Metal-ligand complex, catalyst composition for producing ethylene polymer containing the same, and method for producing ethylene polymer using the same

Abstract

The present invention relates to a metal-ligand complex having significantly improved high-temperature activity due to increased resistance and stability of the catalyst against impurities such as oxygen and moisture by introducing a specific functional group, a catalyst composition for producing an ethylene polymer containing the same, and a method for producing an ethylene polymer using the same.

Description

[Technical field]

[0001] The present invention relates to a metal-ligand complex, a catalyst composition for producing an ethylene polymer containing the same, and a method for producing an ethylene polymer using the same. [Background technology]

[0002] Conventionally, the production of ethylene-based polymers such as copolymers of ethylene and α-olefins or copolymers of ethylene and olefin-diene has generally used the so-called Ziegler-Natta catalyst system, which is composed of a titanium or vanadium compound as the main catalyst component and an alkylaluminum compound as the cocatalyst component.

[0003] U.S. Patent Nos. 3,594,330 and 3,676,415 disclose improved Ziegler-Natta catalysts. Although Ziegler-Natta catalyst systems exhibit high activity in ethylene polymerization, they have the disadvantage that the polymers generally produced have a wide molecular weight distribution due to non-uniform catalytic active sites, and in particular, the composition distribution of copolymers of ethylene and α-olefins is not uniform.

[0004] Since then, various researches have been conducted on metallocene catalyst systems consisting of metallocene compounds of transition metals in Group 4 of the periodic table, such as zirconium and hafnium, and methylaluminoxane as a co-catalyst, which are homogeneous catalysts with a single type of catalytic activity and can produce polyethylene with a narrower molecular weight distribution and more uniform composition distribution than the existing Ziegler-Natta catalyst systems.

[0005] For example, European Patent Publication Nos. 320,762 and 372,632 disclose that by activating metallocene compounds such as Cp2TiCl2, Cp2ZrCl2, Cp2ZrMeCl, Cp2ZrMe2, and ethylene (IndH4)2ZrCl2 with the cocatalyst methylaluminoxane, ethylene can be polymerized with high activity to produce polyethylene with a molecular weight distribution (Mw / Mn) in the range of 1.5 to 2.0.

[0006] However, it is difficult to obtain a high molecular weight polymer with the above catalyst system.

[0007] That is, when applied to a solution polymerization method carried out at high temperatures, it is known that the polymerization activity decreases rapidly and the β-hydrogen elimination reaction predominates, making it unsuitable for producing a high molecular weight polymer.

[0008] On the other hand, organometallic catalysts are often complicated and expensive to manufacture. In addition, the catalyst may be exposed to air during the manufacturing process, storage, or transportation, which may cause the catalyst to lose activity or, in the worst case, cause the catalyst to be discarded because it cannot be used. From the perspective of catalyst manufacturers and catalyst users, a catalyst that is stable against oxygen and moisture in the air is surely a great advantage.

[0009] Therefore, the chemical industry still needs catalysts and catalyst precursors with desired improved properties, and therefore there is a strong need for research into competitive catalysts with properties such as excellent stability, high temperature activity, reactivity with higher α-olefins, and the ability to produce polymers with high molecular weights. Summary of the Invention [Problem to be solved by the invention]

[0010] Therefore, in order to alleviate the above problems, the present invention provides a metal-ligand complex having a specific functional group and a catalyst composition containing the same.

[0011] The present invention also provides a process for producing an ethylene polymer using the catalyst composition of the present invention. [Means for solving the problem]

[0012] The present invention provides a metal-ligand complex having significantly improved high-temperature activity by increasing the catalyst's resistance to impurities such as oxygen and moisture and its stability at high temperatures through the introduction of a specific functional group, and the metal-ligand complex of the present invention is represented by the following chemical formula 1. [ka] (In the above Chemical Formula 1, M is a transition metal of Group 4 of the periodic table; Ar1 and Ar2 are each independently a C6-C20 aryl, and the aryl of Ar1 and Ar2 may be further substituted with a C1-C20 alkyl; R1 to R4 are each independently C1-C20 alkyl, C6-C20 aryl, or C6-C20 arylC1-C20 alkyl; R5 and R6 are each independently a C1-C20 alkyl group; R7 and R8 are each independently a halogen or a C1-C20 alkyl; a, b, c, d, e and f are each independently an integer from 0 to 4; m is an integer from 2 to 5.

[0013] The present invention also provides a catalyst composition for producing ethylene polymers which comprises the metal-ligand complex of the present invention and a cocatalyst.

[0014] The present invention also provides a method for producing an ethylene-based polymer, comprising the step of polymerizing ethylene or ethylene and an α-olefin in the presence of the catalyst composition for producing an ethylene-based polymer of the present invention to produce an ethylene-based polymer. Effect of the Invention

[0015] The metal-ligand complex of the present invention has a significantly improved stability due to the introduction of a specific functional group, and can promote polymerization at high polymerization temperatures without a decrease in catalytic activity.

[0016] In particular, the metal-ligand complex of the present invention has the advantage that it has relatively excellent resistance to impurities such as oxygen and moisture, and can produce a high molecular weight ethylene polymer at a high polymerization temperature.

