Molded foam manufacturing apparatus and screw for molded foam manufacturing apparatus

Abstract

A molded foam manufacturing apparatusincludes a cylinderin which a plasticization zonewhere a thermoplastic resin is plasticized and melted, a starvation zonewhere the molten resin is put into a starvation state and an injected physical foaming agent is dissolved in the molten resin, and a feeding zonewhere the molten resin in which the physical foaming agent is dissolved is compressed and metered are provided in this order from an upstream side, and a screwthat is installed inside the cylinderso as to be freely rotatable around an axis of the cylinder and has flights formed in a spiral shape on an outer circumference of a shaft, wherein a lead angle R of the flights of the screwcorresponding to the feeding zoneis set smaller than a lead angle α of the flight corresponding to the starvation zone, and the number of pieces of the flight of the screwcorresponding to the feeding zoneis set smaller than the number of pieces of the flight corresponding to the starvation zone. In this way, it is possible to prevent a decrease in the flow rate of the molten resin transported in the starvation zone and the feeding sone and manufacture high-quality molded foams with high production efficiency.