| 摘要 |
PROBLEM TO BE SOLVED: To provide a screw extruder capable of preventing a resin from residing between the tip face of a screw and the opposite face of a breaker plate and obtaining high-quality moldings. SOLUTION: The screw extruder A has numerous resin circulating holes 31 formed penetrating the breaker plate 3, the resin circulating holes opposed to the tip face of the screw 2 of which are smaller in diameter than the remaining resin circulating holes 31b as a small-diameter resin circulating holes 31a. A back pressure between the tip face 23 of the screw 2 and the opposite face of the breaker plate 3, that is, the pressure of a molten resin is increased and thus a turbulence is generated in the molten resin between the tip face 23 of the screw 2 and the opposite face of the breaker plate 3 to promote the kneading of the molten resin. Consequently, the molten resin does not reside between the tip face 23 of the screw 2 and the opposite face of the breaker plate 3 and an unforeseeable trouble such as the qualitative deterioration of the molten resin due to its residence in a cylinder for a long time and exposure to head, is not generated.
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