PROPYLENE-ETHYLENE BLOCK COPOLYMER

摘要

PROBLEM TO BE SOLVED: To obtain a propylene-ethylene block copolymer excellent in balance of impact resistance and rigidity and improved in surface hardness. SOLUTION: In this propylene-ethylene block copolymer, heat of fusion (ΔHm) obtained from differential scanning calorimetry(DSC) of the cold xylene-insoluble part and MFR satisfy the relationship of the equationΔHm>=24.50+1.583 log MFR and a ratio of tanδarea (at <=-30 deg.C) of the propylene-ethylene block copolymer to the weight fraction of the cold xylene-soluble part satisfies the relationship of the equation (tanδarea/weight fraction of cold xylene-soluble part) >=0.6.