| 摘要 |
<p>A molded exterior body part of an automobile, e.g. a bumper, is molded from a thermoplastic composition comprising, by weight, (a) 100 parts of a block copolymer of formula A &lparstr& B-A)n where A is polymer block of a monovinyl-substituted aromatic hydrocarbon, preferably styrene, B is an elastomeric polymer block, e.g. butadiene, and n = 1-5, comprising at least 65 wt % of the copolymer, e.g. made using a Li or Ziegler catalyst followed by catalytic hydrogenation; (b) 40 to 300 parts of a block copolymer of propylene and an alpha-olefin, e.g. ethylene or butene, optionally (c) 0-50 parts of a softening agent for rubber, e.g. a napthenic or paraffinic agent and (d) 0-200 parts of a copolymer rubber of ethylene and an alpha-olefin, e.g. propylene.
<??>The copolymer (b) should have a melt flow rate of 1g/10mm, e.g. 5-200g/10min. This copolymer provides good elasticity, low temperature impact strength, scratch resistance and flowability, to the composition which is readily moldable from pellets thereof, e.g. by injection molding. </p> |
