Indian Patents. 218474:POLYAMIDE WITH LOW VISCOSITY DECOMPOSITION

Title of Invention	POLYAMIDE WITH LOW VISCOSITY DECOMPOSITION
Abstract	The invention relates to a polyamide with low viscosity degradation after remelting which can be produced by anionic polymerization of lactam in the presence of alkaline catalysts and if necessary activators and the method for production of the polyamide. The invention relates furthermore to a method for reprocessing anionically produced polyamide.

Full Text	FORM 2 THE PATENTS ACT, 1970 [39 OF 1970] COMPLETE SPECIFICATION [See Section 10] "POLYAMIDE WITH LOW VISCOSITY. DECOMPOSITION" EMS-CHEMIE AG, a Swiss company of Reichenauerstrasse, CH-7013 Domat/EMS, Switzerland, The following specification particularly describes the nature of the invention and the manner in which it is to be performed:- The invention relates to a polyamide which is degradation-stable on remelting and produced by the anionic polymerisa¬tion of lactam. Furthermore, the invention relates to the production of the polyamide using an anionic catalyst sy¬stem, preferably in a continuous process. The procedure thereby is such that the polymerisation proceeds in a de¬fined processing zone until the conversion of lactam into polylactam has just been effected, after that the activity of the catalyst is neutralized by homogeneous mixing-in of protic compounds, after which further process steps can fol¬low. As a result, a polyamide moulding compound is success¬fully produced which is stable on reprocessing. The invention relates furthermore to a method for reproces¬sing anionically produced polyamide, in which polyamide is crushed and then mixed with the deactivator, melted and ex¬truded. Anionic lactam polymerisation is comprehensively described in Elastic Material Handbook 3/4, Polyamides", Carl Hanser 2 Press/ Munich 1998, In practical application/ in particular activated anionic lactam polymerisation has thereby been successful and is used preferably for producing tough, volu¬minous cast parts {cast polyamide). The activator group, which has acylated the first lactam mo¬lecule, thereby forms the one chain end, after which lacta-mate effects actual chain growth, with ring-opening and re¬formation of lactamate. A multiplicity of patents for activated anionic lactam poly¬merisation relates to the activators. A special system has become known from DE 197 15 679 Al. Accordingly, species are contained in a solvation medium which, upon addition to the lactam melt, embrace the activa¬tor and the catalyst function, so that only one more compo¬nent must be added to the lactam melt, which component di¬rectly initiates then the accelerated lactam polymerisation. In S. K. Ha, J. L. White: Continuous Polymerisation and Co-polymerisation of Lauryl Lactam in a Modular Corotating Twin Screw Extruder, Intern. Polymer Processing XIII (1998) 2, p. 136 - 141, tests are described where, with separate addition of catalyst (Na-caprolactamate dissolved in lactam-6) and also activator, the lactam polymerisation is implemented continuously in a twin screw extruder. In particular, me¬thod parameters are thereby described and optimised. Expe¬riments for further conversion of the granulates and experi¬ments on the behaviour of parts made of anionic polymerised lactam are not described. A method is known furthermore from DE-OS 22 41 133 for pro¬ducing polyamides with a high molecular weight. This method also concerns an anionic polymerisation of lactams in anhy¬drous medium in the presence of alkaline catalysts. It is proposed therein that one or more compounds are added to the obtained polymer which, in the given method conditions, are 3 more strongly acidic than the amide function of the polymers and the lactams and lead only to a limited acidolysis of the polymer chains or to acidolysis equal to 0, For this purpo¬se, sulphonic acid or sulphonic acid esters are proposed as compounds. As was shown by means of laboratory tests, this freshly po¬lymerised melt could however only be stabilised inadequate¬ly. If in fact the acidic supplements mentioned there, especially in the described molar excess, are used in a com¬monly used extrusion process, then massive corrosion of the machine parts occurs. Furthermore, it has emerged that when a corresponding extrusion strand is drawn as normal through a water bath for cooling and subsequent granulation, H3O+ ions are formed which effect a chain split during remelting for the thermoplastic shaping. Correspondingly acidically set polyamide moulding bodies thereby proved also to be un¬suitable for practical usage because they are susceptible to degradation by the effects of hydrolysis, heat and radiati¬on, which leads in particular to a strong viscosity degrada¬tion during remelting. Further methods for neutralizing the catalyst are disclosed in DE-OS 22 41 132 and also in DE-OS 22 41 131. In the first mentioned publication, open to public inspection, tertiary alcohols are mixed in, in particular t-butyl alco¬hol and in the last mentioned malonic acid esters. During examination of the last mentioned methods, it emerged that the weak protic compounds added thereto only slow down the anionic lactam polymerisation but do not interrupt it entirely so that this is also displayed in a constantly slight reduction of the MVR (volume melt index), i.e. a ne¬vertheless slight increase in the molecular weight. It should however be mentioned specially that in particular conventionally anionically produced, non-neutralized polya¬mide suffers a massive chain length- or viscosity degradati- on on remelting. Reference is made to EP 0 905 166 Al in this respect. It can therefore be established in summary that no anioni-cally produced polyamide is known from the state of the art which displays only a slight viscosity change on rerne1ting. Proceeding herefrom, it is therefore the object of the pre¬sent invention to indicate a polyamide which has good physi¬cal properties/ in particular with respect to processing stability and which at the same time displays only a "slight" viscosity degradation on remelting. The invention is achieved with respect to the polyamide by the characterizing features of patent claim 1 and with re¬spect to the method for production, by the characterizing features of patent claim 16. The features of claim 28 rela¬te to the method for reprocessing polyamide which was produ¬ced via anionic polymerisation according to the conventional method without deactivation of the catalyst. The sub-claims show advantageous developments. The inventors were able to show that the disadvantages of the state of the art are eliminated if the lactam melt is polymerised just until the conversion of lactam into poly-lactam is effected to at least 90% by weight, preferably to 99% by weight up to approximately 99.9% by weight, then the catalyst (the lactamate) is destroyed rapidly and entirely by adding a lactamate-protonising compound (deactivator) in the form of a protic compound (after which further method steps can follow) and subsequently the corresponding poly-1actam melt is granulated for further use according to nor¬mal methods, or it is used directly for producing formed pieces. The thus obtained polyamide then still contains the deacti¬vator. The deactivator, i.e. the protic compound is thereby still partly in its protic form preferably in a residual 5 proportion of at least 1% of the starter value. The polya¬mide according to the invention has furthermore preferably a polydispersity D of % 5.0 and also a relative viscosity nrel of 1.55, measured according to EN ISO 307. The polydis¬persity of polymers and determination thereof is described for example in ROmpp Dictionary Chemistry, 10th Edition, page 2735. it is notable that the polyamides obtained according to the invention show in most cases a D value In the case of the polyamide according to the invention, its stability during remelting should be stressed in particular. The characterization of the stability is effected via the viscosity degradation nrel, which is equal to the difference between the relative viscosities of the polyamide before and after remelting. Since however the viscosity degradation is dependent upon the starter viscosity, i.e. the molecular weight, a correlation, which is determined empirically by the inventors for characterizing the viscosity degradation, is used, said correlation producing a virtually constant va¬lue independently of the starter viscosity for a specific number of molecular chain cleavages per unit of weight of polymer. The inventors were in fact able to show that the viscosity-corrected degradation is VKA = As the inventors could verify, the "sensitivity" of a speci¬fic polymer to a specific viscosity degradation (expressed as nrel) is hence in a ratio which is approximately quadra¬tic to the specific starter viscosity nsp1- This applies at least for the range examined here. With respect to the de¬finition of nrel and nsp reference is made to Rompp 10th Edi¬tion page 4870. The specific viscosity nsp is thereby the polymer-specific portion of the relative viscosity nrel, i.e. nrel = nrel -1, said polymer-specific portion exceeding the proportion of the pure solvent. According to the invention, the VKA. of the polyamide is s 0.13, preferably = 0.10 and particularly preferred £0.08. Anionically produced polyamides with these properties have to date not become known in the state of the art. Substances which destroy the catalyst rapidly and irreversi¬bly are suitable as deactivator in the sense of the present invention. Surprisingly, it has been shown that many classes of com¬pounds are able to do this. Of concern here are preferably protic compounds with an acidity constant pK which is less than approximately 14. Organic carboxylic acids in oligome-ric or low molecular form are used preferably; particularly preferred are also polymeric forms, whereby a stoichiometric 1 : 1 proportion of acidic functions to catalyst function is sufficient to destroy the catalyst entirely. In the case of organic carboxylic acids, those are particu¬larly preferred in which the carboxylic groups are sterical-ly hindered, i.e. restricted and/or screened in their mova-bility. Included herein are in particular compounds, i.e. deactivators in a polymer or oligomer form in which the COOH groups are bonded to the main chain. Examples are indicated in claims 7 and 8. Representatives from the group of carboxylic acids are: stearic acid, versatic acid or benzoic acid, and also polya-cids, such as for example dodecanedioic acid or also iso-and terephthalic acid and also oligomeric, wax-like pro¬ducts, such as for example oxidi2ed polyethylene waxes or else COOH group-containing polyamide oligomers which can be linear, branched or star-shaped with an average molecular weight of 500 - 10, 000 g/mol and also preferably also car- boxylic copolymers with a wide molecular weight spectrum. Examples are ethylene(meth)acrylic acid copolymers, whereby many further comonomers, such as long-chained or branched olefins, carboxylic acid esters, esterified alcohols etc. can be used as comonomers as well. Examples of such comono¬mers are butene, alkyl(meth)acrylate, vinyl alcohol and vinyl acetate and also styrene. It was shown unexpectedly that acidic polymers are also ex¬ceedingly suitable when their COOH groups are partly neutra¬lized with metal compounds and the counter-ions of the COOo groups are derived for example from Na, K, Ca, Zn, Li and Mg. Such polyolefin derivatives are described as ionomers (see Rdmpp) and in particular the so-called Zn ionomers are exceptionally compatible with polylactam, such as for examp¬le polylaurin lactam and hence also highly effective with respect to catalyst destruction. If they contain further comonomers in a proportion suitable for application, then they can in addition increase toughness and for example make the product flexible. The desired translucence of the po-lyamide is thereby often not lost or in fact is increased. In many cases, normal so-called EAA copolymers (ethylene acrylic acid copolymers), such as are produced for example by the firm DOW with a very varied acid proportion and MVR, are however suitable. The molar proportion of added COOH groups can constitute thereby a multiple of the basicity of the catalyst which is to be deactivated. The added EAA then operates preferably also as impact modifier. In summary, it can be established, that in the case of orga¬nic carboxylic acids in low molecular, but particularly in polymer form, those are particularly preferred, in which the carboxylic acid is directly incorporated in the polymer chain with steric hinderance, i.e. the carboxylic group is bonded directly to the main chain (backbone). In the case of mono- and dicarboxylic acids and also oxidized waxes, in which the carboxylic group is easily acccessible, or in the case of olefins with grafted-on maleic acid where the steric 8 hinderance respectively is missing, the excess requires however to be limited. The invention comprises furthermore, in the case of deacti¬vators, the acids of phosphorus and boron. Acids of phos¬phorus in a raonoraeric and oligomeric form which have acidic groups of different acidity are hereby preferred. For ex¬ample, H3P04 and the condensation products resulting there¬from are suitable. In the case of acids of phosphorrus, it is advantageous that these have a plurality of buffer areas, neutralization in the basic region often being suitable. In Fig. 7, buffer areas for a) phosphoric acid (H3PO4) and for b) the linear aliphatic Carboxylic acids are illustrated. The invention comprises all known lactams with respect to the starter component from a material point of view. Particularly the representatives with 5 - 12 C atoms, in particular however lactam-6 and lactam-12 and mixtures the¬reof, are suitable as lactams, lactam-12 being particularly preferred because, even at temperatures of approximately 200 - 320 oC, preferably 200 - 300 °C and particularly preferred 200 - 280 °C, it can be converted into polylactam to at least 99% by weight and the conversion runs extensively irreversi¬bly. Catalysts and catalyst systems which are described in the literature, in particular metal lactamates or lactamate-forming compounds are suitable as catalysts. Examples are sodium and magnesium lactamate and further ma¬gnesium compounds which are known from the literature. The mainly used catalyst is however commercially available sodi¬um caprolactamate dissolved in caprolactam. The activators used within the scope of the invention are known. 