Abstract: In the hot parison method of stretch blow molding, the temperature distribution of the body wall of the injection molded preform is changed to a gentle gradient slope shape from a mountain shape not by the external application of heat, but by the preform itself, to prepare a bottle with an improved top load value. After the injection-molded preform is released from the mold, cooling of the inner side of the preform is continued by the injection core. Inner side cooling is terminated by release from the injection core. The preform is left in a hollow state for a time, the temperature-averaging time, until the outer surface temperature drops to the stretch blow molding temperature, after passing a peak temperature. While in the molding temperature region, stretch blow molding of the thin-wall hollow molded article is conducted.

Abstract: As the hot parison method stretch blow molding, the temperature distribution of the inner side of the body wall of the injection molded preform is changed to the gentle gradient slope shape temperature distribution from the mountain shape not by the external application of heating but by the preform itself so that the bottle which the top load value is improved can be prepared. The preform which is injection molded is mold-released in a high temperature state. The inner side cooling of the preform after mold-release is continued by the injection core. The inner side cooling is terminated by mold-release of the preform from the injection core. The preform is left in a hollow state. The leaving time is made as the temperature-averaging time of the preform. The preform is maintained until the outer surface temperature drops to the stretch blow molding temperature thereafter the peak temperature. In the molding temperature region, the stretch blow molding of the thin-wall hollow molded article is conducted.