JP5049459B2 - Solid polymer electrolyte composite membrane obtained by impregnating polyacrylonitrile porous membrane with phosphoric acid group-containing unsaturated monomer (composition) and (co) polymerization and use thereof - Google Patents

Description

  The present invention relates to a solid polymer electrolyte composite membrane suitable for electrolyte membranes such as primary batteries, secondary batteries, fuel cells, display elements, various sensors, signal transmission media, solid capacitors, ion exchange membranes, etc. The present invention relates to a solid polymer electrolyte composite membrane exhibiting high proton conductivity over a wide temperature range and humidity range and its use.

  Polymers belonging to so-called cation exchange resins such as polystyrene sulfonic acid, polyvinyl sulfonic acid, perfluorosulfonic acid polymer, perfluorocarboxylic acid polymer [Polymer Preprints, Japan Vol. 42, No. 7, pp. 2490-2492 (1993), Polymer Preprints, Japan Vol. 43, No. 3, pp. 735-736 (1994), Polymer Preprints, Japan Vol. 42, No. 3, p. 730 (1993)] etc. Has been reported.

  In particular, a solid polymer material having a sulfonic acid group in the side chain has a property of binding firmly to a specific ion or selectively transmitting a cation or an anion. And is used for various applications such as electrodialysis membranes, diffusion dialysis membranes, and battery membranes. Above all, a fluoropolymer electrolyte membrane having a sulfonic acid group in the side chain of the perfluoro skeleton known by the trademark Nafion (manufactured by DuPont) is excellent in heat resistance and chemical resistance and can be used under severe conditions. It has been put to practical use as a durable electrolyte membrane. However, the fluorine-based electrolyte membrane as described above has a problem that it is very expensive.

  In contrast, JP-A-2003-86021 (Patent Document 1) discloses a phosphoric acid group-containing unsaturated monomer having one or more phosphate groups and one or more ethylenically unsaturated bonds in the molecule, and a molecule. A solid polymer electrolyte membrane comprising a copolymer of a sulfonic acid group-containing unsaturated monomer having one or more sulfonic acid groups and one or more ethylenically unsaturated bonds therein is proposed. The solid polymer electrolyte membrane of Patent Document 1 can be produced at a relatively low cost, and has a high conductivity, a low temperature dependency of conductivity, and excellent heat resistance and solvent resistance. It was in line with the solid polymer material.

  Patent Document 1 also describes a solid polymer electrolyte composite membrane comprising a phosphate group-containing polymer and a reinforcing sheet. A solid polymer electrolyte composite membrane using a reinforcing sheet has the advantage of being excellent in strength, heat resistance, chemical resistance and dimensional stability.

Japanese Patent Laid-Open No. 2003-86021

  Patent Document 1 describes a sheet (woven fabric, nonwoven fabric, and paper) made of a microporous resin film and inorganic fibers or organic fibers as a reinforcing sheet. However, a porous film made of polyethylene or the like conventionally used for a composite film has a problem of insufficient adhesion to a phosphate group-containing polymer.

  Accordingly, an object of the present invention is to include a phosphoric acid group-containing (co) polymer and a porous membrane excellent in adhesiveness with it, which can be produced at a relatively low cost, and has a high proton conductivity in a wide temperature range and humidity range. It is to provide a solid polymer electrolyte composite membrane having a property and its use.

  As a result of intensive studies in view of the above object, the present inventors have found that (1) the polyacrylonitrile porous membrane is excellent in adhesiveness with a (co) polymer containing a phosphate group, and (2) phosphorus It has been found that a solid polymer electrolyte composite membrane including an acid group-containing (co) polymer and a polyacrylonitrile porous membrane can be produced at a relatively low cost and has high proton conductivity in a wide temperature range and humidity range. I came up with it.

That is, the solid polymer electrolyte composite membrane of the present invention comprises (a) a phosphate group-containing unsaturated monomer having one or more phosphate groups and one or more ethylenically unsaturated bonds in the molecule, or (b) impregnating a microporous film formed from a polyacrylonitrile resin by a wet method with the phosphate group-containing unsaturated monomer and another unsaturated monomer copolymerizable therewith , and (co) polymerizing It is characterized by becoming.

The phosphate group-containing unsaturated monomer is represented by the following general formula (1):
(Wherein R ¹ is a hydrogen group or an alkyl group, R ² is a hydrogen group or a substituted or unsubstituted alkyl group, and n is an integer of 1 to 6). . R ¹ is preferably H or CH ₃ and R ² is preferably H, CH ₃ or CH ₂ Cl.

The other unsaturated monomer is at least one selected from the group consisting of one or more ethylenically unsaturated bonds in the molecule, a sulfonic acid group, a carboxylic acid group, an alcoholic hydroxyl group, an amino group, and a fluorine group. And at least one selected from the group consisting of (meth) acrylonitrile, (meth) acrylic acid esters, substituted or unsubstituted styrenes, vinyl chloride, and vinyl acetate. Is preferred.

The phosphate group-containing unsaturated monomer is represented by the following general formula (2):
(However, R ³ and R ⁶ are each independently a hydrogen group or an alkyl group, R ⁴ and R ⁵ are each independently a hydrogen group or a substituted or unsubstituted alkyl group, and k and p are each independently 1 to 1) It may contain a phosphoric acid group-containing diester unsaturated monomer represented by the following formula: Preferably R ³ and R ⁶ are each independently H or CH ₃ and R ⁴ and R ⁵ are each independently H, CH ₃ or CH ₂ Cl.

The solid polymer electrolyte composite membrane of the present invention may contain a phosphoric acid-modified epoxy resin. The phosphoric acid-modified epoxy resin has the following general formula (3):
(However, R ⁷ and R ⁹ each represent a substituted or unsubstituted alkylene group, R ⁸ represents hydrogen, a halogen atom or a substituted or unsubstituted alkyl group, and m represents the degree of polymerization. According to the general formula (3) The compound represented may be a copolymer containing two or more structural units or a mixture of two or more structural units.) The epoxy ring of the novolak epoxy resin represented by Modified by introducing an acid group, wherein a phosphate group and a hydroxyl group coexist in one molecule, and / or the following general formula (4):
(However, R ¹⁰ represents a residue derived from bisphenols, or a substituted or unsubstituted alkylene group having 1 to 4 carbon atoms, m ′ represents the degree of polymerization. The compound represented by the general formula (4) is 2 It may be a cocondensate containing two or more kinds of structural units or a mixture of two or more kinds of structural units.) At least partially introducing a phosphate group into the epoxy ring of the bisphenol type epoxy resin represented by It is preferable that the phosphoric acid group and the hydroxyl group coexist in one molecule.

The polyacrylonitrile porous membrane is preferably at least one selected from the group consisting of a microporous film formed from a polyacrylonitrile resin by a wet method, and a paper, woven fabric, and non-woven fabric made of polyacrylonitrile fiber. The water permeability of the polyacrylonitrile porous membrane made of the microporous film is preferably 1 to 500 m ³ / m ² · day · atm. The polyacrylonitrile porous membrane made of paper or non-woven fabric is preferably continuously made by a wet process. The polyacrylonitrile porous membrane made of paper or non-woven fabric is composed of a composite of short fibers obtained by spinning polyacrylonitrile long fibers obtained by spinning and fibrillated fibers obtained by beating the short fibers. Is preferred.

The polyacrylonitrile porous membrane, the polyacrylonitrile microporous film is composed of (a) an acrylonitrile homopolymer, (b) a copolymer of acrylonitrile and a monomer copolymerizable with acrylonitrile, or (c) a mixture thereof. Is preferred. Monomers copolymerizable with acrylonitrile include alkyl (meth) acrylates having 4 or less carbon atoms in the alkyl group; (meth) acrylic acid; hydroxyethyl (meth) acrylate; bromoethyl (meth) acrylate; methacrylonitrile Itaconic acid; (Meth) acrylic acid amide; Fatty acid vinyl; Vinyl pyrrolidone; Methyl vinyl ketone; Halogenated vinyl; Halogenated vinylidene; Styrene; Butadiene; Vinyl pyridine: Methallylsulfonic acid, allylsulfonic acid, p-styrenesulfonic acid And at least one selected from the group consisting of olefins.

  The solid polymer electrolyte composite membrane of the present invention is useful for fuel cell applications.

The polyacrylonitrile (PAN) porous membrane has good affinity with a phosphate group-containing (co) polymer, and the present invention has a solid polymer electrolyte comprising a phosphate group-containing (co) polymer supported on the PAN porous membrane. This composite membrane is excellent in adhesion between the solid polymer electrolyte and the porous membrane. The PAN porous membrane is also excellent in heat resistance and strength. For this reason, the composite membrane of the present invention is expected to exhibit excellent durability when used as an electrolyte membrane for batteries. The solid polymer electrolyte composite membrane of the present invention also has an excellent proton with an electrical conductivity on the order of 10 ⁻³ to 10 ⁻² S · cm ⁻¹ under a relative humidity of 90% and a temperature of 30 to 80 ° C. It has conductivity and the temperature dependence of proton conductivity is small.

  The solid polymer electrolyte composite membrane of the present invention having such characteristics includes an electrolyte membrane for a primary battery, an electrolyte membrane for a secondary battery, an electrolyte membrane for a fuel cell, a display element membrane, various sensor membranes, a signal transmission medium membrane, a solid membrane It can be suitably used for capacitor membranes, ion exchange membranes, and the like.