9 Activators operate as starters - initiators of the anionic lactam polymerisation, by activating the CONH bonds of the lactam and thus, upon admission of lactamate, initiating the starting reaction of the anionic polymerisation. Common commercially available activators are for example N-acylated lactams, such as for example N-acetylcaprolactam. Compounds also reacting directly with the lactam, such as isocyanates, which can also be capped according to the normal state of the art, and carbodiimides are often used which activate the CONH bond after acylation of the lactam. Examples of this are for example hexamethylehe diisocyanate or phenyl isocya-nate which can also occur trimerized in the isocyanurate form. If for example a diisocyanate is thereby used, then the polylactam chain grows after addition of the catalyst, or lactamate in two directions, if a monoisocyanate, such as for example phenyl isocyanate or also stearyl isocyanate, is used, the chain grows in one direction, these rules applying preferably as long as an excess of free lactam is present. A preferred class of substances for implementing the descri¬bed invention are catalyst-activator systems as are descri¬bed for example in DE 197 156 79. These are distinguished by the fact that only one formulati¬on which in addition occurs preferably as an easily dosable liquid must be added to the lactam, in particular to the lactam melt. According to patent claim 16, the invention relates further¬more to a method for producing polyamides as described abo¬ve. Anionically polymerized polylactam, in particular polycapro-lactam has been used to date almost exclusively in the mono¬mer casting process often for large volume parts, such as for example crane jibs because the procedure can start from a low viscose easily pourable melt. High fractive strength in particular is sought after and the molecular structure 10 has no special requirements to satisfy with respect to recy¬cling for example in thermoplastic shaping processes- Be¬cause of good processability in thermoplastic processes and thereby stability against degradation during remelting, to¬day hydrolytically produced polylactam is used almost exclu¬sively for the so-called thermoplastic shaping processes. Formulations and methods for simplified production of poly¬lactam which can then be further processed easily and wi¬thout degradation and leads to parts of good application properties, therefore represent a substantial technical pro¬gress, It has been shown astonishingly that the method according to the invention leads in particular to polyamide in granulate form, which can be shaped thermoplastically in an easy and stable manner into parts, such as for example pipes of a high application value. The new method in the preferred embodiment is distinguished in that a lactam melt is converted by means of a catalyst-activator system with suitable reaction control until a lac¬tam conversion of at least approximately 90% by weight, pre¬ferably 99% by weight of lactam-12, is effected, after which a deactivator is added which irreversibly destroys the cata¬lyst, if necessary further processing steps follow directly, then a part is directly formed or the melt is converted di¬rectly into granulate which then can be processed thermopla¬stically into objects of high application value according to common methods. The new process is suitable in particular for continuous me¬thods, for which twin screw extruders with co-rotating screws and with special processing elements are particularly suitable. However, the process can be conducted also in several steps by activating for example a lactam melt in a continuous process, for example by means of a dynamic (rotating) or al¬so static continuous mixer with the catalyst/activator and then by polymerizing under constant feeding, for example in a single screw or also a twin screw extruder with suitable choice of temperature and residence time until the lactam is just converted into polylactam and then by removing and gra¬nulating it. Subsequently, the deactivator is added as far as possible at the beginning of the remelting process in a second extrusion passage, for example in an extruder for compounding tasks, such as for example a twin screw extru¬der, and is intermixed into the melt, the incorporated of all further compounds and additives, which are required for a commercial product, being then able to follow. The method can also be implemented in varied ways, the main aim residing in attaining a polyamide which is stable during processing and which can be shaped without substantial de¬gradation via melt processing into parts of a high service value. At the beginning of implementation of the method it is of particular advantage that the catalyst/activator is distri¬buted rapidly and homogeneously in the lactam melt and that the chain growth proceeds as uniformly as possible and that, after completion of the lactam conversion, the catalyst is destroyed rapidly and in the entire now-viscose polylactam mass. This presents process-technological requirements which suggest implementing the whole method in a continuous¬ly mixing machine with the necessary supply and mixing ele¬ments. Twin screw extruders with co-rotating screws, such as for example the commercial machine ZSK-25 of the company Werner and Pfleiderer, Stuttgart which can be equipped in an extraordinarily variable manner, with respect to process lengths, dosing devices, mixing and barrier elements, is suitable for optimizing the formulations and method conditi¬ons adapted to the application. In the feed zone of the extruder, the lactam can thereby be melted or the extruder can be supplied with lactam melt also for example from a supply tank in a continuous manner. Now addition of the catalyst/activator into the lactam melt should be effected with rapid homogeneous mixing so that the polymerisation is started as simultaneously as possible in the entire polylactam melt. This step can be implemented according to many alternative methods by processing for ex¬ample according to the 2-pot principle which is well known in lactam polymerization or by adding solid catalyst as a solid material solution of sodium caprolactamate in capro-lactam to the lactam in a solid or already molten form and then adding the activator, such as for example a liquid isocyanate, which can also occur in a capped or cyclized form or also dissolved/ or of N-acylated lactam to the cata¬lyst-containing lactam melt. Systems, which directly initiate the polymerization and which hence contain simultaneously the function of catalyst and activator, are particularly suitable. Particularly pre¬ferred thereby are those systems which occur in a liquid form and which for example can be metered into the lactam melt directly by means of a liquid metering pump at a con¬stant volume proportion, or which can be added directly via a static mixer to the lactam melt. Systems of this type are described in DE 197 15 679 A1, After completion of the catalyst-activator addition and ho¬mogeneous mixing, the polymerisation process follows, pre¬ferably a plug flow is maintained so that all growing poly¬lactam chains have as far as possible identical growth con¬ditions which are defined in particular by the temperature in this zone and of course by the residence time. As soon as the aimed lactam conversion is achieved (lactam-6 approximately 90%, lactam-12 approximately 99 - 99.9%), the catalyst activity is stopped by rapid and homogeneous mi-xing-in of the deactivator, and thereby the catalyst is de- stroyed. On effecting the method continuously, the addition zone for the deactivator should be separated from the poly¬merization zone in such a manner that as far as possible no backflow of deactivator into the polymerization zone occurs. The deactivator which can be used as a single substance or also as a substance mixture is often able to perform supple¬mentary effects in the polylactam. Preferably, the deactivator is therefore used as a substance mixture. All compounds described in the case of the polya-mide are possible as deactivator. If the deactivator is a long-chain acidic alkene containing comonomers such as for example butene, hexene, octene etc. or alkyl esters, such as for example originating from buty-lacrylate, it can also have a flexibilizing effect and si¬gnificantly increase the toughness. If the deactivator is an ionomer, for example based on Zn or Na or an EAA-copolymer which during the deactivation reac¬tion also becomes an ionomer, and for example containing co-monomers, such as for example alkylacrylate, then for examp¬le translucence is achieved together with high toughness and high flexibility which represents an additional advantage for particular applications. Such deactivators can also contain a high excess of COOH groups which are directly in¬corporated in the chain as long as the deactivator fulfils its supplementary objectives, such as for example an impact strength increase. Different deactivators can of course be combined with each other according to the requirement of the final product. The deactivators can thereby be introduced in different ways, for example as a master batch in for example granulate form. Deactivators of a polymeric nature or also pulverulent types are introduced into the melt for example via metering belt 14 scales or a stuffing screw, of course the rules for metering and mixing, which are known from the state of the art, re¬quiring to be observed. Deactivators can of course be fed also in a molten form via a so-called side-feeder". Together with the various deactivators or also subsequently, further additives, such as minerals, glass fibres/ flame re-tardants, impact modifiers, colourants, stabilisers etc. and mixtures thereof can be added to the polylactam melt with the aim of providing a market product of good proeessabili-ty. After that, these additives are mixed-in homogeneously and the ready formulated polylactam melt is supplied under pres¬sure to the output nozzle of the extruder, and following normal technology, is converted into a granulate form or, in a suitable tool, for example a pipe head, is directly shaped for the application task, for example a covering or a coa¬ting, a pipe or a profile. It has been shown that the method according to the invention as described previously is implemented best at temperatures of 140 - 320 °C Preferably, temperatures of 140 - 300 °C, particularly preferred 140 - 280 c are however used hereby. The invention is now explained in more detail with reference to examples which represent only a selection of the various possibilities with respect to implementation and applicati¬on. It has been shown thereby that, within the scope of the in¬vention, various method variants can be applied in order to avoid chain length degradation of anionically polymerized polylactam during processing via the melt and in order to obtain polyamide of a stable restricted molecular weight. According to the patent claims 28 to 33, the invention rela¬tes furthermore to a method for reprocessing anionically produced polyamide. A particular application of the method according to the in¬vention, as explained above, is thereby of concern. It was presented already at the beginning that the method according to the invention, as characterized in patent claim 16, can also be implemented in two steps. Within the scope of the invention, it is therefore fundamentally not required that the steps a (polymerization) and b (deactivation) are imple¬mented in succession but instead that also a fairly large time span, for example several days or even months or even a first application or life cycle, for example as matrix in a composite material or as a cast part can lie between step a and b. This implies in other words that the method accor¬ding to the invention can also be implemented for polyamide which was already produced anionically a long time ago and that is treated with the deactivator as explained in patent claim 16. Hence the method according to the invention is suitable, as it is now characterized particularly by the pa¬tent claims 28 to 33, also for reprocessing of already pre¬sent anionically produced polyamide. According to the in¬vention, the deactivator is added thereto in such a quantity that at least the basicity still present from the catalyst system is neutralized. Then the mixture is melted and ex¬truded in a manner which is known per se, optionally by ad¬ding auxiliary agents such as further matrix material, car¬bon black or stabilizers. The reprocessing method according to the invention is parti¬cularly of advantage when the polyamide is present mixed with fibres. The method of the invention according to the patent claims 28 - 33 is preferably applied for filament structures, such as for example woven fabric, hosiery fabric, knitted fabric or plaited material, in a polyamide matrix in the form of a composite material. It is then provided according to the method that these com¬posite material parts are comminuted, followed by mixing with the deactivator according to the invention. This mix¬ture is then subjected preferably to a continuous melting process in a twin screw extruder, whereby the melt is homo¬genized. Preferably the melt is then withdrawn as a strand via an aqueous cooling bath and cut into granulate. In this way, a fibre-reinforced polylactam granulate of high service value is achieved which can be shaped by common thermoplastic processes, in particular by injection moulding into parts with new application pqssibilitiefs. Without the method according to the invention often no material recy¬cling was possible previously. The present invention relates to polyamide with low viscosity decomposition after re-melting, producible by anionic polymerisation of lactam in the presence of alkaline catalysts and, if appropriate, activators, characterized in that the polyamide contains a protic compound as deactivator, selected from organic carboxylic acids in oligomer or polymer form and/or acids of phosphorus and boron with the protic compound still present in its protic form at least in a residual proportion of 1% of the initial value, with a relative viscosity (nrel)of al.55 as measured on a 0.5 weight-% solution in m-cresol as claimed EN ISO 307 and during re-melting at 275°C and a water content of below 0.15 weight-% a viscosity corrected decomposition. VKA= Anrel of o.13 (nsp.12)2 In the following summary, the abbreviations used in the ex¬amples and comparative examples are explained. Compilation of the abbreviations of the Examples 1. Deactivators Designation Manufacturer Comments Surlyn 9320 & 9120 Du Font, Delaware, Ionomer, partially neutralized with zn Primacor 3340 Dow, Horgen, CH Ethylene acrylic acid copolymer; €.5% acrylic acid Lucalen 292a BASF, Ludwigshafen Copolyolefin with 4% acrylic acid Luvax EAS BASF, Ludwigshafen Polyethylene wax with 5.5% acrylic acid According to requirement/ additionally ethylene distearamide of trade name Acrawachs-C from Lonza (Basel, CH) was used as processing aid in the injection moulding process (for impro¬ved extruder feed), whereby Acrawachs-C has no deactivator function- 2. Analysis and test methods • nrel = relative viscosity, measured as a 0.5% by weight solution of polyamide in m-cresol accor¬ding to EN ISO 307. • MVR (previously also often described as MVI), the volume melt index in cm3 per 10 min. measured af¬ter a melting time of 4 min. at 275 oC and a load of 5 kg according to EN ISO 1133. Specific mel¬ting conditions are also established in this norm which are practical and which can be used for de¬termining the viscosity degradation nrel or of VKa by using a MVR apparatus . • MGV = molecular weight distribution. This was determined after derivatisation of the samples with trifluoroacetic acid anhydride in tetrahy-drofurane as solvent by means of GPC {Gel permea¬tion chromatography) . The polydispersi/ty D Ww/Mn was determined therefrom (cf. Rompp) . 