| 摘要 |
PURPOSE:To prevent deformation from developing even when the vessel concerned is subjected to hot-filling and hot-showering by a method wherein polyester resin is injected from a lower gate and, after the injection rate of said resin is lowered, heat-resistant resin is injected from an upper gate in a cavity and, after both the resins are co-injected from the lower gate, the resins are biaxially stretching blow-molded. CONSTITUTION:Polyester resin is injected through a flow path 58. Concretely, under the condition that the check valve 56 of a lower hot runner nozzle 55 is closed, only polyester resin 60 is injected through flow paths 58a and 58b in the cavity 25 of an injection mold 20. Just before the arrival of the flow front 90 of the polyester resin 60 to the position corresponding to the lower edge face of the support ring 3 of the pre-formed body of the cavity 25, the injection rate of the polyester resin through the lower gate 51 and, at the same time, heat-resistant resin 70 is injected from an upper hot runner nozzle 45 through an annular sprue 42 and an upper gate 41 in the cavity 25 of the injection mold 20. After that, under the condition that the injection pressure of the heat-resistant resin 70 is raised and the check valve 56 is opened, the heat-resistant resin 70 and the polyester resin 60 are co-extruded. The pre-formed body, which is obtained under the condition that the pressure in the injection mold 20, is installed in a biaxially stretching blow mold and biaxially stretching blow-molded. |
