Symmetrical hafnium metallocenes for preparing polymers having wide orthogonal component distribution

Abstract

Embodiments of the present disclosure are directed to symmetric hafnium metallocenes having isobutyl cyclopentadienyl ligands, compositions including those having isobutyl cyclopentadienyl ligands, and methods of utilizing compositions including symmetric hafnium metallocenes having isobutyl cyclopentadienyl ligands.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to metallocenes, methods of making and using the same, and polyolefins made therefrom. Background Art

[0002] Metallocenes can be used in a variety of applications, including as polymerization catalysts. Polymers can be used in several products, including membranes, etc. Polymers can be formed by reacting one or more types of monomers in a polymerization reaction. The industry is constantly working to develop new and improved materials and / or methods that can be used to form polymers. Summary of the invention

[0003] The present disclosure provides various embodiments including the following.

[0004] A symmetric hafnium metallocene having an isobutylcyclopentadienyl ligand, wherein the symmetric hafnium metallocene is represented by structure (I):

[0005]

[0006] wherein each X is independently a leaving group.

[0007] A metallocene catalyst composition comprises a symmetric hafnium metallocene having an isobutylcyclopentadienyl ligand and an activator.

[0008] A method for preparing a metallocene catalyst composition comprises contacting a symmetric hafnium metallocene having an isobutylcyclopentadienyl ligand with an activator.

[0009] A method for preparing a polyolefin polymer comprises polymerizing at least one olefin monomer with a metallocene catalyst composition to prepare the polyolefin polymer. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 Shown is a graph of data for determining the molecular weight comonomer distribution index (MWCDI) according to various embodiments of the present disclosure. DETAILED DESCRIPTION

[0011] Symmetrical hafnium metallocenes with isobutylcyclopentadienyl ligands are discussed herein. Advantageously, these symmetric hafnium metallocenes with isobutylcyclopentadienyl ligands can be used to prepare, for example, catalyst compositions. These catalyst compositions can be used to prepare polymers having improved (i.e., larger) molecular weight comonomer distribution indexes (MWCDI) compared to other polymers prepared by other metallocenes. These polymers are desired for many applications (including films, etc.). Therefore, it is advantageous to provide improved MWCDI. In addition, these catalyst compositions can be used to prepare polymers having improved (i.e., larger) comonomer incorporation (C6 weight %) compared to polymers prepared by other metallocenes.

[0012] As described herein, symmetrical hafnium metallocenes with isobutylcyclopentadienyl ligands can also be used to provide polymers with improved reverse short chain branching distribution. The limiting feature of polymers such as poly (ethylene-to-1-olefin) resins is short chain branching distribution (SCBD) or comonomer distribution. In order to improve product performance in many applications, it is desirable to have reverse SCBD or reverse comonomer distribution, wherein the weight percentage (wt%) of the comonomer in the polymer increases with the molecular weight (MW) of the polymer chain. This is also referred to as a polymer with a wide orthogonal composition distribution (BOCD). Dual reactor configurations and single or dual catalyst processes are typically used to achieve such distribution. In a dual reactor process, a single catalyst can be used to prepare high MW lower density components (with higher wt % comonomers) and low MW high density (lower wt % comonomer) components in a separate reactor via independent process control in two reactors. The result is a bimodal resin with reverse SCBD. In the case of a dual catalyst single reactor process, a catalyst prepares a high MW low density component, and another prepares a low MW high density component, thereby producing a bimodal product with reverse SCBD.

[0013] A more ideal way to achieve polymers with reverse SCBD is to use a single catalyst that can prepare such BOCD resins in a single reactor. As discussed herein, the symmetrical hafnium metallocenes with isobutylcyclopentadienyl ligands of the present disclosure provide the ability to produce polymers with improved BOCD resins in a single reactor, especially those polymers that have a measurable greater tendency to contain comonomers in higher MW fractions and maintain significant BOCD characteristics across a wide spectrum of process conditions. In addition, low melt index resins with broad molecular weight distributions and high BOCD components are needed in the industry for films and other applications. Without wishing to be bound by theory, it is believed that the isobutyl group of the symmetrical hafnium metallocenes of the present disclosure increases the primary C (sp 3)-H bonds, thereby increasing the frequency of this reaction and increasing the propensity of the symmetric hafnium metallocene catalyst to be multisite and produce polymers with BOCD.

[0014] A symmetric hafnium metallocene with an isobutylcyclopentadienyl ligand can be represented by structure (I):

[0015]

[0016] Wherein: Each X is independently a leaving group. As shown in structure (I), the upper cyclopentadienyl ring is substituted by an isobutyl ligand, and the lower cyclopentadienyl ring is substituted by another isobutyl ligand. Since the two cyclopentadienyl rings are each substituted by a corresponding isobutyl ligand, the metallocene can be referred to as a symmetric metallocene.

[0017] Embodiments of the present disclosure provide that X is a leaving group. One or more embodiments provide that X is selected from alkyl, aryl, hydride and halogen. One or more embodiments provide that X is selected from halogen, (C1-C5) alkyl, CH2SiMe3 and benzyl. One or more embodiments provide that X is selected from alkyl and halogen. One or more embodiments provide that X is chlorine. One or more embodiments provide that X is methyl.

[0018] Examples of X include halogen ions, hydrides, (C1-C 12 )alkyl, (C2-C 12 )alkenyl, (C6-C 12 ) aryl, (C7-C 20 ) alkylaryl, (C1-C 12 ) alkoxy, (C6-C 16 )aryloxy, (C7-C8)alkylaryloxy, (C1-C 12 )fluoroalkyl, (C6-C 12 ) fluoroaryl and (C1-C 12 ) heteroatom-containing hydrocarbons and their substituted derivatives; one or more embodiments include hydrides, halides, (C1-C6) alkyls, (C2-C6) alkenyls, (C7-C 18 )alkylaryl, (C1-C6)alkoxy, (C6-C 14 ) aryloxy, (C7-C 16 ) alkyl aryloxy, (C1-C6) alkyl carboxylate, (C1-C6) fluorinated alkyl carboxylate, (C6-C 12 ) aryl carboxylate, (C7-C 18 ) alkyl aryl carboxylates, (C1-C6) fluoroalkyl, (C2-C6) fluoroalkenyl and (C7-C 18) fluoroalkylaryl; one or more embodiments include hydride, chloride, fluoride, methyl, phenyl, phenoxy, benzoyloxy, tosyl, fluoromethyl and fluorophenyl; one or more embodiments include (C1-C 12 )alkyl, (C2-C 12 )alkenyl, (C6-C 12 ) aryl, (C7-C 20 ) alkylaryl, substituted (C1-C 12 ) alkyl, substituted (C6-C 12 ) aryl, substituted (C7-C 20 ) alkylaryl and (C1-C 12 ) containing heteroatoms, (C1-C 12 ) containing heteroatoms and (C1-C 12 ) heteroatom-containing alkylaryl; one or more embodiments include chloride, fluoride, (C1-C6) alkyl, (C2-C6) alkenyl, (C7-C 18 ) alkylaryl, halogenated (C1-C6) alkyl, halogenated (C2-C6) alkenyl and halogenated (C7-C 18 ) alkylaryl; one or more embodiments include fluoride, methyl, ethyl, propyl, phenyl, methylphenyl, dimethylphenyl, trimethylphenyl, fluoromethyl (monofluoromethyl, difluoromethyl and trifluoromethyl) and fluorophenyl (monofluorophenyl, difluorophenyl, trifluorophenyl, tetrafluorophenyl and pentafluorophenyl).

