US4152197A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preparing high-yield cellulose pulps by vapor phase pulping an unpulped portion of lignocellulosic material and a partially chemically pulped portion
Assignee: Mo och Domsjo AB
•
Filing: 1977-05-02
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Granted: 1979-05-01
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Expires: 1997-05-02
Abstract
Abstract Process and apparatus are provided for the preparation of improved high-yield cellulose pulps, such as semichemical, chemimechanical, thermomechanical, and mechanical pulps, which comprises mechanically defibrating a mixture of particulate lignocellulosic materials which have been partially pulped and softened to different extents. Part of the raw lignocellulosic material is particulate form is washed, moistened with steam, impregnated with pulping chemicals and pulped to a yield of from about 65 to about 92%. Another part is treated in similar manner but either not pulped at all or, if pulped, pulped to a lesser extent. The two parts are mixed without intermediate washing, after which the mixture is subjected to a vapor phase pulping by heating to a temperature within the range from about 90 to about 200° C. under pressure to obtain softening of the lignin, and delignification, after which the resulting product is mechanically defibrated to form cellulose pulp.
Inventors
- 👤 Jonas A. I. Lindahl
- 👤 Lars G. Rudstrom
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 05:44
CPC Classifications
D; D21; D21C; D21C3/00; D21C3/22
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
196 words
A process for preparing cellulose pulps having a yield within the range from about 70 to about 93% from raw lignocellulosic material which comprises subjecting to a vapor phase pulping by heating under a superatmospheric pressure within the range from about 1 to about 11 atmospheres at a temperature within the range from about 90 to about 200° C. a mixture of at least two separate portions of particulate lignocellulosic material, of which at least one portion is unpulped and at least one portion is separately partially chemically pulped to a yield within the range from about 65 to about 92%; and then directly subjecting the heat-treated incompletely pulped mixture, of which said partially chemically pulped portion is softer than the other portion, to a mechanical defibration sufficient to convert the raw lignocellulosic material to a high yield cellulose pulp having a yield within the range from about 70% to about 93%, the heating under pressure being so effected that the final yield of the partially pulped portion is within the range from about 60 to about 88%, and the final yield of the unpulped portion is within the range from about 85 to about 100%.
Claim 2
Dependent Claim
196 words
A process for preparing cellulose pulps having a yield within the range from about 70 to about 93% from raw lignocellulosic material which comprises subjecting to a vapor phase pulping by heating under a superatmospheric pressure within the range from about 1 to about 11 atmospheres at a temperature within the range from about 90 to about 200° C. a mixture of at least two separate portions of particulate lignocellulosic material, of which at least one portion is unpulped and at least one portion is separately partially chemically pulped to a yield within the range from about 65 to about 92%; and then directly subjecting the heat-treated incompletely pulped mixture, of which said partially chemically pulped portion is softer than the other portion, to a mechanical defibration sufficient to convert the raw lignocellulosic material to a high yield cellulose pulp having a yield within the range from about 70% to about 93%, the heating under pressure being so effected that the final yield of the partially pulped portion is within the range from about 60 to about 88%, and the final yield of the unpulped portion is within the range from about 85 to about 100%.
Claim 3
Dependent Claim
23 words
A process according to claim 1, in which the unpulped and the partially pulped portions are of the same type of lignocellulosic material.
Claim 4
Dependent Claim
22 words
A process according to claim 1, in which the unpulped and the partially pulped portions are of different types of lignocellulosic material.
Claim 5
Dependent Claim
48 words
A process according to claim 1, in which the partially pulped portion of raw lignocellulosic material in particulate form is washed, moistened with steam, impregnated with pulping chemicals, and then partially pulped and mixed without intermediate washing with the unpulped portion of lignocellulosic material which has been washed.
Claim 6
Dependent Claim
22 words
A process according to claim 4, in which the unpulped and partially pulped portions are of the same type of lignocellulosic material.
Claim 7
Dependent Claim
21 words
A process according to claim 4, in which the unpulped and partially pulped portions are of different types of lignocellulosic material.
