JP5552785B2 - Solid polymer electrolyte membrane, method for producing the same, and liquid composition - Google Patents

Description

  The present invention relates to a novel solid polymer electrolyte membrane, a method for producing the same, and a liquid composition used for forming the solid polymer electrolyte membrane.

  A fuel cell is a power generator that directly extracts electricity by electrochemically reacting hydrogen obtained by reforming hydrogen gas or various hydrocarbon fuels (natural gas, methane, etc.) and oxygen in the air. It is attracting attention as a pollution-free power generation system that can directly convert the chemical energy of fuel into electrical energy with high efficiency.

  Such a fuel cell is composed of a pair of electrode membranes (anode electrode and cathode electrode) carrying a catalyst and a proton conductive solid polymer electrolyte membrane (hereinafter also referred to as a proton conductive membrane) sandwiched between the electrode membranes. Composed. The anode electrode catalyst separates hydrogen ions and electrons. The hydrogen ions pass through the solid polymer electrolyte membrane and react with oxygen at the air electrode to become water.

  Commercially available solid polymer electrolyte membranes under the trade names Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Kogyo Co., Ltd.), Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.) Fluorocarbon polymer electrolyte membrane with sulfonic acid group, aromatic hydrocarbon polymer system, polyether ether ketone system, polyphenylene sulfide system, polyimide system, polybenzazole system aromatic ring as main chain skeleton And an aromatic hydrocarbon polymer electrolyte membrane having a sulfonic acid group has been proposed.

  By the way, in such a fuel cell, there is a concern that the solid polymer electrolyte membrane may be deteriorated by hydrogen peroxide or a peroxide radical generated by a reduction reaction of oxygen. Further, since oxygen molecules permeate through the membrane, there is a concern that hydrogen peroxide or peroxide radicals may be generated in the same manner to cause deterioration of the solid polymer electrolyte membrane.

  In order to solve such problems, it has been proposed to include cerium ions in an ion exchange membrane made of a polymer compound having a sulfonic acid group (Patent 3915846, Patent Document 1). In addition, it has also been proposed to include a sparingly soluble cerium compound such as cerium oxide together with a polymer compound having a sulfonic acid group (Japanese Patent Laid-Open No. 2006-107914, Patent Document 2).

  Conventionally, in order to decompose such hydrogen peroxide, it is also known to provide a peroxide decomposition layer in which a catalyst such as platinum or ruthenium is supported on inorganic oxide particles (Japanese Patent Laid-Open No. 2006-2006). 79904, Patent Document 3)

Patent No. 3915846 JP 2006-107914 A JP 2006-79904 A

  However, in the prior art, the durability of the solid polymer electrolyte membrane is not sufficient, and further improvement has been demanded. In addition, when metal oxide fine particles such as cerium oxide particles are simply added, the dispersibility of the metal oxide particles is inferior, so that there is a problem that the effect of improving durability is not sufficient.

  Under such circumstances, the present inventors have intensively studied to solve the above problems, and as a result, under the condition that a polymer having a pyrrolidone group is coexisted in a non-aqueous solvent together with a polymer having a sulfonic acid group. It was found that the durability of the solid polymer electrolyte membrane can be improved by including metal oxide particles obtained by oxidizing a metal compound with the present invention, and the present invention has been completed.

The configuration of the present invention is as follows.
[1] A polymer having a sulfonic acid group and a metal oxide particle having a number average primary particle diameter of 1 nm to 20 nm and a number average secondary particle diameter of 30 nm to 200 nm. Molecular electrolyte membrane.
[2] including a polymer having a sulfonic acid group, metal oxide particles,
A solid polymer electrolyte membrane, wherein the metal oxide particles are obtained by oxidizing a metal compound in the presence of a nonionic surfactant and an anionic surfactant.
[3] The solid polymer electrolyte membrane according to [1] or [2], containing the metal oxide particles in an amount of 0.01 to 30% by weight based on the total amount of the polymer and the metal oxide particles.
[4] The solid polymer electrolyte membrane according to [1] to [3], wherein the metal oxide particles are at least one selected from oxides of aluminum, titanium, zirconium, manganese, nickel, cobalt, or cerium.

[5] A polymer having a sulfonic acid group, metal oxide particles having a number average primary particle diameter of 1 nm to 20 nm and a number average secondary particle diameter of 30 nm to 200 nm, and a solvent. Liquid composition.
[6] including a polymer having a sulfonic acid group, metal oxide particles, and a solvent,
A liquid composition, wherein the metal oxide particles are obtained by oxidizing a metal compound in the presence of at least one selected from a nonionic surfactant and an anionic surfactant.
[7] The liquid composition according to [5] or [6], comprising 0.01 to 30% by weight of the metal oxide particles with respect to the polymer and the metal oxide particles.
[8] A method for producing a liquid composition according to the above [5] to [7],
A method for producing a liquid composition, which is obtained by mixing a polymer having a sulfonic acid group and a metal oxide in a solvent.
[9] A method for producing a solid polymer electrolyte membrane, comprising casting the liquid composition of [5] to [7] above.
[10] A membrane-electrode assembly comprising the solid polymer electrolyte membrane of [1] to [4], and a catalyst layer and a gas diffusion layer in contact with both sides of the solid polymer electrolyte membrane .
[11] A polymer electrolyte fuel cell having the membrane-electrode assembly according to [10].

  Since the solid polymer electrolyte membrane of the present invention contains specific metal oxide particles, it is excellent in durability. Therefore, the polymer electrolyte fuel cell provided with the membrane electrode assembly having the proton conducting membrane of the present invention is excellent in durability and can stably generate power over a long period of time.

[Solid polymer electrolyte membrane]
The solid polymer electrolyte membrane of the present invention comprises specific metal oxide particles and a polymer having a sulfonic acid group.

(i) Metal oxide particles The metal oxide particles used in the present invention have a number average primary particle diameter of 1 nm to 20 nm and a number average secondary particle diameter of 30 nm to 200 nm.

  The metal oxide particles used in the present invention are obtained by oxidizing a metal compound in the presence of at least one selected from a nonionic surfactant and an anionic surfactant.

  Specifically, it is not clear how nonionic surfactants and anionic surfactants are present in the particles, but some of them are taken in and adsorbed on the surface of the metal oxide particles during particle preparation. Or presumed to be supported.

  The metal oxide particles used in the present invention are obtained by oxidizing a metal compound in the presence of a nonionic surfactant and an anionic surfactant, and have a number average primary particle size and a secondary particle size. Particles having a particle size in the above range are preferred. Since such particles have a narrow and stable particle size distribution, the metal oxide particles have excellent dispersibility in the solid polymer electrolyte membrane, and the metal oxide particles are eluted when containing water. Or desorption is difficult to occur.

  When particles are prepared without the presence of a nonionic surfactant and an anionic surfactant, the resulting particles may not have a uniform particle size, and may form aggregates or electrolyte membranes. Dispersibility in the inside may be insufficient.

  Nonionic surfactants include polymers having a pyrrolidone group such as polyvinylpyrrolidone, N-vinylpyrrolidone / styrene copolymer, N-vinylpyrrolidone / vinyl acetate copolymer; polyvinylimidazole, N-vinylimidazole / styrene copolymer Polymers, polymers having an imidazole group such as N-vinylimidazole / vinyl acetate copolymer; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; polyalkylene glycol alkyl ethers such as polyethylene glycol monomethyl ether and polypropylene glycol dimethyl ether; polyethylene glycol mono Polyalkylene glycol phenyl ether agents such as phenyl ether and polypropylene glycol diphenyl Polyalkylene glycol fatty acid esters such as polyethylene glycol alkyl ester, polyethylene glycol stearic acid ester, polyethylene glycol lauric acid ester, polyethylene glycol sorbitan acid ester, polypropylene glycol sorbitan acid ester; polyvinyl caprolactam, polyvinyl alcohol, alkyl polyglucoside, chitosan series Examples thereof include polymer surfactants.

  Examples of the anionic surfactant include alkyl sulfate ester salt, polyoxyethylene alkyl ether sulfate ester salt, alkylbenzene sulfonate, aliphatic monocarboxylate, polyoxyethylene alkyl ether carboxylate, N-acyl. Sarcosinate, N-acyl glutamate, dialkyl sulfosuccinate, alkane sulfonate, alphoolefin sulfonate, naphthalene sulfonate-formamide condensate, alkyl naphthalene sulfonate, N-methyl-N-acyl taurine, Examples thereof include fat and oil sulfate esters, alkyl phosphates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl phenyl ether phosphates, and the like.

