KR102888777B1 - Metal-ligand complexes having electron withdrawing group, catalyst composition for ethylene-based polymerization containing the same, and production methods of ethylene-based polymers using the same - Google Patents

Abstract

The present invention relates to a metal-ligand complex having both a strong electron-donating group and an electron-withdrawing group, a catalyst composition for ethylene polymerization comprising the same, and a method for producing an ethylene polymer using the same.

Description

Metal-ligand complexes having electron withdrawing groups, catalyst composition for ethylene-based polymerization containing the same, and production methods of ethylene-based polymers using the same

The present invention relates to a metal-ligand complex having a specific electron-withdrawing group, a catalyst composition for producing an ethylene polymer comprising the same, and a method for producing an ethylene polymer using the same.

In the past, a so-called Ziegler-Natta catalyst system consisting of a main catalyst component of a titanium or vanadium compound and a cocatalyst component of an alkyl aluminum compound has been generally used to produce a copolymer of ethylene and an α-olefin or a copolymer of ethylene and an olefin-diene.

U.S. Patent Nos. 3,594,330 and 3,676,415 disclose improved Ziegler-Natta catalysts. Although Ziegler-Natta catalyst systems exhibit high activity for ethylene polymerization, they generally have a wide molecular weight distribution due to non-uniform catalytic activity sites, and especially in copolymers of ethylene and α-olefins, they have the disadvantage of non-uniform composition distribution.

Since then, various studies have been conducted on a metallocene catalyst system composed of a metallocene compound of a transition metal in Group 4 of the periodic table, such as zirconium or hafnium, and methylaluminoxane as a cocatalyst, which can produce polyethylene with a narrow molecular weight distribution and a uniform composition distribution compared to the existing Ziegler-Natta catalyst system, as a homogeneous catalyst with a single type of catalytic activity site.

For example, European Patent Publication Nos. 320,762, 372,632, Japanese Patent Application Laid-Open Nos. Sho 63-092621, Hei 02-84405, and Hei 03-2347 disclose that by activating metallocene compounds in Cp ₂ TiCl ₂ , Cp ₂ ZrCl ₂ , Cp ₂ ZrMeCl, Cp ₂ ZrMe ₂ , ethylene(IndH ₄ ) ₂ ZrCl ₂ , etc. with a cocatalyst methylaluminoxane, ethylene can be polymerized with high activity to produce polyethylene having a molecular weight distribution (Mw/Mn) in the range of 1.5 to 2.0.

Low-density and low-molecular-weight ethylene polymers obtained by polymerizing ethylene or ethylene with alpha-olefins can be applied to the development of high-value-added products such as synthetic oils, lubricants, and adhesives. However, it is difficult to obtain low-density and low-molecular-weight ethylene polymers when applying the above-mentioned catalyst system. That is, most of these low-density and low-molecular-weight ethylene polymers are produced at temperatures below 100°C, and their activity decreases rapidly as the temperature increases. In addition, although hydrogen can be used as a molecular weight regulator to produce low-molecular-weight ethylene polymers, the catalytic activity decreases rapidly as the amount of hydrogen used increases, making it difficult to achieve high-temperature application and high activity for producing low-molecular-weight ethylene polymers.

Therefore, the chemical industry still needs catalysts and catalyst precursors with improved properties.

U.S. Patent No. 3,594,330 U.S. Patent No. 3,676,415 European Patent Publication No. 320,762 European Patent Publication No. 372,632 Japanese Patent Application Laid-Open No. 63-092621 Japanese Patent Application Laid-Open No. 02-84405 Japanese Patent Application Publication No. 03-2347

Accordingly, the present invention aims to improve the above-mentioned problems by providing a metal-ligand complex having a specific electron donor group and a catalyst composition for producing an ethylene polymer comprising the same.

The present invention also provides a method for producing a low-density and low-molecular-weight ethylene polymer using the catalyst composition for producing an ethylene polymer of the present invention.

The present invention provides a metal-ligand complex having significantly improved high-temperature activity due to increased stability at high temperatures, and the metal-ligand complex of the present invention is represented by the following chemical formula 1.

[Chemical Formula 1]

(In the above chemical formula 1,

M is a transition metal in group 4 of the periodic table;

R' and R'' are independently C ₁ -C ₂₀ alkyl, C ₆ -C ₂₀ aryloxy or C ₁ -C ₂₀ alkylC ₆ -C ₂₀ aryloxy;

R ₁ and R ₂ are independently hydrogen or -C _n F _2n+1 ;

R ₃ to R ₆ are each independently C ₁ -C ₂₀ alkyl, C ₆ -C ₂₀ aryl or C ₆ -C ₂₀ arylC ₁ -C ₂₀ alkyl;

R ₇ and R ₈ are independently C ₁ -C ₂₀ alkyl or C ₁ -C ₂₀ alkoxy;

R ₉ and R ₁₀ are independently hydrogen or C ₁ -C ₂₀ alkyl;

a, b and n are independently integers from 1 to 3;

m is an integer from 2 to 5.)

