Patent US2694631A successfully refreshed from Google Patents.
US2694631A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process of preparing wood pulp
Assignee: Eastman Kodak Co
•
Filing: 1949-08-31
•
Granted: 1954-11-16
•
Expires: 1969-08-31
Abstract
No abstract record available.
Inventors
- 👤 George A Richter
- 👤 Robert H Macclaren
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 11:02
CPC Classifications
D; D21; D21C; D21C3/00; D21C3/02; D21C3/022; D21C1/00; D21C1/04
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
108 words
A METHOD OF PREPARING WOOD PULP HAVING A HIGH A-CELLULOSE AND LOW PENTOSAN CONTENT WHICH COMPRISES HEATING WOOD CHIPS WITH AQUEOUS SO2 SOLUTIONS HAVING A SOLUTION CONCENTRATION 12 TO 35% SO2 AT 100 TO 110* C. FOR FOUR TO TEN HOURS IN AN ENCLOSED VESSEL WHEREBY THE WOOD REMAINS UNPULPED, AND SUBJECTING THE SO-TREATED WOOD TO A PULPING OPERATION WITH AN ALKALINE PULPING LIQUOR ESSENTIALLY CONSISTING OF SODIUM CARBONATE, SODIUM SULFIDE AND SODIUM SULFITE, THE SODIUM CARBONATE BEING THE PRINCIPAL SODIUM COMPOUND, HAVING A CONCENTRATION OF 3-5 LBS. OF SODIUM ION IN TERMS OF NA2O PER CUBIC FOOT OF LIQUOR UNDER PRESSURE AT 160-175* C. FOR 2-4 HOURS.
Claim 2
Independent Claim
108 words
A METHOD OF PREPARING WOOD PULP HAVING A HIGH A-CELLULOSE AND LOW PENTOSAN CONTENT WHICH COMPRISES HEATING WOOD CHIPS WITH AQUEOUS SO2 SOLUTIONS HAVING A SOLUTION CONCENTRATION 12 TO 35% SO2 AT 100 TO 110* C. FOR FOUR TO TEN HOURS IN AN ENCLOSED VESSEL WHEREBY THE WOOD REMAINS UNPULPED, AND SUBJECTING THE SO-TREATED WOOD TO A PULPING OPERATION WITH AN ALKALINE PULPING LIQUOR ESSENTIALLY CONSISTING OF SODIUM CARBONATE, SODIUM SULFIDE AND SODIUM SULFITE, THE SODIUM CARBONATE BEING THE PRINCIPAL SODIUM COMPOUND, HAVING A CONCENTRATION OF 3-5 LBS. OF SODIUM ION IN TERMS OF NA2O PER CUBIC FOOT OF LIQUOR UNDER PRESSURE AT 160-175* C. FOR 2-4 HOURS.
References Cited (Backward Citations)
US1722993A
Cited
US1859847A
Cited
US1787954A
Cited
US1931575A
Cited
US1918250A
Cited
US1838326A
Cited
US1804967A
Cited
US1921539A
Cited
US2065396A
Cited
US2542801A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1957-11-15 | 1958-05-17 | 1958-11-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1961-11-15 | 1962-05-17 | 1962-11-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1965-11-15 | 1966-05-17 | 1966-11-16 | $7700.00 | Window Closed / Lapsed |