Title of Invention	METHOD OF MAKING A LITHOGRAPHIC PRINTING PLATE
Abstract	A method for making a lithographic printing plate is disclosed which comprises the steps of : (1) providing a heat-sensitive lithographic printing plate precursor comprising on a support having a hydrophilic surface or which is provided with a hydrophilic layer, a heat- sensitive coating, (2) image-wise exposing said precursor with IR-radiation or heat, and (3) developing said image-wise exposed precursor with an alkaline developing solution comprising a compound having at least two onium groups . According to the above method, a printing plate is formed with an improved developing latitude or an improved exposure latitude.

Title of Invention

METHOD OF MAKING A LITHOGRAPHIC PRINTING PLATE

Abstract

A method for making a lithographic printing plate is disclosed which comprises the steps of : (1) providing a heat-sensitive lithographic printing plate precursor comprising on a support having a hydrophilic surface or which is provided with a hydrophilic layer, a heat- sensitive coating, (2) image-wise exposing said precursor with IR-radiation or heat, and (3) developing said image-wise exposed precursor with an alkaline developing solution comprising a compound having at least two onium groups . According to the above method, a printing plate is formed with an improved developing latitude or an improved exposure latitude.

Full Text	METHOD FOR MAKING A LITHOGRAPHIC PRINTING PLATE [DESCRIPTION] FIELD OF THE INVENTION The present invention relates to a method for making a lithographic printing plate wherein an image-wise exposed precursor is developed with an alkaline developing solution comprising a compound having at least two onium groups. The present invention relates also to an alkaline developing solution and to a replenishing solution comprising said compound having at least two onium groups. The present invention relates also to a lithographic printing plate precursor wherein the coating comprises said compound having at least two onium groups. BACKGROUND OF THE INVENTION Lithographic printing typically involves the use of a so-called printing master such as a printing plate which is mounted on a cylinder of a rotary printing press. The roaster carries a lithographic image on its surface and a print is obtained by applying ink to said image and then transferring the ink from the master onto a receiver material, which is typically paper. In conventional lithographic printing, ink as well as an aqueous fountain solution (also called dampening liquid) are supplied to the lithographic image which consists of oleophilic {or hydrophobic, i.e. ink-accepting, water-repelling) areas as well as hydrophiiic for oleophobic, i.e. water-accepting, ink-repelling) areas. In so- calied driographic printing, the lithographic image consists of ink- accepting and ink-abhesive {ink-repelling) areas and during driographic printing, only ink is supplied to the master. Printing masters are generally obtained by the iinage-wise exposure and processing of an imaging material called plate precursor. A typical positive-working plate precursor comprises a hydrophiiic support and an oleophilic coating which is not readily soluble in an aqueous alkaline developer in the non-exposed state and becomes soluble in the developer after exposure to radiation. In addition to the well known photosensitive imaging materials which are suitable for UV contact exposure through a film mask (the so- called pre-sensitized plates), also heat-sensitive printing plate precursors have become very popular. Such thermal materials offer the advantage of daylight stability and are especially used in the -called cor;pj-er-to-plate m.ethod (CtP) wherein the elate precurso^i.^ is directly exposed, i.e. without the use of a film mask. The rr.aterial is exposed to heat or tc infrared light and the generated heat triggers a (physico-)chemical process, such as ablation, polymerization, insolubilization by cross-linking of a polymer or by parti cl e coagulation of a therm.oplastic polymer latex, and solubi]ization by the destruction of intermolecular interactions or by increasing the penetrability of a development barrier layer. Although some of these thermal processes enable plate rriaking without, wet processing, the miost popular thermal plates form an image by a heat-induced solubility difference in an alkaline developer between exposed and non-exposed areas of the coating. The coating typically comprises an oleophilic binder, e.g. a phenolic resin, of which the rate of dissolution in the developer is either reduced (negative working) or increased (positive working) by the image-wise exposure. During processing, the solubility differential leads ro the removal of the non-image (non-printing) areas of the coating, thereby revealing the hydrophilic support, while the image iprinring) areas of the coating remain on the support. Typically, for a positive-working thermal plate, a dissolution inhibitor is added to a phenolic resin as binder whereby the rate of dissolution of the coating is reduced. Upon heating, this reduced rate of oissolution of the coating is increased on the exposed areas compared with the non-exposed areas, resulting in a sufficient difference in solubility of the coating after image-wise recording by heat or IR-radiation. Many different dissolution inhibitors are known and disclosed in the literature, such as organic compounds having an aromatic group and a hydrogen bonding site or polymers or surfactants comprising siloxane or fluoroalkyl units. The known heat-sensitive printing plate precursors typically comprise a hydroiohilic support and a coating which is alkali-soluble in exposed areas [positive worxing material; or in non-exposed areas inegaoive working m.aterial) and an IR-absorbing compound. Such coating typically comprises an oleophilic polymer which may be a ohenolic resin such as novolac, resol or a polyvinylphenolic resin. The phienclic resin can be chemically modified whereby the phenolic .Tionomeri c ur.i t is substi tuted by £ group such as described in WO&9/01795, EP 934 822, EP 1 C72 432, US 3,929,486, EP 2 102 443, EP 2 1C2 44^, EP 2 102 445, EP 2 102 446. The phenolic resin can also oeen laixsd v;it.h other polymers such as an acidic pclyvinyi acetal as described in WC2004/020484 or a copolymer comprising sulfonamide groups as described in US 6,143,454. The use of other pclymeric tinders in lithographic printing plates are described in VJC2001/09682, EP 933 682, WO99/63407, W02002753626, EP 1 433 594 and E? 1 439 058. The positive-working thermal plate may further comprise, between the heat-sensitive recording layer and the support, an intermediate layer comprising an alkali soluble resin. This intermediate layer can improve the chemical resistance of ^he plate against press chemicals. This layer induces an improved removing of the coating on the exposed areas. Typical examples of positive- working thermal plate materials having such a two layer structure are described in e.g. EP 864420, EP 909657, EP-A 1011970, EP-A 1263590, EP-A 1268660, EP-A 1D72432, EP-A 1120246, EP-A 1303399, EP- A 1311394, EP-A 1211065, EP-A 1368413, EP-A 1241003,EF-A 1299238, E?-A 12 62318, EP-A 1275498, EP-A 1291172, W02003/74287, WG2004/33206, EP-A 14 33594 and EP-A 14 39058. However, in the non- exposed areas of these plates the resistance of the coating for the alkaline developer is poor whereby the difference in dissolution rate oetween the exposed and non-exposed areas is insufficient, i.e. the non-exposed areas are partially affected by the developer before ihe exposed areas are completely dissolved in the developer. As a result, it is difficult to form highly sharp and clear images, particularly highlights, i.e. fine images comprising a dot pattern or fine lines, are difficult to be reproduced. In a high quality plate it is advantageous that such highlights can be reproduced within a sufficient developing latitude, i.e. small fluctuations in developing time does not substantially affect the image formed on the plates and this developing latitude is obtained when the difference in dissolution rate is improved. EP 1 J 82 512 discloses an alkaline developing solution comprising an amphoteric or cationic surfactant for development of an infrared radiation-presensitized plate. EP 1 400 856 discloses a method for making a lithographic printing plats whereby the exposed precursor is developed with an alkaline developing solution conprising a car ionic sur f acranr. or a compound having three or more ethylene oxide-rerminal groups in the molecule tnereof. EF 1 211 055 discloses 5 posirive-working heat-sensitive print:i ng pi are precursor wherein the recording layer comprises an organic quaternary ainmonium. salt. Tne printing plates of the prior art suffer from an insufficient developing latitude. SUMMARY OF THE INVENTION It is therefore an aspect of the present invention to provide a method for making a heat-sensirive lithographic printing plate whereby excellent printing properties are obtained and whereby the developing latitude or exposure latitude are improved. This object is realized by the method defined in claim 1, having the characteristic feature that the developing solution in the developing step comprises a coiripound having at least two oniuru groups. This compound, hereinafter also referred to as 'blocking agenr", which is capable of reducing the solubility of the alkaline soluble resin of the coating of a positive-working heat-sensitive printing plate precursor whereby the resistance of the coating in the non-exposed areas against the alkaline developer is increased, is present in the precursor and/or in an alkaline developing solution or replenishing solution. By use of compounds mentioned in the prior art documents EP 1 182 512, EP 1 400 856 and EP 1 211 065 an insufficient developing latitude is obtained. Therefore, the inverters have found this new compound which is capable of improving the resistance of the coating in the non-exposed areas against the alkaline developer and capable of improving the developing latitude or the exposure latitude. Other specific embodiments of the invention are defined in the dependent clainis. DETAILED DESCRIPTION OF THE INVENTION In accordance with the present invention, there is provided a method for making a lithographic printing plate comprising the steps ' 1) providing a heat-sensitive iiizhographic printing pi are precursor comprising on a support having a nydrophiiic surface or v/hich is provided a hydrophilic ^ayer, a near-sensitive coating, IjT,age-wise exposing said precursor wirh IR-raaiarion or iieat, and '3; developing said image-wise exposed precursor wirh an aixaiine developing sclution comprising a compound having ar least two onium groups. In a preferred embodiment of rhe present invention, said oo^mpound having at least two onium groups has a structure according to fornijla I / \ -Q- d \ / L' Z' (iormula 1 wherein Q is a divalent group Q when e and f are 0, a trivalent group Q" 4 when the sum of e and f is 1, or a tetravalent group Q when e and f are borh 1, Z^ to Z" independently are onium groups, L'" to L^ independently are divalent linking groups, and a, b, c, d, e and f independenrly are 0 or 1, preferably a, b, c and d are 1 . Ir_ another preferred embodiinent of the present invention, said compound having at least two onium groups has a structure according Z"" and z'^ independently are cnium croups, Ii"' is s divalent linking group, -7"-L"~ represents a repeating unit wherein Z^ and L"'' represent respectively a divalent oniuiri group and a divalent linking group for each x-value, and X is 0, 1 or an integer >1, more preferably x is an integer ranging between 1 and 50, most preferably between 1 and 10. In a more preferred embodiment of the present invention, said compound having at least two oniuni groups has a structure according to formula III Z^-L-Z^', (formula 111) wherein L is a divalent linking group, and Z"' and z"^ independently are onium groups. The divalent linking groups L^ to l"^, each L^' and L in the compounds of formula I, II and III are preferably selected from the group consisting of a linear, branched or cyclic alkylene group such as a methylene, ethylene, propylene, butylene group, c-hexylene or 1-methyl-ethylene; an arylene group such as a phenylene, naphtalene or an heteroarylene group; an arylene-alkylene group sucri as benzylidene group; a bis-alkylene aromatic hydrocarbon group such as o-, p- or m-bis-methylene benzene group; an oxy-alkylene group such ss methylene oxide, ethylene oxide or propylene oxide group; an oxy- arylene cr oxy-heteroarylene group such as phenylene oxide; or a combination of two or more of these groups. Each of these alkylene or arylene groups can be substituted. The linking group of the present invention is composed of at least one of these groups. In a preferred embodiment, the linking group is composed of one or two of these groups which are repeated for at least two times, more preferably for a number ranging between 2 and 15, most pre-i'erably between 3 and 8. The linking group of the present invention can also be composed of r.wo, three or more sequences or these groups whererr. each sequence contains at lease cwo or more of these groups. Examples cf a divalent linking group are -'CH^.-, - ; - (CH-j - (CH-i - ;CH-CH;)-c-C.rHio", - : - , - 'CH; ; - {CfH4} - , - (CH;) - (CeHa; - (CK2J - , -0- (CH2; -, -c- (CH:; - ■ CH.^ ) -, -0- 'CH;) - (CH~CH3) - ^CeHj : - ;CgH4) -O- !CfH4) - , " (CH-) - (CH-) - J-0- (CHjJ - (CH-) -1- -, wherein P"^ and r'^ are indepenaently hydrogen or an optionaJly substituted alkyl cr aryl group; n is an integer ranging between 2 and 15, preferably between 5 and 10, m is an integer ranging between i ana 15, preferably between 3 and 10, 0'" is a divalent group, preferably selected from the group consisting of the divalent linking groups as defined above, '■J Q" is a trivalent group, preferably selected from the group consisting of -CR' each of > and R', R" and R'" are hydrogen or an optionaly substituted alkyl, aryl or aialkyl group, L', L" and L"' are a divalent linking, preferably selected from the group consisting of the divalent linking groups as defined above, and p, q and r independently are 0 or 1, is a tetravalent group, preferably selected from the list of tne following groups: >C XCeH.X, CeH-{-(L' ) p-) (-(L") q-) (-(L'" ) r-) s") ' [>N wherein each of > and L' , L" and L'" are a divalent linking, preferably selected from the grout consisting of the divalent linking groups as defined above, and p, q, r and s independently are 0 or preferably . Tne onium croups Z^ to Z" and Z" in the compounds or lorraula I, :T anc III are positively charged groups and preferably selected f roiT; cne group consisting of prrmary amine salts, secondary arr.ine sales, tertiary amine salts, quaternary aminonium salts, phosphoniun/ salts or su 1;;J']oniurn salts. The onium groups Z"" to Z'^ are more preferably selected from the groups consisting of one of the following structures: P/ 'N X R' _ 1 W R R" N R" R" R- p- p R wherein * denotes rhe binding site of the onium group with one site of the d i V a 1 e ri t linking group; Z represents oxygen, sulfur or -NR'^-; 1 each of R to R^ groups are independently hydrogen; an optionally substituted alkyl, alkylene, aryl or aralkyl group such as methyl, ethyl, propyl, butyl, propenyl, butenyl, phenyl or benzyl; a halogen atom such as bromide or chloride; -CN; -NO2; an oxy-alkyl or oxy- aryl group; a thio-alkyl or thio-aryl group; an amide or sulphonamide group; a carboxylic acid or salt or alkyl estor group; a sulphonic acid or salt or alP:yl ester group,- a sulphonalkyl or sulphonaryl group; an amino group; or whereby two groups of the R^ to R" groups together comprise the necessary atoms to form a cyclic structure, preferably a 5- or 6-meinberd xing; 6 S each of R to R groups are independently hydrogen; an optionally substituted alkyl, alkylene, aryl or aralkyl group such as methyl, ethyl, propyl, butyl, propenyl^ butenyl, phenyl or benzyl; a carboxylic acid or salt or alkyl ester group; or whereby two groups of the r"^ to R® groups together comprise the necessary atoms to form a cyclic structure, preferably a 5- or 6~memberd ring. Each of the onium groups Z^" in the compounds of formula 11 are positively charged groups having two binding sites, i.e. divalent, and more preferably selected from the list of the onium groups as above wherein one of the R^ to R^ groups is not present and is replaced by indicating the second binding site. In order to obtain electrically neutrality, one or more anions are present as counterion. Examples of such counterions are cnlor 1 de, brorr.i de, iodide, or a compound comprising at least one of the follov;ina anionic groups: a sulphonate, sulphate, carboxylate, phosphate or phosphonate anion, or wherein the sulphonate, sulphate, r,5rboxylate, phosphate or phosphonace anion is part of one of the substituting groups R^ to R" of "he onium group as defined above. Preferred counter ions are broiriide, chloride, methyl sulphonate or The onruni groups Z to Z" in the compounds of formula I have preferably the same structure. The or.ium groups Z^ and Z'^ in the compounds of formula II, have preferably the same structure. All the Z^' groups rn the oompounds of formula II, have preferably the same structure. The onium groups Z® and Z^ in the compounds of formula III, have preferably the same structure. 7 CI Ci Examples of blocking agents of the present invention are CI CI B]ock-02: N- -N. 3lock-03 : B1ock-06: Elock-07: > \ &1ock-0 Elock-09' ^N \W CI N N, N, E1 o c "f^ - ] 0 During developing of an image-wise exposed heat-sensitive lithographic printing plate precursor, the blocking agent of the present invention is present in the aqueous alkaline developing solution. In accordance with a preferred embodiment of the present invention, the blocking agent of rhe present invention is present in 'he alkaline developing solution at the start of the developing process. Br Bi r;iocf:-l 1; In accordance with another preferred Gmbodiment of the present invention, The blocking agent is added to the alkaline developing solution during the developing process, preferably as a solution or cii.=;pe:-.=;ion. ir: a more preferred embodiment, the blocking aqent is added t.o the alkaline developing solution by the addition of a leplenishinq solution comprising ^he blocking agent during the oeveioping process. In accordance with another preferred embodimenc oi the present invancion, che blocking agent is added to the alkaline developing solution during the developing process by removing at least part of the precursor comprising the blocking agent. The biockinc agent can oe present in the heat-sensitive coating, an intermediate layer between the support and the heat-sensitive coating, a top layer ind/or a layer on the back side cf the plate. Developing solution The aqueous alkaline developing soluti®n (hereinafter also referred to as "developer") may comprise an alkaline agent. The composition of said aqueous alkaline solution can be selected from conventional alkaline developers, The aqueous alkaline developing solution of the present invention has preferably a pH value of at least 10, more preferably of at least 11.5, most preferably of at least 12. There is no specific upper limit for the pH but the pH is usually not higher chan 14 . The alkaline agent includes inorganic alkaline agents such as sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium zertiary phosphate, potassium tertiary phosphate, ammonium tertiary phosphate, sodium secondary phosphate, potassium secondary phosphate, aminonium secondary phosphate, sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium borate, potassium borate and ammonium borate, and potassium citrate, sodium citrate and the Mke. The alkaline agent may also include organic alkaline agents such as monomethylamine, dimethylam.ine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisoDropvls:[^.ine, triisopropylamine, n-butylamine, monoethanolamine, diethanolami ne, triethanolairiine, monoisopropanolamdne, diiscpropanoiamine, ethylenediamine, pyridine and the like. The alkaline aqueous soluzion may also Include an alkaline silicate. The alkaline silicate may be those exhibiting an alkalinity '/;nen dissolved in water, and examples thereof include an ?.lkali metal silicate and alkali metal ine-asilicate such as sodium silicate, sodium nietasilicate, potassium silicate and lithiuir! silicate, and anmioniuni silicate. Said alkaline silicate mav be used,,,. =:lc;ne, or ir. combination. The devalopment performance of the alkaline aqueous solution" iiiay be easilv moaulated by adjuscing a molar ratio of alkaline siiicaces and alkali metal hydroxides, represented by sij icon oxide iSiO;;.'; and an alkali oxide (M2C, wherein M represents an alkali inetal or an arpinonium. group) . The alkaline aqueous solution has preferably a mciar ratio Si02/M20 from 0.;. to 3.0, and more preferably from 1.0 tc 2.0. When the molar ratio Si02/M20 is less than 0.5, alkalinity of the solution strengthens so as to cause a harmful effect such as etching of an aluminum plate w.hich is generally used as a substrate in a lithographic printing plare precursor. When the molar ratio, 3i02/M20 is more than 3.0, the development performance of the solution may be degraded. The concentration of alkaline silicate in the developer ranges generally from 1 to 14% by weight, preferably from 3 to 14% by weight, and more preferably from 4 to 14% by weight. When said concentration is less than 1% by weight, the development performance or treatment capacity may be degraded. When said concentration is more chan 14% by weight, precipitared materials or crystals may be easily generated, and gelation may be easily caused during neutraJization of waste liquid, resulting in an obstacle to the ■waste disposal. The developer based on an alkaline aqueous solution may also comprise a nonreducing sugar. The nonreducing sugar denotes sugars having no reductive property due to the absence of a free aldehyde group or a free ketone group. Said nonreducing sugar is classified into trehalcse-type oligosaccharides wherein a reductive group and another reductive group make a linkage; glycosides wherein a reductive group in a sugar is linked to a non-sugar compound; and sugar alcohols which are produced by reducing a sugar by nvarog&nation. Said trehalose-zype oligosaccharides include sucrose and trehalose, and said glycosides include alkyl glycosides, phenol glycosides, mustard oil glycosides and the like. Said sugar alcohols incluoe D, I.