US3632797A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the preparation of polyimides
Assignee: BP Corp North America Inc
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Filing: 1968-11-26
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Granted: 1972-01-04
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Expires: 1988-11-26
Abstract
Abstract PROCESS FOR THE PREPARATION OF POLYIMIDES FROM POLYMERS CONTAINING A PLURALITY OF CARBOXY GROUPS AND/OR ANHYDRIDE GROUPS WHICH COMPRISES TREATING SAID POLYMER WITH AN AMIDE, SULFONAMIDE OR PHOSPHONAMIDE AT TEMPERATURE OF FROM ABOUT 150*C. TO ABOUT 250*C. WATER MAY BE ADDED AS A CAYALYST.
Inventors
- 👤 Franklin Boardman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 22:26
CPC Classifications
C; C08; C08F; C08F8/00; C08F8/30; C08F8/32
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) | 1975-01-03 | 1975-07-05 | 1976-01-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-03 | 1979-07-05 | 1980-01-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-03 | 1983-07-05 | 1984-01-04 | $7700.00 | Window Closed / Lapsed |