Title of Invention	PREPARATION OF BROMINATED STYRENIC POLYMERS OR RESINS
Abstract	Abstract Bromination of styrenic polymer is carried out in aclosed reaction system to retain HX coproduct (where HX is HBr or HCl, or both) in the bromination reaction mixture at superatmospheric pressure. Preferably, the reaction mixtuire which includes the brominated styrenic polymer and substantially all of the HX coproduct forced is discharged into an aqueous quenchingg medium. By operating in this manner, the reaction is terminated and the brominated styrenic polymer of desired bromine content and substantially all HX coproduct are captured in the same operation, process equipment costs are reduced, and processing of the reaction mixture is facilitated.

Title of Invention

PREPARATION OF BROMINATED STYRENIC POLYMERS OR RESINS

Abstract

Abstract Bromination of styrenic polymer is carried out in aclosed reaction system to retain HX coproduct (where HX is HBr or HCl, or both) in the bromination reaction mixture at superatmospheric pressure. Preferably, the reaction mixtuire which includes the brominated styrenic polymer and substantially all of the HX coproduct forced is discharged into an aqueous quenchingg medium. By operating in this manner, the reaction is terminated and the brominated styrenic polymer of desired bromine content and substantially all HX coproduct are captured in the same operation, process equipment costs are reduced, and processing of the reaction mixture is facilitated.

