JP2006100241A - Solid polyelectrolyte membrane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide at low cost a solid polyelectrolyte membrane which is superior in methanol prevention performance while maintaining high ion conductivity. <P>SOLUTION: This is the solid polyelectrolyte membrane which is obtained by mixing an electrolyte polymer made by copolymerizing a monomer having an acidic group or a monomer having acidic group turned into quarternary ammonium and a monomer having a basic group with polyimide, and which satisfies the following conditions (a) and (b). (a) The monomer having an acidic group is a monomer having at least one kind selected from a group of sulfonic acid group, phosphonic acid group, and carboxyl group, and (b) the monomer having a basic group is a monomer having one kind selected from a group of amino group, amide group, and urea group. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ion conductive solid polymer electrolyte membrane. More specifically, the present invention relates to a solid polymer electrolyte membrane having high ion conductivity, such as a fuel cell, an ion conductive membrane for a solid polymer electrolyte fuel cell, a redox cell, an electrodialysis membrane, a reverse osmosis membrane, a nanofiltration membrane, and a diffusion dialysis. Used in the fields of membranes, gas separation membranes, pervaporation and permeation extraction membranes, humidity sensors, gas sensors. The solid polymer electrolyte membrane according to the present invention has extremely low methanol permeability and is used as an electrolyte membrane for a direct methanol fuel cell (hereinafter referred to as DMFC).

  In recent years, fuel cells are becoming important as next-generation clean energy sources. Among the fuel cells, the solid polymer electrolyte fuel cell has both an anode and a cathode arranged with a solid polymer electrolyte membrane in between. For example, in the case of DMFC in which methanol is used as fuel, methanol is supplied to the anode side and oxygen or air is supplied to the cathode side to cause an electrochemical reaction to generate electricity. In order to realize a small and lightweight fuel cell utilizing the characteristics of high output and high energy density, a solid polymer electrolyte membrane having high proton conductivity has been developed. The solid polymer electrolyte membrane used in the DMFC has a fuel methanol blocking property while maintaining high ionic conductivity, that is, fuel methanol permeation from the anode side to the cathode side of the solid polymer electrolyte membrane. Reduction of (crossover) is required.

  Conventionally, in general, a hydrated perfluorocarbon sulfonic acid (hereinafter referred to as PFS) polymer (for example, a product name Nafion membrane manufactured by DuPont, etc.) has high ionic conductivity. Widely used and studied as an electrolyte membrane. However, a hydrated PFS polymer membrane is easy to allow methanol having high affinity for water to pass (crossover), and has a theoretical limit in methanol blocking ability. As a means for reducing the methanol crossover of the PFS polymer hydrated film, it is conceivable to combine different materials based on the PFS polymer hydrated film. However, the above-mentioned composite significantly reduces the high ionic conductivity of the original PFS polymer hydrated film.

  As a method for solving these problems, it is disclosed that a Nafion 112 membrane is impregnated with aniline to form a meta-type polyaniline, and that ion conductivity comparable to that of the Nafion membrane and methanol blocking ability of about 1/3 of the Nafion membrane are achieved. However, it is still insufficient for use in DMFC electrolyte membranes (see Patent Document 1). Further, since the expensive Nafion membrane is further processed, the number of steps is complicated and the membrane must be made more expensive. In addition, a graft copolymer comprising a main chain having a basic group and water-soluble and a side chain insoluble in water, and a water-soluble main chain having an acidic group and a side chain insoluble in water, A zwitterionic polymer gel obtained by mixing a graft copolymer consisting of the above and a method for producing the polymer gel membrane have been disclosed (see Patent Document 2). It is characterized by a large change in the degree, and there is no description about the ion conductive membrane. In addition, even if these gel membranes are used as fuel cell membranes, they do not serve as fuel cell membranes if the volume and area of the membrane change greatly due to pH changes in the fuel cell during power generation. There is even a risk of destroying the fuel cell itself. Furthermore, a solid polymer film obtained by impregnating a main polymer having an acidic or basic site with a secondary polymer having a basic or acidic site and a method for producing the same have been disclosed (see Patent Document 3). Many problems still remain, such as not showing ionic conductivity.

  Various membranes obtained by sulfonating a hydrocarbon membrane having an aromatic ring have been studied. Sulfuric acid and fuming sulfuric acid act on engineering plastics such as polyimide (see non-patent documents 1 to 4), polyether ether ketone (see non-patent document 5), polybenzimidazole (see non-patent document 6), etc. It has been reported that a sulfonated membrane or a benzene ring skeleton as a starting material is sulfonated and then a desired sulfonated membrane is obtained by a condensation reaction. These electrolyte membranes are insufficient in ion conductivity and methanol blocking property, are too special raw materials, and are difficult and complicated to manufacture, and are difficult to manufacture at low cost.

Prior to this, polyethyleneimine doped with sulfuric acid or phosphoric acid (see Non-patent Document 7) Polysilamine doped with phosphoric acid (see Non-Patent Document 8), polyacrylamide doped with sulfuric acid or phosphoric acid (See non-patent document 9), polybenzimidazole doped with phosphoric acid (see patent document 4), and sulfonated polyethersulfone added with polybenzimidazole (see non-patent document 10). However, it has many problems such as the dopant flowing down and not exhibiting sufficient ionic conductivity.
JP 2001-81220 A JP-A-6-145464 JP 2001-236773 A Japanese National Patent Publication No. 11-503262 M. Watanabe, Chem. Commun., 368 (2003) Y.Zhan, M.Litt, RFSavinell, ACS Polym.Prepr., 41 (2), 1561 (2000) C. Genies, R. Marcier, B. Silion, Polymer, 42, 359 (2001) J.Fang, X.Guo, S.Harada, Macromolecules, 35,9022 (2002) J. Roziere, J. Membr. Sci., 185, 41 (2001) O. Savadogo, J. New Mat. Electroanal. Sys. 2,95 (1999) D. Schoolmann, O. Trinquent, and J.-C. Lassegues, Electrochim Acta, 37, 1619 (1992) K. Tsuruhara, M. Rikukawa, K. Sunui, N. Ogata, Y. Nagasaki, and M. Kato, Electrochim Acta, 45, 1391 (2000) W. Wieczorek and JR Stevens, Polymer, 38, 2057 (1997) J. Kerrer, A. Ullrich, F. Meier and T. Harig, Solid State Ionics, 125, 243 (1999)

  The present invention has been made to solve the present problems of the PFS polymer hydrated membrane, the PFS modified membrane, and various hydrocarbon electrolyte membranes as the solid polymer electrolyte for DMFC as described above. An object of the present invention is to provide a solid polymer electrolyte membrane excellent in methanol blocking property while maintaining high ionic conductivity at low cost.

