Patent US3558702A successfully refreshed from Google Patents.
US3558702A
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Method for purifying dimethylformamide recovered from acrylonitrile polymerization processes in the commercial production of polyacrylonitrile fibers and yarns
Assignee: SNIA Viscosa SpA
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Filing: 1967-11-24
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Granted: 1971-01-26
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Expires: 1987-11-24
Abstract
Abstract A METHOD IS DISCLOSED FOR PURIFYING DIMETHYLFORMAMIDE, WHICH HAS BEEN OBTAINED BY RECOVERY THEREOF IN SUBSTANTIALLY NON-AQUEOUS CONDITION FROM A PROCESS FOR SPINNING ACRYLONITRILE POLYMERS AND COPOLYMERS TO PRODUCE FIBERS AND YARNS, COMPRISING TREATING THE IMPURE DIMETHYLFORMAMIDE BY CONTACTING IT WITH TWO DIFFERENT ION-EX CHANGE RESINS WHICH ARE INSOLUBLE IN DIMETHLFORMAMIDE, ONE OF WHICH IS SELECTED FROM THE GROUP OF STRONGLY ACIDIC RESINS CONSISTING OF SULPHONATED STYRENE-DIVINYL BENZENE COPOLYMERS, AND THE OTHER OF WHICH IS SELECTED FROM THE GROUP CONSISTING OF RESINS HAVING QUATERNARY AMMONIUM GROUPS IN HYDROXIDE FORM AND OF RESINS HAVING ALIPHATIC AMINO GROUPS.
Inventors
- 👤 Alberto Pasin
- 👤 Casano Maderno
- 👤 Silvano Borgo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 15:16
CPC Classifications
C; C07; C07C; C07C233/00; Y; Y10; Y10S; Y10S526/00; Y10S526/912
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) | 1974-01-25 | 1974-07-27 | 1975-01-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-25 | 1978-07-27 | 1979-01-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-25 | 1982-07-27 | 1983-01-26 | $7700.00 | Window Closed / Lapsed |