[1] Phosphoric acid group-containing (co) polymer The phosphoric acid group-containing (co) polymer is a polymer of phosphoric acid group-containing unsaturated monomers described below, and / or a phosphoric acid group-containing unsaturated monomer. And a copolymer of another unsaturated monomer copolymerizable therewith as a main component.
(1) Phosphoric acid group-containing unsaturated monomer The phosphoric acid group-containing unsaturated monomer is represented by the following general formula (1):
(Wherein R ¹ is hydrogen or an alkyl group, R ² is hydrogen or a substituted or unsubstituted alkyl group, and n is an integer of 1 to 6). R ¹ is preferably H or CH ₃ and R ² is preferably H, CH ₃ or CH ₂ Cl.

  Tables 1 and 2 show the structural formulas and physical properties of representative ones of the phosphate group-containing unsaturated monomers represented by the general formula (1) (phosphate group-containing unsaturated monomers (I)), respectively. Show. These monomers are sold by Unichemical Corporation under the trade name Phosmer (registered trademark). However, the phosphate group-containing unsaturated monomer that can be used in the present invention is not limited to these. The phosphate group-containing unsaturated monomer (I) can be used alone, but two or more kinds may be used in combination.

The phosphoric acid group may be dissociated or may form a complex salt. When forming a complex salt, in order to neutralize the charge, for example, ammonium ions containing mono-, di- or tri-alkyl groups such as primary, secondary, tertiary or quaternary alkyl groups, allyl groups, aralkyl groups, etc. It is preferable to form a complex salt with an alkanolamine residue, particularly N ⁺ R ¹¹ _4-f (OH) _f (where R ¹¹ is an alkyl group having 1 to 18 carbon atoms, an aromatic group having 6 to 12 carbon atoms and carbon). It represents at least one selected from the group consisting of alicyclic groups of formula 6 to 12, and f represents a positive integer of 1 to 3).

As the phosphate group-containing unsaturated monomer, the following general formula (2):
(However, R ³ and R ⁶ are each independently a hydrogen group or an alkyl group, R ⁴ and R ⁵ are each independently a hydrogen group or a substituted or unsubstituted alkyl group, and k and p are each independently 1 to 1) The phosphoric acid group-containing diester unsaturated monomer (phosphoric acid group-containing unsaturated monomer (II)) represented by the following general formula (5):
(However, R ¹² and R ¹⁵ are each independently a hydrogen group or an alkyl group, R ¹³ and R ¹⁴ are each independently a hydrogen group or a substituted or unsubstituted alkyl group, and r and s are each independently 1 to 1) A pyrophosphate group-containing unsaturated monomer represented by (phosphate group-containing unsaturated monomer (III)), and the following general formula (6):
(However, R ¹⁶ , R ¹⁹ and R ²¹ are each independently a hydrogen group or an alkyl group, R ¹⁷ , R ¹⁸ and R ²⁰ are each independently a hydrogen group or a substituted or unsubstituted alkyl group, and x, y And z are each independently an integer of 1 to 6.) It is also possible to use a phosphate group-containing unsaturated monomer (IV) represented by:

  As the phosphate group-containing unsaturated monomer (II), di (methacryloyloxyethyl) phosphate and di (acryloyloxyethyl) phosphate are preferable. As the phosphate group-containing unsaturated monomer (III), di (methacryloyloxyethyl) acid pyrophosphate and di (acryloyloxyethyl) acid pyrophosphate are preferable.

  The phosphoric acid group-containing unsaturated monomer (I) has excellent proton conductivity, and the phosphoric acid group-containing unsaturated monomers (II) to (IV) have a crosslinking action and excellent film forming properties. Therefore, the phosphate group-containing unsaturated monomer (I) and at least one selected from the group consisting of the phosphate group-containing unsaturated monomers (II) to (IV) may be used in combination. Such a combination improves the balance of proton conductivity, solvent resistance and membrane strength of the composite membrane. Among them, it is preferable to use the phosphate group-containing unsaturated monomers (I) and (II) in combination. When the phosphate group-containing unsaturated monomer (I) and at least one selected from the group consisting of the phosphate group-containing unsaturated monomers (II) to (IV) are used in combination, the formula [phosphate group Containing molar ratio represented by [containing unsaturated monomer (I)] / [total of phosphate group-containing unsaturated monomers (II) to (IV)] is 1 / 0.05 to 1/2. preferable.

  When the phosphoric acid group-containing (co) polymer includes a phosphoric acid group-containing unsaturated monomer component as described above, a high water retention capability can be imparted to the solid polymer electrolyte, and a composite film having high conductivity can be obtained. can get.

(2) Other unsaturated monomers that can be copolymerized Other unsaturated monomers that can be copolymerized with the above phosphate group-containing unsaturated monomers include the following two groups (a) unsaturated monomers A and ( b) It can be roughly divided into unsaturated monomers B.
(a) Unsaturated monomer A
The unsaturated monomer A is a compound having in the molecule at least one functional group shown below and at least one ethylenically unsaturated bond. Examples of the functional group include an acidic group and an amino group (including those having an amide group). The acidic group is preferably at least one selected from the group consisting of a sulfonic acid group, a carboxylic acid group and an alcoholic hydroxyl group. Examples of the skeleton having an ethylenically unsaturated bond include a (meth) acrylate skeleton and a (meth) allyl ester skeleton.

(i) Sulfonic acid group-containing unsaturated monomer Examples of the unsaturated monomer-containing unsaturated monomer include the following general formula (7):
(Wherein R ²² is a hydrogen group or a methyl group), a compound represented by the following general formula (8):
Wherein R ²³ is a hydrogen group or a methyl group, and Y ¹ is a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms or an arylene group having 6 to 12 carbon atoms, and the following: General formula (9):
(Wherein R ²⁴ is a hydrogen group or a methyl group, X ¹ is an —O— group or an —NH— group, and Y ² is a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms or 6 to 12 carbon atoms. And at least one selected from the group consisting of compounds represented by formula (1):

  Examples of the sulfonic acid group-containing unsaturated monomer represented by any one of the general formulas (7) to (9) include allyl sulfonic acid, methallyl sulfonic acid, and vinyl sulfone. Acid, p-styrenesulfonic acid, (meth) acrylic acid butyl-4-sulfonic acid, (meth) acrylooxybenzenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid (tertiary butylacrylamidesulfonic acid), etc. Can be mentioned. Preferred are vinyl sulfonic acid, p-styrene sulfonic acid and tertiary butyl acrylamide sulfonic acid. However, allyl sulfonic acid and methallyl sulfonic acid have a degradative chain transfer because the allyl group causes a degradative chain transfer. preferable. Specifically, the total of the phosphate group-containing unsaturated monomer and other unsaturated monomers is 100% by mass, and the amount used is at most about 10% by mass.

  The sulfonic acid group may be dissociated or may form a complex salt. When forming a complex salt, it is preferable to form a complex salt with an ammonium ion, an amine residue or an alkali metal as described above for the unsaturated monomer containing a phosphorus acid residue.

(ii) Unsaturated monomer containing a carboxylic acid group Examples of unsaturated monomers containing a carboxylic acid group include (meth) acrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, maleic acid. An acid anhydride etc. are mentioned. These can be used alone, but two or more may be used in combination.

(iii) Unsaturated monomer containing alcoholic hydroxyl group The unsaturated monomer containing alcoholic hydroxyl group includes glycerol dimethacrylate [for example, “Blemmer GMR”, “Blemmer GMR-R” (Nippon Yushi). Etc.)], glycerol methacrylate acrylate [e.g., trade name "Blemmer GAM", "Blenmer GAM-R" (manufactured by Nippon Oil & Fats Co., Ltd.)], 1,6-hexanediol diglycidyl ether acrylate [e.g. Product name “NK Oligo EA-5521” (manufactured by Shin-Nakamura Chemical Co., Ltd.), etc.], 1,4-butanediol diglycidyl ether acrylate [eg, product name “NK Oligo EA-5520” (Shin Nakamura Chemical Co., Ltd.) Etc.)], bisphenol A type epoxy acrylate [for example, “NK Oligo EA-1020” (manufactured by Shin-Nakamura Chemical Co., Ltd.)], and 2-hydroxy (meta ) Acrylates (for example, 2-hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, etc.).

  Among them, glycerol dimethacrylate, glycerol methacrylate acrylate, 1,6-hexanediol diglycidyl ether acrylate, 1,4-butanediol diglycidyl ether acrylate and bisphenol A type epoxy acrylate have two ethylenically unsaturated groups in the molecule. It is preferable from the viewpoint.

  These alcoholic hydroxyl group-containing unsaturated monomers further improve the conductivity and strength of the composite film by converting these hydroxyl groups into phosphoric acid monoesters. In particular, a monoesterified monomer of an alcoholic hydroxyl group-containing unsaturated monomer having two ethylenically unsaturated groups in the molecule has good crosslinking efficiency during polymerization.