3. Mechanical values • S2Z bars: Impact tensile bars, 1mm thick • SZZ: tensile impact strength, in kJ/mm2 • Heat storage: according to ICE 216 • weathering: according to ISO 4892-2 Tests 1-6 and comparative test. XI In order to perform the tests 1- 6, the process was imple¬mented in two steps so that initially anionically polymeri¬zed polyaraide-12 in granulate form was produced by the con- tinuous method and this was subsequently reprocessed into test pieces by injection moulding with the addition of sup¬plements destroying the catalyst activity (deactivators). In order to produce the granules, lactam-12 pills were pre-dried and then supplied continuously to a twin screw extru¬der, ZSK-25, of the firm Werner and Pfleiderer Stuttgart, using a common compounding screw and usual process conditi¬ons, namely 150 rotations per minute, a constant set tempe¬rature of all barrel sections of 270 oC, and a throughput of 10 kg/h. Directly after melting the pills, the liquid cata¬lyst, as described in DE 197 15 679, was injected in such a quantity that 1 equivalent (Val) of active liquid catalyst is present per 225 mol parts of lactam-12. The liquid cata¬lyst immediately initiates the polymerization so that a com¬pact polymer strand can be withdrawn at the nozzle, which strand is then cooled in a water bath, followed by granula¬tion and drying of the granulate ready for processing. In order to obtain a first overview of the effectiveness of the substances according to the invention which destroy the catalyst, the granulates were pre-mixed with the correspon¬ding additives and these mixtures were injection moulded on a commonly used injection moulding machine, type Arburg-Allrounder 320-210-750 Hydronica, into 4 mm thick ISO tensi¬on bars, normal injection moulding conditions being main¬tained corresponding to a melt temperature of 258 °C, a mould temperature of 40 °c and a cycle time of 50 seconds. The results are compiled in Fig. 1 {Table l), tests designa¬ted respectively with X being comparative tests. They show how, by using the deactivators according to the invention which are only applied onto the granulate before the injection moulding operation, the degradation on melting is very substantially reduced. In test XI, where pure, anionically polymerized granulate was injection moulded identically into test pieces/ a very much higher viscosity degradation occured. The measured vo¬lume melt index values also confirm the strong degradation during remelting of anionically polymerised PA12 granulate on the comparative test XI where no deactivator was added. At the same time the low MVR values of tests 1-6 verify that only a low degradation occurs during melting if deacti¬vators according to the invention are mixed into the melt during the injection moulding processing. The following tests describe the continuous production of anionically polymerized polyamide granulate according to the invention which is of high stability in the melt state with respect to viscosity degradation. This new polyamide granulate can be processed exceptionally well via the melt state by thermoplastic shaping processes such as injection moulding and extrusion into pipes/ films and coatings of high service value. The polyamide granulates produced according to the new processes have property combinations not known to date so that parts produced therefrom have in addition to good heat stability, very good weathering stability and an extraordi¬narily high hydrolysis stability in aqueous media. Pipes produced therefrom have for example a high degree of low temperature toughness not known to date and also high resi¬stance to internal pressure even at temperatures up to 130 °C. In order to produce the polyamides according to the inventi¬on in granulate form, the process can be implemented for ex¬ample in two stages by proceeding for example in a first ex¬trusion passage as in the case of test 1-6 and thereby converting laurin lactam into polylaurin lactam by means of a liquid catalyst according to D£ 197 15 €79. In a second extrusion passage, the components which destroy the catalyst and often at the same time are able to take up the required supplementary functions are added. The deactivator is thereby melted preferably under mild con¬ditions and with intensive mixing together with the polylac¬tam granulate produced in the first process step so that its effect is rapidly developed by neutralizing in particular the strong basicity of the melt. Further components of the formulation required for practical application, such as sta¬bilizers/ plasticizers, colourants, such as carbon black and further necessary additives, can be introduced for example directly into the melt also at a later stage of the extrusi¬on process or in the case of liquids, such as plasticizers, can be injected directly into the melt. Alternatively, the process can be implemented however also in a one stage method, the continuous conversion of the lac¬tam into polylactam being effected in a first process step, preferably by means of a liquid catalyst, and an appropriate design of the extruder, then the melt being stabilized against viscosity change by means of the deactivator which neutralizes the catalyst activity and simultaneously or sub¬sequently further components being added to the final formu¬lation and then being mixed-in, then the melt being dischar¬ged as a strand, being cooled and the solidified strand being granulated so that after drying a processing-ready granulate is present or the melt being supplied directly in¬to a tool for shaping. The one stage production process requires furthermore only an average residence time of approximately 2 minutes, the deactivation in the second extruder zone being included. The high economic efficiency is thereby demonstrated if one considers that several hours are required for the hydrolytic production of polylactam. The process conditions are in principle able to be varied within a wide range. Preferably however the procedure is implemented in such a way that the polymerisation time in the chosen set conditi¬ons of the extruder, such as tempering of the heat rones and screw speed, is just adequate to convert 99 - 99.8% by weight of the lactam-12 and after that the catalyst is de¬stroyed by addition of the deactivator. In the case of lac-tam-6/ polymerization takes place preferably in the known, temperature-dependent range of the monomer/polymer equili¬brium. If the two step process is thereby used, this can be achieved easily by appropriate setting of temperature con¬trol, throughput and screw speed. Comparative teste X3, X4, and X5 and examples 10 - IS By use of the twin screw extruder, ZSK-25, polyamide-12 gra¬nulates were again produced using the normal compounding screw and starting from laurin lactam and liquid catalyst. The test conditions and the test results of the comparative tests are compiled in Fig. 2 (Table 3). As the analysis results show, the melting with only one pas¬sage through the MVR appliance effects already a considerab¬le viscosity degradation. Tests 10 - 15 The PA-12 base granulates, produced in the comparative test X3 - X5 and still viscosity-unstable, were now pre-mixed with the deactivators according to Fig. 3 {Table 4} and the substance mixtures then were melted gently on a twin screw extruder ZSK-30, equipped with a compounding screw, so that the deactivators are able to exert their influence of cata¬lyst deactivation and modification of the melt, liquid addi¬tives/ in particular plasticizers, being injected into the melt directly in a later stage of the compounding. The melt which now contains the catalyst residues in deactivated form and also additives mixed-in homogeneously, is then introdu¬ced into an aqueous cooling bath via a nozzle, the solidi¬fied strand is granulated and the granulates are dried, af¬ter which a processing-ready, processing-stable granulate is present. This can be processed dependent upon the formula¬tion into plasticized PA-12 pipes, into injection moulded parts, into sheaths of cables, into foils and into coatings via thermoplastic processes without degradation occurring and into finished parts which have excellent properties. The formulations and properties of the PA-12 moulding com¬pounds according to the invention are compiled in Fig. 3. The measurement of the nrel values proves impressively that, both during MVR measurement and also during processing into pipes and cable sheaths, the new polyamides are viscosity-stable during rerne1ting. Test 16-19 During these tests, the following goals were striven for: 1. The polymerization and the compounding must be effected in one extrusion step. 2. During compounding, effective heat- and weathering sta¬bilizers should be incorporated into the melt. 3. The behaviour of test pieces made of polyamide moulding formulations according to the invention should be te¬sted in a comparative test under heat and light effect (weathering). For this purpose, the extruder, ZSK-25, which was used al¬ready in the previous polymerization tests was used, but the twin screws were modified such that the feed and the melting of the lactam-12 pills was effected approximately in the first third, then the already previously described liquid catalyst was metered continuously into the melt, so that the polymerization of the lactam proceeded in the second third of the extruder, the extruder shafts were subsequently fit¬ted with elements preventing backflow of viscous melt, sub¬sequently in the last third, the deactivator and the stabi¬lisers were metered into the melt via a so called "side-feeder" and then were mixed-in homogeneously, the melt was then withdrawn as a strand, this was granulated and the gra¬nulate was dried to a processing-suitable water content of lower than 0.15% by weight. The following conditions were maintained in the polymeriza¬tion zone: • 1 mol equivalent of liquid catalyst was added continuously per 200 parts of lactam-12 • the extruder housings after the injection point of the catalyst were set at 290 °c • the rotational speed was set at 200 rpm with a total mass throughput of 14 kg/h. Temperature increase to 290 °C was effected in order to ac¬celerate conversion because, during implementation of this test/ only 1/3 of the extruder length was available for the polymerisation. In order to increase the total quantity of additives metered into the melt via side-feeders to at least 5% by weight/ partly anionically polymerized PA12 granulate (PA12, A) from previous tests was metered into the melt together with the recipe components. The following combination of stabilizers was used for all tests (even X6): 0.3% by weight Irganox 245, 0.15% by weight Irganox P-EPQ (= stabilizers by Ciba, SC, Basel) and also 0.5% by weight Nylostab S-EED (= stabilizer by Clariant). The added deactivators are represented in Fig, 4 (Table 5a). Test X6 once again represents thereby a comparative test, in the production of which no deactivator was added in the nar-row sense. The relative viscosity nrel, the MVR and subsequently again nrel in the sample after MVR measurement were determined. The difference nrel of both relative viscosities corresponds to the degradation during melting which is however dependent upon the starter value The inventors have however found the surprisingly simple empirical formulation that the viscosity-corrected degradation, calculated according to the formula VKA=nrel (nap1)2, for a specific material composi¬tion remains, independently of the starter value of the re lative viscosity, virtually constant (nsp=1 being the speci¬fic viscosity before melting, with nep (nep=l) . Thanks to this knowledge, VKA is a characteristic dimension for eva¬luation of the degradation stability of the polyamide. Mo¬reover, the molecular weight distribution was measured. Furthermore DIN impact tensile bars were moulded from the granulates and these were subjected to a heat test at 150 °C. Likewise, a rapid weathering test was implemented in a Wether-0-meter appliance. The results of all these tests are contained in Fig. 5 (Ta¬ble 5b). It should be taken into account during evaluation of the tests in Table 5b that the stabilizers used in comparative test X6 already act upon the catalyst up to a certain degree in a deactivating manner so that the viscosity degradation in the MVR test is smaller than in corresponding measure¬ments on pure, anionically polymerised granulate. 5 The MGV measurements are interesting. It should be taken into account that the polymerization conditions on the ex¬truder were chosen such that polymerization is essentially finished after 2/3 extruder length. During test X6, where the catalyst activity is maintained at least in part, a broader MG distribution resulted and in particular many short-chain molecule fragments are produced. In the tests 16 - 19 on the other hand, the effectiveness of the catalyst is stopped entirely by the deactivator and the molecular weights remain high with a D-value close to 2, as is common also in hydrolytically produced polyamide. In the tests 16 - 19, the results are somewhat worse where the low-molecular compound Luvax EAS (EAS ethylene acrylic acid) was used. They are particularly good in tests 16, 18 and 19 where high-molecular acidic compounds are used as de¬activator. The effect of the higher molecular weight of these compounds is demonstrated also in the heat test at 150 °C where the variant X without deactivator fails already after 72 hours, followed by the variant Luvax EAS whilst then in the tests with high-molecular weight deactivator a substantial de¬crease in strength only occurs after 8 days. During rapid weathering in the Wether-0-meter, all variants display exceptionally good behaviour up to 2000 h. With respect to the level of the SZZ values, the following substantial correlation should be taken into account. The solvation agent contained in the liquid catalyst greatly affects the increase in toughness so that also finished parts based on lactam-12 polymerised with liquid catalyst have a high toughness and fracture strength. If such parts are now subjected to extreme heat effect, for example a heat 26 test at ISO °C then the solvation agent of the used liquid catalyst is initially evaporated and the tensile impact strength falls to the normal level of PA12, as it is known for hydrolytically produced PA12. This relevant plateau is then maintained until the effectiveness of the stabilizer combination recedes. The half-life rule which is hydrolyti¬cally common with PA12 must therefore not be applied for evaluation of the heat resistance but instead the achieved level of toughness after evaporation of the solvation agent must be selected for example after 48 h heat effect as the basis for the subsequent drop in strength. Tests 20 - 24 The tests 20 - 24 relate to further testing of deactivators of anionic catalysts for the polymerization of lactam. For this purpose, anionically polymerized PA12 granulate was produced without additives as a first stage under mild con¬ditions with a simple compounding screw on the ZSK-25 in one extrusion passage. Polymerization was thereby implemented at a temperature set¬ting of the housings of 260 oC respectively, a rotational speed of 150 rpm and with a throughput of 13 kg/h, and a ca¬talyst to LC-12 mol ratio of 1:125. As already described previously, this granulate was then re-extruded on a ZSK-30 with additives according to Fig. 6 (Ta¬ble 6). The deactivators and the base granulate were there¬by supplied together to the extruder and melted so that they were able from the start to exert their deactivating effect. The additives used and the effect of the deactivators which stabilises the viscosity of the melts, is illustrated by me¬ans of nrel and MVR measurements in Table 6. 27 As the measured, mechanical values on test pieces produced by the injection moulding method prove conclusively, test pieces with excellent mechanical properties based on the PA12 granulates according to the invention result despite the relatively low molecular weight. 28

