Patent US3576791A successfully refreshed from Google Patents.
US3576791A
Expired / Lapsed
US
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Polysulfones
Assignee: Shell USA Inc
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Filing: 1969-07-10
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Granted: 1971-04-27
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Expires: 1989-07-10
Abstract
Abstract REACTION PRODUCTS ACCORDING TO THIS INVENTION ARE POLYSULFONES OF DIOLEFINS AND SO2 IN WHICH THE MOLAR RATIO OF DIOLEFIN-DERIVED MONOMER UNITS TO -SO2- IS GRATER THAN 1.2:2, AND THEIR HYDROGENATION PRODUCTS. POLYSULFONES OF THIS INVENTION EXHIBIT GREATER STABILITY IN SOLVENTS SUCH AS PHENOLS, COMPARED TO POLYSULFONES CONTAINING HYDROCARBON-DERIVED AND -SO2- UNITS IN 1:1 RATIO IN A PERFECTLY ALTERNATING STRUCTURE.
Inventors
- 👤 Howard V Holler
- 👤 Edward A Youngman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 11:59
CPC Classifications
C; C08; C08G; C08G75/00; C08G75/20; C08G75/205; C08G75/22
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) | 1974-04-26 | 1974-10-26 | 1975-04-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-04-26 | 1978-10-26 | 1979-04-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-04-26 | 1982-10-26 | 1983-04-27 | $7700.00 | Window Closed / Lapsed |