| 摘要 |
PURPOSE:To obtain the title foam having excellent high-temperature rigidity and low-temperature fluidity, by mixing a specified block PP or homo PP with a blowing agent, a crosslinking aid, etc., molding the mixture, crosslinking the molded product by irradiating it with a radiation and expanding it. CONSTITUTION:A block PP (a) having an MFR of 1-20 or homo-PP (a) having an MFR of 1-30 is mixed with 100-600ppm of an org. peroxide (b) having a decomposition temp. of not lower than 170 deg.C. The mixture is heat-treated at 170-250 deg.C or irradiated with a radiation at a dose of 1-100Mrad to modify the PP, thus obtaining a block PP or homo-PP (A) having an MFR of 30-100 and an ethylene content of 1-20wt%. The component A or a pelletized mixture thereof with 40-60wt% random PP is mixed with a powdered blowing agent (C) (e.g., azodicarbonamide), a liquid crosslinking aid (D) (e.g., trimethylolpropane trimethacrylate), etc. The mixture is molded and the molded product is irradiated with a radiation, pref. beta-ray at a dose of 0.1-50Mrad to crosslink it. The product is then expanded by heating it at 190 deg.C or higher, pref. 230-260 deg.C.
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