Full Text	BACKGROUND [00011 Commonly-owned U.S. Pat. Nos. 5,677,390. 5.686,38, 5,767,203. 5,852,131, 5.852.132, 5.916,978, 6,113,381, 6,207,765, 6.232,93, 6,232.408, 6,235.831, 6,235,844, 6.326.439, and 6,521,714 describe what is believed to be the best previously-published process technology for producing brominates styrene polymeric such as brominated polystyrene having the best pointiest of those of any previously-published brominated styrene polymer. In this connection, the terms "brominated styrene polymer" and "brominated polystyrene" as used in the specification and in the claims hereof refer to a brominated polymer produced by bromination of a pre-existing styrenic polymer such as polystyrene or a copolymer of styrene and at least one other vinyl aromatic monomer, as distinguished from an oligopoly* or polymers- produced by oligomerization or polymerization of one or more brominated styrenic monraners, the properties of the latter" oligomers or polymers typically being considerably different from brominated polystyrene in a number of respects. [0002] The processes for preparing brominated polystyrenic polymers described in the foregoing commonly-owned patents teach the desirability of removing co product that is usually found in the head space of the brominatioa reactor by passing such bead space vapors into a scrubber, followed by viding a cook period for the bromination reaction mixture to allow bromination to continue to the desired extent, and then terminating the bromination reaction with a suitable aqueous medium. Such an operation is of economic importance since the HBr co product is of value either for use as HBr or for conversion to other commercially desirable products, such as bromine itself. In cases where bromine chloride is used as the brominating agent, HCL is formed as a coproduct, [0003] Despite the excellence of such prior technology, new improvements, especially in the manner of conducting the processes, are always welcome. This invention is deemed to provide at least one such new improvement BRIEF SUMMARY OF THE INVENTION [0004] This invention enables the valuable bromine values to be recovered from the styrenic polymer- bromination reaction mixture in a highly efficient manner. The invention also reduces the capital required for conducting the overall process by eliminating equipment typically used in the plant facilities for stubbing HX gases vented from the bromination reactor in order to keep HX gas from entering the environment and for absorbing organic solvent vapors from such gas. Further, reaction mixtures framed in a brominationprocess of this invention can be more readily processed in the plant than corresponding conventional styrenic polymer bromination reaction mixtures in as much as the HX can serve as an [0005] In accordance with one embodiment of this invention there is provided a process of preparing a abominated styrcnic polymer having a bromine content of at least about 50 wt%, and preferably at least about 60 wt%, and still more inferably at least about 67 wt% by brominating styrenic polymer, wherein said process is characterized by conducting the abomination in a liquid phase reaction mixture under superattnospheric pressure in a closed reaction system so that gaseous HX coproduct is notieleased on said closed reaction system separately and apart from said reaction mixture. Stated in other terms, the invention of this embodiment is in a process wherein a brominated styrenic polymer having a bromine content of at least about 50 wt%, and preferably at teats about 60 wt%, and still more preferably at least about 67 wt% is prepared by brominating styrenic polymer. The improvement in such process comprises ccMiducting the bromination In a liquid phase reaction mixture under super atmospheric pressure in a closed reaction system so that gaseous HX Product is not released from said closed reaction system squarely and apart from said reaction mixture. [0006] The above embodiment of this invention (in whichever of the two forms in which it is stated above) enables: A) capture within the bromination reactor of substantially all coproduct HX along with and as a part of the reaction mixture formed in a batch bromination conducted in the closed reaction system; or 6) removal of substantially all coproduct HX along with and as a part of the reaction mixture existing after completion of a batch bromination of styrenic polymer conducted in the closed reaction system; ai C) removal of substantially all coprodtK:t HX aloe, with and as a part of the reaction mixture being formed in a continuous bromination of styrenic poem, conducted in a closed reaction system, hi each of A), B), and C) the brominated styrenic polymer and the coproduct HX can then be separated and recoding [0007] In accordance with another embodiment of this invention there is provided a process for the preparation of a brominated styrenic polymer having a bromine content of at least about 50 wt%, and preferably at least about 60 wt%, and still mars preferably at least about 67 wt%, said process characterized in that a styrenic polymers is brominated under superatmospheric pressure in the presence of a Lewis acid bromination catalyst and in a closed reaction system in which substantiaUy all of the HX coproduct is retained in the reaction mixture until the catalyst is quenched either in the reaction zone or externally from the reaction zone. from the organic phase containing the brominated stymieing polymer. lo cases where HX is HBr, it is preferred to recover the bromine values in the aqueous phase by (i) steam stripping the aqueous phase to remove residual organic solvent from the aqueous phase and thereby provide a bydrobromic acid product suitable for use or sale; (ii) converting the HBr in the aqueous phase to elemental bromine; or (iii) reacting the HBr with an aqueous metallic base to nieces a solute of a metal bromide salt suitable fin- use or sale. [0009] In a batch bromination process of this invention Ate. liquid reaction mixture comprised of brominated styrenic polymer and substantially all coproduct HX can be quenched in the reaction vessel in which they are formed, or the liquid reaction mixture comprised of bromioated styrenic polymer and substantially all ccqiroduct HX can be removed from reaction vessel in which they are formed and quenched in a separate quenching zone. In this latter case the liquid reaction minutiae comprised of brominated styrenic polymer and coproduct HX is kept under pressure, preferably in confinetnent as it is transported within piping, conduits, or the like, extending from the reaction vessel into the sqiarate quenching vessel and released within dte body of a liquid quenching medium, prefen)ly an aqueous quenching medium, contained in the quenching vessel so that gaseous HX does not esc,>e into the surroundings. [0010] By "closed reaction system" in connection with a batch process in. which the bromination and quenching are to be carried out seriatim in the same reaction vessel is meant that except fn- piping or conduits carrying the necessary components (including purging earner gases, liquid quenching medium etc.) into and out of the dominations reaction vessel, the system is closed from its surroundings. In short, the system is designed such that gaseous HX coproduct does not sack from the system, but rattier is caused to remain within the confines of the reaction vessel under sufficient pressure so that substantially all of the HX coproduct remains within and is part of the reaction mixture unto quenching whereby the HX is captured in the quenching medium concurrently with deactivation of the bromination catalyst. When HX is HBr, the bromine values are then recovered in a suitable form ami when HX is HCl, the HCl can be recovered, e.g., as hydrochloric acid, if desired. [0011] By "closed reaction system" in connection with a batch process or continuous process in which ttie bromination and quenching are to be carried out, or aie carried out, in separate vessels or zones is meant that exec>t for ping or conduits carrying the necessary components (including purging carrier gases, if used, etc.) into and out of the rumination reaction vessel or zone and into and out of the catalyst deactivaticMi vessel or zone, the system is closed &om its surroundings. In short, the system is designed such that gaseous HX coproduct does not excel from the system, but rather is caused to travel from the rumination until quenching whereby such coproduct HX is catered in Hire quenching medium concurrently with deactivation of the bromination catalyst Here again, when HX is HBr, the bromine values are then recovered in a suitable fen, and when HX is HCl, the HCl can be recovered, e.g., as hydrophilic acid, if desired. [0012] By conducting the process in accordance witii this invention, emendated styrenic polymer of desired bromine content and substantially all WX. ct,nnduct are catered in the same operation (quenching), process equipment costs aye Focused, and hissing of the reaction mixture is facilitated. [0013] These and other embodiments and features of this invention will be still further ,)parent from the ensuing description, accompanying drawings and upended claims. BRIEF Descriptor OF THE DRAWING [0014] Figure I is a schematic flow diagram of a lHtHiiination\|wocess of this invention that can be used for producing brominated satanic polymers. FURTHER DETAILED DESCRIPTION [0015] One of the features of this Invention is the fact that the process of this invention can beapphedto any process for producing brominated stryrBnicpolymeis, including preferably, those of the commonly-owned patents described at the outset of this document. [0016] Thus for exanqrle, the process for brominating styrenic polymers can be a process which comprises forming a reaction mixture by fee a mixture (t) wide is substantially free of a bromination catalyst and (il) which is formed from at least a brominating agent and a styrenic polymer, to a catalytic quantity of a bromination catalyst, this being exemplary of process technology first described in U.S. Pat No. 5,677,390. [0017] Similarly, the process for brominating styrenic polymer can be a process which comprises feeding a first stream comprising brominating agent, a second stream comprising styrenic polymer and a third stream comprising bromination catalyst to a mica to intimately mix such streams, this being exenqilary of process technology first described in U.S. Pat No. 5,686,538. [0018] Also, the process for brominating styrenic polymers can be a process which comprises contacting styrenic polymer with brominating agent in the presence of Lewis acid catalyst and solvent quantities of tromochlcKXimethaae, this being exenqilaiy of process technology first described in U.S. Pat. No. 5.767,203. [0019} In each of the above processes described in U.S. Pat No. 5.677,390; 5,586,538; or 5,767,203, such process is iroprovedpiusuaot to this ingratiation by conducting the brominates in a closed reaction system under superatmospheric pressure which is typically up to about 60 psig, to retain substantiality all of the HX coproduct in a bromination reaction mixture, and tenanting the bromination by quenching the reaction mixture which connives brominated strum pulpier and substantially all of the coproduct HX, in an aqueous quenching medium. F,ferably the brominated strums polymer and the HX coproduct are separated and recovered &om at least a portion of the aqueous quenching mixture formed during the quenching. [0020] ID addict to the fate going, still another toxics of this invention is a process fcK-brominating styrenic polymers which process commixes concurrently feeding a first stream comprising brominating agent and a bromination catalyst, and a second stream comparing styrenic polymer to a reaction zone wherein: A) the bromination is conducted in a closed reaction system to retain HX coproduct in a bromination reaction mixture at superatmospheric pressure, and B) the catal;,t is deactivated by quenching the reaction mixture which, includes the brominated styrenic polymer and substantially auk of the HX coproduct, in an aqueous quenching medium. Preferably the HX dissolved in the resultant aqueous phase is separated from the organic phase containing the brominated styrenic polymer. When HX is HBr, it is preferred to recover the bromine values in the aqueous phase by (i) steam stripping the aqueous phase to remove residual organic solvent from the aqueous phase and thereby provide a hydrotropic acid product suitable fco' use or sale; (ii) converting the HBr in the aqueous phase to elemental bromine; w (iii) reacting the HBr witii an aqueous metallic base to produce a solution of a metal tnomide salt suitable for use or sale. [0021] In each of the processes of this invention, the superatmospheric pressure employed can be the autogenously pressure generated in the closed system. However, any superatmospheric pressure within the safe operating limits of the reactor and/or associated pressurized equipment can be used. [0022] HX coproduct is soluble in the halogenated solvents used in the processes of this invention. Thus, in the practice of this invention the HX coproduct is carried through the closed reaction zone while in solution, and in fact serves as an additional diluent thereby reducing the viscosity of the polymeric solution. Such a reduction in viscosity offers the opportunity of operating with less solvent at enabling use of a moderately fierier molecular weight of streams polymer with the same level of solvent. In addition, the typical need for a scrubbing system for scrubbing HX coproduct from the exit gas stream from the bromination reactor is eliminated. Instead of providing and using such a scrubbing system, all of the HX coproduct can be recovered in a single operation from the contents of an aqueous quenching system used for deactivating the catalyst. Moreover, the capital cost fact- a scrabbling system and the costs involved in the maintenance of a scrubbing system are 10023} Another feature of this invention is that although it might be expected that the bromination reaction rate would be reduced by operating in a closed bromination reaction system so that the HX coproduct remains with the reaction mixture throughout the brominatioii, it has been found that for all practical purposes the tmimination reaction rate appears to be as ,t as if the bromination was conducted at atmo,,c pressure. [0024] If necessary, the feed streams to the Nominations reaction zone can be degassed to remove dissolved atmospheric gases that may be entrained Uneven. In this way, the possibility of exceeding the pressure limitations of the bromination reaction system being employed is mimeses. [0025] Styrenic polymers wide are bcominated in accordance with the [Hasten invention are biopolymers and copolymers of vinyl aromatic mommas, that is, ouHiomers having an unsaturated moiety and an aromatic moie,. The profited vinyl aromatic monomers have the formula: HCL=CR-Ar wherein R is hydrogen or an alkyl group having from 1 to 4 carbon atoms and Ar is an aromatic radical (including various alkyl and halo-ring-substituted aromatic units) of from 6 to 10 carbon atoms. Examples of suds vinyl aromatic monomers are styrene, alpha-methylstyrane, orlfao-methylstyrene, meta-methylstyrene, para-mefliylsiyreae, para-ethylstyrene, isopropenyltoluene, isopropenylni,hdialeoe, vinyl toluene, vinyl n,hthaleoe, vinyl biphenyl, vinyl anthracite, the dimethylstyrenes, t-butyl styrene, the several chiorostyrenes (such as the mono-.and dichloro- variants), the sevord bromos,renes (such as the mono-, dibromo- and tribromo- variants). Polystyrene is the currently preferred styrenic polymer and, when the styrenic polymer being brominated is a calmer of two or more vinyl aromatic monomers, it is preferred that styrene be one of the monument and that styrene comprise at least 50 weight pewit of the ct,Ktlymeiizablc vinyl aromatic monomers. [0026] The styrenic polymers, which are brominated in accordance with the present invention, are readily prepared by bulk or mass, solution, suspension or emulsion polymerization techniques comparable to those employed in the polymerization of styrene. Polymerization can be ejected in the presence of &ee radical, atomic or anionic initiators, such as di-t-butyl peroxide, azo-bisCisobutyronitrile), di-benzo>d peroxide, t-butyl perbenzoate, dicumyl peroxide, potassium per sulfate, aluminum dichloride, boron trifluoride, etherate one or more monomers copolymerizable with styrene, is well known and it is considered unnecessary to further discuss the polymerization process. Saranac polymers produced by &ee radical polymerization with GPC molecular weights of at least 1,000, preferably at least 50,000 and most jaeferably 150,000 to 500,000, are brominated in accordance with the present invention. AnionicstyrcnicpolymefSi;i.e-,styTaiicpolymersformedusinganamonic initiator) having a GPC number average molecular wait in the range of 2000 to 30,000, preferably in the range of 20O0 to 10,000 and more preferably in the range of 3000 to 7000 constitute another preferred type of styrenic polymers for use in this invention. Although styrenic polymers outside these molecular weight ranges can be brominated in accordance with the present invention, liege is typically