US3767642A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Preparation of secondary cellulose acetate
Assignee: Celanese Corp
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Filing: 1971-06-30
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Granted: 1973-10-23
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Expires: 1991-06-30
Abstract
Abstract AN IMPROVED PROCESS FOR THE CONTINUOUS PRODUCTION OF SECONDARY CELLULOSE ESTERS, THE PROCESS INVOLVING THE STEPS OF FULLY NEUTRALIZING ALL STRONG ACID CATALYSTS IN A FULLY ESTERIFIED CELLULOSE DOPE AND THEN HYDROLYZING THE DOPE AT TEMPERATURES IN EXCESS OF ABOUT 125*C.
Inventors
- 👤 Kenneth C Campbell
- 👤 James M Davis
- 👤 Robert E Woods Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 18:01
CPC Classifications
C; C08; C08B; C08B3/00; C08B3/06; C08B3/22; C08B3/24
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) | 1976-10-22 | 1977-04-23 | 1977-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-22 | 1981-04-23 | 1981-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-22 | 1985-04-23 | 1985-10-23 | $7700.00 | Window Closed / Lapsed |