JP2005320472A - Proton conductive film, assembly of catalytic electrode and proton conductor and fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a proton conductive film excellent in resistance to methanol solubility, film formability and the like. <P>SOLUTION: The proton conductive film is obtained by (1) subjecting (A) an amino group-containing silicon alkoxide, (B) an amino group-free silicon alkoxide, (C) a metal alkoxide containing at least one of titanium, aluminum and zirconium, and (D) a phosphoric acid compound or a phosphorous acid compound to hydrolysis and condensation to prepare a first solution containing a metal oxide derivative, (2) adding the first solution to a solution containing an organic proton conductive polymer having a specific glass transition temperature to prepare a second solution containing the organic proton conductive polymer and the metal oxide derivative, and (3) casting the second solution, and has a reduction ratio of the storage modulus at a temperature (T) to the storage modulus at 30°C of ≤90%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a proton conducting membrane and a fuel cell using the same.

  As a proton conductive membrane made of a polymer compound, there is a styrene-based cation exchange membrane developed in the 1950s. However, a fuel cell having a practically sufficient life is lacking in stability under a fuel cell operating environment. It is not yet ready for production.

  As a proton conducting membrane having practical stability, a perfluorocarbon sulfonic acid membrane represented by Nafion (registered trademark of Nafion, DuPont, the same applies hereinafter) has been developed, and many electrochemical devices including PEFC fuel cells have been developed. Application to is proposed.

  As an application example of the electrochemical element, there is a methanol fuel cell. This methanol fuel cell is classified into two types, the liquid supply type and the vaporization supply type, depending on the liquid fuel supply method, and the vaporization supply type fuel cell has a high activity and high performance because the electrode reaction is carried out with the gaseous fuel. It can be demonstrated, but the system is complicated and difficult to downsize.

  On the other hand, the liquid supply type fuel cell can simplify the system compared to the vaporization supply type, but has low activity and low performance because the electrode reaction is carried out with the liquid fuel. Since liquid fuel cells that use capillary force for fuel supply are also in a liquid state, they do not require a pump or the like and are suitable for miniaturization, but the electrode reaction is low activity and performance is low.

  In addition to the above problems, a perfluorocarbon sulfonic acid membrane as an electrolyte membrane is currently excellent in proton conductivity and oxidation resistance, but has a complicated manufacturing process and is very expensive. Further, when the perfluorocarbon sulfonic acid membrane is applied to the electrolyte membrane of a methanol fuel cell, a crossover occurs in which methanol permeates the electrolyte membrane. When this phenomenon occurs, the supplied methanol and oxidant react directly, and energy cannot be output as electric power. Therefore, there is a fatal drawback that it is impossible to obtain stable power.

  In order to remedy the above problems, an alcohol solution containing a metal alkoxide is impregnated with a perfluorocarbon sulfonic acid membrane, a proton conductive membrane in which an inorganic substance is introduced into the film, and further an alcohol solution containing a metal alkoxide having an amino group. Although the proton conductive membrane obtained by impregnation is adjusted, this method cannot control the addition amount of the metal oxide introduced, and the metal oxide is introduced as particles, so the methanol permeation inhibiting effect is weak. In addition, when a material other than the perfluorocarbon sulfonic acid membrane is used, it dissolves and this method cannot be applied.

  Furthermore, the fluorine-containing compound has a large environmental load at the time of synthesis and disposal, and is not necessarily optimal as a constituent material for fuel cells and the like when considering future environmental problems.

  Against this background, various non-perfluorocarbon sulfonated proton conducting membranes such as sulfonated partially fluorinated membranes or sulfonated aromatic polymer membranes with reduced fluorine content have been proposed. Typical examples include sulfonated polyetheretherketone, sulfonated products of heat-resistant aromatic polymers such as sulfonated polyethersulfone and sulfonated polysulfone, and a copolymer consisting of a fluorocarbon vinyl monomer and a hydrocarbon vinyl monomer. Examples include a sulfonated polystyrene-graft-ethylene-tetrafluoroethylene copolymer film composed of a combined structure and an aromatic hydrocarbon structure having a sulfonic acid group. Further, a proton conductive membrane made of a sulfonated product of SEBS (styrene- (ethylene-butylene) -styrene) that is inexpensive, mechanically and chemically stable has been proposed.

  Conventionally proposed non-perfluorocarbon sulfonic acid membranes, that is, sulfonated partially fluorinated membranes or sulfonated aromatic polymer membranes, are said to be easy to manufacture and cost-effective. Yes. However, when used as a fuel cell membrane, it exhibits severe dimensional changes due to swelling when the membrane is hydrated, insufficient chemical stability (oxidation resistance), and solubility in methanol, a liquid fuel. It is known.

  On the other hand, a polymer electrolyte membrane in which a three-dimensional cross-linked polymer containing a metal element using a non-perfluorosulfonic acid membrane has an internal penetrating polymer network structure has been proposed. Insufficient reactivity with non-perfluorosulfonic acid membranes and insufficient internal penetrating polymer network structure is insufficient to improve the required methanol solubility (for example, Patent Documents) 1 and 2).

  For these organic polymer proton conductors, a proton conductor made of an inorganic compound (glass conductor) having methanol solubility resistance, low swellability, oxidation resistance and conductivity has been developed. Processability and flexibility are poor, handling is difficult, and it is difficult to form a flexible film having a practical shape.

  In order to improve these problems, a proton conductor obtained by blending an inorganic compound mainly composed of silicon oxide and Bronsted acid with an organic proton conductive polymer has been proposed. Since the proton conductor obtained by the method is a simple blend, only a slight suppression effect on the degree of swelling of the organic proton conductive polymer is expected and insufficient (see, for example, Patent Documents 3, 4 and 5).

  In contrast, in a solution containing an aromatic polymer compound having a sulfonic acid group, an inorganic compound mainly composed of a silicon oxide and a phosphoric acid derivative is synthesized, and the solvent is removed by drying. A method of manufacturing a composite proton conducting membrane is proposed (see, for example, Patent Document 6).

  In the case of this method, it is expected that the organic proton conductive polymer and the inorganic proton conductive material are intertwined with each other, but the swelling suppression effect is expected. However, the inorganic proton conductive material obtained in the preparation method includes a phosphoric acid derivative and a silicon compound. And free phosphoric acid that is not fixed to silicon remains, the phosphoric acid dissolves in the water generated during fuel cell operation, and the expression of proton conductivity is insufficient. At the same time, it becomes porous due to elution of non-immobilized phosphoric acid, and methanol as a liquid fuel permeates.

  A system using a metal compound other than a silicon compound in combination with phosphoric acid immobilized on an inorganic proton conductor and a conductor using a silicon compound carrying a sulfonic acid or phosphonic acid derivative carrying proton conductivity However, since there are few organic components which are soft components, workability and flexibility are poor, and it is difficult to obtain a practical film (see, for example, Patent Documents 7 and 8, Non-Patent Documents). Reference 1).

  As described above, a proton conductive membrane that exhibits methanol solubility resistance, oxidation resistance, dimensional stability, and excellent proton conductivity, suppresses methanol crossover, is highly flexible, and has good film formability is still available. Not found.

