A literature survey of the influence of preform reheating and stretch blow molding with hot mold process parameters on the properties of PET containers Part I

Abstract

The paper presents a wide analysis of the literature on the modified blow molding process with simultaneous stretching of PET material for storing hot filled drinks. The hot fill process is an inexpensive conventional filling technology for high-acidity products (pH < 4.5). It allows certain drinks (sensitive beverages such as fruit and vegetable juices, nectars, soft drinks, vitaminized water) to be stored at ambient temperature without the need for chemical preservatives. The primary feature of the bottles used in the hot fill process is their temperature stability, i.e. the ability to retain the shape of the bottle at the filling temperature. From a mechanical point of view, the thermal stability of PET [poly(ethylene terephthalate)] bottles manufactured by the ISBM (injection stretch blow molding) process is determined by the mechanical and thermal response of the blown preforms. From a microscopic point of view, the strongest influences on the mechanical and thermal properties of PET bottles are the orientation and crystallization processes. From a technological point of view, the properties of PET bottles after manufacture by the stretch blow molding process is mainly determined by the initial structure of the PET preform, the geometry and temperature distribution of the preform, the geometry of the blow mold, the temperature of the blow mold and its distribution in various parts of the mold and technological parameters of the blow molding process.