US3592672A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dry stabilized,rewettable semipermeable cellulose ester and ether membranes and their preparation
Assignee: Eastman Kodak Co
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Filing: 1969-12-22
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Granted: 1971-07-13
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Expires: 1989-12-22
Abstract
Abstract MEMBRANES SPECIALLY ADAPTED TO PREFERENTIALLY PERMIT THE PASSAGE OF RELATIVELY PURE WATER THROUGH THEM, WHILE RESISTING THE PASSAGE OF DISSOLVED SALTS MUST CONVENTIONALLY BE KEPT WATER-WET IN ORDER TO RETIAN THIS ABILITY TO EXCLUDE SALTS. DRY, REWETTABLE, STABILIZED MEMBRANES IN WHICH THIS DESIRABLE PROPERTY IS PRESERVED, CAN BE MADE BY TREATING THE WET MEMBRANE FIRST WITH A WATER-MISCIBLE SOLVENT, THEN WITH A NON-POLAR ORGANIC SOLVENT AND FINALLY DRYING THE MEMBRANE. THE PRESENCE OF A WATER-SOLUBLE POLYOL IN THE DRY MEMBRANE RESULTS IN STILL BETTER PROPERTIES.
Inventors
- 👤 Martin E Rowley
- 👤 Walter D Slowig
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:54
CPC Classifications
C; C08; C08L; C08L1/00; C08L1/08; C08L1/10
Claims Analysis
Total Claims: 0
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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) | 1974-07-12 | 1975-01-11 | 1975-07-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-07-12 | 1979-01-11 | 1979-07-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-07-12 | 1983-01-11 | 1983-07-13 | $7700.00 | Window Closed / Lapsed |