As a result of diligent research on the above problems, the present inventors have obtained an electrolyte polymer obtained by copolymerizing a monomer having a specific acidic group or a monomer obtained by quaternizing ammonium with the monomer and a monomer having a specific basic group, The present inventors have found that a solid polymer electrolyte membrane obtained by mixing polyimide improves methanol blocking properties while maintaining high ionic conductivity. That is, the present invention is as follows.
1. A solid polymer electrolyte obtained by mixing an electrolyte polymer obtained by copolymerizing a monomer having an acidic group or a monomer having an acidic group with a quaternary ammonium salt and a monomer having a basic group, with a polyimide, A solid polymer electrolyte that satisfies the following conditions (a) and (b):
(A) the monomer having an acidic group is a monomer having at least one selected from the group consisting of a sulfonic acid group, a phosphonic acid group, and a carboxyl group;
(B) The monomer having basicity is a monomer having at least one selected from the group consisting of an amino group, an amide group, and a urea group.
2. The mixing ratio (electrolyte polymer weight / polyimide weight) of an electrolyte polymer obtained by copolymerizing a monomer having an acidic group or a monomer having an acidic group quaternary ammonium and a monomer having a basic group with a polyimide is 10 The solid polymer electrolyte according to item 1, which is in the range of / 90 to 80/20.
3. 3. The solid polymer electrolyte according to item 1 or 2, wherein the polyimide has a hydroxyl group and / or a carboxyl group.
4). A monomer having an acidic group or a monomer having an acidic group that has been converted to a quaternary ammonium salt is acrylamidomethylpropanesulfonic acid, styrenesulfonic acid, vinylsulfonic acid, (meth) allylsulfonic acid, acid phosphohydroxyethyl methacrylate, (meta The solid polymer electrolyte according to any one of Items 1 to 3, which is acrylic acid, maleic anhydride, fumaric acid, or a quaternary ammonium salt of these monomers.
5. A monomer having a basic group is acrylamide, allylamine, vinylpyrrolidone, vinylimidazole, aminoacrylamide, aminosulfone, vinylpyridine, dimethylaminoethyl (meth) acrylate, vinylcaprolactam, vinylcarbazole, vinyldiaminotriazine or ethyleneimine. Item 5. The solid polymer electrolyte according to any one of Items 1 to 4.
6). The electrolyte polymer is obtained by copolymerization by adding a neutral monomer to a monomer having an acidic group or a monomer having an acidic group and a monomer having a quaternary ammonium group and a basic group. Item 6. The solid polymer electrolyte according to any one of Items 5 to 5.
7). The solid polymer electrolyte according to claim 6, wherein the neutral monomer is 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, styrene, acrylonitrile, or polyethylene glycol di (meth) acrylate.
8). The polyimide is a solvent comprising at least one selected from the tetracarboxylic dianhydrides and tetracarboxylic acids shown in the following (c) and at least one selected from the diamine compounds shown in the following (d) Item 8. The solid polymer electrolyte according to any one of Items 1 to 7, which is obtained by polycondensation therein.
(C) 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclopentanetetracarboxylic dianhydride Bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic acid, 1,2,3 4-cyclobutanetetracarboxylic acid, 1,2,4,5-cyclopentanetetracarboxylic acid, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic acid (d) 2 2,2'-dihydroxy-4,4'-diaminodiphenylene, methylenebis [4-amino-2-benzoic acid], 4,4'-diaminodiphenyl ether, 2,2-bis [4- (4-aminophenoxy) Phenyl] Pro Emissions, 1,4-bis (4-aminophenoxy) benzene, 4,4'-diaminodicyclohexylmethane 9. A solid polymer electrolyte membrane formed by forming the solid polymer electrolyte according to any one of Items 1 to 8.

  A solid polymer obtained by mixing an electrolyte polymer obtained by copolymerizing a monomer having a specific acidic group of the present invention or a monomer obtained by quaternizing ammonium with the monomer and a monomer having a specific basic group with polyimide The electrolyte membrane is excellent in proton conductivity and methanol blocking property. The solid polymer electrolyte membrane is useful as a solid polymer electrolyte membrane for fuel cells, particularly for DMFC. Moreover, the production of the solid polymer electrolyte membrane of the present invention is simple and can be produced at low cost.

  The monomer having an acidic group in the present invention (sometimes referred to as A monomer) may be any monomer having a sulfonic acid group, a phosphonic acid group, or a carboxyl group, and a plurality of these different types of monomers may be mixed. . Further, a monomer obtained by quaternary ammonium conversion of the monomer (sometimes referred to as A ′ monomer) may be used. Further, some or all of the hydrogen atoms bonded to carbon may be substituted with fluorine atoms.

  Specific examples include acrylamidomethylpropane sulfonic acid, styrene sulfonic acid, vinyl sulfonic acid, (meth) allyl sulfonic acid, acid phosphooxyethyl methacrylate, (meth) acrylic acid, maleic anhydride, and fumaric acid. However, the present invention is not limited thereto, and any monomer having at least one selected from the group consisting of a sulfonic acid group, a phosphonic acid group, and a carboxyl group may be used. Further, quaternary ammonium salts of these monomers may be used.

  In order to quaternize the monomer having an acidic group, the monomer may be mixed or dissolved with an appropriate solvent, reacted with a tertiary amine compound, and quaternized. As the tertiary amine compound, trimethylamine, triethylamine, tributylamine, trihexylamine, dimethylethylamine and the like can be used. However, the tertiary amine compound is not limited to these, and sulfonic acid group, phosphonic acid group, carboxyl group and What is necessary is just to be able to produce | generate a quaternary compound. Examples of the solvent include water, alcohols such as methanol and ethanol, acetones, ketones, dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, etc., which dissolve monomers and quaternized compounds, and are quaternary. It is good if there is no abnormality in the chemical reaction. When quaternizing, some heat is generated, so that it is 60 ° C. or less, preferably 50 ° C. or less, and more preferably 40 ° C. or less. When the temperature is 60 ° C. or higher, there is a possibility of causing a polymerization reaction when quaternizing.

  The monomer having a basic group in the present invention (sometimes referred to as B monomer) may be any monomer having an amino group, an amide group, or a urea group. Also, a mixture of a plurality of these different monomers may be used. Furthermore, some or all of the hydrogen atoms bonded to carbon may be substituted with fluorine atoms.

  Specifically, acrylamide, allylamine, vinylpyrrolidone, vinylimidazole, aminoacrylamide, aminosulfone, vinylpyridine, dimethylaminoethyl (meth) acrylate, vinylcaprolactam, vinylcarbazole, vinyldiaminotriazine, ethyleneimine, and derivatives thereof It can be illustrated. In addition, examples include, but are not limited to, monomers having an aromatic ring, and have an aliphatic monomer or aromatic compound having at least one selected from the group consisting of an amino group, an amide group, and a urea group. Any monomer may be used.

  The A monomer or A ′ monomer and the B monomer are generally mixed with a solvent. The solvent used may be water, methanol, ethanol, isopropanol, acetone, dimethyl sulfoxide, dimethylacetamide, dimethylformamide, etc., but is not limited thereto, and the polymerization reaction can be controlled, and the hydroxyl group described later In addition, it can be mixed well with polyimide having a carboxyl group and should not cause problems such as phase separation in the film forming process. N-methylpyrrolidone, γ-butyrolactone, dimethylacetamide, dimethyl sulfoxide are preferably used.

  A predetermined amount of the A monomer or A ′ monomer and the B monomer is usually added to the polymerization reactor in the form of a solution to which the above solvent is added. Thereafter, a uniform polymerization composition is obtained by mixing and stirring. In the polymerization method, these monomers can be added all at once to the reactor, or the monomer mixture can be added into the polymerization reactor by a sequential addition method for polymerization. These methods may be appropriately employed depending on the properties of the obtained polymer, and the usual methods of the business operator can be used as these techniques. Furthermore, after completion of the polymerization reaction, other additives such as an antioxidant (such as a radical scavenger and a hydroperoxide decomposer) and a colorant may be mixed together.

  A neutral monomer may be added to the monomer mixed solution of (A or A ′ + B) for copolymerization. As the third monomer, 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, styrene, acrylonitrile, polyethylene glycol di (meth) acrylate, or the like is preferably used. By adding these third monomers, it is possible to expect effects such as that a large amount of electrolyte polymer can be introduced into the solid polymer electrolyte membrane and that the domain of the electrolyte polymer can be reduced. In addition, by introducing 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, etc., a crosslinked structure can be introduced between electrolyte polymers, and an IPN polymer (interpenetrating network structure) mutually interpenetrated with polyimide. Polymer), and the release and elution of the electrolyte polymer can be prevented. As a result, the IPN polymer thus obtained is also excellent in mechanical strength. If a cross-linked structure can be introduced between electrolyte polymers, cross-linking between functional groups of the polymer, cross-linking by hydrogen abstraction reaction by adding peroxide, etc. can be adopted, and the properties of the obtained solid polymer electrolyte membrane etc. What is necessary is just to employ | adopt suitably collectively. Examples of the cross-linking agent between the functional groups of the polymer include diisocyanates such as trielediisocyanate, diols such as polyethylene glycol, diepoxy such as bisphenol A diepoxy compound, and dianhydrides. It does not restrict to a compound, What is necessary is just to be able to introduce | transduce a crosslinked structure between electrolyte polymers and between an electrolyte polymer and a polyimide.

  Polymerization of A monomer or A ′ monomer and B monomer can be initiated by heat, light, electron beam, etc., but in the case of thermal polymerization, radical, cation and anionic polymerization initiators can be used, A radical initiator is used. The polymerization by light is generally performed by a combination of a photosensitizer and a polymerization initiator, and these methods can be appropriately used. For example, when an organic solvent is used as a polymerization solvent, organic peroxides and azo compounds described in the catalog of Nippon Oil & Fats Co., Ltd. can also be used, and benzoyl peroxide, azobisisobutyronitrile, etc. are preferably used. it can. When water is used as a polymerization solvent, a water-soluble radical initiator can be used, and VA-044, V-50, VA-086, etc. described in the catalog of Wako Pure Chemical Industries, Ltd. are preferably used. Is done.

