US3699089A
Expired / Lapsed
US
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Anhydrous sparingly cross-linked hydrophilic copolymers
Assignee: Czech Academy of Sciences
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Filing: 1968-09-25
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Granted: 1972-10-17
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Expires: 1988-09-25
Abstract
Abstract A SUBSTANTIALLY ANHYDROUS SPARINGLY CROSS LINKED HYDROPHILIC POLYMER CAPABLE OF BEING SWOLLEN WHEN IN CONTACT WITH WATER. THE POLYMER CONSISTS OF AT LEAST 98% BY WEIGHT OF A WATER SOLUBLE MONOESTERS OF ACRYLIC OR METHACRYLIC ACID, ITS AMIDES, MIXTURE AND DERIVATIVES THEREOF AND NOT MORE THAN 2% BY WEIGHT OF A DIESTER OF THE MONOMERS. THE POLYMER IS THREE DIMENSIONALLY CROSS-LINKED AND IN THE FORM OF A XEROGEL OR IN THE FORM OF A GEL INTO WHICH PLASTICIZER MAY BE ADDED.
Inventors
- 👤 Otto Wichterle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 05:07
CPC Classifications
G; G02; G02B; G02B1/00; G02B1/04; G02B1/041; G02B1/043; B; B29; B29C; B29C71/00; B29C71/0009; B29D; B29D11/00; B29D11/00009; B29D11/00038; B29D11/00067; B29D11/00932; B29D11/00942; Y; Y10; Y10S; Y10S425/00; Y10S425/808
Claims Analysis
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References Cited (Backward Citations)
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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) | 1975-10-17 | 1976-04-17 | 1976-10-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-17 | 1980-04-17 | 1980-10-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-17 | 1984-04-17 | 1984-10-17 | $7700.00 | Window Closed / Lapsed |