no economic advantage in so doing. [0027] The catalyst used in the processes of this invention can be any bromination catalyst, provided that the catalyst does not act to frustrate the efficient and safe production of a high quality brominated polystyrenic product. The fevered catalysts arc the Lewis acid catalysts which are typified by AICI3, FeClj, AlBr,, FeBrj, SbClj, ZrCl,, and the like. Fe, Al and Sb,Oj may be used to form Lewis acid catalysts by simply adding them to the reaction system. Mixtures of catalyst can also be used. Once the catalyst has been added to the reaction system, it may undei,o some reaction without significant loss of catalytic activity, e. g., AICI3 may convert to some extent to AlBtg. The more preferred catalysts are the aluminum and iron-based catalysts. Of these, more preferred are the aluminum and iron ballades, especially the bromides and chlorides, such as AICI3 and AlBrj. When intimae (Brj) is used as the brominating agent, most preferred as catalyst are the bromides such as AlBr, or FeBr, that show excellent activity for aromatic bromination and do not provide a source of MCI that could contaminate fte anhydrous HBr copout stream and reduce its wish value. Also highly preferred is a catalyst solution prepared by combining solid AICI3 (a substance »4uch is not soluble in bromine) and gaseous HBr in warm (40-50°C) lime iodine. A rated halogen exchange produces a soluble bromoalimiinum halide catalyst and HCl and the catalyst can be used with or without copiresence of HCl. An advantage of tiding a catalyst of this type is that the active brominating species (believed to be the polonium ion, Br)is preformed, and ±us the bromination of die styrenic polymer initiates van idly and with high selectivity. The direct addition of AlBr, to bromine also produces a solution of this preferred preformed brominating species. [0028] The catalyst is used in an amount vetch is sufficient to obtain the catalytic effect sought. These catalytic amounts will depend on the activity of the catalyst, but will generally fall within the range of from 02 to 20 wet percent and preferably within the rare of from 0.5 to 15 weight percent, based on the weight of the styrenic polymer being The Replacement Page 7 most active catalysts will t>e used in the tower agoutis wife ten less active catalysts witii oe used in the higher amounts. For the preferred aluminum and iron-based catalysts, it is preferred that they be used in amounts within the range of from 0.5 to 5 weight percent MCI3 and FeCI] are use I in amounts within the range of from 0.2 to 10 weight percent. When AICI3. AlBr3, or a catalyst solution made from solid AlC, and gaseous HBr in warm liquid bromine as described above is used as the catalyst, anoints within the range of from 0.5 to 3 weight platen are preformed.- [0029] The brominating agates useful in the process of this invention can be any of those which can brominates aromatic carbons in the aromatic ,ups of the polymer (hereinafter also referred to as stymieing monomer units). The art recognizes Brj and BrQ as good brominating agents, with the former being mart preferred. Bromine can be obtained commercially in the diatomic form or can be generated by the oxidation of HBr, Br: ,,, , supplied either as a liquid or a gas. The amount of brominating ,ent used in the process should provide an overall mole ratio of total brominating agent to total styrenic polymer fed, which will provide from 1 to 3 bromine substitutions per styrenic monomer unit in the polymer. Generally, it is dashed that the brominated styrenic polymer products of this invention contain at least 30 wit% bromine, based ION the tall weight of the brominated pylon. It is preferred that the brominated polymer contain above about 50 wt% brome, and most preferably above about 60 wt% bromine. Poor any particular styrenic polymer, the amount of brominating agent used in the praxes will be determined by the bromine content desired considering the highest bromine content which is obtainable with the process parameters chosen. The higher bromine contents will require the most brominating agent. It is pointed out that as tiibromitiation is approached, it becomes more difficult to substitute more bromines. Adding ever largo' amounts of a brominating agent does not always reduce this diCSculty. However-, it is helpful, in attempting to maximize the bromine content, to provide a small stoichicMiethc excess of brominating agent. Stoichiometric excesses up to about 2% are performed. The stoichiometry is easily determined as it requires one mole of Br, or BrCl per substitution sought. In practice, the practitioner will determine the bromine content sought on a weight basis and then will calculate, on an idealized basis, die amen' of moles of brominating agent needed to obtain the same. For example, if the styrenic polymer is polystyrene and the bromine content south is 68 wt%, at least 2.7 moles of bromine or BrCl per styrenic monomer unit will be required, not including any desired stoichiometric excess. For brominated polystyrene, a bromine content of from 40 to 70+ wt% bromine is desirable. This range can be diuretically obtained with a mole ratio of bromine to styrenic monomer unit of from 0,9:1 to 3.0:1. Preferred for brominated polystyrene isalwominecontentoffrom 60to 70+wt%, which can be obtained with a theoretical mole ratio of from 1.9:1 to 3.0:1 for bromine wreck The processes of this invention can, with facility, provide iq) to 67-69 wt% and ia feet even op to 70-72 wt% bromine in the ruminated styrenic polymer. In deteEEniEiing the amount of brominating agent in the process, the brominating agent in the feed mixture and any brominating agent pre-added prior to the feed of the mixture are both counted. As pointed out herein, it is not necessary to pre-old a brominating agent to the catalyst and, thus, all of the process brominating agent requirements can be supplied via tithe feed of the mixture. K, however, the practitioner chooses to pre-add a brominating agent to the reacts', it can be demise. While the caging describes the overall quantitative relationship between the brominating agent and styrene; polymer, flu quantit,ve relationship between these two reactants in the feed mixture has not been icily discussed. Generally, the mixture which is to be fed will contain from 1 to 8 moles of brominating agent p» mole of styrenic monomer units at any time during the feed period. During the feed, the quantitative relatitmship can be constant or can vary within the above-mentioned range. Qx. is within the sties of this invention to allow for some excursions outside of the range so long as such does not do significant harm to the process efficiency or to product quality.) A preferred range is from 2.S to S moles of brominating agent per mole of styrenic monomer units in the fated mixture. As can be appreciated, the use of an amount of brominating ant in the feed mixture which gives a mole ratio of brominating agent to styrenic monomer units which is less than or greater than the selected overall mole ratio of brominating agent to styrenic monomer units, will result in exhaustion of editor the brominating agent or the sardonic polymer as a mixture constituent before exhaustion of the other constituent. For example, if the practitioiier chooses to produce brominated polystyrene with a 70 wt% Women content, an overall molar ratio of bromine to stately monomer units of 3.0:1, and any excess if desired, would be suitable. If the practitioner chooses to form a feed mixture In which the molar ratio of bromine to styrenic monomer units is 1:1, it can be seen that the amount of polystyrene to be fed will be completed before obtaining the needed overall amount of bromine. In this case, the practitioner first uses the 1:1 mixture and then continues on with just a bromine feed after the polystyrene feed has been exhausted. Jf, on the other hand, the molar ratio in the feed mixture is chosen to be 5; 1, then the bromine will first become exhausted and the feed will have to be finished with the polystyrene alone. Generally, It is preferred to have the overall molar ratio and the feed mixture ratio at least somewhat similar. In all cases though, the initial feed should preferably contain at least a molar ratio of bromine to styrenic monomer units of 1:1. [0030] It is preferred that the bromine used in the process of diis invention be essentially anhydrous, ie., contain less than 100 ppm (weight basis) water and contain no more than 10 ppm organic impurities, e. g., oil, grease, carbonyl containing hydroc,iKins, iron, and the like. Available, commercial grade Iwomine may have such purity. If, however, such is not available, ttie organic impurities and water content of the bromine can be conveniently reduced by mixing together a 3 to 1 volume ratio of bromine and concentrated (94-98 percent) sulfuric acid. Atwo-phasemixisformed whichisstinedfbrl0-16hours. Aftersdrring and settling, the sulfuric acid phase, along with the iniquities and water, is separated from the bromine phase. To further mace the purity of tie bromine, tbe recovered bromine phase can be subjected to distillation. [0031] As before stated, it is preferred diat flie processes of this invention use a solvent The solvent must be capable of solubilizing the styrene polymer feed and uoderbrominated intermediates and be relatively inky to the process at reaction conditions. TAT solvent should also exhibit solubility of the underbromioaled styrenic polymers and, in preferred cases, tee final brominated product Preferred solvents are those in which the bromination catalyst is also soluble, readily dispersed or readily suspended. Halogenated solvents are [»,furred and are exemplified by carbon tetracbtoride, chloroform, tetrachloroetbane, methylene chloride, dichlorDethane,trichlOToefliyIene,trichlorobeDzene,niethyleneta>raide,l,2-dibromoetfaane, dichlorodifluoromethane, Bram chloromethane, and mixtures thereof. Especially preferred are bromochloromethane, 1,2-dichloroethane, methylene bromide, and methylene chloride. By forming a solution of solvent and styrenic polymer, the polymer becomes easy to handle and mix with bromine. The solutions of this invention preferably contain from 5 to 50wt% polymer. More highly preferred are those which contain from 5 to 30 wt% polymer. [0032] It is preferred to have the bromination catalyst, to which the bromine/styrenic polymer mixture is fed, to be in association with a liquid so that the catalyst can be in a solution, slurry, dispersion or suspension, Such will enhance mixing of tbe reactants and mass transfer qualities. It is expedient, but not necessary, to use the same liquid, i.e., solvent, that is used to form tbe styrenic polymer solution. Thus, in one preferred mode, processes of this invention will provide a mixture of halogenated solvait and catalyst in the reactor into which the styrenic polymerAtroniinating agent mixture can be fed. The mixture of halogenated solvent and catalyst is best described as a suspension. Genially, it is suitable to use from 95 to 99.9 wt% liquid and preferably from 99 to 99.8 wt%,based on the total weightofUquid and catalyst In a second more preferred mode, the catalyst is dissolved or sequined in the brominating agent and then combined with the styrenic polymer solution as it enters the reaction zone. [0033] The solvent used to dissolve the styrenic polymer and the liquid used in association with the catalyst are preferably dry, that is, they contain less than about 200 R)m (waist basis) water between them and preferably less than about 150 or 100 ppm water. The presence of water is not desired as, in significant quantities, it can deK,tivatc tbe catalyst to an undesirable extent If, for some reascm, the pracdticMier has large amounts of water in the process and dewatering is not practical, then it may be possible to overcome the situation by simply increasing the amount of catalyst used. For the process of this invention, it is not a feature to solely use water to avoid cross-linking as is taught in U.S. Pat. No. 4,00,703, but rather, this invention minimizes cross-linking by means such include its novel feed, techniques. [0034] The styrenic polymers/brominating agent mixture feed should occur expeditiously, with consideration bdng given to the alriiity of the process equipmrat to handle the heat load from the exothermic process, the pressure emigrated by the HX cofBTxluct, and other process concerns. In short, the feed can occur over the shortest time period that will be allowed by the equipment without excursion outside of critical process parameters. Generally, it is anticipated that the feed period for batch operations will be from 0.5 to 10 hours for a commercial-size plant. Shorter feed periods are expected for smaller scale batch processes. Average residence times for continuous processes of this invention (i. e., periods between the time initiation of bromination occurs in the reaction zone until deactivation of the catalyst occurs) are typically less than 20 minutes, preferably 10 minutes or less, and mote preferably 5 minutes or less. [003S] The process of this invention occurs at a temperature in the range of -20° to 20° preferably in the range of -10° to 10 °C, and more preferably in the range of -S,C to 5°C. The bromination and preferably the transfer to the aqueous queiuibing median are conducted at superatmospberic pressure. Less preferred is to reduce the pressure at commencements or durian, the transfer of reactor contents to the aqueous quencher, medium, while keeping all of the reactor contents including the HX confined, e.g., within transfer piping or conduits so that substantially all of the HX coprodiict formed in the bromination is kept confined, and transferred to and captured by the quenching medium. [0036] To carry out a typical batch-type process of files invention, a bromination catalyst, e.g., AlClj, is suspended in essentially anhydrous solvent, to give an easily storable suspension. The suspension is prepared in a glass-lid,, stirred reactor and brought to a temperature within the range of from -5° to lO,C. The mix is kept under a pressurized, inert, diy atmosphere in the reactor. A solution of a styrenic polymer and solvent, eg., bromochloromethane, is prepared and intimately mixed with a bromine stream to yield a homogenous mixture. The cool mixture is fed into the storied bromination catalyst suspension in the sealed pressurized reactor. The intimate mixing of the styrenic polymer solution and brominating agent can be accomplished in a numbs of ways. For example, the solution and a brominating agent can be fed to a mixing device, e.g., a maxis,; nozzle, at the lower end of the dip tube in the reactor v,iiich extends to a point below the suspension level. The -mixed, Replacement Page 11 device is designed to obtain the intimate mixing of the solution and thximinating agent. Also, the mixing device acts to impart mixing energy, at the point of feed, to the intimate mixture and catalyst suspension. Another technique for obtaining intimate mixing of the styrenic polymer solution and brominating agent, is to use an exterior reactor loop baling an in-fine XDixer, say an impingement mixer. Generally, the use of an exoteric»' reactor loc, includes first charging the reacts" with a bromination catalyst slurry, suspension, etc., and then withdrawing from the reactor a stream which is then fed to a nixes: external of the reactor. A mixture cuffed from at least bromine and styrenic polymer is also fed to the mixer to yield a second doctored which is formed from the two feeds to the mixer, lye second mixture is subsequently fed back to the reactor. True stream withdrawn from the reactor will initially comprise the catalyst. After the second mixture is fed to the reactor and the process runs, the withdrawn stream will begin to comprise brominated polystyrene along wittily catalyst. Use of an exterior reactor lof, in a bromination process is flirtier discussed with reference to FIG. 1 of U.S. Pat No. 5,677,390. [0037] TTie reactor is kept at a low temperMure,«.g., from -5°C, during the feed of the styrenic polymer and/or brominating feed, as the case may be. and preferably &om -2 ° to 2°C. [003S] As can be appreciated, the contents of the sealed, pressurized Bach reactor change in composition during the bromine and polystyrene/solvent solution feeds. Initially, the contents of the reactor comprise catalj,t and solvent As the process runs, the reactor contents comprise and begin to become more rich in polystyrene. During a cook period, bromination of the last styrenic polymer fed to the reactor occurs. Removal of die reactor contents can continue to occur during the cook period to aid in mixing. [0039] After the teed has been accomplished in suc, batch-type operation, the reaction mixture which includes substantially all of the HX coproduct is maintained in tbe sealed reactor under superatmospheric pressure for a coca, polio of from 5 to 30 minutes, and preferably from 5to 15 minutes. Thecookten,wratureis within the range of from -10° to lO'C and preferably within the range of from -5° to S,C. The cook period serves to complete the bromination of the last of the styrenic polymer fed to the reacted. The cook period can occur in the rectums. [0040] Bromination of styrenic polymers is a