Abstract:
A preform 20 for a large container, used for producing a large container which is made of a polyethylene terephthalate resin and which is formed by stretch blow molding, is formed by injecting molding to have a wall thickness of 6 mm to 9 mm and have a longitudinal axis length longer than that of the large container which is a final molded product.
Abstract:
An embodiment of a method of molding a large returnable container includes a heat treatment step for subjecting a thick preform formed of a polyester resin or a primary blow-molded article to intermediate blow molding with heating to obtain an intermediate molded article, and a final blow molding step that includes subjecting the intermediate molded article that has shrunk to final blow molding with heating to obtain a large returnable container. The heat treatment step includes disposing the preform or the primary blow-molded article in a heat treatment mold, and pressurizing the preform or the primary blow-molded article so that a shoulder and a body obtained by blow molding close contact to a cavity surface of the heat treatment mold, and are subjected to a heat treatment, the shoulder being heated at a low temperature as compared with the body.