Apparatus for plasticizing material for molding thermoplastic resin foam

An apparatus for plasticizing a material for molding thermoplastic resin foam comprising:

• a screw cylinder;
• said screw cylinder including:
• a material supply opening formed adjacent to a rear end thereof;
• an injection nozzle disposed at the leading end thereof;
• a gas supply opening formed between said material supply opening and said injection nozzle and arranged to supply said screw cylinder with at least one of an inactive liquid having a super critical pressure and an inactive gas having a pressure not lower than the super critical pressure;
• a screw disposed in said screw cylinder such that rotation and axial movement are permitted so that when said screw is rotated, thermoplastic resin is plasticized, and when said screw is moved in the axial direction, said plasticized thermoplastic molten resin is injected into a mold, said screw including:
• a first stage having a front portion formed into a first metering portion;
• a second stage having a front portion formed into a second metering portion and a rear portion formed into a low pressure portion in which the capacity of a screw groove is enlarged;
• and
• a screw head portion formed at the leading end of said screw cylinder,
• wherein said gas supply opening of said screw cylinder is formed at a position corresponding to said low pressure portion in said second stage.