Biaxially drawn, blow-molded bottle and its preform

摘要

The purpose of this invention is to set the position of the gas barrier layer in such a manner as to solve the problem of decreased accuracy of neck molding dimensions created by the thermal crystallization and the problem of interlaminar separation in the bottom, both of which are associated with the provision of the gas barrier layer. Problems should be solved without being affected by the displacement of the gas barrier layer, which may take place during the co-injection operation of the PET resin layers and the gas barrier layer. A biaxially drawn, blow-molded bottle and its preform comprise at least a layer of a gas barrier material 3 laminated inside the PET resin layers 2, a functional portion 5 having a screw thread 8 raised spirally in the upper portion of neck 4 and also having a stop ring 6 disposed under the screw thread 8, and a neck ring 7 disposed at the lower end of the neck 4. In these preform and bottle, the leading edge 3a of the gas barrier layer 3 is positioned at a half height of the neck ring 7 where the most advanced front of the leading edge 3a neither reaches a half height of the stop ring 6 nor extends to the functional portion 5. It is intended here that the neck 4 would not be affected by the shrinking deformation caused by the existence of the gas barrier layer 3 in the functional portion 5 of the neck 4, which is treated for thermal crystallization.