substitution reaction. Coproduct HX is also formed in this reaction, ha the practice of the present invention, the HX formed in the process is kept within the reactor and discharged along wade the reaction mixture into an aqueous quenching bath or zone. A dry, inert gas, e.g., nitrogen, can be used as a care, gas to purge the HX vapors from the react into an aqueous upending bath or into a quenching zone equipped with aqueous sprays to dissolve substantially all of the HX. The aqueous quenching bath or ths sprays in the quenching zone may contain a salt-forming base such as sodium hydroxide so that the HX entrained in the reaction mixture and the UX purged &om the vapor state are converted into a water-soluble dissolved salt sudi as an alkali metal salt, typically NaBr or NaCl. Pre,nbly, only wa, is used for the quench so diat the hydrolsBmic acid or hydrochloric acid solution that is formed is suitable fACT use or sale after removal of any small quantities of retained bromination solvent. [0041] While pure water is the preferred aqueous quenching medium, a solution OT slurry of sodium sulfite, and/or sodium hydroxide can be used to deactivate the catalyst, kill any remaining brominating agent and to adjust the reaction mixture pH. After such treatment, tiie quenched reaction mixture is settled to obtain a two-phase reaction mixture containing an organic phase, which contains, as a solute, the brominated styrcnic poplin product, and an aqueous phase whidi contains most, if not all, of the HX coronal The aqueous phase is decanted and the remaining organic phase is stripped of its solvent component. It is most convenient to accompUsh this strip by punning the (organic phase into boiling water. As the solvent is flashed off, the brominated styrenic polymer product forms a precipitate. The precipitate can be recovered by any liquid-solid separation technique, e.g., filtration, centrifugatiDQ, etc. The recovered precipitate is then dried. The aqueous phase from the quench which includes the HX coproduct is treated with live steam in either a batch or continuous operation to remove any residual bromination solvent. When bromine (Brj) is used as the brominating agent, the steam stripped aqueous solution may then be sent to a bromine recovery unit where the bromine value is recovered as elemental bromine, or if pure water was used for the quench, the solution is suitable for use or sale as hydrotropic acid. Alternatively, the stripped aqueous solution can be treated with a metallic base in order to form a solution of metallic bromide salt suit Mile for use or sale. [0042} TD carry out a process of this invention as a typical continuous process, typically two or three continuous feeds of the reactor components are carried out consonantly, the reactor or reaction zone is preferably a bluer or loop-type reactor, and contents from the reactor are typically continuously removed from the reaction zone and transferred to a quenching bath or quenching zone. Wiles two continuous feeds are used, neither feed contains all three of the components for a period of lime ,'eater than a few seconds, viz., (1) brominating agent, (2) catalyst, and (3) s,rcnic polymer (preferably dissolved in a solvent), but all three of these are fed by combining two of these three components intone of the two feeds. Him such case (3) is fed neat, the solvent should be fed either with the brominating agent and the catalyst or a third feed of solvent should be used. When three feeds are used each of (1), (2), and (3) can be fed separately but a portion of any one of them can be combined with a feed of (I). (2) anWoT (Jj provioed no teed contains all three of them tor a period of time greater than a few seconds. Permissible combination of all three feeds for a period of time not greater than a few seconds can arise, for example, vtben the three components enter a small impingement mixing chamber in aniajector and thenareinjected&om the injector. Insucfaacasetheimpii,emeDt mixing chamber an exit passage therefrom constitute part of tbe reaction zone. [0043] Multiple feeds of con,wnents (1), (2) and/or (3) can be employed, if desired. [0044] The flow diagram of Figure 1 schematically depicts one type of syst,n that can be used for conducting a continuous process pursuant to Has invention involving continuous bromination of anionic styrenic polymer {Le., styteoic polymer formed by use of an anionic polymerization initiator such as a lithium alkyl). Basically the system is composed of a loop type reactor 40, a pump 42 for circulating the reaction mixture uicluding the HX coproduct throu, reactor 40, a take-offline 44 for receivii, from reactor 40 a portion of the circulating reaction mixture includir, HX coproduct and transmitting such contents to a quench vessel (not shown), a dual injection system conqxised of injector 43 and injector 45, an indirect heat exchanger 46, and a static mixer 48. In , form deleted beat exchanger 46 is disposed upstream from injectors 43 and 45 and downstream from pump 42 so as to remove heat generated by tbe action of pump 42, as well as heat from the exothermic bromination reaction. If desired, heat exchanger 46 can be placed at any other suitable place relative to reactor 40. Also more than one such heat exchanger can be employed in association with reactor 40 to remove heat at more than one locatton around the loop. Heat exchanger 46 is provided with a flow of suitable heat absorbing liquid such as cooling water and/or ethylene glycol. [0045] As depicted, injectors 43 and 45 are in axial opposed alignment. Thoi, not shown in the line dmwing of Figure 1, tbe orifices of injectors 43 and 45 are spaced apart from each other so that the contents of lilies respective injectors are forced directly toward each other and substantially at r,t angles relative to and into the reaction mixture including the HX coproduct flowing throw reactor 40. Such an arrangement ensures very rapid contacting among the injected contents from the injectors and the reaction mixture flowing through the reactor. This in turn ensures highly rapid initiation of the bromination reaction. Take-offline 44 as depicted continuously removes from reactor 40 a portion of the circulating reaction mass. The contents of take-off line 44 are typically transported to and discharged into a vessel (not down) containing a staunching liquid which pronqrtly deactivates the catalyst. [0046] Injector 43 receives and discharges a solution of anionic strait polymer in a suitable solvent ,,4le,eas injector 45 receives and discharges a mixture of brominating agent such as bromine, and catalyst such as aluminum tribromide. If desired, three injectors (not shown) can be disposed around reactor 40, one for injecting solution of anionic styrenic polymer, another for directing Iodination agent (with or without solvent or diluent) and the Replacement Page 14 third for injecting catalyst (with or without solvent or diluent) so that contact among the three injected streams occurs rapidly thus resulting in rapid initiation of taximinalioii of styrenic polymer. In such a three-ejector system the three injectors can be in any disposition relative to each other provided the injected contents from the injectors come into contact with each other radii, preferably within a matter of a few seconds. One such three injector agreement involves disposing the injectors around reactor 40 with the respective axes of the three injectors in the same plane and radically spaced at about 120" intervals. [0047] The system of Figure 1 is typically operated at siieratmoqdieric pressure. Accordingly, the HX coproduct remains with the reaction mixture within the confines of reactor 40 and is carried out of the reactor via take-off line 44 and is discharged along with the reaction mixture directly into a vessel contained an aqueous quenching medium ,lich takes up the HX and prevents its rescue into the environment. Thus substantially all of the HX coproduct is cohered at the same time the reaction mixture is quenched, a step leading to recovery of both products in commercially desirable fumes. (00481 Product recovery and workup after quenched can be conducted by letting the quenched reaction mixture settle to obtain a two-phase reaction mixture containing an organic phase, which contemns, as a solute, the brominated anionic strayed polymer product and an aqueous phase containing the HX coproduct. The aqueous phase is decanted and the remaining organic phase is stripped of its solvent component. It is most convenient to strip by punning the organic phase into boiling water. As the solvent is flashed off, the brominated anionic styrenic polymer product forms a precipitate. The precipitate can be recovered by any liquid-solid separation technique, e.g., filtration, centrifugation, etc. The recovered precipitated washed product is then dried, typically at a temperature in the range of about 110° to about 150°C. [0049] The aqueous phase fiord the quench is treated with live steam in either a batch or continuous operation to remove any residual bromination solvent. When HX is HBr, the steam stripped aqueous solution may then be sent to a bromide recovery unit where the bromine value is recovered as elemental bromine, or if pure water was used for the quench, the solution is suitable for use or sale as acid. [OOSO] When using bromine as the brominating agent and operating the system of Figure 1 at elevated pressures in the order of 20 to 60psigandiffeferablyatabout45psig,allofthe HBr coproduct formed can be retained in the liquid reaction mixture. This has the advantage not only of eliminating a need for a separate HBr scrubber overall system, but in addition all of the bromine values in the HBr can be recovered from the aqueous quench of the reaction mixture thus simplifying and reduced the cost of the recovery of such bromine Replacement Page 15 values, runner, the rename tour nays a Net enteric on lie reason mixers mat reduces me viscosity of the reaction mixture. Such reduced viscosity enables the bromination process to operate with less solvent or enable use of a moderately higher molecular weight anionic styrenic polymer with the same level of solvent or allow use of a smaller, less costly heat exchanger. [0051] Brominated styrenic polymers produced by this invention can be used as flame retardants for various polymeric materials such as and thermosetting polymeric materials and resins. The weight average molecular weights of the polymers that can be flame retarded pursuant to tins inveodcji can vary widely, from low molecular weight policies to very high molecular weight pollsters. Methods for producing the various thermoplastic en* thermosetting polymers that can be flame retarded with the bronunated styrenic polymers of this invention are known to those of ordinary skill in the art. Other persons who may be unfamiliar with such matters, should redo* to the extensive literature that exists on such subjects. Preferably the brominated styrenic polymers of this invention are used as additive flame retardants for various thermoplastic polymers. [0052] As used anywhere herein including the claims, the terms 'continuous' and "continuously" denote that the cremation referred to ordinarily proceeds without interruption in time provided however that an interruption is permissible if of a duration that does not disrupt steady-state conditions of that operations. If the interruption is of a duration that disrupts steady-state operation, a steady stale condition of operatic should be achieved befit resuming collection of the product. [0053] Components referred to by chemical name CH* formula anywhere in the specification or claims hereof, whether referred to in the singular w plural, are identified as they exist prim-to coming into contact with another substance referred to by chemical name or chemical type {e.g., another convenient, a solvent, or etc.). It matters not what preliminary chemical changes, transformations and/or reactions, if any, take place In the resulting mixture or solution as such changes, transfmnations, and/or reactions are die natural result of bringing the specified components togedier under the conditions called for pursuant to this disclosure. Thus die components are identified as ingredients to be eight together in conoectiofl with performing a desired operation or in forming a desired composition. Also, even though the claims hereinafter may refer to substances, components and/or ingredients in the present tense C'comprises", "is", etc.), the reference is to the substance, component or ingredient as it existed at the time just before it was first contacted, bellied or mixed with one or more other substances, components and/or ingredients in accordance wide the present disclosure. The fact that a substance, component or ingredient may have lost its (signal identity through a chemical reaction cv transformation during the course of contacting, blending or mixing operations, if conducted in accordance with this disclosure and with winery skill of a chemist, is thus of no practical concern. [0054] Each and every patent or publication refined to in any cation of this specification is incorporated in too into this disclosure by difference, as if fully set forth herein. [00S5] This invention is susceptible to considerable variation in its practice. Thereafter the foregoing description is not intended to limit, and should not be construed as limiting, the invention to the particular exemplifications \|He seated hereinabove. AMENDED CLAIMS 1. A process wherein a brominated styrenic polymer having a bromine content of at least about 50 wt% is prepared by brominating styrenic polymer, wherein said process is characterized by brominating the styrenic polymer in a liquid phase reaction mixture under superatmospheric pressure in a closed reaction system so that substantially all of gaseous HX coproduct is captured as part of said reaction mixture and said gaseous HX coproduct is not released from said closed reaction system separately and apart from said reaction mixture. 2. A process as in Claim 1 wherein the bromination is conducted using bromine, Br2, as brominating agent so that said gaseous HX is HBr. 3. A process as in Claim 2 wherein said bromine content is at least about 60 wt%. 4. A process as in Claim 2 wherein said bromine content is at least about 67 wt%. 5. A process for the preparation of a brominated styrenic polymer having a bromine content of at least about 50 wt%, said process characterized in that a styrenic polymer is brominated under superatmospheric pressure in the presence of a Lewis acid bromination catalyst and in a closed reaction system in which substantially all of the HX coproduct is retained in the reaction mixture until the catalyst is quenched either in the reaction zone or externally from the reaction zone. 6. A process as in Claim 5 wherein the catalyst is quenched in an aqtreous quenching medium. 7. A process as in Claim 5 wherein the bromination is conducted in a solvent which solubilizes the styrenic polymer. 8. A process as in Claim 7 wherein said solvent comprises at least one aliphatic halocarbon and/or haiohydrocarbon solvent in which the halogen atoms are chlorine atoms, bromine atoms or both. 9. A process as in Claim 8 wherein said solvent comprises bromochloromethane. 10. A process as in any of Claims 5, 6, 7, 8, or 9 wherein the Lewis acid catalyst is an aluminum halide in which the halogen atoms are bromine, chlorine or both. 11. A process as in any of Claims 5, 6, 7, 8, or 9 wherein bromination is effected with bromine, bromine chloride, or both, as brominating agent. 12. A process as in any of Claims 5, 6, 7, 8, or 9 wherein the styrenic polymer is a styrenic polymer formed by free radical polymerization. 13. ' A process as in Claim 14 wherein the styrenic polymer is polystyrene. 14. A process as in any of Claims 5, 6, 7, 8, or 9 wherein the styrenic polymer is a styrenic polymer formed by anionic polymerization. 15. A process as in Claim 5 wherein: A) bromination is conducted with bromine, bromine chloride, or both, as brominating agent; B) bromination is conducted in a solvent which solubilizes the styrenic polymer; and C) brominated styrenic polymer and HX are separated and recovered from at least a portion of the aqueous quenching mixture formed during the quenching. 16. A process as in Claim 15 wherein the styrenic polymer is a styrenic polymer formed by free radical polymerization or by anionic polymerization. 17. A process as m any of Claims 14 or 16 wherein the styrenic polymer is polystyrene. 18. A process as in Claim 5 wherein in conducting the bromination, a mixture (i) which is substantially free of a bromination catalyst and (ii) which is formed from at least a brominating agent and a styrenic polymer is fed to a catalytic quantity of a bromination catalyst contained in said closed reaction system. 19. A process as in Claim 5 wherein a first stream comprising brominating agent, a second stream comprising styrenic polymer and a third stream comprising bromination catalyst are fed to a mixer disposed in said closed reaction system to intimately mix such streams. 20. A process as in Claim 5 wherein a first stream comprising brominating agent and catalyst, and a second sfream comprising styrenic polymer are fed into said closed reaction system.

