JP2006265478A - Electrolyte material and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an electrolyte material that is excellent in oxidation resistance. <P>SOLUTION: The method comprises a process for introducing a polymerization starting point into a base material, a process of grafting a vinyl monomer containing a monomer represented by formula (1) (where X is a halogen) to the polymerization starting point, a process of reacting an antioxidant having a functional group selected from an OH group, an amino group, and an imino group in the molecular structure through the functional groups, and a post-treatment process including a step of reacting a sulfonation agent. According to the method, the polymer material is formed as the base backbone of an electrolyte material before the polymer chain is coupled with the antioxidant, allowing the introduction of the polymer chain with the antioxidant without inhibiting the chemical reaction for forming the polymer chain, and further facilitating the polymer chain to couple with the antioxidant so strongly that the electrolyte material does not easily uncouple and can keep improved resistance to oxidation for a long time. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrolyte material that has excellent oxidation resistance and can be suitably used for a fuel cell, and a method for producing the same.

  An electrolyte material is used for the fuel cell. Many electrolyte materials employing perfluoro-based electrolyte materials have been reported.

  The perfluoro-based electrolyte material is represented by Nafion (trademark), and is a material generally employed in fuel cells, and is a material excellent in oxidation resistance. In the fuel cell, when protons produced at the anode reach the cathode through the electrolyte membrane during the electrode reaction process, they are oxidized by oxygen supplied to the cathode to produce water. The hydroxyl radicals may diffuse and decompose fuel cell components.

  A perfluoro-based electrolyte material is a material excellent in oxidation resistance due to high binding energy between carbon and fluorine. However, although perfluoro-based electrolyte material has high performance when applied to a fuel cell, it is a material synthesized through a complicated process and has a high fluorine content, so the cost is very high. It is an obstacle to the spread of batteries.

  Therefore, with the aim of reducing costs, hydrocarbon-based electrolyte materials for fuel cell electrodes (in the present specification, replacement with fluorine is completely performed because the cost can be reduced by reducing fluorine. It has been studied to employ an electrolyte material that is not included in the "hydrocarbon electrolyte material" (Patent Document 1, etc.).

  Hydrocarbon electrolyte materials can generally be reduced in cost, but there has been a tendency that sufficient performance cannot be exhibited as compared with perfluoro electrolyte materials. One reason for this is that the hydrocarbon-based electrolyte material has a lower carbon-hydrogen bond energy than the carbon-fluorine bond energy, so that the oxidation resistance is not as good as that of the perfluoro-electrolyte material. It is considered that the properties cannot be fully exhibited.

  Further, it is needless to say that even perfluoro-based electrolyte materials are not deteriorated by oxidation at all, and further improvement in oxidation resistance is required.

  As a conventional technology developed for the purpose of improving the oxidation resistance of electrolyte materials, it is possible to incorporate a polymer combined with a phenolic antioxidant when a electrolyte polymer is formed by radical polymerization. A method of introducing an antioxidant into the chain is disclosed (Patent Document 2).

In addition, a technique for providing an antioxidant function by impregnating an electrolyte membrane with an antioxidant (phosphorus-based or sulfur-based) is disclosed (Patent Document 3).
Japanese Patent Laid-Open No. 5-36418 JP 2000-223135 A JP 2003-151346 A

  However, in the technique described in Patent Document 2, as a result of inhibition of the progress of radical polymerization by a monomer into which an antioxidant is introduced, it may be difficult to form a polymer chain having a necessary molecular weight. Further, in the technique described in Patent Document 3, it is predicted that the impregnated antioxidant is eluted, and it is difficult to stably impart oxidation resistance.

  This invention is made | formed in view of the said situation, and makes it the problem which should be solved to provide the electrolyte material excellent in oxidation resistance, and its manufacturing method.

(1-1) As a result of intensive studies for the purpose of solving the above-mentioned problems, the present inventors have conceived the following invention. That is, the method for producing an electrolyte material of the present invention includes a step of introducing a polymerization initiation point into a substrate,
Starting from the polymerization initiation point, grafting a vinyl monomer containing a monomer represented by the following general formula (1);
A post-treatment step having a step of reacting an antioxidant having a functional group selected from an OH group, an amino group and an imino group in the molecular structure, and a step of reacting a sulfonating agent;
It is characterized by having.

