Parison and method for forming parisons for biaxial orientation blow molding

摘要

Bottles made of saturated polyester resin, particularly polyethylene terephthalate resin, by orientation blow molding exhibit phenomenal properties and characteristics, but suffer from a serious disadvantage in that the bottle neck is greatly inferior in the properties and characteristics to the bottle body, because the neck is molded into the final form without undergoing biaxial orientation. Biaxial orientation gives the bottle body outstanding properties and performance because it causes the molecules of a molding resin material to be arranged in the same direction. Based on this principle, the bottle neck is given the same effect as is produced with biaxial orientation by applying tensile force in a certain direction to the molecules of a molding resin material while it is still in a temperature range at which orientation takes place.