(iv) Amino group-containing unsaturated monomer The amino group-containing unsaturated monomer is not particularly limited as long as it has at least one substituted or unsubstituted amino group and one or more ethylenically unsaturated bonds in the molecule. There is no. As an amino group-containing unsaturated monomer, for example, (iv-1) the following general formula (10):
(However, R ²⁵ is a hydrogen group or a methyl group, R ²⁶ and R ²⁷ are each independently a hydrogen group, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and X ² is —O -Group or -NH- group, and Y ³ is a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms or a substituted or unsubstituted arylene group having 6 to 16 carbon atoms.) (iv-2) The following general formula (11):
Wherein R ²⁸ is a hydrogen group or a methyl group, and R ²⁹ and R ³⁰ are each independently a hydrogen group, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 10 carbon atoms. Compound (iv-3) The following general formula (12):
(However, R ³¹ is a hydrogen group or a methyl group, R ³² and R ³³ are each independently a hydrogen group, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and Y ⁴ is substituted or An unsubstituted alkylene group having 1 to 6 carbon atoms or a substituted or unsubstituted arylene group having 6 to 16 carbon atoms.) (Iv-4) the following general formula (13):
(However, R ³⁴ is a hydrogen group or a methyl group, and R ³⁵ and R ³⁶ are each independently a hydrogen group, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 10 carbon atoms.) Compound (iv-5) The following general formula (14):
(However, R ³⁷ and R ³⁸ are each independently a hydrogen group or a methyl group, R ³⁹ is a hydrogen group, an alkyl group having 1 to 4 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and Y ⁵ and Y ⁶ Each independently represents a substituted or unsubstituted alkylene group having 1 to 6 carbon atoms or a substituted or unsubstituted arylene group having 6 to 16 carbon atoms, and (iv-6) one or more And at least one selected from the group consisting of heterocyclic amine compounds having a vinyl group.

  Examples of the amino group-containing unsaturated monomer represented by the above formula (10) include N, N-dimethylaminomethyl (meth) acrylate, N, N-diethylaminomethyl (meth) acrylate, and N, N-dipropylamino. Methyl (meth) acrylate, N, N-dibutylaminomethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dipropylaminoethyl ( (Meth) acrylate, N, N-dibutylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, N, N-dipropylaminopropyl (meth) Acrylate, N, N-Dibutylaminopropyl (meth) acrylate, N, N-dimethylaminobutyl (meth) acrylate, N, N-diethyl Minobutyl (meth) acrylate, N, N-dipropylaminobutyl (meth) acrylate, N, N-dibutylaminobutyl (meth) acrylate, N, N-dimethylaminomethyl (meth) acrylamide, N, N-diethylaminomethyl ( (Meth) acrylamide, N, N-dipropylaminomethyl (meth) acrylamide, N, N-dibutylaminomethyl (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) Acrylamide, N, N-dipropylaminoethyl (meth) acrylamide, N, N-dibutylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-diethylaminopropyl (meth) acrylamide, N, N-dipropylaminopropyl (meth) acrylamide, N, N-dibutylamino Propyl (meth) acrylamide, N, N-dimethylaminobutyl (meth) acrylamide, N, N-diethylaminobutyl (meth) acrylamide, N, N-dipropylaminobutyl (meth) acrylamide, N, N-dibutylaminobutyl ( And (meth) acrylamide.

  Examples of the amino group-containing unsaturated monomer represented by the above formula (11) include vinylamine, N-vinyldimethylamine, N-vinyldiethylamine, N-vinyldiphenylamine and the like.

  Examples of the amino group-containing unsaturated monomer represented by the above formula (12) include allylamine, N, N-dimethyl-p-aminostyrene, N, N-diethyl-p-aminostyrene, dimethyl (p-vinylbenzyl). ) Amine, diethyl (p-vinylbenzyl) amine, dimethyl (p-vinylphenethyl) amine, diethyl (p-vinylphenethyl) amine, dimethyl (p-vinylbenzyloxymethyl) amine, dimethyl [2- (p-vinylbenzyl) Oxy) ethyl] amine, diethyl (p-vinylbenzyloxymethyl) amine, diethyl [2- (p-vinylbenzyloxy) ethyl] amine, dimethyl (p-vinylphenethyloxymethyl) amine, dimethyl [2- (p- Vinylphenethyloxy) ethyl] amine, diethyl (p-vinylphenethyloxymethyl) amine, diethyl [2- (p-vinylphenethyloxy) Ii) ethyl] amine and the like.

  Examples of the amino group-containing unsaturated monomer represented by the above formula (13) include acrylamide, methacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide and the like.

  Examples of the amino group-containing unsaturated monomer represented by the above formula (14) include diallylmethylamine.

  Examples of heterocyclic amine compounds having one or more vinyl groups include 2-vinylpyridine, 3-vinylpyridine, 4-vinylpyridine, 1-vinylimidazole, 2-vinylimidazole, 4-vinylimidazole, 5-vinylimidazole, 1-vinylpyrazole, 3-vinylpyrazole, 4-vinylpyrazole, 1-vinyltriazole, 2-vinylpyrimidine, 4-vinylpyrimidine, 5-vinylpyrimidine, 2-vinylpyrazine, 3-vinylpyridazine, 4-vinylpyridazine, 2-vinyltriazine, N-vinylpyrrole, N-vinylindole, N-vinylcarbazole, N-vinylpyrrolidone, N-vinyl-ε-caprolactam, N-vinylsuccinimide, N-vinylglutarimide, N-vinylphthalimide, etc. Can be mentioned.

  Among them, the amino group-containing unsaturated monomer is preferably one represented by the above formulas (10), (12) and (14) from the viewpoint of improving the solvent resistance of the solid polymer electrolyte composite membrane, What is represented by the said Formula (10) is more preferable.

(b) Unsaturated monomer B
Unsaturated monomer B includes all unsaturated monomers other than those described in (a) that are not gaseous at room temperature and have one or more ethylenically unsaturated bonds in the molecule. (Meth) acrylonitrile; (meth) acrylic esters such as methyl (meth) acrylate, ethyl (meth) acrylate, alkyl (meth) acrylate; substituted or unsubstituted styrenes; vinyls such as vinyl chloride and vinyl acetate Preferably used. Ethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate and divinylbenzene containing a plurality of ethylenically unsaturated bonds in one molecule are also used for the purpose of improving the solvent resistance of the copolymer. The

  Moreover, the heat resistance and water resistance of a solid polymer electrolyte composite membrane are improved by including a fluorine group-containing unsaturated monomer as a copolymerization component. Fluorine group-containing unsaturated monomers are (i) fluorine group-containing (meth) acrylic acid esters having at least one fluorine group, and (b) fluorine group-containing (meth) acrylic having at least one fluorine group. Acids, (c) a fluorine-containing alkyl group having at least one fluorine group and / or a fluorine-containing olefinically unsaturated monomer having at least one fluorine group and one ethylenically unsaturated bond, And (d) at least one selected from the group consisting of a fluorine group-containing diene unsaturated monomer having a fluorine group-containing alkylene group containing at least one fluorine group and two ethylenically unsaturated bonds. Preferably there is.

As fluorine group-containing (meth) acrylic acid esters, the following general formula (15):
Wherein X ³ is a hydrogen group, a fluorine group, a fluorine group-containing methyl group or methyl group having at least one fluorine group, and R ⁴⁰ is a fluorine group-containing alkyl group or alkyl group containing at least one fluorine group. Is preferred.

In the general formula (15), R ⁴⁰ preferably has 1 to 10 carbon atoms, and more preferably 1 to 5 carbon atoms. When R ⁴⁰ is a fluorine group-containing alkyl group containing a fluorine group and has 2 or more carbon atoms, it is preferable that all of the hydrogen groups of the terminal methyl group are substituted with fluorine groups. R ⁴⁰ may be a linear structure or a branched structure. R ⁴⁰ may have a halogen atom other than fluorine. R ⁴⁰ may have a hetero atom. Examples of the hetero atom include an etheric oxygen atom and a thioetheric sulfur atom contained between carbon-carbon bonds in R ⁴⁰ .

  Fluorine group-containing (meth) acrylic esters represented by the general formula (15) include 2,2,2-trifluoroethyl acrylate, 2,2,2-trifluoroethyl methacrylate, tertiary butyl- Examples include α- (trifluoromethyl) acrylate, trifluoroethyl-α- (trifluoromethyl) acrylate, and perfluorooctylethyl (meth) acrylate. Among them, as the fluorine group-containing (meth) acrylic acid esters, 2,2,2-trifluoroethyl methacrylate and tertiary butyl-α- (trifluoromethyl) acrylate are preferable.

As fluorine group-containing (meth) acrylic acids, the following general formula (16):
(Wherein X ⁴ is a fluorine group-containing methyl group or fluorine group having at least one fluorine group) is preferred. In the general formula (16), X ⁴ is more preferably a perfluoromethyl group or a fluorine group. As the fluorine group-containing (meth) acrylic acid, α- (trifluoromethyl) acrylic acid is particularly preferable.

The fluorine group-containing olefinically unsaturated monomer is represented by the following general formula (17):
(Wherein Rf ¹ is a fluorine group-containing alkyl group containing at least one fluorine group, and X ⁵ , X ⁶ and X ⁷ are each independently a hydrogen group or a fluorine group) or the following general formula (18) :
(However, X ⁸ , X ⁹ and X ¹⁰ are each independently a fluorine group-containing methyl group or fluorine group having at least one fluorine group, and X ¹¹ is a fluorine group, other halogens, or at least one fluorine group. Preferably a fluorine group-containing methyl group, an alkoxy group, a fluorine group-containing alkoxy group, an alkyl group or a hydrogen group.

The fluorine group-containing alkyl group Rf ¹ containing a fluorine group in the general formula (17) is preferably a perfluoroalkyl group. Rf ¹ preferably has 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms. Rf ¹ may be a linear structure or a branched structure, but is preferably a linear structure. Rf ¹ may have a halogen atom other than fluorine. Rf ¹ may have a hetero atom. Examples of the hetero atom include an etheric oxygen atom and a thioetheric sulfur atom contained between carbon-carbon bonds in Rf ¹ .

As the fluorine group-containing olefinically unsaturated monomer represented by the general formula (17), the following general formula (19):
(Wherein Rf ¹ is the same as that in the above formula (17)) is more preferable.