-arabitol, ribitol, xylitol, D, L-sorbitol, D, L-mannitol, :;,I-;dicol, talitol, dulcitol, allodulcitol and the like. Further, malticol obtained by hydrogenacion of disaccharide, a reduced !T,£-eriai obtained by hydroger.at.ion cf oligosaccharide (a reduced 5zarch syrup? and the like are preferably used. In rhe abov^e ^ nonreducing sugar, preferred are sugar alcohols and sucrose, and particularly preferred are D-sorbicol, sucrose and a reduced starch syrup, since they have buffering action in appropriate pH range. "he above nonreducing sugar rr.ay be used alone or in combination v.'ith other ingredients, and the concentration thereof in the developer ranges generally frorr, 0.1 to 30% by weight, and preferably from 1 to by weight. In the developer, an alkaline agent may be used as a base in combination with the above mentioned alkaline silicate or nonreducing sugar, and said alkaline agent may be selected from sodium hydroxide and potassium hydroxide. Further, sodium tertiary phosphate, potassium tertiary phosphate, sodium carbonate and potassium carbonate are also preferable, since they have themselves, buffering action. The above alkaline agent may be used alone or in combination. The developer may optionally contain further components, such as buffer substances, complexing agents, antifoaming agents, organic solvents, antisludge agent, corrosion inhibitors, dyes, surfactants and/or hydrotropic agents as known in the art. In the aqueous alkaline developing solution, it is possible to sirnui taneously use organic solvents having solubility in water at 20 "C of not more than 15 % by weight according to need. Examples of such organic solvents are such carboxilic acid esters as ethyl acetate, propyl acetate, butyl acetate, amyl acetate, benzyl acetate, ethylene glycol monobutyl ether acetate, butyl lactate and butyl levulinate; such ketones as ethyl butyl ketone, methyl isobutyl ketone and cyclohexanone; such alcohols as ethylene glycol monobutyl ether, ethylene glycol benzyl ether, ethylene glycol monophenyl ether, benzyl alcohol, methylphenylcarbitol, n-amyl a'cohoJ snd .nethylamyl alcohol; such alkyl-substituted aromatic hydrocarbons as xylene; and such halogenated hydrocarbons as methyJ.ene cichloride and monochlorobenzene. These organic solvents may be used alone or in combination. Particularly preferred is r-er.zvl alcohol in the invention. Ihese oraanic solvents are added tc ^he developer or replenisher therefor generally in an amount of not mo.-9 than 10 % by weight and preferably not more than 5 I ■ Besides the components described above, the developing solution cf the present invention comprises a non-ionic surf^ctanr.. Such a non-ionic surfactant may be used as a dissolution preventing agent whereby undercutting of non-expossd areas is reduced. Examples of nonion], c surfactants include echoKviated alcohols^ polyethylene glycols and polyhydric alcohols. Ethoxylated alcohols are preferred, and in particular ethoxylated alcohols having a hydrophilic- lipophilic balance (HLB) higher than 5 are more preferred. Specific examples of nonionic surfactants are listed below; polyethylene glycol, polyoxyethylene lauryl ether, laurylalcchol polyglycol ethers, oleyl alcohol ethoxylaced, lanolin alcohol ethoxylated, dodecanol ethoxylated, cetostearyl alcohol ethoxylated, tetramethyldecindiol ethoxylated, polyoxyethylene nonyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene behenyi ether, polyoxyethylene polyoxypropylene block copolymers, polyoxyethylene polyoxypropylene cetyl ether, polyoxyethylene polyoxypropylene beheryi ether, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene stearylamine, polyoxyethylene ol eylarr.ine, polyoxyethylene stearic acid amide, polyoxyethylene oleic acid arrdde, polyoxyethylene castor oil, polyoxyethylene acietyl ether, polyoxyethylene lanolin ether, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene glyceryl monooleate, polyoxyethylene glyceryl monostearate, polyoxyethylene propylene glycol monostearate, polyoxyethylene sorbitan monolaurate, and sorbitan monolaurate. The non-ionic surfactants, which have an ethylene diamine group, substituted with groups of polyoxyethylene, Dolyoxypropylene or mixtures thereof, are of special interest in the developing solution. Examples of such non-ionic surfactants are the TETFONIC surfactans commercially available from BASF. The non-ionic surfactants preferably have an average molecular weight ranging from 500 to 10,000, preferably from 1000 to 5000. They can be comprised individually or as admixture of two or more ':crrtpou:,ds in an amount ranginq from 0.05 to 5S, preferably from O.i TO 1 % by weignt of the total developing solution. The developers used in zhs present invention may simulT:aneoiisl'- another surfactant for the purpose of improving dev'eloping propei'T-ies thereof. By incorporating surfactants to the developer solution, the surface tension reduces drastically and the developer, so]ution becomes effective - i.e. removal of the non-imaqe areas wit-hc'it occur rence of stain/toning ~ at a lower pH compared co ~he same oeveloper solution wirhour a surfactant. The developer may comprise an ionic surfactant such as anionic or cationic surfactant, non-ionic surfactant and/or arr.photeric surfactants such as Librateric AJv30 (trademark from Libra Chemicals Limited). Examples of Such surfactants include salts of higher alcohol (C8 - C22) sulfuric acid esters such as sodium salt of lauryl alcohol sulfate, sodium salt of octyl alcohol surface, ammonium salt of lauryl alcohol sulfate, Teepol B-81 (trade mark, available from Shell Chemicals Co., Ltd.) and sodium alkyl sulfates; salts of aliphatic alcohol phosphoric acid esters such as sodium salt of cetyl alcohol phosphate; alkyl aryl sulfonic acid salts such as sodium salt of aodecylbenzene sulfonate, sodium salt of isopropylnaphthalene sulfonate,sodium salt of dinaphthalene disulfonate and sodium salt of metanitrobenzene sulfonate; sulfonic acid salts of aikylamides such as Ci7.n33CON (CH3) CH2CH2S03Kia and sulfonic acid salts of dibasic aliphatic acid esters such as sodium dioctyl sulfosuccinate and sodium dihexyl sulfosuccinate, These surfactants may be used alone or in combination. Particulariy preferred are sulfonic acid salts. These surfactants may be used in an amount of generally not more than 5 % by weight and preferably nor more than 3 % by weight. The cationic surfactant used in the developer may include amine salts, quaternary ammonium salts, phosphoniLiin salts, suifo.nium salts and the like. Examples of the am.ine salts are primary amine salts, secondary am.ine salts, tertiary amine salts, and imidazoline salts. Examples of the quaternary ammonium salts include tetraalkyl quaternary ammonium salts, trialkyl benzyl quaternary ammonium saits, aikyl pyridinium salts, alJiyl quinolinium salts^ irr.idazcliniurr. salts and benzim.idazolinium salts. Exemplary amphoteric surfactants include betaine derivatives, such as, for example, alkylamidopropyl betaine, alkyldimetny1 Detaine, bisnydroxyethyl betaine, alkylamido propyl betaine, lauryl betaine, and rhe 11ke, glycine derivatives, such as, for example, cocoarr.chccarbcxy glycinate, lauroaniphocarboxy glycinate, caprylamphocarboxy glycinate, oieoamphocarboxy glycinate, oleoamphopolycarboxy glycxnate, N-aikyl glycinate, and the 1 ike, imino derivatives, such as, tor example, cocoiminodipropionate, octyliminod:! propionate, and the li ke, imidazoline derivatives , such as, fcr example, coconut imiaazoline, and the like, lecithin derivatives, and arcinocarboxylic acids. These amphoreric surfactants pieferably nave an average molecular weight ranging from ICO r.o 10,000, preferably from 1,000 to 5,000. They can be comprised individually or as admixture of two or more compounds. The above described anionic and amphoteric surfactant can be present in the developing solution of the present invention in a total ainount ranging from 0>5 to 101, preferably from 1 to 6%, and more preferably from 1 to 3% oy weight of the total developing solution. In order to enhance developing stability of the developers, the following compounds may simultaneously be used. Examples of such compounds are neutral salts such as NaCl, KCl and KBr as disclosed in JN'A- 53- 75 152; chelating agents such as EDTA and NTA as disclosed in JN-A- 58- 190 952 (U.S-A- 4 469 776), complexes such as [Co (NH. j ,„]C1, as aisclosed in JK-A- 59- 121 336 {US-A-- 4 606 995); lonizable compounds of elements of the group Ila, Ilia or Illb of ■Lhe Periodic Table such as those disclosed in JK-A- 55- 25 100; anionic or amphoteric surfactants such as sodium alkyl naphthalene sulfonate and K-tetradecyl-N,N-dihydroxyethyl betaine as disclosed in JN-A- 50- 51 324; tetramethyldecyne diol as disclosed in US-A- A 374 920; non-ionic surfactants as disclosed in JK-A- 60- 213 94 3; cationic polymers such as methyl chloride quaternary products of p-dimethylaminomethyl polystyrene as disclosed in JN-A- 55- 95 546; amphoteric polyelectroiytes such as coDolyrr.er of vinylbenzyl trimethylammonium chloride and sodium acrylate as disclosed in JN-A- 56- 142 528; reducing inorganic salts such as sodium sulfite as disclosed in JN-A- 57- 192 952 fOS-A- 4 4 67 02 7) and alkaline-soluble m.ercapto com.pounds or thioether compounds such as thiosalicylic acid, cysteine and chioqlycolic acid; inorganic lithium compounds such as lithium chloride as disclosed in JN-A- 56- 59 444; organic lithiumi compounds sv.ch as lichiuir, benzoate as disclosed in JN-A- 50 34 442 ; Dtganometallic surfactants concaining Si, Ti or the like as disclosed in JN-A.- 59- "^5 25 5; organoboron com.pounds as disclosed in JN-A- 55- 84 241 (US-A- 4 500 525); quaternary ammonium salts such 23 tstraaikyiammonium oxides as disclosed in EP-A- ICl CIO; and bac-.sricides such as sodium dahydroacetate as disclosed in JN-A- 63- 226 657. In a preferred embodiment of rhe present invention, the ^Tilocking agent is present in a developing solution at a concentration of at least 0.02 g/1, preferably in a concentration ranging between 0.05 and 30 g/1, rriore preferably between 0.05 and 15 g/1, more preferably between 0.0 5 and 5 g/i, most preferably between 0.1 and 1 g/1. Replenishing solution During the development the non-image areas of the coating are removed with an aqueous alkaline developer solution optionally in combination combined with mechanical rubbing, e.g. by a rotating brush. During the development step, any water-soluble layer present is preferably also removed- The development is preferably carried out at temperatures of from 20 to 40 °C in automated processing units as customary in the art. To perforrri development processing stably for a long time period, it is particularly important to control the strength of elkaii and the concentration of silicates and other ingredients in the developer. Therefore, a replenishing solution, hereinafter also referred to as replenisher, is added to the developing solution, usually in small amounts such that a stable development processing can be performed over a long time period without exchanging the developer. Therefore, it is also important that the concentration of the blocking agent of the present invention is present in the developing solution at a sufficiently high level in order to maintain the developing latitude or exposure latitude of the precursor and this can be realised by adding a replenishing solution comprising the blocking agent of the present invention. For regeneration, the replenishing solution, hereinafter also referred to as repienisher, preferably comprises active ingredients of the developing solution such as alkaline agent. The replenishing solution is added continuously or in small amounts to the developing solution auring or after the aeveloping process in order to regulate r ne coricen-.ration of the active ingredients in the developing soion ar a level sufficient.ly high or at a constant level such -„hat "he development of image-wise exposed precursors remains at a constant level. The required amcunts of regenerated rriaterisl must be zailoreG to tne developing apparatuses used, daily plate T.r.rovghpuzs, image areas, ezc. and are in general from 1 to i5C ml per square neter of plate precursor. The aadition of replerilsher can be regulatea, for example, by measuring the conductiviry of the developer as described in EP-A 0,556,690 . In the method for development processing, any known means of suppJ eraenting a replenisher for developer may also be employed. ^'xamples cf sach methods preferably ased are a method for interjrattently or continuously supplementing a replenisher as a function of the amount of plates processed and time as disclosed in JN-A- 56- 115 039 (GB-A- 2 046 931), a method comprising disposing a sensor for detecting the degree of light-sensitive layer dissolved out in the middle portion of a developing zone and supplementing the replenisher in proportion to the detected degree of the light- sensitive layer dissolved out as disclosed in JN-A- 58- 95 349 I'US-A- 4 537 496) ; a method comprising determining the impedance value of a developer and processing the detected Impedance value by a computer to perform supplementation of a replenisher as disclosed in GB-A- 2 2 08 2 49. In a preferred embodiment of the present invention, the blocking agent is present in a replenishing solution at a concentration of at least 0.05 g/1, preferably in a concentration ranging between 0.1 and 30 g/1, more preferably between 0.5 and 20 g/l, more preferably between 0.5 and 15 g/1, most preferably between 0.5 and 10 g/1. In another preferred embodiment, the ratio of the concentration of the blocking agent in the replenishing solution, containing at least 0.05 g/1 of the blocking agent, and in the developing solution is preferably between 0.5 and 100, more preferably between 1.1 and lOO, most preferably between 2 and 50. The replenishing solution has preferably a pH value of at least 10, more preferably of at least 11.5, most preferably of a- least 12. There is no specific upper limit for the pH but the pH is usually rot higher than 14. In anc'her embodiment of the present invention, more than one replenishing .polutions can be used for adding to the developing solution during or after the development processing and these rspier.ishers may contain aifferenr types in different amoun-cs of blocking agents of the presen- invention, and also different types in cjifferent amounts of other coinpounds for improving ^he a e51 o p rri e n ^ processing. I'n a mere preferred eiribodiment of the present invention, the fres:^ cieveioping solution at starting the development processing for the first time is essentially free of the blocking agent of the present invention and during or after processing precursors, a replenishing solution, containing a blocking agent of the present invention, is added to the developing solution and/or a layer of the precursor, comprising a blocking agent of the present invention, is removed at least partially in "ne developing solution. The heat-sensitive lithographic printing plate precursor of the present invention comprises a support having a hydrophilic surface or which is provided with a hydrophilic layer, and, on said support, a heat-sens itive coating. Support The support of the lithographic printing plate precursor has a hydrophilic surface or is provided with a hydrophilic layer. The support may fae a sheet-like material such as a plate or it may be a cylindiical element such as a sleeve which can be slid around a print cylinder of a printing press. A preferred support is a metal support such as aluminum or stainless steel. The metal can also be laminated to a plastic layer, e.g. polyester film. h particularly preferred lithographic support is an electrochemically grained and anodized aluminum support. Graining and anodization of aluminum is well known in the art. The anodized aluminum support may be treated to improve the hydrophilic roperties of its surface. For example, the aluminum support may he siiicated by treating its surface with a sodium silicate solution at Isva^-C-d temperature, e.g. 9 5°C. Alternatively, a phosphate treatment may be applied which involves treating the aluminum oxide surface with a phosphate solution that may further contain an inorganic fluoride. Further, the aluminum oxide surface miay be rinsed with a citric acid or citrate solution. This treatment may be carried out at room temperature or may be carried out at a slightly elevat-Sd temperature or about 30 to SCc. A further interesting treatment involves rirising the aluminum o^cide surface v.'i th a Dicaroonate solution. Still further, the aluminum oxide surfa'::= may be treated with polyvinylphosphonic acici, polyv Lnyirrietrjvlphosphonic acid, phosphoric acid esters of polyvinyl .7 Coating The heat-sensitive coating, which is provided on the support, may be positive-working or negative-working. A positive-working hsat-sensitive coating is preferred. The coating of a positive- rt-or king hear.-sensitive coating does not dissolve in an alkaline developing solution in the unexposed areas and becomes soluble in the exposed areas within the time used for developing the plate. The coating preferably comprises an infrared absorbing agent and an alkaline soluble oleophilic resin whereof the solubility in an alkaline developing solution is reduced in the coating and whereof the solubility in an alkaline developing solution is increased upon heating or lP-.-radiatiDn. The coating preferably further comprises a dissolution inhibitor whereby rate of dissolution in an alkaline developing solution is reduced. Due to this solubility differential the rate of dissolution of the exposed areas is sufficiently higher than in the non-exposed areas. In a preferred emibodiment of the present invention, the heat- .=;ensicive coating comprises a first polymer which is a phenolic resin such as novolac, resol or a polyvinylphenolic resin; novolac is nor? preferred. Typical examples of such polymers are described in DE-A-400742S, DE-A-40273C1 and DE-A-4445820. Other preferred poJ ymers are phenolic resins v-.'terein the phenyl group or the hydrox}' group of the phenolic monomeric unit are chem.ically modified with an organic substituer.t as described in EP 894 622, EP 901 9C2, EF 953 662, W099/63407, EP 934 822, EP 1 072 432, US 5,641,608, EP 9B2 123, WOC4/035310, W004/0356S6, W004/035 64 5, WOO'3/C35687 or EP ] 50c' 58 . The novclac resin or rssol resin may be prepared by po j.ycondens.?,T; on oi ar leasr one meraber selected from aronatic hydrocarbons such as phenol, o-cresol, p-cresol, m-eresol, 2,5- xylenol, 3,5-xylenol, resorcinol, pyrogallol, bisphenol, Disphenol A, rri sphenol, o-ethylphenoi, p-etylphenol, propylphenol, n- butylphenol, t-butylphenol, octyl-phenol, 1-naphtol and 2-naphtol, v.'irh ar least one aldehyde or Ketone selected from aldehydes such as formaldehyde, glyoxai, acetoaldehyde, propionaldehyde, benzaldehyde and furfural and ketones such as acetone^ methyl ethyl ketone and methyl isobutyl ketone, in the presence of an acid catalyst. Instead of formaldehyde and acetaldehyde, paraformaldehyde and paraldehyde may, respectively, be used. The weight average molecular weight, measured by gel permeation chromatography using universal calibration and polystyrene standards, of the novolac resin is preferably from 500 to 150,000 cj/'reol, more preferably from 1,500 to 50,000 g/mol. The poly(vinylphenol) resin may also be a polymer of one or more hydroxy-phenyl containing monomers such as hydroxystyrenes or hydroxy-phenyl (meth)acrylates, Examples of such hydroxystyrenes are o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, 2-(o- hydroxyphenyJipropylene, 2-(m-hydroxyphenyl)propylene and 2~(p- hydroxyphenyi)propylene. Such a hydroxystyrene may have a substituent such as chlorine, brorr.ine, iodine, fluorine or a C1-4 alkyl group, on its aromatic ring. An example of such hydroxy-phenyl (methiacrylate is 2-hydroxy-ph6nyl methacrylate, Tne poly(vinylphenol) resin may usually be prepared by polvrr.erizing one or more hydroxy-phenyl containing monomer in the presence of a radical initiator or a cationic polymerization initiator. The poly [vinylphenol) resin may also be prepared by copolymerizing one or more of these hydroxy-phenyl containing monomers with other monomeric compounds such as acrylate monomers, msthacrylate inonomers, acrylamide monomers, methacrylamide monomers, vinyl monom.ers, aromatic vinyl monomers or diene monomers. The weight average molecular weighr, measured by gel permeation chrorr.ar.ography using universal calibration and polystyrene standards , of the poly (vinyl phenol) resin is preferably from 1. 