Full Text

FORM 2
THE PATENTS ACT, 1970
[39 OF 1970]
COMPLETE SPECIFICATION [See Section 10]
"POLYAMIDE WITH LOW VISCOSITY. DECOMPOSITION"
EMS-CHEMIE AG, a Swiss company of Reichenauerstrasse, CH-7013 Domat/EMS, Switzerland,

The following specification particularly describes the nature of the invention and the manner in which it is to be performed:-

The invention relates to a polyamide which is degradation-stable on remelting and produced by the anionic polymerisa¬tion of lactam. Furthermore, the invention relates to the production of the polyamide using an anionic catalyst sy¬stem, preferably in a continuous process. The procedure thereby is such that the polymerisation proceeds in a de¬fined processing zone until the conversion of lactam into polylactam has just been effected, after that the activity of the catalyst is neutralized by homogeneous mixing-in of protic compounds, after which further process steps can fol¬low. As a result, a polyamide moulding compound is success¬fully produced which is stable on reprocessing.
The invention relates furthermore to a method for reproces¬sing anionically produced polyamide, in which polyamide is crushed and then mixed with the deactivator, melted and ex¬truded.
Anionic lactam polymerisation is comprehensively described in Elastic Material Handbook 3/4, *Polyamides", Carl Hanser
2