The present invention also provides a catalyst composition for producing an ethylene polymer comprising the metal-ligand complex and a cocatalyst of the present invention.

The present invention also provides a method for producing an ethylene polymer, comprising the step of producing an ethylene polymer by polymerizing ethylene or ethylene and alpha-olefin in the presence of a catalyst composition for producing an ethylene polymer of the present invention.

The metal-ligand complex according to the present invention has a structure of a phenyl group substituted with a carbazole group, which is a strong electron-donating group, and an electron-accepting group due to the introduction of a phenyl group substituted with a perfluoroalkyl group, preferably a trifluoromethyl group, as a highly controlled bulky electron-withdrawing group. Due to this structural feature, the electrons of the ligands within the complex are enriched, and the stability of the complex is dramatically improved, thereby promoting polymerization at high polymerization temperatures without a decrease in catalytic activity.

In addition, the metal-ligand complex according to the present invention has an advantage in that it can be easily polymerized due to its high reactivity with olefins, and can produce low-density and low-molecular-weight ethylene polymers at high polymerization temperatures. In particular, when a catalyst composition comprising the metal-ligand complex according to the present invention is used in the production of ethylene polymers, i.e., ethylene homopolymers or copolymers of ethylene and alpha-olefins, low-density and low-molecular-weight ethylene homopolymers or copolymers of ethylene and alpha-olefins can be efficiently produced with excellent catalytic activity at high polymerization temperatures of 100°C or higher.

This is due to the structural characteristics of the metal-ligand complex according to the present invention, and the metal-ligand complex according to the present invention has excellent thermal stability of the catalyst, maintains high catalytic activity even at high temperatures, has good copolymerization reactivity with olefins, and can produce low-density and low-molecular-weight ethylene polymers in high yields. Therefore, compared to already known metallocene and non-metallocene single-site catalysts, it can be said to have high commercial practicality, such as application to the development of numerous high-value-added products, such as synthetic oils, lubricants, and adhesives.

Therefore, the metal-ligand complex and the catalyst composition comprising the same according to one embodiment of the present invention can be very usefully used in the production of an ethylene polymer having excellent physical properties.

Hereinafter, the metal-ligand complex of the present invention, the catalyst composition for producing an ethylene polymer comprising the same, and the method for producing an ethylene polymer using the same will be described in detail. However, unless otherwise defined, the technical and scientific terms used herein have meanings commonly understood by those of ordinary skill in the art to which this invention pertains, and in the following description, descriptions of known functions and configurations that may unnecessarily obscure the gist of the present invention are omitted.

The following terms used in this specification are defined as follows, but are for illustrative purposes only and are not intended to limit the invention, application, or use.

The terms “substituent,” “radical,” “group,” “group,” “moiety,” and “fragment” in this specification are used interchangeably.

The term "C _A -C _B " in this specification means "having carbon number greater than or equal to A and less than or equal to B."

The term "alkyl" as used herein refers to a straight-chain or branched saturated hydrocarbon monovalent radical composed solely of carbon and hydrogen atoms. The alkyl may have, but is not limited to, 1 to 20 carbon atoms, 1 to 10 carbon atoms, 1 to 5 carbon atoms, 5 to 20 carbon atoms, 8 to 20 carbon atoms, or 8 to 15 carbon atoms. Specific examples of the above 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.

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

The term "alkoxy" as used herein refers to an -O-alkyl radical, where 'alkyl' is as defined above. Specific examples of the alkoxy include, but are not limited to, methoxy, ethoxy, isopropoxy, butoxy, isobutoxy, t-butoxy, and the like.

The term "aryloxy" as used herein refers to an -O-aryl radical, where 'aryl' is as defined above. Specific examples of the aryloxy include, but are not limited to, phenoxy, naphthoxy, and the like.