'inn 2CC', 000 g/rrrol, more preferably from 1,500 to 50,000 g/iriol, Examples of phenolic resins are: POL-CI: AlKOVOL SPN4 52 is a sclution of a novolac resin, 4 0 s oy weight in Dowanoi PM, obtained from CLARIANT GmbH. Dowanoi PM consists of l-merhoxy-2-propanol (>99.5 %) and 2~methoxy- 1-propanol ( POL-02: ALNOVOL SPN400 is a solution of a novolac resin, 44 % by weight in Dowanoi PMA, obtained from CLARIANT GmbH. Dowanoi PMA consists of 2-methoxy-l-methyl-ethylacetate. POL-03: ALMOVOL HPKIOO a novolac resin obtained from CLARIANT GmbH. ?aL-C4: DORITE PD443 is a novolac resin obtained from BORDEN CHEM. INC. POL-05; DURITE SD423A is a novolac resin obtained from BORDEN CH5M. INC. POL-Og; DURITE SD126A is a novolac resin obtained from BORDEN CHEM. INC. POL-C?: BAKELITE 6866LB02 is a novolac resin obtained from 3AKELITE AG. POL-08: BAKELITE 6866LB03 is a novolac resin obtained from BAKELITE AG. POL-CS; KR 40C/8 is a novolsc resin obtained from, KOYO CHEMICALS POL-10: HRJ 1085 is a novolac resin obtained from SCHNECTADY INTERNATIONAL INC. I.-L-Ij.: H?;!' 2606 is a phenol ncvolac resin obrained froia JCHNECTADY INTERNATIONAL INC. POL-lz: LiNCUR CMM is a copciyraer of 4-hydroxy-styrene and merhvl msthacrylate obtained from SIBER HEGNER. In another preferred embodiment of the present invention, the neat-sensitive coating further comprises a second polymer which is insoluble in v.;ater and soluble in an alkaline solution. Ir: accordance with a more preferred embodiment of che present i nvention, tne heat-sensitive coating comprises a heat-sensitive layer and an intermediate layer. The intermediate layer is present between the heat-sensitive layer and the hydrophilic surface of the support. In a still more preferred embodiment, the heat-sensitive flayer comprises a first polymer and optionally an inhibitor, and the ir.y.er-nediate layer comprises a second polymer. The second polymer is preferably an organic polymer which nas acidic qroups with a pKa of less than 13 to ensure that the layer is s";luble cr at least swellable in aqueous alkaline developers. Advantageously, the binder is a polymer or polycondensate, for example a pcdyester, a polyamide resin, an epoxy resin, an acetal resin, an acrylic resin, a m.ethacrylic resin, a styrene based resin, a polyurethane resin or polyurea. The second polymer has more preferably one or more functional groups selected from the list of ii) a sulfonam.ide group such as -S02-NH-R^ wherein R^ represents a hydrogen cr an optionally subscituted hydrocarbon group such as an optionally substituted alkyl, aryl or heteroaryl group, ;ii) an active imide group such as -SO2-NH-CO-R'', -SO.-NH-SO^-r'' or ■ CT-Nn-SO'/-R" wherein r'"' represents a hydrogen or an optionally substituted hydrocarbon group such as an optionally substicuted alkyl, aryl or heteroaryl group, ■■ i ii a car boxy late group, IIV) a sulfonate group, ;v'; a phcsphonate group, and 'vi) a phosphate group; a su]fonamide group or an active imide group are more preferred; most preferred are poiymers selected from a copolymer comprising a M-benzyl-maleimnde monomeric unio or a monorrieric unit comprising a fcnamide group as descrioed in EP-A 933 682, EP G 894 622 (page to page c line 30!, SP-A G 982 125 (page 3 line 56 to page o I c;.JU .:ne 5:, EP-A 1 072 432 (page 4 line 21 to page IG line WO 99/63407 (page 4 line 13 to page 9 line 37) . O'her polymers having an acidic group are polycondensates and polymers having free phenolic hydroxyl groups, as obtained, for example, by reacting phenol, resorcinol, a cresol, a xylenol or a trimethyiphenol with aldehydes, especially formaldehyde, or ketones. Condensates of sulfamoyl- or carbamcyl-substituted aromatics and aldehydes or ketones are also suitable. Polymers of bismethylol- substiouted ureas, vinyl ethers, vinyl alcohols, vinyl acetals or vinylamides and polymers of phenylacrylates and copolymers of hydroxy-phenylmaleimides are likewise suitable. Furthermore, polymers having units of vinylaromatics, N-aryl(meth)acrylamides or aryl (meth}acrylates may be mentioned, it being possible for each of these units also to have one or more carboxyl groups, phenolic nydroxyl groups, sulfamoyl groups or carbamoyl groups. Specific examples include polymers having units of 2-hydroxypheny1 (meth)acrylate, of N-(4-hydroxyphenyl)(meth)acrylamide, of N-(4- sulfamoylphenyl)-(meth)acrylamide, of N-(4-hydroxy-3,5- dimethylbenzyl)-(meth)acrylamide, or 4~hydroxystyrene or of hydroxyphenylmaleimide. The polymers may additionally contain units of other monomers which have no acidic units. Such units include vinylarorriatics , methyl (meth) acrylate, phenyl (meth) acrylate, benzyl ;rr;eth; acrylate, methacrylamide or acrylonitrile. Dissolution inhibitor Ir. a preferred embodiment of the present invention, the heat- sensitive coating or the heat-sensitive layer also contain one or more dissolution inhibitors. Dissolution inhibitors are compounds which reduce the dissolution rate of the hydrophobic polymer in the aqueous alkaline developer ao the non-exposed areas of the coating and '.'.■he-rein this reduction of the dissolution rate is destroyed by rhe heat generated during the exposure so that the coating readily aissclves in -he developer at exposed areas. The dissolution inhibitor exhibits a substantial latitude in dissolution rate betvjeen the exposed and non-exposed areas. By preference, iihe dissoiULJon inhibitor has a good dissolution rate iati::ude when rhe exposec coating areas have dissolved completely in the developer oefore the non-expcsed areas are attacked by the developer to such an extent tnat the ink-accepting capability of the coating is affected. The dissolution inhibitor (s) can be added to the layer which comprises the hydrophobic poiym.er discussed above. The di ssolution rate of the non-exposed coating in che deve]oper is preferably reduced by interaction between the hydrophobic polymer and the inhibitor, due to e.g. hydrogen bonding between these compounds. Suitable dissolution inhibitors are preferably organic compounds which comprise at least one aromatic group and a hydrogen bonding site, e.g. a carbonyl group, a sulfonyl group, or a nitrogen atom which may be quaternized and which may be part of a heterocyclic ring or which may be part of an amino substituent of said organic compound. Suitable dissolution inhibitors of this type have been disclosed in e.g. EP-A 825 S27 and Water-repellent polymers represent an another type of suitable dissolution inhibitors. Such polymers seem to increase the developer resistance of the coating by repelling the aqueous developer from the coating. The water-repellent polymers can be added to the layer comprising the first polymer and/or can be present in a separate layer provided on top of the layer with the first polymer. In the latter embodiment, the water-repellent polymer forms a barrier layer wnich shields the coating frorr: the developer and the solubility of the barrier layer in the developer or the penetrability of the barrier layer by the developer can be increased by exposure to heat or infrared light, as described in e.g. EP-A S64420, EP-A 950 517 and VJ099/2172 5. Preferred examples of the water-repellent polymers are pclym.ers comprising siloxane and/or perfluoroalkyl units. In one embodiment, the coating contains such a water-repellent polymer in an amount between 0.5 and 25 mg/m^, preferably between 0.5 and 15 2 2 mg/m and most preferably between 0.5 and 10 mg/m , vJhen the water- repel len L polymer is also ink-repelling, e.g. in the case of 2 polysiloxanes, higher amounts than 25 mg/m can result in poor ink- accept ance of the non-exposed areas. An amouni. ^^ower than 0. 5 mg/m^ on cne other hand may lead oo an unsatisfactory development rssi5;tance. The polysiloxane rr.ay tas a linear, cyclic or complex cioss-1inkea polymer or copclymer. The rerm polysiloxane compound shall include any compound which contains more than one siloxane group -SiiR,?';-0-, wherein R ana R' are optionally substiru-ed aikyi or aryi groups. Preferred siloxanes are phenylalkylsiloxanes and dia 1kylsiloxanes. The number of siloxane groups in the ^cojpolymsr is at least 2, preferably at least 10, more preferably at least 20. It may be less than 100, preferably less than 60. In anocher embodiment, the water-repellent polymer is a block-copolymer or a graft-copolymer of a poly(alkylene oxide) block and a block of a polymer comprising siloxane and/or perfluoroalkyl units. A suitable copolymer comprises about 15 to 25 siloxane units and 50 to 70 alkylene oxide groups. Preferred examples include copolymers comprising phenylmethylsiloxane and/or dimethylsiloxane as well as ethylene oxide and/or propylene oxide, such as Tego Glide 410, Tego Wet 265, Tego Protect 5001 or Silikophen P50/X, all commercially availat)le from Tego Chemie/ Essen, Germany. Such a copolymer acts as a surfactant which upon coating, due to its bifunctional structure, autom.atically positions itself at the interface between the coating and air and thereby forms a separate top layer even when the whole c:oating is applied from a single coating solution. Simultaneously, such surfactants act as a spreading agent which improves tne coating quality. Alternatively, the water-repellent polymer can be applied in a second solution, coated on top of the layer comprising the hydrophobic polymer. In that embodiment, it may be advantageous to use a solvent in the second coaring solution that is not capable of dissolving the ingredients present in the first layer so that a highly concentrated water-repellent phase is obtained at the top of tne coating. Development accelerator Preferably, also one or more development accelerators are included in the inea'c-sensitive coating or in the heat-sensitive layer, i.e. compounds which act as dissolution prom.oters because ti'iey are capable of increasing rhe dissolution rate of the non- exposed coat :.ng in the dei^eloper, Tlie simultaneous application of aissclution inhititors and accelerators allows a precise fine tuning of the dissolution behavior of the coating. Suioable dissolution accelerators are cyclic acid anhydrides, phenols or organic acids. Exarapies of the cyclic acid anhydride include phthalic anhvdride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, alpha -phenylmaleic anhydride, succinic anhydride, and pyroinelliric anhydride, as described in U.S. Patent No. 4,115,128. Examples of ohe phenols include bisphenol A, p-nitrophenol, p- ethoxyphenol, 2,4,4'-trihydroxybenzophenone, 2,3,4-trihydroxy- Denzophenone , 4-hydroxybenzophenone, 4,4',4"-trihydroxy- triphenylmethane, and 4,4',3",4"-tetrahydroxy-3,5,3',5'- tetramethyltriphenyl-methane, and the like. Examples of the organic acids include sulfonic acids, sulfinic acids, alkylsulfuric acids, phosphonic acids, phosphates, and carboxylic acids, as described in, for example, JP-A Nos. 60-88,942 and 2-96,755. Specific examples of these organic acids include p-toluenesulfonic acid, aodecylbenzenesulfonic acid, p-toluenesuifinic acid, ethylsulfuric acid, phenylphosphonic acid, phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, adipic acid, p-toluic acid, 3,4-dimethoxybenzoic acid, phthalic acid, terephthalic acid, 4-cyclohexene-l,2-dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, and ascorbic acid. The amount of the cyclic acid anhydride, phenol, or organic acid contained in the coating is preferably in the range of 0.05 to 20% by weight, relative to the coating as a whole. Blocking agent In accordance with a preferred embodiment of the present invention, the blocking agent is added to the developing solution by removing at least part of the precursor wherein said blocking agent of che present invention is present. In this embodiment, the layer comprising one blocking agent is removed at least partially during developrrisnt, preferably, the blocking agent is present in the heat- sensitivs coating or in the heat-sensitive layer and/or the interraediate layer and/or in a top layer and/or in an optional other layer on tne back side of the suDDoro. According "co a more preferred erabodiment, rhe blocking agent is preser.c in the heat-sensitive coating or in the heat-sensitive layer anc/or the intermediate layer whereby the layer comprising the t■ocK i ng agent is removed at rhe exposed areas in the developing solut i or. In tnis way, it is hignly advantageous that the ,imount of Dlocl-: L ng agenr added to the developing solution is in correspondence with the amount of precursors developed. When the precursor has a toplayer which is removed only on the exposed areas, the blocking agent can also be present in the toplayer and the addition of blocking agent is also in correspondance v.'ith the exposed areas. In Lhis way the blocking agent is released in proportion with exposed areas and the amount of blocking agent present in such an image-wise dissolving coating ranges preferably between 0.01 g/m^ to 2,5 g/m^, 2 2 more preferably between 0.05 g/'m to 1.5 g/m , most preferably between 0.07 g/m'^ to 1.0 g/m^. According to another preferred embodiment of the present invention, the blocking agent is present in layer on the back side of the support and this layer is removed at least partially in the deve-oping solution. In this way the addition of blocking agent is proportional with the surface of the precursors which are developed, in an analogous way, the blocking agent can also be present in a top layer which is removed also in the non-exposed areas. In this way the blocking agent is released in proportion with surface of the precursor and the amount of blocking agent present in such a layer ranges preferably between O.Cl g/m^ to 2.0 g/m^, more preferably x ? 2 between 0.05 g/m to 1.5 g/m", most preferably between 0.0^ g/m to 1.0 g/re". In order to obtain an optimum blocking activity, it is aovanrageous to combine a precursor, having the blocking agent in a coating in a lower concentration, preferably between 0.005 and 0,35 g/m"", with a developing solution (or replenisher) , having a concentration of the blocking agent, preferably in the range of G.l and 3 g/1. LxDOSi.ire The material can be image-wise exposed directly witrj heat, e.g. thermal head. or indi V iTiean^ irectly by infrared light, which IS preferably converted into heat by an infrared light absorbing "ompourd, v.-mcn ir.ay be a dye or pigment having an absorpt.ion maKiraum :n the infrared wavelength range. The infrared light absoroing dye o: pig:r.ent is preferably present in rhe heat-sensitive coating or the heat-sensitive layer and typically in a concentration ranging oetween 0.25 and 10.0 wt.?, more preferably between 0.5 and 7.5 wt.% relative to the coating as a whole. Preferred IR-absorbing compounds .sre dyes such as cyanine or raerocyanine dyes or pig.tients such as carbon black. A suitable componncl is the following infrared dye IR- 1 : (IR-1i wherein X is a suitable counter ion such as tosylate, The heat-sensitive coating, or the heat-sensitive layer and/or tne intermediate layer, may further contain an organic dye which absorbs visible light so that a perceptible image is obtained upon irti.age-wise exposure and subsequent development. Such a dye is often called contrast dye or indicator dye. Preferably, the dye has a blue color and an absorption maximum in the wavelength range netween oOOn.Ti and 750 nm. Although the dye absorbs visible light, it preferably does not sensitize the printing plate precursor, i.e. the coating does not become more soluble in the developer upon exposure tc visible light. Suitable examples of such a contrast dye are the quaternized triarylmiethane dyes. and/or According to a preferred embodiment, the contrast dye is nresent in the heat-sensitive coating, or the heat-sensitive layer :he intermediate layer. riccoraing ro a highly preferred embodiment, rhe infrared light absor;-ing compound is concentrated in the heat-sensitive coating or he£;t-sens:.tive layer. The printing plate precursor of the present invention can be •^^xpossTi T-.o infrared light with LEDs or a laser. Preferably, a laser emitting near infrared light having a wavelength in the range from about 7 50 to about 1500 nm is used, such as a semiconductor laser diode, a Nd;YAG or a Nd:YLF laser. The required laser power depends on the sensitivity of the image-recording layer, the pixel dwell lime of the laser beam, which is determined by the spot diameter 2 ■:rypicai value of modern place-setters at 1/e of ma.xijnum intensity : 10-25 pm), the scan speed and the resolution of the exposure apparatus (i.e. the number of addressable pixels per unit of linear distance, often expressed in dots per inch or dpi; typical value : 1000-4 000 dpi}. Two types of laser-exposure apparatuses are commonly used: internal (ITD) and external drum (XTD) plate-setters. ITD plate- setters for thermal plates are typically characterized by a very high scan speed up to 500 m/sec and may require a laser povjer of several Watts. XTD plate-setters for thermal plates having a typical laser power from about 200 mW to about 1 W operate at a lower scan speed, e.g. from 0.1 to 10 m/sec. The known plate-setters can be used as an off-press exposure apparatus, which offers the benefit of reduced press down-time. XTD plate-setter configurations can also be used for on-press exposure, offering the benefit of immediate registration in a multi-color press. Mere technical details of on-press exposure apparatuses are aescribed in e.g. US 5,174,205 and US 5,163,368. In the development step, the non-image areas of the coating are removed by immersion in an aqueous alkaline developer, which may be combined with m.echanical rubbing, e.g. by a rotating brush. The developer preferably has a pK above 10, more preferably above 12. The developer may further contain a poly hydroxyl compound such as e.g. sorbitol, preferably in a concentration of at least 40 g/1, and a_so a Dolyethylene oxide containing compound such as e.g. Supronic 325, comjnercially available from RODTA, preferably in a concentrstior; of at most 0.15 g/1 - The clevelopinent step may be followed by a rinsing step and/or ■=! gunn-.ing stec. The gumming step involves post-treatment of the 1 i-hographic printing plate v.'rtn a gum solution. A gum solution is i-vpicaiy an aqueous 11quid wni ch comprises one or more sui face protectve compounds that are capable cf protectinc rhe lirhogra^ itTiage or a prinring plate against contamination or damaging. Suitable exair.ples of such compounds are film-forming hydroohilic polymers or surfactants. Tne plate precursor can, if required, be post-treated with a ^ri'^itabl e correcting agent or preservative as known in the art. To ::ncrea.= e the resistance of the finished printing plate and hence to extend the run length, the layer can be briefly heated to elevated temperatures ("baking"}. The plate can be dried before baking or is dried during the baking process itself. During the baking step, the plate can be heated at a temperature which is higher than the glass "ransit.ion temperature of the nea;:-sensitive coating, e.g. between lOO^C and 230'C for a period of 40 seconds to 5 minutes. Baking can be done in convenziOTial hot air ovens or by irradiation wirh lamps emitting in the infrared or ultraviolet spectrum. As a result of this baking srep, the resistance of the printing plate to plate cleaners, correction agents and UV-curable printing inks increases. Such a thermal pcst-treatment is described, inter alia, in DE 1,447,963 and GB 1,154,749. The printing plate thus obtained can be used for conventional, s.c-called wet offset printing, in which ink and an aqueous dampening liquid is supplied to the plate. Another suitable printing method uses so-called single-fluid ink without a dampening liquid. Suitable single-fluid inks have been described in US 4,045,232; US 4,981,517 and US 6,140,392. In a most preferred embodiment, the single-fluid ink comprises an ink phase, also called the hydrophobic or oleophilic pnase, and a polyol phase as described in WO 00/32705. EXAMPLES Preparation of Binder-02 In a 250 mi reactor, 162 rninol of Monomer-Ol, 21 . 