POLYOLEFIN CONTAINER HAVING CERTAIN SHRINK CHARACTERISTICS AND METHOD OF MAKING SUCH CONTAINERS

摘要

The two stage production of clear, low-haze, injection stretch blow molded polypropylene container articles with advantageous free shrink characteristics is disclosed. In the first processing stage, a preform article is manufactured on an injection molding machine. In a second and subsequent step, which may occur remotely from apparatus used in the first step, the preform article is heated and stretch blown into a container. The process may employ the selection of processing parameters to produce preform articles that facilitate stretch blow molding at relatively high rates of speed, while still maintaining an appropriate polypropylene polymer morphology that results in clear, low haze containers. Free shrink may be improved and measured. Furthermore, a haze, MFI, and wall thickness of containers subjected to a free shrinkage test following manufacture may be used to estimate or predict the processing parameters used to manufacture the container.