[0017] That is, when a catalyst composition containing the metal-ligand complex of the present invention is used in the production of an ethylene-based polymer, i.e., an ethylene homopolymer or a copolymer of ethylene and an alpha-olefin, a high molecular weight ethylene homopolymer or a copolymer of ethylene and an alpha-olefin can be efficiently produced at a high polymerization temperature of 220°C or higher due to its excellent catalytic activity.

[0018] This is due to the structural characteristics of the metal-ligand complex according to the present invention. The metal-ligand complex according to the present invention has excellent resistance to impurities and thermal stability, and therefore has the advantages of maintaining high catalytic activity even at high temperatures, and having good copolymerization reactivity with olefins, allowing the production of high-molecular-weight ethylene polymers in high yields.

[0019] Therefore, the metal-ligand complex of the present invention and the catalyst composition containing the same can be used very effectively in the production of ethylene polymers having excellent physical properties. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, the metal-ligand complex of the present invention, the catalyst composition for producing an ethylene polymer containing the same, and the process for producing an ethylene polymer using the same will be described in detail. Unless otherwise defined, technical and scientific terms used herein have the meanings that are commonly understood by those having ordinary skill in the technical field to which the present invention belongs, and descriptions of known functions and configurations that may make the gist of the present invention unclear from the following description will be omitted.

[0021] The following terms used herein are defined as follows, but are for illustrative purposes only and are not intended to be limitations of the present invention, application or use.

[0022] As used herein, the terms "substituent," "radical," "group," "moiety," and "fragment" may be used interchangeably.

[0023] As used herein, the term "CA-CB" means "having a carbon number of A or more and B or less."

[0024] As used herein, the term "alkyl" refers to a linear or branched saturated hydrocarbon monovalent radical composed solely of carbon and hydrogen atoms. The alkyl may have, but is not limited to, 1-20 carbon atoms, 1-10 carbon atoms, 1-5 carbon atoms, 5-20 carbon atoms, 8-20 carbon atoms, or 8-15 carbon atoms. Specific examples of the alkyl include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, i-butyl, t-butyl, pentyl, i-pentyl, methylbutyl, n-hexyl, t-hexyl, methylpentyl, dimethylbutyl, heptyl, ethylpentyl, methylhexyl, dimethylpentyl, n-octyl, t-octyl, dimethylhexyl, ethylhexyl, n-decyl, t-decyl, n-dodecyl, t-dodecyl, and the like.

[0025] The term "aryl" as used herein refers to a monovalent organic radical derived from an aromatic hydrocarbon by removal of one hydrogen, and includes single or fused ring systems, suitably containing 4 to 7, preferably 5 or 6 ring atoms in each ring, including multiple aryls linked by single bonds. Specific examples of the aryl include, but are not limited to, phenyl, naphthyl, biphenyl, fluorenyl, phenanthrenyl, anthracenyl, triphenylenyl, pyrenyl, chrysenyl, naphthacenyl, etc.

[0026] The term "alkylaryl" as used herein means an aryl radical substituted with at least one alkyl, where "alkyl" and "aryl" are as defined above. Specific examples of the alkylaryl include, but are not limited to, tolyl, etc.

[0027] The term "arylalkyl" as used herein means an alkyl radical substituted with at least one aryl, where "alkyl" and "aryl" are as defined above. Specific examples of the arylalkyl include, but are not limited to, benzyl.

[0028] The present invention relates to a metal-ligand complex having a specific functional group, and provides a metal-ligand complex represented by the following chemical formula 1.

[0029] [ka]

[0030] (In the above Chemical Formula 1, M is a transition metal of Group 4 of the periodic table; Ar1 and Ar2 are each independently a C6-C20 aryl, and the aryl of Ar1 and Ar2 may be further substituted with a C1-C20 alkyl; R1 to R4 are each independently C1-C20 alkyl, C6-C20 aryl, or C6-C20 arylC1-C20 alkyl; R5 and R6 are each independently a C1-C20 alkyl group; R7 and R8 are each independently a halogen or a C1-C20 alkyl; a, b, c, d, e and f are each independently an integer from 0 to 4; m is an integer from 2 to 5.

[0031] In one embodiment, the metal-ligand complex can be significantly improved in stability by introducing a specific functional group, an aryloxy group, as a leaving group, thereby increasing the resistance of the catalyst to impurities such as oxygen and moisture and maintaining a strong bond between the central transition metal and the ligand.

[0032] In addition, the metal-ligand complex according to one embodiment has a significantly improved solubility in organic solvents due to the introduction of an aryloxy group instead of a methyl group as a leaving group, thereby making it possible to improve the efficiency of the polymerization process.

[0033] Due to the above-mentioned structural features, the metal-ligand complex has not only significantly improved solubility in hydrocarbon solvents, but also relatively high resistance to impurities and excellent thermal stability, so that it maintains high catalytic activity even at high temperatures and has good polymerization reactivity with other olefins, and can produce high molecular weight ethylene polymers in high yields, and is therefore commercially viable compared to known metallocene and nonmetallocene single active site catalysts.

