Symmetrical zirconium metallocenes with isobutyl cyclopentadienyl ligands

Abstract

Embodiments of the present disclosure relate to symmetric zirconium metallocenes having an isobutyl cyclopentadienyl ligand, compositions comprising those of the symmetric zirconium metallocenes having an isobutyl cyclopentadienyl ligand, and methods of utilizing the compositions comprising the symmetric zirconium metallocenes having an isobutyl cyclopentadienyl ligand.

Description

Technical Field

[0001] Embodiments of the present disclosure are directed to symmetric zirconium metallocenes having isobutylcyclopentadienyl ligands, catalyst compositions comprising symmetric zirconium metallocenes having isobutylcyclopentadienyl ligands, methods of making and using the same, and polyolefins made thereby. Background Art

[0002] Metallocenes can be used in a variety of applications, including as polymerization catalysts. Polymers can be used in a variety of 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 symmetrical zirconium metallocene having an isobutylcyclopentadienyl ligand, wherein the symmetrical zirconium metallocene is represented by structure (I):

[0005]

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

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

[0008] A method for preparing a metallocene catalyst composition comprises contacting a symmetric zirconium 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 zirconium metallocenes with isobutylcyclopentadienyl ligands are discussed herein. Advantageously, these symmetrical zirconium 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. Such polymers are advantageous for many applications. In addition, these catalyst compositions can be used to prepare polymers having improved (i.e., larger) comonomer incorporation (MWCDI) compared to polymers prepared by other metallocenes. 6 wt %) of the polymer.

[0012] As discussed herein, symmetrical zirconium metallocenes with isobutylcyclopentadienyl ligands can also be used to provide polymers with improved reverse short chain branching distribution. The defining 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 percent (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). This type of distribution is usually achieved using a dual reactor configuration and a single or dual catalyst process. In a dual reactor process, a single catalyst can be used to prepare a high MW lower density component (with a higher wt % comonomer) and a low MW high density (lower wt % comonomer) component 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 zirconium metallocenes with isobutylcyclopentadienyl ligands of the present disclosure provide the ability to produce polymers with improved BOCD resins in a single reactor, especially those that have a measurable greater tendency to contain comonomers in the 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 zirconium 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 zirconium metallocene catalyst to be multisite and produce polymers with BOCD.

[0014] A symmetric zirconium 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 the 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, (C 1 -C 5 ) alkyl, CH 2 SiMe 3 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, (C 1 To C 12 ) alkyl, (C 2 To C 12 ) alkenyl, (C 6 To C 12 ) aryl, (C 7 To C 20 ) alkylaryl, (C 1 To C 12 ) alkoxy, (C 6 To C 16 ) aryloxy, (C 7 To C 8 ) alkylaryloxy, (C 1 To C 12 ) fluoroalkyl, (C 6 To C 12 ) fluoroalkyl and (C 1 To C 12 ) heteroatom-containing hydrocarbons and their substituted derivatives; one or more embodiments include hydrides, halides, (C 1 To C 6 ) alkyl, (C 2 To C 6 ) alkenyl, (C 7To C 18 ) alkylaryl, (C 1 To C 6 ) alkoxy, (C 6 To C 14 ) aryloxy, (C 7 To C 16 ) alkylaryloxy, (C 1 To C 6 ) alkyl carboxylate, (C 1 To C 6 ) fluorinated alkyl carboxylate, (C 6 To C 12 ) aryl carboxylate, (C 7 To C 18 ) alkyl aryl carboxylate, (C 1 To C 6 ) fluoroalkyl, (C 2 To C 6 ) fluoroalkenyl and (C 7 To C 18 ) fluoroalkylaryl; one or more embodiments include hydride, chloride, fluoride, methyl, phenyl, phenoxy, benzoyloxy, tosyl, fluoromethyl and fluorophenyl; one or more embodiments include (C 1 To C 12 ) alkyl, (C 2 To C 12 ) alkenyl, (C 6 To C 12 ) aryl, (C 7 To C 20 ) alkylaryl, substituted (C 1 To C 12 ) alkyl, substituted (C 6 To C 12 ) aryl, substituted (C 7 To C 20 ) alkylaryl and (C 1 To C 12 ) containing heteroatom alkyl, (C 1 To C 12 ) containing heteroatom aromatic groups and (C 1 To C 12 ) containing heteroatom alkylaryl; one or more embodiments include chloride, fluoride, (C 1 To C 6 ) alkyl, (C 2 To C 6 ) alkenyl, (C 7 To C 18 ) alkylaryl, halogenated (C 1 To C 6 ) alkyl, halogenated (C 2 To C6 )alkenyl and halo (C 7 To 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 having 1 to 20 carbon atoms, fluorinated hydrocarbon groups (e.g., -C 6 F 5 (pentafluorophenyl)), fluorinated alkyl carboxylates (e.g., CF 3 C(O)O-), hydrides, halides, 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, among others. In one embodiment, two or more X form a fused ring or part of a ring system. In one or more embodiments, X can be a leaving group selected from the group consisting of chloride, bromide, (C(O)O-), halides, and combinations thereof. 1 To C 10 ) alkyl, (C 2 To C 12 ) alkenyl, carboxylate, acetylacetonate, and alcoholate. In one or more embodiments, X is methyl.