  The number average molecular weight in terms of polystyrene of the nonionic surfactant and the anionic surfactant is not particularly limited, but is preferably 200 to 300,000 in view of solubility in a solvent and ease of handling, and 5,000 to 200,000 is more preferred. Moreover, it is preferable to make nonionic surfactant or anionic surfactant exist about 10-1,000g with respect to 1 mol of raw material metal compounds, and it is more preferable to make 20-500g exist.

  Among the above surfactants, nonionic surfactants are preferable, and polymers having a pyrrolidone group are more preferable. The polymer having a pyrrolidone group is a polymer compound containing a pyrrolidone group in all or part of the side chain, and may be a copolymer with another compound. Preferably, it is one or more polymers selected from the group of polyvinyl pyrrolidone, N-vinyl pyrrolidone / styrene copolymer, N-vinyl pyrrolidone / vinyl acetate copolymer, and the like.

  The metal oxide particle is not particularly limited as long as it is a metal compound containing oxygen, but specifically, for example, aluminum, silicon, titanium, zirconium, zinc, tin, iron, bismuth, magnesium, yttrium, lead And oxides of metals such as manganese, germanium, copper, indium, beryllium, neodymium, lanthanum, niobium, tantalum, nickel, cobalt, gallium, cerium, molybdenum, tungsten, and composite oxides thereof.

Further, for example, tin-containing indium oxide (ITO), yttrium-containing zirconium oxide (YZrO _2), yttrium-containing aluminum oxide (YAl ₂ O _3), lanthanum-containing aluminum oxide (LaAl ₂ O _3), neodymium-containing aluminum oxide (NdAl ₂ Metal oxides containing other metals such as O ₃ ) may also be used.

Among these metal oxides, oxides such as aluminum, titanium, zirconium, manganese, nickel, cobalt, and cerium are particularly preferably used.
The number average primary particle diameter of the metal oxide particles is 1 nm to 20 nm, preferably 1 to 10 nm, and more preferably 2 to 5 nm. The number average primary particle size is determined by observation with an electron microscope.

  Further, the obtained particles have a uniform property with little aggregation and a narrow particle size distribution. Specifically, the number average secondary particle diameter is 30 nm to 200 nm, preferably 50 to 150 nm. It also has excellent long-term stability when stored as a dispersion. The dispersity (= primary particle diameter / secondary particle diameter) is preferably 0.005 to 0.8, and more preferably 0.01 to 0.5.

  The number average primary particle size and the number average secondary particle size can be adjusted by the amount of nonionic surfactant or anionic surfactant and the amount of raw material metal compound. Nonionic surfactant or anionic surfactant If the amount of the agent is increased or the amount of the starting metal compound is decreased, the average particle size can be reduced.

The solvent used in the production of the metal oxide particles is preferably a relatively polar solvent, specifically, for example, water, acetone, acetonitrile, benzonitrile, dimethylformamide, dimethyl sulfoxide, chloroform. , Methanol, ethanol, terpionol, dioxane, tetrahydrofuran, methyl ethyl ketone, ethylene glycol, diethylene glycol, polyethylene glycol, glycerin, or a mixed solvent containing these. The amount of the solvent is such that the concentration of the starting metal compound is 10 ⁻¹⁰ mol / l to 5 mol / l, preferably 10 ⁻⁴ mol / l to 10 ⁻¹ mol / l, more preferably 10 ⁻³ mol / l to 10 ⁻² mol / l. The amount is about l.

  The metal oxide particles can be obtained, for example, by oxidizing a raw material metal compound, which is a precursor of the metal oxide, in the presence of a nonionic surfactant and an anionic surfactant in a solvent. . In this case, a basic compound and water can be added as necessary. Examples of the basic compound include basic inorganic compounds such as sodium hydroxide, magnesium hydroxide and calcium hydroxide, and amine compounds such as ammonia and hydrazine. Moreover, you may heat or recirculate | reflux as needed. Although it does not specifically limit as reaction temperature, Usually, it is 0-200 degreeC, Preferably it is room temperature-the boiling point of a solvent. The reaction time is not particularly limited, but is usually 1 minute to 100 hours, preferably 10 minutes to 10 hours.

  The raw material metal compound referred to in the present invention is a metal compound that is soluble in the solvent to be used. For example, organic acid salts such as metal acetate constituting the metal oxide, metal nitrates, perchlorates, Alkoxides, acetylacetonates, halides and the like are used. Preferably, metal halides, metal nitrates, metal perchloric acids, and metal acetates are used. These may contain crystal water.

  Oxygen for oxidizing these raw metal compounds may be basically supplied to the reaction system as oxygen or air, but since the required amount is small, dissolved oxygen in water is sufficient, Furthermore, oxygen generated by a reaction from a base or a hydroxyl group in water may be used. In addition, the base used as necessary promotes the reaction from the metal compound to the metal oxide, and is preferably a strong base. For example, sodium hydroxide and potassium hydroxide are preferable. Used.

  When the solvent is removed from the stabilized metal oxide particle dispersion obtained in this way by decompression, air drying, heat evaporation, etc., the metal stabilized by the nonionic surfactant or the anionic surfactant An ultrafine oxide powder is obtained.

  If necessary, the obtained particles may be washed with water or alcohol to remove unreacted substances and excess nonionic surfactant or anionic surfactant. Furthermore, if necessary, it may be baked at a high temperature of 500 ° C. or higher to remove water of crystallization or enhance crystallinity.

  In the production of the metal oxide particles, a polymer having a sulfonic acid group, which will be described later, may coexist in advance. In this case, a coating liquid for forming an electrolyte membrane may be prepared without performing an operation such as drying. it can.

  The nonionic surfactant or anionic surfactant is preferably 1 to 50% by mass, more preferably 3 to 25% by mass, and further preferably 5 to 20% by mass with respect to the metal oxide particles finally obtained. It is desirable to be included in the amount of.

  When such metal oxide particles are included, oxygen, hydrogen peroxide, or peroxide radicals are inhibited, and deterioration of the solid polymer electrolyte membrane can be suppressed. Further, in the present invention, particles having a uniform particle diameter and little aggregation are used, so that the effect of suppressing deterioration of the solid polymer electrolyte membrane is particularly excellent.

(ii) Polymer having sulfonic acid group The polymer having a sulfonic acid group is not particularly limited as long as it is a polymer having a sulfonic acid group, which has been conventionally used in a solid polymer electrolyte membrane.

  For example, sulfonic acid is added to aliphatic hydrocarbon polymers such as polyacetal, polyethylene, polypropylene, acrylic resin, polystyrene, polystyrene-graft-ethylenetetrafluoroethylene copolymer, polystyrene-graft-polytetrafluoroethylene, and aliphatic polycarbonate. Group-introduced polymer (aliphatic hydrocarbon polymer having sulfonic acid group), polyester, polysulfone, polyphenylene ether, polyetherimide, aromatic polycarbonate, polyetheretherketone, polyetherketone, polyetherketoneketone , Polyetherethersulfone, polyethersulfone, polycarbonate, polyphenylene sulfide, aromatic polyamide, aromatic polyamideimide, aromatic polyimide, polybenzo Polymers in which sulfonic acid groups are introduced into aromatic hydrocarbon polymers having an aromatic ring in the main chain such as xazole, polybenzothiazole, polybenzimidazole (aromatic hydrocarbon polymers having sulfonic acid groups) are also available It is possible to use.

Further, a perfluorinated carbon-based polymer having a sulfonic acid group (which may contain an etheric oxygen atom) can also be used. No particular limitation is imposed on the total fluorocarbon _{polymer, CF 2 = CF- (OCF 2} CFX) m -O p - (CF 2) a perfluorovinyl compound represented by _n -SO ₃ H (m is 0 And n represents an integer of 1 to 12, p represents 0 or 1, and X represents a fluorine atom or a trifluoromethyl group.) And a polymerization based on tetrafluoroethylene A copolymer containing units.

In the case of using a total fluorocarbon polymer having a sulfonic acid group, a polymer in which the polymer terminal is fluorinated by fluorination after polymerization may be used.
Examples of the total fluorocarbon-based polymer having a sulfonic acid group include Nafion (registered trademark, manufactured by DuPont), Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.), Aciplex (manufactured by Asahi Kasei Kogyo Co., Ltd.) Is commercially available.

  In addition, a perfluoroalkyl sulfonic acid polymer complexed with polytetrafluoroethylene or a partially fluorinated sulfonated polymer such as polytetrafluoroethylene graft sulfonated polystyrene can also be used. For example, GORE-SELECT (manufactured by Japan Gore-Tex) in which a stretched porous polytetrafluoroethylene is impregnated with a polymer having a sulfonic acid group can also be used.

