Method for producing a polymer electrolyte

Abstract: A polymer electrolyte which contains an inorganic pigment, having a sulfonated polystyrene resin as a principal ingredient, and is soluble to water.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention: This invention relates to a method for producing a polymer electrolyte. 2. Description of Prior Art: Polystyrene resin is transparent, and is excellent in electric properties, rigidity, and resistance to water. In addition, it requires less cost for production. Accordingly, the polystyrene resin is used alone, or as copolymers and alloys in combination with other resins to serve as a material of buffering members (foamed styrol), packing materials, or cabinets and parts of electric appliances and automobiles, and has been used as widely as polyolefin resins represented by polyethylene. The polystyrene resin is used not only as a structural element as described above, but can be used, for example, as an agglutinating agent after it has been converted to a polymer electrolyte. Recently, a world-wide attention has been directed to protection of natural environment, and preservation of clean water resources is thought as a key to the problem. Under these circumstances, legal regulations controlling liquid waste discharged from plants and general households as are specified in the sewage control law become more strict. To control waste water, recourse has been made to purification by a variety of polymer aggregating agents. The polymer aggregating agent widely used includes non-ionic/anion types for industrial water wastes, and cationic types for general sewage and human excretions. Although these aggregating agents are chosen as appropriate according to a given application, they are required of, in common, having properties to clean liquid waste, concentrate it and remove water content from it. Of these properties, the cleaning activity of a suspension is most important, and demand for that activity has been increasingly strengthened from the viewpoint to protect environment from pollution because the filtrate produced after sewage has been treated with an aggregating agents discharged into rivers, lakes and the sea in local areas. Under these circumstances, trials have been made in which two kinds of polymer aggregating agents are combined or a polymer aggregating agent is combined with a metal compound, to give a product capable of reducing the chemical oxygen demand (COD) and turbidity of a filtrate. However, conventional technologies have not produced yet any aggregating agents that can satisfactorily clean a suspension, and improvement of conventional technologies involved in water treatment has been desired. OBJECTS AND SUMMARY OF THE INVENTION This invention intends to provide a method for producing a polymer electrolyte which dissolves sufficiently readily into water. The polymer electrolyte in the method of this invention contains a sulfonated polystyrene resin as a principal ingredient, in addition to an inorganic pigment, and is water soluble. The presence of the inorganic pigment, during sulfonation of the polystyrene resin, inhibits cross-linking reactions, thereby suppressing gelation of the product. Through this maneuver, unnecessary polymers are not generated in water , and water-soluble polymer electrolytes can be stably obtained. A polymer aggregating agent contains a polymer compound as a principal ingredient, and, in addition, carbon black. A liquid waste disposal consists of adding the polymer aggregating agent to liquid waste, aggregating suspended matters, and removing the aggregated matters by filtration. Use of a polymer aggregating agent supplemented with carbon black or use of a polymer aggregating agent together with carbon black will enhance the purification activity of that agent towards a suspension. A polymer aggregating agent contains a sulfonated styrene polymer as a principal ingredient and has a molecular weight of 150,000-600,000. Use of a styrene polymer having a comparatively large molecular weight will enhance the purification activity of the product towards a suspension, and reduce the water content of resulting cakes. The polymer electrolyte in the method of this invention contains, in addition to an inorganic pigment, a sulfonated polystyrene resin as a principal ingredient, and is water soluble. The inorganic pigment may include either carbon black or titanium oxide, or both, and the content may be 1 × 10 -5 - 15 wt%, or more preferably 5 × 10 -4 - 5 wt%. Carbon black and titanium oxide can be chosen from any general products that are used as a colorant of resins, a reinforcing agent or an agent conferring electroconductivity. For example, carbon black can be chosen from any products that have been produced by a channel method, furnace method or thermal method. A carbon black product which has been produced by any one of those methods may be used, or carbon black products which have been produced by different methods may be used in combination. It preferably has an average particle size of 5-500nm, or