| 摘要 |
PURPOSE:To mold a molded product such as a preform by plasticizing directly an uncrystallized or a crystallized PET without drying preliminarily by means of the adoption of a vent type injection device. CONSTITUTION:A vent type injection device, provided with an injection screw 1 consisting of a first stage 10 and a second stage 20 and fitted inside rotatably and movably back and forth in a heating cylinder 2 with a vent 3, is used. The transfer amount of a material resin to a feed zone 12 of the first stage 10 of the vent type injection device is so controlled as not to be softened, compressed and delayed before reaching a compression zone 13 in front of the feed zone. The control is carried out by forming a screw channel sectional area of a receiving and feeding zone 11, in which a hopper inlet section of the first stage 1 is positioned, to be smaller than the screw channel sectional area of the feed zone 12. Uncrystallized polyethylene terephthalate in the above state with which predrying is omitted is fed into a hopper 5 as the material resin, plasticized and injected. |
