WO2009081841A1 - 固体高分子型燃料電池用隔膜、及び隔膜-触媒電極接合体 - Google Patents
固体高分子型燃料電池用隔膜、及び隔膜-触媒電極接合体 Download PDFInfo
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- WO2009081841A1 WO2009081841A1 PCT/JP2008/073118 JP2008073118W WO2009081841A1 WO 2009081841 A1 WO2009081841 A1 WO 2009081841A1 JP 2008073118 W JP2008073118 W JP 2008073118W WO 2009081841 A1 WO2009081841 A1 WO 2009081841A1
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- membrane
- anion exchange
- exchange resin
- fuel cell
- resin
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- 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
- H01M8/1023—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having only carbon, e.g. polyarylenes, polystyrenes or polybutadiene-styrenes
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/20—Manufacture of shaped structures of ion-exchange resins
- C08J5/22—Films, membranes or diaphragms
- C08J5/2206—Films, membranes or diaphragms based on organic and/or inorganic macromolecular compounds
- C08J5/2218—Synthetic macromolecular compounds
- C08J5/2231—Synthetic macromolecular compounds based on macromolecular compounds obtained by reactions involving unsaturated carbon-to-carbon bonds
- C08J5/2243—Synthetic macromolecular compounds based on macromolecular compounds obtained by reactions involving unsaturated carbon-to-carbon bonds obtained by introduction of active groups capable of ion-exchange into compounds of the type C08J5/2231
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- 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
- H01M8/1053—Polymer electrolyte composites, mixtures or blends consisting of layers of polymers with at least one layer being ionically conductive
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- 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
- H01M8/1058—Polymeric electrolyte materials characterised by a porous support having no ion-conducting properties
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2325/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Derivatives of such polymers
- C08J2325/02—Homopolymers or copolymers of hydrocarbons
- C08J2325/04—Homopolymers or copolymers of styrene
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0065—Solid electrolytes
- H01M2300/0082—Organic polymers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2300/00—Electrolytes
- H01M2300/0088—Composites
- H01M2300/0094—Composites in the form of layered products, e.g. coatings
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- 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 membrane for a polymer electrolyte fuel cell and a membrane-catalyst electrode assembly produced using the membrane. More specifically, the present invention relates to a polymer electrolyte fuel cell membrane comprising an anion exchange resin membrane, a membrane-catalyst electrode assembly, and a fuel cell incorporating these.
- the diaphragm is composed of an anion exchange resin film and an adhesive layer made of an anion exchange resin having a Young's modulus at 25 ° C. of 1 to 1000 MPa formed on the surface thereof.
- the present invention includes the anion exchange resin film, an adhesive layer, and an intermediate layer formed therebetween.
- the diaphragm is satisfactorily bonded to the catalyst electrode layer through the adhesive layer. As a result, the interface resistance value between the two becomes small, and the output of the fuel cell manufactured using this diaphragm becomes high.
- the ion exchange resin membrane is widely used as a membrane for a battery such as a polymer electrolyte fuel cell, a redox flow battery, a zinc-bromine battery, or a dialysis membrane.
- a polymer electrolyte fuel cell uses an ion exchange resin membrane as a solid electrolyte membrane.
- a fuel and an oxidant are continuously supplied to the polymer electrolyte fuel cell, they react to generate chemical energy.
- a fuel cell takes out this generated chemical energy as electric power, and this fuel cell is one of clean and highly efficient power generation systems.
- polymer electrolyte fuel cells can be expected to operate at a low temperature and can be miniaturized, and therefore, their importance is increasing for automobile use, home use, and portable use.
- a membrane-catalyst electrode assembly (hereinafter sometimes abbreviated as a membrane-catalyst electrode assembly) incorporated in a polymer electrolyte fuel cell generally comprises an ion exchange resin membrane that acts as an electrolyte, and both surfaces thereof. And a diffusion electrode joined to each other.
- the diffusion electrode is generally composed of a porous electrode material and an electrode on which a catalyst is supported and bonded to the porous electrode material.
- direct liquid fuel cells that can directly use fuel such as methanol are evaluated as being easy to handle and inexpensive because the fuel is liquid. For these reasons, the direct liquid fuel cell is expected to be used as a relatively small output power source for portable devices.
- Fig. 1 shows the basic structure of a polymer electrolyte fuel cell.
- reference numerals 1a and 1b denote battery partition walls. These battery partition walls 1a and 1b are respectively provided on both sides of a solid polymer electrolyte membrane 6 made of an ion exchange resin membrane.
- the solid polymer electrolyte membrane 6 functions as a diaphragm.
- 2 is a fuel flow hole formed in the inner wall of one battery partition wall 1a
- 3 is an oxidant gas flow hole formed in the inner wall of the other battery partition wall 1b
- 4 is a fuel chamber side diffusion electrode
- 5 is an oxidant chamber side gas diffusion electrode.
- a cation exchange type electrolyte membrane When a cation exchange type electrolyte membrane is used as the solid polymer electrolyte membrane 6, it is provided in the fuel chamber side diffusion electrode 4 when liquid fuel such as alcohol or gaseous fuel such as hydrogen gas is supplied to the fuel chamber 7. Protons (hydrogen ions) and electrons are generated by the action of the catalyst. The protons conduct in the solid polymer electrolyte membrane 6 and move to the other oxidant chamber 8, where they react with oxygen in the air or oxygen gas to generate water. On the other hand, electrons generated in the fuel chamber side diffusion electrode 4 are sent to the oxidant chamber side gas diffusion electrode 5 through an external load circuit (not shown), and at this time, electric energy is given to the external load circuit.
- liquid fuel such as alcohol or gaseous fuel such as hydrogen gas
- a cation exchange resin diaphragm is usually used for the polymer electrolyte membrane 6.
- Diffusion electrodes 4 and 5 are formed on the surface of the cation exchange resin diaphragm.
- a hot press method is usually employed as a method of forming these diffusion electrodes 4 and 5, a hot press method is usually employed. In this hot pressing method, a diffusion electrode composed of a porous electrode material and a catalyst electrode layer formed on one surface thereof is previously formed on a support. Next, the formed diffusion electrode is thermally transferred from the support to the surface of the cation exchange resin diaphragm.
- the cation exchange resin diaphragm and the catalyst electrode layer are integrated when the polymer electrolyte binder impregnated in the catalyst electrode layer is thermally compatible with the cation exchange resin on the surface of the cation exchange resin diaphragm.
- perfluorocarbon sulfonic acid resin membranes are the most common cation exchange type resin membranes used as fuel cell membranes.
- the reaction field is strongly acidic, only precious metal catalysts can be used.
- the perfluorocarbon sulfonic acid resin membrane is expensive and has a limit in cost reduction.
- the water retention capacity of the resin film is small.
- a fuel cell using an anion exchange membrane generates electrical energy
- the ionic species moving in the solid polymer electrolyte membrane 6 are different from the ionic species of the fuel cell using the cation exchange membrane. That is, liquid fuel such as methanol or gaseous fuel such as hydrogen gas is supplied to the fuel chamber side, and oxygen and water are supplied to the oxidant chamber side, so that the oxidant gas diffusion electrode 5 is included in the electrode. Hydroxide ions (OH ⁇ ) are generated by contacting the catalyst with the oxygen and water. The hydroxide ions are conducted through the solid polymer electrolyte membrane 6 made of the hydrocarbon-based anion exchange membrane and move to the fuel chamber 7. The hydroxide ions that have moved react with the fuel at the fuel diffusion electrode 4 to generate water. At this time, electrons generated by the fuel diffusion electrode 4 are sent to the oxidant gas diffusion electrode 5 through an external load circuit.
- the problem (iv) is alleviated by moisture supplied from the fuel containing water. Furthermore, it is expected that the problem (v) of methanol permeating the diaphragm can be significantly reduced for the following reasons. That is, during energization, hydroxide ions having a large ion diameter move from the oxidant chamber side opposite to the methanol permeation direction toward the fuel chamber side. The movement of methanol ions is hindered by the movement of the hydroxide ions.
- the oxygen reduction overvoltage at the oxidant chamber side diffusion electrode can be reduced by making the reaction field basic.
- a polymer electrolyte fuel cell using a hydrocarbon-based anion exchange membrane has such advantages.
- a porous membrane such as a woven fabric is filled with a hydrocarbon-based crosslinked polymer having an anion-exchange group such as a quaternary ammonium base or a quaternary pyridinium base.
- a film Patent Document 1
- a membrane formed by introducing a quaternary ammonium base into hydrocarbon-based engineering plastics and then cast Patent Document 2
- a hydrocarbon-based monomer having an anion exchange group is graft-polymerized to a substrate made of a fluoropolymer.
- the formation method of the catalyst electrode layers 4 and 5 formed on the surface of the anion exchange membrane is the same as that in the case of using a cation exchange membrane. That is, a catalyst electrode layer is formed using a coating solution comprising an electrode catalyst, a binder made of an anion exchange resin, and a solvent, and this is joined to the anion exchange membrane by a hot press method.
- an anion exchange resin binder anion exchange resins obtained by amination of a chloromethylated copolymer of aromatic polyethersulfone and aromatic polythioethersulfone are disclosed (Patent Documents 1 and 2). ).
- a catalyst electrode sheet made of an electrode catalyst and a polytetrafluoroethylene binder is prepared, a binder made of an anion exchange resin is applied to the surface of the catalyst electrode sheet, and this is subjected to anion exchange.
- a method in which both are bonded by pressure bonding to a film is used as the binder.
- a polymer in which the terminal of a perfluorocarbon polymer having a sulfonic acid group is quaternized by treatment with diamine is used (Patent Document 3).
- anion exchange membranes use a reinforcing material in order to suppress fuel permeation and impart mechanical strength, or a cross-linking structure is imparted to the resin constituting the anion exchange membrane. is there.
- a resin material having a relatively high hardness such as an engineering plastic is used for the same purpose.
- an engineering plastic having a relatively high hardness is used for the binder made of an anion exchange resin used for forming the catalyst electrode layer.
- a binder made of an anion exchange resin a resin having a main structure of a fluorocarbon resin having a low affinity with a hydrocarbon anion exchange membrane is also used.
- the adhesion between the catalyst electrode layers 4 and 5 and the anion exchange resin diaphragm is poor, and poor adhesion tends to occur at this portion.
- the resistance at the interface between the two becomes high.
- the interface between the two is exposed to a fuel liquid.
- the adhesive strength between the two at this interface is likely to be reduced.
- both have different chemical structures, compositions, etc., there is a difference in the degree of swelling with respect to the fuel liquid. Therefore, adhesion failure tends to occur at this interface, and there is a problem that the anion exchange membrane and the catalyst electrode layer are finally peeled off.
- Patent Document 4 An anion exchange resin in which an anion exchange group is introduced into a hydrocarbon polymer elastomer is used as a binder for the catalyst electrode layer in order to improve the bondability between the hydrocarbon anion exchange membrane and the catalyst electrode layer.
- Patent Document 4 This document only discloses a method in which a catalyst electrode layer formed from the anion exchange resin and an electrode catalyst is bonded to an anion exchange membrane by hot pressing. However, the bondability is not sufficient.
- Japanese Patent Laid-Open No. 11-135137 Japanese Patent Laid-Open No. 11-273695 JP 2000-331693 A JP 2002-367626 A
- the present inventors have made various studies to solve the problem of reducing the hydroxide ion conductivity between the anion exchange resin diaphragm and the catalyst electrode layer due to peeling.
- the anion exchange resin membrane can function stably in water and organic liquid fuel, and further, it can improve the fuel impermeability and the mechanical strength of the diaphragm, It was found by the study by the researchers.
- an object of the present invention is to solve the above problem. That is, a membrane for a polymer electrolyte fuel cell, which operates stably for a long period of time while suppressing separation between the anion exchange resin membrane and the catalyst electrode layer, and has high hydroxide ion conductivity between the two, and the membrane
- Another object is to provide a membrane-electrode assembly manufactured using
- an adhesive layer made of an anion exchange resin having high flexibility, elasticity, and further having an anion exchange group between the anion exchange resin membrane and the catalyst electrode layer.
- I came up with the intervention.
- a highly crosslinked anion exchange resin membrane having a high hydroxide ion conductivity, a high fuel liquid permeation suppressing action, a high mechanical strength, a high hardness anion exchange resin membrane, and a catalyst It has been found that the electrode layer can be reliably bonded and problems such as peeling between the two can be solved.
- the hydroxide ion conductivity at the interface between the two is greatly improved.
- the reason why this hydroxide ion conductivity is greatly improved is currently being clarified.
- the present inventors consider that the surface of the catalyst electrode layer is in a state where the conductive carbon or the like carrying the catalyst protrudes from the surface of the catalyst layer and is relatively uneven.
- the adhesive layer made of the anion exchange resin is flexible, the adhesive layer is deformed and adhered along the irregularities on the surface of the catalyst electrode layer at the interface of the catalyst electrode layer. As a result, it is assumed that a sufficient contact state is realized between the two.
- a solid comprising a hydrocarbon-based anion exchange resin membrane in which an anion-exchange group is covalently bonded to a hydrocarbon-based resin, and an adhesive layer formed on at least one surface of the hydrocarbon-based anion exchange resin membrane.
