PRODUCTION OF PLASTIC MOLDED PRODUCT

摘要

PROBLEM TO BE SOLVED: To obtain a highly accurate molded product by using a crystalline resin. SOLUTION: A crystalline thermoplastic resin (polypropylene in a drawing) is molded into an almost final shape at load bending temp. (H.D.T) of 60 deg.C on a basis of a wt. determined so that the resin pressure in a mold cavity becomes atmospheric pressure. This molding matrix is inserted into the mold cavity having a transfer surface and heated to temp. of 160 deg.C (B-point) equal to or higher than thermal deformation temp. (A-point) but equal to or lower than melt temp. Tm(o) to be thermally expanded. The transfer surface is transferred to the resin in the mold cavity by the resin inner pressure caused by this thermal expansion. Thereafter, the molded matrix is gradually cooled to temp. equal to or lower than H.D.T (60 deg.C) through a route of (B→C) and taken out as a molded product in a state near to almost atmospheric pressure.