Patent ID: 6160072
Filing Date: 2000-12-12
Classification: C08F

Abstract:
A process comprising the step of contacting, in a condensed phase, propylene with at least one titanocene catalyst/catalyst precursor of formula (I):ZR""Z'TiQ.sub.k A.sub.l (I)where:(a) Z and Z' are the same or different and are a cyclopentadienyl containing ligand or a heterocyclic analog of a cyclopentadienyl containing ligand;(b) R"" is a structural bridge;(c) Q is a linear or branched alkyl radical, an aryl radical, an alkenyl radical, an alkylaryl radical, an arylalkyl radical or a halogen atom;(d) A is a counterion;(e) k is an integer having a value from 1 to 3;(f) 1 is an integer having a value from 0 to 2;(g) Z and Z' have at least one .beta. substituent sterically larger than a hydrogen atom;(h) the ZR""Z' ligand system has C.sub.2 or near C.sub.2 symmetry;(i) the process generates isotactic polypropylene having a melting point above about 158.degree. C. at a temperature greater than or equal to about 50.degree. C. and at a pressure sufficient to maintain the contacting in the condensed phase.