Among these, in the present invention, it is preferable to use an aromatic hydrocarbon polymer having a sulfonic acid group.
Examples of such aromatic hydrocarbon polymers having a sulfonic acid group include those described in Japanese Patent Application Laid-Open No. 2008-247857, Japanese Patent Application Laid-Open No. 2007-210919, Japanese Patent Application Laid-Open No. 2007-91788, and the like by the present applicant. Are illustrated.

Configuration of Solid Polymer Electrolyte Membrane The solid polymer electrolyte membrane according to the present invention includes (i) the metal oxide particles and (ii) the polymer having a sulfonic acid group.

  The metal oxide particles are desirably in the range of 0.01 to 30% by weight, preferably 0.1 to 20% by weight, more preferably 0.5 to 15% by weight, based on the total amount of the polymer and the metal oxide particles.

When the metal oxide particles are contained in such a range, the solid polymer electrolyte membrane exhibits good durability and proton conductivity.
Moreover, the solid polymer electrolyte membrane concerning this invention can also contain another metal compound or metal ion besides the said metal oxide particle. Other metal compounds or metal ions include aluminum (Al), titanium (Ti), zirconium (Zr), vanadium (V), tin (Sn), manganese (Mn), niobium (Nb), tantalum (Ta), Chromium (Cr), molybdenum (Mo), tungsten (W), iron (Fe), ruthenium (Ru), nickel (Ni), palladium (Pd), platinum (Pt), silver (Ag), cerium (Ce), Metal compounds such as neodymium (Nd), praseodymium (Pr), samarium (Sm), cobalt (Co), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), and erbium (Er) Or these metal ions are mentioned.

  The solid polymer electrolyte membrane according to the present invention can be produced using a liquid composition containing the metal oxide particles and a polymer having a sulfonic acid group, and a polymer solution having a sulfonic acid group. The film can be cast on a substrate to form a film, and then immersed in a solution containing the metal oxide particles.

Liquid composition The liquid composition according to the present invention comprises (i) metal oxide particles and (ii) a polymer having a sulfonic acid group. The amount of the metal oxide particles relative to the number of sulfonic acid groups contained in the metal oxide particles and the polymer, and the amount of the metal oxide particles relative to the whole of the polymer and the metal oxide particles are as described above. is there.

The liquid composition usually contains a solvent in addition to the metal oxide particles, the polymer having a pyrrolidone group, and the polymer having a sulfonic acid group.
The solvent may be any solvent that dissolves or swells the polymer having a sulfonic acid group. For example, N-methyl-2-pyrrolidone, N, N-dimethylformamide, γ-butyrolactone, N, N— Aprotic polar solvents such as dimethylacetamide, dimethylsulfoxide, dimethylurea, dimethylimidazolidinone, acetonitrile, chlorinated solvents such as dichloromethane, chloroform, 1,2-dichloroethane, chlorobenzene, dichlorobenzene, methanol, ethanol, propanol, Alcohols such as iso-propyl alcohol, sec-butyl alcohol, tert-butyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl ether, etc. Alkylene glycol monoalkyl ethers, acetone, methyl ethyl ketone, ketones such as cyclohexanone, tetrahydrofuran, solvents such as ethers 1,3-dioxane and the like. These solvents can be used alone or in combination of two or more. In particular, N-methyl-2-pyrrolidone (hereinafter also referred to as “NMP”) is preferable in terms of solubility and solution viscosity.

  When a mixture of an aprotic polar solvent and another solvent is used as the solvent, the composition of the mixture is such that the aprotic polar solvent is 95 to 25% by mass, preferably 90 to 25% by mass, A solvent is 5-75 mass%, Preferably it is 10-75 mass% (however, total is 100 mass%). When the amount of the other solvent is within the above range, the effect of lowering the solution viscosity is excellent. As a combination of the aprotic polar solvent and the other solvent in this case, N-methyl-2-pyrrolidone is preferred as the aprotic polar solvent, and methanol having an effect of lowering the solution viscosity in a wide composition range is preferred as the other solvent. .

  The concentration of the polymer having a sulfonic acid group in the liquid composition is usually 5 to 40% by mass, preferably 7 to 25% by mass, although it depends on the molecular weight. If it is less than 5% by mass, it is difficult to form a thick film, and pinholes are easily generated. On the other hand, if it exceeds 40% by mass, the solution viscosity is too high to form a film, and surface smoothness may be lacking.

  The metal oxide particle concentration may be such that the ratio to the polymer is in the above range, and is generally in the range of 0.05 to 12% by mass, preferably 0.7 to 5% by mass. It is preferable.

The solution viscosity is usually 2,000 to 100,000 mPa · s, preferably 3,000 to 50, although it depends on the molecular weight of the polymer having the sulfonic acid group, the polymer concentration, and the concentration of the additive. 1,000 mPa · s. If the viscosity is low, the solution stays poor during film formation and may flow from the substrate. On the other hand, if the viscosity is too high, film formation by the casting method may be difficult.

The liquid composition according to the present invention can be prepared by mixing a polymer having a sulfonic acid group and metal oxide particles in the solvent. Specifically, after the polymer having a sulfonic acid group is dissolved or dispersed in the solvent, the metal oxide particles are mixed with the polymer, or the metal oxide particles are mixed with the solvent. Examples of the method include dissolving or dispersing a polymer having a sulfonic acid group after being dissolved or dispersed therein.

  Furthermore, the liquid composition according to the present invention comprises a polymer having a sulfonic acid group and a nonionic surfactant or an anionic surfactant coexisting in a non-aqueous solvent in the solvent, and adding a metal compound. It can also be prepared by oxidizing a metal compound into metal oxide particles.

  In addition to the polymer having the sulfonic acid group and the metal oxide particles, the liquid composition includes inorganic acids such as sulfuric acid and phosphoric acid, phosphate glass, tungstic acid, phosphate hydrate, and β-alumina proton substitution. Bodies, inorganic proton conductor particles such as proton-introduced oxides, organic acids including carboxylic acids, organic acids including sulfonic acids, organic acids including phosphonic acids, and appropriate amounts of water may be used in combination.

Production Method of Solid Polymer Electrolyte Membrane The solid polymer electrolyte membrane according to the present invention can be produced , for example, by a casting method in which the liquid composition is cast on a substrate and formed into a film shape. The substrate is not particularly limited as long as it is a substrate used in a normal solution casting method. For example, a substrate made of plastic or metal is used, and preferably made of a thermoplastic resin such as a polyethylene terephthalate (PET) film. A substrate is used.

  After film formation as described above, when the obtained undried film is immersed in water, the organic solvent in the undried film can be replaced with water, and the amount of residual solvent in the obtained solid polymer electrolyte membrane Can be reduced.

  In addition, after film formation, before immersing an undried film in water, you may predry an undried film. The preliminary drying is performed by holding the undried film at a temperature of usually 50 to 150 ° C. for 0.1 to 10 hours.

  After film formation, a solution containing a polymer having a sulfonic acid group may be further applied to form a solid polymer electrolyte membrane in a multilayer structure. When a multilayer structure is used, the metal oxide particles can be unevenly distributed. In this case, from the viewpoint of durability and proton conductivity of the solid polymer electrolyte membrane, when the membrane-electrode assembly is produced, the metal oxide particles are contained only in the cathode side layer, and the other layers are made of metal. A structure that does not include oxide particles may also be used.

  When the undried film is immersed in water and dried as described above, a film with a reduced amount of residual solvent is obtained. The amount of residual solvent in the film thus obtained is usually 5% by mass or less. Further, depending on the immersion conditions, the amount of residual solvent in the obtained film can be set to 1% by mass or less. As such conditions, for example, the amount of water used is 50 parts by mass or more with respect to 1 part by mass of the undried film, the temperature of the water during immersion is 10 to 60 ° C., and the immersion time is 10 minutes to 10 hours. is there.

  After immersing the undried film in water as described above, the film is dried at 30-100 ° C, preferably 50-80 ° C, for 10-180 minutes, preferably 15-60 minutes, and then at 50-150 ° C. The film can be obtained by vacuum drying under reduced pressure of 500 mmHg to 0.1 mmHg for 0.5 to 24 hours.

The solid polymer electrolyte membrane obtained by the method of the present invention has a dry film thickness of usually 10 to 100 μm, preferably 20 to 80 μm.
A reinforced solid polymer electrolyte membrane can also be produced by using a porous substrate or a sheet-like fibrous material.

