US 6,982,304 B2 | ||
Blow molding resins with improved ESCR | ||
Cliff Robert Mure, Hillsborough, N.J. (US); Guylaine St. Jean, Somerset, N.J. (US); Stephen Paul Jaker, Colonia, N.J. (US); Robert J. Jorgensen, Scott Depot, W. Va. (US); and Karen Breetz, Morgantown, W. Va. (US) | ||
Assigned to Union Carbide Chemicals & Plastics Technology Corporation, Danbury, Conn. (US) | ||
Filed on Dec. 22, 2003, as Appl. No. 10/743,500. | ||
Prior Publication US 2005/0137365 A1, Jun. 23, 2005 | ||
Int. Cl. C08F 4/69 (2006.01); C08F 4/78 (2006.01); C08F 210/16 (2006.01) |
U.S. Cl. 526—106 | 32 Claims |
1. A process to produce an ethylene polymer, the process comprising the steps of:
blending at least one chromium oxide catalyst carried on a first support, the chromium oxide catalyst including compounds
calcinable to chromium oxide at conditions used to activate the chromium oxide catalyst, and at least one silyl chromium catalyst
carried on a second support to form a catalyst mixture, wherein the chromium oxide catalyst is present in an amount from about
25 to about 50 weight percent based on the total weight of the catalyst mixture and the silyl chromium catalyst is present
in an amount of about 50 to about 75 weight percent based on the total weight of the catalyst mixture;
introducing the catalyst mixture into a polymerization reactor, wherein at least one monomer comprising ethylene is present
in the reactor and the reactor is maintained at polymerization conditions such that the at least one monomer will polymerize
in the presence of the catalyst mixture;
activating the chromium oxide catalyst either before or after the blending step but prior to introducing the catalyst mixture
into the reactor; and,
contacting the catalyst mixture and the at least one monomer in the reactor such that an ethylene polymer is formed,
wherein the ethylene polymer is characterized, in comparison to an ethylene polymer prepared under the same polymerization
conditions in the presence of the chromium oxide catalyst only, by an increase in environmental stress crack resistance (ESCR)
at least about 400% and an increase in swell of no more than about 15%.
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