WO2012099118A1 - Polymer electrolyte membrane, membrane electrode assembly and fuel cell - Google Patents

Polymer electrolyte membrane, membrane electrode assembly and fuel cell Download PDF

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Publication number
WO2012099118A1
WO2012099118A1 PCT/JP2012/050851 JP2012050851W WO2012099118A1 WO 2012099118 A1 WO2012099118 A1 WO 2012099118A1 JP 2012050851 W JP2012050851 W JP 2012050851W WO 2012099118 A1 WO2012099118 A1 WO 2012099118A1
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polymer electrolyte
group
electrolyte membrane
ion exchange
fine particles
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PCT/JP2012/050851
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French (fr)
Japanese (ja)
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寛之 栗田
伸 齋藤
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住友化学株式会社
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/06—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances
    • H01B1/12—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances organic substances
    • H01B1/122—Ionic conductors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/102—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer
    • H01M8/1025—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having only carbon and oxygen, e.g. polyethers, sulfonated polyetheretherketones [S-PEEK], sulfonated polysaccharides, sulfonated celluloses or sulfonated polyesters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/102—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer
    • H01M8/1027—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having carbon, oxygen and other atoms, e.g. sulfonated polyethersulfones [S-PES]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1041—Polymer electrolyte composites, mixtures or blends
    • H01M8/1046—Mixtures of at least one polymer and at least one additive
    • H01M8/1051—Non-ion-conducting additives, e.g. stabilisers, SiO2 or ZrO2
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present invention relates to a polymer electrolyte membrane, a membrane electrode assembly, and a fuel cell.
  • fuel cells polymer electrolyte fuel cells
  • a fuel cell has a basic configuration of a cell (fuel cell) having a gas diffusion layer for supplying gas serving as power generation fuel to both surfaces of a membrane electrode assembly (hereinafter also referred to as “MEA”).
  • the membrane electrode assembly is a catalyst that promotes a redox reaction between hydrogen and oxygen as power generation fuel on both sides of a polymer electrolyte membrane containing a polymer having ion conductivity (hereinafter referred to as a polymer electrolyte).
  • An electrode called a catalyst layer is formed.
  • fluorine-based polymer electrolytes are mainly studied as polymer electrolyte membranes used in membrane electrode assemblies (see, for example, Patent Document 1), and examples of such fluorine-based polymer electrolytes include Nafion. (A registered trademark of DuPont) is known. Further, it is known that a fluorine-based polymer electrolyte is very expensive and has low heat resistance and membrane strength when applied to a fuel cell that requires high reliability. For this reason, studies have been made on hydrocarbon polymer electrolytes as materials that can be substituted for fluorine polymer electrolytes (see, for example, Patent Documents 2 and 3).
  • the polymer electrolyte membranes disclosed in the above-mentioned patent documents have low operational stability (hereinafter referred to as “long-term stability”) when long-term operation is performed.
  • long-term stability Various factors have been estimated as factors that hinder this long-term stability.
  • the film is deteriorated by a peroxide (for example, hydrogen peroxide) generated during battery operation or a radical generated from the peroxide.
  • the deterioration of the membrane is caused by a decrease in the molecular weight of the polymer electrolyte in the case of a fluorine-based polymer electrolyte membrane and the elution amount of fluorine ions contained in waste water, and in the case of a hydrocarbon-based polymer electrolyte membrane. May be observed.
  • radical resistance improves the durability of the polymer electrolyte membrane against peroxides and radicals. It is said that.
  • radicals generated from peroxide may be simply referred to as “radicals”.
  • antioxidants such as hindered phenolic antioxidants have been widely used for the purpose of suppressing melting deterioration during processing and oxidation deterioration that occurs over time. It has been.
  • antioxidants such as hindered phenolic antioxidants
  • it is insufficient for improving the long-term stability of the solid polymer fuel cell.
  • the present invention has been made in view of such circumstances, and an object thereof is to provide a polymer electrolyte membrane having high durability. Furthermore, to provide a membrane electrode assembly having the above-described polymer electrolyte membrane and having excellent long-term stability, and to providing a fuel cell having this membrane and electrode assembly and having excellent long-term stability. Is one of the purposes.
  • a polymer electrolyte membrane of the present invention comprises a film-like base material formed of a polymer electrolyte, and metal fine particles dispersed in the base material, and the metal
  • the fine particle forming material includes one or more metals selected from the group consisting of noble metals and noble metal alloys, and the metal fine particles are dispersed with a concentration gradient in the thickness direction of the base material.
  • the metal fine particles have a particle size of 500 nm or less.
  • the metal fine particle forming material is at least one of a noble metal or a noble metal alloy selected from the group of noble metals consisting of platinum, gold, palladium, iridium, rhodium and ruthenium, or both. It is desirable to include.
  • the polymer electrolyte membrane is composed of a hydrocarbon polymer electrolyte.
  • the hydrocarbon-based polymer electrolyte includes a block copolymer including a block having an ion exchange group and a block having substantially no ion exchange group.
  • a metal layer is laminated on the surface of the film-shaped base material formed of the polymer electrolyte, and a voltage is applied from both sides of the base material and the metal layer to apply the base. It is desirable to include the metal fine particles deposited inside the material.
  • the metal layer is formed by physical vapor deposition.
  • the metal layer is preferably formed by applying a liquid containing metal fine particles to the surface of the polymer electrolyte membrane.
  • the membrane electrode assembly of the present invention includes the above-described polymer electrolyte membrane, and an anode catalyst layer and a cathode catalyst layer that sandwich the polymer electrolyte membrane.
  • the maximum value of the concentration of the metal fine particles is on the cathode catalyst layer side with respect to the center in the film thickness direction of the polymer electrolyte membrane.
  • the fuel cell of the present invention has the above-described polymer electrolyte membrane.
  • the first aspect of the present invention is a film-like base material formed of a polymer electrolyte, Metal fine particles dispersed in the base material,
  • the metal fine particle forming material contains one or more metals selected from the group consisting of noble metals and noble metal alloys, and the metal fine particles are dispersed with a concentration gradient in the thickness direction of the base material. It is a molecular electrolyte membrane.
  • a second aspect of the present invention is the polymer electrolyte membrane according to the first aspect, wherein the concentration of the metal fine particles has a maximum value.
  • a third aspect of the present invention is the polymer electrolyte membrane according to the first or second aspect, wherein the metal fine particles have a particle diameter of 500 nm or less.
  • the metal fine particle forming material is selected from a noble metal group consisting of platinum, gold, palladium, iridium, rhodium and ruthenium, A polymer electrolyte membrane containing one or both of one kind of noble metal and noble metal alloy.
  • the polymer electrolyte is a polymer electrolyte membrane made of a hydrocarbon polymer electrolyte.
  • a block copolymer according to the fifth aspect wherein the hydrocarbon-based polymer electrolyte includes a segment having an ion exchange group and a segment having substantially no ion exchange group.
  • a polymer electrolyte membrane containing a polymer is provided.
  • a metal layer is laminated on a surface of a film-shaped base material formed of the polymer electrolyte, and the base material and the base material
  • the polymer electrolyte membrane includes the metal fine particles deposited inside the base material by applying a voltage from both sides of the metal layer.
  • An eighth aspect of the present invention is the polymer electrolyte membrane according to the seventh aspect, wherein the metal layer is formed by physical vapor deposition.
  • a ninth aspect of the present invention is the polymer electrolyte membrane according to the seventh aspect, wherein the metal layer is formed by applying a liquid containing metal fine particles to the surface of the base material.
  • a membrane electrode junction comprising the polymer electrolyte membrane according to any one of the first to ninth aspects, and an anode catalyst layer and a cathode catalyst layer sandwiching the polymer electrolyte membrane. Is the body.
  • An eleventh aspect of the present invention is the membrane electrode assembly according to the tenth aspect, wherein the maximum value of the concentration of the metal fine particles is closer to the cathode catalyst layer side than the center in the film thickness direction of the polymer electrolyte membrane. It is.
  • a twelfth aspect of the present invention is a fuel cell having the membrane electrode assembly according to the tenth or eleventh aspect.
  • a highly durable polymer electrolyte membrane can be obtained.
  • the membrane electrode assembly excellent in long-term stability can be obtained by using such a polymer electrolyte membrane.
  • a fuel cell having excellent long-term stability can be obtained.
  • achieve such high durability can be manufactured easily.
  • FIG. 1 is an electron micrograph showing the inside of a polymer electrolyte membrane according to a preferred embodiment of the present invention.
  • FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention.
  • FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention.
  • FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention.
  • FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention.
  • FIG. 1 is an electron micrograph showing the inside of a polymer electrolyte membrane according to a preferred embodiment of the present invention.
  • FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte
  • FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention.
  • FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention.
  • FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention.
  • FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention.
  • FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention.
  • FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention.
  • FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention.
  • FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention.
  • FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention.
  • FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention.
  • FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention.
  • FIG. 1 is a longitudinal sectional view of a cell of a fuel cell having a membrane electrode assembly according to a preferred embodiment of the present invention (hereinafter sometimes simply referred to as a fuel cell).
  • the fuel cell 10 includes a membrane electrode assembly (MEA) 20 composed of a polymer electrolyte membrane 12 and a pair of catalyst layers 14a and 14b sandwiched therebetween.
  • MEA membrane electrode assembly
  • a structure composed of the membrane electrode assembly 20 and the gas diffusion layers 16a and 16b may be generally called a membrane electrode-gas diffusion layer assembly (MEGA).
  • MEGA membrane electrode-gas diffusion layer assembly
  • the anode catalyst layer 14 a and the cathode catalyst layer 14 b are layers that function as electrode layers in the fuel cell 10.
  • the anode catalyst layer 14a and the cathode catalyst layer 14b include an electrode catalyst and a polymer electrolyte having proton conductivity such as perfluoroalkyl sulfonic acid resin.
  • the electrode catalyst is not particularly limited as long as it can activate a redox reaction with hydrogen or oxygen, and a known electrode catalyst can be used, but platinum or platinum-based alloy fine particles are used as a catalyst. It is preferable to use it.
  • the fine particles of platinum or platinum-based alloys are often used by being supported on particulate or fibrous carbon such as activated carbon or graphite.
  • the gas diffusion layers 16a and 16b are layers having a function of promoting the diffusion of the raw material gas into the catalyst layers 14a and 14b.
  • the gas diffusion layers 16a and 16b are preferably made of a porous material having electron conductivity.
  • a porous carbon nonwoven fabric or carbon paper is preferable because the raw material gas can be efficiently transported to the catalyst layers 14a and 14b.
  • Separator 18a, 18b is formed with the material which has electronic conductivity.
  • Examples of the material having electron conductivity include carbon, resin mold carbon, titanium, and stainless steel.
  • the fuel cell manufactured in this way can be used in various forms using, for example, hydrogen gas, reformed hydrogen gas, and methanol as fuel.
  • the membrane electrode assembly 20 shown in FIG. 10 has a pair of catalyst layers 14a and 14b that sandwich the polymer electrolyte membrane 12 as described above.
  • FIG. 2 is a transmission electron micrograph showing the inside of the polymer electrolyte membrane 12.
  • the polymer electrolyte membrane 12 of the present embodiment includes a base material 12X using a polymer electrolyte as a forming material and metal fine particles 13A dispersed in the base material 12X.
  • the metal fine particles 13A are shown as black spots in the photograph of FIG.
  • polymer electrolyte constituting the base material of the polymer electrolyte membrane 12 examples include hydrocarbon polymer electrolytes and fluorine polymer electrolytes as described below. Further, as components other than the polymer electrolyte constituting the base material 12X, additives such as plasticizers, stabilizers, mold release agents, water retention agents and the like used for ordinary polymers can be mentioned.
  • Hydrocarbon polymer electrolyte First, a hydrocarbon polymer electrolyte that can be used for the polymer electrolyte membrane in one embodiment of the present invention will be described.
  • the hydrocarbon polymer electrolyte means a polymer electrolyte having a halogen atom content of 15% by mass or less in terms of the mass content ratio of elements constituting the polymer electrolyte.
  • a hydrocarbon-based polymer electrolyte is more preferable because it has an advantage that it is cheaper than the above-mentioned fluorine-based polymer electrolyte.
  • Particularly preferred hydrocarbon polymer electrolytes are hydrocarbon polymer electrolytes that do not substantially contain halogen atoms. Such hydrocarbon polymer electrolytes do not generate hydrogen halide during the operation of the fuel cell. There is no danger of corrosion and corrosion of other components.
  • the “hydrocarbon polymer electrolyte” mentioned here may contain a hetero atom.
  • the hydrocarbon-based polymer electrolyte is preferably a polymer having an ion exchange group.
  • the reason is that when a polymer electrolyte membrane for a fuel cell is obtained using a polymer electrolyte having an ion exchange group, the ion conductivity of the polymer electrolyte membrane is improved.
  • the ion exchange group examples include an acidic ion exchange group (that is, a cation exchange group) or a basic ion exchange group (that is, an anion exchange group). From the viewpoint of obtaining high proton conductivity, the ion exchange group is preferably a cation exchange group. By using a polymer electrolyte having a cation exchange group, a fuel cell having further excellent power generation performance can be obtained.
  • the cation exchange group examples include a sulfo group (—SO 3 H), a carboxyl group (—COOH), a phosphono group (—PO 3 H 2 ), a sulfonylimide group (—SO 2 NHSO 2 —), a phenolic hydroxyl group, and the like. Is mentioned. Among these, as the cation exchange group, a sulfo group or a phosphono group is more preferable, and a sulfo group is particularly preferable. These ion exchange groups may be partially or wholly exchanged with metal ions or quaternary ammonium ions to form a salt, but when used as a fuel cell member, It is preferred that substantially all are in the free acid form. When the ion exchange group is in the form of a free acid, there is an advantage that the preparation of the polymer electrolyte solution becomes easier in the production of the laminated film described later.
  • ion exchange groups may be introduced into either or both of the main chain or side chain of the polymer electrolyte, but are preferably introduced into the main chain.
  • the introduction amount of the ion exchange group can be represented by an ion exchange group capacity which is the number of ion exchange groups per unit mass of the polymer electrolyte.
  • the “ion exchange group capacity” is a value [milli equivalent / g dry resin] defined by the number of equivalents of ion exchange groups contained in 1 g of dry resin in the polymer electrolyte constituting the polymer electrolyte membrane.
  • meq / g meq / g
  • dry resin refers to a resin in which the polymer electrolyte is maintained at a temperature equal to or higher than the boiling point of water, the mass decrease hardly occurs, and the change in mass with time converges to a substantially constant value.
  • the amount of ion exchange groups introduced is preferably 0.5 meq / g or more and 6.0 meq / g or less in terms of ion exchange capacity; 1.0 meq / g or more and 6.0 meq. / G or less; more preferably 2.0 meq / g or more and 5.5 meq / g or less; and most preferably 2.7 meq / g or more and 5.0 meq / g or less.
  • the polymer electrolyte membrane to be obtained has better proton conductivity and water resistance, both of which are excellent because the function as a polymer electrolyte membrane used in a fuel cell is excellent.
  • polymer electrolyte having a suitable ion exchange group examples include polymer electrolytes represented by the following (A) to (F).
  • A a polymer electrolyte in which an ion exchange group is introduced into a polymer whose main chain is an aliphatic hydrocarbon
  • B a polymer electrolyte in which an ion exchange group is introduced into a polymer in which the main chain is composed of an aliphatic hydrocarbon and a part of the hydrogen atoms of the main chain is substituted with fluorine atoms
  • C a polymer electrolyte in which an ion exchange group is introduced into a polymer having a main chain having an aromatic ring
  • D a polymer electrolyte in which an ion exchange group is introduced into a polymer whose main chain has an inorganic unit structure such as a siloxane group or a phosphazene group;
  • a polymer electrolyte whose ion exchange group is a sulfo group is mainly exemplified, but a polymer electrolyte in which this sulfo group is replaced with another ion exchange group may be used.
  • polymer electrolyte (A) examples include polyvinyl sulfonic acid, polystyrene sulfonic acid, poly ( ⁇ -methylstyrene) sulfonic acid, and the like.
  • polymer electrolyte (B) a polymer produced by copolymerization of a fluorocarbon vinyl monomer and a hydrocarbon vinyl monomer described in JP-A-9-102322 has a main chain, and a sulfo group.
  • a sulfonic acid type polystyrene-graft-ethylene-tetrafluoroethylene copolymer (ETFE) having a hydrocarbon chain having a side chain as a side chain and a copolymerization mode of graft polymerization is exemplified.
  • a copolymer of a fluorocarbon vinyl monomer and a hydrocarbon vinyl monomer obtained by the method described in US Pat. No. 4,012,303 or US Pat.
  • sulfonic acid type poly (trifluorostyrene) -graft-ETFE in which a solid polymer electrolyte is prepared by graft polymerization of, ⁇ , ⁇ -trifluorostyrene and introducing a sulfo group into the polymer.
  • the polymer electrolyte (C) may be a polymer electrolyte containing a hetero atom such as an oxygen atom in the main chain.
  • a polymer electrolyte examples include polyether ketone, polyether ether ketone, polysulfone, polyether sulfone, polyether ether sulfone, poly (arylene ether), polyimide, poly ((4-phenoxybenzoyl) -1, Examples thereof include polymer electrolytes each having a sulfo group introduced into each of homopolymers such as 4-phenylene) and polyphenylquinoxalen.
  • the polymer electrolyte (C) may be a compound in which the main chain is interrupted by a heteroatom such as an oxygen atom.
  • Such polymer electrolytes are disclosed in JP-A-9-110882 and J.P. Appl. Polym. Sci. 18, 1969 (1974).
  • Examples of the polymer electrolyte (D) include a polymer electrolyte in which a sulfo group is introduced into polyphosphazene. These are Polymer Prep. , 41, no. 1, 70 (2000).
  • the polymer electrolyte (E) may be any of a random copolymer having a sulfo group introduced therein, an alternating copolymer having a sulfo group introduced therein, or a block copolymer having a sulfo group introduced therein. .
  • polymer electrolyte (F) examples include polybenzimidazole into which phosphoric acid is introduced as described in JP-A-11-503262.
  • the polymer electrolyte used for the polymer electrolyte membrane in one embodiment of the present invention is preferably a copolymer composed of a structural unit having an ion exchange group and a structural unit having no ion exchange group.
  • the polymer electrolyte membrane prepared by the method described later using the resulting polymer electrolyte exhibits good proton conductivity and water resistance, and is advantageous for fuel cells.
  • the copolymerization mode of the two kinds of structural units may be any of random copolymerization, block copolymerization, graft copolymerization or alternating copolymerization, and these copolymerization modes are combined. Also good.
  • the hydrocarbon polymer electrolyte particularly a hydrocarbon polymer electrolyte having an aromatic ring in the main chain (that is, the above-mentioned (C) a hydrocarbon-based polymer electrolyte) is preferred; and further has an aromatic ring constituting the main chain, and is directly bonded to the aromatic ring or indirectly through another atom or atomic group Hydrocarbon polymer electrolytes having bound ion exchange groups are preferred.
  • it may have aromatics constituting the main chain, and may further have side chains having aromatic rings, and directly bonded to either the aromatic ring constituting the main chain or the aromatic ring of the side chain.
  • An aromatic polymer electrolyte having an ion exchange group is preferred.
  • aromatic polymer electrolytes include polymer electrolytes having a structural unit having an ion exchange group in the molecular structure and a structural unit having no ion exchange group.
  • Examples of the structural unit having an ion exchange group include structures represented by the following formulas (11a) to (14a).
  • Ar 1 to Ar 9 are the same or different and each represents a divalent aromatic group which may have a side chain having an aromatic ring in the main chain and further having an aromatic ring; A group is directly bonded to at least one of the aromatic ring of the main chain or the aromatic ring of the side chain; Z and Z ′ are the same or different and each represents a group represented by —CO— or a group represented by —SO 2 —; X, X ′, and X ′′ are the same or different —O— Y represents a direct bond or a group represented by the following formula (15); p represents 0, 1 or 2; q and r represent Each represents the same or different and represents 1, 2 or 3.)
  • examples of the structural unit having no ion exchange group include structures represented by the following formulas (11b) to (14b).
  • Ar 11 to Ar 19 are the same or different and each represents a divalent aromatic group which may have a substituent as a side chain;
  • Z and Z ′ are the same or different and each represents a group represented by —CO— or a group represented by —SO 2 —;
  • X, X ′ and X ′′ are the same or different —O— Or
  • Y represents a direct bond or a group represented by the following formula (15);
  • p ′ represents 0, 1 or 2
  • q ′ And r ′ are the same or different and represent 1, 2 or 3.
  • R 1 and R 2 are the same or different and each is a hydrogen atom, an optionally substituted alkyl group having 1 to 20 carbon atoms, or an optionally substituted carbon group having 1 to 20 alkoxy groups, optionally substituted aryl groups having 6 to 20 carbon atoms, optionally substituted aryloxy groups having 6 to 20 carbon atoms, or substituted groups.
  • Ar 1 to Ar 9 represent a divalent aromatic group.
  • the divalent aromatic group include divalent monocyclic aromatic hydrocarbon groups such as 1,3-phenylene group and 1,4-phenylene group; 1,3-naphthalenediyl group, 1,4- Divalent condensed rings such as naphthalenediyl group, 1,5-naphthalenediyl group, 1,6-naphthalenediyl group, 1,7-naphthalenediyl group, 2,6-naphthalenediyl group, 2,7-naphthalenediyl group, etc.
  • Ar 1 to Ar 9 in the formulas (11a) to (14a) are preferably divalent monocyclic aromatic hydrocarbon groups such as 1,3-phenylene group and 1,4-phenylene group; -Naphthalenediyl group, 1,4-naphthalenediyl group, 1,5-naphthalenediyl group, 1,6-naphthalenediyl group, 1,7-naphthalenediyl group, 2,6-naphthalenediyl group, 2,7-naphthalene
  • a divalent condensed ring aromatic hydrocarbon group such as a diyl group; and more preferably a divalent monocyclic aromatic hydrocarbon group.
  • the hydrogen atom on the aromatic ring of the aromatic group represented by Ar 1 to Ar 9 in formulas (11a) to (14a) is an optionally substituted alkyl group having 1 to 20 carbon atoms, An optionally substituted alkoxy group having 1 to 20 carbon atoms, an optionally substituted aryl group having 6 to 20 carbon atoms, and an optionally substituted carbon group having 6 to 20 carbon atoms.
  • the aryloxy group may be substituted with an acyl group having 2 to 21 carbon atoms which may have a substituent.
  • the aromatic groups represented by Ar 1 to Ar 9 in formulas (11a) to (14a) have at least one ion exchange group in the aromatic ring.
  • Specific examples and preferred examples of the ion exchange group can be the same as those described above.
  • These ion exchange groups may be introduced into one or both of the main chain and the side chain of the polymer electrolyte, but are preferably introduced into the aromatic ring of the main chain.
  • an acidic ion exchange group is preferable as described above, and among the acidic ion exchange groups, a sulfo group or a phosphono group is more preferable, and a sulfo group is particularly preferable.
  • Ar 110 , Ar 120 , and Ar 130 each independently represent a divalent aromatic group, and the hydrogen atom on the aromatic ring may be substituted with a fluorine atom.
  • Y 000 represents —CO—, —SO 2 —, —SO—, —CONH—, —COO— , — (CF 2 ) u000 — (u000 is an integer of 1 to 10), —C (CF 3 ) 2 - or a direct bond are shown;
  • Z 000 is, -O -, - S-, a direct bond, -CO -, - SO 2 - , - SO -, - (CH 2) k000 - (k000 1-10
  • R 110 represents a direct bond, —O (CH 2 ) p000 —, —O (CF 2 ) p000 —, — (CH 2 ) p000 —, or —C (CH 3 ) 2 — - (CF 2) p000
  • Ar 110 , Ar 120 and Ar 130 in the formula (14a-1) represent a divalent aromatic group.
  • Examples of such a divalent aromatic group include the same divalent aromatic groups as Ar 1 to Ar 9 in formulas (11a) to (14a).
  • R 120 and R 130 each independently represent a hydrogen atom, an alkali metal atom or a hydrocarbon group.
  • the alkali metal atom include lithium, sodium, potassium, rubidium, and cesium.
  • the hydrocarbon group may have a heterocyclic group, and examples of such a hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, a tert-butyl group, an iso group.
  • heptyl group bicyclo [2.2.1] heptylmethyl group, tetrahydrofurfuryl group, 2-methylbutyl group, 3,3-dimethyl-2,4-dioxolanemethyl group, cyclohexylmethyl group, adamantylmethyl
  • a straight-chain hydrocarbon group such as a bicyclo [2.2.1] heptylmethyl group, a branched hydrocarbon group, Cyclic hydrocarbon group, and hydrocarbon group having a heterocyclic group.
  • R 120 and R 130 are preferably hydrogen atoms.
  • the structural unit represented by the above formula (14a-1) is preferably a structural unit represented by the following formula (14a-2).
  • Y 001 is —CO—, —SO 2 —, —SO—, —CONH—, —COO—, — (CF 2 ) h — (where h is 1 to 10).
  • An integer) and at least one structure selected from the group consisting of —C (CF 3 ) 2 —;
  • Z 001 represents a direct bond or — (CH 2 ) g — (where g is 1 to And an at least one structure selected from the group consisting of —C (CH 3 ) 2 —, —O—, —S—, —CO— and —SO 2 —;
  • Ar 001 represents — An aromatic group having a substituent represented by SO 3 H, —O (CH 2 ) p SO 3 H or —O (CF 2 ) p SO 3 H;
  • p represents an integer of 1 to 12;
  • n001 represents an integer of 0 to 10;
  • k001 represents an
  • structural unit having an ion exchange group represented by the above formula (14a-2) include structural units represented by the following formulas (4a-13) to (4a-20).
  • Ar 11 to Ar 19 each independently represent a divalent aromatic group.
  • divalent aromatic groups include divalent monocyclic aromatic hydrocarbon groups such as 1,3-phenylene group and 1,4-phenylene group; 1,3-naphthalenediyl group, 1 , 4-Naphthalenediyl group, 1,5-naphthalenediyl group, 1,6-naphthalenediyl group, 1,7-naphthalenediyl group, 2,6-naphthalenediyl group, 2,7-naphthalenediyl group, etc.
  • Ar 11 to Ar 19 in the formulas (11b) to (14b) are preferably divalent monocyclic aromatic hydrocarbon groups such as 1,3-phenylene group and 1,4-phenylene group, 1,3 -Naphthalenediyl group, 1,4-naphthalenediyl group, 1,5-naphthalenediyl group, 1,6-naphthalenediyl group, 1,7-naphthalenediyl group, 2,6-naphthalenediyl group, 2,7-naphthalene It is a divalent fused ring aromatic hydrocarbon group such as a diyl group, and more preferably a divalent monocyclic aromatic hydrocarbon group.
  • the hydrogen atom on the aromatic ring of the aromatic group represented by Ar 11 to Ar 19 is a fluorine atom, a formyl group, a cyano group, an alkyl group having 1 to 20 carbon atoms which may have a substituent, An optionally substituted alkoxy group having 1 to 20 carbon atoms, an optionally substituted aryl group having 6 to 20 carbon atoms, and an optionally substituted carbon group having 6 to 20 carbon atoms.
  • the aryloxy group may be substituted with an acyl group having 2 to 21 carbon atoms which may have a substituent.
  • the “optionally substituted” substituent here does not include the ion exchange group.
  • divalent aromatic groups (the aromatic groups represented by Ar 1 to Ar 9 in the formulas (11a) to (14a) and the Ar 11 to Ar 19 in the formulas (11b) to (14b) are represented.
  • substituent of the aromatic group are as follows.
  • Examples of the optionally substituted alkyl group having 1 to 20 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, n -Pentyl group, 2,2-dimethylpropyl group, cyclopentyl group, n-hexyl group, cyclohexyl group, 2-methylpentyl group, 2-ethylhexyl group, nonyl group, dodecyl group, hexadecyl group, octadecyl group, icosyl group, etc.
  • Alkyl groups having 1 to 20 carbon atoms include fluorine atom, hydroxyl group, nitrile group, amino group, methoxy group, ethoxy group, isopropyloxy group, phenyl group, naphthyl group, phenoxy group, naphthyloxy group, etc. Examples thereof include an alkyl group which is substituted and has a total carbon number of 20 or less.
  • Examples of the optionally substituted alkoxy group having 1 to 20 carbon atoms include methoxy group, ethoxy group, n-propyloxy group, isopropyloxy group, n-butyloxy group, sec-butyloxy group, tert- Butyloxy, isobutyloxy, n-pentyloxy, 2,2-dimethylpropyloxy, cyclopentyloxy, n-hexyloxy, cyclohexyloxy, 2-methylpentyloxy, 2-ethylhexyloxy, dodecyl
  • An alkoxy group having 1 to 20 carbon atoms such as an oxy group, a hexadecyloxy group, an icosyloxy group; and these groups include a fluorine atom, a hydroxyl group, a nitrile group, an amino group, a methoxy group, an ethoxy group, an isopropyloxy group, and a phenyl
  • aryl groups such as a phenyl group, a naphthyl group, a phenanthrenyl group, and an anthracenyl group; and these groups include a fluorine atom, a hydroxyl group, and a nitrile.
  • Group, amino group, methoxy group, ethoxy group, isopropyloxy group, phenyl group, naphthyl group, phenoxy group, naphthyloxy group and the like are substituted, and aryl groups having a total carbon number of 20 or less can be mentioned.
  • aryloxy group having 6 to 20 carbon atoms which may have a substituent include aryloxy groups such as a phenoxy group, a naphthyloxy group, a phenanthrenyloxy group, and an anthracenyloxy group; Are substituted with fluorine atom, hydroxyl group, nitrile group, amino group, methoxy group, ethoxy group, isopropyloxy group, phenyl group, naphthyl group, phenoxy group, naphthyloxy group, etc.
  • a certain aryloxy group is mentioned.
  • Examples of the optionally substituted acyl group having 2 to 21 carbon atoms include acetyl group, propionyl group, butyryl group, isobutyryl group, pivaloyl group, benzoyl group, 1-naphthoyl group, and 2-naphthoyl group.
  • an acyl group having a total carbon number of 21 or less isopropyloxy group, phenyl group, naphthyl group, phenoxy group, naphthyloxy group, etc.
  • the substituent is an aryl group such as a phenyl group, a naphthyl group, a phenanthrenyl group or an anthracenyl group; an aryloxy group such as a phenoxy group, a naphthyloxy group, a phenanthrenyloxy group or an anthracenyloxy group; a benzoyl group, 1 -A substituent having an aromatic ring such as an acyl group having an aromatic ring such as a naphthoyl group or a 2-naphthoyl group tends to improve the heat resistance of the polymer, and a more practical fuel cell member can be obtained. Therefore, it is preferable.
  • a polyelectrolyte including a polymer having an acyl group having an aromatic ring as a substituent two structural units having the acyl group are adjacent to each other, and the acyl groups in the two structural units are bonded to each other.
  • the structure may change by causing a rearrangement reaction after the groups are bonded to each other. Whether or not such a structural change has occurred can be confirmed, for example, by measuring a 13 C-nuclear magnetic resonance spectrum.
  • One of the preferable elements of the hydrocarbon-based polymer electrolyte in the present invention is a polymer electrolyte having a halogen atom content of 15% by mass or less in terms of the mass content ratio of elements constituting the polymer electrolyte.
  • Such hydrocarbon polymer electrolytes have the advantage of being inexpensive compared to the fluorine polymer electrolytes described above, and therefore more preferred, particularly preferred hydrocarbon polymer electrolytes substantially contain halogen atoms. This hydrocarbon polymer electrolyte does not generate hydrogen halide during the operation of the fuel cell and does not corrode other members.
  • the hydrocarbon-based polymer electrolyte includes a structural unit having an ion exchange group and a structural unit not having an ion exchange group, and a dense phase of the structural unit having an ion exchange group forms a continuous phase in the film thickness direction. If it can be formed, it is preferable because there is an advantage that a polymer electrolyte membrane having more excellent proton conductivity can be obtained.
  • suitable polymer electrolytes are represented by the structural units having an ion exchange group composed of the structural units represented by the formulas (11a) to (14a) and the formulas (11b) to (14b). And a structural unit having no ion-exchange group.
  • a polymer electrolyte can be obtained as a copolymer starting from monomers or oligomers corresponding to a structural unit having an ion exchange group and a structural unit having no ion exchange group.
  • examples of the combination of a structural unit having an ion exchange group and a structural unit having no ion exchange group include the combinations shown in ⁇ A> to ⁇ M> in Table 1 below.
  • the structure of the polymer electrolyte preferably used in the present invention is more preferably ⁇ B>, ⁇ C>, ⁇ D>, ⁇ G>, ⁇ H>, ⁇ I>, ⁇ J>, ⁇ L>.
  • ⁇ M> even more preferably ⁇ G>, ⁇ H>, ⁇ L> or ⁇ M>; and particularly preferably ⁇ G>, ⁇ H> or ⁇ L>.
  • suitable copolymers include one or more structural units selected from the group of structural units having ion exchange groups shown below, and a group of structural units having no ion exchange groups shown below. And a copolymer composed of one or more structural units.
  • the ion exchange group in the repeating unit which has an ion exchange group is illustrated by the suitable sulfo group.
  • any of the above-described ion exchange groups may be employed instead of the sulfo group.
  • these structural units may be directly bonded to each other, or may be connected to each other with an appropriate atom or atomic group.
  • an atom or an atomic group for bonding structural units here a divalent aromatic group, an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or a divalent group formed by combining these is used. Can be mentioned.
  • r000 represents 0 or an integer of 1 or more; r000 is preferably 100 or less, more preferably 1 or more and 80 or less.
  • the formulas representing the structural unit having an ion exchange group include the formulas (4a-1), (4a-2), (4a-3), (4a-4), (4a-5), ( 1a or more selected from the group consisting of 4a-6), (4a-7), (4a-8), (4a-9), (4a-10), (4a-11), and (4a-12)
  • the structural unit is preferred.
  • one or more structural units selected from the group consisting of formulas (4a-10), (4a-11), and (4a-12) are more preferred, and formula (4a-11) or (4a-12) Is particularly preferred.
  • a polymer electrolyte having a segment containing such a structural unit particularly a polymer electrolyte having a segment containing such a structural unit as a repeating unit (segment having an ion exchange group) has a polyarylene structure. Therefore, the chemical stability tends to be relatively good.
  • the formulas representing the structural unit having no ion exchange group include formulas (4b-1), (4b-2), (4b-3), (4b-4), (4b-5), (4b- 6), (4b-7), (4b-8), (4b-9), (4b-10), (4b-11), (4b-12), (4b-13), and (4b-14) And one or more structural units selected from the group consisting of Similarly, one or more structural units selected from the group consisting of formulas (4b-2), (4b-3), (4b-10), (4b-13), and (4b-14) are more preferred; One or more structural units selected from the group consisting of formulas (4b-2), (4b-3), and (4b-14) are particularly preferred.
  • the polymer electrolyte according to the present invention is a polymer electrolyte having a structural unit having an ion exchange group and a structural unit not having an ion exchange group, and the copolymerization mode of these two structural units is random copolymerization.
  • Preferred are random copolymerization, block copolymerization, and graft copolymerization; more preferred are random copolymerization and block copolymerization; and particularly preferred is block copolymerization.
  • a segment mainly composed of a structural unit having an ion exchange group (segment having an ion exchange group) and a segment mainly composed of a structural unit not having an ion exchange group (that is, substantially having an ion exchange group) And a copolymer having a segment not included).
  • a block copolymer has an advantage that a polymer electrolyte membrane having more excellent proton conductivity can be obtained by forming a continuous phase in the film thickness direction with a dense phase having segments having ion exchange groups.
  • combinations of structural units constituting a segment having a suitable ion exchange group and structural units constituting a segment having substantially no ion exchange group are shown in ⁇ A> to ⁇ M> in Table 2 below. A combination of segments can be mentioned.
  • formulas (4a-1), (4a-2), (4a-3), (4a-4) represent the structural units used for the repeating units constituting the segment having an ion exchange group.
  • (4a-5), (4a-6), (4a-7), (4a-8), (4a-9), (4a-10), (4a-11) and (4a-12) One or more structural units selected from the group are preferred; one or more structural units selected from the group consisting of the formulas (4a-10), (4a-11), and (4a-12) are more preferred; 4a-11) or (4a-12) is particularly preferred.
  • the block copolymer according to the present invention is that the main chain of the segment having an ion exchange group has a polyarylene structure formed by substantially directly connecting a plurality of aromatic rings.
  • the structural unit of such a segment preferably the above formulas (4a-10), (4a-11), (4a-12), (4a-13), (4a-14), (4a-15), One or more structural units selected from the group consisting of (4a-16), (4a-17), (4a-18), (4a-19) and (4a-20) are preferred, and are represented by the formula (4a-10) , One or more structural units selected from the group consisting of (4a-11) and (4a-12) are more preferred, and formula (4a-11) or (4a-12) is particularly preferred.
  • a polymer electrolyte having a segment including a repeating unit composed of such a structural unit that is, a segment having an ion exchange group
  • a polymer electrolyte having a segment composed of such a repeating unit has excellent ion conductivity. Since this segment has a polyarylene structure, chemical stability tends to be relatively good.
  • the “polyarylene structure” is a form in which the aromatic rings constituting the main chain are substantially directly bonded to each other. Specifically, the total number of bonds between the aromatic rings is 100. %, The direct bond ratio is preferably 80% or more, more preferably 90% or more, and still more preferably 95% or more.
  • bonded by the direct bond are forms in which aromatic rings are couple
  • the formulas representing the structural units used for the repeating units constituting the segment having no ion exchange group include the formulas (4b-1), (4b-2), (4b-3), (4b-4), (4b -5), (4b-6), (4b-7), (4b-8), (4b-9), (4b-10), (4b-11), (4b-12), (4b-13) ) And (4b-14) are preferred; one or more structural units selected from the group consisting of: (4b-2), (4b-3), (4b-9), (4b-10), (4b- More preferred is one or more structural units selected from the group consisting of 13) and (4b-14); consisting of formulas (4b-2), (4b-3), (4b-13) and (4b-14) Even more preferred are one or more structural units selected from the group; formulas (4b-2), (4b-3) and ( b-14) 1 or more structural units selected from the group consisting of especially preferred.