  The fluorine group-containing olefinically unsaturated monomer represented by the general formula (19) includes (perfluorobutyl) ethylene, (perfluorohexyl) ethylene, (perfluorooctyl) ethylene, and (perfluorodecyl) ethylene. Etc. Of these, (perfluorobutyl) ethylene, (perfluorohexyl) ethylene and (perfluorooctyl) ethylene are preferable as the fluorine group-containing olefinic unsaturated monomer.

X ⁸ , X ⁹ and X ^{10 in the} general formula (18) are preferably a perfluoromethyl group or a fluorine group. When X ¹¹ in the general formula (18) is an alkyl group, an alkoxy group, or a fluorine group-containing alkoxy group, the carbon number thereof is preferably 1 to 10. Examples of the fluorine-containing olefinically unsaturated monomer represented by the general formula (18) include hexafluoropropene, chlorotrifluoroethylene, 1-methoxy- (perfluoro-2-methyl-1-propene), and the like. Can be mentioned.

As the fluorine group-containing diene unsaturated monomer, the following general formula (20):
(However, Rf ² is a fluorine group-containing alkylene group containing at least one fluorine group, and X ¹² , X ¹³ , X ¹⁴ , X ¹⁵ , X ¹⁶ and X ¹⁷ are each independently a hydrogen group or a fluorine group. .) Are preferred.

The fluorine group-containing alkylene group Rf ² containing at least one fluorine group in the general formula (20) is preferably a perfluoroalkylene group. Rf ² preferably has 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms. Rf ² may be a linear structure or a branched structure, but is preferably a linear structure. Rf ² may have a halogen atom other than fluorine. Rf ² may have a hetero atom and / or a hetero atom group. The hetero atom, carbon in Rf ² - etheric oxygen atoms contained in the carbon-carbon bond, and the like thioether sulfur atom. Examples of the hetero atom group include an ester bond.

Examples of the fluorine-containing olefinically unsaturated monomer represented by the general formula (20) include the following general formula (21):
(Wherein Rf ² is the same as the above formula (20)) is more preferable.

  Examples of the fluorine-containing diene unsaturated monomer represented by the general formula (21) include 1,4-divinyl (perfluorobutylene) (also known as 1,4-divinyloctafluorobutane), 1,6- Divinyl (perfluorohexylene) (alias: 1,6-divinyldodecafluorohexane) and 1,8-divinyl (perfluorooctylene) (alias: 1,8-divinylhexadecafluorooctane) are preferred.

  Each of the four types of fluorine-containing unsaturated monomers can be used alone, but two or more types may be used in combination. When using 2 or more types together, for example, fluorine group-containing olefinic unsaturated monomer and / or fluorine group-containing diene unsaturated monomer, fluorine group-containing (meth) acrylic acid esters and / or fluorine group-containing The composition etc. which mixed (meth) acrylic acid can be mentioned.

(3) Ratio of use of each unsaturated monomer The mass ratio (1) / (2) between the phosphate group-containing unsaturated monomer (1) and the other unsaturated monomer (2) is 100 It is preferably in the range of / 0 to 20/80, and more preferably (1) / (2) = 90/10 to 40/60. In addition, among other unsaturated monomers (2), the mass ratio of unsaturated monomer A containing a functional group to other unsaturated monomers B is an unfavorable effect on proton conductivity. The unsaturated monomer A / unsaturated monomer B is preferably in the range of 100/0 to 50/50 so that the saturated monomer (a) becomes dominant. Therefore, especially when using a sulfonic acid group-containing unsaturated monomer as the unsaturated monomer A containing acid groups, the mass of the phosphoric acid group-containing unsaturated monomer / sulfonic acid group-containing unsaturated monomer The ratio is 100/0 to 20/80, preferably 90/10 to 40/60, and the mass ratio of the sulfonic acid group-containing unsaturated monomer / functional group-free unsaturated monomer is 100/0 to 50 / 50.

(4) Phosphoric acid-modified epoxy resin The phosphoric acid group-containing (co) polymer may contain a phosphoric acid-modified epoxy resin, whereby the phosphoric acid group-containing (co) polymer and the polyacrylonitrile (PAN) porous membrane Adhesion is improved. In this specification, the term “phosphoric acid-modified epoxy resin” means a resin that has been modified by introducing a phosphoric acid group at least partially into the epoxy ring of the epoxy resin. There is no particular limitation on the epoxy resin that is the base of the phosphoric acid-modified epoxy resin. For example, a novolak type epoxy resin such as a phenol novolak type or a cresol novolak type; a bisphenol type epoxy resin such as a bisphenol A type or a bisphenol F type may be used. it can. In order to introduce a phosphate group at least partially into the epoxy ring of the epoxy resin, for example, a method described in JP-A-2001-151854, JP-A-2002-327040, or the like can be employed. As described in these known documents.

As the phosphoric acid-modified epoxy resin, the following general formula (3):
(However, R ⁷ and R ⁹ each represent a substituted or unsubstituted alkylene group, R ⁸ represents hydrogen, a halogen atom or a substituted or unsubstituted alkyl group, and m represents the degree of polymerization. According to the general formula (3) The compound represented may be a copolymer containing two or more structural units or a mixture of two or more structural units.) The epoxy ring of the novolak epoxy resin represented by Those modified by introducing an acid group and having a phosphate group and a hydroxyl group coexisting in one molecule (hereinafter referred to as “CEP”) are preferred, and the presumed structure thereof is represented by the following general formula (22):
[However, in the general formula (22), X ¹⁸ and Y ⁷ are each independently —OH group, —OP (O) (OH) ₂ group or —OP (O) (OH) —OP (O ) (OH) ₂ group, R ⁷ , R ⁸ and R ⁹ represent the same substituent as in the general formula (3), and m represents the degree of polymerization. However, (total number of -OP (O) (OH) ₂ groups) / (total number of substituents X ¹⁸ and Y ⁷ ) = 0.3 to 0.75 (provided that -OP (O) (OH) -OP (O) (OH) ₂ groups are converted into two -OP (O) (OH) ₂ groups). ].

As another preferred phosphoric acid-modified epoxy resin, the following general formula (4):
(However, R ¹⁰ represents a residue derived from bisphenols, or a substituted or unsubstituted alkylene group having 1 to 4 carbon atoms, m ′ represents the degree of polymerization. The compound represented by the general formula (4) is 2 It may be a cocondensate containing two or more kinds of structural units or a mixture of two or more kinds of structural units.) At least partially introducing a phosphate group into the epoxy ring of the bisphenol type epoxy resin represented by (BEP) in which a phosphate group and a hydroxyl group are allowed to coexist in one molecule, and its estimated structure is represented by the following general formula (23):
[In the general formula (23), V, W, X ¹⁸ , Y ⁷ and Z are each independently —OH group, —OP (O) (OH) ₂ group or —OP (O) (OH) —OP ( O) (OH) ₂ group, R ¹⁰ represents the same substituent as in the general formula (4), and m ′ represents the degree of polymerization. However, (total number of -OP (O) (OH) ₂ groups) / (total number of substituents V, W, X ¹⁸ , Y ⁷ and Z) = 1.2 / (n + 4) to 3 / (n + 4) ( However, -OP (O) (OH) -OP (O) (OH) ₂ groups are converted into ₂ -OP (O) (OH) ₂ groups). ].

  The phosphoric acid-modified epoxy resin is self-condensed and cured when heated to 120 ° C. or higher. The heating time for curing is preferably 5 to 60 minutes. The phosphoric acid-modified epoxy resin also crosslinks with the phosphoric acid group-containing (co) polymer by association between phosphoric acid groups. There is no restriction | limiting in particular in the mixture ratio of the phosphoric acid modified epoxy resin in a phosphoric acid group containing (co) polymer, What is necessary is just to set suitably according to the adhesiveness calculated | required for a phosphoric acid group containing (co) polymer. Usually, the mass ratio represented by the formula [(phosphate group-containing unsaturated monomer + other unsaturated monomer) / (phosphoric acid-modified epoxy resin)] is in the range of 100/0 to 70/30. And is more preferably in the range of 100/0 to 80/20.

(5) Unsaturated oligomer that can be copolymerized The phosphoric acid group-containing (co) polymer may contain, as a copolymerization component, an unsaturated oligomer that can be copolymerized with the phosphate group-containing unsaturated monomer. Examples of such unsaturated oligomers include conjugated diene liquid oligomers. As the conjugated diene-based liquid oligomer, at least one selected from the group consisting of a butadiene oligomer, an isoprene oligomer and derivatives thereof each having at least two ethylenically unsaturated bonds in the molecule is preferable. As the conjugated diene liquid oligomer, the following general formula (24):
(However, R ⁴¹ and R ⁴² are each independently a hydrocarbon group having one or more ethylenically unsaturated bonds and may have other atomic groups, and R ⁴³ and R ⁴⁴ are each independently hydrogen. And a methyl group, and at least one of R ⁴³ and R ⁴⁴ is a hydrogen group, and t represents the degree of polymerization. However, the conjugated diene-based liquid oligomer is not limited to those in which the conjugated diene unit in the polymer chain is a 1,2-bond as shown in the formula (24), and the conjugated diene unit is a 1,4-bond. There may be something.

R ⁴¹ and R ⁴² are not particularly limited as long as they are hydrocarbon groups which have one or more ethylenically unsaturated bonds and may have other atomic groups. Examples of the other atomic group that R ⁴¹ and R ⁴² may have include at least one selected from the group consisting of a urethane bond, an ester bond, an ether bond, an isocyanate group, a hydroxyl group, a carboxyl group, and an alkoxy group. Specific examples of R ⁴¹ and R ⁴² include a (meth) acryl group.

