US3634381A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Degradation of high molecular weight polyisobutylene in extruders
Assignee: BASF SE
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Filing: 1969-04-23
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Granted: 1972-01-11
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Expires: 1989-04-23
Abstract
Abstract A PROCESS AND APPARATUS FOR THE DEGRADATION OF HIGH MOLECULAR WE MOLECULAR WEIGHT POLYISOBUTYLENE IN A SCREW EXTRUDER PROVIDED WITH A SCREW SPINDLE BY THE ACTION OF SHEARING FORCES IN THREE DEGRADATION ZONES CONNECTED BY CONVEYING ZONES, THE POLYISOBUTYLENE BEING EXPOSED, AS IT IS CONVEYED FROM DEGRADATION ZONE TO DEGRADATION ZONE, TO TEMPERATURES ALTERNATING BETWEEN 150* AND 350*C. AND TO ALTERNATING SHEARING FORCES WHICH RESULT FROM VELOCITY GRADIENTS OF FROM ABOUT 100 TO ABOUT 700 SEC-1 MAINTAINED BETWEEN THE SHEARING SURFACES OF THE WALL OF THE BARREL AND THE SCREW WHICH ARE MOVING IN RELATION TO ONE ANOTHER.
Inventors
- 👤 Wolfgang Lehnerer
- 👤 Hermann Gueterbock
- 👤 Klaus Kinkel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 21:18
CPC Classifications
B; B29; B29C; B29C48/00; B29C48/25; B29C48/36; B29C48/50; B29C48/76; B29C48/03; B29C48/395; B29C48/505; B29C48/63; B29C48/78; B29C48/875
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) | 1975-01-10 | 1975-07-12 | 1976-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-10 | 1979-07-12 | 1980-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-10 | 1983-07-12 | 1984-01-11 | $7700.00 | Window Closed / Lapsed |