Abstract: The present invention relates to an expanded product comprising a thermoplastic fluroine type resin which does not have a cross-linking structure and has an expansion ratio of between 4-fold and 30-fold and a closed cell percentage of 40% or more. The expanded product contains at least one interface comprising layers having different cell densities and has a distribution index (Sc) and a coefficient of variation (Cv) of the maximum diameter of an open cell present at an optional cross section of each layer of 0<Sc.ltoreq.6 and 0<Cv.ltoreq.1, respectively, which are represented by the following equations:Sc=(L.sub.Max. -L.sub.Min.)/Lav. (1)Cv=SD/L.sub.av. (2)wherein L.sub.Max., L.sub.Min. and L.sub.av. represent maximum, minimum and average values of maximum diameters of open cells, respectively; and SD represents a standard deviation.

Abstract: There is disclosed a fiber of a fluorocarbon polymer having pendant ion exchange groups, the fiber having a tensile strength at break as high as at least 1.0 g/denier. The fiber can be produced by subjecting to hydrolysis or chemical modification treatment a filament of a fluorocarbon polymer having ion exchange precursor groups in melt-fabricatable form to convert the ion exchange precursor groups to ion exchange groups in melt-nonfabricatable form and subjecting the resultant heat-infusible filament to drawing.

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 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.

Abstract: An electrolytic cell having anode and cathode chambers separated by a cation exchange membrane comprising a fluorocarbon polymer containing pendant carboxylic acid or salt groups of the formula ##STR1## wherein R is a group containing perfluoroalkyl or perfluoroalkoxy having 1 to 5 carbon atoms and M is hydrogen, an alkali or alkaline earth metal or ammonium as a surface stratum on the cathode side of the membrane.

Abstract: Cation exchange membrane comprising a fluorocarbon polymer characterized by the presence of pendant carboxylic acid groups of the formula -- OCF.sub.2 COOH -- and derivatives thereof.