Bimetallic metallocene alumoxane catalyst system and its use in the preparation of ethylene-alpha olefin and ethylene-alpha olefin-non-conjugated diolefin elastomers

Claim 1

A catalyst system comprising: (A) a group IV B transition metal component having the general formula ##STR10## wherein M is zirconium, hafnium or titanium; each R 1 which can be the same or different is an alkyl, alkenyl, aryl, alkylaryl or arylalkyl group having from 1 to 20 carbon atoms or two adjacent R 1 are joined together forming a ring system having from 4 to 20 carbon atoms; ##STR11## wherein M 2 is carbon or silicon; each R 21 which can be the same of different is an alkyl, aryl, alkylaryl or arylalkyl group having from 1 to 8 carbon atoms or can be hydrogen when M 2 is carbon, R 22 is a linear branched or cyclic alkylene having from 4 to 12 carbon atoms or is a phenylene group or 2 or 3 phenylene groups coupled in the 1 and 4 positions; R 3 is a dialkyl substituted silanylene, a diaryl substituted silanylene, an alkyl, aryl substituted silanylene, a linear, branched or cyclic alkylene having from 1 to 4 carbon atoms when R 2 is present, and is a dialkyl substituted silanylene, a diaryl substituted silanylene or an alkyl aryl substituted silanylene when R 2 is not present, R 4 is a linear, branched or cyclic alkylene having from 4 to 12 carbon atoms or is a phenylene group or 2 or 3 phenylene groups coupled to one another in the 1 to 4 positions; each L independently is a hydrocarbyl group having from 1 to 20 carbon atoms, an alkoxide or aryloxide having from 1 to 8 carbon atoms, a halogen atom or hydrogen atom; x, a and b are 0 or 1 with the conditions that a and b cannot both be 1 at the same time and when x=0, a=1 and b=0, y and z which denote the degree of substitution of the cyclopentadienyl rings have the values from 0 to 4 and 0 to 5 respectively; when x=1, a=1 and b=0, y has the value from 0 to 3 and z has the value from 0 to 4; when x=1, a=0 and b=1, both y and z can have any value from 0 to 4; and (B) an alumoxane.