- a hydrocarbon-based anion exchange resin membrane in which an anion-exchange group is covalently bonded to a hydrocarbon-based resin is a porous membrane and a hydrocarbon-based anion exchange filled in a void in the porous membrane.
- a membrane-catalyst electrode assembly formed by forming a catalyst electrode layer on at least one surface of the membrane for a polymer electrolyte fuel cell according to [1].
- a membrane-catalyst electrode assembly formed by forming a catalyst electrode layer on at least one surface of the membrane for a polymer electrolyte fuel cell according to [8].
- a polymer electrolyte fuel cell comprising the membrane-catalyst electrode assembly according to [9].
- a polymer electrolyte fuel cell comprising the membrane-catalyst electrode assembly according to [10].
- the diaphragm of the present invention achieves both high fuel ion conductivity, high fuel impermeability, particularly high fuel liquid impermeability, stability in water and liquid fuel, and high mechanical strength.
- This is a polymer electrolyte fuel cell diaphragm.
- the diaphragm of the present invention is excellent in bondability with the catalyst electrode layer. As a result, the hydroxide ion conductivity between the diaphragm and the catalyst electrode layer is high, and the high hydroxide ion conductivity can be maintained for a long time.
- the polymer electrolyte fuel cell using the diaphragm of the present invention can obtain a high battery output over a long period of time due to the excellent diaphragm characteristics.
- FIG. 2 shows an example of the configuration of the membrane for a polymer electrolyte fuel cell according to the first embodiment of the present invention (hereinafter sometimes simply referred to as a cell membrane).
- reference numeral 200 denotes a membrane for a polymer electrolyte fuel cell, and adhesive layers 204 and 206 are formed on both surfaces of a hydrocarbon-based anion exchange resin membrane 202, respectively.
- FIG. 3 shows another example of the membrane for a polymer electrolyte fuel cell of the present invention.
- reference numeral 300 denotes a battery diaphragm, and an adhesive layer 304 is formed only on one surface of a hydrocarbon-based anion exchange resin membrane 302.
- hydrocarbon anion exchange resin membranes 202 and 302 conventionally known hydrocarbon anion exchange resin membranes can be used without any limitation.
- anion exchange group include primary to tertiary amino groups, quaternary ammonium bases, pyridyl groups, imidazole groups, and quaternary pyridinium bases. Quaternary ammonium bases and quaternary pyridinium bases which are strongly basic groups are preferred.
- the anion exchange resin constituting the hydrocarbon-based anion exchange resin membrane is composed of a hydrocarbon-based polymer in which anion exchange groups are chemically bonded.
- This anion exchange resin is generally harder than a fluorine ion exchange resin.
- This anion exchange resin is, for example, an anion exchange resin in which an anion exchange group is introduced into a polystyrene material, an engineer represented by polysulfone, polyetherketone, polyetheretherketone, polybenzimidazole polymer, etc. Examples thereof include an anion exchange resin in which various functional groups are introduced into a plastic material as necessary.
- anion exchange resins used for fuel cell applications are insoluble in liquid fuels and water, and have a covalently crosslinked structure in the polymer structure from the viewpoint of reducing fuel permeability. Is preferred. Since this anion exchange resin has the crosslinked structure, the anion exchange resin becomes hard.
- a crosslinked structure by an ion complex is formed between a cationic functional group and an anionic functional group in the ion exchange resin membrane.
- the method is also effective.
- An anion exchange resin having a crosslinked structure by an ion complex also becomes hard, like an anion exchange resin having a covalent bond. Therefore, an anion exchange resin formed by further forming a crosslink by an ion complex in an anion exchange resin having a crosslink by a covalent bond is a harder resin.
- the hydrocarbon-based anion exchange resin is preferably one in which all main chains and side chains other than anion exchange groups are composed of hydrocarbons. Also included are anion exchange resins in which the majority of the chains are formed.
- an ether bond, an ester bond, an amide bond, a siloxane bond or the like may be interposed between the carbon-carbon bonds constituting the main chain and the side chain.
- a small amount of atoms such as oxygen, nitrogen, silicon, sulfur, boron and phosphorus derived from these bonds are contained. The amount is 40 mol% or less, preferably 10 mol% or less.
- the group other than the anion exchange group that may be bonded to the main chain and the side chain includes a small amount of halogen atoms such as chlorine, bromine, fluorine, iodine, or other substituents in addition to hydrogen. Also good.
- the amount of these atoms and substituents is preferably 40 mol% or less, more preferably 10 mol% or less, relative to the hydrogen.
- hydrocarbon-based anion exchange resins into a film
- methods such as cast molding of the anion exchange resins.
- a method using a base material also called a reinforcing material.
- a method using a substrate is a preferable method because it can further improve mechanical strength and dimensional stability and can impart flexibility.
- any base material known as a base material for ion exchange resin membranes can be used.
- a porous film, non-woven paper, woven fabric, non-woven fabric, paper, inorganic film and the like can be used without limitation.
- the material of these base materials include a thermoplastic resin composition, a thermosetting resin composition, an inorganic material, or a mixture thereof.
- thermoplastic resin composition is preferable from the viewpoint of easy production and high adhesion strength with a hydrocarbon-based anion exchange resin.
- thermoplastic resin composition include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 4-methyl-1-pentene, 5-methyl-1-heptene and the like.
- Polyolefin resins such as olefin homopolymers or copolymers; polyvinyl chloride diameters such as polyvinyl chloride, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinylidene chloride copolymers, vinyl chloride-olefin copolymers Resin; Fluorine such as polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-ethylene copolymer Diameter resin: Poly, such as nylon 6, nylon 66 Bromide resin, polyimide resin and the like.
- polyolefin resins are preferred because they are excellent in mechanical strength, chemical stability and chemical resistance and have particularly good affinity with hydrocarbon-based anion exchange resins.
- polyethylene or polypropylene resin is more preferable, and polyethylene resin is most preferable.
- a porous film made of polyolefin resin is preferable in terms of having a smooth surface and high adhesion to the catalyst electrode layer, and high strength, and a porous film made of polyethylene resin is particularly preferable. preferable.
- the average pore diameter of the porous film used as the base material of such an ion exchange resin membrane is preferably 0.005 to 5.0 ⁇ m, more preferably 0.01 to 2.0 ⁇ m, and 0.015 to 0 .4 ⁇ m is most preferred.
- the porosity (also referred to as porosity) of the polyolefin resin porous membrane is preferably 20 to 95%, more preferably 30 to 90%, and most preferably 30 to 65% for the same reason as the average pore diameter.
- the air permeability (JIS P-8117) is preferably 1500 seconds or less, particularly preferably 1000 seconds or less.
- the thickness is preferably 3 to 200 ⁇ m, more preferably 3 to 40 ⁇ m, and particularly preferably 8 to 20 ⁇ m. By making this thickness of the substrate, the resulting anion exchange resin membrane is thin and maintains sufficient strength.
- the porous film can be produced by the method described in, for example, JP-A-9-216964, JP-A-9-235399, JP-A-2002-338721, and the like.
- commercially available products for example, Asahi Kasei Chemicals “Hypore”, Ube Industries “Yupor”, Tonen Tapils “Setera”, Nitto Denko “Exepor”, etc. are also available.
- the hydrocarbon-based anion exchange resin membrane may be blended with other components such as a plasticizer and an inorganic filler as long as the function of the present invention is not impaired.
- the hydrocarbon-based anion exchange resin membrane used in the present invention may be produced by any method, but in general, it is preferably produced by the following method.
- the above-mentioned monomer composition comprising a polymerizable monomer having an anion exchange group or capable of introducing an anion exchange group and a bi- or higher functional crosslinkable polymerizable monomer is described above. Impregnated in the void portion. Next, the above monomer composition is polymerized. Thereafter, ion exchange groups are introduced as necessary.
- polymerizable monomers capable of introducing an anion exchange group in the monomer composition include styrene, ⁇ -methylstyrene, vinyltoluene, 2,4-dimethylstyrene, p-tert- Examples thereof include monofunctional polymerizable monomers such as butyl styrene, ⁇ -halogenated styrene, chloromethyl styrene, vinyl naphthalene, vinyl pyridine, vinyl imidazole, and other vinyl compounds.
- polymerizable monomer having an anion exchange group examples include amine monomers such as vinylbenzyltrimethylamine and vinylbenzyltriethylamine, nitrogen-containing heterocyclic monomers such as vinylpyridine and vinylimidazole, salts and esters thereof. Examples are shown.
- styrene, ⁇ -methylstyrene, vinyltoluene, 2,4-dimethylstyrene, p-tert-butylstyrene, ⁇ -halogen are easy to introduce strongly basic anion exchange groups.
- Monofunctional aromatic vinyl compounds such as fluorinated styrene, chloromethylstyrene and vinylnaphthalene, and nitrogen-containing compounds such as vinylpyridine are preferred.
- chloromethylstyrene and vinylpyridine are most preferred because the anion exchange group density in the anion exchange membrane can be increased.
- polyfunctional crosslinkable polymerizable monomer having two or more functions generally a bifunctional or trifunctional monomer is used.
- polyfunctional aromatic vinyl compounds such as divinylbenzene, divinylbiphenyl, and trivinylbenzene
- polyfunctional (meth) acrylic acid such as trimethylolmethanetrimethacrylate, methylenebisacrylamide, and hexamethylenedimethacrylamide Derivatives
- other polyfunctional polymerizable monomers such as butadiene, chloroprene, and divinyl sulfone.
- polyfunctional aromatic vinyl compounds such as divinylbenzene, divinylbiphenyl, and trivinylbenzene are preferable.
- the content of the crosslinkable polymerizable monomer in the polymerizable composition is not particularly limited, but is preferably 0.5 to 40% by mass of the total amount of polymerizable monomers contained in the polymerizable composition. 1 to 25% by mass is more preferable.
- the monomer composition preferably contains a polymerization initiator in order to polymerize the polymerizable monomer.
- the polymerization initiator is not particularly limited as long as it is a polymerization initiator capable of polymerizing the polymerizable monomer.
- Specific examples of the polymerization initiator include octanoyl peroxide, lauroyl peroxide, t-butylperoxy-2-ethylhexanoate, benzoyl peroxide, t-butylperoxyisobutyrate, t-butylperoxylaur Examples thereof include organic peroxides such as rate, t-hexyl peroxybenzoate, and di-t-butyl peroxide.
- the blending amount of the polymerization initiator is within a known range used for the polymerization of the polymerizable monomer. Generally, it is 0.01 to 10 parts by mass with respect to 100 parts by mass of the polymerizable monomer.
- the monomer composition may contain a solvent as necessary, and may further contain known additives such as a plasticizer, an organic or inorganic filler.
- a plasticizer such as ethylene glycol dimethacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacrylate, polymethyl methacryl
- the monomer composition and the substrate are brought into contact with each other to fill the monomer composition in the pores of the substrate.
- Examples of the contact method include a method in which the monomer composition is applied or sprayed onto a substrate, or a method in which the substrate is immersed in the monomer composition.
- the method by dipping is particularly preferable in terms of easy production.
- the immersion time varies depending on the type of the substrate and the composition of the monomer composition. In general, the immersion time is 0.1 second to a few dozen minutes.
- a known polymerization method can be employed without limitation.
- polymerization is performed by heating using a polymerization initiator composed of the peroxide. This method is preferable because it is easy to operate and can be relatively uniformly polymerized.
- cover with a film excess monomer composition is excluded from the substrate. As a result, a thin and uniform anion exchange resin membrane can be obtained.
- the polymerization temperature in the case of polymerizing by thermal polymerization is not particularly limited, and known conditions may be appropriately selected. In general, the polymerization temperature is 50 to 150 ° C, preferably 60 to 120 ° C. In addition, when a solvent is contained in the monomer composition, the solvent may be removed prior to polymerization.
- the film-like polymer obtained by polymerizing the monomer composition filled in the voids of the substrate is the hydrocarbon used in the present invention as it is. It can be used as a system anion exchange resin membrane.
- an anion exchange group is further introduced into the membrane-like product.
- the method for introducing the anion exchange group is not particularly limited, and a known method such as amination or alkylation can be appropriately employed.
- chloromethylstyrene when used as a monofunctional polymerizable monomer, it can be derived into an anion exchange resin membrane having a quaternary ammonium base by contacting the membrane-like polymer with an amination product such as trimethylamine.
- vinyl pyridine when vinyl pyridine is used as a monofunctional polymerizable monomer, it can be derived into an anion exchange resin membrane having a quaternary pyridinium base by contacting the membrane polymer with a halogenoalkyl such as methyl iodide. .
- anion exchange resin membrane using a monofunctional polymerizable monomer having an anion exchange group
- anion exchange groups are further introduced into the obtained film-like polymer to obtain an anion exchange.
- the group content may be further increased.
- the present inventors diligently studied the structure or properties of the anion exchange resin membrane and the anion exchange resin. As a result, the following knowledge was obtained. That is, carbon dioxide in the air is absorbed by an anion exchange membrane and an anion exchange resin (a hydroxide ion type anion exchange membrane and the same resin) whose counterion species are hydroxide ions. The absorbed carbon dioxide quickly reacts with the hydroxide ion of the counter ion species to be converted to carbonate ion, and becomes a counter ion of the anion exchange group. This carbonate ion then changes to bicarbonate ion. However, during power generation of the fuel cell, hydroxide ions are generated by the catalytic reaction of the fuel cell.