  As a method of producing a reinforced solid polymer electrolyte membrane, for example, a liquid composition is impregnated into a porous substrate or a sheet-like fibrous substance, and a polymer having a sulfonic acid group is formed into a porous substrate or A method of filling the pores inside the sheet-like fibrous substance, the liquid composition is applied to a porous substrate or a sheet-like fibrous substance, and a polymer having a sulfonic acid group is added to the porous substrate or A method of filling the pores inside the sheet-like fibrous substance, and after forming a film from the liquid composition, the film is laminated on a porous substrate or a sheet-like fibrous substance and hot pressed, Examples thereof include a method of filling a polymer having a sulfonic acid group into pores of a porous substrate or a sheet-like fibrous substance.

  Further, when forming a solid polymer electrolyte membrane having a multilayer structure, a die coat, spray coat, knife coat, roll coat, spin coat, gravure is further applied to the surface of the solid polymer electrolyte membrane obtained by the above-described methods. A film containing a polymer having a sulfonic acid group is applied by a known method such as coating, and dried as necessary, or a film formed from a composition containing a polymer having a sulfonic acid group is described above. For example, the film obtained by the above method may be hot-pressed on the film. The thickness of the polymer layer may be adjusted by adjusting the coating amount. For example, one polymer layer may be thick and the other thin. When forming a solid polymer electrolyte membrane having a multilayer structure, the above liquid composition containing metal oxide particles may be used when forming at least one layer. For this reason, when the already formed solid polymer electrolyte membrane contains metal oxide particles, the composition containing a polymer having a sulfonic acid group that is subjected to coating or hot pressing for stacking includes: Metal oxide particles may not be included. In addition, when the formed solid polymer electrolyte membrane does not contain metal oxide particles, a liquid composition containing the metal oxide particles according to the present invention is used as a composition for coating or hot pressing for lamination. You may use things. Further, a composition containing a polymer having a sulfonic acid group, which does not contain metal oxide particles, is applied to form a multilayer structure, or before or after hot pressing formed into a film made of the composition, You may immerse in the solution containing the said metal oxide particle.

  The porous substrate is not particularly limited as long as it has a large number of pores or voids penetrating in the thickness direction. For example, organic porous substrates made of various resins, glass, alumina Inorganic porous base materials composed of metal oxides and metals themselves.

The porous substrate may have a large number of through holes penetrating in a direction substantially parallel to the thickness direction.
As such a porous substrate, JP 2008-119662 A, JP 2007-154153 A, JP 8-20660 A, JP 8-20660 A, JP 2006-120368 A, What was disclosed by Unexamined-Japanese-Patent No. 2004-171994 and 2009-64777 can be used.

  As the porous substrate used in the present invention, an organic porous substrate is preferable, and specifically, polyolefins such as polytetrafluoroethylene, high molecular weight polyethylene, cross-linked polyethylene, polyethylene and polypropylene, polyimide, polyacrylo What consists of 1 or more types chosen from the group which consists of tolyl, polyamideimide, polyetherimide, polyethersulfone, and glass is preferable. The polyolefin is preferably high molecular weight polyethylene, cross-linked polyethylene, polyethylene or the like.

  In the present invention, among these, in view of combining with the polymer having a sulfonic acid group, the porous substrate is composed of polyolefin such as polytetrafluoroethylene, high molecular weight polyethylene, cross-linked polyethylene, polyethylene, etc. preferable. If necessary, the polyolefin may be hydrophilized. The hydrophilization treatment is a treatment that modifies the polyolefin constituting the porous using an alkali metal solution, and this treatment modifies the porous membrane surface and imparts hydrophilicity. Since the modified portion may be browned, the brown layer may be removed by oxidative decomposition with hydrogen peroxide, sodium hypochlorite, ozone, or the like. Such hydrophilic treatment is sometimes referred to as chemical etching. Examples of the alkali metal solution include an organic solvent solution such as tetrahydrofuran, such as methyl lithium, a metal sodium-naphthalene complex, and a metal sodium-anthracene complex, and a solution of metal sodium-liquid ammonia.

  Moreover, as a sheet-like fibrous substance, a nonwoven fabric, a woven fabric, a knitted fabric, etc. are mentioned. Examples of the fibers constituting the woven fabric include, but are not limited to, polyethylene fibers, fluoropolymer reinforced fibers, polyimide fibers, polyphenylene sulfide sulfone fibers, polysulfone fibers, and glass fibers.

  Examples of the fibers constituting the nonwoven fabric include polyamide resins, polyvinyl alcohol resins, polyvinylidene chloride resins, polyvinyl chloride resins, polyester resins, polyacrylonitrile resins, polyolefin resins (for example, polyethylene resins, Polypropylene resin, etc.), polystyrene resin (eg, crystalline polystyrene, amorphous polystyrene, etc.), aromatic polyamide resin, organic resin such as polyurethane resin, or glass, carbon, potassium titanate, silicon carbide Those composed of inorganic components such as silicon nitride, zinc oxide, aluminum borate and wollastonite can be used.

  In addition, the solid polymer electrolyte membrane according to the present invention includes a composition containing the metal oxide particles after a polymer solution having a sulfonic acid group is cast on a substrate to form a film. It can also be produced by immersing in an object.

  As the dispersion medium or solvent for the metal oxide particles used in the composition containing the metal oxide particles, those in which the obtained solid polymer electrolyte membrane does not elute are preferably used, and specifically water is exemplified. .

[Membrane-electrode assembly]
The membrane-electrode assembly according to the present invention is a membrane-electrode assembly comprising the solid polymer electrolyte membrane, a catalyst layer, and a gas diffusion layer. Typically, a catalyst layer for the cathode electrode is provided on one side of the solid polymer electrolyte membrane, and a catalyst layer for the anode electrode is provided on the other side, and each of the catalyst layers on the cathode side and the anode side is further provided. Gas diffusion layers are provided on the cathode side and the anode side, respectively, in contact with the side opposite to the solid polymer electrolyte membrane.

Known gas diffusion layers and catalyst layers can be used without particular limitation.
Specifically, the gas diffusion layer is composed of a porous substrate or a laminated structure of a porous substrate and a microporous layer. When the gas diffusion layer is composed of a laminated structure of a porous substrate and a microporous layer, the microporous layer is provided in contact with the catalyst layer. The gas diffusion layers on the cathode side and the anode side preferably contain a fluoropolymer in order to impart water repellency.

  The catalyst layer is composed of a catalyst and an ion exchange resin electrolyte. As the catalyst, a noble metal catalyst such as platinum, palladium, gold, ruthenium or iridium is preferably used. The noble metal catalyst may contain two or more elements such as an alloy or a mixture. As such noble metal catalyst, one supported on high specific surface area carbon fine particles can be used.

  The ion exchange resin electrolyte functions as a binder component for binding the carbon carrying the catalyst, and at the anode electrode, efficiently supplies ions generated by the reaction on the catalyst to the solid polymer electrolyte membrane. Then, ions supplied from the solid polymer electrolyte membrane are efficiently supplied to the catalyst.

  The ion exchange resin for the catalyst layer used in the present invention is preferably a polymer having a proton exchange group in order to improve proton conductivity in the catalyst layer. Proton exchange groups contained in such polymers include sulfonic acid groups, carboxylic acid groups, and phosphoric acid groups, but are not particularly limited. Further, such a polymer having a proton exchange group is also selected without any particular limitation, but a polymer having a proton exchange group composed of a fluoroalkyl ether side chain and a fluoroalkyl main chain, a sulfonic acid group An aromatic hydrocarbon polymer having the same is preferably used. In addition, an aromatic hydrocarbon polymer having a sulfonic acid group constituting the solid polymer electrolyte membrane may be used as an ion-exchange resin, and a polymer containing a fluorine atom having a proton exchange group or ethylene Or other polymers obtained from styrene or the like, copolymers or blends thereof. As such an ion exchange resin electrolyte, a known one can be used without any particular limitation, and for example, Nafion (DuPont, registered trademark), an aromatic hydrocarbon polymer having a sulfonic acid group, or the like can be used without any particular limitation. .

  If necessary, a resin having no carbon fiber or ion exchange group may be used for the catalyst layer used in the present invention. These resins are preferably resins with high water repellency. For example, fluorine-containing copolymers, silane coupling agents, silicone resins, waxes, polyphosphazenes and the like can be mentioned, and fluorine-containing copolymers are preferred.

[Fuel cell]
The polymer electrolyte fuel cell according to the present invention includes the membrane-electrode assembly. Specifically, at least one electricity generation unit including at least one membrane-electrode assembly and separators located on both sides thereof; a fuel supply unit that supplies fuel to the electricity generation unit; and an oxidant as the electricity A fuel cell including an oxidant supply unit for supplying to a generation unit, wherein the membrane-electrode assembly is as described above.

  As the separator used in the battery of the present invention, those used in ordinary fuel cells can be used. Specifically, carbon type or metal type can be used.

