Patent US3639524A successfully refreshed from Google Patents.
US3639524A
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US
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Hydrophilic gel polymer insoluble in water from polyvinylpyrrolidone with n-vinyl-2-pyrrolidone and methacrylic modifier
Assignee: Individual
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Filing: 1969-07-28
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Granted: 1972-02-01
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Expires: 1989-07-28
Abstract
Abstract A PLASTIC OR RESIN PRODUCT OBTAINED BY MIXING COMMINUTED POLYVINYLPYRROLIODONE, VINYLPYRROLIDONE, A MODIFIER SUCH AS AN ORGANIC METHACYLATE, OPTIONALLY A CROSSLINKING AGENT, AND OPTIONALLY A CATALYST; AND CAUSING POLYMERIZATION TO TAKE PLACE BY ELEVATING THE TEMPERATURE. THE INVENTIVE PRODUCT IS INSOLUBLE IN WATER BUT IS HYDRATABLE WITH WATER, AND MAY TAKE UP AS MUCH AS 90% BY WEIGHT OF WATER. THE HYDRATED PRODUCT IS OPTICALLY TRANSPARENT AND ESPICALLY SUITABLE FOR CONTACT LENSES.
Inventors
- 👤 Maurice Seiderman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 10:06
CPC Classifications
G; G02; G02B; G02B1/00; G02B1/04; G02B1/041; G02B1/043; C; C08; C08F; C08F220/00; C08F220/02; C08F220/10; C08F220/12; C08F220/20; C08F26/00; C08F26/06; C08F271/00; C08F271/02
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) | 1975-01-31 | 1975-08-02 | 1976-02-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-31 | 1979-08-02 | 1980-02-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-31 | 1983-08-02 | 1984-02-01 | $7700.00 | Window Closed / Lapsed |