[0019] Other non-limiting examples of X groups include amines, phosphines, ethers, carboxylates, dienes, hydrocarbon groups with 1 to 20 carbon atoms, fluorinated hydrocarbon groups (e.g., -C6F5(pentafluorophenyl)), fluorinated alkyl carboxylates (e.g., CF3C(O)O-), hydrides, halogen ions, and combinations thereof. Other examples of X ligands include alkyl groups such as cyclobutyl, cyclohexyl, methyl, heptyl, tolyl, trifluoromethyl, tetramethylene, pentamethylene, methylene, methoxy, ethoxy, propoxy, phenoxy, bis(N-methylaniline), dimethylamido, and dimethylphosphoryl, etc. In one embodiment, two or more X form a part of a fused ring or ring system. In one or more embodiments, X can be a leaving group selected from the group consisting of chloride, bromide, (C1-C 10 )alkyl, (C2-C 12 ) alkenyl, carboxylate, acetylacetonate, and alcoholate. In one or more embodiments, X is methyl.

[0020] The symmetric hafnium metallocenes with isobutylcyclopentadienyl ligands discussed herein can be prepared by contacting a hafnium complex with an alkali metal complex to prepare the symmetric hafnium metallocenes with isobutylcyclopentadienyl ligands. The symmetric hafnium metallocenes with isobutylcyclopentadienyl ligands discussed herein can be prepared by methods for preparing known metallocenes (e.g., using conventional solvents, reaction conditions, reaction times, and isolation procedures).

[0021] Alkali metal complexes can be represented by the following structure:

[0022]

[0023] Where M' is lithium, sodium or potassium, and R 1 It is an isobutyl group.

[0024] One or more embodiments provide that the hafnium complex may be hafnium tetrachloride.

[0025] One or more embodiments provide that a method for preparing a symmetrical hafnium metallocene having an isobutylcyclopentadienyl ligand (e.g., wherein each X is Cl) comprises contacting the symmetrical hafnium metallocene having an isobutylcyclopentadienyl ligand with two molar equivalents of an organomagnesium halide of formula RMg(halide) or one molar equivalent of R2Mg, wherein R is (C1-C5)alkyl, CH2SiMe3, or benzyl; and the halide is Cl or Br, to prepare a symmetrical hafnium metallocene of structure (I), wherein each X is a halogen, (C1-C5)alkyl, CH2SiMe3, or benzyl. One or more embodiments provide that X is (C1-C5)alkyl, CH2SiMe3, or benzyl. One or more embodiments provide that X is Cl or CH3. As used herein, all references to the Periodic Table of the Elements and its Groups refer to the NEW NOTATION as published in HAWLEY'S CONDENSED CHEMICAL DICTIONARY, Thirteenth Edition, John Wiley & Sons, Inc. (1997) (reproduced with permission from IUPAC), unless reference is made to the previous IUPAC form marked with Roman numbering (which also appears therein) or unless otherwise mentioned.

[0026] As used herein, "alkyl" includes straight chain, branched chain, and cyclic alkane radicals lacking one hydrogen. Thus, for example, CH3 ("methyl") and CH2CH3 ("ethyl") are examples of alkyl radicals.

[0027] As used herein, "alkenyl" includes straight chain, branched chain, and cyclic alkene radicals lacking one hydrogen radical; alkynyl radicals include straight chain, branched chain, and cyclic ethynyl radicals lacking one hydrogen radical.

[0028] As used herein, "aryl" groups include phenyl, naphthyl, pyridyl and other groups whose molecules have ring structures characteristic of benzene, naphthylene, phenanthrene, anthracene, etc. It should be understood that "aryl" groups can be C6-C 20 Aryl groups. For example, a C6H5 aromatic structure is a "phenyl" and a C6H4 aromatic structure is a "phenylene". An "aralkyl" group is an alkyl group with a pendant aryl group. It should be understood that an "aralkyl" group can be (C7-C 20 ) aralkyl groups. "Alkaryl" is an aryl group having one or more pendant alkyl groups.

[0029] As used herein, "alkylene" includes straight chain, branched, and cyclic hydrocarbon groups lacking two hydrogens. Thus, CH2 ("methylene") and CH2CH2 ("ethylene") are examples of alkylene groups. Other groups lacking two hydrogen groups include "arylene" and "alkenylene".

[0030] As used herein, the term "heteroatom" includes any atom selected from the group consisting of: B, Al, Si, Ge, N, P, O and S. A "heteroatom-containing group" is a hydrocarbon group containing heteroatoms and may contain one or more of the same heteroatoms or different heteroatoms, and may contain 1 to 3 heteroatoms in a specific embodiment. Non-limiting examples of heteroatom-containing groups include groups (monovalent and divalent groups) of imines, amines, oxides, phosphines, ethers, ketones, oxazoline heterocycles, oxazolines and thioethers.

[0031] As used herein, the term "substituted" means that one or more hydrogen atoms in the parent structure have been independently replaced with a substituent atom or group.

[0032] Symmetric hafnium metallocenes with isobutylcyclopentadienyl ligands discussed herein can be used to prepare catalyst compositions. These compositions include symmetrical hafnium metallocenes with isobutylcyclopentadienyl ligands discussed herein and activators. One or more embodiments provide that the activator is an alkylaluminoxane, such as methylaluminoxane. As used herein, "activator" refers to any supported or unsupported compound or combination of compounds, which can, for example, activate the complex or catalyst component by generating cationic species of the catalyst component. For example, this can include capturing at least one leaving group, such as "X" group described herein, from the metal center of the complex / catalyst component (e.g., the symmetrical hafnium metallocene with isobutylcyclopentadienyl ligands of structure (I). Activators may also be referred to as "co-catalysts". As used herein, "leaving group" refers to one or more chemical moieties that are combined with metal atoms and can be captured by activators, thereby generating a substance that is active for olefin polymerization. Various catalyst compositions, such as olefin polymerization catalyst compositions are known in the art, and different known catalyst composition components can be used, and different amounts of known catalyst composition components can be used for different applications.

[0033] Symmetric hafnium metallocenes with isobutylcyclopentadienyl ligands discussed herein can be used to prepare spray-dried compositions. As used herein, "spray-dried compositions" refer to compositions comprising a number of components that have undergone a spray-drying process. Various spray-drying methods are known in the art and are suitable for forming the spray-dried compositions disclosed herein. One or more embodiments provide for spray-dried compositions comprising a modified composition.

