PREVENTION OF GENERATION OF SINK IN APPEARANCE SURFACE OF MOLDED PRODUCT AND INJECTION MOLD

摘要

PURPOSE:To prevent the generation of a sink in the surface of the appearance of a molded product. CONSTITUTION:In such a state that a heat insulating membrane 6 of which the close adhesiveness with an injected molten resin is better than that with the mold surface corresponding to the rear surface of a molded product is formed on a part or entire surface of a fixed or movable mold 2 corresponding to the appearance surface of the molded product, a prescribed amt. of a molten thermoplastic resin is injected into the cavity of the mold to fill the cavity and the growth of the skin layer 7 of the molten resin 3 on the surface of the heat insulating membrane 6 is delayed. Further, by preferentially generating the formation of the skin layer 7 and the release of the skin layer 7 on the surface of the other mold, the volumetric shrinkage of the molten resin caused by the cooling and solidification thereof is selectively absorbed by the preferentially released skin layer 7.