  Moreover, as a member which comprises a fuel cell, it is possible to use a well-known thing without a restriction | limiting in particular. The battery of the present invention can be used as a single cell or as a stack in which a plurality of single cells are connected in series. As a stacking method, a known method can be used. Specifically, planar stacking in which single cells are arranged in a plane and bipolar stacking in which single cells are stacked via separators each having a fuel or oxidant flow path formed on the back surface of the separator can be used. .

[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.
Evaluation in this example was performed as follows.

[Sulfonic acid equivalent]
After washing the sulfonated polymer with 1N aqueous hydrochloric acid, it is thoroughly washed with ion-exchanged water until the washing water becomes neutral in order to remove free remaining acid, and after drying, a predetermined amount is weighed. Titration was performed using a standard solution of NaOH using phenolphthalein dissolved in a THF / water mixed solvent as an indicator, and the sulfonic acid equivalent was determined from the neutralization point.

(Measurement of molecular weight)
The molecular weight of the sulfonated polymer, or the molecular weight of the sulfonated polymer after the heat test, was converted into polystyrene using GPC using a mixed solution of 7.83 g of lithium bromide, 3.3 ml of phosphoric acid and a solvent as the eluent. The molecular weight of was determined.

[Particle size]
The number average primary particle size of the particles was measured by a transmission electron microscope (TEM), and the number average secondary particle size of the particles was measured by a dynamic light scattering (DLS) method (measuring device: manufactured by Horiba, Ltd., dynamic light). Scattering type particle size distribution measuring device, product number “HORIBA LB550”)

[Quantification of surface-active agent adhesion]
The amount of attached surfactant was calculated from the weight loss when heated to 900 ° C. using thermogravimetric analysis (TG).

[Synthesis Example 1]
30 cm ³ of ethylene glycol (EG) (manufactured by Wako Pure Chemical Industries), 7.8 g of Ce (NO ₃ ) ₃ .6H ₂ O (manufactured by high purity chemical), and polyvinylpyrrolidone K-30 (PVP) (manufactured by Sigma Aldrich; 2.4 g of polystyrene-equivalent number average molecular weight 3 × 10 ⁴ ) was added, and the mixture was heated to reflux at 190 ° C. for 60 minutes to obtain a cloudy mixed solution.

  Next, in order to remove unreacted substances and excess PVP, a part of the cloudy solution was centrifuged at 10,000 rpm and washed with water and ethanol. After washing, it was dried at 80 ° C. to obtain a powder.

  As a result of analyzing the obtained powder by X-ray diffraction (XRD), it was confirmed that cerium oxide was produced. As a result of analysis by FTIR, a peak due to PVP was observed, and it was confirmed that the obtained powder was cerium oxide stabilized with PVP. Furthermore, in thermogravimetric analysis (TG), heating to 900 ° C. resulted in a weight loss of 20 wt%, so it was confirmed that approximately 20 wt% PVP was attached to cerium oxide.

  When this cerium oxide stabilized with PVP was observed with a transmission electron microscope (TEM), it was found that the average size of the primary particles was 3 nm. Further, as a result of analysis by a dynamic light scattering (DLS) method, it was found that the secondary particle size was 100 nm on average and the standard deviation of the particle size distribution was 30 nm.

[Synthesis Example 2-1]
(1) Synthesis of hydrophobic unit 49.4 g of 2,6-dichlorobenzonitrile was added to a 1 L three-necked flask equipped with a stirrer, thermometer, cooling tube, Dean-Stark tube and nitrogen-introduced three-way cock. 0.29 mol), 2,2-bis (4-hydroxyphenyl) -1,1,1,3,3,3-hexafluoropropane 88.4 g (0.26 mol), potassium carbonate 47.3 g (0 .34 mol) was weighed. After substitution with nitrogen, 346 ml of sulfolane and 173 ml of toluene were added and stirred. The flask was placed in an oil bath and heated to reflux at 150 ° C. When water produced by the reaction was azeotroped with toluene and reacted while being removed from the system with a Dean-Stark tube, almost no water was observed in about 3 hours. After removing most of the toluene while gradually raising the reaction temperature, the reaction was continued at 200 ° C. for 3 hours. Next, 12.3 g (0.072 mol) of 2,6-dichlorobenzonitrile was added and reacted for another 5 hours.

  The resulting reaction solution was allowed to cool and then diluted by adding 100 ml of toluene. The precipitate of the inorganic compound produced as a by-product was removed by filtration, and the filtrate was put into 2 L of methanol. The precipitated product was separated by filtration, collected, dried, and dissolved in 250 ml of tetrahydrofuran. This was reprecipitated in 2 L of methanol to obtain 107 g of the objective compound.

  The number average molecular weight in terms of polystyrene determined by GPC (solvent: tetrahydrofuran) of the obtained target compound was 7,300. The obtained compound was an oligomer represented by the following structural formula.

（２）親水性ユニットの合成
攪拌機、冷却管を備えた３Ｌの三口フラスコに、クロロスルホン酸２３３．０ｇ（２モル）を加え、続いて２,５−ジクロロベンゾフェノン１００．４ｇ（４００ミリモル）を加え、１００℃のオイルバスで８時間反応させた。所定時間後、反応液を砕氷１０００ｇにゆっくりと注ぎ、酢酸エチルで抽出した。有機層を食塩水で洗浄、硫酸マグネシウムで乾燥後、酢酸エチルを留去し、淡黄色の粗結晶３−（２，５−ジクロロベンゾイル）ベンゼンスルホン酸クロリドを得た。粗結晶は精製せず、そのまま次工程に用いた。

(2) Synthesis of hydrophilic unit 233.0 g (2 mol) of chlorosulfonic acid was added to a 3 L three-necked flask equipped with a stirrer and a cooling tube, followed by 100.4 g (400 mmol) of 2,5-dichlorobenzophenone. In addition, the reaction was performed in an oil bath at 100 ° C. for 8 hours. After a predetermined time, the reaction solution was slowly poured onto 1000 g of crushed ice and extracted with ethyl acetate. The organic layer was washed with brine and dried over magnesium sulfate, and then ethyl acetate was distilled off to obtain pale yellow crude crystals of 3- (2,5-dichlorobenzoyl) benzenesulfonic acid chloride. The crude crystals were not purified and used as they were in the next step.

  3,8.8 g (440 mmol) of 2,2-dimethyl-1-propanol (neopentyl alcohol) was added to 300 mL of pyridine and cooled to about 10 ° C. The crude crystals obtained above were gradually added thereto over about 30 minutes. After the total amount was added, the reaction was further stirred for 30 minutes. After the reaction, the reaction solution was poured into 1000 ml of aqueous hydrochloric acid, and the precipitated solid was collected. The obtained solid was dissolved in ethyl acetate, washed with aqueous sodium hydrogen carbonate solution and brine, dried over magnesium sulfate, and then ethyl acetate was distilled off to obtain crude crystals. This was recrystallized with methanol to obtain white crystals of neopentyl 3- (2,5-dichlorobenzoyl) benzenesulfonate represented by the following structural formula.

（３）塩基性ユニットの合成
撹拌羽根、温度計、窒素導入管を取り付けた２Ｌの３口フラスコに、フルオロベンゼン２４０．２ｇ（２．５０モル）を取り、氷浴で１０℃まで冷却し、２，５−ジクロロ安息香酸クロライド１３４．６ｇ（０．５０モル）、塩化アルミニウム８６．７ｇ（０．６５モル）を反応温度が４０℃を超えないように徐々に添加した。添加後、４０℃で８時間撹拌した。薄層クロマトグラフィーにより原料の消失を確認した後、氷水に滴下し、酢酸エチルから抽出を行った。５％重曹水により中和した後、飽和食塩水で洗浄し、硫酸マグネシウムにより乾燥させた後、エバポレーターでにより溶媒を留去した。メタノールから再結晶を行うことにより、中間体の２,５−ジクロロ−４'−フルオロベンゾフェノンを１３０ｇ、収率９７％で得た。

(3) Synthesis of basic unit In a 2 L three-necked flask equipped with a stirring blade, a thermometer, and a nitrogen introduction tube, 240.2 g (2.50 mol) of fluorobenzene was taken, cooled to 10 ° C. in an ice bath, 2,4.6 g (0.50 mol) of 2,5-dichlorobenzoic acid chloride and 86.7 g (0.65 mol) of aluminum chloride were gradually added so that the reaction temperature did not exceed 40 ° C. After the addition, the mixture was stirred at 40 ° C. for 8 hours. After confirming the disappearance of the raw material by thin layer chromatography, it was added dropwise to ice water and extracted from ethyl acetate. The mixture was neutralized with 5% aqueous sodium bicarbonate, washed with saturated brine, dried over magnesium sulfate, and then the solvent was distilled off with an evaporator. By recrystallization from methanol, 130 g of intermediate 2,5-dichloro-4′-fluorobenzophenone was obtained in a yield of 97%.