(In the formula (1), R is an alkylene group having one or more C; n is 1 or more; R ′ is hydrogen or an alkyl group having 1 to 4 C; X is halogen)
In other words, after forming a polymer material that is the basic skeleton of the electrolyte material, an antioxidant is bonded into the polymer chain, thereby oxidizing the polymer chain without inhibiting the chemical reaction that forms the polymer chain. In addition to the introduction of an inhibitor, the antioxidant is firmly bonded to the polymer chain, so that it does not easily fall off, and long-term oxidation resistance can be improved.

  Here, it is desirable that the vinyl monomer contains styrene and chloromethylstyrene which is a monomer described in the general formula (1).

(1-2) Then, another method for producing an electrolyte material of the present invention includes reacting the functional group of an antioxidant having a functional group selected from an OH group, an amino group, and an imino group in the molecular structure. A treatment step having a step of introducing, and a step of introducing a proton conductive functional group,
It is characterized by being performed on a polymer material having a halogenated alkyl group.

  That is, the method for producing an electrolyte material according to the present invention does not contain an antioxidant that may become a reaction inhibiting factor when producing a polymer material that is a basic skeleton of the electrolyte material. It is the method of combining. Since the polymer material has a halogenated alkyl group that is a site where an antioxidant can be introduced, the antioxidant can be easily introduced by a subsequent reaction.

  (1-3) In the method for producing an electrolyte material of the present invention, the antioxidant is preferably selected from amine-based antioxidants and phenol-based antioxidants. The amine-based antioxidant has an amino group or an imino group in the structure, and in particular, can be applied to the present production method without introducing an OH group, an amino group, or an imino group into the structure.

(2) The electrolyte material of the present invention that solves the above problems includes a base material made of a polyolefin-based material in which hydrogen may be partially substituted with fluorine,
A side chain grafted to the substrate, which is a copolymer of styrene and halogenated methylstyrene,
The side chain reacts with the functional group of the antioxidant in which at least a part of the halogen portion derived from the halogenated methylstyrene has a functional group selected from OH group, amino group and imino group in the molecular structure. And at least part of hydrogen of the phenyl group derived from the styrene and the halogenated methylstyrene is substituted with a sulfo group. Here, the base material is preferably an ethylene-tetrafluoroethylene copolymer.

  Since the antioxidant is contained in the molecular structure, it is unlikely that the removal of the antioxidant becomes a problem.

  The method for producing an electrolyte material according to the present invention does not contain an antioxidant that may be a hindrance to reaction when producing a polymer material that is a basic skeleton of the electrolyte material. Necessary molecular weight can be realized. In addition, since the antioxidant can be directly bonded to the electrolyte material, the effect of improving the oxidation resistance lasts for a long time.

  The electrolyte material and the manufacturing method thereof of the present invention will be described in detail based on the following embodiments.

(First embodiment)
The method for producing an electrolyte material of the present embodiment includes a step of introducing a polymerization start point into a base material that is a basic skeleton of the electrolyte material, a step of grafting to the base material, and a post-processing step.

  Although it does not specifically limit as a base material, It is desirable to employ | adopt polyolefin material with high intensity | strength and high oxidation resistance. In the polyolefin material, hydrogen may be partially substituted by fluorine. For example, ethylene-tetrafluoroethylene copolymer (ETFE) is desirable from the viewpoint of handleability and cost. A material that can be a basic skeleton of a perfluoro-based electrolyte material can also be employed. Here, depending on the selection of the base material, the form such as a film or gel and the properties such as insolubility and solubility are determined.

  The polymerization initiation point introduced into the substrate includes radicals that can be radical polymerization initiation points, radicals that are decomposed by heat, light, and the like, ion pairs that can act as ion polymerization initiation points, and the like. For example, radicals can be generated by treatment with radiation irradiation, plasma irradiation, flame, or the like, or radicals or ions can be generated by oxidation with an oxidizing agent or the like. These radicals are preferably generated in an inert atmosphere so that the radicals do not disappear. For example, when generating radicals, it is desirable to generate radicals by irradiating radiation in a non-reactive atmosphere such as nitrogen or argon gas atmosphere or under vacuum.

  The step of grafting is a step of making a polymer material to be a precursor of an electrolyte material by reacting a vinyl monomer from the polymerization starting point formed on the substrate. A vinyl monomer is mixed with the base material, and the vinyl monomer is reacted according to the properties of the polymerization starting point. For example, when the polymerization initiation point is a radical, grafting proceeds by contacting a vinyl monomer in an inert atmosphere. In the case of a polymerization starting point where radicals are generated by decomposition with heat or light, the reaction conditions are adjusted.

