| 摘要 |
PURPOSE:To enhance the reproducibility of the surface of a mold and durability and to stably produce a product excellent in appearance by coating the wall surface of a mold excepting the boundary part of the mold wall surface constituting a mold cavity and the pinch-off part of the mold with a heat insulating layer with predetermined thickness composed of a heat-resistant polymer. CONSTITUTION:A blow mold is constituted so that an extruded parison is subjected to blow molding while bitten off by a pinch-off. Herein, the mold wall surface excepting the boundary part of the mold wall surface constituting the mold cavity of a main mold 1 composed of metal and the pinch-off part 3 of the mold is coated with a heat insulating layer 2 composed of a heat- resistant polymer of which the heat conductivity is 0.002cal/cm.sec. deg.C or less. The heat insulating layer 2 is applied in a thickness of 0.1-2mm. A synthetic resin capable of being molded using this mold is a thermoplastic resin used in general blow molding. The heat-resistant polymer used in the heat insulating layer 2 has a glass transition temp. of 150 deg.C or higher and an m.p. of 250 deg.C or higher. |
