Electrolytic cell ion-exchange membranes
AssigneeThe Dow Chemical Company
InventorsBobby R. Ezzell, Harry S. Burney, Jr., Marius W. Sorenson
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Abstract
Electrolytic cell ion-exchange membranes, comprising fluoropolymers having pendant sulfonic acid functional groups and/or carboxylic acid functional groups, are treated with primary, secondary, and/or tertiary amines to provide dimensional stability and other improvements to the membranes. The treatment with amines provides easily-disassociable amines salts which are leached out by an aqueous leachant, e.g., cell electrolyte, thereby providing sulfonic acid groups and/or carboxylic acid groups to function as ion exchange sites in the membrane during subsequent cell operation.
Claims14
A method for substantially stabilizing the dimensions of fluoropolymer membranes for use in electrolytic cells, said fluoropolymer membranes containing sulfonate functional groups of the empirical formula R--SO.sub.3.sup.-, and/or carboxylate functional groups of the empirical formula R--COO.sup.-, where R represents attachment to a fluoropolymer,
- said method comprising contacting the membranes at a temperature in the range of about 0.degree. C. to 100.degree. C. with at least one liquid amine of the group consisting of primary, secondary, and tertiary organic amines for a period of time to form easily disassociable amine salts with an appreciable amount of said acid groups, said salts conforming substantially to the empirical formula R--SO.sub.3 H.A and/or R--COOH.A, where A is amine, said amine moieties being easily removed by aqueous leaching,
- draining or drying the membranes to substantially remove excess liquid amine therefrom,
- storing said membranes until installment thereof in electrolytic cells.
Dependencies are inferred from the claim text.