[0034] Preferably, in the formula 1 according to an embodiment, Ar1 and Ar2 are each independently a C6-C20 aryl or a C1-C20 alkyl C6-C20 aryl, R1 to R4 are each independently a C1-C20 alkyl, R7 and R8 are each independently a halogen or a C1-C20 alkyl, a, b, c, d, e and f are each independently an integer of 1 to 3, and m may be an integer of 3 to 5. More preferably, Ar 1 and Ar2 are each independently a C6-C12 aryl or a C1-C20 alkyl C6-C12 aryl; R1-R4 are each independently a C1-C10 alkyl; R5 and R6 are each independently a C1-C10 alkyl; R7 and R8 are each independently a halogen or a C1-C10 alkyl; a, b, c, d, e and f are each independently an integer of 1 or 2; and m may be an integer of 3 to 5.

[0035] In one embodiment, M may be titanium, zirconium or hafnium.

[0036] In one embodiment, Ar1 and Ar2 are each independently an aryl substituted or unsubstituted with a C1-C20 alkyl, where the aryl may be phenyl, biphenyl, naphthyl, anthracenyl, pyrenyl, phenanthrenyl, or tetracenyl.

[0037] In one specific example, R1 to R4 may be, independently of each other, a branched C3-C10 alkyl, a branched C3-C7 alkyl, or a branched C3-C4 alkyl.

[0038] In order to have improved resistance, thermal stability and excellent catalytic activity, the metal-ligand complex according to an embodiment may be preferably represented by the following Formula 2-1 or 2-2.

[0039] [ka]

[0040] [ka]

[0041] (In the above chemical formulas 2-1 and 2-2, M is titanium, zirconium or hafnium; Ar1 and Ar2 are, independently of each other, C6-C20 aryl or C1-C20 alkylC6-C20 aryl; R1 to R4 are each independently a C1-C20 alkyl group; R5 and R6 are each independently a C1-C20 alkyl group; X1 and X2 are each independently a halogen; R' and R'' are each independently hydrogen or C1-C20 alkyl; m is an integer from 3 to 5.

[0042] In the formulas 2-1 and 2-2 according to an embodiment, Ar1 and Ar2 are each independently C6-C12 aryl or C1-C20 alkyl C6-C12 aryl, R1 to R4 are each independently C1-C10 alkyl, R5 and R6 are each independently C1-C10 alkyl, and R' and R'' may each independently be hydrogen or C1-C10 alkyl, more preferably, Ar1 and Ar2 are each identical to each other and are C6-C12 aryl or C1-C20 alkyl C6-C12 aryl, R1 to R4 are each identical to each other and are C1-C10 alkyl, R5 and R6 are each identical to each other and are C1-C10 alkyl, and R' and R'' may each be the same to each other and are hydrogen or C1-C10 alkyl.

[0043] In one specific example, R1 to R4 may be, independently of each other, a branched C3-C10 alkyl, a branched C3-C7 alkyl, or a branched C3-C4 alkyl.

[0044] More preferably, the metal-ligand complex according to an embodiment may be represented by the following Formula 3-1 or 3-2.

[0045] [ka]

[0046] [ka]

[0047] (In the above chemical formulas 3-1 and 3-2, M is zirconium or hafnium; Ar is C6-C12 aryl or C1-C20 alkylC6-C12 aryl; R11 is C1-C5 alkyl; R12 is C1-C10 alkyl; X11 is fluoro or chloro; R''' is hydrogen or C1-C10 alkyl; n is an integer from 1 to 3.

[0048] In one embodiment, in formulas 3-1 and 3-2, Ar is C6-C12 aryl or C8-C20 alkyl C6-C12 aryl, R11 is C3-C5 alkyl, R12 is C1-C10 alkyl, X11 is fluoro or chloro, R''' is hydrogen or C1-C5 alkyl, and n may be an integer of 1 to 3.

[0049] In one embodiment, R11 may be a branched C3-C4 alkyl, specifically t-butyl.

[0050] In order to further improve high temperature stability, catalytic activity, and reactivity with olefins, the metal-ligand complex according to one embodiment may be preferably represented by the following Chemical Formula 4-1 or 4-2.

[0051] [ka]

[0052] [ka]

[0053] (In the above chemical formulas 4-1 and 4-2, M is zirconium or hafnium; R is hydrogen or C8-C20 alkyl; R12 is C1-C10 alkyl; X11 is fluoro or chloro; R''' is hydrogen or C1-C10 alkyl; n is an integer from 1 to 3.

[0054] In one embodiment, R may be hydrogen.

[0055] In one embodiment, R may be a linear or branched C8-C20 alkyl, specifically n-octyl, t-octyl, n-nonyl, t-nonyl, n-decyl, t-decyl, n-undecyl, t-undecyl, n-dodecyl, t-dodecyl, n-tridecyl, t-tridecyl, n-tetradecyl, t-tetradecyl, n-pentadecyl, or t-pentadecyl.

[0056] In one embodiment, R''' may be hydrogen or C1-C5 alkyl, specifically hydrogen or methyl.

[0057] Specifically, the metal-ligand complex according to one embodiment may be a compound selected from the following structures, but is not limited thereto:

[0058] [ka] JPEG2024547150000010.jpg227170JPEG2024547150000011.jpg214170JPEG2024547150000012.jpg217170JPEG2024547150000013.jpg216170JPEG2024547150000014.jpg209170JPEG2024547150000015.jpg209170JPEG2024547150000016.jpg206170JPEG2024547150000017.jpg223170 (In the above compounds, M is zirconium or hafnium.)

