US3689439A
Expired / Lapsed
US
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Process for preparing a crosslinked porous polyvinyl pyrrolidone granule
Assignee: GAF Chemicals Corp
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Filing: 1971-04-05
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Granted: 1972-09-05
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Expires: 1991-04-05
Abstract
Abstract A POROUS GRANULAR OR POROUS BEAD FORM OF A VINYLPYRROLIDONE POLYMR IS PRODUCED FROM A SUSPENSION OF MONOMERIC VINYL-PYRROLIDONE, OPTIONALLY WITH ADDITIONAL MONOMER OR MONOMERS, AND A CONTROLLED AMOUNT OF CROSSLINKING AGENT IN AN AQUEOUS SOLUTION OF AN ELECTOLYTE, THE SUSPENSION BEING MAINTAINED DURING POLYMERIZATION BY MECHANICAL MEANS. A FREE RADICAL POLYMERIZATION SOURCE IS UTILIZED. THE RESULTATN PRODUCT MAINTAINS ITS PARTICULATE FORM AFTER WETTING.
Inventors
- 👤 Nathan D Field
- 👤 Earl P Williams
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:59
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/28; A; A23; A23L; A23L2/00; A23L2/70; A23L2/80; C12; C12H; C12H1/00; C12H1/02; C12H1/04; C12H1/0416; C12H1/0424; C08J2339/00
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) | 1975-09-05 | 1976-03-06 | 1976-09-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-09-05 | 1980-03-06 | 1980-09-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-09-05 | 1984-03-06 | 1984-09-05 | $7700.00 | Window Closed / Lapsed |