| 摘要 |
PURPOSE:To mold readily a low foamed resin structure whose expansion ratio of foaming is progressively increased from the surface toward the inside, by injecting a resin into molds at a temperature lower than the temperature of decomposition of a foaming agent contained in the resin, and heating a sprue section through which the resin is passed. CONSTITUTION:The resin 13 is injected at a temperature lower than the decomposition temperature of the foaming agent present in the resin into the molds 1, during the injection the sprue section 9 is heated to a temperature higher than the decomposition temperature of the foaming agent so that the resin 14 which is in the foamed state is injected into the molds 1. At the final stage of the injection, the heating of the sprue is stopped, and with the sprue being cooled to a temperature lower than the decomposition temperature of the foaming agent, the injection of the resin is completed. Thus, the low foamed resin structure whose foaming rate is progressively increased from the surface toward the inside can be molded readily within a short period using a simple apparatus. |