more preferably 10-50nm. Titanium oxide may have a rutile, anatase, or ultra-fine structure. Titanium oxide with any one structure may be used or titanium oxide crystals with different structures may be used in combination. It preferably has an average particle size of 0.01-50nm, or more preferably 0.05-10nm. The polystyrene resin may consist of a single polystyrene compound, or a copolymer of a styrene with other monomers. When the polystyrene resin consists of a copolymer, the styrene unit preferably occupies 30 mol% or more. The polystyrene resin may be alloys or blends which result after the styrene unit has been combined with other polymers. In this case, the polystyrene resin preferably occupies 20 wt% or more of the total product. The styrene copolymer may include styrene-butadiene, styrene-acrylonitrile, styrene-butadiene-acrylonitrile, styrene-(metha)acrylate (aliphatic hydrocarbons with 1-4 carbons), styrene-acrylonitrile-(metha)-acrylate esters (aliphatic hydrocarbons with 1-4 carbons), styrene-butadiene-(metha) acrylate ester (aliphatic hydrocarbons with 1-4 carbons), styrene-anhydrous maleate, and styrene-an hydrous itaconic acid. Of them preferred are styrene-butadiene, styrene-acrylonitrile, styrene-butadiene-acrylonitrile, styrene-acrylonitrile-(metha)acrylate esters (aliphatic hydrocarbons with 1-4 carbons), and styrene-butadiene -(metha)-acrylate esters (aliphatic hydrocarbons with 1-4 carbons), and styrene-a nhydrous maleate. Of them, styrene-butadiene, styrene-acrylonitrile, styrene- butadiene-acrylonitrile, and styrene-anhydrous maleate are particularly preferred. These styrene copolymers may be used alone or in combination with polystyrene or other styrene copolymers. The polystyrene resin preferably has a molecular weight of 5,000-10,000,000, more preferably 50,000-100,000, or further more preferably 100,000-500,000. When the polystyrene resin is made into an alloy, or used as a blend, other polymers to be combined with the alloy or blend may include polyphenylene ether, polycarbonate, polyphenylene sulfide, polyamide (nylon), polyethyleneterephthalate, and polybutyleneterephthalate. Of them particularly preferred are polyphenylene ether and polycarbonate. Any one of them may be used alone, or two or more of them may be used in combination. The above-described polymer electrolytes can be used as an aggregating agent for the treatment of liquid waste, dispersant for cement production, thinning agent for paper production, electroconductive agent for copying machines, and anti-static electricity agent. They are particularly well suited for the treatment of liquid waste, dispersal of cement particles, thinning of paper fibers and electroconduction of the toner particles of copying machines. The manufacture of the polymer electrolyte according to this invention is to produce the polymer electrolytes as described above, and consists of converting a polystyrene resin into a water-soluble polymer electrolyte by sulfonating the resin in the presence of an inorganic pigment. The polystyrene resin may be chosen from among those described above, and can be also adopted from a new material (virgin material) specially prepared for the production of the polymer electrolyte according to this invention, or from wastes (waste materials) from plants, shops and households. Or, a combination of virgin and waste materials may be used. As seen from above, this invention can recycle polystyrene resins which have been mass-produced as a general-purposeres in and wasted, and hence is very beneficial for the protection of global environment from artificial pollutants. From this point of view, it is desirable for this invention to adopt waste materials as a source of polystyrene resins rather than virgin materials. As a source of polystyrene resins, it is desirable to resort to wastes from plants and shops than those from general households, because the wastes from plants and shops may be more or less homogenous in composition. Prior to sulfonation, the polystyrene resin is dissolved in an organic solvent, or dispersed there, to which is added a sulfonating agent. When a polystyrene resin is used in combination with another polymer, the two compounds are dissolved or dispersed in an organic solvent. The organic solvent preferably includes halogenated aliphatic hydrocarbons with 1-2 carbons, particularly 1,2-dichloromethane, chloroform, dichloromethane, and 1,1-dichloroethane. To this organic solvent is preferably added the polystyrene resin at 0.5-50 wt%, or more preferably 2-20 wt%, though the addition is more or less dependent on the molecular weight of the resin. Saturated or unsaturated cyclic hydrocarbon compounds may be used. The saturated cyclic hydrocarbon compound may include cyclopenthane, methylcyclopenthane, cyclohexane, methylcyclohexane, ethylcyclohexane, p-menthane, bicyclohexyl, dekalin, sabinane, etc. The unsaturated cyclic hydrocarbon compound may include cyclohexane, monocyclic monoterpene (limonene, sylvestrene, and terpinene), dicyclic monoterpene (carene, pinene, sabinene, and