Molded foam resin, process for forming the same and speaker diaphragm consisting of the same

Abstract

A molded foam resin, surface of which can be designed easily at low cost, a process for forming a molded foam resin, and a speaker diaphragm made of molded foam resin are provided, in which a molded foam resin is formed by injection molding of foaming agent-containing resin and has a foamed zone having a three layer-structure consisting of a foamed layer inside and a non-foamed layer outside and a non-foamed zone having a single layer-structure consisting of a non-foamed layer. The process for forming the molded foam resin according to the present invention includes the steps of injecting a foaming agent-containing resin into a mold and opening the mold after a lapse of a designated period of time after the completion of the injection, in which a cavity of the mold contains a thick space corresponding to the foamed zone and a thin space corresponding to the non-foamed zone, and the designated period of time is chosen so that a curing of the resin filled into the thin space is completed and a curing of the resin filled into the thick space is not completed. Thus, a molded foam resin and a speaker diaphragm according to the present invention can be thinned, designed with different tone of color on surfaces thereof and lightened without deteriorating stiffness thereof.

Dependencies are inferred from the claim text.