[0059] The present invention also provides a catalyst composition for the production of ethylene-based polymers selected from ethylene homopolymers and copolymers of ethylene and alpha-olefins, comprising a metal-ligand complex of the present invention and a cocatalyst.

[0060] The cocatalyst according to one embodiment may be a boron compound cocatalyst, an aluminum compound cocatalyst, and mixtures thereof.

[0061] According to an embodiment, the co-catalyst may be included in an amount of 0.5 to 10,000 moles per mole of the metal-ligand complex, but is not limited thereto.

[0062] The boron compound usable as the promoter may be any of the boron compounds disclosed in U.S. Pat. No. 5,198,401, and may be one or a mixture of two or more compounds selected from the compounds represented by the following chemical formulas A to C.

[0063] [ka]

[0064] [ka]

[0065] [ka] (In the above Chemical Formulae A to C, B is a boron atom, R21 is phenyl, the phenyl may be further substituted with 3 to 5 substituents selected from a fluorine atom, a C1-C20 alkyl, a C1-C20 alkyl substituted with a fluorine atom, a C1-C20 alkoxy, and a C1-C20 alkoxy substituted with a fluorine atom, R22 is a C5-C7 aromatic radical or a C1-C20 alkyl C6-C20 aryl radical, a C6-C20 aryl C1-C20 alkyl radical, for example, a triphenylmethylium radical, Z is a nitrogen or phosphorus atom, R23 is a C1-C20 alkyl radical or an anilinium radical substituted with two C1-C10 alkyls together with a nitrogen atom, and q is an integer of 2 or 3.

[0066] The boron-based cocatalyst may be, for example, one or more selected from tris(pentafluorophenyl)borane, tris(2,3,5,6-tetrafluorophenyl)borane, tris(2,3,4,5-tetrafluorophenyl)borane, tris(3,4,5-trifluorophenyl)borane, tris(2,3,4-trifluorophenyl)borane, phenylbis(pentafluorophenyl)borane, and the like.

[0067] The boron-based cocatalyst may be one or more boron compounds having a borate anion selected from tetrakis(pentafluorophenyl)borate, tetrakis(2,3,5,6-tetrafluorophenyl)borate, tetrakis(2,3,4,5-tetrafluorophenyl)borate, tetrakis(3,4,5-trifluorophenyl)borate, tetrakis(2,2,4-trifluorophenyl)borate, phenyltris(pentafluorophenyl)borate, and tetrakis(3,5-bistrifluoromethylphenyl)borate.

[0068] The boron-based cocatalyst may be one or more boron compounds having a cation selected from triphenylmethylium, triethylammonium, tripropylammonium, tri(n-butyl)ammonium, N,N-dimethylanilinium, N,N-diethylanilinium, N,N-2,4,6-pentamethylanilinium, diisopropylammonium, dicyclohexylammonium, triphenylphosphonium, tri(methylphenyl)phosphonium, and tri(dimethylphenyl)phosphonium.

[0069] Specifically, the boron-based cocatalyst may be one or more boron compounds having a cation selected from triphenylmethylium, triethylammonium, tripropylammonium, tri(n-butyl)ammonium, N,N-dimethylanilinium, N,N-diethylanilinium, N,N-2,4,6-pentamethylanilinium, diisopropylammonium, dicyclohexylammonium, triphenylphosphonium, tri(methylphenyl)phosphonium, and tri(dimethylphenyl)phosphonium, and a borate anion selected from tetrakis(pentafluorophenyl)borate, tetrakis(2,3,5,6-tetrafluorophenyl)borate, tetrakis(2,3,4,5-tetrafluorophenyl)borate, tetrakis(3,4,5-trifluorophenyl)borate, tetrakis(2,2,4-trifluorophenyl)borate, phenyltris(pentafluorophenyl)borate, and tetrakis(3,5-bistrifluoromethylphenyl)borate.

[0070] More specifically, the boron-based cocatalyst may be triphenylmethylium tetrakis(pentafluorophenyl)borate, triphenylmethylium tetrakis(3,5-bistrifluoromethylphenyl)borate, triethylammonium tetrakis(pentafluorophenyl)borate, tripropylammonium tetrakis(pentafluorophenyl)borate, tri(n-butyl)ammonium tetrakis(pentafluorophenyl)borate, tri(n-butyl)ammonium tetrakis(3,5-bistrifluoromethylphenyl)borate, N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, N,N-diethylanilinium tetrakis(pentafluorophenyl)borate, N,N-2,4,6-pentamethylanilinium tetrakis(pentafluorophenyl)borate, N,N-dimethyl ... The fluorine-containing compound may be one or more selected from the group consisting of anilinium tetrakis(3,5-bistrifluoromethylphenyl)borate, diisopropylammonium tetrakis(pentafluorophenyl)borate, dicyclohexylammonium tetrakis(pentafluorophenyl)borate, triphenylphosphonium tetrakis(pentafluorophenyl)borate, tri(methylphenyl)phosphonium tetrakis(pentafluorophenyl)borate, and tri(dimethylphenyl)phosphonium tetrakis(pentafluorophenyl)borate, and more preferably, may be one or more selected from the group consisting of triphenylmethylium tetrakis(pentafluorophenyl)borate, N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, and tris(pentafluorophenyl)borane.