  As a vinyl monomer, the monomer shown in the above general formula (1) is included. The monomer of the general formula (1) is a compound in which a halogenated alkyl group is introduced into the phenyl group of styrene or α-alkylstyrene, and the halogen site of the halogenated alkyl group is dropped, which will be described later. Can react and bind with antioxidants.

  The functional group R ′ bonded to the α-position is hydrogen or an alkyl group, and hydrogen is particularly desirable from the viewpoint of stability. X is a halogen, and chlorine is particularly desirable. R is an alkylene group, preferably a methylene or ethylene group, and a methylene group is particularly desirable from the viewpoint of availability and cost. One or more RX groups may be introduced, and the introduction site may be any of the para position, the meta position, and the ortho position.

  As other vinyl monomers, those having excellent oxidation resistance and easy polymerization reaction are desirable. Examples thereof include styrene, divinylbenzene, methyl styrene, t-butyl styrene, α-methyl styrene, acrylonitrile, and methyl methacrylate. A monomer having a phenyl group in its structure, such as styrene, is desirable because the sulfo group is easily introduced in the sulfonation step described later. Since the bifunctional monomer such as divinylbenzene acts as a cross-linking agent, the physical properties of the produced electrolyte material can be adjusted by mixing an appropriate amount.

  The mixing ratio of the monomer described in the general formula (1) and another monomer is not particularly limited. By introducing a large amount of the monomer described in the general formula (1), more antioxidant can be introduced. Therefore, it is desirable to determine the amount to be introduced according to the antioxidant ability required for the electrolyte material to be finally produced. In addition, these methods for manufacturing the polymer material are examples, and those manufactured by such a method may be used.

  An antioxidant is a compound having in its molecular structure a functional group selected from an OH group, an amino group and an imino group. For example, an amine antioxidant, a phenolic antioxidant, etc. are mentioned.

  As amine-based antioxidants, 2,2,6,6-tetramethylpiperidine, bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate, phenyl-α-naphthylamine, phenyl-β-naphthylamine , P- (P-toluenesulfonylamide) -diphenylamine, 4,4 ′-(α, α-dimethylbenzyl) -diphenylamine, 4,4′-dioctyl-diphenylamine, P, P′-dioctyl-diphenylamine, alkylation Diphenylamine, N, N′-diphenyl-P-phenylenediamine, N-isopropyl-N′-phenyl-P-phenylenediamine, N, N′-dinaphthyl-P-phenylenediamine, N-cyclohexyl-N′-phenyl-P -Phenylenediamine, N-phenyl-N '-(3-methacryloyl X-P-phenylenediamine, N, N′-bis (1-methylheptyl) -P-phenylenediamine, N, N′-bis (1,4-dimethylpentyl) -P-phenylenediamine, N, N′- Bis (1-ethyl-3-methylpentyl) -P-phenylenediamine, N- (1,3-dimethylbutyl) -N′-phenyl-P-phenylenediamine, etc. Among amine-based antioxidants, In particular, it is preferable to employ a hindered amine antioxidant, which may be 2,2,6,6-tetramethylpiperidine, bis (2,2,6,6-tetramethyl-4-piperidinyl). Sebacate and the like are preferable.

  Examples of phenolic antioxidants include hydroquinone, styrenated phenol, 2,6-di-tert-butyl-4-methylphenol, 4,4′-thiobis (3-methyl-6-tert-butylphenol), bis (3 -Methyl-4-hydroxy-5-t-butylbenzyl) sulfide, 1,1'-bis (4-hydroxyphenyl) -cyclohexane, 2,5-di-t-butylhydroquinone, 2,5-di-t- Amylhydroquinone, 2,2′-methylenebis (4-methyl-6-tert-butylphenol, 2,2′-methylenebis (4-ethyl-6-tert-butylphenol, 4,4′-butylidenebis (3-methyl-6- t-butylphenol), 4,4′-methylenebis (2,6-di-t-butylphenol), 2,2-thio [diethyl-bis-3 (3,5- -T-butyl-4-hydroxyphenol) propionate], tetrakis [methylene-3 (3,5-di-t-butyl-4-hydroxyphenol) propionate] methane, 1,3,5-trimethyl-2,4 6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, n-octadecyl- 3- (4′-hydroxy-3′5′-di-t-butylphenol) propionate, 6- (4-hydroxy-3,5-di-t-butylanilino) -2,4-bis-octyl-thio-1 3,5-triazine.