Full Text

BACKGROUND
[00011 Commonly-owned U.S. Pat. Nos. 5,677,390. 5.686,38, 5,767,203. 5,852,131, 5.852.132, 5.916,978, 6,113,381, 6,207,765, 6.232,93, 6,232.408, 6,235.831, 6,235,844, 6.326.439, and 6,521,714 describe what is believed to be the best previously-published process technology for producing brominates styrene polymeric such as brominated polystyrene having the best pointiest of those of any previously-published brominated styrene polymer. In this connection, the terms "brominated styrene polymer" and "brominated polystyrene" as used in the specification and in the claims hereof refer to a brominated polymer produced by bromination of a pre-existing styrenic polymer such as polystyrene or a copolymer of styrene and at least one other vinyl aromatic monomer, as distinguished from an oligopoly* or polymers- produced by oligomerization or polymerization of one or more brominated styrenic monraners, the properties of the latter" oligomers or polymers typically being considerably different from brominated polystyrene in a number of respects.
[0002] The processes for preparing brominated polystyrenic polymers described in the foregoing commonly-owned patents teach the desirability of removing co product that is usually found in the head space of the brominatioa reactor by passing such bead space vapors into a scrubber, followed by viding a cook period for the bromination reaction mixture to allow bromination to continue to the desired extent, and then terminating the bromination reaction with a suitable aqueous medium. Such an operation is of economic importance since the HBr co product is of value either for use as HBr or for conversion to other commercially desirable products, such as bromine itself. In cases where bromine chloride is used as the brominating agent, HCL is formed as a coproduct,
[0003] Despite the excellence of such prior technology, new improvements, especially in the manner of conducting the processes, are always welcome. This invention is deemed to provide at least one such new improvement
BRIEF SUMMARY OF THE INVENTION
[0004] This invention enables the valuable bromine values to be recovered from the styrenic polymer- bromination reaction mixture in a highly efficient manner. The invention also reduces the capital required for conducting the overall process by eliminating equipment typically used in the plant facilities for stubbing HX gases vented from the bromination reactor in order to keep HX gas from entering the environment and for absorbing organic solvent vapors from such gas. Further, reaction mixtures framed in a brominationprocess of this invention can be more readily processed in the plant than corresponding conventional styrenic polymer bromination reaction mixtures in as much as the HX can serve as an

[0005] In accordance with one embodiment of this invention there is provided a process of preparing a abominated styrcnic polymer having a bromine content of at least about 50 wt%, and preferably at least about 60 wt%, and still more inferably at least about 67 wt% by brominating styrenic polymer, wherein said process is characterized by conducting the abomination in a liquid phase reaction mixture under superattnospheric pressure in a closed reaction system so that gaseous HX coproduct is notieleased on said closed reaction system separately and apart from said reaction mixture. Stated in other terms, the invention of this embodiment is in a process wherein a brominated styrenic polymer having a bromine content of at least about 50 wt%, and preferably at teats about 60 wt%, and still more preferably at least about 67 wt% is prepared by brominating styrenic polymer. The improvement in such process comprises ccMiducting the bromination In a liquid phase reaction mixture under super atmospheric pressure in a closed reaction system so that gaseous HX Product is not released from said closed reaction system squarely and apart from said reaction mixture. [0006] The above embodiment of this invention (in whichever of the two forms in which it is stated above) enables: A) capture within the bromination reactor of substantially all coproduct HX along with
and as a part of the reaction mixture formed in a batch bromination conducted in the
closed reaction system; or 6) removal of substantially all coproduct HX along with and as a part of the reaction
mixture existing after completion of a batch bromination of styrenic polymer
conducted in the closed reaction system; ai C) removal of substantially all coprodtK:t HX aloe, with and as a part of the reaction
mixture being formed in a continuous bromination of styrenic poem, conducted in
a closed reaction system, hi each of A), B), and C) the brominated styrenic polymer and the coproduct HX can then be separated and recoding
[0007] In accordance with another embodiment of this invention there is provided a process for the preparation of a brominated styrenic polymer having a bromine content of at least about 50 wt%, and preferably at least about 60 wt%, and still mars preferably at least about 67 wt%, said process characterized in that a styrenic polymers is brominated under superatmospheric pressure in the presence of a Lewis acid bromination catalyst and in a closed reaction system in which substantiaUy all of the HX coproduct is retained in the reaction mixture until the catalyst is quenched either in the reaction zone or externally from the reaction zone.

from the organic phase containing the brominated stymieing polymer. lo cases where HX is HBr, it is preferred to recover the bromine values in the aqueous phase by (i) steam stripping the aqueous phase to remove residual organic solvent from the aqueous phase and thereby provide a bydrobromic acid product suitable for use or sale; (ii) converting the HBr in the aqueous phase to elemental bromine; or (iii) reacting the HBr with an aqueous metallic base to nieces a solute of a metal bromide salt suitable fin- use or sale. [0009] In a batch bromination process of this invention Ate. liquid reaction mixture comprised of brominated styrenic polymer and substantially all coproduct HX can be quenched in the reaction vessel in which they are formed, or the liquid reaction mixture comprised of bromioated styrenic polymer and substantially all ccqiroduct HX can be removed from reaction vessel in which they are formed and quenched in a separate quenching zone. In this latter case the liquid reaction minutiae comprised of brominated styrenic polymer and coproduct HX is kept under pressure, preferably in confinetnent as it is transported within piping, conduits, or the like, extending from the reaction vessel into the sqiarate quenching vessel and released within dte body of a liquid quenching medium, prefen)ly an aqueous quenching medium, contained in the quenching vessel so that gaseous HX does not esc,>e into the surroundings.
[0010] By "closed reaction system" in connection with a batch process in. which the bromination and quenching are to be carried out seriatim in the same reaction vessel is meant that except fn- piping or conduits carrying the necessary components (including purging earner gases, liquid quenching medium etc.) into and out of the dominations reaction vessel, the system is closed from its surroundings. In short, the system is designed such that gaseous HX coproduct does not sack from the system, but rattier is caused to remain within the confines of the reaction vessel under sufficient pressure so that substantially all of the HX coproduct remains within and is part of the reaction mixture unto quenching whereby the HX is captured in the quenching medium concurrently with deactivation of the bromination catalyst. When HX is HBr, the bromine values are then recovered in a suitable form ami when HX is HCl, the HCl can be recovered, e.g., as hydrochloric acid, if desired. [0011] By "closed reaction system" in connection with a batch process or continuous process in which ttie bromination and quenching are to be carried out, or aie carried out, in separate vessels or zones is meant that exec>t for ping or conduits carrying the necessary components (including purging carrier gases, if used, etc.) into and out of the rumination reaction vessel or zone and into and out of the catalyst deactivaticMi vessel or zone, the system is closed &om its surroundings. In short, the system is designed such that gaseous HX coproduct does not excel from the system, but rather is caused to travel from the rumination

until quenching whereby such coproduct HX is catered in Hire quenching medium
concurrently with deactivation of the bromination catalyst Here again, when HX is HBr, the
bromine values are then recovered in a suitable fen, and when HX is HCl, the HCl can be
recovered, e.g., as hydrophilic acid, if desired.
[0012] By conducting the process in accordance witii this invention, emendated styrenic
polymer of desired bromine content and substantially all WX. ct,nnduct are catered in the
same operation (quenching), process equipment costs aye Focused, and hissing of the
reaction mixture is facilitated.
[0013] These and other embodiments and features of this invention will be still further
,)parent from the ensuing description, accompanying drawings and upended claims.
BRIEF Descriptor OF THE DRAWING
[0014] Figure I is a schematic flow diagram of a lHtHiiination|wocess of this invention that can be used for producing brominated satanic polymers.
FURTHER DETAILED DESCRIPTION
[0015] One of the features of this Invention is the fact that the process of this invention can
beapphedto any process for producing brominated stryrBnicpolymeis, including preferably,
those of the commonly-owned patents described at the outset of this document.
[0016] Thus for exanqrle, the process for brominating styrenic polymers can be a process
which comprises forming a reaction mixture by fee a mixture (t) wide is substantially
free of a bromination catalyst and (il) which is formed from at least a brominating agent and
a styrenic polymer, to a catalytic quantity of a bromination catalyst, this being exemplary of
process technology first described in U.S. Pat No. 5,677,390.
[0017] Similarly, the process for brominating styrenic polymer can be a process which
comprises feeding a first stream comprising brominating agent, a second stream comprising
styrenic polymer and a third stream comprising bromination catalyst to a mica to intimately
mix such streams, this being exenqilary of process technology first described in U.S. Pat No.
5,686,538.
[0018] Also, the process for brominating styrenic polymers can be a process which
comprises contacting styrenic polymer with brominating agent in the presence of Lewis acid
catalyst and solvent quantities of tromochlcKXimethaae, this being exenqilaiy of process
technology first described in U.S. Pat. No. 5.767,203.
[0019} In each of the above processes described in U.S. Pat No. 5.677,390; 5,586,538; or
5,767,203, such process is iroprovedpiusuaot to this ingratiation by conducting the brominates

in a closed reaction system under superatmospheric pressure which is typically up to about 60 psig, to retain substantiality all of the HX coproduct in a bromination reaction mixture, and tenanting the bromination by quenching the reaction mixture which connives brominated strum pulpier and substantially all of the coproduct HX, in an aqueous quenching medium. F,ferably the brominated strums polymer and the HX coproduct are separated and recovered &om at least a portion of the aqueous quenching mixture formed during the quenching. [0020] ID addict to the fate going, still another toxics of this invention is a process fcK-brominating styrenic polymers which process commixes concurrently feeding a first stream comprising brominating agent and a bromination catalyst, and a second stream comparing styrenic polymer to a reaction zone wherein:
A) the bromination is conducted in a closed reaction system to retain HX coproduct in a bromination reaction mixture at superatmospheric pressure, and
B) the catal;,t is deactivated by quenching the reaction mixture which, includes the brominated styrenic polymer and substantially auk of the HX coproduct, in an aqueous quenching medium.
Preferably the HX dissolved in the resultant aqueous phase is separated from the organic phase containing the brominated styrenic polymer. When HX is HBr, it is preferred to recover the bromine values in the aqueous phase by (i) steam stripping the aqueous phase to remove residual organic solvent from the aqueous phase and thereby provide a hydrotropic acid product suitable fco' use or sale; (ii) converting the HBr in the aqueous phase to elemental bromine; w (iii) reacting the HBr witii an aqueous metallic base to produce a solution of a metal tnomide salt suitable for use or sale.
[0021] In each of the processes of this invention, the superatmospheric pressure employed can be the autogenously pressure generated in the closed system. However, any superatmospheric pressure within the safe operating limits of the reactor and/or associated pressurized equipment can be used.
[0022] HX coproduct is soluble in the halogenated solvents used in the processes of this invention. Thus, in the practice of this invention the HX coproduct is carried through the closed reaction zone while in solution, and in fact serves as an additional diluent thereby reducing the viscosity of the polymeric solution. Such a reduction in viscosity offers the opportunity of operating with less solvent at enabling use of a moderately fierier molecular weight of streams polymer with the same level of solvent. In addition, the typical need for a scrubbing system for scrubbing HX coproduct from the exit gas stream from the bromination reactor is eliminated. Instead of providing and using such a scrubbing system, all of the HX coproduct can be recovered in a single operation from the contents of an aqueous quenching system used for deactivating the catalyst. Moreover, the capital cost fact-