Japanese Patent Laid-Open No. 2003-257452 JP 2003-257453 A JP-A-8-249923 (Claims) JP-A-10-69817 (Claims) JP-A-11-203936 (Claims) JP 2001-307752 A (Claims) JP-A-8-119612 (paragraph numbers 0004 to 0005) JP 2002-245846 A (paragraph numbers 0010 to 0023) “Chemistry Letters”, 2000, p. 1314

  The present invention relates to a proton conductive membrane having sufficient proton conductivity and methanol solubility resistance for use as a polymer electrolyte fuel cell and capable of suppressing methanol crossover, and a catalyst electrode using the same It aims at providing the manufacturing method of a combination with a proton conductive membrane, a fuel cell, and a proton conductive membrane. Furthermore, a proton conducting membrane excellent in terms of suppressing swelling (dimension stability) due to water, methanol, etc., solubility in methanol, flexibility, film-forming property and sufficient proton conductivity, and It is an object of the present invention to provide a joined body of a catalyst electrode and a proton conductive membrane, and a fuel cell.

  According to one embodiment of the present invention, a silicon alkoxide (A) containing an amino group, a silicon alkoxide (B) containing no amino group, and a metal alkoxide (C) containing any one or more of titanium, aluminum, and zirconium ) And a phosphoric acid compound or a phosphorous acid compound to prepare a first solution containing a metal oxide derivative, and then the first solution is a molecular chain micro-brown in dynamic viscoelasticity measurement. A temperature (T) at which the main dispersion derived from motion is observed is added to a solution containing an organic proton conductive polymer having a temperature of 60 ° C. to 270 ° C., and the organic proton conductive polymer, the metal oxide derivative, A proton conductive membrane obtained by casting from the second solution, and in the measurement of dynamic viscoelasticity of the proton conductive membrane, 30 ° C. The proton conductive membrane reduction rate of the storage modulus at a temperature (T) for the storage elastic modulus is less than 90% is provided.

  The content of the organic proton conductive polymer in the proton conductive membrane is 20 to 60% by weight, has a proton dissociable group at the end of the side chain, and in particular, the proton dissociable group in the organic proton conductive polymer is sulfonic acid. It is preferably at least one of a group, a phosphonic acid group, a sulfonamide group, a sulfonimide group and derivatives thereof, and more preferably a sulfonated polyether ether ketone or a sulfonated polyether sulfone.

  According to another aspect of the present invention, the catalyst electrode and the proton conductive membrane are joined to each other by arranging a catalyst electrode carrying a metal on a carrier made of electrically conductive fine particles on both sides of the proton conductive membrane. The body is provided.

  The electrically conductive fine particles contain carbon fine particles, the catalyst electrode contains an organic proton conductive polymer, the organic proton conductive polymer has a proton dissociable group at the end of the side chain, The proton dissociable group in the proton conducting polymer is preferably at least one of a sulfonic acid group, a phosphonic acid group, a sulfonamide group, a sulfonimide group, and derivatives thereof. More preferred are sulfonated polyetheretherketone or sulfonated polyethersulfone.

  According to still another aspect of the present invention, there is provided a fuel cell using the above-mentioned joined body of a catalyst electrode and a proton conductive membrane.

  The proton conductive membrane according to the present invention has excellent suppression of swelling (dimensional stability) due to water, methanol, etc., suppression of methanol crossover, durability (oxidation resistance), flexibility, film-forming property, and proton conductivity. Can be. Therefore, the combination of the catalyst electrode and the proton conductive membrane using the proton conductive membrane according to the present invention and the fuel cell are excellent in durability, power generation stability, and the like.

  Hereinafter, embodiments of the present invention will be described using examples and the like. In addition, these Examples etc. and description illustrate this invention, and do not restrict | limit the scope of the present invention. It goes without saying that other embodiments may belong to the category of the present invention as long as they match the gist of the present invention.

  The proton conducting membrane according to the present invention hydrolyzes and condenses a silicon alkoxide containing an amino group, a silicon alkoxide containing no amino group, a metal alkoxide containing any one or more of titanium, aluminum and zirconium and phosphoric acid. By preparing the first solution containing the metal oxide derivative, the temperature (T) at which the main dispersion derived from the micro-Brownian motion of the molecular chain in the dynamic viscoelasticity measurement is observed is 60. A second solution containing the organic proton conductive polymer and the metal oxide is added to a solution containing the organic proton conductive polymer in the temperature range of 270C to 270 ° C. A proton conductive membrane obtained from a solution of the above by a casting method. In the dynamic viscoelasticity measurement of the proton conductive membrane, the temperature (T Rate of decrease in storage modulus at is proton conductive membrane 90% or less.

  The metal oxide derivatives according to the present invention are, for example, materials such as phosphate silicate prepared by sol-gel reaction using tetraethoxylane and phosphoric acid as raw materials, and sol-gel using tetraisopropoxytitanium and phosphoric acid as raw materials. By a material such as phosphate titanate prepared by reaction.

  In the present specification, “proton dissociation” means that protons can be dissociated in a polar solvent such as water.

  As the solvent used in the preparation of the metal oxide derivative, a silicon alkoxide containing an amino group according to the present invention, a silicon alkoxide containing no amino group, and a metal alkoxide containing any one or more of titanium, aluminum and zirconium are used. Examples of the solvent that can be uniformly dispersed and dissolved include various alcohols such as methanol, ethanol, propanol, butanol, ethoxyethanol, ketones such as acetone, toluene, xylenes, NMP (N-methyl-2-pyrrolidone). ), DMF (dimethylformamide), and DMAc (dimethylacetamide).

  The proton conducting membrane obtained by the above method suppresses swelling with respect to water, methanol, etc., because the molecular chains of the organic proton conducting polymer and the metal oxide derivative enter each other to form a network structure. In addition, it is possible to obtain a proton conducting membrane that realizes high solvent resistance, methanol solubility resistance when actually applied to direct methanol, and methanol crossover suppression.

Although it is not always possible to directly confirm that molecular chains invade each other to form a network structure, the following can be cited as a method for indirectly confirming this. (1)
When the proton conductive membrane is immersed in the solvent used to make the organic proton conductive polymer cast film or the solvent in which the organic proton conductive polymer is dissolved and the re-dissolution test is performed, the solubility of the proton conductive membrane is reduced. Less than 15%, (2) The rate of decrease in storage elastic modulus at the glass transition temperature of the organic proton conductive polymer with respect to the storage elastic modulus at 50 ° C. of the proton conducting membrane is 90% or less, (3) Proton conduction In the electron microscopic observation of the membrane, the metal oxide is observed only in a size substantially less than a micron order, and the proton conducting membrane composed of the organic proton conducting polymer and the metal oxide satisfying these three conditions simultaneously is It is thought that molecular chains enter each other to form a network structure.

  Next, the organic proton conductive polymer used in the present invention will be described. The organic proton conductive polymer used in the present invention is not particularly limited as long as it is an organic polymer exhibiting proton conductivity and is soluble in a solvent compatible with the sol-gel reaction solvent described later. However, a polymer having a proton dissociable group in the side chain is preferable from the viewpoints of proton conductivity and film-forming property. Examples of the proton dissociable group in this case include a sulfonic acid group, a phosphonic acid group, a sulfonamide group, a sulfonimide group, and derivatives thereof as in the case of the silicon alkoxide compound. Furthermore, an organic proton conductive polymer having a temperature (T) at which main dispersion derived from micro-Brownian motion of molecular chains in dynamic viscoelasticity measurement is observed is 60 ° C to 270 ° C. When the temperature is 60 ° C. or lower, the film is deformed by heat generation during operation of the fuel cell, which is not preferable. When the temperature is 270 ° C. or higher, the bonding between the membrane and the electrode is insufficient when the electrode / membrane / electrode unit is produced, which is not preferable.

