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US4384921A
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US
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Alkaline sulfite pulping process with sodium aluminate and anthraquinone
Assignee: Ahlstrom Corp
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Filing: 1981-05-04
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Granted: 1983-05-24
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Expires: 2001-05-04
Abstract
Abstract An alkaline sulfite pulping process in which the lignocellulosic material is cooked in a solution containing sodium sulfite is provided. Sodium aluminate is used as a buffering agent. As a result of this, the stability of the pH of the cook and the properties of the pulp are improved. The amount of sodium aluminate as NaOH is from 2% to 8% based on the dry weight of the chips. The pulping process is carried out with the addition of a small dosage of anthraquinone, to produce chemically defibered pulps.
Inventors
- 👤 Soile H. Pihlajamaki
- 👤 Nils-Erik Virkola
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 05:01
CPC Classifications
D; D21; D21C; D21C3/00; D21C3/22; D21C3/222
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
83 words
An alkaline pulping process for chips of lignocellulosic material which comprises cooking said lignocellulosic material at 140°-210° C. for 250 minutes with a solution containing sodium sulfite at a pH of 10-13.5 in the presence of sodium aluminate as a buffering agent in the amount of 2% to 8% as NaOH based on the dry weight of the chips of lignocellulosic material, and 0.2% anthraquinone, wherein said cooking is carried out to produce a pulp of high viscosity, high strength and good yield.
Claim 2
Dependent Claim
83 words
An alkaline pulping process for chips of lignocellulosic material which comprises cooking said lignocellulosic material at 140°-210° C. for 250 minutes with a solution containing sodium sulfite at a pH of 10-13.5 in the presence of sodium aluminate as a buffering agent in the amount of 2% to 8% as NaOH based on the dry weight of the chips of lignocellulosic material, and 0.2% anthraquinone, wherein said cooking is carried out to produce a pulp of high viscosity, high strength and good yield.
Claim 3
Dependent Claim
23 words
A process according to claim 1, wherein the amount of sodium aluminate as NaOH is about 4% of the dry weight of chips.
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) | 1986-05-23 | 1986-11-22 | 1987-05-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-05-23 | 1990-11-22 | 1991-05-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-05-23 | 1994-11-22 | 1995-05-24 | $7700.00 | Window Closed / Lapsed |