US3557083A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cellulose triacetate containing at most 150 parts per million by weight of combined sulfuric acid and process for its production
Assignee: Rhodiaceta SA
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Filing: 1968-05-20
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Granted: 1971-01-19
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Expires: 1988-05-20
Abstract
Abstract CELLULOSE TRIACETATE CONTAINING AT MOST 150 PARTS PER MILLION BY WEIGHT OF COMBINED SULPHURIC ACID AND HAVING A DISSOLUTION FACTOR OF AT LEAST 90 IN 10 MINUTES IS PRODUCED BY PRECIPITATING WITH WATER CELLULOSE TRICETATE FROM AN ACETIC GUM OBTAINED BY THE ACETYLATION OF WOOD PULP IN THE PRESENCE OF SULPHURIC ACID AS CATALYST, THEN DISPLACING THE WATER IN THE RESULTING WATER-IMPREGNATED CELLULOSE TRIACETATE WITH METHANOL, THEN DISPLACING THE METHANOL WITH ETHYL ETHER OR ISOPROPL ETHER, AND FINALLY DRYING THE ETHER-IMPREGNATED CELLULOSE TRIACETATE.
Inventors
- 👤 Jean Sacco
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:23
CPC Classifications
C; C08; C08B; C08B3/00; C08B3/22; C08B3/26; C08B3/28; C08B3/06
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) | 1974-01-18 | 1974-07-20 | 1975-01-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-18 | 1978-07-20 | 1979-01-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-18 | 1982-07-20 | 1983-01-19 | $7700.00 | Window Closed / Lapsed |