  In addition, other sulfur-based and phosphorus-based antioxidants may be used by introducing an OH group, an amino group or an imino group into the structure, or by introducing an OH group, an amino group or an imino group. it can.

  In order to introduce these antioxidants into the polymer material, halogenation of the polymer material is performed by immersing the polymer material in which the antioxidant is to be bound in a solution in which the antioxidant is dissolved in an appropriate solvent. The OH group, amino group or imino group of the antioxidant is bonded to the halogen part of the alkyl group.

  Then, a sulfo group is introduced to impart proton conductivity to the polymer material. The sulfo group can be introduced by reacting an appropriate sulfonating agent. The sulfo group can be easily introduced into the phenyl group, can be introduced into the phenyl group site derived from the compound of the general formula (1), and can also be introduced into the phenyl group site when styrene is employed as the vinyl monomer. Examples of the sulfonating agent include chlorosulfonic acid, fuming sulfuric acid, sulfuric acid and the like as they are, or a solution in which they are dissolved in an appropriate solvent. Either the step of introducing the antioxidant or the sulfonation step may be performed first, but the introduction of the antioxidant can be more reliably performed by performing the step of introducing the antioxidant first.

(Second Embodiment)
The electrolyte material of the present embodiment (manufacturing method thereof) has no base material in the electrolyte material of the first embodiment (manufacturing method thereof), and has a OH group for a polymer material having a halogenated alkyl group, This is a process that includes a step of introducing a functional group of an antioxidant having a functional group selected from an amino group and an imino group in the molecular structure by reacting and a step of introducing a proton conductive functional group. is there. Since the electrolyte material of this embodiment does not have a base material like the electrolyte material of the first embodiment, it can be easily adjusted so that it can be dissolved in an appropriate solvent.

  The step of introducing the antioxidant is the same as that described in the first embodiment. Examples of the proton conductive functional group include a carboxy group and a phosphate group in addition to the same sulfo group as in the first embodiment.

  Examples of the present invention will be described below. In the following examples, a film made of ETFE (thickness 25 μm) was adopted as the substrate.

(Example 1)
After the ETFE film was washed with acetone, gamma rays were irradiated at 10 kGy using cobalt 60 as a radiation source to generate radicals as polymerization initiation points. After putting the obtained film into a glass reaction tube, a styrene-chloromethylstyrene-divinylbenzene mixture (9: 0.5: 0.5) as a vinyl monomer was added to the reaction tube, and the inside of the reaction tube was Fully replaced with nitrogen.

  Then, the reaction tube was immersed in a 60 degreeC thermostat for 2 hours. Thereafter, the film was washed with xylene three times and then dried using a dryer. The dry mass was 1.45g. The mass grafted with the vinyl monomer was 45% with respect to the ETFE film before the reaction.

  In a state where 200 mg of this dry film was immersed in 20 mL of 1-propanol, 20 mg of hindered amine antioxidant (2,2,6,6-tetramethylpiperidine) as an antioxidant was dissolved. The mixture was refluxed for 3 hours under an inert gas atmosphere. After the reaction, the membrane was taken out, washed with ethanol and dried. The dry mass was 202.9 mg. The amount of 2,2,6,6-tetramethylpiperidine introduced was 1.4% by mass.

  This dry membrane was immersed in 30 mL of a 1% chlorosulfonic acid-dichloroethane solution and reacted at 60 ° C. for 1.5 hours. Thereafter, the membrane was taken out and washed by being immersed in hot water at 90 ° C. for 24 hours.

  The obtained electrolyte membrane had an ion exchange capacity of 1.8 meq / g and an ionic conductivity of 0.07 S / cm (AC impedance method, 90 ° C. saturated water-containing state, room temperature).

(Example 2)
After the ETFE film was washed with acetone, gamma rays were irradiated at 10 kGy using cobalt 60 as a radiation source to generate radicals as polymerization initiation points. After putting the obtained film into a glass reaction tube, a styrene-chloromethylstyrene-divinylbenzene mixture (7: 2.5: 0.5) as a vinyl monomer was added to the reaction tube, and the inside of the reaction tube was Fully replaced with nitrogen.