  • the segment having an ion exchange group and the segment having substantially no ion exchange group may be directly bonded or may be connected by an appropriate atom or atomic group.
  • atoms or atomic groups connecting the segments a divalent aromatic group, an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or a divalent group formed by combining these is given. be able to.
  • divalent aromatic group include the same divalent aromatic groups as Ar 1 to Ar 9 in formulas (11a) to (14a).
  • Suitable block copolymers include a segment containing one or more structural units selected from the group of structural units having an ion exchange group shown above (ie, a segment having an ion exchange group), and A block copolymer comprising a segment containing one or more structural units selected from the group of structural units having no ion exchange group shown above (that is, a segment having substantially no ion exchange group). Can be mentioned.
  • the “segment having an ion exchange group” means that the ion exchange group is a segment containing an average of 0.5 or more per structural unit constituting the segment. It is more preferable that one or more ion exchange groups are contained on an average per unit.
  • the “segment substantially having no ion exchange group” means that the ion exchange group is a segment having an average of less than 0.5 per structural unit constituting the segment, More preferably, the number of ion exchange groups per unit is 0.1 or less on average; more preferably 0.05 or less on average.
  • a block copolymer in a form in which a segment having an ion exchange group and a segment having substantially no ion exchange group are bonded by a direct bond or bonded by an appropriate atom or atomic group. is there.
  • the degree of polymerization of the segment composed of one or more structural units selected from the structural units represented by the above formulas (11a) to (14a) is 2 or more, preferably 3 or more; more preferably 5 or more; Further preferred.
  • the polymerization degree of the segment is preferably 1000 or less; preferably 500 or less. If the degree of polymerization is 2 or more, preferably 5 or more, sufficient proton conductivity is expressed as a polymer electrolyte for a fuel cell, and if the degree of polymerization is 1000 or less, the advantage is that manufacture is easier. There is. That is, the polymerization degree of the segment is preferably 2 or more and 1000 or less; more preferably 5 or more and 1000 or less; more preferably 5 or more and 500 or less; and most preferably 10 or more and 500 or less.
  • the degree of polymerization of a segment composed of one or more structural units selected from the structural units represented by formulas (11b) to (14b) is 1 or more, preferably 2 or more; more preferably 3 or more. Further, the polymerization degree of the segment is preferably 100 or less; more preferably 90 or less; and still more preferably 80 or less. If the degree of polymerization is within such a range, it is preferable as a polymer electrolyte for a fuel cell because it has sufficient mechanical strength and is easy to produce. That is, the polymerization degree of the segment is preferably 1 or more and 100 or less; more preferably 2 or more and 90 or less; and further preferably 3 or more and 80 or less.
  • the molecular weight of the hydrocarbon-based polymer electrolyte used in the present invention is preferably 5000 to 1,000,000, more preferably 10,000 to 800,000, more preferably 10,000 to 600,000 in terms of polystyrene-reduced number average molecular weight. More preferably, it is more preferably 15,000 to 400,000.
  • a polymer electrolyte having a molecular weight in such a range a polymer electrolyte membrane prepared by a method described later tends to stably maintain the shape of the membrane.
  • the number average molecular weight is measured by gel permeation chromatography (GPC).
  • fluorine-type polymer electrolyte which can be used for the polymer electrolyte membrane in one Embodiment of this invention
  • the normally known fluorine-type polymer electrolyte can be illustrated.
  • a fluorine-based polymer electrolyte in which hydrogen atoms in the above-described hydrocarbon-based polymer electrolyte are substituted with fluorine atoms can be used.
  • a perfluoroalkyl sulfonic acid polymer or a perfluorocarboxylic acid polymer can be mentioned.
  • fluorine polymer electrolytes such as Nafion (registered trademark of DuPont), Aciplex (Asahi Kasei registered trademark) manufactured by Asahi Kasei, Flemion (Asahi Glass registered trademark) manufactured by Asahi Glass, and the above-mentioned JP-A No. 2003-113136.
  • the described fluorine-based polymer electrolytes can also be used.
  • the “fluorine polymer electrolyte” means a polymer electrolyte having a fluorine atom content of more than 15% by mass in terms of a mass content ratio of elements constituting the polymer electrolyte.
  • the metal fine particles 13A included in the polymer electrolyte membrane 12 according to an embodiment of the present invention will be described.
  • the metal fine particles 13A have a function of deactivating peroxides generated during battery operation or radicals generated from the peroxides, and have a concentration gradient in the film thickness direction in the polymer electrolyte membrane 12. Are distributed.
  • “having a concentration gradient in the film thickness direction” means that the metal fine particles 13A are not uniformly dispersed in the polymer electrolyte membrane 12, but at a certain position when viewed in the film thickness direction. This indicates that the existence of the metal fine particles 13A is biased such that the concentration of the metal fine particles 13A is small and the concentration of the metal fine particles 13A is high at a certain position.
  • the metal fine particles 13A are dispersed with a concentration gradient, where the concentration of the metal fine particles 13A shows the maximum value, the effective concentration becomes higher than that of the uniform dispersion, and the radicals are effectively lost. It becomes easy to make it live.
  • the proximity effect that the activity with respect to a radical becomes high can be expected because the metal fine particles 13A are densely packed.
  • the “maximum value” means that when the function shown for the concentration change of the metal fine particles in the film thickness direction in the polymer electrolyte membrane changes from increase to decrease at a position in the film thickness direction, It is the value at.
  • the concentration of the metal fine particles 13 ⁇ / b> A may have a maximum value inside the membrane rather than the membrane surface of the polymer electrolyte membrane 12. Further, it is preferable that the maximum value of the concentration of the metal fine particles 13A is on the cathode catalyst layer side with respect to the center in the film thickness direction of the polymer electrolyte membrane. For example, the maximum value is preferably in the vicinity of the surface in contact with the cathode catalyst layer in the polymer electrolyte membrane.
  • Such a material for forming the metal fine particles 13A includes one or more metals selected from the group consisting of noble metals and noble metal alloys.
  • the forming material preferably contains at least one kind of noble metal or noble metal alloy selected from the group of noble metals consisting of platinum, gold, palladium, iridium, rhodium and ruthenium, or both, gold, palladium, ruthenium, And at least one metal selected from the noble metal group consisting of rhodium is more preferable, and palladium is particularly preferable.
  • metal fine particle 13A it is good also considering 2 or more types of metals chosen from the said group as a forming material.
  • the metal fine particles 13A may be a mixture of metal fine particles 13A made of a single metal, or may be an alloy of a plurality of types of metals.
  • the particle diameter of the metal fine particles 13A is preferably 500 nm or less. More preferably, it is 100 nm or less, More preferably, it is 50 nm or less.
  • the lower limit is not particularly limited. It may be present in the film in a metal state, and a part may be present in an ionic state. In the electron micrograph shown in FIG. 2, the metal fine particles 13 ⁇ / b> A appear as black spots, but there may be fine particles having a size that does not appear at the imaged magnification at locations where there are no black spots. .
  • the total amount of Pd metal present on and in the electrolyte membrane surface is preferably 5% or more and 95% or less with respect to the total amount of Pd metal and Pd ions present on and inside the electrolyte membrane.
  • they are 5% or more and 80% or less, More preferably, they are 5% or more and 65% or less, More preferably, they are 5% or more and 50% or less.
  • the base material 12X of the polymer electrolyte membrane 12 is manufactured using the polymer electrolyte as described above.
  • a method for producing the polymer electrolyte membrane various generally known methods can be adopted, but in the present embodiment, the following description will be made assuming that the following cast film forming method is adopted.
  • the base material 12X that can be used in the membrane electrode assembly according to an embodiment of the present invention is preferably manufactured by a cast film forming method including the following steps (i) to (iv).
  • a step of preparing a polymer electrolyte solution by dissolving the polymer electrolyte as described above in an organic solvent capable of dissolving the polymer electrolyte (Ii) The polymer electrolyte solution obtained in (i) above is cast-coated on a support substrate having a relatively smooth surface, and a polymer electrolyte cast film is formed on the support substrate.
  • a polymer electrolyte solution is prepared.
  • an organic solvent capable of dissolving the polymer electrolyte to be used is selected.
  • an organic solvent capable of dissolving these other components is preferable.
  • the organic solvent is a solvent that can dissolve the polymer electrolyte to be used, and specifically means an organic solvent that can dissolve the polymer electrolyte at a concentration of 1% by weight or more at 25 ° C.
  • an organic solvent capable of dissolving the polymer electrolyte at a concentration of 5 to 50% by weight is used.
  • the organic solvent needs to be volatile enough to be removed by heat treatment after forming a cast film of a polymer electrolyte on the support base material in the next step (ii).
  • the polymer electrolyte membrane is formed by removing the organic solvent from the cast film in the step (iii) described later.
  • the formed polymer electrolyte membrane may have uneven appearance. This is because in an organic solvent having a boiling point of 150 ° C. or lower, the organic solvent suddenly volatilizes from the cast film. Therefore, the organic solvent preferably contains at least one organic solvent having a boiling point of 150 ° C. or higher at 101.3 kPa (1 atm).
  • organic solvents suitable for the preparation of the polymer electrolyte solution include dimethylformamide (DMF), dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), and ⁇ -butyrolactone (GBL).
  • DMF dimethylformamide
  • DMAc dimethylacetamide
  • NMP N-methyl-2-pyrrolidone
  • DMSO dimethyl sulfoxide
  • GBL ⁇ -butyrolactone
  • Aprotic polar solvents such as; or chlorinated solvents such as dichloromethane, chloroform, 1,2-dichloroethane, chlorobenzene and dichlorobenzene; alcohols such as methanol, ethanol and propanol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether; An alkylene glycol monoalkyl ether such as propylene glycol monomethyl ether or propylene glycol monoethyl ether is preferably used.
  • chlorinated solvents such as dichloromethane, chloroform, 1,2-dichloroethane, chlorobenzene and dichlorobenzene
  • alcohols such as methanol, ethanol and propanol
  • ethylene glycol monomethyl ether ethylene glycol monoethyl ether
  • An alkylene glycol monoalkyl ether such as propylene glycol monomethyl ether or propylene glycol monoethyl ether is preferably used.
  • an organic solvent containing an aprotic polar solvent is preferable, and an organic solvent substantially consisting of an aprotic polar solvent is particularly preferable.
  • an organic solvent substantially composed of an aprotic polar solvent means an organic solvent mainly composed of a protic polar solvent, but does not exclude the presence of unintentionally contained water or the like. .
  • the aprotic polar solvent has an advantage that the affinity for the supporting substrate is relatively small and the aprotic polar solvent is hardly absorbed by the supporting substrate.
  • the block copolymer which is the preferred polymer electrolyte described above
  • aprotic polar solvents DMSO, DMF, DMAc, NMP, GBL or two or more selected from these are used.
  • the mixed solvent is preferable.
  • FIG. 3A is an explanatory diagram showing step (ii).
  • This step is a step of casting the polymer electrolyte solution 12S obtained in the step (i) on the support substrate P to form a casting film 12A.
  • the casting coating method various means such as a roller coating method, a spray coating method, a curtain coating method, a slot coating method, or a screen printing method can be used.
  • the polymer electrolyte solution 12S is discharged from the die 100 to form the casting film 12A.
  • the casting film 12A formed on the support substrate P has a film shape because a part of the organic solvent in the polymer electrolyte solution 12S is volatilized at the time of coating.
  • the thickness of the casting film 12A is preferably 3 ⁇ m to 50 ⁇ m.
  • the polymer electrolyte concentration of the polymer electrolyte solution 12S to be used, the coating amount of the coating apparatus, and the like may be appropriately adjusted.
  • the said support base material P is a base material which drive
  • support base material P used at a process (ii) it has sufficient endurance to polymer electrolyte solution 12S used for cast coating, and also with respect to processing conditions in process (iii) mentioned below.
  • a substrate made of a durable material is selected.
  • “durability” means that the support substrate P itself is not substantially dissolved by the polymer electrolyte solution 12S, and that the support substrate P itself swells and contracts due to the processing conditions of step (iii). This means that it does not occur and has good dimensional stability.
  • Examples of such a supporting substrate P include glass plates; metal foils such as SUS foil and copper foil; plastic films such as polyethylene terephthalate (PET) films and polyethylene naphthalate (PEN) films. Further, this plastic film may be subjected to surface treatment such as UV treatment, mold release treatment, embossing treatment, etc. on the film surface within a range that does not significantly impair the durability as described above. In the following description, it is assumed that the support substrate P is a plastic film.
  • FIG. 3B is an explanatory diagram showing step (iii).
  • This step is a step of removing the organic solvent S contained in the casting film 12A formed on the support substrate P in the step (ii) and forming the base material 12X on the support substrate P.
  • drying or washing with a washing solvent is recommended.
  • FIG. 3B illustrates that the organic solvent S is dried and removed by evaporation. It is even more preferable to remove the organic solvent by combining such drying and washing.
  • drying and washing first, drying is performed, and the film formed on the support substrate P It is particularly preferable to carry out washing with a washing solvent after most of the organic solvent S contained in is removed.
  • the drying and washing which are suitable methods as the step (iii), are performed in this order.
  • treatment such as heating, decompression, and ventilation can be employed.
  • the heat treatment is preferable in that it is good and the operation is easy.
  • the support base P hereinafter referred to as “first laminated film” in some cases
  • first laminated film on which the casting film 12A is formed is heat-treated by direct heating, hot air treatment or the like.
  • Hot air treatment is particularly preferable in that the polymer electrolyte in the casting membrane 12A is not significantly impaired.
  • the first laminated film may be passed through a drying furnace.
  • the drying furnace is configured to apply hot air whose temperature is set in a range of 40 ° C. to 150 ° C., preferably in a range of 50 ° C. to 140 ° C., in a direction perpendicular to the passing direction of the first laminated film and / or in a facing direction. Blow along.
  • the second laminated film in which the volatile component such as the organic solvent S is dried (evaporated) from the casting film 12A on the support base P and the base material 12X is formed on the support base P.
  • the base material 12X of the second laminated film thus obtained still contains a slight amount of organic solvent, this organic solvent is washed with a washing solvent. By cleaning with a cleaning solvent, it is easy to obtain the base material 12X having excellent appearance and the like.
  • a mixed solvent consisting of DMSO, DMF, DMAc, NMP, GBL, or a combination thereof, which is a suitable organic solvent in the preparation of the polymer electrolyte solution
  • pure water particularly ultrapure water, is used as the cleaning solvent. It is preferable to do.
  • the second laminated film formed continuously through the drying furnace is filled with, for example, a cleaning solvent. It can wash
  • FIG. 3C is an explanatory diagram showing step (iv).
  • the base material 12X of the polymer electrolyte membrane 12 is obtained by removing the supporting substrate P from the second laminated film formed in step (iii) by peeling or the like. Since the obtained base material 12X is obtained by a suitable cast film forming method, it is substantially non-porous.
  • substantially non-porous means that minute through holes such as voids are not formed in the polymer electrolyte membrane 12.
  • the polymer electrolyte membrane 12 may be a membrane having such a void as long as it is a small amount of voids or a small diameter void that does not hinder the operation of the fuel cell.
  • the case where the support substrate P is continuously running has been described, but of course, using the single wafer support substrate P Also, the polymer electrolyte membrane 12 can be obtained.
  • the polymer electrolyte solution coated on the single-wafer supporting substrate P can be removed from the organic solvent by storing it in an appropriate drying furnace, and thus obtained.
  • the second laminated film as a single wafer can be cleaned by immersing it in a cleaning tank equipped with a cleaning solvent.
  • the second laminated film may be removed by removing the cleaning solvent remaining or adhering after the support substrate P is removed, or the second laminated film after washing may be heated as it is. Then, after the remaining or attached cleaning solvent is removed by drying, the supporting substrate P may be removed.
  • the polymer electrolyte membrane 12 and the membrane electrode assembly 20 are manufactured using the base material 12X.
  • the metal layer 13 is formed on one surface of the base material 12X.
  • the metal layer 13 can be formed by physically depositing the metal fine particle forming material on the surface of the base material 12X.
  • physical vapor deposition generally known methods such as vapor deposition, sputtering, and ion plating can be used.
  • the ion plating method is preferable.
  • the palladium particles SP are illustrated as being stacked by an ion plating method using palladium as a target metal.
  • the metal layer 13 having a film-like form is adopted, but it may not be a film-like form.
  • the “metal layer” includes the metal fine particle layer in addition to the layer having a film form.
  • the metal fine particle layer can be formed by applying and solidifying a dispersion obtained by mixing fine particles of the above-described forming material and a resin precursor or a resin solution onto the surface of the base material 12X. Fine particles having an average particle diameter of several nm to several tens of nm can be used, and the fine particles may be aggregated during coating. Moreover, as a precursor, the precursor of a photocurable resin or a thermosetting resin can be used. As the coating method, known techniques such as a spray method and a die coating method can be used.
  • the metal layer formed by these coating methods has a structure in which metal fine particles are finely dispersed on the electrolyte membrane surface.
  • a metal fine particle layer unlike the film-like metal layer formed by the physical vapor deposition described above, a gap is formed between the metal fine particles, and therefore the polymer electrolyte membrane and the catalyst layer are interposed through the gap. The exchange of ions between them is easy. Therefore, such a metal fine particle layer can maintain power generation performance.
  • the solvent of the dispersion is selected based on the solubility of the polymer electrolyte forming the base material 12X.
  • the dispersion is a poor solvent for the polymer electrolyte constituting the base material 12X.
  • the solvent is a mixed solvent
  • at least one kind of solvent that is a poor solvent is used for the polymer electrolyte that forms the base material 12X, and the physical properties are adjusted so as to be a poor solvent.
  • the poor solvent for the polymer electrolyte refers to a solvent that cannot dissolve the polymer electrolyte at a concentration of 0.1% by mass or more at 25 ° C.
  • a good solvent for a polymer electrolyte refers to a solvent that can dissolve the polymer electrolyte at a concentration of 0.1% by mass or more at 25 ° C. Specifically, by dissolving a predetermined amount of polymer electrolyte in a predetermined amount of 25 ° C. solvent to prepare a solution, drying the solution and measuring the dry mass, the polymer electrolyte with respect to the solvent Measure the solubility of.
  • the solvent of the dispersion can be appropriately selected by measuring the solubility according to the type of polymer electrolyte and deterioration inhibitor used.
  • the above-described forming material is used as a target, and the energy of ionized gas that collides with the target is controlled, thereby controlling the particle diameter of the sputtered particles.
  • a metal fine particle layer in which particles are spread in layers can be formed.
  • the metal layer formed by the physical vapor deposition method has excellent adhesion to the electrolyte membrane surface, and can suppress the decrease in the transport amount of hydrogen ions at the interface between the electrolyte membrane and the catalyst layer. Can be maintained.
  • the base material 12X on which the metal layer 13 is formed is sandwiched between the electrodes 50 and 51, and forced energization is performed in the same direction as energization during power generation from the external power source 52.
  • the metal layer 13 is ionized and disappears, and the ionized metal penetrates into the base material 12X.
  • the metal ions dissolved from the metal layer 13 precipitate as metal fine particles 13A while the metals aggregate together in the base material 12X.
  • the metal layer 13 is formed using two or more kinds of forming materials, it may be precipitated as an alloy.
  • FIG. 4C schematically shows a state in which a large amount of the metal fine particles 13A are deposited in the width W, and the concentration is higher than that of other portions. Further, it is shown that the high concentration portion is on the side where the original metal layer 13 was present (above the base material 12X) rather than the center in the thickness direction of the base material 12X.
  • the polymer electrolyte membrane 12 which is one embodiment of this invention is manufactured.
  • platinum or a platinum-based alloy supported on carbon is mixed with a solvent of a perfluoroalkylsulfonic acid resin to form a paste (hereinafter sometimes referred to as catalyst ink 14S).
  • the anode catalyst layer 14a is obtained by applying and drying one surface of the polymer electrolyte membrane 12.
  • the cathode catalyst layer 14b is formed by applying and drying the catalyst ink 14S on the other surface of the polymer electrolyte membrane 12, and the membrane electrode assembly 20 which is one embodiment of the present invention is manufactured.
  • a metal fine particle dispersion in which metal fine particles are added and dispersed in the polymer electrolyte solution is prepared, and these solutions are prepared. And a method of forming using the dispersion.
  • the casting membrane 12A is formed on the support substrate P by discharging the polymer electrolyte solution 12S from the die 100. This step is the same as that in FIG. 3A described above.
  • a casting film 19A is formed on the casting film 12A by discharging a metal fine particle dispersion 19S containing separately prepared metallic fine particles 13A.
  • the metal fine particle dispersion 19S is discharged onto the casting film 12A, the surface of the casting film 12A is swollen by the solvent contained in the metal fine particle dispersion 19S, and the interface between the casting film 12A and the casting film 19A is unclear. become.
  • the metal fine particles 13A in the metal fine particle dispersion 19S are difficult to be dispersed in the casting film 12A obtained by evaporating a part of the solvent in advance, the metal fine particles 13A are localized in the casting film 19A. Cheap.
  • the organic solvent S contained in the casting membrane 12A and the casting membrane 19A is removed, and the polymer electrolyte membrane 12 is formed on the support substrate P.
  • the interface between the casting film 12A and the casting film 19A becomes unclear and is formed as an integral polymer electrolyte membrane 12.
  • the casting film 12A or the casting film 19A can be further laminated on the casting film 19A formed in FIG. 5B.
  • the order of stacking the manufacturing steps described above may be reversed. That is, first, the casting film 19A is formed on the support substrate P, and then the casting film 12A is laminated on the casting film 19A to remove the solvent, thereby forming the polymer electrolyte membrane 12. Good.
  • the polymer electrolyte membrane 12 and the membrane electrode assembly 20 may be manufactured using a method as shown in FIGS. 6A to 6C.
  • an anode catalyst layer 14a laminated and integrated with the gas diffusion layer 16a is obtained by applying and drying the catalyst ink 14S on the surface of the gas diffusion layer 16a.
  • a cathode catalyst layer laminated and integrated with the gas diffusion layer is also formed.
  • the base material 12X on which the metal layer 13 is formed is sandwiched and joined between the obtained anode catalyst layer 14a and cathode catalyst layer 14b by the same method as in FIG. 4A described above.
  • a known method for example, a method described in J. Electrochem. Soc .: Electrochemical Science Science Technology, 1988, 135 (9), 2209
  • a membrane electrode assembly for a fuel cell can be obtained by applying the catalyst ink 14S to the polymer electrolyte membrane 12 and drying it to form a catalyst layer directly on the surface of the membrane.
  • separators 18a and 18b are provided outside the gas diffusion layers 16a and 16b to form a fuel cell, and then hydrogen is supplied to the anode catalyst layer 14a and oxygen is supplied to the cathode catalyst layer 14b. Power is supplied to generate power, and initial acclimation operation is performed until the battery voltage called aging is saturated. Usually, after assembly of the fuel cell, aging is performed because power generation tends to become unstable because the proton conduction path is not sufficiently formed. Here, by energizing in this aging, the metal layer 13 is ionized and deposited as metal fine particles 13A in the base material 12X.
  • the polymer electrolyte membrane 12 and the membrane electrode assembly 20 which are one embodiment of the present invention can be produced as described above.
  • the membrane electrode assembly having the above-described configuration, it is possible to obtain a membrane electrode assembly with high durability by achieving long-term stability of the polymer electrolyte.
  • radicals in the polymer electrolyte membrane can be effectively deactivated, and long-term stabilization can be achieved.
  • the metal layer 13 is formed on one surface of the base material 12X.
  • the metal layer 13 may be formed on either one of the surfaces.
  • a polymer film obtained by forming a polymer to be measured by a cast film forming method was obtained, and the obtained polymer film was cut to an appropriate weight.
  • the dry weight of the cut polymer film was measured using a halogen moisture meter set at a heating temperature of 110 ° C.
  • the polymer membrane thus dried was immersed in 5 mL of a 0.1 mol / L sodium hydroxide aqueous solution, and further 50 mL of ion exchange water was added and left for 2 hours.
  • titration was performed by gradually adding 0.1 mol / L hydrochloric acid to the solution in which the polymer film was immersed, and the neutralization point was determined.
  • the ion exchange capacity (unit: meq / g) of the polymer was calculated from the dry weight of the cut polymer film and the amount of hydrochloric acid required for neutralization.
  • Example 1 [Synthesis of Polymer Electrolyte 1] 2,2.4 g of 2,2-dimethylpropanol was dissolved in 72.5 g of pyridine. To this, 50 g of 2,5-dichlorobenzenesulfonic acid chloride was added at 0 ° C., and the mixture was stirred at room temperature for 1 hour to be reacted. To the reaction mixture, 300 mL of toluene and 250 mL of 2 mol% hydrochloric acid were added, stirred for 30 minutes, and allowed to stand to separate the organic layer.
  • the separated organic layer was washed sequentially with 150 mL of water, 150 mL of 10 wt% aqueous potassium carbonate solution and 150 mL of water, and then the solvent was distilled off under reduced pressure to obtain 105 g of a concentrated solution.
  • the concentrate was cooled to 0 ° C., and the precipitated solid was separated by filtration.
  • the separated solid was dried to obtain 49.3 g (yield: 81.4%) of a white solid of 2,5-dichlorobenzenesulfonic acid (2,2-dimethylpropyl).
  • the obtained polymerization solution was poured into 1200 g of hot water at 70 ° C., and the resulting precipitate was collected by filtration. Water was added to the precipitate so that the total amount of the precipitate and water was 696 g, and further 9.2 g of a 35 wt% sodium nitrite aqueous solution was added. To this slurry solution, 160 g of 69% by weight nitric acid was added dropwise, and then stirred at room temperature for 1 hour.
  • the slurry solution was filtered and the collected crude polymer was washed with water until the pH of the filtrate exceeded 1.
  • water is added to a flask equipped with a condenser until the total weight of the crude polymer and the crude polymer and water reaches 698 g, and a 5% by weight lithium hydroxide aqueous solution is added to the slurry solution of the crude polymer and water.
  • a 5% by weight lithium hydroxide aqueous solution is added to the slurry solution of the crude polymer and water.
  • the crude polymer was collected by filtration, washed by immersion using 200 g of water and then 250 g of methanol, and dried to obtain the following formula (2).
  • the target polymer electrolyte 1 containing the segment shown by these was obtained.
  • the yield was 14.7g.
  • 1 H-NMR spectrum was measured, and it was confirmed that the 2,2-dimethylpropoxysulfonyl group was quantitatively converted to a sulfo group.
  • Mw 455000
  • Mn 195000
  • IEC ion exchange capacity
  • polymer electrolyte membrane 1A Preparation of polymer electrolyte membrane 1A
  • the polymer electrolyte 1 obtained as described above was dissolved in N, N-dimethyl sulfoxide to prepare a polymer electrolyte solution having a concentration of 10% by weight.
  • the obtained polymer electrolyte solution was continuously cast and applied to a polyethylene terephthalate (PET) film (Toyobo Co., Ltd., E5000 grade, thickness 100 ⁇ m) having a width of 300 mm as a supporting substrate using a slot die.
  • PET polyethylene terephthalate
  • Toyobo Co., Ltd., E5000 grade, thickness 100 ⁇ m having a width of 300 mm as a supporting substrate using a slot die.
  • a cast film was formed.
  • the support substrate and the cast film were continuously conveyed to a hot air heater drying furnace, and the solvent was removed to form a film.
  • the obtained membrane was immersed in 2N sulfuric acid for 2 hours, then washed with ion-exchanged water, further air-dried, and then peeled off from the supporting base material to produce a polymer electrolyte membrane 1A.
  • the film thickness of the polymer electrolyte membrane 1A was 20 ⁇ m.
  • the amount of laminated Pd was measured using the following inductively coupled plasma optical emission spectrometer (ICP emission). As a result of the measurement, the amount of Pd laminated as the Pd layer was 0.18% (1800 ppm) with respect to the weight of the polymer electrolyte membrane.
  • ICP luminescence measuring device SII Nanotechnology, SPS3000 Measurement wavelength: 340.46 nm
  • the catalyst ink was applied to a 3 cm ⁇ 3 cm region in the center of the surface not having the Pd layer by a spray method. At this time, the distance from the discharge port to the film was set to 6 cm, and the stage temperature was set to 75 ° C. After overcoating in the same manner, the solvent was removed to form an anode catalyst layer. As an anode catalyst layer, 14.2 mg of solid content (platinum weight: 0.6 mg / cm 2 ) was applied. Subsequently, a catalyst ink was similarly applied on the Pd layer to form a cathode catalyst layer, thereby obtaining a membrane electrode assembly 1B. As the cathode catalyst layer, 14.2 mg of solid content (platinum weight: 0.6 mg / cm 2 ) was applied.
  • a carbon cloth as a gas diffusion layer and a carbon separator in which a gas passage groove is cut are disposed on both outer sides of the membrane electrode assembly 1B obtained as described above, and a current collector is further disposed on the outer side thereof.
  • a fuel cell having an effective electrode area of 9 cm 2 was assembled by sequentially arranging the end plates and fastening them with bolts.
  • a known material can be used as the conductive material as the current collector used in the present invention, but the porous carbon woven fabric, carbon non-woven fabric or carbon paper efficiently transports the source gas to the catalyst. Therefore, it is preferable.
  • FIG. 7 to 9 are TEM observation images obtained, FIG. 7 is near the interface between the anode catalyst layer and the polymer electrolyte membrane, FIG. 8 is near the center of the polymer electrolyte membrane, and FIG. 9 is the cathode. It is a TEM photograph which shows the mode of the interface vicinity of a catalyst layer and a polymer electrolyte membrane. In addition, the TEM observation magnification of FIG. 9 is 10,000 times, and the TEM observation magnification of FIGS. 7 and 8 is 50,000 times.
  • the particle diameter of the Pd particles precipitated in the film was confirmed visually from a TEM observation image.
  • Pd particles near the interface between the cathode catalyst layer and the polymer electrolyte membrane were about 10 nm to about 50 nm.
  • the Pd particle size in the vicinity of the interface between the anode catalyst layer and the polymer electrolyte membrane and in the vicinity of the center of the polymer electrolyte membrane was about 10 nm or less.
  • ICP emission inductively coupled plasma emission spectrometer
  • the treated solution was made up to a volume of 5 mL, and the solution was measured using an inductively coupled plasma emission spectrometer (ICP emission).
  • ICP luminescence measuring device SII Nanotechnology, SPS3000 Measurement wavelength: 340.46 nm
  • the anode / cathode catalyst layer and the anode catalyst layer are removed by removing the membrane electrode assembly from the fuel cell that has been subjected to durability evaluation, and placing it in a mixed solution of ethanol / water (ethanol content: 90% by mass) and subjecting it to ultrasonic treatment. Removed. Next, 4 mg of the polymer electrolyte membrane before and after the test was immersed in 10 ⁇ L of a 25 mass% tetramethylammonium hydroxide methanol solution and reacted at 100 ° C. for 2 hours. After standing to cool, the weight average molecular weight of the obtained reaction solution was measured using gel permeation chromatography (GPC).
  • GPC gel permeation chromatography
  • the concentrated residue was purified by silica gel chromatography (developing solvent: chloroform). From the obtained eluate, the solvent was distilled off under reduced pressure. The residue was dissolved in 500 mL of toluene at 70 ° C., and then cooled to room temperature. The precipitated solid was separated by filtration, and the separated solid was dried to obtain 31.2 g of a white solid of 4,4′-dichlorobiphenyl-2,2′-disulfonic acid di (2,2-dimethylpropyl). It was.
  • the bath temperature was raised to 160 ° C., and the mixture was kept warm for 14 hours.
  • the reaction solution was added to a mixed solution of 1000 g of methanol and 200 g of 35 wt% hydrochloric acid, and the deposited precipitate was filtered, washed with ion-exchanged water until neutral, and dried. 27.2 g of the obtained crude product was dissolved in 97 g of N, N-dimethylacetamide, insoluble matters were filtered, and then added to a mixed solution of 1100 g of methanol and 100 g of 35 wt% hydrochloric acid.
  • the obtained polymerization solution was put into 3360 g of 13 wt% hydrochloric acid and stirred at room temperature for 30 minutes.
  • the resulting precipitate was filtered, 3360 g of 13 wt% hydrochloric acid was added, and the mixture was stirred at room temperature for 30 minutes. Thereafter, the precipitate was filtered and washed with ion exchange water until the pH of the filtrate exceeded 4.
  • 840 g of ion exchanged water and 790 g of methanol were added, and the mixture was heated and stirred at a bath temperature of 90 ° C. for 1 hour.
  • the target polymer electrolyte 2 containing the segment shown by these was obtained.
  • the yield was 17.25g. Mw: 5.78 ⁇ 10 5
  • polymer electrolyte membrane 2A The polymer electrolyte 2 obtained as described above was dissolved in N-methyl 2-pyrrolidone to prepare a polymer electrolyte solution having a concentration of 7.5% by weight. The obtained polymer electrolyte solution was continuously cast and applied to a polyethylene terephthalate (PET) film (Toyobo Co., Ltd., E5000 grade, thickness 100 ⁇ m) having a width of 300 mm as a supporting substrate using a slot die. Thus, a cast film was formed. Thereafter, the support substrate and the cast film were continuously conveyed to a hot air heater drying furnace, and the solvent was removed to form a film.
  • PET polyethylene terephthalate
  • the obtained membrane was immersed in 2N sulfuric acid for 2 hours, then washed with ion-exchanged water, further air-dried, and then peeled off from the support base material to produce a polymer electrolyte membrane 2A.
  • the film thickness of the polymer electrolyte membrane 2A was 10 ⁇ m.
  • a catalyst layer (anode catalyst layer, cathode catalyst layer) is formed on both surfaces to form a membrane electrode assembly 2B.
  • Example 2B Further, a fuel cell was assembled and durability was evaluated in the same manner as in Example 1 except that the membrane electrode assembly 2B was used. In the durability evaluation, the fuel cell was continuously operated for 500 hours. Thereafter, the membrane electrode assembly was taken out from the fuel cell, and the weight average molecular weight of the polymer electrolyte membrane 2A was measured.
  • Example 3 [Synthesis of polymer electrolyte 3] Under an argon atmosphere, 7.69 g (35.2 mmol) of anhydrous nickel bromide, 5.49 g (35.2 mmol) of 2,2′-bipyridyl and 460 g of N-methylpyrrolidone were added to the flask. A containing solution was prepared. In a separate flask, 17.2 g (263.8 mmol) of zinc powder and 4,4′-dichlorobiphenyl-2,2′-disulfonic acid di (2) synthesized by the method described in Example 1 of JP-A-2007-270118 were used.
  • the block copolymer which has a segment which does not have an ion exchange group substantially, and was shown as the polymer electrolyte 3.
  • Mn 1.73 ⁇ 10 5
  • Mw 3.46 ⁇ 10 5
  • polymer electrolyte membrane 3A Preparation of polymer electrolyte membrane 3A
  • the polymer electrolyte 3 was dissolved in N, N-dimethyl sulfoxide to prepare a polymer electrolyte solution having a concentration of 10% by weight.
  • a polymer electrolyte membrane 3A was produced in the same manner as in Example 1 except that this polymer electrolyte solution was used.
  • the thickness of the polymer electrolyte membrane 3A was 20 ⁇ m.
  • a carbon cloth, a carbon separator, a current collector and an end plate are arranged in this order on both outer sides of the membrane electrode assembly 3B obtained as described above in the same manner as in Example 1, and these are tightened with bolts.
  • a fuel cell having an effective electrode area of 25 cm 2 was assembled.
  • the membrane / electrode assembly was taken out of the fuel cell after the OCV test, and the molecular weight of the polymer electrolyte membrane after durability evaluation was measured in the same manner as in Example 1.
  • Example 1 and Comparative Example 1 the weight average molecular weight maintenance rates from the initial state of the polymer electrolyte 1 are summarized in Table 4 below.
  • Example 2 and Comparative Example 2 the weight average molecular weight maintenance rates from the initial state of the polymer electrolyte 2 are shown together in Table 5 below.
  • Example 3 and Comparative Example 3 the weight average molecular weight maintenance ratio from the initial state of the polymer electrolyte 3 is shown together in Table 6 below.
  • the evaluation results indicate that the higher the molecular weight maintenance rate before and after the load fluctuation test, the less the deterioration of the polymer electrolyte membrane and the better the long-term stability.
  • the ratio of “the amount of Pd ions present in the film after durability evaluation” to “the total amount of Pd present in the film after durability evaluation” Table 7 summarizes the ratio of “the amount of Pd metal present in the film after durability evaluation” to “the total amount of Pd present in the film after durability evaluation”.
  • Pd metal indicates that Pd is not ionized and is dispersed as fine particles in the polymer electrolyte membrane.
  • the membrane / electrode assembly of the present invention was less deteriorated and stable than the membrane / electrode assembly of the comparative example in continuous power generation (that is, continuous oxidation-reduction reaction). .
  • the durability evaluation it was confirmed that Pd formed as a Pd layer on the surface of the polymer electrolyte membrane was present in the polymer electrolyte membrane in an ion or metal state. It was. Further, no Pd layer remained on the surface of the polymer electrolyte membrane. This confirmed the usefulness of the present invention.
  • the membrane / electrode assembly including the polymer electrolyte membrane is excellent in long-term stability and is suitably used for a fuel cell.

Abstract

A polymer electrolyte membrane which comprises: a membrane-like base material that is formed of a polymer electrolyte; and metal fine particles that are dispersed in the base material. The material which forms the metal fine particles contains one or more metals that are selected from the group consisting of noble metals and noble metal alloys, and the metal fine particles are dispersed so as to have a concentration gradient in the thickness direction of the base material.

Description

高分子電解質膜、膜電極接合体、燃料電池Polymer electrolyte membrane, membrane electrode assembly, fuel cell
本発明は、高分子電解質膜、膜電極接合体、燃料電池に関するものである。
本願は、２０１１年１月１７日に、日本に出願された特願２０１１－００７１３０号に基づき優先権を主張し、その内容をここに援用する。 The present invention relates to a polymer electrolyte membrane, a membrane electrode assembly, and a fuel cell.
This application claims priority based on Japanese Patent Application No. 2011-007130 filed in Japan on January 17, 2011, the contents of which are incorporated herein by reference.
