| 摘要 |
PURPOSE:To improve the heat resistance, cushioning property and strength of a molded body, by incorporating a volatile foaming agent or an inorganic gas into foamed particles that are prepared by cutting polypropyrene resin foamed strands, and heating the particles so that they are further allowed to foam. CONSTITUTION:A polypropylene resin is mixed with a foaming agent at high temperatures under high pressures using an extruder, and a cellular strand having a foaming rate of 1.1-20, an open cell rate of 30% or below and a cell diameter of 0.6mm. or below is extruded from a die into a low pressure zone. The cellular strand is cut into foamed partilces, a volatile foaming agent or inorganic gas is incorporated therein, and the foamed particles are heated further to be allowed to foam in steps so that foamed particles having a foamed ratio of 10-50 is obtained. As the foaming agent used in extrusion foaming, are mentioned azodicarboxylic amides, etc. and as the volatile foaming agent are mentioned propane, dicyclotetrafluoloethane, etc. |
