US3740311A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Delignification of cellulosic pulp with ammonia gas followed by heating in the presence of oxygen
Assignee: PULP AND PAPER RES INST CA
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Filing: 1971-05-24
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Granted: 1973-06-19
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Expires: 1991-05-24
Abstract
Abstract A PROCEDURE FOR THE DELIGNIFICATION OF A CELLULOSIC PULP WHICH COMPRISES FIRST UNIFORMLY DISTRIBUTING AMMONIA GAS IN THE MOISTURE OF A FLUFFED PULP OF A CONSISTENCY OF ABOUT 15 TO BOUT 40% AND THEN, IN THE ABSENCE OF INTERMEDIATE WASHING, THE GASEOUS AMMONIA-TREATED PULP IS HEATED IN THE PRESENCE OF OXYGEN MAINTAINED AT A PRESSURE OF ABOUT 4 TO ABOUT 12 BARS AT A TEMPERATURE OF ABOUT 85 TO ABOUT 135*C. FOR A TIME OF ABOUT 10 TO ABOUT 360 MINUTES TO PROVIDE A PULP WITH A FINAL PH OF 9.6 TO 10.4.
Inventors
- 👤 N Liebergott
- 👤 D Clayton
- 👤 Montigny R De
- 👤 B Burgess
- 👤 Montigny M De
- 👤 Gaspe Tache A De
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 06:20
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/10; D21C9/1026
Claims Analysis
Total Claims: 0
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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) | 1976-06-18 | 1976-12-18 | 1977-06-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-18 | 1980-12-18 | 1981-06-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-18 | 1984-12-18 | 1985-06-19 | $7700.00 | Window Closed / Lapsed |