  The addition amount of the polymerization initiator depends on the respective polymerization conditions, but is 0.001 to 5 parts by weight, preferably 0.01 to 2 parts by weight, and more preferably 100 parts by weight of the total addition amount of monomers. Is 0.05 to 1 part by weight. The polymerization temperature is preferably from 0 ° C to 120 ° C, preferably from 20 ° C to 100 ° C, more preferably from 30 ° C to 80 ° C, but the monomer composition, the physical properties of the obtained polymer, and the process time. What is necessary is just to select suitably by etc.

  Thus, a copolymer of (A or A ′ + B) is first prepared, and then a polyimide solution is added to the copolymer to obtain a uniform solution to form a film-forming solution.

  As the polyimide forming the matrix, a tetracarboxylic dianhydride or tetracarboxylic acid and a polyimide using a diamine compound as raw materials can be applied, and a polyimide soluble in an organic solvent as described below is preferable. Examples of the raw material tetracarboxylic dianhydride include 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,4,5-cyclopentanetetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid. And bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic acid. Of these, 1,2,4,5-cyclohexanetetracarboxylic acid is particularly preferred.

Examples of the diamine compound as a polyimide raw material include 2,2′-dihydroxy-4,4′-diaminodiphenylene, methylenebis [4-amino-2-benzoic acid], p-phenylenediamine, m-phenylenediamine, 4 , 4′-diaminobiphenyl, 4,4′-diamino-2,2′-dimethylbiphenyl, 4,4′-diamino-3,3′-dimethylbiphenyl, 4,4′-diamino-2,2′-ditri Fluoromethylbiphenyl, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 4,4′-diaminobenzophenone, 4,4′-diaminodiphenyl sulfone, 4,4′- Diaminodiphenyl sulfide, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenyl) Noxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, bis [4- (3-aminophenoxy) phenyl] sulfone, 9,9 -Aromatic diamine compounds such as bis (4-aminophenyl) fluorene, ethylenediamine, hexamethylenediamine, polyethylene glycol bis (3-aminopropyl) ether, polypropylene glycol bis (3-aminopropyl) ether, 1,3-bis ( Aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 4,4 ′ Diaminodicyclohexylmethane, 3 (4), 8 (9) - bis (aminomethyl) - tricyclo [5.2.1.0 ^2,6] decane, m-xylylenediamine, p-xylylenediamine, isophoronediamine, norbornanediamine And aliphatic diamine compounds such as siloxane diamines. These can be used individually by 1 type or in mixture of 2 or more types.

  As the diamine compound, 4,4′-diaminodiphenyl ether, 1,4-bis (4-aminophenoxy) benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 4,4 ′ -Diaminodicyclohexylmethane etc., or these derivatives can be illustrated. More preferred are 2,2'-dihydroxy-4,4'-diaminodiphenylene, methylenebis [4-amino-2-benzoic acid], or a diamine compound containing these. However, the present invention is not limited to these, and a polyimide that is soluble in an organic solvent, preferably a polyimide that is soluble in an organic solvent and has a hydroxyl group and / or a carboxyl group may be obtained.

  A desired polyimide can be produced by mixing a predetermined amount of tetracarboxylic dianhydride or tetracarboxylic acid and a diamine compound in a predetermined solvent and raising the temperature to perform a dehydration condensation reaction. For example, the reaction molar ratio of the tetracarboxylic acids and the total diamine compound is preferably in the range of 95 to 105 mol% with respect to either one. More preferably, it is the range of 98-102 mol%. Moreover, when using a catalyst for dehydration condensation reaction, 0.001-1.0 mol of tertiary amine compounds of a catalyst are used with respect to 1 mol of tetracarboxylic acid components to be used. Tertiary amine compounds include trimethylamine, triethylamine, tripropylamine, tributylamine, triethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, triethylenediamine, N-methylpyrrolidine, N-ethylpyrrolidine. N-methylpiperidine, N-ethylpiperidine, imidazole, pyridine, quinoline, isoquinoline and the like. Particularly preferred is triethylamine. Solvents include γ-butyrolactone, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N, N-dimethylformamide, dimethyl sulfoxide, hexamethylphosphoramide, tetramethylene sulfone, p-chlorophenol, m- Examples thereof include cresol and 2-chloro-4-hydroxytoluene. These can be used individually by 1 type or in mixture of 2 or more types. Of these, γ-butyrolactone, N, N-dimethylacetamide, N-methyl-2-pyrrolidone and dimethyl sulfoxide are preferred. Furthermore, a poor solvent for polyimide can be used in combination so that the polymer does not precipitate. Examples of the poor solvent include hexane, heptane, benzene, toluene, xylene, chlorobenzene, o-dichlorobenzene, and the like. The amount of the solvent used is such that the total weight of the tetracarboxylic acid component and the total diamine component is 1 to 50% by weight with respect to the total weight of the reaction solution. The amount is preferably 20 to 45% by weight.

  The method for preparing the tetracarboxylic acid component and the diamine compound component is not particularly limited. The other component is contained in a solution containing one of the two components in a batch (not necessarily completely dissolved). Or the like can be gradually charged in a solid or solution state.

  The tertiary amine compound is preferably charged until the temperature reaches the target temperature in order to sufficiently exert its catalytic effect. In particular, it is preferable that the solvent, the tetracarboxylic acid component, and the diamine compound are charged at the same time. The method of charging the solvent is not particularly limited, and is a method of charging into the reaction tank in advance, a method of charging into the reaction tank in which either one or both of the tetracarboxylic acid component and the diamine compound are present, the tetracarboxylic acid component, or the diamine. A method in which either one of the components is dissolved in advance and then charged into the reaction vessel can be performed alone or in combination.

  The reaction temperature is in the range of 150-250 ° C. The reaction pressure is usually atmospheric pressure, but may be increased. The holding time is in the range of 0.2 to 48 hours. The obtained polyimide is generally used by dissolving in a solvent such as N-methylpyrrolidone, γ-butyrolactone, dimethylacetamide, dimethyl sulfoxide. A suitable polyimide concentration is in the range of 5-20%.

  In preparing a film-forming solution by mixing a solution of an electrolyte polymer obtained by copolymerization of an A monomer or A ′ monomer and a B monomer with a polyimide solution that forms a matrix, the electrolyte polymer and the polyimide The mixing ratio (weight of electrolyte polymer / weight of polyimide) is in the range of 10/90 to 80/20. The proportion of the electrolyte polymer is 80% by weight or less, preferably 75% by weight or less, and more preferably 70% by weight or less. When the proportion of the electrolyte polymer exceeds 80% by weight, it becomes tattered in the 0.5 mol sulfuric acid treatment or the water washing treatment after film formation, and a self-supporting membrane cannot be obtained (see Comparative Example 1). On the other hand, when the proportion of the electrolyte polymer is less than 10% by weight, sufficient ionic conductivity is not exhibited (see Comparative Example 5).

  As a film forming method, a general cast film forming method can be employed. A desired solid polymer electrolyte membrane can be obtained by applying a mixed solution of a concentration-adjusted electrolyte polymer and polyimide to a glass plate so as to have a predetermined thickness, and drying and curing at a predetermined temperature.

  Furthermore, a mold release agent may be used in order to improve the mold release property between the electrolyte membrane obtained from the electrolyte polymer and the polyimide solution and the glass plate. As the internal mold release agent, stearic acid, zinc stearate or the like can be used. As an external mold release agent, an external mold release agent described in catalogs of Samei Co., Ltd. and Chukyo Chemical Industry Co., Ltd. can be used. For example, Mirror Glaze (manufactured by Samei Co., Ltd.), Pericoat S6, Pericoat MD8 (manufactured by Chukyo Kasei Kogyo Co., Ltd.) and the like can be exemplified. Good. Moreover, it can replace with a mold release agent and can also use it, putting films, such as polyethylene, a polypropylene, a polyvinyl chloride, a polyvinylidene chloride, a polyethylene terephthalate, a polyimide, between glass plates.

  The film thickness of the solid polymer electrolyte membrane produced as described above is 200 μm or less, preferably 180 μm or less, and more preferably 150 μm or less.

