Patent US4094735A successfully refreshed from Google Patents.
US4094735A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of pulping with sulfite liquor containing formic acid esters
Assignee: Kopparfors AB
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Filing: 1977-01-17
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Granted: 1978-06-13
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Expires: 1997-01-17
Abstract
Abstract In the sulfite pulping, the yield of pulp is increased, if at least one of a selected group of formic acid esters is added to the cooking liquid before the impregnation of the wood.
Inventors
- 👤 Sigbjorn P. H. E. Holgersson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 07:19
CPC Classifications
D; D21; D21C; D21C3/00; D21C3/22; D21C3/222
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
108 words
In the method of producing wood pulp by cooking wood in a sulfite cooking liquid, the improvement comprising adding to said sulfite cooking liquid, prior to bringing it into contact with the wood, at least one formic acid ester having the formula ##STR3## where R is a hexyl group or an unsubstituted or methyl-substituted norbornyl group, in an amount of from 0.02 to 71 moles of ester per ton of absolutely dry wood and from 0 to 25% by weight of formic acid based on the weight of the added ester and cooking the wood with said cooking liquid to produce a pulp of increased yield and strength.
Claim 2
Dependent Claim
108 words
In the method of producing wood pulp by cooking wood in a sulfite cooking liquid, the improvement comprising adding to said sulfite cooking liquid, prior to bringing it into contact with the wood, at least one formic acid ester having the formula ##STR3## where R is a hexyl group or an unsubstituted or methyl-substituted norbornyl group, in an amount of from 0.02 to 71 moles of ester per ton of absolutely dry wood and from 0 to 25% by weight of formic acid based on the weight of the added ester and cooking the wood with said cooking liquid to produce a pulp of increased yield and strength.
Claim 3
Dependent Claim
22 words
The method of claim 1, wherein the ester is added in the amount of 0.1 mole per ton of absolutely dry wood.
Claim 4
Dependent Claim
27 words
Th method of claim 1, wherein the ester is dispersed in water by means of a non-ionic dispersing agent prior to addition to the sulfite cooking liquid.
References Cited (Backward Citations)
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Cited
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US2645633A
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US2743179A
Cited
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Cited
US3560331A
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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) | 1981-06-12 | 1981-12-12 | 1982-06-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-06-12 | 1985-12-12 | 1986-06-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-06-12 | 1989-12-12 | 1990-06-13 | $7700.00 | Window Closed / Lapsed |