US4385172A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Prevention of hornification of dissolving pulp
Assignee: International Paper Co
•
Filing: 1980-03-24
•
Granted: 1983-05-24
•
Expires: 2000-03-24
Abstract
Abstract Heat treatment of never-dried dissolving pulps prior to drying prevents or retards the hornification and consequent decrease in esterification reactivity which normally occurs on drying of untreated pulps.
Inventors
- 👤 V. M. Yasnovsky
- 👤 Donald M. MacDonald
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 22:10
CPC Classifications
C; C08; C08B; C08B3/00; C08B3/06; C08B1/00; C08B1/02
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
92 words
A process for the preparation of cellulose esters of carboxylic acids which comprises: (a) treating cold alkali post treated dissolving pulp which has never been dried for about 0.5 to about 15 minutes at temperatures of from about 70° C. to about 170° C. at pH of from about 2.0 to about 10.0 and at consistency from about 5% to about 75%; (b) drying the pulp treated in step a above; and (c) esterifying the pulp dried in step b above by treating with a carboxylic acid or a carboxylic acid anhydride.
Claim 2
Dependent Claim
92 words
A process for the preparation of cellulose esters of carboxylic acids which comprises: (a) treating cold alkali post treated dissolving pulp which has never been dried for about 0.5 to about 15 minutes at temperatures of from about 70° C. to about 170° C. at pH of from about 2.0 to about 10.0 and at consistency from about 5% to about 75%; (b) drying the pulp treated in step a above; and (c) esterifying the pulp dried in step b above by treating with a carboxylic acid or a carboxylic acid anhydride.
Claim 3
Dependent Claim
34 words
A process as defined in claim 1 wherein the treatment in step a is for from 1 to 15 minutes at 70° to 110° C., pH 2.0 to 3.5 and 5% to 40% consistency.
Claim 4
Dependent Claim
22 words
A process as defined in claim 2 wherein the treatment is at 95° to 100° C. and at 8% to 12% consistency.
Claim 5
Dependent Claim
35 words
A process as defined in claim 1 wherein the treatment of step a is for from 0.5 to 15 minutes at 150° to 170° C. at pH 5.0 to 10.0 and consistency 5% to 50%.
Claim 6
Dependent Claim
22 words
A process as defined in claim 4 wherein the treatment is for 0.5 to 1.0 minutes and at 30% to 40% consistency.
Claim 7
Dependent Claim
34 words
A process as defined in claim 1 wherein the treatment of step a is for 0.5 to 15 minutes at 150° to 170° C. at pH 5.0 to 10.0 and 60% to 75% consistency.
Claim 8
Dependent Claim
27 words
A process as defined in claims 1, 2, 3, 4, 5, or 6 wherein the esterification of step c is performed with acetic acid and acetic anhydride.
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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) | 1986-05-23 | 1986-11-22 | 1987-05-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-05-23 | 1990-11-22 | 1991-05-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-05-23 | 1994-11-22 | 1995-05-24 | $7700.00 | Window Closed / Lapsed |