The ionic conductivity of the solid polymer electrolyte membrane is 1 × 10 ⁻⁴ S / cm or more, preferably 5 × 10 ⁻⁴ S / cm or more, more preferably 1 × 10 ⁻³ S / cm or more. good.

  Further, the methanol permeability of the solid polymer electrolyte membrane is 60 μg / cm · min or less, preferably 50 μg / cm · min or less, more preferably 40 μg / cm · min or less.

The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples. In the synthesis examples, polymerization examples, examples and comparative examples, parts and% are based on weight unless otherwise specified. Various measurements were performed as follows.
Ionic conductivity measurement The ionic conductivity of the solid polymer electrolyte membrane of the present invention was measured at 25 ° C. using an impedance analyzer SI1260 manufactured by Solartron. Next, the direct current component R was read from the Col-Col plot, and the proton conductivity was calculated.
Measurement of methanol permeability The methanol permeability of the solid polymer electrolyte membrane of the present invention was measured according to the following method. The obtained solid polymer electrolyte membrane was sandwiched in the center of the communication tube, 100 ml of 30% methanol aqueous solution was charged on one side, and 100 ml of ion exchange water on the other side, and immersed in a constant temperature water bath at 40 ° C. The methanol permeating into the water side was quantified by gas chromatography, and the methanol permeation rate (mg / cm ² / min) was first calculated. Next, the methanol permeability (μg / cm · min) taking into account the film thickness was calculated based on the following formula.
Methanol permeability (μg / cm · min) = Methanol permeation rate (mg / cm ² / min) × film thickness (μm)
Measurement of mechanical strength The mechanical strength of the solid polymer electrolyte membrane of the present invention was measured using Shimadzu Autograph manufactured by Shimadzu Corporation at room temperature according to ASTM D 3039 by the following method. The obtained film is punched using a bowl-shaped die-cutting machine with a width of 10 mm, a length of 65 mm, a gauge distance of 20 mm, and a minimum width of 3 mm. did. The strength was the mechanical strength at the maximum yield point.

Synthesis Example 1 Production of polyimide from 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 4,4′-diaminodiphenyl ether and methylenebis [4-amino-2-benzoic acid] 300 ml of 5 necks In a glass round bottom flask, weigh 0.054 mol of 4,4′-diaminodiphenyl ether (ODA), 0.058 mol of methylenebis [4-amino-2-benzoic acid] (MBAA), and 65.0 g of γ-butyrolactone. A Dean-Stark equipped with a stainless steel half-moon stirring blade, a nitrogen inlet tube, a cooling tube, a thermometer, and a glass end cap were attached, and the mixture was dissolved by stirring at 100 rpm in a nitrogen atmosphere. To this, 0.116 mol of 1,2,4,5-cyclohexanetetracarboxylic dianhydride (HPMDA) and 16.3 g of dimethylacetamide were added, a mantle heater was attached to the flask, and the temperature in the reaction system was raised to 180 ° C. . The component to be distilled off was collected and left in that state for 2 hours. After adding 118.7 g of dimethylacetamide, the mantle heater was removed and air-cooled to obtain a polyimide varnish having a solid content concentration of 20 wt% (referred to as polyimide HPMDA-ODA-MBAA).

Synthesis Example 2 Production of polyimide from 1,2,4,5-cyclohexanetetracarboxylic dianhydride and 2,2′-dihydroxy-4,4′-diaminodiphenylene 4,4′- used in Synthesis Example 1 Instead of diaminodiphenyl ether and methylenebis [4-amino-2-benzoic acid], 25.06 g (0.116 mol) of 2,2′-dihydroxy-4,4′-diaminodiphenylene (HAB) was used and retained. A polyimide was synthesized in the same manner as in Synthesis Example 1 except that the time was 4 hours. The reaction solution was a uniform brown transparent viscous liquid, and the solubility of the polyimide was good. A colorless and transparent flexible film having a thickness of 100 μm was obtained in the same manner as in Synthesis Example 1 at a polymer concentration of 20.0%. When the IR spectrum of this film was measured, the characteristic absorption of the imide ring of ν (C═O) 1772 and 1706 cm ⁻¹ was recognized, and the formation of polyimide was confirmed. (Referred to as polyimide HPMDA-HAB).

Synthesis Example 3 From 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 2,2-bis [4- (4-aminophenoxy) phenyl] propane and methylenebis [4-amino-2-benzoic acid] Preparation of Polyimide In a 300 ml 5-neck glass round bottom flask, 0.058 mol of 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP), methylenebis [4-amino-2- Benzoic acid] (MBAA) 0.058 mol, γ-butyrolactone 78.0 g, weighed stainless steel half-moon stirrer, nitrogen inlet tube, Dean Stark fitted with cooling tube, thermometer, glass end cap The solution was stirred and dissolved at 100 rpm in a nitrogen atmosphere. To this, 0.116 mol of 1,2,4,5-cyclohexanetetracarboxylic dianhydride (HPMDA) and 16.3 g of dimethylacetamide were added, a mantle heater was attached to the flask, and the temperature in the reaction system was raised to 180 ° C. . The component to be distilled off was collected and left in that state for 2 hours. After adding 118.7 g of dimethylacetamide, the mantle heater was removed and air-cooled to obtain a polyimide varnish having a solid content concentration of 20 wt% (referred to as polyimide HPMDA-BAPP-MBAA).

Synthesis Example 4 Production of polyimide from 1,2,4,5-cyclohexanetetracarboxylic dianhydride and 4,4'-diaminodiphenyl ether Thermometer, stirrer, nitrogen introduction tube, rectification column, Liebig condenser In a 300 ml five-necked flask, 7.0 g of N, N-dimethylacetamide, 27.8 g of γ-butyrolactone, 0.25 g (0.0025 mol) of triethylamine, 1,2,4,5-cyclohexane under a nitrogen stream Tetracarboxylic dianhydride 11.32 g (0.05 mol) and 4,4′-diaminodiphenyl ether 10.06 g (0.05 mol) were charged. The temperature was raised to 180 ° C. with stirring, and the temperature was maintained for 3 hours. While the temperature was raised to 180 ° C., a distillate component containing water as a main component was separated and recovered. Thereafter, the mixture was air-cooled until the internal temperature reached 150 ° C., 30.0 g of N, N-dimethylacetamide was added, and the mixture was stirred until it became uniform. The reaction solution was uniformly transparent and the solubility of the polyimide was good. At a polymer concentration of 23.2%, the obtained solution was applied to a glass plate, dried on a hot plate at 100 ° C. for 1 hour, then peeled off from the glass plate to obtain a self-supporting film, and fixed to a stainless steel fixing jig. And dried in a hot air dryer at 220 ° C. for 2 hours to obtain a colorless and transparent flexible film having a thickness of 100 μm. When the IR spectrum of this film was measured, the characteristic absorption of the imide ring of ν (C═O) 1772, 1700 cm ⁻¹ was recognized, and the formation of polyimide was confirmed. The film had a glass transition temperature of 307 ° C. (DSC), a thermal decomposition starting temperature of 479 ° C. (DTG), a total light transmittance of 89%, and a logarithmic viscosity of 0.95 dl / g. To this, 111.4 g of dimethyl sulfoxide was added to adjust the polymer concentration to 10% (referred to as polyimide HPMDA-ODA).

Synthesis Example 5 Preparation of polyimide of 1,2,4,5-cyclohexanetetracarboxylic dianhydride and 2,2-bis [4- (4-aminophenoxy) phenyl] propane 4,4 used in Example 4 Example 1 except that 20.63 g (0.05 mol) of 2,2-bis [4- (4-aminophenoxy) phenyl] propane was used in place of '-diaminodiphenyl ether and the retention time was 4 hours. A polyimide was synthesized in the same manner. The reaction solution was uniformly transparent and the solubility of the polyimide was good. A colorless and transparent flexible film having a thickness of 100 μm was obtained in the same manner as in Synthesis Example 1 at a polymer concentration of 31.8%. When the IR spectrum of this film was measured, the characteristic absorption of the imide ring of ν (C═O) 1772 and 1706 cm ⁻¹ was recognized, and the formation of polyimide was confirmed. The film had a glass transition temperature of 259 ° C. (DSC), a thermal decomposition starting temperature of 484 ° C. (DTG), a total light transmittance of 88%, and a logarithmic viscosity of 0.89 dl / g. To this, 206.6 g of dimethyl sulfoxide was added to adjust the polymer concentration to 10% (referred to as polyimide HPMDA-BAPP).