3g (132 mmol) o-?nz.yl acrylamide, 0.43 g {6 miriolj acrylic acid and 103g gamma- were added and the rr.^xture was heated to 140' C, while stirring at iOG rpiu. h constanr flow of nitrogen was put over the reactov . Afcer di ssolution of al^ ■::he components, the reactor was ::ociea to iOO c. 0.35 ml Trigonox DC5C, commercially available from AK20 NOBEL, was added followed by the addrtron of 1.39 ml Trigonox 141, commercially available from AKZO NOBEL, in 3,43 ml butyrolactone. The polymerization was started and the reactor was heated to 140°C over 2 hours while dosing 1.75 ml Trigonox DC50. The mixt'jre was stirred at 400 rpm and the polymerization was allowed to continue for 2 hours ar 140"C. The reaction mixture was cooled to 120°C and the stirrer speed was enhanced to 500 rpm, 85.7 ml 1- methoxy-2-propanol was added and rhe reaction mixture was allowed to cool down to room temperature. Binder-01 was analyzed with 'H~NMR-spectroscopy and size exclusion chromatography, using dimethyl acetamide/0.21 % LiCl as eluent on a 5x mixed-B column and relative to polystyrene standards. I Mn 1 PD Binder-01 23500 ; 1 67000 2 . 84 The reaction mixture was cooled to 40°C and the resulting 25 weight % polymer solution was collected in a drum. CH, Compound-01: n' c impound-0 2: :;mpo'^na-C3 : Compound-04: ComDCLind-Oo: Preparation of the lithographic support. A 0.3C mm thick aluminum foil was degreased by immersing the foil in an aqueous solution containing 34 g/1 of sodium hydroxide at 7 C: C for 6 seconds and rinsed with deroineralised water for 3.6 seconds. The foil was then electrochemically grained during 8 seconds using an alternating current in an aqueous solution comiaining 15 g/1 HCl, 15 g/1 S04^ ions and 5 g/1 Al"^"^ at a 2 ceiTiperature of 37 °C and a current density of 100 A/dm , The aluminum foil W3S then desmutted by etching with an aqueous solution coniiaining 145 g/1 of sulfuric acid at SCC for 5 seconds and rinsed wirh demineraiized water for 4 seconds. The foil was subsequently subjected to anodic oxidation during 10 seconds in an aqueous solution containing 145 g/1 of sulfuric acid at a temperature of 2 57 "c and a current density of 25 A/dni , then washed with dem.inerali zed water for 7 seconds and post-treated for 4 seconds v;ith a solution containing 2.2 g/1 of polyvinylphosphonic acid at 'O^C, rinsed wirh demineralized warer for 3.5 seconds and dried at 120°C for 7 seconds. The support thus obtained was characterized by a surface roughness Ra of 0.35-0.40 jjiti (measured with interferometyer NTllOO) 2 and an anodic weight of 3.0 g/m". Preparation of the printing plate precursor ??P-01 The FPP-Cl was produced by first applying a first coating layer defined in Table 1 onto the above described lithographic support. The coating was applied at a v;et coating thickness of 2C ym and rhen drieo dL Cor^DCsition of the solution of the first coatinq lavei Amount oi proaac. 'iil-, " i. INGREDIEKTS ■ g; 351.54 Li-wariD-. PK i THF 1698.99 661 .86 253.7' 33. 84 Eander~01 ;25 % by weight; (3) :ry3tai Violet (1% by weight) (4) Tegoglaae 410 [l % by weight) (5) :l)Dowanol PH is l--methoxy-2-propanGi, commercially available from DOW CHEMICAL Company. [2] THF is tecrahydrofuran. i3;Binder-C1, preparation see above. ( ■: 5)TEG0GLIDE 410 is a copolymer of polysiloxane and poly (alkylene oxide) , corraTiercially available from CEGO CHEMIE SERVICE GmbH. On the first coated layer, a second layer as defined in Table 2 was coated at a wet coating thickness of 25 pm and dried at 135°C. Table 2; Composition of the solution of the second coating layer INGREDIENTS Amount of product (g) Dowanoi FM {1) 600.73 Alnovol SPN^52 (40 % by weight; (2; 132.07 I 1TMCA i1n % Dv we i ght) (3) 66 .20 2.74 Crystal Violet {1% by weight) (5) 1 80.23 1— — — Tegovjet 26r! (1 % by weight) (6) 11.23 ITeaoolide 410 il s bv weight) C?) i ^ ' 3 6.90 Amount of produc" (g) i b ■■■ . y i ■■ _; S^s 'i dCx s J . ■i A±ncvo: S?N4 52 is a novo lac soiu" ion, 4 0.5 % by weigh- in Dcwanol PM, corrjTiercially available from CLARIAKT. :3)TKCA is 3,4,5-trimethoxy cinnamic acid, (4) 30094 IS an IR absorbing cyanine dye, comnierciaily available from FEW CHEKlCfiLS; the chemical structure of S00S4 is equal to IR-1 (5) See Table 1. !£)Tegowet 265 is a copolymer of polysiloxane and poly(alkylene oxide'^, commercially available from TEGO CHEMIE SERVICE GmbH. (7) See Table 1. Imaging and processing of the printing plate precursor PPP-01 with DEV~Oi oo DEV-G3 The printing plate precursor PPP-01 was exposed with a Creo Trendsetter 3244 (plate-setter, trademark from Creo, Burnaby, Canada), operating at 150 rpm» and varying energy densities up to 200 mJ/cm^. INGREDIENTS After exposure the plate was processed with the developing solutions DEV-01 to DEV-C3 as defined in Table 4. Table 4: Composition of the developing solutions DEV-01 to DEV-C3 INGREDIENTS DEV-01 I (g) DEV-02 (g) DEV-0 3 sg) 1 Na-mf^-tas i li cate (1) 66 88 S8 Icrafol AP2 61 (2) 8 .83 8 . 83 8 .83 'r,ynpercnic 7304 (3) 4 . 4 ( 1 4 . 4 4 . 4 El oo>:-01 0 > 17 5 1 SiQCf:-03 0.31 V.;ater until IGOO 1000 1000 I'ja-m.e-Lasi 1 icate is sodium mstasilicate pentahyd rare , :omrrierci al 1V available from SILMACO NV ■ 2 ! Crsiol AF2 61 iS al kylether sociiurt-. salt, commercially available from COGNIS ; Synperoni c T304 is a block-cc-polyiner of polyethylene oxide 5 no polypropylene oxide 1 =PPO) attached ro ethyl en edi amine i-ECAi in a ratio EDA/PEO/PPC of 1/15/14 and having a rr.ean TT.D J 6 c u 1 £ r weight of 1500, cornirie r c i a 11 y available r r om. UN IQEMA. ID these experiments the precursor was exposed at the Right Exposure, hereinafter also referred to as RE. The RE is defined as the exposure energy at which a dot coverage on the plate for a 1x1 checkerboard and for a 8x8 checkerboard matches 50%. The dot coverage vjas measured with a GretagMacbeth D19C densitometer, commercially available from Gretag-Macbeth AG, with the uncoated support as reference. The development latitude was determined by developing a 1x1 cneckerbcard at different developing times. The Right Developing Titds, hereinafter also referred ro as RDT, is defined whereby the optical density, hereinafter also referred to as OD, on the plate match a SO ?. dot coverage, measured with a densitometer as described above. (A 5C dot coverage corresponds with an OD of approximately 0.3; the experimentally measured values are indicated in Table 5). The development latitude was measured by the difference between the optical density of a 1x1 checkerboard, developed at a shorter {e.g. ~3 seconds) or longer (e.g. -^2, +5 or +10 seconds) developing time, and the optical density of a 1x1 checkerboard, developed at the RDT. The lower the absolute value of this difference in OD, the more efficient of the additive is working as a blocking agent to reduce the dissolution kinetic of this coating and the more the development latitude is improved. The results are summiarized in Table 5. Table 5: Results of developing latitude 1 Compara¬ Inven¬ Inven¬ tive tion tion i Example 1 Exa.^ple 1 Ei^arrjple 2 'Precursor 1 PPP-01 1 PPP-01 1 PPP-01 'DeveJ oping solution ^ 1 DEV-01 1 DEV-02 1 1 1 DEV-0 3 1 Right developdnc time for 1x1 screen pattern (RDT) ( seconds; 1 ^ T 1 1 s 22 s 27 s ! D:: ... - RLT 0 . 30 0 . 32 0 . 29 ' , PDTt-2s) - RDT'] ' -0.11 j ~0. 05 i , at RDT+5s] - (ODrixl.at RDT) j -0.14 1 ~C . 06 -0.07 [ ':0D ,;■:>;',: at RDT + lOs) - (OD(ixl)at RDT)] -0.24 -0 . IC -C . 13 [{OD.:v:;at RDT-3S)--(OD;ivi )at RDT)] + 0.09 1 + 0.03 + 0.08 i The resu^Lts Table 5 demonstrate that the improved deveioprDent latitude for the Invention Examples 1 and 2 comprising a blocking agent £c-::ording to the present invention in the developing solution in comparisoPi with the Comparative Example 1. Imaging and processing of the printing plate precursor PPP-01 with DEV-04 to DEV-07 Tne printing plate precursor PPP-01 was exposed with a Creo Trendsetter 3244 (plate-setter, trademark from Creo, Burnaby, Canada), operating at 150 rpm and an energy density of 100, 110 and 12G mJ/cm"^. After exposure the plate was processed with the developing solutions at a temperature of 25°C during 15 seconds for DEV-04 and during 16 seconds for DEV-05 to DSV-07. The composition of the developing solutions are defined in Table 6. Table 6; Coreposition of the developing solutions DEV-04 to DEV-0' 1 INGREDIENTS DSV-04 (g) DEV-05 (g) DEV-0 6 (g) DEV-07 (g) K3-metasilioate (1) 177 r 177 177 17? Crafol AF2 61 ;2) 22 . 3 22. 3 1 22. 3 22 . 3 1 Tc-.T^pound-Oi ! 1 D.89 I blccf^-Cl j 0-356 Block-OS 0.85 ! iyatsr 1780 , 1780 i 1780 1730 )1; and ;2; sse Table 4. The dot coverages of a 8xS checkerbaord, exposed at these three expoi^cre energies, were measured wizh a GrezagMacbeth Di9C ■:ier.5; roiT:er.er v.'izh the unccatsd support as reference, as -described i'bcve. The exposure latitude is aetermined by the differenc- between the DD 01 the 3x6 checkerboard at each exposure energy. The lo>jer this difference tn OD, the mors efficient of the additive is working as a blocking agent to reduce the dissolution kinetic of this coating and the more the exposure latitude is irriproved. The results are summarized in Table Table 7: Results of exposure latitude Precursor Developing Exposure Developing 0D{ 8x8} solution Energy time (mJ/cm^ ] (seconds) j Comparative PPP-01 j DSV-04 100 15 s 0. 180 1 Example 2 110 15 s 0- 137 120 15 s 0. 095 1 Comparative, PPF-01 DEV-05 , i 100 16 s 0. 2G4 Example 3 1 1 110 16 s 0. 089 120 16 s 0. 012 Invention Example 3 PPP-01 DEV-06 100 16 s 0. 300 110 16 s 0. 301 120 TeT^ 0. 253 Invention PPP-01 DEV-07 100 16 s 0 . 340 j Example 4 1 110 16 s 'J . 330 i 120 1 16 s 0 . 313 The results in Table 7 demonstrate that the improved exposure ]atitude for the Invention Examples 3 and 4 comprising a blocking agent according to the present invention in the developing solution L) E V - f; 6 and DE',^ - 0 " . Ttse developing solutions DEV-04 and DEV-05 in rhe Comparative Exam.plss 2 and 3 comprise no blocking agent and a blocking agent of the prior art respectively, whereby these developing solutions behave a to srrong developing property resulting in an OD ieveioping solutions is very poor in comparison with the developin' solutions of the present invention whereby the change in OD at itifersnt exposure energies is very small, resulting in a high exposvire laojrude. Pieodration of the prinoing plate precursor PPP-Oi j-iererenc^ Therefore, the expos ea irsor PPP-C2 was proce?5sed, withouT_ previously been exposed to IR-laser or heat, in the develooing solutions as mentioned in Table 9 and 10 with a dwell time of 20 seconds at a temperature of 25°C. DEV-Reference is a developing solution without addition of a blocking agent or an other The PFP-02 was produced by applying a coating layer defined in Table 5 onto the above described lithographic support, The solvent used to apply the coating is a mixture of 17% by volume of Dowanol PM and 5 3 -r by volume of tetrahydrofuran. The coating was applied at a wet co'ating thickness of 20 and then dried at 135°C. Table 8: Composition of the coating layer INGREDIENTS Amount of product (g /m' ) Uinder~01 (25 % by weight) (1] 1. 00 Crystal Vjol^t 'U by weight^ (2) "O7OT9~ ' " Tegoglide 410 {1 % by weight) (3) 0.0025 Total dry coating weight (g/m ) 1.02 1) to (3) see previous tables. Processing of the printing plate precursor FPP-02 in DEV- ^no BEV-08 to DEV-22 The printing plate precursor PPP-02 comprises the coating layer as defined in Table 8 and this layer has an analogue composition as the first coating layer of PPP-01. This layer is soluble in an alkaline solution and is used as a model for testing the efficiency of the blocking agents to reduce the dissolution kinetic of non- coir.pcund; DEV--08 i:o DEV-18 are developing solutions comprising a DlDCking agent of the present invention; and DEV~19 to DEV-22 are ■developing solutions comprising another additive compound as defined in Taole 9 and IC. Table 9: Ccrripcsition of the aeveloping solutions DEV-Reference and DEV-08 to OEV-22 INGREDIENTS : DEV-Reference (g) DEV-08 to DEV-l"^ (g) DEV-18 to DEV-22 (g) 1Na-glucoheptonate (1) 5 Na-rnetas ill care (2) 102 102 102 Na-silicate solution (3) 10 10 10 jVariquat cc 9NS (4) 0.044 0 . 044 0 . 044 Triton H-66 ;5) 5.8 6.8 5.8 Synperonic T304 (6) 0.141 0.141 0.141 ja blocking agent added as defined in Table 10 0. 01 mol a compound added as defined I in Table 10 f 1 i 0.01 mol Water until 1000 1000 1000 f1) Na-glucoheptonate is glucoheptonate sodium salt (2) See previous tables liiVariquat cc 9N3 is a cationic surfactant, commsrcially available from GCLTjSCHMIDT '•^t Triton is an anionic surfactant, commercially available from SEPULCHRE '5)See previous tables. .tfter processing the OD is measured with a GretagMacbeth D19C densitometer with the uncoated support as reference, as described above. The difference between ohe OD of the plate PPP-02, developed with each o: the developing solutions DEV-08 to DEV-22, and the OD of the plate FPP-02, developed with DEV-Reference, were calculated. The h;igher the value of this difference in OD, the more efficient the additive is working as a blocking agent to reduce the di3solution kinetic of this coating. The blocking efficiency of nhe differenr compounds was rated by t;-j-5 difference in OD: difference in OD D.15 and Code 2: difference in OD ^ 0.5C and Code 3: difference in OD > 1.00, means a high blocking effect. The results are summarized in Table 10. Table 10: Results of blocking efficiency Precursor Developing solution Additive in developing solution Code for blocking efficiency Invention Example 5 PPP-02 DEV-08 Block-01 2 Invention Zxa;T.pls 6 PPP-02 DEV-09 Block-02 2 Invsrtion Example 7 PPP-02 DEV-10 Elock-03 3 Invention Example 8 PPP-02 DEV-11 Block-04 3 Invention Exarr.ple 9 PPP-02 DEV-12 Block-05 2 Invention Example 10 PFP-02 1 DEV-13 Block-06 I 1 Invention ExaiTiple 11 PPP-C2 DEV-14 1 Block-07 1 Invention 1 Example 12 PPP-02 DSV-15 Block-08 3 Invention Example 13 PPP-02 DEV-16 Block-09 3 i Invention Example 14 ( PPP-02 DEV-17 Eiock-10 1 Comparative ; PPP-02 Example 5 1 DEV-IB Compound-02 i 0 : Comparative ' PFF-02 i DEV-19 i Compound-0'J 0 E.xample 5 Comparative PPP-02 ! DEV-2a 1 ' CDmpound-04 0 Coriipa rati ve PPP-02 DEV-il ■ Compound-05 1 0 Compa rj! 12 ve Example 9 ; PPP-02 DZV-22 1 Compound-06 The results in Table 10 de.-nonsfcrate that, in the Invention Examples 5 to 14, the developsrs DEV-08 to DEV-17 comprising a c'lociiing agent of the present invermion exhibit an improved ef flcLency In reducing the dissolution kinetic of this coating. In the Comparative Examples 5 to 9, the developers DEV-18 to DEV-22, comprising a compound of the prior art, exhibit a poor blocking effect. Preparation of the printing plate precursors PPP- Tne ??F-C7 were prod'^ted by first applying a fi rst coating 2ayer defined in Table 11 onto the above described lithographic support. The coating was applied at a wet coating thickness of 20 ijm and Chen dried at 135°C. The dry coating weight amounts to 1.02 g /m ~. 03 to PPP-07 Ta'Dle 11: Composition of the solution of the first coating layer INGREDIENTS Amount of product for PPP-03 ?jnount of product for PPP-04 Amount of product for PPP-05 Amount of product for PPP-06 Amount of 1 product for PPP-07 (g) (g) (g) (g) 1 Eiowanol (1) 160.74 160.45 160.45 160.4 5 160.45 i 1 iTHF '2i 1 535.04 5 3 5.96 ' 1 535.96 53 5.96 535.96 3inder-01 ;25 wt.^) (3) 211.37 211.62 211.62 211. 62 211.62 Bloc>:-04 i 1.35 INGREDIENTS Amount or product for PPF-C3 !g) Amount of product for PPP-C4 Amount of product for j PPP-05 (g) Amounr of product for PPP-0 6 ; g ' Amount of product - for , FPP-07 1 :■ O ± 0 C - J. -L 1. 35 Block-03 1. 35 Block-G1 1 .35 Crystal Violet 11 wt.V! i 81.05 81.14 i 81.14 81.14 81.14 ;Tego?liae i1 wt.%) (5 ) 10 . 81 10.32 1 10 . 82 10.82 10.02 ;1; zo (5) see previous tables. Or. zhe f:i.rst coated layer, a second layer as defined in T3.ble 12 was coated at a wet coating thickness of 25 pm and dried at 135°C. 2 The dry coating weight amounts to 0,8 0 g/m , 5ble 12: Composition of the solution of the second coating layer INGREDIENTS 1 Amount of product for PPP-03 to PPP-07 (g) Dowanol PM '1) 1 2 3 5.0 AInovci SPN-^52 (40 % by weight) (2) 117.11 TMCA no ? by weight) {3) 1 60. 34 \|S0094 (4) 2 .41 Crystal Violet (1% by weight'; (5) 70 . 99 ! Teqowe i. 2 65 i' 1 % by weight) ; 6) 9. 94 Tegoglide 410 (1 1 by weight) (7) 32.65 Butanone 471.55 see previous tables ^ I u- I . ipTiasing and processing of the printing plate precursor PFP-03 to p p p _ n 7 Tne printing plate precursors PPP-C3 to PPP-O" were, in a first gxperir::er.t, exposed with a Creo Trendsetter 3244 (plate-setter, ■..radeiv^srk from Creo, Burnaby, Canada^, operating at 15C rpm at the Pight Exposure (RE) as defined above and developed with DEV-01 as defined above- in Table 4. In a second experiment, the printing plate precursors PPP-03 to PPP-07 were exposed by a 1x1 checkerboard at an exposure energy which is 20 « lower than the RE value as determined above and, also, at an exposure energy which is 20 % higher than the RE value. After developing, the dot coverage for the under-exposure by 20 % and for the over-exposure by 20 % was measured by the OD as defined above. The exposure latitude was determined by difference between the dot coverage by the 20 % under-exposure and the dot coverage by the 20 I over-exposure. The lower the absolute value of this difference, the more efficiently the dissolution kinetic of the coating is reduced and rhe more the exposure latitude is improved. The results are surmarized in Table 13, "able 13: Results of exposure latitude EXAMPLES PPP-type RE-valus (mJ/cm") [Dot coverage RE-20t-,]- [Dot coverage at Comparative .; Example 10 PPP-03 35 15 Invention Example 15 PPP-04 124 13 Invention Example 16 PPP-05 132 12 Invention Example PPP-06 110 8 ! Invention 1 Examp-Le — ti 1 PPP-07 121 15 i The results in Table 13 demonstrate an improved exposure latitude for the Invention Examples 15 to 18, comprising a blocking agent ding to rhe present invention, whereby the difference between c;. j_ , t.'e dot coverage by -he 20 % under-exposure and the dot coverage by the 2C % over-exposure is lower "han in the Comparative Eixample 10. WE CLAIM 1. A rrsthod for making a li-hographic printing plate comprising tne sreps of: (1; providing a heat-sensitive lithographic printing plate precursor comprisxng on a support having a hydrophiiic surface or whicn is provided with a hydrophiiic layer, a heat- sensitive coating, (iO image-wise exposing said precursor with IR-radiation or heat, and (3) developing said image-wise exposed precursor with an alkaline developing solution comprising a compound having at least two oni-am groups, whereby said compound having at least two onium groups has a structure according to formula I, II or III: Q is a divalent group when e and f are 0, a trivalent group when the surr, of e and f is 1, or a tetravalent grouD when e and f are both 1, 2" ""-c Z' independently are oniurr. groups, L and L" to L*^ independently are linkrng groups, and represents a repeating unit wherein Z"'" and L' represenr respectively an onium group and a linking group for each x-value, a, b, c, d, e and f independently are 0 or 1, and X is an integer ranging between 1 and 10. A method according to any of the preceding claims, wherein said linking group is selected from the group consisting of a linear, branched or cyclic alkylene group, an arylene group, an arylene-alkylene group, an oxy-alkylene group, an oxy- arylsne group, an oxy-heteroarylene group, or a combination of t'wo or more of these groups. A method according to any of the preceding claims, wherein said onium group is selected from the group consisting of primary amine salts, secorLdary amine salts, tertiary amine sal's, quaternary ammoni'um salts, phosphonium salts or sulphoniurn salts. 1. A method according to any of the preceding claims, wherein the precursor comprises a compound having a structure according to formula I, II or III and wherein, during said developing step, at least part of said compound is removed from said precursor. A i-isthod according to any of the preceding claims, wherein during or after said developing step, a replenishing solution comprising a compound having a structure according to fC'riuula I, or III is added to said developing solution. t. A T-ethod according to any of the preceding claims, wherein s.Tiid slKsline developing solution comprising said compound having a structure according uo formula I, II or III further comprises a silicate or metasilicate. 7. An aqueous alkaline developing solution or replenishing solution comprising an alkaline agent and a compound having a structure according to formula I, II or III, 3. A heat-sensitive lithographic printing plate precursor com,prising on a support having a hydrophiiic surface or which is provided with a hydrophiiic layer, a heat-sensitive coating comprising a compound having a structure according to formula I, Ii or III.