  Then, the reaction tube was immersed in a 60 degreeC thermostat for 2 hours. Thereafter, the film was washed with xylene three times and then dried using a dryer. The dry mass was 1.5 g. The mass grafted by the vinyl monomer was 50% with respect to the ETFE film before the reaction.

  In a state where 200 mg of this dry film was immersed in 20 mL of 1-propanol, 50 mg of 2,2,6,6-tetramethylpiperidine was dissolved. The mixture was refluxed for 3 hours under an inert gas atmosphere. After the reaction, the membrane was taken out, washed with ethanol and dried. The dry mass was 211.5 mg. The amount of 2,2,6,6-tetramethylpiperidine introduced was 5.7% by mass.

  This dry membrane was immersed in 30 mL of a 1% chlorosulfonic acid-dichloroethane solution and reacted at 60 ° C. for 1.5 hours. Thereafter, the membrane was taken out and washed by being immersed in hot water at 90 ° C. for 24 hours.

  The obtained electrolyte membrane had an ion exchange capacity of 1.4 meq / g and an ionic conductivity of 0.05 S / cm (AC impedance method, 90 ° C. saturated water-containing state, room temperature).

(Example 3)
After the ETFE film was washed with acetone, gamma rays were irradiated at 10 kGy using cobalt 60 as a radiation source to generate radicals as polymerization initiation points. After the obtained film was put in a glass reaction tube, a styrene-chloromethylstyrene-divinylbenzene mixture (5.5: 4: 0.5) as a vinyl monomer was added to the reaction tube, and the inside of the reaction tube was Fully replaced with nitrogen.

  Then, the reaction tube was immersed in a 60 degreeC thermostat for 2 hours. Thereafter, the film was washed with xylene three times and then dried using a dryer. The dry mass was 1.4 g. The mass of the vinyl monomer grafted was 40% with respect to the ETFE film before the reaction.

  In a state where 200 mg of this dry film was immersed in 20 mL of 1-propanol, 50 mg of 2,2,6,6-tetramethylpiperidine was dissolved. The mixture was refluxed for 3 hours under an inert gas atmosphere. After the reaction, the membrane was taken out, washed with ethanol and dried. The dry mass was 215.4 mg. The amount of 2,2,6,6-tetramethylpiperidine introduced was 7.7% by mass.

  This dry membrane was immersed in 30 mL of a 1% chlorosulfonic acid-dichloroethane solution and reacted at 60 ° C. for 1.5 hours. Thereafter, the membrane was taken out and washed by being immersed in hot water at 90 ° C. for 24 hours.

  The obtained electrolyte membrane had an ion exchange capacity of 1.1 meq / g and an ionic conductivity of 0.03 S / cm (AC impedance method, 90 ° C. saturated water-containing state, room temperature).

Example 4
After the ETFE film was washed with acetone, gamma rays were irradiated at 10 kGy using cobalt 60 as a radiation source to generate radicals as polymerization initiation points. After putting the obtained film into a glass reaction tube, a styrene-chloromethylstyrene-divinylbenzene mixture (9: 0.5: 0.5) as a vinyl monomer was added to the reaction tube, and the inside of the reaction tube was Fully replaced with nitrogen.

  Then, the reaction tube was immersed in a 60 degreeC thermostat for 2 hours. Thereafter, the film was washed with xylene three times and then dried using a dryer. The dry mass was 1.45g. The mass grafted with the vinyl monomer was 45% with respect to the ETFE film before the reaction.

  After adding 100 mg of hydroquinone as a phenolic antioxidant to 20 mL of dimethylformamide (DMF), 20 mg of sodium hydride was added, and after reacting at 40 ° C. for 20 minutes, 200 mg of this dry film was immersed. The reaction was carried out at 120 ° C. for 5 hours under an inert gas atmosphere. After the reaction, the membrane was taken out, washed with ethanol and dried. The dry mass was 202 mg. The amount of hydroquinone introduced was 1% by mass.

  This dry membrane was immersed in 30 mL of a 1% chlorosulfonic acid-dichloroethane solution and reacted at 60 ° C. for 1.5 hours. Thereafter, the membrane was taken out and washed by being immersed in hot water at 90 ° C. for 24 hours.

