Abstract: To provide an electrolyte material which has a high proton conductivity and which is excellent in hot water resistance. An electrolyte material which is formed of a polymer H having units represented by the formula u1 and units based on tetrafluoroethylene, wherein the polymer H has an equivalent weight EW of from 400 to 550 g/eq, and the mass reduction ratio when immersed in hot water at 120° C. for 24 hours is at most 15 mass %: wherein Q11 is a perfluoroalkylene group which may have an etheric oxygen atom, Q12 is a single bond or a perfluoroalkylene group which may have an etheric oxygen atom, Y1 is a fluorine atom or the like, s is 0 or 1, Rf1 is a perfluoroalkyl group which may have an etheric oxygen atom, X1 is an oxygen atom or the like, a is 0 when X1 is an oxygen atom, and Z+ is H+ or the like.

Abstract: The present invention provides a strong polymer electrolyte membrane which can provide a water electrolyzer operable at low electrolysis voltage. The polymer electrolyte membrane of the present invention comprises a fluorinated polymer and a woven fabric, wherein the weight of the woven fabric is from 20 to 95 g/m2, and the warp and weft of the woven fabric independently have a denier of from 30 to 100.

Abstract: To provide a liquid composition with which a catalyst layer and a polymer electrolyte membrane will hardly be broken at the time of their formation and a method for producing the liquid composition; and a method for producing a membrane/electrode assembly by which a catalyst layer and a polymer electrolyte membrane will hardly be broken at the time of their formation. A liquid composition comprising a polymer having ion exchange groups, water and an organic solvent, wherein the average secondary particle size of the polymer having ion exchange groups is from 100 to 3,000 nm, and the primary particle size parameter represented by the product of the average primary particle size (nm) and the ion exchange capacity (meq/g dry resin) of the polymer having ion exchange groups, is from 12 to 20.

Abstract: The present invention provides a catalyst layer, a catalyst layer ink and a membrane-electrode assembly which enable provision of fuel cells with high power efficiency. The catalyst layer of the present invention comprises a carbon alloy catalyst and an ion exchange polymer which comprises at least one species of units having a cyclic ether structure selected from the group consisting of units represented by the formula (u11), units represented by the formula (u12), units represented by the formula (u21), units represented by the formula (u22) and units represented by the formula (u24).

Abstract: A method for producing a liquid composition containing a fluoropolymer having sulfonic acid groups, trivalent cerium ions and water, by (1) irradiating a solution containing at least one cerium compound selected from cerium carbonate, cerium hydroxide and cerium oxide, the fluoropolymer and the water, with light at least partially in a wavelength region from 300 to 400 nm so that the ultraviolet irradiance on the surface of the solution is at least 0.1 mW/cm2 or (2) adding a reducing agent to a solution containing at least one cerium compound selected from cerium carbonate, cerium hydroxide and cerium oxide, the fluoropolymer and the water.

Abstract: To provide an electrolyte material having a low hydrogen gas permeability and excellent hot water resistance. An electrolyte material comprising a polymer having units represented by the following formula u1 and units based on chlorotrifluoroethylene at the specific proportion: wherein Q11 is a perfluoroalkylene group which may have an etheric oxygen atom, Q12 is a single bond or a perfluoroalkylene group which may have an etheric oxygen atom, Y1 is a fluorine atom or the like, s is 0 or 1, Rf1 is a perfluoroalkyl group which may have an etheric oxygen atom, X1 is an oxygen atom or the like, a is 0 when X1 is an oxygen, and Z+ is H+ or the like.

Abstract: To provide a catalyst layer, a catalyst layer forming liquid, and a membrane electrode assembly, capable of forming a fuel cell excellent in power generation efficiency.

Abstract: To provide a method for producing a fluorinated polymer, in which it is possible to efficiently and easily control the molecular weight to be proper when polymerizing a perfluoromonomer having a dioxolane ring containing a polymerizable double bond in the ring skeleton, and in which the obtainable fluorinated polymer is less susceptible to a decrease in molecular weight even when contacted with a base.

