| 摘要 |
PURPOSE:To prepare the titled foamed particles, with heat resistance, yielding a foam product with a low density, shock-absorbing properties, and great strength, by incorporating a specific foaming agent in PP resin particles and allowing to foam in multiple steps. CONSTITUTION:PP resin particles (ethylene content 1-10wt%; MI 0.1-20; Vicat softening pt. (load 1kg) 100-150 deg.C) selected from propylene/ethylene random copolymer and propylene/ethylene/butene random terpolymer are impregnated with a low b.p. org. compd. foaming agent (e.g. butane) to allow to expand 3-20 times the original volume with heat. The foamed particles are impregnated with a low b.p. org. compd. (e.g. dichlorodifluoromethane) or an inorg. gas (e.g. N2 gas), and the resulting mixt. is allowed to foam with heat, yielding a foamed PP resin particles, expansion 10-50 times the original volume; closed cell content >=65%. |