[2] Polyacrylonitrile porous membrane The solid polymer electrolyte composite membrane of the present invention has a polyacrylonitrile (PAN) porous membrane as a support. Examples of the PAN porous membrane include a PAN microporous film formed from a PAN resin by a wet method, or paper, woven fabric, or nonwoven fabric made of PAN fibers.

(1) Polyacrylonitrile resin
The PAN resin constituting the PAN porous membrane is not limited to a homopolymer, and may be a copolymer including a monomer copolymerizable with acrylonitrile. Examples of such monomers include alkyl (meth) acrylates having 4 or less carbon atoms in the alkyl group (for example, methyl (meth) acrylate, ethyl (meth) acrylate); (meth) acrylic acid; (meth) acrylic acid Hydroxyethyl; bromoethyl (meth) acrylate; methacrylonitrile; itaconic acid; (meth) acrylic acid amide; fatty acid vinyl (eg, vinyl acetate, vinyl propionate, etc.); vinyl pyrrolidone; methyl vinyl ketone; Vinyl, vinyl bromide, vinyl fluoride, etc.); vinylidene halides (eg, vinylidene chloride, vinylidene bromide, etc.); styrene; butadiene; vinyl pyridine; methallyl sulfonic acid, allyl sulfonic acid, p-styrene sulfonic acid , and these Salts of olefins (eg ethylene, Pyrene, etc.) and the like. When the PAN resin is a copolymer, the content of other monomers copolymerized with acrylonitrile is preferably 30% by mass or less, more preferably 15% by mass or less, based on 100% by mass of the entire copolymer.

  The PAN resin is not limited to a single resin component, and may be a plurality of resin components. As a combination of resin components, in addition to a mixture of a homopolymer and a copolymer, a mixture of copolymers having different copolymerization compositions, etc., other resins were added to one or more PAN resins as long as the properties are not impaired. Things. As such other resins, polysulfone, polyethersulfone, polyallylsulfone, polyimide, cellulose acetate, other cellulose derivatives, vinyl chloride, polyester, polyvinylidene fluoride, polyurethane and the like are preferable. When other resins are contained, the proportion is preferably 50% by mass or less, based on 100% by mass of the entire PAN porous membrane. Therefore, unless otherwise specified, the term “PAN resin” used in the present specification should be understood to include not only a simple substance of PAN but also a composition comprising PAN + other resin.

  The PAN homopolymer or copolymer can be prepared by a known polymerization method such as solution polymerization, emulsion polymerization or suspension polymerization. For example, JP-A-62-106906 describes a method for preparing a PAN resin by radical suspension polymerization.

(2) PAN porous membrane and production procedure thereof PAN microporous film, PAN paper / nonwoven fabric, PAN woven fabric and procedures for producing them will be described below.
(a) PAN microporous film
The water permeability of the PAN microporous film is preferably 1 to 500 m ³ / m ² · day · atm, more preferably 10 to 50 m ³ / m ² · day · atm. Here, the amount of water permeated per unit time, unit membrane area, and unit pressure (unit transmembrane pressure difference) by passing ultrafiltered water at 25 ° C through a circular sample (diameter: 50 mm) of PAN microporous film. Calculates the permeation speed and is expressed in units of m ³ / m ² · day · atm. The thickness of the PAN microporous film is preferably 5 to 100 μm, and more preferably 10 to 70 μm.

  A procedure for producing a PAN microporous film will be described below. First, PAN resin is dissolved in an appropriate solvent to prepare a PAN resin solution. When preparing the PAN resin solution, it may be heated as necessary. Although not limited, the intrinsic viscosity of the PAN resin used for the PAN microporous film is preferably 0.4 or more and less than 2. When the intrinsic viscosity is less than 0.4, the strength of the film is weak. On the other hand, if it is 2 or more, the solubility in a solvent is poor, the solution viscosity is high, and the film formability is poor. Various additives such as antioxidants, plasticizers, UV absorbers, antiblocking agents, antistatic agents, surfactants, pigments, dyes, lubricants, inorganic fillers and the like are added to the PAN resin solution according to the present invention. Can be added within a range that does not impair the effect. For example, finely divided silicic acid can be added as a pore forming agent.

  Solvents include propylene carbonate, ethylene carbonate, acetonitrile, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, γ-butyrolactone, ethylene carbonate, N-methyl-2-pyrrolidone, 2-pyrrolidone, hexamethylene Examples thereof include organic solvents such as phosphoamides, concentrated aqueous solutions of zinc chloride, nitric acid, or sodium thiocyanate.

  Although the dissolution method is not particularly limited, a mixer such as a stirrer or a Hensyl mixer may be used, and the mixture may be uniformly kneaded in the extruder. Although there is no restriction | limiting in particular in the mixture ratio of the PAN resin and solvent in a PAN resin solution, It is preferable that PAN resin is 5-35 mass% when the sum total of both is 100 mass%, and is 10-30 mass%. Is more preferable.

  By immersing the solution extruded from the die in a coagulation bath, a film-like molded product in which the PAN resin and the solvent are phase-separated is formed. As the solvent used in the coagulation bath, a water dilution of the solvent used in the PAN resin solution is generally used. The temperature of the coagulation bath is preferably −10 to 90 ° C., more preferably 0 to 70 ° C. The film-like molded product obtained as described above is a porous body containing a large number of micropores formed during solidification.

  The film-like molded product formed as described above is stretched. By stretching the film-like molded product, the micropores are enlarged. Although it is not limited, it is preferable to perform extending | stretching in the hot water adjusted to the temperature range of 80-100 degreeC, and, thereby, can stabilize a porous membrane structure. Stretching is performed by heating the film-shaped molded article, and then by a usual tenter method, roll method, inflation method, rolling method, or a combination of these methods. The stretching may be uniaxial stretching or biaxial stretching, but biaxial stretching is preferred. Biaxial stretching may be simultaneous biaxial stretching, sequential stretching, or multistage stretching (for example, a combination of simultaneous biaxial stretching and sequential stretching). The draw ratio may be appropriately set according to the porosity and film thickness of the porous film to be formed, but it is usually preferably 2 to 30 times as the total area draw ratio. The PAN microporous film obtained by stretching is preferably washed with methanol and / or water to remove residual solvent and dried.

  If necessary, the PAN microporous film may be heat-treated. The crystal of the PAN microporous film is stabilized by the heat treatment. As the heat treatment method, any one of heat setting treatment and heat shrink treatment may be used. In particular, it is preferable to perform a heat shrink treatment because a porous film having a low shrinkage rate and a high strength can be obtained. A known method can be used for both the heat setting treatment and the heat shrinking treatment. These heat treatments are performed within a temperature range below the melting point of the PAN microporous film.

(b) PAN paper / nonwoven fabric
The air permeability of the PAN paper / nonwoven fabric is preferably 0.1 to 5 seconds / 100 ml, and more preferably 0.2 to 1 second / 100 ml. Here, the air permeability is measured according to JIS P8117. The thickness of the PAN paper / nonwoven fabric may be the same as that of the PAN microporous film. The basis weight of the PAN paper / nonwoven fabric is preferably 5 to 50 g / m ² , and more preferably 7 to 20 g / m ² .

  The PAN paper / nonwoven fabric is preferably formed by combining PAN short fibers and fibrillated PAN fibers. Such composite PAN paper / nonwoven fabric is excellent in strength and denseness. The blending ratio of the fibrillated PAN fibers is not particularly limited, but is preferably 5 to 50% by mass, more preferably 10 to 40% by mass, where the total of the PAN short fibers and the fibrillated PAN fibers is 100% by mass. If the blending ratio is less than 5% by mass, the strength of the PAN paper / nonwoven fabric becomes weak and the denseness also decreases. On the other hand, if it exceeds 50% by mass, the dimensional stability becomes worse.

The PAN resin used for the PAN short fiber and the fibrillated PAN fiber may be made of a copolymer as described above, but is preferably made of a homopolymer from the viewpoint of heat resistance, chemical resistance, oxidation resistance, dimensional stability, and the like. . As the PAN resin used for the PAN short fiber and the fibrillated PAN fiber, it is preferable to use a PAN resin having a weight average molecular weight (Mw) of 150,000 or more, thereby improving the heat resistance, chemical resistance, durability, etc. Further improve. Where Mw is
Formula: [η] = 3.35 × 10 ⁻⁴ Mw ^−0.72 (where [η] is an intrinsic viscosity at 30 ° C. when dimethylformamide is used as a solvent).

  The PAN paper / nonwoven fabric may contain binder fibers as necessary. Examples of the binder fiber include synthetic fibers such as polyester fiber, polyolefin fiber, nylon fiber, aramid fiber, and polyphenylene sulfide fiber. The content of the binder fiber is preferably 70% by mass or less based on 100% by mass of the entire PAN paper / nonwoven fabric.

  The procedure for producing PAN paper / nonwoven fabric will be described below. First, PAN long fibers are produced. For the production of PAN long fibers, known spinning techniques such as wet spinning, dry wet spinning, and dry spinning can be applied. When producing by a wet spinning method, the solvent used and the concentration of the stock solution may be the same as in producing a microporous film. The fineness of the PAN long fibers is preferably 0.1 to 10 denier. The PAN short fiber is obtained by cutting the PAN long fiber into a predetermined length. The length of the PAN short fiber is not limited, but is preferably 1 to 25 mm, more preferably 3 to 15 mm. The fibrillated PAN fiber is obtained by beating a PAN short fiber using a beater, a refiner or the like. As PAN fibers that are easily fibrillated by beating, for example, (i) one that is spun using a stock solution containing two or more types of PAN resins that are susceptible to phase separation, and (ii) PAN long fibers obtained by spinning are highly stretched. And those having improved molecular orientation.

