| 摘要 |
PURPOSE:To obtain a multilayered vessel without the possibility of layer separation, having outer layers and a central layer stuck forcibly by substituting the layer of the gate portion of a parison by resin A, post-injecting the resin A finally, while injecting successively the resins in order of resin A, resin B and resin C into a single mold by one time mold closing operation. CONSTITUTION:The volume of molten resin A corresponding to 40-80% of the volume of a cavity 7 is injected into the cavity from an injection cylinder 1, and successively the volume of molten resin B corresponding to 1-5% of its volume is injected into the cavity 7 from an injection cylinder 2. Further the volume of molten resin C corresponding to 16-50% of its volume is injected into the cavity 7, and again a small volume of resin A is injected from the injection cylinder 1, whereby the outermost layer adjacent to the gate 5 of the parison is substituted with resin A, and simultaneously the content in a flow path is replaced by resin A. After pressurizing and cooling thereof have been kept, when the mold is opened, the multilayer parison composed of five- layer structure and having at least a mouth opening portion made of a single structure is obtained. |