Polymerization Example 1 Copolymerization of a monomer having an acidic group and a monomer having a basic group 10.4 g (0.05 mol) of 2-acrylamido-2-methylpropanesulfonic acid, 3.6 g (0.05 mol) of acrylamide (acidic group) Ratio of functional group equivalents of monomer having a basic group and monomer having a basic group: 50/50), 105.6 g of dimethyl sulfoxide (DMSO) and 2% dimethyl sulfoxide of polymerization initiator azobisisobutyronitrile 20 g of the solution was charged into a 200 ml separable flask equipped with a stirrer and a cooling tube, and polymerized at a polymerization temperature of 70 ° C. for 5 hours while blowing nitrogen gas. This was polymer A, and a light yellow transparent and viscous liquid was obtained at a polymer concentration of 10%. Used in Example 1.

Polymerization Example 2 Copolymerization of a monomer having an acidic group quaternary ammonium and a monomer having a basic group 10.4 g (0.05 mol) of 2-acrylamido-2-methylpropanesulfonic acid, 3.6 g of acrylamide ( 0.05 mol) (ratio of the number of functional group equivalents of the monomer having an acidic group and the monomer having a basic group: 50/50) and 6.1 g (0.06 mol) of triethylamine were charged in the same apparatus as in Polymerization Example 1. The same polymerization operation was performed to obtain a 10% DMSO solution with a light brown color. This was designated as Polymer B and used in Example 2.

Polymerization Example 3 Copolymerization of a monomer having an acidic group with a quaternary ammonium salt and a monomer having a basic group 10.4 g (0.05 mol) of 2-acrylamido-2-methylpropanesulfonic acid, 3.56 g of acrylamide ( 0.05 mol) (ratio of functional group equivalent number of monomer having acidic group and monomer having basic group: 50/50), 0.27 g (0.05 mol) of tributylamine and 1.30 g of 2-hydroxyethyl methacrylate ( 0.01 mol) and 40 g of DMSO as a solvent, and dissolved in a dropping funnel. A 200 ml separable flask as in Example 1 was charged with 48 g of DMSO, heated to a polymerization temperature of 70 ° C. while blowing nitrogen gas, and a 2% DMSO solution of the monomer solution in the dropping funnel and the polymerization initiator azobisisobutyronitrile. 20 g was added to the polymerization flask over 1 hour, and then the polymerization reaction was continued for 4 hours. A yellow transparent and viscous liquid was obtained at a polymer concentration of 20.0%. To this, 134.6 g of dimethyl sulfoxide was added to adjust the polymer concentration to 10%. Used in Examples 3 and 4.

Example 1 Production of a solid polymer electrolyte membrane (cast film)
4.0 g of Polymer A obtained in Polymerization Example 1 and 4.0 g of polyimide HPMDA-ODA-MBAA solution obtained in Synthesis Example 1 and 8.0 g of dimethyl sulfoxide (DMSO) were added and stirred to obtain a homogeneous solution. (Total polymer concentration 5.0%). Pericot S was thinly applied to one side of the glass plate as an external mold release agent, and the surface was turned upside down to form a weir around 0.5 mm thick Teflon (registered trademark) rubber and adjusted in this enclosure. The mixed solution was poured gently and allowed to stand on a horizontal hot plate. The hot plate temperature was raised from 70 ° C. to 120 ° C. over 6 hours to obtain an electrolyte membrane having a thickness of 27 μm. Next, platinum electrodes were mounted on both sides of the membrane, and the ionic conductivity was measured. As a result, it was 1.4 × 10 ⁻² S / cm. The methanol transmission rate was 4.5 mg / cm ² / min, and the methanol transmission rate was 12 μg / cm · min.

Example 2 Production of a solid polymer electrolyte membrane (cast film)
5.0 g of the polymer B obtained in Polymerization Example 2, 5.0 g of the polyimide HPMDA-ODA-MBAA solution obtained in Synthesis Example 1 and 10.0 g of DMSO were added and stirred to obtain a homogeneous solution (total polymer concentration 5.0% ). Thereafter, the same operation as in Example 1 was performed to obtain a cast film. This was immersed in a 5% aqueous sulfuric acid solution overnight and then thoroughly washed with water to obtain an electrolyte membrane. The film thickness was 30 μm. Platinum electrodes were mounted on both sides of the membrane, and ionic conductivity was measured. As a result, it was 1.1 × 10 ⁻² S / cm. Next, the methanol permeability was determined and found to be 29 μg / cm · min.

Example 3 Production of a solid polymer electrolyte membrane (cast film)
Polymer C (5.0 g) obtained in Polymerization Example 3 and polyimide HPMDA-ODA-MBAA solution (5.0 g) obtained in Synthesis Example 1 and DMSO (10.0 g) were added and stirred to obtain a uniform solution (total polymer concentration 5.0% ). Thereafter, the same operation as in Example 2 was performed to obtain a film having a thickness of 40 μm. This membrane was immersed in 0.5 mol sulfuric acid for one day and then thoroughly washed with water to obtain a solid polymer electrolyte membrane. The ion conductivity of this membrane was 4.9 × 10 ⁻³ S / cm, and the methanol permeability was determined to be 9 μg / cm · min.

Example 4 Production of a solid polymer electrolyte membrane (cast film)
5.0 g of the polymer C obtained in Polymerization Example 3 and 5.0 g of the polyimide HPMDA-HAB solution obtained in Synthesis Example 2 and 10.0 g of dimethyl sulfoxide were added and stirred to obtain a uniform solution (total polymer concentration of 5. 0%). Thereafter, the same operation as in Example 2 was performed to obtain a film having a thickness of 50 μm. This membrane was immersed in 0.5 mol sulfuric acid for one day and then thoroughly washed with water to obtain a solid polymer electrolyte membrane. The ion conductivity of this membrane was 3.3 × 10 ⁻² S / cm, and the methanol permeability was 30 μg / cm · min.

Comparative Example 1 Production of a solid polymer electrolyte membrane (cast film)
8.5 g of the polymer C obtained in Polymerization Example 3, 1.5 g of the polyimide HPMDA-BAPP-MBAA solution obtained in Synthesis Example 1 and 10.0 g of dimethyl sulfoxide (DMSO) were added and stirred to obtain a uniform solution ( Total polymer concentration 5.0%). Thereafter, the same operation as in Example 2 was performed to obtain a film having a thickness of 55 μm. After this membrane was immersed in 0.5 mol sulfuric acid, the membrane became tattered and did not become a self-supporting membrane.

Polymerization Example 4 Copolymerization of a monomer having an acidic group quaternary ammonium and a monomer having a basic group 2-acrylamido-2-methylpropanesulfonic acid 20.7 g (0.1 mol), acrylamide 3.6 g ( 0.05 mol) (ratio of functional group equivalent number of monomer having acidic group and monomer having basic group: 67/33), 10.2 g (0.1 mol) of triethylamine and 1.95 g of 2-hydroxyethyl methacrylate (0 .015 mol) and 40 g of DMSO as a solvent, and charged in a dropping funnel. Thereafter, the same operation as in Polymerization Example 2 was performed to obtain a light yellow polymer solution. DMSO128.7g was added to this, and it was set as the uniform solution with a polymer concentration of 10%. This was designated as Polymer D and used in Example 5.

Polymerization Example 5 Copolymerization of a monomer having an acidic group with a quaternary ammonium salt and a monomer having a basic group 10.4 g (0.05 mol) of 2-acrylamido-2-methylpropanesulfonic acid, 7.1 g of acrylamide ( 0.1 mol) (ratio of functional group equivalent number of monomer having acidic group and monomer having basic group: 33/67), 5.1 g (0.05 mol) of triethylamine and 1.95 g of 2-hydroxyethyl methacrylate (0 .015 mol) and 40 g of DMSO as a solvent, and charged in a dropping funnel. Thereafter, the same procedure as in Polymerization Example 2 was performed to obtain a light yellow polymer solution. DMSO 67.1g was added to this, and it was set as the uniform solution with a polymer concentration of 10%. This was designated as Polymer E and used in Example 6.