camphene), and terpinorene. Of these cyclic hydrocarbons, saturated cyclic hydrocarbons are more preferred. The solvent which can coexist with such a cyclic hydrocarbon may include, in addition to above-described aliphatic hydrocarbons, paraffin hydrocarbons with 1-7 carbons, acetonitrile, carbondisulfide, tetrahydrofuran, tetrahydrobilan, acetone, methylethylketone, thiophene, etc. Of them particularly preferred are paraffin hydrocarbons, acetonitrile, tetrahydrofuran, and acetone. The sulfonating agent may include anhydrous sulfuric acid, fuming sulfuric acid, chlorosulfonic acid, and concentrated sulfuric acid. The addition of the sulfonating agent is preferably set to 0.5-2.0 mol for every benzenering in the branched chain of the polystyrene resin, or preferably 0.7-1.5 mol. When a polyphenylene ether or polycarbonate resin is used in combination, benzene rings in the backbone of this resin and benzene rings in the above-described polystyrene resin should be taken into account, to determine the amount of the sulfonating agent to be added. If addition of the sulfonating agent is too little, the product would be insufficiently sulfonated and its solubility to water would be also insufficient. On the contrary, if addition of the sulfonating agent is too much, cross-linking reactions within and among molecules would be enhanced, which would lead to increased production of by-products, and solubility of the product to water would be also impaired. The sulfonating agent may be used in combination with a Lewis base. In this case, the Lewis base may include alkyl phosphates such as triethylphosphate and trimethylphosphate, dioxane, anhydrous acetic acid, ethyl acetate, diethylether, thioxane, etc. The sulfonating reaction preferably takes place at 0-80°C, or more preferably at 10-60°C. It is important to allow either carbon black or titanium oxide or an inorganic pigment to coexist during the sulfonation. During the sulfonation, either carbon black or titanium oxide, or both are preferably allowed to exist at a concentration of 1 × 10 -5 - 25 wt%, or more preferably at 5 × 10 -4 - 10 wt%. The inorganic pigment may be added to the reaction system prior to sulfonation so that it can coexist during sulfonation occurring subsequently, or inorganic pigment remains in the polystyrene resin may be used instead. Typically, polystyrene resin waste contains carbon black or titanium oxide as an additive, and when the content satisfies the above-described requirement, the polystyrene resin waste can undergo sulfonation without any deliberate addition of an inorganic pigment. The resin supplemented previously with an inorganic pigment disperses more readily in a reaction system. The resin supplemented with an inorganic pigment in advance preferably contains the pigment at 0.002-50 wt %, particularly at 0.01-10 wt%. when an inorganic solvent is allowed to coexist during the sulfonation of a polystyrene resin as described above, it improves the dispersibility of the resin so that reaction proceeds evenly. This inhibits cross-linking reactions within and among involved molecules, thereby suppressing the production of by-products insoluble to water. Thus, presence of an inorganic solvent in the reaction system ensures stable production of water-soluble polymer electrolytes, improves the dispersibility of polymer electrolytes, and allows stable production of polymer electrolytes even in quality. The reaction system, after sulfonation as described above, is allowed to react with a basic compound to be neutralized. The basic compound may include hydroxides and carbonates of alkali metals and alkali earth metals, ammonia, and primary to tertiary alkyl amine compounds. It may be added neat or as a solution gradually until the system is completely neutralized. When it is added as an aqueous solution, its addition varies according to the molecular weight of the polystyrene resin, but preferably is 1-100 times, or more preferably 2-50 times the total weight of the resin. When the neutralization reaction is completed, the solvent may be removed by fractional distillation or evaporation. Above procedures produce a water-soluble polymer electrolyte containing an inorganic pigment. Although generally the polymer electrolyte containing an inorganic pigment is excellent in its homogenous dispersibility when dissolved in water, it may be removed of the inorganic pigment by filtration as needed. In addition, disposal of liquid waste is enabled by utilizing the polymer electrolyte containing carbon black as an aggregating agent, or by utilizing the polymer aggregating agent in combination with carbon black. Carbon black to be used in this invention may include the products generally used as a coloring agent or a reinforcing agent of resins, or as a conductivity-conferring agent. Carbon black can be chosen from any products that have been produced by a channel method, furnace method or thermal method. A carbon black product which has been produced by any one of those methods may be used alone, or carbon black products which have