  Specific examples of such polymers include hydrocarbon-based proton conductive polymers, specifically, sulfonated ethylene tetrafluoroethylene copolymer-graft-polystyrene, sulfonamide-type ethylene tetrafluoroethylene copolymer-graft. -Polystyrene, sulfonated polyethersulfone, sulfonamide type polyethersulfone, sulfonated polyetheretherketone, sulfonamide type polyetheretherketone, sulfonated crosslinked polystyrene, sulfonamide type crosslinked polystyrene, sulfonated polytrifluorostyrene, sulfone Amide type polytrifluorostyrene, sulfonated polyaryl ether ketone, sulfonamide type polyaryl ether ketone, sulfonated poly (aryl ether sulfone), sulfonamide type polysulfone (Aryl ether sulfone), sulfonated polyimide, sulfonamide type polyimide, sulfonated 4-phenoxybenzoyl-1,4-phenylene, sulfonamide type 4-phenoxybenzoyl-1,4-phenylene, phosphonic acid type 4-phenoxybenzoyl- 1,4-phenylene, sulfonated polybenzimidazole, sulfonamide type polybenzimidazole, phosphonic acid type polybenzimidazole, sulfonated polyphenylene sulfide, sulfonamide type polyphenylene sulfide, sulfonated polybiphenylene sulfide, sulfonamide type polybiphenylene sulfide, Examples thereof include sulfonated polyphenylene sulfone and sulfonamide type polyphenylene sulfone. Of these, sulfonated polyetheretherketone and sulfonated polyethersulfone are preferred from the viewpoint of film forming properties and easiness of sulfonation. The content of the organic proton conductive membrane in the proton conductive membrane according to the present invention is preferably in the range of 20 to 60% by weight, and more preferably in the range of 30 to 50% by weight. Below 20% by weight, the rate of decrease in storage modulus at the temperature (T) at which the main dispersion derived from micro-Brownian motion of the molecular chain relative to the storage modulus at 30 ° C. is measured in the dynamic viscoelasticity measurement of the proton conducting membrane. Is 90% or more, and the effect of forming a network is weak, and it is often unfavorable because methanol solubility resistance, swelling degree inhibiting effect, and methanol crossover inhibiting effect are not seen. If it is 60% by weight or more, cracks and the like occur in the drying process during film formation, which is often not preferred. The content of the organic proton conductive polymer in the proton conductive membrane according to the present invention is preferably a value obtained by subtracting the above metal oxide derivative content from 100% by weight, but depending on the case, other components may be added. May be included.

  Examples of the metal oxide derivative include those obtained by condensing a metal alkoxide and a phosphoric acid compound or a phosphorous acid compound. Specifically, it can be obtained by adding water to a silicon alkoxide, titanium isopropoxide, and phosphoric acid to perform hydrolysis to perform sol-gel reaction and condensation.

As the metal alkoxide in the present invention, any metal alkoxide can be used.
The metal alkoxide according to the present invention includes a silicon alkoxide containing an amino group, a silicon alkoxide containing no amino group, a metal alkoxide containing any one or more of titanium, aluminum and zirconium, a phosphoric acid compound or phosphorous acid. It is obtained by hydrolysis and condensation of the compound.

  Examples of silicon alkoxides containing amino groups include N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, and 3-aminopropyltrimethoxysilane. Among them, 3-aminopropyltriethoxysilane is preferable, among which 3-aminopropyltrimethoxysilane is preferable.

  It is preferable that the organic proton conductive polymer and the metal oxide derivative have compatibility and the catalytic effect of the sol-gel reaction. The molecular chains of the organic proton conductive polymer and the metal oxide derivative are formed by interpenetrating each other. The network structure is preferable because it is stronger.

  Examples of silicon alkoxides that do not contain amino groups include tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetra-i-propoxysilane, tetra-n-butoxysilane, tetraacetyloxysilane, tetraphenoxysilane, and methyl. Trimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, n-butyl Trimethoxysilane, n-butyltriethoxysilane, n-pentyltrimethoxysilane, n-pentyltriethoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, phenyl Limethoxysilane, phenyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4 -Epoxycyclohexyl) ethyltriethoxysilane, 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, vinyltri Acetoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, 2-hydroxyethyl Limethoxysilane, 2-hydroxyethyltriethoxysilane, 2-hydroxypropyltrimethoxysilane, 2-hydroxypropyltriethoxysilane, 3-hydroxypropyltrimethoxysilane, 3-hydroxypropyltriethoxysilane, 3-mercaptopropyltrimethoxy Silane, 3-mercaptopropyltriethoxysilane, 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane methyltriacetyloxysilane, methyl Triphenoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, di-n-propyldimeth Xisilane, di-n-propyldiethoxysilane, di-i-propyldimethoxysilane, di-i-propyldiethoxysilane, di-n-butyldimethoxysilane, di-n-butyldiethoxysilane, n-pentyl methyl Dimethoxysilane, n-pentyl methyldiethoxysilane, cyclohexyl methyldimethoxysilane, cyclohexyl methyldiethoxysilane, phenyl methyldimethoxysilane, phenyl methyldiethoxysilane, di-n-pentyldimethoxysilane, di-n- Pentyldiethoxysilane, di-n-hexyldimethoxysilane, di-n-hexyldiethoxysilane, di-n-heptyldimethoxysilane, di-n-heptyldiethoxysilane, di-n-octyldimethoxysilane, di-n -Octyldiethoxy Orchids, dicyclohexyl dimethoxysilane, dicyclohexyl diethoxysilane, diphenyl dimethoxysilane, di-alkoxysilanes such as diphenyl diethoxy silane, dimethyl acetyl silane, can be cited dimethyl phenoxy silane. These may be used alone or as a mixture.

  When a bifunctional or trifunctional silicon alkoxide containing an amino group is used, the amount of amino group added to the proton dissociable group in the organic proton conductive polymer is 0.05 to 0.55 equivalents. A range is preferable. If it is 0.05 or less, the compatibility improvement effect between the organic proton conductive polymer and the metal oxide is weak, which is not preferable. If it is 0.55 equivalent or more, a proton-dissociable group and a salt that express proton conductivity are not preferable. Since it forms, proton conductivity does not express and it is not preferable.

The amount of amino group here is defined by the equivalent amount of amino group described below.
Equivalent amino group = (number of molecules of amino group to be added) / (number of molecules of proton dissociable group in organic proton conducting polymer)
(The number of proton-dissociable groups in the organic proton-conducting polymer was calculated from the equivalent weight of ion-exchange groups obtained by determining the amount introduced by 1H-NMR.)

  Specific examples of metal alkoxides other than silicon alkoxide include titanium alkoxides such as tetraisopropoxy titanium, tetra-n-butoxy titanium, and tetra-t-butoxy titanium, aluminum such as tri-isopropoxy aluminum and tri-n-butoxy aluminum. Examples thereof include alkoxide and tetra-n-butoxyzirconium.

Next, the phosphoric acid compound or phosphorous acid compound used in the present invention will be described.
Phosphoric acid represented by the following general formula (1) or a derivative thereof, or phosphorous acid represented by the following general formula (2) or a derivative thereof is preferable.
PO (OR) 3-y (OH) y (1)
[In the formula, R represents a monovalent organic group having 1 to 6 carbon atoms, and y is an integer of 0 to 3. ]
P (OR) 3-z (OH) z (2)
[In the formula, R represents a monovalent organic group having 1 to 6 carbon atoms, and z represents an integer of 0 to 3. ]

  Examples of the monovalent organic group having 1 to 6 carbon atoms in the general formula (1) include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, and a t-butyl group. Group, n-pentyl group, phenyl group and the like.