- an anion exchange resin a hydroxide ion type anion exchange membrane and the same resin
- the carbonate ions and / or bicarbonate ions which are counter ions, are substituted (ion exchange) by the generated hydroxide ions.
- carbonate ions and / or bicarbonate ions are released out of the system as carbon dioxide gas. Therefore, even when part or all of the anion exchange membrane and the counter ion species (hydroxide ions) of the resin are replaced with carbonate ions and / or bicarbonate ions, Since the ions become hydroxide ions, they can be used as a fuel cell without problems.
- the hydrocarbon-based anion exchange resin membrane obtained by the above method varies depending on the monomer composition used, the anion exchange group, and the type of the substrate, but usually in a 0.5 mol / L-sodium chloride aqueous solution.
- the membrane resistance is 0.005 ⁇ 1.5 ⁇ ⁇ cm 2, preferably 0.01 ⁇ 0.8 ⁇ ⁇ cm 2, more preferably 0.01 ⁇ 0.5 ⁇ ⁇ cm 2. It is practically difficult to make the film resistance less than 0.005 ⁇ cm 2 . When the membrane resistance exceeds 1.5 ⁇ cm 2 , the power generation efficiency is deteriorated, which is disadvantageous as a fuel cell diaphragm.
- the anion exchange capacity of the hydrocarbon-based anion exchange resin membrane is preferably maintained at 0.2 to 3.0 mmol / g, 0.5 to 2.5 mmol / g is more preferable.
- the water content of the hydrocarbon-based anion exchange resin membrane is 7% by mass or more, preferably 10% by mass or more. In general, when air is supplied as an oxidizing agent as it is, the moisture content is maintained at about 7 to 90% by mass. In order to control the water content in such a range, the type of ion exchange group, ion exchange capacity, and degree of crosslinking of the hydrocarbon-based anion exchange resin membrane may be controlled. When the water content is less than 7% by mass, the resin film is dried and the conductivity of hydroxide ions is reduced.
- the thickness of the hydrocarbon-based anion exchange resin membrane is preferably from 3 to 200 ⁇ m, more preferably from 5 to 40 ⁇ m, from the viewpoint of keeping the membrane resistance low and providing the mechanical strength necessary for the support membrane.
- the burst strength is preferably 0.08 to 1.0 MPa, more preferably 0.1 MPa or more. When the burst strength is less than 0.08 MPa, the mechanical strength is insufficient. As a result, when the hydrocarbon-based anion exchange resin membrane is incorporated as a diaphragm into a fuel cell, the diaphragm may crack. Furthermore, pinholes may occur in the diaphragm due to the ends of carbon fibers that may protrude from the carbon paper normally used as a gas diffusion electrode.
- the burst strength can generally be produced up to an upper limit of 1.0 MPa. In order to operate the fuel cell stably over a long period of time, the burst strength is preferably 0.1 MPa or more.
- the adhesive layers 204, 206, and 304 are laminated on at least one surface of the hydrocarbon-based anion exchange resin membrane, and are integrated with the exchange membrane.
- the thickness of the adhesive layer is preferably from 0.1 to 20 ⁇ m, more preferably from 1 to 10 ⁇ m.
- the adhesive layer is made of a soft anion exchange resin for adhesive layer (hereinafter also referred to as “adhesive layer resin”) that is soft and has a Young's modulus at 25 ° C. of 1 to 1000 (MPa).
- the Young's modulus is measured by the following method. First, a cast film of the adhesive layer resin is prepared, and this is allowed to stand in an atmosphere of 25 ° C. and 60% RH for 24 hours or more to adjust the humidity. Next, a curve showing the relationship between the stress and strain of the cast film is obtained using the tensile tester under the atmosphere. The Young's modulus of the adhesive layer resin is calculated from the slope of the first straight line portion of this curve.
- the Young's modulus at 25 ° C. and 60% RH of the adhesive layer resin is 1 to 1000 (MPa), preferably 3 to 300 (MPa). Under these conditions, by forming an adhesive layer with an elastomer in the range of this Young's modulus, the fuel cell has high hydroxyl ion conductivity, high mechanical strength, and sufficient fuel liquid impermeability under the operating conditions of the fuel cell. In addition, it is possible to obtain a battery diaphragm that is stable against peeling of the catalyst electrode layer.
- the adhesive layer resin is preferably an anion exchange resin in which all parts other than the anion exchange group are composed of hydrocarbons.
- the adhesive layer resin may be a hydrocarbon polymer in which most of the main chain and side chain are formed of carbon and hydrogen.
- an ether bond, an ester bond, an amide bond, a siloxane bond, etc. may be interposed between the carbon-carbon bonds constituting the main chain and the side chain, and oxygen, nitrogen,
- a small amount of atoms such as silicon, sulfur, boron, and phosphorus may be contained.
- Their content is 40 mol% or less, preferably 10 mol% or less.
- the group other than the anion exchange group that may be bonded to the main chain and the side chain may be a small amount of atoms such as chlorine, bromine, fluorine, iodine, or other substituents other than hydrogen. .
- the amount of these atoms and substituents is preferably 40 mol% or less, more preferably 10 mol% or less of the hydrogen.
- hydrocarbon polymer constituting the main chain of the adhesive layer resin examples include a block copolymer or a random copolymer of an aromatic vinyl compound and a conjugated diene compound, or a conjugated diene portion of the block copolymer.
- a block copolymer or a random copolymer in which the double bond in the main chain is partially or completely saturated by adding is preferable.
- an adhesive layer resin may be produced by introducing an anion exchange group into these elastomers.
- examples of the block form examples include a diblock copolymer, a triblock copolymer, and a multiblock copolymer. Among these, a triblock copolymer is preferable.
- the content of the aromatic vinyl compound unit in the block copolymer or random copolymer is not particularly limited, but is preferably 5 to 70% by mass, more preferably 10 to 50% by mass. By setting the content of the aromatic vinyl compound monomer within this range, the electrical properties and mechanical properties of the resin after introducing the anion exchange group become desired.
- the average molecular weight of the obtained block copolymer or random copolymer is preferably 5,000 to 300,000, more preferably 10,000 to 150,000.
- the styrene-based elastomer can be obtained by copolymerizing an aromatic vinyl compound and a conjugated diene compound by a known method such as anionic polymerization, cationic polymerization, coordination polymerization, or radical polymerization.
- a styrenic elastomer produced by living anionic polymerization is preferred.
- the hydrogenation rate is preferably 95% or more.
- styrenic elastomer examples include polystyrene-polybutadiene-polystyrene triblock copolymer (SBS), polystyrene-polyisoprene-polystyrene triblock copolymer (SIS), random copolymer of styrene and butadiene, styrene and propylene. Of the random copolymer.
- SEBS polystyrene-poly (ethylene-butylene) -polystyrene triblock copolymer
- SEPS polystyrene-poly (ethylene-propylene) -polystyrene triblock
- polystyrene-poly (ethylene-butylene) -polystyrene triblock copolymer SEBS
- SEBS polystyrene-poly (ethylene-butylene) -polystyrene triblock copolymer
- SEPS polystyrene triblock copolymer
- An anion exchange group is appropriately introduced into the hydrocarbon polymer constituting the elastomer by a known method.
- a method of introducing a chloromethyl group into the aromatic ring, then aminating the introduced chloromethyl group, and further deriving to a quaternary ammonium base Is preferably exemplified.
- Any anion exchange group can be used in the form of a hydroxide ion by ion exchange.
- the anion exchange group bonded to the adhesive layer resin can be selected without particular limitation as long as it is a functional group having a positive charge and a function of conducting hydroxide ions.
- Specific examples include primary to tertiary amino groups, quaternary ammonium bases, pyridyl groups, imidazole groups, quaternary pyridinium bases, and quaternary imidazolium bases.
- a quaternary ammonium base or a quaternary pyridinium base is preferable because the conductivity of the hydroxide ion in the adhesive layer can be increased.
- These anion exchange groups may be used alone or in combination of two or more.
- a cation exchange group and an anion exchange group may coexist. In this case, the anion exchange group is made to occupy a majority.
- the anion exchange capacity of the adhesive layer resin is preferably from 0.1 to 5.0 mmol / g, and more preferably from 0.5 to 3.0 mmol / g so that good ion conductivity can be maintained.
- an anion exchange amount is preferably 0.5 to 2.5 mmol / g because it dissolves in water if the anion exchange capacity is high.
- the adhesive layer resin is soluble in water, the adhesive layer resin is eluted out of the battery system during power generation, or the bondability between the anion exchange membrane and the catalyst electrode layer deteriorates, and stable power supply performance May not be maintained.
- the adhesive layer resin is preferably hardly soluble in water.
- being sparingly soluble in water means that the solubility in water at 20 ° C. is less than 1% by mass, preferably less than 0.8% by mass.
- the solubility in water is larger than the above value, the adhesive layer resin is eluted more than acceptable from the gas diffusion electrode during power generation of the fuel cell.
- the adhesive layer resin is preferably hardly soluble in the liquid fuel to be used.
- liquid fuel methanol and ethanol are generally used. Compared to many other liquid fuels, methanol and ethanol easily dissolve the adhesive layer resin, so if the adhesive layer resin is poorly soluble in methanol and ethanol, the solubility in other liquid fuel systems is also low. It can be judged.
- “Slightly soluble in methanol and ethanol” means that both the solubility in methanol and ethanol at 20 ° C. is less than 1% by mass, preferably less than 0.8% by mass. When the solubility in methanol and ethanol is larger than the above values, the adhesive layer resin is eluted more than acceptable from the gas diffusion electrode during power generation of the fuel cell.
- the adhesive layer resin having the above physical properties may be appropriately selected from those conventionally known as anion exchange resins, in addition to those having the above-described styrene elastomer in the main chain. Or you may synthesize
- the solubility characteristics in an organic solvent or water can be adjusted by selecting a monomer to be polymerized, the degree of crosslinking, the amount of cation exchange groups introduced, the degree of polymerization of the resin, and the like. In general, it is preferable to adjust the degree of crosslinking.
- the degree of crosslinking can be adjusted by increasing or decreasing the addition amount of the crosslinkable monomer, or by designing the molecule so that a polymer chain or segment having a strong cohesive force forms a physical crosslinking point.
- These adhesive layer resins are prepared by adjusting a monomer having an anion exchange group and, if necessary, a small amount of a crosslinkable monomer so that the solubility characteristics in water, methanol and ethanol satisfy the above-mentioned conditions. It can be produced by polymerization or condensation. Alternatively, a monomer capable of introducing an anion exchange group and, if necessary, a small amount of a crosslinkable monomer, preferably adjusted so that the solubility characteristics in water, methanol and ethanol satisfy the above-mentioned conditions, It can be produced by polymerizing or condensing to obtain a hydrocarbon polymer, and then subjecting the functional group capable of introducing an anion exchange group to an anion exchange group introduction treatment.
- Examples of the monomer having a functional group capable of introducing an anion exchange group include aromatic vinyl compounds such as styrene, ⁇ -methylstyrene, chloromethylstyrene, vinylpyridine, vinylimidazole, and vinylnaphthalene. Of these, styrene, ⁇ -methylstyrene, and chloromethylstyrene are preferable in view of ease of introduction of an anion exchange group.
- amine monomers such as vinylbenzyltrimethylamine and vinylbenzyltriethylamine, nitrogen-containing heterocyclic monomers such as vinylpyridine and vinylimidazole, salts and esters thereof, etc. Is exemplified.
- the crosslinkable polymerizable monomer is not particularly limited, but divinylbenzenes, divinylsulfone, butadiene, isoprene, chloroprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene.
- polyfunctional vinyl compounds such as divinylbiphenyl and trivinylbenzene, and polyfunctional methacrylic acid derivatives such as trimethylolmethanetrimethacrylic acid ester, methylenebisacrylamide and hexamethylenedimethacrylamide.
- the amount used is generally a monomer having a functional group into which an anion exchange group can be introduced, or a monomer 100 having an anion exchange group.
- the amount is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 1 part by mass with respect to parts by mass.
- the use amount of the crosslinkable polymerizable monomer is less than 0.01 parts by mass, the obtained adhesive layer resin is easily soluble in water, methanol and ethanol.
- crosslinked polymerizable monomer exceeds 5 mass parts, it becomes insoluble in an organic solvent and handling property worsens.
- the monomer having an anion exchange group or a crosslinkable monomer can be copolymerized with these monomers as necessary.
- Other monomers and plasticizers may be added.
- Other monomers include ethylene, propylene, butylene, styrene, acrylonitrile, methyl styrene, acrolein, methyl vinyl ketone, vinyl biphenyl and other vinyl compounds, butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl- Examples thereof include conjugated diene compounds such as 1,3-butadiene.
- the amount used is preferably 0 to 100 parts by mass with respect to 100 parts by mass of the monomer having a functional group into which an anion exchange group can be introduced or the monomer having an anion exchange group.
- plasticizers examples include dibutyl phthalate, dioctyl phthalate, dimethyl isophthalate, dibutyl adipate, triethyl citrate, acetyl tributyl citrate, dibutyl sebacate and the like.
