US3617435A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Treatment of woodpulp with an alkaline solution containing formaldehyde prior to a bisulfite cooking thereof
Assignee: TABERT Inc
•
Filing: 1968-06-03
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Granted: 1971-11-02
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Expires: 1988-06-03
Abstract
Abstract A bisulfite wood-pulping process in which not more than about 2 percent by weight, based on the wood, of formaldehyde in an alkaline solution is used to pretreat the wood prior to the bisulfite cooking.
Inventors
- 👤 John H Kalisch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 18:07
CPC Classifications
D; D21; D21C; D21C1/00; D21C1/06; Y; Y10; Y10S; Y10S162/00; Y10S162/12
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
16 words
The process of claim 1 wherein the alkaline solution is a mixture of hydroxide and carbonate.
Claim 2
Dependent Claim
12 words
A process as in claim 1 wherein the maximum pH is 2.9.
Claim 3
Dependent Claim
13 words
A process as in claim 1 wherein the maximum pH is 3 .
Claim 4
Dependent Claim
33 words
The process of claim 1 wherein the alkaline impregnation is carried out for about 90 minutes at a temperature not exceeding about 50* C. and a pressure of about 100 p.s.i.g. is employed.
Claim 5
Dependent Claim
30 words
A process of claim 1 wherein a short alkaline impregnation of about 2 minutes is carried out at about 200 p.s.i.g. pressure at a temperature not exceeding about 100* C.
Claim 6
Dependent Claim
32 words
The process of claim 1 wherein SO2 is injected in liquid or aqueous form after draining of the impregnation liquor and the cook is carried out in a vapor or trickle phase.
Claim 7
Dependent Claim
15 words
A process as in claim 1 wherein the impregnation pH is not lower than 12.6
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) | 1974-11-01 | 1975-05-03 | 1975-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-01 | 1979-05-03 | 1979-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-01 | 1983-05-03 | 1983-11-02 | $7700.00 | Window Closed / Lapsed |