Patent US3639340A successfully refreshed from Google Patents.
US3639340A
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Thermostable polymers obtained from phenols and aromatic tetracarboxylic acid anhydrides
Assignee: Rhone Poulenc SA
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Filing: 1968-07-08
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Granted: 1972-02-01
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Expires: 1988-07-08
Abstract
Abstract NOVEL THERMOSTABLE POLYMERS ARE MADE BY POLYCONDENSING A PHENOL OR POLYPHENOL WITH A DIANHYDRIDE OF FORMULA; 1,3-DI(O=),((1,3-DI(O=)PHTHALANYL)-R-)PHTHALAN OR A CORRESPONDING TETRACID, IN WHICH R REPRESENTS A SIMPLE VALENCE BOND OR ONE OF THE FOLLOWING DIVALENT RADICALS: -O-,-S-,-SO2-,-NH-,-NR'',-N=N-, -N=N=O, -SI(-R1)2-, -O-SI(-R1)2-O-, -O-P(=O)(-R1)-O-, -P(=O)(-R1)- -CHOH-,-CO-,-C(CH32-, -CO-C6H4-CO- AND -CHOH-C6H4-CHOH-, R1 REPRESENTING A LOWER ALKYL, CYCLOALKYL OR ARYL RADICAL.
Inventors
- 👤 Maurice Balme
- 👤 Maurice Ducloux
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 18:32
CPC Classifications
B; B32; B32B; B32B27/00; C; C08; C08J; C08J5/00; C08J5/24; C08J5/241; C08J5/244; C08J5/249; Y; Y02; Y02A; Y02A30/00; Y02A30/14
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) | 1975-01-31 | 1975-08-02 | 1976-02-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-31 | 1979-08-02 | 1980-02-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-31 | 1983-08-02 | 1984-02-01 | $7700.00 | Window Closed / Lapsed |