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US 12,502,656 B2Granted
Methods of chromium catalyst activation to reduce gels and improve melt index potential
AssigneeChevron Phillips Chemical Company LP
InventorsMax P. McDaniel, Zhihui Gu, Ted H. Cymbaluk, Anand Ramanathan, Julian Abrego, Taryn L Huber, David W. Dockter
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Abstract
Processes for producing activated chromium catalysts such as titanated chromium/silica catalysts are disclosed, and these processes utilize a multistep process involving exposure to inert and oxidizing atmospheres at specific temperature conditions. The resulting activated chromium catalysts have unexpectedly high melt index potential and can produce ethylene-based polymers with lower gel counts in addition to higher melt indices.
Claims21
An ethylene polymer having:
- a melt index (MI) in a range from 0.1 to 1 g/10 min and/or a high load melt index (HLMI) in a range from 10 to 80 g/10 min;
- a density in a range from 0.93 to 0.96 g/cm3;
- and
- a total film gel count of less than or equal to 40 gels per ft2 of 25 micron thick film, wherein film gels encompass a size in diameter of greater than 200 μm;
- wherein the ethylene polymer contains:
- from 150 to 680 ppm silica;
- from 1.5 to 6.8 ppm chromium;
- and
- from 1.5 to 40 ppm titanium.
6 more elements
Dependencies are inferred from the claim text.