MOLDING OF HOLLOW INJECTION MOLDED PRODUCT

摘要

PURPOSE:To obtain an injection molded product capable of dispensing with design painting by injecting a high temp. pressure fluid simultaneously with or immediately after the molding of a thermoplastic resin by injection molding not only to form a hollow part but also to eliminate the surface defect of the molded product. CONSTITUTION:Simultaneously with or immediately after the injection of a molten resin 13 into the cavity 10b of a mold 10 from the nozzle 12 provided to the leading end of the screw of a molding machine, steam 14 is injected into the cavity 10b from the nozzle 12 through a pipe 15. A weld line becomes almost inconspicuous by the heat of this steam 14. Further, flowability is enhanced because of the lowering of the viscosity of the molten resin and a thin- walled molded product having high gloss is obtained. The steam 14 is pref. set to 100-350 deg.C in temp. and to 1-170kg/cm<2> in pressure. The injection place 17 of the steam 14 is pref. provided to a plurality of places of the mold 10 inclusive of the nozzle 12.