Asahi Kasei Kogyo Kabushiki Kaisha

Asahi Kasei Kabushiki Kaisha

Sakae Tsushima

Itaru Watanabe

Hirotsugu Miyauchi

Yasumichi Yamakoshi

Mitsunobu Fukumoto

Kyoji Kimoto

Toshioki Hane

Teruyuki Misumi

Hiroshi Sagami

Maomi Seko

Tadashi Inoue

Naomi Seko

Masahiko Murakoshi

Isamu Wataya

An ion exchange membrane reinforced by a woven reinforcing fabric is provided in which the difference between the thickness of the membrane at the crossover points where the warp and weft strands of the fabric cross each other and that at the window portions defined by the crossed warp and weft strands is not greater than 35 .mu.m. This membrane may be produced for example, by heating an assembly comprising at least two fluorinated polymer films each having pendant sulfonyl groups and/or carboxyl groups in a melt-fabricable form, and a woven reinforcing fabric sandwiched between the polymer films, and a support sheet laminated to the outermost polymer film, while applying a negative pressure to one side of the assembly that is remote from the support film, followed by converting the sulfonyl and/or carboxyl groups of the polymer films to sulfonate and/or carboxylate groups. This reinforced ion exchange membrane has flat film surfaces, thereby eliminating the danger of gas bubbles during chloralkali electrolysis which enables the cell voltage to be low, so that electric power consumption can be reduced.

Reinforced ion exchange membrane and a process for producing the same

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

A cation exchange membrane reinforced by one sheet of a woven fabric made of folded glass-fiber-filament yarns subjected to a bulky treatment is found to be improved in dimensional stability, water permeability (water leakage) and durability with much improved adhesion of the reinforcement to the resin constituting the cation exchange membrane.

Cation exchange membrane

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

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. The fluorocarbon polymer may also contain sulfonic acid groups of the formula ##STR2##

Electrolysis of aqueous alkali metal halide solution

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.

Cation exchange membrane preparation and use thereof

A leno-woven fabric of a specific construction is found to effectively reinforce an ion-exchange membrane at a scarce density of reinforcing yarns to improve electrochemical property of the reinforced ion-exchange membrane.

Reinforced ion-exchange membrane

An improved cation-exchange membrane, onto which have been adhered fine particles of a crosslinked high molecular weight substance having anion-exchange groups and which can maintain a specific permselectivity for monovalent cations over a long period of time, is prepared with ease by treating a cation-exchange membrane with a suspension of fine particles of the said crosslinked high molecular weight substance.

Process for preparing improved cation-exchange membranes

A specific class of anionic ion-exchange membranes, comprising a crosslinked vinyl imidazole polymer or copolymer film, is suitable for use in electrodialysis process by use of ion-exchange membranes of an aqueous solution containing organic contaminating electrolyte such as humic acid without organic contamination.

Growing community of inventors

Yokohama, Japan

Sakae Tsushima