Full Text

METHOD FOR MAKING A LITHOGRAPHIC PRINTING PLATE [DESCRIPTION]
FIELD OF THE INVENTION
The present invention relates to a method for making a lithographic printing plate wherein an image-wise exposed precursor is developed with an alkaline developing solution comprising a compound having at least two onium groups. The present invention relates also to an alkaline developing solution and to a replenishing solution comprising said compound having at least two onium groups. The present invention relates also to a lithographic printing plate precursor wherein the coating comprises said compound having at least two onium groups.
BACKGROUND OF THE INVENTION
Lithographic printing typically involves the use of a so-called printing master such as a printing plate which is mounted on a cylinder of a rotary printing press. The roaster carries a lithographic image on its surface and a print is obtained by applying ink to said image and then transferring the ink from the master onto a receiver material, which is typically paper. In conventional lithographic printing, ink as well as an aqueous fountain solution (also called dampening liquid) are supplied to the lithographic image which consists of oleophilic {or hydrophobic, i.e. ink-accepting, water-repelling) areas as well as hydrophiiic for oleophobic, i.e. water-accepting, ink-repelling) areas. In so- calied driographic printing, the lithographic image consists of ink- accepting and ink-abhesive {ink-repelling) areas and during driographic printing, only ink is supplied to the master.
Printing masters are generally obtained by the iinage-wise exposure and processing of an imaging material called plate precursor. A typical positive-working plate precursor comprises a hydrophiiic support and an oleophilic coating which is not readily soluble in an aqueous alkaline developer in the non-exposed state and becomes soluble in the developer after exposure to radiation. In addition to the well known photosensitive imaging materials which are suitable for UV contact exposure through a film mask (the so-
called pre-sensitized plates), also heat-sensitive printing plate precursors have become very popular. Such thermal materials offer the advantage of daylight stability and are especially used in the
-called cor;pj-er-to-plate m.ethod (CtP) wherein the elate precurso^i.^ is directly exposed, i.e. without the use of a film mask. The rr.aterial is exposed to heat or tc infrared light and the generated heat triggers a (physico-)chemical process, such as ablation, polymerization, insolubilization by cross-linking of a polymer or by parti cl e coagulation of a therm.oplastic polymer latex, and solubi]ization by the destruction of intermolecular interactions or by increasing the penetrability of a development barrier layer.
Although some of these thermal processes enable plate rriaking without, wet processing, the miost popular thermal plates form an image by a heat-induced solubility difference in an alkaline developer between exposed and non-exposed areas of the coating. The coating typically comprises an oleophilic binder, e.g. a phenolic resin, of which the rate of dissolution in the developer is either reduced (negative working) or increased (positive working) by the image-wise exposure. During processing, the solubility differential leads ro the removal of the non-image (non-printing) areas of the coating, thereby revealing the hydrophilic support, while the image iprinring) areas of the coating remain on the support.
Typically, for a positive-working thermal plate, a dissolution inhibitor is added to a phenolic resin as binder whereby the rate of dissolution of the coating is reduced. Upon heating, this reduced rate of oissolution of the coating is increased on the exposed areas compared with the non-exposed areas, resulting in a sufficient difference in solubility of the coating after image-wise recording by heat or IR-radiation. Many different dissolution inhibitors are known and disclosed in the literature, such as organic compounds having an aromatic group and a hydrogen bonding site or polymers or surfactants comprising siloxane or fluoroalkyl units.
The known heat-sensitive printing plate precursors typically comprise a hydroiohilic support and a coating which is alkali-soluble in exposed areas [positive worxing material; or in non-exposed areas inegaoive working m.aterial) and an IR-absorbing compound. Such coating typically comprises an oleophilic polymer which may be a ohenolic resin such as novolac, resol or a polyvinylphenolic resin. The phienclic resin can be chemically modified whereby the phenolic .Tionomeri c ur.i t is substi tuted by £ group such as described in WO&9/01795, EP 934 822, EP 1 C72 432, US 3,929,486, EP 2 102 443, EP 2 1C2 44^, EP 2 102 445, EP 2 102 446. The phenolic resin can also oeen laixsd v;it.h other polymers such as an acidic pclyvinyi acetal as described in WC2004/020484 or a copolymer comprising sulfonamide groups as described in US 6,143,454. The use of other pclymeric tinders in lithographic printing plates are described in VJC2001/09682, EP 933 682, WO99/63407, W02002753626, EP 1 433 594 and E? 1 439 058.
The positive-working thermal plate may further comprise, between the heat-sensitive recording layer and the support, an intermediate layer comprising an alkali soluble resin. This intermediate layer can improve the chemical resistance of ^he plate against press chemicals. This layer induces an improved removing of the coating on the exposed areas. Typical examples of positive- working thermal plate materials having such a two layer structure are described in e.g. EP 864420, EP 909657, EP-A 1011970, EP-A 1263590, EP-A 1268660, EP-A 1D72432, EP-A 1120246, EP-A 1303399, EP- A 1311394, EP-A 1211065, EP-A 1368413, EP-A 1241003,EF-A 1299238, E?-A 12 62318, EP-A 1275498, EP-A 1291172, W02003/74287, WG2004/33206, EP-A 14 33594 and EP-A 14 39058. However, in the non- exposed areas of these plates the resistance of the coating for the alkaline developer is poor whereby the difference in dissolution rate oetween the exposed and non-exposed areas is insufficient, i.e. the non-exposed areas are partially affected by the developer before ihe exposed areas are completely dissolved in the developer. As a result, it is difficult to form highly sharp and clear images, particularly highlights, i.e. fine images comprising a dot pattern or fine lines, are difficult to be reproduced.
In a high quality plate it is advantageous that such highlights can be reproduced within a sufficient developing latitude, i.e. small fluctuations in developing time does not substantially affect the image formed on the plates and this developing latitude is obtained when the difference in dissolution rate is improved.
EP 1 J 82 512 discloses an alkaline developing solution comprising an amphoteric or cationic surfactant for development of an infrared radiation-presensitized plate.
EP 1 400 856 discloses a method for making a lithographic printing plats whereby the exposed precursor is developed with an
alkaline developing solution conprising a car ionic sur f acranr. or a compound having three or more ethylene oxide-rerminal groups in the molecule tnereof.
EF 1 211 055 discloses 5 posirive-working heat-sensitive print:i ng pi are precursor wherein the recording layer comprises an organic quaternary ainmonium. salt.
Tne printing plates of the prior art suffer from an insufficient developing latitude.
SUMMARY OF THE INVENTION
It is therefore an aspect of the present invention to provide a method for making a heat-sensirive lithographic printing plate whereby excellent printing properties are obtained and whereby the developing latitude or exposure latitude are improved. This object is realized by the method defined in claim 1, having the characteristic feature that the developing solution in the developing step comprises a coiripound having at least two oniuru groups. This compound, hereinafter also referred to as 'blocking agenr", which is capable of reducing the solubility of the alkaline soluble resin of the coating of a positive-working heat-sensitive printing plate precursor whereby the resistance of the coating in the non-exposed areas against the alkaline developer is increased, is present in the precursor and/or in an alkaline developing solution or replenishing solution. By use of compounds mentioned in the prior art documents EP 1 182 512, EP 1 400 856 and EP 1 211 065 an insufficient developing latitude is obtained. Therefore, the inverters have found this new compound which is capable of improving the resistance of the coating in the non-exposed areas against the alkaline developer and capable of improving the developing latitude or the exposure latitude.
Other specific embodiments of the invention are defined in the dependent clainis.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the present invention, there is provided a method for making a lithographic printing plate comprising the steps
' 1) providing a heat-sensitive iiizhographic printing pi are precursor comprising on a support having a nydrophiiic surface or v/hich is provided a hydrophilic ^ayer, a near-sensitive coating,
IjT,age-wise exposing said precursor wirh IR-raaiarion or iieat,
and
'3; developing said image-wise exposed precursor wirh an aixaiine developing sclution comprising a compound having ar least two onium groups.
In a preferred embodiment of rhe present invention, said oo^mpound having at least two onium groups has a structure according to fornijla I
/ \

-Q-
d
\ /

L'
Z'
(iormula 1
wherein
Q is a divalent group Q when e and f are 0, a trivalent group Q"
4
when the sum of e and f is 1, or a tetravalent group Q when e and f are borh 1,
Z^ to Z" independently are onium groups,
L'" to L^ independently are divalent linking groups, and
a, b, c, d, e and f independenrly are 0 or 1, preferably a, b, c and
d are 1 .
Ir_ another preferred embodiinent of the present invention, said compound having at least two onium groups has a structure according

Z"" and z'^ independently are cnium croups, Ii"' is s divalent linking group,
-7"-L"~ represents a repeating unit wherein Z^ and L"'' represent respectively a divalent oniuiri group and a divalent linking group for each x-value, and
X is 0, 1 or an integer >1, more preferably x is an integer ranging between 1 and 50, most preferably between 1 and 10.
In a more preferred embodiment of the present invention, said compound having at least two oniuni groups has a structure according to formula III Z^-L-Z^', (formula 111)
wherein
L is a divalent linking group, and
Z"' and z"^ independently are onium groups.
The divalent linking groups L^ to l"^, each L^' and L in the compounds of formula I, II and III are preferably selected from the group consisting of a linear, branched or cyclic alkylene group such as a methylene, ethylene, propylene, butylene group, c-hexylene or 1-methyl-ethylene; an arylene group such as a phenylene, naphtalene or an heteroarylene group; an arylene-alkylene group sucri as benzylidene group; a bis-alkylene aromatic hydrocarbon group such as o-, p- or m-bis-methylene benzene group; an oxy-alkylene group such ss methylene oxide, ethylene oxide or propylene oxide group; an oxy- arylene cr oxy-heteroarylene group such as phenylene oxide; or a combination of two or more of these groups. Each of these alkylene or arylene groups can be substituted. The linking group of the present invention is composed of at least one of these groups. In a preferred embodiment, the linking group is composed of one or two of these groups which are repeated for at least two times, more preferably for a number ranging between 2 and 15, most pre-i'erably between 3 and 8. The linking group of the present invention can also
be composed of r.wo, three or more sequences or these groups whererr. each sequence contains at lease cwo or more of these groups.
Examples cf a divalent linking group are -'CH^.-, - ; - (CH-j - (CH-i - ;CH-CH;)-c-C.rHio", -
: - , - 'CH; ; - {CfH4} - , - (CH;) - (CeHa; - (CK2J - , -0- (CH2; -, -c- (CH:; - ■ CH.^ ) -, -0- 'CH;) - (CH~CH3) - ^CeHj : - ;CgH4) -O- !CfH4) - , " (CH-) - (CH-) - J-0- (CHjJ - (CH-) -1- -,
wherein P"^ and r'^ are indepenaently hydrogen or an optionaJly substituted alkyl cr aryl group; n is an integer ranging between 2 and 15, preferably between 5 and 10, m is an integer ranging between i ana 15, preferably between 3 and 10,
0'" is a divalent group, preferably selected from the group consisting of the divalent linking groups as defined above,
'■J
Q" is a trivalent group, preferably selected from the group consisting of -CR' each of > and R', R" and R'" are hydrogen or an optionaly substituted alkyl, aryl or aialkyl group,
L', L" and L"' are a divalent linking, preferably selected from the group consisting of the divalent linking groups as defined above, and
p, q and r independently are 0 or 1,
is a tetravalent group, preferably selected from the list of
tne following groups: >C XCeH.X, CeH-{-(L' ) p-) (-(L") q-) (-(L'" ) r-) s") ' [>N wherein
each of > and L' , L" and L'" are a divalent linking, preferably selected from the grout consisting of the divalent linking groups as defined above, and
p, q, r and s independently are 0 or preferably .

Tne onium croups Z^ to Z" and Z" in the compounds or lorraula I, :T anc III are positively charged groups and preferably selected f roiT; cne group consisting of prrmary amine salts, secondary arr.ine sales, tertiary amine salts, quaternary aminonium salts, phosphoniun/ salts or su 1;;J']oniurn salts.
The onium groups Z"" to Z'^ are more preferably selected from the groups consisting of one of the following structures:
P/
'N X
R'
_ 1
W
R
R"
N R"
R"
R-
p- p
R
wherein
* denotes rhe binding site of the onium group with one site of the
d i V a 1 e ri t linking group;
Z represents oxygen, sulfur or -NR'^-; 1
each of R to R^ groups are independently hydrogen; an optionally substituted alkyl, alkylene, aryl or aralkyl group such as methyl, ethyl, propyl, butyl, propenyl, butenyl, phenyl or benzyl; a halogen atom such as bromide or chloride; -CN; -NO2; an oxy-alkyl or oxy- aryl group; a thio-alkyl or thio-aryl group; an amide or sulphonamide group; a carboxylic acid or salt or alkyl estor group; a sulphonic acid or salt or alP:yl ester group,- a sulphonalkyl or sulphonaryl group; an amino group; or whereby two groups of the R^ to R" groups together comprise the necessary atoms to form a cyclic
structure, preferably a 5- or 6-meinberd xing;
6 S
each of R to R groups are independently hydrogen; an optionally substituted alkyl, alkylene, aryl or aralkyl group such as methyl, ethyl, propyl, butyl, propenyl^ butenyl, phenyl or benzyl; a carboxylic acid or salt or alkyl ester group; or whereby two groups of the r"^ to R® groups together comprise the necessary atoms to form a cyclic structure, preferably a 5- or 6~memberd ring.
Each of the onium groups Z^" in the compounds of formula 11 are positively charged groups having two binding sites, i.e. divalent, and more preferably selected from the list of the onium groups as above wherein one of the R^ to R^ groups is not present and is
replaced by indicating the second binding site.
In order to obtain electrically neutrality, one or more anions are present as counterion. Examples of such counterions are cnlor 1 de, brorr.i de, iodide, or a compound comprising at least one of the follov;ina anionic groups: a sulphonate, sulphate, carboxylate, phosphate or phosphonate anion, or wherein the sulphonate, sulphate,

r,5rboxylate, phosphate or phosphonace anion is part of one of the substituting groups R^ to R" of "he onium group as defined above. Preferred counter ions are broiriide, chloride, methyl sulphonate or
The onruni groups Z to Z" in the compounds of formula I have preferably the same structure.
The or.ium groups Z^ and Z'^ in the compounds of formula II, have preferably the same structure.
All the Z^' groups rn the oompounds of formula II, have preferably the same structure.
The onium groups Z® and Z^ in the compounds of formula III, have preferably the same structure.
7
CI Ci
Examples of blocking agents of the present invention are
CI CI
B]ock-02:
N-
-N.
3lock-03 :
B1ock-06:
Elock-07:
>
\

&1ock-0
Elock-09'
^N \W
CI
N

N,
N,
E1 o c "f^ - ] 0
During developing of an image-wise exposed heat-sensitive lithographic printing plate precursor, the blocking agent of the present invention is present in the aqueous alkaline developing solution.
In accordance with a preferred embodiment of the present invention, the blocking agent of rhe present invention is present in 'he alkaline developing solution at the start of the developing process.
Br Bi
r;iocf:-l 1;
In accordance with another preferred Gmbodiment of the present invention, The blocking agent is added to the alkaline developing solution during the developing process, preferably as a solution or cii.=;pe:-.=;ion. ir: a more preferred embodiment, the blocking aqent is added t.o the alkaline developing solution by the addition of a