  To a 2 L three-necked flask equipped with a stirrer, thermometer, condenser, Dean-Stark tube, and nitrogen-introduced three-way cock, 130.5 g (0.49 mol) of 2,5-dichloro-4′-fluorobenzophenone was added. 2-hydroxypyridine 46.1 g (0.49 mol), potassium carbonate 73.7 g (0.53 mol), N, N-dimethylacetamide (DMAc) 500 mL, toluene 100 mL was added, The reaction was performed at 130 ° C. with stirring and heating under a nitrogen atmosphere. When water produced by the reaction was azeotroped with toluene and reacted while being removed from the system with a Dean-Stark tube, almost no water was observed in about 3 hours. Thereafter, most of the toluene was removed, and the reaction was continued at 130 ° C. for 10 hours. The resulting reaction solution was allowed to cool, and then the filtrate was put into 2 L of water / methanol (9/1). The precipitated product was filtered off, collected and dried. Take the dried product in a 2 L three-necked flask equipped with a stirrer, thermometer, cooling tube, Dean-Stark tube and nitrogen-introduced three-way cock, stir at 100 ° C. in 1 L of toluene, and distill off the remaining water. Dissolved. After allowing to cool, the crystallized product was filtered to obtain 142 g of pale yellow 2,5-dichloro-4 ′-(pyridin-2-yl) benzophenone represented by the following structural formula in a yield of 83%.

（４）スルホン酸基を有する重合体の合成
撹拌機、温度計、窒素導入管を接続した１Ｌの３口フラスコに、乾燥したＮ,Ｎ−ジメチルアセトアミド（ＤＭＡｃ）１６６ｍＬを（１）で合成したオリゴマー１３．４ｇ（１．８ミリモル）、（２）で合成した３−(２,５−ジクロロベンゾイル)ベンゼンスルホン酸ネオペンチル ３７．６ｇ（９３．７ミリモル）、（３）で合成した２,５−ジクロロ−４'−(ピリジン−２−イル)ベンゾフェノン １．６１ｇ（４．７ミリモル）、ビス（トリフェニルホスフィン）ニッケルジクロリド２．６２ｇ（４．０ミリモル）、トリフェニルホスフィン１０．５ｇ（４０．１ミリモル）、ヨウ化ナトリウム０．４５ｇ（３．０ミリモル）、亜鉛１５．７ｇ（２４０．５ミリモル）の混合物中に窒素下で加えた。

(4) Synthesis of polymer having sulfonic acid group 166 mL of dried N, N-dimethylacetamide (DMAc) was synthesized in (1) in a 1 L three-necked flask connected with a stirrer, thermometer, and nitrogen introduction tube. 13.4 g (1.8 mmol) of the oligomer, 37.6 g (93.7 mmol) of neopentyl 3- (2,5-dichlorobenzoyl) benzenesulfonate synthesized in (2), and 2,5 synthesized in (3) -Dichloro-4 '-(pyridin-2-yl) benzophenone 1.61 g (4.7 mmol), bis (triphenylphosphine) nickel dichloride 2.62 g (4.0 mmol), triphenylphosphine 10.5 g (40 mmol) 0.1 mmol), 0.45 g (3.0 mmol) sodium iodide, and 15.7 g (240.5 mmol) zinc were added under nitrogen.

  The reaction system was heated with stirring (finally heated to 82 ° C.) and allowed to react for 3 hours. An increase in viscosity in the system was observed during the reaction. The polymerization reaction solution was diluted with 175 mL of DMAc, stirred for 30 minutes, and filtered using Celite as a filter aid. Lithium bromide (24.4 g, 281 mmol) was added to the filtrate in 1/3 portions at 1-hour intervals through a 1-L three-neck equipped with a stirrer, and the internal temperature was 120 ° C. for 5 hours. Reacted below. After the reaction, the mixture was cooled to room temperature, poured into 4 L of acetone and solidified. The coagulum was collected by filtration, air-dried, pulverized with a mixer, and washed with 1500 mL of 1N sulfuric acid while stirring. After filtration, the product is washed with ion-exchanged water until the pH of the washing solution becomes 5 or higher, and then dried at 80 ° C. overnight, and 38.0 g of a polymer having a sulfonic acid group into which a target basic unit has been introduced. Got. The molecular weight in terms of polystyrene measured by GPC (solvent: N-methyl-2-pyrrolidone) of the polymer having a sulfonic acid group after deprotection was Mn = 63000 and Mw = 194000. The ion exchange capacity of this polymer was 2.33 meq / g. The obtained polymer having a sulfonic acid group is a compound (polymer A) represented by the following structural formula.

〔合成例２-２〕
（１）親水性ユニットの合成
２,２−ジメチルプロパノール４４．９ｇ（５１０．２ミリモル）をピリジン１４７ｍｌに溶解させた。これに、０℃で、２，５−ジクロロベンゼンスルホン酸クロリド１００ｇ（４０５．６ミリモル）を加え、室温で、１時間攪拌、反応させた。反応混合物に、酢酸エチル７４０ｍＬ及び２ｍｏｌ％塩酸７４０ｍＬを加え、３０分間撹拌した後、静置し、有機層を分離した。分離した有機層を水７４０ｍＬ、１０質量％炭酸カリウム水溶液７４０ｍＬ、飽和食塩水７４０ｍＬで順次洗浄した後、減圧条件下で、溶媒を留去した。残渣をシリカゲルカラムクロマトグラフィ（クロロホルム溶媒）で精製した。得られた溶出液から溶媒を、減圧条件下で留去した。残渣を、６５℃でヘキサン９７０ｍＬに溶解させた後、室温まで冷却した。析出した固体を濾過により分離した。分離した固体を乾燥し、下記構造式で表される２，５−ジクロロベンゼンスルホン酸（２，２−ジメチルプロピル）の白色固体を９９．４ｇ、収率８２．１％で得た。

[Synthesis Example 2-2]
(1) Synthesis of hydrophilic unit 44.9 g (510.2 mmol) of 2,2-dimethylpropanol was dissolved in 147 ml of pyridine. To this, 100 g (405.6 mmol) of 2,5-dichlorobenzenesulfonic acid chloride was added at 0 ° C., and the mixture was stirred and reacted at room temperature for 1 hour. Ethyl acetate (740 mL) and 2 mol% hydrochloric acid (740 mL) were added to the reaction mixture, and the mixture was stirred for 30 minutes and then allowed to stand to separate the organic layer. The separated organic layer was washed successively with 740 mL of water, 740 mL of 10% by mass potassium carbonate aqueous solution and 740 mL of saturated brine, and then the solvent was distilled off under reduced pressure. The residue was purified by silica gel column chromatography (chloroform solvent). The solvent was distilled off from the resulting eluate under reduced pressure. The residue was dissolved in 970 mL of hexane at 65 ° C. and then cooled to room temperature. The precipitated solid was separated by filtration. The separated solid was dried to obtain 99.4 g of a white solid of 2,5-dichlorobenzenesulfonic acid (2,2-dimethylpropyl) represented by the following structural formula in a yield of 82.1%.

（２）スルホン酸基を有する重合体の合成
無水塩化ニッケル１．６２ｇ（１２．５ミリモル）とジメチルスルホキシド（ＤＭＳＯ）１５ｍＬとを混合し、内温７０℃ に調整した。これに、２，２’−ビピリジン２．１５ｇ（１３．８モル）を加え、同温度で１０分撹拌し、ニッケル含有溶液を調製した。（１）で合成した２，５−ジクロロベンゼンスルホン酸（２，２−ジメチルプロピル）１．４９ｇ（５．０ミリモル）と下記構造式

(2) Synthesis of polymer having sulfonic acid group 1.62 g (12.5 mmol) of anhydrous nickel chloride and 15 mL of dimethyl sulfoxide (DMSO) were mixed to adjust the internal temperature to 70 ° C. To this, 2.15 g (13.8 mol) of 2,2′-bipyridine was added and stirred at the same temperature for 10 minutes to prepare a nickel-containing solution. 1.49 g (5.0 mmol) of 2,5-dichlorobenzenesulfonic acid (2,2-dimethylpropyl) synthesized in (1) and the following structural formula

