Polyester resin lamination vessel and molding method therefor

摘要

A multilayer preform having at least a medium or intermediate gas barrier layer is prepared in advance by the injection molding of this preform in a predetermined shape that corresponds to the shape of a finished molded product. The body portion of this preform is heated to a blow moldable temperature. The heated preform is set in a primary blow mold (12), and is blow molded in the biaxial orientation to give a primary molded intermediate (5). The primary intermediate (5) is then heated to deform it forcibly by thermal shrinkage and thereby to give the secondary molded intermediate (6). The shrunken secondary intermediate (6) is set in a secondary blow mold (13), and is subjected to the secondary blow molding in the biaxial orientation to obtain a finished molded product, which is fixed thermally to give heat history to the PET resin. As a result, the PET resin layers are given a high degree of crystallization, which serves to complement the function of the gas barrier layer or layers in such a way that the container has high and effective gas barrier properties.