  The obtained electrolyte membrane had an ion exchange capacity of 1.9 meq / g and an ionic conductivity of 0.085 S / cm (AC impedance method, 90 ° C. saturated water-containing state, room temperature).

(Example 5)
After the ETFE film was washed with acetone, gamma rays were irradiated at 10 kGy using cobalt 60 as a radiation source to generate radicals as polymerization initiation points. After putting the obtained film into a glass reaction tube, a styrene-chloromethylstyrene-divinylbenzene mixture (7: 2.5: 0.5) as a vinyl monomer was added to the reaction tube, and the inside of the reaction tube was Fully replaced with nitrogen.

  Then, the reaction tube was immersed in a 60 degreeC thermostat for 2 hours. Thereafter, the film was washed with xylene three times and then dried using a dryer. The dry mass was 1.5 g. The mass grafted by the vinyl monomer was 50% with respect to the ETFE film before the reaction.

  In a state where 200 mg of this dry film was immersed in 20 mL of 1-propanol, 10 mg of 2,2,6,6-tetramethylpiperidine was dissolved. The mixture was refluxed for 3 hours under an inert gas atmosphere. After the reaction, the membrane was taken out, washed with ethanol and dried. The dry mass was 204.5 mg. The amount of 2,2,6,6-tetramethylpiperidine introduced was 2.2% by mass.

  After adding 100 mg of hydroquinone to 20 mL of DMF, 20 mg of sodium hydride was added, and after reacting at 40 ° C. for 20 minutes, 200 mg of this dry film was immersed. The reaction was carried out at 120 ° C. for 5 hours under an inert gas atmosphere. After the reaction, the membrane was taken out, washed with ethanol and dried. The dry mass was 207 mg. The amount of hydroquinone introduced was 1.25% by mass.

  This dry membrane was immersed in 30 mL of a 1% chlorosulfonic acid-dichloroethane solution and reacted at 60 ° C. for 1.5 hours. Thereafter, the membrane was taken out and washed by being immersed in hot water at 90 ° C. for 24 hours.

  The obtained electrolyte membrane had an ion exchange capacity of 1.7 meq / g and an ionic conductivity of 0.07 S / cm (AC impedance method, 90 ° C. saturated water-containing state, room temperature).

(Example 6)
10 mg of benzoyl peroxide was dissolved in 30 mL of a styrene-chloromethylstyrene-divinylbenzene mixture (7.5: 2.5: 0.5) as a vinyl monomer, purged with nitrogen, and reacted at 80 ° C. for 2 hours. . Then, the vinyl monomer polymer produced by dropping the reaction solution cooled to room temperature into a large amount of ethanol was precipitated. The precipitate was collected by filtration and dried to obtain 20 g of resin.

  In a state where 2 g of this resin was immersed in 30 mL of toluene, 200 mg of 2,2,6,6-tetramethylpiperidine was dissolved. The mixture was refluxed for 2 hours under an inert gas atmosphere. After the reaction, it was dropped into a large amount of ethanol to precipitate a vinyl monomer polymer. The precipitate was collected by filtration and dried to obtain 2.1 g of resin. The amount of 2,2,6,6-tetramethylpiperidine introduced was 5% by mass.

  It put into 30 mL of this dry resin dichloroethane solution, 1 g of chlorosulfonic acid was added, and it was made to react at room temperature for 1.5 hours. Thereafter, the reaction solution was poured into 100 mL of ion-exchanged water, and then heated to 90 ° C. to evaporate dichloroethane. A pale yellow precipitate was formed by evaporation of dichloroethane, which was collected by filtration and washed with ion-exchanged water until the washing solution became neutral to obtain an electrolyte material.

  The obtained electrolyte material had an ion exchange capacity of 1.7 meq / g (EW = 588).

(Comparative Example 1)
After the ETFE film was washed with acetone, gamma rays were irradiated at 10 kGy using cobalt 60 as a radiation source to generate radicals as polymerization initiation points. After putting the obtained film into a glass reaction tube, a styrene-divinylbenzene mixture (9.5: 0.5) as a vinyl monomer was added to the reaction tube, and the inside of the reaction tube was sufficiently replaced with nitrogen. .

  Then, the reaction tube was immersed in a 60 degreeC thermostat for 2 hours. Thereafter, the film was washed with xylene three times and then dried using a dryer. The dry mass was 1.4 g. The mass of the vinyl monomer grafted was 40% with respect to the ETFE film before the reaction.