近年、一次電池、二次電池、あるいは固体高分子形燃料電池（以下、場合により「燃料電池」という）の開発が数多く検討されている。 In recent years, many developments of primary batteries, secondary batteries, or polymer electrolyte fuel cells (hereinafter sometimes referred to as “fuel cells”) have been studied.
燃料電池は、膜電極接合体（以下、「ＭＥＡ」と称することがある）の両面に発電燃料となるガスを供給するためのガス拡散層を有するセル（燃料電池セル）を基本構成としている。ここで、膜電極接合体とは、イオン伝導性を有する高分子（以下、高分子電解質）を含む高分子電解質膜の両面に、発電燃料である水素と酸素の酸化還元反応を促進する触媒を含む触媒層と呼ばれる電極を形成したものである。 A fuel cell has a basic configuration of a cell (fuel cell) having a gas diffusion layer for supplying gas serving as power generation fuel to both surfaces of a membrane electrode assembly (hereinafter also referred to as “MEA”). Here, the membrane electrode assembly is a catalyst that promotes a redox reaction between hydrogen and oxygen as power generation fuel on both sides of a polymer electrolyte membrane containing a polymer having ion conductivity (hereinafter referred to as a polymer electrolyte). An electrode called a catalyst layer is formed.
膜電極接合体に用いられる高分子電解質膜としては、現在、主としてフッ素系高分子電解質が検討されており（例えば、特許文献１参照）、このようなフッ素系高分子電解質としては、例えば、ナフィオン（デュポン社の登録商標）が知られている。また、フッ素系高分子電解質は非常に高価であり、高い信頼性が求められる燃料電池に適用するには耐熱性や膜強度が低いことが知られている。そのため、フッ素系高分子電解質に代替する材料として、炭化水素系の高分子電解質についても検討が成されている（例えば、特許文献２，３参照）。 Currently, fluorine-based polymer electrolytes are mainly studied as polymer electrolyte membranes used in membrane electrode assemblies (see, for example, Patent Document 1), and examples of such fluorine-based polymer electrolytes include Nafion. (A registered trademark of DuPont) is known. Further, it is known that a fluorine-based polymer electrolyte is very expensive and has low heat resistance and membrane strength when applied to a fuel cell that requires high reliability. For this reason, studies have been made on hydrocarbon polymer electrolytes as materials that can be substituted for fluorine polymer electrolytes (see, for example, Patent Documents 2 and 3).
特開２００３－１１３１３６号公報JP 2003-113136 A 特開２００３－３１２３２号公報JP 2003-31232 A 特開２００７－１７７１９７号公報JP 2007-177197 A
しかしながら、上記特許文献に示された高分子電解質膜は、長期運転を行った場合の運転安定性（以下、「長期安定性」と呼ぶ）が低いことが指摘されている。この長期安定性を妨げる要因としては、様々の原因が推定されている。その１つとして、電池稼動時に発生する過酸化物（例えば、過酸化水素等）またはこの過酸化物から発生するラジカルによる膜の劣化が指摘されている。具体的には、膜の劣化は、フッ素系高分子電解質膜であれば、排水中に含まれるフッ素イオンの溶出量、炭化水素系高分子電解質膜であれば、高分子電解質の分子量の低下として観察されることがある。 However, it has been pointed out that the polymer electrolyte membranes disclosed in the above-mentioned patent documents have low operational stability (hereinafter referred to as “long-term stability”) when long-term operation is performed. Various factors have been estimated as factors that hinder this long-term stability. As one of them, it is pointed out that the film is deteriorated by a peroxide (for example, hydrogen peroxide) generated during battery operation or a radical generated from the peroxide. Specifically, the deterioration of the membrane is caused by a decrease in the molecular weight of the polymer electrolyte in the case of a fluorine-based polymer electrolyte membrane and the elution amount of fluorine ions contained in waste water, and in the case of a hydrocarbon-based polymer electrolyte membrane. May be observed.
それゆえ、高分子電解質膜の過酸化物やラジカルに対する耐久性（以下、「ラジカル耐性」と呼ぶことがある）を向上させることが、固体高分子形燃料電池の長期安定性に繋がる１つの対策とされている。なお、以下の説明においては、「過酸化物から発生するラジカル」を単に「ラジカル」と称することがある。 Therefore, improving the durability of the polymer electrolyte membrane against peroxides and radicals (hereinafter sometimes referred to as “radical resistance”) is one measure that leads to the long-term stability of the polymer electrolyte fuel cell. It is said that. In the following description, “radicals generated from peroxide” may be simply referred to as “radicals”.
ラジカル耐性が不十分な高分子電解質膜を用いた燃料電池は、電池の起動・停止を繰り返すような長期運転を行なうと、高分子電解質膜が著しく劣化して、イオン伝導性が低下し、結果として燃料電池自体の発電性能が低下し易い。 When a fuel cell using a polymer electrolyte membrane with insufficient radical resistance is operated for a long time such as repeated starting and stopping of the cell, the polymer electrolyte membrane deteriorates significantly, resulting in a decrease in ionic conductivity. As a result, the power generation performance of the fuel cell itself is likely to deteriorate.
この課題に対し、高分子材料分野では、従来から、例えばヒンダードフェノール系酸化防止剤等の酸化防止剤が、加工時の溶融劣化や、経時的に生じる酸化劣化を抑制する目的で広範に用いられている。しかしながら、ラジカル耐性の向上を求めて、このような酸化防止剤を燃料電池用高分子電解質膜に用いたとしても、固体高分子形燃料電池の長期安定性の改善には不十分であった。 In response to this problem, in the polymer material field, for example, antioxidants such as hindered phenolic antioxidants have been widely used for the purpose of suppressing melting deterioration during processing and oxidation deterioration that occurs over time. It has been. However, even if such an antioxidant is used in a polymer electrolyte membrane for a fuel cell in order to improve radical resistance, it is insufficient for improving the long-term stability of the solid polymer fuel cell.
したがって、良好なラジカル耐性を有し、燃料電池の長期安定性を可能とする高分子電解質膜の実現が切望されていた。 Therefore, realization of a polymer electrolyte membrane having good radical resistance and enabling long-term stability of the fuel cell has been desired.
本発明はこのような事情に鑑みてなされたものであって、高耐久化がなされた高分子電解質膜を提供することを目的の一つとする。更には、上述の高分子電解質膜を有し、長期安定性に優れた膜電極接合体を提供すること、およびこの膜電極接合体を有し、長期安定性に優れた燃料電池を提供することをあわせて目的の一つとする。 The present invention has been made in view of such circumstances, and an object thereof is to provide a polymer electrolyte membrane having high durability. Furthermore, to provide a membrane electrode assembly having the above-described polymer electrolyte membrane and having excellent long-term stability, and to providing a fuel cell having this membrane and electrode assembly and having excellent long-term stability. Is one of the purposes.
上記の課題を解決するため、本発明の高分子電解質膜は、高分子電解質で形成された膜状の母材と、前記母材の中に分散された金属微粒子と、を有し、前記金属微粒子の形成材料が、貴金属および貴金属合金からなる群より選ばれる１種以上の金属を含み、かつ、前記金属微粒子が前記母材の厚み方向に濃度勾配を有して分散している。 In order to solve the above problems, a polymer electrolyte membrane of the present invention comprises a film-like base material formed of a polymer electrolyte, and metal fine particles dispersed in the base material, and the metal The fine particle forming material includes one or more metals selected from the group consisting of noble metals and noble metal alloys, and the metal fine particles are dispersed with a concentration gradient in the thickness direction of the base material.
本発明の一形態においては、前記金属微粒子の濃度の極大値を有することが望ましい。 In one form of this invention, it is desirable to have the maximum value of the density | concentration of the said metal microparticle.
本発明の一形態においては、前記金属微粒子の粒子径が５００ｎｍ以下であることが望ましい。 In one form of this invention, it is desirable that the metal fine particles have a particle size of 500 nm or less.
本発明の一形態においては、前記金属微粒子の形成材料が、白金、金、パラジウム、イリジウム、ロジウムおよびルテニウムからなる貴金属群より選ばれる、少なくとも１種の貴金属もしくは貴金属合金のいずれか一方、または両方を含むことが望ましい。 In one embodiment of the present invention, the metal fine particle forming material is at least one of a noble metal or a noble metal alloy selected from the group of noble metals consisting of platinum, gold, palladium, iridium, rhodium and ruthenium, or both. It is desirable to include.
本発明の一形態においては、前記高分子電解質膜が、炭化水素系高分子電解質からなることが望ましい。 In one form of this invention, it is desirable that the polymer electrolyte membrane is composed of a hydrocarbon polymer electrolyte.
本発明の一形態においては、前記炭化水素系高分子電解質が、イオン交換基を有するブロックと、イオン交換基を実質的に有しないブロックと、を備えたブロック共重合体を含むことが望ましい。 In one aspect of the present invention, it is desirable that the hydrocarbon-based polymer electrolyte includes a block copolymer including a block having an ion exchange group and a block having substantially no ion exchange group.
本発明の一形態においては、前記高分子電解質で形成された膜状の母材の表面に、金属層を積層させ、前記母材と前記金属層との両面から電圧を印加することで前記母材の内部に析出させた前記金属微粒子を含むことが望ましい。 In one embodiment of the present invention, a metal layer is laminated on the surface of the film-shaped base material formed of the polymer electrolyte, and a voltage is applied from both sides of the base material and the metal layer to apply the base. It is desirable to include the metal fine particles deposited inside the material.
本発明の一形態においては、前記金属層が、物理蒸着法によって形成されることが望ましい。 In one form of this invention, it is desirable that the metal layer is formed by physical vapor deposition.
本発明の一形態においては、前記金属層が、金属微粒子を含有する液を前記高分子電解質膜の表面に塗工して形成されることが望ましい。 In one embodiment of the present invention, the metal layer is preferably formed by applying a liquid containing metal fine particles to the surface of the polymer electrolyte membrane.
本発明の膜電極接合体は、上述の高分子電解質膜と、前記高分子電解質膜を挟持するアノード触媒層およびカソード触媒層と、を有することを特徴とする。 The membrane electrode assembly of the present invention includes the above-described polymer electrolyte membrane, and an anode catalyst layer and a cathode catalyst layer that sandwich the polymer electrolyte membrane.
本発明の一形態においては、前記金属微粒子の濃度の極大値が、前記高分子電解質膜の膜厚方向の中心よりも前記カソード触媒層側にあることが望ましい。 In one embodiment of the present invention, it is desirable that the maximum value of the concentration of the metal fine particles is on the cathode catalyst layer side with respect to the center in the film thickness direction of the polymer electrolyte membrane.
本発明の燃料電池は、上述の高分子電解質膜を有することを特徴とする。 The fuel cell of the present invention has the above-described polymer electrolyte membrane.
即ち、本発明の第１の態様は、高分子電解質で形成された膜状の母材と、
前記母材の中に分散された金属微粒子と、を有し、
前記金属微粒子の形成材料が、貴金属および貴金属合金からなる群より選ばれる１種以上の金属を含み、かつ、前記金属微粒子が前記母材の厚み方向に濃度勾配を有して分散している高分子電解質膜である。 That is, the first aspect of the present invention is a film-like base material formed of a polymer electrolyte,
Metal fine particles dispersed in the base material,
The metal fine particle forming material contains one or more metals selected from the group consisting of noble metals and noble metal alloys, and the metal fine particles are dispersed with a concentration gradient in the thickness direction of the base material. It is a molecular electrolyte membrane.
本発明の第２の態様は、前記第１の態様において、前記金属微粒子の濃度が極大値を有する高分子電解質膜である。 A second aspect of the present invention is the polymer electrolyte membrane according to the first aspect, wherein the concentration of the metal fine particles has a maximum value.
本発明の第３の態様は、前記第１または２の態様において、前記金属微粒子の粒子径が５００ｎｍ以下である高分子電解質膜である。 A third aspect of the present invention is the polymer electrolyte membrane according to the first or second aspect, wherein the metal fine particles have a particle diameter of 500 nm or less.
本発明の第４の態様は、前記第１～３のいずれか１つの態様において、前記金属微粒子の形成材料が、白金、金、パラジウム、イリジウム、ロジウムおよびルテニウムからなる貴金属群より選ばれる、少なくとも１種の貴金属もしくは貴金属合金のいずれか一方、または両方を含む高分子電解質膜である。 According to a fourth aspect of the present invention, in any one of the first to third aspects, the metal fine particle forming material is selected from a noble metal group consisting of platinum, gold, palladium, iridium, rhodium and ruthenium, A polymer electrolyte membrane containing one or both of one kind of noble metal and noble metal alloy.
本発明の第５の態様は、前記第１～４のいずれか１つの態様において、前記高分子電解質が、炭化水素系高分子電解質からなる高分子電解質膜である。 According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the polymer electrolyte is a polymer electrolyte membrane made of a hydrocarbon polymer electrolyte.
本発明の第６の態様は、前記第５の態様において、前記炭化水素系高分子電解質が、イオン交換基を有するセグメントと、イオン交換基を実質的に有しないセグメントと、を備えたブロック共重合体を含む高分子電解質膜である。 According to a sixth aspect of the present invention, there is provided a block copolymer according to the fifth aspect, wherein the hydrocarbon-based polymer electrolyte includes a segment having an ion exchange group and a segment having substantially no ion exchange group. A polymer electrolyte membrane containing a polymer.
本発明の第７の態様は、前記第１～６のいずれか１つの態様において、前記高分子電解質で形成された膜状の母材の表面に、金属層を積層させ、前記母材と前記金属層との両面から電圧を印加することで前記母材の内部に析出させた前記金属微粒子を含む高分子電解質膜である。 According to a seventh aspect of the present invention, in any one of the first to sixth aspects, a metal layer is laminated on a surface of a film-shaped base material formed of the polymer electrolyte, and the base material and the base material The polymer electrolyte membrane includes the metal fine particles deposited inside the base material by applying a voltage from both sides of the metal layer.
本発明の第８の態様は、前記第７の態様において、前記金属層が、物理蒸着法によって形成される高分子電解質膜である。 An eighth aspect of the present invention is the polymer electrolyte membrane according to the seventh aspect, wherein the metal layer is formed by physical vapor deposition.
本発明の第９の態様は、前記第７の態様において、前記金属層が、金属微粒子を含有する液を前記母材の表面に塗工して形成される高分子電解質膜である。 A ninth aspect of the present invention is the polymer electrolyte membrane according to the seventh aspect, wherein the metal layer is formed by applying a liquid containing metal fine particles to the surface of the base material.
本発明の第１０の態様は、前記第１～９のいずれか１つの態様に記載の高分子電解質膜と、前記高分子電解質膜を挟持するアノード触媒層およびカソード触媒層とを有する膜電極接合体である。 According to a tenth aspect of the present invention, there is provided a membrane electrode junction comprising the polymer electrolyte membrane according to any one of the first to ninth aspects, and an anode catalyst layer and a cathode catalyst layer sandwiching the polymer electrolyte membrane. Is the body.
本発明の第１１の態様は、前記第１０の態様において、前記金属微粒子の濃度の極大値が、前記高分子電解質膜の膜厚方向の中心よりも前記カソード触媒層側にある膜電極接合体である。 An eleventh aspect of the present invention is the membrane electrode assembly according to the tenth aspect, wherein the maximum value of the concentration of the metal fine particles is closer to the cathode catalyst layer side than the center in the film thickness direction of the polymer electrolyte membrane. It is.
本発明の第１２の態様は、前記第１０または１１の態様に記載の膜電極接合体を有する燃料電池である。 A twelfth aspect of the present invention is a fuel cell having the membrane electrode assembly according to the tenth or eleventh aspect.
本発明によれば、高耐久化がなされた高分子電解質膜を得ることができる。また、このような高分子電解質膜を用いることで、長期安定性に優れた膜電極接合体を得ることができる。更に、このような膜電極接合体を用いることで、長期安定性に優れた燃料電池とすることができる。そして、このような高耐久化を実現することが可能な高分子電解質膜を容易に製造することができる。 According to the present invention, a highly durable polymer electrolyte membrane can be obtained. Moreover, the membrane electrode assembly excellent in long-term stability can be obtained by using such a polymer electrolyte membrane. Furthermore, by using such a membrane electrode assembly, a fuel cell having excellent long-term stability can be obtained. And the polymer electrolyte membrane which can implement | achieve such high durability can be manufactured easily.
本発明の好適な一実施態様の燃料電池のセルについての縦断面図である。It is a longitudinal cross-sectional view about the cell of the fuel cell of preferable one Embodiment of this invention. 本発明の好適な一実施態様の高分子電解質膜の膜内を示す電子顕微鏡写真である。1 is an electron micrograph showing the inside of a polymer electrolyte membrane according to a preferred embodiment of the present invention. 本発明の好適な一実施態様の高分子電解質膜の製造工程を示す工程図の一部である。FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention. 本発明の好適な一実施態様の高分子電解質膜の製造工程を示す工程図の一部である。FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention. 本発明の好適な一実施態様の高分子電解質膜の製造工程を示す工程図の一部である。FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention. 本発明の好適な一実施態様の高分子電解質膜の製造工程を示す工程図の一部である。FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention. 本発明の好適な一実施態様の高分子電解質膜の製造工程を示す工程図の一部である。FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention. 本発明の好適な一実施態様の高分子電解質膜の製造工程を示す工程図の一部である。FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention. 本発明の好適な一実施態様の高分子電解質膜の製造工程を示す工程図の一部である。FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention. 本発明の好適な一実施態様の高分子電解質膜の製造工程を示す工程図の一部である。FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention. 本発明の好適な一実施態様の高分子電解質膜の製造工程を示す工程図の一部である。FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention. 本発明の好適な一実施態様の高分子電解質膜の製造工程を示す工程図の一部である。FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention. 本発明の好適な一実施態様の高分子電解質膜の製造工程を示す工程図の一部である。FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention. 本発明の好適な一実施態様の高分子電解質膜の製造工程を示す工程図の一部である。FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention. 本発明の好適な一実施態様の高分子電解質膜の製造工程を示す工程図の一部である。FIG. 2 is a part of a process chart showing a production process of a polymer electrolyte membrane according to a preferred embodiment of the present invention. 本実施形態の高分子電解質膜の膜内を示す電子顕微鏡写真である。It is an electron micrograph which shows the inside of the polymer electrolyte membrane of this embodiment. 本実施形態の高分子電解質膜の膜内を示す電子顕微鏡写真である。It is an electron micrograph which shows the inside of the polymer electrolyte membrane of this embodiment. 本実施形態の高分子電解質膜の膜内を示す電子顕微鏡写真である。It is an electron micrograph which shows the inside of the polymer electrolyte membrane of this embodiment. 本発明の好適な一実施態様の膜電極接合体についての縦断面図である。It is a longitudinal cross-sectional view about the membrane electrode assembly of one suitable embodiment of this invention.
以下、図１から図１０を用いて、本発明の実施形態に係る膜電極接合体および燃料電池について順次説明する。 Hereinafter, the membrane electrode assembly and the fuel cell according to the embodiment of the present invention will be described in order with reference to FIGS.
＜燃料電池＞
図１は、本発明の好適な一実施態様の膜電極接合体を有する燃料電池のセル（以下、単に燃料電池と称することがある。）についての縦断面図である。図１では、燃料電池１０は、高分子電解質膜１２と、これら挟む一対の触媒層１４ａ，１４ｂとから構成された膜電極接合体（ＭＥＡ）２０を備えている。
高分子電解質膜１２については後に詳述する。 <Fuel cell>
FIG. 1 is a longitudinal sectional view of a cell of a fuel cell having a membrane electrode assembly according to a preferred embodiment of the present invention (hereinafter sometimes simply referred to as a fuel cell). In FIG. 1, the fuel cell 10 includes a membrane electrode assembly (MEA) 20 composed of a polymer electrolyte membrane 12 and a pair of catalyst layers 14a and 14b sandwiched therebetween.
The polymer electrolyte membrane 12 will be described in detail later.
燃料電池１０は、膜電極接合体２０の両側に、これを挟むようにガス拡散層１６ａ，１６ｂおよびセパレータ１８ａ，１８ｂ（セパレータ１８ａ，１８ｂは、触媒層１４ａ，１４ｂ側に、燃料ガス等の流路となる溝（図示せず）が形成されていると好ましい）を順に備えている。なお、膜電極接合体２０およびガス拡散層１６ａ，１６ｂとからなる構造体は、一般的に、膜電極－ガス拡散層接合体（ＭＥＧＡ）と呼ばれることがある。 In the fuel cell 10, gas diffusion layers 16a and 16b and separators 18a and 18b are sandwiched between both sides of the membrane electrode assembly 20 (the separators 18a and 18b flow toward the catalyst layers 14a and 14b). It is preferable that a groove (not shown) to be a path is formed in order. A structure composed of the membrane electrode assembly 20 and the gas diffusion layers 16a and 16b may be generally called a membrane electrode-gas diffusion layer assembly (MEGA).
アノード触媒層１４ａ、およびカソード触媒層１４ｂは、燃料電池１０における電極層として機能する層である。アノード触媒層１４ａ、およびカソード触媒層１４ｂには、電極触媒とパーフルオロアルキルスルホン酸樹脂等のプロトン伝導性を有する高分子電解質とが含まれる。 The anode catalyst layer 14 a and the cathode catalyst layer 14 b are layers that function as electrode layers in the fuel cell 10. The anode catalyst layer 14a and the cathode catalyst layer 14b include an electrode catalyst and a polymer electrolyte having proton conductivity such as perfluoroalkyl sulfonic acid resin.
ここで電極触媒としては、水素または酸素との酸化還元反応を活性化できる電極触媒であれば特に制限はなく、公知の電極触媒を用いることができるが、白金または白金系合金の微粒子を触媒として用いることが好ましい。白金または白金系合金の微粒子はしばしば活性炭や黒鉛などの粒子状または繊維状のカーボンに担持されて用いられることもある。 Here, the electrode catalyst is not particularly limited as long as it can activate a redox reaction with hydrogen or oxygen, and a known electrode catalyst can be used, but platinum or platinum-based alloy fine particles are used as a catalyst. It is preferable to use it. The fine particles of platinum or platinum-based alloys are often used by being supported on particulate or fibrous carbon such as activated carbon or graphite.
ガス拡散層１６ａ，１６ｂは、触媒層１４ａ，１４ｂへの原料ガスの拡散を促進する機能を有する層である。このガス拡散層１６ａ，１６ｂは、電子伝導性を有する多孔質材料により構成されることが好ましい。前記多孔質材料としては、多孔質性のカーボン不織布、またはカーボンペーパーが、原料ガスを触媒層１４ａ，１４ｂへ効率的に輸送することができるために好ましい。 The gas diffusion layers 16a and 16b are layers having a function of promoting the diffusion of the raw material gas into the catalyst layers 14a and 14b. The gas diffusion layers 16a and 16b are preferably made of a porous material having electron conductivity. As the porous material, a porous carbon nonwoven fabric or carbon paper is preferable because the raw material gas can be efficiently transported to the catalyst layers 14a and 14b.
セパレータ１８ａ，１８ｂは、電子伝導性を有する材料で形成されている。前記電子伝導性を有する材料としては、例えば、カーボン、樹脂モールドカーボン、チタン、ステンレスが挙げられる。 Separator 18a, 18b is formed with the material which has electronic conductivity. Examples of the material having electron conductivity include carbon, resin mold carbon, titanium, and stainless steel.
このようにして製造された燃料電池は、燃料として、例えば、水素ガス、改質水素ガス、メタノールを用いる各種の形式で使用可能である。 The fuel cell manufactured in this way can be used in various forms using, for example, hydrogen gas, reformed hydrogen gas, and methanol as fuel.
＜膜電極接合体＞
以下、本発明の一実施態様としての膜電極接合体２０について、更に説明する。図１０で表される膜電極接合体２０は、上述のように高分子電解質膜１２を挟む一対の触媒層１４ａ，１４ｂを有している。 <Membrane electrode assembly>
Hereinafter, the membrane electrode assembly 20 as one embodiment of the present invention will be further described. The membrane electrode assembly 20 shown in FIG. 10 has a pair of catalyst layers 14a and 14b that sandwich the polymer electrolyte membrane 12 as described above.
＜高分子電解質膜＞
まず、本実施形態の高分子電解質膜１２について説明する。図２は、高分子電解質膜１２の膜内の様子を示す透過型電子顕微鏡写真である。図に示すように、本実施形態の高分子電解質膜１２は、高分子電解質を形成材料とした母材１２Ｘと、母材１２Ｘ内に分散した金属微粒子１３Ａと、を有している。金属微粒子１３Ａは、図２の写真の中で黒い斑点状に示されている。 <Polymer electrolyte membrane>
First, the polymer electrolyte membrane 12 of this embodiment will be described. FIG. 2 is a transmission electron micrograph showing the inside of the polymer electrolyte membrane 12. As shown in the figure, the polymer electrolyte membrane 12 of the present embodiment includes a base material 12X using a polymer electrolyte as a forming material and metal fine particles 13A dispersed in the base material 12X. The metal fine particles 13A are shown as black spots in the photograph of FIG.
＜高分子電解質＞
高分子電解質膜１２の母材を構成する高分子電解質としては、以下に示すように、炭化水素系高分子電解質と、フッ素系高分子電解質とを挙げることができる。
また、母材１２Ｘを構成する高分子電解質以外の成分としては、通常の高分子に使用される可塑剤、安定剤、離型剤、保水剤等の添加剤が挙げられる。 <Polymer electrolyte>
Examples of the polymer electrolyte constituting the base material of the polymer electrolyte membrane 12 include hydrocarbon polymer electrolytes and fluorine polymer electrolytes as described below.
Further, as components other than the polymer electrolyte constituting the base material 12X, additives such as plasticizers, stabilizers, mold release agents, water retention agents and the like used for ordinary polymers can be mentioned.
（炭化水素系高分子電解質）
まず、本発明の一実施態様における高分子電解質膜に用いることができる炭化水素系高分子電解質について説明する。 (Hydrocarbon polymer electrolyte)
First, a hydrocarbon polymer electrolyte that can be used for the polymer electrolyte membrane in one embodiment of the present invention will be described.
ここで、炭化水素系高分子電解質とは、この高分子電解質を構成する元素質量含有比で表してハロゲン原子が１５質量％以下である高分子電解質を意味する。かかる炭化水素系高分子電解質は、前記のフッ素系高分子電解質と比較して安価であるという利点を有するため、より好ましい。特に好適な炭化水素系高分子電解質とは実質的にハロゲン原子を含有していない炭化水素系高分子電解質であり、このような炭化水素系高分子電解質は燃料電池の作動時に、ハロゲン化水素を発生して、他の部材を腐食させたりする恐れがない。
なお、ここでいう「炭化水素系高分子電解質」とは複素原子を含んでもよい。 Here, the hydrocarbon polymer electrolyte means a polymer electrolyte having a halogen atom content of 15% by mass or less in terms of the mass content ratio of elements constituting the polymer electrolyte. Such a hydrocarbon-based polymer electrolyte is more preferable because it has an advantage that it is cheaper than the above-mentioned fluorine-based polymer electrolyte. Particularly preferred hydrocarbon polymer electrolytes are hydrocarbon polymer electrolytes that do not substantially contain halogen atoms. Such hydrocarbon polymer electrolytes do not generate hydrogen halide during the operation of the fuel cell. There is no danger of corrosion and corrosion of other components.
The “hydrocarbon polymer electrolyte” mentioned here may contain a hetero atom.
また、炭化水素系高分子電解質は、イオン交換基を有する高分子であることが好ましい。その理由は、このようにイオン交換基を有する高分子電解質を用いて燃料電池用の高分子電解質膜を得たとき、この高分子電解質膜のイオン伝導性が良好になるためである。 The hydrocarbon-based polymer electrolyte is preferably a polymer having an ion exchange group. The reason is that when a polymer electrolyte membrane for a fuel cell is obtained using a polymer electrolyte having an ion exchange group, the ion conductivity of the polymer electrolyte membrane is improved.
上述のイオン交換基として、酸性のイオン交換基（すなわち、カチオン交換基）または塩基性のイオン交換基（すなわち、アニオン交換基）が挙げられる。高いプロトン伝導性を得る観点から、イオン交換基はカチオン交換基であることが好ましい。カチオン交換基を有する高分子電解質を用いることにより、一層発電性能に優れた燃料電池が得られる。カチオン交換基としては、例えば、スルホ基（－ＳＯ３Ｈ）、カルボキシル基（－ＣＯＯＨ）、ホスホノ基（－ＰＯ３Ｈ２）、スルホニルイミド基（－ＳＯ２ＮＨＳＯ２－）、フェノール性水酸基等が挙げられる。これらの中でも、カチオン交換基としては、スルホ基またはホスホノ基がより好ましく、スルホ基が特に好ましい。なお、これらのイオン交換基は、部分的に、あるいは全てが、金属イオンや４級アンモニウムイオン等で交換されて塩を形成していてもよいが、燃料電池用部材として使用する際には、実質的に全てが遊離酸の形態であることが好ましい。前記イオン交換基が遊離酸の形態であると、後述する積層フィルムの製造において、高分子電解質溶液の調製がより容易になるという利点もある。 Examples of the ion exchange group include an acidic ion exchange group (that is, a cation exchange group) or a basic ion exchange group (that is, an anion exchange group). From the viewpoint of obtaining high proton conductivity, the ion exchange group is preferably a cation exchange group. By using a polymer electrolyte having a cation exchange group, a fuel cell having further excellent power generation performance can be obtained. Examples of the cation exchange group include a sulfo group (—SO 3 H), a carboxyl group (—COOH), a phosphono group (—PO 3 H 2 ), a sulfonylimide group (—SO 2 NHSO 2 —), a phenolic hydroxyl group, and the like. Is mentioned. Among these, as the cation exchange group, a sulfo group or a phosphono group is more preferable, and a sulfo group is particularly preferable. These ion exchange groups may be partially or wholly exchanged with metal ions or quaternary ammonium ions to form a salt, but when used as a fuel cell member, It is preferred that substantially all are in the free acid form. When the ion exchange group is in the form of a free acid, there is an advantage that the preparation of the polymer electrolyte solution becomes easier in the production of the laminated film described later.
これらのイオン交換基は、高分子電解質の主鎖もしくは側鎖の何れか一方に、または両方に導入されていてもよいが、主鎖へ導入されているのが好ましい。 These ion exchange groups may be introduced into either or both of the main chain or side chain of the polymer electrolyte, but are preferably introduced into the main chain.
前記高分子電解質がイオン交換基を有する場合、前記イオン交換基の導入量は、高分子電解質単位質量当たりのイオン交換基数であるイオン交換基容量で表すことができる。 When the polymer electrolyte has an ion exchange group, the introduction amount of the ion exchange group can be represented by an ion exchange group capacity which is the number of ion exchange groups per unit mass of the polymer electrolyte.
ここで「イオン交換基容量」とは、高分子電解質膜を構成する高分子電解質の、乾燥樹脂１ｇ当たりに含有するイオン交換基の当量数で定義される値［ミリ当量／ｇ乾燥樹脂］（以下、ｍｅｑ／ｇ）である。 Here, the “ion exchange group capacity” is a value [milli equivalent / g dry resin] defined by the number of equivalents of ion exchange groups contained in 1 g of dry resin in the polymer electrolyte constituting the polymer electrolyte membrane. Hereinafter, meq / g).
また、「乾燥樹脂」とは高分子電解質を、水の沸点以上の温度に保持し、質量減少がほとんどなくなり質量の経時変化がほぼ一定値に収束した樹脂をいう。 In addition, “dry resin” refers to a resin in which the polymer electrolyte is maintained at a temperature equal to or higher than the boiling point of water, the mass decrease hardly occurs, and the change in mass with time converges to a substantially constant value.
本実施形態で用いる高分子電解質は、イオン交換基の導入量が、イオン交換容量で表して０．５ｍｅｑ／ｇ以上６．０ｍｅｑ／ｇ以下であると好ましく；１．０ｍｅｑ／ｇ以上６．０ｍｅｑ／ｇ以下であるとより好ましく；２．０ｍｅｑ／ｇ以上５．５ｍｅｑ／ｇ以下であると、更に好ましく；２．７ｍｅｑ／ｇ以上５．０ｍｅｑ／ｇ以下であると最も好ましい。イオン交換容量がこの範囲であると、得られる高分子電解質膜のプロトン伝導性や耐水性がより良好となり、いずれも燃料電池の使用される高分子電解質膜としての機能が優れるので好ましい。 In the polymer electrolyte used in the present embodiment, the amount of ion exchange groups introduced is preferably 0.5 meq / g or more and 6.0 meq / g or less in terms of ion exchange capacity; 1.0 meq / g or more and 6.0 meq. / G or less; more preferably 2.0 meq / g or more and 5.5 meq / g or less; and most preferably 2.7 meq / g or more and 5.0 meq / g or less. When the ion exchange capacity is within this range, the polymer electrolyte membrane to be obtained has better proton conductivity and water resistance, both of which are excellent because the function as a polymer electrolyte membrane used in a fuel cell is excellent.
以下、好適なイオン交換基を有する高分子電解質に関し詳述する。このような高分子電解質の具体例としては、例えば、下記の（Ａ）～（Ｆ）で表される高分子電解質が挙げられる。
（Ａ）主鎖が脂肪族炭化水素からなる高分子に、イオン交換基が導入された高分子電解質；
（Ｂ）主鎖が脂肪族炭化水素からなり、主鎖の一部の水素原子がフッ素原子で置換された高分子に、イオン交換基が導入された高分子電解質；
（Ｃ）主鎖が芳香環を有する高分子に、イオン交換基が導入された高分子電解質；
（Ｄ）主鎖が、シロキサン基やフォスファゼン基等の無機の単位構造を有する高分子にイオン交換基が導入された高分子電解質；
（Ｅ）高分子電解質（Ａ）～（Ｄ）の調製に使用する高分子の主鎖を構成する構造単位から選ばれる２種以上の構造単位を組み合わせた共重合体に、イオン交換基が導入された高分子電解質；
（Ｆ）主鎖や側鎖に窒素原子を含む炭化水素系高分子に、硫酸やリン酸等の酸性化合物をイオン結合により導入した高分子電解質 Hereinafter, a polymer electrolyte having a suitable ion exchange group will be described in detail. Specific examples of such a polymer electrolyte include polymer electrolytes represented by the following (A) to (F).
(A) a polymer electrolyte in which an ion exchange group is introduced into a polymer whose main chain is an aliphatic hydrocarbon;
(B) a polymer electrolyte in which an ion exchange group is introduced into a polymer in which the main chain is composed of an aliphatic hydrocarbon and a part of the hydrogen atoms of the main chain is substituted with fluorine atoms;
(C) a polymer electrolyte in which an ion exchange group is introduced into a polymer having a main chain having an aromatic ring;
(D) a polymer electrolyte in which an ion exchange group is introduced into a polymer whose main chain has an inorganic unit structure such as a siloxane group or a phosphazene group;
(E) An ion exchange group is introduced into a copolymer obtained by combining two or more structural units selected from structural units constituting the main chain of the polymer used for the preparation of the polymer electrolytes (A) to (D). Polymer electrolytes;
(F) A polymer electrolyte in which an acidic compound such as sulfuric acid or phosphoric acid is introduced into a hydrocarbon polymer containing a nitrogen atom in the main chain or side chain by ionic bond
なお、以下の例示においては、イオン交換基がスルホ基である高分子電解質を主として例示するが、このスルホ基を別のイオン交換基に置き換えた高分子電解質でもよい。 In the following examples, a polymer electrolyte whose ion exchange group is a sulfo group is mainly exemplified, but a polymer electrolyte in which this sulfo group is replaced with another ion exchange group may be used.
前記（Ａ）の高分子電解質としては、例えば、ポリビニルスルホン酸、ポリスチレンスルホン酸、ポリ（α－メチルスチレン）スルホン酸等が挙げられる。 Examples of the polymer electrolyte (A) include polyvinyl sulfonic acid, polystyrene sulfonic acid, poly (α-methylstyrene) sulfonic acid, and the like.
前記（Ｂ）の高分子電解質としては、特開平９－１０２３２２号公報に記載された炭化フッ素系ビニルモノマーと炭化水素系ビニルモノマーとの共重合によって製造された高分子を主鎖とし、スルホ基を有する炭化水素鎖を側鎖とし、共重合様式がグラフト重合であるスルホン酸型ポリスチレン－グラフト－エチレン－テトラフルオロエチレン共重合体（ＥＴＦＥ）が挙げられる。また、米国特許第４，０１２，３０３号公報または米国特許第４，６０５，６８５号公報に記載された方法により得られる炭化フッ素系ビニルモノマーと炭化水素系ビニルモノマーとの共重合体に、α，β，β－トリフルオロスチレンをグラフト重合させ、これにスルホ基を導入して固体高分子電解質としたスルホン酸型ポリ(トリフルオロスチレン)－グラフト－ＥＴＦＥも挙げることができる。 As the polymer electrolyte (B), a polymer produced by copolymerization of a fluorocarbon vinyl monomer and a hydrocarbon vinyl monomer described in JP-A-9-102322 has a main chain, and a sulfo group. A sulfonic acid type polystyrene-graft-ethylene-tetrafluoroethylene copolymer (ETFE) having a hydrocarbon chain having a side chain as a side chain and a copolymerization mode of graft polymerization is exemplified. In addition, a copolymer of a fluorocarbon vinyl monomer and a hydrocarbon vinyl monomer obtained by the method described in US Pat. No. 4,012,303 or US Pat. There can also be mentioned sulfonic acid type poly (trifluorostyrene) -graft-ETFE in which a solid polymer electrolyte is prepared by graft polymerization of, β, β-trifluorostyrene and introducing a sulfo group into the polymer.