been produced by different methods may be used in combination. It preferably has an average particle size of 5-500nm, or more preferably 10-50nm. When carbon black is placed in waste water, minute particles and organic elements suspending in the water cluster together around carbon black particles as nuclei, to form aggregates. These tiny aggregates, thanks to the polymer aggregating agent, cluster further together to form larger aggregates, which are then removed by filtration. This will result in reduction of the turbidity and COD of the filtrate. In above procedure, whether carbon black is added after having been combined with the polymer aggregating agent, or it is added independently of the polymer aggregating agent, the resulting effect will be the same. However, it is preferable for carbon black to be combined with the polymer aggregating agent prior to use, because then the polymer aggregating agent will disperse more evenly in waste water, and require no complicated processes as would be necessary if these agents were added separately. If they are added separately, any one of the two may come first, but it is more preferable to add carbon black first. When carbon black is combined with the polymer aggregating agent, its addition is preferably set to 0.01-20 wt%, or more preferably 0.05-10 wt% with respect to the polymer content of the polymer aggregating agent. When carbon black is added independently of the polymer aggregating agent to waste water, its added amount is typically 0.005-1000 ppm, or preferably 0.01-200 ppm, although the amount may be adjusted more or less according to the concentration of suspended particles (SS) in the water. If the added amount is too little, the filtrate, even after being removed of aggregates, will still hold a considerable fraction of turbidity and COD. On the contrary, if the added amount is too much, carbon black will remain in the filtrate, or interfere with aggregation of suspended particles. The polymer compound constituting the polymer aggregating agent may include sulfonates of polystyrene resins, non-ionic or anionic acrylamide resins, or cationic resins. They may be used alone or in combination. Non-ionic, anionic and cationic polymer aggregating agents appropriate for this invention will be given for illustration. <Non-ionic polymer aggregating agents> They may include polyacrylamide and polymethacrylamide, and preferably polyacrylamide. <Anionic polymer aggregating agents> They may include (metha)acrylate resins such as polyacrylamide and polymethacrylamide having undergone partial hydrolysis, copolymers of an acrylic acid or methacrylic acid with acrylamide or methacrylamide, or their salts, and triple copolymers of an acrylic acid or methacrylic acid with acrylamide or methacrylamide, and 2-acrylamide-methylpropane sulfonic acid or vinylsulfonic acid, and their salts. Preferred are polyacrylamide having undergone partial hydrolysis, copolymers of an acrylic acid with acrylamide and their salts, and triple copolymers of an acrylic acid with acrylamide and 2-acrylamide-methylpropane sulfonic acid, and their salts. The polystyrene sulfonate polymer may include polystyrene, styrenebutadiene, styrene-acrilonitrile, styrene-butadiene-acrilonitrile, styrene-(metha)acrylate, styrene-(metha)acrylate ester (aliphatic hydrocarbons with 1-4 carbons), styrene-butadiene-(metha)acrylate ester (aliphatic hydrocarbons with 1-4 carbons) , styrene-anhydrous maleic acid, and styrene-anhydrous itaconic acid. The polystyrene sulfonate polymer may include polystyrene, styrene-butadiene, styrene-acrylonitrile, styrene-butadiene-acrylonitrile, styrene-(metha)acrylate, styrene-(metha)acrylate esters (aliphatic hydrocarbons with 1-4 carbons), styrene-butadiene-(metha)acrylate esters (aliphatic hydrocarbons with 1-4 carbons), styrene-anhydrous maleate, and styrene-anhydrous itaconic acid. Of them preferred are polystyrene, styrene-butadiene, styrene-acrilonitrile, styrene-butadiene, and styrene-anhydrous maleic acid. Other polymers may include polyphenylene ether, polycarbonate, polyphenylene sulfide, and polyethyleneterephthalate, and of them preferably polyphenylene ether and polycarbonate. The anionic polymer aggregating agent can be prepared by recycling polystyrene resins which are mass-produced as a general-purpose resin material for many products, and hence can incorporate conveniently sulfonates of polystyrene resins. <Cationic polymer aggregating agents> Preferred are polymers of the quaternary compound of dialkylaminoalkyl(metha)acrylate (for example, with methyl chloride, benzyl chloride, etc.) or its salts (inorganic salts such as chlorinates, sulfates, etc., and organic salts such as acetates, etc.) or their compolymers with (metha)acrylamide. For example, polymers of the quaternary compound of dimethylaminoetheracrylate with methylchloride, or their copolymers with acrylamide are preferred. Polymers of the quaternary compound of dialkylaminoalkyl(metha)acrylamide or their acidic salts, or their copolymers with (metha)acrylamide are preferred. For