- the amount of the plasticizer used is preferably 0 to 50 parts by mass with respect to 100 parts by mass of the monomer having a functional group capable of introducing an anion exchange group or the monomer having an anion exchange group.
- a method for polymerizing a monomer composition comprising the above monomer or crosslinkable monomer
- known methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization are employed. Which production method is selected depends on the composition of the monomer composition and the like, and is appropriately determined.
- the average molecular weight is from 5,000 to 1,000,000, preferably from 10,000 to 200,000.
- the polymerization conditions are selected.
- the same method as described in the method for producing the hydrocarbon-based anion exchange resin membrane is used.
- An anion exchange group is introduced into the resin obtained by polymerization.
- the counter ion of the obtained anion exchange resin is ion-exchanged with a hydroxide ion.
- the adhesive layer resin is used as an adhesive layer.
- the bonding strength between the catalyst electrode layer and the hydrocarbon-based anion exchange resin diaphragm is dramatically improved.
- the hydroxide ion conductivity at these interfaces is greatly improved.
- the durability of the fuel cell in long-term use is greatly improved.
- the adhesive layer resin can be dissolved in at least one organic solvent other than the above methanol and ethanol for the convenience of manufacturing the adhesive layer.
- the solvent for the adhesive layer resin is not particularly limited and may be appropriately selected depending on the weight average molecular weight and structure of the anion exchange resin to be dissolved.
- the solvent is preferably a low-melting polar solvent, specifically, a polar solvent having a melting point of 20 ° C. or lower and a dielectric constant of 15 or higher.
- examples of the solvent include 1-propanol, 2-propanol, N-butanol, tert-amyl alcohol, methyl ethyl ketone, acetonitrile, nitromethane, dimethyl sulfoxide, N-methylpyrrolidone, N, N-dimethylformamide, N, Examples thereof include N-dimethylacetamide and tetrahydrofuran.
- the polar solvent and 1,2-dichloromethane, trichloroethane, toluene, xylene, etc. You may mix and use a nonpolar solvent.
- the organic solvent to be used is water-soluble, it may be mixed with water as long as the solubility in the adhesive layer resin is not impaired.
- soluble in an organic solvent means that the saturated solubility of the dry resin is 1% by mass or more, preferably 3% by mass or more at 20 ° C. under atmospheric pressure.
- the adhesive layer resin can be dissolved by selecting a solvent that can be dissolved by heating or pressurization, or once it is made into a solution using a soluble solvent, When the solution can be obtained by solvent substitution with another solvent by a known method, the resin can be used for forming an adhesive layer.
- the fuel cell membrane of the present invention has an adhesive layer composed of the above adhesive layer resin formed on at least one surface of a hydrocarbon-based anion exchange resin membrane.
- the method for forming the adhesive layer on at least one surface of the hydrocarbon-based anion exchange resin is not particularly limited.
- an adhesive layer resin thin film is formed on a sheet by applying an adhesive layer resin solution to a polytetrafluoroethylene sheet in advance and then drying it.
- this thin film is transferred to a crosslinked anion exchange resin film by a method such as hot pressing.
- an adhesive layer resin solution is brought into contact with a hydrocarbon-based anion exchange resin membrane and then dried.
- concentration of the adhesive layer resin solution used for forming the adhesive layer is not particularly limited, but is generally preferably 0.01 to 10% by mass, more preferably 0.05 to 5% by mass.
- the method of contact between the adhesive layer resin solution and the hydrocarbon-based anion exchange resin membrane is not particularly limited, and the adhesive layer resin solution is applied to the hydrocarbon-based anion exchange resin membrane, sprayed, or
- a method of immersing a hydrocarbon-based anion exchange resin membrane in an adhesive layer resin solution is exemplified. From the viewpoint of easy production, a method by dipping or a method by coating is preferred. In the case of immersion, the immersion time is generally preferably 1 minute to 24 hours. In the case of the immersion method, usually an adhesive layer is formed on both surfaces of the hydrocarbon-based anion exchange resin membrane at once.
- the hydrocarbon-based anion exchange resin membrane brought into contact with the adhesive layer resin solution is taken out of the solution, and the solvent is dried.
- the drying method is not particularly limited, and it is usually dried at 0-100 ° C. for 1 minute to 5 hours. In order to sufficiently dry, hot air or the like may be blown or dried under reduced pressure, or may be dried in an inert atmosphere such as argon or nitrogen. Further, when drying, the hydrocarbon anion exchange resin membrane is fixed horizontally to the frame so that the solvent removal does not occur unevenly and the adhesion amount of the adhesive layer resin does not become uneven. It is preferable to dry while applying tension.
- the adhesive layer resin solution is applied in advance to the surface where the catalyst electrode layer contacts the diaphragm and dried. Thereafter, by bonding the catalyst electrode layer to the hydrocarbon-based anion exchange resin membrane, the adhesive layer can be formed between the polymer electrolyte fuel cell membrane and the catalyst electrode layer.
- the adhesive layer resin solution may penetrate into the catalyst electrode layer and the resin may cover the catalyst more than necessary. In this case, the catalyst active area is reduced. Therefore, it is desirable to form the adhesive layer on the hydrocarbon-based anion exchange resin membrane.
- the membrane for a polymer electrolyte fuel cell of the present invention comprising the hydrocarbon-based anion exchange resin membrane and the adhesive layer formed on at least one surface of the hydrocarbon-based anion exchange resin membrane is obtained.
- the counter ion of the hydrocarbon-based anion exchange resin membrane and the adhesive layer resin of the first membrane-type membrane for a polymer electrolyte fuel cell is a hydroxide ion or a hydroxyl ion of the hydroxide ion.
- the carbonate ions and / or bicarbonate ions are exchanged. Therefore, before using this diaphragm in a fuel cell, it is preferable to immerse this diaphragm in an aqueous solution such as potassium hydroxide to ensure that the counter ion is of the hydroxide ion type.
- both the hydrocarbon-based anion exchange membrane and the adhesive layer resin are manufactured without using the hydroxide ion type, and then the obtained membrane is immersed in an aqueous solution of potassium hydroxide or the like. Ions may be converted to the hydroxide ion type at once.
- FIG. 4 shows an example of the configuration of the membrane for a polymer electrolyte fuel cell of the second membrane type of the present invention.
- 400 is a polymer electrolyte fuel cell membrane, and intermediate layers 408 and 410 are formed on both surfaces of a hydrocarbon-based anion exchange resin membrane 402, respectively. Further, an adhesive layer is formed on the surfaces of the intermediate layers 408 and 410. 404 and 406 are formed. That is, intermediate layers 408 and 410 are formed between the hydrocarbon-based anion exchange resin film 402 and the adhesive layers 404 and 406, respectively.
- FIG. 5 shows another example of the membrane for the polymer electrolyte fuel cell of the second membrane type according to the present invention.
- 500 is a diaphragm, and an adhesive layer 504 is formed only on one surface of a hydrocarbon-based anion exchange resin membrane 502, and an intermediate layer 508 is formed between the anion exchange resin membrane 502 and the adhesive layer 504. Yes.
- the hydrocarbon-based anion exchange resin membranes 402 and 502 and the adhesive layers 404, 406, and 504 are the same as those described in the first diaphragm configuration, and thus description thereof is omitted. .
- the intermediate layer resin constituting the intermediate layers 408, 410, and 508 is made of a cation exchange resin.
- an intermediate layer is formed on at least one surface of a hydrocarbon-based anion exchange resin membrane used as a solid polymer electrolyte membrane.
- This intermediate layer is made of a cation exchange resin having a cation exchange group having a polarity opposite to that of the anion exchange group of the exchange resin membrane.
- an adhesive layer made of a soft anion exchange resin is formed on the surface of the intermediate layer.
- the anion exchange group possessed by the anion exchange resin membrane and the cation exchange group possessed by the intermediate layer formed on the surface of the anion exchange resin membrane have opposite polarities. Accordingly, these ion exchange groups having opposite polarities form an ionic bond at the interface between the two. As a result, the anion exchange resin film and the intermediate layer are bonded to each other more firmly by adding an adhesive force due to ionic bonds in addition to an adhesive force due to normal affinity.
- the adhesive layer laminated on the intermediate layer having a cation exchange group has an anion exchange group. Accordingly, a strong ionic bond is formed between the cation exchange group of the intermediate layer and the anion exchange group of the adhesive layer as described above. As a result, the intermediate layer and the adhesive layer are firmly bonded by an adhesive force due to ionic bonds in addition to an adhesive force due to normal affinity.
- the anion exchange resin film and the adhesive layer are strongly bonded to each other through the intermediate layer, and the occurrence of peeling between the two is strongly suppressed.
- a proton type conventionally known as a cation exchange resin such as perfluorocarbon sulfonic acids such as Nafion (trade name) manufactured by DuPont, or a hydrocarbon cation exchange resin.
- a hydrocarbon cation exchange resin is preferable because of its good affinity with the hydrocarbon anion exchange membrane.
- the hydrocarbon-based cation exchange resin is preferably one in which all parts other than the cation exchange group are composed of hydrocarbons.
- the main chain and side chain of carbon and hydrogen are used. Most of them may be formed.
- the hydrocarbon polymer has an ether bond, an ester bond, an amide bond, a siloxane bond, etc. interposed between the carbon-carbon bonds constituting the main chain and the side chain, and oxygen, nitrogen, silicon, sulfur derived from these bonds, A small amount of atoms such as boron and phosphorus may be contained. The amount is 40 mol% or less, preferably 10 mol% or less.
- the group other than the cation exchange group that may be bonded to the main chain and the side chain may be a small amount of atoms such as chlorine, bromine, fluorine, iodine, or other substituents other than hydrogen. good.
- the amount of these atoms and substituents is preferably 40 mol% or less, more preferably 10 mol% or less of the hydrogen.
- the cation exchange group is not particularly limited, and examples thereof include a sulfonic acid group, a carboxylic acid group, and a phosphonic acid group.
- a weakly acidic group is preferable and a carboxylic acid group is most preferable because it easily forms an ionic bond strongly with an anion exchange group.
- These cation exchange groups may be used alone or in combination of two or more. Furthermore, a cation exchange group and an anion exchange group may be combined. In this case, a majority of cation exchange groups are used.
- the method for forming the intermediate layer made of the cation exchange resin is not particularly limited, and any method may be used. Specifically, the following method is exemplified.
- a cation exchange resin solution as an intermediate layer is applied to a polytetrafluoroethylene sheet and then dried to form a thin film of the cation exchange tree on the sheet surface.
- the thin film formed on the sheet surface is transferred to the anion exchange resin film by a method such as hot pressing to form an intermediate layer.
- an adhesive layer is formed on the surface of the formed intermediate layer.
- the cation exchange resin solution is brought into contact with at least one surface of the above-described hydroxide ion type anion exchange resin membrane, and then dried, so that the cation exchange resin serving as an intermediate layer becomes an anion exchange resin membrane. It is the method of making it adhere.
- the amount of adhesion of the intermediate layer is controlled by the concentration of the cation exchange resin solution used in the adhesion process It can be controlled by adjusting the contact time to the substrate, and the cleaning conditions after the adhesion.
- the solvent for dissolving the cation exchange resin is not particularly limited.
- the solvent may be appropriately selected according to the weight average molecular weight and chemical structure of the cation exchange resin to be dissolved.
- Specific examples of solvents that can be used include alcohols such as methanol, ethanol, 1-butanol and 2-ethoxyethanol, aliphatic hydrocarbons such as hexane, cyclohexane, heptane and 1-octane; fatty acids such as octanoic acid.
- Amines such as dimethyloctylamine; aromatic hydrocarbons such as toluene, xylene and naphthalene; ketones such as acetone, cyclohexanone and methyl ethyl ketone; ethers such as dibenzyl ether and diethylene glycol dimethyl ether; methylene chloride, chloroform and ethylene Halogenated hydrocarbons such as bromide; dimethyl phthalate, dioctyl phthalate, dimethyl isophthalate, dibutyl adipate, triethyl citrate, acetyl tributyl citrate, dibutyl sebacate, etc. Alcohol esters and alkylphosphoric acid esters of aromatic acids and aliphatic acid, and the like; and the like water.
- the cation exchange resin solution is brought into contact with the anion exchange resin membrane that has been subjected to the ion exchange treatment of the counter ion to the hydroxide ion type.
- This contact method is not particularly limited. Specifically, a method of coating or spraying the cation exchange resin solution on the anion exchange resin membrane or immersing the anion exchange resin membrane in the cation exchange resin solution is exemplified. A contact method by coating or dipping is particularly preferable in terms of easy production. In the case of the contact method by immersion, the immersion time varies depending on the type of anion exchange resin membrane or cation exchange resin, the concentration of the cation exchange resin solution, and the solvent.
- the anion exchange group of the anion exchange resin membrane and the cation exchange group of the cation exchange resin form an ionic bond, and the cation exchange resin is formed on the surface of the anion exchange resin membrane.
- the anion exchange resin membrane brought into contact with the cation exchange resin solution is taken out from the solution and, if necessary, dried to remove the solvent.