前記（Ｃ）の高分子電解質は、主鎖に酸素原子等のヘテロ原子を含む高分子電解質であってもよい。このような高分子電解質としては、例えば、ポリエーテルケトン、ポリエーテルエーテルケトン、ポリスルホン、ポリエーテルスルホン、ポリエーテルエーテルスルホン、ポリ（アリーレンエーテル）、ポリイミド、ポリ（（４－フェノキシベンゾイル）－１，４－フェニレン）、ポリフェニルキノキサレン等の単独重合体のそれぞれに、スルホ基が導入された高分子電解質が挙げられる。具体的には、スルホアリール化ポリベンズイミダゾール、スルホアルキル化ポリベンズイミダゾール（例えば、特開平９－１１０９８２号公報参照）等が挙げられる。前記（Ｃ）の高分子電解質は、主鎖が酸素原子等のヘテロ原子で中断されている化合物であってもよく、例えば、ポリエーテルエーテルケトン、ポリスルホン、ポリエーテルスルホン、ポリ（アリーレンエーテル）、ポリイミド、ポリ（（４－フェノキシベンゾイル）－１，４－フェニレン）、ポリフェニレンスルフィド、ポリフェニルキノキサレン、スルホアリール化ポリベンズイミダゾール、スルホアルキル化ポリベンズイミダゾール、ホスホアルキル化ポリベンズイミダゾール、ホスホン化ポリ（フェニレンエーテル）が挙げられる。このような高分子電解質は、特開平９－１１０９８２号公報、およびＪ．Ａｐｐｌ．Ｐｏｌｙｍ．Ｓｃｉ．，１８，１９６９（１９７４）にも記載されている。 The polymer electrolyte (C) may be a polymer electrolyte containing a hetero atom such as an oxygen atom in the main chain. Examples of such a polymer electrolyte include polyether ketone, polyether ether ketone, polysulfone, polyether sulfone, polyether ether sulfone, poly (arylene ether), polyimide, poly ((4-phenoxybenzoyl) -1, Examples thereof include polymer electrolytes each having a sulfo group introduced into each of homopolymers such as 4-phenylene) and polyphenylquinoxalen. Specific examples include sulfoarylated polybenzimidazoles and sulfoalkylated polybenzimidazoles (for example, see JP-A-9-110882). The polymer electrolyte (C) may be a compound in which the main chain is interrupted by a heteroatom such as an oxygen atom. For example, polyetheretherketone, polysulfone, polyethersulfone, poly (arylene ether), Polyimide, poly ((4-phenoxybenzoyl) -1,4-phenylene), polyphenylene sulfide, polyphenylquinoxalen, sulfoarylated polybenzimidazole, sulfoalkylated polybenzimidazole, phosphoalkylated polybenzimidazole, phosphonated Poly (phenylene ether) is mentioned. Such polymer electrolytes are disclosed in JP-A-9-110882 and J.P. Appl. Polym. Sci. 18, 1969 (1974).
前記（Ｄ）の高分子電解質としては、例えば、ポリフォスファゼンにスルホ基が導入された高分子電解質等が挙げられる。これらは、Ｐｏｌｙｍｅｒ　Ｐｒｅｐ．，４１，Ｎｏ．１，７０（２０００）に記載された方法に準じて容易に製造することができる。 Examples of the polymer electrolyte (D) include a polymer electrolyte in which a sulfo group is introduced into polyphosphazene. These are Polymer Prep. , 41, no. 1, 70 (2000).
前記（Ｅ）の高分子電解質は、スルホ基が導入されたランダム共重合体、スルホ基が導入された交互共重合体、またはスルホ基が導入されたブロック共重合体のいずれであってもよい。 The polymer electrolyte (E) may be any of a random copolymer having a sulfo group introduced therein, an alternating copolymer having a sulfo group introduced therein, or a block copolymer having a sulfo group introduced therein. .
前記（Ｆ）の高分子電解質としては、例えば、特表平１１－５０３２６２号公報に記載されたようなリン酸を導入させたポリベンズイミダゾール等が挙げられる。 Examples of the polymer electrolyte (F) include polybenzimidazole into which phosphoric acid is introduced as described in JP-A-11-503262.
さらに、本発明の一実施態様における高分子電解質膜に使用する高分子電解質としては、イオン交換基を有する構造単位とイオン交換基を有しない構造単位とからなる共重合体が、好ましい。このような共重合体であると、得られる高分子電解質を用い、後述の方法にて作成される高分子電解質膜が良好なプロトン伝導性と耐水性を発現し、燃料電池用として有利であるという利点がある。なお、かかる共重合体に関し、２種の構造単位の共重合様式は、ランダム共重合、ブロック共重合、グラフト共重合または交互共重合のいずれであってもよく、これらの共重合様式を組み合わせてもよい。 Furthermore, the polymer electrolyte used for the polymer electrolyte membrane in one embodiment of the present invention is preferably a copolymer composed of a structural unit having an ion exchange group and a structural unit having no ion exchange group. When such a copolymer is used, the polymer electrolyte membrane prepared by the method described later using the resulting polymer electrolyte exhibits good proton conductivity and water resistance, and is advantageous for fuel cells. There is an advantage. In addition, regarding such a copolymer, the copolymerization mode of the two kinds of structural units may be any of random copolymerization, block copolymerization, graft copolymerization or alternating copolymerization, and these copolymerization modes are combined. Also good.
燃料電池用として良好な耐熱性を有する高分子電解質膜を得るためには、前記炭化水素系高分子電解質であって、中でも、主鎖に芳香環を有する炭化水素系高分子電解質（すなわち、上記（Ｃ）で表される炭化水素系高分子電解質）が好ましく；さらには主鎖を構成する芳香環を有し、かつ前記芳香環に直接結合または他の原子もしくは原子団を介して間接的に結合したイオン交換基を有する炭化水素系高分子電解質が好ましい。特に、主鎖を構成する芳香族を有し、さらに芳香環を有する側鎖を有してもよく、主鎖を構成する芳香環か側鎖の芳香環の、どちらかの芳香環に直接結合したイオン交換基を有する芳香族系高分子電解質が好ましい。 In order to obtain a polymer electrolyte membrane having good heat resistance for a fuel cell, the hydrocarbon polymer electrolyte, particularly a hydrocarbon polymer electrolyte having an aromatic ring in the main chain (that is, the above-mentioned (C) a hydrocarbon-based polymer electrolyte) is preferred; and further has an aromatic ring constituting the main chain, and is directly bonded to the aromatic ring or indirectly through another atom or atomic group Hydrocarbon polymer electrolytes having bound ion exchange groups are preferred. In particular, it may have aromatics constituting the main chain, and may further have side chains having aromatic rings, and directly bonded to either the aromatic ring constituting the main chain or the aromatic ring of the side chain. An aromatic polymer electrolyte having an ion exchange group is preferred.
特に好ましい芳香族系高分子電解質としては、分子構造内にイオン交換基を有する構造単位と、イオン交換基を有しない構造単位と、を有する高分子電解質が例示される。 Particularly preferred aromatic polymer electrolytes include polymer electrolytes having a structural unit having an ion exchange group in the molecular structure and a structural unit having no ion exchange group.
上述のイオン交換基を有する構造単位としては、下記式（１１ａ）～（１４ａ）で示される構造を例示することができる。 Examples of the structural unit having an ion exchange group include structures represented by the following formulas (11a) to (14a).
Figure JPOXMLDOC01-appb-C000001
 （式中、Ａｒ１～Ａｒ９は、それぞれ同一または相異なり、主鎖に芳香環を有し、さらに芳香環を有する側鎖を有してもよい２価の芳香族基を表し；イオン交換基が、前記主鎖の芳香環か側鎖の芳香環の少なくとも１つに直接結合しており； 
ＺおよびＺ’はそれぞれ同一または相異なり－ＣＯ－で示される基、または－ＳＯ２－で示される基のいずれかを表し；Ｘ、Ｘ’、およびＸ”はそれぞれ同一または相異なり－Ｏ－で示される基、－Ｓ－で示される基のいずれかを表し；Ｙは直接結合もしくは下記式（１５）で表される基を表し；ｐは０、１または２を表し；ｑ、ｒはそれぞれ同一または相異なり１、２または３を表す。）
Figure JPOXMLDOC01-appb-C000001
 (Wherein Ar 1 to Ar 9 are the same or different and each represents a divalent aromatic group which may have a side chain having an aromatic ring in the main chain and further having an aromatic ring; A group is directly bonded to at least one of the aromatic ring of the main chain or the aromatic ring of the side chain;
Z and Z ′ are the same or different and each represents a group represented by —CO— or a group represented by —SO 2 —; X, X ′, and X ″ are the same or different —O— Y represents a direct bond or a group represented by the following formula (15); p represents 0, 1 or 2; q and r represent Each represents the same or different and represents 1, 2 or 3.)
また、上述のイオン交換基を有しない構造単位としては、下記式（１１ｂ）～（１４ｂ）で示される構造を例示することができる。 Moreover, examples of the structural unit having no ion exchange group include structures represented by the following formulas (11b) to (14b).
Figure JPOXMLDOC01-appb-C000002
 （式中、Ａｒ１１～Ａｒ１９は、それぞれ同一または相異なり側鎖としての置換基を有していてもよい２価の芳香族基を表し；
Ｚ、およびＺ’はそれぞれ同一または相異なり－ＣＯ－で示される基、または－ＳＯ２－で示される基のいずれかを表し；Ｘ、Ｘ’およびＸ”はそれぞれ同一または相異なり－Ｏ－で示される基、または－Ｓ－で示される基のいずれかを表し；Ｙは直接結合もしくは下記式（１５）で表される基を表し；ｐ’は０、１または２を表し、ｑ’、およびｒ’はそれぞれ同一または相異なり１、２または３を表す。）
Figure JPOXMLDOC01-appb-C000002
 (In the formula, Ar 11 to Ar 19 are the same or different and each represents a divalent aromatic group which may have a substituent as a side chain;
Z and Z ′ are the same or different and each represents a group represented by —CO— or a group represented by —SO 2 —; X, X ′ and X ″ are the same or different —O— Or Y represents a direct bond or a group represented by the following formula (15); p ′ represents 0, 1 or 2, q ′ And r ′ are the same or different and represent 1, 2 or 3.
Figure JPOXMLDOC01-appb-C000003
 （式中、Ｒ１およびＲ２はそれぞれ同一または相異なり、水素原子、置換基を有していてもよい炭素数１～２０のアルキル基、置換基を有していてもよい炭素数１～２０のアルコキシ基、置換基を有していてもよい炭素数６～２０のアリール基、置換基を有していてもよい炭素数６～２０のアリールオキシ基または置換基を有していてもよい炭素数２～２１のアシル基を表し；Ｒ１とＲ２とが連結して環を形成していてもよく；Ｒ１とＲ２とが連結して形成される環を有する式（１５）の基としては、シクロヘキシリデン基などの炭素数５～２０の２価の環状炭化水素基が挙げられる。）
Figure JPOXMLDOC01-appb-C000003
 (Wherein R 1 and R 2 are the same or different and each is a hydrogen atom, an optionally substituted alkyl group having 1 to 20 carbon atoms, or an optionally substituted carbon group having 1 to 20 alkoxy groups, optionally substituted aryl groups having 6 to 20 carbon atoms, optionally substituted aryloxy groups having 6 to 20 carbon atoms, or substituted groups. Represents a good acyl group having 2 to 21 carbon atoms; R 1 and R 2 may be linked to form a ring; and R 1 and R 2 are linked to form a ring (15) ) Includes divalent cyclic hydrocarbon groups having 5 to 20 carbon atoms such as a cyclohexylidene group.
イオン交換基を有する構造単位を示す式（１１ａ）～（１４ａ）において、Ａｒ１～Ａｒ９は、２価の芳香族基を表す。２価の芳香族基としては、例えば、１，３－フェニレン基、１，４－フェニレン基等の２価の単環性芳香族炭化水素基；１，３－ナフタレンジイル基、１，４－ナフタレンジイル基、１，５－ナフタレンジイル基、１，６－ナフタレンジイル基、１，７－ナフタレンジイル基、２，６－ナフタレンジイル基、２，７－ナフタレンジイル基等の２価の縮合環系芳香族炭化水素基；ピロール、イミダゾール、ピラゾール、イソオキサゾール、ピリジン、ピラジン、ピリミジン、ピリダジン、インドリジン、イソインドール、３Ｈ－インドール、インドール、１Ｈ－インダゾール、プリン、４Ｈ－キノリジン、キノリン、イソキノリン、フタラジン、ナフチリジン、キノキサリン、キナゾリン、シンノリン、プテリジン、カルバゾール、カルボリン、フェナントリジン、アクリジン、ペリミジン、フェナントロリン、フェナジン、フラザン、フェノキサジン、インドリン、イソインドリン、キヌクリジン、オキサゾール、ベンゾオキサゾール、１，３，５－トリアジン、テトラゾール、テトラジン、トリアゾール、フェナルサジン、ベンゾイミダゾール、およびベンゾトリアゾールからなる群より選ばれる１種の化合物から芳香環上の水素原子を２個取り去って得られる２価のヘテロ芳香族基；下記式（Ｎ－０１）～（Ｎ－０７）で表される構造からなる群より選ばれる少なくとも１種の構造を含む２価のヘテロ芳香族基等が挙げられる。 In the formulas (11a) to (14a) showing the structural unit having an ion exchange group, Ar 1 to Ar 9 represent a divalent aromatic group. Examples of the divalent aromatic group include divalent monocyclic aromatic hydrocarbon groups such as 1,3-phenylene group and 1,4-phenylene group; 1,3-naphthalenediyl group, 1,4- Divalent condensed rings such as naphthalenediyl group, 1,5-naphthalenediyl group, 1,6-naphthalenediyl group, 1,7-naphthalenediyl group, 2,6-naphthalenediyl group, 2,7-naphthalenediyl group, etc. Pyrrole, imidazole, pyrazole, isoxazole, pyridine, pyrazine, pyrimidine, pyridazine, indolizine, isoindole, 3H-indole, indole, 1H-indazole, purine, 4H-quinolidine, quinoline, isoquinoline, Phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, carbazole, carboline Phenanthridine, acridine, perimidine, phenanthroline, phenazine, furazane, phenoxazine, indoline, isoindoline, quinuclidine, oxazole, benzoxazole, 1,3,5-triazine, tetrazole, tetrazine, triazole, phenalsazine, benzimidazole, and benzo A divalent heteroaromatic group obtained by removing two hydrogen atoms on an aromatic ring from one compound selected from the group consisting of triazoles; represented by the following formulas (N-01) to (N-07) And divalent heteroaromatic groups containing at least one structure selected from the group consisting of structures.
Figure JPOXMLDOC01-appb-C000004
Figure JPOXMLDOC01-appb-C000004
式（１１ａ）～（１４ａ）におけるＡｒ１～Ａｒ９としては、好ましくは、１，３－フェニレン基、１，４－フェニレン基等の２価の単環性芳香族炭化水素基；１，３－ナフタレンジイル基、１，４－ナフタレンジイル基、１，５－ナフタレンジイル基、１，６－ナフタレンジイル基、１，７－ナフタレンジイル基、２，６－ナフタレンジイル基、２，７－ナフタレンジイル基等の２価の縮合環系芳香族炭化水素基であり；より好ましくは２価の単環性芳香族炭化水素基である。 Ar 1 to Ar 9 in the formulas (11a) to (14a) are preferably divalent monocyclic aromatic hydrocarbon groups such as 1,3-phenylene group and 1,4-phenylene group; -Naphthalenediyl group, 1,4-naphthalenediyl group, 1,5-naphthalenediyl group, 1,6-naphthalenediyl group, 1,7-naphthalenediyl group, 2,6-naphthalenediyl group, 2,7-naphthalene A divalent condensed ring aromatic hydrocarbon group such as a diyl group; and more preferably a divalent monocyclic aromatic hydrocarbon group.
また、式（１１ａ）～（１４ａ）におけるＡｒ１～Ａｒ９で表される芳香族基の芳香環上の水素原子は、置換基を有していてもよい炭素数１～２０のアルキル基、置換基を有していてもよい炭素数１～２０のアルコキシ基、置換基を有していてもよい炭素数６～２０のアリール基、置換基を有していてもよい炭素数６～２０のアリールオキシ基または置換基を有していてもよい炭素数２～２１のアシル基で置換されていてもよい。 In addition, the hydrogen atom on the aromatic ring of the aromatic group represented by Ar 1 to Ar 9 in formulas (11a) to (14a) is an optionally substituted alkyl group having 1 to 20 carbon atoms, An optionally substituted alkoxy group having 1 to 20 carbon atoms, an optionally substituted aryl group having 6 to 20 carbon atoms, and an optionally substituted carbon group having 6 to 20 carbon atoms. The aryloxy group may be substituted with an acyl group having 2 to 21 carbon atoms which may have a substituent.
式（１１ａ）～（１４ａ）におけるＡｒ１～Ａｒ９で表される芳香族基は、芳香環に少なくとも一つのイオン交換基を有する。前記イオン交換基の具体例および好ましい例は前述のものと同様なものを挙げることができる。これらのイオン交換基は、高分子電解質の主鎖、側鎖の何れか一方、または両方に導入されていてもよいが、主鎖の芳香環へ導入されているのが好ましい。前記イオン交換基として、上述のように酸性のイオン交換基が好ましく、酸性のイオン交換基の中でも、スルホ基またはホスホノ基がより好ましく、スルホ基が特に好ましい。 The aromatic groups represented by Ar 1 to Ar 9 in formulas (11a) to (14a) have at least one ion exchange group in the aromatic ring. Specific examples and preferred examples of the ion exchange group can be the same as those described above. These ion exchange groups may be introduced into one or both of the main chain and the side chain of the polymer electrolyte, but are preferably introduced into the aromatic ring of the main chain. As the ion exchange group, an acidic ion exchange group is preferable as described above, and among the acidic ion exchange groups, a sulfo group or a phosphono group is more preferable, and a sulfo group is particularly preferable.
また、式（１４ａ）で表されるイオン交換基を有する構造単位の例の一つとして、下記式（１４ａ－１）で表される構造単位を挙げることができる。 Moreover, as an example of the structural unit having an ion exchange group represented by the formula (14a), a structural unit represented by the following formula (14a-1) can be given.
Figure JPOXMLDOC01-appb-C000005
 (上記式(１４ａ－１)中、Ａｒ１１０、Ａｒ１２０、Ａｒ１３０は、それぞれ独立に、２価の芳香族基を示し、その芳香環上の水素原子はフッ素原子で置換されていてもよく；Ｙ０００は、－ＣＯ－、－ＳＯ２－、－ＳＯ－、－ＣＯＮＨ－、－ＣＯＯ－、－（ＣＦ２）ｕ０００－（ｕ０００は１～１０の整数である）、－Ｃ（ＣＦ３）２－または直接結合を示し；Ｚ０００は、－Ｏ－、－Ｓ－、直接結合、－ＣＯ－、－ＳＯ２－、－ＳＯ－、－（ＣＨ２）ｋ０００－（ｋ０００は１～１０の整数である）または－Ｃ（ＣＨ３）２－を示し；Ｒ１１０は、直接結合、－Ｏ（ＣＨ２）ｐ０００－、－Ｏ（ＣＦ２）ｐ０００－、－（ＣＨ２）ｐ０００－または－（ＣＦ２）ｐ０００－を示し（ｐ０００は、１～１２の整数を示す）；Ｒ１２０、Ｒ１３０は、それぞれ独立に、水素原子、アルカリ金属原子または炭化水素基を示し；ただし、上記式中に含まれる全てのＲ１２０およびＲ１３０のうち少なくとも１個は水素原子であり；ｘ１００は、０～４の整数であり；ｘ２００は、１～５の整数であり；a０００は、０～１の整数であり、ｂ０００は、０～３の整数を示す。）
Figure JPOXMLDOC01-appb-C000005
 (In the above formula (14a-1), Ar 110 , Ar 120 , and Ar 130 each independently represent a divalent aromatic group, and the hydrogen atom on the aromatic ring may be substituted with a fluorine atom. Y 000 represents —CO—, —SO 2 —, —SO—, —CONH—, —COO— , — (CF 2 ) u000 — (u000 is an integer of 1 to 10), —C (CF 3 ) 2 - or a direct bond are shown; Z 000 is, -O -, - S-, a direct bond, -CO -, - SO 2 - , - SO -, - (CH 2) k000 - (k000 1-10 R 110 represents a direct bond, —O (CH 2 ) p000 —, —O (CF 2 ) p000 —, — (CH 2 ) p000 —, or —C (CH 3 ) 2 — - (CF 2) p000 - indicates (p000 is 1 to 12 Indicates the number); R 120, R 130 are each independently a hydrogen atom, an alkali metal atom or a hydrocarbon group; provided that at least one of all R 120 and R 130 contained in the above formulas X100 is an integer of 0 to 4; x200 is an integer of 1 to 5; a000 is an integer of 0 to 1, and b000 represents an integer of 0 to 3.)
式（１４ａ－１）におけるＡｒ１１０、Ａｒ１２０およびＡｒ１３０は、２価の芳香族基を表す。このような２価の芳香族基としては、式（１１ａ）～（１４ａ）におけるＡｒ１～Ａｒ９と同様の２価の芳香族基が挙げられる。 Ar 110 , Ar 120 and Ar 130 in the formula (14a-1) represent a divalent aromatic group. Examples of such a divalent aromatic group include the same divalent aromatic groups as Ar 1 to Ar 9 in formulas (11a) to (14a).
Ｒ１２０、Ｒ１３０は、それぞれ独立に、水素原子、アルカリ金属原子または炭化水素基を示す。アルカリ金属原子としては、例えば、リチウム、ナトリウム、カリウム、ルビジウム、またはセシウム、が挙げられる。
炭化水素基としては、複素環基を有していてもよく、このような炭化水素基としては、例えば、メチル基、エチル基、ｎ－プロピル基、ｉｓｏ－プロピル基、ｔｅｒｔ－ブチル基、ｉｓｏ－ブチル基、ｎ－ブチル基、ｓｅｃ－ブチル基、ネオペンチル基、シクロペンチル基、ヘキシル基、シクロヘキシル基、シクロペンチルメチル基、シクロヘキシルメチル基、アダマンチル基、アダマンタンメチル基、２－エチルヘキシル基、ビシクロ［２.２.１］へプチル基、ビシクロ［２.２.１］へプチルメチル基、テトラヒドロフルフリル基、２－メチルブチル基、３,３－ジメチル－２,４－ジオキソランメチル基、シクロヘキシルメチル基、アダマンチルメチル基、ビシクロ［２.２.１］ ヘプチルメチル基等の直鎖状炭化水素基、分岐状炭化水素基、脂環式炭化水素基、複素環基を有する炭化水素基等が挙げられる。これらのうちｎ－ブチル基、ネオペンチル基、テトラヒドロフルフリル基、シクロペンチル基、シクロヘキシル基、シクロヘキシルメチル基、アダマンチルメチル基、ビシクロ［２.２.１］ヘプチルメチル基が好ましく、さらにはネオペンチル基が好ましい。なお、Ｒ１２０、Ｒ１３０は、水素原子であることが好ましい。 R 120 and R 130 each independently represent a hydrogen atom, an alkali metal atom or a hydrocarbon group. Examples of the alkali metal atom include lithium, sodium, potassium, rubidium, and cesium.
The hydrocarbon group may have a heterocyclic group, and examples of such a hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, a tert-butyl group, an iso group. -Butyl group, n-butyl group, sec-butyl group, neopentyl group, cyclopentyl group, hexyl group, cyclohexyl group, cyclopentylmethyl group, cyclohexylmethyl group, adamantyl group, adamantanemethyl group, 2-ethylhexyl group, bicyclo [2. 2.1] heptyl group, bicyclo [2.2.1] heptylmethyl group, tetrahydrofurfuryl group, 2-methylbutyl group, 3,3-dimethyl-2,4-dioxolanemethyl group, cyclohexylmethyl group, adamantylmethyl A straight-chain hydrocarbon group such as a bicyclo [2.2.1] heptylmethyl group, a branched hydrocarbon group, Cyclic hydrocarbon group, and hydrocarbon group having a heterocyclic group. Of these, n-butyl, neopentyl, tetrahydrofurfuryl, cyclopentyl, cyclohexyl, cyclohexylmethyl, adamantylmethyl, and bicyclo [2.2.1] heptylmethyl are preferred, and neopentyl is more preferred. . R 120 and R 130 are preferably hydrogen atoms.
上記式（１４ａ－１）で表される構造単位は、さらに下記式（１４ａ－２）で表される構造単位であることが好ましい。 The structural unit represented by the above formula (14a-1) is preferably a structural unit represented by the following formula (14a-2).
Figure JPOXMLDOC01-appb-C000006
 （式(１４ａ-２)中、Ｙ００１は－ＣＯ－、－ＳＯ２－、－ＳＯ－、－ＣＯＮＨ－、－ＣＯＯ－、－（ＣＦ２）ｈ－（ここでのｈは１～１０の整数である）、および－Ｃ（ＣＦ３）２－からなる群より選ばれる少なくとも１種の構造を示し；Ｚ００１は直接結合または、－（ＣＨ２）ｇ－（ここでのｇは１～１０の整数である）、－Ｃ（ＣＨ３）２－、－Ｏ－、－Ｓ－、－ＣＯ－および－ＳＯ２－からなる群より選ばれる少なくとも１種の構造を示し；Ａｒ００１は－ＳＯ３Ｈ、－Ｏ（ＣＨ２）ｐＳＯ３Ｈまたは－Ｏ（ＣＦ２）ｐＳＯ３Ｈで表される置換基を有する芳香族基を示し；ｐは１～１２の整数を示し；ｍ００１は０～１０の整数を示し；ｎ００１は０～１０の整数を示し；ｋ００１は１～４の整数を示す。）
Figure JPOXMLDOC01-appb-C000006
 (In the formula (14a-2), Y 001 is —CO—, —SO 2 —, —SO—, —CONH—, —COO—, — (CF 2 ) h — (where h is 1 to 10). An integer), and at least one structure selected from the group consisting of —C (CF 3 ) 2 —; Z 001 represents a direct bond or — (CH 2 ) g — (where g is 1 to And an at least one structure selected from the group consisting of —C (CH 3 ) 2 —, —O—, —S—, —CO— and —SO 2 —; Ar 001 represents — An aromatic group having a substituent represented by SO 3 H, —O (CH 2 ) p SO 3 H or —O (CF 2 ) p SO 3 H; p represents an integer of 1 to 12; Represents an integer of 0 to 10; n001 represents an integer of 0 to 10; k001 represents an integer of 1 to 4. )
上記式（１４ａ－２）で表されるイオン交換基を有する構造単位の具体例としては、後述の式（４ａ－１３）～（４ａ－２０）で表される構造単位を挙げることができる。 Specific examples of the structural unit having an ion exchange group represented by the above formula (14a-2) include structural units represented by the following formulas (4a-13) to (4a-20).
一方、イオン交換基を有しない構造単位を示す式（１１ｂ）～（１４ｂ）において、Ａｒ１１～Ａｒ１９は、互いに独立に２価の芳香族基を表す。このような２価の芳香族基としては、例えば、１，３－フェニレン基、１，４－フェニレン基等の２価の単環性芳香族炭化水素基；１，３－ナフタレンジイル基、１，４－ナフタレンジイル基、１，５－ナフタレンジイル基、１，６－ナフタレンジイル基、１，７－ナフタレンジイル基、２，６－ナフタレンジイル基、２，７－ナフタレンジイル基等の２価の縮合環系芳香族炭化水素基；ピロール、イミダゾール、ピラゾール、イソオキサゾール、ピリジン、ピラジン、ピリミジン、ピリダジン、インドリジン、イソインドール、３Ｈ－インドール、インドール、１Ｈ－インダゾール、プリン、４Ｈ－キノリジン、キノリン、イソキノリン、フタラジン、ナフチリジン、キノキサリン、キナゾリン、シンノリン、プテリジン、カルバゾール、カルボリン、フェナントリジン、アクリジン、ペリミジン、フェナントロリン、フェナジン、フラザン、フェノキサジン、インドリン、イソインドリン、キヌクリジン、オキサゾール、ベンゾオキサゾール、１，３，５－トリアジン、テトラゾール、テトラジン、トリアゾール、フェナルサジン、ベンゾイミダゾール、およびベンゾトリアゾールからなる群より選ばれる１種の化合物から芳香環上の水素原子を２個取り去って得られる２価のヘテロ芳香族基；および下記式（Ｎ－０１）～（Ｎ－０７）で表される構造からなる群より選ばれる少なくとも１種の構造を含む２価のヘテロ芳香族基等が挙げられる。 On the other hand, in the formulas (11b) to (14b) showing the structural units having no ion exchange group, Ar 11 to Ar 19 each independently represent a divalent aromatic group. Examples of such divalent aromatic groups include divalent monocyclic aromatic hydrocarbon groups such as 1,3-phenylene group and 1,4-phenylene group; 1,3-naphthalenediyl group, 1 , 4-Naphthalenediyl group, 1,5-naphthalenediyl group, 1,6-naphthalenediyl group, 1,7-naphthalenediyl group, 2,6-naphthalenediyl group, 2,7-naphthalenediyl group, etc. Fused ring aromatic hydrocarbon groups of: pyrrole, imidazole, pyrazole, isoxazole, pyridine, pyrazine, pyrimidine, pyridazine, indolizine, isoindole, 3H-indole, indole, 1H-indazole, purine, 4H-quinolidine, quinoline , Isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, carbazole, Ruborine, phenanthridine, acridine, perimidine, phenanthroline, phenazine, furazane, phenoxazine, indoline, isoindoline, quinuclidine, oxazole, benzoxazole, 1,3,5-triazine, tetrazole, tetrazine, triazole, phenalsazine, benzimidazole, And a divalent heteroaromatic group obtained by removing two hydrogen atoms on the aromatic ring from one compound selected from the group consisting of benzotriazole; and the following formulas (N-01) to (N-07): And divalent heteroaromatic groups including at least one structure selected from the group consisting of the structures represented.
Figure JPOXMLDOC01-appb-C000007
Figure JPOXMLDOC01-appb-C000007
式（１１ｂ）～（１４ｂ）におけるＡｒ１１～Ａｒ１９としては、好ましくは、１，３－フェニレン基、１，４－フェニレン基等の２価の単環性芳香族炭化水素基、１，３－ナフタレンジイル基、１，４－ナフタレンジイル基、１，５－ナフタレンジイル基、１，６－ナフタレンジイル基、１，７－ナフタレンジイル基、２，６－ナフタレンジイル基、２，７－ナフタレンジイル基等の２価の縮合環系芳香族炭化水素基であり、より好ましくは２価の単環性芳香族炭化水素基である。 Ar 11 to Ar 19 in the formulas (11b) to (14b) are preferably divalent monocyclic aromatic hydrocarbon groups such as 1,3-phenylene group and 1,4-phenylene group, 1,3 -Naphthalenediyl group, 1,4-naphthalenediyl group, 1,5-naphthalenediyl group, 1,6-naphthalenediyl group, 1,7-naphthalenediyl group, 2,6-naphthalenediyl group, 2,7-naphthalene It is a divalent fused ring aromatic hydrocarbon group such as a diyl group, and more preferably a divalent monocyclic aromatic hydrocarbon group.
また、Ａｒ１１～Ａｒ１９で表される芳香族基の芳香環上の水素原子は、フッ素原子、ホルミル基、シアノ基、置換基を有していてもよい炭素数１～２０のアルキル基、置換基を有していてもよい炭素数１～２０のアルコキシ基、置換基を有していてもよい炭素数６～２０のアリール基、置換基を有していてもよい炭素数６～２０のアリールオキシ基または置換基を有していてもよい炭素数２～２１のアシル基で置換されていてもよい。なお、ここでいう「置換基を有していてもよい」の置換基とは前記イオン交換基を包含するものではない。 The hydrogen atom on the aromatic ring of the aromatic group represented by Ar 11 to Ar 19 is a fluorine atom, a formyl group, a cyano group, an alkyl group having 1 to 20 carbon atoms which may have a substituent, An optionally substituted alkoxy group having 1 to 20 carbon atoms, an optionally substituted aryl group having 6 to 20 carbon atoms, and an optionally substituted carbon group having 6 to 20 carbon atoms. The aryloxy group may be substituted with an acyl group having 2 to 21 carbon atoms which may have a substituent. In addition, the “optionally substituted” substituent here does not include the ion exchange group.
ここで、前述の２価の芳香族基（式（１１ａ）～（１４ａ）におけるＡｒ1～Ａｒ9で表される芳香族基および式（１１ｂ）～（１４ｂ）におけるＡｒ11～Ａｒ19で表される芳香族基）の置換基を以下に例示する。 Here, the divalent aromatic groups (the aromatic groups represented by Ar 1 to Ar 9 in the formulas (11a) to (14a) and the Ar 11 to Ar 19 in the formulas (11b) to (14b) are represented. Examples of the substituent of the aromatic group) are as follows.
置換基を有していてもよい炭素数１～２０のアルキル基としては、例えば、メチル基、エチル基、ｎ－プロピル基、イソプロピル基、ｎ－ブチル基、ｓｅｃ－ブチル基、イソブチル基、ｎ－ペンチル基、２，２－ジメチルプロピル基、シクロペンチル基、ｎ－ヘキシル基、シクロヘキシル基、２－メチルペンチル基、２－エチルヘキシル基、ノニル基、ドデシル基、ヘキサデシル基、オクタデシル基、イコシル基等の炭素数１～２０のアルキル基；およびこれらの基にフッ素原子、ヒドロキシル基、ニトリル基、アミノ基、メトキシ基、エトキシ基、イソプロピルオキシ基、フェニル基、ナフチル基、フェノキシ基、ナフチルオキシ基等が置換され、その総炭素数が２０以下であるアルキル基が挙げられる。 Examples of the optionally substituted alkyl group having 1 to 20 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl group, n -Pentyl group, 2,2-dimethylpropyl group, cyclopentyl group, n-hexyl group, cyclohexyl group, 2-methylpentyl group, 2-ethylhexyl group, nonyl group, dodecyl group, hexadecyl group, octadecyl group, icosyl group, etc. Alkyl groups having 1 to 20 carbon atoms; and these groups include fluorine atom, hydroxyl group, nitrile group, amino group, methoxy group, ethoxy group, isopropyloxy group, phenyl group, naphthyl group, phenoxy group, naphthyloxy group, etc. Examples thereof include an alkyl group which is substituted and has a total carbon number of 20 or less.
置換基を有していてもよい炭素数１～２０のアルコキシ基としては、例えば、メトキシ基、エトキシ基、ｎ－プロピルオキシ基、イソプロピルオキシ基、ｎ－ブチルオキシ基、ｓｅｃ－ブチルオキシ基、ｔｅｒｔ－ブチルオキシ基、イソブチルオキシ基、ｎ－ペンチルオキシ基、２，２－ジメチルプロピルオキシ基、シクロペンチルオキシ基、ｎ－ヘキシルオキシ基、シクロヘキシルオキシ基、２－メチルペンチルオキシ基、２－エチルヘキシルオキシ基、ドデシルオキシ基、ヘキサデシルオキシ基、イコシルオキシ基等の炭素数１～２０のアルコキシ基；およびこれらの基にフッ素原子、ヒドロキシル基、ニトリル基、アミノ基、メトキシ基、エトキシ基、イソプロピルオキシ基、フェニル基、ナフチル基、フェノキシ基、ナフチルオキシ基等が置換され、その総炭素数が２０以下であるアルコキシ基が挙げられる。 Examples of the optionally substituted alkoxy group having 1 to 20 carbon atoms include methoxy group, ethoxy group, n-propyloxy group, isopropyloxy group, n-butyloxy group, sec-butyloxy group, tert- Butyloxy, isobutyloxy, n-pentyloxy, 2,2-dimethylpropyloxy, cyclopentyloxy, n-hexyloxy, cyclohexyloxy, 2-methylpentyloxy, 2-ethylhexyloxy, dodecyl An alkoxy group having 1 to 20 carbon atoms such as an oxy group, a hexadecyloxy group, an icosyloxy group; and these groups include a fluorine atom, a hydroxyl group, a nitrile group, an amino group, a methoxy group, an ethoxy group, an isopropyloxy group, and a phenyl group. , Naphthyl group, phenoxy group, naphthyloxy Etc. is replaced, the total carbon number and an alkoxy group having 20 or less.
置換基を有していてもよい炭素数６～２０のアリール基としては、例えば、フェニル基、ナフチル基、フェナントレニル基、アントラセニル基等のアリール基；およびこれらの基にフッ素原子、ヒドロキシル基、ニトリル基、アミノ基、メトキシ基、エトキシ基、イソプロピルオキシ基、フェニル基、ナフチル基、フェノキシ基、ナフチルオキシ基等が置換され、その総炭素数が２０以下であるアリール基が挙げられる。 Examples of the aryl group having 6 to 20 carbon atoms which may have a substituent include aryl groups such as a phenyl group, a naphthyl group, a phenanthrenyl group, and an anthracenyl group; and these groups include a fluorine atom, a hydroxyl group, and a nitrile. Group, amino group, methoxy group, ethoxy group, isopropyloxy group, phenyl group, naphthyl group, phenoxy group, naphthyloxy group and the like are substituted, and aryl groups having a total carbon number of 20 or less can be mentioned.
置換基を有していてもよい炭素数６～２０のアリールオキシ基としては、例えば、フェノキシ基、ナフチルオキシ基、フェナントレニルオキシ基、アントラセニルオキシ基等のアリールオキシ基；およびこれらの基にフッ素原子、ヒドロキシル基、ニトリル基、アミノ基、メトキシ基、エトキシ基、イソプロピルオキシ基、フェニル基、ナフチル基、フェノキシ基、ナフチルオキシ基等が置換され、その総炭素数が２０以下であるアリールオキシ基が挙げられる。 Examples of the aryloxy group having 6 to 20 carbon atoms which may have a substituent include aryloxy groups such as a phenoxy group, a naphthyloxy group, a phenanthrenyloxy group, and an anthracenyloxy group; Are substituted with fluorine atom, hydroxyl group, nitrile group, amino group, methoxy group, ethoxy group, isopropyloxy group, phenyl group, naphthyl group, phenoxy group, naphthyloxy group, etc. A certain aryloxy group is mentioned.
置換基を有していてもよい炭素数２～２１のアシル基としては、例えば、アセチル基、プロピオニル基、ブチリル基、イソブチリル基、ピバロイル基、ベンゾイル基、１－ナフトイル基、２－ナフトイル基等の炭素数２～２０のアシル基；およびこれらの基にフッ素原子、ヒドロキシル基、ニトリル基、アミノ基、メトキシ基、エトキシ基、イソプロピルオキシ基、フェニル基、ナフチル基、フェノキシ基、ナフチルオキシ基等が置換され、その総炭素数が２１以下であるアシル基が挙げられる。 Examples of the optionally substituted acyl group having 2 to 21 carbon atoms include acetyl group, propionyl group, butyryl group, isobutyryl group, pivaloyl group, benzoyl group, 1-naphthoyl group, and 2-naphthoyl group. An acyl group having 2 to 20 carbon atoms; and fluorine atom, hydroxyl group, nitrile group, amino group, methoxy group, ethoxy group, isopropyloxy group, phenyl group, naphthyl group, phenoxy group, naphthyloxy group, etc. And an acyl group having a total carbon number of 21 or less.
