MVTR resin produced with post-titanated Cr/Si/Ti catalyst
AssigneeChevron Phillips Chemical Company LP
InventorsGene E. Kellum, Kevin J. Taylor, Charles D. Mills, James A. Solis
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Abstract
A process is disclosed for producing polyethylene resin of broad molecular weight distribution, when formed into a film, high barrier to moisture (low MVTR (Moisture Vapor Transmission Rate) for the film). The resin is formed by polymerizing ethylene, preferably in a gas phase process or in a slurry process, using a post-titanated catalyst, that is, a catalyst wherein after initial formation of a catalyst comprising Cr—Ti-inorganic refractory support, further titanium is added to the catalyst in a post-titanation step, preferably to increase the titanium content of the catalyst to a final level preferably between 7 and 9.5 wt. %.
Claims7
A process for polymerizing ethylene to form a polyethylene homopolymer having a MWD greater than 4 and suitable for forming a film having an MVTR less than 0.3 g mil/100 in2/day, which comprises contacting the ethylene under slurry or gas phase reaction conditions with a chromium-silica cogel catalyst containing titanium, wherein the catalyst contains titanium added in at least two steps:
- (1) titanium added as part of a first cogel formation, comprising chromium, titanium and silica, and (2) titanium added in a post-titanation step after the first cogel is formed and dried.
Dependencies are inferred from the claim text.