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US4248663A
Expired / Lapsed
US
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Pulping with an alkaline liquor containing a cyclic keto compound and an amino compound
Assignee: FPInnovations
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Filing: 1978-07-05
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Granted: 1981-02-03
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Expires: 1998-07-05
Abstract
Abstract Lignocellulosic materials such as wood, bagasse, straw, reeds, and other plants and crops can be delignified effectively by a soda-type pulping with an alkaline liquor containing small quantities of both ethylenediamine or like amino compound, and a cyclic keto compound, such as anthraquinone. Pulping rates comparable to kraft are achieved and the pulps thereby obtained have excellent physical properties, especially tear strength.
Inventors
- 👤 George J. Kubes
- 👤 James M. MacLeod
- 👤 Bruce I. Fleming
- 👤 Henry I. Bolker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:11
CPC Classifications
D; D21; D21C; D21C3/00; D21C3/22; D21C3/222
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
151 words
In a pulping process for delignifying a lignocellulosic material wherein a cyclic keto compound and a low molecular weight primary diamine which is soluble in the pulping mixture are added to the pulping mixture to improve pulping rates and yields, the improvement which comprises adding to the pulping liquor of an aqueous soda-type alkaline pulping process an amount, between 0.05% and 2% by weight based on the oven-dry weight of the lignocellulosic material, of the primary diamine which is effective in the presence of the cyclic keto compound either for decreasing the amount of the cyclic keto compound required to provide such improved pulping rate and yield or for improving the physical strength properties of the delignified pulp to kraft pulp-like values but which is ineffective in the absence of the cyclic keto compound to significantly affect any of pulping rate, yield and the physical strength properties of the delignified pulp.
Claim 2
Dependent Claim
151 words
In a pulping process for delignifying a lignocellulosic material wherein a cyclic keto compound and a low molecular weight primary diamine which is soluble in the pulping mixture are added to the pulping mixture to improve pulping rates and yields, the improvement which comprises adding to the pulping liquor of an aqueous soda-type alkaline pulping process an amount, between 0.05% and 2% by weight based on the oven-dry weight of the lignocellulosic material, of the primary diamine which is effective in the presence of the cyclic keto compound either for decreasing the amount of the cyclic keto compound required to provide such improved pulping rate and yield or for improving the physical strength properties of the delignified pulp to kraft pulp-like values but which is ineffective in the absence of the cyclic keto compound to significantly affect any of pulping rate, yield and the physical strength properties of the delignified pulp.
Claim 3
Dependent Claim
33 words
A process as claimed in claim 1 wherein the diamine is ethylenediamine and the pulping liquor contains from 0.1% to 2.0% by weight thereof, based on the oven-dry weight of the lignocellulosic material.
Claim 4
Dependent Claim
14 words
A process as claimed in claim 2 wherein the cyclic keto compound is anthraquinone.
Claim 5
Dependent Claim
14 words
A process as claimed in claim 2 wherein the cyclic keto compound is 2-methyl-anthraquinone.
Claim 6
Dependent Claim
33 words
A process as claimed in claim 1 wherein the alkaline pulping liquor contains from 0.01% to 1.0% by weight of the cyclic keto compound, based on the oven-dry weight of the lignocellulosic material.
Claim 7
Dependent Claim
42 words
A process as claimed in claim 5 wherein the cyclic keto compound is anthraquinone and the diamine is ethylenediamine and the pulping liquor contains from 0.1% to 2.0% by weight of the ethylenediamine, based on the oven-dry weight of the lignocellulosic material.
Claim 8
Dependent Claim
50 words
A process as claimed in claim 5 wherein the lignocellulosic material is coniferous wood, the pulping liquor contains from 0.02% to 0.25% by weight of the cyclic ketone and from 0.1% to 2.0% by weight of the diamine, both weights being based on the oven-dry weight of the coniferous wood.
Claim 9
Dependent Claim
19 words
A process as claimed in claim 7 wherein the cyclic keto compound is anthraquinone and the diamine is ethylenediamine.
Claim 10
Dependent Claim
41 words
A process as claimed in claim 7 wherein the alkaline pulping liquor is soda liquor and the combined total of the cyclic keto compound and the diamine is less than 0.5% by weight of the oven-dry weight of the lignocellulosic material.
Claim 11
Dependent Claim
18 words
A process as claimed in claim 1 wherein the delignified cellulosic material is afterward subjected to conventional bleaching.
References Cited (Backward Citations)
JPS5143403A
Cited
US4178861A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-02-03 | 1984-08-04 | 1985-02-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-02-03 | 1988-08-04 | 1989-02-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-02-03 | 1992-08-04 | 1993-02-03 | $7700.00 | Window Closed / Lapsed |