a scrabbling system and the costs involved in the maintenance of a scrubbing system are
10023} Another feature of this invention is that although it might be expected that the bromination reaction rate would be reduced by operating in a closed bromination reaction system so that the HX coproduct remains with the reaction mixture throughout the brominatioii, it has been found that for all practical purposes the tmimination reaction rate appears to be as ,t as if the bromination was conducted at atmo,,c pressure. [0024] If necessary, the feed streams to the Nominations reaction zone can be degassed to remove dissolved atmospheric gases that may be entrained Uneven. In this way, the possibility of exceeding the pressure limitations of the bromination reaction system being employed is mimeses.
[0025] Styrenic polymers wide are bcominated in accordance with the [Hasten invention are biopolymers and copolymers of vinyl aromatic mommas, that is, ouHiomers having an unsaturated moiety and an aromatic moie,. The profited vinyl aromatic monomers have the formula:
HCL=CR-Ar
wherein R is hydrogen or an alkyl group having from 1 to 4 carbon atoms and Ar is an aromatic radical (including various alkyl and halo-ring-substituted aromatic units) of from 6 to 10 carbon atoms. Examples of suds vinyl aromatic monomers are styrene, alpha-methylstyrane, orlfao-methylstyrene, meta-methylstyrene, para-mefliylsiyreae, para-ethylstyrene, isopropenyltoluene, isopropenylni,hdialeoe, vinyl toluene, vinyl n,hthaleoe, vinyl biphenyl, vinyl anthracite, the dimethylstyrenes, t-butyl styrene, the several chiorostyrenes (such as the mono-.and dichloro- variants), the sevord bromos,renes (such as the mono-, dibromo- and tribromo- variants). Polystyrene is the currently preferred styrenic polymer and, when the styrenic polymer being brominated is a calmer of two or more vinyl aromatic monomers, it is preferred that styrene be one of the monument and that styrene comprise at least 50 weight pewit of the ct,Ktlymeiizablc vinyl aromatic monomers. [0026] The styrenic polymers, which are brominated in accordance with the present invention, are readily prepared by bulk or mass, solution, suspension or emulsion polymerization techniques comparable to those employed in the polymerization of styrene. Polymerization can be ejected in the presence of &ee radical, atomic or anionic initiators, such as di-t-butyl peroxide, azo-bisCisobutyronitrile), di-benzo>d peroxide, t-butyl perbenzoate, dicumyl peroxide, potassium per sulfate, aluminum dichloride, boron trifluoride, etherate one or more monomers copolymerizable with styrene, is well known and it is considered unnecessary to further discuss the polymerization process. Saranac polymers produced by &ee radical polymerization with GPC molecular weights of at least 1,000, preferably at least 50,000 and most jaeferably 150,000 to 500,000, are brominated in accordance with the present invention. AnionicstyrcnicpolymefSi;i.e-,styTaiicpolymersformedusinganamonic initiator) having a GPC number average molecular wait in the range of 2000 to 30,000, preferably in the range of 20O0 to 10,000 and more preferably in the range of 3000 to 7000 constitute another preferred type of styrenic polymers for use in this invention. Although styrenic polymers outside these molecular weight ranges can be brominated in accordance with the present invention, liege is typically no economic advantage in so doing. [0027] The catalyst used in the processes of this invention can be any bromination catalyst, provided that the catalyst does not act to frustrate the efficient and safe production of a high quality brominated polystyrenic product. The fevered catalysts arc the Lewis acid catalysts which are typified by AICI3, FeClj, AlBr,, FeBrj, SbClj, ZrCl,, and the like. Fe, Al and Sb,Oj may be used to form Lewis acid catalysts by simply adding them to the reaction system. Mixtures of catalyst can also be used. Once the catalyst has been added to the reaction system, it may undei,o some reaction without significant loss of catalytic activity, e. g., AICI3 may convert to some extent to AlBtg. The more preferred catalysts are the aluminum and iron-based catalysts. Of these, more preferred are the aluminum and iron ballades, especially the bromides and chlorides, such as AICI3 and AlBrj. When intimae (Brj) is used as the brominating agent, most preferred as catalyst are the bromides such as AlBr, or FeBr, that show excellent activity for aromatic bromination and do not provide a source of MCI that could contaminate fte anhydrous HBr copout stream and reduce its wish value. Also highly preferred is a catalyst solution prepared by combining solid AICI3 (a substance »4uch
is not soluble in bromine) and gaseous HBr in warm (40-50°C) lime iodine. A rated halogen exchange produces a soluble bromoalimiinum halide catalyst and HCl and the catalyst can be used with or without copiresence of HCl. An advantage of tiding a catalyst of this type is that the active brominating species (believed to be the polonium ion, Br*)is preformed, and ±us the bromination of die styrenic polymer initiates van idly and with high selectivity. The direct addition of AlBr, to bromine also produces a solution of this preferred preformed brominating species.
[0028] The catalyst is used in an amount vetch is sufficient to obtain the catalytic effect sought. These catalytic amounts will depend on the activity of the catalyst, but will generally fall within the range of from 02 to 20 wet percent and preferably within the rare of from 0.5 to 15 weight percent, based on the weight of the styrenic polymer being The
Replacement Page 7

most active catalysts will t>e used in the tower agoutis wife ten less active catalysts witii oe used in the higher amounts. For the preferred aluminum and iron-based catalysts, it is preferred that they be used in amounts within the range of from 0.5 to 5 weight percent MCI3 and FeCI] are use I in amounts within the range of from 0.2 to 10 weight percent. When AICI3. AlBr3, or a catalyst solution made from solid AlC, and gaseous HBr in warm liquid bromine as described above is used as the catalyst, anoints within the range of from 0.5 to 3 weight platen are preformed.-
[0029] The brominating agates useful in the process of this invention can be any of those which can brominates aromatic carbons in the aromatic ,ups of the polymer (hereinafter also referred to as stymieing monomer units). The art recognizes Brj and BrQ as good brominating agents, with the former being mart preferred. Bromine can be obtained commercially in the diatomic form or can be generated by the oxidation of HBr, Br: ,,, , supplied either as a liquid or a gas. The amount of brominating ,ent used in the process should provide an overall mole ratio of total brominating agent to total styrenic polymer fed, which will provide from 1 to 3 bromine substitutions per styrenic monomer unit in the polymer. Generally, it is dashed that the brominated styrenic polymer products of this invention contain at least 30 wit% bromine, based ION the tall weight of the brominated pylon. It is preferred that the brominated polymer contain above about 50 wt% brome, and most preferably above about 60 wt% bromine. Poor any particular styrenic polymer, the amount of brominating agent used in the praxes will be determined by the bromine content desired considering the highest bromine content which is obtainable with the process parameters chosen. The higher bromine contents will require the most brominating agent. It is pointed out that as tiibromitiation is approached, it becomes more difficult to substitute more bromines. Adding ever largo' amounts of a brominating agent does not always reduce this diCSculty. However-, it is helpful, in attempting to maximize the bromine content, to provide a small stoichicMiethc excess of brominating agent. Stoichiometric excesses up to about 2% are performed. The stoichiometry is easily determined as it requires one mole of Br, or BrCl per substitution sought. In practice, the practitioner will determine the bromine content sought on a weight basis and then will calculate, on an idealized basis, die amen' of moles of brominating agent needed to obtain the same. For example, if the styrenic polymer is polystyrene and the bromine content south is 68 wt%, at least 2.7 moles of bromine or BrCl per styrenic monomer unit will be required, not including any desired stoichiometric excess. For brominated polystyrene, a bromine content of from 40 to 70+ wt% bromine is desirable. This range can be diuretically obtained with a mole ratio of bromine to styrenic monomer unit of from 0,9:1 to 3.0:1. Preferred for brominated polystyrene isalwominecontentoffrom 60to 70+wt%, which can be obtained with a theoretical mole ratio of from 1.9:1 to 3.0:1 for bromine wreck The

processes of this invention can, with facility, provide iq) to 67-69 wt% and ia feet even op to 70-72 wt% bromine in the ruminated styrenic polymer. In deteEEniEiing the amount of brominating agent in the process, the brominating agent in the feed mixture and any brominating agent pre-added prior to the feed of the mixture are both counted. As pointed out herein, it is not necessary to pre-old a brominating agent to the catalyst and, thus, all of the process brominating agent requirements can be supplied via tithe feed of the mixture. K, however, the practitioner chooses to pre-add a brominating agent to the reacts', it can be demise. While the caging describes the overall quantitative relationship between the brominating agent and styrene; polymer, flu quantit,ve relationship between these two reactants in the feed mixture has not been icily discussed. Generally, the mixture which is to be fed will contain from 1 to 8 moles of brominating agent p» mole of styrenic monomer units at any time during the feed period. During the feed, the quantitative relatitmship can be constant or can vary within the above-mentioned range. Qx. is within the sties of this invention to allow for some excursions outside of the range so long as such does not do significant harm to the process efficiency or to product quality.) A preferred range is from 2.S to S moles of brominating agent per mole of styrenic monomer units in the fated mixture. As can be appreciated, the use of an amount of brominating ant in the feed mixture which gives a mole ratio of brominating agent to styrenic monomer units which is less than or greater than the selected overall mole ratio of brominating agent to styrenic monomer units, will result in exhaustion of editor the brominating agent or the sardonic polymer as a mixture constituent before exhaustion of the other constituent. For example, if the practitioiier chooses to produce brominated polystyrene with a 70 wt% Women content, an overall molar ratio of bromine to stately monomer units of 3.0:1, and any excess if desired, would be suitable. If the practitioner chooses to form a feed mixture In which the molar ratio of bromine to styrenic monomer units is 1:1, it can be seen that the amount of polystyrene to be fed will be completed before obtaining the needed overall amount of bromine. In this case, the practitioner first uses the 1:1 mixture and then continues on with just a bromine feed after the polystyrene feed has been exhausted. Jf, on the other hand, the molar ratio in the feed mixture is chosen to be 5; 1, then the bromine will first become exhausted and the feed will have to be finished with the polystyrene alone. Generally, It is preferred to have the overall molar ratio and the feed mixture ratio at least somewhat similar. In all cases though, the initial feed should preferably contain at least a molar ratio of bromine to styrenic monomer units of 1:1. [0030] It is preferred that the bromine used in the process of diis invention be essentially anhydrous, ie., contain less than 100 ppm (weight basis) water and contain no more than 10 ppm organic impurities, e. g., oil, grease, carbonyl containing hydroc,iKins, iron, and the like. Available, commercial grade Iwomine may have such purity. If, however, such is not

