EXTRUSION FOAM MOLDING METHOD FOR THERMOPLASTIC RESIN

摘要

PURPOSE:To reduce the range of fluctuation in widths by improving productivity in a foamed sheet and increasing a discharge quantity, by providing a helical gear pump to a foam extrusion molding machine. CONSTITUTION:A resin extrusion molding device where a helical gear pump 2 is arranged is used for a resin passage between an extrusion machine 1 and die 4. Styrene resin containing a foaming agent plasticized and melted with a screw 7 is agitated by the helical gear pump 2 and then extruded into a low pressure sphere than pressure of the inside of the resin passage through the die 4 for foaming. Intermittent air release of resin pressure is made continuous by making use of the helical gear 2, through which prevention of evaporation of a foaming agent within molten resin and reductions in a variation of a discharge quantity and a deflection range of a thickness distribution can be performed. Foaming can be performed at high discharge quantity without raising a resin temperature.