Asahi Kasei Kogyo Kabushiki Kaisha

Yoshinori Masuda

Mitsuo Yoshida

Akio Kashiwada

Hiroshi Kobayashi

Maomi Seko

Kyoji Kimoto

Hirotsugu Miyauchi

Hiroshi Saito

Yasumichi Yamakoshi

A high molecular weight fluoroelastomer is provided comprising 65 to 100 wt % of vinylidene fluoride units and hexafluoropropylene units and 35 to 0 wt % of tetrafluoroethylene units exhibiting low compression set and high elongation properties and showing good processability.

High molecular weight fluoroelastomer

In cation exchange membranes having a multi-layer structure consisting of two or three layers or more each having different equivalent weight and/or different kind of ion exchange group used for the electrolysis of alkali metal chloride according to an ion exchange membrane process, a homogeneous cation exchange membrane which comprises that at least one outer layer having a lower water content of both outer layers of said membrane has a roughened surface so that the amount of hydrogen gas bubbles generated from the cathode and attached to the membrane surface is the least whereby the electrolysis voltage is the lowest and the process for the production thereof.

Homogeneous cation exchange membrane having a multi-layer structure

There is disclosed a fluorinated cation exchange membrane having a multi-layered structure, of which one layer contains sulfonic acid groups as ion-exchange groups and the other layer contains carboxylic acid groups as principal ion-exchange groups. The membrane is treated with an acid, followed by heat treatment at an elevated temperature in an aqueous atmosphere or aqueous solution whereby improved electrolytic performance such as electrolysis voltage and current efficiency when used in electrolysis of sodium chloride for production of caustic soda is obtained.

Fluorinated cation exchange membrane

A homogeneous cation exchange membrane having at least one roughened surface, which is assembled in an electrolytic cell with the roughened surface facing toward the cathode side of the cell, is employed in the electrolysis of an alkali chloride in an electrolytic cell divided by a cation exchange membrane into an anode compartment and a cathode compartment to produce an alkali hydroxide. The electrolysis voltage can be considerably reduced at a high current efficiency to provide a great economical advantage.

Process for electrolysis of alkali chloride

An aqueous alkali metal halide solution is electrolyzed in an electrolytic cell using a cation exchange membrane which is a fluorocarbon polymer containing sulfonic acid groups and at least one cation exchange group which is less acidic than the sulfonic acid group with higher proportion of the latter in surface stratum on the cathode side of the membrane than in the entire membrane, while controling proton concentration in the anolyte at not higher than critical proton concentration at which no substantial amount of protons in the anolyte penetrate into the membrane.

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Nobeoka, Japan

Yoshinori Masuda