US2645577A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purifying wood pulp
Assignee: Acordis UK Ltd
•
Filing: 1950-04-08
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Granted: 1953-07-14
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Expires: 1970-04-08
Abstract
No abstract record available.
Inventors
- 👤 Bate Stanley Charles
- 👤 Peach Francis George
- 👤 Rogerson Walter Alan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:07
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/08; D21C9/083; C; C08; C08B; C08B1/00; C08B1/02
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
106 words
PROCESS FOR PURIFYING WOOD PULPS HAVING AN ALPHA-CELLULOSE CONTENT ABOVE 85% AND A PENTOSAN CONTENT BELOW 3.5% WHEREBY THERE IS OBTAINED A CELLULOSE SUITABLE FOR ESTERIFICATION, WHICH COMPRISES DIGESTING THE PULP WITH AN AQUEOUS CAUSTIC SODA SOLUTION OF 17-19% CONCENTRATION AT A TEMPERATURE OF 50* -55* C. FOR 45 TO 90 MINUTES AS THE ONLY CHEMICAL PURIFYING OPERATION, THEN REMOVING THE GREATER PART OF THE ALKALI SOLUTION FROM THE DIGESTED PULP WHILE MAINTAINING THE CONCENTRATION OF THE SOLUTION, WASHING THE PULP WITH WATER UNTIL IT IS SUBSTANTIALLY FREE FROM ALKALI, AND BOILING THE WASHED PULP WITH WATER FOR A PERIOD OF 15-45 MINUTES UNDER ATMOSPHERIC PRESSURE.
Claim 2
Dependent Claim
106 words
PROCESS FOR PURIFYING WOOD PULPS HAVING AN ALPHA-CELLULOSE CONTENT ABOVE 85% AND A PENTOSAN CONTENT BELOW 3.5% WHEREBY THERE IS OBTAINED A CELLULOSE SUITABLE FOR ESTERIFICATION, WHICH COMPRISES DIGESTING THE PULP WITH AN AQUEOUS CAUSTIC SODA SOLUTION OF 17-19% CONCENTRATION AT A TEMPERATURE OF 50* -55* C. FOR 45 TO 90 MINUTES AS THE ONLY CHEMICAL PURIFYING OPERATION, THEN REMOVING THE GREATER PART OF THE ALKALI SOLUTION FROM THE DIGESTED PULP WHILE MAINTAINING THE CONCENTRATION OF THE SOLUTION, WASHING THE PULP WITH WATER UNTIL IT IS SUBSTANTIALLY FREE FROM ALKALI, AND BOILING THE WASHED PULP WITH WATER FOR A PERIOD OF 15-45 MINUTES UNDER ATMOSPHERIC PRESSURE.
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) | 1956-07-13 | 1957-01-12 | 1957-07-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1960-07-13 | 1961-01-12 | 1961-07-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1964-07-13 | 1965-01-12 | 1965-07-14 | $7700.00 | Window Closed / Lapsed |