Patent ID: 8227563

Claim:
A process for the preparation of 1-butene homopolymers or 1-butene/alpha olefin copolymers containing 0.1 to 20% by mol of alpha olefin, wherein the alpha olefins are selected from ethylene, propylene or alpha olefins of formula CH 2 ═CHZ wherein Z is a C 3 -C 20 alkyl radical, the process comprising contacting 1-butene and optionally at least one alpha olefin under polymerization conditions, in the presence of a catalyst system comprising: (a) a solid component comprising a Ti compound and an internal electron-donor compound supported on MgCl 2 ; (b) an alkylaluminum cocatalyst; and (c) a compound of formula (I) as external donor wherein: R 1 , R 2 , R 3 and R 4 , equal to or different from each other, are hydrogen atoms or C 1 -C 20 hydrocarbon radicals optionally containing heteroatoms belonging to groups 13-17 of the Periodic Table of the Elements; or two R 1 , R 2 , R 3 and R 4 can be joined to form a C 5 -C 20 , saturated or unsaturated ring, said ring can be substituted by C 1 -C 10 hydrocarbon radicals optionally containing heteroatoms belonging to groups 13-17 of the Periodic Table of the Elements, and the 1-butene homopolymers or 1-butene/alpha olefin copolymers containing 0.1 to 20% by mol of alpha olefin, have mmmm pentads between 10% and 50%, and do not show 4,1 inserted butene units.