Press/ Munich 1998, In practical application/ in particular activated anionic lactam polymerisation has thereby been successful and is used preferably for producing tough, volu¬minous cast parts {cast polyamide).
The activator group, which has acylated the first lactam mo¬lecule, thereby forms the one chain end, after which lacta-mate effects actual chain growth, with ring-opening and re¬formation of lactamate.
A multiplicity of patents for activated anionic lactam poly¬merisation relates to the activators.
A special system has become known from DE 197 15 679 Al. Accordingly, species are contained in a solvation medium which, upon addition to the lactam melt, embrace the activa¬tor and the catalyst function, so that only one more compo¬nent must be added to the lactam melt, which component di¬rectly initiates then the accelerated lactam polymerisation.
In S. K. Ha, J. L. White: Continuous Polymerisation and Co-polymerisation of Lauryl Lactam in a Modular Corotating Twin Screw Extruder, Intern. Polymer Processing XIII (1998) 2, p. 136 - 141, tests are described where, with separate addition of catalyst (Na-caprolactamate dissolved in lactam-6) and also activator, the lactam polymerisation is implemented continuously in a twin screw extruder. In particular, me¬thod parameters are thereby described and optimised. Expe¬riments for further conversion of the granulates and experi¬ments on the behaviour of parts made of anionic polymerised lactam are not described.
A method is known furthermore from DE-OS 22 41 133 for pro¬ducing polyamides with a high molecular weight. This method also concerns an anionic polymerisation of lactams in anhy¬drous medium in the presence of alkaline catalysts. It is proposed therein that one or more compounds are added to the obtained polymer which, in the given method conditions, are
3

more strongly acidic than the amide function of the polymers and the lactams and lead only to a limited acidolysis of the polymer chains or to acidolysis equal to 0, For this purpo¬se, sulphonic acid or sulphonic acid esters are proposed as compounds.
As was shown by means of laboratory tests, this freshly po¬lymerised melt could however only be stabilised inadequate¬ly. If in fact the acidic supplements mentioned there, especially in the described molar excess, are used in a com¬monly used extrusion process, then massive corrosion of the machine parts occurs. Furthermore, it has emerged that when a corresponding extrusion strand is drawn as normal through a water bath for cooling and subsequent granulation, H3O+ ions are formed which effect a chain split during remelting for the thermoplastic shaping. Correspondingly acidically set polyamide moulding bodies thereby proved also to be un¬suitable for practical usage because they are susceptible to degradation by the effects of hydrolysis, heat and radiati¬on, which leads in particular to a strong viscosity degrada¬tion during remelting.
Further methods for neutralizing the catalyst are disclosed in DE-OS 22 41 132 and also in DE-OS 22 41 131. In the first mentioned publication, open to public inspection, tertiary alcohols are mixed in, in particular t-butyl alco¬hol and in the last mentioned malonic acid esters.
During examination of the last mentioned methods, it emerged that the weak protic compounds added thereto only slow down the anionic lactam polymerisation but do not interrupt it entirely so that this is also displayed in a constantly slight reduction of the MVR (volume melt index), i.e. a ne¬vertheless slight increase in the molecular weight.
It should however be mentioned specially that in particular conventionally anionically produced, non-neutralized polya¬mide suffers a massive chain length- or viscosity degradati-

on on remelting. Reference is made to EP 0 905 166 Al in this respect.
It can therefore be established in summary that no anioni-cally produced polyamide is known from the state of the art which displays only a slight viscosity change on rerne1ting.
Proceeding herefrom, it is therefore the object of the pre¬sent invention to indicate a polyamide which has good physi¬cal properties/ in particular with respect to processing stability and which at the same time displays only a "slight" viscosity degradation on remelting.
The invention is achieved with respect to the polyamide by the characterizing features of patent claim 1 and with re¬spect to the method for production, by the characterizing features of patent claim 16. The features of claim 28 rela¬te to the method for reprocessing polyamide which was produ¬ced via anionic polymerisation according to the conventional method without deactivation of the catalyst. The sub-claims show advantageous developments.
The inventors were able to show that the disadvantages of the state of the art are eliminated if the lactam melt is polymerised just until the conversion of lactam into poly-lactam is effected to at least 90% by weight, preferably to 99% by weight up to approximately 99.9% by weight, then the catalyst (the lactamate) is destroyed rapidly and entirely by adding a lactamate-protonising compound (deactivator) in the form of a protic compound (after which further method steps can follow) and subsequently the corresponding poly-1actam melt is granulated for further use according to nor¬mal methods, or it is used directly for producing formed pieces.
The thus obtained polyamide then still contains the deacti¬vator. The deactivator, i.e. the protic compound is thereby still partly in its protic form preferably in a residual
5

proportion of at least 1% of the starter value. The polya¬mide according to the invention has furthermore preferably a polydispersity D of % 5.0 and also a relative viscosity nrel of 1.55, measured according to EN ISO 307. The polydis¬persity of polymers and determination thereof is described for example in ROmpp Dictionary Chemistry, 10th Edition, page 2735. it is notable that the polyamides obtained according to the invention show in most cases a D value In the case of the polyamide according to the invention, its stability during remelting should be stressed in particular.
The characterization of the stability is effected via the viscosity degradation nrel, which is equal to the difference between the relative viscosities of the polyamide before and after remelting. Since however the viscosity degradation is dependent upon the starter viscosity, i.e. the molecular weight, a correlation, which is determined empirically by the inventors for characterizing the viscosity degradation, is used, said correlation producing a virtually constant va¬lue independently of the starter viscosity for a specific number of molecular chain cleavages per unit of weight of polymer.
The inventors were in fact able to show that the viscosity-corrected degradation is

VKA =
As the inventors could verify, the "sensitivity" of a speci¬fic polymer to a specific viscosity degradation (expressed as nrel) is hence in a ratio which is approximately quadra¬tic to the specific starter viscosity nsp1- This applies at least for the range examined here. With respect to the de¬finition of nrel and nsp reference is made to Rompp 10th Edi¬tion page 4870. The specific viscosity nsp is thereby the

polymer-specific portion of the relative viscosity nrel, i.e. nrel = nrel -1, said polymer-specific portion exceeding the proportion of the pure solvent. According to the invention, the VKA. of the polyamide is s 0.13, preferably = 0.10 and particularly preferred £0.08.
Anionically produced polyamides with these properties have to date not become known in the state of the art.
Substances which destroy the catalyst rapidly and irreversi¬bly are suitable as deactivator in the sense of the present invention.
Surprisingly, it has been shown that many classes of com¬pounds are able to do this. Of concern here are preferably protic compounds with an acidity constant pK which is less than approximately 14. Organic carboxylic acids in oligome-ric or low molecular form are used preferably; particularly preferred are also polymeric forms, whereby a stoichiometric 1 : 1 proportion of acidic functions to catalyst function is sufficient to destroy the catalyst entirely.
In the case of organic carboxylic acids, those are particu¬larly preferred in which the carboxylic groups are sterical-ly hindered, i.e. restricted and/or screened in their mova-bility. Included herein are in particular compounds, i.e. deactivators in a polymer or oligomer form in which the COOH groups are bonded to the main chain. Examples are indicated in claims 7 and 8.
Representatives from the group of carboxylic acids are: stearic acid, versatic acid or benzoic acid, and also polya-cids, such as for example dodecanedioic acid or also iso-and terephthalic acid and also oligomeric, wax-like pro¬ducts, such as for example oxidi2ed polyethylene waxes or else COOH group-containing polyamide oligomers which can be linear, branched or star-shaped with an average molecular weight of 500 - 10, 000 g/mol and also preferably also car-

boxylic copolymers with a wide molecular weight spectrum. Examples are ethylene(meth)acrylic acid copolymers, whereby many further comonomers, such as long-chained or branched olefins, carboxylic acid esters, esterified alcohols etc. can be used as comonomers as well. Examples of such comono¬mers are butene, alkyl(meth)acrylate, vinyl alcohol and vinyl acetate and also styrene.
It was shown unexpectedly that acidic polymers are also ex¬ceedingly suitable when their COOH groups are partly neutra¬lized with metal compounds and the counter-ions of the COOo groups are derived for example from Na, K, Ca, Zn, Li and Mg. Such polyolefin derivatives are described as ionomers (see Rdmpp) and in particular the so-called Zn ionomers are exceptionally compatible with polylactam, such as for examp¬le polylaurin lactam and hence also highly effective with respect to catalyst destruction. If they contain further comonomers in a proportion suitable for application, then they can in addition increase toughness and for example make the product flexible. The desired translucence of the po-lyamide is thereby often not lost or in fact is increased. In many cases, normal so-called EAA copolymers (ethylene acrylic acid copolymers), such as are produced for example by the firm DOW with a very varied acid proportion and MVR, are however suitable. The molar proportion of added COOH groups can constitute thereby a multiple of the basicity of the catalyst which is to be deactivated. The added EAA then operates preferably also as impact modifier.
In summary, it can be established, that in the case of orga¬nic carboxylic acids in low molecular, but particularly in polymer form, those are particularly preferred, in which the carboxylic acid is directly incorporated in the polymer chain with steric hinderance, i.e. the carboxylic group is bonded directly to the main chain (backbone). In the case of mono- and dicarboxylic acids and also oxidized waxes, in which the carboxylic group is easily acccessible, or in the case of olefins with grafted-on maleic acid where the steric
8

hinderance respectively is missing, the excess requires
however to be limited.
The invention comprises furthermore, in the case of deacti¬vators, the acids of phosphorus and boron. Acids of phos¬phorus in a raonoraeric and oligomeric form which have acidic groups of different acidity are hereby preferred. For ex¬ample, H3P04 and the condensation products resulting there¬from are suitable. In the case of acids of phosphorrus, it is advantageous that these have a plurality of buffer areas, neutralization in the basic region often being suitable. In Fig. 7, buffer areas for a) phosphoric acid (H3PO4) and for b) the linear aliphatic Carboxylic acids are illustrated.
The invention comprises all known lactams with respect to the starter component from a material point of view.
Particularly the representatives with 5 - 12 C atoms, in particular however lactam-6 and lactam-12 and mixtures the¬reof, are suitable as lactams, lactam-12 being particularly preferred because, even at temperatures of approximately 200 - 320 oC, preferably 200 - 300 °C and particularly preferred 200 - 280 °C, it can be converted into polylactam to at least 99% by weight and the conversion runs extensively irreversi¬bly.
Catalysts and catalyst systems which are described in the literature, in particular metal lactamates or lactamate-forming compounds are suitable as catalysts.
Examples are sodium and magnesium lactamate and further ma¬gnesium compounds which are known from the literature. The mainly used catalyst is however commercially available sodi¬um caprolactamate dissolved in caprolactam.
The activators used within the scope of the invention are known.
9