[0034] In one or more embodiments, the spray drying method may include atomizing a composition comprising a symmetrical hafnium metallocene with an isobutylcyclopentadienyl ligand as discussed herein. Many other known components may be used in the spray drying process. Atomizers such as atomizing nozzles or centrifugal high-speed disks may be used, for example, to produce a spray or dispersion of composition droplets. The droplets of the composition may then be rapidly dried by contact with an inert dry gas. The inert dry gas may be any gas, such as nitrogen, that is not reactive under the conditions employed during atomization. The inert dry gas may encounter the composition at the atomizer, which produces a droplet stream on a continuous basis. The dried composition particles may be captured from the process in a separator, such as a cyclone separator, which may separate the solid formed from a gas mixture of a dry gas, a solvent, and other volatile components.

[0035] For example, the spray-dried composition can have a free-flowing powder form. After the spray-drying process, the spray-dried composition and many known components can be used to form a slurry. The spray-dried composition can be used together with a diluent to form a slurry suitable for, for example, olefin polymerization. In one or more embodiments, the slurry can be merged with one or more other catalysts or other known components before being delivered in a polymerization reactor.

[0036] In one or more embodiments, the spray-dried composition can be formed by contacting the solution of the symmetrical hafnium metallocene with isobutylcyclopentadienyl ligands discussed herein with spray-dried activator particles (such as spray-dried MAO). Such solutions can be prepared in, for example, inert hydrocarbon solvents, and are sometimes referred to as adjustment solutions. Such spray-dried compositions including contacting the adjustment solution of the symmetrical hafnium metallocene with isobutylcyclopentadienyl ligands with spray-dried activator particles (such as spray-dried MAO) can be prepared in situ by contacting the adjustment solution with a slurry (usually in mineral oil) of the spray-dried activator particles in the feed line leading to the gas phase polymerization reactor. Alternatively, the spray-dried composition can be formed by contacting the slurry of the spray-dried activator particles (such as the mineral oil slurry of the spray-dried activator particles) with the symmetrical hafnium metallocene with isobutylcyclopentadienyl ligands.

[0037] Various spray drying conditions can be used for different applications. For example, the spray drying method can utilize a drying temperature of 115° C. to 185° C. Other drying temperatures are also possible, wherein the temperature may depend on the metallocene and activator particles. Various sizes of orifices of the atomizing nozzle employed during the spray drying process can be used to obtain different particle sizes. Alternatively, for other types of atomizers such as disks, the rotation speed, disk size, and number / size of holes can be adjusted to obtain different particle sizes. One or more embodiments provide that fillers can be used in the spray drying process. Different fillers and their amounts can be used for various applications.

[0038] Symmetric hafnium metallocenes with isobutylcyclopentadienyl ligands discussed herein (e.g., catalyst compositions, such as spray-dried hafnium metallocene compositions) can be used to prepare polymers. For example, symmetrical hafnium metallocenes with isobutylcyclopentadienyl ligands can be activated, i.e., activated with an activator, to prepare a catalyst. One or more embodiments provide that the spray-dried composition comprises an activator. As used herein, "activator" refers to any supported or unsupported compound or combination of compounds, which can activate a complex or catalyst component, such as by generating a cationic species of a catalyst component, for example, to provide a catalyst. An activator may also be referred to as a "cocatalyst". An activator may include a Lewis acid or a non-coordinating ion activator or an ionizing activator, or any other compound including a Lewis base, an alkyl aluminum and / or a conventional cocatalyst. An activator includes methylaluminoxane (MAO) and modified methylaluminoxane (MMAO), etc. One or more embodiments provide that the activator is methylaluminoxane. Activation conditions are well known in the art. Known activation conditions may be used.

[0039] The molar ratio of the metal (e.g., aluminum) in the activator to the hafnium in the symmetric hafnium metallocene with isobutylcyclopentadienyl ligands can be from 1500:1 to 0.5:1, from 300:1 to 1:1, or from 150:1 to 1:1. One or more embodiments provide that the molar ratio of the activator to the hafnium in the symmetric hafnium metallocene with isobutylcyclopentadienyl ligands is at least 75:1. One or more embodiments provide that the molar ratio of the activator to the hafnium in the symmetric hafnium metallocene with isobutylcyclopentadienyl ligands is at least 100:1. One or more embodiments provide that the molar ratio of the activator to the hafnium in the symmetric hafnium metallocene with isobutylcyclopentadienyl ligands is at least 150:1.

[0040] Symmetrical hafnium metallocenes with isobutylcyclopentadienyl ligands discussed herein and many other components can be loaded on the same or separate carriers, or one or more of these components can be used in an unloaded form. The use of carriers can be achieved by any technology used in the art. One or more embodiments provide that a spray drying process is utilized. For example, a symmetrical metallocene with isobutylcyclopentadienyl ligands in an inert solvent can be contacted with a loaded or spray-dried activator (or its slurry) to obtain a spray-dried metallocene catalyst composition. Alternatively, the loaded symmetrical hafnium metallocenes of the present invention and many other components can be formed by drying the slurry of the components under vacuum or reduced pressure. The carrier can be functionalized. One or more embodiments provide that the spray-dried composition comprises a carrier.

[0041] "Carrier" may also be referred to as "support", and refers to any carrier material, including porous carrier materials (such as talc), inorganic oxides and inorganic chlorides. Other carrier materials include resin carrier materials (such as polystyrene), functionalized or cross-linked organic carriers (such as polystyrene divinyl benzene polyolefins or polymeric compounds), zeolites, clays or any other organic or inorganic carrier materials, etc., or mixtures thereof.

[0042] The support material includes an inorganic oxide including a Group 2, 3, 4, 5, 13 or 14 metal oxide. Some preferred supports include silica, fumed silica, alumina, silica-alumina and mixtures thereof. Some other supports include magnesium oxide, titanium oxide, zirconium oxide, magnesium chloride, montmorillonite, phyllosilicates, zeolites, talc, clays and the like. Moreover, combinations of these support materials may be used, such as silica-chromium, silica-alumina, silica-titania and the like. One or more embodiments provide that the support is silica. One or more embodiments provide that the support is hydrophobic pyrogenic silica. One or more embodiments provide that the support is dehydrated silica. Additional support materials may include porous acrylic polymers, nanocomposites, aerogels, spherulites and polymer beads. An example of a support is available under the trade name Cabosil. TM Fumed silica is obtained from TS-610, or other TS-series or TG-series supports available from Cabot Corporation. Fumed silica is typically silica having a particle size of 7 to 30 nanometers that has been treated with dimethylsilyl dichloride such that most of the surface hydroxyl groups are capped.

[0043] Symmetrical hafnium metallocenes (e.g., compositions / catalyst compositions / spray-dried compositions) with isobutylcyclopentadienyl ligands discussed herein can be contacted with olefins under polymerization conditions to prepare polymers (e.g., polyolefin polymers). The polymerization process can be a suspension polymerization process, a slurry polymerization process, and / or a gas phase polymerization process. The polymerization process can utilize known equipment and reaction conditions, such as known polymerization conditions. The polymerization process is not limited to any particular type of polymerization system. The polymer can be used in many articles, such as films, fibers, nonwoven fabrics and / or woven fabrics, extruded articles, and / or molded articles.