leplenishinq solution comprising ^he blocking agent during the oeveioping process.
In accordance with another preferred embodimenc oi the present invancion, che blocking agent is added to the alkaline developing solution during the developing process by removing at least part of the precursor comprising the blocking agent. The biockinc agent can oe present in the heat-sensitive coating, an intermediate layer between the support and the heat-sensitive coating, a top layer ind/or a layer on the back side cf the plate.
Developing solution
The aqueous alkaline developing soluti®n (hereinafter also referred to as "developer") may comprise an alkaline agent. The composition of said aqueous alkaline solution can be selected from conventional alkaline developers,
The aqueous alkaline developing solution of the present invention has preferably a pH value of at least 10, more preferably of at least 11.5, most preferably of at least 12. There is no specific upper limit for the pH but the pH is usually not higher chan 14 .
The alkaline agent includes inorganic alkaline agents such as sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium zertiary phosphate, potassium tertiary phosphate, ammonium tertiary phosphate, sodium secondary phosphate, potassium secondary phosphate, aminonium secondary phosphate, sodium carbonate, potassium carbonate, ammonium carbonate, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium borate, potassium borate and ammonium borate, and potassium citrate, sodium citrate and the Mke.
The alkaline agent may also include organic alkaline agents such as monomethylamine, dimethylam.ine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisoDropvls:[^.ine, triisopropylamine, n-butylamine, monoethanolamine, diethanolami ne, triethanolairiine, monoisopropanolamdne, diiscpropanoiamine, ethylenediamine, pyridine and the like.
The alkaline aqueous soluzion may also Include an alkaline silicate. The alkaline silicate may be those exhibiting an alkalinity '/;nen dissolved in water, and examples thereof include an
?.lkali metal silicate and alkali metal ine-asilicate such as sodium silicate, sodium nietasilicate, potassium silicate and lithiuir! silicate, and anmioniuni silicate. Said alkaline silicate mav be used,,,. =:lc;ne, or ir. combination.
The devalopment performance of the alkaline aqueous solution" iiiay be easilv moaulated by adjuscing a molar ratio of alkaline siiicaces and alkali metal hydroxides, represented by sij icon oxide iSiO;;.'; and an alkali oxide (M2C, wherein M represents an alkali inetal or an arpinonium. group) . The alkaline aqueous solution has preferably a mciar ratio Si02/M20 from 0.;. to 3.0, and more preferably from 1.0 tc 2.0. When the molar ratio Si02/M20 is less than 0.5, alkalinity of the solution strengthens so as to cause a harmful effect such as etching of an aluminum plate w.hich is generally used as a substrate in a lithographic printing plare precursor. When the molar ratio, 3i02/M20 is more than 3.0, the development performance of the solution may be degraded.
The concentration of alkaline silicate in the developer ranges generally from 1 to 14% by weight, preferably from 3 to 14% by weight, and more preferably from 4 to 14% by weight. When said concentration is less than 1% by weight, the development performance or treatment capacity may be degraded. When said concentration is more chan 14% by weight, precipitared materials or crystals may be easily generated, and gelation may be easily caused during neutraJization of waste liquid, resulting in an obstacle to the ■waste disposal.
The developer based on an alkaline aqueous solution may also comprise a nonreducing sugar. The nonreducing sugar denotes sugars having no reductive property due to the absence of a free aldehyde group or a free ketone group. Said nonreducing sugar is classified into trehalcse-type oligosaccharides wherein a reductive group and another reductive group make a linkage; glycosides wherein a reductive group in a sugar is linked to a non-sugar compound; and sugar alcohols which are produced by reducing a sugar by nvarog&nation. Said trehalose-zype oligosaccharides include sucrose and trehalose, and said glycosides include alkyl glycosides, phenol glycosides, mustard oil glycosides and the like. Said sugar alcohols incluoe D, I.-arabitol, ribitol, xylitol, D, L-sorbitol, D, L-mannitol, :;,I-;dicol, talitol, dulcitol, allodulcitol and the like. Further, malticol obtained by hydrogenacion of disaccharide, a reduced !T,£-eriai obtained by hydroger.at.ion cf oligosaccharide (a reduced 5zarch syrup? and the like are preferably used. In rhe abov^e ^ nonreducing sugar, preferred are sugar alcohols and sucrose, and particularly preferred are D-sorbicol, sucrose and a reduced starch syrup, since they have buffering action in appropriate pH range.
"he above nonreducing sugar rr.ay be used alone or in combination v.'ith other ingredients, and the concentration thereof in the developer ranges generally frorr, 0.1 to 30% by weight, and preferably from 1 to by weight.
In the developer, an alkaline agent may be used as a base in combination with the above mentioned alkaline silicate or nonreducing sugar, and said alkaline agent may be selected from sodium hydroxide and potassium hydroxide. Further, sodium tertiary phosphate, potassium tertiary phosphate, sodium carbonate and potassium carbonate are also preferable, since they have themselves, buffering action. The above alkaline agent may be used alone or in combination.
The developer may optionally contain further components, such as buffer substances, complexing agents, antifoaming agents, organic solvents, antisludge agent, corrosion inhibitors, dyes, surfactants and/or hydrotropic agents as known in the art.
In the aqueous alkaline developing solution, it is possible to sirnui taneously use organic solvents having solubility in water at 20 "C of not more than 15 % by weight according to need. Examples of such organic solvents are such carboxilic acid esters as ethyl acetate, propyl acetate, butyl acetate, amyl acetate, benzyl acetate, ethylene glycol monobutyl ether acetate, butyl lactate and butyl levulinate; such ketones as ethyl butyl ketone, methyl isobutyl ketone and cyclohexanone; such alcohols as ethylene glycol monobutyl ether, ethylene glycol benzyl ether, ethylene glycol monophenyl ether, benzyl alcohol, methylphenylcarbitol, n-amyl a'cohoJ snd .nethylamyl alcohol; such alkyl-substituted aromatic hydrocarbons as xylene; and such halogenated hydrocarbons as methyJ.ene cichloride and monochlorobenzene. These organic solvents may be used alone or in combination. Particularly preferred is r-er.zvl alcohol in the invention. Ihese oraanic solvents are added
tc ^he developer or replenisher therefor generally in an amount of not mo.-9 than 10 % by weight and preferably not more than 5 I ■
Besides the components described above, the developing solution cf the present invention comprises a non-ionic surf^ctanr.. Such a non-ionic surfactant may be used as a dissolution preventing agent whereby undercutting of non-expossd areas is reduced. Examples of nonion], c surfactants include echoKviated alcohols^ polyethylene glycols and polyhydric alcohols. Ethoxylated alcohols are preferred, and in particular ethoxylated alcohols having a hydrophilic- lipophilic balance (HLB) higher than 5 are more preferred. Specific examples of nonionic surfactants are listed below; polyethylene glycol, polyoxyethylene lauryl ether, laurylalcchol polyglycol ethers, oleyl alcohol ethoxylaced, lanolin alcohol ethoxylated, dodecanol ethoxylated, cetostearyl alcohol ethoxylated, tetramethyldecindiol ethoxylated, polyoxyethylene nonyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene behenyi ether, polyoxyethylene polyoxypropylene block copolymers, polyoxyethylene polyoxypropylene cetyl ether, polyoxyethylene polyoxypropylene beheryi ether, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene stearylamine, polyoxyethylene ol eylarr.ine, polyoxyethylene stearic acid amide, polyoxyethylene oleic acid arrdde, polyoxyethylene castor oil, polyoxyethylene acietyl ether, polyoxyethylene lanolin ether, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene glyceryl monooleate, polyoxyethylene glyceryl monostearate, polyoxyethylene propylene glycol monostearate, polyoxyethylene sorbitan monolaurate, and sorbitan monolaurate. The non-ionic surfactants, which have an ethylene diamine group, substituted with groups of polyoxyethylene, Dolyoxypropylene or mixtures thereof, are of special interest in the developing solution. Examples of such non-ionic surfactants are the TETFONIC surfactans commercially available from BASF.
The non-ionic surfactants preferably have an average molecular weight ranging from 500 to 10,000, preferably from 1000 to 5000. They can be comprised individually or as admixture of two or more ':crrtpou:,ds in an amount ranginq from 0.05 to 5S, preferably from O.i TO 1 % by weignt of the total developing solution.
The developers used in zhs present invention may simulT:aneoiisl'- another surfactant for the purpose of improving dev'eloping propei'T-ies thereof. By incorporating surfactants to the developer solution, the surface tension reduces drastically and the developer, so]ution becomes effective - i.e. removal of the non-imaqe areas wit-hc'it occur rence of stain/toning ~ at a lower pH compared co ~he same oeveloper solution wirhour a surfactant. The developer may comprise an ionic surfactant such as anionic or cationic surfactant,
non-ionic surfactant and/or arr.photeric surfactants such as Librateric AJv30 (trademark from Libra Chemicals Limited). Examples of Such surfactants include salts of higher alcohol (C8 - C22) sulfuric acid esters such as sodium salt of lauryl alcohol sulfate, sodium salt of octyl alcohol surface, ammonium salt of lauryl alcohol sulfate, Teepol B-81 (trade mark, available from Shell Chemicals Co., Ltd.) and sodium alkyl sulfates; salts of aliphatic alcohol phosphoric acid esters such as sodium salt of cetyl alcohol phosphate; alkyl aryl sulfonic acid salts such as sodium salt of aodecylbenzene sulfonate, sodium salt of isopropylnaphthalene sulfonate,sodium salt of dinaphthalene disulfonate and sodium salt of metanitrobenzene sulfonate; sulfonic acid salts of aikylamides such as Ci7.n33CON (CH3) CH2CH2S03Kia and sulfonic acid salts of dibasic aliphatic acid esters such as sodium dioctyl sulfosuccinate and sodium dihexyl sulfosuccinate, These surfactants may be used alone or in combination. Particulariy preferred are sulfonic acid salts. These surfactants may be used in an amount of generally not more than 5 % by weight and preferably nor more than 3 % by weight.
The cationic surfactant used in the developer may include amine salts, quaternary ammonium salts, phosphoniLiin salts, suifo.nium salts and the like. Examples of the am.ine salts are primary amine salts, secondary am.ine salts, tertiary amine salts, and imidazoline salts. Examples of the quaternary ammonium salts include tetraalkyl quaternary ammonium salts, trialkyl benzyl quaternary ammonium saits, aikyl pyridinium salts, alJiyl quinolinium salts^ irr.idazcliniurr. salts and benzim.idazolinium salts.
Exemplary amphoteric surfactants include betaine derivatives, such as, for example, alkylamidopropyl betaine, alkyldimetny1 Detaine, bisnydroxyethyl betaine, alkylamido propyl betaine, lauryl betaine, and rhe 11ke, glycine derivatives, such as, for example, cocoarr.chccarbcxy glycinate, lauroaniphocarboxy glycinate, caprylamphocarboxy glycinate, oieoamphocarboxy glycinate,
oleoamphopolycarboxy glycxnate, N-aikyl glycinate, and the 1 ike, imino derivatives, such as, tor example, cocoiminodipropionate, octyliminod:! propionate, and the li ke, imidazoline derivatives , such as, fcr example, coconut imiaazoline, and the like, lecithin derivatives, and arcinocarboxylic acids. These amphoreric surfactants pieferably nave an average molecular weight ranging from ICO r.o 10,000, preferably from 1,000 to 5,000. They can be comprised individually or as admixture of two or more compounds.
The above described anionic and amphoteric surfactant can be present in the developing solution of the present invention in a total ainount ranging from 0>5 to 101, preferably from 1 to 6%, and more preferably from 1 to 3% oy weight of the total developing solution.
In order to enhance developing stability of the developers, the following compounds may simultaneously be used. Examples of such compounds are neutral salts such as NaCl, KCl and KBr as disclosed in JN'A- 53- 75 152; chelating agents such as EDTA and NTA as disclosed in JN-A- 58- 190 952 (U.S-A- 4 469 776), complexes such as [Co (NH. j ,„]C1, as aisclosed in JK-A- 59- 121 336 {US-A-- 4 606 995); lonizable compounds of elements of the group Ila, Ilia or Illb of ■Lhe Periodic Table such as those disclosed in JK-A- 55- 25 100; anionic or amphoteric surfactants such as sodium alkyl naphthalene sulfonate and K-tetradecyl-N,N-dihydroxyethyl betaine as disclosed in JN-A- 50- 51 324; tetramethyldecyne diol as disclosed in US-A- A 374 920; non-ionic surfactants as disclosed in JK-A- 60- 213 94 3; cationic polymers such as methyl chloride quaternary products of p-dimethylaminomethyl polystyrene as disclosed in JN-A- 55- 95 546; amphoteric polyelectroiytes such as coDolyrr.er of vinylbenzyl trimethylammonium chloride and sodium acrylate as disclosed in JN-A- 56- 142 528; reducing inorganic salts such as sodium sulfite as disclosed in JN-A- 57- 192 952 fOS-A- 4 4 67 02 7) and alkaline-soluble m.ercapto com.pounds or thioether compounds such as thiosalicylic acid, cysteine and chioqlycolic acid; inorganic lithium compounds such as lithium chloride as disclosed in JN-A- 56- 59 444; organic lithiumi compounds sv.ch as lichiuir, benzoate as disclosed in JN-A- 50 34 442 ; Dtganometallic surfactants concaining Si, Ti or the like as disclosed in JN-A.- 59- "^5 25 5; organoboron com.pounds as disclosed in JN-A- 55- 84 241 (US-A- 4 500 525); quaternary ammonium salts such
23 tstraaikyiammonium oxides as disclosed in EP-A- ICl CIO; and bac-.sricides such as sodium dahydroacetate as disclosed in JN-A- 63- 226 657.
In a preferred embodiment of rhe present invention, the ^Tilocking agent is present in a developing solution at a concentration of at least 0.02 g/1, preferably in a concentration ranging between 0.05 and 30 g/1, rriore preferably between 0.05 and 15 g/1, more preferably between 0.0 5 and 5 g/i, most preferably between 0.1 and 1 g/1.
Replenishing solution
During the development the non-image areas of the coating are removed with an aqueous alkaline developer solution optionally in combination combined with mechanical rubbing, e.g. by a rotating brush. During the development step, any water-soluble layer present is preferably also removed- The development is preferably carried out at temperatures of from 20 to 40 °C in automated processing units as customary in the art.
To perforrri development processing stably for a long time period, it is particularly important to control the strength of elkaii and the concentration of silicates and other ingredients in the developer. Therefore, a replenishing solution, hereinafter also referred to as replenisher, is added to the developing solution, usually in small amounts such that a stable development processing can be performed over a long time period without exchanging the developer. Therefore, it is also important that the concentration of the blocking agent of the present invention is present in the developing solution at a sufficiently high level in order to maintain the developing latitude or exposure latitude of the precursor and this can be realised by adding a replenishing solution comprising the blocking agent of the present invention.
For regeneration, the replenishing solution, hereinafter also referred to as repienisher, preferably comprises active ingredients of the developing solution such as alkaline agent. The replenishing solution is added continuously or in small amounts to the developing solution auring or after the aeveloping process in order to regulate r ne coricen-.ration of the active ingredients in the developing
soion ar a level sufficient.ly high or at a constant level such -„hat "he development of image-wise exposed precursors remains at a constant level. The required amcunts of regenerated rriaterisl must be zailoreG to tne developing apparatuses used, daily plate T.r.rovghpuzs, image areas, ezc. and are in general from 1 to i5C ml per square neter of plate precursor. The aadition of replerilsher can be regulatea, for example, by measuring the conductiviry of the developer as described in EP-A 0,556,690 .
In the method for development processing, any known means of suppJ eraenting a replenisher for developer may also be employed. ^'xamples cf sach methods preferably ased are a method for interjrattently or continuously supplementing a replenisher as a function of the amount of plates processed and time as disclosed in JN-A- 56- 115 039 (GB-A- 2 046 931), a method comprising disposing a sensor for detecting the degree of light-sensitive layer dissolved out in the middle portion of a developing zone and supplementing the replenisher in proportion to the detected degree of the light- sensitive layer dissolved out as disclosed in JN-A- 58- 95 349 I'US-A- 4 537 496) ; a method comprising determining the impedance value of a developer and processing the detected Impedance value by a computer to perform supplementation of a replenisher as disclosed in GB-A- 2 2 08 2 49.
In a preferred embodiment of the present invention, the blocking agent is present in a replenishing solution at a concentration of at least 0.05 g/1, preferably in a concentration ranging between 0.1 and 30 g/1, more preferably between 0.5 and 20 g/l, more preferably between 0.5 and 15 g/1, most preferably between 0.5 and 10 g/1. In another preferred embodiment, the ratio of the concentration of the blocking agent in the replenishing solution, containing at least 0.05 g/1 of the blocking agent, and in the developing solution is preferably between 0.5 and 100, more preferably between 1.1 and lOO, most preferably between 2 and 50.
The replenishing solution has preferably a pH value of at least 10, more preferably of at least 11.5, most preferably of a- least 12. There is no specific upper limit for the pH but the pH is usually rot higher than 14.
In anc'her embodiment of the present invention, more than one replenishing .polutions can be used for adding to the developing solution during or after the development processing and these
rspier.ishers may contain aifferenr types in different amoun-cs of blocking agents of the presen- invention, and also different types in cjifferent amounts of other coinpounds for improving ^he a e51 o p rri e n ^ processing.
I'n a mere preferred eiribodiment of the present invention, the fres:^ cieveioping solution at starting the development processing for the first time is essentially free of the blocking agent of the present invention and during or after processing precursors, a replenishing solution, containing a blocking agent of the present invention, is added to the developing solution and/or a layer of the precursor, comprising a blocking agent of the present invention, is removed at least partially in "ne developing solution.
The heat-sensitive lithographic printing plate precursor of the present invention comprises a support having a hydrophilic surface or which is provided with a hydrophilic layer, and, on said support, a heat-sens itive coating.
Support
The support of the lithographic printing plate precursor has a hydrophilic surface or is provided with a hydrophilic layer. The support may fae a sheet-like material such as a plate or it may be a cylindiical element such as a sleeve which can be slid around a print cylinder of a printing press. A preferred support is a metal support such as aluminum or stainless steel. The metal can also be laminated to a plastic layer, e.g. polyester film.
h particularly preferred lithographic support is an electrochemically grained and anodized aluminum support. Graining and anodization of aluminum is well known in the art. The anodized aluminum support may be treated to improve the hydrophilic
roperties of its surface. For example, the aluminum support may he siiicated by treating its surface with a sodium silicate solution at
Isva^-C-d temperature, e.g. 9 5°C. Alternatively, a phosphate treatment may be applied which involves treating the aluminum oxide surface with a phosphate solution that may further contain an inorganic fluoride. Further, the aluminum oxide surface miay be rinsed with a citric acid or citrate solution. This treatment may be carried out at room temperature or may be carried out at a
slightly elevat-Sd temperature or about 30 to SCc. A further interesting treatment involves rirising the aluminum o^cide surface v.'i th a Dicaroonate solution. Still further, the aluminum oxide surfa'::= may be treated with polyvinylphosphonic acici, polyv Lnyirrietrjvlphosphonic acid, phosphoric acid esters of polyvinyl .7 Coating
The heat-sensitive coating, which is provided on the support, may be positive-working or negative-working. A positive-working hsat-sensitive coating is preferred. The coating of a positive- rt-or king hear.-sensitive coating does not dissolve in an alkaline developing solution in the unexposed areas and becomes soluble in the exposed areas within the time used for developing the plate. The coating preferably comprises an infrared absorbing agent and an alkaline soluble oleophilic resin whereof the solubility in an alkaline developing solution is reduced in the coating and whereof the solubility in an alkaline developing solution is increased upon heating or lP-.-radiatiDn. The coating preferably further comprises a dissolution inhibitor whereby rate of dissolution in an alkaline developing solution is reduced. Due to this solubility differential the rate of dissolution of the exposed areas is sufficiently higher than in the non-exposed areas.
In a preferred emibodiment of the present invention, the heat- .=;ensicive coating comprises a first polymer which is a phenolic resin such as novolac, resol or a polyvinylphenolic resin; novolac is nor? preferred. Typical examples of such polymers are described in DE-A-400742S, DE-A-40273C1 and DE-A-4445820. Other preferred poJ ymers are phenolic resins v-.'terein the phenyl group or the hydrox}' group of the phenolic monomeric unit are chem.ically modified with an
organic substituer.t as described in EP 894 622, EP 901 9C2, EF 953 662, W099/63407, EP 934 822, EP 1 072 432, US 5,641,608, EP 9B2 123, WOC4/035310, W004/0356S6, W004/035 64 5, WOO'3/C35687 or EP
] 50c' 58 .
The novclac resin or rssol resin may be prepared by po j.ycondens.?,T; on oi ar leasr one meraber selected from aronatic hydrocarbons such as phenol, o-cresol, p-cresol, m-eresol, 2,5- xylenol, 3,5-xylenol, resorcinol, pyrogallol, bisphenol, Disphenol A, rri sphenol, o-ethylphenoi, p-etylphenol, propylphenol, n- butylphenol, t-butylphenol, octyl-phenol, 1-naphtol and 2-naphtol, v.'irh ar least one aldehyde or Ketone selected from aldehydes such as formaldehyde, glyoxai, acetoaldehyde, propionaldehyde, benzaldehyde and furfural and ketones such as acetone^ methyl ethyl ketone and methyl isobutyl ketone, in the presence of an acid catalyst. Instead of formaldehyde and acetaldehyde, paraformaldehyde and paraldehyde may, respectively, be used.
The weight average molecular weight, measured by gel permeation chromatography using universal calibration and polystyrene standards, of the novolac resin is preferably from 500 to 150,000 cj/'reol, more preferably from 1,500 to 50,000 g/mol.
The poly(vinylphenol) resin may also be a polymer of one or more hydroxy-phenyl containing monomers such as hydroxystyrenes or hydroxy-phenyl (meth)acrylates, Examples of such hydroxystyrenes are o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, 2-(o- hydroxyphenyJipropylene, 2-(m-hydroxyphenyl)propylene and 2~(p- hydroxyphenyi)propylene. Such a hydroxystyrene may have a
substituent such as chlorine, brorr.ine, iodine, fluorine or a C1-4
alkyl group, on its aromatic ring. An example of such hydroxy-phenyl (methiacrylate is 2-hydroxy-ph6nyl methacrylate,
Tne poly(vinylphenol) resin may usually be prepared by polvrr.erizing one or more hydroxy-phenyl containing monomer in the presence of a radical initiator or a cationic polymerization initiator. The poly [vinylphenol) resin may also be prepared by copolymerizing one or more of these hydroxy-phenyl containing monomers with other monomeric compounds such as acrylate monomers, msthacrylate inonomers, acrylamide monomers, methacrylamide monomers, vinyl monom.ers, aromatic vinyl monomers or diene monomers.
The weight average molecular weighr, measured by gel permeation
chrorr.ar.ography using universal calibration and polystyrene
standards , of the poly (vinyl phenol) resin is preferably from 1. 'inn 2CC', 000 g/rrrol, more preferably from 1,500 to 50,000 g/iriol, Examples of phenolic resins are:
POL-CI: AlKOVOL SPN4 52 is a sclution of a novolac resin, 4 0 s oy weight in Dowanoi PM, obtained from CLARIANT GmbH.
Dowanoi PM consists of l-merhoxy-2-propanol (>99.5 %) and 2~methoxy- 1-propanol ( POL-02: ALNOVOL SPN400 is a solution of a novolac resin, 44 % by weight in Dowanoi PMA, obtained from CLARIANT GmbH.
Dowanoi PMA consists of 2-methoxy-l-methyl-ethylacetate.
POL-03: ALMOVOL HPKIOO a novolac resin obtained from CLARIANT GmbH.
?aL-C4: DORITE PD443 is a novolac resin obtained from BORDEN CHEM. INC.
POL-05; DURITE SD423A is a novolac resin obtained from BORDEN CH5M. INC.
POL-Og; DURITE SD126A is a novolac resin obtained from BORDEN CHEM. INC.
POL-C?: BAKELITE 6866LB02 is a novolac resin obtained from 3AKELITE AG.
POL-08: BAKELITE 6866LB03 is a novolac resin obtained from BAKELITE AG.
POL-CS; KR 40C/8 is a novolsc resin obtained from, KOYO CHEMICALS
POL-10: HRJ 1085 is a novolac resin obtained from SCHNECTADY INTERNATIONAL INC.
I.-L-Ij.: H?;!' 2606 is a phenol ncvolac resin obrained froia JCHNECTADY INTERNATIONAL INC.
POL-lz: LiNCUR CMM is a copciyraer of 4-hydroxy-styrene and merhvl msthacrylate obtained from SIBER HEGNER.
In another preferred embodiment of the present invention, the neat-sensitive coating further comprises a second polymer which is insoluble in v.;ater and soluble in an alkaline solution.
Ir: accordance with a more preferred embodiment of che present i nvention, tne heat-sensitive coating comprises a heat-sensitive layer and an intermediate layer. The intermediate layer is present between the heat-sensitive layer and the hydrophilic surface of the support. In a still more preferred embodiment, the heat-sensitive flayer comprises a first polymer and optionally an inhibitor, and the ir.y.er-nediate layer comprises a second polymer.
The second polymer is preferably an organic polymer which nas acidic qroups with a pKa of less than 13 to ensure that the layer is s";luble cr at least swellable in aqueous alkaline developers. Advantageously, the binder is a polymer or polycondensate, for example a pcdyester, a polyamide resin, an epoxy resin, an acetal resin, an acrylic resin, a m.ethacrylic resin, a styrene based resin, a polyurethane resin or polyurea.
The second polymer has more preferably one or more functional groups selected from the list of
ii) a sulfonam.ide group such as -S02-NH-R^ wherein R^ represents a hydrogen cr an optionally subscituted hydrocarbon group such as an optionally substituted alkyl, aryl or heteroaryl group, ;ii) an active imide group such as -SO2-NH-CO-R'', -SO.-NH-SO^-r'' or ■
CT-Nn-SO'/-R" wherein r'"' represents a hydrogen or an optionally
substituted hydrocarbon group such as an optionally substicuted
alkyl, aryl or heteroaryl group,
■■ i ii a car boxy late group,
IIV) a sulfonate group,
;v'; a phcsphonate group, and
'vi) a phosphate group;
a su]fonamide group or an active imide group are more preferred; most preferred are poiymers selected from a copolymer comprising a M-benzyl-maleimnde monomeric unio or a monorrieric unit comprising a fcnamide group as descrioed in EP-A 933 682, EP G 894 622 (page to page c line 30!, SP-A G 982 125 (page 3 line 56 to page