Activators operate as starters - initiators of the anionic lactam polymerisation, by activating the CONH bonds of the lactam and thus, upon admission of lactamate, initiating the starting reaction of the anionic polymerisation. Common commercially available activators are for example N-acylated lactams, such as for example N-acetylcaprolactam. Compounds also reacting directly with the lactam, such as isocyanates, which can also be capped according to the normal state of the art, and carbodiimides are often used which activate the CONH bond after acylation of the lactam. Examples of this are for example hexamethylehe diisocyanate or phenyl isocya-nate which can also occur trimerized in the isocyanurate form. If for example a diisocyanate is thereby used, then the polylactam chain grows after addition of the catalyst, or lactamate in two directions, if a monoisocyanate, such as for example phenyl isocyanate or also stearyl isocyanate, is used, the chain grows in one direction, these rules applying preferably as long as an excess of free lactam is present.
A preferred class of substances for implementing the descri¬bed invention are catalyst-activator systems as are descri¬bed for example in DE 197 156 79.
These are distinguished by the fact that only one formulati¬on which in addition occurs preferably as an easily dosable liquid must be added to the lactam, in particular to the lactam melt.
According to patent claim 16, the invention relates further¬more to a method for producing polyamides as described abo¬ve.
Anionically polymerized polylactam, in particular polycapro-lactam has been used to date almost exclusively in the mono¬mer casting process often for large volume parts, such as for example crane jibs because the procedure can start from a low viscose easily pourable melt. High fractive strength in particular is sought after and the molecular structure
10

has no special requirements to satisfy with respect to recy¬cling for example in thermoplastic shaping processes- Be¬cause of good processability in thermoplastic processes and thereby stability against degradation during remelting, to¬day hydrolytically produced polylactam is used almost exclu¬sively for the so-called thermoplastic shaping processes.
Formulations and methods for simplified production of poly¬lactam which can then be further processed easily and wi¬thout degradation and leads to parts of good application properties, therefore represent a substantial technical pro¬gress,
It has been shown astonishingly that the method according to the invention leads in particular to polyamide in granulate form, which can be shaped thermoplastically in an easy and stable manner into parts, such as for example pipes of a high application value.
The new method in the preferred embodiment is distinguished in that a lactam melt is converted by means of a catalyst-activator system with suitable reaction control until a lac¬tam conversion of at least approximately 90% by weight, pre¬ferably 99% by weight of lactam-12, is effected, after which a deactivator is added which irreversibly destroys the cata¬lyst, if necessary further processing steps follow directly, then a part is directly formed or the melt is converted di¬rectly into granulate which then can be processed thermopla¬stically into objects of high application value according to common methods.
The new process is suitable in particular for continuous me¬thods, for which twin screw extruders with co-rotating screws and with special processing elements are particularly suitable.
However, the process can be conducted also in several steps by activating for example a lactam melt in a continuous

process, for example by means of a dynamic (rotating) or al¬so static continuous mixer with the catalyst/activator and then by polymerizing under constant feeding, for example in a single screw or also a twin screw extruder with suitable choice of temperature and residence time until the lactam is just converted into polylactam and then by removing and gra¬nulating it. Subsequently, the deactivator is added as far as possible at the beginning of the remelting process in a second extrusion passage, for example in an extruder for compounding tasks, such as for example a twin screw extru¬der, and is intermixed into the melt, the incorporated of all further compounds and additives, which are required for a commercial product, being then able to follow.
The method can also be implemented in varied ways, the main aim residing in attaining a polyamide which is stable during processing and which can be shaped without substantial de¬gradation via melt processing into parts of a high service value.
At the beginning of implementation of the method it is of particular advantage that the catalyst/activator is distri¬buted rapidly and homogeneously in the lactam melt and that the chain growth proceeds as uniformly as possible and that, after completion of the lactam conversion, the catalyst is destroyed rapidly and in the entire now-viscose polylactam mass. This presents process-technological requirements which suggest implementing the whole method in a continuous¬ly mixing machine with the necessary supply and mixing ele¬ments. Twin screw extruders with co-rotating screws, such as for example the commercial machine ZSK-25 of the company Werner and Pfleiderer, Stuttgart which can be equipped in an extraordinarily variable manner, with respect to process lengths, dosing devices, mixing and barrier elements, is suitable for optimizing the formulations and method conditi¬ons adapted to the application.

In the feed zone of the extruder, the lactam can thereby be melted or the extruder can be supplied with lactam melt also for example from a supply tank in a continuous manner. Now addition of the catalyst/activator into the lactam melt should be effected with rapid homogeneous mixing so that the polymerisation is started as simultaneously as possible in the entire polylactam melt. This step can be implemented according to many alternative methods by processing for ex¬ample according to the 2-pot principle which is well known in lactam polymerization or by adding solid catalyst as a solid material solution of sodium caprolactamate in capro-lactam to the lactam in a solid or already molten form and then adding the activator, such as for example a liquid isocyanate, which can also occur in a capped or cyclized form or also dissolved/ or of N-acylated lactam to the cata¬lyst-containing lactam melt.
Systems, which directly initiate the polymerization and which hence contain simultaneously the function of catalyst and activator, are particularly suitable. Particularly pre¬ferred thereby are those systems which occur in a liquid form and which for example can be metered into the lactam melt directly by means of a liquid metering pump at a con¬stant volume proportion, or which can be added directly via a static mixer to the lactam melt. Systems of this type are described in DE 197 15 679 A1,
After completion of the catalyst-activator addition and ho¬mogeneous mixing, the polymerisation process follows, pre¬ferably a plug flow is maintained so that all growing poly¬lactam chains have as far as possible identical growth con¬ditions which are defined in particular by the temperature in this zone and of course by the residence time.
As soon as the aimed lactam conversion is achieved (lactam-6 approximately 90%, lactam-12 approximately 99 - 99.9%), the catalyst activity is stopped by rapid and homogeneous mi-xing-in of the deactivator, and thereby the catalyst is de-

stroyed. On effecting the method continuously, the addition zone for the deactivator should be separated from the poly¬merization zone in such a manner that as far as possible no backflow of deactivator into the polymerization zone occurs. The deactivator which can be used as a single substance or also as a substance mixture is often able to perform supple¬mentary effects in the polylactam.
Preferably, the deactivator is therefore used as a substance mixture. All compounds described in the case of the polya-mide are possible as deactivator.
If the deactivator is a long-chain acidic alkene containing comonomers such as for example butene, hexene, octene etc. or alkyl esters, such as for example originating from buty-lacrylate, it can also have a flexibilizing effect and si¬gnificantly increase the toughness.
If the deactivator is an ionomer, for example based on Zn or Na or an EAA-copolymer which during the deactivation reac¬tion also becomes an ionomer, and for example containing co-monomers, such as for example alkylacrylate, then for examp¬le translucence is achieved together with high toughness and high flexibility which represents an additional advantage for particular applications. Such deactivators can also contain a high excess of COOH groups which are directly in¬corporated in the chain as long as the deactivator fulfils its supplementary objectives, such as for example an impact strength increase.
Different deactivators can of course be combined with each other according to the requirement of the final product. The deactivators can thereby be introduced in different ways, for example as a master batch in for example granulate form.
Deactivators of a polymeric nature or also pulverulent types are introduced into the melt for example via metering belt
14

scales or a stuffing screw, of course the rules for metering and mixing, which are known from the state of the art, re¬quiring to be observed. Deactivators can of course be fed also in a molten form via a so-called side-feeder".
Together with the various deactivators or also subsequently, further additives, such as minerals, glass fibres/ flame re-tardants, impact modifiers, colourants, stabilisers etc. and mixtures thereof can be added to the polylactam melt with the aim of providing a market product of good proeessabili-ty.
After that, these additives are mixed-in homogeneously and the ready formulated polylactam melt is supplied under pres¬sure to the output nozzle of the extruder, and following normal technology, is converted into a granulate form or, in a suitable tool, for example a pipe head, is directly shaped for the application task, for example a covering or a coa¬ting, a pipe or a profile.
It has been shown that the method according to the invention as described previously is implemented best at temperatures of 140 - 320 °C Preferably, temperatures of 140 - 300 °C, particularly preferred 140 - 280 c are however used hereby.
The invention is now explained in more detail with reference to examples which represent only a selection of the various possibilities with respect to implementation and applicati¬on.
It has been shown thereby that, within the scope of the in¬vention, various method variants can be applied in order to avoid chain length degradation of anionically polymerized polylactam during processing via the melt and in order to obtain polyamide of a stable restricted molecular weight.
According to the patent claims 28 to 33, the invention rela¬tes furthermore to a method for reprocessing anionically