Example 5 Production of a solid polymer electrolyte membrane (cast film)
Polymer D (5.0 g) obtained in Polymerization Example 4 and polyimide HPMDA-ODA-MBAA solution (5.0 g) obtained in Synthesis Example 1 and DMSO (10.0 g) were added and stirred to obtain a uniform solution (total polymer concentration 5.0% ). Thereafter, the same operation as in Example 2 was performed to obtain a film having a thickness of 42 μm. This membrane was immersed in 0.5 mol sulfuric acid for one day and then thoroughly washed with water to obtain a solid polymer electrolyte membrane. The ion conductivity of this membrane was 1.5 × 10 ⁻² S / cm, and the methanol permeability was 28 μg / cm · min.

Example 6 Production of a solid polymer electrolyte membrane (cast film)
Polymer E 5.0 g obtained in Polymerization Example 5 and 5.0 g of polyimide HPMDA-BAPP-MBAA solution obtained in Synthesis Example 3 and 10.0 g of dimethyl sulfoxide were added and stirred to obtain a uniform solution (total polymer concentration 5.0%). Thereafter, the same operation as in Example 2 was performed to obtain a film having a thickness of 53 μm. This membrane was immersed in 0.5 mol sulfuric acid for one day and then thoroughly washed with water to obtain a solid polymer electrolyte membrane. The ion conductivity of this membrane was 3 × 10 ⁻³ S / cm, and the methanol permeability was 22 μg / cm · min.

Comparative Example 2 Polymerization of Monomer Having Quaternary Ammonium Monomer having Acid Group 2-acrylamido-2-methylpropanesulfonic acid 20.7 g (0.1 mol), (of monomer having acid group and monomer having basic group Ratio of functional group equivalent number: 100/0), 10.1 g (0.1 mol) of triethylamine and 1.3 g (0.01 mol) of 2-hydroxyethyl methacrylate and 68 g of DMSO as a solvent, and 2% -azobisisobutyronitrile -DMSO solution 20.0g was added to a 200 ml separable flask, and a polymerization reaction was performed at 60 ° C for 6 hours to obtain a slightly yellow viscous polymer solution. To this polymer solution, 110.0 g of DMSO was added to obtain a uniform solution having a polymer concentration of 10%. This was designated as Polymer F and used in Comparative Example 3.

Comparative Example 3 Production of a solid polymer electrolyte membrane (cast film)
5.0 g of the polymer F obtained in Comparative Example 2, 5.0 g of the polyimide HPMDA-ODA-MBAA solution obtained in Synthesis Example 1 and 10.0 g of dimethyl sulfoxide were added and stirred to obtain a uniform solution (total polymer concentration 5.0%). Thereafter, the same operation as in Example 2 was performed to obtain a film having a thickness of 38 μm. This membrane was immersed in 0.5 mol sulfuric acid for one day and then thoroughly washed with water to obtain a solid polymer electrolyte membrane. The ion conductivity of this membrane was 1.5 × 10 ⁻³ S / cm, and the methanol permeation rate was 84 μg / cm · min.

Polymerization Example 6 Copolymerization of a monomer having an acidic group and a monomer having a basic group 10.4 g (0.05 mol) of 2-acrylamido-2-methylpropanesulfonic acid, 2.85 g (0.05 mol) of allylamine (acidic group) The ratio of the functional group equivalent number of the monomer having a basic group and the monomer having a basic group: 50/50), DMSO 52 g and polymerization initiator azobisisobutyronitrile 0.04 g were charged into a 200 ml separable flask and nitrogen gas was blown into the flask. Polymerization was performed at a polymerization temperature of 50 ° C. for 4 hours to obtain a colorless, transparent and viscous liquid. DMSO 67.3g was added to this, and it was set as the 10% polymer solution. This was designated as Polymer G and used in Example 7.

Example 7 Production of a solid polymer electrolyte membrane (cast film)
4.0 g of the polymer G obtained in Polymerization Example 6, 6.0 g of the polyimide HPMDA-HAB solution obtained in Synthesis Example 2 and 10.0 g of DMSO were added and stirred to obtain a uniform solution (total polymer concentration 5.0%). Thereafter, the same operation as in Example 1 was performed to obtain a film having a thickness of 56 μm. As a result of mounting platinum electrodes on both sides of this membrane and measuring ionic conductivity, the ionic conductivity was 1.9 × 10 ⁻⁴ S / cm, and the methanol permeation rate in a 30% aqueous methanol solution was 11 μg / cm · min.

Polymerization Example 7 Copolymerization of Monomer Having Acid Group and Monomer Having Basic Group Allylamine of Polymerization Example 6 was converted to 5.55 g (0.05 mol) of 1-vinyl-2-pyrrolidone (monomer having acidic group and basic group) Polymerization product was obtained in the same manner as in Polymerization Example 6 except that the ratio of the number of functional group equivalents of the monomer having a ratio was changed to 50/50). A colorless transparent viscous liquid was obtained at a polymer concentration of 23.5%. DMSO 91.3g was added to this to make a 10% polymer solution. This was designated as Polymer H and used in Example 8.

Example 8 Production of a solid polymer electrolyte membrane (cast film)
4.5 g of the polymer H obtained in Polymerization Example 7 and 5.5 g of the polyimide HPMDA-ODA-MBAA solution obtained in Synthesis Example 1 and 10.0 g of DMSO were added and stirred to obtain a uniform solution (total polymer concentration 5.0% ). Thereafter, the same operation as in Example 1 was performed to obtain a film having a film thickness of 49 μm. The ion conductivity of the membrane was 9.7 × 10 ⁻⁴ S / cm, and the methanol permeation rate in a 30% aqueous methanol solution was measured. As a result, it was 8 μg / cm · min.

Polymerization Example 8 Copolymerization of Monomer Having Acidic Group and Monomer Having Basic Group 1.70 g (0.05 mol) of 1-vinylimidazole in Polymerization Example 7 (Monomer Having Acidic Group) A polymerization product was obtained in the same manner as in Polymerization Example 7 except that the ratio of the functional group equivalent number of the monomer having a basic group was changed to 50/50). A colorless transparent viscous liquid was obtained with a polymer concentration of 22.5%. DMSO 83.9g was added to this, and it was set as the 10% polymer solution. This was designated as Polymer I and used in Example 9.

Example 9 Production of a solid polymer electrolyte membrane (cast film)
4.5 g of the polymer I obtained in Polymerization Example 8 and 5.5 g of the polyimide HPMDA-ODA-MBAA solution obtained in Synthesis Example 1 and 10.0 g of DMSO were added and stirred to obtain a homogeneous solution (total polymer concentration 5.0% ). Thereafter, the same operation as in Example 1 was performed to obtain an electrolyte membrane. The obtained membrane (film thickness: 65 μm) had an ionic conductivity of 1.5 × 10 ⁻⁴ S / cm, and the methanol permeability in a 30% aqueous methanol solution was 0.2 μg / cm · min. .

Polymerization Example 9 Copolymerization of a monomer having an acidic group and a monomer having a basic group 9.21 g (0.05 mol) of styrene sulfonic acid and 3.56 g (0.05 mol) of acrylamide (monomer having an acidic group and basic group The ratio of the number of functional group equivalents of the monomer having: 50/50) 2-hydroxyethyl methacrylate 1.30 g (0.01 mol), DMSO 56.3 g and polymerization initiator azobisisobutyronitrile 0.2 g The flask was charged and polymerized at a polymerization temperature of 60 ° C. for 4 hours while blowing nitrogen gas. After completion of the polymerization, 70.4 g of DMSO was added to make a 10% by weight polymer concentration solution. A pale yellow transparent viscous liquid was obtained, which was referred to as Polymer J and used in Example 10.

Example 10 Production of a solid polymer electrolyte membrane (cast film)
4.5 g of the polymer J obtained in Polymerization Example 9, 5.5 g of the polyimide HPMDA-ODA-MBAA solution obtained in Synthesis Example 1 and 10.0 g of DMSO were added and stirred to obtain a homogeneous solution (total polymer concentration 5.0% ). Thereafter, the same operation as in Example 1 was performed to obtain an electrolyte membrane. The obtained membrane (film thickness: 60 μm) had an ionic conductivity of 3.3 × 10 ⁻³ S / cm, and a methanol permeability in a 30% aqueous methanol solution was 10 μg / cm · min.

