Patent US2543191A successfully refreshed from Google Patents.
US2543191A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Manufacture of organic esters of cellulose
Assignee: Celanese Corp
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Filing: 1948-10-15
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Granted: 1951-02-27
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Expires: 1968-10-15
Abstract
No abstract record available.
Inventors
- 👤 Neilson John Francis
- 👤 Hawkes John Arthur
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 23:05
CPC Classifications
C; C08; C08B; C08B3/00; C08B3/06
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
91 words
A PROCESS FOR THE MANUFACTURE OF AN ACETONE-SOLUBLE CELLULOSE ACETATE HAVING AN ACETYL VALUE OF AT LEAST 57%, CALCULATED AS ACETIC ACID, WHICH COMPRISES ACETYLATING CELLULOSE WITH ACETIC ANHYDRIDE IN THE PRESENCE OF A SOLVENT FOR THE CELLULOSE TRIACETATE FORMED, USING AS CATALYST THROUGHOUT THE ACETYLATION 0.8 TO 10% OF SULPHURIC ACID AND 0.2 TO 2% OF PERCHLORIC ACID, CALCULATED ON THE WEIGHT OF THE CELLULOSE, AND HYDROLYZING THE CELLULOSE TRIACETATE IN THE ACETYLATION SOLUTION UNTIL THE CELLULOSE ACETATE IS SOLUBLE IN ACETONE AND HAS AN ACETYL VALUE AT LEAST 57%.
Claim 2
Dependent Claim
91 words
A PROCESS FOR THE MANUFACTURE OF AN ACETONE-SOLUBLE CELLULOSE ACETATE HAVING AN ACETYL VALUE OF AT LEAST 57%, CALCULATED AS ACETIC ACID, WHICH COMPRISES ACETYLATING CELLULOSE WITH ACETIC ANHYDRIDE IN THE PRESENCE OF A SOLVENT FOR THE CELLULOSE TRIACETATE FORMED, USING AS CATALYST THROUGHOUT THE ACETYLATION 0.8 TO 10% OF SULPHURIC ACID AND 0.2 TO 2% OF PERCHLORIC ACID, CALCULATED ON THE WEIGHT OF THE CELLULOSE, AND HYDROLYZING THE CELLULOSE TRIACETATE IN THE ACETYLATION SOLUTION UNTIL THE CELLULOSE ACETATE IS SOLUBLE IN ACETONE AND HAS AN ACETYL VALUE AT LEAST 57%.
References Cited (Backward Citations)
US2175842A
Cited
US2265528A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1954-02-26 | 1954-08-28 | 1955-02-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1958-02-26 | 1958-08-28 | 1959-02-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1962-02-26 | 1962-08-28 | 1963-02-27 | $7700.00 | Window Closed / Lapsed |