Forming polyethylene terephthalate
Abstract
Abstract A PROCESS FOR FORMING A SHEET OF POLYETHYLENE TETRPHTHALATE INTO A MOLD CONFIGURATION, THE PROCESS COMPRISING (A) HEATING A SHEET OF POLYETHYLENE TEREPHTHALATE HAVING AN INTRINSIC VISCOSITY OF ABOUT FROM 0.50 TO 0.59 AND A DEGREE OF CRYSTALLIZATION OF ABOUT FROM 0 TO 25% TO A TEMPERATURE OF ABOUT FROM 75* TO 180*C.; (B) FORCING THE HEATED SHEET ONTO A MOLD SURFACE; AND (C) HEAT SETTING THE SHAPED SHEET AT A TEMPERATURE OF ABOUT FROM 125* TO 220*C. AND FOR A PERIOD OF TIME SUFFICIENT TO INCREASE THE DEGREE OF CRYSTALLIZATION OF THE FORMED ARTICLE TO ABOUT FROM 25 TO 60%. PARTICULARLY USEFUL ARTICLES THAT CAN BE FORMED BY THE PROCESS INCLUDE TRAYS HAVING A BOTTOM PANEL, SIDE WALLS CONNECTED TO THE BOTTOM PANEL AND A CONTINUOUS OUTWARDLY EXTENDING FLANGE CONNECTED TO THE UPPER EDGES OF THE SIDE WALLS; THESE TRAYS CAN BE USED FOR FOOD CONTAINERS, WHICH ARE HEATABLE IN EITHER CONVENTIONAL OR MICROWAVE OVENS AND ARE STRONG AND DIMENSIONALLY STABLE AT TEMPERATURES UP TO ABOUT 460*F. ADHESIVE CAN BE APPLIED TO THE UPPER SURFACES OF THE FLANGE TO PERMIT THE APPLICATION OF A COVER FILM TO THE TRAY.
Inventors
No inventors recorded.
Bibliographic Details
Claims Analysis
Total Claims: 0References 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) | 1976-10-08 | 1977-04-09 | 1977-10-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-08 | 1981-04-09 | 1981-10-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-08 | 1985-04-09 | 1985-10-09 | $7700.00 | Window Closed / Lapsed |