US3607706A
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Method of making stable laminated cation-exchange membranes
Assignee: Veolia WTS Systems USA Inc
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Filing: 1967-08-04
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Granted: 1971-09-21
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Expires: 1987-08-04
Abstract
Abstract A method of making laminated multilayered, reinforced, cationexchange membranes of a styrene-divinylbenzene, diethylbenzene solvated structure, whereby the organic solvating medium is substituted by equilibration with a polar solvent, such as methanol, before the polymerized structure is sulfonated with concentrated sulfuric acid.
Inventors
- 👤 John L Eisenmann
- 👤 Edward T Roach
- 👤 Anthony Scieszko
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 08:31
CPC Classifications
C; C08; C08J; C08J5/00; C08J5/20; C08J5/22; C08J5/2206; C08J5/2218
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
20 words
The method of claim 1 wherein the sulfonating acid is reagent grade sulfuric at a concentration of at least 95%.
Claim 2
Dependent Claim
20 words
The method of claim 1 wherein the sulfonating acid is technical grade sulfuric at a concentration of at least 98%.
Claim 3
Dependent Claim
26 words
The method of claim 2 wherein the sulfonation of the structure is effected at temperatures in the range of about 18* C. to about 50* C.
Claim 4
Dependent Claim
26 words
The method of claim 3 wherein the sulfonation of the structure is effected at temperatures in the range of about 18* C. to about 22* C.
Claim 5
Dependent Claim
22 words
The method of claim 1 wherein the reinforcing woven fabric is selected from the group consisting of glass, polytetrafluoroethylene, polypropylene, and polyethylene.
Claim 6
Dependent Claim
31 words
The method of claim 1 wherein the nonpolar, nonpolymerizable organic solvating medium is diethylbenzene, the equilibrating water soluble organic solvent is substantially pure methanol, and the concentrated acid is sulfuric acid.
Claim 7
Dependent Claim
76 words
The method of claim 1 wherein the board structure is first equilibrated with a polar solvent of methanol for a period of several hours, equilibrated a second time in fresh methanol for several additional hours, reacted with concentrated sulfuric acid for a period of about 40 hours at a temperature of about 20* C., reacted again with freshly prepared 50% by volume of aqueous sulfuric acid for at least one hour, and finally rinsed in water.
Claim 8
Dependent Claim
10 words
A cation-exchange membrane prepared by the method of claim 1.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-20 | 1975-03-22 | 1975-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-20 | 1979-03-22 | 1979-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-20 | 1983-03-22 | 1983-09-21 | $7700.00 | Window Closed / Lapsed |