[0071] Examples of aluminum compounds that can be used as cocatalysts in the catalyst composition according to one embodiment of the present invention include aluminoxane compounds of formula D or E, organoaluminum compounds of formula F, or organoaluminum alkyloxides or organoaluminum aryloxide compounds of formula G or H.

[0072] [ka]

[0073] [ka]

[0074] [ka]

[0075] [ka]

[0076] [ka] (In the above chemical formulas D to H, R31 is a C1-C20 alkyl, preferably methyl or isobutyl, r and s are each independently an integer of 5 to 20, R32 and R33 are each independently a C1-C20 alkyl, E is a hydrogen atom or a halogen atom, t is an integer of 1 to 3, and R34 is a C1-C20 alkyl or a C6-C30 aryl.

[0077] Specific examples of the aluminum compound that can be used include aluminoxane compounds such as methylaluminoxane, modified methylaluminoxane, and tetraisobutyldialuminoxane. Examples of the organoaluminum compounds include trialkylaluminums such as trimethylaluminum, triethylaluminum, tripropylaluminum, triisobutylaluminum, and trihexylaluminum, dialkylaluminum chlorides such as dimethylaluminum chloride, diethylaluminum chloride, dipropylaluminum chloride, diisobutylaluminum chloride, and dihexylaluminum chloride, methylaluminum dichloride, ethylaluminum dichloride, propylaluminum chloride, and the like. Examples of the cocatalyst include alkylaluminum dichlorides including dimethylaluminum hydride, isobutylaluminum dichloride, and hexylaluminum dichloride, dialkylaluminum hydrides including dimethylaluminum hydride, diethylaluminum hydride, dipropylaluminum hydride, diisobutylaluminum hydride, and dihexylaluminum hydride, and alkylalkoxyaluminums including methyldimethoxyaluminum, dimethylmethoxyaluminum, ethyldiethoxyaluminum, diethylethoxyaluminum, isobutyldibutoxyaluminum, diisobutylbutoxyaluminum, hexyldimethoxyaluminum, dihexylmethoxyaluminum, and dioctylmethoxyaluminum. Preferably, aluminoxane compounds, trialkylaluminums, and mixtures thereof may be used as the cocatalyst, and specifically, a single one or a mixture of methylaluminum, modified methylaluminum, tetraisobutyldialuminum, trimethylaluminum, triethylaluminum, and triisobutylaluminum may be used, and more preferably, tetraisobutyldialuminum, triisobutylaluminum, or a mixture thereof may be used.

[0078] Preferably, in the catalyst composition according to one embodiment of the present invention, when the aluminum compound is used as a co-catalyst, the ratio of the metal-ligand complex of the present invention to the co-catalyst may be in the range of 1:10 to 10,000 in terms of the molar ratio of transition metal (M):aluminum atom (Al) in the aluminum compound co-catalyst.

[0079] Preferably, in the catalyst composition according to one embodiment of the present invention, when the aluminum compound and the boron compound are used simultaneously as co-catalysts, the preferred ratio of the metal-ligand complex of the present invention to the co-catalyst may be, based on the molar ratio, a ratio of transition metal (M):boron atom (B):aluminum atom (Al) in the range of 1:0.1-200:10-10,000, more preferably 1:0.5-100:25-5,000.

[0080] When the ratio of the metal-ligand complex of the present invention to the cocatalyst is within the above range, it exhibits excellent catalytic activity for producing ethylene polymers, and the range of the ratio varies depending on the purity of the reaction.

[0081] In yet another aspect according to an embodiment of the present invention, the method for producing an ethylene-based polymer using the catalyst composition for producing an ethylene-based polymer may be carried out by contacting the metal-ligand complex, a cocatalyst, and ethylene or, if necessary, a comonomer in the presence of a suitable organic solvent. In this case, the precatalyst, which is the metal-ligand complex, and the cocatalyst component may be separately charged into a reactor, or each component may be premixed and charged into the reactor, and the mixing conditions such as the charging order, temperature, or concentration are not particularly limited.

[0082] Preferred organic solvents that can be used in the production method are C3-C20 hydrocarbons, and specific examples thereof include n-butane, isobutane, n-pentane, n-hexane, n-heptane, n-octane, isooctane, nonane, decane, dodecane, cyclohexane, methylcyclohexane, benzene, toluene, and xylene.

[0083] Specifically, when producing an ethylene homopolymer, ethylene is used alone as a monomer, and when producing a copolymer of ethylene and an alpha-olefin, a C3-C18 α-olefin may be used as a comonomer together with ethylene. Specific examples of the C3-C18 α-olefin include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-hexadecene, and 1-octadecene. In the present invention, the C3-C18 α-olefin may be homopolymerized with ethylene, or two or more kinds of olefins may be copolymerized with ethylene, and more preferably, 1-butene, 1-hexene, 1-octene, or 1-decene may be copolymerized with ethylene.

[0084] The pressure of ethylene may be 1 to 1000 atm, and more preferably 5 to 100 atm. The polymerization reaction is effectively carried out at a temperature of 80° C. or higher, preferably 100° C. or higher, and more preferably 160° C. to 250° C. The temperature and pressure conditions of the polymerization step may be determined in consideration of the efficiency of the polymerization reaction depending on the type of reaction to be applied and the type of reactor.

