| 摘要 |
PURPOSE:To obtain the titled pre-expanded particles suitable as a shock- absorbing material for automobiles, having uniform and large pore diameters and improved expanding and molding properties in mold, by dispersing thermoplastic resin particles containing a volatile blowing agent into water, heating the particles under heating and releasing them to a low-pressure zone. CONSTITUTION:100pts.wt. thermoplastic resin is blended with 5-50pts.wt. volatile blowing agent (e.g., propane, butane, etc.,) to give resin particles, 20-100pts. wt. of the resin particles are added to 100pts.wt. water and dispersed into water while agitating in a pressure container. The water dispersions are heated at 90-180 deg.C under pressure (15-50kg/cm<2>) and released through a die having a ratio of land length of die/average hole diameter of die of 4-100, preferably 10-40 to a low-pressure zone to give pre-expanded particles having >=200mum cell diameters.
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