| 摘要 |
A new improved catalyst system for alpha-olefin type polymerizations, includes at least one metal alkyl compound having the formula R'''M in combination with a Group IVB-VIII transition metal compound on a support and at least one hindered Lewis base and one unhindered Lewis base and a Group IA-IIIA metal salt of a sterically hindered carboxylate, alkoxide or aryloxide, wherein R''' is selected from the group consisting of C1 to C20 primary alkyl, alkenyl or aralkyl groups, or a hydride, and M is selected from the group consisting of aluminum, gallium, or indium. The improved catalyst system provides polymers having increased isotactic stereoregularity as well as lower catalyst residue.
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