前記置換基は、フェニル基、ナフチル基、フェナントレニル基、アントラセニル基等のアリール基；フェノキシ基、ナフチルオキシ基、フェナントレニルオキシ基、アントラセニルオキシ基等のアリールオキシ基；ベンゾイル基、１－ナフトイル基、２－ナフトイル基等の芳香環を有するアシル基等の芳香環を有する置換基であると、ポリマーの耐熱性が良好となる傾向があり、より実用的な燃料電池用部材が得られるため好ましい。 The substituent is an aryl group such as a phenyl group, a naphthyl group, a phenanthrenyl group or an anthracenyl group; an aryloxy group such as a phenoxy group, a naphthyloxy group, a phenanthrenyloxy group or an anthracenyloxy group; a benzoyl group, 1 -A substituent having an aromatic ring such as an acyl group having an aromatic ring such as a naphthoyl group or a 2-naphthoyl group tends to improve the heat resistance of the polymer, and a more practical fuel cell member can be obtained. Therefore, it is preferable.
芳香環を有するアシル基を置換基として有する重合体を含む高分子電解質においては、前記アシル基を有する２つの構造単位が隣接し、前記２つの構造単位にあるアシル基同士が結合したり、アシル基同士が結合した後に転位反応を生じたりすることにより、構造が変化する場合がある。また、このような構造変化が生じたか否かは、例えば１３Ｃ－核磁気共鳴スペクトルの測定により確認することができる。 In a polyelectrolyte including a polymer having an acyl group having an aromatic ring as a substituent, two structural units having the acyl group are adjacent to each other, and the acyl groups in the two structural units are bonded to each other. The structure may change by causing a rearrangement reaction after the groups are bonded to each other. Whether or not such a structural change has occurred can be confirmed, for example, by measuring a 13 C-nuclear magnetic resonance spectrum.
なお、本発明においての炭化水素系高分子電解質の好ましい要素の一つとして、この高分子電解質を構成する元素質量含有比で表してハロゲン原子が１５質量％以下である高分子電解質であることが挙げられる。かかる炭化水素系高分子電解質は、前記のフッ素系高分子電解質と比較して安価であるという利点を有するため、より好ましい、特に好適な炭化水素系高分子電解質とは実質的にハロゲン原子を含有していない炭化水素系高分子電解質であり、このような炭化水素系高分子電解質は燃料電池の作動時に、ハロゲン化水素を発生して、他の部材を腐食させたりする恐れがない。 One of the preferable elements of the hydrocarbon-based polymer electrolyte in the present invention is a polymer electrolyte having a halogen atom content of 15% by mass or less in terms of the mass content ratio of elements constituting the polymer electrolyte. Can be mentioned. Such hydrocarbon polymer electrolytes have the advantage of being inexpensive compared to the fluorine polymer electrolytes described above, and therefore more preferred, particularly preferred hydrocarbon polymer electrolytes substantially contain halogen atoms. This hydrocarbon polymer electrolyte does not generate hydrogen halide during the operation of the fuel cell and does not corrode other members.
前記炭化水素系高分子電解質は、イオン交換基を有する構造単位、および、イオン交換基を有しない構造単位を有し、イオン交換基を有する構造単位が密な相が膜厚方向に連続相を形成できれば、よりプロトン伝導性に優れる高分子電解質膜が得られるといった利点があるので好ましい。 The hydrocarbon-based polymer electrolyte includes a structural unit having an ion exchange group and a structural unit not having an ion exchange group, and a dense phase of the structural unit having an ion exchange group forms a continuous phase in the film thickness direction. If it can be formed, it is preferable because there is an advantage that a polymer electrolyte membrane having more excellent proton conductivity can be obtained.
本発明において、好適な高分子電解質は、前記式（１１ａ）～（１４ａ）で表される構造単位からなる、イオン交換基を有する構造単位と、前記式（１１ｂ）～（１４ｂ）で表される構造単位からなる、イオン交換基を有しない構造単位とを有する高分子電解質である。このような高分子電解質は、イオン交換基を有する構造単位と、イオン交換基を有しない構造単位と、のそれぞれに対応するモノマーまたはオリゴマーを出発物質とする共重合体として得ることができる。さらに好適なイオン交換基を有する構造単位と、イオン交換基を有しない構造単位との組み合わせとしては、下記の表１の＜Ａ＞～＜Ｍ＞に示す組み合わせを挙げることができる。 In the present invention, suitable polymer electrolytes are represented by the structural units having an ion exchange group composed of the structural units represented by the formulas (11a) to (14a) and the formulas (11b) to (14b). And a structural unit having no ion-exchange group. Such a polymer electrolyte can be obtained as a copolymer starting from monomers or oligomers corresponding to a structural unit having an ion exchange group and a structural unit having no ion exchange group. Further, examples of the combination of a structural unit having an ion exchange group and a structural unit having no ion exchange group include the combinations shown in <A> to <M> in Table 1 below.
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000008
本発明において好適に用いられる高分子電解質の構造としては、更に好ましくは、＜Ｂ＞、＜Ｃ＞、＜Ｄ＞、＜Ｇ＞、＜Ｈ＞、＜Ｉ＞、＜Ｊ＞、＜Ｌ＞、または＜Ｍ＞であり；より更に好ましくは＜Ｇ＞、＜Ｈ＞、＜Ｌ＞または＜Ｍ＞であり；特に好ましくは＜Ｇ＞、＜Ｈ＞、または＜Ｌ＞である。 The structure of the polymer electrolyte preferably used in the present invention is more preferably <B>, <C>, <D>, <G>, <H>, <I>, <J>, <L>. Or <M>; even more preferably <G>, <H>, <L> or <M>; and particularly preferably <G>, <H> or <L>.
好適な共重合体の例として、以下に示すイオン交換基を有する構造単位の群から選ばれる１種または２種以上の構造単位と、以下に示すイオン交換基を有しない構造単位の群から選ばれる１種または２種以上の構造単位と、からなる共重合体を挙げることができる。なお、イオン交換基を有する繰り返し単位におけるイオン交換基は、好適なスルホ基により例示している。もちろん、スルホ基に代えて上述のイオン交換基のいずれかを採用してもよい。 Examples of suitable copolymers include one or more structural units selected from the group of structural units having ion exchange groups shown below, and a group of structural units having no ion exchange groups shown below. And a copolymer composed of one or more structural units. In addition, the ion exchange group in the repeating unit which has an ion exchange group is illustrated by the suitable sulfo group. Of course, any of the above-described ion exchange groups may be employed instead of the sulfo group.
また、これら構造単位同士は直接結合している形態でもよく、適当な原子または原子団で連結している形態でもよい。ここでいう構造単位同士を結合する原子または原子団の典型的な例としては、２価の芳香族基、酸素原子、硫黄原子、カルボニル基、スルホニル基またはこれらを組み合わせてなる２価の基を挙げることができる。 In addition, these structural units may be directly bonded to each other, or may be connected to each other with an appropriate atom or atomic group. As a typical example of an atom or an atomic group for bonding structural units here, a divalent aromatic group, an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or a divalent group formed by combining these is used. Can be mentioned.
（イオン交換基を有する構造単位） (Structural unit having an ion exchange group)
Figure JPOXMLDOC01-appb-C000009
Figure JPOXMLDOC01-appb-C000009
Figure JPOXMLDOC01-appb-C000010
Figure JPOXMLDOC01-appb-C000010
（イオン交換基を有しない構造単位） (Structural unit without ion exchange group)
Figure JPOXMLDOC01-appb-C000011
Figure JPOXMLDOC01-appb-C000011
Figure JPOXMLDOC01-appb-C000012
Figure JPOXMLDOC01-appb-C000012
Figure JPOXMLDOC01-appb-C000013
 （式（４ｂ－１５）～（４ｂ－３２）中、ｒ０００は０または１以上の整数を示し；ｒ０００は、好ましくは１００以下であり、 より好ましくは１以上８０以下である。）
Figure JPOXMLDOC01-appb-C000013
 (In the formulas (4b-15) to (4b-32), r000 represents 0 or an integer of 1 or more; r000 is preferably 100 or less, more preferably 1 or more and 80 or less.)
前記例示の中でも、イオン交換基を有する構造単位を表す式としては、式（４ａ－１）、（４ａ－２）、（４ａ－３）、（４ａ－４）、（４ａ－５）、（４ａ－６）、（４ａ－７）、（４ａ－８）、（４ａ－９）、（４ａ－１０）、（４ａ－１１）、および（４ａ－１２）からなる群から選ばれる１種以上の構造単位が好ましい。同様に、式（４ａ－１０）、（４ａ－１１）、および（４ａ－１２）からなる群から選ばれる１種以上の構造単位がより好ましく、式（４ａ－１１）または（４ａ－１２）が特に好ましい。 Among the examples, the formulas representing the structural unit having an ion exchange group include the formulas (4a-1), (4a-2), (4a-3), (4a-4), (4a-5), ( 1a or more selected from the group consisting of 4a-6), (4a-7), (4a-8), (4a-9), (4a-10), (4a-11), and (4a-12) The structural unit is preferred. Similarly, one or more structural units selected from the group consisting of formulas (4a-10), (4a-11), and (4a-12) are more preferred, and formula (4a-11) or (4a-12) Is particularly preferred.
このような構造単位を含むセグメントを有する高分子電解質、特に、このような構造単位を繰り返し単位として含むセグメント（イオン交換基を有するセグメント）を有する高分子電解質は、このセグメントがポリアリーレン構造となるために化学的安定性も比較的良好となる傾向がある。 A polymer electrolyte having a segment containing such a structural unit, particularly a polymer electrolyte having a segment containing such a structural unit as a repeating unit (segment having an ion exchange group) has a polyarylene structure. Therefore, the chemical stability tends to be relatively good.
また、イオン交換基を有しない構造単位を表す式としては、式（４ｂ－１）、（４ｂ－２）、（４ｂ－３）、（４ｂ－４）、（４ｂ－５）、（４ｂ－６）、（４ｂ－７）、（４ｂ－８）、（４ｂ－９）、（４ｂ－１０）、（４ｂ－１１）、（４ｂ－１２）、（４ｂ－１３）、および（４ｂ－１４）からなる群から選ばれる１種以上の構造単位が好ましい。同様に、式（４ｂ－２）、（４ｂ－３）、（４ｂ－１０）、（４ｂ－１３）、および（４ｂ－１４）からなる群から選ばれる１種以上の構造単位がより好ましく；式（４ｂ－２）、（４ｂ－３）、および（４ｂ－１４）からなる群から選ばれる１種以上の構造単位が特に好ましい。 The formulas representing the structural unit having no ion exchange group include formulas (4b-1), (4b-2), (4b-3), (4b-4), (4b-5), (4b- 6), (4b-7), (4b-8), (4b-9), (4b-10), (4b-11), (4b-12), (4b-13), and (4b-14) And one or more structural units selected from the group consisting of Similarly, one or more structural units selected from the group consisting of formulas (4b-2), (4b-3), (4b-10), (4b-13), and (4b-14) are more preferred; One or more structural units selected from the group consisting of formulas (4b-2), (4b-3), and (4b-14) are particularly preferred.
本発明に係る高分子電解質は、イオン交換基を有する構造単位と、イオン交換基を有しない構造単位とを有する高分子電解質であり、この２種の構造単位の共重合様式は、ランダム共重合、交互共重合、ブロック共重合、またはグラフト共重合の何れでもよく、これらの共重合様式の組み合わせでもよい。好ましくは、ランダム共重合、ブロック共重合、グラフト共重合であり；より好ましくは、ランダム共重合、ブロック共重合であり；特に好ましくはブロック共重合である。 The polymer electrolyte according to the present invention is a polymer electrolyte having a structural unit having an ion exchange group and a structural unit not having an ion exchange group, and the copolymerization mode of these two structural units is random copolymerization. , Alternating copolymerization, block copolymerization, or graft copolymerization, or a combination of these copolymerization modes. Preferred are random copolymerization, block copolymerization, and graft copolymerization; more preferred are random copolymerization and block copolymerization; and particularly preferred is block copolymerization.
ブロック共重合体としては、主としてイオン交換基を有する構造単位からなるセグメント（イオン交換基を有するセグメント）および、主としてイオン交換基を有しない構造単位からなるセグメント（すなわち、イオン交換基を実質的に有しないセグメント）とを有する共重合体が好ましい。このようなブロック共重合体では、イオン交換基を有するセグメントが密な相が膜厚方向に連続相を形成することで、よりプロトン伝導性に優れる高分子電解質膜が得られるといった利点がある。また、好適なイオン交換基を有するセグメントを構成する構造単位とイオン交換基を実質的に有しないセグメントを構成する構造単位の組み合わせとしては、下記の表２の＜Ａ＞～＜Ｍ＞に示すセグメントの組み合わせを挙げることができる。 As the block copolymer, a segment mainly composed of a structural unit having an ion exchange group (segment having an ion exchange group) and a segment mainly composed of a structural unit not having an ion exchange group (that is, substantially having an ion exchange group) And a copolymer having a segment not included). Such a block copolymer has an advantage that a polymer electrolyte membrane having more excellent proton conductivity can be obtained by forming a continuous phase in the film thickness direction with a dense phase having segments having ion exchange groups. Further, combinations of structural units constituting a segment having a suitable ion exchange group and structural units constituting a segment having substantially no ion exchange group are shown in <A> to <M> in Table 2 below. A combination of segments can be mentioned.
Figure JPOXMLDOC01-appb-T000014
Figure JPOXMLDOC01-appb-T000014
更に好ましくは、＜Ｂ＞、＜Ｃ＞、＜Ｄ＞、＜Ｇ＞、＜Ｈ＞、＜Ｉ＞、＜Ｊ＞、＜Ｌ＞、または＜Ｍ＞であり；より更に好ましくは＜Ｇ＞、＜Ｈ＞、＜Ｌ＞または＜Ｍ＞であり；＜Ｇ＞、＜Ｈ＞、または＜Ｌ＞が特に好ましい。 More preferably <B>, <C>, <D>, <G>, <H>, <I>, <J>, <L>, or <M>; even more preferably <G> , <H>, <L> or <M>; <G>, <H> or <L> is particularly preferred.
前記例示の中でも、イオン交換基を有するセグメントを構成する繰り返し単位に用いられる構造単位を表す式としては式（４ａ－１）、（４ａ－２）、（４ａ－３）、（４ａ－４）、（４ａ－５）、（４ａ－６）、（４ａ－７）、（４ａ－８）、（４ａ－９）、（４ａ－１０）、（４ａ－１１）および（４ａ－１２）からなる群から選ばれる１種以上の構造単位が好ましく；式（４ａ－１０）、（４ａ－１１）、および（４ａ－１２）からなる群から選ばれる１種以上の構造単位がより好ましく；式（４ａ－１１）または（４ａ－１２）が特に好ましい。 Among the examples, formulas (4a-1), (4a-2), (4a-3), (4a-4) represent the structural units used for the repeating units constituting the segment having an ion exchange group. , (4a-5), (4a-6), (4a-7), (4a-8), (4a-9), (4a-10), (4a-11) and (4a-12) One or more structural units selected from the group are preferred; one or more structural units selected from the group consisting of the formulas (4a-10), (4a-11), and (4a-12) are more preferred; 4a-11) or (4a-12) is particularly preferred.
本発明に係る上記ブロック共重合体の好ましい形態の一つとして、イオン交換基を有するセグメントの主鎖が、実質的に複数の芳香環が直接連結してなるポリアリーレン構造を有することがあげられる。そのようなセグメントの構造単位として、好ましくは前述の式（４ａ－１０）、（４ａ－１１）、（４ａ－１２）、（４ａ－１３）、（４ａ－１４）、（４ａ－１５）、（４ａ－１６）、（４ａ－１７）、（４ａ－１８）、（４ａ－１９）および（４ａ－２０）からなる群から選ばれる１種以上の構造単位が好ましく、式（４ａ－１０）、（４ａ－１１）および（４ａ－１２）からなる群から選ばれる１種以上の構造単位がより好ましく、式（４ａ－１１）または（４ａ－１２）が特に好ましい。 One preferred form of the block copolymer according to the present invention is that the main chain of the segment having an ion exchange group has a polyarylene structure formed by substantially directly connecting a plurality of aromatic rings. . As the structural unit of such a segment, preferably the above formulas (4a-10), (4a-11), (4a-12), (4a-13), (4a-14), (4a-15), One or more structural units selected from the group consisting of (4a-16), (4a-17), (4a-18), (4a-19) and (4a-20) are preferred, and are represented by the formula (4a-10) , One or more structural units selected from the group consisting of (4a-11) and (4a-12) are more preferred, and formula (4a-11) or (4a-12) is particularly preferred.
このような構造単位からなる繰り返し単位を含むセグメント（すなわち、イオン交換基を有するセグメント）を有する高分子電解質、特に、このような繰り返し単位からなるセグメントを有する高分子電解質は、優れたイオン伝導性を発現できるものであり、このセグメントがポリアリーレン構造となるために化学的安定性も比較的良好となる傾向がある。 A polymer electrolyte having a segment including a repeating unit composed of such a structural unit (that is, a segment having an ion exchange group), in particular, a polymer electrolyte having a segment composed of such a repeating unit has excellent ion conductivity. Since this segment has a polyarylene structure, chemical stability tends to be relatively good.
ここで「ポリアリーレン構造」とは、主鎖を構成している芳香環同士が実質的に直接結合で結合されている形態であり、具体的には、前記芳香環同士の結合の総数を１００％としたとき、直接結合の割合が８０％以上の構造であると好ましく、９０％以上の構造であるとより好ましく、９５％以上の構造であると更に好ましい。なお、直接結合で結合されている形態以外の形態とは、芳香環同士が２価の原子または２価の原子団を介して結合している形態である。 Here, the “polyarylene structure” is a form in which the aromatic rings constituting the main chain are substantially directly bonded to each other. Specifically, the total number of bonds between the aromatic rings is 100. %, The direct bond ratio is preferably 80% or more, more preferably 90% or more, and still more preferably 95% or more. In addition, forms other than the form couple | bonded by the direct bond are forms in which aromatic rings are couple | bonded through a bivalent atom or a bivalent atomic group.
イオン交換基を有しないセグメントを構成する繰り返し単位に用いられる構造単位を表す式としては、式（４ｂ－１）、（４ｂ－２）、（４ｂ－３）、（４ｂ－４）、（４ｂ－５）、（４ｂ－６）、（４ｂ－７）、（４ｂ－８）、（４ｂ－９）、（４ｂ－１０）、（４ｂ－１１）、（４ｂ－１２）、（４ｂ－１３）および（４ｂ－１４）からなる群から選ばれる１種以上の構造単位が好ましく；式（４ｂ－２）、（４ｂ－３）、（４ｂ－９）、（４ｂ－１０）、（４ｂ－１３）および（４ｂ－１４）からなる群から選ばれる１種以上の構造単位がより好ましく；式（４ｂ－２）、（４ｂ－３）、（４ｂ－１３）および（４ｂ－１４）からなる群から選ばれる１種以上の構造単位がよりさらに好ましく；式（４ｂ－２）、（４ｂ－３）および（４ｂ－１４）からなる群から選ばれる１種以上の構造単位が特に好ましい。 The formulas representing the structural units used for the repeating units constituting the segment having no ion exchange group include the formulas (4b-1), (4b-2), (4b-3), (4b-4), (4b -5), (4b-6), (4b-7), (4b-8), (4b-9), (4b-10), (4b-11), (4b-12), (4b-13) ) And (4b-14) are preferred; one or more structural units selected from the group consisting of: (4b-2), (4b-3), (4b-9), (4b-10), (4b- More preferred is one or more structural units selected from the group consisting of 13) and (4b-14); consisting of formulas (4b-2), (4b-3), (4b-13) and (4b-14) Even more preferred are one or more structural units selected from the group; formulas (4b-2), (4b-3) and ( b-14) 1 or more structural units selected from the group consisting of especially preferred.
また、イオン交換基を有するセグメントとイオン交換基を実質的に有しないセグメントとは、直接結合している形態でもよく、適当な原子または原子団で連結している形態でもよい。ここでいうセグメント同士を結合する原子または原子団の典型的な例としては、２価の芳香族基、酸素原子、硫黄原子、カルボニル基、スルホニル基またはこれらを組み合わせてなる２価の基を挙げることができる。　　　　　　　
前記２価の芳香族基としては、例えば、式（１１ａ）～（１４ａ）におけるＡｒ１～Ａｒ９と同様の２価の芳香族基が挙げられる。 In addition, the segment having an ion exchange group and the segment having substantially no ion exchange group may be directly bonded or may be connected by an appropriate atom or atomic group. As typical examples of the atoms or atomic groups connecting the segments, a divalent aromatic group, an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or a divalent group formed by combining these is given. be able to.
Examples of the divalent aromatic group include the same divalent aromatic groups as Ar 1 to Ar 9 in formulas (11a) to (14a).
好適なブロック共重合体の例として、上記に示すイオン交換基を有する構造単位の群から選ばれる１種または２種以上の構造単位を含むセグメント（すなわち、イオン交換基を有するセグメント）と、主として上記に示すイオン交換基を有しない構造単位の群から選ばれる１種または２種以上の構造単位を含むセグメント（すなわち、イオン交換基を実質的に有しないセグメント）と、からなるブロック共重合体を挙げることができる。 Examples of suitable block copolymers include a segment containing one or more structural units selected from the group of structural units having an ion exchange group shown above (ie, a segment having an ion exchange group), and A block copolymer comprising a segment containing one or more structural units selected from the group of structural units having no ion exchange group shown above (that is, a segment having substantially no ion exchange group). Can be mentioned.
ここで、「イオン交換基を有するセグメント」とは、イオン交換基が、前記セグメントを構成する構造単位１個あたりで平均０．５個以上含まれているセグメントであることを意味し、構造単位１個あたりでイオン交換基が平均１．０個以上含まれているとより好ましい。 Here, the “segment having an ion exchange group” means that the ion exchange group is a segment containing an average of 0.5 or more per structural unit constituting the segment. It is more preferable that one or more ion exchange groups are contained on an average per unit.
一方、「イオン交換基を実質的に有しないセグメント」とは、イオン交換基が、前記セグメントを構成する構造単位１個あたりで平均０．５個未満であるセグメントであることを意味し、構造単位１個あたりでイオン交換基が平均０．１個以下であるとより好ましく；平均０．０５個以下であるとさらに好ましい。 On the other hand, the “segment substantially having no ion exchange group” means that the ion exchange group is a segment having an average of less than 0.5 per structural unit constituting the segment, More preferably, the number of ion exchange groups per unit is 0.1 or less on average; more preferably 0.05 or less on average.
典型的には、イオン交換基を有するセグメントとイオン交換基を実質的に有しないセグメントとが、直接結合で結合されているか、適当な原子または原子団で結合された形態のブロック共重合体である。 Typically, a block copolymer in a form in which a segment having an ion exchange group and a segment having substantially no ion exchange group are bonded by a direct bond or bonded by an appropriate atom or atomic group. is there.
上記式（１１ａ）～（１４ａ）で表される構造単位から選ばれる１種以上の構造単位からなるセグメントの重合度は２以上であり、３以上が好ましく；５以上がより好ましく；１０以上が更に好ましい。また、かかるセグメントの重合度は１０００以下が好ましく；５００以下が好ましい。この重合度が２以上、好ましくは５以上であれば、燃料電池用の高分子電解質として、十分なプロトン伝導度を発現し、この重合度が１０００以下であれば、製造がより容易である利点がある。
即ち、かかるセグメントの重合度は、２以上、１０００以下が好ましく；５以上、１０００以下がよりに好ましく；５以上、５００以下が更に好ましく；１０以上、５００以下が最も好ましい。 The degree of polymerization of the segment composed of one or more structural units selected from the structural units represented by the above formulas (11a) to (14a) is 2 or more, preferably 3 or more; more preferably 5 or more; Further preferred. In addition, the polymerization degree of the segment is preferably 1000 or less; preferably 500 or less. If the degree of polymerization is 2 or more, preferably 5 or more, sufficient proton conductivity is expressed as a polymer electrolyte for a fuel cell, and if the degree of polymerization is 1000 or less, the advantage is that manufacture is easier. There is.
That is, the polymerization degree of the segment is preferably 2 or more and 1000 or less; more preferably 5 or more and 1000 or less; more preferably 5 or more and 500 or less; and most preferably 10 or more and 500 or less.
また、式（１１ｂ）～（１４ｂ）で表される構造単位から選ばれる１種以上の構造単位からなるセグメントの重合度は１以上であり、２以上が好ましく；３以上がより好ましい。また、かかるセグメントの重合度は１００以下が好ましく；９０以下がより好ましく；８０以下が更に好ましい。重合度がこのような範囲内であれば、燃料電池用の高分子電解質として、十分な機械強度を有し、製造が容易であるので好ましい。
即ち、かかるセグメントの重合度は、１以上、１００以下が好ましく；２以上、９０以下がより好ましく；３以上、８０以下が更に好ましい。 Further, the degree of polymerization of a segment composed of one or more structural units selected from the structural units represented by formulas (11b) to (14b) is 1 or more, preferably 2 or more; more preferably 3 or more. Further, the polymerization degree of the segment is preferably 100 or less; more preferably 90 or less; and still more preferably 80 or less. If the degree of polymerization is within such a range, it is preferable as a polymer electrolyte for a fuel cell because it has sufficient mechanical strength and is easy to produce.
That is, the polymerization degree of the segment is preferably 1 or more and 100 or less; more preferably 2 or more and 90 or less; and further preferably 3 or more and 80 or less.
また、本発明で用いられる炭化水素系高分子電解質の分子量は、ポリスチレン換算の数平均分子量で表して、５０００～１００００００であることが好ましく；１００００～８０００００であることがより好ましく；１００００～６０００００であることがより更に好ましく；中でも１５０００～４０００００であることが特に好ましい。このような範囲の分子量の高分子電解質を用いることにより、後述の方法にて作成される高分子電解質膜は、その膜の形状を安定的に維持できる傾向がある。前記数平均分子量は、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）により測定される。 Further, the molecular weight of the hydrocarbon-based polymer electrolyte used in the present invention is preferably 5000 to 1,000,000, more preferably 10,000 to 800,000, more preferably 10,000 to 600,000 in terms of polystyrene-reduced number average molecular weight. More preferably, it is more preferably 15,000 to 400,000. By using a polymer electrolyte having a molecular weight in such a range, a polymer electrolyte membrane prepared by a method described later tends to stably maintain the shape of the membrane. The number average molecular weight is measured by gel permeation chromatography (GPC).
（フッ素系高分子電解質）
また、本発明の一実施形態における高分子電解質膜に用いることができるフッ素系高分子電解質としては、通常知られたフッ素系高分子電解質を例示することができる。例えば、上述の炭化水素系高分子電解質中の水素原子がフッ素原子で置換されたフッ素系高分子電解質を用いることができる。具体的には、パーフルオロアルキルスルホン酸ポリマー、またはパーフルオロカルボン酸ポリマーが挙げられる。他にも、Ｎａｆｉｏｎ（デュポン社登録商標）、旭化成製のＡｃｉｐｌｅｘ（旭化成登録商標）、旭硝子製のＦｌｅｍｉｏｎ（旭硝子登録商標）等のフッ素系高分子電解質や、上述した特開２００３－１１３１３６号公報に記載されているフッ素系高分子電解質等も用いることが可能である。
なお、「フッ素系高分子電解質」とは、当該高分子電解質を構成する元素質量含有比で表してフッ素原子が１５質量％を超える高分子電解質を意味する。 (Fluoropolymer electrolyte)
Moreover, as a fluorine-type polymer electrolyte which can be used for the polymer electrolyte membrane in one Embodiment of this invention, the normally known fluorine-type polymer electrolyte can be illustrated. For example, a fluorine-based polymer electrolyte in which hydrogen atoms in the above-described hydrocarbon-based polymer electrolyte are substituted with fluorine atoms can be used. Specifically, a perfluoroalkyl sulfonic acid polymer or a perfluorocarboxylic acid polymer can be mentioned. In addition, fluorine polymer electrolytes such as Nafion (registered trademark of DuPont), Aciplex (Asahi Kasei registered trademark) manufactured by Asahi Kasei, Flemion (Asahi Glass registered trademark) manufactured by Asahi Glass, and the above-mentioned JP-A No. 2003-113136. The described fluorine-based polymer electrolytes can also be used.
The “fluorine polymer electrolyte” means a polymer electrolyte having a fluorine atom content of more than 15% by mass in terms of a mass content ratio of elements constituting the polymer electrolyte.
＜金属微粒子＞
次に、本発明の一実施態様である高分子電解質膜１２が有する金属微粒子１３Ａについて説明する。金属微粒子１３Ａは、電池稼動時に発生する過酸化物またはこの過酸化物から発生するラジカルを失活させる機能を有するものであり、高分子電解質膜１２の膜内に膜厚方向に濃度勾配を有して分散しているものである。 <Metal fine particles>
Next, the metal fine particles 13A included in the polymer electrolyte membrane 12 according to an embodiment of the present invention will be described. The metal fine particles 13A have a function of deactivating peroxides generated during battery operation or radicals generated from the peroxides, and have a concentration gradient in the film thickness direction in the polymer electrolyte membrane 12. Are distributed.
ここで、「膜厚方向に濃度勾配を有する」とは、金属微粒子１３Ａが高分子電解質膜１２の膜内に一様に分散しているのではなく、膜厚方向に見ると、ある位置では金属微粒子１３Ａの濃度が小さく、またある位置では金属微粒子１３Ａの濃度が大きいというように、存在に偏りがあることを示している。金属微粒子１３Ａが濃度勾配を有して分散していると、金属微粒子１３Ａの濃度が極大値を示すところでは、一様に分散しているよりも実効濃度が高くなり、効果的にラジカルを失活させやすくなる。また、金属微粒子１３Ａが密集することにより、ラジカルに対する活性が高くなる近接効果も期待できる。 Here, “having a concentration gradient in the film thickness direction” means that the metal fine particles 13A are not uniformly dispersed in the polymer electrolyte membrane 12, but at a certain position when viewed in the film thickness direction. This indicates that the existence of the metal fine particles 13A is biased such that the concentration of the metal fine particles 13A is small and the concentration of the metal fine particles 13A is high at a certain position. When the metal fine particles 13A are dispersed with a concentration gradient, where the concentration of the metal fine particles 13A shows the maximum value, the effective concentration becomes higher than that of the uniform dispersion, and the radicals are effectively lost. It becomes easy to make it live. Moreover, the proximity effect that the activity with respect to a radical becomes high can be expected because the metal fine particles 13A are densely packed.
なお、本明細書において「極大値」とは、高分子電解質膜内の膜厚方向における金属微粒子の濃度変化について示した関数が、ある膜厚方向の位置において増加から減少に変わるとき、当該位置における値のことである。 In the present specification, the “maximum value” means that when the function shown for the concentration change of the metal fine particles in the film thickness direction in the polymer electrolyte membrane changes from increase to decrease at a position in the film thickness direction, It is the value at.
金属微粒子１３Ａの濃度は、高分子電解質膜１２の膜表面ではなく、膜内部に極大値を有するとよい。また、金属微粒子１３Ａの濃度の最大値が、高分子電解質膜の膜厚方向の中心よりも前記カソード触媒層側にあることが好ましい。例えば、極大値が高分子電解質膜内のカソード触媒層に接する表面近傍に有することが好ましい。 The concentration of the metal fine particles 13 </ b> A may have a maximum value inside the membrane rather than the membrane surface of the polymer electrolyte membrane 12. Further, it is preferable that the maximum value of the concentration of the metal fine particles 13A is on the cathode catalyst layer side with respect to the center in the film thickness direction of the polymer electrolyte membrane. For example, the maximum value is preferably in the vicinity of the surface in contact with the cathode catalyst layer in the polymer electrolyte membrane.
カソード触媒層１４ｂの近傍では、アノード触媒層１４ａに供給される水素が、アノード触媒層１４ａ側から高分子電解質膜を通過してカソード触媒層１４ｂ側に浸透してしまう（いわゆるクロスリーク、またはクロスオーバー）ことにより、カソード触媒層１４ｂに供給される酸素と反応し、過酸化水素およびヒドロキシラジカルが生じ得る。しかし、カソード触媒層１４ｂ側の表面近傍に金属微粒子１３Ａが多く存在していると、発生するラジカルを効率良く失活させることができるため、高分子電解質膜の劣化（分子量低下、フッ素イオンの溶出量の増大）を抑制することができる。 In the vicinity of the cathode catalyst layer 14b, hydrogen supplied to the anode catalyst layer 14a passes through the polymer electrolyte membrane from the anode catalyst layer 14a side and permeates into the cathode catalyst layer 14b side (so-called cross leak or cross leak). Over), it reacts with oxygen supplied to the cathode catalyst layer 14b, and hydrogen peroxide and hydroxy radicals can be generated. However, if there are many metal fine particles 13A in the vicinity of the surface on the cathode catalyst layer 14b side, the generated radicals can be deactivated efficiently, so that the polymer electrolyte membrane is deteriorated (molecular weight reduction, fluorine ion elution). Increase in amount) can be suppressed.
このような金属微粒子１３Ａの形成材料は、貴金属および貴金属合金からなる群より選ばれる１種以上の金属を含む。前記形成材料は、白金、金、パラジウム、イリジウム、ロジウムおよびルテニウムからなる貴金属群より選ばれる少なくとも１種の貴金属もしくは貴金属合金のいずれか一方、または両方を含むことが好ましく、金、パラジウム、ルテニウム、およびロジウムからなる貴金属群より選ばれる少なくとも１種の金属がより好ましく、パラジウムが特に好ましい。 Such a material for forming the metal fine particles 13A includes one or more metals selected from the group consisting of noble metals and noble metal alloys. The forming material preferably contains at least one kind of noble metal or noble metal alloy selected from the group of noble metals consisting of platinum, gold, palladium, iridium, rhodium and ruthenium, or both, gold, palladium, ruthenium, And at least one metal selected from the noble metal group consisting of rhodium is more preferable, and palladium is particularly preferable.
なお、金属微粒子１３Ａとしては、上記群より選ばれる２種以上の金属を形成材料としてもよい。その場合、金属微粒子１３Ａは、単一の金属からなる金属微粒子１３Ａが混合されていることとしてもよく、複数種の金属の合金を形成材料としていることとしてもよい。 In addition, as metal fine particle 13A, it is good also considering 2 or more types of metals chosen from the said group as a forming material. In that case, the metal fine particles 13A may be a mixture of metal fine particles 13A made of a single metal, or may be an alloy of a plurality of types of metals.
金属微粒子１３Ａの粒子径は、５００ｎｍ以下であることが好ましい。より好ましくは１００ｎｍ以下であり、更に好ましくは５０ｎｍ以下である。また、下限は特に限定はない。金属状態で膜内に存在していればよく、一部がイオン状態で存在していてもよい。図２に示す電子顕微鏡写真では、金属微粒子１３Ａが黒い斑点状に写っているが、黒い斑点がない箇所には撮像した倍率では写らない大きさの微粒子が存在していることがあってもよい。 The particle diameter of the metal fine particles 13A is preferably 500 nm or less. More preferably, it is 100 nm or less, More preferably, it is 50 nm or less. The lower limit is not particularly limited. It may be present in the film in a metal state, and a part may be present in an ionic state. In the electron micrograph shown in FIG. 2, the metal fine particles 13 </ b> A appear as black spots, but there may be fine particles having a size that does not appear at the imaged magnification at locations where there are no black spots. .
電解質膜表面および内部に存在するＰｄ金属の総量は、電解質膜表面および内部に存在するＰｄ金属とＰｄイオンの総量に対して５％以上９５％以下であることが好ましい。好ましくは５％以上８０％以下であり、より好ましくは５％以上６５％以下であり、更に好ましくは５％以上５０％以下である。 The total amount of Pd metal present on and in the electrolyte membrane surface is preferably 5% or more and 95% or less with respect to the total amount of Pd metal and Pd ions present on and inside the electrolyte membrane. Preferably they are 5% or more and 80% or less, More preferably, they are 5% or more and 65% or less, More preferably, they are 5% or more and 50% or less.
＜膜電極接合体の製造方法＞
次に、図３から図５を参照しながら、本発明の一実施態様である高分子電解質膜の製造方法について説明する。 <Method for producing membrane electrode assembly>
Next, a method for producing a polymer electrolyte membrane, which is one embodiment of the present invention, will be described with reference to FIGS.
まず、図３に示すように、上述のような高分子電解質を用い、高分子電解質膜１２の母材１２Ｘを製造する。高分子電解質膜の製造方法としては、通常知られた種々の方法を採用することができるが、本実施形態においては、以下のキャスト製膜法を採用して製造することとして説明する。 First, as shown in FIG. 3, the base material 12X of the polymer electrolyte membrane 12 is manufactured using the polymer electrolyte as described above. As a method for producing the polymer electrolyte membrane, various generally known methods can be adopted, but in the present embodiment, the following description will be made assuming that the following cast film forming method is adopted.
＜キャスト製膜＞
本発明の一実施態様である膜電極接合体に用いることができる母材１２Ｘは、好ましくは、以下の（ｉ）～（ｉｖ）の工程を含むキャスト製膜法を用いて製造される。
　（ｉ）上述のような高分子電解質を、前記高分子電解質を溶解し得る有機溶媒に溶解し、高分子電解質溶液を調製する工程；
　（ｉｉ）前記（ｉ）で得られた高分子電解質溶液を、比較的平滑な表面を有する支持基材上に流延塗工し、前記支持基材上に高分子電解質の流延膜を形成する工程；
　（ｉｉｉ）前記（ｉｉ）で支持基材上に形成された流延膜から、前記有機溶媒を除去して、前記支持基材上に高分子電解質膜を形成する工程；
　（ｉｖ）前記（ｉｉｉ）の工程を行った後、支持基材と高分子電解質膜とを分離する工程 <Cast film formation>
The base material 12X that can be used in the membrane electrode assembly according to an embodiment of the present invention is preferably manufactured by a cast film forming method including the following steps (i) to (iv).
