Asahi Kasei Kogyo Kabushiki Kaisha

Tatsuo Hiyoshi

Akio Kashiwada

Makoto Miyazaki

A method for the electrolysis of an alkali metal chloride in an electrolytic cell is disclosed, in which use is made of a cation exchange membrane comprising a carboxylate-containing fluorocarbon polymer layer disposed on a cathode compartment side and provided on its surface with an inorganic coating, and a sulfonate and/or carboxylate-containing fluorocarbon polymer layer disposed on an anode compartment side and having a water content of from 3 to 10% by weight. By this method, an alkali metal hydroxide, e.g., sodium hydroxide, can be directly produced in a concentration as high as 45-55 % by weight from a saline solution having an alkali metal chloride concentration as low as from 3.0 to 3.5N with reduced energy consumption, stably for a prolonged period of time.

Method for the electrolysis of an alkali metal chloride using a cation

A highly stable cation exhange membrane for use in the electrolysis of an alkali metal chloride is disclosed, which comprises a reinforced base membrane comprised of at least one layer of a fluorocarbon polymer and a reinforcing woven fabric encapsulated therein and a coating disposed on at least one surface of the reinforced base membrane, the coating comprising particles of at least one inorganic material selected from the group consisting of oxides, nitrides and carbides of elements belonging to group IV of the periodic table, which particles have an average primary particle diameter as small as from 0.01 to 0.2 .mu.m, and a binder polymer. In the cation exchange membrane, the coating containing particles of an inorganic material, uniformly and strongly adheres to the surface of the reinforced base membrane, so that the inorganic material can remain in the coating for a prolonged period of time. Accordingly, by the use of the cation exchange membrane, the electrolysis of an alkali metal chloride can be stably performed at an advantageously low cell voltage for a prolonged period of time.

Cation exchange membrane having high stability

A novel process is disclosed in which a membrane of a fluorinated resin containing a pendant precursor ion exchange group represented by the formula:

Process for preparing an ion exchange membrane

A novel process is provided in which a membrane of a fluorinated resin having pendant ion exchange precursor groups represented by at least one formula selected from the group consisting of:

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Yokohama, Japan

Tatsuo Hiyoshi