  For PAN paper / nonwoven fabric, for example, (i) PAN short fibers (+ fibrillated PAN fibers) are dispersed in a solvent such as water and then drawn on a net (wet method), (ii) PAN shorts in the air (Iii) Needle punch method, chemical bonding method, heat obtained by dispersing fiber (+ fibrillated PAN fiber), and (iii) web obtained by applying PAN short fiber (+ fibrillated PAN fiber) to card or random webber It can be produced by a method of bonding or entanglement by an adhesion method or the like. The wet method is preferred from the viewpoint of productivity and paper / non-woven fabric uniformity. In the case of a wet method, for example, it can be produced by a method of continuous paper making (continuous paper making method) using a circular net type, long net type or short net type paper machine. When produced by the continuous paper making method, the tensile strength (JIS P8113) of PAN paper / nonwoven fabric is preferably 0.1 to 4 kg / 15 mm in the longitudinal direction (MD), and 0.05 to 1.3 kg / 15 in the width direction (TD). It is preferably mm. When producing a PAN paper / nonwoven fabric in which a PAN short fiber and a fibrillated PAN fiber are combined, a sheet-like material may be formed separately from each fiber by any one of the methods described above and laminated.

  The PAN paper / nonwoven fabric obtained by the wet method may be subjected to a heat calender treatment as necessary. An example of the thermal calendar treatment method is a method of passing through a thermal calendar roller. The conditions for the thermal calendar treatment are not particularly limited. For example, the temperature is 60 to 210 ° C., and the linear pressure is 2 kg / cm or more.

(c) PAN woven fabric
The air permeability, basis weight and thickness of PAN woven fabric may be the same as PAN paper / nonwoven fabric. The composition and Mw of the PAN long fiber constituting the PAN woven fabric may be the same as that of the PAN paper / nonwoven fabric. The PAN woven fabric can be produced by a known weaving method such as plain weave, twill weave and satin weave using PAN long fibers.

[3] Method for Producing Solid Polymer Electrolyte Composite Membrane The method for producing the solid polymer electrolyte composite membrane of the present invention is described below. First, (a) the phosphate group-containing unsaturated monomer, (b) a photosensitizer, and (c) each of the other unsaturated monomers added as necessary, the phosphoric acid-modified epoxy resin, and A composition containing at least one selected from the group consisting of the unsaturated oligomers (hereinafter referred to as “unsaturated monomer composition”) is prepared. When preparing an unsaturated monomer composition containing any one of the phosphoric acid-modified epoxy resin and the unsaturated oligomer, the phosphoric acid-modified epoxy resin and / or the unsaturated oligomer and the phosphoric acid group-containing to be added It is preferable to add a common solvent in which all of the unsaturated monomers are dissolved, whereby a uniform unsaturated monomer composition can be prepared.

As a photosensitizer,
(i) adjacent polyketone compounds represented by R— (CO) _w —R ′ (R, R ′ = hydrogen group or hydrocarbon group, w = 2 to 3) (for example, diacetyl, dibenzyl, etc.),
(ii) α-carbonyl alcohols represented by R—CO—CHOH—R ′ (R, R ′ = hydrogen group or hydrocarbon group) (for example, benzoin),
(iii) acyloin ethers represented by R—CH (OR ″) — CO—R ′ (R, R ′, R ″ = hydrocarbon group) (for example, benzoin methyl ether),
(iv) α-substituted acyloins represented by Ar—CR (OH) —CO—Ar (Ar = aryl group, R = hydrocarbon group) (for example, α-alkylbenzoin), and
(v) There are polynuclear quinones (for example, 9,10-anthraquinone, etc.).
These photosensitizers can be used alone, but a plurality of them may be used in combination.

  The amount of the photosensitizer used is based on the total mass of the unsaturated compound (the phosphate group-containing unsaturated monomer and the other unsaturated monomer and / or the unsaturated oligomer added as necessary). The range is 0.01 to 3% by mass, preferably 0.01 to 1.5% by mass. When the amount used is less than 0.01% by mass, polymerization is not completed within a predetermined ultraviolet irradiation time, and an unreacted monomer remains, and when it exceeds 3% by mass, the degree of polymerization of the resulting polymer is preferable. And the polymer tends to be colored, which is not preferable.

The prepared unsaturated monomer composition is impregnated or applied to the PAN porous membrane. In order to improve the adhesion of the solid polymer electrolyte to the PAN porous membrane by sufficiently penetrating the unsaturated monomer composition into the micropores of the PAN porous membrane, (a) the unsaturated monomer composition Pressurize the PAN porous membrane to which an object is attached in an inert gas atmosphere, or (b) activate the back surface of the PAN porous membrane by ultraviolet irradiation, or (c) PAN porous membrane It is preferable to impregnate the unsaturated monomer composition while sucking one side. When pressurizing, it is usually performed at room temperature for 5 to 24 hours under a nitrogen atmosphere at a pressure of 0.5 to 10 kg / cm ² . When irradiating with ultraviolet rays, the irradiation time is 10 to 120 seconds with respect to the porous back surface. When sucking, for example, a method of applying an unsaturated monomer composition while placing a PAN porous film on Nutsche and sucking, or an unsaturated monomer while contacting the PAN porous film with a suction roll The method of apply | coating a composition or immersing in an unsaturated monomer composition is mentioned. Only one of the pressurization and suction as described above may be applied, or both may be combined.

  In order to improve the adhesion of the solid polymer electrolyte to the PAN porous film, the phosphoric acid-modified epoxy resin is added to the PAN porous film before attaching the unsaturated monomer composition to the PAN porous film. The membrane may be permeated.

  The PAN porous membrane having the unsaturated monomer composition attached as described above is sandwiched between UV permeable support substrates and irradiated with UV rays to produce unsaturated compounds (the above phosphate group-containing unsaturated monomers and A solid polymer electrolyte composite membrane can be obtained by photopolymerizing the other unsaturated monomer and / or the unsaturated oligomer added as necessary.

  The ultraviolet transmissive plate and the support substrate used for the ultraviolet irradiation polymerization of the unsaturated monomer composition not only have a high ultraviolet transmittance, but also have heat resistance that can withstand the temperature rise during polymerization due to ultraviolet irradiation, and It is necessary that the unsaturated monomer composition and the solid polymer electrolyte obtained by polymerizing the unsaturated monomer composition are not bonded to each other and have good peelability.

  The glass plate usually used as the support substrate is very good in terms of ultraviolet transmittance and heat resistance, but is in close contact with the solid polymer electrolyte obtained by (co) polymerization of the unsaturated compound used in the present invention. It is preferable to apply a silicone-based or fluorine-based release agent on the surface of the film or attach a fluororesin-based thin transparent film.

  In addition to glass flat plates, the supporting substrate has good UV transmittance such as polyperfluorovinyl ether resin (PFA) and polyvinylidene fluoride resin (PVDF), as well as poly-3-methylpentene resin and polypropylene resin. A resin flat plate having heat resistance of 100 ° C. or higher can be used.

When irradiating ultraviolet rays with a PAN porous membrane impregnated or coated with an unsaturated monomer composition being sandwiched between two supporting substrates, air and excess unsaturated monomer composition are squeezed out of the system. There is a need. For example, as shown in FIG. 1, a composite membrane 1 in which an unsaturated monomer composition 11 is attached to a PAN porous membrane 12 is sandwiched between two support substrates 2 and 2, and pressure is applied evenly. It is preferable to irradiate with ultraviolet rays while being kept horizontal with the clip or clamp 3 stopped. Irradiation is performed for at least one side for 1 to 15 minutes. When irradiation is performed alternately on the front and back sides, it is performed for 1 to 15 minutes on one side. The ultraviolet irradiation intensity at the time of photopolymerization is 5 to 100 μW / cm ² , preferably 10 to 80 μW / cm ² . The ultraviolet irradiation distance is appropriately set so as to be sufficiently cured within the above irradiation time range. The film obtained by the photopolymerization method is preferably heat-treated at 100 to 140 ° C. for about 1 to 15 minutes for the purpose of improving mechanical strength and solvent resistance. In particular, when the unsaturated monomer composition contains the phosphoric acid-modified epoxy resin, it is preferable to heat-treat at 120 to 140 ° C. for about 5 to 15 minutes.

  Since the composite film obtained by the photopolymerization method also includes impurities such as unreacted components such as monomers, it is preferable to extract the impurities. Extraction is performed by immersing the composite membrane in a poor solvent and then removing it. As the poor solvent, water, methanol and the like are preferable. When water or methanol is used as the poor solvent, each of them may be used alone or in combination. The amount of the poor solvent used for one extraction operation is 10 to 100 times the volume of the composite membrane. The immersion temperature may be usually room temperature, and may be heated to such an extent that the composite film does not deteriorate as necessary. Regarding the immersion time, for example, when extraction is performed at room temperature using water or methanol as a poor solvent, the impurities can be substantially extracted by one extraction operation if immersed for about 24 hours. You may repeat extraction by a poor solvent as needed. When repeating extraction with a poor solvent, a heating and vacuum drying operation may be performed between the extraction operations. After being immersed in a poor solvent, it is dried by heat treatment at 100 to 140 ° C. for about 1 to 90 minutes.