(I) a step of preparing a polymer electrolyte solution by dissolving the polymer electrolyte as described above in an organic solvent capable of dissolving the polymer electrolyte;
(Ii) The polymer electrolyte solution obtained in (i) above is cast-coated on a support substrate having a relatively smooth surface, and a polymer electrolyte cast film is formed on the support substrate. The step of:
(Iii) removing the organic solvent from the cast film formed on the support substrate in (ii) to form a polymer electrolyte membrane on the support substrate;
(Iv) A step of separating the support substrate and the polymer electrolyte membrane after performing the step (iii)
ここで、前記キャスト製膜法に関する各工程（ｉ）～（ｉｖ）に関し順次説明する。 Here, the steps (i) to (iv) relating to the cast film forming method will be sequentially described.
＜工程（ｉ）＞
まず、工程（ｉ）では高分子電解質溶液を調製する。この高分子電解質溶液調製に使用する有機溶媒としては、使用する高分子電解質を溶解し得る有機溶媒が選ばれる。また、高分子電解質に加えて、他の高分子や添加剤などの成分を用いる場合は、これら他の成分も共に溶解し得る有機溶媒が好ましい。
前記有機溶媒は、使用する高分子電解質を溶解し得る溶媒であり、具体的には、この高分子電解質を、２５℃で１重量％以上の濃度で溶解し得る有機溶媒を意味する。好適には、高分子電解質を５～５０重量％の濃度で溶解し得る有機溶媒を用いることが好ましい。 <Process (i)>
First, in step (i), a polymer electrolyte solution is prepared. As the organic solvent used for the preparation of the polymer electrolyte solution, an organic solvent capable of dissolving the polymer electrolyte to be used is selected. In addition to the polymer electrolyte, when other components such as other polymers and additives are used, an organic solvent capable of dissolving these other components is preferable.
The organic solvent is a solvent that can dissolve the polymer electrolyte to be used, and specifically means an organic solvent that can dissolve the polymer electrolyte at a concentration of 1% by weight or more at 25 ° C. Preferably, an organic solvent capable of dissolving the polymer electrolyte at a concentration of 5 to 50% by weight is used.
また、この有機溶媒は、次の工程（ｉｉ）において支持基材上に高分子電解質の流延膜を形成した後に、加熱処理により除去し得る程度の揮発性が必要である。高分子電解質を溶解し得る有機溶媒として沸点が１５０℃以下の有機溶媒のみを用いると、後述する工程（ｉｉｉ）で流延膜から有機溶媒を除去して高分子電解質膜を形成しようとする場合に、形成した高分子電解質膜に凹凸状の外観不良が発生するおそれがある。これは、沸点が１５０℃以下である有機溶媒では、前記流延膜から急激に有機溶媒が揮発してしまうためである。したがって、前記有機溶媒は、１０１．３ｋＰａ（１気圧）における沸点が１５０℃以上である有機溶媒を少なくとも１種含むことが好ましい。 Further, the organic solvent needs to be volatile enough to be removed by heat treatment after forming a cast film of a polymer electrolyte on the support base material in the next step (ii). When only an organic solvent having a boiling point of 150 ° C. or lower is used as an organic solvent capable of dissolving the polymer electrolyte, the polymer electrolyte membrane is formed by removing the organic solvent from the cast film in the step (iii) described later. In addition, the formed polymer electrolyte membrane may have uneven appearance. This is because in an organic solvent having a boiling point of 150 ° C. or lower, the organic solvent suddenly volatilizes from the cast film. Therefore, the organic solvent preferably contains at least one organic solvent having a boiling point of 150 ° C. or higher at 101.3 kPa (1 atm).
高分子電解質溶液の調製に好適な有機溶媒を例示すると、ジメチルホルムアミド（ＤＭＦ）、ジメチルアセトアミド（ＤＭＡｃ）、Ｎ－メチル－２－ピロリドン（ＮＭＰ）、ジメチルスルホキシド（ＤＭＳＯ）、γ-ブチロラクトン（ＧＢＬ）等の非プロトン性極性溶媒；あるいはジクロロメタン、クロロホルム、１，２－ジクロロエタン、クロロベンゼン、ジクロロベンゼン等の塩素系溶媒；メタノール、エタノール、プロパノール等のアルコール類；エチレングリコールモノメチルエーテル、エチレングリコールモノエチルエーテル、プロピレングリコールモノメチルエーテル、プロピレングリコールモノエチルエーテル等のアルキレングリコールモノアルキルエーテルが好適に用いられる。 Examples of organic solvents suitable for the preparation of the polymer electrolyte solution include dimethylformamide (DMF), dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), and γ-butyrolactone (GBL). Aprotic polar solvents such as; or chlorinated solvents such as dichloromethane, chloroform, 1,2-dichloroethane, chlorobenzene and dichlorobenzene; alcohols such as methanol, ethanol and propanol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether; An alkylene glycol monoalkyl ether such as propylene glycol monomethyl ether or propylene glycol monoethyl ether is preferably used.
これらは単独で用いることもできるが、必要に応じて２種以上の有機溶媒を混合して用いることもできる。中でも、非プロトン性極性溶媒を含む有機溶媒が好ましく、実質的に非プロトン性極性溶媒からなる有機溶媒が特に好ましい。ここでいう「実質的に非プロトン性極性溶媒からなる有機溶媒」とは、主としてプロトン性極性溶媒からなる有機溶媒を意味するが、企図せず含有される水分などの存在を排除するものではない。前記非プロトン性極性溶媒は、支持基材に対して親和性が比較的小さく、前記支持基材に非プロトン性極性溶媒が吸収され難いという利点もある。また、上述の好適な高分子電解質であるブロック共重合体の溶解性が高いという点では、前記非プロトン性極性溶媒の中でも、ＤＭＳＯ、ＤＭＦ、ＤＭＡｃ、ＮＭＰ、ＧＢＬまたはこれらから選ばれる２種以上の混合溶媒が好ましい。 These can be used singly, or two or more organic solvents can be mixed and used as necessary. Among these, an organic solvent containing an aprotic polar solvent is preferable, and an organic solvent substantially consisting of an aprotic polar solvent is particularly preferable. As used herein, “an organic solvent substantially composed of an aprotic polar solvent” means an organic solvent mainly composed of a protic polar solvent, but does not exclude the presence of unintentionally contained water or the like. . The aprotic polar solvent has an advantage that the affinity for the supporting substrate is relatively small and the aprotic polar solvent is hardly absorbed by the supporting substrate. Further, in terms of the high solubility of the block copolymer which is the preferred polymer electrolyte described above, among the aprotic polar solvents, DMSO, DMF, DMAc, NMP, GBL or two or more selected from these are used. The mixed solvent is preferable.
＜工程（ｉｉ）＞
次に、工程（ｉｉ）について説明する。図３Ａは、工程（ｉｉ）を示す説明図である。 <Process (ii)>
Next, process (ii) is demonstrated. FIG. 3A is an explanatory diagram showing step (ii).
この工程は、工程（ｉ）で得られた高分子電解質溶液１２Ｓを支持基材Ｐ上に流延塗工し、流延膜１２Ａを形成する工程である。前記流延塗工の方法としては、ローラーコート法、スプレイコート法、カーテンコート法、スロットコート法、またはスクリーン印刷法等の各種手段を用いることができるが、好ましくは、一定間隔の隙間（クリアランス）が設けられたダイと呼ばれる金型により、所定の幅および厚みに賦型する手段が挙げられる。図３Ａでは、ダイ１００から高分子電解質溶液１２Ｓを吐出して流延膜１２Ａを形成することとして示している。 This step is a step of casting the polymer electrolyte solution 12S obtained in the step (i) on the support substrate P to form a casting film 12A. As the casting coating method, various means such as a roller coating method, a spray coating method, a curtain coating method, a slot coating method, or a screen printing method can be used. There is a means for shaping to a predetermined width and thickness by a die called a die provided with). In FIG. 3A, the polymer electrolyte solution 12S is discharged from the die 100 to form the casting film 12A.
このようにして支持基材Ｐ上に形成された流延膜１２Ａは、塗工時に高分子電解質溶液１２Ｓ中の有機溶媒の一部が揮発するために膜の形状を有するものとなる。この際の流延膜１２Ａの膜厚は、３μｍ～５０μｍになるようにしておくことが好ましい。このような膜厚の流延膜１２Ａを得るには、使用する高分子電解質溶液１２Ｓの高分子電解質濃度、塗工装置の塗出量等を適宜調整すればよい。また、前記支持基材Ｐが連続的に走行する基材である場合は、その支持基材Ｐの走行速度等で調節することもできる。 Thus, the casting film 12A formed on the support substrate P has a film shape because a part of the organic solvent in the polymer electrolyte solution 12S is volatilized at the time of coating. At this time, the thickness of the casting film 12A is preferably 3 μm to 50 μm. In order to obtain the casting film 12A having such a film thickness, the polymer electrolyte concentration of the polymer electrolyte solution 12S to be used, the coating amount of the coating apparatus, and the like may be appropriately adjusted. Moreover, when the said support base material P is a base material which drive | works continuously, it can also adjust with the running speed of the support base material P, etc.
工程（ｉｉ）で使用する支持基材Ｐとしては、流延塗工に供する高分子電解質溶液１２Ｓに対して十分な耐久性を有し、後述する工程（ｉｉｉ）での処理条件に対しても耐久性を有する材質からなる基材が選択される。この場合の「耐久性」とは、高分子電解質溶液１２Ｓによって支持基材Ｐ自身が実質的に溶け出さないことや、工程（ｉｉｉ）の処理条件により、支持基材Ｐ自身が膨潤や収縮を起こさず寸法安定性がよいこと等を意味するものである。 As support base material P used at a process (ii), it has sufficient endurance to polymer electrolyte solution 12S used for cast coating, and also with respect to processing conditions in process (iii) mentioned below. A substrate made of a durable material is selected. In this case, “durability” means that the support substrate P itself is not substantially dissolved by the polymer electrolyte solution 12S, and that the support substrate P itself swells and contracts due to the processing conditions of step (iii). This means that it does not occur and has good dimensional stability.
このような支持基材Ｐとしては、たとえばガラス板；ＳＵＳ箔、銅箔等の金属箔；ポリエチレンテレフタレート（ＰＥＴ）フィルム、ポリエチレンナフタレート（ＰＥＮ）フィルム等のプラスチックフィルムを挙げることができる。また、このプラスチックフィルムには、上述したような耐久性を著しく損なわない範囲で、そのフィルム表面に対し、ＵＶ処理、離型処理、エンボス処理等の表面処理を行ってもよい。以下においては、支持基板Ｐがプラスチックフィルムであることとして説明を行う。 Examples of such a supporting substrate P include glass plates; metal foils such as SUS foil and copper foil; plastic films such as polyethylene terephthalate (PET) films and polyethylene naphthalate (PEN) films. Further, this plastic film may be subjected to surface treatment such as UV treatment, mold release treatment, embossing treatment, etc. on the film surface within a range that does not significantly impair the durability as described above. In the following description, it is assumed that the support substrate P is a plastic film.
＜工程（ｉｉｉ）＞
次に、工程（ｉｉｉ）に関し説明する。図３Ｂは工程（ｉｉｉ）を示す説明図である。 <Process (iii)>
Next, process (iii) is demonstrated. FIG. 3B is an explanatory diagram showing step (iii).
この工程は工程（ｉｉ）において支持基材Ｐ上に形成された流延膜１２Ａに含有される有機溶媒Ｓを除去して、前記支持基材Ｐ上に母材１２Ｘを形成する工程である。このような除去には、乾燥または洗浄溶媒による洗浄が推奨される。図３Ｂでは、有機溶媒Ｓが蒸発することにより乾燥し、除去されることとして図示している。このような乾燥と洗浄とを組み合わせて、前記有機溶媒を除去することがより一層好ましく、乾燥と洗浄とを組み合わせる場合には、まず乾燥を行って、支持基材Ｐ上に形成された延膜に含有される有機溶媒Ｓのほとんどを除去した後、洗浄溶媒による洗浄を行うことが特に好ましい。 This step is a step of removing the organic solvent S contained in the casting film 12A formed on the support substrate P in the step (ii) and forming the base material 12X on the support substrate P. For such removal, drying or washing with a washing solvent is recommended. FIG. 3B illustrates that the organic solvent S is dried and removed by evaporation. It is even more preferable to remove the organic solvent by combining such drying and washing. When combining drying and washing, first, drying is performed, and the film formed on the support substrate P It is particularly preferable to carry out washing with a washing solvent after most of the organic solvent S contained in is removed.
ここでは、工程（ｉｉｉ）として好適な方法である乾燥と洗浄とを、この順で実施することについて詳述する。工程（ｉｉ）を経て得られた支持基材Ｐ上に形成された流延膜１２Ａから有機溶媒を乾燥除去するには、加熱、減圧、通風等の処理を採用することができるが、生産性が良好である点と、操作が容易である点で加熱処理が好ましい。この場合、流延膜１２Ａが形成された支持基材Ｐ（以下、場合により「第１の積層フィルム」という）を、直接加熱、温風処理等により加熱処理する。 Here, it will be described in detail that the drying and washing, which are suitable methods as the step (iii), are performed in this order. In order to dry and remove the organic solvent from the cast film 12A formed on the support substrate P obtained through the step (ii), treatment such as heating, decompression, and ventilation can be employed. The heat treatment is preferable in that it is good and the operation is easy. In this case, the support base P (hereinafter referred to as “first laminated film” in some cases) on which the casting film 12A is formed is heat-treated by direct heating, hot air treatment or the like.
流延膜１２Ａ中の高分子電解質を著しく損なわない点で、温風処理が特に好ましい。たとえば、第１の積層フィルムが長尺状であり、かかる長尺状の第１の積層フィルムを連続的に処理する場合は、乾燥炉中に前記第１の積層フィルムを通過させればよい。このときの乾燥炉は、４０℃～１５０℃の範囲、好ましくは５０℃～１４０℃の範囲に温度設定された温風を、第１の積層フィルムの通過方向に対し垂直方向および／または対向方向に沿って送風する。こうすることにより、支持基材Ｐ上にある流延膜１２Ａから有機溶媒Ｓ等の揮発成分が乾燥（蒸発）除去され、支持基材Ｐ上に母材１２Ｘが形成された第２の積層フィルムが形成する。 Hot air treatment is particularly preferable in that the polymer electrolyte in the casting membrane 12A is not significantly impaired. For example, when the first laminated film is long and the long first laminated film is continuously processed, the first laminated film may be passed through a drying furnace. At this time, the drying furnace is configured to apply hot air whose temperature is set in a range of 40 ° C. to 150 ° C., preferably in a range of 50 ° C. to 140 ° C., in a direction perpendicular to the passing direction of the first laminated film and / or in a facing direction. Blow along. Thus, the second laminated film in which the volatile component such as the organic solvent S is dried (evaporated) from the casting film 12A on the support base P and the base material 12X is formed on the support base P. Form.
このようにして得られた第２の積層フィルムの母材１２Ｘ中には、まだ若干量の有機溶媒が含有されているため、この有機溶媒を洗浄溶媒で洗浄する。洗浄溶媒で洗浄することにより、外観等に優れる母材１２Ｘが得られ易い。高分子電解質溶液の調製において好適な有機溶媒である、ＤＭＳＯ、ＤＭＦ、ＤＭＡｃ、ＮＭＰまたはＧＢＬ、あるいはこれらの組合せからなる混合溶媒を使用した場合、洗浄溶媒には純水、特に超純水を使用することが好ましい。 Since the base material 12X of the second laminated film thus obtained still contains a slight amount of organic solvent, this organic solvent is washed with a washing solvent. By cleaning with a cleaning solvent, it is easy to obtain the base material 12X having excellent appearance and the like. When using a mixed solvent consisting of DMSO, DMF, DMAc, NMP, GBL, or a combination thereof, which is a suitable organic solvent in the preparation of the polymer electrolyte solution, pure water, particularly ultrapure water, is used as the cleaning solvent. It is preferable to do.
上述のように、第１の積層フィルムが長尺状であって連続的に走行している場合、乾燥炉を通過して連続的に形成された第２の積層フィルムは、たとえば洗浄溶媒を充填した洗浄槽中を通過させることにより洗浄することができる。また、乾燥炉を通過して連続的に形成された第２の積層フィルムを適当な巻芯に巻き取って巻取り体として後、この巻取り体を、洗浄処理を担う洗浄装置へと移し変え、移し変えた巻取り体から第２の積層フィルムを洗浄槽へと送り出す形式で洗浄を行うこともできる。こうすることで、第２の積層フィルムにある母材１２Ｘの有機溶媒含有量はより一層低減することが可能である。 As described above, when the first laminated film is long and continuously running, the second laminated film formed continuously through the drying furnace is filled with, for example, a cleaning solvent. It can wash | clean by letting it pass through the washing tank which carried out. Moreover, after winding the 2nd laminated | multilayer film continuously formed through the drying furnace on a suitable core and making it a winding body, this winding body is transferred to the washing | cleaning apparatus which bears a cleaning process. It is also possible to perform cleaning in such a manner that the second laminated film is sent from the transferred winding body to the cleaning tank. By doing so, it is possible to further reduce the organic solvent content of the base material 12X in the second laminated film.
＜工程（ｉｖ）＞
次に工程（ｉｖ）に関し説明する。図３Ｃは工程（ｉｖ）を示す説明図である。工程（ｉｖ）においては、工程（ｉｉｉ）において形成された第２の積層フィルムから支持基材Ｐを剥離などによって除去することにより高分子電解質膜１２の母材１２Ｘを得る。
得られる母材１２Ｘは、好適なキャスト製膜法により得られたものであるため、実質的に無多孔質となる。なお、ここでいう「実質的に無多孔質」とは、ボイドなどの微小貫通孔が高分子電解質膜１２に形成されていないことを意味する。ただし、この高分子電解質膜１２は、燃料電池作動を阻害しない程度の少数量のボイドまたは小さい径のボイドであれば、このボイドを有するような膜であってもよい。 <Process (iv)>
Next, step (iv) will be described. FIG. 3C is an explanatory diagram showing step (iv). In step (iv), the base material 12X of the polymer electrolyte membrane 12 is obtained by removing the supporting substrate P from the second laminated film formed in step (iii) by peeling or the like.
Since the obtained base material 12X is obtained by a suitable cast film forming method, it is substantially non-porous. Here, “substantially non-porous” means that minute through holes such as voids are not formed in the polymer electrolyte membrane 12. However, the polymer electrolyte membrane 12 may be a membrane having such a void as long as it is a small amount of voids or a small diameter void that does not hinder the operation of the fuel cell.
なお、工程（ｉｉｉ）と工程（ｉｖ）との間に、得られた第２の積層フィルムを塩酸や硫酸等の強酸に接触させる酸処理工程が含まれることとしてもよい。 In addition, it is good also as an acid treatment process which makes the obtained 2nd laminated | multilayer film contact strong acids, such as hydrochloric acid and a sulfuric acid, between process (iii) and process (iv).
また、上述のキャスト製膜法による高分子電解質膜１２の製造においては、主として支持基材Ｐが連続的に走行している場合を説明したが、無論、枚葉の支持基材Ｐを用いても、高分子電解質膜１２を得ることができる。この場合、枚葉の支持基材Ｐ上に塗工された高分子電解質溶液は、適当な乾燥炉中に保管することで、有機溶媒を除去することができるし、このようにして得られた枚葉の第２の積層フィルムは、洗浄溶媒を備えた洗浄槽に浸漬等することで洗浄処理を行うことができる。 Further, in the production of the polymer electrolyte membrane 12 by the cast film forming method described above, the case where the support substrate P is continuously running has been described, but of course, using the single wafer support substrate P Also, the polymer electrolyte membrane 12 can be obtained. In this case, the polymer electrolyte solution coated on the single-wafer supporting substrate P can be removed from the organic solvent by storing it in an appropriate drying furnace, and thus obtained. The second laminated film as a single wafer can be cleaned by immersing it in a cleaning tank equipped with a cleaning solvent.
また、洗浄後の第２の積層フィルムは、支持基材Ｐを除去した後、残存または付着している洗浄溶媒を乾燥除去させてもよいし、洗浄後の第２の積層フィルムをそのまま加熱等することで残存または付着している洗浄溶媒を乾燥除去した後、支持基材Ｐを除去してもかまわない。 In addition, after the cleaning, the second laminated film may be removed by removing the cleaning solvent remaining or adhering after the support substrate P is removed, or the second laminated film after washing may be heated as it is. Then, after the remaining or attached cleaning solvent is removed by drying, the supporting substrate P may be removed.
次に、図４Ａ～Ｄに示すように、上述の母材１２Ｘを用いて、高分子電解質膜１２および膜電極接合体２０を製造する。 Next, as shown in FIGS. 4A to 4D, the polymer electrolyte membrane 12 and the membrane electrode assembly 20 are manufactured using the base material 12X.
まず、図４Ａに示すように、母材１２Ｘの一方の表面に金属層１３を形成する。金属層１３としては、母材１２Ｘの表面に、上述の金属微粒子の形成材料を物理蒸着して成膜することにより形成することができる。物理蒸着としては、蒸着法、スパッタ法、イオンプレーティング法など、通常知られた方法を用いることができる。物理蒸着法の中では、イオンプレーティング法が好ましい。ここでは、パラジウムをターゲット金属として用いたイオンプレーティング法により、パラジウム粒子ＳＰを積層させることとして図示している。 First, as shown in FIG. 4A, the metal layer 13 is formed on one surface of the base material 12X. The metal layer 13 can be formed by physically depositing the metal fine particle forming material on the surface of the base material 12X. As physical vapor deposition, generally known methods such as vapor deposition, sputtering, and ion plating can be used. Among the physical vapor deposition methods, the ion plating method is preferable. Here, the palladium particles SP are illustrated as being stacked by an ion plating method using palladium as a target metal.
なお、本発明の一実施態様においては、膜状の形態を有する金属層１３を採用するものとしたが、膜状でなくてもよい。他にも、上述の形成材料の微粒子が層状に敷き詰められた形態（以下、金属微粒子層と称することがある）を採用することもできる。本明細書においては、「金属層」には、膜状の形態を有する層の他に、上記金属微粒子層も含まれることとする。 In one embodiment of the present invention, the metal layer 13 having a film-like form is adopted, but it may not be a film-like form. In addition, it is possible to adopt a form in which the fine particles of the above-described forming material are spread in layers (hereinafter sometimes referred to as a metal fine particle layer). In the present specification, the “metal layer” includes the metal fine particle layer in addition to the layer having a film form.
金属微粒子層は、上述の形成材料の微粒子と、樹脂の前駆体または樹脂の溶液と、を混合した分散液を母材１２Ｘの表面に塗布し、固化させることにより形成することができる。微粒子は、数ｎｍ～数十ｎｍの平均粒子径であるものを用いることができ、塗布する際に、微粒子が凝集した状態になっても構わない。また、前駆体としては、光硬化性樹脂や熱硬化性樹脂の前駆体を用いることができる。塗工方法としては、スプレイ法、ダイコート法等の公知の技術を用いることができる。 The metal fine particle layer can be formed by applying and solidifying a dispersion obtained by mixing fine particles of the above-described forming material and a resin precursor or a resin solution onto the surface of the base material 12X. Fine particles having an average particle diameter of several nm to several tens of nm can be used, and the fine particles may be aggregated during coating. Moreover, as a precursor, the precursor of a photocurable resin or a thermosetting resin can be used. As the coating method, known techniques such as a spray method and a die coating method can be used.
これらの塗工方法で形成された金属層は、金属微粒子が電解質膜表面に微分散した構造を有している。このような金属微粒子層では、上述の物理蒸着で形成した膜状の金属層とは異なり、金属微粒子間に隙間が形成されているため、この隙間を介して高分子電解質膜と触媒層との間のイオンの授受が容易に行われる。したがって、このような金属微粒子層は発電性能を維持することができる。 The metal layer formed by these coating methods has a structure in which metal fine particles are finely dispersed on the electrolyte membrane surface. In such a metal fine particle layer, unlike the film-like metal layer formed by the physical vapor deposition described above, a gap is formed between the metal fine particles, and therefore the polymer electrolyte membrane and the catalyst layer are interposed through the gap. The exchange of ions between them is easy. Therefore, such a metal fine particle layer can maintain power generation performance.
ここで、分散液の溶媒は、母材１２Ｘを形成する高分子電解質の溶解度を基準として選択される。詳しくは、分散液は、母材１２Ｘを構成する高分子電解質に対して貧溶媒となっている。溶媒が混合溶媒である場合、母材１２Ｘを構成する高分子電解質に対して貧溶媒である少なくとも１種の溶媒が用いられ、貧溶媒となるように物性が調整されている。
なお、本明細書において、高分子電解質の貧溶媒とは、前記高分子電解質を２５℃において０．１質量％以上の濃度で溶解し得ない溶媒を言う。これに対し、高分子電解質の良溶媒とは、前記高分子電解質を２５℃において０．１質量％以上の濃度で溶解し得る溶媒を言う。具体的には、所定量の２５℃の溶媒に対して所定量の高分子電解質を溶解させて溶液を調整し、当該溶液を乾固させて乾燥質量を測定することにより、溶媒に対する高分子電解質の溶解度を測定する。分散液の溶媒は、用いる高分子電解質と劣化防止剤との種類に応じ、各々溶解度を測定することにより適宜選択することができる。 Here, the solvent of the dispersion is selected based on the solubility of the polymer electrolyte forming the base material 12X. Specifically, the dispersion is a poor solvent for the polymer electrolyte constituting the base material 12X. When the solvent is a mixed solvent, at least one kind of solvent that is a poor solvent is used for the polymer electrolyte that forms the base material 12X, and the physical properties are adjusted so as to be a poor solvent.
In the present specification, the poor solvent for the polymer electrolyte refers to a solvent that cannot dissolve the polymer electrolyte at a concentration of 0.1% by mass or more at 25 ° C. In contrast, a good solvent for a polymer electrolyte refers to a solvent that can dissolve the polymer electrolyte at a concentration of 0.1% by mass or more at 25 ° C. Specifically, by dissolving a predetermined amount of polymer electrolyte in a predetermined amount of 25 ° C. solvent to prepare a solution, drying the solution and measuring the dry mass, the polymer electrolyte with respect to the solvent Measure the solubility of. The solvent of the dispersion can be appropriately selected by measuring the solubility according to the type of polymer electrolyte and deterioration inhibitor used.
さらに、物理蒸着法であっても、例えばスパッタ法において、上述の形成材料をターゲットに用い、ターゲットに衝突させるイオン化ガスのエネルギーを制御することにより、スパッタ粒子の粒子径を制御することで、スパッタ粒子が層状に敷き詰められた金属微粒子層を形成することができる。物理蒸着法によって形成された金属層は、電解質膜表面との密着性が優れており、電解質膜と触媒層との界面での水素イオンの輸送量の低下を抑制することができることから、発電性能を維持することができる。 Further, even in the physical vapor deposition method, for example, in the sputtering method, the above-described forming material is used as a target, and the energy of ionized gas that collides with the target is controlled, thereby controlling the particle diameter of the sputtered particles. A metal fine particle layer in which particles are spread in layers can be formed. The metal layer formed by the physical vapor deposition method has excellent adhesion to the electrolyte membrane surface, and can suppress the decrease in the transport amount of hydrogen ions at the interface between the electrolyte membrane and the catalyst layer. Can be maintained.
次に、図４Ｂに示すように、金属層１３を形成した母材１２Ｘを電極５０，５１で挟持し、外部電源５２から発電時における通電と同じ方向に、強制通電を行なう。この操作により、金属層１３はイオン化して消失し、イオン化した金属は母材１２Ｘの内部に浸透する。 Next, as shown in FIG. 4B, the base material 12X on which the metal layer 13 is formed is sandwiched between the electrodes 50 and 51, and forced energization is performed in the same direction as energization during power generation from the external power source 52. By this operation, the metal layer 13 is ionized and disappears, and the ionized metal penetrates into the base material 12X.
次に、図４Ｃに示すように、通電をやめると、金属層１３から溶け出した金属イオンは、母材１２Ｘ内で金属が互いに凝集しながら金属微粒子１３Ａとして析出する。金属層１３が２種以上の形成材料を用いて形成されている場合には、合金として析出することもある。 Next, as shown in FIG. 4C, when the energization is stopped, the metal ions dissolved from the metal layer 13 precipitate as metal fine particles 13A while the metals aggregate together in the base material 12X. When the metal layer 13 is formed using two or more kinds of forming materials, it may be precipitated as an alloy.
図４Ｃでは、金属微粒子１３Ａが幅Ｗの間に多く析出し、他の箇所よりも高濃度になっている様子を模式的に示している。また、高濃度になっている箇所は母材１２Ｘの厚さ方向の中心よりは、もとの金属層１３があった側（母材１２Ｘの上方）となっていることとして示している。
このようにして本発明の一実施態様である高分子電解質膜１２を製造する。 FIG. 4C schematically shows a state in which a large amount of the metal fine particles 13A are deposited in the width W, and the concentration is higher than that of other portions. Further, it is shown that the high concentration portion is on the side where the original metal layer 13 was present (above the base material 12X) rather than the center in the thickness direction of the base material 12X.
Thus, the polymer electrolyte membrane 12 which is one embodiment of this invention is manufactured.
次に、図４Ｄに示すように、カーボンに担持された白金または白金系合金を、パーフルオロアルキルスルホン酸樹脂の溶剤と共に混合してペースト化したもの（以下、触媒インク１４Ｓという場合がある）を、高分子電解質膜１２の一方の表面に塗布・乾燥することにより、アノード触媒層１４ａが得られる。同様に、高分子電解質膜１２の他方の表面に触媒インク１４Ｓを塗布・乾燥することにより、カソード触媒層１４ｂを形成し、本発明の一実施態様である膜電極接合体２０を製造する。 Next, as shown in FIG. 4D, platinum or a platinum-based alloy supported on carbon is mixed with a solvent of a perfluoroalkylsulfonic acid resin to form a paste (hereinafter sometimes referred to as catalyst ink 14S). The anode catalyst layer 14a is obtained by applying and drying one surface of the polymer electrolyte membrane 12. Similarly, the cathode catalyst layer 14b is formed by applying and drying the catalyst ink 14S on the other surface of the polymer electrolyte membrane 12, and the membrane electrode assembly 20 which is one embodiment of the present invention is manufactured.
なお、高分子電解質膜１２のその他の製造方法としては、上述の高分子電解質溶液の他に、高分子電解質溶液に金属微粒子を添加して分散させた金属微粒子分散液を調整し、これらの溶液および分散液を用いて形成する方法を示すことができる。 In addition, as another method for producing the polymer electrolyte membrane 12, in addition to the polymer electrolyte solution described above, a metal fine particle dispersion in which metal fine particles are added and dispersed in the polymer electrolyte solution is prepared, and these solutions are prepared. And a method of forming using the dispersion.
すなわち、図５Ａに示すように、支持基材Ｐの上に、ダイ１００から高分子電解質溶液１２Ｓを吐出して流延膜１２Ａを形成する。本工程は、上述の図３Ａと同様である。 That is, as shown in FIG. 5A, the casting membrane 12A is formed on the support substrate P by discharging the polymer electrolyte solution 12S from the die 100. This step is the same as that in FIG. 3A described above.
次いで、図５Ｂに示すように、流延膜１２Ａ上に、別途調整した金属微粒子１３Ａを含む金属微粒子分散液１９Ｓを吐出して流延膜１９Ａを形成する。流延膜１２Ａ上に金属微粒子分散液１９Ｓを吐出すると、金属微粒子分散液１９Ｓに含まれる溶媒により流延膜１２Ａの表面が膨潤し、流延膜１２Ａと流延膜１９Ａとの界面が不明確になる。一方で、予め一部の溶媒を蒸発させてなる流延膜１２Ａ内には、金属微粒子分散液１９Ｓ内の金属微粒子１３Ａが分散されにくいため、金属微粒子１３Ａは流延膜１９Ａ内に局在しやすい。 Next, as shown in FIG. 5B, a casting film 19A is formed on the casting film 12A by discharging a metal fine particle dispersion 19S containing separately prepared metallic fine particles 13A. When the metal fine particle dispersion 19S is discharged onto the casting film 12A, the surface of the casting film 12A is swollen by the solvent contained in the metal fine particle dispersion 19S, and the interface between the casting film 12A and the casting film 19A is unclear. become. On the other hand, since the metal fine particles 13A in the metal fine particle dispersion 19S are difficult to be dispersed in the casting film 12A obtained by evaporating a part of the solvent in advance, the metal fine particles 13A are localized in the casting film 19A. Cheap.
次いで、図５Ｃに示すように、流延膜１２Ａおよび流延膜１９Ａに含有される有機溶媒Ｓを除去して、前記支持基材Ｐ上に高分子電解質膜１２を形成する。溶媒Ｓの除去の過程において、流延膜１２Ａと流延膜１９Ａとの界面は不明確になり、一体の高分子電解質膜１２として形成される。 Next, as shown in FIG. 5C, the organic solvent S contained in the casting membrane 12A and the casting membrane 19A is removed, and the polymer electrolyte membrane 12 is formed on the support substrate P. In the process of removing the solvent S, the interface between the casting film 12A and the casting film 19A becomes unclear and is formed as an integral polymer electrolyte membrane 12.
形成される高分子電解質膜１２を支持基板Ｐから剥離することにより、目的とする高分子電解質膜１２が得られる。 By peeling the formed polymer electrolyte membrane 12 from the support substrate P, the intended polymer electrolyte membrane 12 is obtained.
なお、必要に応じ、図５Ｂで形成した流延膜１９Ａの上に、さらに流延膜１２Ａまたは流延膜１９Ａを積層することもできる。 If necessary, the casting film 12A or the casting film 19A can be further laminated on the casting film 19A formed in FIG. 5B.
また、上述した製造工程の積層順は、逆であってもよい。すなわち、まず、支持基板Ｐの上に流延膜１９Ａを形成した後、流延膜１９Ａの上に流延膜１２Ａを積層して溶媒除去を行い、高分子電解質膜１２を形成することとしてもよい。 Further, the order of stacking the manufacturing steps described above may be reversed. That is, first, the casting film 19A is formed on the support substrate P, and then the casting film 12A is laminated on the casting film 19A to remove the solvent, thereby forming the polymer electrolyte membrane 12. Good.
また、図６Ａ～Ｃに示すような方法を用いて、高分子電解質膜１２および膜電極接合体２０を製造することとしてもよい。 Alternatively, the polymer electrolyte membrane 12 and the membrane electrode assembly 20 may be manufactured using a method as shown in FIGS. 6A to 6C.
まず、図６Ａに示すように、ガス拡散層１６ａの表面に、触媒インク１４Ｓを塗布・乾燥することにより、ガス拡散層１６ａと積層一体化したアノード触媒層１４ａが得られる。同様の方法にて、ガス拡散層と積層一体化したカソード触媒層も形成する。 First, as shown in FIG. 6A, an anode catalyst layer 14a laminated and integrated with the gas diffusion layer 16a is obtained by applying and drying the catalyst ink 14S on the surface of the gas diffusion layer 16a. In the same manner, a cathode catalyst layer laminated and integrated with the gas diffusion layer is also formed.
次に、図６Ｂに示すように、得られたアノード触媒層１４ａ、カソード触媒層１４ｂにて、上述の図４Ａと同様の方法で金属層１３を形成した母材１２Ｘを挟持して接合させる。 Next, as shown in FIG. 6B, the base material 12X on which the metal layer 13 is formed is sandwiched and joined between the obtained anode catalyst layer 14a and cathode catalyst layer 14b by the same method as in FIG. 4A described above.
図６ＡおよびＢに示す工程の具体的な方法としては、公知の方法（例えば、Ｊ． Ｅｌｅｃｔｒｏｃｈｅｍ． Ｓｏｃ．： Ｅｌｅｃｔｒｏｃｈｅｍｉｃａｌ Ｓｃｉｅｎｃｅ ａｎｄ Ｔｅｃｈｎｏｌｏｇｙ， １９８８， １３５（９）， ２２０９に記載されている方法）を用いることができる。また、触媒インク１４Ｓを、高分子電解質膜１２に塗布・乾燥して、この膜の表面上に、直接触媒層を形成させても、燃料電池用の膜電極接合体を得ることができる。 6A and 6B, a known method (for example, a method described in J. Electrochem. Soc .: Electrochemical Science Science Technology, 1988, 135 (9), 2209) is used. be able to. Alternatively, a membrane electrode assembly for a fuel cell can be obtained by applying the catalyst ink 14S to the polymer electrolyte membrane 12 and drying it to form a catalyst layer directly on the surface of the membrane.
次に、図６Ｃに示すように、ガス拡散層１６ａ，１６ｂの外側にセパレータ１８ａ，１８ｂを設けて燃料電池を形成した後、アノード触媒層１４ａ側に水素、カソード触媒層１４ｂ側に酸素をそれぞれ供給して発電を行い、エージングと呼ばれる電池電圧が飽和するまで初期馴らし運転を行なう。通常、燃料電池セルの組み立て後においては、プロトン伝導パスが充分に形成されていないために、発電が不安定になりやすいことからエージングを行う。ここでは、このエージングにおいて通電することにより、金属層１３をイオン化して母材１２Ｘ内に金属微粒子１３Ａとして析出させる。
本発明の一実施態様である高分子電解質膜１２および膜電極接合体２０は、以上のようにして製造することができる。 Next, as shown in FIG. 6C, separators 18a and 18b are provided outside the gas diffusion layers 16a and 16b to form a fuel cell, and then hydrogen is supplied to the anode catalyst layer 14a and oxygen is supplied to the cathode catalyst layer 14b. Power is supplied to generate power, and initial acclimation operation is performed until the battery voltage called aging is saturated. Usually, after assembly of the fuel cell, aging is performed because power generation tends to become unstable because the proton conduction path is not sufficiently formed. Here, by energizing in this aging, the metal layer 13 is ionized and deposited as metal fine particles 13A in the base material 12X.
The polymer electrolyte membrane 12 and the membrane electrode assembly 20 which are one embodiment of the present invention can be produced as described above.