で示されるスミカエクセルＰＥＳ５２００Ｐ（住友化学社製、Ｍｎ＝４００００、Ｍｗ＝９４０００）０．５０ｇ(０．０１３ミリモル)とをジメチルスルホキシド（ＤＭＳＯ）５ｍＬに溶解させて得られた溶液に、亜鉛１．２３ｇ（１８．８ミリモル）を加え、７０℃に調整した。これに、前記ニッケル含有溶液を注ぎ込み、７０℃で４時間重合反応を行った。反応混合物をメタノール６０ｍＬ中に加え、次いで、６ｍｏｌ／Ｌ塩酸６０ｍＬを加え、１時間撹拌した。析出した固体を濾過により分離し、乾燥し、灰白色の重合中間体を１．６２ｇ得た。得られた重合中間体１．６２ｇを、臭化リチウム１．１３ｇ（１３．０ミリモル）とＮ−メチル−２−ピロリドン（ＮＭＰ）５６ｍＬとの混合溶液に加え、１２０℃で２４時間反応させた。反応混合物を、６ｍｏｌ／Ｌ塩酸５６０ｍＬ中に注ぎ込み、１時間撹拌した。析出した固体を濾過により分離した。分離した固体を乾燥し、灰白色の目的のスルホン酸基を有する重合体０．４２ｇを得た。この脱保護後のスルホン酸基を有する重合体のGPC（溶媒：Ｎ−メチル−２ピロリドン）で測定したポリスチレン換算の分子量は、Ｍ ｎ＝７５０００、Ｍｗ＝１７３０００であった。この重合体のイオン交換容量は１．９５ｍｅｑ／ｇであった。得られたスルホン酸基を有する重合体は、下記構造式で表される化合物（重合体Ｂ）である。

In a solution obtained by dissolving 0.50 g (0.013 mmol) of Sumika Excel PES5200P (manufactured by Sumitomo Chemical Co., Ltd., Mn = 40000, Mw = 94000) in 5 mL of dimethyl sulfoxide (DMSO). 23 g (18.8 mmol) was added and adjusted to 70 ° C. The nickel-containing solution was poured into this, and a polymerization reaction was performed at 70 ° C. for 4 hours. The reaction mixture was added to 60 mL of methanol, and then 60 mL of 6 mol / L hydrochloric acid was added and stirred for 1 hour. The precipitated solid was separated by filtration and dried to obtain 1.62 g of an off-white polymerization intermediate. 1.62 g of the obtained polymerization intermediate was added to a mixed solution of 1.13 g (13.0 mmol) of lithium bromide and 56 mL of N-methyl-2-pyrrolidone (NMP) and reacted at 120 ° C. for 24 hours. . The reaction mixture was poured into 560 mL of 6 mol / L hydrochloric acid and stirred for 1 hour. The precipitated solid was separated by filtration. The separated solid was dried to obtain 0.42 g of an off-white polymer having a target sulfonic acid group. The molecular weight in terms of polystyrene measured by GPC (solvent: N-methyl-2pyrrolidone) of the polymer having a sulfonic acid group after deprotection was Mn = 75000 and Mw = 173000. The ion exchange capacity of this polymer was 1.95 meq / g. The obtained polymer having a sulfonic acid group is a compound (polymer B) represented by the following structural formula.

〔実施例１〕
合成例１で得られた酸化セリウム微粒子０．８ｇをメタノール／Ｎ−メチル−２−ピロリドン（ＮＭＰ）＝４０／６０の混合溶媒８４ｍｌに添加し、超音波発生ホモジナイザーを使用して分散させた。次いで、この分散液に合成例２-１で得られた重合体Ａ１６ｇを添加し、溶解させた。この溶液をＰＥＴフィルムの上にダイコータにてキャスト塗工し、８０℃で４０分予備乾燥した後、１２０℃で４０分乾燥した。これを大量の蒸留水に一晩浸漬し、膜中の残存ＮＭＰを希釈により取り除いた後、風乾し、膜厚４０μｍの膜を得た。

[Example 1]
0.8 g of the cerium oxide fine particles obtained in Synthesis Example 1 was added to 84 ml of a mixed solvent of methanol / N-methyl-2-pyrrolidone (NMP) = 40/60, and dispersed using an ultrasonic generation homogenizer. Next, 16 g of the polymer A obtained in Synthesis Example 2-1 was added to this dispersion and dissolved. This solution was cast-coated on a PET film with a die coater, pre-dried at 80 ° C. for 40 minutes, and then dried at 120 ° C. for 40 minutes. This was immersed in a large amount of distilled water overnight, the remaining NMP in the film was removed by dilution, and then air-dried to obtain a film having a thickness of 40 μm.

  A size of 5 cm × 5 cm was cut out from this film, dried at 110 ° C. under reduced pressure for 2 hours, accurately weighed, and allowed to stand at 550 ° C. for 2 days. To obtain a liquid in which cerium was completely extracted. The amount of cerium oxide in the film was quantified by measuring this liquid by inductively coupled plasma (ICP) emission analysis, and it was found to be 37 mg with respect to 1 g of the film. In addition, when the film was immersed in hot water at 120 ° C. under pressure for 100 hours and ICP measurement was performed in the same manner as described above, there was no change in the amount of cerium before and after the hot water immersion, and the cerium oxide fine particles were added to the hot water. It was found that no elution occurred.

[Preparation of anode electrode paste]
Next, 80 g of a zirconia ball having a diameter of 5 mm (“YTZ ball” manufactured by Nikkato Corporation) is placed in a 200 ml plastic bottle, and platinum ruthenium-supported carbon particles (“TEC61E54” manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., Pt: 29.8 mass% supported, Ru : 23.2% by mass) 1.28 g, distilled water 3.60 g, n-propyl alcohol 12.02 g and Nafion ™ D2020 (manufactured by DuPont, polymer concentration 21% dispersion, ion exchange capacity 1.08 meq / g) Anode paste was obtained by adding 3.90 g and stirring with a paint shaker for 60 minutes.

[Preparation of cathode electrode paste]
Next, 80 g of zirconia balls having a diameter of 5 mm are placed in a 200 ml plastic bottle, 1.25 g of platinum-supported carbon particles (“TEC10E50E” manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., Pt: 45.6% by mass), 3.64 g of distilled water, n -11.91 g of propyl alcohol and 4.40 g of Nafion ™ D2020 were added, and the mixture was stirred with a paint shaker for 60 minutes to obtain a cathode electrode paste.

[Production of electrodes]
The anode electrode paste is applied with a doctor blade using a mask having an opening of 5 cm × 5 cm on one side of the polymer electrolyte membrane, and the surface not coated with the electrode paste has an opening of 5 cm × 5 cm. The cathode electrode paste was applied with a doctor blade using a mask. This was dried at 120 ° C. for 60 minutes. The amount of catalyst applied to each electrode catalyst layer was 0.50 mg / cm ² .

[Gas diffusion layer]
GDL24BC manufactured by SGL CARBON was used as the gas diffusion layer.
[Production of fuel cell]
The electrolyte membrane having the electrode catalyst layer formed on both sides is sandwiched between two gas diffusion layers and hot press molded under a pressure of 60 kg / cm ² and a temperature of 160 ° C. for 20 minutes to produce a membrane-electrode assembly. did. A separator also serving as a gas flow path is laminated on both sides of the obtained electrode-membrane assembly, sandwiched between two current collectors made of titanium, and a heater is disposed on the outside thereof, and an effective area of 25 cm ² is evaluated. A fuel cell was prepared.

[Performance evaluation]
(1) OCV durability test Air is supplied to the cathode electrode side of the evaluation fuel cell at a normal pressure and a flow rate of 0.2 L / min, and pure hydrogen is supplied to the anode electrode side at a flow rate of 0.2 L / min at normal pressure. The cell temperature was 90 ° C., the cathode electrode side relative humidity was 20%, and the anode electrode side relative humidity was 20%. The battery was operated for 300 hours in an open circuit state without power generation, and the voltage drop rate was measured. The results are shown in Table 1.

(2) Output voltage measurement before and after the OCV durability test Air was supplied to the cathode electrode side of the evaluation fuel cell at a back pressure of 120 kPa and a utilization rate of 40%, and the anode electrode side was pure at a back pressure of 120 kPa and a utilization rate of 70%. Hydrogen was supplied, and the cell voltage was measured at a current density of 1 A / cm ² before and after the OCV endurance test at a cell temperature of 80 ° C., a cathode electrode side relative humidity of 50%, and an anode electrode side relative humidity of 50%. The degree of decline was determined. The results are shown in Table 2.

[Example 2]
A film having a thickness of 40 μm was obtained in the same manner as in Example 1 except that the polymer B obtained in Synthesis Example 2-2 was used instead of the polymer A in Example 1. This film was found to have an amount of cerium oxide of 37 mg with respect to 1 g of the film, by the same ICP measurement as in Example 1. Moreover, when the same hot water immersion as in Example 1 was performed and ICP measurement was performed, it was found that there was no change in the amount of cerium before and after the hot water immersion, and the elution of the cerium oxide fine particles into the hot water did not occur. did. Using this film, the same OCV durability test as in Example 1 and evaluation of output voltage measurement before and after the OCV durability test were performed. The results are shown in Tables 1-2.