o
I c;.JU
.:ne 5:, EP-A 1 072 432 (page 4 line 21 to page IG line

WO 99/63407 (page 4 line 13 to page 9 line 37) .
O'her polymers having an acidic group are polycondensates and polymers having free phenolic hydroxyl groups, as obtained, for example, by reacting phenol, resorcinol, a cresol, a xylenol or a trimethyiphenol with aldehydes, especially formaldehyde, or ketones. Condensates of sulfamoyl- or carbamcyl-substituted aromatics and aldehydes or ketones are also suitable. Polymers of bismethylol- substiouted ureas, vinyl ethers, vinyl alcohols, vinyl acetals or vinylamides and polymers of phenylacrylates and copolymers of hydroxy-phenylmaleimides are likewise suitable. Furthermore, polymers having units of vinylaromatics, N-aryl(meth)acrylamides or aryl (meth}acrylates may be mentioned, it being possible for each of these units also to have one or more carboxyl groups, phenolic nydroxyl groups, sulfamoyl groups or carbamoyl groups. Specific examples include polymers having units of 2-hydroxypheny1 (meth)acrylate, of N-(4-hydroxyphenyl)(meth)acrylamide, of N-(4- sulfamoylphenyl)-(meth)acrylamide, of N-(4-hydroxy-3,5- dimethylbenzyl)-(meth)acrylamide, or 4~hydroxystyrene or of hydroxyphenylmaleimide. The polymers may additionally contain units of other monomers which have no acidic units. Such units include vinylarorriatics , methyl (meth) acrylate, phenyl (meth) acrylate, benzyl ;rr;eth; acrylate, methacrylamide or acrylonitrile.
Dissolution inhibitor
Ir. a preferred embodiment of the present invention, the heat- sensitive coating or the heat-sensitive layer also contain one or more dissolution inhibitors. Dissolution inhibitors are compounds which reduce the dissolution rate of the hydrophobic polymer in the aqueous alkaline developer ao the non-exposed areas of the coating and '.'.■he-rein this reduction of the dissolution rate is destroyed by rhe heat generated during the exposure so that the coating readily

aissclves in -he developer at exposed areas. The dissolution inhibitor exhibits a substantial latitude in dissolution rate betvjeen the exposed and non-exposed areas. By preference, iihe dissoiULJon inhibitor has a good dissolution rate iati::ude when rhe exposec coating areas have dissolved completely in the developer oefore the non-expcsed areas are attacked by the developer to such an extent tnat the ink-accepting capability of the coating is affected. The dissolution inhibitor (s) can be added to the layer which comprises the hydrophobic poiym.er discussed above.
The di ssolution rate of the non-exposed coating in che deve]oper is preferably reduced by interaction between the hydrophobic polymer and the inhibitor, due to e.g. hydrogen bonding between these compounds. Suitable dissolution inhibitors are preferably organic compounds which comprise at least one aromatic group and a hydrogen bonding site, e.g. a carbonyl group, a sulfonyl group, or a nitrogen atom which may be quaternized and which may be part of a heterocyclic ring or which may be part of an amino substituent of said organic compound. Suitable dissolution inhibitors of this type have been disclosed in e.g. EP-A 825 S27 and
Water-repellent polymers represent an another type of suitable dissolution inhibitors. Such polymers seem to increase the developer resistance of the coating by repelling the aqueous developer from the coating. The water-repellent polymers can be added to the layer comprising the first polymer and/or can be present in a separate layer provided on top of the layer with the first polymer. In the latter embodiment, the water-repellent polymer forms a barrier layer wnich shields the coating frorr: the developer and the solubility of the barrier layer in the developer or the penetrability of the barrier layer by the developer can be increased by exposure to heat or infrared light, as described in e.g. EP-A S64420, EP-A 950 517 and VJ099/2172 5. Preferred examples of the water-repellent polymers are pclym.ers comprising siloxane and/or perfluoroalkyl units. In one embodiment, the coating contains such a water-repellent polymer in
an amount between 0.5 and 25 mg/m^, preferably between 0.5 and 15
2 2 mg/m and most preferably between 0.5 and 10 mg/m , vJhen the water-
repel len L polymer is also ink-repelling, e.g. in the case of
2
polysiloxanes, higher amounts than 25 mg/m can result in poor ink-
accept ance of the non-exposed areas. An amouni. ^^ower than 0. 5 mg/m^
on cne other hand may lead oo an unsatisfactory development rssi5;tance. The polysiloxane rr.ay tas a linear, cyclic or complex cioss-1inkea polymer or copclymer. The rerm polysiloxane compound shall include any compound which contains more than one siloxane group -SiiR,?';-0-, wherein R ana R' are optionally substiru-ed aikyi or aryi groups. Preferred siloxanes are phenylalkylsiloxanes and dia 1kylsiloxanes. The number of siloxane groups in the ^cojpolymsr is at least 2, preferably at least 10, more preferably at least 20. It may be less than 100, preferably less than 60. In anocher embodiment, the water-repellent polymer is a block-copolymer or a graft-copolymer of a poly(alkylene oxide) block and a block of a polymer comprising siloxane and/or perfluoroalkyl units. A suitable copolymer comprises about 15 to 25 siloxane units and 50 to 70 alkylene oxide groups. Preferred examples include copolymers comprising phenylmethylsiloxane and/or dimethylsiloxane as well as ethylene oxide and/or propylene oxide, such as Tego Glide 410, Tego Wet 265, Tego Protect 5001 or Silikophen P50/X, all commercially availat)le from Tego Chemie/ Essen, Germany. Such a copolymer acts as a surfactant which upon coating, due to its bifunctional structure, autom.atically positions itself at the interface between the coating and air and thereby forms a separate top layer even when the whole c:oating is applied from a single coating solution. Simultaneously, such surfactants act as a spreading agent which improves tne coating quality. Alternatively, the water-repellent polymer can be applied in a second solution, coated on top of the layer comprising the hydrophobic polymer. In that embodiment, it may be advantageous to use a solvent in the second coaring solution that is not capable of dissolving the ingredients present in the first layer so that a highly concentrated water-repellent phase is obtained at the top of tne coating.
Development accelerator
Preferably, also one or more development accelerators are included in the inea'c-sensitive coating or in the heat-sensitive layer, i.e. compounds which act as dissolution prom.oters because ti'iey are capable of increasing rhe dissolution rate of the non- exposed coat :.ng in the dei^eloper, Tlie simultaneous application of aissclution inhititors and accelerators allows a precise fine tuning of the dissolution behavior of the coating. Suioable dissolution accelerators are cyclic acid anhydrides, phenols or organic acids. Exarapies of the cyclic acid anhydride include phthalic anhvdride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, alpha -phenylmaleic anhydride, succinic anhydride, and pyroinelliric anhydride, as described in U.S. Patent No. 4,115,128. Examples of ohe phenols include bisphenol A, p-nitrophenol, p- ethoxyphenol, 2,4,4'-trihydroxybenzophenone, 2,3,4-trihydroxy- Denzophenone , 4-hydroxybenzophenone, 4,4',4"-trihydroxy- triphenylmethane, and 4,4',3",4"-tetrahydroxy-3,5,3',5'- tetramethyltriphenyl-methane, and the like. Examples of the organic acids include sulfonic acids, sulfinic acids, alkylsulfuric acids, phosphonic acids, phosphates, and carboxylic acids, as described in, for example, JP-A Nos. 60-88,942 and 2-96,755. Specific examples of these organic acids include p-toluenesulfonic acid,
aodecylbenzenesulfonic acid, p-toluenesuifinic acid, ethylsulfuric acid, phenylphosphonic acid, phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, adipic acid, p-toluic acid, 3,4-dimethoxybenzoic acid, phthalic acid, terephthalic acid, 4-cyclohexene-l,2-dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, and ascorbic acid. The amount of the cyclic acid anhydride, phenol, or organic acid contained in the coating is preferably in the range of 0.05 to 20% by weight, relative to the coating as a whole.
Blocking agent
In accordance with a preferred embodiment of the present invention, the blocking agent is added to the developing solution by removing at least part of the precursor wherein said blocking agent of che present invention is present. In this embodiment, the layer comprising one blocking agent is removed at least partially during developrrisnt, preferably, the blocking agent is present in the heat- sensitivs coating or in the heat-sensitive layer and/or the interraediate layer and/or in a top layer and/or in an optional other layer on tne back side of the suDDoro.
According "co a more preferred erabodiment, rhe blocking agent is preser.c in the heat-sensitive coating or in the heat-sensitive layer anc/or the intermediate layer whereby the layer comprising the t■ocK i ng agent is removed at rhe exposed areas in the developing solut i or. In tnis way, it is hignly advantageous that the ,imount of Dlocl-: L ng agenr added to the developing solution is in correspondence with the amount of precursors developed. When the precursor has a toplayer which is removed only on the exposed areas, the blocking agent can also be present in the toplayer and the addition of blocking agent is also in correspondance v.'ith the exposed areas. In Lhis way the blocking agent is released in proportion with exposed areas and the amount of blocking agent present in such an image-wise
dissolving coating ranges preferably between 0.01 g/m^ to 2,5 g/m^,
2 2
more preferably between 0.05 g/'m to 1.5 g/m , most preferably
between 0.07 g/m'^ to 1.0 g/m^.
According to another preferred embodiment of the present invention, the blocking agent is present in layer on the back side of the support and this layer is removed at least partially in the deve-oping solution. In this way the addition of blocking agent is proportional with the surface of the precursors which are developed, in an analogous way, the blocking agent can also be present in a top layer which is removed also in the non-exposed areas. In this way the blocking agent is released in proportion with surface of the precursor and the amount of blocking agent present in such a layer ranges preferably between O.Cl g/m^ to 2.0 g/m^, more preferably
x ? 2
between 0.05 g/m to 1.5 g/m", most preferably between 0.0^ g/m to 1.0 g/re".
In order to obtain an optimum blocking activity, it is aovanrageous to combine a precursor, having the blocking agent in a coating in a lower concentration, preferably between 0.005 and 0,35 g/m"", with a developing solution (or replenisher) , having a concentration of the blocking agent, preferably in the range of G.l and 3 g/1.
LxDOSi.ire

The material can be image-wise exposed directly witrj heat, e.g.

thermal head.
or indi
V iTiean^
irectly by infrared light, which

IS preferably converted into heat by an infrared light absorbing "ompourd, v.-mcn ir.ay be a dye or pigment having an absorpt.ion maKiraum :n the infrared wavelength range. The infrared light absoroing dye o: pig:r.ent is preferably present in rhe heat-sensitive coating or the heat-sensitive layer and typically in a concentration ranging oetween 0.25 and 10.0 wt.?, more preferably between 0.5 and 7.5 wt.% relative to the coating as a whole. Preferred IR-absorbing compounds .sre dyes such as cyanine or raerocyanine dyes or pig.tients such as carbon black. A suitable componncl is the following infrared dye IR- 1 :
(IR-1i
wherein X is a suitable counter ion such as tosylate,
The heat-sensitive coating, or the heat-sensitive layer and/or tne intermediate layer, may further contain an organic dye which absorbs visible light so that a perceptible image is obtained upon irti.age-wise exposure and subsequent development. Such a dye is often called contrast dye or indicator dye. Preferably, the dye has a blue color and an absorption maximum in the wavelength range netween oOOn.Ti and 750 nm. Although the dye absorbs visible light, it preferably does not sensitize the printing plate precursor, i.e. the coating does not become more soluble in the developer upon exposure tc visible light. Suitable examples of such a contrast dye are the quaternized triarylmiethane dyes.
and/or
According to a preferred embodiment, the contrast dye is nresent in the heat-sensitive coating, or the heat-sensitive layer
:he intermediate layer.

riccoraing ro a highly preferred embodiment, rhe infrared light absor;-ing compound is concentrated in the heat-sensitive coating or he£;t-sens:.tive layer.
The printing plate precursor of the present invention can be •^^xpossTi T-.o infrared light with LEDs or a laser. Preferably, a laser emitting near infrared light having a wavelength in the range from about 7 50 to about 1500 nm is used, such as a semiconductor laser diode, a Nd;YAG or a Nd:YLF laser. The required laser power depends on the sensitivity of the image-recording layer, the pixel dwell lime of the laser beam, which is determined by the spot diameter
2
■:rypicai value of modern place-setters at 1/e of ma.xijnum
intensity : 10-25 pm), the scan speed and the resolution of the exposure apparatus (i.e. the number of addressable pixels per unit of linear distance, often expressed in dots per inch or dpi; typical value : 1000-4 000 dpi}.
Two types of laser-exposure apparatuses are commonly used: internal (ITD) and external drum (XTD) plate-setters. ITD plate- setters for thermal plates are typically characterized by a very high scan speed up to 500 m/sec and may require a laser povjer of several Watts. XTD plate-setters for thermal plates having a typical laser power from about 200 mW to about 1 W operate at a lower scan speed, e.g. from 0.1 to 10 m/sec.
The known plate-setters can be used as an off-press exposure apparatus, which offers the benefit of reduced press down-time. XTD plate-setter configurations can also be used for on-press exposure, offering the benefit of immediate registration in a multi-color press. Mere technical details of on-press exposure apparatuses are aescribed in e.g. US 5,174,205 and US 5,163,368.
In the development step, the non-image areas of the coating are removed by immersion in an aqueous alkaline developer, which may be combined with m.echanical rubbing, e.g. by a rotating brush. The developer preferably has a pK above 10, more preferably above 12. The developer may further contain a poly hydroxyl compound such as e.g. sorbitol, preferably in a concentration of at least 40 g/1, and a_so a Dolyethylene oxide containing compound such as e.g. Supronic 325, comjnercially available from RODTA, preferably in a concentrstior; of at most 0.15 g/1 -
The clevelopinent step may be followed by a rinsing step and/or ■=! gunn-.ing stec. The gumming step involves post-treatment of the 1 i-hographic printing plate v.'rtn a gum solution. A gum solution is i-vpicaiy an aqueous 11quid wni ch comprises one or more sui face protectve compounds that are capable cf protectinc rhe lirhogra^ itTiage or a prinring plate against contamination or damaging. Suitable exair.ples of such compounds are film-forming hydroohilic polymers or surfactants.
Tne plate precursor can, if required, be post-treated with a ^ri'^itabl e correcting agent or preservative as known in the art. To ::ncrea.= e the resistance of the finished printing plate and hence to extend the run length, the layer can be briefly heated to elevated temperatures ("baking"}. The plate can be dried before baking or is dried during the baking process itself. During the baking step, the plate can be heated at a temperature which is higher than the glass "ransit.ion temperature of the nea;:-sensitive coating, e.g. between lOO^C and 230'C for a period of 40 seconds to 5 minutes. Baking can be done in convenziOTial hot air ovens or by irradiation wirh lamps emitting in the infrared or ultraviolet spectrum. As a result of this baking srep, the resistance of the printing plate to plate cleaners, correction agents and UV-curable printing inks increases. Such a thermal pcst-treatment is described, inter alia, in DE 1,447,963 and GB 1,154,749.
The printing plate thus obtained can be used for conventional, s.c-called wet offset printing, in which ink and an aqueous dampening liquid is supplied to the plate. Another suitable printing method uses so-called single-fluid ink without a dampening liquid. Suitable single-fluid inks have been described in US 4,045,232; US 4,981,517 and US 6,140,392. In a most preferred embodiment, the single-fluid ink comprises an ink phase, also called the hydrophobic or oleophilic pnase, and a polyol phase as described in WO 00/32705.
EXAMPLES
Preparation of Binder-02

In a 250 mi reactor, 162 rninol of Monomer-Ol, 21 . 3g (132 mmol) o-?nz.yl acrylamide, 0.43 g {6 miriolj acrylic acid and 103g gamma-
were added and the rr.^xture was heated to 140' C, while stirring at iOG rpiu. h constanr flow of nitrogen was put over the reactov . Afcer di ssolution of al^ ■::he components, the reactor was ::ociea to iOO c. 0.35 ml Trigonox DC5C, commercially available from AK20 NOBEL, was added followed by the addrtron of 1.39 ml Trigonox 141, commercially available from AKZO NOBEL, in 3,43 ml butyrolactone. The polymerization was started and the reactor was heated to 140°C over 2 hours while dosing 1.75 ml Trigonox DC50. The mixt'jre was stirred at 400 rpm and the polymerization was allowed to continue for 2 hours ar 140"C. The reaction mixture was cooled to 120°C and the stirrer speed was enhanced to 500 rpm, 85.7 ml 1- methoxy-2-propanol was added and rhe reaction mixture was allowed to cool down to room temperature.
Binder-01 was analyzed with 'H~NMR-spectroscopy and size exclusion chromatography, using dimethyl acetamide/0.21 % LiCl as eluent on a 5x mixed-B column and relative to polystyrene standards.
I Mn 1 PD
Binder-01 23500 ; 1 67000 2 . 84

The reaction mixture was cooled to 40°C and the resulting 25 weight % polymer solution was collected in a drum.
CH,

Compound-01:
n'
c
impound-0 2:
:;mpo'^na-C3 :
Compound-04:
ComDCLind-Oo:
Preparation of the lithographic support.
A 0.3C mm thick aluminum foil was degreased by immersing the foil in an aqueous solution containing 34 g/1 of sodium hydroxide at 7 C: C for 6 seconds and rinsed with deroineralised water for 3.6 seconds. The foil was then electrochemically grained during 8 seconds using an alternating current in an aqueous solution comiaining 15 g/1 HCl, 15 g/1 S04^ ions and 5 g/1 Al"^"^ at a
2
ceiTiperature of 37 °C and a current density of 100 A/dm , The aluminum
foil W3S then desmutted by etching with an aqueous solution coniiaining 145 g/1 of sulfuric acid at SCC for 5 seconds and rinsed wirh demineraiized water for 4 seconds. The foil was subsequently subjected to anodic oxidation during 10 seconds in an aqueous solution containing 145 g/1 of sulfuric acid at a temperature of
2
57 "c and a current density of 25 A/dni , then washed with
dem.inerali zed water for 7 seconds and post-treated for 4 seconds v;ith a solution containing 2.2 g/1 of polyvinylphosphonic acid at 'O^C, rinsed wirh demineralized warer for 3.5 seconds and dried at 120°C for 7 seconds.
The support thus obtained was characterized by a surface roughness Ra of 0.35-0.40 jjiti (measured with interferometyer NTllOO)
2
and an anodic weight of 3.0 g/m".
Preparation of the printing plate precursor ??P-01
The FPP-Cl was produced by first applying a first coating layer defined in Table 1 onto the above described lithographic support. The coating was applied at a v;et coating thickness of 2C ym and rhen
drieo dL

Cor^DCsition of the solution of the first coatinq lavei
Amount oi proaac.
'iil-, " i.
INGREDIEKTS
■ g;

351.54
Li-wariD-. PK i

THF
1698.99

661 .86
253.7'
33. 84
Eander~01 ;25 % by weight; (3)
:ry3tai Violet (1% by weight) (4)
Tegoglaae 410 [l % by weight) (5)

:l)Dowanol PH is l--methoxy-2-propanGi, commercially available from DOW CHEMICAL Company.
[2] THF is tecrahydrofuran.
i3;Binder-C1, preparation see above.
( ■: 5)TEG0GLIDE 410 is a copolymer of polysiloxane and poly (alkylene oxide) , corraTiercially available from CEGO CHEMIE SERVICE GmbH.
On the first coated layer, a second layer as defined in Table 2 was coated at a wet coating thickness of 25 pm and dried at 135°C.
Table 2; Composition of the solution of the second coating layer
INGREDIENTS Amount of product
(g)
Dowanoi FM {1) 600.73
Alnovol SPN^52 (40 % by weight; (2; 132.07
I
1TMCA i1n % Dv we i ght) (3) 66 .20
2.74
Crystal Violet {1% by weight) (5)
1 80.23
1— — —
Tegovjet 26r! (1 % by weight) (6) 11.23
ITeaoolide 410 il s bv weight) C?)
i ^ ' 3 6.90

