Process for injection stretch blow molding

摘要

An improved method for injection stretch blowing is provided. In the process, a molten resin is injected into an injection cavity defined by an injection mold, a lip mold and an injection core to form a desired preform, where cooling time for this preform is positively reduced to form a rigid skin layer on the outer surface of the preform without increasing the thickness. After then it is released from the injection mold and transferred into a blow mold with a mouth portion being held with the lip mold while the skin layer keeps the configuration of the preform and the interior is in a high temperature state, and is stretch blow molded into a hollow molded article, e.g. a bottle of which major portion is ultra-thin at the moment when a surface temperature of the preform that rises due to its own interior temperature is significantly higher than a glass transition temperature (Tg) and is expected to reach to a peak temperature. Thereby, it is possible to allow molding of a hollow molded article having a thickness of 0.17 mm or smaller without being affected by limitations of thickness of the preform and molding temperature even in a molding process where the preform is released from the mold at a high temperature and is then immediately subjected to stretch blow molding. <IMAGE>