PRODUCTION METHOD FOR THERMOPLASTIC RESIN FOAM, MOLDING MOLD THEREFOR AND THERMOPLASTIC RESIN FOAM

摘要

A thermoplastic resin foam in a desired shape, having a high expansion ratio and cells of a desired diameter, especially fine foam cells. A production method for a thermoplastic resin foam, comprising the steps of filling a thermoplastic resin containing a foaming agent into a cavity (31) of a mold (2a), and then foaming the resin by expanding the cavity (31), wherein, after a molten resin containing a foaming agent is filled into the cavity (31), the cavity (31) is expanded to a final cavity expansion width when an average temperature of the filled resin in the cavity (31) reaches a range from resin melting point to melting point plus 30 DEG C with the cavity kept in a filled shape.