- the solvent in which the cation exchange resin is dissolved is a solvent having a high dielectric constant, or when the cation exchange resin has a high solubility in the solvent, the anion exchange group of the anion exchange resin membrane and the cation exchange resin In some cases, ion pairing with the cation exchange group is insufficient. In this case, the ion pair formation can be promoted by drying the anion exchange resin membrane brought into contact with the cation exchange resin solution.
- the drying method is not particularly limited, and may be dried by allowing to stand at 0 to 100 ° C. for 1 minute to 5 hours depending on the concentration of the cation exchange resin solution used and the solvent. In order to sufficiently dry, hot air may be blown or dried under reduced pressure. You may dry in inert atmosphere, such as argon and nitrogen. In drying, it is preferable to dry the anion exchange resin membrane in contact with the cation exchange resin solution while applying tension. The tension can be applied by a method such as fixing the anion exchange resin membrane brought into contact with the solution to the frame. When this tension is not applied, the solvent is removed unevenly, and the cation exchange resin tends to adhere unevenly to the anion exchange resin membrane surface.
- a part of the cation exchange resin attached to the anion exchange resin membrane surface by the above attachment method may not form an ion pair with the anion exchange group of the anion exchange resin membrane.
- the cation exchange resin covers the catalyst of the catalyst electrode layer. Poisoning may reduce the fuel cell output. Furthermore, this cation exchange resin may increase the internal resistance of the fuel cell.
- the anion exchange resin membrane having the cation exchange resin adhered to the surface using a solvent.
- the cation exchange resin that does not form an ion pair with the anion exchange group of the anion exchange resin membrane is dissolved out.
- the cation exchange resin forming the ion pair does not elute because it is firmly fixed to the anion exchange resin membrane by ionic bonds.
- the solvent used for washing is not particularly limited as long as it is a solvent that can dissolve the attached cation exchange resin.
- the solvent is appropriately selected according to the weight average molecular weight and chemical structure of the cation exchange resin. Specifically, the solvent used for preparation of the said cation exchange resin solution can be illustrated.
- the washing method is not particularly limited, but from the viewpoint of simplicity of operation, a method of washing by immersing an anion exchange resin film in which a cation exchange resin is attached to the solvent in a solvent is preferable.
- the cleaning conditions by immersion it may be preferably immersed in a solvent at 0 to 100 ° C. for 10 minutes to 24 hours. Furthermore, in order to increase the cleaning efficiency, a method of repeating immersion 2 to 5 times while exchanging the solvent with a new solvent is preferable. In this case, the total immersion time is preferably 10 minutes to 10 hours.
- the anion exchange resin membrane is taken out from the soaking solvent and dried to remove the solvent.
- the drying method is not particularly limited as long as the solvent does not substantially remain in the obtained fuel cell diaphragm. For example, drying is performed by allowing to stand at 0 to 100 ° C. for 1 minute to 5 hours depending on the type of the washing solvent.
- hot air etc. may be sprayed on an anion exchange resin membrane, or it may dry under reduced pressure.
- anion exchange resin membrane with an intermediate layer having a cation exchange resin attached to the surface.
- tension By adopting a method such as fixing the anion exchange resin membrane with an intermediate layer to a frame, tension can be applied to the anion exchange resin membrane with an intermediate layer.
- the weight average molecular weight of the cation exchange resin is preferably 8,000 to 1,000,000.
- the cation exchange resin having a weight average molecular weight of less than 8000 tends to penetrate the inside of the anion exchange resin membrane in the step of attaching the cation exchange resin to the anion exchange resin membrane. As a result, the density of cation exchange groups present on the surface of the anion exchange resin membrane is reduced. As a result, the electrostatic attractive force between the intermediate layer made of the cation exchange resin and the anion exchange resin film or the anion exchange group in the adhesive layer is weakened, and the resulting fuel cell diaphragm and the adhesive layer are joined. The property becomes insufficient.
- the weight average molecular weight of the cation exchange resin is more preferably 20,000 or more, particularly preferably 30,000 or more, and most preferably 100,000 or more.
- a cation exchange resin having a weight average molecular weight exceeding 1 million makes it difficult to dissolve the cation exchange resin in the step of adhering to an anion exchange membrane.
- the weight average molecular weight of the cation exchange resin is preferably 300,000 or less, particularly preferably 250,000 or less.
- the amount of the cation exchange resin attached to the anion exchange resin membrane is not particularly limited, but is preferably 0.0001 to 0.5 mg / cm 2 .
- the adhesion amount of the cation exchange resin is less than 0.0001 mg / cm 2 , the resin amount of the intermediate layer is insufficient, and as a result, the bondability between the anion exchange resin film and the intermediate layer becomes insufficient.
- the adhesion amount exceeds 0.5 mg / cm 2 , the electric resistance in the intermediate layer increases, which is not preferable.
- the adhesion amount of the cation exchange resin is 0.0003 ⁇ 0.3mg / cm 2, particularly preferably 0.001 ⁇ 0.1mg / cm 2.
- the amount of cation exchange resin adhering to the anion exchange resin membrane surface can be determined by measuring the adhering surface by the following method.
- the adhesion amount is 0.001 to 0.5 mg / cm 2 , the following method is used.
- an anion exchange resin film having an intermediate layer formed on both sides of the germanium optical crystal is overlaid on both sides.
- a measurement sample is produced.
- the incident angle of the measurement sample with respect to the anion exchange resin film is set to 45 °, and the multiple reflection infrared spectrum of the sample is measured according to the total reflection absorption spectrum method.
- the characteristic absorption intensity based on the cation exchange group of the cation exchange resin is determined from the obtained spectrum.
- the size of the germanium optical crystal used is usually 20 mm ⁇ 50 mm ⁇ 3 mm, and the area of the anion exchange membrane used for the measurement is 10 mm ⁇ 45 mm.
- the characteristic absorption based on the cation exchange group is, for example, the characteristic of the sulfone group having absorption in the vicinity of 1000 to 1200 cm ⁇ 1 when the cation exchange resin membrane has a sulfone group such as sulfonic acid.
- the absorption of the carbonyl group having absorption in the vicinity of 1650 to 1760 cm ⁇ 1 is exhibited.
- infrared rays used for measurement do not penetrate deeply into the anion exchange resin membrane. Therefore, it is possible to accurately measure the amount of the cation exchange resin present near the surface of the anion exchange membrane. That is, according to the above method, the substantial amount of the cation exchange resin adhering to the membrane surface can be determined.
- the hydroxide ions are carbonate ions, and further bicarbonate ions. Ion exchange is going on.
- the characteristic absorption wavelength of the carbonate ions depends on the type of cation exchange group when measuring the amount of cation exchange resin deposited by the ATR method (for example, , Carboxylic acid group), and its characteristic absorption wavelength overlaps. In this case, correct measurement becomes difficult.
- the anion exchange membrane is immediately stored in a gas such as nitrogen gas not containing carbon dioxide, and in this gas It is necessary to carry out the above measurement.
- a glove box or the like can be used for this purpose.
- the amount of cation exchange resin adhering to the anion exchange resin membrane surface is not necessarily uniform microscopically. However, the presence of minute variations in the amount of adhesion has little effect on the measurement results when a germanium optical crystal having the above-mentioned area is used and an anion exchange resin film having the above-mentioned area is used as a measurement sample. Absent.
- the following solvent immersion method can be adopted.
- this solvent immersion method first, the anion exchange resin membrane with the intermediate layer attached is immersed in a mixed solution of equal mass of 0.5 mol / l hydrochloric acid aqueous solution and methanol for a long time.
- the cation exchange resin adhering to the surface of the anion exchange resin membrane and the cation exchange resin that may have entered inside are completely eluted in the mixed solution.
- the elution amount of the cation exchange resin eluted in the mixed solution is quantified using liquid chromatography or the like.
- the value obtained by dividing the mass of the cation exchange resin obtained by this solvent immersion method by the total area (cm 2 ) of the membrane is not the amount of adhesion only on the surface of the membrane obtained by the ATR method, but enters the inside of the membrane.
- the total amount of the cation exchange resin is also combined.
- the hydrocarbon-based anion exchange resin membrane is a cross-linked type and the cation exchange resin has a weight average molecular weight of 5000 to 1 million as described above, it is obtained by the solvent immersion method. It was confirmed that the measured value was usually about the same as the adhesion amount obtained by the ATR method. Therefore, when the anion exchange resin membrane and the cation exchange resin are used, the cation exchange resin hardly penetrates into the anion exchange membrane, and most of them adhere to the membrane surface. Has been confirmed.
- the adhesion amount of the cation exchange resin when the applied amount of the cation exchange resin is less than 0.001 mg / cm 2 , the measurement accuracy of the adhesion amount of the cation exchange resin is lowered. Accordingly, the adhesion amount of the cation exchange resin to adhere to the surface of the anion-exchange resin membrane, below the 0.001 mg / cm 2, when the range of up to 0.0001 mg / cm 2, the above-mentioned solvent immersion
- the amount of adhesion to the surface can be obtained by the following method applying the method.
- the above-mentioned solvent dipping method is performed on the anion exchange resin membrane on which the intermediate layer made of the cation exchange resin is formed, and the amount of the cation exchange resin deposited by this method is determined.
- the anion exchange resin membrane the cation exchange resin hardly penetrates into the inside of the membrane, and many of them adhere to the membrane surface. Therefore, the amount of cation exchange resin required by this method is very close to the amount of adhesion on the membrane surface.
- the substantial amount of penetration into the inside of the cation exchange resin is obtained by the procedure described below, and this value is subtracted to more accurately determine the anion exchange resin membrane. Determine the amount of cation exchange resin adhering to the surface.
- the surface layer portion of the anion exchange resin film formed with the same method and having the intermediate layer formed thereon is sandblasted to scrape the surface layer portion by 1 ⁇ m in the thickness direction.
- the solvent immersion method is performed again to determine the amount of cation exchange resin attached. From this value, the substantial amount of the cation exchange resin that has entered the anion exchange resin membrane from which the surface layer portion has been removed is determined.
- the depth of infrared rays that pass through the surface layer of the anion exchange membrane is generally estimated to be about 0.4 ⁇ m. Therefore, if the surface layer portion of the fuel cell membrane is cut by 1 ⁇ m, the portion measured as the amount of cation exchange resin adhering to the surface of the anion exchange resin membrane in the ATR method can be removed.
- the membrane to be eluted is usually 8 cm ⁇ 8 cm. Even in this case, even if there is a variation in the amount of the cation exchange resin adhering to the surface of the diaphragm, the variation hardly affects the measurement results if the diaphragm having the above-mentioned area is used.
- the amount of cation exchange resin adhering to the surface of the solid polymer electrolyte membrane is correlated with this method, even if it is a method other than the above method, and the method can obtain substantially the same measured value. For example, it may be obtained by a method other than the above.
- the attachment form in which the cation exchange resin constituting the intermediate layer adheres to the anion exchange resin membrane surface is not particularly limited, and the intermediate layer is formed so as to cover the entire surface of the anion exchange resin membrane. You may do it. Further, an intermediate layer may be formed on a part of one side of the anion exchange resin membrane. When the intermediate layer is formed only on a part of the surface of the anion exchange resin membrane, the formation area of the intermediate layer should be 1/2 or more of the area per side of the anion exchange resin membrane. Is preferred. By setting the formation area of the intermediate layer to 1 ⁇ 2 or more, the bonding between the anion exchange resin film on which the intermediate layer is formed and the adhesive layer becomes good. Of course, when the anion exchange resin is partially present in this way, the amount of the cation exchange resin attached is determined based on the membrane portion where the cation exchange resin is formed on the surface of the anion exchange resin membrane. calculate.
- hydrocarbon cation exchange resin used for the intermediate layer in the present invention examples include polyether ether ketone, polysulfone, polyether sulfone, polybenzimidazole, polyvinyl imidazole, polyoxazole, polyphenylene oxide, polyphenylene sulfide, Styrene elastomers such as sulfonated or alkylsulfonated engineering plastics such as polyimide, polystyrene-poly (ethylene-butylene) -polystyrene triblock copolymer, polystyrene-poly (ethylene-propylene) -polystyrene triblock copolymer Sulfonated products such as carboxylic acid-modified polyvinyl alcohol, polystyrene sulfonic acid, polyvinyl sulfonic acid, polyacrylic acid, polymethacrylic acid, And La derivatives thereof.
- polyacrylic acid and polymethacrylic acid whose main chain skeleton is an aliphatic chain are more preferable. This is because these polymers have a high degree of freedom of cation exchange groups, so that ion pairs are easily formed.
- the adhesive layer described in the first diaphragm mode of the present invention is joined to the surface of the intermediate layer of the anion exchange resin on which the intermediate layer is formed, so that the second diaphragm type is formed.
- a diaphragm for a fuel cell is obtained.
- the membrane electrode assembly for the polymer electrolyte fuel cell of the present invention can be obtained by bonding the catalyst electrode layers to both surfaces of the membrane for the fuel cell of the present invention.
- the catalyst electrode layer known ones used for hydrogen fuel type and direct liquid type fuel cells can be employed without particular limitation.
- the catalyst electrode layer is composed of catalyst metal particles and a binder resin that binds these metal particles.
- a method for joining the catalyst electrode layer and the fuel cell membrane there is a method of joining the catalyst electrode layer supported by the electrode made of a porous material to the fuel cell membrane of the present invention.
