Patent US1824937A successfully refreshed from Google Patents.
US3663492A
Expired / Lapsed
US
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Process for the preparation of polyamidocarboxylic acids
Assignee: Dynamit Nobel AG
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Filing: 1971-01-06
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Granted: 1972-05-16
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Expires: 1991-01-06
Abstract
Abstract NEW AND IMPROVED PROCESS OF PRODUCING POLYCARBOXY PENDANT POLYCARBONAMIDE POLYMERS SUITABLE FOR CYCLIZATION INTO POLYIMIDES BY FORMING A DISPERSION OF EACH REACTANT, THAT IS, A TETRACARBOXYLIC ACID (OR A CORRESPONDING MONO OR DIANHYDRIDE) AND A DIAMINE RESPECTIVELY, IN AN INERT SUBSTANTIALLY NON-POLAR, ORGANIC SUBSTANTIALLY ANHYDROUS LIQUID; AND THEN ADDING A POLAR ORGANIC SOLVENT SLOWLY TO THE DISPERSION EITHER CONTINUOUSLY OR INTERMITTENTLY, WITH STIRRING AND APPROPIATE HEAT CONTROL, WHEREBY SAID REACTANTS REACT TO FORM SAID POLYCARBOXYL PENDANT POLYCARBONAMIDE.
Inventors
- 👤 Erich Behr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 15:55
CPC Classifications
C; C08; C08G; C08G73/00; C08G73/06; C08G73/10; C08G73/1003
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) | 1975-05-16 | 1975-11-15 | 1976-05-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-16 | 1979-11-15 | 1980-05-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-16 | 1983-11-15 | 1984-05-16 | $7700.00 | Window Closed / Lapsed |