Heat-treated fluorocarbon sulfonamide cation exchange membrane and process therefor

Claim 2

The process of heating a membrane which has a first layer formed from an intermediate fluorinated polymer containing pendant sulfonyl halide groups attached to carbon atoms which have at least one fluorine atom connected thereto, said polymer having an equivalent weight in the range of 700 to 1600, at least 40% of the sulfonyl halide groups to a depth of at least 2×10 -5 mm of said intermediate polymer on at least one side of said first layer having been reacted with a di- or polyamine wherein one amino group is primary and a second amino group is primary or secondary, said first layer being unsupported or having support material consisting of inert fibers therein, to a temperature of 100° to 160° C. for a time of at least 15 minutes.

Claim 3

The process of claim 1 wherein said membrane has a second layer, said second layer being integral with said first layer and being of a fluorinated polymer having pendant side chains containing sulfonyl groups wherein the sulfonyl groups are in the --SO 3 M form wherein M is an alkali metal or NH 4 , the fluorinated polymer of each layer has an equivalent weight in the range of 1000 to 1300, said first layer having said support material therein in the form of a fabric of fibers of perfluorinated polymer, at least 40% of the sulfonyl halide groups to a depth of at least 10 -3 mm of said intermediate polymer on at least the exposed side of said first layer having been reacted with a diamine having 2 or 3 carbon atoms.

Claim 4

The process of claim 2 wherein said time is from 30 minutes to 2 days.

Claim 5

The process of claim 3 wherein the fluorinated polymer of each layer has an equivalent weight in the range of 1025 to 1200, and said diamine is ethylenediamine.

Claim 6

The process of claim 4 wherein said temperature is 100° to 140° C. and said time is from 2 hours to 1 day.

Claim 7

The process of claim 5 wherein said fluorinated polymer is a copolymer of tetrafluoroethylene and perfluoro(3,6-dioxa-4-methyl-7-octenesulfonyl fluoride).

Claim 8

The process of claim 6 wherein said fabric support material has been embedded in said first layer before reaction of the first layer with said di- or polyamine.

Claim 9

The process of claim 7 wherein only the exposed side of the first layer has been reacted with the amine.

Claim 10

The process of claim 7 wherein both sides of the first layer have been reacted with said amine.

Claim 11

The process of claim 6 wherein only the exposed side of the first layer has been reacted with the amine.

Claim 12

The process of claim 6 wherein both sides of the first layer have been reacted with said amine.

Claim 13

The process of claim 4 wherein only the exposed side of the first layer has been reacted with the amine.

Claim 14

The process of claim 4 wherein both sides of the first layer have been reacted with said amine.

Claim 15

The process of claim 2 wherein only the exposed side of the first layer has been reacted with the amine.

Claim 16

The process of claim 2 wherein both sides of the first layer have been reacted with said amine.

Claim 17

A process which comprises the steps: (A) treating a laminar membrane comprising (i) a first layer of fluorinated polymer having pendant side chains containing sulfonyl groups wherein the sulfonyl groups are in the --SO 2 X form wherein X is F or Cl, said first layer having support material consisting of fiber of inert polymer therein, and (ii) a second layer of fluorinated polymer having pendant side chains containing sulfonyl groups wherein the sulfonyl groups are in the --SO 3 M form wherein M is an alkali metal or NH 4 , said second layer being integral with said first layer, fluorinated polymer of each layer having an equivalent weight in the range of 700 to 1600, on at least the exposed surface of said first layer with a di- or polyamine wherein one amino group is primary and a second amino group is primary or secondary, until at least 40% of said --SO 2 X groups to a depth of at least 2×10 -5 mm in said first layer have reacted with said di- or polyamine; (B) hydrolyzing any remaining --SO 2 X groups in said laminar membrane; and (C) heating said laminar membrane to a temperature of 100° to 160° C. for a time of at least 15 minutes.

Claim 18

A process which comprises the steps: (A) treating a laminar membrane comprising (i) a first layer of fluorinated polymer having pendant side chains containing sulfonyl groups wherein the sulfonyl groups are in the --SO 2 X form wherein X is F or Cl, said first layer having support material consisting of fiber of inert polymer therein, and (ii) a second layer of fluorinated polymer having pendant side chains containing sulfonyl groups wherein the sulfonyl groups are in the --SO 3 M form wherein M is an alkali metal or NH 4 , said second layer being integral with said first layer, fluorinated polymer of each layer having an equivalent weight in the range of 700 to 1600, on at least the exposed surface of said first layer with a di- or polyamine wherein one amino group is primary and a second amino group is primary or secondary, until at least 40% of said --SO 2 X groups to a depth of at least 2×10 -5 mm in said first layer have reacted with said di- or polyamine; (B) hydrolyzing any remaining --SO 2 X groups in said laminar membrane; and (C) heating said laminar membrane to a temperature of 100° to 160° C. for a time of at least 15 minutes.

Claim 19

The process of claim 16 wherein in step (A) the fluorinated polymer of each layer has an equivalent weight in the range of 1000 to 1300, said support material is a fabric of fibers of perfluorinated polymer, and said treating is with a diamine having 2 or 3 carbon atoms and is to a depth of at least 10 -3 mm.

Claim 20

The process of claim 17 wherein in step (C) said time is from 30 minutes to 2 days.

Claim 21

The process of claim 18 wherein in step (A) the fluorinated polymer of each layer has an equivalent weight in the range of 1025 to 1200, and said diamine is ethylenediamine.

Claim 22

The process of claim 19 wherein in step (C) said temperature is from 100° to 140° C. and said time is from 2 hours to 1 day.

Claim 23

The process of claim 20 wherein said fluorinated polymer is a copolymer of tetrafluoroethylene and perfluoro(3,6-dioxa-4-methyl-7-octenesulfonyl fluoride).

Claim 24

The process of claim 21 wherein in step A only the exposed surface of said first layer is treated with the amine.

Claim 25

The process of claim 21 wherein in step A both surfaces of said laminar membrane are treated with said amine.

Claim 26

The membrane produced by the process of claims 1, 7, 10, 8, 11, 9, 16, 22, or 23.

Claim 27

In a process for production of halogen and an alkali metal hydroxide by electrolysis of a halide of said alkali metal in an electrolytic cell having anode and cathode compartments separated by a membrane, the improvement comprising passing ions of said metals through a membrane of claim 24.

Claim 28

The process of claim 19 wherein in step A only the exposed surface of said first layer is treated with the amine.

Claim 29

The process of claim 19 wherein in step A both surfaces of said laminar membrane are treated with said amine.

Claim 30

The process of claim 17 wherein in step A only the exposed surface of said first layer is treated with the amine.

Claim 31

The process of claim 17 wherein in step A both surfaces of said laminar membrane are treated with said amine.