IN-MOLD MOLDING OF THERMOPLASTIC RESIN FOAMABLE PARTICLE

摘要

PURPOSE:To obtain a product wherein enough fusion has reached the inner part even if the thickness of a molded item is thick or the foaming ratio thereof is high by performing evacuation of gas existing in gaps between foamable particles filled in a cavity with steam under a pressurized condition. CONSTITUTION:In a cavity 21 of a mold consisting of a fixed mold 11 with a steam hole 20 and a movable mold 12 with a steam hole 20', wherein the pressure is elevated with a pressurized gas, thermoplastic resin foamable particles are filled while being compressed by using this pressurized gas. After the pressure of the cavity 21 after pressurized filling is furthermore elevated than the pressure at filling time, a steam for evacuation with a pressure which is 0.2kg/cm or more higher than the inner pressure of the cavity 21 is passed through from the steam holes 20 and 21'. Then, the pressure in the cavity 21 is returned to the atmospheric pressure and the compressed foamable particles are returned and expanded to their original condition in the cavity and are furthermore heat-fused together.