Patent US2528351A successfully refreshed from Google Patents.
US2528351A
Expired / Lapsed
US
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Alkaline sulfite digestion of hardwood
Assignee: Hardwood By-Products Inc
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Filing: 1950-08-17
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Granted: 1950-10-31
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Expires: 1970-08-17
Abstract
No abstract record available.
Inventors
- 👤 Farber Eduard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 10:21
CPC Classifications
D; D21; D21C; D21C3/00; D21C3/04; D21C3/06
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
81 words
A PROCESS OF PREPARING FOR SUBSEQUENT FIBERIZING TREATMENT PARTICLES OF HARDWOODS HAVING A HEMICELLULOSE CONTENT OF AT LEAST 18% WHICH COMPRISES ESSENTIALLY DIGESTING SAID PARTICLES AT ATMOSPHERIC PRESSURE FOR A PERIOD OF FROM ABOUT ONE TO ABOUT TWO HOURS AT A TEMPERATURE OF FROM ABOUT 55*C. TO ABOUT 75*C. WITH A DILUTE AQUEOUS SOLUTION CONTAINING ESSENTIALLY FROM ABOUT 1% TO ABOUT 4% BY WEIGHT OF AN ALKALI METAL HYROXIDE AND FROM ABOUT 0.4% TO ABOUT 2.5% OF AN ALKALI METAL SULFITE.
Claim 2
Dependent Claim
81 words
A PROCESS OF PREPARING FOR SUBSEQUENT FIBERIZING TREATMENT PARTICLES OF HARDWOODS HAVING A HEMICELLULOSE CONTENT OF AT LEAST 18% WHICH COMPRISES ESSENTIALLY DIGESTING SAID PARTICLES AT ATMOSPHERIC PRESSURE FOR A PERIOD OF FROM ABOUT ONE TO ABOUT TWO HOURS AT A TEMPERATURE OF FROM ABOUT 55*C. TO ABOUT 75*C. WITH A DILUTE AQUEOUS SOLUTION CONTAINING ESSENTIALLY FROM ABOUT 1% TO ABOUT 4% BY WEIGHT OF AN ALKALI METAL HYROXIDE AND FROM ABOUT 0.4% TO ABOUT 2.5% OF AN ALKALI METAL SULFITE.
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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) | 1953-10-30 | 1954-05-01 | 1954-10-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1957-10-30 | 1958-05-01 | 1958-10-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1961-10-30 | 1962-05-01 | 1962-10-31 | $7700.00 | Window Closed / Lapsed |