US2779656A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Bleaching of kraft pulp
Assignee: EIDP Inc
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Filing: 1953-06-16
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Granted: 1957-01-29
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Expires: 1973-06-16
Abstract
No abstract record available.
Inventors
- 👤 Francis L Fennell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 02:20
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/10; D21C9/1026
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
106 words
IN A MULTI-STAGE PROCESS FOR BLEACHING KRAFT PULP IN WHICH ACTIVE CHLORINE AGENTS ARE EMPLOYED IN A SERIES OF TREATMENTS INCLUDING A FINAL HYPOCHLORITE BLEACHING STAGE AND WHICH INCLUDES AN INTERMEDIATE CAUSTIC EXTRACTION TREATMENT USING AN ALKALINE EXTRACTING LIQUOR CONTAINING A PEROXYGEN COMPOUND PRIOR TO SAID FINAL HYPOCHLORITE BLEACHINGS STAGE, THE IMPROVEMENT COMPRISING EMPLOYING IN SAID EXTRACTION TREATMENT A LIQUOR HAVING A TOTAL ALKALI CONTENT OF 1.0 TO 2.2% CALCULATED AS NAOH AND BASED UPON THE DRY WEIGHT OF THE PULP, AT LEAST 60% OF SAID TOTAL ALKALINITY BEING DERIVED FROM A MATERIAL OF THE GROUP CONSISTING OF THE ALKALI METAL HYROXIDES AND ALKALI METAL PEROXIDES.
Claim 2
Dependent Claim
106 words
IN A MULTI-STAGE PROCESS FOR BLEACHING KRAFT PULP IN WHICH ACTIVE CHLORINE AGENTS ARE EMPLOYED IN A SERIES OF TREATMENTS INCLUDING A FINAL HYPOCHLORITE BLEACHING STAGE AND WHICH INCLUDES AN INTERMEDIATE CAUSTIC EXTRACTION TREATMENT USING AN ALKALINE EXTRACTING LIQUOR CONTAINING A PEROXYGEN COMPOUND PRIOR TO SAID FINAL HYPOCHLORITE BLEACHINGS STAGE, THE IMPROVEMENT COMPRISING EMPLOYING IN SAID EXTRACTION TREATMENT A LIQUOR HAVING A TOTAL ALKALI CONTENT OF 1.0 TO 2.2% CALCULATED AS NAOH AND BASED UPON THE DRY WEIGHT OF THE PULP, AT LEAST 60% OF SAID TOTAL ALKALINITY BEING DERIVED FROM A MATERIAL OF THE GROUP CONSISTING OF THE ALKALI METAL HYROXIDES AND ALKALI METAL PEROXIDES.
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) | 1960-01-29 | 1960-07-30 | 1961-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1964-01-29 | 1964-07-30 | 1965-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1968-01-29 | 1968-07-30 | 1969-01-29 | $7700.00 | Window Closed / Lapsed |