Patent ID: 6262199
Filing Date: 2001-07-17
Classification: C08F,Y10S

Abstract:
A process for the polymerization of olefins of at least three carbon atoms comprising:(a) selecting a predominantly racemic stereorigid metallocene described by the formula:R""(CpR.sub.2 C.sub.4 R.sub.4)(CpR'.sub.2 C.sub.4 R'.sub.4)MeQ.sub.kwherein (CpR.sub.2 C.sub.4 R.sub.4) and (CpR'.sub.2 C.sub.4 R'.sub.4) are substituted indenyl rings; each R and R' is a hydrogen or hydrocarbyl radical having 1-20 carbon atoms, each R being the same or different, each R' also being the same or different, one R and R' being a hydrocarbyl radical having 1-20 carbon atoms in a proximal position adjacent to the bridgehead carbon of the indenyl rings; R"" is a structural bridge between the two indenyl rings imparting stereorigidity to the indenyl rings; Me is a Group IVB, Group VB, or Group VIB transition metal; and each Q is a hydrocarbyl radical or is a halogen and k is the valence of Me minus 2; and(b) forming a catalyst by contacting the metallocene with a cocatalyst or a Lewis acid ionic ionizing agent;(c) bringing the catalyst in contact with an alpha olefin of at least three carbon atoms under polymerization conditions; and(d) extracting isotactic polyolefin.