Olefin polymerization process
AssigneePhillips Petroleum Company
InventorsAshish M. Sukhadia, Elizabeth A. Benham, Joseph J. Bergmeister, Rex L. Bobsein, Gerhard K. Guenther, Eric T. Hsieh, Max P. McDaniel, Steven J. Secora, Joseph S. Shveima, John D. Stewart
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Abstract
A copolymer of ethylene and a higher alpha-olefin having broadened melt processing windows and reduced melt fracture can be produced using a chromium-containing catalyst system and a trialkyl boron cocatalyst. The polymerization process must be carefully controlled to produce a copolymer resin that easily can be made into articles of manufacture.
Claims9
A polymerization process comprising contacting in a reaction zone, at a temperature within a range of about 180° F. to about 215° F., in the absence of hydrogen:
- a) ethylene monomer;
- b) at least one mono-1-olefin comonomer having from about 2 to about 8 carbon atoms per molecule;
- c) a catalyst system comprising chromium supported on a silica-titania support, wherein said support comprises from about 2 to about 10 weight percent titanium, based on the weight of the support, and wherein said catalyst system has been activated in oxygen at a temperature within a range of about 900° F. to about 1050° F. and has not been subjected to a reduction treatment;
- and
- d) a trialkyl boron compound;
- and recovering an ethylene/mono-1-olefin copolymer, wherein the ethylene/mono-1-olefin copolymer has a critical shear rate for the onset of melt fracture greater than about 1900 sec−1.
Dependencies are inferred from the claim text.