| 摘要 |
PURPOSE:To easily manufacture foam large in the degree of freedom by forming a plastic preform so as to have a multilayered structure consisting of a layer containing a foaming agent and a magnetic material and a layer not containing them and applying a high frequency magnetic field thereto to activate a foamed layer. CONSTITUTION:A preform 1 consists of a resin layer la containing a foaming agent 2 and a magnetic material 3 and a resin layer 1b not containing them and is introduced into a high frequency magnetic field 4 to heat the magnetic material 3 in the resin layer 1a by magnetic field induction. The resin 1a' of the resin layer 1a is melted by this heating and the foaming agent 2 is foamed by thermal reaction to form a foamed layer. Since the resin layer 1b is not heated, the preformed shape is held by the resin layer 1b. Therefore, foam large in the degree of freedom, for example, a three-dimensional tubular member or a double pipe member can be easily and efficiently produced and foaming magnification is also easily controlled. |
