Dual catalyst systems for producing polymers with a broad molecular weight distribution and a uniform short chain branch distribution

摘要

Disclosed herein are ethylene-based polymers having a melt index less than 50 g/10 min, a ratio of Mw/Mn from 4 to 20, a density from 0.90 to 0.945 g/cm3, and a substantially constant short chain branch distribution. These polymers can be produced using a dual catalyst system containing a boron bridged metallocene compound with a cyclopentadienyl group and an indenyl group, and a single atom bridged metallocene compound with a fluorenyl group.

主权项

1. A polymerization process, the process comprising:
contacting a catalyst composition with ethylene and an α-olefin comonomer in a polymerization reactor system under polymerization conditions to produce an ethylene/α-olefin copolymer, wherein the catalyst composition comprises catalyst component I, catalyst component II, an activator, and an optional co-catalyst, wherein: catalyst component I comprises a boron bridged metallocene compound with a cyclopentadienyl group and an indenyl group; and catalyst component II comprises a single atom bridged metallocene compound with a fluorenyl group; and the ethylene/α-olefin copolymer is characterized by a slope of a plot of the number of short chain branches per 1000 total carbon atoms versus the logarithm of molecular weight of the copolymer, determined via linear regression over the range from D15 to D85, in a range from about −0.6 to about 0.6.