Abstract: A cation exchange membrane of a fluorocarbon polymer containing pendant carboxylic acid and/or carboxylate groups, preferably having, at a predetermined ratio, pendant carboxylic acid and/or carboxylate groups and pendant sulfonic acid and/or sulfonate groups uniformly distributed therein, is produced by contacting with a reducing agent a fluorocarbon polymer containing pendant groups of the formula:--O(CF.sub.2).sub.m SO.sub.2 Xwherein X is a fluorine atom, a chlorine atom, a hydrogen atom, M or OM in which M represents a hydrogen atom, a metal atom or an ammonium group, and m is as defined above, and transforming the resultant to a film. An excellent double-layer type composite cation exchange membrane can be produced by laminating the above-mentioned membrane having pendant carboxylic acid and/or carboxylate groups and pendant sulfonic acid and/or sulfonate groups on a membrane of a fluorocarbon polymer containing pendant sulfonic acid and/or sulfonate groups.

Abstract: A novel fluorinated copolymer is prepared by copolymerization of a fluorinated olefin with a novel sulfur containing fluorinated vinylether of the formula: ##STR1## wherein k is 0 or 1 and l is an integer of 3 to 5, which is prepared from starting materials which are also novel. Said copolymer is useful for preparation of a fluorinated cation exchange membrane having carboxylic acid groups and/or sulfonic acid groups which can be used advantageously in electrolysis of an aqueous alkali metal halide solution with improved electrolysis performance.

Abstract: A novel fluorinated cation exchange membrane containing carboxylic acid groups and sulfonic acid groups, both in the form of a specific pendant structure, the carboxylic acid groups being at least 20% on one surface of the membrane and gradually decreasing toward the innerside of the membrane, which membrane is useful in electrolysis of an aqueous alkali metal halide solution with advantageously stable performance for a long term under more severe operational conditions than those conventionally used. The membrane can be prepared from a novel copolymer of a fluorinated olefin with a novel sulfur containing fluorinated vinylether of the formula: ##STR1## wherein k is 0 or 1, l is an integer of 3 to 5, Z is --S-- or --SO.sub.2 -- and R is C.sub.1 -C.sub.10 alkyl, an aryl, C.sub.1 -C.sub.10 perfluoroalkyl.

Abstract: A novel fluorinated cation exchange membrane containing carboxylic acid groups and sulfonic acid groups, both in the form of a specific pendant structure, the carboxylic acid groups being at least 20% on one surface of the membrane and gradually decreasing toward the innerside of the membrane, which membrane is useful in electrolysis of an aqueous alkali metal halide solution with advantageously stable performance for a long term under more severe operational conditions than those conventionally used. The membrane can be prepared from a novel copolymer of a fluorinated olefin with a novel sulfur containing fluorinated vinylether of the formula: ##STR1## wherein k is 0 or 1, l is an integer of 3 to 5, Z is --S-- or --SO.sub.2 -- and R is C.sub.1 -C.sub.10 alkyl, an aryl, Cl or C.sub.1 -C.sub.10 perfluoroalkyl. Acyl fluorides, which are the precursors of the fluorinated olefin ethers, are also disclosed.

Abstract: A novel fluorinated copolymer is prepared by copolymerization of a fluorinated olefin with a novel sulfur containing fluorinated vinylether of the formula: ##STR1## wherein k is 0 or 1 and l is an integer of 3 to 5, which is prepared from starting materials which are also novel. Said copolymer is useful for preparation of a fluorinated cation exchange membrane having carboxylic acid groups and/or sulfonic acid groups which can be used advantageously in electrolysis of an aqueous alkali metal halide solution with improved electrolysis performance.

Abstract: A novel fluorinated copolymer is prepared by copolymerization of a fluorinated olefin with a novel sulfur containing fluorinated vinylether of the formula: ##STR1## wherein k is 0 or 1 and l is an integer of 3 to 5, which is prepared from starting materials, which are also novel. Said copolymer is useful for preparation of a fluorinated cation exchange membrane having carboxylic acid groups and/or sulfonic acid groups which can be used advantageously in electrolysis of an aqueous alkali metal halide solution with improved electrolysis performance.