Polymerization Example 10 Copolymerization of a monomer having an acidic group and a monomer having a basic group 10.4 g (0.05 mol) of 2-acrylamido-2-methylpropanesulfonic acid, 3.6 g (0.05 mol) of acrylamide (acidic group) The ratio of the number of functional group equivalents of the monomer having a basic group and the monomer having a basic group: 50/50), 0.53 g (0.01 mol) of acrylonitrile, 38.1 g of DMSO, and 2 of polymerization initiator azobisisobutyronitrile 20 g of a 20% aqueous solution was charged into a 200 ml separable flask equipped with a stirrer and a condenser, and polymerized at a polymerization temperature of 60 ° C. for 5 hours while blowing nitrogen gas. Thereafter, 72.7 g of DMSO was added to give a polymer concentration of 10%. An almost colorless and transparent viscous liquid was obtained. This was designated as Polymer K and used in Example 11.

Example 11 Production of a solid polymer electrolyte membrane (cast film)
4.5 g of the polymer K obtained in Polymerization Example 10 and 5.5 g of the polyimide HPMDA-ODA-MBAA solution obtained in Synthesis Example 1 and 10.0 g of dimethyl sulfoxide were added and stirred to obtain a uniform solution (total polymer concentration 5.0%). Thereafter, the same operation as in Example 1 was performed to obtain an electrolyte membrane. The obtained membrane (thickness 55 μm) had an ionic conductivity of 2.1 × 10 ⁻³ S / cm, and a methanol permeability in a 30% aqueous methanol solution was 7 μg / cm · min.

Example 12 Production of a solid polymer electrolyte membrane (cast film)
4.0 g of Polymer A obtained in Polymerization Example 1 and 4.0 g of the polyimide HPMDA-ODA solution obtained in Synthesis Example 4 and 8.0 g of dimethyl sulfoxide were added and stirred to obtain a uniform solution (total polymer concentration 5.0%). Pericot S was thinly applied to one side of the glass plate as an external mold release agent, and the surface was turned upside down to form a weir around 0.5 mm thick Teflon (registered trademark) rubber and adjusted in this enclosure. The mixed solution was poured gently and allowed to stand on a horizontal hot plate. The hot plate temperature was raised from 70 ° C. to 120 ° C. over 6 hours to obtain an electrolyte membrane having a thickness of 45 μm. Next, platinum electrodes were mounted on both sides of this membrane, and the ionic conductivity was measured. As a result, it was 3.1 × 10 ⁻³ S / cm. The methanol transmission rate was 4.5 mg / cm ² / min, and the methanol permeability was 20 μg / cm · min.

Example 13 Production of a solid polymer electrolyte membrane (cast film)
Polymer B (5.0 g) obtained in Polymerization Example 2, 5.0 g of the polyimide HPMDA-ODA solution obtained in Synthesis Example 4 and 10.0 g of dimethyl sulfoxide were added and stirred to obtain a uniform solution (total polymer concentration of 5. 0%). Thereafter, the same operation as in Example 12 was performed to obtain an electrolyte membrane. The film thickness was 52 μm. Platinum electrodes were mounted on both sides of the membrane, and ionic conductivity was measured. As a result, it was 2.8 × 10 ⁻³ S / cm. Next, as a result of measuring the methanol permeation rate, it was 4.0 mg / cm ² / min, and the methanol permeability was 21 μg / cm · min.

Example 14 Production of a solid polymer electrolyte membrane (cast film)
5.0 g of the polymer C obtained in Polymerization Example 3 and 5.0 g of the polyimide HPMDA-ODA solution obtained in Synthesis Example 4 and 10.0 g of dimethyl sulfoxide were added and stirred to obtain a uniform solution (total polymer concentration of 5. 0%). Thereafter, the same operation as in Example 12 was performed to obtain a film having a thickness of 46 μm. This membrane was immersed in 0.5 mol sulfuric acid for one day and then thoroughly washed with water to obtain a solid polymer electrolyte membrane. The ion conductivity of this membrane was 3.9 × 10 ⁻³ S / cm, the methanol permeation rate was 3.4 mg / cm ² / min, and the methanol permeability was 16 μg / cm · min. The mechanical tensile strength of this film was 230 kgf / cm ² .

Example 15 Production of solid polymer electrolyte membrane (cast film)
5.0 g of the polymer C obtained in Polymerization Example 3 and 5.0 g of the polyimide HPMDA-BAPP solution obtained in Synthesis Example 5 and 10.0 g of dimethyl sulfoxide were added and stirred to obtain a uniform solution (total polymer concentration of 5. 0%). Thereafter, the same operation as in Example 12 was performed to obtain a film having a thickness of 58 μm. This membrane was immersed in 0.5 mol sulfuric acid for one day and then thoroughly washed with water to obtain a solid polymer electrolyte membrane. The membrane had an ionic conductivity of 3.3 × 10 ⁻³ S / cm, a methanol permeation rate of 3.3 mg / cm ² / min, and a methanol permeability of 19 μg / cm · min. The tensile strength was 180 kgf / cm ² .

Example 16 Production of a solid polymer electrolyte membrane (cast film)
3.0 g of the polymer C obtained in Polymerization Example 3, 7.0 g of the polyimide HPMDA-ODA solution obtained in Synthesis Example 4 and 10.0 g of dimethyl sulfoxide were added and stirred to obtain a uniform solution (total polymer concentration of 5. 0%). Thereafter, the same operation as in Example 12 was performed to obtain a film having a thickness of 30 μm. This membrane was immersed in 0.5 mol sulfuric acid for one day and then thoroughly washed with water to obtain a solid polymer electrolyte membrane. The ion conductivity of this membrane was 1.3 × 10 ⁻³ S / cm, the methanol permeation rate was 2.4 mg / cm ² / min, and the methanol permeability was 7 μg / cm · min.

Example 17 Production of a solid polymer electrolyte membrane (cast film)
Polymer D 5.0 g obtained in Polymerization Example 4 and 5.0 g of polyimide HPMDA-ODA solution obtained in Synthesis Example 4 and 10.0 g of dimethyl sulfoxide were added and stirred to obtain a uniform solution (total polymer concentration 5. 0%). Thereafter, the same operation as in Example 12 was performed to obtain a film having a thickness of 42 μm. This membrane was immersed in 0.5 mol sulfuric acid for one day and then thoroughly washed with water to obtain a solid polymer electrolyte membrane. The ion conductivity of this membrane was 2.5 × 10 ⁻³ S / cm, the methanol permeation rate was 4.8 mg / cm ² / min, and the methanol permeability was 20 μg / cm · min.

Example 18 Production of a solid polymer electrolyte membrane (cast film)
5.0 g of the polymer E obtained in Polymerization Example 5 and 5.0 g of the polyimide HPMDA-ODA solution obtained in Synthesis Example 4 and 10.0 g of dimethyl sulfoxide were added and stirred to obtain a uniform solution (total polymer concentration of 5. 0%). Thereafter, the same operation as in Example 12 was performed to obtain a film having a film thickness of 53 μm. This membrane was immersed in 0.5 mol sulfuric acid for one day and then thoroughly washed with water to obtain a solid polymer electrolyte membrane. The ion conductivity of this membrane was 1.3 × 10 ⁻³ S / cm, the methanol permeation rate was 4.1 mg / cm ² / min, and the methanol permeability was 22 μg / cm · min.

Example 19 Production of a solid polymer electrolyte membrane (cast film)
4.0 g of the polymer G obtained in Polymerization Example 6 and 6.0 g of the polyimide HPMDA-BAPP solution obtained in Synthesis Example 5 and 10.0 g of dimethyl sulfoxide were added and stirred to obtain a uniform solution (total polymer concentration of 5. 0%). Thereafter, the same operation as in Example 12 was performed to obtain a film having a thickness of 56 μm. As a result of mounting platinum electrodes on both sides of this membrane and measuring the ionic conductivity, the ionic conductivity was 1.9 × 10 ⁻⁴ S / cm, and the methanol permeation rate in a 30% aqueous methanol solution was 1.5 mg / The methanol permeability was 8 μg / cm · min at cm ² / min.

Example 20 Production of a solid polymer electrolyte membrane (cast film)
4.5 g of the polymer H obtained in Polymerization Example 7, 5.5 g of the polyimide HPMDA-ODA solution obtained in Synthesis Example 4 and 10.0 g of dimethyl sulfoxide were added and stirred to obtain a uniform solution (total polymer concentration of 5. 0%). Thereafter, the same operation as in Example 12 was performed to obtain a film having a thickness of 49 μm. The ionic conductivity of the membrane was 9.7 × 10 ⁻⁴ S / cm, and the methanol permeation rate in a 30% methanol aqueous solution was measured. As a result, it was 1.7 mg / cm ² / min, and the methanol permeability was 8 μg / cm · min.

