US3909345A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of treatment of wood pulp for greater efficiency in wood utilization
Assignee: BASF Corp
•
Filing: 1972-12-14
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Granted: 1975-09-30
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Expires: 1992-12-14
Abstract
Abstract The addition of certain surfactant polyoxyethylene polyoxypropylene block copolymers in the sulfate pulping process results in increased yields of pulp.
Inventors
- 👤 Edward T Parker
- 👤 Lester G Lundsted
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 06:46
CPC Classifications
D; D21; D21C; D21C3/00; D21C3/22; D21C3/222
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
60 words
IN A PROCESS FOR THE PREPARATION OF PULPWOOD BY THE DIGESTION OF WOOD CHIPS IN AN AQUEOUS ALKALINE LIQUOR IN WHICH THE TOTAL ACTIVE ALKALI CONSISTS SUBSTANTILLY OF SODIUM SULFIDE AND SODIUM HYDROXIDE AT A MAXIMUM TEMPERATURE OF 400*F., THE IMPROVEMENT WHICH COMPRISES CARRYING OUT THE DIGESTION IN THE PRESENCE OF A DIGESTER ADDITIVE WHOSE STRUCTURE CORRESPONDS TO THE FORMULA
Claim 2
Dependent Claim
60 words
IN A PROCESS FOR THE PREPARATION OF PULPWOOD BY THE DIGESTION OF WOOD CHIPS IN AN AQUEOUS ALKALINE LIQUOR IN WHICH THE TOTAL ACTIVE ALKALI CONSISTS SUBSTANTILLY OF SODIUM SULFIDE AND SODIUM HYDROXIDE AT A MAXIMUM TEMPERATURE OF 400*F., THE IMPROVEMENT WHICH COMPRISES CARRYING OUT THE DIGESTION IN THE PRESENCE OF A DIGESTER ADDITIVE WHOSE STRUCTURE CORRESPONDS TO THE FORMULA
Claim 3
Dependent Claim
25 words
The process according to claim 1 wherein the total active alkali ranges from about 15 to 22 percent of the oven-dried weight of wood chips.
Claim 4
Dependent Claim
16 words
The process according to claim 1 wherein the liquor-to-wood ratio is from about 3/1 to 5/1.
Claim 5
Dependent Claim
26 words
The process according to claim 1 wherein the concentration of additive ranges from about 0.1 to 0.5 percent of the oven dry weight of wood chips.
Claim 6
Dependent Claim
16 words
The process according to claim 1 wherein the nucleus of the digester additive is ethylene glycol.
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) | 1978-09-29 | 1979-03-31 | 1979-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-29 | 1983-03-31 | 1983-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-29 | 1987-03-31 | 1987-09-30 | $7700.00 | Window Closed / Lapsed |