- a resin having no ionic group such as polytetrafluoroethylene can be used.
- This resin preferably contains a hydroxide ion conductive substance.
- the hydroxide ion conductive material increases the conductivity of the hydroxide ions in the catalyst electrode layer, thereby reducing the internal resistance of the fuel cell and improving the utilization factor of the catalyst.
- hydroxide ion conductive substance a substance having an anion exchangeable functional group having a hydroxide ion as a counter ion can be used without limitation.
- anion exchange resins are preferably used.
- the hydrocarbon-based anion exchange resin constituting the adhesive layer of the present invention the quaternized product of hydroxyl ion type polyvinylpyridine, the aminated product of hydroxyl ion type polychloromethylstyrene, polyvinyl benzyltetra Examples include methylammonium hydroxide.
- the catalyst in the catalyst electrode layer is not particularly limited as long as it is a metal that promotes the oxidation reaction of fuel such as hydrogen and methanol and the reduction reaction of oxygen.
- fuel such as hydrogen and methanol and the reduction reaction of oxygen.
- examples include platinum, gold, silver, palladium, iridium, rhodium, ruthenium, tin, iron, cobalt, nickel, molybdenum, tungsten, vanadium, or alloys thereof.
- platinum, ruthenium, or an alloy of platinum and ruthenium having excellent catalytic activity is preferable.
- the particle size of the metal particles used as the catalyst is usually 0.1 to 100 nm, more preferably 0.5 to 10 nm. The smaller the particle size, the higher the catalyst performance. However, it is difficult to produce metal particles having a particle size of less than 0.5 nm. When the particle size is larger than 100 nm, the catalyst performance becomes insufficient.
- These catalysts may be supported on a conductive agent.
- the conductive agent is not particularly limited as long as it is an electronic conductive substance.
- Examples thereof include carbon black such as furnace black and acetylene black, and conductive carbon such as activated carbon and graphite. These also function as catalyst supports. Particularly preferred are those in which the catalyst is supported on the conductive agent.
- Examples of the conductive carbon carrying a catalyst used for an electrode of a fuel cell include those described in JP 2002-329500 A, JP 2002-1000037 A, JP 7-246336 A, and the like. There is.
- a conductive agent carrying a number of catalysts with different catalysts or carriers is commercially available, and it can be used as it is or after performing a necessary treatment.
- the amount of the catalyst supported in the electrode catalyst layer is usually 0.01 to 10 mg / cm 2 , more preferably 0.1 to 5.0 mg / cm 2 when the electrode catalyst layer is regarded as a sheet. .
- the catalyst content is less than 0.01 mg / cm 2 , the catalyst performance is not sufficiently exhibited, and when it exceeds 10 mg / cm 2 , the catalyst performance is saturated.
- a membrane-electrode assembly for a fuel cell can be obtained by joining the catalyst electrode layer comprising these components and the membrane for a fuel cell of the present invention.
- the thickness of the catalyst electrode layer is preferably 5 to 50 ⁇ m.
- the catalyst electrode layer is preferably formed on the surface of the adhesive layer of the fuel cell membrane.
- a general method for producing a catalyst electrode layer is a method in which a catalyst electrode paste in which the above components and an organic solvent are mixed is applied to the surface of the adhesive layer of the diaphragm and then dried.
- Examples of the method for applying the catalyst electrode paste include a screen printing method and a spray method. Adjustment of the amount of catalyst supported and adjustment of the thickness of the catalyst electrode layer are performed by adjusting the viscosity of the catalyst electrode paste. The viscosity is adjusted by adjusting the amount of organic solvent added to the catalyst electrode paste.
- the catalyst electrode layer is previously formed on a polytetrafluoroethylene or polyester film, and this catalyst electrode layer is formed on the fuel cell membrane.
- the catalyst electrode layer is generally transferred to the fuel cell membrane by thermocompression bonding using an apparatus capable of pressurization and heating. Examples of devices capable of pressurization and heating include hot press machines and roll press machines.
- the pressing temperature is generally 40 ° C to 200 ° C. The pressing pressure depends on the thickness and hardness of the catalyst electrode layer to be used, but is usually 0.5 to 20 MPa.
- the membrane-electrode assembly of the present invention may be produced by a method in which the catalyst electrode layer is supported by a porous electrode material as described above and then joined to the diaphragm.
- the porous electrode material include carbon fiber woven fabric and carbon paper.
- the thickness of the electrode material is preferably 50 to 300 ⁇ m, and the porosity is preferably 50 to 90%.
- the catalyst electrode paste is applied to the electrode material, dried, and then thermally bonded to the fuel cell membrane of the present invention in the same manner as described above to produce a membrane-electrode assembly.
- the membrane-electrode assembly for a fuel cell produced in this way is incorporated into a solid electrolyte fuel cell having a basic structure shown in FIG. 1 and used for power generation.
- the polymer electrolyte fuel cell produced using the diaphragm of the present invention is generally one having the basic structure shown in FIG. 1, but of course also applicable to other direct liquid fuel cells having a known structure. can do.
- fuel liquids methanol, ethanol, and aqueous solutions thereof are the most common, and when these are used as fuels, good power generation can be achieved.
- other fuels include ethylene glycol, dimethyl ether, ammonia, hydrazine and the like, and aqueous solutions thereof.
- the diaphragm of the present invention can generate excellent power even when these are used as fuel.
- a basic compound may be added to the liquid fuel.
- the basic compound include potassium hydroxide, sodium hydroxide, potassium hydrogen carbonate, sodium hydrogen carbonate and the like.
- the fuel is not limited to liquid, and gaseous hydrogen gas or the like can be used.
- Ion exchange capacity A membrane for a fuel cell was immersed in a 0.5 mol / L-NaCl aqueous solution for 10 hours or more to obtain a chloride ion type. This diaphragm was immersed in a 0.2 mol / L-NaNO 3 aqueous solution to replace the chloride ion type with the nitrate ion type. The liberated chloride ions were quantified (Amol) by potentiometric titration using an aqueous silver nitrate solution (use apparatus COMMITE-900, manufactured by Hiranuma Sangyo Co., Ltd.).
- the same ion exchange membrane was immersed in a 0.5 mol / L-NaCl aqueous solution for 4 hours or more, and then sufficiently washed with ion exchange water. After removing the ion exchange water on the surface of the diaphragm, the wet weight (Wg) was measured. Then, it dried under reduced pressure at 60 degreeC for 5 hours, and measured the weight (Dg) at the time of drying.
- the ion exchange capacity and water content of the fuel cell membrane were determined by the following equations.
- Membrane resistance In the center of a cell provided with two platinum black electrodes, a fuel cell membrane was sandwiched between the cells, and the cell was partitioned at the center to form a two-chamber cell. Both sides of the diaphragm were filled with 0.5 mol / L-NaCl aqueous solution. The resistance between the electrodes at 25 ° C. was measured using an AC bridge (frequency 1000 cycles / second) circuit. Next, the fuel cell diaphragm was removed, and the resistance between the electrodes was measured in the same manner as described above.
- the difference between the resistance value between the electrodes when the diaphragm was installed and the resistance value between the electrodes when the diaphragm was removed was calculated and used as the membrane resistance.
- the diaphragm used for the above measurement was previously equilibrated in a 0.5 mol / L-sulfuric acid aqueous solution.
- Adhesion layer thickness Using a micrometer having a measurement terminal system of 5 mm ⁇ , the thickness of the fuel cell membrane was measured. On the other hand, when manufacturing the fuel cell membrane, the thickness of the hydrocarbon-based anion exchange resin membrane before forming the adhesive layer was measured in advance. The thickness of the hydrocarbon-based anion exchange resin before forming the adhesive layer was subtracted from the film thickness of the fuel cell membrane, and this value was taken as the thickness of the adhesive layer. The thickness of the hydrocarbon-based anion exchange resin before the formation of the fuel cell membrane and the adhesive layer was measured at 10 points at intervals of 1 cm, and the average value was used.
- the thickness of the adhesive layer could also be obtained by observing the cross section of the fuel cell membrane with a scanning electron microscope (SEM).
- the adhesive layer resin solution was cast on polytetrafluoroethylene and then dried to prepare a cast film of an adhesive layer resin having a thickness of 30 ⁇ m.
- the cast film was placed in an atmosphere of 25 ° C. and 60% RH for 24 hours to adjust the humidity, and using a tensile tester (Shimadzu Corporation: EZ Tester) under the same atmosphere, the relationship between the stress and strain of the cast film was determined. The curve shown was obtained.
- the Young's modulus of the adhesive layer resin was determined from the slope of the first linear portion of this curve.
- the resulting solution was then analyzed by liquid chromatography.
- the amount of the eluted cation exchange resin was determined using a calibration curve prepared using polystyrene sulfonic acid (weight average molecular weight: 75,000) or polyacrylic acid (weight average molecular weight: 250,000).
- the obtained resin amount is divided by the area (128 cm 2 ) of both surfaces of the anion exchange resin membrane, and the amount of adhesion per unit area (cm 2 ) of one surface of the anion exchange resin membrane is calculated. The total amount of resin adhered.
- a sample for measurement was prepared by stacking two anion exchange resin membranes (10 mm ⁇ 45 mm) having a cation exchange resin attached on both upper and lower surfaces of a germanium optical crystal (20 mm ⁇ 50 mm ⁇ 3 mm). Using an infrared spectrometer (Perkin Elmer Spectrum One) in an environment of 50% RH at 25 ° C., the multiple reflection infrared spectrum of the sample was measured at an incident angle of 45 ° according to the total reflection absorption spectrum method. It was measured.
- the sample for measurement is a glove box in a nitrogen gas atmosphere that does not substantially contain carbon dioxide immediately after the ion exchange treatment of the counter ion of the anion exchange resin membrane to which the cation exchange resin is adhered to the hydroxide ion. Stored.
- the intermediate layer resin adhesion amount was measured using the infrared spectroscopic device housed in the same glove box.
- a standard sample was prepared by applying a predetermined amount of polystyrene sulfonic acid (weight average molecular weight 75,000) or polyacrylic acid (weight average molecular weight 250,000) on a polyethylene terephthalate film. The same measurement was performed using the prepared standard sample. The absorption intensity based on the characteristic absorption of the sulfonic acid group (1177 cm ⁇ 1 ) or carbonyl group (1760 cm ⁇ 1 ) was measured. A calibration curve was prepared using these data. Using this calibration curve, the adhesion amount per unit plane area (cm 2 ) of the intermediate layer resin on the anion exchange resin membrane surface was determined. ⁇ Method using solvent immersion method (applied when the adhesion amount is less than 0.001 mg / cm 2 ) First, the solvent dipping method described in 5) above was performed to determine the total amount of intermediate layer resin adhered in this state.
- alumina oxide powder was sprayed onto the surface of the anion exchange resin membrane with the intermediate layer attached, which was separately cut out from the same anion exchange resin membrane with the intermediate layer attached, as described above.
- the surface layer portion of the cut out anion exchange resin membrane was scraped off to a thickness of 1 ⁇ m (including the intermediate layer).
- the solvent immersion method was implemented again using the diaphragm which cut off this surface layer part, and the amount of cation exchange resin was calculated
- the obtained value indicates the substantial amount of the intermediate layer resin that has entered the anion exchange resin membrane from which the surface layer portion has been removed.
- membrane surface was computed by deducting the adhesion total amount after shaving off a surface layer part from the adhesion amount before scraping off a surface layer part.
- adhesion of the intermediate layer resin to the surface of the anion exchange resin membrane required by a method applying this solvent immersion method using the hydrocarbon-based anion exchange resin membrane produced in Example 10 and Example 12 described later
- the amount and the same adhesion amount determined by the ATR method were compared.
- Deposition amount obtained by the former method Example 10 is 0.017 mg / cm 2
- Example 12 was 0.0015 mg / cm 2.
- the adhesion amounts of these examples obtained by the ATR method were exactly the same as the above values as shown in Tables 5 and 6 described later. From these results, it was confirmed that the adhesion amount of the intermediate layer resin to the electrolyte membrane surface obtained by both methods was substantially the same value.
- an output voltage test of a hydrogen fuel type or direct methanol type fuel cell was performed. Furthermore, in order to confirm the power generation stability during long-term power generation, a durability test was performed. Thereafter, the membrane-electrode assembly is taken out from the cell, and a tape peeling test is performed in the same manner as described above (in the case of a membrane-electrode assembly for a direct methanol type fuel cell, the surface on the fuel chamber side). Evaluated.
- Production Example 1 100 parts by mass of chloromethylstyrene, 3 parts by mass of divinylbenzene (3.5 mol% in all polymerizable monomers), 5 parts by mass of polyethylene glycol diepoxide (molecular weight 400), 5 parts by mass of t-butylperoxyethyl hexanoate A monomer composition consisting of parts was prepared. A porous film made of polyethylene (PE, weight average molecular weight 250,000) (film thickness 25 ⁇ m, porosity 37%, average pore diameter 0.03 ⁇ m) was immersed in this monomer composition at 25 ° C. for 10 minutes under atmospheric pressure. The porous film was impregnated with the monomer composition.