  In general formula (1), y is 0 to 3, and specific examples of y being 0 are phosphoric acid trimethyl ester, phosphoric acid triethyl ester, phosphoric acid tripropyl ester, phosphoric acid tributyl ester, phosphoric acid. A triphenyl ester etc. can be mentioned.

  In the general formula (1), specific examples of y being 1 or 2 include phosphoric acid dimethyl ester, phosphoric acid diethyl ester, phosphoric acid dipropyl ester, phosphoric acid dibutyl ester, phosphoric acid diphenyl ester, phosphoric acid. Prepared by dissolving P2O5 in methanol, ethanol, propanol, butanol, pentanol, phenol, etc. in addition to methyl ester, ethyl phosphate, propyl phosphate, butyl phosphate, phenyl phosphate, etc. Is mentioned. Further, as a specific example where y is 3, orthophosphoric acid can be mentioned.

  Examples of the monovalent organic group having 1 to 6 carbon atoms in the general formula (2) include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, and t-butyl. Group, n-pentyl group, phenyl group and the like.

  In the general formula (2), z is 0 to 3, and specific examples of z being 0 are trimethyl phosphite, triethyl phosphite, tripropyl phosphite, tributyl phosphite. Examples thereof include esters and triphenyl phosphite.

  In the general formula (2), specific examples of z = 1 are dimethyl phosphite, diethyl phosphite, dipropyl phosphite, dibutyl phosphite, diphenyl phosphite. In addition, as specific examples of z being 2, phosphorous acid methyl ester, phosphorous acid ethyl ester, phosphorous acid propyl ester, phosphorous acid butyl ester, phosphorous acid phenyl ester, and z being 3 Specific examples include phosphorous acid.

  The phosphoric acid compound in the present invention means a gelation inhibitor of a metal oxide at the time of adjusting the proton conductive membrane, and if it is 0.5% by weight or less, gelation occurs at the time of producing the proton conductive membrane, and at 30% by weight or more If so, phosphoric acid is not sufficiently fixed, and the phosphoric acid leaks with water generated during operation of the fuel cell, and the proton conducting membrane becomes porous, so that methanol crossover cannot be suppressed.

  From the viewpoint of phosphoric acid fixation, it is preferable to use a metal alkoxide containing at least one of titanium, aluminum and zirconium which are highly reactive metal alkoxides.

  In this way, it has sufficient suppression for swelling with water, methanol, etc. (dimensional stability), methanol solubility resistance, proton conductivity and durability (oxidation resistance) sufficient for use as a polymer electrolyte fuel cell. A proton conducting membrane can be realized. In addition, it is possible to realize a proton conductive membrane that is excellent in either flexibility or film forming property.

  An assembly of a catalyst electrode and a proton conductive membrane (in this specification, an electrode / membrane) in which a catalyst electrode carrying a metal supported on a conductive material is disposed on both sides of a membrane (proton conductive membrane) made of this proton conductive membrane. / May be referred to as an electrode unit.) Can be suitably applied to a fuel cell with one electrode as an oxidant electrode, the other electrode as a fuel electrode, and a proton conducting membrane as an electrolyte.

  The catalyst electrode here can be prepared by supporting a metal serving as a catalyst on a conductive material. The metal used for the catalyst electrode may be any metal that promotes the fuel oxidation reaction and the oxidant reduction reaction, for example, the hydrogen oxidation reaction and the oxygen reduction reaction, such as platinum, gold, and the like. Silver, palladium, iridium, rhodium, ruthenium, iron, cobalt, nickel, chromium, tungsten, manganese, vanadium or alloys thereof. Platinum is particularly preferable.

  The shape of the metal serving as the catalyst is arbitrary, but in the case of a particulate shape, the particle size is generally 100 to 3000 nm.

  As the conductive material to be used, any conductive material may be used, and examples thereof include various metals and carbon materials. Examples of the carbon material include carbon black such as furnace black, channel black, and acetylene black, activated carbon, and graphite. These may be used alone or in combination. As a method of supporting the catalyst metal on these conductive materials, a method of depositing a metal as a catalyst on the surface of the conductive material by a reduction method, a method of suspending the catalyst metal in a solvent, and applying this to the surface of the conductive material, etc. There is.

  When these metals are attached to a conductive material (carrier) made of electrically conductive fine particles such as carbon fine particles, the amount used as a catalyst is small, which is advantageous in terms of cost. The amount of these metals supported is preferably 0.01 to 10 mg / cm <2> per one side area in the state where one electrode is formed. As such electrically conductive fine particles, carbon fine particles are particularly preferable.

  When the organic proton conductive polymer described above is added to the catalyst electrode in which the metal is supported on the electrically conductive fine particles, the shape can be easily maintained or deformed while maintaining the performance as the catalyst electrode. Therefore, it is preferable. Specifically, electrically conductive fine particles carrying a metal are added to an organic proton conductive polymer solution to prepare a paste (electrode forming solution). Apply to both sides of the film and dry. In this way, an electrode / membrane / electrode unit in which the catalyst electrode is bonded to both sides of the proton conducting membrane can be produced.

  The fuel cell according to the present invention can be produced using the electrode / membrane / electrode unit formed as described above. An example of using methanol as the fuel and air as the oxidant will be described with reference to FIG. In FIG. 1, the single cell includes a stack body 9, a fuel tank 11 that stores liquid fuel 12, and an introduction pipe 13 that supplies liquid fuel from the fuel tank 11 to the body 9. The liquid fuel is introduced into each unit cell constituting the stack body 9 via the liquid fuel introduction unit 10.

  The components of each single battery constituting the stack body 9 will be described. Each unit cell includes an electrode / membrane / electrode unit 4 including a proton conducting membrane 1, a fuel electrode 2, and an oxidant electrode 3. Each unit cell includes a fuel permeation section 6 having a function of retaining liquid fuel and a fuel vaporization section 7 for guiding the gaseous fuel vaporized by the liquid fuel retained in the fuel permeation section 6 to the fuel electrode 2. 2 is provided adjacent. A stack type fuel cell 9 is configured by stacking a plurality of unit cells each including the fuel permeation unit 6, the fuel vaporization unit 7, and the electrode / membrane / electrode unit 4 through the separator 5. An oxidant gas supply groove 8 for flowing an oxidant gas is installed as a continuous groove on the oxidant electrode 3 side of the separator 5.

  As a means for supplying liquid fuel from the fuel tank 11 to the fuel penetration part 6 of the single cell, it is conceivable to form a liquid fuel introduction part connected to the fuel tank along at least one side face of the stack 9 along this face. The liquid fuel introduced into the liquid fuel introduction unit 10 is supplied from the side surface of the stack 9 to the fuel permeation unit 6, further vaporized by the fuel vaporization unit 7, and supplied to the fuel electrode 2. At this time, by configuring the fuel permeation portion 6 with a material exhibiting capillary action, liquid fuel can be supplied to the fuel permeation portion by capillary force without using an auxiliary device. For this purpose, it is necessary that the liquid fuel introduced into the liquid fuel introduction unit 10 is in direct contact with one end of the fuel permeation unit 6. The liquid fuel introduction part 10 and the main body 9 must be insulated except for the fuel permeation part 6.