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

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

The present invention relates to a metal-ligand complex in which a perfluoroalkyl group is substituted with an electron-withdrawing group of a highly controlled bulky form, and the present invention provides a metal-ligand complex represented by the following chemical formula 1, which comprises a ligand in which a carbazole group, a strong electron-donating group, and a perfluoroalkyl group, an electron-withdrawing group, are introduced at specific positions:

[Chemical Formula 1]

(In the above chemical formula 1,

M is a transition metal in group 4 of the periodic table;

R' and R'' are independently C ₁ -C ₂₀ alkyl, C ₆ -C ₂₀ aryloxy or C ₁ -C ₂₀ alkylC ₆ -C ₂₀ aryloxy;

R ₁ and R ₂ are independently hydrogen or -C _n F _2n+1 ;

R ₃ to R ₆ are each independently C ₁ -C ₂₀ alkyl, C ₆ -C ₂₀ aryl or C ₆ -C ₂₀ arylC ₁ -C ₂₀ alkyl;

R ₇ and R ₈ are independently C ₁ -C ₂₀ alkyl or C ₁ -C ₂₀ alkoxy;

R ₉ and R ₁₀ are independently hydrogen or C ₁ -C ₂₀ alkyl;

a, b and n are independently integers from 1 to 3;

m is an integer from 2 to 5.)

According to one embodiment, a metal-ligand complex can significantly improve the stability of the complex by introducing a phenyl group substituted with a perfluoroalkyl group as a bulky electron-withdrawing group, thereby forming an electron donor-acceptor structure with a phenyl group substituted with a carbazole group as an electron-donating group, thereby enriching the electrons of the ligand.

Due to the structural features described above, the metal-ligand complex has excellent thermal stability, maintains high catalytic activity even at high temperatures, has good polymerization reactivity with other olefins, and can produce low-density and low-molecular-weight ethylene polymers in high yields, and thus has high commercial practicality in the development of numerous high-value-added products such as synthetic oils, lubricants, and adhesives compared to already known metallocene and non-metallocene single-site catalysts.

Preferably, in the chemical formula 1 according to one embodiment of the present invention, a and b may be integers of 1.

Preferably, in the chemical formula 1 according to one embodiment of the present invention, R' and R'' are each independently C ₁ -C ₂₀ alkyl or C ₁ -C ₂₀ alkylC ₆ -C ₂₀ aryloxy; R ₁ and R ₂ are each independently hydrogen or -CF ₃ ; R ₃ to R ₆ are each independently C ₁ -C ₂₀ alkyl; R ₇ and R ₈ are each independently C ₁ -C ₂₀ alkyl or C ₁ -C ₂₀ alkoxy; R ₉ and R ₁₀ are each independently hydrogen or C ₁ -C ₂₀ alkyl; and m may be an integer of 3 to 5.

In terms of improving thermal stability and catalytic activity, the metal-ligand complex of chemical formula 1 according to one embodiment of the present invention may be preferably represented by the following chemical formula 2.

[Chemical Formula 2]

(In the above chemical formula 2,

M is titanium, zirconium or hafnium;

R' and R'' are independently C ₁ -C ₂₀ alkyl or C ₁ -C ₂₀ alkylC ₆ -C ₂₀ aryloxy;

R ₁ and R ₂ are independently hydrogen or -CF ₃ ;

R ₃ to R ₆ are each independently C ₁ -C ₂₀ alkyl;

R ₇ and R ₈ are independently C ₁ -C ₂₀ alkyl or C ₁ -C ₂₀ alkoxy;

R ₉ and R ₁₀ are independently hydrogen or C ₁ -C ₂₀ alkyl;

m is an integer between 3 and 5.)

In the chemical formula 2 according to one embodiment of the present invention, R' and R'' are each independently C ₁ -C ₂₀ alkyl; R ₁ and R ₂ are each independently hydrogen or -CF ₃ ; R ₃ to R ₆ are each independently C ₁ -C ₂₀ alkyl; R ₇ and R ₈ are each independently C ₁ -C ₂₀ alkyl; and R ₉ and R ₁₀ may each independently be hydrogen or C ₁ -C ₂₀ alkyl.

Preferably, in the chemical formula 2 according to one embodiment of the present invention, R' and R'' are the same as each other and are C ₁ -C ₅ alkyl; R ₁ and R ₂ are the same as each other and are hydrogen or -CF ₃ ; R ₃ to R ₆ are the same as each other and are C ₁ -C ₅ alkyl; R ₇ and R ₈ are each independently C ₈ -C ₂₀ alkyl, and R ₉ and R ₁₀ can each independently be hydrogen or C ₁ -C ₅ alkyl.

More preferably, in the chemical formula 2 according to one embodiment of the present invention, R' and R'' are the same as each other and are methyl or ethyl; R ₁ and R ₂ are the same as each other and are hydrogen or -CF ₃ ; R ₃ to R ₆ are the same as each other and may be a C ₃ -C ₄ alkyl of a branched group, specifically, t-butyl; R ₇ and R ₈ are each independently C ₈ -C ₂₀ alkyl; R ₉ and R ₁₀ are the same as each other and are hydrogen or methyl; and m may be an integer of 3 or 5.

In order to further improve catalytic activity and reactivity with olefins, the metal-ligand complex of chemical formula 1 according to one embodiment of the present invention may be represented by the following chemical formula 3.