  The use ratio of the PAN porous membrane and the unsaturated monomer composition is preferably in the range of PAN porous membrane / unsaturated monomer composition = 1/20 to 1/2 (mass ratio).

  Diluent for the purpose of reducing the viscosity of the unsaturated monomer composition, facilitating impregnation into the PAN porous membrane, reducing the amount of adhesion to the PAN porous membrane, and reducing the thickness of the composite membrane It is also possible to add a low boiling point solvent.

[4] Properties of solid polymer electrolyte composite membrane
The PAN porous membrane has good affinity with the phosphoric acid group-containing (co) polymer. Therefore, the composite of the present invention in which the PAN porous membrane carries a solid polymer electrolyte made of a phosphoric acid group-containing (co) polymer. The membrane is excellent in adhesion between the solid polymer electrolyte and the porous membrane. The PAN porous membrane is also excellent in heat resistance and strength. For this reason, the composite membrane of the present invention is expected to exhibit excellent durability when used as an electrolyte membrane for batteries.

The solid polymer electrolyte composite membrane of the present invention has an electrical conductivity on the order of 10 ⁻³ to 10 ⁻² S · cm ⁻¹ under a relative humidity of 90% and a temperature of 30 to 80 ° C. And the temperature dependence of such proton conductivity is small. Here, the conductivity is obtained from a resistance value obtained by performing plane complex impedance analysis on data measured by the complex impedance method and further performing cole-cole plot graphic processing.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Examples 1-9
(1) Unsaturated monomer and phosphoric acid-modified epoxy resin
(i) Phosmer M: methacryloyloxyethyl phosphate (molecular weight: 210), manufactured by Unichemical Co., Ltd.
(ii) Acrylonitrile: molecular weight 53
(iii) Phosmer 2M: a composition containing methacryloyloxyethyl phosphate (molecular weight: 210) and di (methacryloyloxyethyl) phosphate (molecular weight: 322) in a theoretical molar ratio of about 1: 1, manufactured by Unichemical Co., Ltd.
(iv) Phosmer 2A: a composition comprising acryloyloxyethyl phosphate (molecular weight: 196) and di (acryloyloxyethyl) phosphate (molecular weight: 294) in a theoretical molar ratio of about 1: 1, manufactured by Unichemical Co., Ltd.
(v) Phosphoric acid-modified epoxy resin (CEP): prepared according to Example 1 of JP-A-2001-151584 [Phosphoric acid value: 549.5 mg KOH / g, phosphoric acid equivalent: 203.8 g / eq. Actual value)].

(2) Fabrication of PAN microporous film (PAN microporous film)
17 parts by mass of acrylonitrile (90% by mass) -methyl acrylate (10% by mass) copolymer was dissolved in 83 parts by mass of 70% by mass nitric acid aqueous solution to prepare a PAN resin solution. The obtained PAN resin solution was extruded from a T die while being kept at 20 ° C., and immersed in a 31% by mass nitric acid aqueous solution adjusted to 18 ° C. to form a film-like molded article having a thickness of 0.12 mm. The obtained film-shaped molded article was biaxially stretched in a hot water bath adjusted to 95 ° C. so as to be 2.5 × 2.5 times. The stretched PAN microporous membrane was immersed in methanol overnight and then dried at room temperature over time. The resulting PAN microporous membrane had a thickness of 40 μm and a water permeability of 35 m ³ / m ² · day · atm.

(3) Production of solid polymer electrolyte composite membrane Table 3 shows the blending ratio of the unsaturated monomer and phosphoric acid-modified epoxy resin used. First, the unsaturated monomer and phosphoric acid-modified epoxy resin shown in Table 3 were used as photosensitizers [Irgacure 651 (2,2-dimethoxy-1,2-diphenylethane-1-one) + Irgacure 500 (1 -Hydroxycyclohexyl phenyl ketone, benzophenone) = 1 wt% + 0.5 wt%] (vs. total monomer) was dissolved to prepare each unsaturated monomer composition. A solid polymer electrolyte composite membrane was prepared using the obtained unsaturated monomer compositions according to the following procedure. First, the following treatments (a) to (c) were performed for the purpose of improving the adhesion of the solid polymer electrolyte to the PAN microporous membrane.

(a) Examples 1, 3, 5-8: The unsaturated monomer composition was immersed in the PAN microporous membrane, and then subjected to nitrogen pressure treatment under the conditions shown in Table 3. However, in Example 7, CEP was infiltrated into the PAN microporous membrane for 2 hours before the unsaturated monomer was immersed.
(b) Examples 2, 4, and 9: Both surfaces of the PAN microporous membrane were irradiated with ultraviolet rays for the time shown in Table 3 for activation treatment.
(c) The PAN microporous membrane subjected to the treatment (a) or (b) above is placed on a Nutsche and allowed to pass through each unsaturated monomer composition while being sucked. The pores were filled with an unsaturated monomer composition.

  Next, as shown in FIGS. 1 and 2, the composite film 1 in which the unsaturated monomer composition 11 is attached to the PAN microporous film 12 is placed between the two glass flat plates 2 and 2 to which the fluororesin film is attached. Each solid polymer electrolyte composite membrane was prepared by photopolymerization under the conditions shown in Table 3 and sandwiched between the two. Each obtained composite film was heat-treated at 130 ° C. for 5 minutes. Further, in Examples 5 to 8, an extraction treatment was performed by immersing in methanol at room temperature for 24 hours, and in Example 9, immersing in a mixed solvent of methanol and water [methanol / water = 5/95 (mass ratio)] at room temperature for 24 hours. An extraction process was performed. Table 3 shows the mass ratio, thickness, and the like of the PAN microporous membrane and the polymer of each prepared solid polymer electrolyte composite membrane. Each of the composite membranes of Examples 1 to 9 has a transparent appearance, and it can be said that the adhesion between the solid polymer electrolyte and the PAN microporous membrane is good.

Comparative Example 1
A solid polymer electrolyte composite membrane was produced in the same manner as in Example 1 except that a polyethylene microporous membrane was used as the support. However, the obtained composite membrane was cloudy, and the solid polymer electrolyte was not sufficiently adhered. Further, when this composite membrane was immersed in methanol, the solid polymer electrolyte was easily peeled from the polyethylene microporous membrane.

Table 3 (continued)
Table 3 (continued)

Notes: (1) Methacryloyloxyethyl phosphate (molecular weight: 210).
(2) Acrylonitrile (molecular weight: 53).
(3) A composition containing methacryloyloxyethyl phosphate (molecular weight: 210) and di (methacryloyloxyethyl) phosphate (molecular weight: 322) in a theoretical molar ratio of about 1: 1.
(4) A composition comprising acryloyloxyethyl phosphate (molecular weight: 196) and di (acryloyloxyethyl) phosphate (molecular weight: 294) in a theoretical molar ratio of about 1: 1.
(5) Phosphoric acid modified epoxy resin (Novolac type)
(6) Ultrafiltration water at 25 ° C is permeated through a circular sample (diameter: 50 mm) of PAN microporous film, and the permeation rate per unit time, unit membrane area, and unit pressure (unit membrane differential pressure) is set. Calculated.
(7) Pressurize overnight at room temperature under nitrogen atmosphere.
(8) Using a UV irradiator (800 W) manufactured by Clean TECHNOLOGY Co., Ltd., the PAN microporous membrane was activated with ultraviolet rays (wavelength: 253 nm).
(9) Place PAN microporous membrane on Nutsche, let 20 g of unsaturated monomer composition pass twice, and add 20 g of unsaturated monomer composition to PAN microporous membrane. The unsaturated monomer composition was infiltrated by suction after coating.
(10) Photopolymerization was performed using a high-pressure mercury lamp [Cure Arab HLR-1000F-22 (1 kw) manufactured by Sen Special Light Source Co., Ltd.] (ultraviolet wavelength: 365 nm, irradiation intensity: 15 to 30 μW / cm ² , irradiation distance: 25) cm).
(11) Before immersing the unsaturated monomer, CEP was allowed to permeate the PAN microporous membrane over 2 hours.
(12) Methanol / water = 5/95 (mass ratio).

Reference Examples 1-3
(1) Production of PAN paper
(i) Preparation of PAN short fibers Homo PAN resin (Mw: 150,000) was dissolved in an aqueous sodium thiocyanate solution to prepare PAN long fibers by a wet spinning method. Was prepared.

(ii) Preparation of fibrillated PAN fiber A fibrillated PAN fiber was prepared by beating a PAN short fiber produced in the same manner as in the above (i) with a beater.

(iii) Preparation of PAN paper
69.7 parts by mass of the PAN short fiber (i) above and 30.3 parts by mass of the fibrillated PAN fiber (ii) above are uniformly dispersed in water (solid content: 0.5% by mass) and wet using a circular net paper machine After paper making, the paper was dried at 104 ° C. with a Yankee dryer, and heat calendered at a temperature of 110 ° C. and a linear pressure of 100 kg / cm to prepare PAN paper. The obtained PAN paper was immersed in methanol for 2 hours, then left overnight on a filter paper at room temperature, and dried at 105 ° C. for 5 minutes. Table 4 shows the basis weight and thickness of the obtained PAN paper.

(2) Production of solid polymer electrolyte composite membrane As unsaturated monomers, the same Phosmer M, 2M, 2A and acrylonitrile as in Examples 1 to 9 were used in the blending ratios shown in Table 4, and photosensitizers were used. [Irgacure 651 + Irgacure 500 = 2 wt% + 1 wt%] (vs. total monomers) was dissolved to prepare each unsaturated monomer composition. Each obtained unsaturated monomer composition was attached to PAN paper and photopolymerized under the conditions shown in Table 4 to produce each solid polymer electrolyte composite membrane.