  In the case where the stack 9 is formed by stacking single cells, the separator 5, the fuel permeation portion 6, and the fuel vaporization portion 7 also function as a current collecting plate that conducts the generated electrons, and therefore a porous body containing carbon. Formed of a conductive material.

  As described above, the separator 5 in the unit cell can reduce the number of parts and reduce the size of the fuel cell by using the separator 5 having both functions of the channel through which the oxidant gas flows.

  As a method for supplying the liquid fuel from the fuel storage tank 11 to the liquid fuel introduction unit 10, there is a method in which the liquid fuel accommodated in the fuel storage tank is freely dropped and introduced into the liquid fuel introduction unit 10. Although this method has a structural restriction that the fuel storage tank must be provided at a position higher than the upper surface of the stack 9, the liquid fuel can be reliably introduced into the liquid fuel introduction unit 10. As another method, there is a method of drawing the liquid fuel from the fuel storage tank 11 by the capillary force of the liquid fuel introduction unit 10. When this method is adopted, the connection point of the fuel storage tank 11, the liquid fuel storage tank 11 and the liquid fuel introduction part 10, that is, the position of the fuel inlet provided in the liquid fuel introduction part 10 is made higher than the upper surface of the stack 9. There is no need. When combined with the natural fall method, the installation location of the fuel tank 11 can be freely set.

  However, it is desirable that the liquid fuel introduced into the liquid fuel introduction unit 10 by capillary force is continuously set so that the capillary force to the fuel permeation unit 6 is larger than the capillary force. Note that the number of liquid fuel introduction portions 10 is not limited to one along the side surface of the stack 9, and the liquid fuel introduction portions 6 can be formed on the other side surface of the stack.

  Further, the fuel storage tank 11 described above can be detachable from the stack 9. This makes it possible to continue the operation of the battery for a long time by replacing the fuel storage tank. Further, the supply of the liquid fuel from the fuel storage tank 11 to the liquid fuel introduction unit 10 is configured to extrude the liquid fuel by the natural fall as described above, the internal pressure or the like in the tank, or the capillary force of the liquid fuel introduction unit 10. The fuel can be drawn out by the above.

  The liquid fuel introduced into the liquid fuel introduction unit 10 by the method described above is supplied to the fuel penetration unit 6. The form of the fuel permeation unit 6 is not particularly limited as long as it has a function of holding the liquid fuel therein and supplying only the vaporized fuel to the fuel electrode through the fuel supply vaporization unit 7. For example, a liquid fuel passage may be provided, and a gas-liquid separation membrane may be provided at the interface with the fuel vaporization unit 7. Furthermore, when supplying liquid fuel to the fuel penetration part 6 by capillary force, the form of the fuel penetration part 6 will not be specifically limited if liquid fuel can be penetrated by capillary force. In addition to a porous body composed of particles and fillers, a nonwoven fabric produced by a papermaking method, a woven fabric woven with fibers, and the like, gaps formed between plates of glass or plastic can also be used.

  Here, the case where a porous body is used as the fuel permeation portion 6 will be described. As a capillary force for drawing liquid fuel to the fuel permeation portion side, first, the capillary force of the porous body itself constituting the fuel permeation portion 6 is as follows. Can be mentioned. When such a capillary force is used, a so-called continuous hole is formed by connecting the holes of the fuel permeation unit 6 that is a porous body, the hole diameter is controlled, and the side surface of the fuel permeation unit 6 on the liquid fuel introduction side 10 is controlled. By forming continuous holes from at least one other surface, it is possible to supply liquid fuel smoothly in the lateral direction with capillary force.

  The pore diameter and the like of the porous body used as the fuel permeation section 6 are not particularly limited as long as it can be drawn into the liquid fuel of the liquid fuel introduction section 10. The capillary of the liquid fuel introduction section 10 is not particularly limited. Considering the force, it is preferable to be about 0.01 to 150 μm.

  Moreover, it is preferable that the volume of the hole used as the parameter | index of the continuity of the hole in a porous body shall be about 20 to 90%. When the pore diameter is smaller than 0.01 μm, it is difficult to manufacture the fuel permeation portion, while when it exceeds 150 μm, the capillary force may be reduced. Further, if the pore volume is less than 20%, the amount of continuous pores is reduced and the number of closed pores is increased, so that it is difficult to obtain sufficient capillary force. Practically, the porous body constituting the fuel infiltration portion 6 preferably has a pore diameter in the range of 0.5 to 100 μm, and the pore volume in the range of 30 to 75%.

Next, examples and comparative examples of the present invention will be described in detail. In addition, the following processes, tests, and measurements were adopted.
<Proton conductive membrane pretreatment>
The produced proton conducting membrane was immersed in 0.1N HCl overnight to remove the solvent, then washed with ion-exchanged water for 2 hours, wiped off the surface water, and then dried under reduced pressure at 120 ° C. for 2 hours.

<Solvent dissolution test>
The pretreated proton conductive membrane (1 cm × 4 cm) was immersed in 20 mL of% NMP for 3 days at room temperature and dried at 120 ° C. for 3 hours, and the change in weight before and after immersion was measured.
Solubility (% by weight) = {[(weight before NMP immersion−weight after NMP immersion)] / (weight before immersion in NMP aqueous solution)} × 100

<Measurement of viscoelasticity>
Using an RSA-II viscoelasticity measuring device, the storage elastic modulus was measured in a temperature range of 30 ° C to 300 ° C. The storage elastic modulus reduction rate was calculated as follows.
(Storage Elastic Modulus of Proton Conducting Membrane Prepared at 30 ° C.—Storage Elastic Modulus at Temperature at which Main Dispersion Derived from Micro Brownian Motion of Molecular Chain of Organic Proton Conducting Polymer of Proton Conducting Membrane) / (30 ° C. Storage modulus of proton conducting membrane prepared in

<Swelling degree measurement (area change)>
The pre-treated proton conducting membrane (1 cm × 4 cm) was treated in MeOH at room temperature for 1 hour, and the degree of swelling was calculated from the area change before and after the treatment.
Swelling degree (%) = {[(Area after immersion in MeOH) − (Area before immersion in MeOH)] / (Area before immersion in MeOH aqueous solution)} X100

<Measurement of proton conductivity>
The measurement was carried out at room temperature after the sample was immersed in a 30% MeOH aqueous solution. The impedance was measured by an alternating current method using a Solartron impedance analyzer. A frequency sweep with an amplitude of 10 mV and 10 k to 1 kHz was performed, the obtained colle-coll plot was linearly approximated, and the intercept with the real axis was defined as resistance.
As shown in FIG. 3, the proton conductive membrane 15 after the above pretreatment was disposed, platinum plates 16 were disposed above and below it, and the resistance was measured by appropriately energizing between the platinum plates to calculate the conductivity.
Proton conductivity = 1 / [(resistance) × (sample film thickness) × (sample area)]

<Methanol dissolution test>
The pretreated proton conductive membrane (1 cm × 4 cm) was immersed in 20 mL of MeOH at 25 ° C. for 3 days and dried at 120 ° C. for 3 hours, and the change in weight before and after immersion was measured.

<Synthesis of organic proton conducting polymer>
[Reference Example 1]
10 g of the pulverized polyether ether ketone was gradually added to 200 mL of concentrated sulfuric acid, and the sulfonation reaction was performed for 5 hours. After completion of the reaction, it is washed 3 times with 4 L of ion exchange water, recovered by filtration, dried at 120 ° C. overnight, and sulfonated polyether which is one of the organic proton conductive polymers according to the present invention. Ether ketone was obtained. The sulfonation rate calculated by 1H-NMR was 58 mol% (EW: 576).

