Patent US2862784A successfully refreshed from Google Patents.
US2862784A
Expired / Lapsed
US
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Oxidative-reductive multi-stage bleaching of ground wood pulp
Assignee: Virginia Smelting Co
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Filing: 1955-03-04
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Granted: 1958-12-02
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Expires: 1975-03-04
Abstract
No abstract record available.
Inventors
- 👤 Mearl A Kise
- 👤 Robert W Barton
- 👤 Robert H Ingwall
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 20:57
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/10; D21C9/1057
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
165 words
A PROCESS OF BLEACHING GROUND WOOD PULP IN THE FORM OF AN AQUEOUS SUSPENSION CONTAINING APPROXIMATELY 11 PERCENT BY WEIGHT OF PULP WHICH COMPRISES CONTACTING AT A TEMEPRATURE OF FROM 90 TO 125*F. SAID PULP WITH AN OXIDIZING BLEACH MEDIUM CONTAINING FROM 1 TO 3 PERCENT BY WEIGHT OF SODIUM PEROXIDE AND ABOUT 5 PERCENT BY WEIGHT OF SODIUM SILICATE, CALCULATED ON THE DRY WEIGHT OF THE WOOD PULP IN SAID SUSPENSION, IN ALKALINE SOLUTION FOR A TIME SUFFICIENT TO EXPAND APPROXIMATELY 98 PERCENT OF THE OXIDIZING MATERIAL PRESENT IN THE SOLUTION, ACIDIFYING SAID SUSPENSION WITH SULFUR DIOXIDE TO APPROXIMATE NEUTRALITY AND THEREAFTER SUBJECTING SAID PULP AT A TEMPERATURE OF FROM 90* TO 190*F. TO THE ACTION OF A REDUCING BLEACH MEDIUM CONTAINING ABOUT 1 PERCENT BY WEIGHT OF SODIUM HYDROSULFITE AND FROM 0.1 TO 1 PERCENT BY WEIGHT OF SODIUM TRIPOLYPHOSPHATE, CALCULATED ON THE DRY WEIGHT OF THE WOOD PULP IN SAID SUSPENSION, IN A SOLUTION OF A PH RANGING FROM 8.5 TO 5.0.
Claim 2
Dependent Claim
165 words
A PROCESS OF BLEACHING GROUND WOOD PULP IN THE FORM OF AN AQUEOUS SUSPENSION CONTAINING APPROXIMATELY 11 PERCENT BY WEIGHT OF PULP WHICH COMPRISES CONTACTING AT A TEMEPRATURE OF FROM 90 TO 125*F. SAID PULP WITH AN OXIDIZING BLEACH MEDIUM CONTAINING FROM 1 TO 3 PERCENT BY WEIGHT OF SODIUM PEROXIDE AND ABOUT 5 PERCENT BY WEIGHT OF SODIUM SILICATE, CALCULATED ON THE DRY WEIGHT OF THE WOOD PULP IN SAID SUSPENSION, IN ALKALINE SOLUTION FOR A TIME SUFFICIENT TO EXPAND APPROXIMATELY 98 PERCENT OF THE OXIDIZING MATERIAL PRESENT IN THE SOLUTION, ACIDIFYING SAID SUSPENSION WITH SULFUR DIOXIDE TO APPROXIMATE NEUTRALITY AND THEREAFTER SUBJECTING SAID PULP AT A TEMPERATURE OF FROM 90* TO 190*F. TO THE ACTION OF A REDUCING BLEACH MEDIUM CONTAINING ABOUT 1 PERCENT BY WEIGHT OF SODIUM HYDROSULFITE AND FROM 0.1 TO 1 PERCENT BY WEIGHT OF SODIUM TRIPOLYPHOSPHATE, CALCULATED ON THE DRY WEIGHT OF THE WOOD PULP IN SAID SUSPENSION, IN A SOLUTION OF A PH RANGING FROM 8.5 TO 5.0.
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) | 1961-12-01 | 1962-06-02 | 1962-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1965-12-01 | 1966-06-02 | 1966-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1969-12-01 | 1970-06-02 | 1970-12-02 | $7700.00 | Window Closed / Lapsed |