US3703570A
Expired / Lapsed
US
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Process for the preparation of a semipermeable membrane from polymerized beta-lactam unsubstituted at the nitrogen atom
Assignee: Kalle GmbH and Co KG
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Filing: 1969-12-29
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Granted: 1972-11-21
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Expires: 1989-12-29
Abstract
Abstract THIS INVENTION RELATES TO AN IMPROVEMENT IN THE PROCESS FOR THE PREPARATION OF A SEMIERMEABLE MEMBRANE BY POURING A LAYER OF A SOLUTION OF A PLASTIC ONTO A SUPPORT, EVAPORATING A PORTION OF THE SOLVENT FROM THE LAYER WHEREBY THE LAYERS IS PROVIDED WITH A SURFACE LAYER POOR IN SOLVENT, AND REMOVING THE REMAINING SOLVENT FROM THE LAYER BY MEANS OF A LIQUID WHICH IS MISCIBLE WITH THE SOLVENT BUT DOES NOT DISSOLVE THE PLASTIC, THE IMPROVEMENT COMPRISNG EMPLOYING AS THE PLASTIC AT LEAST ONE POLYAMIDE WHICH IS A POLYMERIZED B-LACTAM UNSUBSTITUTED AT THE NITROGEN ATOM.
Inventors
- 👤 Walter Busch
- 👤 Franz Schwarzer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 10:05
CPC Classifications
B; B01; B01D; B01D71/00; B01D71/06; B01D71/56; C; C08; C08J; C08J9/00; C08J9/28; C08J2201/00; C08J2201/04; C08J2201/054; C08J2201/0542; C08J2201/0544
Claims Analysis
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References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-11-21 | 1976-05-22 | 1976-11-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-11-21 | 1980-05-22 | 1980-11-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-11-21 | 1984-05-22 | 1984-11-21 | $7700.00 | Window Closed / Lapsed |