[Reference Example 2]
10 g of pulverized polyethersulfone was gradually added to 200 mL of concentrated sulfuric acid, and the sulfonation reaction was carried out for 5 hours. After completion of the reaction, it was washed 3 times with 4 L of ion exchange water, recovered by filtration, dried at 120 ° C. overnight, and sulfonated polyethersulfone, which is one of the organic proton conductive polymers according to the present invention. Got. The sulfonation rate calculated by 1H-NMR was 35 mol% (EW: 742).

[Example 1]
Dissolve 0.85 g of titanium tetraisopropoxide in 5 ml of NMP, add 1.18 g of phosphoric acid and react at 30 ° C. for 3 hours. Further, 2.5 g of tetraethoxysilane, 3-aminopropyltriethoxysilane 0 0.1 g (amino group equivalent: 0.14) was added and reacted at 30 ° C. for 3 hours to prepare a solution containing a metal oxide. 4 g of this solution was added to an NMP solution (5.7 mL) in which 1 g of a sulfonated polyether ether ketone having a sulfonation rate of 58 mol% prepared in Reference Example 1 was dissolved, and the mixture was stirred at 80 ° C. for 3 hours.

Thereafter, using an applicator, the film was coated on a glass substrate and dried under conditions of 150 ° C. for 2 hours to obtain a proton conductive membrane having an organic proton conductive polymer of 52% by weight.
In the NMP dissolution test of the obtained proton conducting membrane, the solubility was 8% by weight and substantially no solubility was exhibited.

Further, the decrease rate of the storage elastic modulus in the dynamic viscoelasticity measurement of the proton conducting membrane was 20%, and the relaxation of the storage elastic modulus was small.
Furthermore, in observation of the proton conducting membrane with an electron microscope, the metal alkoxide derivative was observed only in a size substantially less than a micron order.

From the above, it was confirmed that the proton conducting membrane had a network structure in which the molecular chains of the organic proton conducting polymer and the metal alkoxide derivative entered each other.
In the obtained proton conducting membrane methanol dissolution test, the solubility was 1% by weight and substantially no solubility was exhibited.

In the measurement of the degree of swelling, the degree of swelling (%) was 25% in methanol and 20% in 30% aqueous methanol. The proton conductivity measured by proton conductivity was 2.0 × 10 ⁻³ S / cm.
From these results, it is understood that methanol solubility resistance is exhibited, swelling degree can be suppressed, and proton conductivity sufficient for use as a polymer electrolyte fuel cell is obtained.

[Example 2]
Dissolve 0.85 g of titanium tetraisopropoxide in 5 ml of NMP, add 1.18 g of phosphoric acid and react at 30 ° C. for 3 hours. Further, 2.5 g of tetraethoxysilane, 3-aminopropyltriethoxysilane 0 0.1 g (amino group equivalent: 0.18) was added and reacted at 30 ° C. for 3 hours to prepare a solution containing a metal oxide. 4 g of this solution was added to an NMP solution (5.7 mL) in which 1 g of a sulfonated polyethersulfone having a sulfonation rate of 20 mol% prepared in Reference Example 2 was dissolved, and the mixture was stirred at 80 ° C. for 3 hours.

Thereafter, using an applicator, the film was coated on a glass substrate and dried under conditions of 150 ° C. for 2 hours to obtain a proton conductive membrane having an organic proton conductive polymer of 52% by weight.
In the NMP dissolution test of the obtained proton conducting membrane, the solubility was 12% by weight, and substantially no solubility was exhibited.

Further, the decrease rate of the storage elastic modulus in the dynamic viscoelasticity measurement of the proton conducting membrane was 30%, and the relaxation of the storage elastic modulus was small.
Furthermore, in observation of the proton conducting membrane with an electron microscope, the metal alkoxide derivative was observed only in a size substantially less than a micron order.

From the above, it was confirmed that the proton conducting membrane had a network structure in which the molecular chains of the organic proton conducting polymer and the metal alkoxide entered each other.
In the obtained proton conducting membrane methanol dissolution test, the solubility was 2% by weight and substantially no solubility was exhibited.

In the degree of swelling measurement, the degree of swelling (%) was 27% in methanol and 22% in 30% aqueous methanol. The proton conductivity measured by proton conductivity was 1.7 × 10 ⁻³ S / cm.
From these results, it is understood that methanol solubility resistance is exhibited, swelling degree can be suppressed, and proton conductivity sufficient for use as a polymer electrolyte fuel cell is obtained.

[Example 3]
Dissolve 0.85 g of titanium tetraisopropoxide in 5 ml of NMP, add 1.18 g of phosphoric acid, react at 30 ° C. for 3 hours, and further 2.5 g of tetraethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane 0.1g (amino group equivalent: 0.2) was added and reacted at 30 ° C for 3 hours to prepare a solution containing a metal oxide.
4 g of this solution was added to an NMP solution (5.7 mL) in which 1 g of a sulfonated polyether ether ketone having a sulfonation rate of 58 mol% prepared in Reference Example 1 was dissolved, and the mixture was stirred at 80 ° C. for 3 hours.

Thereafter, using an applicator, the film was coated on a glass substrate and dried under conditions of 150 ° C. for 2 hours to obtain a proton conductive membrane having an organic proton conductive polymer of 52% by weight.
In the NMP dissolution test of the obtained proton conducting membrane, the solubility was 8% by weight and substantially no solubility was exhibited.

Further, the decrease rate of the storage elastic modulus in the dynamic viscoelasticity measurement of the proton conducting membrane was 20%, and the relaxation of the storage elastic modulus was small.
Furthermore, in observation of the proton conducting membrane with an electron microscope, the metal alkoxide derivative was observed only in a size substantially less than a micron order.

From the above, it was confirmed that the proton conducting membrane had a network structure in which the molecular chains of the organic proton conducting polymer and the metal alkoxide derivative entered each other.
In the obtained proton conducting membrane methanol dissolution test, the solubility was 1% by weight and substantially no solubility was exhibited.

In the measurement of the degree of swelling, the degree of swelling (%) was 25% in methanol and 20% in a 30% aqueous methanol solution. The proton conductivity measured by proton conductivity was 2.0 × 10 ⁻³ S / cm.
From these results, it is understood that methanol solubility resistance is exhibited, swelling degree can be suppressed, and proton conductivity sufficient for use as a polymer electrolyte fuel cell is obtained.

[Example 4]
An NMP solution containing 10% by weight of sulfonated polyetheretherketone is added to 40% by weight of platinum-supported carbon so that the weight ratio of platinum-supported carbon and sulfonated polyetheretherketone is 2: 1. To prepare a paste (electrode forming solution). This electrode forming solution was applied to both sides of the proton conducting membrane obtained in Example 1, and then dried to prepare an electrode / membrane / electrode unit having a platinum loading of 4 mg / cm ² . The obtained electrode / membrane / electrode unit exhibited good shape retention, and even when bent by hand, neither cracking nor peeling occurred.

