PROPYLENE/ETHYLENE BLOCK COPOLYMER COMPOSITION FOR EXTERIOR AUTOMOTIVE PART

摘要

The present invention provides a propylene-ethylene block copolymer composition for automobile exterior parts having sufficient stiffness and mechanical strength required for the automobile exterior arts, which is produced at low cost since no additional steps for blending other rubber components are required in the production thereof. The composition contains methylenebis(2,4-di-t-butylphenol) acid sodium phosphate which is blended with the propylene-ethylene block copolymer in an amount of 300 to 2,000 ppm upon granulation thereof, and has (a) a melt flow rate of 10 to 18 g/10 min when measured at 230 DEG C under a load of 2.16 kg (21.2N); (b) an ordinary temperature xylene insoluble having a stereoregularity index ÄmmmmÜ fraction of 98.9% or higher when measured by <13>C-NMR; and (c) an ordinary temperature xylene soluble characterized by: (c-1) having a content of 22 to 28% by weight; (c-2) comprising only a single component with respect to a relaxation time T1 measured by pulse NMR; and (c-3) satisfying the following formula (I): <DF NUM="(I)">y </= 0.0014x<3> - 0.0897x<2> - 1.0593x + 231.6 </DF> wherein x is an ethylene content (% by weight) measured by <13>C-NMR and y is the relaxation time T1 (msec) measured by pulse NMR.