available, ttie organic impurities and water content of the bromine can be conveniently reduced by mixing together a 3 to 1 volume ratio of bromine and concentrated (94-98 percent) sulfuric acid. Atwo-phasemixisformed whichisstinedfbrl0-16hours. Aftersdrring and settling, the sulfuric acid phase, along with the iniquities and water, is separated from the bromine phase. To further mace the purity of tie bromine, tbe recovered bromine phase can be subjected to distillation.
[0031] As before stated, it is preferred diat flie processes of this invention use a solvent The solvent must be capable of solubilizing the styrene polymer feed and uoderbrominated intermediates and be relatively inky to the process at reaction conditions. TAT solvent should also exhibit solubility of the underbromioaled styrenic polymers and, in preferred cases, tee final brominated product Preferred solvents are those in which the bromination catalyst is also soluble, readily dispersed or readily suspended. Halogenated solvents are [»,furred and are exemplified by carbon tetracbtoride, chloroform, tetrachloroetbane, methylene chloride, dichlorDethane,trichlOToefliyIene,trichlorobeDzene,niethyleneta>raide,l,2-dibromoetfaane, dichlorodifluoromethane, Bram chloromethane, and mixtures thereof. Especially preferred are bromochloromethane, 1,2-dichloroethane, methylene bromide, and methylene chloride. By forming a solution of solvent and styrenic polymer, the polymer becomes easy to handle and mix with bromine. The solutions of this invention preferably contain from 5 to 50wt% polymer. More highly preferred are those which contain from 5 to 30 wt% polymer. [0032] It is preferred to have the bromination catalyst, to which the bromine/styrenic polymer mixture is fed, to be in association with a liquid so that the catalyst can be in a solution, slurry, dispersion or suspension, Such will enhance mixing of tbe reactants and mass transfer qualities. It is expedient, but not necessary, to use the same liquid, i.e., solvent, that is used to form tbe styrenic polymer solution. Thus, in one preferred mode, processes of this invention will provide a mixture of halogenated solvait and catalyst in the reactor into which the styrenic polymerAtroniinating agent mixture can be fed. The mixture of halogenated solvent and catalyst is best described as a suspension. Genially, it is suitable to use from 95 to 99.9 wt% liquid and preferably from 99 to 99.8 wt%,based on the total weightofUquid and catalyst In a second more preferred mode, the catalyst is dissolved or sequined in the brominating agent and then combined with the styrenic polymer solution as it enters the reaction zone.
[0033] The solvent used to dissolve the styrenic polymer and the liquid used in association with the catalyst are preferably dry, that is, they contain less than about 200 R)m (waist basis) water between them and preferably less than about 150 or 100 ppm water. The presence of water is not desired as, in significant quantities, it can deK,tivatc tbe catalyst to an undesirable extent If, for some reascm, the pracdticMier has large amounts of water in the

process and dewatering is not practical, then it may be possible to overcome the situation by simply increasing the amount of catalyst used. For the process of this invention, it is not a feature to solely use water to avoid cross-linking as is taught in U.S. Pat. No. 4,00,703, but rather, this invention minimizes cross-linking by means such include its novel feed, techniques.
[0034] The styrenic polymers/brominating agent mixture feed should occur expeditiously, with consideration bdng given to the alriiity of the process equipmrat to handle the heat load from the exothermic process, the pressure emigrated by the HX cofBTxluct, and other process concerns. In short, the feed can occur over the shortest time period that will be allowed by the equipment without excursion outside of critical process parameters. Generally, it is anticipated that the feed period for batch operations will be from 0.5 to 10 hours for a commercial-size plant. Shorter feed periods are expected for smaller scale batch processes. Average residence times for continuous processes of this invention (i. e., periods between the time initiation of bromination occurs in the reaction zone until deactivation of the catalyst occurs) are typically less than 20 minutes, preferably 10 minutes or less, and mote preferably 5 minutes or less. [003S] The process of this invention occurs at a temperature in the range of -20° to 20°
preferably in the range of -10° to 10 °C, and more preferably in the range of -S,C to 5°C. The bromination and preferably the transfer to the aqueous queiuibing median are conducted at superatmospberic pressure. Less preferred is to reduce the pressure at commencements or durian, the transfer of reactor contents to the aqueous quencher, medium, while keeping all of the reactor contents including the HX confined, e.g., within transfer piping or conduits so that substantially all of the HX coprodiict formed in the bromination is kept confined, and transferred to and captured by the quenching medium.
[0036] To carry out a typical batch-type process of files invention, a bromination catalyst, e.g., AlClj, is suspended in essentially anhydrous solvent, to give an easily storable suspension. The suspension is prepared in a glass-lid,, stirred reactor and brought to a temperature within the range of from -5° to lO,C. The mix is kept under a pressurized, inert, diy atmosphere in the reactor. A solution of a styrenic polymer and solvent, eg., bromochloromethane, is prepared and intimately mixed with a bromine stream to yield a homogenous mixture. The cool mixture is fed into the storied bromination catalyst suspension in the sealed pressurized reactor. The intimate mixing of the styrenic polymer solution and brominating agent can be accomplished in a numbs of ways. For example, the solution and a brominating agent can be fed to a mixing device, e.g., a maxis,; nozzle, at the lower end of the dip tube in the reactor v,iiich extends to a point below the suspension level. The -mixed,
Replacement Page 11

device is designed to obtain the intimate mixing of the solution and thximinating agent. Also, the mixing device acts to impart mixing energy, at the point of feed, to the intimate mixture and catalyst suspension. Another technique for obtaining intimate mixing of the styrenic polymer solution and brominating agent, is to use an exterior reactor loop baling an in-fine XDixer, say an impingement mixer. Generally, the use of an exoteric»' reactor loc, includes first charging the reacts" with a bromination catalyst slurry, suspension, etc., and then withdrawing from the reactor a stream which is then fed to a nixes: external of the reactor. A mixture cuffed from at least bromine and styrenic polymer is also fed to the mixer to yield a second doctored which is formed from the two feeds to the mixer, lye second mixture is subsequently fed back to the reactor. True stream withdrawn from the reactor will initially comprise the catalyst. After the second mixture is fed to the reactor and the process runs, the withdrawn stream will begin to comprise brominated polystyrene along wittily catalyst. Use of an exterior reactor lof, in a bromination process is flirtier discussed with reference to FIG. 1 of U.S. Pat No. 5,677,390.
[0037] TTie reactor is kept at a low temperMure,«.g., from -5°C, during the feed of the styrenic polymer and/or brominating feed, as the case may be. and preferably &om -2 ° to 2°C.
[003S] As can be appreciated, the contents of the sealed, pressurized Bach reactor change in composition during the bromine and polystyrene/solvent solution feeds. Initially, the contents of the reactor comprise catalj,t and solvent As the process runs, the reactor contents comprise and begin to become more rich in polystyrene. During a cook period, bromination of the last styrenic polymer fed to the reactor occurs. Removal of die reactor contents can continue to occur during the cook period to aid in mixing. [0039] After the teed has been accomplished in suc, batch-type operation, the reaction mixture which includes substantially all of the HX coproduct is maintained in tbe sealed reactor under superatmospheric pressure for a coca, polio of from 5 to 30 minutes, and preferably from 5to 15 minutes. Thecookten,wratureis within the range of from -10° to lO'C and preferably within the range of from -5° to S,C. The cook period serves to complete the bromination of the last of the styrenic polymer fed to the reacted. The cook period can occur in the rectums.
[0040] Bromination of styrenic polymers is a substitution reaction. Coproduct HX is also formed in this reaction, ha the practice of the present invention, the HX formed in the process is kept within the reactor and discharged along wade the reaction mixture into an aqueous quenching bath or zone. A dry, inert gas, e.g., nitrogen, can be used as a care, gas to purge the HX vapors from the react into an aqueous upending bath or into a quenching zone

equipped with aqueous sprays to dissolve substantially all of the HX. The aqueous quenching bath or ths sprays in the quenching zone may contain a salt-forming base such as sodium hydroxide so that the HX entrained in the reaction mixture and the UX purged &om the vapor state are converted into a water-soluble dissolved salt sudi as an alkali metal salt, typically NaBr or NaCl. Pre,nbly, only wa, is used for the quench so diat the hydrolsBmic acid or hydrochloric acid solution that is formed is suitable fACT* use or sale after removal of any small quantities of retained bromination solvent.
[0041] While pure water is the preferred aqueous quenching medium, a solution OT slurry of sodium sulfite, and/or sodium hydroxide can be used to deactivate the catalyst, kill any remaining brominating agent and to adjust the reaction mixture pH. After such treatment, tiie quenched reaction mixture is settled to obtain a two-phase reaction mixture containing an organic phase, which contains, as a solute, the brominated styrcnic poplin product, and an aqueous phase whidi contains most, if not all, of the HX coronal The aqueous phase is decanted and the remaining organic phase is stripped of its solvent component. It is most convenient to accompUsh this strip by punning the (organic phase into boiling water. As the solvent is flashed off, the brominated styrenic polymer product forms a precipitate. The precipitate can be recovered by any liquid-solid separation technique, e.g., filtration, centrifugatiDQ, etc. The recovered precipitate is then dried. The aqueous phase from the quench which includes the HX coproduct is treated with live steam in either a batch or continuous operation to remove any residual bromination solvent. When bromine (Brj) is used as the brominating agent, the steam stripped aqueous solution may then be sent to a bromine recovery unit where the bromine value is recovered as elemental bromine, or if pure water was used for the quench, the solution is suitable for use or sale as hydrotropic acid. Alternatively, the stripped aqueous solution can be treated with a metallic base in order to form a solution of metallic bromide salt suit Mile for use or sale.
[0042} TD carry out a process of this invention as a typical continuous process, typically two or three continuous feeds of the reactor components are carried out consonantly, the reactor or reaction zone is preferably a bluer or loop-type reactor, and contents from the reactor are typically continuously removed from the reaction zone and transferred to a quenching bath or quenching zone. Wiles two continuous feeds are used, neither feed contains all three of the components for a period of lime ,'eater than a few seconds, viz., (1) brominating agent,
(2) catalyst, and (3) s,rcnic polymer (preferably dissolved in a solvent), but all three of these are fed by combining two of these three components intone of the two feeds. Him such case
(3) is fed neat, the solvent should be fed either with the brominating agent and the catalyst or a third feed of solvent should be used. When three feeds are used each of (1), (2), and (3) can be fed separately but a portion of any one of them can be combined with a feed of (I). (2)