[Example 5]
An NMP solution containing 10% by weight of sulfonated polyethersulfone is added to 40% by weight of platinum-supported carbon so that the weight ratio of platinum-supported carbon to sulfonated sulfone is 2: 1 and dispersed uniformly. A paste (electrode forming solution) was prepared. This electrode forming solution was applied to both sides of the proton conducting membrane obtained in Example 2 and then dried to prepare an electrode / membrane / electrode unit having a platinum loading of 4 mg / cm ² . The obtained electrode / membrane / electrode unit exhibited good shape retention, and even when bent by hand, neither cracking nor peeling occurred.

[Example 6]
<Fuel cell single cell performance evaluation>
Using the proton conducting membrane prepared in Example 1, an electrode / membrane / electrode unit was prepared and incorporated in the evaluation cell shown in FIG. 1, and the fuel cell output performance was evaluated. A 10M methanol aqueous solution was supplied as a fuel, air was allowed to flow, and both sides of the cell were heated to 40 ° C. to obtain a current of 10 mA / cm ² , and the temporal stability of the battery performance was observed. As a result, the output was stable even after several hours.

[Example 7]
<Fuel cell single cell performance evaluation>
Using the proton conducting membrane prepared in Example 2, an electrode / membrane / electrode unit was prepared and incorporated in the evaluation cell shown in FIG. 1, and the fuel cell output performance was evaluated. A 10M methanol aqueous solution was supplied as a fuel, air was allowed to flow, and both surfaces of the cell were heated to 40 ° C. to obtain a current of 10 mA / cm ² , and the temporal stability of the battery performance was observed. As a result, the output was stable even after several hours.

[Comparative Example 1]
An NMP solution (5.7 mL) obtained by dissolving 1 g of a sulfonated polyether ether ketone having a sulfonation rate of 58 mol% obtained in Reference Example 1 was prepared, and a film-like material was formed on a glass substrate using an applicator. And dried at 150 ° C. for 2 hours to obtain a proton conducting membrane.
In the NMP dissolution test of the obtained proton conducting membrane, the solubility was 100% by weight and was completely dissolved.
In the obtained proton conducting membrane methanol dissolution test, the solubility was 100% by weight and was completely dissolved.

[Comparative Example 2]
An NMP solution (5.7 mL) obtained by dissolving 1 g of a sulfonated polyethersulfone having a sulfonation rate of 20 mol% obtained in Reference Example 2 was prepared, and a film was formed on a glass substrate using an applicator. This was applied and dried at 150 ° C. for 2 hours to obtain a proton conducting membrane.
In the NMP dissolution test of the obtained proton conducting membrane, the solubility was 100% by weight and was completely dissolved.
In the obtained proton conducting membrane methanol dissolution test, the solubility was 100% by weight and was completely dissolved.

[Comparative Example 3]
A solution containing metal oxide was prepared by dissolving 2.5 g of tetraethoxysilane in 5 ml of NMP, adding 1 ml of 1N hydrochloric acid, and reacting at 30 ° C. for 3 hours. 3 g of this solution was added to an NMP solution (5.7 mL) in which 1 g of a sulfonated polyether ether ketone having a sulfonation rate of 58 mol% was dissolved, reacted at 80 ° C. for 3 hours, and then made of glass using an applicator. The film was coated on the substrate in a film form and dried at 150 ° C. for 2 hours to obtain a proton conductive membrane having a metal alkoxide content of 52% by weight.
In the NMP dissolution test of the obtained proton conducting membrane, the solubility was 30% by weight, indicating solubility.
Further, the decrease rate of the storage elastic modulus in the dynamic viscoelasticity measurement of the proton conducting membrane was 93%, and the relaxation of the storage elastic modulus was large.

From the above, it was not confirmed that the proton conducting membrane had a network structure in which the molecular chains of the organic proton conducting polymer and the metal alkoxide entered each other.
In the obtained proton conducting membrane methanol dissolution test, the solubility was 25% by weight.
In the degree of swelling measurement, the degree of swelling (%) was 75% in methanol and 70% in a 30% aqueous methanol solution.
From these results, it is understood that methanol solubility is exhibited and it is insufficient for use as a direct methanol type polymer electrolyte fuel cell.

[Comparative Example 4]
A solution containing metal oxide was prepared by dissolving 2.5 g of tetraethoxysilane and 0.5 g of tetraisopropoxytitanium in 5 ml of NMP, adding 1 ml of water and reacting at 30 ° C. for 3 hours. 3 g of this solution was added to an NMP solution (5.7 mL) in which 1 g of a sulfonated polyethersulfone having a sulfonation rate of 35 mol% prepared in Reference Example 2 was dissolved, and the mixture was stirred at 80 ° C. for 3 hours.

Thereafter, using an applicator, the film was coated on a glass substrate and dried under conditions of 150 ° C. for 2 hours to obtain a proton conductive membrane having an organic proton conductive polymer of 52% by weight.
The obtained proton conducting membrane was a good membrane having a uniform thickness, and did not break even when bent by hand, and showed good flexibility.
In the NMP dissolution test of the obtained proton conducting membrane, the solubility was 35% by weight, indicating solubility.
Further, the decrease rate of the storage elastic modulus in the dynamic viscoelasticity measurement of the proton conducting membrane was 95%, and the relaxation of the storage elastic modulus was large.

From the above, it was not confirmed that the proton conducting membrane had a network structure in which the molecular chains of the organic proton conducting polymer and the metal alkoxide entered each other.
In the obtained proton conducting membrane methanol dissolution test, the solubility was 30% by weight, indicating solubility.
In the degree of swelling measurement, the degree of swelling (%) was 80% in methanol and 75% in 30% aqueous methanol.
From these results, it is understood that methanol solubility is exhibited and it is insufficient for use as a direct methanol type polymer electrolyte fuel cell.

[Comparative Example 5]
Dissolve 0.85 g of titanium tetraisopropoxide in 5 ml of NMP, add 1.18 g of phosphoric acid, react at 30 ° C. for 3 hours, add 2.5 g of tetraethoxysilane and react at 30 ° C. for 3 hours. And a solution containing a metal oxide was prepared.
4 g of this solution was added to an NMP solution (5.7 mL) in which 1 g of a sulfonated polyether ether ketone having a sulfonation rate of 58 mol% prepared in Reference Example 1 was dissolved, and the mixture was stirred at 80 ° C. for 3 hours.

Thereafter, using an applicator, the film was coated on a glass substrate and dried under conditions of 150 ° C. for 2 hours to obtain a proton conductive membrane containing 58% by weight of organic proton conductive polymer.
In the NMP dissolution test of the obtained proton conducting membrane, the solubility was 13% by weight, indicating solubility.
Further, the decrease rate of the storage elastic modulus in the dynamic viscoelasticity measurement of the proton conducting membrane was 91%, and the relaxation of the storage elastic modulus was large.

From the above, it was not confirmed that the proton conducting membrane had a network structure in which the molecular chains of the organic proton conducting polymer and the metal alkoxide entered each other.
In the obtained proton conducting membrane methanol dissolution test, the solubility was 20% by weight, indicating solubility.
In the degree of swelling measurement, the degree of swelling (%) was 55% in methanol and 50% in a 30% aqueous methanol solution.
From these results, it is understood that methanol solubility is exhibited and it is insufficient for use as a direct methanol type polymer electrolyte fuel cell.

[Comparative Example 6]
Dissolve 0.85 g of titanium tetraisopropoxide in 5 ml of NMP, add 1.18 g of phosphoric acid, react at 30 ° C. for 3 hours, add 2.5 g of tetraethoxysilane, and add at 30 ° C. for 3 hours. Reaction was performed and the solution containing a metal oxide derivative was prepared.
4 g of this solution was added to an NMP solution (5.7 mL) in which 1 g of a sulfonated polyethersulfone having a sulfonation rate of 35 mol% prepared in Reference Example 2 was dissolved, and the mixture was stirred at 80 ° C. for 3 hours.

