INJECTION STRETCH BLOW MOLDING METHOD

摘要

A molten resin filled by injection into an injection mold is molded into a required preform (2) by rapid cooling. The preform (2) is mold-released at high temperature by holding its neck by a neck form. It is subjected to biaxial stretch blow molding in a blow mold to form a bottle (1) having a thin-walled barrel portion (1a). Of the wall thickness (2a) and the length (2b) of the stretched portion of the preform (2) that are set from the volume and weight of the bottle (1) and the barrel wall-thickness (1a), the wall-thickness (2a) is set smaller than the normal set wall-thickness. The length (2b) is set to be larger in inverse proportion to the set wall-thickness. The preform (2) is mold-released at a higher temperature than normal and subjected to stretch blow molding before the outer-surface temperature reaches its peak. Even though being of the hot parison type based on high-temperature mold release, the method makes it possible to reduce the wall-thickness of the stretched portion of the preform while increasing the length, thereby enabling stretch blow molding of blow molded articles of normal configurations whose barrel wall-thickness is smaller than 0.2 mm.