Note: (1) to (4) Same as Table 3.
(5) Photopolymerization was performed using a high-pressure mercury lamp [Cure Arab HLR-1000F-22 (1 kw) manufactured by Sen Special Light Source Co., Ltd.] (ultraviolet wavelength: 365 nm, irradiation intensity: 15 to 30 μW / cm ² , irradiation distance: 25) cm).
(6) The mass loss after the composite membrane was immersed in a large excess of methanol at room temperature for 24 hours and dried at 105 ° C. for 1 hour was measured.
(7) The composite membrane was immersed in a large excess of water at room temperature for 24 hours, and the mass loss after drying at 105 ° C. for 1 hour was measured.

<Evaluation of proton conductivity>
Proton conductivity was measured using the complex impedance method. A rectangular sample of 3 cm × 1 cm cut out from the composite membranes of Examples 1 to 9 and Reference Examples 1 to 3 produced by the above method was placed in an open impedance cell. This cell is installed in a constant temperature and humidity chamber, relative humidity: 90%, measurement temperature range: impedance measurement at 30-80 ° C, and relative humidity range: 60-90%, measurement temperature: impedance measurement at 60 ° C (Examples 1 and 2) were performed. The obtained data was subjected to plane complex impedance analysis, and the conductivity was obtained from the resistance value of the sample obtained by performing the cole-cole plot graphic processing on the result. The results are shown in FIGS.

From the results shown in FIGS. 3, 4, and 6, the conductivity of the solid polymer electrolyte composite membrane of the present invention is 10 ⁻³ to 10 ⁻² S · cm at a relative humidity of 90% and a temperature range of 30 to 80 ° C. It can be seen that it is in the order of ⁻¹ , which is a good level as a polymer electrolyte having a phosphate group as a functional group, and the temperature dependence of conductivity is small. In particular, the composite membrane using the PAN microporous film of Examples 1 to 9 is excellent in electrical conductivity and has low temperature dependence of electrical conductivity, and in particular, the composite membrane in which the solid polymer electrolyte includes a phosphoric acid-modified epoxy resin (Examples 8 and 9) showed high conductivity. Further, according to the comparison between Examples 3 and 8 and the comparison between Examples 4 and 9, the conductivity was almost the same regardless of the presence or absence of the extraction treatment. From the results shown in FIG. 5, the conductivity of the solid polymer electrolyte composite membrane of the present invention is 10 ⁻³ to 10 ⁻² S · cm ⁻¹ at a temperature of 60 ° C. and a relative humidity range of 60 to 90%. It was in order and was a good level as a polymer electrolyte having a phosphate group as a functional group.

<Methanol extraction test>
The composite membranes extracted with methanol of Reference Examples 1 to 3 were further immersed in a large excess of methanol at room temperature for 24 hours and dried at 105 ° C. for 1 hour, and the mass loss was measured. From Table 4, the methanol extraction residual ratio exceeded 90% in any of the membranes, indicating excellent methanol extractability.

<Water extraction test>
The water-extracted composite membranes of Reference Examples 1 to 3 were further immersed in a large excess of water at room temperature for another 24 hours, and the mass loss after drying at 105 ° C. for 1 hour was measured. From Table 4, the extraction ratio with respect to water was 10 mass% or less in any of the membranes, and excellent water extractability was exhibited.

It is a side view which shows the state which pinched | interposed the solid polymer electrolyte composite film between two glass flat plates. It is a top view which shows the state which pinched | interposed the solid polymer electrolyte composite film between two glass flat plates. It is a graph which shows the relationship between temperature T (degreeC) and electrical conductivity log ((sigma) / S * cm < ^-1 >) by a cole-cole plot about the solid polymer electrolyte composite film of Examples 1-4. It is a graph which shows the relationship between temperature T (degreeC) and electrical conductivity log ((sigma) / S * cm < ^-1 >) by a cole-cole plot about the solid polymer electrolyte composite film of Examples 5-9. It is a graph which shows the relationship between relative humidity (%) and electrical conductivity log ((sigma) / S * cm < ^-1 >) by a cole-cole plot about the solid polymer electrolyte composite film of Example 1,2. It is a graph which shows the relationship between temperature T (degreeC) and electrical conductivity log ((sigma) / S * cm < ^-1 >) by a cole-cole plot about the solid polymer electrolyte composite film of the reference examples 1-3 .

Explanation of symbols

1. Solid polymer electrolyte composite membrane
11 ... Solid polymer electrolyte
12 ... PAN porous membrane 2 ... Glass flat plate 3 ... Clip

Claims (12)

(a) a phosphate group-containing unsaturated monomer having one or more phosphate groups and one or more ethylenically unsaturated bonds in the molecule, or (b) the phosphate group-containing unsaturated monomer And a solid polymer electrolyte composite obtained by impregnating a microporous film formed from a polyacrylonitrile resin by a wet method with (un) polymerizing with another unsaturated monomer copolymerizable therewith film. The solid polymer electrolyte composite membrane according to claim 1, wherein the phosphate group-containing unsaturated monomer is represented by the following general formula (1):

(Wherein R ¹ is a hydrogen group or an alkyl group, R ² is a hydrogen group or a substituted or unsubstituted alkyl group, and n is an integer of 1 to 6). A solid polymer electrolyte composite membrane. 3. The solid polymer electrolyte composite membrane according to claim 2, wherein R ¹ is H or CH ₃ and R ² is H, CH ₃ or CH ₂ Cl. The solid polymer electrolyte composite membrane according to any one of claims 1 to 3, wherein the other unsaturated monomer includes one or more ethylenically unsaturated bonds, a sulfonic acid group, and a carboxylic acid group in the molecule. , Unsaturated monomers having at least one functional group selected from the group consisting of alcoholic hydroxyl groups, amino groups and fluorine groups , (meth) acrylonitrile, (meth) acrylic esters, substituted or unsubstituted styrene A solid polymer electrolyte composite membrane, wherein the membrane is at least one member selected from the group consisting of vinyl chloride and vinyl acetate . The solid polymer electrolyte composite membrane according to any one of claims 1 to 4, wherein the phosphate group-containing unsaturated monomer is represented by the following general formula (2):

(However, R ³ and R ⁶ are each independently a hydrogen group or an alkyl group, R ⁴ and R ⁵ are each independently a hydrogen group or a substituted or unsubstituted alkyl group, and k and p are each independently 1 to 1) A solid polymer electrolyte composite membrane comprising a phosphoric acid group-containing diester unsaturated monomer represented by the formula: ^6. The solid polymer electrolyte composite membrane according to claim 5, wherein R ³ and R ⁶ are each independently H or CH ₃ , and R ⁴ and R ⁵ are each independently H, CH ₃ or CH ₂ Cl. A solid polymer electrolyte composite membrane. The solid polymer electrolyte composite membrane according to any one of claims 1 to 6, further comprising a phosphoric acid-modified epoxy resin. The solid polymer electrolyte composite membrane according to claim 7, wherein the phosphoric acid-modified epoxy resin has the following general formula (3):

(However, R ⁷ and R ⁹ each represent a substituted or unsubstituted alkylene group, R ⁸ represents hydrogen, a halogen atom, or a substituted or unsubstituted alkyl group, and m is an integer of 0 or more representing the degree of polymerization. The compound represented by the general formula (3) may be a copolymer containing two or more constitutional units or a mixture of two or more constitutional units). Modified by introducing a phosphate group at least partially, and having a phosphate group and a hydroxyl group present in one molecule, and / or the following general formula (4):

(However, R ¹⁰ represents a residue derived from bisphenols, or a substituted or unsubstituted alkylene group having 1 to 4 carbon atoms, and m ′ represents an integer of 0 or more representing the degree of polymerization. According to the general formula (4) The compound represented may be a cocondensate containing two or more structural units or a mixture of two or more structural units.) The epoxy ring of the bisphenol-type epoxy resin represented by A solid polymer electrolyte composite membrane, which is modified by introducing an acid group, wherein a phosphate group and a hydroxyl group coexist in one molecule. The solid polymer electrolyte composite membrane according to any one of claims 1 to 8, wherein the water permeability of the polyacrylonitrile microporous film is 1 to 500 m ³ / m ² · day · atm. Molecular electrolyte composite membrane. 10. The solid polymer electrolyte composite membrane according to claim 1, wherein the polyacrylonitrile microporous film comprises (a) an acrylonitrile homopolymer, (b) a copolymer of acrylonitrile and a monomer copolymerizable with acrylonitrile. Or (c) a solid polymer electrolyte composite membrane comprising a mixture thereof. 11. The solid polymer electrolyte composite membrane according to claim 10, wherein the monomer copolymerizable with acrylonitrile is an alkyl (meth) acrylate having an alkyl group having 4 or less carbon atoms; (meth) acrylic acid; (meth) acrylic Hydroxyethyl acid; Bromoethyl (meth) acrylate; Methacrylonitrile; Itaconic acid; (Meth) acrylic acid amide; Fatty acid vinyl; Vinyl pyrrolidone; Methyl vinyl ketone; Halogenated vinyl; Halogenated vinylidene; A solid polymer electrolyte composite membrane, which is at least one selected from the group consisting of methallylsulfonic acid, allylsulfonic acid, p-styrenesulfonic acid, and salts thereof; and olefins. A fuel cell using the solid polymer electrolyte composite membrane according to claim 1.