US4404061A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Bleaching of lignocellulosic materials with monopersulfuric acid or its salts
Assignee: International Paper Co
•
Filing: 1981-08-17
•
Granted: 1983-09-13
•
Expires: 2001-08-17
Abstract
Abstract Treatment of lignocellulosic materials and bleaching of wood pulp with monoperoxysulfate to permit more ready separation of non-cellulosic materials therefrom to produce papermaking and bleached pulps.
Inventors
- 👤 John J. Cael
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 16:16
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/10; D21C9/16
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
86 words
A process wherein wood pulp produced from wood chips in a standard alkaline pulping process is bleached with a bleaching agent containing a persulfate ion selected from the group consisting of monopersulfuric acid and its salts with cations in a pH range of from about 2.0 to about 12.0, said bleaching comprising treating said wood pulp with an equivalent of about 0.5 to 5% KHSO 5 based on oven dry pulp for 0.5 to 3.0 hours at a temperature between about 40° C. to 80° C.
Claim 2
Dependent Claim
86 words
A process wherein wood pulp produced from wood chips in a standard alkaline pulping process is bleached with a bleaching agent containing a persulfate ion selected from the group consisting of monopersulfuric acid and its salts with cations in a pH range of from about 2.0 to about 12.0, said bleaching comprising treating said wood pulp with an equivalent of about 0.5 to 5% KHSO 5 based on oven dry pulp for 0.5 to 3.0 hours at a temperature between about 40° C. to 80° C.
Claim 3
Dependent Claim
19 words
A process as defined in claim 1 wherein the bleaching agent containing persulfate ion is supplied by potassium peroxydisulfate.
References Cited (Backward Citations)
US2388592A
Cited
US2353823A
Cited
US2528351A
Cited
US2739034A
Cited
GB847748A
Cited
US3351419A
Cited
US3353902A
Cited
US3467574A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-09-12 | 1987-03-14 | 1987-09-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-09-12 | 1991-03-14 | 1991-09-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-09-12 | 1995-03-14 | 1995-09-13 | $7700.00 | Window Closed / Lapsed |