Example 3
0.8 g of the cerium oxide fine particles obtained in Synthesis Example 1 was added to 76 g of Nafion ^™ D2020 and dispersed using an ultrasonic generation homogenizer. Next, this dispersion was cast-coated on a PET film with a die coater, preliminarily dried at 80 ° C. for 40 minutes, and then dried at 120 ° C. for 40 minutes to obtain a film having a thickness of 40 μm. This film was found to have an amount of cerium oxide of 36 mg with respect to 1 g of the film by ICP measurement similar to that of Example 1. Moreover, when the same hot water immersion as in Example 1 was performed and ICP measurement was performed, it was found that there was no change in the amount of cerium before and after the hot water immersion, and the elution of the cerium oxide fine particles into the hot water did not occur. did. Using this film, the same OCV durability test as in Example 1 and evaluation of output voltage measurement before and after the OCV durability test were performed. The results are shown in Tables 1-2.

[Comparative Example 1]
In Example 1, a 40 μm-thick film was obtained in the same manner as in Example 1 except that the cerium oxide fine particles obtained in Synthesis Example 1 were not used. Using this film, the same OCV durability test as in Example 1 and evaluation of output voltage measurement before and after the OCV durability test were performed. The results are shown in Tables 1-2.

[Comparative Example 2]
In Example 1, in place of 0.79 g of cerium nitrate hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) instead of the cerium oxide fine particles obtained in Synthesis Example 1, the film thickness was the same as in Example 1. A 40 μm membrane was obtained. According to the same ICP measurement as in Example 1, this membrane had a cerium content of 0.11 mmol / g based on the total mass of the polymer A and the cerium component, and 4.6 mol% of sulfonic acid groups. There was found. Moreover, the hot water immersion similar to Example 1 was performed, and when ICP measurement was performed, it was found that there was no change in the amount of cerium before and after the hot water immersion, and no elution of cerium into the hot water occurred. Using this film, the same OCV durability test as in Example 1 and evaluation of output voltage measurement before and after the OCV durability test were performed. The results are shown in Tables 1-2.

[Comparative Example 3]
In Example 1, in place of the cerium oxide fine particles obtained in Synthesis Example 1, commercially available cerium oxide particles (manufactured by Junsei, number average secondary particle size 400 nm) were used in the same manner as in Example 1, A film having a thickness of 40 μm was obtained. This film was found to have an amount of cerium oxide of 46 mg with respect to 1 g of the film, by the same ICP measurement as in Example 1. Moreover, when the same hot water immersion as in Example 1 was performed and ICP measurement was performed, it was found that there was no change in the amount of cerium before and after the hot water immersion, and the elution of the cerium oxide fine particles into the hot water did not occur. did. Using this film, the same OCV durability test as in Example 1 and evaluation of output voltage measurement before and after the OCV durability test were performed. The results are shown in Tables 1-2.

[Comparative Example 4]
In Example 3, a film having a thickness of 40 μm was obtained in the same manner as Example 3 except that the cerium oxide fine particles obtained in Synthesis Example 1 were not used. Using this film, the same OCV durability test as in Example 1 and evaluation of output voltage measurement before and after the OCV durability test were performed. The results are shown in Tables 1-2.

〔評価結果〕
表１より、実施例１、２、及び比較例２、３は開回路電圧の低下速度が比較例１より小さく、実施例３は開回路電圧の低下速度が比較例４より小さいものであった。さらに、酸化セリウム微粒子を用いた実施例1は開回路電圧の低下速度が比較例３より小さいものであった。また、表２より、実施例１、２、及び比較例２、３はＯＣＶ耐久試験後の電流密度１Ａ／ｃｍ²でのセル電圧低下度が比較例１より小さく、実施例３はＯＣＶ耐久試験後の電流密度１Ａ／ｃｍ²でのセル電圧低下度が比較例４より小さいものであった。さらに、酸化セリウム微粒子を用いた実施例1はＯＣＶ耐久試験後の電流密度１Ａ／ｃｍ²でのセル電圧低下度が比較例３より小さいものであった。また、表２より、実施例１、２は電流密度１Ａ／ｃｍ²でのセル電圧の初期値が比較例２より高いものであった。以上より、本発明の電解質膜は発電性能に優れ、燃料電池の発電により生成される過酸化水素または過酸化物ラジカルに対する耐久性に優れているものである。

〔Evaluation results〕
From Table 1, Examples 1, 2 and Comparative Examples 2, 3 have a lower open circuit voltage decrease rate than Comparative Example 1, and Example 3 has an open circuit voltage decrease rate lower than Comparative Example 4. . Further, Example 1 using fine cerium oxide particles had a lower open circuit voltage reduction rate than Comparative Example 3. Also, from Table 2, Examples 1, 2 and Comparative Examples 2, 3 have a cell voltage decrease degree at a current density of 1 A / cm ² after the OCV durability test is smaller than that of Comparative Example 1, and Example 3 is an OCV durability test. The cell voltage drop at a later current density of 1 A / cm ² was smaller than that of Comparative Example 4. Furthermore, in Example 1 using the cerium oxide fine particles, the cell voltage drop degree at a current density of 1 A / cm ² after the OCV endurance test was smaller than that in Comparative Example 3. Also, from Table 2, Examples 1 and 2 were higher in cell voltage initial value than Comparative Example 2 at a current density of 1 A / cm ² . As described above, the electrolyte membrane of the present invention has excellent power generation performance and excellent durability against hydrogen peroxide or peroxide radicals generated by power generation of the fuel cell.

Claims (11)

Including a polymer having a sulfonic acid group, metal oxide particles,
The metal oxide particles are obtained by oxidizing a metal compound in the presence of at least one selected from a nonionic surfactant and an anionic surfactant,
The metal oxide particles include 0.01 to 30 wt% with respect to the total amount of the polymer and the metal oxide particles,
Metal oxide particles are aluminum, silicon, titanium, zirconium, zinc, tin, iron, bismuth, magnesium, yttrium, lead, manganese, germanium, copper, indium, beryllium, neodymium, lanthanum, niobium, tantalum, nickel, cobalt, A solid polymer electrolyte membrane characterized by being an oxide of a metal selected from gallium, cerium, molybdenum and tungsten and at least one of these composite oxides .   2. The solid polymer electrolyte membrane according to claim 1, wherein the metal oxide particles have a number average primary particle diameter of 1 nm to 20 nm and a number average secondary particle diameter of 30 nm to 200 nm.   3. The solid polymer electrolyte membrane according to claim 1, wherein the metal oxide particles are at least one selected from oxides of aluminum, titanium, zirconium, manganese, nickel, cobalt, or cerium.   The solid polymer electrolyte membrane according to claim 1, wherein the surfactant is a nonionic surfactant and is a polymer having a pyrrolidone group. Including a polymer having sulfonic acid groups, metal oxide particles, and a solvent;
The metal oxide particles are obtained by oxidizing a metal compound in the presence of at least one selected from a nonionic surfactant and an anionic surfactant,
The metal oxide particles are included in an amount of 0.01 to 30% by weight based on the whole of the polymer and the metal oxide particles,
Metal oxide particles are aluminum, silicon, titanium, zirconium, zinc, tin, iron, bismuth, magnesium, yttrium, lead, manganese, germanium, copper, indium, beryllium, neodymium, lanthanum, niobium, tantalum, nickel, cobalt, A liquid composition comprising at least one of an oxide of a metal selected from gallium, cerium, molybdenum, and tungsten and a composite oxide thereof. 6. The liquid composition according to claim 5, wherein the metal oxide particles have a number average primary particle diameter of 1 nm to 20 nm and a number average secondary particle diameter of 30 nm to 200 nm . The liquid composition according to claim 5 or 6, wherein the surfactant is a nonionic surfactant and is a polymer having a pyrrolidone group . A method for producing a liquid composition according to any one of claims 5 to 7,
A method for producing a liquid composition, which is obtained by mixing a polymer having a sulfonic acid group and a metal oxide in a solvent.   A method for producing a solid polymer electrolyte membrane, comprising casting the liquid composition according to claim 5.   5. A membrane-electrode assembly comprising the solid polymer electrolyte membrane according to claim 1 and a catalyst layer and a gas diffusion layer in contact with both sides of the solid polymer electrolyte membrane.   A polymer electrolyte fuel cell comprising the membrane-electrode assembly according to claim 10.