| 摘要 |
A polypropylene-based copolymer containing 50 to 95% by weight of a polymer component comprising 95% by weight or more of the constitutional unit derived from propylene and having a melting point exceeding 155° C. (component A) and 5 to 50% by weight of a copolymer component of propylene, ethylene and an α-olefin having 4 or more carbon atoms (component B) in which the content of the constitutional unit derived from propylene (X) is 10% by weight≦̸X<50% by weight, the content of the constitutional unit derived from ethylene (Y) is 50% by weight<Y≦̸70% by weight, the content of the constitutional unit derived from an α-olefin having 4 or more carbon atoms (Z) is 0% by weight<Z≦̸20% by weight, provided that the sum total of X, Y and Z is 100% by weight, and the ratio of Z to X is 1 or less.
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