| 摘要 |
PURPOSE:To obtain easily a large expansion molding item having a complicated shape wherein strength is required and to attempt to improve the productive efficiency of a product having an excellent surface condition, by carrying out expansion molding of an expandable melt in a mold by adding an impact. CONSTITUTION:A thermoplastic resin and a foaming agent are melt-kneaded homogeneously under pressure and kept at a temp. and pressure condition where no expansion occurs. The mixture is therefrom extruded intermittently into a lower pressure zone such as atmospheric pressure to obtain a molten extrudate F. The molten extrudate F is placed on a fixed place 8 and is impacted by lowering an impacting plate 7, which is rapidly elevated to the original position. The impact process can be carried out during the molten extrudate F is sent to a molding process IV or by the pressing pressure when it is clamped by a mold. A lot of fine foams are generated in the molten extrudate during foaming process by this impact treatment, and large foams are also divided into fine foams to increase an expanding force, and it is possible to obtain the molten extrudate having excellent expansion moldability. The impacted molten extrudate F is molded in a mold to a required shape. |