- PE weight average molecular weight 250,000
- the porous film was taken out from the monomer composition, and both surfaces of the porous film were covered with a 100 ⁇ m thick polyester film (peeling material). Thereafter, the impregnated monomer composition was polymerized by heating at 80 ° C. for 5 hours under a nitrogen pressure of 0.3 MPa.
- the obtained membrane was immersed in an amination bath at room temperature for 16 hours to obtain a chloride ion type quaternary ammonium type anion exchange membrane.
- the amination bath contained 30 parts by mass of 10 parts by mass of trimethylamine, 5 parts by mass of water, and 5 parts by mass of acetone.
- the obtained anion exchange resin membrane was immersed in a large excess of 0.5 mol / L-NaOH aqueous solution, and the counter ion was ion-exchanged from a chloride ion to a hydroxide ion, and then washed with ion-exchanged water.
- a hydroxide ion type anion exchange resin membrane was obtained.
- Production Examples 2-3 An anion exchange resin membrane was obtained in the same manner as in Production Example 1 except that the monomer composition and the porous membrane were changed to those shown in Table 1. The results of measuring the ion exchange capacity, water content, membrane resistance, and film thickness of these anion exchange resin membranes are shown in Table 2.
- a monomer composition was prepared by mixing 100 parts by mass of 4-vinylpyridine, 5 parts by mass of divinylbenzene (3.9 mol% in the total polymerizable monomer) and 5 parts by mass of t-butylperoxyethylhexanoate. Prepared. A porous film made of polyethylene (PE, weight average molecular weight 250,000) (film thickness 25 ⁇ m, porosity 37%, average pore diameter 0.03 ⁇ m) was immersed in this monomer composition at 25 ° C. for 10 minutes under atmospheric pressure. The porous film was impregnated with the monomer composition.
- PE weight average molecular weight 250,000
- the porous membrane was taken out from the monomer composition, and both surfaces of the porous membrane were covered with a 100 ⁇ m polyester film (peeling material). Thereafter, the impregnated monomer composition was polymerized by heating at 80 ° C. for 5 hours under a nitrogen pressure of 0.3 MPa. The obtained film was immersed in a 1: 4 (mass ratio) mixture of methyl iodide and methanol at 30 ° C. for 24 hours to obtain an iodide ion type quaternary pyridinium type anion exchange resin film. .
- anion exchange resin membrane was immersed in a large excess of 0.5 mol / L-NaOH aqueous solution, whereby the counter ion was ion exchanged from iodide ion to hydroxide ion. Thereafter, a hydroxide ion type anion exchange resin membrane was obtained by washing with ion exchange water.
- Adhesive layer resin is a chloromethylation of ⁇ polystyrene-poly (ethylene-butylene) -polystyrene ⁇ triblock copolymer (SEBS), and the counter ion of the anion exchange resin derived into quaternary ammonium type is converted to hydroxide ion. It was a replacement.
- this adhesive layer resin may be referred to as quaternary ammonium type SEBS.
- Table 3 The properties of this adhesive layer resin are shown in Table 3.
- the other adhesive layer resins are also abbreviated in the same manner.
- the adhesive layer resin solution was a solution in which 5% by mass of the quaternary ammonium type SEBS was dissolved in 1-propanol.
- the anion exchange resin membrane coated with the adhesive layer resin solution was dried at 25 ° C. under atmospheric pressure for 2 hours. Thereby, the diaphragm for fuel cells of this invention which has an adhesion layer on both surfaces of an anion exchange resin membrane was obtained.
- Table 5 shows the measurement results of the anion exchange capacity, water content, membrane resistance, film thickness, and adhesive layer thickness of the fuel cell membrane.
- carbon black supporting 50% by mass of platinum and a quaternary ammonium type ⁇ polystyrene-poly (ethylene-propylene) -polystyrene ⁇ triblock copolymer (quaternary ammonium-modified in the same manner as the quaternary ammonium type SEBS)
- the prepared said liquid mixture was apply
- a fuel chamber side catalyst electrode layer having a catalyst amount of 3 mg / cm 2 was produced in the same manner except that carbon black supported by 50% by mass of platinum and a ruthenium alloy catalyst (ruthenium 50 mol%) was used.
- both the catalyst electrode layers described above were overlapped on both sides of the manufactured fuel cell membrane, and hot-pressed for 100 seconds under a pressure of 100 ° C. and a pressure of 5 MPa.
- a membrane-electrode assembly for a direct methanol fuel type was obtained.
- the bondability of this membrane-electrode assembly was evaluated.
- a direct methanol fuel type fuel cell was prepared using this fuel cell membrane-electrode assembly, and its fuel cell output voltage, durability, and bondability after the durability test were evaluated. The results are shown in Table 5.
- a hydrogen fuel type fuel cell is prepared by using the catalyst electrode layers prepared so that the platinum catalyst amount is 0.5 mg / cm 2 as the oxidant chamber side catalyst electrode layer and the fuel chamber side catalyst electrode layer, respectively.
- a membrane-electrode assembly was produced. The bondability of the obtained fuel cell membrane-electrode assembly was evaluated.
- a hydrogen fuel type fuel cell was produced, and its fuel cell output voltage, durability, and bondability after the durability test were evaluated. The results are shown in Table 6.
- Examples 2 to 9 A membrane for a fuel cell was obtained in the same manner as in Example 1 except that the anion exchange membrane and the adhesive layer resin (the properties are shown in Table 3) were changed to those shown in Table 4.
- Table 5 shows the anion exchange capacity, moisture content, membrane resistance, film thickness, and adhesive layer thickness of the obtained fuel cell membrane.
- Example 5 a direct methanol fuel type membrane-electrode assembly was produced in the same manner as in Example 1. The bondability of the obtained membrane-electrode assembly was evaluated. Furthermore, a direct methanol fuel type fuel cell was produced using this membrane-electrode assembly, and its fuel cell output voltage, durability, and bondability after the durability test were evaluated. The results are shown in Table 5.
- Example 10 The anion exchange membrane of Production Example 1 was immersed in a 0.2 mass% methanol solution of polyacrylic acid (weight average molecular weight 250,000) for 15 minutes at room temperature, then at 25 ° C. under atmospheric pressure for 16 hours, and then 40 It dried for 5 hours under reduced pressure at ° C. Thereafter, the diaphragm was immersed in methanol at room temperature for 30 minutes. Thereafter, the methanol was changed to fresh methanol, and the immersion was performed twice in the same manner.
- polyacrylic acid weight average molecular weight 250,000
- the diaphragm was dried at room temperature for 5 hours to obtain a fuel cell diaphragm having an intermediate layer.
- the fuel cell membrane having the intermediate layer was further provided with an adhesive layer by the method shown in Example 1 to obtain a fuel cell membrane of the present invention.
- Table 5 shows the anion exchange capacity, water content, membrane resistance, film thickness, and intermediate layer adhesion amount of this fuel cell membrane.
- Example 2 the same operation as in Example 1 was performed to obtain a direct methanol fuel type membrane-electrode assembly for a fuel cell.
- a hydrogen fuel type membrane-electrode assembly for a fuel cell was prepared, and its bondability, fuel cell output voltage in the hydrogen fuel type, durability, and bondability after the durability test were measured. evaluated. The results are shown in Table 6.
- Examples 11-15 A fuel cell membrane was obtained in the same manner as in Example 10 except that the intermediate layer resin solution concentration, the intermediate layer resin type, and the adhesive layer thickness were changed to those shown in Table 4.
- Table 5 shows the anion exchange capacity, moisture content, membrane resistance, film thickness, and adhesive layer thickness of the obtained fuel cell membrane.
- Example 13 a direct methanol fuel type diaphragm-electrode assembly for a fuel cell was obtained in the same manner as in Example 1.
- the results are shown in Table 5.
- a hydrogen fuel type diaphragm-electrode assembly for a fuel cell was prepared in the same manner as in Example 1, and its joining property, fuel cell output voltage in the hydrogen fuel type, durability And bondability after the durability test were evaluated. The results are shown in Table 6.
- Example 16 A perfluorocarbon sulfonic acid solution (commercial product A) was prepared in the same manner as in Example 10 except that an intermediate layer was formed using a solution adjusted to a predetermined concentration by adding 1-propanol, and washed with methanol. A diaphragm for a fuel cell was obtained. Tables 5 and 6 show the anion exchange capacity, water content, membrane resistance, film thickness, and adhesive layer thickness of the obtained fuel cell membrane.
- Example 2 a direct methanol fuel type membrane-electrode assembly for a fuel cell was obtained in the same manner as in Example 1.
- a hydrogen fuel type membrane-electrode assembly for a fuel cell was prepared in the same manner as in Example 1, its joining property, the fuel cell output voltage in the hydrogen fuel type, durability, and the joining property after the durability test. Evaluated. The results are shown in Table 6.
- Comparative Example 3 In the same manner as in Example 10, a fuel cell membrane having only an intermediate layer formed on the anion exchange membrane of Production Example 1 was produced. Table 5 shows the anion exchange capacity, moisture content, membrane resistance, film thickness, and adhesive layer thickness of the obtained fuel cell membrane.
- Example 2 a direct methanol fuel type fuel cell membrane-electrode assembly was produced.
- the bondability of the fuel cell membrane-electrode assembly, the fuel cell output voltage in the direct methanol fuel type, durability, and the bondability after the durability test were evaluated.
- the results are shown in Table 5.
- a hydrogen fuel type fuel cell membrane-electrode assembly was prepared, and its bondability, fuel cell output voltage in hydrogen fuel type, durability, and bondability after the durability test. Evaluated. The results are shown in Table 6.
- Comparative Example 4 A diaphragm for a fuel cell was obtained in the same manner as in Example 10 except that the adhesive layer resin was changed to that shown in Table 4.
- Table 5 shows the anion exchange capacity, moisture content, membrane resistance, film thickness, and adhesive layer thickness of the obtained fuel cell membrane.
- a direct methanol fuel type membrane-electrode assembly for a fuel cell was produced in the same manner as in Example 1.
- the fuel cell membrane-electrode assembly obtained was evaluated for its bondability, direct fuel cell fuel cell output voltage, durability, and bondability after the durability test. The results are shown in Table 5.
- a diaphragm-catalyst electrode assembly for a hydrogen fuel type fuel cell was prepared in the same manner as in Example 1, its joining property, the fuel cell output voltage in the hydrogen fuel type, durability, and the joining property after the durability test. Evaluated. The results are shown in Table 6.