example, copolymers of the quaternary compound of dimethylaminopropylacrylamide incorporating methylchloride, with acrylamide are preferred. Compounds which are produced after polyacrylamide has been made to have a cationic activity, and they include, for example, those that are produced after polyacrylamide has undergone Mannig's degeneration or Hoffman's decomposition. Compounds which are produced after epihalohydrine-amine has been condensed, and they include, for example, a polymerized condensate between ephihalohydrine and alkylene diamine with 2-8 carbons. Polydimethyldialylammonium chloride Condensates of dicyandiamide, and they include, for example, formalin condensates of dicyandiamide and ammonium chloride. Polyethylene imine Polyvinylimizazoline Acid salts of chitosan The cationic polymer aggregating agent preferably includes polymers of the quaternary compounds of dialkylaminoalkyl (metha)acrylate or their acid salts, and their copolymers with (metha)acrylamide, polymers of the quaternary compounds of dialkylaminoalkyl(metha)acrylamide or their acid salts, or their copolymers with (metha)acrylamide, and acid salts of chitosan. A plurality of polymer aggregating agents with the same ionic type may be combined, or a plurality of polymer aggregating agents with a combination of anionic and non-ionic activities, or with a cationic and non-ionic combination may be used. The polystyrene resin may be chosen from new materials (virgin material) specially prepared for the production of polymer electrolytes of this invention, or from wastes (waste materials) from plants, shops and households. Or, a combination of virgin and waste materials may be used. As seen from above, this invention can recycle polystyrene which has been mass-produced as a general-purpose resin, and hence is very beneficial for the protection of global environment from artificial pollutants. From this point of view, it is desirable for this invention to adopt waste materials as a source of polystyrene resins rather than virgin materials. Since many of waste polystyrene resin materials contain carbon black, they will provide, when the polystyrene resin has been converted to a sulfonate, an aggregating agent containing a sufficient amount of carbon black. For a polystyrene resin to be sulfonated, it is only necessary to dissolve or disperse the polystyrene resin in an organic solvent, and to add a sulfonating agent to the solution. The solution, after sulfonation, is neutralized through reaction with a basic compound, and the solvent is removed by fractional distillation or by evaporation. The solvent preferably includes aliphatic halogenated hydrocarbons with 1-4 carbons represented by 1,2-dichlorohexane, and aliphatic, cyclic compounds represented by cyclohexane. This invention may recycle polymer electrolytes which contain a sulfonated styrene polymer as a principal ingredient, and whose molecular weight is 150,000 to 600,000. The polystyrene resin used for this purpose may be chosen from new materials ( virgin material) specially prepared for the production of polymer electrolytes of this invention, or from wastes (waste materials) from plants, shops and households. Or, a combination of virgin and waste materials may be used. This invention can recycle polystyrene which has been mass-produced as a general-purpose resin, and hence is very beneficial for the protection of global environment from artificial pollutants. From this point of view, it is desirable for this invention to adopt waste materials as a source of polystyrene rather than virgin materials. The above-described polymer aggregating agent can be obtained by allowing specified amounts of styrene polymer, sulfonating agent and solvent to mix and undergo sulfonating reaction. For this sulfonating reaction, addition of the styrene polymer is preferably set to 0.1-30 wt%, or more preferably to 0.5-20 wt%. If the styrene polymer is allowed to have a concentration lower than above range, it will be difficult to introduce sulfone group into the styrene polymer. On the contrary, if the styrene polymer is adjusted to have a concentration exceeding above range, gels will readily develop during sulfonation, or a large fraction of polymer will remain unreacted. Sulfonation reaction is preferably allowed to proceed at 0-100°C, or more preferably at 15-80°C. If the reaction temperature is set below this range, sulfonation will hardly take place, and the yield of polymer aggregating agent will be reduced. Further, the sulfonating reaction is allowed to take 10 minute to 10 hours, more preferably 30 minutes to 5 hours (the time required for dropwise addition of the sulfonating agent is not included). The solution, after having completed sulfonation in the manner as described above, has sulfone group neutralized by the addition of a neutralizing agent, and is removed of its solvent through evaporation, to produce the target polymer aggregating agent. The neutralizing agent may include oxides, hydroxides, carbonates, acetates, sulfates and phosphates of basic compounds such as