METHOD OF MOLDING SYNTHETIC RESIN BOTTLE BODY

摘要

A technical problem to be solved by this invention is to create a biaxially drawing and blow molding process that can fully make up for a restricted upper limit to the preform body wall thickness. An object of this invention is to provide a biaxially drawn, blow molded bottle which is narrow-mouthed and yet has a substantially expanded body. In principle, the molding process of this invention to solve the technical problems comprises three steps of :
(1) injection molding a preform in the shape of a test tube taller than the bottle wherein the preform has a cylindrical mouth opening portion disposed in an upper part of the preform, and wherein the mouth opening portion of the preform serves also as a mouth opening portion of the bottle product;
(2) thermally shrinking the preform from an initial height so that portions other than the mouth opening portion of the preform would have a height that is smaller than that of the bottle; and
(3) setting this thermally shrunk preform in a blow mold and biaxially drawing and blow molding the preform into the bottle.