[0044] One or more embodiments provide for the use of a gas phase reactor system to prepare the polymer. One or more embodiments provide for the use of a single gas phase reactor, for example as opposed to a series of reactors. In other words, the polymerization reaction occurs in only one reactor. For example, a fluidized bed reactor may be used to prepare the polymer. Gas phase reactors are known, and known components may be used in fluidized bed reactors.

[0045] As used herein, "olefins" which may be referred to as "alkenes" refer to linear, branched or cyclic compounds comprising carbon and hydrogen and having at least one double bond. As used herein, when polyolefins, polymers and / or copolymers are referred to as comprising olefins (e.g., prepared from olefins), the olefins present in such polymers or copolymers are olefins in polymerized form. For example, when it is said that the ethylene content of a copolymer is 75% to 95% by weight, it is understood that the polymer units in the copolymer are derived from ethylene in the polymerization reaction, and based on the gross weight of the polymer, the derived units are present in 75% to 95% by weight. Higher alpha-olefins refer to alpha-olefins having 3 or more carbon atoms.

[0046] The polyolefin prepared with the composition discussed herein can be prepared from olefin monomers, such as ethylene (i.e., polyethylene) or propylene (i.e., polypropylene), and other substances specified herein, wherein the polyolefin is a homopolymer prepared only from olefin monomers (e.g., prepared from 100% by weight ethylene or 100% by weight propylene). Alternatively, the polyolefin prepared with the composition discussed herein can be made from olefin monomers such as ethylene (i.e., polyethylene), and straight or branched higher alpha-olefin monomers containing 3 to 20 carbon atoms. Examples of higher alpha-olefin monomers include, but are not limited to, propylene, butene, pentene, 1-hexene, and 1-octene. Examples of polyolefins include ethylene-based polymers with at least 50% by weight ethylene, including ethylene-1-butene, ethylene-1-hexene, and ethylene-1-octene copolymers, etc. One or more embodiments provide that, based on the total weight of the polymer, the polymer may include 50% by weight to 99.9% by weight of units derived from ethylene. All individual values ​​and subranges of 50 wt % to 99.9 wt % are included; for example, based on the total weight of the polymer, the polymer may include a lower limit of 50 wt %, 60 wt %, 70 wt %, 80 wt % or 90 wt % of units derived from ethylene to an upper limit of 99.9 wt %, 99.7 wt %, 99.4 wt %, 99 wt %, 96 wt %, 93 wt %, 90 wt % or 85 wt % of units derived from ethylene. Based on the total weight of the polymer, the polymer may include 0.1 wt % to 50 wt % of units derived from comonomers. One or more embodiments provide that ethylene is used as a monomer and hexene is used as a comonomer.

[0047] As mentioned, polymers prepared with the compositions disclosed herein can be prepared in a fluidized bed reactor. The fluidized bed reactor can have a reaction temperature of 10°C to 130°C. All individual values ​​and subranges from 10°C to 130°C are included; for example, the fluidized bed reactor can have a reaction temperature of 10°C, 20°C, 30°C, 40°C, 50°C, or 55°C to an upper limit of 130°C, 120°C, 110°C, 100°C, 90°C, 80°C, 70°C, or 60°C.

[0048] The fluidized bed reactor can have an ethylene partial pressure of 30 pounds per square inch (psi) to 250 psi, including all individual values ​​and subranges from 30 psi to 250 psi; for example, the fluidized bed reactor can have an ethylene partial pressure of 30 psi, 45 psi, 60 psi, 75 psi, 85 psi, 90 psi, or 95 psi on the lower limit and 250 psi, 240 psi, 220 psi, 200 psi, 150 psi, or 125 psi on the upper limit.

[0049] One or more embodiments provide that ethylene is used as a monomer and hexene is used as a comonomer. The fluidized bed reactor can have a comonomer to ethylene molar ratio of 0.0001 to 0.100, for example, C6 / C2. All individual values ​​and subranges from 0.0001 to 0.100 are included; for example, the fluidized bed reactor can have a comonomer to ethylene molar ratio of 0.0001, 0.0005, 0.0007, 0.001, 0.0015, 0.002, 0.007, or 0.010 to an upper limit of 0.100, 0.080, or 0.050.

[0050] When hydrogen is used in the polymerization process, the fluidized bed reactor can have, for example, a hydrogen to ethylene molar ratio (H2 / C2) of 0.00001 to 0.90000. All individual values ​​and subranges from 0.00001 to 0.90000 are included; for example, the fluidized bed reactor can have a H2 / C2 with a lower limit of 0.00001, 0.00005, or 0.00008 to an upper limit of 0.90000, 0.500000, 0.10000, 0.01500, 0.00700, or 0.00500. One or more embodiments provide that hydrogen is not utilized.

[0051] Melt temperature was determined using Differential Scanning Calorimetry according to ASTM D 3418-08.

[0052] Conventional gel permeation chromatography can be used to determine multiple polymer properties. For example, a chromatographic system consisting of a PolymerChar GPC-IR (Valencia, Spain) high temperature GPC chromatograph equipped with an internal IR5 infrared detector (IR5) is used to determine weight average molecular weight (Mw), number average molecular weight (Mn), Z average molecular weight (Mz) and Mw / Mn (PDI). The autosampler oven chamber is set to 160°C, and the column chamber is set to 150°C. The column used is 4 Agilent "MixedA" 30cm 20 micron linear mixed bed columns. The chromatographic solvent used is 1,2,4 trichlorobenzene and contains 200ppm of butylated hydroxytoluene (BHT). The solvent source is nitrogen sparged. The injection volume used is 200 microliters, and the flow rate is 1.0 ml / min.

[0053] The calibration of the GPC column set was performed with 21 narrow molecular weight distribution polystyrene standards, the molecular weight of which ranged from 580 g / mol to 8,400,000 g / mol, and were arranged in 6 "mixed liquid" mixtures, with at least ten times intervals between individual molecular weights. The standards were purchased from Agilent Technologies. For molecular weights equal to or greater than 1,000,000, 0.025 grams of polystyrene standards were prepared in 50 milliliters of solvent, and for molecular weights less than 1,000,000, 0.05 grams of polystyrene standards were prepared in 50 milliliters of solvent. The polystyrene standards were pre-dissolved at 80°C under gentle stirring for 30 minutes, then cooled, and the room temperature solution was transferred to a 160°C autosampler dissolution oven and cooled for 30 minutes. The polystyrene standard peak molecular weight was converted to polyethylene molecular weight using equation 1 (as described in Williams and Ward, J. Polym. Sci., Polym. Let.), 6, 621 (1968)):

[0054] M 聚乙烯 =A×(M 聚苯乙烯 ) B (Equation 1)

[0055] Where M is the molecular weight, A has a value of 0.4061, and B equals 1.0.

[0056] A fifth-order polynomial was used to fit the calibration points to the corresponding polyethylene equivalents.

[0057] Total plate counts for the GPC column set were performed with decane, which was introduced into the blank sample via a micro pump controlled by the PolymerChar GPC-IR system. The plate count of the chromatography system should be greater than 18,000 for 4 Agilent "Mixed A" 30 cm 20 micron linear mixed bed columns.

