The present invention provides polymerization catalyst compounds, catalyst
systems including these catalyst compounds, and to their use in the
polymerization of ethylene and at least one comonomer. In particular, the
invention provides a catalyst system comprising a poor comonomer
incorporating catalyst compound and a good comonomer incorporating
catalyst compound. Preferably, the low comonomer incorporating catalyst
compound is a metallocene containing at least one substituted or
unsubstituted fused ring cyclopentadienyl based ligand which is
substantially directed to the front of the molecule, contains a long
bridging group, or which contains a methyl substitution pattern which
correlates to poor comonomer incorporation. The invention also provides
methods of selecting the poor comonomer incorporating metallocene to pair
with the good comonomer incorporating metallocene to produce polymers
that are easy to process into a variety of articles, especially
polyethylene based film, having enhanced properties.