Particulate group 4 metallocene-aluminoxane catalyst compositions devoid of preformed support, and their preparation and their use
AssigneeAlbemarle Corporation
InventorSteven P. Diefenbach
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Abstract
Described are solid olefin polymerization catalysts that have, inter alia, very high productivities as shown by a standard test procedure for measuring this property or characteristic, and excellent morphology. Such particulate catalysts can be prepared by prepolymerizing a controlled amount of vinylolefin with a Group 4 metallocene-aluminoxane solution, in which the original metallocene ingredient used in the process has in its molecular structure at least one polymerizable olefinic substituent. These particulate catalysts do not contain, and thus are not produced in the presence of, a preformed support such as an inorganic compound (silica or etc.) or a preformed particulate polymeric support.
Claims19
A self-supported vinylolefin-prepolymerized Group 4 metallocene-aluminoxane particulate catalyst composition devoid of a preformed support and having (i) a mean (average) particle size in the range of about 20 to about 60 microns, (ii) a mean:median particle size ratio in the range of about 0.7:1 to about 1.5:1, and (iii) a productivity, when fresh and if tested in slurry form for productivity with ethylene in a 2-liter autoclave that has been precharged with about one liter of isobutane and that is charged with ethylene to a total pressure of 450 psig at 91.5° C., of at least 12,000 grams of polyethylene per gram of catalyst in one hour, the metallocene having, prior to use in forming said catalyst composition, at least one polymerizable olefinic substituent in the molecule.
A self-supported ethylene-prepolymerized Group 4 metallocene-aluminoxane particulate catalyst composition devoid of a preformed support and having (i) a particle size distribution in which 75% of the catalyst composition has a particle size below 70 microns and 25% of the catalyst composition has a particle size of 70 microns or above, in which 50% of the catalyst composition has a particle size below about 62 microns and 50% of the catalyst composition has a particle size of 62 microns or above, in which 25% of the catalyst composition has a particle size below 45 microns and 75% of the catalyst composition has a particle size of 45 microns or above, and in which no more than 5% of the catalyst composition has a particle size above 400 microns, the foregoing percentages being volume percentages, and (ii) a productivity, when fresh and if tested in slurry form for productivity with ethylene in a 2-liter autoclave that has been precharged with about one liter of isobutane and that is charged with ethylene to a total pressure of 450 psig at 91.5° C., of at least 12,000 grams of polyethylene per gram of catalyst in one hour, the metallocene having, prior to use in forming said catalyst composition, at least one polymerizable olefinic substituent in the molecule.
A process which comprises contacting in an inert organic solvent medium and under polymerization conditions, a controlled amount of at least one vinylolefin monomer with (a) at least one Group 4 metallocene that has at least one polymerizable olefinic substituent in the molecule, and (b) at least one aluminoxane, and/or (c) at least one reaction product formed from (a) and (b), such that prepolymerization occurs and there is formed a self-supported particulate catalyst composition devoid of any preformed support and having (i) a mean (average) particle size in the range of about 20 to about 60 microns, (ii) a mean:median particle size ratio in the range of about 0.7:1 to about 1.5:1, and (iii) a productivity, when fresh and if tested in slurry form for productivity with ethylene in a 2-liter autoclave that has been precharged with about one liter of isobutane and that is charged with ethylene to a total pressure of 450 psig at 91.5° C., of at least 12,000 grams of polyethylene per of catalyst in one hour.
A process which comprises contacting in an inert organic solvent medium and under polymerization conditions, a controlled amount of ethylene with (a) at least one zirconium metallocene that has at least one polymerizable olefinic substituent in the molecule, and (b) at least one aluminoxane, and/or (c) at least one reaction product formed from (a) and (b), such that prepolymerization occurs and there is formed a self-supported particulate catalyst composition devoid of any preformed support, and having (i) a mean (average) particle size in the range of about 20 to about 60 microns, (ii) a mean:median particle size ratio in the range of about 0.7:1 to about 1.5:1, (iii) a particle size distribution in which 75% of the catalyst composition has a particle size below 70 microns and 25% of the catalyst composition has a particle size of 70 microns or above, in which 50% of the catalyst composition has a particle size below about 62 microns and 50% of the catalyst composition has a particle size of 62 microns or above, in which 25% of the catalyst composition has a particle size below 45 microns and 75% of the catalyst composition has a particle size of 45 microns or above, and in which no more than 5% of the catalyst composition has a particle size above 400 microns, the foregoing percentages being volume percentages, and (iv) a productivity, when fresh and if tested in slurry form for productivity with ethylene in a 2-liter autoclave that has been precharged with about one liter of isobutane and that is charged with ethylene to a total pressure of 450 psig at 91.5° C., of at least 12,000 grams of polyethylene per gram of catalyst in one hour.
Dependencies are inferred from the claim text.