US3597314A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of improving the drainage of cellulose fiber suspensions with polymers of n-vinyl-n-methyl-formamide
Assignee: Hoechst AG
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Filing: 1968-11-27
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Granted: 1971-08-03
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Expires: 1988-11-27
Abstract
Abstract DEWATERING OF AQUEOUS CELLULOSE FIBER SUSPENSION IN THE FORMATION OF PAPER IS IMPROVED BY ADDING TO THE SUSPENSION FROM 0.05 TO 4% OF A WATER SOLUBLE POLYMER CONSISTING ESSENTIALLY OF UNITS DERIVED FROM N-VINYL-N-METHYLFORMAMIDE, SUCH AS N-VINYL-N-METHYL FORMAMIDE, HAVING 60-100% OF THE FORMIC ACID RADICALS OF THE POLYMER SPLIT OFF BY ACID HYDROLYSIS.
Inventors
- 👤 Karlheinz Laube
- 👤 Dieter Ulmschneider
- 👤 Ehrenfried Nischwith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 19:30
CPC Classifications
D; D21; D21H; D21H17/00; D21H17/20; D21H17/33; D21H17/34; D21H17/41; D21H17/44; D21H17/45
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) | 1974-08-02 | 1975-02-01 | 1975-08-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-02 | 1979-02-01 | 1979-08-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-02 | 1983-02-01 | 1983-08-03 | $7700.00 | Window Closed / Lapsed |