| 摘要 |
PROBLEM TO BE SOLVED: To provide a propylenic block copolymer which exhibits good flowability and an excellent balance between impact resistance and flexural modulus, and permits selection of more advantageous molding conditions. SOLUTION: The propylenic block copolymer comprises a propylene polymer component satisfying (A) an isotactic pentad ratio (mmmm) of at least 98.0%, and anα-olefin/propylene copolymer component satisfying (B) a content of the copolymer component of 5-50 wt.% and anα-olefin content in the copolymer component of 20-70 wt.%, and satisfies (C) (C-1) the weight-average mol.wt. (Mw) to number-average mol.wt (Mn) ratio of at least 8 and (C-2) a melting point [Tm ( deg.C)] measured by the DSC and the isotactic pentad ratio (mmmm) of the propylene polymer component satisfying the equation: 155<=Tm<=2.5×(mmmm)-85.
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