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Abstract
Description
(i)反応場が強酸性のため、貴金属触媒しか使用できない。
(ii)パーフルオロカーボンスルホン酸樹脂膜は高価であり、コストダウンに限界がある。
(iii)樹脂膜の物理的な強度が低いため、樹脂膜を薄膜化させることによって、樹脂膜の電気抵抗を低減させることが困難である。
(iv)樹脂膜の保水力が小さい。従って、樹脂膜のプロトン導電性を保つために水を補給する必要がある。
(v)燃料にメタノールを用いる場合、樹脂膜に対するメタノールの透過性が高く、酸化剤室側ガス拡散電極にメタノールが到達する。このメタノールは、拡散電極の触媒表面で酸素または空気と反応して過電圧を発生させる。その結果、出力電圧が低下する(他の液体燃料を用いる場合も同様である)。
2 燃料流通孔
3 酸化剤ガス流通孔
4 燃料室側拡散電極
5 酸化剤室側ガス拡散電極
6 固体高分子電解質膜(陰イオン交換膜)
7 燃料室
8 酸化剤室
本発明の第1の形態の固体高分子型燃料電池用隔膜(以下、単に電池用隔膜と記載することがある。)の構成の一例を図2に示す。図2において、200は固体高分子型燃料電池用隔膜で、炭化水素系陰イオン交換樹脂膜202の両面に接着層204、206がそれぞれ形成されている。
炭化水素系陰イオン交換樹脂膜202、302は、従来公知である炭化水素系陰イオン交換樹脂膜が何ら制限無く使用できる。陰イオン交換基としては、1~3級アミノ基、4級アンモニウム塩基、ピリジル基、イミダゾール基、4級ピリジニウム塩基等が挙げられる。強塩基性基である4級アンモニウム塩基や4級ピリジニウム塩基が好ましい。
接着層204、206、304は、上記炭化水素系陰イオン交換樹脂膜の少なくとも1面に積層されて、該交換膜と一体化されている。
炭化水素系陰イオン交換樹脂の少なくとも一面に接着層を形成する方法としては、特に限定されない。例えば、先ず、接着層樹脂溶液を予めポリテトラフルオロエチレンシートに塗布後、乾燥させることによりシート上に接着層樹脂薄膜を形成しておく。次いで、この薄膜を架橋型陰イオン交換樹脂膜に熱プレスなどの方法で転写する方法がある。
本発明の第2の隔膜形態の固体高分子型燃料電池用隔膜の構成の一例を図4に示す。
燃料電池用隔膜を0.5mol/L-NaCl水溶液に10時間以上浸漬し、塩化物イオン型とした。この隔膜を、0.2mol/L-NaNO3水溶液に浸漬し、塩化物イオン型から硝酸イオン型に置換させた。遊離した塩化物イオンを、硝酸銀水溶液を用いる電位差滴定法(使用装置 COMTITE-900、平沼産業株式会社製)で定量した(Amol)。
含水率=100×(W-D)/D[%]
2)膜抵抗
2つの白金黒電極を備えたセルの中央において、燃料電池用隔膜をセルに挟み込み、セルを中央で仕切って2室セルを構成した。隔膜の両側に0.5mol/L-NaCl水溶液を満たした。交流ブリッジ(周波数1000サイクル/秒)回路を用いて、25℃における電極間の抵抗を測定した。次に、燃料電池用隔膜を取外して、上記と同様に操作して電極間の抵抗を測定した。隔膜を設置した場合の電極間の抵抗値と、隔膜を取外した場合の電極間の抵抗値との差を算出し、これを膜抵抗とした。上記測定に使用する隔膜は、あらかじめ0.5mol/L-硫酸水溶液中で平衡にしておいた。
測定端子系5mmφであるマイクロメーターを用いて、燃料電池用隔膜の膜厚を測定した。一方、この燃料電池用隔膜を製造する際に、接着層を形成する前の炭化水素系陰イオン交換樹脂膜の厚みを予め測定しておいた。前記燃料電池用隔膜の膜厚から、接着層を形成する前の炭化水素系陰イオン交換樹脂の厚みを差し引き、この値を接着層の厚みとした。尚、燃料電池用隔膜、及び接着層を形成する前の炭化水素系陰イオン交換樹脂の厚みは、それぞれ1cm間隔で10箇所の厚みを計測し、その平均値を用いた。
接着層樹脂溶液をポリテトラフルオロエチレン上にキャストした後、乾燥させて、厚さ30μmの接着層樹脂のキャストフィルムを作製した。該キャストフィルムを25℃、60%RHの雰囲気に24時間置いて調湿した後、同じ雰囲気下で引っ張り試験機(島津製作所社:EZテスター)を用いて、キャストフィルムの応力と歪みの関係を示す曲線を得た。この曲線の最初の直線部の傾斜より接着層樹脂のヤング率を求めた。
0.5mol/L-塩酸水溶液とメタノールとの等質量混合溶液40mlを用意した。この溶液に、中間層(陽イオン交換樹脂)を形成した炭化水素系陰イオン交換樹脂膜(8cm×8cm)を、室温で16時間浸漬し、陽イオン交換樹脂を溶出させた。
・ATR法(付着量が0.001mg/cm2以上の場合に適用)
陽イオン交換樹脂が付着した陰イオン交換樹脂膜(10mm×45mm)2枚をゲルマニウム光学結晶(20mm×50mm×3mm)の上下両面に重ねて測定用試料を調製した。25℃で50%RHの環境下で、赤外分光装置(パーキンエルマー製スペクトラムワン)を用いて、全反射吸収スペクトル法に従って、入射角45°で、前記試料の多重反射法赤外分光スペクトルを測定した。
・溶媒浸漬法を応用した方法(付着量が0.001mg/cm2未満の場合に適用)
まず、上記5)で説明した溶媒浸漬法を実施して、この状態での中間層樹脂の付着総量を求めた。
作製直後の膜-電極接合体を用い、JISK-5400のXカットテープ法に準拠し、テープ剥離試験を行った。テープ剥離後、陰イオン交換樹脂膜上に残った電極層の状態を目視で観察し、10点法により評価した。得られた結果を、作製直後の接合性とした。
膜-電極接合体を、厚みが200μmであり、空孔率が80%のカーボンペーパーで挟み込み、図1に示す構造の燃料電池セルを構成した。次いで、燃料電池セル温度を50℃に設定し、発電試験を行った。燃料室側には、10質量%メタノール水溶液を1ml/minの流量で供給した。酸化剤室側には大気圧の空気を200ml/minで供給した。電流密度0A/cm2、0.1A/cm2におけるセルの端子電圧を測定した。
膜-電極接合体を、厚みが200μmであり、空孔率が80%のカーボンペーパーで挟み込み、図1に示す構造の燃料電池セルを作製した。次いで、燃料電池セル温度を50℃に設定し、発電試験を行った。大気圧で加湿温度50℃の水素と空気をそれぞれ200ml/min、500ml/minの流量で供給した。電流密度0A/cm2、0.2A/cm2におけるセルの端子電圧を測定した。
上記の燃料電池出力電圧の測定後、水素燃料型燃料電池は50℃、0.2A/cm2で、また、直接メタノール型燃料電池は50℃、0.1A/cm2で連続発電試験を行った。250時間後の出力電圧を測定し、膜-電極接合体の耐久性を評価した。
クロロメチルスチレン100質量部、ジビニルベンゼン3質量部(全重合性単量体中3.5モル%)、ポリエチレングリコールジエポキシド(分子量400)5質量部、t-ブチルパーオキシエチルヘキサノエート5質量部よりなる単量体組成物を調製した。この単量体組成物にポリエチレン(PE、重量平均分子量25万)製の多孔質膜(膜厚25μm、空隙率37%、平均孔径0.03μm)を大気圧下、25℃で10分浸漬し、単量体組成物を多孔質膜に含浸させた。
単量体組成物と多孔質膜とを表1に示すものに変えた以外は製造例1と同様に操作して、陰イオン交換樹脂膜を得た。これら陰イオン交換樹脂膜のイオン交換容量、含水率、膜抵抗、膜厚を測定した結果を表2に示した。
4-ビニルピリジン100質量部、ジビニルベンゼン5質量部(全重合性単量体中3.9モル%)、t-ブチルパーオキシエチルヘキサノエート5質量部を混合して単量体組成物を調製した。この単量体組成物にポリエチレン(PE、重量平均分子量25万)製の多孔質膜(膜厚25μm、空隙率37%、平均孔径0.03μm)を大気圧下、25℃で10分浸漬し、単量体組成物を多孔質膜に含浸させた。
製造例1の陰イオン交換樹脂膜の両表面に、それぞれ接着層樹脂溶液をスクリーン印刷法によってコートした。接着層樹脂は、{ポリスチレン‐ポリ(エチレン‐ブチレン)‐ポリスチレン}トリブロック共重合体(SEBS)をクロロメチル化し、更に4級アンモニウム型に誘導した陰イオン交換樹脂の対イオンを水酸イオンに交換処理したものであった。以後、この接着層樹脂を4級アンモニウム型SEBSと記載することがある。この接着層樹脂の性状を表3に示した。その他の接着層樹脂についても、同様に略記する。
陰イオン交換膜ならびに接着層樹脂(それぞれの性状は表3に表示した。)を表4に示したものに変えた以外は実施例1と同様に操作して燃料電池用隔膜を得た。得られた燃料電池用隔膜のアニオン交換容量、含水率、膜抵抗、膜厚、接着層の厚みを表5に示した。
製造例1の陰イオン交換膜を、ポリアクリル酸(重量平均分子量25万)の0.2質量%メタノール溶液に室温で15分間浸漬し、次いで、25℃、大気圧下で16時間、その後40℃、減圧下で5時間乾燥した。その後、隔膜をメタノールに室温で30分間浸漬した。その後、メタノールを新しいメタノールに変えて、同様にして合計2回の浸漬を行った。
中間層樹脂溶液濃度、中間層樹脂種、接着層厚みを表4に示したものに変えた以外は実施例10と同様にして燃料電池用隔膜を得た。得られた燃料電池用隔膜のアニオン交換容量、含水率、膜抵抗、膜厚、接着層の厚みを表5に示した。
パーフルオロカーボンスルホン酸溶液(市販品A)に、1-プロパノールを加え所定濃度に調整した溶液を用いて中間層を形成し、メタノールを用いて洗浄した以外は実施例10と同様に操作して、燃料電池用隔膜を得た。得られた燃料電池用隔膜のアニオン交換容量、含水率、膜抵抗、膜厚、接着層の厚みを表5および表6に示した。
製造例1および製造例4の陰イオン交換膜をそのまま燃料電池用隔膜として用いて、実施例1と同様にして直接メタノール燃料型の燃料電池用隔-電極接合体を得た。得られた膜-電極接合体の接合性、直接メタノール燃料型での燃料電池出力電圧、耐久性、該耐久性試験後の接合性を評価した。結果を表5に示した。また、実施例1と同様にして水素燃料型の燃料電池用膜-電極接合体も作製し、その接合性、水素燃料型での燃料電池出力電圧、耐久性、該耐久性試験後の接合性を評価した。結果を表6に示した。
製造例1の陰イオン交換膜に、実施例10と同様に、中間層のみを形成した燃料電池隔膜を作製した。得られた燃料電池用隔膜のアニオン交換容量、含水率、膜抵抗、膜厚、接着層の厚みを表5に示した。
接着層樹脂を表4に示したものに変えた以外は実施例10と同様にして燃料電池用隔膜を得た。得られた燃料電池用隔膜のアニオン交換容量、含水率、膜抵抗、膜厚、接着層の厚みを表5に示した。さらに、実施例1と同様にして、直接メタノール燃料型の燃料電池用膜-電極接合体を作製した。得られた燃料電池用膜-電極接合体の接合性、直接メタノール燃料型での燃料電池出力電圧、耐久性、該耐久性試験後の接合性を評価した。結果を表5に示した。更に、実施例1と同様にして水素燃料型の燃料電池用隔膜-触媒電極接合体を作製し、その接合性、水素燃料型における燃料電池出力電圧、耐久性、該耐久性試験後の接合性を評価した。結果を表6に示した。
Claims (12)
- 陰イオン交換基が炭化水素系樹脂に共有結合している炭化水素系陰イオン交換樹脂膜と、前記炭化水素系陰イオン交換樹脂膜の少なくとも一面に形成された接着層とからなる固体高分子型燃料電池用隔膜であって、前記接着層はヤング率が1~1000MPaの陰イオン交換樹脂からなる、固体高分子型燃料電池用隔膜。
- 接着層が、20℃の水に対して1質量%未満の溶解性を有する請求項1に記載の固体高分子型燃料電池用隔膜。
- 接着層が、20℃のメタノール及びエタノールに対して1質量%未満の溶解性を有する請求項1に記載の直接液体型燃料電池用隔膜。
- 接着層が、陰イオン交換基が炭化水素系樹脂に共有結合している炭化水素系陰イオン交換樹脂からなる請求項1に記載の固体高分子型燃料電池用隔膜。
- 接着層が、陰イオン交換基がスチレン系エラストマーに共有結合しているスチレン系陰イオン交換樹脂からなる請求項1に記載の固体高分子型燃料電池用隔膜。
- スチレン系エラストマーが、ポリスチレン-ポリアルキレン-ポリスチレントリブロック共重合体である請求項5に記載の固体高分子型燃料電池用隔膜。
- 陰イオン交換基が炭化水素系樹脂に共有結合している炭化水素系陰イオン交換樹脂膜が、多孔質膜と、前記多孔質膜内の空隙に充填された炭化水素系陰イオン交換樹脂とからなる請求項1に記載の、固体高分子型燃料電池用隔膜。
- 請求項1乃至7の何れかに記載の固体高分子型燃料電池用隔膜において、炭化水素系陰イオン交換樹脂隔膜と接着層との間に陽イオン交換樹脂からなる中間層を有する固体高分子型燃料電池用隔膜。
- 請求項1に記載の固体高分子型燃料電池用隔膜の少なくとも一面に触媒電極層を形成してなる隔膜-触媒電極接合体。
- 請求項8に記載の固体高分子型燃料電池用隔膜の少なくとも一面に触媒電極層を形成してなる隔膜-触媒電極接合体。
- 請求項9に記載の隔膜-触媒電極接合体を組込んでなる固体高分子型燃料電池。
- 請求項10に記載の隔膜-触媒電極接合体を組込んでなる固体高分子型燃料電池。
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WO2011154835A1 (en) * | 2010-06-07 | 2011-12-15 | Cellera, Inc. | Chemical bonding for catalyst/membrane surface adherence in membrane-electrolyte fuel cells |
US10096838B2 (en) | 2010-06-07 | 2018-10-09 | POCell Tech Ltd. | Chemical bonding for catalyst/membrane surface adherence in membrane electrolyte fuel cells |
JP2019522887A (ja) * | 2016-06-22 | 2019-08-15 | ビトゥイーン リツェンツ ゲーエムベーハー | 親水性膜相としてポリエチレングリコールを用いた架橋高安定アニオン交換ブレンド膜 |
JP2022160413A (ja) * | 2016-06-22 | 2022-10-19 | ビトゥイーン リツェンツ ゲーエムベーハー | 親水性膜相としてポリエチレングリコールを用いた架橋高安定アニオン交換ブレンド膜 |
US11923584B2 (en) | 2020-04-24 | 2024-03-05 | Asahi Kasei Kabushiki Kaisha | Membrane for redox flow battery, method for producing membrane for redox flow battery, membrane electrode assembly for redox flow battery, cell for redox flow battery, and redox flow battery |
Also Published As
Publication number | Publication date |
---|---|
KR20100106980A (ko) | 2010-10-04 |
JPWO2009081841A1 (ja) | 2011-05-06 |
EP2224522B1 (en) | 2013-10-09 |
JP5301466B2 (ja) | 2013-09-25 |
US9153830B2 (en) | 2015-10-06 |
KR101590651B1 (ko) | 2016-02-01 |
EP2224522A4 (en) | 2012-01-04 |
US20100291470A1 (en) | 2010-11-18 |
EP2224522A1 (en) | 2010-09-01 |
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