Method for producing a high-density polyethylene of high melt index ratio and low oligomer content

摘要

A process for producing a high density polyethylene resin which has a negligible oligomer content while having a melt index ratio of at least 75 by polymerizing ethylene with a minor amount of an aliphatic diene in the presence of a supported organophosphorous modified vanadium-containing catalyst component. Vanadium-containing catalyst components useful with an organoaluminum cocatalyst for polymerizing ethylen with an aliphatic diene to produce high density resins having not only a low C10-C32 oligomer content (characteristic of high molecular weight polymers having a narrow molecular weight distribution), but, surprisingly, also a melt index ratio desirable for melt blowing applications more characteristic of vanadium catalyzed polymers (which have relatively high oligomer content), are obtained by contacting an inert support material with an organoaluminum compound, an optional halogenating agent, a vanadium compound, and an organophosphorous compound. An aliphatic diene containing at least four carbon atoms in which at least one of the double bonds is in a terminal position is used to copolymerize with ethylene.