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

[0021] The alkali metal complex 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 zirconium complex can be zirconium tetrachloride.

[0025] One or more embodiments provide that a method of preparing a symmetric zirconium metallocene having an isobutylcyclopentadienyl ligand (e.g., wherein each X is Cl) comprises reacting the symmetric zirconium metallocene having an isobutylcyclopentadienyl ligand with two molar equivalents of an organomagnesium halide of the formula RMg(halide) or one molar equivalent of R 2 Mg contact, where R is (C 1 -C 5 ) alkyl, CH 2 SiMe 3 or benzyl; and the halide is Cl or Br, to prepare a symmetrical zirconium metallocene of structure (I), wherein each X is a halogen, (C 1 -C 5 ) alkyl, CH 2 SiMe 3 Or benzyl. One or more embodiments provide that X is (C 1 -C 5 ) alkyl, CH 2 SiMe 3 or benzyl. One or more embodiments provide that X is Cl or CH 3 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 groups lacking one hydrogen. Thus, for example, CH 3 ("methyl") and CH 2 CH 3 ("ethyl") is an example of an alkyl group.

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

[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 C 6 To C 20 Aryl groups. For example, C 6 H 5 The aromatic structure is "phenyl", C 6 H 42 aromatic structure is a "phenylene". An "aralkyl" group is an alkyl group with a pendant aryl group. It is understood that an "aralkyl" group can be (C 7 To 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 chain, and cyclic hydrocarbon groups lacking two hydrogen atoms. 2 ("methylene") and CH 2 CH 2 ("Ethylene") is an example of an alkylene group. Other groups lacking two hydrogen radicals 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 particular embodiment. Non-limiting examples of heteroatom-containing groups include groups (monovalent and divalent) 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] Symmetrical zirconium metallocenes with isobutylcyclopentadienyl ligands discussed herein can be used to prepare catalyst compositions. These compositions comprise symmetrical zirconium 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 a cationic species of the catalyst component. For example, this can include capturing at least one leaving group, such as the "X" group described herein, from the metal center of the complex / catalyst component (e.g., the symmetrical zirconium 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 a metal atom and can be captured by an activator, 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. Different amounts of known catalyst composition components can be used for different applications.

[0033] Symmetrical zirconium metallocenes with isobutylcyclopentadienyl ligands discussed herein can be used to prepare spray-dried compositions. As used herein, "spray-dried composition" refers to a composition comprising a number of components that has 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 the spray-dried composition to include a conditioning composition.