[0085] Generally, when a solution polymerization process is carried out at such high temperatures, the catalyst is deformed or deteriorated with an increase in temperature, resulting in a decrease in catalyst activity, making it difficult to obtain a polymer having desired physical properties. However, when an ethylene-based polymer is produced using the catalyst composition according to the present invention, the catalyst composition exhibits stable catalytic activity even at high polymerization temperatures.

[0086] The ethylene-based polymer is an ethylene homopolymer or a copolymer of ethylene and an alpha-olefin, and the copolymer of ethylene and an alpha-olefin contains 50% by weight or more of ethylene, preferably 60% by weight or more of ethylene, and more preferably 60 to 99% by weight of ethylene.

[0087] As described above, linear low density polyethylene (LLDPE) produced using C4-C10 alpha olefin as a comonomer has a density range of 0.940 g / cc or less, and can be extended to a very low density polyethylene (VLDPE or ULDPE) or olefin elastomer range of 0.900 g / cc or less. In addition, hydrogen can be used as a molecular weight regulator to regulate the molecular weight during the production of the ethylene copolymer according to the present invention, and the copolymer usually has a weight average molecular weight (Mw) in the range of 80,000 to 500,000.

[0088] The catalyst composition proposed in the present invention is present in a homogeneous form in the polymerization reactor, and is therefore preferably applied to a solution polymerization process carried out at a temperature equal to or higher than the melting point of the polymer, but may also be used in a slurry or gas phase polymerization process in the form of a heterogeneous catalyst composition obtained by supporting the precatalyst and cocatalyst, which are the metal-ligand complexes, on a porous metal oxide support, as disclosed in U.S. Patent No. 4,752,597.

[0089] The present invention will be described in detail below with reference to examples. However, the scope of the present invention is not limited to the following examples.

[0090] Unless otherwise noted, all ligand and catalyst synthesis experiments were carried out under nitrogen atmosphere using standard Schlenk or glove box techniques, and organic solvents used in reactions were refluxed under sodium metal and benzophenone to remove moisture and distilled immediately before use. 1H-NMR analysis of the synthesized ligands and catalysts was carried out at room temperature using a Bruker 400 or 500 MHz.

[0091] The polymerization solvents, methylcyclohexane and n-heptane, were passed through a tube filled with 5 Å molecular sieves and activated alumina, and were bubbled with high-purity nitrogen to thoroughly remove moisture, oxygen, and other catalyst poisons before use.

[0092] [Comparative Example 1] Synthesis of Precatalyst C1 [ka]

[0093] Precatalyst C1 was prepared using 4-tert-octylphenol and 3,6-di-tert-butyl-9H-carbazole according to KR10-2018-0048728A and KR10-2019-0075778A.

[0094] [Example 1] Synthesis of pre-catalyst C2 [ka]

[0095] The reaction was carried out in a glove box under a nitrogen atmosphere. Precatalyst C1 (1.17 g, 0.87 mmol) and toluene (40 mL) were placed in a 100 mL flask, to which 3-pentadecylphenol (0.53 g, 1.74 mmol) was added, and the mixture was stirred at room temperature for 2 hours, after which the solvent was removed. This was dissolved in 50 mL of normal hexane, and then filtered through a filter filled with dried celite to remove the solids. The filtered solution was dried in a vacuum to obtain precatalyst C2 (1.52 g, 91%) as a white solid.

[0096] 1H NMR (CDCl3): δ 8.40 (s, 2H), 8.28 (s, 2H), 7.53-7.00 (m, 14H), 6.72 (m, 2H), 6.64 (m, 2H), 6.36 (m, 2H), 5.89 (m, 2H), 5.60 (s, 2H), 4.99 (m, 2H), 4.70 (m, 2H), 4.12 (m, 2H), 3.65 (m, 2H), 2.32(m, 4H), 1.73 (s, 4H) 1.59-0.81 (124H).

[0097] [Example 2] Synthesis of pre-catalyst C3 [ka]

[0098] A pre-catalyst A was prepared in the same manner as in Comparative Example 1, except that 4-methylphenol was used instead of 4-tert-octylphenol.

[0099] 1H NMR (CDCl3): δ 8.30 (s, 2H), 8.07 (s, 2H), 7.47-7.00 (m, 16H), 6.27 (m, 2H), 4.60 (m, 2H), 3.80 (m, 2H), 3.40 (m, 2H), 2.34 (s, 6H), 1.54 (s, 18H), 1.38 (s, 18H), -1.50 (s, 6H).

[0100] Pre-catalyst C3 was prepared in the same manner as in Example 1, except that pre-catalyst A was used instead of pre-catalyst C1 (white solid, 1.36 g, 90%).

[0101] 1H NMR (CDCl3): δ 8.36 (s, 2H), 8.25 (s, 2H), 7.44-7.00 (m, 14H), 6.72 (m, 2H), 6.60 (m, 2H), 6.33 (m, 2H), 5.85 (m, 2H), 5.58 (s, 2H), 4.94 (m, 2H), 4.67 (m, 2H), 4.15 (m, 2H), 3.69 (m, 2H), 2.32 (s, 6H), 2.30(m, 4H), 1.56-1.26 (m, 52H), 1.51 (s, 18H), 1.40 (s, 18H), 0.90 (m, 6H).