[Chemical Formula 3]

(In the above chemical formula 3,

M is zirconium or hafnium;

R ₁₁ is hydrogen or -CF ₃ ;

R ₁₂ is C ₈ -C ₂₀ alkyl;

R ₁₃ is hydrogen or methyl;

p is an integer of 1 or 2.)

Preferably, in chemical formula 3 according to one embodiment of the present invention, R ₁₂ may be a straight-chain or branched C ₈ -C ₁₂ alkyl, specifically, R ₁₂ may be n-octyl, t-octyl, n-nonyl, t-nonyl, n-decyl, t-decyl, n-undecyl, t-undecyl, n-dodecyl or t-dodecyl; and p may be an integer of 1 or 2.

In chemical formula 3 according to one embodiment of the present invention, R ₁₁ is hydrogen; R ₁₂ may be n-octyl, t-octyl, n-decyl or n-dodecyl; R ₁₃ is hydrogen; and p may be an integer of 1.

In chemical formula 3 according to one embodiment of the present invention, R ₁₁ is -CF ₃ ; R ₁₂ may be n-octyl, t-octyl, n-decyl or n-dodecyl; R ₁₃ is hydrogen; and p may be an integer of 1.

In chemical formula 3 according to one embodiment of the present invention, R ₁₁ is hydrogen; R ₁₂ may be n-octyl, t-octyl, n-decyl or n-dodecyl; R ₁₃ is hydrogen; and p may be an integer of 2.

In chemical formula 3 according to one embodiment of the present invention, R ₁₁ is -CF ₃ ; R ₁₂ may be n-octyl, t-octyl, n-decyl or n-dodecyl; R ₁₃ is hydrogen; and p may be an integer of 2.

In chemical formula 3 according to one embodiment of the present invention, R ₁₁ is hydrogen; R ₁₂ may be n-octyl, t-octyl, n-decyl or n-dodecyl; R ₁₃ is methyl; and p may be an integer of 1.

In chemical formula 3 according to one embodiment of the present invention, R ₁₁ is -CF ₃ ; R ₁₂ may be n-octyl, t-octyl, n-decyl or n-dodecyl; R ₁₃ is methyl; and p may be an integer of 1.

In chemical formula 3 according to one embodiment of the present invention, R ₁₁ is hydrogen; R ₁₂ may be n-octyl, t-octyl, n-decyl or n-dodecyl; R ₁₃ may be methyl; and p may be an integer of 2.

In chemical formula 3 according to one embodiment of the present invention, R ₁₁ is -CF ₃ ; R ₁₂ may be n-octyl, t-octyl, n-decyl or n-dodecyl; R ₁₃ may be methyl; and p may be an integer of 2.

Specifically, the metal-ligand complex according to one embodiment of the present invention may be a compound selected from the following structures, but is not limited thereto.

(In the above compound, M is zirconium or hafnium.)

The present invention also provides a catalyst composition for producing an ethylene polymer selected from an ethylene homopolymer and a copolymer of ethylene and an alpha-olefin, comprising the metal-ligand complex and a cocatalyst of the present invention.

According to one embodiment, the cocatalyst may be a boron compound cocatalyst, an aluminum compound cocatalyst, or a mixture thereof.

According to one embodiment, the cocatalyst 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.

The boron compound that can be used as the above cocatalyst may be a boron compound known from U.S. Patent No. 5,198,401, and specifically may be one or a mixture of two or more compounds selected from compounds represented by the following chemical formulas A to C.

[Chemical Formula A]

B(R ²¹ ) ₃

[Chemical Formula B]

[R ²² ] ⁺ [B(R ²¹ ) ₄ ] ^-

[Chemical Formula C]

[(R ²³ ) _q ZH] ⁺ [B(R ²¹ ) ₄ ] ^-

(In the above chemical formulas A to C,

B is a boron atom; R ²¹ is phenyl, which may be further substituted with 3 to 5 substituents selected from fluorine, C _{1 -C 20} alkyl, C ₁ -C ₂₀ alkyl substituted with a fluorine atom, C ₁ -C ₂₀ alkoxy and C 1 -C ₂₀ alkoxy substituted with a fluorine atom; R ²² is a C ₅ -C ₇ aromatic radical or a C ₁ -C ₂₀ alkylC ₆ -C ₂₀ aryl radical, a C ₆ -C ₂₀ arylC ₁ -C ₂₀ alkyl radical, for example, a triphenylmethylium radical; Z is a nitrogen or phosphorus atom; R ²³ is a C ₁ -C ₂₀ alkyl radical or anilinium radical substituted with two C ₁ -C ₁₀ alkyls together with a nitrogen atom; q is an integer of 2 or 3.)

