摘要:
The present techniques relate to catalyst compositions, methods, and polymers encompassing a Group 4 metallocene compound comprising bridging η5-cyclopentadienyl-type ligands, typically in combination with a cocatalyst, and a activator. The compositions and methods presented herein include ethylene polymers with low melt elasticity.
摘要:
This invention relates to the field of olefin polymerization catalyst compositions, and methods for the polymerization and copolymerization of olefins, including polymerization methods using a catalyst composition. One aspect of this invention is the formation and use of a catalyst composition comprising a transition metal compound and an activator for olefin polymerization processes.
摘要:
This invention relates to catalyst compositions comprising a first metallocene compound, a second metallocene compound, at least one chemically-treated solid oxide, and at least one organoaluminum compound. This invention also relates to methods to prepare and use the catalyst compositions and new polyolefins. The compositions and methods disclosed herein provide ethylene polymers and copolymers with lower MI, increased melt strength, and good MD tear properties.
摘要:
A polymer having a long chain branching content peaking at greater than about 20 long chain branches per million carbon atoms, and a polydispersity index of greater than about 10 wherein the long chain branching decreases to approximately zero at the higher molecular weight portion of the molecular weight distribution. A polymer having a long chain branching content peaking at greater than about 8 long chain branches per million carbon atoms, a polydispersity index of greater than about 20 wherein the long chain branching decreases to approximately zero at the higher molecular weight portion of the molecular weight distribution. A polymer having a long chain branching content peaking at greater than about 1 long chain branches per chain, and a polydispersity index of greater than about 10 wherein the long chain branching decreases to approximately zero at the higher molecular weight portion of the molecular weight distribution.
摘要:
Polymerization reactor systems providing real-time control of the average particle size of catalyst system components are disclosed. Methods for operating such polymerization reactor systems also are described.
摘要:
A method comprising (a) contacting a support and a chromium-containing compound to form chromium-containing support, (b) heat treating the chromium-containing support in an oxidizing atmosphere to form a treated support, (c) contacting the treated support with carbon monoxide to form a CO-contacted support, and (d) contacting the CO-contacted support with hydrogen to form a catalyst. A method comprising oxidizing a chromium-treated support to form a polymerization catalyst, contacting the polymerization catalyst with carbon monoxide to form a reduced polymerization catalyst, contacting the reduced polymerization catalyst with hydrogen to form an activated polymerization catalyst, and contacting the activated polymerization catalyst with ethylene in a reaction zone under suitable reaction conditions to form a random copolymer. A method comprising reducing a polymerization catalyst comprising Cr(VI) to form a polymerization catalyst comprising Cr(II), and treating the polymerization catalyst comprising Cr(II) with hydrogen.
摘要:
A method comprising contacting a support with a chromium-containing compound and a tin-containing compound to produce a catalyst precursor, and activating the catalyst precursor in a temperature range of from about 400° C. to about 700° C. to produce a polymerization catalyst. A method comprising contacting a support with a chromium-containing compound and a tin-containing compound to produce a catalyst precursor, activating the catalyst precursor in a temperature range of from about 400° C. to about 700° C. to produce a polymerization catalyst, and contacting the polymerization catalyst with ethylene in a reaction zone under suitable reaction conditions to form polyethylene wherein the molecular weight distribution of the polyethylene is broadened.
摘要:
Methods and systems for preparing catalyst, such as chromium catalysts, are provided. The valence of at least a portion of the catalyst sent to an activator is changed from Cr(III) to Cr(VI). The catalyst is prepared or activated continuously using a fluidization bed catalyst activator.
摘要:
A system and method for activating chromium catalyst, including: increasing temperature of a chromium catalyst at a first rate for a first period of time to a first temperature; and increasing temperature of the chromium catalyst at a second rate for a second period of time from the first temperature to a second temperature, wherein the first rate is greater than the second rate, and wherein the first period precedes the second period.
摘要:
A polymeric resin having a density of greater than about 0.960 g/cc, a melt index of from about 1.3 g/10 min. to about 2.8 g/10 min., a zero shear viscosity of from about 1×104 Pa*s to about 1×105 Pa*s, a recoverable shear parameter of from about 220 to about 370, and a CY-a parameter of from about 0.155 to about 0.200. A polymeric resin having an initial tension defined by the equation IT≧−1.67*(MI)+b where b is 5.17 and a percent decrease in the extrusion pressure of the resin of about 30% when compared to polymer resin of similar melt index prepared with a catalyst that has not undergone an activation comprising an oxidation, reduction, oxidation sequence wherein the resin when formed into a film has a moisture vapor transmission rate of from about 0.21 g.mil/100 in2/day to about 0.33 g.mil/100 in2/day.