[0034] In one or more embodiments, the spray drying method can include atomizing a composition comprising a symmetrical zirconium metallocene with an isobutylcyclopentadienyl ligand as discussed herein. Many other known components can be used in the spray drying process. Atomizers such as atomizing nozzles or centrifugal high-speed disks can be used, for example, to produce a spray or dispersion of composition droplets. The droplets of the composition can then be quickly dried by contacting with an inert dry gas. The inert dry gas can be any gas that is not reactive under the conditions used during atomization, such as nitrogen. The inert dry gas can encounter the composition at the atomizer, which produces a droplet stream on a continuous basis. The dried composition particles can be captured from the process in a separator (such as a cyclone separator), which can separate the formed solid 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 a solution of a spray-dried activator particle (such as spray-dried MAO) with a symmetrical zirconium metallocene with an isobutylcyclopentadienyl ligand as discussed herein. Such solutions can be prepared, for example, in an inert hydrocarbon solvent, and are sometimes referred to as adjustment solutions. Such spray-dried compositions including contacting an adjustment solution of a symmetrical zirconium metallocene with an isobutylcyclopentadienyl ligand 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 a feed line to a gas phase polymerization reactor. Alternatively, the spray-dried composition can be formed by contacting a slurry of spray-dried activator particles (such as a mineral oil slurry of spray-dried activator particles) with a symmetrical zirconium metallocene with an isobutylcyclopentadienyl ligand as discussed herein.

[0037] Various spray drying conditions can be used for different applications. For example, the spray drying process 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 nozzles 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] Symmetrical zirconium metallocenes with isobutylcyclopentadienyl ligands discussed herein (e.g., catalyst compositions, such as spray-dried zirconium metallocene compositions) can be used to prepare polymers. For example, symmetrical zirconium 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 zirconium in the symmetric zirconium 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 zirconium in the symmetric zirconium metallocene with isobutylcyclopentadienyl ligands is at least 75:1. One or more embodiments provide that the molar ratio of the activator to the zirconium in the symmetric zirconium metallocene with isobutylcyclopentadienyl ligands is at least 100:1. One or more embodiments provide that the molar ratio of the activator to the zirconium in the symmetric zirconium metallocene with isobutylcyclopentadienyl ligands is at least 150:1.

[0040] Symmetrical zirconium 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 the carrier can be achieved by any technology used in the art. One or more embodiments provide for the use of a spray drying process. 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 zirconium 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 for the spray-dried composition to include 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, and one or more embodiments provide that the support is hydrophobic fumed 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 zirconium 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 solution polymerization process, 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 by 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 polyolefins prepared with the compositions 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 polyolefins prepared with the compositions discussed herein can be prepared 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 having 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 to 250; 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 the monomer and hexene is used as the comonomer. The fluidized bed reactor may have a comonomer to ethylene molar ratio of 0.0001 to 0.100, for example, C 6 / C 2 0.0001 to 0.100 including all individual values ​​and subranges; for example, the fluidized bed reactor can have a comonomer to ethylene molar ratio ranging from a lower limit 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 may have a hydrogen to ethylene molar ratio (H2) of, for example, 0.00001 to 0.90000. 2 / C 2 ). All individual values ​​and subranges from 0.00001 to 0.90000 are included; for example, a fluidized bed reactor can have a H with a lower limit of 0.00001, 0.00005, or 0.00008 and an upper limit of 0.90000, 0.500000, 0.10000, 0.01500, 0.00700, or 0.00500. 2 / C 2 One or more embodiments provide that hydrogen is not utilized.

[0051] 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.

[0052] 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)):

[0053] M 聚乙烯 =A×(M 聚苯乙烯 ) B (Equation 1)

[0054] Where M is the molecular weight, A has a value of 0.4061, and B equals 1.0.

[0055] A fifth-order polynomial was used to fit the calibration points to the corresponding polyethylene equivalents.

[0056] 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.

[0057] 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.

[0058] Mn was determined based on GPC results using the internal IR5 detector (measurement channel) of a PolymerChar GPC-IR spectrometer according to Equations 2-4 using the PolymerChar GPCONE software, the baseline-subtracted IR chromatogram at each equally spaced 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:

[0059]

[0060] To monitor the deviation over time, a flow rate marker (decane) was introduced into each sample via a micropump controlled by the PolymerChar GPC-IR system. This flow marker (FM) was used to linearly calibrate the pump flow (flow (标称) ): The RV of the corresponding decane peak in the sample (RV (FM样品) ) with the decane peak within the narrow standard calibration (RV (FM校准) ) were compared. It was then assumed that any changes in the decane marker peak time were related to the flow rate (flow rate (有效) ). After calibrating the system based on the flow marker peak, the effective flow rate (relative to the narrow standard calibration) is calculated according to Equation 5. TM The software completes the processing of the flow marker peaks. An acceptable flow rate correction is such that the effective flow rate should be within + / - 0.5% of the nominal flow rate.

