Patent ID: 8097681

Claim:
A 1-butene/propylene copolymer composition comprising a content of propylene derived units from 1 to 4% by weight, a) from 5% by weight to 95% by weight of an atactic 1-butene propylene copolymer comprising: i) a distribution of molecular weight Mw/Mn equal to or lower than 4; ii) rr triads, measured by 13 C-NMR, between 10% and 40%; iii) no enthalpy of fusion detectable at a differential scanning calorimeter (DSC); and iv) an infrared crystallinity lower than 0.5%; and b) from 5% by weight to 95% by weight of an isotactic 1-butene propylene comprising: i) isotactic pentads (mmmm), measured by 13 C-NMR, higher than 80%; ii) a melting point (Tm(II) form II) higher than 70° C.; and iii) a distribution of molecular weight Mw/Mn equal to or lower than 4, the copolymer composition having a crystalline polymer fraction wherein at least 50% of the crystalline polymer is present in a thermodynamically stable, trigonal Form I (detected by DSC analysis) after 100 hours of a first melting at room temperature.