Patent US6359816B1 successfully refreshed from Google Patents.
US2899423A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Manufacture of cellulose acetate
Assignee: —
•
Filing: —
•
Granted: 1959-08-11
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Expires: 1976-08-11
Abstract
No abstract record available.
Inventors
No inventors recorded.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 18:08
CPC Classifications
C; C08; C08B; C08B3/00; C08B3/06
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
141 words
A PROCESS OF PREPARING CELLULOSE ACETATE WHICH COMPRISES PRETREATING CELLULOSE CONTAINING 1-7% OF WATER WITH A MIXTURE OF ACETIC ACID AND ACETIC ANHYDRIDE AT 80-180* F. FOR A TIME OF AT LEAST 15 MINUTES WHICH IS INSUFFICIENT TO DESTROY MORE THAN 50% OF THE WATER IN THE CELLULOSE, THE ACETIC ANHYDRIDE BEING 30-80% OF THE MIXTURE AND IN AN AMOUNT WHICH WILL COMPLETELY ESTERIFY THE CELLULOSE BUT NOT MORE THAN 3.5 PARTS PER PART THEREOF, COOLING THE MASS CONSISTING OF PRETREATED CELLULOSE, ACETIC ANHYDRIDE, AND ACETIC ACID TO 35-50*F., ADDIND TO THE MASS 5-12% BASED ON THE CELLULOSE OF SULFURIC ACID CATALYST WHEREBY ESTERIFICATION IS INDUCED AND REGULATING THE ESTERIFICATION SO THAT THE TEMPERATURE OF THE MASS PROGRESSIVELY RISES TO A MAXIMUM TEMPERATURE WITHIN THE RANGE OF 80-130* F. AND CONTINUING THE ESTERIFICATION UNTIL THE CELLULOSE HAS BEEN SUBSTANTIALLY COMPLETELY ACETYLATED.
Claim 2
Dependent Claim
141 words
A PROCESS OF PREPARING CELLULOSE ACETATE WHICH COMPRISES PRETREATING CELLULOSE CONTAINING 1-7% OF WATER WITH A MIXTURE OF ACETIC ACID AND ACETIC ANHYDRIDE AT 80-180* F. FOR A TIME OF AT LEAST 15 MINUTES WHICH IS INSUFFICIENT TO DESTROY MORE THAN 50% OF THE WATER IN THE CELLULOSE, THE ACETIC ANHYDRIDE BEING 30-80% OF THE MIXTURE AND IN AN AMOUNT WHICH WILL COMPLETELY ESTERIFY THE CELLULOSE BUT NOT MORE THAN 3.5 PARTS PER PART THEREOF, COOLING THE MASS CONSISTING OF PRETREATED CELLULOSE, ACETIC ANHYDRIDE, AND ACETIC ACID TO 35-50*F., ADDIND TO THE MASS 5-12% BASED ON THE CELLULOSE OF SULFURIC ACID CATALYST WHEREBY ESTERIFICATION IS INDUCED AND REGULATING THE ESTERIFICATION SO THAT THE TEMPERATURE OF THE MASS PROGRESSIVELY RISES TO A MAXIMUM TEMPERATURE WITHIN THE RANGE OF 80-130* F. AND CONTINUING THE ESTERIFICATION UNTIL THE CELLULOSE HAS BEEN SUBSTANTIALLY COMPLETELY ACETYLATED.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1962-08-10 | 1963-02-09 | 1963-08-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1966-08-10 | 1967-02-09 | 1967-08-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1970-08-10 | 1971-02-09 | 1971-08-11 | $7700.00 | Window Closed / Lapsed |