Preferred examples of the above boron-based cocatalyst include triphenylmethylinium tetrakis(pentafluorophenyl)borate, 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, 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, phenylbis(pentafluorophenyl)borate or tetrakis(3,5-bistrifluoromethylphenyl)borate. There are. Also, specific examples of their combinations include ferrocenium tetrakis(pentafluorophenyl)borate, 1,1'-dimethylferrocenium tetrakis(pentafluorophenyl)borate, silver tetrakis(pentafluorophenyl)borate, triphenylmethyllinium tetrakis(pentafluorophenyl)borate, triphenylmethyllinium 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-dimethylanilinium tetrakis(3,5-bistrifluoromethylphenyl)borate, diisopropylammonium tetrakis(pentafluorophenyl)borate, dicyclohexylammonium tetrakis(pentafluorophenyl)borate, triphenylphosphonium tetrakis(pentafluorophenyl)borate, tri(methylphenyl)phosphonium tetrakis(pentafluorophenyl)borate, or tri(dimethylphenyl)phosphonium tetrakis(pentafluorophenyl)borate, and the most preferred of these may be any one or two or more selected from triphenylmethyllinium tetrakis(pentafluorophenyl)borate, N,N-dimethylanilinium tetrakispentafluorophenylborate, triphenylmethyllinium tetrakispentafluorophenylborate, and trispentafluoroborane. there is.

Examples of aluminum compounds that can be used as a cocatalyst in a catalyst composition according to one embodiment of the present invention include an aluminoxane compound of chemical formula D or E, an organoaluminum compound of chemical formula F, or an organoaluminum alkyloxide or organoaluminum aryloxide compound of chemical formula G or H.

[Chemical Formula D]

(-Al(R ³¹ )-O-) _r

[Chemical Formula E]

(R ³¹ ) ₂ Al-(-O(R ³¹ )-) _s -(R ³¹ ) ₂

[Chemical formula F]

(R ³² ) _t Al(E) _3-t

[Chemical formula G]

(R ³³ ) ₂ AlOR ³⁴

[Chemical formula H]

R ³³ Al(OR ³⁴ ) ₂

(In the above chemical formulas D to H,

R ³¹ is C ₁ -C ₂₀ alkyl, preferably methyl or isobutyl, r and s are each independently an integer of 5 to 20; R ³² and R ³³ are each independently C ₁ -C ₂₀ alkyl; E is a hydrogen atom or a halogen atom; t is an integer of 1 to 3; R ³⁴ is C ₁ -C ₂₀ alkyl or C ₆ -C ₃₀ aryl.)

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

Preferably, in the catalyst composition according to one embodiment of the present invention, when the aluminum compound is used as a cocatalyst, the preferred range of the ratio between the metal-ligand complex of the present invention and the cocatalyst is that the aluminum compound cocatalyst may have a ratio of transition metal (M): aluminum atom (Al) in the range of 1:10 to 10,000 on a molar basis.

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 a cocatalyst, the preferred range of the ratio between the metal-ligand complex of the present invention and the cocatalyst may be a range of transition metal (M): boron atom (B): aluminum atom (Al) in terms of molar ratio of 1:0.1 to 200:10 to 10,000, and more preferably, a range of 1:0.5 to 100:25 to 5,000.

The ratio between the metal-ligand complex of the present invention and the cocatalyst exhibits excellent catalytic activity for producing an ethylene polymer within the above range, and the range of the ratio varies depending on the purity of the reaction.

In another aspect according to one embodiment of the present invention, a method for producing an ethylene polymer using the catalyst composition for producing an ethylene polymer may be carried out by contacting the metal-ligand complex, the cocatalyst, and ethylene or, if necessary, a comonomer in the presence of an appropriate organic solvent. At this time, the precatalyst and cocatalyst components, which are metal-ligand complexes, may be separately introduced into a reactor or each component may be mixed in advance and introduced into the reactor, and there are no particular restrictions on the mixing conditions such as the order of introduction, temperature, or concentration.

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

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 to C18 α-olefin can be used as a comonomer together with ethylene. Specific examples of the C3 to C18 α-olefin include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-hexadecene, 1-octadecene, etc. In the present invention, the C3 to C18 α-olefin can be polymerized alone with ethylene, or two or more kinds of olefins can be copolymerized, and more preferably, 1-butene, 1-hexene, 1-octene, or 1-decene can be copolymerized with ethylene.

The pressure of ethylene may be 1 to 1000 atm, more preferably 10 to 150 atm. In addition, it is effective that the polymerization reaction temperature is 80°C or higher, preferably 100°C or higher, and more preferably 100°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.

