Asahi Kasei Kogyo Kabushiki Kaisha

Asahi Kasei Kabushiki Kaisha

Hiroshi Sagami

Sakae Tsushima

Hirotsugu Miyauchi

Hisashi Wakamatsu

Keizo Hosoi

Isao Imai

A cation exchange membrane having having durability, which is adapted for use in electrolysis or an alkali metal chloride, which comprises a quadrilateral base membrane and, disposed on at least one marginal area of one surface of the base membrane, a diffusion coating having a capability for an alkali metal hydroxide to diffuse therethrough at a diffusion velocity greater than that at which the alkali metal hydroxide diffuses through a fluorocarbon polymer layer constituting the base membrane when the base membrane is composed of one fluorocarbon polymer layer or through one outermost layer of the base membrane which layer has thereon the diffusion coating and has a water sorption smaller than that of the opposite outermost layer of the base membrane, when the base membrane is composed of a plurality of fluorocarbon polymer layers. The cation exchange membrane is free, for a prolonged period of time, from the local lowering of the mechanical strength of the membrane as caused by the precipitation of an alkali metal chloride within and the formation of oxygen in nascent state within the base membrane during the electrolysis of an alkali metal chloride.

Cation exchange membrane having high durability with diffusion coating

A fluorinated polymer having pendant cation exchange groups selected from sulfonic acid, carboxylic acid or sulfonamide groups, or their salts, is modified with a sulfonium compound and/or a phosphonium compound for substitution of the counter-ions of the cation exchange groups with sulfonium ions and/or phosphonium ions. The polymers treated in this manner are improved in their melt-flow characteristic to make fusion bonding between these polymers possible. The process is particularly suitable for repairing damaged cation exchange membranes for use in chlor-alkali electrolytic cells to advantageously elongate the life of the membranes.

Process for fusion bonding of fluorocarbon type polymers which comprises

In performing melt processing of a fluorinated polymer which contains such pendant functional groups as sulfonic acid, carboxylic acid, sulfonamide and salts thereof, an aqueous medium is allowed to be present in the polymer to improve its melt-flow characteristic. Excellent heat sealing can be effected without degradation of the polymer. This method is particularly suitable for repairing the damaged ion-exchange membranes of fluorinated polymers used in the electrolysis of sodium chloride to enable elongation of their life to a great economical advantage.

Melt processing of fluorinated polymers

Addition polymerizable polymeric compounds produced by esterification reaction or addition reaction of a copolymer having pendent carboxyl groups and about 0.03 to 1.0 equivalent, based upon the carboxyl groups of said copolymer, of an ethylenically unsaturated compound having one oxirane ring, said copolymer being obtained by copolymerizing (1) about 10 to 95 percent by weight of at least one member selected from the group consisting of styrene and the methyl-substituted styrene derivatives (2) about 5 to 70 percent by weight of at least one ethylenically unsaturated mono- or di-carboxylic acid, its anhydride or its monoalkyl of 1 to 4 carbon atoms ester, (3) up to about 30 percent weight of at least one member selected from the group consisting of acrylonitrile and methacrylonitrile, (4) up to about 85 percent by weight of at least one compound of the formula ##EQU1## wherein R.sup.1 represents a hydrogen atom or methyl group; and R.sup.2 represents an alkyl group having 1 to 12 carbon atoms, and (5) up to about 50 percent by weight, based upon the total weight of said compound (3) and/or (4), of at least one vinyl ester of a saturated aliphatic mono-carboxylic acid having 2 to 10 carbon atoms, and photopolymerizable compositions comprising (A) about 100 parts by weight of the above-described addition polymerizable polymeric compound, (B) about 5 to 70 parts by weight of at least one ethylenically unsaturated compound and (C) about 0.0001 to 10 parts by weight of a photopolymerization initiator. The compositions give photopolymerizable elements which are useful for various pattern or image yielding purposes and especially useful in making reliefs, particularly lithographic plates having an excellent printing durability.

Growing community of inventors

Yokohama, Japan

Hiroshi Sagami