alkali metals (sodium, lithium, potassium, etc.) and of alkali earth metals (magnesium, calcium, etc.), ammonia, and various (primary to tertiary alkyl) amine oompounds. The neutralizing agent may be slowly added as a solid or an aqueous solution to the reaction system, to neutralize sulfone group introduced into the styrene polymer. Removal of the solvent may take place through fractional distillation or evaporation. The thus-obtained polymer aggregating agent must have a molecular weight of 150,000 to 600,000, or more preferably 200,000 to 500,000. The polymer aggregating agent of which the sulfonated styrene polymer has a molecular weight less than 150,000 will lose the activity to aggregate suspended particles in a suspension, and rather disperse those suspended matters into the solvent. On the contrary, if the sulfonated styrene polymer has a molecular weight of 600,000 or more, it will cause suspended particles to aggregate into coarse masses, not being able to purify water sufficiently, and the resulting cake will contain too much water. For this polymer aggregating agent, 40 mol% or more, or preferably 50 mol% or more sulfone group is introduced into the styrene polymer. The polymer aggregating agent, of which the styrene polymer contains 40 mol% or less sulfone group, will become less soluble to water, and thus greatly lose the aggregating activity towards suspended matters in a suspension. As discussed above, for the desired amount of sulfone group to be introduced into the styrene polymer to produce a proper polymer aggregating agent, the styrene unit preferably occupies 60 mol%, or more preferably 80 mol% or more of the styrene polymer. If the fraction of styrene unit in the styrene polymer were less than 60 mol%, it would be difficult to obtain a polymer aggregating agent in which the desired amount of sulfone group can be introduced through sulfonation. The thus-obtained polymer aggregating agent may be used in combination with another aggregating agent consisting of acrylamide polymer with non-ionic and/or anionic activity, for the treatment of waste water. The agent in question may be used in combination with another aggregating agent with cationic activity as well. Any one of non-ionic, anionic, or cationic polymer aggregating agents that have been cited above may be used. The polymer aggregating agent, when used in combination with another aggregating agent, may be combined with the latter prior to use, or may be added separately during use. Particularly, when it is used in combination with a cationic polymer aggregating agent, it is preferably added separately during use. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Polymer electrolyte containing an inorganic substance A resin was prepared by grinding following substances with a milling machine. (a) Polystyrene Aldrich, molecular weight (Mw) = 280,000 (free from inorganic pigments) (b) High impact polystyrene housing material for VHS cassette tapes (containing 1 wt% carbon black) (c) High impact polystyrene: alloy with polyphenyleneether housing material of facsimile machines (containing 2 wt% titanium oxide) (d) Polystyrene: alloy with polyphenyleneether housing material of CD-ROM drives (containing 2 wt% carbon black) Example 1 Sixty gram of polystyrene (a) was dissolved in 540g of 1,2-dichloroethane, to which was added 0.5g of carbon black (a standard product for coloration, HCC type, having an average particle size of 9-14nm). The mixture was heated to 50°C, to which was dropwise added 77g of 60% fuming sulfuric acid over 30 minutes. A slurry product developed in the reaction system, but there was no gel adherence on the wall of the reaction vessel throughout the reaction process. After dropwise addition, for further 30 minutes, the mixture was kept at the same temperature for sulfonation, and while the reaction proceeded an aqueous solution of sodium hydroxide was added for neutralization. Then, the mixture was heated to remove 1,2-dichloroethane through evaporation, and the residue was dissolved in water, which was then adjusted with sodium hydroxide to give pH 8. This procedure gave a 20 wt% aqueous solution of the polymer electrolyte. The thus obtained aqueous solution of the polymer electrolyte was allowed to stand at room temperature for one month, and still held a good homogenous dispersibility. Example 2 A solution was produced after 6.93g of high impact polystyrene (b) was dissolved in 63g of 1,2-dichloroethane. The first solution and 9.33g of 60% fuming sulfuric acid were simultaneously added dropwise over 60 minutes to a solution which was produced after 2.44g of triethylphosphate had been added to 70g of 1,2-dichloroethane. During dropwise addition, the reaction system was controlled to be in the range of 20-25°C. Carbon black contained in the high impact polystyrene (b) dispersed evenly in the reaction system, and produced stable, slurry compounds with the progression of sulfonation. In this example either, there was no adherence of gel substances to the wall of the reaction vessel. After dropwise