[0058] The samples were prepared semi-automatically using the PolymerChar "Instrument Control" software, where the target weight of the sample was set to 2 mg / ml, and the solvent (containing 200 ppm BHT) was added to a septum-capped vial previously sparged with nitrogen via the PolymerChar high temperature autosampler. The samples were dissolved at 160 degrees Celsius for 2 hours under "slow" shaking.

[0059] Based on the GPC results, using the internal IR5 detector (measurement channel) of the PolymerChar GPC-IR spectrometer, according to equations 2-4, the PolymerChar GPCOne TM The software was used to calculate the Mn value of the baseline-subtracted IR chromatogram at each equidistant data collection point (i) and the polyethylene equivalent molecular weight obtained from the narrow standard calibration curve at point (i) according to Equation 1. (GPC) 、Mw (GPC) and Mz (GPC) Calculation.

[0060]

[0061] To monitor deviations over time, a flow rate marker (decane) was introduced into each sample via a micropump controlled by the PolymerChar GPC-IR system. This flow rate marker (FM) was used to linearly correct the pump flow rate for each sample (Flow Rate (Nominal)) by comparing the RV of the corresponding decane peak in the sample (RV (FM Sample)) with the RV of the decane peak in the narrow standard calibration (RV (FM Calibrated)). Any changes in the decane marker peak time were then assumed to be related to a linear change in flow rate (Flow Rate (Effective)) throughout the run. After calibrating the system based on the flow marker peak, the effective flow rate (relative to the narrow standard calibration) was calculated as Equation 5. TM The software completes the processing of the flow marker peak. An acceptable flow rate correction is such that the effective flow rate should be within + / - 0.5% of the nominal flow rate. Flow Rate (Effective) = Flow Rate (Nominal) x (RV (FM Cal) / RV (FM Sample)) (Equation 5)

[0062] IR5 GPC Octene Composition Calibration. Calibration for IR5 detector dosing is performed using at least ten ethylene-based polymer standards (octene as comonomer) produced in a solution process (polyethylene homopolymer and ethylene / octene copolymer) from a single reactor over a single site metallocene catalyst with narrow SCB distribution and known comonomer content (e.g., by 13C NMR method, Qiu et al., Anal. Chem.) 2009, 81, 8585-8589) in a solution process (polyethylene homopolymer and ethylene / octene copolymer) from a single reactor by a single-site metallocene catalyst, the known monomer content is in the range of from homopolymer (0 SCB / 1000 total C) to about 40 SCB / 1000 total C, where total C = carbon in the main chain + carbon in the branch chain. Each SCB standard has a weight average molecular weight of 36,000 g / mole to 126,000 g / mole, as measured by GPC. The molecular weight distribution (Mw / Mn) of each standard is 2.0 to 2.5. The SCB standard polymer properties are shown in Table A.

[0063] Table A: "Copolymer" Standards

[0064]

[0065] The “IR5 Area Ratio” (or “IR5 Area Response”) of the “Baseline-Subtracted Area Response of the IR5 Methyl Channel Sensor” to the “Baseline-Subtracted Area Response of the IR5 Measurement Channel Sensor” was calculated for each of the “Copolymer” standards. 甲基通道面积 / IR5 测量通道面积 ”)” (including standard filters and filter wheels supplied by PolymerChar: Part No. IR5_FWM01 as part of the GPC-IR instrument). A linear fit of comonomer wt% frequency versus “IR5 Area Ratio” was constructed in the form of Equation 6 below:

[0066] Comonomer weight % = A0 + [A1 × (IR5 甲基通道面积 / IR5 测量通道面积 )] (Equation 6) where A0 is the "Comonomer wt%" intercept at "IR5 Area Ratio" of zero, and A1 is the slope of "Comonomer wt%" relative to "IR5 Area Ratio" and represents the increase of comonomer wt% as "IR5 Area Ratio" changes. For narrow PDI and narrow SCBD standard materials, IR5 Area Ratio is equal to IR5 Height Ratio.

[0067] The comonomer distribution or short chain branching distribution in ethylene / α-olefin copolymers can be characterized as normal (also referred to as having a Ziegler-Natta distribution), inverse or flat. Several reported methods are used to quantify broad orthogonal composition distribution (BOCD). Herein, a simple straight line fit is used so that the normal or inverse nature of the comonomer distribution can be quantified by the molecular weight comonomer distribution index (MWCDI), which is the slope of the linear regression of the comonomer distribution measured by composition GPC, where the x-axis is Log (MW), and the y-axis is the weight percent of the comonomer. Figure 1 Data plots for determining the MWCDI for Example 3 (MWCDI = 5.91) and for determining the MWCDI for Comparative Example C (MWCDI = 3.60) are shown, as shown in Table 3 of the Examples section of the present application. Reverse comonomer distribution is defined when MWCDI>0, and normal comonomer distribution is defined when MWCDI<0. When MWCDI=0, the comonomer distribution is said to be flat. In addition, MWCDI quantifies the magnitude of the comonomer distribution. Comparing two polymers with MWCDI>0, the polymer with a larger MWCDI value is defined as having a larger, i.e., increased BOCD; in other words, the polymer with a larger MWCDI value has a larger reverse comonomer distribution. For example, as reported in Table 3, the catalyst of Example 2 has an increased BOCD compared to the catalyst of Comparative Example B. Polymers with relatively large MWCDI (i.e., BOCD) can provide improved physical properties (such as improved film performance) compared to polymers with relatively small MWCDI.

[0068] The polymers prepared with the compositions disclosed herein can have a MWCDI of 0.10 to 10.00, including all individual values ​​and subranges from 0.10 to 10.00; for example, the polymer can have a MWCDI from a lower limit of 0.10, 0.50, or 1.00 to an upper limit of 10.00, 9.00, 8.00, 8.50, or 8.35.

[0069] The polymers prepared with the compositions disclosed herein may have a density of from 0.8700 to 0.9700 g / cm 3 Density. From 0.8700 to 0.9700 g / cm 3 All individual values ​​and subranges of; for example, the polymer can have a lower limit of 0.8700, 0.9000, 0.9100, 0.9150, 0.9200, or 0.9250 g / cm 3 Up to 0.9700, 0.9600, 0.9500, 0.9450, 0.9350 or 0.9300 g / cm 3 Density. The density can be measured according to ASTM D792.

[0070] The polymer prepared with the composition disclosed herein can have a weight average molecular weight (Mw) of 5,000 to 750,000 g / mol. All individual values ​​and subranges of 5,000 to 750,000 g / mol are included; for example, the polymer can have a Mw with a lower limit of 5,000, 10,000 or 15,000 g / mol to an upper limit of 750,000, 500,000 or 200,000 g / mol. As known in the art, Mw can be determined by gel permeation chromatography (GPC). GPC is discussed herein.