[0061] Flow rate (effective) = flow rate (nominal) × (RV (FM calibration) / 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] Comonomer weight % IR5 Area Ratio SCB / 1000Total C M Mw / Mn 23.1 0.2411 28.9 37,300 2.22 14.0 0.2152 17.5 36,000 2.19 0.0 0.1809 0.0 38,400 2.20 35.9 0.2708 44.9 42,200 2.18 5.4 0.1959 6.8 37,400 2.16 8.6 0.2043 10.8 36,800 2.20 39.2 0.2770 49.0 125,600 2.22 1.1 0.1810 1.4 107,000 2.09 14.3 0.2161 17.9 103,600 2.20 9.4 0.2031 11.8 103,200 2.26

[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 % = A 0 +[A 1 ×(IR5 甲基通道面积 / IR5 测量通道面积 )](Equation 6)

[0067] Among them A 0 is the "comonomer weight %" intercept at the "IR5 area ratio" of zero, and A 1 is the slope of "Comonomer wt%" versus "IR5 Area Ratio" and represents the increase in comonomer wt% as a function of "IR5 Area Ratio." For the narrow PDI and narrow SCBD standard materials, the IR5 Area Ratio is equal to the IR5 Height Ratio.

[0068] 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 graphs for determining the MWCDI for Example 1-2 (MWCDI = 1.41) and for determining the MWCDI for Comparative Example A-2 (MWCDI = 0.52) are shown, as shown in Table 1 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 1, Example 1-2 has an increased BOCD compared to Comparative Example A-2. 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.

[0069] 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 of 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.

[0070] The polymers prepared using the compositions disclosed herein may have a hardness of 0.8700 g / cm 3 Up to 0.9700g / cm 3 Density. Including 0.8700g / cm 3 Up to 0.9700g / cm 3 All individual values ​​and subranges of; for example, a polymer may have a lower limit of 0.8700 g / cm 3 , 0.9000g / cm 3 、0.9100g / cm 3 、0.9150g / cm 3 , 0.9200g / cm 3or 0.9250g / cm 3 The upper limit is 0.9700g / cm 3 , 0.9600g / cm 3 , 0.9500g / cm 3 、0.9450g / cm 3 、0.9350g / cm 3 or 0.9300g / cm 3 Density. Density can be determined according to ASTM D792.

[0071] The polymer prepared with the composition disclosed herein can have a weight average molecular weight (Mw) of 5,000 g / mol to 750,000 g / mol. All individual values ​​and subranges of 5,000 g / mol to 750,000 g / mol are included; for example, the polymer can have a lower limit of 5,000 g / mol, 10,000 g / mol or 15,000 g / mol to an upper limit of 750,000 g / mol, 500,000 g / mol or 200,000 g / mol Mw. As known in the art, Mw can be determined by gel permeation chromatography (GPC). GPC is discussed herein.

[0072] The polymers prepared with the compositions disclosed herein can have a number average molecular weight (Mn) of 3,000 g / mol to 300,000 g / mol. All individual values ​​and subranges of 3,000 g / mol to 300,000 g / mol are included; for example, the polymer can have a Mn with a lower limit of 3,000 g / mol, 5,000 g / mol, or 10,000 g / mol to an upper limit of 300,000 g / mol, 250,000 g / mol, or 200,000 g / mol. Mn can be determined by GPC.

[0073] The polymer prepared with the composition disclosed herein can have a Z average molecular weight (Mz) of 20,000 g / mol to 2,000,000 g / mol. All individual values ​​and subranges of 20,000 g / mol to 2,000,000 g / mol are included; for example, the polymer can have a lower limit of 20,000 g / mol, 25,000 g / mol, or 30,000 g / mol to an upper limit of 2,000,000 g / mol, 1,000,000 g / mol, 500,000 g / mol, or 200,000 g / mol. Mz can be determined by GPC.

