Patent US2309658A successfully refreshed from Google Patents.
US3671490A
Expired / Lapsed
US
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Cross-linked polyimides
Assignee: Rhone Poulenc SA
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Filing: 1971-01-22
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Granted: 1972-06-20
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Expires: 1991-01-22
Abstract
Abstract The invention provides novel cross-linked polyimides made by reacting a dianhydride with a molar excess of diamine, reacting the product with an unsaturated anhydride to produce an unsaturated polyamide, and heating the latter to produce the cross-linked polyimide.
Inventors
- 👤 Michel Bargain
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 23:40
CPC Classifications
C; C08; C08G; C08G73/00; C08G73/06; C08G73/10; C08G73/1003; C08G73/1007; C08G73/101; C08G73/1014; B; B32; B32B; B32B27/00; H; H01; H01B; H01B3/00; H01B3/18; H01B3/30; H01B3/303; H01B3/306; H01B3/307
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
6 words
A polyamide consisting of the formula:
Claim 2
Dependent Claim
9 words
A cross-linked polyimide consisting of units of the formula:
Claim 3
Dependent Claim
6 words
A polyamide consisting of the formula:
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) | 1975-06-20 | 1975-12-20 | 1976-06-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-20 | 1979-12-20 | 1980-06-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-20 | 1983-12-20 | 1984-06-20 | $7700.00 | Window Closed / Lapsed |