US4036681A
Expired / Lapsed
US
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Delignification of lignocellulosic material with an alkaline pulping liquor containing a Diels Alder adduct of benzoquinone or naphthoquinone
Assignee: PPG Architectural Coatings Canada Inc
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Filing: 1976-12-14
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Granted: 1977-07-19
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Expires: 1996-12-14
Abstract
Abstract Delignification of lignocellulosic material, such as wood, straw or bagasse, by treatment with an alkaline pulping liquor containing a diketo hydroanthracene selected from the unsubstituted and lower alkyl substituted Diels Alder adducts of benzoquinone and naphthoquinone.
Inventors
- 👤 Harry Hutchinson Holton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:07
CPC Classifications
D; D21; D21C; D21C3/00; D21C3/003
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
114 words
A process for the delignification of lignocellulosic material comprising the steps of 1. treating the lignocellulosic material in a closed reaction vessel with an alkaline pulping liquor containing from 0.001% to 10.0% by weight, based on the lignocellulosic material, or a diketo hydroanthracene selected from the group consisting of the unsubstituted and lower alkyl substituted Diels Alder adducts of naphthoquinone and benzoquinone, the treatment taking place at a temperature in the range of from 150° C. to 200° C. for a period of 0.5 to 480 minutes, and 2. displacing the pulping liquor from the lignocellulosic material with water or an aqueous liquor inert to the lignocellulosic material to obtain a delignified lignocellulosic material.
Claim 2
Dependent Claim
114 words
A process for the delignification of lignocellulosic material comprising the steps of 1. treating the lignocellulosic material in a closed reaction vessel with an alkaline pulping liquor containing from 0.001% to 10.0% by weight, based on the lignocellulosic material, or a diketo hydroanthracene selected from the group consisting of the unsubstituted and lower alkyl substituted Diels Alder adducts of naphthoquinone and benzoquinone, the treatment taking place at a temperature in the range of from 150° C. to 200° C. for a period of 0.5 to 480 minutes, and 2. displacing the pulping liquor from the lignocellulosic material with water or an aqueous liquor inert to the lignocellulosic material to obtain a delignified lignocellulosic material.
Claim 3
Dependent Claim
40 words
A process as claimed in claim 1 wherein the lower alkyl substituted Diels Alder adducts are adducts substituted with 1 to 4 alkyl groups which may be the same or different and may each contain 1 to 4 carbon atoms.
Claim 4
Dependent Claim
31 words
A process as claimed in claim 1 wherein the diketo hydroanthracene is selected from the group consisting of 1,4,4a,9a-tetrahydro-9,10-diketo anthracene, 2-ethyl-1,4,4a,9a-tetrahydro-9,10-diketo anthracene, 2,3-dimethyl-1,4,4a,9a-tetrahydro-9,10-diketo anthracene, 1,3-dimethyl-1,4,4a,9a-tetrahydro-9,10-diketo anthracene, 1,4,4a,5,8,8a,9a,10a-octahydro-9,10-diketo anthracene and 2,3,6,7-tetramethyl-1,4,4a,5,8,8a,9a,10a-octahydro-9,10-diketo anthracene.
Claim 5
Dependent Claim
28 words
A process as claimed in claim 1 wherein the alkaline pulping liquor contains from 0.01% to 1.0% by weight based on the lignocellulosic material, of the diketo hydroanthracene.
Claim 6
Dependent Claim
16 words
A process as claimed in claim 1 wherein the alkaline pulping liquor is a soda liquor.
Claim 7
Dependent Claim
16 words
A process as claimed in claim 1 wherein the alkaline pulping liquor is a kraft liquor.
Claim 8
Dependent Claim
29 words
A process as claimed in claim 6 wherein the kraft liquor contains from 1.0% to 5.0% by weight (based on weight of lignocellulosic material) of polysulphides expressed as sulphur.
Claim 9
Dependent Claim
125 words
A process as claimed in claim 1 wherein the delignified lignocellulosic material is subjected to the following additional steps: 3. treatment of the delignified lignocellulosic material in aqueous suspension at a consistency of from 2% to 40% by weight for from 0.5 to 60 minutes at from 20° C. to 90° C. with from 2 to 20% by weight of an alkali metal base and 4. treatment of the alkali metal base treated material in an aqueous medium at a consistency of from 3.0% to 40% by weight with oxygen or an oxygen-containing gas for from 0.5 to 120 minutes at a temperature of from 80° C. to 150° C. and a partial pressure of oxygen of from 20 to 200 pounds per square inch.
Claim 10
Dependent Claim
16 words
A process as claimed in claim 8 wherein the oxygen-treated material is subjected to conventional bleaching.
Claim 11
Dependent Claim
17 words
A process as claimed in claim 1 wherein the delignified lignocellulosic material is subjected to conventional bleaching.
References Cited (Backward Citations)
JPS5143403A
Cited
US4012280A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-07-18 | 1981-01-17 | 1981-07-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-07-18 | 1985-01-17 | 1985-07-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-07-18 | 1989-01-17 | 1989-07-19 | $7700.00 | Window Closed / Lapsed |