Patent US3644233A successfully refreshed from Google Patents.
US3644233A
Expired / Lapsed
US
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Process for preparing microporous foils from polyurethanes containing hydrated electrolytes
Assignee: Individual
•
Filing: 1968-07-18
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Granted: 1972-02-22
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Expires: 1988-07-18
Abstract
Abstract Microporous sheet structures having increased permeability to water vapor are prepared by coagulating a solution of a polyurethane by washing out the solvent of the solution with a nonsolvent, the coagulation being conducted in the presence of an electrolyte.
Inventors
- 👤 Harro Tranbel
- 👤 Harald Oertel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 23:37
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/28; C08J2375/00; C08J2375/04
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
13 words
The process of claim 1 wherein the polar solvent is dimethylformamide or dimethylacetamide.
Claim 2
Dependent Claim
54 words
The process of claim 1 wherein the electrolyte is selected from the group consisting of aluminum sulfate octadecahydrate, barium chloride dihydrate, cobalt-II-nitrate hexahydrate, chromium-III-acetate hydrate, chromium-III-sulphate pentadecahydrate, iron-II-sulfate heptahydrate, iron-III-phosphate tetrahydrate, potassium aluminum sulfate dodecahydrate, magnesium chloride hexahydrate, iron-II-ammonium sulfate hexahydrate, iron-II-ammonium sulfate dodecahydrate, sodium acetaTe trihydrate, disodium hydrogen phosphate dihydrate and nickel-II-chloride hexahydrate.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-02-21 | 1975-08-23 | 1976-02-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-21 | 1979-08-23 | 1980-02-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-21 | 1983-08-23 | 1984-02-22 | $7700.00 | Window Closed / Lapsed |