Claim 8
Dependent Claim
78 words
A process according to claim 4, in which the unpulped portion of lignocellulosic material prior to mixing with the partially pulped portion is impregnated with pulping chemicals subsequent to being washed and moistened with steam at a temperature within the range from about 90° to about 110° C. for at least five minutes, so that a partial pulping and softening of the unpulped portion is obtained after mixing with the partially pulped portion during the heating under pressure.
Claim 9
Dependent Claim
22 words
A process according to claim 4, in which the heating under pressure is effected for from about 1 to about 20 minutes.
Claim 10
Dependent Claim
29 words
A process according to claim 4 in which, prior to the second pulping of the partially pulped portion of lignocellulosic material, the excess pulping chemicals are removed and recycled.
Claim 11
Dependent Claim
45 words
A process according to claim 4, in which the partial pulping of the partially pulped portion is effected with pulping chemicals selected from at least one of the groups consisting of chemicals for sulfate pulping; chemicals for sulfite pulping, and chemicals for oxygen gas/alkali pulping.
Claim 12
Dependent Claim
16 words
A process according to claim 1, in which the mechanically defibrated mixture is subjected to bleaching.
Claim 13
Dependent Claim
16 words
A process according to claim 11, in which the bleaching is effected with lignin-preserving bleaching agents.
Claim 14
Dependent Claim
17 words
A process according to claim 1, in which two of the portions of lignocellulosic material are softwood.
Claim 15
Dependent Claim
17 words
A process according to claim 1, in which two of the portions of lignocellulosic material are hardwood.
Claim 16
Dependent Claim
21 words
A process according to claim 1, in which one of the portions of lignocellulosic material is hardwood, and another is softwood.
Claim 17
Dependent Claim
49 words
A process according to claim 1, in which the lignocellulosic material is in the form of chips having a size within the range from about 15 to 30 mm by from about 20 to 40 mm, with a thickness within the range from about 0.5 to about 10 mm.
Claim 18
Dependent Claim
19 words
A process according to claim 1 in which the mechanically defibrated mixture is subjected to an additional mechanical defibration.
Claim 19
Dependent Claim
16 words
A process according to claim 17 in which the mechanically defibrated mixture is subjected to bleaching.
Claim 20
Dependent Claim
22 words
A process according to claim 1, which comprises heating at a pressure within the range from about 1.5 to about 9 atmospheres.
Claim 21
Dependent Claim
52 words
A process according to claim 1, in which the partially pulped portion of raw lignocellulosic material in particulate form is washed, moistened with steam, impregnated with pulping chemicals, and then partially pulped and mixed without intermediate washing with the unpulped portion of lignocellulosic material which has been washed and moistened with steam.
Claim 22
Dependent Claim
22 words
A process according to claim 20, in which the unpulped and partially pulped portions are of the same type of lignocellulosic material.
Claim 23
Dependent Claim
21 words
A process according to claim 20, in which the unpulped and partially pulped portions are of different types of lignocellulosic material.
Claim 24
Dependent Claim
78 words
A process according to claim 20, in which the unpulped portion of lignocellulosic material prior to mixing with the partially pulped portion is impregnated with pulping chemicals subsequent to being washed and moistened with steam at a temperature within the range from about 90° to about 110° C. for at least five minutes, so that a partial pulping and softening of the unpulped portion is obtained after mixing with the partially pulped portion during the heating under pressure.
Claim 25
Dependent Claim
22 words
A process according to claim 20, in which the heating under pressure is effected for from about 1 to about 20 minutes.
Claim 26
Dependent Claim
29 words
A process according to claim 20, in which prior to the second pulping of the partially pulped portion of lignocellulosic material, the excess pulping chemicals are removed and recycled.
Claim 27
Dependent Claim
45 words
A process according to claim 20, in which the partial pulping of the partially pulped portion is effected with pulping chemicals selected from at least one of the groups consisting of chemicals for sulfate pulping; chemicals for sulfite pulping, and chemicals for oxygen gas/alkali pulping.
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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) | 1982-04-30 | 1982-10-30 | 1983-05-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-04-30 | 1986-10-30 | 1987-05-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-04-30 | 1990-10-30 | 1991-05-01 | $7700.00 | Window Closed / Lapsed |