Method of forming foamed polystyrene articles from polystyrene beads
Abstract
Abstract A SCREW EXTRUDER FOR CONVERTING POLYSTYRENE BEADS INTO FOAM INCLUDING AN EXTRUDER SCREW HAVING A FIRST SCREW STAGE FOR RECEIVING POLYESTERS BEADS AND FOR COMPRISING AND MELTING THE BEADS TO FORM MELTED POLYSTRENE AND A SECOND SCREW STAGE FORRECEIVING MELTED POLYSTRENE FROM THE FIRST STAGE AND FOR DISTRUBING A BOWLING AGENT THROUGHOUT THE MELTED POLYRENE; AND A RING VALVE FOR CONTROLLING THE FLOW OF MELTED POLYSTYRENE FROM THE FIRST STAGE TO THE SECOND STAGE AND THEREBY PREVENTING BACKFLOE OF THE BOWLING AGENT FROM THE SECOND STAGE INTO THE FIRST STAGE. THE FIRST SCREW STAGE OF THE EXTRUDER SCREW HAS A COMPRESSION RATIO OF ABOUT 3.5:1, AND COMPRISES A METERING SECTION, A TRANSITION SECTION THAT IS ABOUT 1.5 TIMES AS LONG AS THE METERING SECTION, AND A FEED SECTION THAT IS ABOUT 2 TIMES AS LONG AS THE METERING SECTION.
Inventors
- 👤 D Wiley
Bibliographic Details
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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) | 1977-06-03 | 1977-12-03 | 1978-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-03 | 1981-12-03 | 1982-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-03 | 1985-12-03 | 1986-06-04 | $7700.00 | Window Closed / Lapsed |