Patent US3812071A successfully refreshed from Google Patents.
US3812071A
Expired / Lapsed
US
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Method of manufacturing hydrogels
Assignee: Czech Academy of Sciences
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Filing: 1971-09-02
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Granted: 1974-05-21
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Expires: 1991-09-02
Abstract
Abstract STRONG, ELASTIC HYDROGELS ARE MADE BY COPOLYMERIZING ACRYLONTRILE OR METHACRYLONITRILE OR MIXTURES THEREOF WITH CO-MONOMERS HAVING HYDROPHILIC SIDE-GROUPS, SUCH AS ACRYLAMIDE, METHACRYLAMIDE, ACRYLIC ACID, METHACRYLIC ACID AND VINYL PYRROLIDONE OR WITH MIXTURES OF SUCH CO-MONOMERS. THE COPOLYMERIZATION IS CARRIED OUT IN PRESECE OF FREE RADICALS AND IN AN INORGANIC SOLVENT WHICH DOES NOT UNDERGO ANY SUBSTANTIAL CHAIN TRANSFER SUCH AS CONCENTERED AQUEOUS ZINC CHLORIDE SOLUTION OR NITRIC ACID.
Inventors
- 👤 A Stoy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:29
CPC Classifications
C; C08; C08F; C08F2/00; C08F2/04; C08F2/10; G; G02; G02B; G02B1/00; G02B1/04; G02B1/041; G02B1/043
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) | 1977-05-20 | 1977-11-19 | 1978-05-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-20 | 1981-11-19 | 1982-05-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-20 | 1985-11-19 | 1986-05-21 | $7700.00 | Window Closed / Lapsed |