Abstract: To provide a polymer electrolyte membrane for polymer electrolyte fuel cells having high mechanical strength and excellent dimensional stability when it contains water even when it is made thin and the concentration of ionic groups is increased so as to reduce the electrical resistance, and a membrane/electrode assembly providing high output and having excellent durability.

Abstract: To obtain a nonwoven fabric which is excellent in the heat resistance and the chemical resistance, of which the fiber diameter is small, and which is excellent in the mechanical strength at a temperature at which it is used; and an electrolyte membrane which is excellent in the dimensional stability when it is swollen by water, and of which an increase in the resistance by a reinforcing material is suppressed. A nonwoven fabric 28 containing fibers 26 of an ethylene/tetrafluoroethylene copolymer having a storage elastic modulus E? at 25° C. of at least 8×108 Pa and a melt viscosity measured at 300° C. of higher than 60 Pa·s and at most 300 Pa·s, wherein the average fiber diameter of the fibers is from 0.01 to 3 ?m; and an electrolyte membrane reinforced by the nonwoven fabric 28.

Abstract: A process comprising: providing a substrate with a catalyst layer thereon; depositing a first ionomer overcoat layer over the catalyst layer, the first ionomer overcoat layer comprising an ionomer and a first solvent; drying the first ionomer overcoat layer to provide a first electrode ionomer overcoat layer; depositing a second ionomer overcoat layer over the first electrode ionomer overcoat layer, and wherein the second ionomer overcoat layer comprises an ionomer and a second solvent.

Abstract: To provide an electrolyte membrane having excellent dimensional stability even upon absorption of water, a high proton conductance and high power generation performance; and a process for producing the electrolyte membrane with a high productivity. An electrolyte membrane for polymer electrolyte fuel cells, which is made mainly of an ion exchange resin and reinforced with a nonwoven fabric made of fiber of a fluororesin wherein at least some of intersecting points of the fiber are fixed, and which has, as the outermost layer on one side or each side, a layer not reinforced, made of an ion exchange resin which may be the same as or different from the above ion exchange resin, wherein the fluororesin is an ethylene/tetrafluoroethylene copolymer having a melting point of at most 240° C., and the above fixing is fixing by fusion of the fiber.

Abstract: Provided is an electrolyte membrane containing: a reinforced inner layer; and an unreinforced outer layer on one or each side of the reinforced inner layer, wherein the reinforced inner layer includes an inner ion exchange resin reinforced with a non-woven fabric composed of a melt moldable fluororesin in the form of a continuous fiber, wherein a number of intersecting points of the continuous fiber are fused and/or bonded, and wherein the unreinforced outer layer includes an outer ion exchange resin, which may be the same as or different from the inner ion exchange resin. Also provided is a membrane electrode assembly for a polymer electrolyte fuel cell, wherein the membrane electrode assembly contains the above-mentioned polymer electrolyte membrane.

Abstract: In the production of a membrane/electrode assembly 10, a first catalyst layer 22 (a second catalyst layer 34) is formed by a process comprising steps (a) and (b). (a) A step of applying a coating fluid comprising a catalyst and an ion-exchange resin, on a substrate to form a coating fluid layer. (b) A step of disposing a reinforcing layer 24 (34) on the coating fluid layer formed in the step (a) and then, drying the coating fluid layer to form a first catalyst layer 22 (a second catalyst layer 34) The process provides a catalyst layer whereby defects such as cracks are scarcely formed in the catalyst layer, and the bond strength is high at the interface between the catalyst layer and a reinforcing layer and at the interface between the catalyst layer and a polymer electrolyte membrane.

Abstract: To provide a process whereby an ultrafine fiber of a fluorinated ion exchange resin can be produced easily at low cost, and a method whereby a catalyst layer having a high gas diffusion property can be produced easily at low cost.

Abstract: A polymer electrolyte membrane made of a polymer has a low electrical resistance, high heat resistance and is strong against repeats of swelling and shrinkage. Thus, a membrane/electrode assembly for polymer electrolyte fuel cells having high power generation performance and excellent in durability can be provided. For a polymer electrolyte membrane 15 or for a catalyst layer 11 constituting electrodes 13 and 14, a polymer comprising units (U1) and units (U2) is used: Q1, Q2: a perfluoroalkylene group which may have —O— or the like; Rf1, Rf2: a perfluoroalkyl group which may have —O—; X: an oxygen atom or the like; a: 0 or the like; Y, Z: a fluorine atom, or a monovalent perfluoroorganic group such as —CF3; S: 0 to 1; and t: 0 to 3.

Abstract: To provide a polymer electrolyte material for polymer electrolyte fuel cells, which is an electrolyte material having a high ion exchange capacity and a low resistance, and which has a higher softening temperature than a conventional electrolyte material.

Abstract: To obtain a nonwoven fabric which is excellent in the heat resistance and the chemical resistance, of which the fiber diameter is small, and which is excellent in the mechanical strength at a temperature at which it is used; and an electrolyte membrane which is excellent in the dimensional stability when it is swollen by water, and of which an increase in the resistance by a reinforcing material is suppressed. A nonwoven fabric 28 containing fibers 26 of an ethylene/tetrafluoroethylene copolymer having a storage elastic modulus E? at 25° C. of at least 8×108 Pa and a melt viscosity measured at 300° C. of higher than 60 Pa·s and at most 300 Pa·s, wherein the average fiber diameter of the fibers is from 0.01 to 3 ?m; and an electrolyte membrane reinforced by the nonwoven fabric 28.