Amount of produc"
(g)
i b ■■■ . y i
■■ _; S^s 'i dCx s J .
■i A±ncvo: S?N4 52 is a novo lac soiu" ion, 4 0.5 % by weigh- in Dcwanol PM, corrjTiercially available from CLARIAKT.
:3)TKCA is 3,4,5-trimethoxy cinnamic acid,
(4) 30094 IS an IR absorbing cyanine dye, comnierciaily available from FEW CHEKlCfiLS; the chemical structure of S00S4 is equal to IR-1
(5) See Table 1.
!£)Tegowet 265 is a copolymer of polysiloxane and poly(alkylene oxide'^, commercially available from TEGO CHEMIE SERVICE GmbH.
(7) See Table 1.
Imaging and processing of the printing plate precursor PPP-01 with DEV~Oi oo DEV-G3
The printing plate precursor PPP-01 was exposed with a Creo Trendsetter 3244 (plate-setter, trademark from Creo, Burnaby, Canada), operating at 150 rpm» and varying energy densities up to 200
mJ/cm^.
INGREDIENTS
After exposure the plate was processed with the developing solutions DEV-01 to DEV-C3 as defined in Table 4.
Table 4: Composition of the developing solutions DEV-01 to DEV-C3
INGREDIENTS DEV-01
I
(g) DEV-02
(g) DEV-0 3
sg)
1 Na-mf^-tas i li cate (1) 66 88 S8
Icrafol AP2 61 (2) 8 .83 8 . 83 8 .83
'r,ynpercnic 7304 (3) 4 . 4
( 1 4 . 4 4 . 4
El oo>:-01 0 > 17 5
1 SiQCf:-03 0.31
V.;ater until IGOO 1000 1000
I'ja-m.e-Lasi 1 icate is sodium mstasilicate pentahyd rare , :omrrierci al 1V available from SILMACO NV

■ 2 ! Crsiol AF2 61 iS al kylether sociiurt-. salt, commercially available from COGNIS
; Synperoni c T304 is a block-cc-polyiner of polyethylene oxide
5 no polypropylene oxide 1 =PPO) attached ro ethyl en edi amine i-ECAi in a ratio EDA/PEO/PPC of 1/15/14 and having a rr.ean TT.D J 6 c u 1 £ r weight of 1500, cornirie r c i a 11 y available r r om. UN IQEMA.
ID these experiments the precursor was exposed at the Right Exposure, hereinafter also referred to as RE. The RE is defined as the exposure energy at which a dot coverage on the plate for a 1x1 checkerboard and for a 8x8 checkerboard matches 50%. The dot coverage vjas measured with a GretagMacbeth D19C densitometer, commercially available from Gretag-Macbeth AG, with the uncoated support as reference.
The development latitude was determined by developing a 1x1 cneckerbcard at different developing times. The Right Developing Titds, hereinafter also referred ro as RDT, is defined whereby the optical density, hereinafter also referred to as OD, on the plate match a SO ?. dot coverage, measured with a densitometer as described above. (A 5C dot coverage corresponds with an OD of approximately 0.3; the experimentally measured values are indicated in Table 5). The development latitude was measured by the difference between the optical density of a 1x1 checkerboard, developed at a shorter {e.g. ~3 seconds) or longer (e.g. -^2, +5 or +10 seconds) developing time, and the optical density of a 1x1 checkerboard, developed at the RDT. The lower the absolute value of this difference in OD, the more efficient of the additive is working as a blocking agent to reduce the dissolution kinetic of this coating and the more the development latitude is improved.
The results are summiarized in Table 5.
Table 5: Results of developing latitude
1 Compara¬ Inven¬ Inven¬
tive tion tion
i Example 1 Exa.^ple 1 Ei^arrjple 2
'Precursor 1 PPP-01
1 PPP-01
1 PPP-01
'DeveJ oping solution ^ 1 DEV-01
1 DEV-02 1
1 1 DEV-0 3
1

Right developdnc time for 1x1 screen pattern (RDT) ( seconds; 1 ^ T 1
1 s 22 s 27 s !
D:: ... - RLT 0 . 30 0 . 32 0 . 29
' , PDTt-2s) - RDT'] ' -0.11
j ~0. 05
i , at RDT+5s] - (ODrixl.at RDT) j -0.14
1 ~C . 06 -0.07
[ ':0D ,;■:>;',: at RDT + lOs) - (OD(ixl)at RDT)] -0.24 -0 . IC -C . 13
[{OD.:v:;at RDT-3S)--(OD;ivi )at RDT)] + 0.09
1 + 0.03 + 0.08
i

The resu^Lts Table 5 demonstrate that the improved deveioprDent latitude for the Invention Examples 1 and 2 comprising a blocking agent £c-::ording to the present invention in the developing solution in comparisoPi with the Comparative Example 1.
Imaging and processing of the printing plate precursor PPP-01 with DEV-04 to DEV-07
Tne printing plate precursor PPP-01 was exposed with a Creo Trendsetter 3244 (plate-setter, trademark from Creo, Burnaby, Canada), operating at 150 rpm and an energy density of 100, 110 and
12G mJ/cm"^.
After exposure the plate was processed with the developing solutions at a temperature of 25°C during 15 seconds for DEV-04 and during 16 seconds for DEV-05 to DSV-07. The composition of the developing solutions are defined in Table 6.
Table 6; Coreposition of the developing solutions DEV-04 to DEV-0'
1 INGREDIENTS DSV-04
(g) DEV-05
(g) DEV-0 6
(g) DEV-07
(g)
K3-metasilioate (1) 177 r 177 177 17?
Crafol AF2 61 ;2) 22 . 3 22. 3
1 22. 3 22 . 3
1 Tc-.T^pound-Oi ! 1 D.89
I blccf^-Cl j 0-356
Block-OS 0.85
! iyatsr 1780 , 1780
i 1780 1730
)1; and ;2; sse Table 4.

The dot coverages of a 8xS checkerbaord, exposed at these three expoi^cre energies, were measured wizh a GrezagMacbeth Di9C ■:ier.5; roiT:er.er v.'izh the unccatsd support as reference, as -described i'bcve.
The exposure latitude is aetermined by the differenc- between the DD 01 the 3x6 checkerboard at each exposure energy. The lo>jer this difference tn OD, the mors efficient of the additive is working as a blocking agent to reduce the dissolution kinetic of this coating and the more the exposure latitude is irriproved. The results are summarized in Table
Table 7: Results of exposure latitude
Precursor Developing Exposure Developing 0D{ 8x8}
solution Energy time
(mJ/cm^ ] (seconds)
j Comparative PPP-01
j DSV-04 100 15 s 0. 180
1 Example 2 110 15 s 0- 137
120 15 s 0. 095
1 Comparative, PPF-01 DEV-05 , i 100 16 s 0. 2G4
Example 3
1 1 110 16 s 0. 089
120 16 s 0. 012
Invention Example 3 PPP-01 DEV-06 100 16 s 0. 300
110 16 s 0. 301
120 TeT^ 0. 253
Invention PPP-01 DEV-07 100 16 s 0 . 340
j Example 4 1 110 16 s 'J . 330
i 120
1 16 s 0 . 313

The results in Table 7 demonstrate that the improved exposure ]atitude for the Invention Examples 3 and 4 comprising a blocking agent according to the present invention in the developing solution L) E V - f; 6 and DE',^ - 0 " .
Ttse developing solutions DEV-04 and DEV-05 in rhe Comparative Exam.plss 2 and 3 comprise no blocking agent and a blocking agent of the prior art respectively, whereby these developing solutions behave a to srrong developing property resulting in an OD
ieveioping solutions is very poor in comparison with the developin' solutions of the present invention whereby the change in OD at itifersnt exposure energies is very small, resulting in a high exposvire laojrude.
Pieodration of the prinoing plate precursor PPP-Oi
j-iererenc^
Therefore, the
expos ea
irsor PPP-C2 was proce?5sed,
withouT_ previously been exposed to IR-laser or heat, in the develooing solutions as mentioned in Table 9 and 10 with a dwell time of 20 seconds at a temperature of 25°C. DEV-Reference is a developing solution without addition of a blocking agent or an other
The PFP-02 was produced by applying a coating layer defined in Table 5 onto the above described lithographic support, The solvent used to apply the coating is a mixture of 17% by volume of Dowanol PM and 5 3 -r by volume of tetrahydrofuran. The coating was applied at a wet co'ating thickness of 20 and then dried at 135°C.
Table 8: Composition of the coating layer
INGREDIENTS Amount of product (g /m' )
Uinder~01 (25 % by weight) (1] 1. 00
Crystal Vjol^t 'U by weight^ (2) "O7OT9~ ' "
Tegoglide 410 {1 % by weight) (3) 0.0025
Total dry coating weight (g/m ) 1.02
1) to (3) see previous tables.

Processing of the printing plate precursor FPP-02 in DEV-
^no BEV-08 to DEV-22
The printing plate precursor PPP-02 comprises the coating layer as defined in Table 8 and this layer has an analogue composition as the first coating layer of PPP-01. This layer is soluble in an alkaline solution and is used as a model for testing the efficiency of the blocking agents to reduce the dissolution kinetic of non-
coir.pcund; DEV--08 i:o DEV-18 are developing solutions comprising a DlDCking agent of the present invention; and DEV~19 to DEV-22 are ■developing solutions comprising another additive compound as defined in Taole 9 and IC.
Table 9: Ccrripcsition of the aeveloping solutions DEV-Reference and DEV-08 to OEV-22
INGREDIENTS : DEV-Reference
(g) DEV-08 to DEV-l"^
(g) DEV-18 to DEV-22
(g)
1Na-glucoheptonate (1) 5
Na-rnetas ill care (2) 102 102 102
Na-silicate solution (3) 10 10 10
jVariquat cc 9NS (4) 0.044 0 . 044 0 . 044
Triton H-66 ;5) 5.8 6.8 5.8
Synperonic T304 (6) 0.141 0.141 0.141
ja blocking agent added as defined in Table 10 0. 01 mol
a compound added as defined I in Table 10 f 1 i 0.01 mol
Water until 1000 1000 1000

f1) Na-glucoheptonate is glucoheptonate sodium salt (2) See previous tables
liiVariquat cc 9N3 is a cationic surfactant, commsrcially available from GCLTjSCHMIDT
'•^t Triton is an anionic surfactant, commercially available from
SEPULCHRE '5)See previous tables.
.tfter processing the OD is measured with a GretagMacbeth D19C densitometer with the uncoated support as reference, as described above. The difference between ohe OD of the plate PPP-02, developed with each o: the developing solutions DEV-08 to DEV-22, and the OD of the plate FPP-02, developed with DEV-Reference, were calculated. The h;igher the value of this difference in OD, the more efficient the additive is working as a blocking agent to reduce the di3solution kinetic of this coating.
The blocking efficiency of nhe differenr compounds was rated by t;-j-5 difference in OD:
difference in OD D.15 and Code 2: difference in OD ^ 0.5C and Code 3: difference in OD > 1.00, means a high blocking effect. The results are summarized in Table 10.
Table 10: Results of blocking efficiency
Precursor Developing solution Additive in developing solution Code for blocking efficiency
Invention Example 5 PPP-02 DEV-08 Block-01 2
Invention Zxa;T.pls 6 PPP-02 DEV-09 Block-02 2
Invsrtion Example 7 PPP-02 DEV-10 Elock-03 3
Invention Example 8 PPP-02 DEV-11 Block-04 3
Invention Exarr.ple 9 PPP-02 DEV-12 Block-05 2
Invention Example 10 PFP-02
1 DEV-13 Block-06 I
1
Invention ExaiTiple 11 PPP-C2 DEV-14 1 Block-07 1
Invention
1
Example 12 PPP-02 DSV-15 Block-08 3
Invention Example 13 PPP-02 DEV-16 Block-09 3
i Invention Example 14
( PPP-02 DEV-17 Eiock-10
1 Comparative ; PPP-02 Example 5
1 DEV-IB Compound-02
i 0
: Comparative ' PFF-02 i DEV-19 i Compound-0'J 0

E.xample 5
Comparative PPP-02
! DEV-2a
1 ' CDmpound-04 0
Coriipa rati ve PPP-02 DEV-il ■ Compound-05 1 0
Compa rj! 12 ve Example 9 ; PPP-02 DZV-22 1 Compound-06

The results in Table 10 de.-nonsfcrate that, in the Invention Examples 5 to 14, the developsrs DEV-08 to DEV-17 comprising a c'lociiing agent of the present invermion exhibit an improved ef flcLency In reducing the dissolution kinetic of this coating. In the Comparative Examples 5 to 9, the developers DEV-18 to DEV-22, comprising a compound of the prior art, exhibit a poor blocking effect.
Preparation of the printing plate precursors PPP-
Tne ??F-C7 were prod'^ted by first applying a fi rst coating
2ayer defined in Table 11 onto the above described lithographic support. The coating was applied at a wet coating thickness of 20 ijm and Chen dried at 135°C. The dry coating weight amounts to 1.02
g /m ~.
03 to PPP-07
Ta'Dle 11: Composition of the solution of the first coating layer
INGREDIENTS Amount of product
for PPP-03 ?jnount of product
for PPP-04 Amount of product
for PPP-05 Amount of product
for PPP-06 Amount of 1 product
for PPP-07
(g) (g) (g) (g)
1
Eiowanol (1) 160.74 160.45 160.45 160.4 5 160.45
i 1
iTHF '2i 1 535.04 5 3 5.96 ' 1 535.96 53 5.96 535.96
3inder-01 ;25 wt.^) (3) 211.37 211.62 211.62 211. 62 211.62
Bloc>:-04 i 1.35

INGREDIENTS Amount or product
for PPF-C3 !g) Amount of product
for PPP-C4 Amount of product for
j PPP-05 (g) Amounr of product for
PPP-0 6 ; g ' Amount of
product -
for
, FPP-07 1 :■
O ± 0 C - J. -L 1. 35
Block-03 1. 35
Block-G1 1 .35
Crystal Violet 11 wt.V! i 81.05 81.14
i 81.14 81.14 81.14
;Tego?liae i1 wt.%) (5 ) 10 . 81 10.32 1 10 . 82 10.82 10.02
;1; zo (5) see previous tables.

Or. zhe f:i.rst coated layer, a second layer as defined in T3.ble 12 was coated at a wet coating thickness of 25 pm and dried at 135°C.
2
The dry coating weight amounts to 0,8 0 g/m ,
5ble 12: Composition of the solution of the second coating layer
INGREDIENTS
1 Amount of product for PPP-03 to PPP-07
(g)
Dowanol PM '1)
1 2 3 5.0
AInovci SPN-^52 (40 % by weight) (2) 117.11
TMCA no ? by weight) {3)
1 60. 34
|S0094 (4) 2 .41
Crystal Violet (1% by weight'; (5) 70 . 99
! Teqowe i. 2 65 i' 1 % by weight) ; 6) 9. 94
Tegoglide 410 (1 1 by weight) (7) 32.65
Butanone 471.55
see previous tables

^ I u- I .
ipTiasing and processing of the printing plate precursor PFP-03 to
p p p _ n 7
Tne printing plate precursors PPP-C3 to PPP-O" were, in a first gxperir::er.t, exposed with a Creo Trendsetter 3244 (plate-setter, ■..radeiv^srk from Creo, Burnaby, Canada^, operating at 15C rpm at the Pight Exposure (RE) as defined above and developed with DEV-01 as defined above- in Table 4.
In a second experiment, the printing plate precursors PPP-03 to PPP-07 were exposed by a 1x1 checkerboard at an exposure energy which is 20 « lower than the RE value as determined above and, also, at an exposure energy which is 20 % higher than the RE value. After developing, the dot coverage for the under-exposure by 20 % and for the over-exposure by 20 % was measured by the OD as defined above. The exposure latitude was determined by difference between the dot coverage by the 20 % under-exposure and the dot coverage by the 20 I over-exposure. The lower the absolute value of this difference, the more efficiently the dissolution kinetic of the coating is reduced and rhe more the exposure latitude is improved. The results are surmarized in Table 13,
"able 13: Results of exposure latitude
EXAMPLES PPP-type RE-valus (mJ/cm") [Dot coverage RE-20t-,]- [Dot coverage at
Comparative .; Example 10 PPP-03 35 15
Invention Example 15 PPP-04 124 13
Invention Example 16 PPP-05 132 12
Invention Example PPP-06 110 8
! Invention
1 Examp-Le — ti 1 PPP-07 121 15
i

The results in Table 13 demonstrate an improved exposure latitude for the Invention Examples 15 to 18, comprising a blocking agent
ding to rhe present invention, whereby the difference between
c;. j_ ,
t.'e dot coverage by -he 20 % under-exposure and the dot coverage by the 2C % over-exposure is lower "han in the Comparative Eixample 10.

WE CLAIM
1. A rrsthod for making a li-hographic printing plate comprising tne sreps of:
(1; providing a heat-sensitive lithographic printing plate precursor comprisxng on a support having a hydrophiiic surface or whicn is provided with a hydrophiiic layer, a heat- sensitive coating,
(iO image-wise exposing said precursor with IR-radiation or heat, and
(3) developing said image-wise exposed precursor with an alkaline developing solution comprising a compound having at least two oni-am groups,
whereby said compound having at least two onium groups has a structure according to formula I, II or III:
Q is a divalent group when e and f are 0, a trivalent group when the surr, of e and f is 1, or a tetravalent grouD when e and f are both 1,
2" ""-c Z' independently are oniurr. groups,
L and L" to L*^ independently are linkrng groups, and
represents a repeating unit wherein Z"'" and L' represenr respectively an onium group and a linking group for each x-value,
a, b, c, d, e and f independently are 0 or 1, and X is an integer ranging between 1 and 10.
A method according to any of the preceding claims, wherein said linking group is selected from the group consisting of a linear, branched or cyclic alkylene group, an arylene group, an arylene-alkylene group, an oxy-alkylene group, an oxy- arylsne group, an oxy-heteroarylene group, or a combination of t'wo or more of these groups.
A method according to any of the preceding claims, wherein said onium group is selected from the group consisting of primary amine salts, secorLdary amine salts, tertiary amine sal's, quaternary ammoni'um salts, phosphonium salts or sulphoniurn salts.
1. A method according to any of the preceding claims, wherein the precursor comprises a compound having a structure according to formula I, II or III and wherein, during said developing step, at least part of said compound is removed from said precursor.
A i-isthod according to any of the preceding claims, wherein during or after said developing step, a replenishing solution comprising a compound having a structure according to fC'riuula I, or III is added to said developing solution.
t. A T-ethod according to any of the preceding claims, wherein s.Tiid slKsline developing solution comprising said compound having a structure according uo formula I, II or III further comprises a silicate or metasilicate.
7. An aqueous alkaline developing solution or replenishing
solution comprising an alkaline agent and a compound having a structure according to formula I, II or III,
3. A heat-sensitive lithographic printing plate precursor
com,prising on a support having a hydrophiiic surface or which is provided with a hydrophiiic layer, a heat-sensitive coating comprising a compound having a structure according to formula I, Ii or III.

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Patent Number

269728

Indian Patent Application Number

4930/CHENP/2008

PG Journal Number

45/2015

Publication Date

06-Nov-2015

Grant Date

03-Nov-2015

Date of Filing

16-Sep-2008

Name of Patentee

AGFA GRAPHICS NV

Applicant Address

SEPTESTRAAT 27, B-2640 MORTSEL, BELGIUM;

Inventors:

#	Inventor's Name	Inventor's Address
1	LINGIER, STEFAAN,	AGFA GRAPHICS NV, IP DEPARTMENT 3622, SEPTESTRAAT 27, B-2640 MORTSEL,
2	VAN DAMME, MARC,	AGFA GRAPHICS NV, IP DEPARTMENT 3622, SEPTESTRAAT 27, B-2640 MORTSEL,
3	LOCCUFIER, JOHAN,	AGFA GRAPHICS NV, IP DEPARTMENT 3622, SEPTESTRAAT 27, B-2640 MORTSEL,

PCT International Classification Number

B41N 3/08

PCT International Application Number

PCT/EP07/52443

PCT International Filing date

2007-03-15

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	60/784,414	2006-03-21	EUROPEAN UNION
2	06111310.6	2006-03-17	EUROPEAN UNION