Patent ID: 7943717

Claim:
Butene-1 copolymers comprising a content from 0.1 to 40% by mole of at least one comonomer, the comonomer being selected from ethylene, propylene, or mixtures thereof, the butene-1 copolymers further comprising: a) a product of the reactivity ratios r1·r2≦1.5; b) a content of butene-1 units in form of isotactic pentads (mmmm)>98.5%; and c) an absence of 4,1 insertions of butene units, the butene-1 copolymers being produced by a process comprising copolymerizing butene-1 and the at least one comonomer in the presence of a stereospecific catalyst comprising: (A) a solid catalyst component comprising a Ti compound of formula Ti(OR) n-y X y , where n=4; X is a halogen; and y is a number from 1 to n, and an electron-donor compound selected from phthalates, supported on MgCl 2 ; (B) an alkylaluminum compound; and (C) a thexyltrimethoxysilane external donor.