Propylenic copolymer, and its film

A propylenic copolymer (A) of propylene and ethylene, that satisfies the following conditions (1) to (5):

• (1) The ethylene unit content (xa, wt. %) of the copolymer is from 3 to 10 wt. %;
• (2) The relation between the boiling diethyl ether extraction (Ea, wt. %) of the copolymer and xa satisfies the formulae (I) or (II):
• Ea≦0.25xa+1.1(xa=3 to 6 wt. %) (I)
• Ea≦2.6(xa=6 to 10 wt. %);
• (II)
• (3) The relation between the melting point ([Tm]Tma, ° C.) of the copolymer as measured with a differential scanning calorimeter and xa satisfies the formulae (III) or (IV):
• Tma≦140(xa=3 to 4 wt. %) (III)
• Tma≦160−5xa(xa=4 to 10 wt. %);
• (IV)
• (4) The copolymer has a melt index (MI. g/10 min.) of from 4 to 12 g/10 min., measured at a temperature of 230° C. under a load of 2160 g, according to JIS K7210;
• and
• (5) The isotactic triad fraction in the PPP sequence of the copolymer, as measured in 13C-NMR, is not smaller than 98.0 mol %.