US3645840A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for peroxide bleaching of pulp
Assignee: Atlantic Richfield Co
•
Filing: 1971-01-19
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Granted: 1972-02-29
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Expires: 1991-01-19
Abstract
Abstract Bleaching of ligneous cellulosic materials such as paper pulp by treating the pulp with a combination of tertiary butyl hydroperoxide and hydrogen peroxide as the bleaching agent.
Inventors
- 👤 Robert M Lincoln
- 👤 Joseph A Meyers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 03:09
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/10; D21C9/16; D21C9/163
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
53 words
The method according to claim 1, wherein the cellulosic fibers which have been treated with hydrogen peroxide, tertiary butyl hydroperoxide and buffer are treated with a sulfite compound said sulfite compound ranging in an amount from about 1 weight percent to 6 weight percent based on the weight of the dry cellulosic fibers.
Claim 2
Dependent Claim
13 words
The method according to claim 1, wherein the said buffer is sodium carbonate.
Claim 3
Dependent Claim
12 words
The method according to claim 1, wherein said buffer is sodium bicarbonate.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-02-28 | 1975-08-30 | 1976-02-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-28 | 1979-08-30 | 1980-02-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-28 | 1983-08-30 | 1984-02-29 | $7700.00 | Window Closed / Lapsed |