addition, for further 30 minutes, the mixture was kept at the same temperature for sulfonation, and, while the reaction proceeded, an aqueous solution of sodium hydroxide was added for neutralization. Then, the mixture was heated to remove 1,2-dichloroethane through evaporation, and the residue was dissolved in water to give a 20 wt% aqueous solution of the polymer electrolyte. The thus obtained aqueous solution of the polymer electrolyte was allowed to stand at room temperature for one month, and still held a good homogenous dispersibility. Example 3 A solution produced after 0.6g of triethyl phosphate had been added to 70g of 1,2-dichloroethane, while being kept at 20-25°C, was added to 0.27g of anhydrous sulfuric acid. A solution produced after 7.0g of alloy (c) of high impact polystyrene-polyphenylene ether had been dissolved in 63g of 1,2-dichloroethane, and 5.4g of anhydrous sulfuric acid, while being kept at the same temperature, were simultaneously added dropwise over 60 minutes to the foregoing mixture. Titanium oxide contained in the high impact polystyrene (c) dispersed evenly in the reaction system, and produced stable, slurry compounds with the progression of sulfonation. In this example either, there was no adherence of gel substances to the wall of the reaction vessel. After dropwise addition, 32g of an aqueous solution containing 3.0g of sodium hydroxide was slowly added with stirring to the reaction system for neutralization. Then, the mixture was heated to remove the solvent through evaporation, the residue was dissolved in water, and the aqueous solution was adjusted by the addition of sodium hydroxide to give pH 8. This procedure produced an aqueous solution containing 30 wt% polymer electrolyte. The thus obtained aqueous solution of the polymer electrolyte was allowed to stand at room temperature for one month, and still held a good homogenous dispersibility. Example 4 The same procedure was employed as in Example 3 except that an alloy (d) of polystyrene-polyphenylene ether was used instead of the alloy of high impact polystyrene-polyphenylene ether (c), to produce an aqueous solution of polymer electrolyte. In this case too, carbon black contained in the alloy (d) of polystyrene-polyphenylene ether dispersed evenly in the reaction system, and produced stable, slurry compounds with the progression of sulfonation. In this example either, there was no adherence of gel substances to the wall of the reaction vessel. The thus obtained aqueous solution of the polymer electrolyte was allowed to stand at room temperature for one month, and still held a good homogenous dispersibility. Comparative Example 1 The same procedure was employed as in Example 1 except that carbon black was not added, to produce an aqueous solution of polymer electrolyte. In this Comparative Example, about 10 minutes after dropwise addition of fuming sulfuric acid, a solid mass of gel substances developed in the reaction system, and, on completion of the dropwise addition, the gel substances adhered to the wall of the reaction vessel. In addition, these gel substances remained insoluble to water or alkaline aqueous solutions. Evaluation of performance Comparison of Example 1 and Comparative Example 1 showed that the presence of carbon black inhibits the development of by-products insoluble to water while polystyrene is undergoing sulfonation. Example 2 further revealed that waste materials derived from used polystyrene resins can provide a good yield of aqueous solution of polymer electrolyte, and that used polystyrene resins already contain a sufficient amount of carbon black. Further, results from Examples 3 and 4 demonstrated that an alloy of polystyrene resin with another polymer can provide an aqueous solution of polymer electrolyte as good as that provided by a polystyrene resin alone.

Claims: Method of producing a polymer electrolyte which is characterized by sulfonating a polystyrene resin in the presence of an inorganic pigment, thereby changing it into a water-soluble polymer electrolyte. Method of producing a polymer electrolyte as described in claim 1 wherein the inorganic pigment is added prior to sulfonation. Method of producing a polymer electrolyte according to any of the preceding claims wherein the inorganic pigment has been combined with the polystyrene resin prior to use. Method of producing a polymer electrolyte according to any of the preceding claims wherein the polystyrene resin is derived from a waste material. Method of producing a polymer electrolyte according to any of the preceding claims wherein the polystyrene resin has been dissolved in a solvent prior to sulfonation. Method of producing a polymer electrolyte according to any of the preceding claims wherein the inorganic pigment is either carbon black or titanium oxide.

Inventors: INAGAKI YASUHITO, KUROMIYA MIYUKI, NOGUCHI TSUTOMU, WATANABE HARUO, INAGAKI, YASUHITO, KUROMIYA, MIYUKI, NOGUCHI, TSUTOMU, WATANABE, HARUO
Applicants: SONY CORP, SONY CORPORATION
Application year: 1997
Main classification: C02F1
IPC codes: C08F8, C02F1