In general, when a solution polymerization process is carried out at a high temperature as described above, the catalyst is deformed or deteriorated as the temperature rises, which lowers the activity of the catalyst, making it difficult to obtain a polymer having desired properties. However, when an ethylene polymer is produced using the catalyst composition according to the present invention, it exhibits stable catalytic activity at a high polymerization temperature.

The above ethylene 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 wt% or more of ethylene, preferably 60 wt% or more of ethylene, and more preferably 60 to 99 wt% of ethylene.

As described above, by using the metal-ligand complex of the present invention as a main catalyst for a polymerization reaction, a low-density and low-molecular-weight ethylene homopolymer or a copolymer of ethylene and α-olefin can be produced.

For example, the ethylene polymer manufactured according to the present invention is a low-density ethylene homopolymer or a copolymer of ethylene and alpha-olefin, which may have a low density of less than 0.870 g/cc, preferably a density of 0.850 g/cc or more and less than 0.870 g/cc, and at the same time may exhibit a melt index (MI) value of 10 to 50 g/10 min (ASTM D1238, 190°C/2.16kg).

In addition, hydrogen can be used as a molecular weight regulator to control the molecular weight when producing an ethylene copolymer according to the present invention, and typically has a weight average molecular weight (Mw) in the range of 50,000 to 200,000.

The catalyst composition presented in the present invention is preferably applied to a solution polymerization process performed at a temperature above the melting point of the polymer, since it exists in a uniform form within the polymerization reactor. However, as disclosed in U.S. Patent No. 4,752,597, the catalyst composition may also be used in a slurry polymerization or gas phase polymerization process in the form of a heterogeneous catalyst composition obtained by supporting the metal-ligand complex, i.e., a procatalyst and a cocatalyst, on a porous metal oxide support.

The present invention is specifically described through the following examples, but the scope of the present invention is not limited by the following examples.

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

Methylcyclohexane, a polymerization solvent, was passed through a tube filled with 5Å molecular sieves and activated alumina and bubbled with high-purity nitrogen to sufficiently remove moisture, oxygen, and other catalyst poisons before use.

[Preparation Example 1] Synthesis of 1,3-Bis((3-iodo-3',5'-bis(trifluoromethyl)-[1,1'-biphenyl]-4-yl)oxy)propane (Compound A)

Synthesis of 3,5-Bis(trifluoromethyl)phenyl)boronic acid (compound a-1)

1-Bromo-4-methoxybenzene (2 mmol, 374 mg) was added to a two-necked round-bottomed flask, and THF (3 mL) was added. The mixture was stirred at -78°C for 30 min. n-BuLi (2 equiv) was added very slowly and stirred for 30 min. i -PrOB(pin) (1.2 equiv) was added very slowly and stirred at -78°C for 1 h. The mixture was then stirred at room temperature for 12 h. After the reaction was completed, extraction was performed using EA (ethyl acetate) and a saturated NaHCO ₃ aqueous solution. The solvent was removed by distillation under reduced pressure, and the remaining solvent was removed in vacuo to obtain the product a-1 as a white solid (438 mg, 90%).

¹ H NMR (CDCl ₃ ): δ 7.67 (d, 2H), 6.81 (d, 2H), 3.74 (s, 3H), 1.25 (s, 12H)

Synthesis of 4'-Methoxy-3,5-bis(trifluoromethyl)-1,1'-biphenyl (compound a-2)

Compound a-1 (1.5 mmol, 351 mg), 1-bromo-3,5-bis(trifluoromethyl)benzene (1.5 equiv.), Pd(PPh ₃ ) ₄ (5 mol%), and Na ₂ CO ₃ (8 equiv) were added to a two-necked round-bottomed flask and nitrogen conditions were created. DME (10 mL), EtOH (5 mL), and H ₂ O (10 mL) were sequentially added and heated under reflux at 85 °C for 24 h. After the reaction was completed, the mixture was cooled to room temperature and the catalyst was removed through a silica filter. Compound a-2 (336 mg, 70%) was obtained as a white solid through column chromatography (eluent: Ether/n-Hex = 1/50 v/v).

¹ H NMR (CDCl ₃ ): δ 7.96 (s, 2H), 7.80 (s, 1H), 7.55 (d, 2H), 7.02 (d, 2H), 3.88 (s, 3H)

Synthesis of 3',5'-Bis(trifluoromethyl)-[1,1'-biphenyl]-4-ol (compound a-3)

Compound a-2 (1 mmol, 320 mg) and DCM (8 mL) were placed in a round-bottomed flask and prepared under nitrogen conditions at 0°C. 1 M BBr ₃ (2 equiv.) was added and stirred for 4 hours. After the temperature was raised to room temperature, the mixture was stirred for 24 hours. After the reaction was completed, extraction was performed using EA and H ₂ O. The organic layer was separated and distilled under reduced pressure to remove the solvent. Recrystallization was performed using hexane (3 mL) to obtain compound a-3 as a white solid (214 mg, 70%).