[0102] [Example 3] Synthesis of pre-catalyst C4 [ka]

[0103] A pre-catalyst B was prepared in the same manner as in Comparative Example 1, except that 4-methylphenol was used instead of 4-tert-octylphenol and 2,7-di-tert-butyl-9H-carbazole was used instead of 3,6-di-tert-butyl-9H-carbazole.

[0104] Precatalyst C4 was prepared in the same manner as in Example 1, except that precatalyst B was used instead of precatalyst C1 (white solid, 0.58 g, 70%).

[0105] 1H NMR (CDCl3): δ 8.31 (d, 2H), 8.25 (s, 2H), 7.44-7.00 (m, 8H), 6.98-6.96 (m, 2H), 6.92-6.91 (m, 2H), 6.75 (m, 4H), 6.51 (m, 2H), 5.84 (m, 2H), 5.38 (m, 2H), 5.23 (m, 2H), 4.84 (m, 2H), 4.24-4.22 (m, 2H), 3.81-3.80 (m, 2H), 2.32 (s, 6H), 1.94-1.93(m, 2H), 1.51 (m, 92H), 1.08 (m, 6H).

[0106] [Example 4] Copolymerization of ethylene and 1-octene to measure the oxygen sensitivity of the prepared transition metal compounds 10 μmol of the precatalyst C2 prepared in Example 1 was exposed to the atmosphere at 22.1° C. and humidity 31% for about 1 hour, and then dissolved in 10 ml of toluene to prepare a saturated solution. Then, ethylene and 1-octene were copolymerized using a batch polymerization apparatus as follows.

[0107] After thorough drying, 600 mL of methylcyclohexane and 50 mL of 1-octene were placed in a 1500 mL stainless steel reactor purged with nitrogen, and then 2 mL of a 1.0 M hexane solution of triisobutylaluminum was added to the reactor. Next, the temperature of the reactor was heated to 100°C, and 1 mL of a saturated solution of pre-catalyst C2 (i.e., a saturated solution containing 1.0 μmol of pre-catalyst C2 in 1 mL of toluene) and 40 μmol of triphenylmethylium tetrakis(pentafluorophenyl)borate were sequentially added, and the pressure in the reactor was filled to 20 bar with ethylene, and then the two were continuously fed to polymerize. After the reaction was carried out for 5 minutes, the collected reaction product was dried in a vacuum oven at 40°C for 8 hours. The polymerization results are shown in Table 1 below.

[0108] [Example 5] Except for using precatalyst C2 (Example 1) not exposed to the atmosphere, copolymerization of ethylene and 1-octene was carried out in the same manner as in Example 4. The polymerization reaction conditions and polymerization results are shown in Table 1 below.

[0109] [Comparative Example 2] Except for using Precatalyst C1 (Comparative Example 1) instead of Precatalyst C2 (Example 1), copolymerization of ethylene and 1-octene was carried out in the same manner as in Example 4. The polymerization reaction conditions and polymerization results are shown in Table 1 below.

[0110] [Comparative Example 3] Copolymerization of ethylene and 1-octene was carried out in the same manner as in Example 4, except that precatalyst C1 (Comparative Example 1) not exposed to the atmosphere was used instead of precatalyst C2 (Example 1). The polymerization reaction conditions and polymerization results are shown in Table 1 below.

[0111] [Table 1]

[0112] The results of observing the temperature change (ΔT) of precatalyst C2 of Example 1 and precatalyst C1 of Comparative Example 1, which are used as catalysts in the polymerization of ethylene and 1-octene, depending on whether they are exposed to the atmosphere, are shown in Table 1. From this, it can be seen that precatalyst C2 of Example 1 exhibits a certain temperature change during polymerization regardless of whether it is exposed to the atmosphere, whereas precatalyst C1 of Comparative Example 1 exhibits a significantly reduced temperature change as it is exposed to the atmosphere.

[0113] Specifically, from the polymerization results in Table 1, precatalyst C2 (Example 1) of the present invention has a structure in which a phenoxy-based leaving group substituted with an alkyl such as pentadecyl has been introduced, unlike precatalyst C1 (Comparative Example 1) in which an alkyl-based leaving group such as methyl has been introduced. Therefore, it is relatively insensitive to impurities such as oxygen and moisture in the atmosphere, and is relatively less susceptible to the resulting decrease in activity, i.e., is less affected by impurities that may appear during the reaction, and has excellent catalyst stability, which may be advantageous when applied to commercial plants.

[0114] As described above, it can be confirmed that the resistance to impurities such as oxygen and moisture, and the catalyst stability and activity change significantly depending on the structure of the polymerization catalyst.

[0115] [Examples 6-8, Comparative Example 4] Copolymerization of ethylene and 1-octene at high temperatures by a continuous solution polymerization process Copolymerization of ethylene and 1-octene was carried out in a temperature-controlled continuous polymerization reactor equipped with a mechanical stirrer.

