| 摘要 |
PURPOSE:To provide a preform, which has excellent external appearance characteristics and gas barrier property and at the same time the blocked bottom of which has sure sealing property, by a method wherein a pipe, the inner and outer surface layers of which are made of thermoplastic polyester and the intermidiate layer of which is made of gas barrier resin, is melt-extruded and cut to size and formed so as to have a tapered cut surface at its inner or outer peripheral surface in order to form a blocked bottom by stamping its end. CONSTITUTION:A multi-layer pipe 14, the inner layer 8 and the outer layer 10 of which are made of polyester, the intermediate layer 9 of which is made of gas barrier resin and resin layers 11a and 11b of which are made of bonding agent and interposed between the layers 8 and 9 and between the layers 9 and 10, is extruded through multi-layer, multiple dies. The pipe 14 is immersed in the water so as to be quenched to the supercooled state in order to be cut to size. By being obliquely cut on the outer peripheral surface at a cut end, which is but-joined in order to form the bottom, a multi-layer pipe 16 with a tapered part 15a is formed. The end, at which the tapered part 15a is provided, is heated up to a heat-fusible temperature. The pipe 16 and an outer mold 17 and an inner mold 18' are arranged concentrically. The blocked bottom is formed by shifting the tapered end, the inner mold 18 and the outer mold 17 is such a manner that the tapered end and the concave surface part 19 of the outer mold engages with each other. |