Example 21 Production of a solid polymer electrolyte membrane (cast film)
4.5 g of the polymer I obtained in Polymerization Example 8, 5.5 g of the polyimide HPMDA-ODA solution obtained in Synthesis Example 4 and 10.0 g of dimethyl sulfoxide were added and stirred to obtain a uniform solution (total polymer concentration of 5. 0%). Thereafter, the same operation as in Example 4 was performed to obtain an electrolyte membrane. The ionic conductivity of the obtained membrane (film thickness 65 μm) was 1.5 × 10 ⁻⁴ S / cm, and as a result of measuring the methanol permeation rate in a 30% aqueous methanol solution, 1.2 mg / cm ² / min, The methanol permeability was 10 μg / cm · min.

Example 22 Production of a solid polymer electrolyte membrane (cast film)
4.5 g of the polymer J obtained in Polymerization Example 9, 5.5 g of the polyimide HPMDA-ODA solution obtained in Synthesis Example 4 and 10.0 g of dimethyl sulfoxide were added and stirred to obtain a uniform solution (total polymer concentration of 5. 0%). Thereafter, the same operation as in Example 12 was performed to obtain an electrolyte membrane. The ionic conductivity of the obtained membrane (film thickness 60 μm) was 3.3 × 10 ⁻³ S / cm, and as a result of measuring the methanol permeation rate in a 30% aqueous methanol solution, it was 1.7 mg / cm ² / min. The methanol permeability was 10 μg / cm · min.

Example 23 Production of solid polymer electrolyte membrane (cast film)
4.5 g of the polymer K obtained in Polymerization Example 10 and 5.5 g of the polyimide HPMDA-ODA solution obtained in Synthesis Example 4 and 10.0 g of dimethyl sulfoxide were added and stirred to obtain a uniform solution (total polymer concentration of 5. 0%). Thereafter, the same operation as in Example 12 was performed to obtain an electrolyte membrane. The ionic conductivity of the obtained membrane (film thickness 55 μm) was 2.1 × 10 ⁻³ S / cm, and as a result of measuring the methanol permeation rate in a 30% aqueous methanol solution, 1.3 mg / cm ² / min, The methanol permeability was 7 μg / cm · min.

Comparative Example 4 Production of solid polymer electrolyte membrane (cast film)
8.5 g of the polymer C obtained in Polymerization Example 3 and 1.5 g of the polyimide HPMDA-ODA solution obtained in Synthesis Example 4 and 10.0 g of dimethyl sulfoxide were added and stirred to obtain a uniform solution (total polymer concentration of 5. 0%). Thereafter, the same operation as in Example 12 was performed to obtain a film having a thickness of 55 μm. After this membrane was immersed in 0.5 mol sulfuric acid, the membrane became tattered and did not become a self-supporting membrane.

Comparative Example 5 Production of solid polymer electrolyte membrane (cast film)
0.8 g of the polymer C obtained in Polymerization Example 3, 9.8 g of the polyimide HPMDA-ODA solution obtained in Synthesis Example 4 and 10.0 g of dimethyl sulfoxide were added and stirred to obtain a uniform solution (total polymer concentration of 5. 0%). Thereafter, the same operation as in Example 12 was performed to obtain a film having a thickness of 48 μm. The membrane was immersed in 0.5 mol sulfuric acid and washed with water, and the ionic conductivity of the membrane was 1 × 10 ⁻⁶ S / cm.

Comparative Example 6 Polymerization of Monomer Having Acidic Group Monomer Quaternized Ammonium 2-acrylamido-2-methylpropanesulfonic acid 20.7 g (0.1 mol), (monomer having acidic group and monomer having basic group Ratio of functional group equivalent number: 100/0), 10.1 g (0.1 mol) of triethylamine and 1.3 g (0.01 mol) of 2-hydroxyethyl methacrylate and 68 g of DMSO as a solvent, and 2% -azobisisobutyronitrile -Dimethyl sulfoxide solution 20.0g was added to the 200 ml separable flask, and the polymerization reaction was performed at 60 degreeC for 6 hours, and the slightly yellow viscous polymer solution was obtained. To this polymer solution, 110.0 g of dimethylformamide was added to obtain a uniform solution having a polymer concentration of 10%. This was designated as Polymer L and used in Comparative Example 7.

Comparative Example 7 Production of solid polymer electrolyte membrane (cast film)
5.0 g of the polymer L obtained in Comparative Example 6, 5.0 g of the polyimide HPMDA-ODA solution obtained in Synthesis Example 4 and 10.0 g of dimethyl sulfoxide were added and stirred to obtain a uniform solution (total polymer concentration 5. 0%). Thereafter, the same operation as in Example 12 was performed to obtain a film having a thickness of 38 μm. This membrane was immersed in 0.5 mol sulfuric acid for one day and then thoroughly washed with water to obtain a solid polymer electrolyte membrane. The ion conductivity of this membrane was 1.5 × 10 ⁻³ S / cm, the methanol permeation rate was 10.0 mg / cm ² / min, and the methanol permeability was 38 μg / cm · min.

Claims (9)

A solid polymer electrolyte obtained by mixing an electrolyte polymer obtained by copolymerizing a monomer having an acidic group or a monomer having an acidic group with a quaternary ammonium salt and a monomer having a basic group, with a polyimide, A solid polymer electrolyte that satisfies the following conditions (a) and (b):
(A) the monomer having an acidic group is a monomer having at least one selected from the group consisting of a sulfonic acid group, a phosphonic acid group, and a carboxyl group;
(B) The monomer having basicity is a monomer having at least one selected from the group consisting of an amino group, an amide group, and a urea group.   The mixing ratio (electrolyte polymer weight / polyimide weight) of an electrolyte polymer obtained by copolymerizing a monomer having an acidic group or a monomer having an acidic group quaternary ammonium and a monomer having a basic group with a polyimide is 10 The solid polymer electrolyte according to claim 1, which is in the range of / 90 to 80/20.   The solid polymer electrolyte according to claim 1 or 2, wherein the polyimide has a hydroxyl group and / or a carboxyl group.   A monomer having an acidic group or a monomer having an acidic group that has been converted to a quaternary ammonium salt is acrylamidomethylpropanesulfonic acid, styrenesulfonic acid, vinylsulfonic acid, (meth) allylsulfonic acid, acid phosphohydroxyethyl methacrylate, (meta The solid polymer electrolyte according to any one of claims 1 to 3, which is acrylic acid, maleic anhydride, fumaric acid, or a quaternary ammonium salt of these monomers.   The monomer having a basic group is acrylamide, allylamine, vinylpyrrolidone, vinylimidazole, aminoacrylamide, aminosulfone, vinylpyridine, dimethylaminoethyl (meth) acrylate, vinylcaprolactam, vinylcarbazole, vinyldiaminotriazine or ethyleneimine Item 5. The solid polymer electrolyte according to any one of Items 1 to 4.   The electrolyte polymer is obtained by copolymerization by adding a neutral monomer to a monomer having an acidic group or a monomer having an acidic group and a monomer having a quaternary ammonium group and a monomer having a basic group. The solid polymer electrolyte according to any one of 1 to 5.   The solid polymer electrolyte according to claim 6, wherein the neutral monomer is 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, styrene, acrylonitrile, or polyethylene glycol di (meth) acrylate. The polyimide is a solvent comprising at least one selected from the tetracarboxylic dianhydrides and tetracarboxylic acids shown in the following (c) and at least one selected from the diamine compounds shown in the following (d) The solid polymer electrolyte according to any one of claims 1 to 7, which is obtained by polycondensation inside.
(C) 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclopentanetetracarboxylic dianhydride Bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic acid, 1,2,3 4-cyclobutanetetracarboxylic acid, 1,2,4,5-cyclopentanetetracarboxylic acid, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic acid (d) 2 2,2'-dihydroxy-4,4'-diaminodiphenylene, methylenebis [4-amino-2-benzoic acid], 4,4'-diaminodiphenyl ether, 2,2-bis [4- (4-aminophenoxy) Phenyl] Pro Emissions, 1,4-bis (4-aminophenoxy) benzene, 4,4'-diaminodicyclohexylmethane   A solid polymer electrolyte membrane formed by forming the solid polymer electrolyte according to claim 1.