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US4376030A
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Electrolytic cell ion-exchange membranes
Assignee: Dow Chemical Co
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Filing: 1981-03-04
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Granted: 1983-03-08
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Expires: 2001-03-04
Abstract
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.
Inventors
- 👤 Bobby R. Ezzell
- 👤 Harry S. Burney, Jr.
- 👤 Marius W. Sorenson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 14:30
CPC Classifications
C; C08; C08J; C08J5/00; C08J5/20; C08J5/22; C25; C25B; C25B13/00; C08J5/2287; C08J5/2293; C08J2327/00; C08J2327/02; C08J2327/12
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
150 words
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 3 - , and/or carboxylate functional groups of the empirical formula R--COO - , where R represents attachment to a fluoropolymer, said method comprising contacting the membranes at a temperature in the range of about 0° C. to 100° 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 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.
Claim 2
Independent Claim
150 words
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 3 - , and/or carboxylate functional groups of the empirical formula R--COO - , where R represents attachment to a fluoropolymer, said method comprising contacting the membranes at a temperature in the range of about 0° C. to 100° 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 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.
Claim 3
Dependent Claim
46 words
The method of claim 1 wherein there is performed the additional steps of installing said membranes in brine electrolysis cells, leaching the amine moieties from the membranes with an aqueous leachant, and employing the membranes, while still wet with aqueous leachant, in the electrolysis of brine.
Claim 4
Dependent Claim
18 words
The method of claim 2 wherein the aqueous leachant is an aqueous electrolyte for the electrolysis of brine.
Claim 5
Dependent Claim
13 words
The method of claim 1 wherein the amine is dissolved in a solvent.
Claim 6
Dependent Claim
15 words
The method of claim 4 wherein the solvent is water or alcohol or mixture thereof.
Claim 7
Dependent Claim
34 words
The method of claim 1 wherein the amine is at least one selected from the group consisting of diethanolamine, triethanolamine, n-octyl amine, benzylmethylamine, N,N'-dimethylbenzylamine, dodecylamine, tert-octylamine, tri-n-octylamine, ethanolamine, diethylene triamine, isopropanolamine, diisopropanolamine, and triisopropanolamine.
Claim 8
Dependent Claim
51 words
The method of claim 1 wherein the fluoropolymer is at least one selected from the group consisting of solid copolymers of tetrafluoroethylene with a perfluorosulfonylethoxy vinyl ether, and solid copolymers of sulfostyrenated perfluoroethylenepropylene, wherein pendant sulfonyl groups have been hydrolyzed to sulfonic acid functional groups prior to contact with said amines.
Claim 9
Dependent Claim
71 words
The method of claim 1 wherein the amine or mixture of amines is dissolved in alcohol and/or water at a weight concentration of from about 2% to about 60%, the contact time is from about 2 minutes to about 24 hours, the contact temperature is from about 20° C. to about 80° C., and the thickness of the membrane is in the range of about 1 mil to about 20 mils.
Claim 10
Dependent Claim
23 words
The method of claim 1 wherein the amine comprises at least one of the group consisting of triethanolamine, trioctylamine, octylamine, diethanolamine, and dodecylamine.
Claim 11
Dependent Claim
28 words
The method of claim 1 wherein the membrane comprises a bilayered sheet of two films having the same or different eq. wts. and the same or different functionalities.
Claim 12
Dependent Claim
19 words
The dried membrane containing easily disassociable amine salts of said sulfonate functional groups prepared in accordance with claim 1.
Claim 13
Dependent Claim
12 words
The method of claim 1 wherein the fluoropolymer contains sulfonic acid groups.
Claim 14
Dependent Claim
12 words
The method of claim 1 wherein the fluoropolymer contains carboxylic acid groups.
Claim 15
Dependent Claim
23 words
The method of claim 1 wherein the fluoropolymer is a composite of fluoropolymer containing sulfonic acid groups and fluoropolymer containing carboxylic acid groups.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-03-07 | 1986-09-06 | 1987-03-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-03-07 | 1990-09-06 | 1991-03-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-03-07 | 1994-09-06 | 1995-03-08 | $7700.00 | Window Closed / Lapsed |