Reversible chain-transfer in polyolefin polymerization with pyridyldiamide catalysts

摘要

A process of producing ethylene α-olefin copolymers, especially ethylene block copolymers, comprising contacting ethylene and a C3 to C10 α-olefin with a transition metal pyridyldiamide (MPN3) catalyst component and an activator, as well as from 10 equivalents to 1000 equivalents relative to the catalyst component of chain transfer agent; isolating an ethylene-α-olefin copolymer having a Tm of less than 140° C., a MWD of less than 2.5, and a weight average molecular weight (Mw) within the range of from 5 kDa to 500 kDa. The chain transfer agent can be selected from Group 2, 12 or Group 13 alkyl or aryl compounds.

主权项

1. A process of producing ethylene α-olefin copolymers comprising:
contacting ethylene and a C3 to C10 α-olefin with a transition metal pyridyldiamide catalyst component and an activator, as well as from 10 equivalents to 1000 equivalents relative to the catalyst component of chain transfer agent;
isolating an ethylene-α-olefin copolymer having a Tm of less than 140° C., a Mw/Mn of less than 2.5, and a weight average molecular weight (Mw) within the range of from 5 kDa to 500 kDa, wherein the contacting first takes place in the absence of the chain transfer agent and ethylene-α-olefin copolymer is first isolated having a weight average molecular weight (Mw) within the range of greater than 200 kDa; followed by addition of the chain transfer agent and isolation of ethylene-α-olefin copolymer having a Mw of less than 400 kDa.