[0071] The polymers prepared with the compositions disclosed herein can have a number average molecular weight (Mn) of 3,000 to 300,000 g / mol. All individual values ​​and subranges of 3,000 to 300,000 g / mol are included; for example, the polymer can have a Mn with a lower limit of 3,000, 5,000, or 10,000 g / mol to an upper limit of 300,000, 250,000, or 200,000 g / mol. Mn can be determined by GPC.

[0072] The polymers prepared with the compositions disclosed herein can have a Z average molecular weight (Mz) of 20,000 to 2,000,000 g / mol. All individual values ​​and subranges of 20,000 to 2,000,000 g / mol are included; for example, the polymer can have a Mz with a lower limit of 20,000, 25,000, or 30,000 g / mol to an upper limit of 2,000,000, 1,000,000, 500,000, or 200,000 g / mol. Mz can be determined by GPC.

[0073] The polymers prepared with the compositions disclosed herein can have a weight average molecular weight to number average molecular weight ratio (Mw / Mn) of 1.00 to 6.00. All individual values ​​and subranges from 1.00 to 6.00 are included; for example, the polymer can have a Mw / Mn with a lower limit of 1.00, 1.50, 2.00, or 2.10 to an upper limit of 6.00, 5.50, or 4.50.

[0074] Various aspects of the disclosure are provided as follows.

[0075] Aspect 1 provides a symmetrical hafnium metallocene having an isobutylcyclopentadienyl ligand, wherein the symmetrical hafnium metallocene is represented by structure (I):

[0076]

[0077] wherein each X is independently a leaving group.

[0078] Aspect 2 provides a symmetrical hafnium metallocene having an isobutylcyclopentadienyl ligand according to aspect 1, wherein each X is independently a leaving group selected from halogen, (C1-C5) alkyl, CH2SiMe3 and benzyl.

[0079] Aspect 3 provides a symmetric hafnium metallocene having an isobutylcyclopentadienyl ligand according to any one of aspects 1 to 2, wherein each X is -Cl, and the symmetric hafnium metallocene is represented by structure (II):

[0080]

[0081] Aspect 4 provides a symmetric hafnium metallocene having an isobutylcyclopentadienyl ligand according to any one of aspects 1 to 2, wherein each X is -CH3, and the symmetric hafnium metallocene is represented by structure (III):

[0082]

[0083] Aspect 5 provides a method for synthesizing the symmetrical hafnium metallocene having an isobutylcyclopentadienyl ligand according to any one of aspects 1 to 4, the method comprising:

[0084] The hafnium complex is contacted with an alkali metal complex, wherein the alkali metal complex is represented by the following structure:

[0085]

[0086] Where M' is lithium, sodium or potassium, and R 1 is an isobutyl group; and the hafnium complex is hafnium tetrachloride.

[0087] Aspect 6 provides a method according to aspect 5, which comprises: contacting a symmetrical hafnium metallocene having an isobutylcyclopentadienyl ligand with two molar equivalents of an organic magnesium halide of formula RMg(halide) or one molar equivalent of R2Mg, wherein R is (C1-C5)alkyl, CH2SiMe3 or benzyl; and the halide is Cl or Br, to prepare the symmetrical hafnium metallocene having an isobutylcyclopentadienyl ligand of structure (I), wherein each X is (C1-C5)alkyl, CH2SiMe3 or benzyl.

[0088] Aspect 7 provides a metallocene catalyst composition, which comprises: a symmetrical hafnium metallocene having an isobutylcyclopentadienyl ligand according to any one of Aspects 1 to 4, or a symmetrical hafnium metallocene having an isobutylcyclopentadienyl ligand prepared by the method of Aspect 5 or Aspect 6; and an activator (e.g., an alkylaluminoxane, such as methylaluminoxane).

[0089] Aspect 8 provides the metallocene catalyst composition according to aspect 7, further comprising a support (eg, silica, such as hydrophobic fumed silica or dehydrated silica).

[0090] Aspect 9 provides the metallocene catalyst composition according to aspect 8, wherein the composition is a spray-dried metallocene catalyst composition.

[0091] Aspect 10 provides a method for preparing a metallocene catalyst composition according to any one of Aspects 7 to 9, the method comprising: contacting a symmetric hafnium metallocene having an isobutylcyclopentadienyl ligand with an activator but not with a carrier to obtain a metallocene catalyst composition without a carrier; or contacting the symmetric hafnium metallocene having an isobutylcyclopentadienyl ligand with the activator and the carrier to obtain the metallocene catalyst composition containing the carrier; or contacting the symmetric hafnium metallocene having an isobutylcyclopentadienyl ligand with the activator and the carrier in an inert solvent; or contacting the symmetric hafnium metallocene having an isobutylcyclopentadienyl ligand with the activator and the carrier in an inert solvent to obtain a suspension thereof, and spray-drying the suspension to obtain the spray-dried metallocene catalyst composition; or contacting a symmetric metallocene having an isobutylcyclopentadienyl ligand in an inert solvent with a supported or spray-dried activator (or its slurry) to obtain a spray-dried metallocene catalyst composition.

[0092] Aspect 11 provides a method for preparing a polyolefin polymer, the method comprising: polymerizing at least one olefin monomer with the metallocene catalyst composition according to any one of aspects 7 to 9 or the metallocene catalyst composition prepared by the method according to aspect 10 to prepare a polyolefin polymer; wherein preferably, the at least one olefin monomer comprises ethylene and an optional comonomer selected from the group consisting of propylene and (C4-C 20 )α-olefins.

[0093] Aspect 12 provides a method according to aspect 11, wherein the at least one olefin monomer comprises ethylene and a comonomer; and wherein the polyolefin polymer has a molecular weight comonomer distribution index (MWCDI) of 0.10 to 10.00, as measured by the MWCDI test method described herein; wherein preferably, the comonomer is selected from the group consisting of: 1-butene, 1-hexene and 1-octene.

[0094] Aspect 13 is a polyolefin polymer prepared by the method according to any one of aspects 11 to 12.

[0095] Example

[0096] 5-(2-methylpropylene)cyclopenta-1,3-diene, which can be represented by the following formula:

[0097]

[0098] Synthesized as follows. In a glove box, pyrrolidine (1.45 g, 10 mol%) was added to a glass container containing a solution of isobutyraldehyde (14.6 g, 203 mmol) and cyclopentadiene (13.4 g, 203 mmol) in MeOH-H2O (200 mL 4 / 1). The contents of the container were transferred to an ice-cold mixture of a saline solution and 10 mol% AcOH in a narrow graduated cylinder. The organic phase was separated and dried over molecular sieves. The product (5-(2-methylpropylidene)cyclopenta-1,3-diene) was filtered to obtain a bright yellow oil, which was then used without further purification (16.0 g, 65%). 1 H NMR (400MHz, CDCl3) δ: 6.54 (tdd, J = 5.4, 3.8, 2.5Hz, 2H), 6.51–6.44 (m, 1H), 6.29–6.17 (m, 2H), 3.02 (dp, J = 10.0, 6.6Hz, 1H), 1.15 (d, J = 6.6Hz, 6H). 13 C NMR (101MHz, CDCl3) δ: 149.88, 143.69, 133.08, 130.87, 126.06, 119.36, 30.58, 23.24.

