Toyo Soda Manufacturing Co., Ltd.

Shunichi Asami

Toru Seita

Akihiko Shimizu

Kenji Takahashi

Characteristics of a cation exchange membrane used for an electrolysis of an alkali metal chloride are recovered by immersing the perfluorocarbon type cation exchange membrane in an organic solvent having a water miscibility and a boiling point of higher than 120.degree. C. in 760 mmHg; holding the immersed membrane between a pair of smooth plates and heating at 40.degree. C. to 180.degree. C.; treating the heat-treated membrane in hydrochloric acid and then, immersing it in an aqueous solution of sodium hydroxide and the organic solvent is preferably ethyleneglycol, propyleneglycol, isopropyleneglycol butanediol, pentanediol, hexanediol, glycerin or polyethyleneglycol.

Method of recovering characteristics of deteriorated cation exchange

A cation-exchange membrane is prepared by swelling a fluorinated polymer membrane having cation-exchangeable groups with an organic solvent and then removing the solvent from the swollen membrane and immersing a monomer with or without a crosslinking agent and a polymerization initiator into it and polymerizing the monomer. The membrane is preferably swollen with a water miscible organic solvent and then, the solvent is removed from the membrane.

Process for preparing cation-exchange membrane

A cation exchange membrane is produced by impregnating a diene derivative having carboxylic acid group and/or carboxylic acid convertible group into a cation exchange membrane of a fluorinated polymer having at least one type cation exchange groups having lower acidity than that of sulfonic acid group wherein a ratio of sulfonic acid groups to total cation exchange groups on one surface (A surface layer) is higher than that of the other surface (B surface layer); performing a partial polymerization of the diene derivative and dipping the resulting membrane into an organic solvent which is miscible with water and has a boiling point of higher than 30.degree. C. at 760 mmHg; holding the membrane between a pair of smooth plates; and heating the membrane at 50.degree. to 180.degree. C.; and if the diene derivative having carboxylic acid convertible group is used, converting said groups into carboxylic acid groups.

Process for producing cation exchange membrane by impregnating a diene

A homogeneous cation-exchange membrane made of one or more fluorinated polymer having cation-exchangeable groups is swollen with a water miscible organic solvent and then the solvent is removed from the swollen membrane and then membrane is treated with hydrochloric acid. The cation-exchange membrane of the fluorinated polymer having cation-exchangeable groups is modified to reduce the permeability of hydroxyl group ions by swelling it and removing the water-miscible organic solvent and then, treating it with hydrochloric acid.

Method of improving characteristic of cation-exchange membrane by

A cation exchange membrane is produced by treating a membrane of a fluorinated polymer having sulfonyl halide group on side chains with a mixture of 1 a reaction product of an amine with a halogenated monomer and 2 a vinyl monomer and/or diene monomer each of which has carboxylic acid group, phenolic hydroxyl group, sulfonic acid group and/or a functional group being convertible into carboxylic acid group, phenolic hydroxyl group or sulfonic acid group.

Process for producing cation exchange membrane by treatment of

A homogeneous cation-exchange membrane made of one or more fluorinated polymer having cation-exchangeable groups is swollen with a water miscible organic solvent and then the solvent is removed from the swollen membrane. The fluorinated polymer having cation-exchangeable groups has special characteristics to the water-miscible organic solvent because the cation-exchangeable groups have high affinity to the water-miscible organic solvent though the base of the fluorinated polymer may have water-and oil-repellent properties, whereby the cation-exchange membrane of the fluorinated polymer having cation-exchangeable groups is modified to reduce the permeability of hydroxyl group ions by swelling it and removing the water-miscible organic solvent.

Method of improving characteristics of cation-exchange membrane by

A cation-exchange membrane is prepared by immersing a monomer having lactone ring and/or a lactonizable monomer with or without a crosslinking agent or a polymerization initiator, into a fluorinated polymer membrane having cation-exchangeable groups and polymerizing the monomer.

Process for preparing cation-exchange membrane by polymerizing lactone

A cation-exchange membrane is prepared by impregnating a diene monomer having carboxylic acid group or a functional group which can be converted to a carboxylic acid group, into a fluorinated polymer membrane having cation-exchangeable groups; partially polymerizing said diene monomer; swelling the membrane with a water miscible organic solvent and heat-treating the swollen membrane and if necessary, converting the functional groups to carboxylic acid groups.

Polymeric electrolyte complexes are prepared by reacting at least one polymer represented by one of the following formulas: ##STR1## wherein R.sub.1 and R.sub.2 represent hydrogen or alkyl of 1 to 4 carbon atoms; R.sub.3 is --CH.sub.2 --C(R).dbd.CH.sub.2, --(CH.sub.2).sub.m COOC(R).dbd.CH.sub.2,--CH.sub.2).sub.m COOCH.sub.2 --C(R).dbd.CH.sub.2, or --CH.sub.2).sub.m O-C(R).dbd.CH.sub.2,--CH.sub.2).sub.m O-CH.sub.2 -C(R).dbd.CH.sub.2 or ##STR2## wherein R is hydrogen or methyl, m is a number from 1 to 3 and n is 0 or 1; at least one of R.sub.4, R.sub.5 and R.sub.6 is --CH.sub.2 --C(R).dbd.CH.sub.2, --CH.sub.2).sub.m COOC(R).dbd.CH.sub.2, --CH.sub.2).sub.m COOCH.sub.2 OC(R).dbd.CH.sub.2,--CH.sub.2).sub.m O--C(R).dbd.CH.sub.2,--CH.sub.2).sub.m O--CH.sub.2 --C(R).dbd.CH.sub.2, --CH.sub.2).sub.m CONH-C(R).dbd.CH.sub.2 or ##STR3## wherein R is hydrogen or methyl, m is a number from 1 to 3 and n is 0 or 1; the remaining R.sub.4, R.sub.5 and R.sub.6 groups represent alkyl or alkylol groups of 1 to 4 carbon atoms; b is an integer of 10 to 20,000; a/b is in a range of 0.01 to 2; c/b is in a range of 0 to 3; X is halogen or hydroxyl, and M is a vinyl monomer and/or a monomer having an ethylenic double bond, with a highly electrolytic polyanion dissolved in water or a mixed solvent of water and at least one member selected from the group consisting of water-miscible acids and organic solvents.

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Shinnanyo, Japan

Shunichi Asami