Polymerization process

摘要

The invention relates to a polymerization process, the polymerization process includes contacting
a cyclic bridged metallocene catalyst represented by the following formula:
LA(A)LBMQn wherein A is a divalent group bound to each of LA and LB; each of LA andLB are bound to M, and each Q is bound to M;LA and LB are independently selected from the group consisting of cyclopentadienyl ligands and substituted cyclopentadienyl ligands;A is a divalent bridging group comprising a heterocyclic ring comprising from 3 to 6 carbon atoms and one silyl, thus forming a 4 to 7 member divalent ring;M is a Group 4, 5, or 6 transition metal;Q is independently a halogen, a hydride, or a hydrocarbyl radical having from 1 to 20 carbon atoms; wherein n is 1 or 2;
with an activator, and optionally a support, to form an activated catalyst and, subsequently, contacting the activated catalyst with ethylene and optionally, at least one C3-C8 alpha olefin comonomer.

主权项

1. A polymerization process, the polymerization process comprising contacting ethylene and, optionally, at least one C3-C8 alpha olefin comonomer, with an activated mixed catalyst system in a polymerization reactor,
wherein the mixed catalyst system comprises:
(a) a first catalyst component that comprises a cyclic bridged metallocene catalyst, an activator, and optionally a support; wherein the cyclic bridged metallocene catalyst is represented by the following formula:
LA(A)LBMQn wherein A is a divalent group bound to each of LA and LB; each of LA and LB are bound to M, and each Q is bound to M;LA and LB are independently selected from the group consisting of cyclopentadienyl ligands and substituted cyclopentadienyl ligands;A is a cyclotetramethylenesilyl group, thus forming a divalent ring;M is zirconium or hafnium;Q is independently chlorine or fluorine;wherein n is 1 or 2;(b) a second catalyst component that comprises a bridged metallocene compound represented by the following formula:
R1R2ELALBMQn wherein R1 and R2 are each bound to E, and E is bound to each of LA and LB; each of LA and LB are bound to M, and each Q is bound to M;LA and LB are independently selected from the group consisting of cyclopentadienyl ligands and substituted cyclopentadienyl ligands;wherein the R1R2E group forms a divalent bridging group, wherein E is silicon or germanium; wherein R1 and R2 are independently C1 to C5 alkyls;M is zirconium or hafnium; wherein n is 1 or 2; and Q is chlorine or fluorine; wherein the first catalyst component is capable of producing a polymer with a melt flow ratio I21/I2 measured according to ASTM 1238 Conditions E and F at 190° C., of 35 or more and the second catalyst component is capable of producing a polymer with a melt flow ratio of 50 or less; and wherein the activated mixed catalyst system is introduced to the polymerization reactor as a slurry comprising the mixed catalyst system in a mineral oil or silicon oil.