[0074] The polymers prepared with the compositions disclosed herein can have a ratio of weight average molecular weight to number average molecular weight (Mw / Mn) from 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.

[0075] Various aspects of the disclosure are provided as follows.

[0076] Aspect 1 provides a symmetrical zirconium metallocene having an isobutylcyclopentadienyl ligand represented by structure (I):

[0077]

[0078] wherein each X is independently a leaving group.

[0079] Aspect 2 provides a symmetrical zirconium metallocene with an isobutylcyclopentadienyl ligand according to aspect 1, wherein each X is independently a leaving group selected from the group consisting of: halogen, (C 1 -C 5 ) alkyl, CH 2 SiMe 3 and benzyl.

[0080] Aspect 3 provides a ligand having an isobutyl cyclopentadienyl group according to any one of aspects 2 to 3, wherein each X is Cl or each X is CH 3 , the symmetrical zirconium metallocenes are represented by structures (II) and (III), respectively:

[0081]

[0082] Aspect 4 provides a method for synthesizing a symmetrical zirconium metallocene having an isobutylcyclopentadienyl ligand according to any one of aspects 1 to 3, the method comprising:

[0083] The zirconium complex is contacted with an alkali metal complex, wherein the alkali metal complex is represented by the following structure:

[0084]

[0085] Where M' is lithium, sodium or potassium, and R 1 is an isobutyl group; and the zirconium complex is zirconium tetrachloride.

[0086] Aspect 5 provides a method according to aspect 4, comprising: reacting a symmetrical zirconium metallocene having an isobutylcyclopentadienyl ligand with two molar equivalents of an organic magnesium halide of formula RMg(halide) or one molar equivalent of R 2 Mg contact, where R is (C1 -C 5 ) alkyl, CH 2 SiMe 3 or benzyl; and the halide is Cl or Br, to prepare a symmetrical zirconium metallocene with an isobutylcyclopentadienyl ligand of structure (I), wherein each X is (C 1 -C 5 ) alkyl, CH 2 SiMe 3 or benzyl.

[0087] Aspect 6 provides a metallocene catalyst composition, which comprises: a symmetrical zirconium metallocene with an isobutylcyclopentadienyl ligand according to any one of Aspects 1 to 3, or a symmetrical zirconium metallocene with an isobutylcyclopentadienyl ligand prepared by the method of Aspect 4 or Aspect 5; and an activator (e.g., an alkylaluminoxane, such as methylaluminoxane).

[0088] Aspect 7 provides the metallocene catalyst composition according to aspect 6, further comprising a support (eg, silica, such as hydrophobic fumed silica or dehydrated silica).

[0089] Aspect 8 provides the metallocene catalyst composition according to aspect 7, wherein the composition is a spray-dried metallocene catalyst composition.

[0090] Aspect 9 provides a method for preparing a metallocene catalyst composition according to any one of Aspects 6 to 8, the method comprising: contacting a symmetric zirconium 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 zirconium metallocene having an isobutylcyclopentadienyl ligand with the activator and the carrier to obtain the metallocene catalyst composition with the carrier; or contacting the symmetric zirconium metallocene having an isobutylcyclopentadienyl ligand with the activator and the carrier in an inert solvent; contacting the symmetric zirconium metallocene having an isobutylcyclopentadienyl ligand with an activator and a carrier in an inert solvent to obtain a suspension thereof, and spray drying the suspension to obtain a spray-dried metallocene catalyst composition; or contacting the 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.

[0091] Aspect 10 provides a method for preparing a polyolefin polymer, the method comprising: polymerizing at least one olefin monomer with a metallocene catalyst composition according to any one of claims 6 to 8 or a metallocene catalyst composition prepared by the method according to claim 9 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 (C 4 -C 20 )α-olefins.

[0092] Aspect 11 provides a method according to aspect 10, 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) from 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.

[0093] Aspect 12 is a polyolefin polymer prepared by the method according to any one of aspects 10 to 11.

