PRODUCTION OF THERMOPLASTIC RESIN FOAM

摘要

PURPOSE: To produce thermoplastic resin foam having a foam structure oriented along in the thickness direction thereof and excellent in surface properties. CONSTITUTION: Thermoplastic resin foam is produced by a process melting and kneading a mixture consisting of a thermoplastic resin and a chemical foaming agent and extruding the kneaded mixture into a mold in a non-foamed state to seal the same in the mold, a process pressing and shaping the mixture by a piston and supplying gas into the mold to hold the pressure in the mold to pressure higher than the surface pressure receiving from the piston by 10-50 kgf/cm<2> , a process decomposing the foaming agent and setting the difference between resin inner pressure and the pressure in the mold to 5kgf/cm<2> or less to discharge the gas to the outside of the mold and opening the piston at a speed equal to or less than the expansion speed of the resin and a process cooling and solidifying the molded product in the mold to take out the same.