Injection blow molding technology for polyethylene terephthalate

A review of patents and the literature addressing the injection blow moldin g (IBM) technology specific to PET bottles and containers is presented. Fab rication and polymer modification issues were cited. It was found that ther e is no model that includes all factors which enables a complete a priori p rediction of injection blow molded PET container performance, but there are several which cover certain aspects of the preform blowing step. Hot fill capability for PET is currently managed by both the control of crystallinit y and container design considerations (i.e., wall profile, ribs, etc.). Dep ending on the desired result, both processing routes to enhance the level o f crystallinity (generically referred to in the industry as heat set techno logy), and molecular modification to disrupt crystallinity have been patent ed, some quite recently. A number of patents address technologies that can be used to modify melt elasticity for blow molding. The modification of PET with PEN presents some new challenges due to transesterification during pr ocessing fabrication. Biaxial stretch ratios of 18 are usually required for the blow molding of PET/PEN blends, and maximum filling temperature notice ably decreases only one day after fabrication.