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Patent US3653804A successfully refreshed from Google Patents.
US3653804A
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Bleaching of wood pulp with dithionite solution stabilized by zinc compound
Assignee: BASF SE
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Filing: 1967-12-26
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Granted: 1972-04-04
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Expires: 1987-12-26
Abstract
Abstract Use of sparingly soluble zinc compounds for prolonging the stability of wood pulp bleaching solutions containing dithionites.
Inventors
- 👤 Alfons Janson
- 👤 Franz Poschmann
- 👤 Georg Wittmann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 23:26
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/10; D21C9/1084; D21C9/1089; D06; D06L; D06L4/00; D06L4/30
Claims Analysis
Total Claims: 1
Claim 1
Independent Claim
26 words
In a process as claimed in claim 1, the step of adding the zinc compound to the sodium dithionite prior to addition to the bleaching mixture.
References Cited (Backward Citations)
US1710310A
Cited
US1810665A
Cited
GB492589A
Cited
US2071307A
Cited
US2707144A
Cited
US3207694A
Cited
US3287276A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-04-04 | 1975-10-04 | 1976-04-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-04 | 1979-10-04 | 1980-04-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-04 | 1983-10-04 | 1984-04-04 | $7700.00 | Window Closed / Lapsed |