US3617432A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Delignifying lignocellulose with an incomplete soda cook followed by gaseous bleaching
Assignee: FPInnovations
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Filing: 1968-10-15
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Granted: 1971-11-02
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Expires: 1988-10-15
Abstract
Abstract A process is provided for the preparation of pulp from lignocellulosic material. It involves two essential steps, namely: firstly, carrying out a modified conventional sodacooking step in which the cooking conditions are deliberately selected to be such that the yield is significantly higher than that normally corresponding to a bleachable pulp and in which the material is simultaneously at least partially defiberized; and secondly, either partially or completely delignifying the pulp by subjecting the pulp so produced to a gaseous bleaching treatment while it is in defiberized form.
Inventors
- 👤 David W Clayton
- 👤 Raimbault M A T De Montigny
- 👤 Norman Liebergott
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 20:55
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/10; D21C9/12; D21C9/14; D21C9/142; D21C9/1026
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
25 words
limiting the residence time within that first zone to such an extent that less than the potential amount of chlorine is acquired by the fluff;
Claim 2
Dependent Claim
36 words
The process of claim 1 including the positive additional step of defiberizing the cooked lignified vegetable matter after it has been subjected to said modified cooking step but before it has been subjected to step (B).
Claim 3
Dependent Claim
12 words
The process of claim 2 wherein the alkaline solution is soda liquor.
Claim 4
Dependent Claim
47 words
continuously passing the fluff including the chlorine which has been acquired by the fluff through a second zone of an essentially chlorine-free atmosphere under such retention time conditions as to permit the amount of said chlorine to react with said fluff; and effecting the further steps of:
Claim 5
Dependent Claim
5 words
washing the pretreated pulp; and
Claim 6
Dependent Claim
20 words
The process of claim 2 wherein the lignified vegetable material is softwood and the yield is at least 48 percent.
Claim 7
Dependent Claim
11 words
The process of claim 4 wherein the softwood is mechanically defiberized.
Claim 8
Dependent Claim
9 words
further treating the washed pulp with an alkaline reagent.
Claim 9
Dependent Claim
13 words
The process of claim 2 wherein step (B) comprises pretreating the pulp by
Claim 10
Dependent Claim
80 words
The process of claim 6 wherein the treatment with the alkaline reagent comprises: i. finely dividing the pretreated pulp into fiber aggregates at a moisture content of about 40-85 percent; ii. preheating the fiber aggregates to a temperature of about 60*-100* C.; iii. exposing the preheated fiber aggregates to an atmosphere comprising gaseous ammonia for a reaction time of about 1 to about 30 minutes; and iv. maintaining the temperature during the reaction time within the range of 60*-100* C.
Claim 11
Dependent Claim
19 words
The process of claim 6 wherein the residence time in the first zone is 20 seconds to 5 minutes.
Claim 12
Dependent Claim
18 words
The process of claim 6 wherein the fluff acquires from 50-85 percent of the potential amount of chlorine.
Claim 13
Dependent Claim
16 words
The process of claim 6 wherein the residence time in the second zone is 1-15 minutes.
Claim 14
Dependent Claim
31 words
The process of claim 8 wherein the fluff acquires from 50-85 percent of the potential amount of chlorine and further wherein the residence time in the second zone is 1-15 minutes.
Claim 15
Dependent Claim
94 words
The process of claim 2 wherein step (C) comprises the step of pretreating the defiberized pulp in the form of a fluff which is at a moisture content of 80-40 percent with chlorine dioxide diluted to less than 100 mm. mercury partial pressure with a nonreactive gas, at a retention time of the order of 20 seconds to 60 minutes and at a temperature which varies between 15* C. and 100* C.; and effecting the further steps of (2) washing the pretreated pulp and (3) further treating the washed pulp with an alkaline reagent.
Claim 16
Dependent Claim
80 words
The process of claim 12 wherein the treatment with the alkaline reagent comprises: i. finely dividing the pretreated pulp into fiber aggregates at a moisture content of about 40-85 percent; ii. preheating the fiber aggregates to a temperature of about 60*-100* C.; iii. exposing the preheated fiber aggregates to an atmosphere comprising gaseous ammonia for a reaction time of about 1 to about 30 minutes; and iv. maintaining the temperature during the reaction time within the range of 60*-100* C.
Claim 17
Dependent Claim
17 words
The process of claim 12 wherein the nonreactive gas is air, nitrogen, steam, or an inert gas.
Claim 18
Dependent Claim
18 words
The process of claim 7 wherein the ammonia is diluted with steam, air, nitrogen, or other inert gas.
Claim 19
Dependent Claim
18 words
The process of claim 12 wherein the ammonia is diluted with steam, air, nitrogen, or other inert gas.
Claim 20
Dependent Claim
96 words
The process of claim 7 including the further steps of: I. adjusting the moisture content of the fibers to a level of from 60 to 70 percent; II. exposing the fiber aggregate to chlorine dioxide gas diluted with an inert solvent where the partial pressure of chlorine dioxide is 100 mm. of mercury or less, for a period of about 5 to about 30 minutes at a temperature from about 65 to about 100* C.; and III. controlling the pH of the mixture so that final pH is in the range of from 3.5 to 6.5.
Claim 21
Dependent Claim
95 words
The process of claim 12 including the fUrther steps of: I. adjusting the moisture content of the fibers to a level of from 60 to 70 percent; II. exposing the fiber aggregate to chlorine dioxide gas diluted with an inert solvent where the partial pressure of chlorine dioxide is 100 mm. of mercury or less, for a period of about 5 to about 30 minutes at a temperature from about 65 to about 100* C.; and III. controlling the pH of the mixture so that final pH is in the range from 3.5 to 6.5.
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) | 1974-11-01 | 1975-05-03 | 1975-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-01 | 1979-05-03 | 1979-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-01 | 1983-05-03 | 1983-11-02 | $7700.00 | Window Closed / Lapsed |