Thereafter, using an applicator, the film was coated on a glass substrate and dried under conditions of 150 ° C. for 2 hours to obtain a proton conductive membrane containing 58% by weight of organic proton conductive polymer.
In the NMP dissolution test of the obtained proton conducting membrane, the solubility was 17% by weight, indicating solubility.
Further, the decrease rate of the storage elastic modulus in the dynamic viscoelasticity measurement of the proton conducting membrane was 93%, and the relaxation of the storage elastic modulus was large.

From the above, it was not confirmed that the proton conducting membrane had a network structure in which the molecular chains of the organic proton conducting polymer and the metal alkoxide entered each other.
In the obtained proton conducting membrane methanol dissolution test, the solubility was 25% by weight, indicating solubility.
In the degree of swelling measurement, the degree of swelling (%) was 60% in methanol and 55% in a 30% aqueous methanol solution.

[Comparative Example 7]
Dissolve 0.85 g of titanium tetraisopropoxide in 5 ml of NMP, add 1.18 g of phosphoric acid, react at 30 ° C. for 3 hours, and further add 2.5 g of tetraethoxysilane and 3-aminopropyltrimethoxysilane. 0.1 g was added and reacted at 30 ° C. for 3 hours to prepare a solution containing a metal oxide derivative.
2.5 g of this solution was added to an NMP solution (5.7 mL) in which 1 g of a sulfonated polyethersulfone having a sulfonation rate of 35 mol% prepared in Reference Example 2 was dissolved, and the mixture was stirred at 80 ° C. for 3 hours.

Thereafter, using an applicator, the film was coated on a glass substrate and dried under conditions of 150 ° C. for 2 hours to obtain a proton conductive membrane containing 65% by weight of organic proton conductive polymer.
In the NMP dissolution test of the obtained proton conducting membrane, the solubility was 17% by weight, indicating solubility.
Further, the decrease rate of the storage elastic modulus in the dynamic viscoelasticity measurement of the proton conducting membrane was 93%, and the relaxation of the storage elastic modulus was large.

From the above, it was not confirmed that the proton conducting membrane had a network structure in which the molecular chains of the organic proton conducting polymer and the metal alkoxide entered each other.
In the obtained proton conducting membrane methanol dissolution test, the solubility was 25% by weight, indicating solubility.
In the degree of swelling measurement, the degree of swelling (%) was 60% in methanol and 55% in a 30% aqueous methanol solution.

[Comparative Example 8]
Dissolve 0.85 g of titanium tetraisopropoxide in 5 ml of NMP, add 1.18 g of phosphoric acid and react at 30 ° C. for 3 hours. Further, 2.5 g of tetraethoxysilane, 3-aminopropyltriethoxysilane 0 0.1 g (amino group equivalent: 1.76) was added and reacted at 30 ° C. for 3 hours to prepare a solution containing a metal oxide. 4 g of this solution was added to an NMP solution (5.7 mL) in which 0.1 g of a sulfonated polyether ether ketone having a sulfonation rate of 58 mol% prepared in Reference Example 1 was dissolved, and the mixture was stirred at 80 ° C. for 3 hours. .

  Then, using an applicator, the film was coated on a glass substrate and dried at 150 ° C. for 2 hours. However, cracks occurred and a proton conducting membrane could not be obtained.

It is the schematic which shows a fuel cell (single cell) typically. Schematic showing the structure of the cell in the stack main body of a fuel cell. Schematic of the proton conductivity measurement method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Proton conductive membrane 2 Fuel electrode 3 Oxidant electrode 4 Electromotive part 5 Separator 6 Fuel penetration part 7 Fuel vaporization part 8 Oxidant gas supply groove 9 Stack main body 10 Liquid introduction path 11 Fuel tank 12 Liquid fuel 13 Inlet pipe 14 Junction 15 Proton conducting membrane 16 Platinum plate

Claims (15)

(1) A silicon alkoxide (A) containing an amino group, a silicon alkoxide (B) containing no amino group, a metal alkoxide (C) containing any one or more of titanium, aluminum and zirconium and a phosphoric acid compound or Preparing a first solution containing the metal oxide derivative by hydrolyzing and condensing the phosphorous acid compound (D);
(2) Next, the first solution contains an organic proton conductive polymer having a temperature (T) of 60 ° C. to 270 ° C. at which main dispersion derived from micro-Brownian motion of molecular chains in dynamic viscoelasticity measurement is observed. Adding to the solution to prepare a second solution containing the organic proton conductive polymer and the metal oxide derivative;
(3) a proton conducting membrane obtained by casting from the second solution,
A proton conductive membrane in which the rate of decrease in storage elastic modulus at a temperature (T) relative to the storage elastic modulus at 30 ° C. is 90% or less in the dynamic viscoelasticity measurement of the proton conductive membrane.   The proton conducting membrane according to claim 1, comprising 20 to 60% by weight of the organic proton conducting polymer.   3. The proton conducting membrane according to claim 1, wherein the organic proton conducting polymer is an organic proton conducting polymer having a proton dissociable group at a side chain end.   The proton conductive membrane according to claim 3, wherein the proton dissociable group is at least one of a sulfonic acid group, a phosphonic acid group, a sulfonamide group, a sulfonimide group, and derivatives thereof.   The proton conductive membrane according to claim 1 or 2, wherein the organic proton conductive polymer is sulfonated polyetheretherketone or sulfonated polyethersulfone.   The proton according to claim 3 or 4, wherein the amino group content of the silicon alkoxide containing an amino group is 0.05 to 0.55 equivalent to the proton dissociable group in the organic proton conductive polymer. Conductive membrane.   2. The proton conducting membrane according to claim 1, comprising 0.5 to 30% by weight of a phosphoric acid compound or a phosphorous acid compound with respect to 100% by weight of the proton conducting membrane.   2. The proton conducting membrane according to claim 1, which has a solubility of 5% or less when held in methanol or a methanol aqueous solution having a concentration of 10 to 69% by volume at 25 ° C. for 72 hours.   A joined body of a catalyst electrode and a proton conductive membrane, wherein a catalyst electrode in which a metal is supported on a carrier made of electrically conductive fine particles is disposed on both surfaces of the proton conductive membrane according to claim 1.   The joined body of a catalyst electrode and a proton conductive membrane according to claim 9, wherein the electrically conductive fine particles include carbon fine particles.   The joined body of a catalyst electrode and a proton conductive membrane according to claim 9 or 10, wherein the catalyst electrode contains an organic proton conductive polymer.   The joined body of a catalyst electrode and a proton conductive membrane according to claim 11, wherein the organic proton conductive polymer has a proton dissociable group at a side chain end.   The catalyst electrode according to claim 12, wherein the proton dissociable group in the organic proton conductive polymer is at least one of a sulfonic acid group, a phosphonic acid group, a sulfonamide group, a sulfonimide group, and derivatives thereof. And proton conductive membrane.   The joined body of the catalyst electrode and the proton conductive membrane according to claim 13, wherein the organic proton conductive polymer is sulfonated polyetheretherketone or sulfonated polyethersulfone.   A fuel cell comprising the joined body of the catalyst electrode according to any one of claims 10 to 14 and a proton conductive membrane.

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