[0099] Isobutylcyclopentadienyllithium, which can be represented by the following formula:

[0100]

[0101] are synthesized as follows.

[0102] Et2O (250 mL) was added to the container. 5-(2-methylpropylidene)cyclopenta-1,3-diene (16.0 g, 133 mmol) was added to the contents of the container while stirring. LiAlH4 (33 mL, 4M Et2O solution) was added dropwise to the contents of the container while stirring. Bubbling was observed. A white solid precipitated during the addition, and the yellow color gradually faded as the LiAlH4 was continued to be added. Addition was stopped once the solution turned only light yellow. The product, isobutylcyclopentadienyllithium, observed as a white solid, was collected by filtration, rinsed with Et2O, and dried under vacuum (13.7 g, 80%).

[0103] Example 1 - Synthesis of bis(isobutylcyclopentadienyl)hafnium dichloride (EX 1)

[0104]

[0105] Isobutylcyclopentadienyl lithium (0.150 g, 17.7 mmol) and hafnium tetrachloride (0.187 g, 0.585 mmol) were added to a container with THF and stirred at about 20 ° C for about 12 hours. The contents of the container were then concentrated to obtain an off-white residue. The residue was extracted with dichloromethane and then filtered. The resulting solution was placed under vacuum to obtain Example 1 (0.276 g, 96%). 1 H NMR (400MHz, C6D6) δ: 5.83 (t, J = 2.7Hz, 4H), 5.72–5.61 (m, 4H), 2.57 (d, J = 7.0Hz, 4H), 1.62 (dq, J = 13.5, 6.8Hz, 2H), 0.80 (d, J = 6.6Hz, 12H). 13 C NMR (101MHz, C6D6) δ: 130.67, 116.15, 110.24, 39.50, 30.32, 22.09.

[0106] Example 2 (spray dried composition) was prepared as follows. In a nitrogen purged glove box, hydrophobic fumed silica (CABOSIL TS-610; 1.33 grams) and toluene (37.5 grams) were added to a container and mixed, followed by the addition of a 10% solution (11 grams) by weight of methylaluminoxane (MAO) in toluene. The contents of the container were then stirred for about 15 minutes. Example 1 (0.049 grams) was then added to the container and the contents of the container were stirred for about 30 minutes. The contents of the container were then spray dried using a Büchi Mini Spray Drier B-290 (set temperature: 140°C; 100°C outlet temperature; aspirator: 95; pump speed: 150 rpm) to provide Example 2 (EX 2).

[0107] Comparative Example A (EX A), a hafnium metallocene with two n-propylcyclopentadienyl ligands (bis-(n-propylcyclopentadienyl)hafnium dichloride), was commercially available from TCI.

[0108]

[0109] Comparative Example B (CE B; spray-dried composition) was prepared as follows. In a nitrogen-purged glove box, hydrophobic fumed silica (CABOSIL TS-610; 2.65 grams) and toluene (75 grams) were added to a container and mixed, followed by the addition of a 10% solution (22 grams) by weight of methylaluminoxane (MAO) in toluene. The contents of the container were then stirred for about 15 minutes. Comparative Example A (0.105 grams) was then added to the container and the contents of the container were stirred for about 30 minutes. The contents of the container were then spray dried using a Büchi Mini Spray Drier B-290 (set temperature: 140°C; 100°C outlet temperature; aspirator: 95; pump speed: 150 rpm) to provide Comparative Example B (CE B).

[0110] Comparative Example C (CE C; a hafnium metallocene (bis-(n-propylcyclopentadienyl) hafnium dichloride) having two n-butylcyclopentadienyl ligands) was prepared as follows.

[0111]

[0112] In a glove box, hafnium tetrachloride (2.068 g) and dimethyl ether (DME, 30 g) were loaded into a 4 ounce container (first wide-mouth bottle) to obtain a white mixture. A solution of n-butylcyclopentadienyl lithium (1.68 g) in DME (30 g) was slowly added to the stirred contents of the first wide-mouth bottle to obtain an opaque orange mixture. The mixture was stirred at room temperature (20° C.) overnight (18 h), and then the solvent was removed in vacuo. The resulting residue was absorbed in toluene and placed in a freezer (-30° C.). Pale orange crystals of CEC (0.500 g) were obtained. Characterization: 1 H NMR (400MHz, benzene-d6) δ5.83(t,J=2.7Hz,4H),5.67(t,J=2.7Hz,4H),2.77–2.62(m,4H),1.50–1.36(m,4H),1.22(h,J=7.3Hz,4H),0.84(t,J=7.3Hz,6H).

[0113] Comparative Example D (CE D; spray-dried composition) was prepared as follows. In a nitrogen-purged glove box, hydrophobic fumed silica (CABOSIL TS-610; 2.65 grams) and toluene (70 grams) were added to a container and mixed, followed by the addition of a 10% solution (22 grams) by weight of methylaluminoxane (MAO) in toluene. The contents of the container were then stirred for about 15 minutes. CE C (0.115 grams) was then added to the container and the contents of the container were stirred for about 30 minutes. The contents of the container were then spray dried using a Büchi Mini Spray Drier B-290 (set temperature: 140°C; 100°C outlet temperature; aspirator: 95; pump speed: 150 rpm) to provide Comparative Example D (CE D).

[0114] The polymerization is performed as follows. For the corresponding polymerization, a laboratory-scale gas phase polymerization reactor (a 2-liter stainless steel autoclave equipped with a variable speed mechanical stirrer) is dried at 100°C for one hour, and then loaded with dry NaCl (200g) and heated to 100°C for thirty minutes under a nitrogen stream. The reactor is then purged with nitrogen, 3g of silica-supported methylaluminoxane is added to the reactor as a scavenger, the reactor temperature is adjusted to about the desired temperature, the reactor is sealed, and the contents of the reactor are stirred. The reactor is preloaded to the desired pressure with hydrogen, ethylene and 1-hexene. When steady state is reached, the catalyst is loaded into the reactor (at a temperature of 80°C) to start polymerization. The reactor temperature is maintained at the desired temperature for 60 minutes of polymerization, wherein hydrogen, C6 / C2 ratio and ethylene pressure are kept constant. At the end of 60 minutes of polymerization, the reactor is cooled, vented and opened. The resulting mixture is washed with water and methanol and dried. The polymerization conditions of Examples 3-9 and Comparative Example CO are reported in Table 1.

[0115] A number of properties of the polymers prepared using Examples 3-9 and Comparative Example CO, respectively, were determined and the results are reported in Tables 2 and 3. The polymerization productivity (gram polymer / gram catalyst-hour) was determined as the ratio of the polymer produced to the amount of catalyst added to the reactor. The melt index (I2) was determined according to ASTM D1238 (190°C, 2.16 kg), the melt index (I5) was determined according to ASTM D1238 (190°C, 5 kg), and the melt index (I 21 ) is determined according to ASTM D1238 (190°C, 21.6 kg); the molecular weight comonomer distribution index (MWCDI) is determined as discussed herein. Melt temperature is determined using differential scanning calorimetry according to ASTM D3418-08, using a scan rate of 10°C / min for a 10 mg sample and a second heating cycle to determine Tm . M w 、M n 、M z 、M w / M n (PDI) and M z / M w Determined as discussed above in the Detailed Description.The comonomer content (eg, 1-hexene) incorporated into the polymer is determined by fast FT-IR spectroscopy of the dissolved polymer in a GPC measurement, as discussed above in the Detailed Description.

