摘要:
Polyethylene compositions having improved properties are provided. In one aspect, a polyethylene composition having a long chain branching index (g′avg) of 0.5 to 0.9; a Melt Flow Rate (MFR) of greater than (49.011×MI(−0.4304)), where MI is Melt Index; and a weight average molecular weight to number average molecular weight (Mw/Mn) of less than or equal to 4.6 is provided.
摘要:
A process for polymerizing olefin(s) utilizing a cyclic bridged metallocene catalyst system to produce polymers with improved properties is provided. The catalyst system may include a cyclic bridged metallocene, LA(R′SiR′)LBZrQ2, activated by an activator, the activator comprising aluminoxane, a modified aluminoxane, or a mixture thereof, and supported by a support, where: LA and LB are independently an unsubstituted or a substituted cyclopentadienyl ligand bonded to Zr and defined by the formula (C5H4-dRd), where R is hydrogen, a hydrocarbyl substituent, a substituted hydrocarbyl substituent, or a heteroatom substituent, and where d is 0, 1, 2, 3 or 4; LA and LB are connected to one another with a cyclic silicon bridge, R′SiR′, where R′ are independently hydrocarbyl or substituted hydrocarbyl substituents that are connected with each other to form a silacycle ring; and each Q is a labile hydrocarbyl or a substituted hydrocarbyl ligand.
摘要:
Bimodal polyethylene compositions and methods for making the same are provided. In at least one specific embodiment, the bimodal polyethylene composition can include a high molecular weight component having a weight average molecular weight (Mw) of from about 400,000 to about 950,000. The bimodal polyethylene composition can also include a low molecular weight component having a weight average molecular weight (Mw) of from about 3,000 to about 100,000. The high molecular weight component can be present in an amount ranging from about 25 wt % to about 40 wt % of the bimodal polyethylene composition. The bimodal polyethylene composition can also have a percent die swell of less than about 80%.
摘要:
Bimodal polyethylene compositions and methods for making the same are provided. In at least one specific embodiment, the bimodal polyethylene composition can include a high molecular weight component having a weight average molecular weight (Mw) of from about 400,000 to about 950,000. The bimodal polyethylene composition can also include a low molecular weight component having a weight average molecular weight (Mw) of from about 3,000 to about 100,000. The high molecular weight component can be present in an amount ranging from about 25 wt % to about 40 wt % of the bimodal polyethylene composition. The bimodal polyethylene composition can also have a percent die swell of less than about 80%.
摘要:
Catalyst systems and methods for making and using the same. The catalyst system can include a single site catalyst compound, a support comprising fluorinated alumina, and an aluminoxane. The aluminoxane can be present in an amount of about 10 mmol or less per gram of the support.
摘要:
Normally sparingly soluble magnesium alkoxide is solubilized in alkanol by the additional presence of certain acidic materials. The resulting solution is used to produce a mixture of substantially spherical particles, substantially free of fines, containing an adduct magnesium alkoxide. The particles are converted by conventional methods to a procatalyst precursor of an olefin polymerization catalyst of good activity and good selectivity to stereoregular polymer whenever appropriate, which catalyst produces polymer product of good morphology.
摘要:
A method for controlling a transition from an initial polymerization reaction to a target polymerization reaction in a manner that reduces significantly the amount of off-grade product having excessively low density produced during the transition, including steps of: during the transition, maintaining a first one of a concentration ratio and a feed ratio at an at least substantially constant value while implementing process changes in an effort to bring produced polymer into compliance with a target specification set and monitoring (without controlling) the other one of the concentration ratio and the feed ratio to generate first data; and during the transition, determining from the first data whether polymer having excessively low density is likely to be produced during the transition, and upon determining that polymer having excessively low density is likely to be produced during the transition, maintaining during the remaining portion of the transition the other ratio at a value that is at least substantially constant while allowing the first ratio to vary is provided.
摘要:
A process is provided for preparing a shape-shifted catalyst component comprising (1) contacting a dihydrocarbyloxide magnesium compound with carbon dioxide in the presence of a slurrying agent to form a slurry of a carboxylated dihydrocarbyloxide magnesium compound; (2) adding a filler to the slurry either before or after the carboxylation of step (1); (3) spray drying the slurry of step (2) to evaporate the slurrying agent and to produce solid particles of the carboxylated dihydrocarbyloxide magnesium compound incorporating the filler; and, optionally, (4) heating the solid particles to remove carbon dioxide to produce a shape-shifted dihydrocarbyloxide magnesium compound component. A catalyst system using the component and a polymerization process employing the catalyst system are also provided.
摘要:
A process comprising contacting a mixture comprising ethylene, propylene, and, optionally, a diene, in the gas phase, under polymerization conditions, with a catalyst system comprising:(a) a catalyst precursor, in independent or prepolymer form, consisting of vanadium (acetylacetonate).sub.3 ;(b) optionally, a support for said precursor;(c) a cocatalyst consisting essentially of (i) an alkylaluminum halide having the formula AlR.sub.(3-a) X.sub.a wherein each R is independently alkyl having 1 to 14 carbon atoms; each X is independently chlorine, bromine, or iodine; and a is 1 or 2, and (ii) optionally, a trialkylaluminum provided that the molar ratio of alkylaluminum halide to trialkylaluminum is at least about 1.5:1; and(d) optionally, a promoter, which is a chlorinated ester having at least 2 chlorine atoms; a saturated or unsaturated aliphatic halocarbon having at least 3 carbon atoms and at least 6 halogen atoms; or a haloalkyl substituted aromatic hydrocarbon wherein the haloalkyl substituent has at least 3 halogen atoms.
摘要:
Spray-dried catalyst compositions comprising a transition metal complex and polymerization processes employing the same are disclosed herein. An embodiment provides a spray-dried catalyst composition comprising a transition metal catalyst component represented by the following formula: (I) and polymerization process employing the same.