Abstract: A polymer electrolyte membrane made of a polymer having a low electrical resistance, high heat resistance and is strong against repeats of swelling and shrinkage. Thus, a membrane/electrode assembly for polymer electrolyte fuel cells having high power generation performance and excellent in durability can be provided.

Abstract: It is an object of the present invention to provide a nonwoven fabric which is excellent in the heat resistance and the chemical resistance, of which the fiber diameter is small, which is excellent in the strength and of which the maximum pore diameter is small. A nonwoven fabric made of an ethylene/tetrafluoroethylene copolymer, characterized in that the nonwoven fabric is mutually fused continuous fibers of an ethylene/tetrafluoroethylene copolymer which has a melt viscosity of from higher than 100 to 1,500 Pa·s at 240° C.

Abstract: To provide a membrane/electrode assembly for polymer electrolyte fuel cells, a polymer electrolyte fuel cell and processes for their production, which make it possible to stably exhibit a high power generation performance in various environments. A membrane/electrode assembly for polymer electrolyte fuel cells, which comprises a first electrode having a first catalyst layer and a first gas diffusion layer, a second electrode having a second catalyst layer and a second gas diffusion layer, and a polymer electrolyte membrane disposed between the first electrode and the second electrode, wherein the 90° peel strength at least one of the interface between the first electrode and the polymer electrolyte membrane and the interface between the second electrode and the polymer electrolyte membrane is at least 0.03 N/cm.

Abstract: An electrolyte material for polymer electrolyte fuel cells, which is made of a polymer containing repeating units based on a fluoromonomer having a radical polymerization reactivity, wherein the repeating units contain a 5-membered ring (which may contain 1 or 2 oxygen atoms), of which at least one carbon atom is contained in the main chain of the polymer, and an ionic group such as a sulfonic acid group which is bonded to the 5-membered ring directly or via a perfluoroalkylene group having a linear or branched structure; and the polymer has a softening temperature of at least 120° C.

Abstract: To provide a process whereby an ultrafine fiber of a fluorinated ion exchange resin can be produced easily at low cost, and a method whereby a catalyst layer having a high gas diffusion property can be produced easily at low cost.

Abstract: To provide a process for forming a catalyst layer whereby defects such as cracks are scarcely formed in the catalyst layer, and the bond strength is high at the interface between the catalyst layer and a reinforcing layer and at the interface between the catalyst layer and a polymer electrolyte membrane; and a process for producing a membrane/electrode assembly for a polymer electrolyte fuel cell, which is capable of exhibiting high power generation performance even under a low humidity condition and has sufficient mechanical strength and dimensional stability and which has excellent durability even in an environment where humidification and drying, etc. are repeated. In the production of a membrane/electrode assembly 10, a first catalyst layer 22 (a second catalyst layer 34) is formed by a process comprising steps (a) and (b). (a) A step of applying a coating fluid comprising a catalyst and an ion-exchange resin, on a substrate to form a coating fluid layer.

Abstract: To provide a polymer electrolyte membrane for polymer electrolyte fuel cells having high mechanical strength and excellent dimensional stability when it contains water even when it is made thin and the concentration of ionic groups is increased so as to reduce the electrical resistance, and a membrane/electrode assembly providing high output and having excellent durability. A polymer electrolyte membrane 15, which comprises a fluorinated proton conductive polymer (i) having a proton conductivity of at least 0.06 S/cm in an atmosphere at a temperature of 80° C. under a relative humidity of 50%, and (ii) having repeating units based on a vinyl ether type monomer with a mass (equivalent weight) of at most 400 per 1 mol of ionic groups and repeating units based on a perfluoromonomer (except for the above vinyl ether type monomer) and a fluorinated reinforcing material; and a membrane/electrode assembly 10 comprising the polymer electrolyte membrane 15 interposed between an anode 13 and a cathode 14.

Abstract: To provide a membrane/electrode assembly for polymer electrolyte fuel cells, a polymer electrolyte fuel cell and processes for their production, which make it possible to stably exhibit a high power generation performance in various environments. A membrane/electrode assembly for polymer electrolyte fuel cells, which comprises a first electrode having a first catalyst layer and a first gas diffusion layer, a second electrode having a second catalyst layer and a second gas diffusion layer, and a polymer electrolyte membrane disposed between the first electrode and the second electrode, wherein the 90° peel strength at least one of the interface between the first electrode and the polymer electrolyte membrane and the interface between the second electrode and the polymer electrolyte membrane is at least 0.03 N/cm.

Abstract: To provide an electrolyte membrane having excellent dimensional stability even upon absorption of water, a high proton conductance and high power generation performance; and a process for producing the electrolyte membrane with a high productivity. An electrolyte membrane for polymer electrolyte fuel cells, which is made mainly of an ion exchange resin and reinforced with a nonwoven fabric made of fiber of a fluororesin wherein at least some of intersecting points of the fiber are fixed, and which has, as the outermost layer on one side or each side, a layer not reinforced, made of an ion exchange resin which may be the same as or different from the above ion exchange resin, wherein the fluororesin is an ethylene/tetrafluoroethylene copolymer having a melting point of at most 240° C., and the above fixing is fixing by fusion of the fiber.

Abstract: It is an object of the present invention to provide a nonwoven fabric which is excellent in the heat resistance and the chemical resistance, of which the fiber diameter is small, which is excellent in the strength and of which the maximum pore diameter is small. A nonwoven fabric made of an ethylene/tetrafluoroethylene copolymer, characterized in that the nonwoven fabric is mutually fused continuous fibers of an ethylene/tetrafluoroethylene copolymer which has a melt viscosity of from higher than 100 to 1,500 Pa˜s at 240° C.