Single site catalyst with methyl aluminoxane or borate free and their applications for the preparation of polyolefins

摘要

A novel organometallic compound is disclosed which can be used, in conjunction with a trialkyl or bialkyl aluminum cocatalyst, for catalyzing the polymerization and copolymerization of ethylene without requiring the use of either methyl aluminoxane or borate as cocatalyst. The organometallic compound is represented by the formula of (C5RnH5-n)(L)MXaYb; wherein: (a) C5RnH5-n is a substituted or unsubstituted cyclopentadienyl group, in which n is an integer between 0 and 5, and R is C1 to C6 alkyl group; (b) L is tetrapyrazolyl borate, hydrotrispyrazolyl borate, dihydrobispyrazolyl borate or hydrotris(3,5-dimethylpyrazolyl) borate; (c) M is a Group IIIB, Grcup IVB, or Group VB transitional metal; (d) a and b are integers such that a+b=m-2, where m is the valance of M; and (e) X and Y, which can be the same of different from each other, are halogen atoms or ligands represented by the formula of ER1 or ER1R2, where E is a Group VA or VIA element, and R1 and R2, which can be the same or different from each other, are C1 to C6 alkyl group or substituted aryl group. Preferably, M is a Group IVB transitional metal and a=b=1, and the organometallic compound is then represented by the formula of (C5RnH5-n)(L)MXY.