LAMINATED PREFORM, ITS MOLDING METHOD, AND INTERMEDIATE PRODUCT AND CONTAINER MOLDED OUT OF THE PREFORM

摘要

PURPOSE: To provide sufficient gas barrier properties using a small amt. of a barrier material by successively injecting a thermoplastic resin, a barrier material and a thermoplastic resin into a mold of a preform for blow molding and forming inner and outer layers of the barrier material and a center layer comprising a thermoplastic resin inside inner and outer layers comprising a thermoplastic resin. CONSTITUTION: A predetermined limited amt. of a thermoplastic resin 56 is injected into the cavity surrounding the core member 26 of a mold 20 to form solidified inner and outer layers 58, 60. Subsequently, when a barrier material 66 is ejected, a tunnel stream is generated and, at the same time, the resin 56 is advanced and, when this resin comes into contact with the layers 58, 60, it is solidified to form solidified layers 68, 70. Next, when a separate thermoplastic resin 72 is ejected, the barrier material 66 is remelted to reduce the thicknesses of the layers 68, 70 to be advanced and the previously ejected thermoplastic resin 56 is advanced. By this method, a preform having the barrier layers 68, 70 built therein and having no barrier material 66 at the open end part and the leading end of the bottom part thereof is obtained.