Abstract: A novel fluorinated cation exchange membrane containing carboxylic acid groups and sulfonic acid groups, both in the form of a specific pendant structure, the carboxylic acid groups being at least 20% on one surface of the membrane and gradually decreasing toward the innerside of the membrane, which membrane is useful in electrolysis of an aqueous alkali metal halide solution with advantageously stable performance for a long term under more severe operational conditions than those conventionally used. The membrane can be prepared from a novel copolymer of a fluorinated olefin with a novel sulfur containing fluorinated vinylether of the formula: ##STR1## wherein k is 0 or 1, l is an integer of 3 to 5, Z is --S-- or --SO.sub.2 -- and R is C.sub.1 -C.sub.10 alkyl, an aryl, Cl or C.sub.1 -C.sub.10 perfluoroalkyl.

Abstract: A novel process is disclosed for preparing (.omega.-fluorosulfonyl)haloaliphatic carboxylic acid fluorides by electrolytic fluorination, simply and efficiently.

Abstract: A novel process is disclosed for preparing (.omega.-fluorosulfonyl)haloaliphatic carboxylic acid fluorides by electrolytic fluorination, simply and efficiently.

Abstract: A fluorinated cation exchange membrane characterized by the gradual decrease in proportion of the density of carboxylic acid and/or carboxylate groups relative to the total density of carboxylic acid and/or carboxylate groups and sulfonic acid and/or sulfonate groups from one surface of the membrane to the other surface or an internal plane therewithin. The cation exchange membrane of the present invention can be prepared by treating one surface of a membrane comprising a fluorocarbon polymer containing pendant groups of the formula:--OCF.sub.2 CF.sub.2 SO.sub.2 Xwherein each X independently is fluorine, chlorine, bromine, hydrogen, ammonium, a quaternary ammonium or a metal atom, with a treating agent having a reducing activity in the presence of a reaction controlling agent selected from carboxylic acids, sulfonic acids, alcohols, nitriles and ethers.

Abstract: A fluorinated cation exchange membrane characterized by the gradual decrease in proportion of the density of carboxylic acid and/or carboxylate groups relative to the total density of carboxylic acid and/or carboxylate groups and sulfonic acid and/or sulfonate groups from one surface of the membrane to the other surface or an internal plane therewithin. The cation exchange membrane of the present invention can be prepared by treating one surface of a membrane comprising a fluorocarbon polymer containing pendant groups of the formula:--OCF.sub.2 CF.sub.2 SO.sub.2 Xwherein each X independently is fluorine, chlorine, bromine, hydrogen, ammonium, a quaternary ammonium or a metal atom,with a treating agent having a reducing activity in the presence of a reaction controlling agent selected from carboxylic acids, sulfonic acids, alcohols, nitriles and ethers.

Abstract: A novel fluorinated copolymer is prepared by copolymerization of a fluorinated olefin with a novel sulfur containing fluorinated vinyl ether of the formula: ##STR1## wherein k is 0 or 1 and l is an integer of 3 to 5, which is prepared from starting materials which are also novel. Said copolymer is useful for preparation of a fluorinated cation exchange membrane having carboxylic acid groups and/or sulfonic acid groups which can be used advantageously in electrolysis of an aqueous alkali metal halide solution with improved electrolysis performance.

Abstract: A novel fluorinated cation exchange membrane containing carboxylic acid groups and sulfonic acid groups, both in the form of a specific pendant structure, the carboxylic acid groups being at least 20% on one surface of the membrane and gradually decreasing toward the innerside of the membrane, which membrane is useful in electrolysis of an aqueous alkali metal halide solution with advantageously stable performance for a long term under more severe operational conditions than those conventionally used. The membrane can be prepared from a novel copolymer of a fluorinated olefin with a novel sulfur containing fluorinated vinylether of the formula: ##STR1## wherein k is 0 or 1, l is an integer of 3 to 5, Z is --S-- or --SO.sub.2 -- and R is C.sub.1 -C.sub.10 alkyl, an aryl, Cl or C.sub.1 -C.sub.10 perfluoroalkyl.