Novel fluorinated copolymer with tridihydro fluorosulfonyl fluoride pendant groups and preparation thereof
AssigneeAsahi Kasei Kogyo Kabushiki Kaisha
InventorsKyoji Kimoto, Hirotsugu Miyauchi, Jukichi Ohmura, Mikio Ebisawa, Toshioki Hane
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Abstract
A novel fluorinated copolymer is prepared by copolymerization of a fluorinated olefin with a novel sulfur containing fluorinated vinyl ether of the formula: ##STR1## wherein k is 0 or 1 and l is an integer of 3 to 5, which is prepared from starting materials which are also novel. Said copolymer is useful for preparation of a fluorinated cation exchange membrane having carboxylic acid groups and/or sulfonic acid groups which can be used advantageously in electrolysis of an aqueous alkali metal halide solution with improved electrolysis performance.
Claims28
A fluorinated copolymer, consisting essentially of the following recurring units (A) and (B):
- (A)--CA.sub.1 A.sub.2 --CA.sub.3 A.sub.4 -- (A)
- wherein each of A.sub.1 and A.sub.2 is F or H;
- A.sub.3 is F, Cl or H;
- and A.sub.4 is F, Cl, CF.sub.3, --OR.sub.F or CH.sub.3, R.sub.F being C.sub.1 -C.sub.5 perfluoroalkyl, ##STR60## wherein k is 0 or 1, l is an integer of 3 to 5, the molar ratio of units (A) (B) being from 1 to 16, said copolymer being substantially a random copolymer having a molecular weight generally in the range from 8,000 to 1,000,000 and having a melt index generally in the range from 0.001 g/10 min. to 500 g/10 min., as measured by the use of an orifice of 2.1 mm in diameter and 8 mm in length, under a load of 2.16 kg at 250.degree. C.
A process for producing a fluorinated cation exchange membrane having both carboxylic acid groups and sulfonic acid groups, which comprises subjecting one surface layer of a membrane of a fluorinated copolymer comprising essentially the following recurring units (C) and (B):
- ##STR63## wherein L is F, Cl, CF.sub.3, -OR.sub.F or H, R.sub.F being C.sub.1 -C.sub.5 perfluoroalkyl, ##STR64## wherein k is 0 or 1, and l is an integer of 3 to 5, to treatment with an aqueous solution of at least one reducing agent selected from the group consisting of inorganic acids having reducing ability, salts thereof and hydrazines in the presence of at least one organic compound having 1 to 12 carbon atoms selected from the group consisting of alcohols, carboxylic acids, sulfonic acids, nitriles and ethers, said copolymer being substantially a random copolymer having a molecular weight generally in the range from 8,000 to 1,000,000 and having a melt index generally in the range from 0.001 g/10 min. to 500 g/10 min., as measured by the use of an orifice of 2.1 mm in diameter and 8 mm in length, under a load of 2.16 kg at 250.degree. C.
A process for producing a fluorinated cation exchange membrane having sulfonic acid groups, which comprises hydrolyzing the pendant terminal groups of a membrane of a fluorinated copolymer comprising essentially the following recurring units (C) and (B):
- ##STR65## wherein L is F, Cl, CF.sub.3, OR.sub.F or H, R.sub.F being C.sub.1 -C.sub.5 perfluoroalkyl, ##STR66## wherein k is 0 or 1, and l is an integer of 3 to 5, said copolymer being substantially a random copolymer having a molecular weight generally in the range from 8,000 to 1,000,000 and having a melt index generally in the range from 0.001 g/10 min. to 500 g/10 min., as measured by the use of an orifice of 2.1 mm in diameter and 8 mm in length, under a load of 2.16 kg at 250.degree. C.
Dependencies are inferred from the claim text.