Patent US3661634A successfully refreshed from Google Patents.
US3661634A
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Semipermeable osmotic membrane and method of producing same
Assignee: United States Department of the Interior
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Filing: 1969-10-31
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Granted: 1972-05-09
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Expires: 1989-10-31
Abstract
Abstract Semipermeable membranes prepared from a mixture of vinylpyrrolidone polymers and polyisocyantes. Process for preparing such membranes by casting the mixture from solution onto a smooth surface followed by curing under conditions of controlled humidity. Reaction of polyisocyanates with certain compounds having an active hydrogen atom provides a ''''blocked'''' polyisocyanate which does not react immediately with water at ambient temperatures thereby allowing greater processing control of membrane production.
Inventors
- 👤 Robert L Riley
- 👤 Clifford R Lyons
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:41
CPC Classifications
C; C08; C08G; C08G18/00; C08G18/06; C08G18/70; C08G18/72; C08G18/80; C08G18/8061; B; B01; B01D; B01D69/00; B01D69/12; B01D71/00; B01D71/06; B01D71/44; B01D71/441; C08G18/28; C08G18/30; C08G18/302; C08G18/40; C08G18/62; C08G18/6283; C08L; C08L75/00; Y; Y10; Y10S; Y10S521/00; Y10S521/905
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
22 words
A process according to claim 1 wherein the ratio of blocked isocyanate groups to polymerized vinylpyrrolidone groups is greater than about 0.25.
Claim 2
Dependent Claim
36 words
A process according to claim 1 wherein said curing is carried oUt in an atmosphere containing sufficient water vapor to provide said atmosphere with a relative humidity of less than about 20 percent at 25.20 C.
Claim 3
Dependent Claim
46 words
A process according to claim 3 wherein said vinylpyrrolidone polymer is a polyvinylpyrrolidone having an average molecular weight in excess of about 100,000, wherein said ratio is between about 0.4 and about 2.0, and wherein said temperature is from about 140* C. to about 175* C.
Claim 4
Dependent Claim
20 words
A process according to claim 4 wherein said blocked polyisocyanate is the reaction product of a polyisocyanate with epsilon -caprolactam.
Claim 5
Dependent Claim
14 words
A process according to claim 4 wherein said polyisocyanate is a blocked polymethylene polyphenylisocyanate.
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) | 1975-05-09 | 1975-11-08 | 1976-05-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-09 | 1979-11-08 | 1980-05-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-09 | 1983-11-08 | 1984-05-09 | $7700.00 | Window Closed / Lapsed |