produced polyamide.
A particular application of the method according to the in¬vention, as explained above, is thereby of concern. It was presented already at the beginning that the method according to the invention, as characterized in patent claim 16, can also be implemented in two steps. Within the scope of the invention, it is therefore fundamentally not required that the steps a (polymerization) and b (deactivation) are imple¬mented in succession but instead that also a fairly large time span, for example several days or even months or even a first application or life cycle, for example as matrix in a composite material or as a cast part can lie between step a and b. This implies in other words that the method accor¬ding to the invention can also be implemented for polyamide which was already produced anionically a long time ago and that is treated with the deactivator as explained in patent claim 16. Hence the method according to the invention is suitable, as it is now characterized particularly by the pa¬tent claims 28 to 33, also for reprocessing of already pre¬sent anionically produced polyamide. According to the in¬vention, the deactivator is added thereto in such a quantity that at least the basicity still present from the catalyst system is neutralized. Then the mixture is melted and ex¬truded in a manner which is known per se, optionally by ad¬ding auxiliary agents such as further matrix material, car¬bon black or stabilizers.
The reprocessing method according to the invention is parti¬cularly of advantage when the polyamide is present mixed with fibres. The method of the invention according to the patent claims 28 - 33 is preferably applied for filament structures, such as for example woven fabric, hosiery fabric, knitted fabric or plaited material, in a polyamide matrix in the form of a composite material.
It is then provided according to the method that these com¬posite material parts are comminuted, followed by mixing

with the deactivator according to the invention. This mix¬ture is then subjected preferably to a continuous melting process in a twin screw extruder, whereby the melt is homo¬genized. Preferably the melt is then withdrawn as a strand via an aqueous cooling bath and cut into granulate.
In this way, a fibre-reinforced polylactam granulate of high service value is achieved which can be shaped by common thermoplastic processes, in particular by injection moulding into parts with new application pqssibilitiefs. Without the method according to the invention often no material recy¬cling was possible previously.
The present invention relates to polyamide with low viscosity decomposition after re-melting, producible by anionic polymerisation of lactam in the presence of alkaline catalysts and, if appropriate, activators, characterized in that the polyamide contains a protic compound as deactivator, selected from organic carboxylic acids in oligomer or polymer form and/or acids of phosphorus and boron with the protic compound still present in its protic form at least in a residual proportion of 1% of the initial value, with a relative viscosity (nrel)of al.55 as measured on a 0.5 weight-% solution in m-cresol as claimed EN ISO 307 and during re-melting at 275°C and a water content of below 0.15 weight-% a viscosity corrected decomposition.
VKA= Anrel of o.13
(nsp.12)2 In the following summary, the abbreviations used in the ex¬amples and comparative examples are explained.
Compilation of the abbreviations of the Examples
1. Deactivators

Designation Manufacturer Comments
Surlyn 9320 & 9120 Du Font, Delaware, Ionomer, partially neutralized with zn
Primacor 3340 Dow, Horgen, CH Ethylene acrylic acid copolymer; €.5% acrylic acid
Lucalen 292a BASF, Ludwigshafen Copolyolefin with 4% acrylic acid
Luvax EAS BASF, Ludwigshafen Polyethylene wax with 5.5% acrylic acid

According to requirement/ additionally ethylene distearamide of trade name Acrawachs-C from Lonza (Basel, CH) was used as processing aid in the injection moulding process (for impro¬ved extruder feed), whereby Acrawachs-C has no deactivator function-
2. Analysis and test methods
• nrel = relative viscosity, measured as a 0.5% by weight solution of polyamide in m-cresol accor¬ding to EN ISO 307.
• MVR (previously also often described as MVI), the volume melt index in cm3 per 10 min. measured af¬ter a melting time of 4 min. at 275 oC and a load of 5 kg according to EN ISO 1133. Specific mel¬ting conditions are also established in this norm which are practical and which can be used for de¬termining the viscosity degradation nrel or of VKa by using a MVR apparatus .
• MGV = molecular weight distribution. This was determined after derivatisation of the samples with trifluoroacetic acid anhydride in tetrahy-drofurane as solvent by means of GPC {Gel permea¬tion chromatography) . The polydispersi/ty D Ww/Mn was determined therefrom (cf. Rompp) .
3. Mechanical values
• S2Z bars: Impact tensile bars, 1mm thick
• SZZ: tensile impact strength, in kJ/mm2
• Heat storage: according to ICE 216
• weathering: according to ISO 4892-2
Tests 1-6 and comparative test. XI
In order to perform the tests 1- 6, the process was imple¬mented in two steps so that initially anionically polymeri¬zed polyaraide-12 in granulate form was produced by the con-

tinuous method and this was subsequently reprocessed into test pieces by injection moulding with the addition of sup¬plements destroying the catalyst activity (deactivators).
In order to produce the granules, lactam-12 pills were pre-dried and then supplied continuously to a twin screw extru¬der, ZSK-25, of the firm Werner and Pfleiderer Stuttgart, using a common compounding screw and usual process conditi¬ons, namely 150 rotations per minute, a constant set tempe¬rature of all barrel sections of 270 oC, and a throughput of 10 kg/h. Directly after melting the pills, the liquid cata¬lyst, as described in DE 197 15 679, was injected in such a quantity that 1 equivalent (Val) of active liquid catalyst is present per 225 mol parts of lactam-12. The liquid cata¬lyst immediately initiates the polymerization so that a com¬pact polymer strand can be withdrawn at the nozzle, which strand is then cooled in a water bath, followed by granula¬tion and drying of the granulate ready for processing.
In order to obtain a first overview of the effectiveness of the substances according to the invention which destroy the catalyst, the granulates were pre-mixed with the correspon¬ding additives and these mixtures were injection moulded on a commonly used injection moulding machine, type Arburg-Allrounder 320-210-750 Hydronica, into 4 mm thick ISO tensi¬on bars, normal injection moulding conditions being main¬tained corresponding to a melt temperature of 258 °C, a mould temperature of 40 °c and a cycle time of 50 seconds.
The results are compiled in Fig. 1 {Table l), tests designa¬ted respectively with X being comparative tests.
They show how, by using the deactivators according to the invention which are only applied onto the granulate before the injection moulding operation, the degradation on melting is very substantially reduced.

In test XI, where pure, anionically polymerized granulate was injection moulded identically into test pieces/ a very much higher viscosity degradation occured. The measured vo¬lume melt index values also confirm the strong degradation during remelting of anionically polymerised PA12 granulate on the comparative test XI where no deactivator was added. At the same time the low MVR values of tests 1-6 verify that only a low degradation occurs during melting if deacti¬vators according to the invention are mixed into the melt during the injection moulding processing.
The following tests describe the continuous production of anionically polymerized polyamide granulate according to the invention which is of high stability in the melt state with respect to viscosity degradation.
This new polyamide granulate can be processed exceptionally well via the melt state by thermoplastic shaping processes such as injection moulding and extrusion into pipes/ films and coatings of high service value.
The polyamide granulates produced according to the new processes have property combinations not known to date so that parts produced therefrom have in addition to good heat stability, very good weathering stability and an extraordi¬narily high hydrolysis stability in aqueous media. Pipes produced therefrom have for example a high degree of low temperature toughness not known to date and also high resi¬stance to internal pressure even at temperatures up to 130 °C.
In order to produce the polyamides according to the inventi¬on in granulate form, the process can be implemented for ex¬ample in two stages by proceeding for example in a first ex¬trusion passage as in the case of test 1-6 and thereby converting laurin lactam into polylaurin lactam by means of a liquid catalyst according to D£ 197 15 €79.

In a second extrusion passage, the components which destroy the catalyst and often at the same time are able to take up the required supplementary functions are added.
The deactivator is thereby melted preferably under mild con¬ditions and with intensive mixing together with the polylac¬tam granulate produced in the first process step so that its effect is rapidly developed by neutralizing in particular the strong basicity of the melt. Further components of the formulation required for practical application, such as sta¬bilizers/ plasticizers, colourants, such as carbon black and further necessary additives, can be introduced for example directly into the melt also at a later stage of the extrusi¬on process or in the case of liquids, such as plasticizers, can be injected directly into the melt.
Alternatively, the process can be implemented however also in a one stage method, the continuous conversion of the lac¬tam into polylactam being effected in a first process step, preferably by means of a liquid catalyst, and an appropriate design of the extruder, then the melt being stabilized against viscosity change by means of the deactivator which neutralizes the catalyst activity and simultaneously or sub¬sequently further components being added to the final formu¬lation and then being mixed-in, then the melt being dischar¬ged as a strand, being cooled and the solidified strand being granulated so that after drying a processing-ready granulate is present or the melt being supplied directly in¬to a tool for shaping.
The one stage production process requires furthermore only an average residence time of approximately 2 minutes, the deactivation in the second extruder zone being included. The high economic efficiency is thereby demonstrated if one considers that several hours are required for the hydrolytic production of polylactam.