[0116] Table 1 - Reaction conditions for Examples (EX) 3-9 and Comparative Example CEC-O

[0117]

[0118] Table 2 - Polymer data and BOCD quantification for Examples (EX) 3-9 and Comparative Example CE CO

[0119]

[0120]

[0121] nc – not collected.

[0122] Table 3 - Polymer data and BOCD quantification for Examples (EX) 3-9 and Comparative Example CE CO

[0123]

[0124] nc – not collected.

[0125] The data of Tables 2 to 3 show that the polymers prepared with EX 2 have a larger quantifiable reverse SCBD or BOCD (MWCDI), which is a desired feature. In addition, the polymers prepared with EX 2 also have a higher comonomer incorporation (wt% C6), which is also a desired feature. In addition, EX 2 has the following advantages over CE B catalysts: the productivity of EX 2 is generally higher than that of CE B, and the exception only appears to be that at higher C6 / C2 (e.g., 0.016) and low H2 / C2 (e.g., 0.0005), where increasing H2 / C2 appears to improve the productivity of EX 2 while impairing the productivity of CE B. This would indicate that EX 2 is a more robust catalyst that tolerates a wider range of process conditions. In addition, EX 2 has an improved (i.e., larger) molecular weight comonomer distribution index compared to polymers prepared with CE A or B. In other words, EX 2 is better at incorporating comonomers (e.g., a higher wt% of 1-hexene under the same conditions).

[0126] Figure 1Data plots for determining the MWCDI for Example 3 (MWCDI = 5.91) and for determining the MWCDI for Comparative Example C (MWCDI = 3.6) are shown, as shown in Table 3. Data graph 102 corresponds to the determination of the MWCDI for Example 3. Data graph 104 corresponds to the determination of the MWCDI for Comparative Example C. The polymerization conditions for EX 5, CE E, and CE L represent higher density polymers and show that EX 5 maintains good BOCD and a higher MWCDI than CE E or CE L. EX 7 and CEG were prepared at elevated temperatures (90°C), which negatively affects BOCD. However, EX 7 still maintains good MWCDI values ​​and is significantly higher than CE G. EX 8, CE H, and CE N were polymerized at both high temperature (100°C) and low C6 / C2 (higher density), both of which negatively affect CE H and CE BOCD (MWCDI). Under these more stressful conditions, EX 8 still maintains a fairly high MWCDI. Finally, EX 9, CE I and CE O were prepared at a polymerization temperature of 90°C and high C6 / C2 (low density), but higher H2 / C2), resulting in polymers with melt indices less than 1. EX 9 still has a larger MWCDI than CE I prepared from comparative CE B.

Claims

1. A symmetric hafnium metallocene having an isobutylcyclopentadienyl ligand, wherein the symmetric hafnium metallocene is represented by structure (I): wherein each X is independently a leaving group.

2. The symmetric hafnium metallocene with an isobutylcyclopentadienyl ligand according to claim 1, wherein each X is independently a leaving group selected from halogen, (C1-C5) alkyl, CH2SiMe3 and benzyl.

3. The symmetric hafnium metallocene with an isobutylcyclopentadienyl ligand according to any one of claims 1 to 2, wherein each X is -Cl, and the symmetric hafnium metallocene is represented by structure (II):

4. The symmetric hafnium metallocene with an isobutylcyclopentadienyl ligand according to any one of claims 1 to 2, wherein each X is -CH3, and the symmetric hafnium metallocene is represented by structure (III):

5. A method for synthesizing a symmetrical hafnium metallocene having an isobutylcyclopentadienyl ligand according to any one of claims 1 to 4, the method comprising: The hafnium complex is contacted with an alkali metal complex, wherein the alkali metal complex is represented by the following structure: Where M' is lithium, sodium or potassium, and R 1 is an isobutyl group; and The hafnium complex is hafnium tetrachloride.

6. The method according to claim 5, comprising: The symmetrical hafnium metallocene with isobutylcyclopentadienyl ligand is contacted with two molar equivalents of an organic magnesium halide of formula RMg(halide) or one molar equivalent of R2Mg, wherein R is (C1-C5)alkyl, CH2SiMe3 or benzyl; and the halide is Cl or Br, to prepare the symmetrical hafnium metallocene with isobutylcyclopentadienyl ligand of structure (I), wherein each X is (C1-C5)alkyl, CH2SiMe3 or benzyl.

7. A metallocene catalyst composition, comprising: The symmetrical hafnium metallocene having an isobutylcyclopentadienyl ligand according to any one of claims 1 to 4, or the symmetrical hafnium metallocene having an isobutylcyclopentadienyl ligand prepared by the method according to claim 5 or claim 6; and Activator.

8. The metallocene catalyst composition according to claim 7, further comprising a carrier.

9. The metallocene catalyst composition of claim 8, wherein the composition is a spray-dried metallocene catalyst composition.

10. A method for preparing a metallocene catalyst composition according to any one of claims 7 to 9, the method comprising: contacting the symmetric hafnium metallocene having an isobutylcyclopentadienyl ligand with the activator but without the support to obtain the metallocene catalyst composition without a support; or contacting the symmetrical hafnium metallocene having an isobutylcyclopentadienyl ligand with the activator and the carrier to obtain the metallocene catalyst composition containing the carrier; or contacting the symmetrical hafnium metallocene having an isobutylcyclopentadienyl ligand with the activator and the carrier in an inert solvent; or contacting the symmetrical hafnium metallocene having an isobutylcyclopentadienyl ligand with the activator and the support in an inert solvent to obtain a suspension thereof, and spray-drying the suspension to obtain the spray-dried metallocene catalyst composition; or The symmetric metallocene having an isobutylcyclopentadienyl ligand is contacted in an inert solvent capable of contacting with a supported or spray-dried activator (or a slurry thereof) to obtain the spray-dried metallocene catalyst composition.

11. A method for preparing a polyolefin polymer, the method comprising: At least one olefin monomer is polymerized with the metallocene catalyst composition according to any one of claims 7 to 9 or the metallocene catalyst composition prepared by the method according to claim 10 to prepare the polyolefin polymer; wherein preferably, the at least one olefin monomer comprises ethylene and optionally a comonomer selected from the group consisting of propylene and (C4-C 20 )α-olefins.

12. The method of claim 11, wherein the at least one olefin monomer comprises ethylene and the comonomer; and wherein the polyolefin polymer has a molecular weight comonomer distribution index (MWCDI) of 0.10 to 10.00, as measured by the MWCDI test method described herein; wherein preferably, the comonomer is selected from the group consisting of: 1-butene, 1-hexene and 1-octene.

13. A polyolefin polymer prepared by the process according to any one of claims 11 to 12.

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