以上のような構成の膜電極接合体によれば、高分子電解質の長期安定性を図ることで高耐久化がなされた膜電極接合体とすることができる。 According to the membrane electrode assembly having the above-described configuration, it is possible to obtain a membrane electrode assembly with high durability by achieving long-term stability of the polymer electrolyte.
また、以上のような構成の膜電極接合体を有する燃料電池では、高分子電解質膜中でのラジカルを効果的に失活させることができ、長期安定化を図ることができる。 Further, in the fuel cell having the membrane electrode assembly having the above configuration, radicals in the polymer electrolyte membrane can be effectively deactivated, and long-term stabilization can be achieved.
なお、本発明の一実施態様である膜電極接合体では、母材１２Ｘの一方の表面に金属層１３を形成することとしたが、いずれか一方にも形成することとしても構わない。 In the membrane / electrode assembly according to one embodiment of the present invention, the metal layer 13 is formed on one surface of the base material 12X. However, the metal layer 13 may be formed on either one of the surfaces.
以上、添付図面を参照しながら本発明に係る好適な実施の形態例について説明したが、本発明はかかる例に限定されないことは言うまでもない。上述した例において示した各構成部材の諸形状や組み合わせ等は一例であって、本発明の主旨から逸脱しない範囲において設計要求等に基づき種々変更可能である。 The preferred embodiment of the present invention has been described above with reference to the accompanying drawings, but it goes without saying that the present invention is not limited to such an example. Various shapes, combinations, and the like of the constituent members shown in the above-described examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.
以下に本発明を実施例により説明するが、本発明はこれらの実施例に限定されるものではない。 EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.
［分子量測定］
膜電極接合体を構成する高分子電解質の分子量測定は、ゲル浸透クロマトグラフィー（ＧＰＣ）を用いた。
測定に際しては、高分子電解質４ｍｇを下記移動層溶媒８ｍＬに溶解して、下記条件で測定を行い、ポリスチレン換算を行うことによって高分子電解質の重量平均分子量および数平均分子量を算出した。測定におけるＧＰＣ条件を下記の表３に示す。 [Molecular weight measurement]
Gel permeation chromatography (GPC) was used for measuring the molecular weight of the polymer electrolyte constituting the membrane electrode assembly.
In the measurement, 4 mg of the polymer electrolyte was dissolved in 8 mL of the following moving bed solvent, the measurement was performed under the following conditions, and the weight average molecular weight and the number average molecular weight of the polymer electrolyte were calculated by performing polystyrene conversion. The GPC conditions in the measurement are shown in Table 3 below.
Figure JPOXMLDOC01-appb-T000015
Figure JPOXMLDOC01-appb-T000015
［イオン交換容量の測定］
測定に供するポリマーをキャスト製膜法により成膜したポリマー膜を得、得られたポリマー膜を適当な重量になるように裁断した。裁断したポリマー膜の乾燥重量を加熱温度１１０℃に設定されたハロゲン水分率計を用いて測定した。次いで、このようにして乾燥させたポリマー膜を０．１ｍｏｌ／Ｌ水酸化ナトリウム水溶液５ｍＬに浸漬した後、更に５０ｍＬのイオン交換水を加え、２時間放置した。その後、ポリマー膜が浸漬された溶液に、０．１ｍｏｌ／Ｌの塩酸を徐々に加えることで滴定を行い、中和点を求めた。そして、裁断したポリマー膜の乾燥重量と中和に要した塩酸の量から、ポリマーのイオン交換容量（単位：ｍｅｑ／ｇ）を算出した。 [Measurement of ion exchange capacity]
A polymer film obtained by forming a polymer to be measured by a cast film forming method was obtained, and the obtained polymer film was cut to an appropriate weight. The dry weight of the cut polymer film was measured using a halogen moisture meter set at a heating temperature of 110 ° C. Next, the polymer membrane thus dried was immersed in 5 mL of a 0.1 mol / L sodium hydroxide aqueous solution, and further 50 mL of ion exchange water was added and left for 2 hours. Then, titration was performed by gradually adding 0.1 mol / L hydrochloric acid to the solution in which the polymer film was immersed, and the neutralization point was determined. Then, the ion exchange capacity (unit: meq / g) of the polymer was calculated from the dry weight of the cut polymer film and the amount of hydrochloric acid required for neutralization.
（実施例１）
［高分子電解質１の合成］
２，２－ジメチルプロパノール２２．４ｇをピリジン７２．５ｇ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５０ｇを加えた後、室温にて１時間攪拌し、反応させた。
反応混合物に、トルエン３００ｍＬおよび２ｍｏｌ％塩酸２５０ｍＬ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１５０ｍＬ、１０重量％炭酸カリウム水溶液１５０ｍＬ、水１５０ｍＬで順次洗浄した後、減圧条件下で、溶媒を留去し、濃縮液１０５ｇを得た。
濃縮液を０℃まで冷却し、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させることにより、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４９．３ｇ（収率：８１．４％）を得た。
１Ｈ－ＮＭＲ（ＣＤＣｌ３，δ（ｐｐｍ））：０．９７（ｓ，９Ｈ），３．７８（ｓ，２Ｈ），７．５２－７．５３（ｃ，２Ｈ），８．０７（ｄ，１Ｈ）
マススペクトル（ｍ／ｚ）：２９７（Ｍ＋） Example 1
[Synthesis of Polymer Electrolyte 1]
2,2.4 g of 2,2-dimethylpropanol was dissolved in 72.5 g of pyridine. To this, 50 g of 2,5-dichlorobenzenesulfonic acid chloride was added at 0 ° C., and the mixture was stirred at room temperature for 1 hour to be reacted.
To the reaction mixture, 300 mL of toluene and 250 mL of 2 mol% hydrochloric acid were added, stirred for 30 minutes, and allowed to stand to separate the organic layer.
The separated organic layer was washed sequentially with 150 mL of water, 150 mL of 10 wt% aqueous potassium carbonate solution and 150 mL of water, and then the solvent was distilled off under reduced pressure to obtain 105 g of a concentrated solution.
The concentrate was cooled to 0 ° C., and the precipitated solid was separated by filtration. The separated solid was dried to obtain 49.3 g (yield: 81.4%) of a white solid of 2,5-dichlorobenzenesulfonic acid (2,2-dimethylpropyl).
1 H-NMR (CDCl 3 , δ (ppm)): 0.97 (s, 9H), 3.78 (s, 2H), 7.52 to 7.53 (c, 2H), 8.07 (d , 1H)
Mass spectrum (m / z): 297 (M + )
無水塩化ニッケル２２．０ｇと、ジメチルスルホキシド２２０ｍＬと、を混合し、内温７０℃に調製した。これに、２，２’－ビピリジン２９．２ｇを加え、７０℃にて１０分間攪拌し、ニッケル含有溶液を調製した。
一方で、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）２０．０ｇと、下記式（１） 22.0 g of anhydrous nickel chloride and 220 mL of dimethyl sulfoxide were mixed to prepare an internal temperature of 70 ° C. To this, 29.2 g of 2,2′-bipyridine was added and stirred at 70 ° C. for 10 minutes to prepare a nickel-containing solution.
On the other hand, 20.0 g of 2,5-dichlorobenzenesulfonic acid (2,2-dimethylpropyl) and the following formula (1)
Figure JPOXMLDOC01-appb-C000016
 で示されるポリエーテルスルホン（住友化学株式会社製、スミカエクセルＰＥＳ３６００Ｐ、Ｍｎ＝２．７×１０４、Ｍｗ＝４．５×１０４）９．８８ｇと、をジメチルスルホキシド３００ｍＬに溶解させて得られた溶液に、メタンスルホン酸３９ｍｇ、亜鉛粉末１６．７ｇを加え、５０℃に調整した。次いで、これに上述のニッケル含有溶液を加え、７０℃で２時間重合反応を行った。
Figure JPOXMLDOC01-appb-C000016
 Obtained by dissolving 9.88 g of polyethersulfone (Sumitomo Chemical Co., Ltd., SUMIKAEXCEL PES3600P, Mn = 2.7 × 10 4 , Mw = 4.5 × 10 4 ) in 300 mL of dimethyl sulfoxide. The solution was adjusted to 50 ° C. by adding 39 mg of methanesulfonic acid and 16.7 g of zinc powder. Next, the above nickel-containing solution was added thereto, and a polymerization reaction was performed at 70 ° C. for 2 hours.
得られた重合溶液を、７０℃の熱水１２００ｇに注加し、生じた沈殿を濾過で集めた。
沈殿物に、沈殿物と水との合計が６９６ｇになるように水を加え、さらに３５重量％亜硝酸ナトリウム水溶液９．２ｇを加えた。このスラリー溶液に、６９重量％硝酸１６０ｇを滴下し、滴下後、室温で１時間攪拌した。 The obtained polymerization solution was poured into 1200 g of hot water at 70 ° C., and the resulting precipitate was collected by filtration.
Water was added to the precipitate so that the total amount of the precipitate and water was 696 g, and further 9.2 g of a 35 wt% sodium nitrite aqueous solution was added. To this slurry solution, 160 g of 69% by weight nitric acid was added dropwise, and then stirred at room temperature for 1 hour.
スラリー溶液を濾過し、集めた粗ポリマーを濾液のｐＨが１を越えるまで水で洗浄した。次に、冷却器を備えたフラスコに、粗ポリマーと、粗ポリマーと水との合計の重量が６９８ｇになるまで水を加え、さらに５重量％水酸化リチウム水溶液を、粗ポリマーと水のスラリー溶液のｐＨが７になるまで加え、さらにメタノール６６６ｇを加え、１時間還流させた。 The slurry solution was filtered and the collected crude polymer was washed with water until the pH of the filtrate exceeded 1. Next, water is added to a flask equipped with a condenser until the total weight of the crude polymer and the crude polymer and water reaches 698 g, and a 5% by weight lithium hydroxide aqueous solution is added to the slurry solution of the crude polymer and water. Was added until the pH of the solution became 7, and 666 g of methanol was further added and refluxed for 1 hour.
粗ポリマーを濾過して集め、水２００ｇ、次いで、メタノール２５０ｇを用いて浸漬洗浄し、乾燥させることにより、下記式（２） The crude polymer was collected by filtration, washed by immersion using 200 g of water and then 250 g of methanol, and dried to obtain the following formula (2).
Figure JPOXMLDOC01-appb-C000017
 で示される繰り返し単位と、下記式（３）
Figure JPOXMLDOC01-appb-C000017
 A repeating unit represented by the following formula (3):
Figure JPOXMLDOC01-appb-C000018
  で示されるセグメントと、を含むポリアリーレン２３．４ｇを得た。
　Ｍｗ：３３６０００、Ｍｎ：６８０００
Figure JPOXMLDOC01-appb-C000018
 And 23.4 g of polyarylene containing the segment represented by
Mw: 336000, Mn: 68000
アルゴン雰囲気下、フラスコに上記ポリアリーレン２３．４ｇと、Ｎ－メチル－２－ピロリドン５８５ｇとを加え、８０℃で保温し溶解した。その後、活性アルミナ３０．４ｇを加え、８０℃に保温しながら１時間３０分攪拌した。得られた溶液に、Ｎ－メチル－２－ピロリドン５８５ｇを加えた後、濾過して活性アルミナを除去した。
得られた溶液からＮ－メチル－２－ピロリドンを減圧留去し、２９８ｇの溶液とした。
この溶液に、無水臭化リチウム１０．３ｇと、水２．２ｇと、を加え、１２０℃に保温しながら１２時間攪拌した。
得られた反応溶液を１３重量％塩酸１１７４ｇ中に投入し、１時間攪拌した。析出した固体を濾過で集め、メタノールと３５％塩酸とを１：１で混合した混合溶液１１６９ｇで洗浄する操作を３回繰り返した。
得られた固体を水で洗浄した後、９０℃以上の熱水１５２０ｇに１時間浸漬し濾過する洗浄操作を４回繰り返した。得られた固体を乾燥することにより、下記式（４） Under an argon atmosphere, 23.4 g of the above polyarylene and 585 g of N-methyl-2-pyrrolidone were added to the flask, and kept at 80 ° C. for dissolution. Thereafter, 30.4 g of activated alumina was added, and the mixture was stirred for 1 hour 30 minutes while being kept at 80 ° C. After adding 585 g of N-methyl-2-pyrrolidone to the obtained solution, the active alumina was removed by filtration.
N-methyl-2-pyrrolidone was distilled off under reduced pressure from the resulting solution to give a 298 g solution.
To this solution, 10.3 g of anhydrous lithium bromide and 2.2 g of water were added and stirred for 12 hours while keeping the temperature at 120 ° C.
The obtained reaction solution was put into 1174 g of 13 wt% hydrochloric acid and stirred for 1 hour. The operation of washing the precipitated solid by filtration and washing with 1169 g of a mixed solution of methanol and 35% hydrochloric acid mixed 1: 1 was repeated three times.
After washing the obtained solid with water, the washing operation of immersing in 1520 g of hot water at 90 ° C. or higher for 1 hour and filtering was repeated 4 times. By drying the obtained solid, the following formula (4)
Figure JPOXMLDOC01-appb-C000019
 で示される繰り返し単位と、下記式（５）
Figure JPOXMLDOC01-appb-C000019
 A repeating unit represented by the following formula (5):
Figure JPOXMLDOC01-appb-C000020
  で示されるセグメントと、を含む、目的とする高分子電解質１を得た。収量は１４．７ｇであった。
　１Ｈ－ＮＭＲスペクトルを測定し、２，２―ジメチルプロポキシスルホニル基が定量的にスルホ基に変換されていることを確認した。
　Ｍｗ：４５５０００、Ｍｎ：１９５０００、イオン交換容量（ＩＥＣ）：２．７ｍｅｑ／ｇ
Figure JPOXMLDOC01-appb-C000020
 The target polymer electrolyte 1 containing the segment shown by these was obtained. The yield was 14.7g.
1 H-NMR spectrum was measured, and it was confirmed that the 2,2-dimethylpropoxysulfonyl group was quantitatively converted to a sulfo group.
Mw: 455000, Mn: 195000, ion exchange capacity (IEC): 2.7 meq / g
［高分子電解質膜１Ａの作製］
上述のようにして得られた高分子電解質１をＮ，Ｎ－ジメチルスルホキシドに溶解して、濃度が１０重量％の高分子電解質溶液を調製した。
得られた高分子電解質溶液を、スロットダイを用いて、支持基材である巾３００ｍｍのポリエチレンテレフタレート（ＰＥＴ）フィルム（東洋紡績社製、Ｅ５０００グレード、厚さ１００μｍ）に連続的に流延塗布して、流延膜を形成した。その後、支持基板と流延膜とを連続的に熱風ヒーター乾燥炉へと搬送し、溶媒を除去して成膜した。
得られた膜を２Ｎ硫酸に２時間浸漬後、イオン交換水で水洗し、更に風乾した後に支持基材から剥離することで、高分子電解質膜１Ａを作製した。高分子電解質膜１Ａの膜厚は２０μｍであった。 [Preparation of polymer electrolyte membrane 1A]
The polymer electrolyte 1 obtained as described above was dissolved in N, N-dimethyl sulfoxide to prepare a polymer electrolyte solution having a concentration of 10% by weight.
The obtained polymer electrolyte solution was continuously cast and applied to a polyethylene terephthalate (PET) film (Toyobo Co., Ltd., E5000 grade, thickness 100 μm) having a width of 300 mm as a supporting substrate using a slot die. Thus, a cast film was formed. Thereafter, the support substrate and the cast film were continuously conveyed to a hot air heater drying furnace, and the solvent was removed to form a film.
The obtained membrane was immersed in 2N sulfuric acid for 2 hours, then washed with ion-exchanged water, further air-dried, and then peeled off from the supporting base material to produce a polymer electrolyte membrane 1A. The film thickness of the polymer electrolyte membrane 1A was 20 μm.
［金属層の作成］
高分子電解質膜１Ａの一方の表面に、イオンプレーティング法を用いて、パラジウム（Ｐｄ）を蒸着し、Ｐｄ層を形成した。
その後、Ｐｄ層を形成した高分子電解質膜を、あらかじめ予備硬化させておいたエポキシ樹脂によって包埋し、ミクロトームにより乾式の条件で厚さ６０ｎｍの切片を切り出した。この際、表面が膜厚方向に沿う断面となるように切り出しを行った。このようにして得られた切片を、Ｃｕメッシュ上に採取し、その表面を透過型電子顕微鏡（日立製作所社製、Ｈ９０００ＮＡＲ）により加速電圧３００ｋＶで観察した。
観察の結果、Ｐｄ層は、１０ｎｍ～４０ｎｍ程度の厚さを有していることが分かった。 [Create metal layer]
Palladium (Pd) was deposited on one surface of the polymer electrolyte membrane 1A using an ion plating method to form a Pd layer.
Thereafter, the polymer electrolyte membrane on which the Pd layer was formed was embedded with an epoxy resin that had been pre-cured in advance, and a 60 nm thick section was cut out by a microtome under dry conditions. At this time, cutting was performed so that the surface had a cross section along the film thickness direction. The slices thus obtained were collected on a Cu mesh, and the surface thereof was observed with a transmission electron microscope (H9000NAR, manufactured by Hitachi, Ltd.) at an acceleration voltage of 300 kV.
As a result of observation, it was found that the Pd layer had a thickness of about 10 nm to 40 nm.
また、積層したＰｄ量を下記の誘導結合プラズマ発光分析装置（ＩＣＰ発光）を用いて測定した。測定の結果、Ｐｄ層として積層したＰｄ量は、高分子電解質膜の重量に対して、０．１８％（１８００ｐｐｍ）であった。
ＩＣＰ発光測定装置：エスアイアイ・ナノテクノロジー社製、ＳＰＳ３０００
測定波長：３４０．４６ｎｍ Further, the amount of laminated Pd was measured using the following inductively coupled plasma optical emission spectrometer (ICP emission). As a result of the measurement, the amount of Pd laminated as the Pd layer was 0.18% (1800 ppm) with respect to the weight of the polymer electrolyte membrane.
ICP luminescence measuring device: SII Nanotechnology, SPS3000
Measurement wavelength: 340.46 nm
［触媒インクの作成］
市販の５重量％ナフィオン（登録商標）溶液（アルドリッチ社製、溶媒：水と低級アルコールの混合物）６．３０ｇに、白金が担持された白金担持カーボン（ＳＡ５０ＢＫ、エヌ・イー・ケムキャット製、白金含有量；５０重量％）１．００ｇ投入し、さらにエタノール４３．４５ｇ、水６．４３ｇを加えた。得られた混合物を１時間超音波処理した後、スターラーで５時間攪拌して触媒インクを得た。 [Catalyst ink creation]
Platinum-supported carbon (SA50BK, N.E. Chemcat, platinum-containing) in which platinum is supported on 6.30 g of a commercially available 5% by weight Nafion (registered trademark) solution (manufactured by Aldrich, solvent: mixture of water and lower alcohol) (Amount: 50% by weight) 1.00 g was added, and 43.45 g of ethanol and 6.43 g of water were further added. The obtained mixture was subjected to ultrasonic treatment for 1 hour and then stirred with a stirrer for 5 hours to obtain a catalyst ink.
［膜電極接合体の作製］
一方の表面にＰｄ層を形成した高分子電解質膜１Ａについて、Ｐｄ層を有しない表面の中央部における３ｃｍ×３ｃｍの領域に、スプレイ法にて上記の触媒インクを塗布した。この際、吐出口から膜までの距離は６ｃｍ、ステージ温度は７５℃に設定した。同様にして重ね塗りをした後、溶媒を除去してアノード触媒層を形成させた。アノード触媒層として１４．２ｍｇの固形分（白金目付け：０．６ｍｇ／ｃｍ２）が塗布された。
続いて、Ｐｄ層の上に同様に触媒インクを塗布して、カソード触媒層を形成させ膜電極接合体１Ｂを得た。カソード触媒層として１４．２ｍｇの固形分（白金目付け：０．６ｍｇ／ｃｍ２）が塗布された。 [Production of membrane electrode assembly]
For the polymer electrolyte membrane 1A having a Pd layer formed on one surface, the catalyst ink was applied to a 3 cm × 3 cm region in the center of the surface not having the Pd layer by a spray method. At this time, the distance from the discharge port to the film was set to 6 cm, and the stage temperature was set to 75 ° C. After overcoating in the same manner, the solvent was removed to form an anode catalyst layer. As an anode catalyst layer, 14.2 mg of solid content (platinum weight: 0.6 mg / cm 2 ) was applied.
Subsequently, a catalyst ink was similarly applied on the Pd layer to form a cathode catalyst layer, thereby obtaining a membrane electrode assembly 1B. As the cathode catalyst layer, 14.2 mg of solid content (platinum weight: 0.6 mg / cm 2 ) was applied.
［燃料電池セルの組み立て］
上述のようにして得られた膜電極接合体１Ｂの両外側に、ガス拡散層としてカーボンクロスと、ガス通路用の溝を切削加工したカーボン製セパレータとを配し、さらにその外側に集電体およびエンドプレートを順に配置し、これらをボルトで締め付けることによって、有効電極面積９ｃｍ２の燃料電池セルを組み立てた。　　
本発明で用いられる集電体としての導電性物質は、公知の材料を用いることができるが、多孔質性のカーボン織布、カーボン不織布またはカーボンペーパーが、原料ガスを触媒へ効率的に輸送するために好ましい。 [Assembly of fuel cell]
A carbon cloth as a gas diffusion layer and a carbon separator in which a gas passage groove is cut are disposed on both outer sides of the membrane electrode assembly 1B obtained as described above, and a current collector is further disposed on the outer side thereof. A fuel cell having an effective electrode area of 9 cm 2 was assembled by sequentially arranging the end plates and fastening them with bolts.
A known material can be used as the conductive material as the current collector used in the present invention, but the porous carbon woven fabric, carbon non-woven fabric or carbon paper efficiently transports the source gas to the catalyst. Therefore, it is preferable.
［燃料電池セルのエージング］
上記で組み立てた燃料電池セルを８０℃に保ちながら、露点８０℃の水素（５００ｍＬ／分、背圧０．１ＭＰａＧ）と露点８０℃の窒素（５００ｍＬ／分、背圧０．１ＭＰａＧ）とをそれぞれセルに導入し、下記条件にて、サイクリックボルタンメトリー（ＣＶ）測定を実施した。
（ＣＶ条件）
開始電圧：０．０５Ｖ
折り返し電圧：１．０Ｖ
終了電圧：０．０５Ｖ
速度：１００ｍＶ／秒
サイクル数：５０サイクル [Aging of fuel cells]
While maintaining the fuel cell assembled above at 80 ° C., hydrogen with a dew point of 80 ° C. (500 mL / min, back pressure 0.1 MPaG) and nitrogen with a dew point of 80 ° C. (500 mL / min, back pressure 0.1 MPaG), respectively The sample was introduced into the cell, and cyclic voltammetry (CV) measurement was performed under the following conditions.
(CV condition)
Starting voltage: 0.05V
Folding voltage: 1.0V
End voltage: 0.05V
Speed: 100 mV / sec Number of cycles: 50 cycles
上記ＣＶ後に、燃料電池セルを８０℃に保ちながら、露点８０℃の水素（５００ｍＬ／分、背圧０．１ＭＰａＧ）と露点８０℃の空気（１０００ｍＬ／分、背圧０．１ＭＰａＧ）とをそれぞれセルに導入し、０．１Ａ／秒の速度で電流が３０Ａになるまで発電特性評価した。繰り返し数を、３０サイクルとした。
発電特性評価後に再度、ＣＶ測定を実施した。この時の速度は、２０ｍＶ／秒、サイクル数は５サイクルとした。
その後、燃料電池セルを８０℃に保ちながら、露点４５℃の水素（５００ｍＬ／分、背圧０．１ＭＰａＧ）と露点５５℃の空気（１０００ｍＬ／分、背圧０．１ＭＰａＧ）とをそれぞれセルに導入し、０．１Ａ／秒の電流掃引速度で電流が３０Ａになるまで発電特性評価した。繰り返し数を、３０サイクルとした。
以上の発電特性評価を行うことで、燃料電池セルのエージングを行った。 After the CV, while maintaining the fuel cell at 80 ° C., hydrogen with a dew point of 80 ° C. (500 mL / min, back pressure 0.1 MPaG) and air with a dew point of 80 ° C. (1000 mL / min, back pressure 0.1 MPaG) The sample was introduced into the cell, and power generation characteristics were evaluated at a rate of 0.1 A / second until the current reached 30 A. The number of repetitions was 30 cycles.
CV measurement was performed again after the power generation characteristics evaluation. The speed at this time was 20 mV / second, and the number of cycles was 5 cycles.
Thereafter, while maintaining the fuel cell at 80 ° C., hydrogen with a dew point of 45 ° C. (500 mL / min, back pressure of 0.1 MPaG) and air with a dew point of 55 ° C. (1000 mL / min, back pressure of 0.1 MPaG) are respectively supplied to the cells. The power generation characteristics were evaluated until the current reached 30 A at a current sweep rate of 0.1 A / second. The number of repetitions was 30 cycles.
The fuel cell was aged by performing the above power generation characteristic evaluation.
［膜内Ｐｄ粒子の析出位置の確認］
上記エージング後の燃料電池に含まれる高分子電解質膜について、厚み方向の断面観察を透過型電子顕微鏡（ＴＥＭ）にて実施した。あらかじめ予備硬化させておいたエポキシ樹脂によって包埋した。それから、この高分子電解質膜から、ミクロトームにより乾式の条件で厚さ６０ｎｍの切片を切り出した。この際、表面が膜厚方向に沿う断面となるように切り出しを行った。このようにして得られた切片を、Ｃｕメッシュ上に採取し、その表面を透過型電子顕微鏡（日立製作所社製、Ｈ９０００ＮＡＲ）により加速電圧３００ｋＶで観察した。 [Confirmation of deposition position of Pd particles in film]
With respect to the polymer electrolyte membrane contained in the fuel cell after aging, cross-sectional observation in the thickness direction was performed with a transmission electron microscope (TEM). It was embedded with an epoxy resin that had been pre-cured in advance. Then, a slice of 60 nm thickness was cut out from the polymer electrolyte membrane by a microtome under dry conditions. At this time, cutting was performed so that the surface had a cross section along the film thickness direction. The slices thus obtained were collected on a Cu mesh, and the surface thereof was observed with a transmission electron microscope (H9000NAR, manufactured by Hitachi, Ltd.) at an acceleration voltage of 300 kV.
図７～図９は、得られたＴＥＭ観察像であり、図７は、アノード触媒層と高分子電解質膜との界面付近、図８は、高分子電解質膜の中心付近、図９は、カソード触媒層と高分子電解質膜との界面付近の様子を示すＴＥＭ写真である。なお、図９のＴＥＭ観察倍率は、１０，０００倍であり、図７，８のＴＥＭ観察倍率は、５０，０００倍である。 7 to 9 are TEM observation images obtained, FIG. 7 is near the interface between the anode catalyst layer and the polymer electrolyte membrane, FIG. 8 is near the center of the polymer electrolyte membrane, and FIG. 9 is the cathode. It is a TEM photograph which shows the mode of the interface vicinity of a catalyst layer and a polymer electrolyte membrane. In addition, the TEM observation magnification of FIG. 9 is 10,000 times, and the TEM observation magnification of FIGS. 7 and 8 is 50,000 times.
図９から、カソード触媒層と高分子電解質膜との界面付近に、Ｐｄ粒子が帯状に多く析出している箇所があることが分かる。また、図７に示すアノード触媒層と高分子電解質膜との界面付近、および図８に示す高分子電解質膜の中心付近についても、多少のＰｄ粒子が析出していることを確認した。 From FIG. 9, it can be seen that there is a portion where a large amount of Pd particles are deposited in the vicinity of the interface between the cathode catalyst layer and the polymer electrolyte membrane. Further, it was confirmed that some Pd particles were also deposited in the vicinity of the interface between the anode catalyst layer and the polymer electrolyte membrane shown in FIG. 7 and in the vicinity of the center of the polymer electrolyte membrane shown in FIG.
この結果より、高分子電解質膜内に分散したＰｄ粒子には濃度勾配があり、かつカソード触媒層と高分子電解質膜との界面付近で最大値を持つことが確認された。 From this result, it was confirmed that the Pd particles dispersed in the polymer electrolyte membrane had a concentration gradient and had a maximum value near the interface between the cathode catalyst layer and the polymer electrolyte membrane.
また、膜内に析出したＰｄ粒子の粒子径は、ＴＥＭ観察像より目視で確認した。その結果、カソード触媒層と高分子電解質膜との界面付近のＰｄ粒子は約１０ｎｍ～約５０ｎｍ程度であった。アノード触媒層と高分子電解質膜との界面付近、および高分子電解質膜の中心付近のＰｄ粒子径は、約１０ｎｍ以下であった。 Moreover, the particle diameter of the Pd particles precipitated in the film was confirmed visually from a TEM observation image. As a result, Pd particles near the interface between the cathode catalyst layer and the polymer electrolyte membrane were about 10 nm to about 50 nm. The Pd particle size in the vicinity of the interface between the anode catalyst layer and the polymer electrolyte membrane and in the vicinity of the center of the polymer electrolyte membrane was about 10 nm or less.
［膜内Ｐｄイオンの分析方法］
耐久性評価を行った燃料電池セルから膜電極接合体を取り出し、エタノール／水の混合溶液（エタノール含有量：９０質量％）を用いて、アノード触媒層およびカソード触媒層を取り除いた。
次いで、あらかじめエチレンジアミン－Ｎ，Ｎ，Ｎ’，Ｎ’－四酢酸二ナトリウム塩二水和物（同仁化学研究所製）７．５ｇを、ビーカーにとり、超純水を加え溶解し、１００ｍＬメスフラスコに定容した溶液（ＥＤＴＡ溶液）を作製した。試験後における高分子電解質膜５ｍｇをスクリュービンにとり、ＥＤＴＡ溶液２ｍＬを加え、膜を浸漬して室温で２時間放置した後、膜を取り出し、誘導結合プラズマ発光分析装置（ＩＣＰ発光）を用いて溶液を測定した。
ＩＣＰ発光測定装置：エスアイアイ・ナノテクノロジー社製、ＳＰＳ３０００
測定波長：３４０．４６ｎｍ [Method for analyzing Pd ions in membrane]
The membrane electrode assembly was taken out from the fuel cell subjected to the durability evaluation, and the anode catalyst layer and the cathode catalyst layer were removed using an ethanol / water mixed solution (ethanol content: 90% by mass).
Next, 7.5 g of ethylenediamine-N, N, N ′, N′-tetraacetic acid disodium salt dihydrate (manufactured by Dojindo Laboratories) is placed in a beaker and dissolved by adding ultrapure water. A solution (EDTA solution) having a constant volume was prepared. 5 mg of the polymer electrolyte membrane after the test is placed in a screw bottle, 2 mL of EDTA solution is added, the membrane is immersed and allowed to stand at room temperature for 2 hours, then the membrane is taken out, and the solution is obtained using an inductively coupled plasma emission spectrometer (ICP emission). Was measured.
ICP luminescence measuring device: SII Nanotechnology, SPS3000
Measurement wavelength: 340.46 nm
［膜内全Ｐｄの分析方法］
耐久性評価を行った燃料電池セルから膜電極接合体を取り出し、エタノール／水の混合溶液（エタノール含有量：９０質量％）を用いて、アノード触媒層およびカソード触媒層を取り除いた。
次いで、試験後における高分子電解質膜５ｍｇを、石英ビーカーにとり、濃硫酸０．２ｍＬを添加し、電気コンロで２０分加熱した後、６５０℃電気炉で２時間加熱処理行った。冷却後に濃塩酸１ｍＬと濃硝酸１ｍＬを添加し、ビーカーにふたをして、８０℃ホットプレートで２０時間加熱処理を行った。処理後の溶液を５ｍＬに定容し、誘導結合プラズマ発光分析装置（ＩＣＰ発光）を用いて溶液を測定した。
ＩＣＰ発光測定装置：エスアイアイ・ナノテクノロジー社製、ＳＰＳ３０００
測定波長：３４０．４６ｎｍ [Analysis method of total Pd in film]
The membrane electrode assembly was taken out from the fuel cell subjected to the durability evaluation, and the anode catalyst layer and the cathode catalyst layer were removed using an ethanol / water mixed solution (ethanol content: 90% by mass).
Next, 5 mg of the polymer electrolyte membrane after the test was placed in a quartz beaker, 0.2 mL of concentrated sulfuric acid was added, heated for 20 minutes with an electric stove, and then heat-treated in an electric furnace at 650 ° C. for 2 hours. After cooling, 1 mL of concentrated hydrochloric acid and 1 mL of concentrated nitric acid were added, the beaker was covered, and heat treatment was performed on an 80 ° C. hot plate for 20 hours. The treated solution was made up to a volume of 5 mL, and the solution was measured using an inductively coupled plasma emission spectrometer (ICP emission).
ICP luminescence measuring device: SII Nanotechnology, SPS3000
Measurement wavelength: 340.46 nm
［燃料電池セルの耐久性評価］
上記エージング後の燃料電池セルを９５℃に保ちながら、アノード触媒層側には低加湿状態の水素（７０ｍＬ／分、背圧０．１ＭＰａＧ）を供給し、カソード触媒層側には低加湿状態の空気（１７４ｍＬ／分、背圧０．０５ＭＰａＧ）を供給して、開回路と一定電流での負荷変動試験を行った。この条件で燃料電池セルを２００時間継続して作動させた。 [Durability evaluation of fuel cells]
While maintaining the fuel cell after the aging at 95 ° C., low humidified hydrogen (70 mL / min, back pressure 0.1 MPaG) is supplied to the anode catalyst layer side, and low humidified state is supplied to the cathode catalyst layer side. Air (174 mL / min, back pressure 0.05 MPaG) was supplied to perform an open circuit and load fluctuation test at a constant current. Under these conditions, the fuel cell was continuously operated for 200 hours.
［耐久性評価後膜の分子量測定］
耐久性評価を行った燃料電池セルから膜電極接合体を取り出し、エタノール／水の混合溶液（エタノール含有量：９０質量％）に投入して超音波処理することで、アノード触媒層およびカソード触媒層を取り除いた。
次いで、試験前後における高分子電解質膜４ｍｇを、２５質量％テトラメチルアンモニウム水酸化物メタノール溶液１０μＬに浸漬し、１００℃で２時間反応させた。
放冷後、得られた反応液の重量平均分子量を、ゲル浸透クロマトグラフィー（ＧＰＣ）を用いて測定した。 [Molecular weight measurement after durability evaluation]
The anode / cathode catalyst layer and the anode catalyst layer are removed by removing the membrane electrode assembly from the fuel cell that has been subjected to durability evaluation, and placing it in a mixed solution of ethanol / water (ethanol content: 90% by mass) and subjecting it to ultrasonic treatment. Removed.
Next, 4 mg of the polymer electrolyte membrane before and after the test was immersed in 10 μL of a 25 mass% tetramethylammonium hydroxide methanol solution and reacted at 100 ° C. for 2 hours.
After standing to cool, the weight average molecular weight of the obtained reaction solution was measured using gel permeation chromatography (GPC).
（比較例１）
高分子電解質膜１の表面にＰｄ層を形成しないこと以外は実施例１と同様に評価した。 (Comparative Example 1)
Evaluation was performed in the same manner as in Example 1 except that no Pd layer was formed on the surface of the polymer electrolyte membrane 1.
（実施例２）
［高分子電解質２の合成］
２，２－ジメチルプロパノール２５．２ｇをテトラヒドロフラン（ＴＨＦ）２００ｍＬに溶解させた。これに、０℃で、ｎ－ブチルリチウムのヘキサン溶液 （１．５７Ｍ）１５１．６ｍＬを滴下した。その後、室温で１時間攪拌し、リチウム（２，２－ジメチルプロポキシド）を含むＴＨＦ溶液を調製した。
４，４’－ジクロロビフェニル－２，２’－ジスルホン酸ジクロリド４０ｇをＴＨＦ３００ｍＬに溶解させて得られた溶液に、０℃で、上述のリチウム （２，２－ジメチルプロポキシド）を含むＴＨＦ溶液を滴下し、その後室温で１時間攪拌して反応させた。
反応混合物を濃縮した後、残渣に、酢酸エチル１０００ｍＬおよび２ｍｏｌ／Ｌ塩酸１００ｍＬを加え、３０分攪拌した後、静置し、有機層を分離した。
分離した有機層を飽和食塩水１０００ｍＬで洗浄した後、減圧条件下で溶媒を留去した。濃縮残渣を、シリカゲルクロマトグラフィ（展開溶媒；クロロホルム）により精製した。
得られた溶出液から、減圧条件下で溶媒を留去し、残渣を７０℃でトルエン５００ｍＬ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、分離した固体を乾燥させることにより、４，４’－ジクロロビフェニル－２，２’－ジスルホン酸ジ（２，２－ジメチルプロピル）の白色固体３１．２ｇを得た。
１Ｈ－ＮＭＲ（ＣＤＣｌ３，δ（ｐｐｍ））：０．９２（ｓ，１８Ｈ），３．６９－３．８６（ｃ，４Ｈ），７．３４－７．３７（ｃ，２Ｈ），７．５９－７．６２（ｃ，２Ｈ），８．０３－８．０４（ｃ，２Ｈ）
マススペクトル（ｍ／ｚ）：４５１（Ｍ－Ｃ５Ｈ１１） (Example 2)
[Synthesis of polymer electrolyte 2]
2,2-dimethylpropanol (25.2 g) was dissolved in tetrahydrofuran (THF) (200 mL). To this, 151.6 mL of a hexane solution (1.57M) of n-butyllithium was added dropwise at 0 ° C. Thereafter, the mixture was stirred at room temperature for 1 hour to prepare a THF solution containing lithium (2,2-dimethylpropoxide).
To a solution obtained by dissolving 40 g of 4,4′-dichlorobiphenyl-2,2′-disulfonic acid dichloride in 300 mL of THF, a THF solution containing the above lithium (2,2-dimethylpropoxide) was added at 0 ° C. The solution was added dropwise, and then reacted by stirring at room temperature for 1 hour.
After the reaction mixture was concentrated, 1000 mL of ethyl acetate and 100 mL of 2 mol / L hydrochloric acid were added to the residue, stirred for 30 minutes, and allowed to stand to separate the organic layer.