[0116] The catalysts used were precatalysts C2, C3, C4 and C1 prepared in Examples 1, 2, 3 and Comparative Example 1, the solvent was n-heptane, and the cocatalyst was modified methylaluminoxane (20 wt%, Nouryon). The amounts of catalysts used were as shown in Table 2 below. Each catalyst was dissolved in toluene at a concentration of 0.2 g / L and injected, and polymerization was carried out using 1-octene as a comonomer. The conversion rate of the reactor could be estimated from the reaction conditions when polymerizing one polymer under each reaction condition and the temperature gradient in the reactor. In the case of a single active site catalyst, the molecular weight was controlled as a function of the reactor temperature and 1-octene content, and the conditions and results are shown in Table 2 below.

[0117] Melt index (MI): Measured according to ASTM D1238 analysis at 190° C. under a load of 2.16 kg.

[0118] Density: Measured by ASTM D792 analytical method.

[0119] [Table 2]

[0120] From the polymerization results in Table 2, it can be seen that in Examples 6, 7 and 8, in which precatalyst C2 (Example 1), precatalyst C3 (Example 2) and precatalyst C4 (Example 3) of the present invention are used as polymerization catalysts, excellent activity is maintained despite the reduced catalyst usage amount at a high temperature of 220°C, as compared to Comparative Example 4, in which the known precatalyst C1 (Comparative Example 1) is used, and the catalytic activity is significantly improved over that of the existing catalysts.

[0121] Therefore, it can be seen that the metal-ligand complex according to the present invention has surprisingly excellent catalytic activity and stability even at high temperatures due to the structural characteristics of the specific functional groups introduced therein, and can effectively produce high molecular weight ethylene and alpha-olefin copolymers.

Claims

1. A metal-ligand complex represented by the following chemical formula 1. 【Chemistry 1】 (In the above Chemical Formula 1, M is a transition metal of Group 4 of the periodic table; Ar1 and Ar2 are each independently a C6-C20 aryl, and the aryl of Ar1 and Ar2 may be further substituted with a C1-C20 alkyl; R1 to R4 are each independently C1-C20 alkyl, C6-C20 aryl, or C6-C20 arylC1-C20 alkyl; R5 and R6 are each independently a C1-C20 alkyl group; R7 and R8 are each independently halogen or C1-C20 alkyl; a, b, c, d, e and f are each independently an integer from 0 to 4; m is an integer from 2 to 5.

2. Ar1 and Ar2 are each independently C6-C20 aryl or C1-C20 alkyl C6-C20 aryl; R1 to R4 are each independently a C1-C20 alkyl group; R7 and R8 are each independently halogen or C1-C20 alkyl; a, b, c, d, e and f are each independently an integer from 1 to 3; 2. The metal-ligand complex of claim 1, wherein m is an integer from 3 to 5.

3. The metal-ligand complex according to claim 1, which is represented by the following chemical formula 2-1 or 2-2. 【Chemistry 2】 (In the above chemical formulas 2-1 and 2-2, M is titanium, zirconium or hafnium; Ar1 and Ar2 are each independently C6-C20 aryl or C1-C20 alkylC6-C20 aryl; R1 to R4 are each independently a C1-C20 alkyl group; R5 and R6 are each independently a C1-C20 alkyl group; X1 and X2 are each independently a halogen; R' and R'' are each independently hydrogen or C1-C20 alkyl; m is an integer from 3 to 5.

4. wherein Ar1 and Ar2 are each independently C6-C12 aryl or C1-C20 alkyl C6-C12 aryl; R1 to R4 are each independently a C1-C10 alkyl group; R5 and R6 are each independently a C1-C10 alkyl; 4. The metal-ligand complex of claim 3, wherein R' and R'' are each independently hydrogen or C1-C10 alkyl.

5. The metal-ligand complex according to claim 1, which is represented by the following chemical formula 3-1 or 3-2. 【Chemistry 3】 (In the above chemical formulas 3-1 and 3-2, M is zirconium or hafnium; Ar is C6-C12 aryl or C1-C20 alkyl C6-C12 aryl; R11 is C1-C5 alkyl; R12 is C1-C10 alkyl; X11 is fluoro or chloro; R''' is hydrogen or C1-C10 alkyl; n is an integer from 1 to 3.

6. The metal-ligand complex according to claim 5, which is represented by the following chemical formula 4-1 or 4-2. 【Chemistry 4】 (In the above chemical formulas 4-1 and 4-2, M is zirconium or hafnium; R is hydrogen or C8-C20 alkyl; R12 is C1-C10 alkyl; X11 is fluoro or chloro; R''' is hydrogen or C1-C10 alkyl; n is an integer from 1 to 3.

7. A metal-ligand complex according to any one of claims 1 to 6, A catalyst composition for producing an ethylene-based polymer, comprising:

8. 8. The catalyst composition for producing an ethylene-based polymer according to claim 7, wherein the cocatalyst is an aluminum compound cocatalyst, a boron compound cocatalyst, or a mixture thereof.

9. The catalyst composition for producing an ethylene polymer according to claim 7, wherein the cocatalyst is used in an amount of 0.5 to 10,000 moles per mole of the metal-ligand complex.

10. A method for producing an ethylene-based polymer, comprising the step of polymerizing ethylene or ethylene and an α-olefin in the presence of the catalyst composition for producing an ethylene-based polymer according to claim 7 to produce an ethylene-based polymer.

11. The method for producing an ethylene-based polymer according to claim 10, wherein the polymerization is carried out at 100 to 250° C.

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