| 摘要 |
PURPOSE:To improve productivity and economical property by filling a closed mold with foaming component of kneaded mixture of PVC, inorganic particles and a foaming agent and heating the mold under pressure and opening it at the temperature which is higher than the softening temperature of PVC and by having the component foam. CONSTITUTION:A fixed amount of vinyl chloride resin, inorganic particles and foaming agent is well kneaded by a ribbon blender, a double arm type kneader, etc. and the foaming material, thus prepared, is put into a closed mold made of aluminum alloy, etc. and set by a hydraulic driven heating press and heated under pressure. A temperature, time and pressure suitable for the foaming material is selected at this time. Then, while the mold is kept under pressure, the temperature of a pressure heating plate of the press is lowered with a cooling medium like water etc. to the foaming point and the pressure of the mold is removed for the content of the mold to be released to the atmosphere. The temperature suitable for foaming should be lower than the pressure heating temperature and higher than the softening temperature of PVC and it should be the one under which cell collapse does not occur. |