The separated organic layer was washed with 1000 mL of saturated brine, and then the solvent was distilled off under reduced pressure. The concentrated residue was purified by silica gel chromatography (developing solvent: chloroform).
From the obtained eluate, the solvent was distilled off under reduced pressure. The residue was dissolved in 500 mL of toluene at 70 ° C., and then cooled to room temperature. The precipitated solid was separated by filtration, and the separated solid was dried to obtain 31.2 g of a white solid of 4,4′-dichlorobiphenyl-2,2′-disulfonic acid di (2,2-dimethylpropyl). It was.
1 H-NMR (CDCl 3 , δ (ppm)): 0.92 (s, 18H), 3.69-3.86 (c, 4H), 7.34-7.37 (c, 2H), 7 .59-7.62 (c, 2H), 8.03-8.04 (c, 2H)
Mass spectrum (m / z): 451 (M−C 5 H 11 )
共沸蒸留装置を備えたフラスコに、窒素雰囲気下、４，４’－ジヒドロキシ－１，１’－ビフェニル１０．２ｇ（５４．７ｍｍｏｌ）、炭酸カリウム８．３２ｇ（６０．２ｍｍｏｌ）、Ｎ，Ｎ－ジメチルアセトアミド９６ｇ、トルエン５０ｇを加えた。バス温１５５℃で２．５時間トルエンを加熱還流することで系内の水分を共沸脱水した。
生成した水とトルエンを留去した後、室温まで放冷し、４，４’－ジクロロジフェニルスルホン２２．０ｇ（７６．６ｍｍoｌ）を加えた。その後、バス温を１６０℃に昇温し、１４時間保温撹拌した。
放冷後、反応液をメタノール１０００ｇと３５重量％塩酸２００ｇとの混合溶液に加え、析出した沈殿を濾過した後、イオン交換水で中性になるまで洗浄し、乾燥させた。得られた粗生成物２７．２ｇをＮ，Ｎ－ジメチルアセトアミド９７ｇに溶解し、不溶物を濾過した後、メタノール１１００ｇと３５重量％塩酸１００ｇとの混合溶液に加えた。
析出した沈殿を濾過した後、イオン交換水で中性になるまで洗浄し、乾燥させることにより、下記式（６）で表される、イオン交換基を実質的に有しないセグメントを誘導する前駆体２５．９ｇを得た。
ＧＰＣ分子量：　Ｍｎ＝１７００、Ｍｗ＝３２００　 To a flask equipped with an azeotropic distillation apparatus, in a nitrogen atmosphere, 10.4 g (54.7 mmol) of 4,4′-dihydroxy-1,1′-biphenyl, 8.32 g (60.2 mmol) of potassium carbonate, N, N -96 g of dimethylacetamide and 50 g of toluene were added. Water in the system was azeotropically dehydrated by heating and refluxing toluene at a bath temperature of 155 ° C. for 2.5 hours.
After the produced water and toluene were distilled off, the mixture was allowed to cool to room temperature, and 22.0 g (76.6 mmol) of 4,4′-dichlorodiphenylsulfone was added. Thereafter, the bath temperature was raised to 160 ° C., and the mixture was kept warm for 14 hours.
After allowing to cool, the reaction solution was added to a mixed solution of 1000 g of methanol and 200 g of 35 wt% hydrochloric acid, and the deposited precipitate was filtered, washed with ion-exchanged water until neutral, and dried. 27.2 g of the obtained crude product was dissolved in 97 g of N, N-dimethylacetamide, insoluble matters were filtered, and then added to a mixed solution of 1100 g of methanol and 100 g of 35 wt% hydrochloric acid.
A precursor that induces a segment substantially having no ion-exchange group represented by the following formula (6) by filtering the deposited precipitate, washing with ion-exchanged water until neutral, and drying. 25.9 g was obtained.
GPC molecular weight: Mn = 1700, Mw = 3200
Figure JPOXMLDOC01-appb-C000021
Figure JPOXMLDOC01-appb-C000021
次に、アルゴン雰囲気下、フラスコに無水臭化ニッケル２．１２ｇ（９．７１ｍｍｏｌ）、Ｎ－メチルピロリドン９６ｇを加え、バス温７０℃で攪拌した。無水臭化ニッケルが溶解したのを確認した後、バス温を５０℃に冷却し、２，２’－ビピリジル１．８２ｇ（１１．７ｍｍｏｌ）を加え、ニッケル含有溶液を調製した。
一方で、アルゴン雰囲気下、フラスコに上記式（６）で表される前駆体４．０２ｇ、Ｎ－メチルピロリドン３８４ｇを加え５０℃に調整した。得られた溶液に、亜鉛粉末３．８１ｇ（５８．２ｍｍｏｌ）、メタンスルホン酸１重量とＮ－メチルピロリドン９重量部との混合溶液１．０５ｇ、および、４，４’－ジクロロビフェニル－２，２’－ジスルホン酸ジ（２，２－ジメチルプロピル）２４．０ｇ（４５．９ｍｍｏｌ）を加え、５０℃で３０分間撹拌した。
これに、上述のニッケル含有溶液を注ぎ込み、５０℃で６時間重合反応を行うことで、黒色の重合溶液を得た。 Next, 2.12 g (9.71 mmol) of anhydrous nickel bromide and 96 g of N-methylpyrrolidone were added to the flask under an argon atmosphere, and the mixture was stirred at a bath temperature of 70 ° C. After confirming that anhydrous nickel bromide was dissolved, the bath temperature was cooled to 50 ° C., and 1.82 g (11.7 mmol) of 2,2′-bipyridyl was added to prepare a nickel-containing solution.
On the other hand, in an argon atmosphere, 4.02 g of the precursor represented by the above formula (6) and 384 g of N-methylpyrrolidone were added to the flask and adjusted to 50 ° C. To the resulting solution, 3.81 g (58.2 mmol) of zinc powder, 1.05 g of a mixed solution of 1 part of methanesulfonic acid and 9 parts by weight of N-methylpyrrolidone, and 4,4′-dichlorobiphenyl-2, 24.0 g (45.9 mmol) of 2′-disulfonic acid di (2,2-dimethylpropyl) was added, and the mixture was stirred at 50 ° C. for 30 minutes.
The above-mentioned nickel-containing solution was poured into this, and a black polymerization solution was obtained by performing a polymerization reaction at 50 ° C. for 6 hours.
得られた重合溶液を、１３重量％塩酸３３６０ｇに投入し、室温で３０分間撹拌した。生じた沈殿を濾過した後、１３重量％塩酸３３６０ｇを加え、室温で３０分間撹拌した。その後、沈殿物を濾過し、イオン交換水で濾液のｐＨが４を越えるまで洗浄した。
得られた粗ポリマーに、イオン交換水８４０ｇと、メタノール７９０ｇを加え、バス温９０℃で１時間加熱撹拌した。粗ポリマーをろ過し、乾燥することにより、下記式（７） The obtained polymerization solution was put into 3360 g of 13 wt% hydrochloric acid and stirred at room temperature for 30 minutes. The resulting precipitate was filtered, 3360 g of 13 wt% hydrochloric acid was added, and the mixture was stirred at room temperature for 30 minutes. Thereafter, the precipitate was filtered and washed with ion exchange water until the pH of the filtrate exceeded 4.
To the obtained crude polymer, 840 g of ion exchanged water and 790 g of methanol were added, and the mixture was heated and stirred at a bath temperature of 90 ° C. for 1 hour. By filtering and drying the crude polymer, the following formula (7)
Figure JPOXMLDOC01-appb-C000022
 で示される繰り返し単位と、下記式（８）
Figure JPOXMLDOC01-appb-C000022
 A repeating unit represented by the following formula (8):
Figure JPOXMLDOC01-appb-C000023
  で示されるセグメントと、を含むポリアリーレン２３．９ｇを得た。
Figure JPOXMLDOC01-appb-C000023
 And 23.9 g of polyarylene containing the segment represented by
上述のポリアリーレン２３．９ｇ、イオン交換水４７．８ｇ、無水臭化リチウム１５．９ｇ（１８３ｍｍｏｌ）およびＮ－メチル－２－ピロリドン４７８ｇをフラスコに入れ、バス温１２６℃で１２時間加熱撹拌し、ポリマー溶液を得た。
得られたポリマー溶液を１３重量％塩酸３３４０ｇに投入し、１時間攪拌した。
析出した粗ポリマーを濾過し、メタノールと３５％塩酸とを１：１で混合した混合溶液２３９０ｇで洗浄する操作を３回繰り返した後、濾液のｐＨが４を越えるまでイオン交換水で洗浄した。
さらに、得られたポリマーに大量のイオン交換水を加え、９０℃以上に昇温し、約１０分間加熱保温し濾過する洗浄操作を、５回繰り返した。
得られたポリマーを濾過により分離し、乾燥させることにより下記式（９） 23.9 g of the above polyarylene, 47.8 g of ion-exchanged water, 15.9 g (183 mmol) of anhydrous lithium bromide and 478 g of N-methyl-2-pyrrolidone were placed in a flask and heated and stirred at a bath temperature of 126 ° C. for 12 hours. A polymer solution was obtained.
The obtained polymer solution was added to 3340 g of 13 wt% hydrochloric acid and stirred for 1 hour.
The operation of washing the precipitated crude polymer with 2390 g of a mixed solution in which methanol and 35% hydrochloric acid were mixed 1: 1 was repeated three times, and then the filtrate was washed with ion-exchanged water until the pH of the filtrate exceeded 4.
Furthermore, a large amount of ion-exchanged water was added to the obtained polymer, the temperature was raised to 90 ° C. or higher, and the washing operation of heating and holding for about 10 minutes and filtering was repeated 5 times.
The polymer obtained is separated by filtration and dried to give the following formula (9)
Figure JPOXMLDOC01-appb-C000024
 で示される繰り返し単位と、下記式（１０）
Figure JPOXMLDOC01-appb-C000024
 A repeating unit represented by the following formula (10):
Figure JPOXMLDOC01-appb-C000025
  で示されるセグメントと、を含む、目的とする高分子電解質２を得た。収量は１７．２５ｇであった。
Ｍｗ：５．７８×１０５　イオン交換容量（ＩＥＣ）：４．６ｍｅｑ／ｇ
Figure JPOXMLDOC01-appb-C000025
 The target polymer electrolyte 2 containing the segment shown by these was obtained. The yield was 17.25g.
Mw: 5.78 × 10 5 Ion exchange capacity (IEC): 4.6 meq / g
［高分子電解質膜２Ａの作製］
上述のようにして得られた高分子電解質２をＮ－メチル２－ピロリドンに溶解して、濃度が７．５重量％の高分子電解質溶液を調製した。
得られた高分子電解質溶液を、スロットダイを用いて、支持基材である巾３００ｍｍのポリエチレンテレフタレート（ＰＥＴ）フィルム（東洋紡績社製、Ｅ５０００グレード、厚さ１００μｍ）に連続的に流延塗布して、流延膜を形成した。その後、支持基板と流延膜とを連続的に熱風ヒーター乾燥炉へと搬送し、溶媒を除去して成膜した。
得られた膜を２Ｎ硫酸に２時間浸漬後、イオン交換水で水洗し、更に風乾した後に支持基材から剥離することで、高分子電解質膜２Ａを作製した。高分子電解質膜２Ａの膜厚は１０μｍであった。 [Preparation of polymer electrolyte membrane 2A]
The polymer electrolyte 2 obtained as described above was dissolved in N-methyl 2-pyrrolidone to prepare a polymer electrolyte solution having a concentration of 7.5% by weight.
The obtained polymer electrolyte solution was continuously cast and applied to a polyethylene terephthalate (PET) film (Toyobo Co., Ltd., E5000 grade, thickness 100 μm) having a width of 300 mm as a supporting substrate using a slot die. Thus, a cast film was formed. Thereafter, the support substrate and the cast film were continuously conveyed to a hot air heater drying furnace, and the solvent was removed to form a film.
The obtained membrane was immersed in 2N sulfuric acid for 2 hours, then washed with ion-exchanged water, further air-dried, and then peeled off from the support base material to produce a polymer electrolyte membrane 2A. The film thickness of the polymer electrolyte membrane 2A was 10 μm.
実施例１と同様にして、高分子電解質膜２Ａの一方の表面にＰｄ層を蒸着して形成した後、両面に触媒層（アノード触媒層、カソード触媒層）を形成して膜電極接合体２Ｂを得た。 In the same manner as in Example 1, after forming a Pd layer on one surface of the polymer electrolyte membrane 2A, a catalyst layer (anode catalyst layer, cathode catalyst layer) is formed on both surfaces to form a membrane electrode assembly 2B. Got.
さらに、膜電極接合体２Ｂを用いる以外は実施例１と同様にして、燃料電池セルを組み立て、耐久性評価を行った。耐久性評価においては、燃料電池セルを５００時間継続して作動させた。その後、燃料電池セルから膜電極接合体を取り出し、高分子電解質膜２Ａの重量平均分子量を測定した。 Further, a fuel cell was assembled and durability was evaluated in the same manner as in Example 1 except that the membrane electrode assembly 2B was used. In the durability evaluation, the fuel cell was continuously operated for 500 hours. Thereafter, the membrane electrode assembly was taken out from the fuel cell, and the weight average molecular weight of the polymer electrolyte membrane 2A was measured.
（比較例２）
高分子電解質膜２Ａの表面にＰｄ層を形成しないこと以外は実施例２と同様に評価した。 (Comparative Example 2)
Evaluation was performed in the same manner as in Example 2 except that the Pd layer was not formed on the surface of the polymer electrolyte membrane 2A.
（実施例３）
［高分子電解質３の合成］
アルゴン雰囲気下、フラスコに無水臭化ニッケル７．６９ｇ（３５．２ｍｍｏｌ）、２，２’－ビピリジル５．４９ｇ（３５．２ｍｍｏｌ）、Ｎ－メチルピロリドン４６０ｇを加え、６５℃に昇温してニッケル含有溶液を調製した。
別のフラスコに、亜鉛粉末１７．２ｇ（２６３．８ｍｍｏｌ）、特開２００７－２７０１１８号公報の実施例１記載の方法により合成した４，４’－ジクロロビフェニル－２，２’－ジスルホン酸ジ（２，２－ジメチルプロピル）１００．０ｇ（１７５．９ｍｍｏｌ）、Ｎ－メチルピロリドン８９８ｇ、上述の（１４ａ－２）で示されるポリエーテルスルホン（住友化学株式会社製、スミカエクセルＰＥＳ３６００Ｐ）５６．７３ｇを加え５０℃に調整した。このフラスコ内を十分に窒素で置換した後、メタンスルホン酸／Ｎ－メチルピロリドン溶液（重量比１／６６の混合溶液）１３．５２ｇを加え、４０℃で３時間撹拌した。
これに、上述のニッケル含有溶液を注ぎ込み、２０℃で１２時間重合反応を行うことで、黒色の重合溶液を得た。 (Example 3)
[Synthesis of polymer electrolyte 3]
Under an argon atmosphere, 7.69 g (35.2 mmol) of anhydrous nickel bromide, 5.49 g (35.2 mmol) of 2,2′-bipyridyl and 460 g of N-methylpyrrolidone were added to the flask. A containing solution was prepared.
In a separate flask, 17.2 g (263.8 mmol) of zinc powder and 4,4′-dichlorobiphenyl-2,2′-disulfonic acid di (2) synthesized by the method described in Example 1 of JP-A-2007-270118 were used. 2,2-dimethylpropyl) 100.0 g (175.9 mmol), N-methylpyrrolidone 898 g, polyethersulfone (Sumitomo Chemical Co., Ltd., Sumika Excel PES3600P) represented by the above (14a-2) 56.73 g In addition, the temperature was adjusted to 50 ° C. After sufficiently replacing the inside of the flask with nitrogen, 13.52 g of a methanesulfonic acid / N-methylpyrrolidone solution (mixed solution with a weight ratio of 1/66) was added, and the mixture was stirred at 40 ° C. for 3 hours.
The above-mentioned nickel-containing solution was poured into this, and a black polymerization solution was obtained by performing a polymerization reaction at 20 ° C. for 12 hours.
得られた重合反応液１００重量部にトルエン２００重量部、メチルエチルケトン１６０重量部、１９重量％塩酸３０重量部を加え、８０℃で１時間撹拌した。
その後、３０分静置して２層に分離させ、下層（水層）の薄青色透明液を除去した後、上層（有機層）の白色懸濁液から減圧下でトルエンとメチルエチルケトンとを留去して濃縮し、反応混合物を得た。
得られた反応混合物にＮ－メチルピロリドンを加えて、１０重量％の反応混合物Ｎ－メチルピロリドン溶液を得た。 To 100 parts by weight of the obtained polymerization reaction solution, 200 parts by weight of toluene, 160 parts by weight of methyl ethyl ketone, and 30 parts by weight of 19% by weight hydrochloric acid were added and stirred at 80 ° C. for 1 hour.
Thereafter, the mixture was allowed to stand for 30 minutes to be separated into two layers. After removing the light blue transparent liquid of the lower layer (aqueous layer), toluene and methyl ethyl ketone were distilled off from the white suspension of the upper layer (organic layer) under reduced pressure. And concentrated to obtain a reaction mixture.
N-methylpyrrolidone was added to the resulting reaction mixture to obtain a 10% by weight reaction mixture N-methylpyrrolidone solution.
上記Ｎ－メチルピロリドン溶液１００重量部に、１９重量％塩酸５重量部を加えて、１２０℃で２４時間加熱した。得られた反応溶液をアセトンに注ぎ込み、上記反応混合物に含まれるポリアリーレンを析出させた。
析出したポリアリーレンをアセトンで洗浄した後、１３重量％塩酸で洗浄し、さらに９３℃の熱水で５回洗浄した上で、メタノール洗浄を４回繰り返した。得られたポリマーを乾燥することにより下記式（１１） To 100 parts by weight of the N-methylpyrrolidone solution, 5 parts by weight of 19% by weight hydrochloric acid was added and heated at 120 ° C. for 24 hours. The obtained reaction solution was poured into acetone to precipitate polyarylene contained in the reaction mixture.
The precipitated polyarylene was washed with acetone, then washed with 13 wt% hydrochloric acid, further washed 5 times with hot water at 93 ° C., and then washed with methanol four times. By drying the obtained polymer, the following formula (11)
Figure JPOXMLDOC01-appb-C000026
 で示される繰り返し単位からなる、スルホ基を有するセグメントと、下記式（１２）
Figure JPOXMLDOC01-appb-C000026
 A segment having a sulfo group, the repeating unit represented by formula (12):
Figure JPOXMLDOC01-appb-C000027
 で示される、イオン交換基を実質的に有しないセグメントを有するブロック共重合体を高分子電解質３として得た。
Ｍｎ：１．７３×１０５　Ｍｗ：３．４６×１０５　イオン交換容量（ＩＥＣ）：２．８ｍｅｑ／ｇ
Figure JPOXMLDOC01-appb-C000027
 The block copolymer which has a segment which does not have an ion exchange group substantially, and was shown as the polymer electrolyte 3.
Mn: 1.73 × 10 5 Mw: 3.46 × 10 5 Ion exchange capacity (IEC): 2.8 meq / g
［高分子電解質膜３Ａの作製］
高分子電解質３をＮ，Ｎ－ジメチルスルホキシドに溶解して、濃度１０重量％の高分子電解質溶液を調製した。この高分子電解質溶液を用いること以外は実施例１と同様にして、高分子電解質膜３Ａを作製した。高分子電解質膜３Ａの膜厚は２０μｍであった。 [Preparation of polymer electrolyte membrane 3A]
The polymer electrolyte 3 was dissolved in N, N-dimethyl sulfoxide to prepare a polymer electrolyte solution having a concentration of 10% by weight. A polymer electrolyte membrane 3A was produced in the same manner as in Example 1 except that this polymer electrolyte solution was used. The thickness of the polymer electrolyte membrane 3A was 20 μm.
［膜電極接合体の作製］
高分子電解質膜３Ａの一方の表面に、イオンプレーティング法を用いて、パラジウム（Ｐｄ）を蒸着し、Ｐｄ層を形成した。さらに、Ｐｄ層を有しない表面の中央部における５ｃｍ×５ｃｍの領域に、実施例１と同様にしてアノード触媒層を形成した。アノード触媒層として３９．２ｍｇの固形分（白金目付け：０．６ｍｇ／ｃｍ２）が塗布された。
続いて、Ｐｄ層の上に同様に触媒インクを塗布して、カソード触媒層を形成させ膜電極接合体３Ｂを得た。カソード触媒層として３９．２ｍｇの固形分（白金目付け：０．６ｍｇ／ｃｍ２）が塗布された。 [Production of membrane electrode assembly]
Palladium (Pd) was vapor-deposited on one surface of the polymer electrolyte membrane 3A using an ion plating method to form a Pd layer. Further, an anode catalyst layer was formed in the same manner as in Example 1 in a 5 cm × 5 cm region at the center of the surface not having the Pd layer. As the anode catalyst layer, 39.2 mg of solid content (platinum weight: 0.6 mg / cm 2 ) was applied.
Subsequently, a catalyst ink was similarly applied on the Pd layer to form a cathode catalyst layer to obtain a membrane electrode assembly 3B. As the cathode catalyst layer, 39.2 mg of solid content (platinum weight: 0.6 mg / cm 2 ) was applied.
［燃料電池セルの組み立て］
上述のようにして得られた膜電極接合体３Ｂの両外側に、実施例１と同様にしてカーボンクロス、カーボン製セパレータ、集電体およびエンドプレートを順に配置し、これらをボルトで締め付けることによって、有効電極面積２５ｃｍ２の燃料電池セルを組み立てた。 [Assembly of fuel cell]
A carbon cloth, a carbon separator, a current collector and an end plate are arranged in this order on both outer sides of the membrane electrode assembly 3B obtained as described above in the same manner as in Example 1, and these are tightened with bolts. A fuel cell having an effective electrode area of 25 cm 2 was assembled.
組み立てた燃料電池セルを８０℃に保ちながら、露点８０℃の水素（５００ｍＬ／分、背圧０．１ＭＰａＧ）と露点８０℃の窒素（５００ｍＬ／分、背圧０．１ＭＰａＧ）とをそれぞれセルに導入し、下記条件にて、サイクリックボルタンメトリー（ＣＶ）測定を実施した。
（ＣＶ条件）
開始電圧：０．０５Ｖ
折り返し電圧：１．０Ｖ
終了電圧：０．０５Ｖ
速度：１００ｍＶ／秒
サイクル数：５０サイクル While maintaining the assembled fuel cell at 80 ° C., hydrogen having a dew point of 80 ° C. (500 mL / min, back pressure 0.1 MPaG) and nitrogen having a dew point of 80 ° C. (500 mL / min, back pressure 0.1 MPaG) are respectively supplied to the cells. Then, cyclic voltammetry (CV) measurement was performed under the following conditions.
(CV condition)
Starting voltage: 0.05V
Folding voltage: 1.0V
End voltage: 0.05V
Speed: 100 mV / sec Number of cycles: 50 cycles
上記ＣＶ後に、燃料電池セルを８０℃に保ちながら、露点８０℃の水素（５００ｍＬ／分、背圧０．１ＭＰａＧ）と露点８０℃の空気（１０００ｍＬ／分、背圧０．１ＭＰａＧ）とをそれぞれセルに導入し、０．１Ａ／秒の速度で電流が３０Ａになるまで発電特性評価した。繰り返し数を、３０サイクルとした。
発電特性評価後に再度、ＣＶ測定を実施した。この時の速度は、２０ｍＶ／秒、サイクル数は５サイクルとした。
その後、燃料電池セルを８０℃に保ちながら、露点４５℃の水素（５００ｍＬ／分、背圧０．１ＭＰａＧ）と露点５５℃の空気（１０００ｍＬ／分、背圧０．１ＭＰａＧ）とをそれぞれセルに導入し、０．１Ａ／秒の電流掃引速度で電流が３０Ａになるまで発電特性評価した。繰り返し数を、３０サイクルとした。 After the CV, while maintaining the fuel cell at 80 ° C., hydrogen with a dew point of 80 ° C. (500 mL / min, back pressure 0.1 MPaG) and air with a dew point of 80 ° C. (1000 mL / min, back pressure 0.1 MPaG) The sample was introduced into the cell, and power generation characteristics were evaluated at a rate of 0.1 A / second until the current reached 30 A. The number of repetitions was 30 cycles.
CV measurement was performed again after the power generation characteristics evaluation. The speed at this time was 20 mV / second, and the number of cycles was 5 cycles.
Thereafter, while maintaining the fuel cell at 80 ° C., hydrogen with a dew point of 45 ° C. (500 mL / min, back pressure of 0.1 MPaG) and air with a dew point of 55 ° C. (1000 mL / min, back pressure of 0.1 MPaG) are respectively supplied to the cells. The power generation characteristics were evaluated until the current reached 30 A at a current sweep rate of 0.1 A / second. The number of repetitions was 30 cycles.
上記発電特性評価後に、燃料電池セルを９５℃に保ちながら、アノード触媒層側には低加湿状態の水素（７０ｍＬ／分、背圧０．１ＭＰａＧ）を供給し、カソード触媒層側には低加湿状態の空気（１７４ｍＬ／分、背圧０．０５ＭＰａＧ）を供給して、開回路と一定電流での負荷変動試験を行った。この条件で燃料電池セルを２００時間継続して作動させた。
以上の操作を行うことで、実施例６の燃料電池セルのエージングを行った。 After the above power generation characteristic evaluation, while maintaining the fuel cell at 95 ° C., low humidified hydrogen (70 mL / min, back pressure 0.1 MPaG) is supplied to the anode catalyst layer side, and low humidification is applied to the cathode catalyst layer side. Air in a state (174 mL / min, back pressure 0.05 MPaG) was supplied, and a load fluctuation test was performed with an open circuit and a constant current. Under these conditions, the fuel cell was continuously operated for 200 hours.
By performing the above operation, the fuel cell of Example 6 was aged.
［燃料電池セルの耐久性評価］
上記エージング後の燃料電池セルを９５℃に保持し、アノード触媒層側には露点９５℃の水素（７０ｍＬ/ｍｉｎ、背圧０．１ＭＰａＧ）を供給し、カソード触媒層側には露点３０℃の空気（１７４ｍＬ/ｍｉｎ、背圧０．０５ＭＰａＧ）を供給して、開回路保持試験（ＯＣＶ試験）１００時間を実施した。 [Durability evaluation of fuel cells]
The fuel cell after the aging is maintained at 95 ° C., hydrogen (70 mL / min, back pressure 0.1 MPaG) with a dew point of 95 ° C. is supplied to the anode catalyst layer side, and a dew point of 30 ° C. is supplied to the cathode catalyst layer side. Air (174 mL / min, back pressure 0.05 MPaG) was supplied, and an open circuit retention test (OCV test) was performed for 100 hours.
ＯＣＶ試験後の燃料電池セルから膜電極接合体を取り出し、実施例１と同様にして耐久性評価後の高分子電解質膜の分子量を測定した。 The membrane / electrode assembly was taken out of the fuel cell after the OCV test, and the molecular weight of the polymer electrolyte membrane after durability evaluation was measured in the same manner as in Example 1.
（比較例３）
高分子電解質膜３Ａの表面にＰｄ層を形成しないこと以外は、実施例３と同様に評価した。 (Comparative Example 3)
Evaluation was performed in the same manner as in Example 3 except that the Pd layer was not formed on the surface of the polymer electrolyte membrane 3A.
上記実施例１および比較例１について、高分子電解質１の初期状態からの重量平均分子量維持率を以下の表４にまとめて示す。また、上記実施例２および比較例２について、高分子電解質２の初期状態からの重量平均分子量維持率を以下の表５にまとめて示す。さらに、上記実施例３および比較例３について、高分子電解質３の初期状態からの重量平均分子量維持率を以下の表６にまとめて示す。
評価結果においては、負荷変動試験前後において分子量維持率が高いほど、高分子電解質膜の劣化が小さく、長期安定性に優れていることを示している。 Regarding Example 1 and Comparative Example 1, the weight average molecular weight maintenance rates from the initial state of the polymer electrolyte 1 are summarized in Table 4 below. In addition, with respect to Example 2 and Comparative Example 2, the weight average molecular weight maintenance rates from the initial state of the polymer electrolyte 2 are shown together in Table 5 below. Further, with respect to Example 3 and Comparative Example 3, the weight average molecular weight maintenance ratio from the initial state of the polymer electrolyte 3 is shown together in Table 6 below.
The evaluation results indicate that the higher the molecular weight maintenance rate before and after the load fluctuation test, the less the deterioration of the polymer electrolyte membrane and the better the long-term stability.
また、実施例１～３の高分子電解質膜１Ａ～３Ａについて、「耐久性評価後の膜中に存在する全Ｐｄ量」に対する「耐久性評価後の膜中に存在するＰｄイオン量」の割合と、「耐久性評価後の膜中に存在する全Ｐｄ量」に対する「耐久性評価後の膜中に存在するＰｄ金属量」の割合と、を表７にまとめて示す。ここで、「Ｐｄ金属」とは、Ｐｄがイオン化しておらず、高分子電解質膜中に微粒子として分散しているものを示す。 For the polymer electrolyte membranes 1A to 3A of Examples 1 to 3, the ratio of “the amount of Pd ions present in the film after durability evaluation” to “the total amount of Pd present in the film after durability evaluation” Table 7 summarizes the ratio of “the amount of Pd metal present in the film after durability evaluation” to “the total amount of Pd present in the film after durability evaluation”. Here, “Pd metal” indicates that Pd is not ionized and is dispersed as fine particles in the polymer electrolyte membrane.
Figure JPOXMLDOC01-appb-T000028
Figure JPOXMLDOC01-appb-T000028
Figure JPOXMLDOC01-appb-T000029
Figure JPOXMLDOC01-appb-T000029
Figure JPOXMLDOC01-appb-T000030
Figure JPOXMLDOC01-appb-T000030
Figure JPOXMLDOC01-appb-T000031
Figure JPOXMLDOC01-appb-T000031
測定の結果、本発明の膜電極接合体は、連続発電（すなわち、連続した酸化還元反応）において比較例の膜電極接合体よりも高分子電解質膜の劣化が小さく、安定であることが分かった。
また、表７に示した通り、耐久性評価を行った後には、高分子電解質膜の表面にＰｄ層として形成したＰｄがイオンまたは金属状態で高分子電解質膜内に存在していることが確かめられた。また、高分子電解質膜の表面には、Ｐｄ層が残存していなかった。
これにより、本発明の有用性が確かめられた。 As a result of the measurement, it was found that the membrane / electrode assembly of the present invention was less deteriorated and stable than the membrane / electrode assembly of the comparative example in continuous power generation (that is, continuous oxidation-reduction reaction). .
In addition, as shown in Table 7, after the durability evaluation, it was confirmed that Pd formed as a Pd layer on the surface of the polymer electrolyte membrane was present in the polymer electrolyte membrane in an ion or metal state. It was. Further, no Pd layer remained on the surface of the polymer electrolyte membrane.
This confirmed the usefulness of the present invention.
本発明の高分子電解質膜は、高耐久性を有しているため、前記高分子電解質膜を含む膜電極接合体は長期安定性に優れており、燃料電池に好適に用いられる。 Since the polymer electrolyte membrane of the present invention has high durability, the membrane / electrode assembly including the polymer electrolyte membrane is excellent in long-term stability and is suitably used for a fuel cell.
１０…燃料電池
１２…高分子電解質膜
１３…金属層
１３Ａ…金属微粒子
１４ａ…アノード触媒層
１４ｂ…カソード触媒層
１６ａ，１６ｂ…ガス拡散層
１８ａ，１８ｂ…セパレータ
２０…膜電極接合体（ＭＥＡ） DESCRIPTION OF SYMBOLS 10 ... Fuel cell 12 ... Polymer electrolyte membrane 13 ... Metal layer 13A ... Metal fine particle 14a ... Anode catalyst layer 14b ... Cathode catalyst layer 16a, 16b ... Gas diffusion layer 18a, 18b ... Separator 20 ... Membrane electrode assembly (MEA)

Claims (12)

  1. 高分子電解質で形成された膜状の母材と、
    前記母材の中に分散された金属微粒子と、を有し、
    前記金属微粒子の形成材料が、貴金属および貴金属合金からなる群より選ばれる１種以上の金属を含み、かつ、前記金属微粒子が前記母材の厚み方向に濃度勾配を有して分散している高分子電解質膜。     A film-like base material formed of a polymer electrolyte;
    Metal fine particles dispersed in the base material,
    The metal fine particle forming material contains one or more metals selected from the group consisting of noble metals and noble metal alloys, and the metal fine particles are dispersed with a concentration gradient in the thickness direction of the base material. Molecular electrolyte membrane.
  2. 前記金属微粒子の濃度が極大値を有する請求項１に記載の高分子電解質膜。 The polymer electrolyte membrane according to claim 1, wherein the concentration of the metal fine particles has a maximum value.
  3. 前記金属微粒子の粒子径が５００ｎｍ以下である請求項１または２に記載の高分子電解質膜。 The polymer electrolyte membrane according to claim 1 or 2, wherein the metal fine particles have a particle size of 500 nm or less.
  4. 前記金属微粒子の形成材料が、白金、金、パラジウム、イリジウム、ロジウムおよびルテニウムからなる貴金属群より選ばれる、少なくとも１種の貴金属もしくは貴金属合金のいずれか一方、または両方を含む請求項１～３のいずれか１項に記載の高分子電解質膜。 The material for forming the fine metal particles includes at least one kind of noble metal or noble metal alloy selected from the group of noble metals consisting of platinum, gold, palladium, iridium, rhodium and ruthenium, or both. The polymer electrolyte membrane according to any one of the above.
  5. 前記高分子電解質が、炭化水素系高分子電解質からなる請求項１～４のいずれか１項に記載の高分子電解質膜。 The polymer electrolyte membrane according to any one of claims 1 to 4, wherein the polymer electrolyte is composed of a hydrocarbon-based polymer electrolyte.
  6. 前記炭化水素系高分子電解質が、イオン交換基を有するセグメントと、イオン交換基を実質的に有しないセグメントと、を備えたブロック共重合体を含む請求項５に記載の高分子電解質膜。 The polymer electrolyte membrane according to claim 5, wherein the hydrocarbon-based polymer electrolyte includes a block copolymer including a segment having an ion exchange group and a segment substantially not having an ion exchange group.
  7. 前記高分子電解質で形成された膜状の母材の表面に、金属層を積層させ、前記母材と前記金属層との両面から電圧を印加することで前記母材の内部に析出させた前記金属微粒子を含む請求項１から６のいずれか１項に記載の高分子電解質膜。 The metal layer is laminated on the surface of the film-like base material formed of the polymer electrolyte, and the inside of the base material is deposited by applying a voltage from both sides of the base material and the metal layer. The polymer electrolyte membrane according to any one of claims 1 to 6, comprising metal fine particles.
  8. 前記金属層が、物理蒸着法によって形成される請求項７に記載の高分子電解質膜。 The polymer electrolyte membrane according to claim 7, wherein the metal layer is formed by physical vapor deposition.
  9. 前記金属層が、金属微粒子を含有する液を前記母材の表面に塗工して形成される請求項７に記載の高分子電解質膜。 The polymer electrolyte membrane according to claim 7, wherein the metal layer is formed by coating a liquid containing metal fine particles on the surface of the base material.
  10. 請求項１～９のいずれか１項に記載の高分子電解質膜と、前記高分子電解質膜を挟持するアノード触媒層およびカソード触媒層とを有する膜電極接合体。 A membrane electrode assembly comprising the polymer electrolyte membrane according to any one of claims 1 to 9, and an anode catalyst layer and a cathode catalyst layer that sandwich the polymer electrolyte membrane.
  11. 前記金属微粒子の濃度の極大値が、前記高分子電解質膜の膜厚方向の中心よりも前記カソード触媒層側にある請求項１０に記載の膜電極接合体。 The membrane electrode assembly according to claim 10, wherein a maximum value of the concentration of the metal fine particles is on the cathode catalyst layer side with respect to the center in the film thickness direction of the polymer electrolyte membrane.
  12. 請求項１０または１１に記載の膜電極接合体を有する燃料電池。 A fuel cell comprising the membrane electrode assembly according to claim 10 or 11.
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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06103992A (en) * 1992-09-22 1994-04-15 Tanaka Kikinzoku Kogyo Kk Plymer solid electrolyte fuel cell
JP2003059511A (en) * 2001-08-17 2003-02-28 Matsushita Electric Ind Co Ltd Electrolyte film and electrode junction for fuel cell, its manufacturing method and polymer electrolyte fuel cell
JP2003086201A (en) * 2001-09-11 2003-03-20 Toyota Motor Corp Electrolyte membrane for fuel cell
JP2006302578A (en) * 2005-04-18 2006-11-02 Nissan Motor Co Ltd Operation method of fuel cell and fuel cell system
JP2007123122A (en) * 2005-10-28 2007-05-17 Nissan Motor Co Ltd Electrolyte membrane for fuel cell and membrane electrode assembly
JP2009097003A (en) * 2007-09-25 2009-05-07 Sumitomo Chemical Co Ltd Polyelectrolyte composition and fuel cell
JP2009187866A (en) * 2008-02-08 2009-08-20 Toyota Motor Corp Membrane-electrode assembly

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06103992A (en) * 1992-09-22 1994-04-15 Tanaka Kikinzoku Kogyo Kk Plymer solid electrolyte fuel cell
JP2003059511A (en) * 2001-08-17 2003-02-28 Matsushita Electric Ind Co Ltd Electrolyte film and electrode junction for fuel cell, its manufacturing method and polymer electrolyte fuel cell
JP2003086201A (en) * 2001-09-11 2003-03-20 Toyota Motor Corp Electrolyte membrane for fuel cell
JP2006302578A (en) * 2005-04-18 2006-11-02 Nissan Motor Co Ltd Operation method of fuel cell and fuel cell system
JP2007123122A (en) * 2005-10-28 2007-05-17 Nissan Motor Co Ltd Electrolyte membrane for fuel cell and membrane electrode assembly
JP2009097003A (en) * 2007-09-25 2009-05-07 Sumitomo Chemical Co Ltd Polyelectrolyte composition and fuel cell
JP2009187866A (en) * 2008-02-08 2009-08-20 Toyota Motor Corp Membrane-electrode assembly

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