US3795574A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Impregnation of wood with a formaldehyde free alkaline solution of sodium hydroxide at a ph between 12.4 and 13
Assignee: TABERT Inc
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Filing: 1971-07-27
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Granted: 1974-03-05
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Expires: 1991-07-27
Abstract
Abstract A PROCESS INVOLVING IMPREGNATION OF WOOD WITH A FORMALDEHYDE FREE ALKALINE SOLUTION CONTAINING SODIUM HYDROXIDE AT A PH OF FROM ABOUT 12.4 TO ABOUT 13 AND SODIUM SULFITE AT TEMPERATURES BELOW 80*C., FOLLOWED BY DRAINING THE SOLUTION, ADDING SULFUR DIOXIDE AND COOKING THE WOOD IN ACCORDANCE WITH THE BISULFITE PROCESS TO PRODUCE INCREASED YIELDS OF PULP HAVING HIGH UNBLEACHED BRIGHTNESS.
Inventors
- 👤 J Kalisch
- 👤 G Tombler
- 👤 F Hurtubise
- 👤 J Kopanidis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 16:56
CPC Classifications
D; D21; D21C; D21C1/00; D21C1/06; D21C3/00; D21C3/04; D21C3/06
Claims Analysis
Total Claims: 0
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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) | 1977-03-04 | 1977-09-03 | 1978-03-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-04 | 1981-09-03 | 1982-03-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-04 | 1985-09-03 | 1986-03-05 | $7700.00 | Window Closed / Lapsed |