Patent ID: 7728078

Claim:
A polypropylene composition comprising: 5 to 95 wt % of polypropylene (PP-A) and 95 to 5 wt % of a propylene/1-butene random copolymer (PBR) comprising: (1) 60 to 90 mol % of units derived from propylene and 10 to 40 mol % of units derived from 1-butene, and having (2) a triad isotacticity, as determined from a 13 C-NMR spectrum, of not less than 85% and not more than 97.5%, (3) a molecular weight distribution (Mw/Mn), as determined by gel permeation chromatography (GPC), of from 1 to 3, (4) an intrinsic viscosity, as measured in decalin at 135° C., of from 0.1 to 12 dl/g, (5) a melting point (Tm), as measured on a differential scanning calorimeter, of from 40 to 66.5° C. and a crystallization rate (½ crystallization time) at 45° C. of 10 minutes or less, and satisfying (6) the following relation 146 exp(−0.022 M)≧ Tm≧ 125 exp(−0.032 M) wherein Tm represents a melting point and M (mol %) represents a content of 1-butene constituent units.