PREFORM AND MOLDED BOTTLE USED THE SAME FOR BIAXIALLY ORIENTED BLOW MOLDING OF PRESSURE RESISTANT INDEPENDENT POLYETHYLENETEREPHTHALATE

摘要

PURPOSE:To enable only the bottom-peripheral edge of a bottle to be surely thickened by only blow molding by a method in which in a preform, the wall thickness of border part is more thickened than that of bottom and barrel, and the diameter of the bottom is more reduced than that of the barrel. CONSTITUTION:A border part 15 is arranged on the boundary between the barrel 12 and the bottom 13 of a preform. When orientation blow molding is carried out, the peripheral edge 5 of the bottom of a bottle is formed by thickening this border part 15, and the wall thickness of said peripheral edge may be more thickened than that of the barrel or the bottom. The wall thickness of the border part 15 of the preform is preferably 1.1-5 times of the wall thickness of the barrel 12 or the bottom 15. In the border part 15, the diameter of the preform is drawn, whereby a step is formed, and then since the diameter of the bottom 13 is more reduced than that of the barrel 12, the preform is first expanded in radial direction in orientation blow molding. The barrel with large outer diameter is expanded large, and the bottom with small auter diameter is expanded smaller. Since the connected part of the bottom 13 to the barrel 12 becomes the peripheral edge of the bottom of the bottle, the bottom- peripheral edge of the bottle in which the border part 15 is molded is formed.