¹ H NMR (CDCl ₃ ): δ 7.95 (s, 2H), 7.80 (s, 1H), 7.50 (d, 2H), 6.96 (d, 2H), 4.95 (s, 1H)

Synthesis of 3-Iodo-3',5'-bis(trifluoromethyl)-[1,1'-biphenyl]-4-ol (compound a-4)

Under a nitrogen atmosphere, compound a-3 (1 mmol, 306 mg) was placed in a round-bottom flask, MeOH (5 mL) was added, and the mixture was stirred at 0°C. NaOH (1.4 equiv.) and NaI (1.1 equiv.) were added sequentially, and then NaOCl (1.0 equiv.) was added very slowly. The mixture was stirred for 3 hours, and then 10% Na ₂ S ₂ O ₃ solution (5 mL) was added. After adjusting the pH to 5-6 with 1 M HCl solution, extraction was performed using DCM and H ₂ O, and the residue was purified by column chromatography (eluent: EA/n-Hex = 1/30 v/v) to obtain compound 4-4 as a white solid (238 mg, 55%).

¹ H NMR (CDCl ₃ ): δ 7.90 (m, 3H), 7.83 (d, 1H), 7.50 (m, 1H), 7.10 (d, 2H), 5.48 (s, 1H)

Synthesis of propane-1,3-diyl bis(4-methylbenzenesulfonate) (compound a-5)

Propane-1,3-diol (25 mmol, 1.9 g) and 4-methylbenzene-1-sulfonyl chloride (55 mmol, 10.5 g) were added to a round-bottomed flask, DCM (200 mL) was added, and the mixture was adjusted to 0℃ using an ice bath. Triethylamine (75 mmol) was added and stirred at room temperature for 12 hours. After the reaction was completed, extraction was performed using DCM and _H2O , followed by silica gel short column chromatography with EA, and recrystallization was performed using acetone to obtain compound a-5 as a white solid by filtration (7.7 g, 80%).

¹ H NMR (CDCl ₃ ): δ 7.73 (d, 4H), 7.31 (d, 4H), 4.13 (t, 4H), 2.43 (s, 6H), 1.98 (m, 2H)

Synthesis of 1,3-Bis((3-iodo-3',5'-bis(trifluoromethyl)-[1,1'-biphenyl]-4-yl)oxy)propane (Compound A)

Compound a-4 (0.5 mmol, 216 mg), compound a-5 (0.45 equiv.), K ₂ CO ₃ (2.5 equiv.), and acetone (5 mL) were added to an Andrew glass and stirred at 65°C for 3 days. After the reaction was completed, extraction was performed using EA and H ₂ O. Subsequently, compound A was obtained as a white solid (248 mg, 55%) through column chromatography (eluent: EA/n-Hex = 1/30 v/v).

¹ H NMR (CDCl ₃ ): δ 8.00 (d, 2H), 7.92 (s, 4H), 7.82 (s, 2H), 7.56 (m, 2H), 7.00 (d, 2H), 4.38 (t, 4H), 4.11 (m, 2H)

[Example 1] Synthesis of precatalyst C1

Preparation of 2-Iodo-4-(2,4,4-trimethylpentan-2-yl)phenol (Compound 1-1)

4-(2,4,4-Trimethylpentan-2-yl)phenol (50 mmol, 10.32 g), NaI (1.1 equiv.), and NaOH (1.2 equiv.) were added to a round-bottomed flask. MeOH (120 mL) was added, the temperature was adjusted to 0°C to 4°C using an ice bath, and NaOCl (1 equiv.) was slowly added over 1 hour using a syringe pump. After stirring at the same temperature for 3 hours, a 10% sodium thiosulfate solution (30 mL) was added. The pH was adjusted to 5-6 using a 5% HCl solution, extracted with diethyl ether, and purified by column chromatography (eluent: EA/n-Hex = 1/30 v/v) to obtain compound 1-1 (8.64 g, 52%) as a colorless liquid.

Preparation of 2-(2-Iodo-4-(2,4,4-trimethylpentan-2-yl)phenoxy)tetrahydro-2H-pyran (compound 1-2)

Compound 1-1 (26 mmol, 8.6 g) and p-TsOH (0.1 equiv.) were added to a round-bottomed flask and dissolved in DCM (50 mL). DHP (3 equiv.) was added, followed by p-TsOH (0.1 equiv.) and stirred at room temperature for 30 min. The reaction mixture was extracted with a 1 M K ₂ CO ₃ solution and purified by column chromatography (eluent: EA/n-Hex = 1/30 v/v) to obtain compound 1-2 as a colorless liquid (9.2 g, 85%).

