Patent US3658973A successfully refreshed from Google Patents.
US3658973A
Expired / Lapsed
US
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Method for extruding a foamed thermoplastic polymer
Assignee: Monsanto Co
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Filing: 1971-03-22
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Granted: 1972-04-25
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Expires: 1991-03-22
Abstract
Abstract EXTRUDING A FOAMED THERMOPLASTIC RESIN WHEREIN A VOLATILE ORGANIC BLOWING AGENT IS INTRODUCED INTO A MOLTEN THERMOPLASTIC POLYMER IN A ZONE OF DECOMPRESSION IN A SCREW EXTRUDER. THEREAFTER, PRIOR TO EXTRUSION THE PRESSURE IS INCREASED AND THE MOLTEN POLYMER FURTHER MIXED WITH THE BLOWING AGENT. THE MIX IS THEN COOLED, AND FINALLY THE PRESSURE ON THE MIX IS INCREASED WHILE CONTINUING THE COOLING. THE MIX IS THEN EXTRUDED INTO A ZONE OF LOW PRESSURE. POLYSTYRENE MAY BE USED AS THE THERMOPLASTIC POLYMER.
Inventors
- 👤 Ardashus A Aykanian
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 10:41
CPC Classifications
B; B29; B29C; B29C44/00; B29C44/34; B29C44/3442
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) | 1975-04-25 | 1975-10-25 | 1976-04-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-25 | 1979-10-25 | 1980-04-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-25 | 1983-10-25 | 1984-04-25 | $7700.00 | Window Closed / Lapsed |