PURPOSE: To obtain a foam molded object free from swirl marks by a method wherein in an injection start-up time and a gate seal time of expandable resin expansion of molding resin is restrained as possible and when expandable core layers of injection molded object are formed, resin is injected above the expanding temperature.
CONSTITUTION: When injection starts up, resin is injected under expanding temperature and at a low injection pressure so that expansion of expanding agent added to resin injected from an injecting nozzle is restrained as possible. Subsequently, resin of the amount enough to form the expanded inner part of a molded object is injected at a temperature and pressure exceeding the expanding point of foaming agent. Finally, when the last end of the cavity in a mold is sealed, resin is injected in an unexpanding state to complete the process. Thus, a molded object with a fine surface can be obtained without producing swirl marks on a foam molded object.
SANO TAKESHI
TAKEUCHI NAOKI
KURUMACHI MASANOBU
FUJII NOBUHIKO
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