| 摘要 |
PURPOSE:To injection mold a foamed body with skin without deteriorating a surface quality of a skin material by a method wherein the skin material is disposed in a mold, a resin mixed with a foaming agent is heated and melted in an unfoamed state in a cylinder, and the foaming agent is thermally decomposed between the cylinder and the mold before the resin is injected into a cavity. CONSTITUTION:For example, a rotary valve 17 generating a shearing heat is provided in an intermediate part of a melt resin path 16 of a nozzle 12 of an injection molding machine. A resin mixed with a foaming agent is increased in temperature in a cylinder part by heaters 63a-63c and by a shearing force by the rotation of a screw 15. At this time, the resin is so controlled as to be melted in an unfoamed state at the top of the screw 15. When the resin is injected by the screw 15 and passed through the rotary valve 17, the resin is heated to at least the decomposition temperature of the foaming agent by adjusting an opening of the valve. Thus, the resin is injected out of a gate 68 while foaming. The resin is quenched by an inner surface of a mold 13 to form a skin layer. The resin coming into contact with a skin material 69 is firmly bonded to the skin material 69 while also forming the skin layer. |
