Processes for producing high density polyethylene

Abstract

Processes for reducing the ultra high molecular weight polymeric material content of a high density polyethylene produced with a bis-triarylsilyl chromate catalyst system are provided. Processes for reducing the gel content of articles produced from high density polyethylene are also provided. The gel content of the articles is reduced by using the high density polyethylene with reduced ultra high molecular weight polymeric material content to produce the articles. The processes described reduce the content of ultra high molecular weight polymeric material in comparison to conventional high density polyethylene by introducing at least one catalyst deactivator into a recycle gas line containing a recycle gas stream associated with the fluidized bed reactor. The at least one catalyst deactivator has a boiling point lower than the maximum temperature within the recycle gas line. In certain embodiments, the at least one catalyst deactivator is introduced in the portion of the recycle gas line upstream of a recycle gas cooler at a ratio of 0.0075 mole of the at least one catalyst deactivator per 1 million moles of make-up ethylene to about 0.12 mole of the at least one catalyst deactivator per 1 million moles of make-up ethylene in the reaction system. In certain embodiments, the at least one catalyst deactivator is oxygen.

Dependencies are inferred from the claim text.