Patent US3663728A successfully refreshed from Google Patents.
US3663728A
Expired / Lapsed
US
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Process for producing polyamide acid and polyimides
Assignee: Von Roll Isola USA Inc
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Filing: 1968-07-25
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Granted: 1972-05-16
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Expires: 1988-07-25
Abstract
Abstract AROMATIC DIANHYDRIDES AND DIAMINES ARE REACTED IN A SOLVENT COMPRISING AT LEAST 40%, BY WEIGHT OF AN ALIPHATIC POLYOL TO PRODUCE POLYAMIDE ACID SOSLUTIONS WHICH CAN BE HEAT-CURED TO POLYIMIDE RESINS. THESE POLYAMIDE ACID SOLUTIONS CAN BE CONVERTED TO POLYIMIDES AND EMPLOYED AS INSULATION OVER CONDUCTION CORES, AS LAMINATING VARNISHES, AS DIPPING VARNISHES TO IMPREGNATE COILS OF PREVIOUSLYINSULATED WIRE IN THE MOTOR AND GENERATOR ROTORS, FIELD COILS, ETC.
Inventors
- 👤 John T Hoback
- 👤 Fred F Holub
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:29
CPC Classifications
C; C08; C08G; C08G73/00; C08G73/06; C08G73/10; C08G73/1003; C08G73/1007; C08G73/1028; C08G73/1032; C09; C09D; C09D5/00; C09D5/44; C09D5/4419; C09D5/4461
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 |