  This dry membrane was immersed in 30 mL of a 1% chlorosulfonic acid-dichloroethane solution and reacted at 60 ° C. for 1.5 hours. Thereafter, the membrane was taken out and washed by being immersed in hot water at 90 ° C. for 24 hours.

  The obtained electrolyte membrane had an ion exchange capacity of 2.0 meq / g and an ionic conductivity of 0.09 S / cm (AC impedance method, 90 ° C. saturated water-containing state, room temperature).

(Comparative Example 2)
10 mg of benzoyl peroxide was dissolved in 30 mL of a styrene-chloromethylstyrene-divinylbenzene mixture (7.5: 2.5: 0.5) as a vinyl monomer, purged with nitrogen, and reacted at 80 ° C. for 2 hours. . Then, the vinyl monomer polymer produced by dropping the reaction solution cooled to room temperature into a large amount of ethanol was precipitated. The precipitate was collected by filtration and dried to obtain 20 g of resin.

  It put into 30 mL of this dry resin dichloroethane solution, 1 g of chlorosulfonic acid was added, and it was made to react at room temperature for 1.5 hours. Thereafter, the reaction solution was poured into 100 mL of ion-exchanged water, and then heated to 90 ° C. to evaporate dichloroethane. A pale yellow precipitate was formed by evaporation of dichloroethane, which was collected by filtration and washed with ion-exchanged water until the washing solution became neutral to obtain an electrolyte material.

  The obtained electrolyte material had an ion exchange capacity of 1.9 meq / g (EW = 523).

(Evaluation of oxidation resistance)
The electrolyte membranes of Examples 1 to 5 and Comparative Example 1 and the electrolyte materials of Example 6 and Comparative Example 2 were placed in 3% by mass hydrogen peroxide (Fe ²⁺ , 2 ppm) maintained at 90 ° C. for 40 minutes. The residual dry mass when immersed was measured and the residual rate was calculated. The results are shown in Table 1.

  As is clear from Table 1, the electrolyte membranes and electrolyte materials of the respective examples into which the antioxidant was introduced were compared with the fact that the vinyl monomers introduced by the corresponding electrolyte membranes and electrolyte materials of the comparative examples were almost eliminated. High mass retention was shown. In other words, it was found that it was excellent in oxidation resistance. In addition, although the ion exchange capacity (IEC) slightly decreases with the introduction of chloromethylstyrene, it is clear that the ion exchange capacity (IEC) is inferior to that of the electrolyte membrane and electrolyte material of the comparative example. It was found that a sufficient amount of graft chains could be introduced.

Claims (6)

Introducing a polymerization starting point into the substrate;
Starting from the polymerization initiation point, grafting a vinyl monomer containing a monomer represented by the following general formula (1);
A post-treatment step having a step of reacting an antioxidant having a functional group selected from an OH group, an amino group and an imino group in the molecular structure, and a step of reacting a sulfonating agent;
A method for producing an electrolyte material, comprising:

(In the formula (1), R is an alkylene group having one or more C; n is 1 or more; R ′ is hydrogen or an alkyl group having 1 to 4 C; X is halogen)   2. The method for producing an electrolyte material according to claim 1, wherein the vinyl monomer contains styrene and chloromethylstyrene which is a monomer described in the general formula (1). A treatment step comprising introducing a functional group selected from an OH group, an amino group and an imino group by reacting the functional group of an antioxidant having a molecular structure in the molecular structure; and introducing a proton conductive functional group The
A method for producing an electrolyte material, which is performed on a polymer material having an alkyl halide group.   The said antioxidant is a manufacturing method of the electrolyte material in any one of Claims 1-3 selected from an amine antioxidant and a phenolic antioxidant. A base material made of a polyolefin-based material in which part of hydrogen may be substituted with fluorine;
A side chain grafted to the substrate, which is a copolymer of styrene and halogenated methylstyrene,
The side chain reacts with the functional group of the antioxidant in which at least a part of the halogen moiety derived from the halogenated methylstyrene has a functional group selected from OH group, amino group and imino group in the molecular structure. And at least a part of hydrogen of the phenyl group derived from the styrene and the halogenated methylstyrene is substituted with a sulfo group.   The electrolyte material according to claim 5, wherein the base material is an ethylene-tetrafluoroethylene copolymer.