Abstract: To provide a membrane/electrode assembly excellent in the power generation characteristics in a wide temperature range and a wide humidity range; an electrolyte material suitable for a catalyst layer of the membrane/electrode assembly; and a liquid composition suitable for forming a catalyst layer of the membrane/electrode assembly. To use an electrolyte material which is formed of a polymer (H) obtained by converting precursor groups in a polymer (F) having structural units (A) based on a perfluoromonomer having a precursor group represented by the formula (g1), structural units (B) represented by the formula (u2), and structural units (C) based on tetrafluoroethylene, wherein the proportion of the structural units (A) is from 8 to 19 mol %, the proportion of the structural units (B) is from 65 to 80 mol %, and the proportion of the structural units (C) is from 1 to 27 mol %, to ion exchange groups.

Abstract: The present invention provides a strong polymer electrolyte membrane which can provide a water electrolyzer operable at low electrolysis voltage. The polymer electrolyte membrane of the present invention comprises a fluorinated polymer and a woven fabric, wherein the weight of the woven fabric is from 20 to 95 g/m2, and the warp and weft of the woven fabric independently have a denier of from 30 to 100.

Abstract: To provide methods for producing a liquid composition, a coating liquid for a catalyst layer and a membrane electrode assembly, capable of making cracking less likely to occur at the time of forming a solid polymer electrolyte membrane or a catalyst layer. A copolymer having a structural unit represented by —[CF2—CF{(OCF2CFX)mOp(CF2)nSO3H}]— (wherein X: F or CF3, m: 1 to 3, p: 0 or 1, and n: an integer of 1 to 12) and a structural unit derived from tetrafluoroethylene, is dispersed in a medium containing water and a hydrocarbon-type alcohol (but not including a fluorinated solvent) to prepare a dispersion wherein the concentration of the copolymer is from 13 to 26 mass %, and the dispersion and a fluorinated solvent are mixed so that the sum of the concentration of the copolymer and the concentration of the fluorinated solvent becomes to be from 17 to 35 mass %, to prepare a liquid composition.

Abstract: To provide an electrolyte material having a low hydrogen gas permeability and excellent hot water resistance. An electrolyte material comprising a polymer having units represented by the following formula u1 and units based on chlorotrifluoroethylene at the specific proportion: wherein Q11 is a perfluoroalkylene group which may have an etheric oxygen atom, Q12 is a single bond or a perfluoroalkylene group which may have an etheric oxygen atom, Y1 is a fluorine atom or the like, s is 0 or 1, Rf1 is a perfluoroalkyl group which may have an etheric oxygen atom, X1 is an oxygen atom or the like, a is 0 when X1 is an oxygen, and Z+ is H+ or the like.

Abstract: To provide a liquid composition capable of forming a catalyst layer that is excellent in resistance to hydrogen peroxide and peroxide radicals, can further increase the output voltage of a membrane/electrode assembly, and can maintain a high output voltage for a long period of time; a method for its production; and a membrane electrode assembly for a polymer electrolyte fuel cell using said liquid composition. Provided is a liquid composition to be used for forming a catalyst layer constituting an electrode of a membrane electrode assembly for a polymer electrolyte fuel cell, wherein the liquid composition comprises a liquid medium, a fluoropolymer (H) having sulfonic acid groups and ring structures, and trivalent or tetravalent cerium ions, and the content of the trivalent or tetravalent cerium ions is from 1.6 to 23.3 mol % to the sulfonic acid groups (100 mol %).

Abstract: To provide an electrolyte material which has a high proton conductivity and which is excellent in hot water resistance. An electrolyte material which is formed of a polymer H having units represented by the formula u1 and units based on tetrafluoroethylene, wherein the polymer H has an equivalent weight EW of from 400 to 550 g/eq, and the mass reduction ratio when immersed in hot water at 120° C. for 24 hours is at most 15 mass %: wherein Q11 is a perfluoroalkylene group which may have an etheric oxygen atom, Q12 is a single bond or a perfluoroalkylene group which may have an etheric oxygen atom, Y1 is a fluorine atom or the like, s is 0 or 1, Rf1 is a perfluoroalkyl group which may have an etheric oxygen atom, X1 is an oxygen atom or the like, a is 0 when X1 is an oxygen atom, and Z+ is H+ or the like.