[0094] Example

[0095] 5-(2-methylpropylene)cyclopenta-1,3-diene, which can be represented by the following formula:

[0096]

[0097] was synthesized as follows. In a glove box, pyrrolidine (1.45 g, 10 mol%) was added to a mixture containing isobutylaldehyde (14.6 g, 203 mmol) and cyclopentadiene (13.4 g, 203 mmol) in MeOH-H 2 O (200mL 4 / 1) in a glass container. The contents of the container were transferred to an ice-cold mixture of saline solution and 10mol% 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 (400 MHz, CDCl 3 )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 (101 MHz, CDCl3 )δ:149.88,143.69,133.08,130.87,126.06,119.36,30.58,23.24.

[0098] Isobutylcyclopentadienyllithium, which can be represented by the following formula:

[0099]

[0100] are synthesized as follows.

[0101] Et 2 O (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. LiAlH 4 (33 mL, 4M Et 2 O solution) was added dropwise to the contents of the container while stirring. Foaming was observed. A white solid precipitated during the addition, and as LiAlH 4 The addition was continued and the yellow color gradually faded. The addition was stopped once the solution became only light yellow. The product, isobutylcyclopentadienyllithium, was observed to be a white solid and collected by filtration and washed with Et 2 O and dried under vacuum (13.7 g, 80%).

[0102] Example 1-1 (a symmetric zirconium metallocene represented by structure (I) having an isobutylcyclopentadienyl ligand as previously discussed) was prepared as follows.

[0103] Isobutylcyclopentadienyl lithium (0.150 g, 17.7 mmol) and zirconium tetrachloride (0.136 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 a slightly yellow residue. The residue was extracted with dichloromethane and then filtered. The resulting solution was placed under vacuum to obtain Example 1-1 (0.207 g, 87%). 1 H NMR (400 MHz, C 6 D 6 ): δ5.91(t,J=2.7Hz,1H), 5.73(t,J=2.7Hz,1H), 2.55(d,J=7.0Hz,1H), 1.63(dp,J=13.5,6.8Hz,1H), 0.79(d,J=6.6Hz,3H). 13 C NMR (101 MHz, C 6 D 6 ): δ132.75,117.48,111.48,39.57,30.17,22.06.

[0104] Example 1-2, a spray-dried composition, was prepared as follows. In a nitrogen-purged glove box, hydrophobic fumed silica (CABOSIL TS-610; 1.33 g) and toluene (37.5 g) were added to a container and mixed, followed by the addition of a 10% solution (11 g) by weight of methylaluminoxane (MAO) in toluene. The contents of the container were then stirred for about 15 minutes. Example 1-1 (0.040 g) 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 Buchi Mini Spray Drier B-290 (set temperature: 140°C; 100°C outlet temperature; pump speed: 150 rpm) to provide Example 1-2.

[0105] Comparative Example A-1, a zirconium metallocene with two n-butylcyclopentadienyl ligands (bis-(n-butylcyclopentadienyl)zirconium dichloride), was commercially available from Boulder Scientific Company.

[0106] Comparative Example A-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. Comparative Example A-1 (0.050 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 Buchi Mini Spray Drier B-290 (set temperature: 140°C; 100°C outlet temperature; aspirator: 95; pump speed: 150 rpm) to provide Comparative Example A-2.

[0107] Polymerization is performed as follows. For the corresponding polymerization, dry NaCl (200 g) is loaded into a laboratory-level gas phase polymerization reactor (equipped with a 2-liter stainless steel autoclave of a variable speed mechanical stirrer) and heated to 100 ° C for one hour under a nitrogen stream. The reactor is then purged with nitrogen, the methylaluminoxane supported by silica 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 stirring reactor are stirred. The reactor is preloaded to the desired pressure with hydrogen, ethylene and 1-hexene. When reaching a steady state, the catalyst is loaded into the reactor (at the temperature indicated below) to start polymerization. The reactor temperature is maintained at the desired temperature for 60 minutes of polymerization, wherein hydrogen, C 6 / C 2The ratio and ethylene pressure were kept constant. At the end of the 60-minute polymerization, the reactor was cooled, vented and opened. The resulting mixture was washed with water and methanol and dried. The polymerization conditions are reported in Tables 1 to 3.

