| 摘要 |
PROBLEM TO BE SOLVED: To produce a molded polypropylene resin foam which is excellent in impact energy absorption and can effectively absorb impact energy on collision when used as an energy absorption material for side collision of an automobile or as a bumper core material. SOLUTION: This foam is obtd. by in-mold molding pre-expanded polypropylene resin particles based on a resin having a bending modulus of 10,000kg/cm<2> or higher according to ASTM D790 and a melt flow rate of 20-100g/10min according to ASTM D1238 (230 deg.C, 2.16kg-load) and selected from among a propylene homopolymer, a propylene-α-olefin block copolymer having anα-olefin content lower than 10wt.%, and a propylene-α-olefin random copolymer having anα-olefin content lower than 1wt.%. The foam has a foaming ratio of 5-60 and an open cell content of 0-30% and, when it is compressed to the max. strain of 80% in the compression test according to JIS K6767, the open cell content reaches 30-95%. |