anWoT (Jj provioed no teed contains all three of them tor a period of time greater than a few seconds. Permissible combination of all three feeds for a period of time not greater than a few seconds can arise, for example, vtben the three components enter a small impingement mixing chamber in aniajector and thenareinjected&om the injector. Insucfaacasetheimpii,emeDt mixing chamber an exit passage therefrom constitute part of tbe reaction zone. [0043] Multiple feeds of con,wnents (1), (2) and/or (3) can be employed, if desired. [0044] The flow diagram of Figure 1 schematically depicts one type of syst,n that can be used for conducting a continuous process pursuant to Has invention involving continuous bromination of anionic styrenic polymer {Le., styteoic polymer formed by use of an anionic polymerization initiator such as a lithium alkyl). Basically the system is composed of a loop type reactor 40, a pump 42 for circulating the reaction mixture uicluding the HX coproduct throu, reactor 40, a take-offline 44 for receivii, from reactor 40 a portion of the circulating reaction mixture includir, HX coproduct and transmitting such contents to a quench vessel (not shown), a dual injection system conqxised of injector 43 and injector 45, an indirect heat exchanger 46, and a static mixer 48. In , form deleted beat exchanger 46 is disposed upstream from injectors 43 and 45 and downstream from pump 42 so as to remove heat generated by tbe action of pump 42, as well as heat from the exothermic bromination reaction. If desired, heat exchanger 46 can be placed at any other suitable place relative to reactor 40. Also more than one such heat exchanger can be employed in association with reactor 40 to remove heat at more than one locatton around the loop. Heat exchanger 46 is provided with a flow of suitable heat absorbing liquid such as cooling water and/or ethylene glycol. [0045] As depicted, injectors 43 and 45 are in axial opposed alignment. Thoi, not shown in the line dmwing of Figure 1, tbe orifices of injectors 43 and 45 are spaced apart from each other so that the contents of lilies respective injectors are forced directly toward each other and substantially at r,t angles relative to and into the reaction mixture including the HX coproduct flowing throw reactor 40. Such an arrangement ensures very rapid contacting among the injected contents from the injectors and the reaction mixture flowing through the reactor. This in turn ensures highly rapid initiation of the bromination reaction. Take-offline 44 as depicted continuously removes from reactor 40 a portion of the circulating reaction mass. The contents of take-off line 44 are typically transported to and discharged into a vessel (not down) containing a staunching liquid which pronqrtly deactivates the catalyst. [0046] Injector 43 receives and discharges a solution of anionic strait polymer in a suitable solvent ,,4le,eas injector 45 receives and discharges a mixture of brominating agent such as bromine, and catalyst such as aluminum tribromide. If desired, three injectors (not shown) can be disposed around reactor 40, one for injecting solution of anionic styrenic polymer, another for directing Iodination agent (with or without solvent or diluent) and the
Replacement Page 14

third for injecting catalyst (with or without solvent or diluent) so that contact among the three injected streams occurs rapidly thus resulting in rapid initiation of taximinalioii of styrenic polymer. In such a three-ejector system the three injectors can be in any disposition relative to each other provided the injected contents from the injectors come into contact with each other radii, preferably within a matter of a few seconds. One such three injector agreement involves disposing the injectors around reactor 40 with the respective axes of the three injectors in the same plane and radically spaced at about 120" intervals. [0047] The system of Figure 1 is typically operated at siieratmoqdieric pressure. Accordingly, the HX coproduct remains with the reaction mixture within the confines of reactor 40 and is carried out of the reactor via take-off line 44 and is discharged along with the reaction mixture directly into a vessel contained an aqueous quenching medium ,lich takes up the HX and prevents its rescue into the environment. Thus substantially all of the HX coproduct is cohered at the same time the reaction mixture is quenched, a step leading to recovery of both products in commercially desirable fumes.
(00481 Product recovery and workup after quenched can be conducted by letting the quenched reaction mixture settle to obtain a two-phase reaction mixture containing an organic phase, which contemns, as a solute, the brominated anionic strayed polymer product and an aqueous phase containing the HX coproduct. The aqueous phase is decanted and the remaining organic phase is stripped of its solvent component. It is most convenient to strip by punning the organic phase into boiling water. As the solvent is flashed off, the brominated anionic styrenic polymer product forms a precipitate. The precipitate can be recovered by any liquid-solid separation technique, e.g., filtration, centrifugation, etc. The recovered precipitated washed product is then dried, typically at a temperature in the range of about 110° to about 150°C.
[0049] The aqueous phase fiord the quench is treated with live steam in either a batch or continuous operation to remove any residual bromination solvent. When HX is HBr, the steam stripped aqueous solution may then be sent to a bromide recovery unit where the bromine value is recovered as elemental bromine, or if pure water was used for the quench, the solution is suitable for use or sale as acid.
[OOSO] When using bromine as the brominating agent and operating the system of Figure 1 at elevated pressures in the order of 20 to 60psigandiffeferablyatabout45psig,allofthe HBr coproduct formed can be retained in the liquid reaction mixture. This has the advantage not only of eliminating a need for a separate HBr scrubber overall system, but in addition all of the bromine values in the HBr can be recovered from the aqueous quench of the reaction mixture thus simplifying and reduced the cost of the recovery of such bromine
Replacement Page 15

values, runner, the rename tour nays a Net enteric on lie reason mixers mat reduces me viscosity of the reaction mixture. Such reduced viscosity enables the bromination process to operate with less solvent or enable use of a moderately higher molecular weight anionic styrenic polymer with the same level of solvent or allow use of a smaller, less costly heat exchanger.
[0051] Brominated styrenic polymers produced by this invention can be used as flame retardants for various polymeric materials such as and thermosetting polymeric materials and resins. The weight average molecular weights of the polymers that can be flame retarded pursuant to tins inveodcji can vary widely, from low molecular weight policies to very high molecular weight pollsters. Methods for producing the various thermoplastic en* thermosetting polymers that can be flame retarded with the bronunated styrenic polymers of this invention are known to those of ordinary skill in the art. Other persons who may be unfamiliar with such matters, should redo* to the extensive literature that exists on such subjects. Preferably the brominated styrenic polymers of this invention are used as additive flame retardants for various thermoplastic polymers.
[0052] As used anywhere herein including the claims, the terms 'continuous' and "continuously" denote that the cremation referred to ordinarily proceeds without interruption in time provided however that an interruption is permissible if of a duration that does not disrupt steady-state conditions of that operations. If the interruption is of a duration that disrupts steady-state operation, a steady stale condition of operatic should be achieved befit resuming collection of the product.
[0053] Components referred to by chemical name CH* formula anywhere in the specification or claims hereof, whether referred to in the singular w plural, are identified as they exist prim-to coming into contact with another substance referred to by chemical name or chemical type {e.g., another convenient, a solvent, or etc.). It matters not what preliminary chemical changes, transformations and/or reactions, if any, take place In the resulting mixture or solution as such changes, transfmnations, and/or reactions are die natural result of bringing the specified components togedier under the conditions called for pursuant to this disclosure. Thus die components are identified as ingredients to be eight together in conoectiofl with performing a desired operation or in forming a desired composition. Also, even though the claims hereinafter may refer to substances, components and/or ingredients in the present tense C'comprises", "is", etc.), the reference is to the substance, component or ingredient as it existed at the time just before it was first contacted, bellied or mixed with one or more other substances, components and/or ingredients in accordance wide the present disclosure. The fact that a substance, component or ingredient may have lost its (signal identity through a chemical reaction cv transformation during the course of contacting, blending or mixing

operations, if conducted in accordance with this disclosure and with winery skill of a
chemist, is thus of no practical concern.
[0054] Each and every patent or publication refined to in any cation of this specification
is incorporated in too into this disclosure by difference, as if fully set forth herein.
[00S5] This invention is susceptible to considerable variation in its practice. Thereafter the
foregoing description is not intended to limit, and should not be construed as limiting, the
invention to the particular exemplifications |He seated hereinabove.

AMENDED CLAIMS
1. A process wherein a brominated styrenic polymer having a bromine content of at least about 50 wt% is prepared by brominating styrenic polymer, wherein said process is characterized by brominating the styrenic polymer in a liquid phase reaction mixture under superatmospheric pressure in a closed reaction system so that substantially all of gaseous HX coproduct is captured as part of said reaction mixture and said gaseous HX coproduct is not released from said closed reaction system separately and apart from said reaction mixture.
2. A process as in Claim 1 wherein the bromination is conducted using bromine, Br2, as brominating agent so that said gaseous HX is HBr.
3. A process as in Claim 2 wherein said bromine content is at least about 60 wt%.
4. A process as in Claim 2 wherein said bromine content is at least about 67 wt%.
5. A process for the preparation of a brominated styrenic polymer having a bromine content of at least about 50 wt%, said process characterized in that a styrenic polymer is brominated under superatmospheric pressure in the presence of a Lewis acid bromination catalyst and in a closed reaction system in which substantially all of the HX coproduct is retained in the reaction mixture until the catalyst is quenched either in the reaction zone or externally from the reaction zone.
6. A process as in Claim 5 wherein the catalyst is quenched in an aqtreous quenching medium.
7. A process as in Claim 5 wherein the bromination is conducted in a solvent which solubilizes the styrenic polymer.
8. A process as in Claim 7 wherein said solvent comprises at least one aliphatic halocarbon and/or haiohydrocarbon solvent in which the halogen atoms are chlorine atoms, bromine atoms or both.
9. A process as in Claim 8 wherein said solvent comprises bromochloromethane.
10. A process as in any of Claims 5, 6, 7, 8, or 9 wherein the Lewis acid catalyst is an aluminum halide in which the halogen atoms are bromine, chlorine or both.
11. A process as in any of Claims 5, 6, 7, 8, or 9 wherein bromination is effected with bromine, bromine chloride, or both, as brominating agent.

12. A process as in any of Claims 5, 6, 7, 8, or 9 wherein the styrenic polymer is a
styrenic polymer formed by free radical polymerization.
13. ' A process as in Claim 14 wherein the styrenic polymer is polystyrene.
14. A process as in any of Claims 5, 6, 7, 8, or 9 wherein the styrenic polymer is a
styrenic polymer formed by anionic polymerization.
15. A process as in Claim 5 wherein:
A) bromination is conducted with bromine, bromine chloride, or both, as brominating agent;
B) bromination is conducted in a solvent which solubilizes the styrenic polymer; and
C) brominated styrenic polymer and HX are separated and recovered from at least a portion
of the aqueous quenching mixture formed during the quenching.
16. A process as in Claim 15 wherein the styrenic polymer is a styrenic polymer
formed by free radical polymerization or by anionic polymerization.
17. A process as m any of Claims 14 or 16 wherein the styrenic polymer is
polystyrene.
18. A process as in Claim 5 wherein in conducting the bromination, a mixture (i)
which is substantially free of a bromination catalyst and (ii) which is formed from at least a
brominating agent and a styrenic polymer is fed to a catalytic quantity of a bromination catalyst
contained in said closed reaction system.
19. A process as in Claim 5 wherein a first stream comprising brominating agent, a
second stream comprising styrenic polymer and a third stream comprising bromination catalyst
are fed to a mixer disposed in said closed reaction system to intimately mix such streams.
20. A process as in Claim 5 wherein a first stream comprising brominating agent and
catalyst, and a second sfream comprising styrenic polymer are fed into said closed reaction
system.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=gkrYDq4liiEfuF/fDS+MhA==&loc=egcICQiyoj82NGgGrC5ChA==

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Patent Number

268339

Indian Patent Application Number

3139/CHENP/2008

PG Journal Number

35/2015

Publication Date

28-Aug-2015

Grant Date

26-Aug-2015

Date of Filing

23-Jun-2008

Name of Patentee

ALBEMARLE CORPORATION

Applicant Address

451 FLORIDA STREET, BATON ROUGE, LA 70801-1765

Inventors:

#	Inventor's Name	Inventor's Address
1	KOLICH, CHARLES, H.	963 FULWAR SKIPWITH ROAD, BATON ROUGE, LA 70810
2	BALHOFF, JOHN, F.,	2816 DAKIN AVENUE, BATON ROUGE, LA 70820
3	BERDON, MARTIN, B.	17561 BROOKFIELD AVENUE, BATON ROUGE, LA 70817
4	LIN, RONNY, W.,	2823 GALAHAD DRIVE, BATON ROUGE, LA 70816

PCT International Classification Number

C08F8/20

PCT International Application Number

PCT/US06/62299

PCT International Filing date

2006-12-19

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	60/753,062	2005-12-21	U.S.A.