摘要:
Bimetallic catalysts, and methods of producing a bimetallic catalyst comprising a modified Ziegler-Natta catalyst and a metallocene are provided, in one embodiment the method including combining: (a) a Ziegler-Natta catalyst comprising a Group 4, 5 or 6 metal halide and/or oxide, optionally including a magnesium compound, with (b) a modifier compound (“modifier”), wherein the modifier compound is a Group 13 alkyl compound, to form a modified Ziegler-Natta catalyst. Also provided is a method of olefin polymerization using the bimetallic catalyst of the invention. The modified Ziegler-Natta catalyst is preferably non-activated, that is, it is unreactive towards olefin polymerization alone. In one embodiment, the molar ratio of the Group 13 metal (of the modifier) to the Group 4, 5 or 6 metal halide and/or oxide is less than 10:1 in one embodiment. The bimetallic catalysts of the present invention are useful in producing bimodal polymers, particularly bimodal polyethylene, having a Polydispersity (Mw/Mn) of from 12 to 50. These bimodal polyolefins are useful in such articles as pipes and films.
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:
A bimodal polyethylene composition that includes ethylene-derived units, and, optionally, one or more other olefin-derived units, wherein the bimodal polyethylene composition possesses a density of at least 0.940 g/cc, an average molecular weight (Mw) of from 200,000 to 370,000, a z-average molecular weight (Mz) of from 1,500,000 to 3,400,000 Daltons, and a z+1 average molecular weight (Mz+1) of from 2,500,000 to 6,800,000 Daltons, is provided in various embodiments. Articles made therefrom and methods of making the same are also provided.
摘要:
A method for making a polyolefin composition according to one embodiment includes altering the concentration of the chain transfer agent present in the reactor to control the HMW and LMW fractions of the polyolefin composition.
摘要:
The invention provides for ethylene copolymers having a polymodal CD, wherein under temperature rising elution fractionation (TREF) analysis the ethylene copolymers evidence at least two peaks.
摘要:
A Ziegler-Natta catalyst composition comprising a solid mixture formed by halogenation of: Al) a spray-dried catalyst precursor comprising the reaction product of a magnesium compound, a non-metallocene titanium compound, and at least one non-metallocene compound of a transition metal other than titanium, with A2) an organoaluminium halide halogenating agent, a method of preparing, precursors for use therein, and olefin polymerization processes using the same.
摘要:
A supported catalyst composition having improved flow properties is disclosed comprising an alkylalumoxane, a metallocene-alkyl an inorganic oxide support having an average particle size of from 0.1 to 50 μm and calcined at a temperature greater than 600° C., and optionally an antifoulant agent and. In one embodiment, the metallocene-alkyl is a Group 4, 5 or 6 metallocene-alkyl, and in another embodiment is a hafnocene-alkyl. Also disclosed is a method of polymerization using such a supported catalyst composition.
摘要:
The present invention relates to a supported, treated catalyst system and its use in a process for polymerizing olefin(s). More particularly, it provides a supported, treated catalyst system produced by a process comprising the steps of: (a) forming a supported bimetallic catalyst system comprising a first catalyst component and a metallocene catalyst compound; and (b) contacting the supported bimetallic catalyst system of (a) with at least one methylalumoxane-activatable compound.
摘要:
The invention provides for polymerization catalyst compositions, and for methods for introducing the catalyst compositions into a polymerization reactor. More particularly, the method combines a catalyst component containing slurry and a catalyst component containing solution to form the completed catalyst composition for introduction into the polymerization reactor. The invention is also directed to methods of preparing the catalyst component slurry, the catalyst component solution and the catalyst compositions, to methods of controlling the properties of polymer products utilizing the catalyst compositions, and to polymers produced therefrom.
摘要:
It has been found that the use of at least one unsupported metallocene polymerization catalyst with at least one supported metallocene polymerization catalyst in the polymerization of olefins allows for better control of the polymerization, especially gas phase polymerization. Such a system takes advantage of the high activity of the unsupported catalyst and the stability of a supported catalyst. Additionally, the relative timing of the addition of the supported and unsupported catalysts to a reaction system can be used to control a continuous polymerization reaction by stabilizing the reactor bed with the supported catalyst prior to addition of the unsupported catalyst.