The process conditions are in principle able to be varied within a wide range.
Preferably however the procedure is implemented in such a way that the polymerisation time in the chosen set conditi¬ons of the extruder, such as tempering of the heat rones and screw speed, is just adequate to convert 99 - 99.8% by weight of the lactam-12 and after that the catalyst is de¬stroyed by addition of the deactivator. In the case of lac-tam-6/ polymerization takes place preferably in the known, temperature-dependent range of the monomer/polymer equili¬brium. If the two step process is thereby used, this can be achieved easily by appropriate setting of temperature con¬trol, throughput and screw speed.
Comparative teste X3, X4, and X5 and examples 10 - IS
By use of the twin screw extruder, ZSK-25, polyamide-12 gra¬nulates were again produced using the normal compounding screw and starting from laurin lactam and liquid catalyst.
The test conditions and the test results of the comparative tests are compiled in Fig. 2 (Table 3).
As the analysis results show, the melting with only one pas¬sage through the MVR appliance effects already a considerab¬le viscosity degradation.
Tests 10 - 15
The PA-12 base granulates, produced in the comparative test X3 - X5 and still viscosity-unstable, were now pre-mixed with the deactivators according to Fig. 3 {Table 4} and the substance mixtures then were melted gently on a twin screw extruder ZSK-30, equipped with a compounding screw, so that the deactivators are able to exert their influence of cata¬lyst deactivation and modification of the melt, liquid addi¬tives/ in particular plasticizers, being injected into the

melt directly in a later stage of the compounding. The melt which now contains the catalyst residues in deactivated form and also additives mixed-in homogeneously, is then introdu¬ced into an aqueous cooling bath via a nozzle, the solidi¬fied strand is granulated and the granulates are dried, af¬ter which a processing-ready, processing-stable granulate is present. This can be processed dependent upon the formula¬tion into plasticized PA-12 pipes, into injection moulded parts, into sheaths of cables, into foils and into coatings via thermoplastic processes without degradation occurring and into finished parts which have excellent properties. The formulations and properties of the PA-12 moulding com¬pounds according to the invention are compiled in Fig. 3.
The measurement of the nrel values proves impressively that, both during MVR measurement and also during processing into pipes and cable sheaths, the new polyamides are viscosity-stable during rerne1ting.
Test 16-19
During these tests, the following goals were striven for:
1. The polymerization and the compounding must be effected in one extrusion step.
2. During compounding, effective heat- and weathering sta¬bilizers should be incorporated into the melt.
3. The behaviour of test pieces made of polyamide moulding formulations according to the invention should be te¬sted in a comparative test under heat and light effect (weathering).
For this purpose, the extruder, ZSK-25, which was used al¬ready in the previous polymerization tests was used, but the twin screws were modified such that the feed and the melting of the lactam-12 pills was effected approximately in the

first third, then the already previously described liquid catalyst was metered continuously into the melt, so that the polymerization of the lactam proceeded in the second third of the extruder, the extruder shafts were subsequently fit¬ted with elements preventing backflow of viscous melt, sub¬sequently in the last third, the deactivator and the stabi¬lisers were metered into the melt via a so called "side-feeder" and then were mixed-in homogeneously, the melt was then withdrawn as a strand, this was granulated and the gra¬nulate was dried to a processing-suitable water content of lower than 0.15% by weight.
The following conditions were maintained in the polymeriza¬tion zone:
• 1 mol equivalent of liquid catalyst was added continuously per 200 parts of lactam-12
• the extruder housings after the injection point of the catalyst were set at 290 °c
• the rotational speed was set at 200 rpm with a total mass throughput of 14 kg/h.
Temperature increase to 290 °C was effected in order to ac¬celerate conversion because, during implementation of this test/ only 1/3 of the extruder length was available for the polymerisation.
In order to increase the total quantity of additives metered into the melt via side-feeders to at least 5% by weight/ partly anionically polymerized PA12 granulate (PA12, A) from previous tests was metered into the melt together with the recipe components.
The following combination of stabilizers was used for all tests (even X6): 0.3% by weight Irganox 245, 0.15% by weight Irganox P-EPQ (= stabilizers by Ciba, SC, Basel) and also

0.5% by weight Nylostab S-EED (= stabilizer by Clariant).
The added deactivators are represented in Fig, 4 (Table 5a). Test X6 once again represents thereby a comparative test, in the production of which no deactivator was added in the nar-row sense.
The relative viscosity nrel, the MVR and subsequently again nrel in the sample after MVR measurement were determined. The difference nrel of both relative viscosities corresponds to the degradation during melting which is however dependent upon the starter value* The inventors have however found the surprisingly simple empirical formulation that the viscosity-corrected degradation, calculated according to the formula VKA=nrel (nap1)2, for a specific material composi¬tion remains, independently of the starter value of the re lative viscosity, virtually constant (nsp=1 being the speci¬fic viscosity before melting, with nep (nep=l) . Thanks to this knowledge, VKA is a characteristic dimension for eva¬luation of the degradation stability of the polyamide. Mo¬reover, the molecular weight distribution was measured.
Furthermore DIN impact tensile bars were moulded from the granulates and these were subjected to a heat test at 150 °C. Likewise, a rapid weathering test was implemented in a Wether-0-meter appliance.
The results of all these tests are contained in Fig. 5 (Ta¬ble 5b).
It should be taken into account during evaluation of the tests in Table 5b that the stabilizers used in comparative test X6 already act upon the catalyst up to a certain degree in a deactivating manner so that the viscosity degradation in the MVR test is smaller than in corresponding measure¬ments on pure, anionically polymerised granulate.
5

The MGV measurements are interesting. It should be taken into account that the polymerization conditions on the ex¬truder were chosen such that polymerization is essentially finished after 2/3 extruder length.
During test X6, where the catalyst activity is maintained at least in part, a broader MG distribution resulted and in particular many short-chain molecule fragments are produced.
In the tests 16 - 19 on the other hand, the effectiveness of the catalyst is stopped entirely by the deactivator and the molecular weights remain high with a D-value close to 2, as is common also in hydrolytically produced polyamide.
In the tests 16 - 19, the results are somewhat worse where the low-molecular compound Luvax EAS (EAS ethylene acrylic acid) was used. They are particularly good in tests 16, 18 and 19 where high-molecular acidic compounds are used as de¬activator.
The effect of the higher molecular weight of these compounds is demonstrated also in the heat test at 150 °C where the variant X without deactivator fails already after 72 hours, followed by the variant Luvax EAS whilst then in the tests with high-molecular weight deactivator a substantial de¬crease in strength only occurs after 8 days.
During rapid weathering in the Wether-0-meter, all variants display exceptionally good behaviour up to 2000 h.
With respect to the level of the SZZ values, the following substantial correlation should be taken into account.
The solvation agent contained in the liquid catalyst greatly affects the increase in toughness so that also finished parts based on lactam-12 polymerised with liquid catalyst have a high toughness and fracture strength. If such parts are now subjected to extreme heat effect, for example a heat
26

test at ISO °C then the solvation agent of the used liquid catalyst is initially evaporated and the tensile impact strength falls to the normal level of PA12, as it is known for hydrolytically produced PA12. This relevant plateau is then maintained until the effectiveness of the stabilizer combination recedes. The half-life rule which is hydrolyti¬cally common with PA12 must therefore not be applied for evaluation of the heat resistance but instead the achieved level of toughness after evaporation of the solvation agent must be selected for example after 48 h heat effect as the basis for the subsequent drop in strength.
Tests 20 - 24
The tests 20 - 24 relate to further testing of deactivators of anionic catalysts for the polymerization of lactam.
For this purpose, anionically polymerized PA12 granulate was produced without additives as a first stage under mild con¬ditions with a simple compounding screw on the ZSK-25 in one extrusion passage.
Polymerization was thereby implemented at a temperature set¬ting of the housings of 260 oC respectively, a rotational speed of 150 rpm and with a throughput of 13 kg/h, and a ca¬talyst to LC-12 mol ratio of 1:125.
As already described previously, this granulate was then re-extruded on a ZSK-30 with additives according to Fig. 6 (Ta¬ble 6). The deactivators and the base granulate were there¬by supplied together to the extruder and melted so that they were able from the start to exert their deactivating effect.
The additives used and the effect of the deactivators which stabilises the viscosity of the melts, is illustrated by me¬ans of nrel and MVR measurements in Table 6.
27

As the measured, mechanical values on test pieces produced by the injection moulding method prove conclusively, test pieces with excellent mechanical properties based on the PA12 granulates according to the invention result despite the relatively low molecular weight.
28

Documents:

328-mum-2002-abstract(17-03-2008).doc

328-mum-2002-abstract(17-03-2008).pdf

328-mum-2002-cancelled pages(17-03-2008).pdf

328-mum-2002-claims(granted)-(17-03-2008).doc

328-mum-2002-claims(granted)-(17-03-2008).pdf

328-mum-2002-correspondence(17-03-2008).pdf

328-mum-2002-correspondence(ipo)-(29-03-2007).pdf

328-mum-2002-drawing(05-04-2002).pdf

328-mum-2002-form 1(17-03-2008).pdf

328-mum-2002-form 13(17-03-2008).pdf

328-mum-2002-form 18(08-02-2006).pdf

328-mum-2002-form 2(granted)-(17-03-2008).doc

328-mum-2002-form 2(granted)-(17-03-2008).pdf

328-mum-2002-form 3(16-07-2002).pdf

328-mum-2002-form 3(17-03-2008).pdf

328-mum-2002-form 5(17-03-2008).pdf

328-mum-2002-petition under rule 138(17-03-2008).pdf

328-mum-2002-power of attorney(17-03-2008).pdf

328-mum-2002-power of attorney(23-07-2002).pdf

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Patent Number

218474

Indian Patent Application Number

328/MUM/2002

PG Journal Number

19/2008

Publication Date

09-May-2008

Grant Date

02-Apr-2008

Date of Filing

05-Apr-2002

Name of Patentee

EMS-CHEMIE AG

Applicant Address

REICHENAUERSTRASSE, CH-7013 DOMAT/EMS, SWITZERLAND

Inventors:

#	Inventor's Name	Inventor's Address
1	IVANO LAUDONIA	Neudorfstrasse 60, CH-7430 Thusis
2	HANSJORG ERNST	Via Salens 5, CH-7402 Bonadoz
3	WERNER KAGI	Via Rudera 8, CH-7013 Domat/EMS
4	EDUARD SCHMID	VALBEUNA 12, CH-7402 BONADUZ, SWITZERLAND

PCT International Classification Number

C08G69/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10118453.0	2001-04-12	Germany