[0108] Various properties of the polymers prepared using Examples 1-2 and Comparative Example A-2, respectively, were determined. The results are reported in Table 1. 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. Melt index (I 2 ) is determined according to ASTM D1238 (190°C, 2.16kg), the melt index (I 5 ) is determined according to ASTM D1238 (190°C, 5kg), melt index (I 21 ) was determined according to ASTM D1238 (190°C, 21.6 kg); the melt temperature was determined using differential scanning calorimetry according to ASTM D3418-08, using a scan rate of 10°C / min for a 10 mg sample and using a second heating cycle to determine T m Mw, Mn, Mz and Mw / Mn are determined by GPC; the molecular weight comonomer distribution index (MWCDI) is determined as discussed herein.

[0109] Table 1

[0110]

[0111]

[0112] Table 2

[0113]

[0114]

[0115] Table 3

[0116]

[0117]

[0118] The data in Tables 1-3 show that the polymers prepared with Examples 1-2 have an improved (ie, greater) molecular weight comonomer distribution index (MWCDI) compared to the polymer prepared with Comparative Example A-2.

[0119] In addition, the data in Tables 1 to 3 show that the polymers prepared using Examples 1-2 have improved (i.e., greater) comonomer incorporation (C6 weight%).

[0120] Figure 1 Data graphs for determining the MWCDI for Example 1-2 (MWCDI = 1.41) and for determining the MWCDI for Comparative Example A-2 (MWCDI = 0.52) are shown as shown in Table 1. Data graph 102 corresponds to the determination of the MWCDI for Example 1-2. Data graph 104 corresponds to the determination of the MWCDI for Comparative Example A-2.

Claims

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

2. A symmetric zirconium 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. A symmetrical zirconium metallocene with an isobutylcyclopentadienyl ligand according to any one of claims 2 to 3, wherein each X is Cl or each X is CH3, and the symmetrical zirconium metallocene is represented by structures (II) and (III), respectively:

4. A method for synthesizing a symmetrical zirconium metallocene having an isobutylcyclopentadienyl ligand according to any one of claims 1 to 3, the method comprising: The zirconium 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 zirconium complex is zirconium tetrachloride.

5. The method according to claim 4, comprising: The symmetrical zirconium 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 zirconium metallocene with isobutylcyclopentadienyl ligand of structure (I), wherein each X is (C1-C5)alkyl, CH2SiMe3 or benzyl.

6. A metallocene catalyst composition, comprising: The symmetrical zirconium metallocene having an isobutylcyclopentadienyl ligand according to any one of claims 1 to 3, or the symmetrical zirconium metallocene having an isobutylcyclopentadienyl ligand prepared by the method according to claim 4 or claim 5; and Activator. 7 . The metallocene catalyst composition according to claim 6 , further comprising a carrier.

8. The metallocene catalyst composition of claim 7, wherein the composition is a spray-dried metallocene catalyst composition.

9. A method for preparing a metallocene catalyst composition according to any one of claims 6 to 8, the method comprising: contacting the symmetric zirconium metallocene having an isobutylcyclopentadienyl ligand with the activator but without the support to obtain the metallocene catalyst composition without a support; Alternatively, the symmetrical zirconium metallocene having an isobutylcyclopentadienyl ligand is contacted with the activator and the carrier to obtain the metallocene catalyst composition with the carrier; or the symmetrical zirconium metallocene having an isobutylcyclopentadienyl ligand is contacted with the activator and the carrier in an inert solvent; or the symmetrical zirconium metallocene having an isobutylcyclopentadienyl ligand is contacted with the activator and the carrier in an inert solvent to obtain a suspension thereof, and the suspension is spray-dried to obtain the spray-dried metallocene catalyst composition; or the symmetrical metallocene having an isobutylcyclopentadienyl ligand in an inert solvent is contacted with a supported or spray-dried activator (or its slurry) to obtain the spray-dried metallocene catalyst composition.

10. 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 6 to 8 or the metallocene catalyst composition prepared by the method according to claim 9 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.

11. The method of claim 10, 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) from 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.

12. A polyolefin polymer prepared by the process according to any one of claims 10 to 11.

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