| 摘要 |
PURPOSE:To mold PET by omitting predrying under the condition that venting is performed by vacuumizing to the specified degree of vacuum with an injection device having venting function at the injection molding with molding material made of green polyethylene terephthalate. CONSTITUTION:An injection screw 7 consists of a front screw 7a, the shaft diameter at the tip of which is made larger than that at the remaining part so as to form compressive part, and a rear screw 7b and has a vent port 8 on the heating cylinder wall at the rear of the front screw 7a. To the vent port 8, a vacuumizing circuit 10 is connected through a member 11 from a vacuum pump 9 so as to plasticize and knead the molding material under the condition that the interior of the vent port is vacuumized to 50-150Torr with the vacuum pump 9. Further, in the vacuumizing circuit 10, a recovery tank 12 for removing volatile components from the molding material by cooling and a filter 13 are provided. Thus, the moisture and the like in the molding material can be forcibly removed during plasticizing and kneading. |