Abstract: To provide a process for forming a polymer electrolyte membrane having good durability and few wrinkles, a polymer electrolyte membrane capable of forming a catalyst layer, or a catalyst layer; a process for producing a fluorinated ion exchange resin fluid, or a paste for forming a catalyst layer, which can be used for such a forming process; and a process for producing a membrane/electrode assembly for a polymer electrolyte fuel cell having good durability and power generation properties. A fluorinated ion exchange resin fluid obtained by subjecting a powder or pellets of a fluorinated ion exchange resin having cation exchange groups to hydrogen peroxide treatment, followed by mixing with a solvent, is used.

Abstract: To provide a method for producing a liquid composition or a coating liquid for forming a catalyst layer, which can make cracking less likely to occur at the time of forming a solid polymer electrolyte membrane or a catalyst layer; and a method for producing a membrane electrode assembly, which can make cracking less likely to occur at the time of forming the catalyst layer or the solid polymer electrolyte membrane.

Abstract: To provide a liquid composition with which a catalyst layer and a polymer electrolyte membrane will hardly be broken at the time of their formation and a method for producing the liquid composition; and a method for producing a membrane/electrode assembly by which a catalyst layer and a polymer electrolyte membrane will hardly be broken at the time of their formation. A liquid composition comprising a polymer having ion exchange groups, water and an organic solvent, wherein the average secondary particle size of the polymer having ion exchange groups is from 100 to 3,000 nm, and the primary particle size parameter represented by the product of the average primary particle size (nm) and the ion exchange capacity (meq/g dry resin) of the polymer having ion exchange groups, is from 12 to 20.

Abstract: To provide methods for producing a liquid composition, a coating liquid for a catalyst layer and a membrane electrode assembly, capable of making cracking less likely to occur at the time of forming a solid polymer electrolyte membrane or a catalyst layer. A copolymer having a structural unit represented by —[CF2—CF{(OCF2CFX)mOp(CF2)nSO3H}]— (wherein X: F or CF3, m: 1 to 3, p: 0 or 1, and n: an integer of 1 to 12) and a structural unit derived from tetrafluoroethylene, is dispersed in a medium containing water and a hydrocarbon-type alcohol (but not including a fluorinated solvent) to prepare a dispersion wherein the concentration of the copolymer is from 13 to 26 mass %, and the dispersion and a fluorinated solvent are mixed so that the sum of the concentration of the copolymer and the concentration of the fluorinated solvent becomes to be from 17 to 35 mass %, to prepare a liquid composition.

Abstract: To provide a method for producing a liquid composition or a coating liquid for forming a catalyst layer, which can make cracking less likely to occur at the time of forming a solid polymer electrolyte membrane or a catalyst layer; and a method for producing a membrane electrode assembly, which can make cracking less likely to occur at the time of forming the catalyst layer or the solid polymer electrolyte membrane.

Abstract: Provided are a method for producing a liquid composition which is capable of eliminating clouding of a liquid with cerium (IV) hydroxide particles in a relatively short time, and methods for producing a polymer electrolyte membrane, a catalyst layer and a membrane/electrode assembly, each having excellent durability, in a relatively short time. A method for producing a liquid composition containing a fluoropolymer having sulfonic acid groups, trivalent cerium ions and water, which comprises (1) irradiating a solution containing at least one cerium compound selected from the group consisting of cerium carbonate, cerium hydroxide and cerium oxide, the fluoropolymer and the water, with light at least partially in a wavelength region from 300 to 400 nm so that the ultraviolet irradiance on the surface of the solution is at least 0.