Synthesis of 3,6-Di-tert-butyl-9-(2-((tetrahydro-2H-pyran-2-yl)oxy)-5-(2,4,4-trimethylpentan-2-yl)phenyl)-9-carbazole (Compound 1-3)

In a two-neck round-bottomed flask were added 3,6-di-tert-butyl-9H-carbazole (9.5 mmol, 2.7 g) and compound 1-2 (1.8 equiv.). CuI (3 mol%), N,N-dimethylethylenediamine (3 mol%), and K ₃ PO ₄ (3.8 equiv.) were added, and the mixture was made nitrogen-conditioned using a Schlenk line. Toluene (50 mL) was added and the mixture was heated and refluxed at 125°C for 4 days. After the reaction was completed, the mixture was cooled to room temperature and the catalyst was removed through a silica filter. THF was used as the washing solution. The solvent was removed by evaporation, filtered through a silica gel short column with EA, and recrystallized with acetonitrile (10 mL) to obtain compound 1-3 (3.7 g, 80%) as a colorless solid.

¹ H NMR (CDCl ₃ ): δ 8.13 (s, 2H), 7.47 (s, 1H), 7.42 (m, 3H), 7.31 (d, 1H), 7.15 (d, 1H), 7.09 (d, 1H), 5.22 (s, 1H), 3.74 (m, 1H), 3.49 (m, 1H), 1.74 (s, 2H), 1.47 (s, 18H), 1.38 (s, 6H), 0.8 (s, 9H)

Synthesis of 3,6-Di-tert-butyl-9-(2-((tetrahydro-2H-pyran-2-yl)oxy)-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-5-(2,4,4-trimethylpentan-2-yl)phenyl)-9H-carbazole (Compound 1-4)

In a round-bottom flask under nitrogen, compounds 1-3 (6.5 mmol, 3.6 g) were added, and THF (45 mL) was added. After that, n-BuLi (1.1 equiv.) was added very slowly at 0°C and stirred for 4 h. Then, 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (2.5 equiv.) was added very slowly, and the mixture was warmed to room temperature and stirred for 12 h. After the reaction was completed, cold saturated aqueous NaHCO ₃ solution (35 mL) was added, stirred for 10 min, and extracted using DCM. The resulting solid was purified by silica gel short column chromatography with EA, and the solvent was evaporated again. The obtained white solid was added to acetonitrile (10 mL) and stirred for 1 h. After stirring, the resulting compound was filtered and dried to obtain compound 1-4 as a colorless solid (4.3 g, 83%).

¹ H NMR (CDCl ₃ ): δ 8.15 (s, 1H), 8.09 (s, 2H), 8.0 (s, 1H), 7.71-7.55 (dd, 1H), 7.45 (m, 4H), 7.14 (d, 1H), 7.10 (d, 1H), 4.84 (s, 1H), 2.74 (m, 1H), 2.60 (m, 1H), 1.65 (s, 3H), 1.60 (s, 2H), 1.55 (s, 5H), 1.45 (s, 27H), 1.38 (m, 27H), 0.81 (s, 5H), 0.77 (s, 9H)

Synthesis of ligand L1

Under a nitrogen atmosphere, compound A (0.4 mmol, 362 mg), compounds 1-4 (2.5 equiv.), Pd(PPh ₃ ) ₄ (5 mol%), and NaOH (12 equiv.) were added to a two-necked round-bottomed flask. DME (16 mL), THF (8 mL), and H ₂ O (2 mL) were sequentially added and refluxed at 85°C for 24 h. After the reaction was completed, the mixture was cooled to room temperature and the catalyst was removed through a silica filter. The solvent was removed by distillation under reduced pressure, and the remaining solvent was removed using a vacuum.

The residue from which the solvent had been removed above was placed in a round-bottomed flask, and p -TsOH (1 mol%) was added thereto. 100 mL each of MeOH and THF were added, and the mixture was heated and refluxed at 65°C for 4 hours. After the reaction was completed, it was cooled to room temperature and extracted with water. The extracted filtrate was purified by column chromatography (eluent EA/n-Hex = 1/50 v/v) and then recrystallized using MeOH (5 mL) to obtain ligand L1 as a white solid (0.28 g, 52%).

¹ H NMR (CDCl ₃ ): δ 8.20 (s, 4H), 7.86 (s, 4H), 7.82 (s, 2H), 7.44 (d, 4H), 7.37 (m, 4H), 7.27 (s, 2H), 7.07 (d, 4H), 6.79 (d, 2H), 6.02 (d, 2H), 4.93 (s, 2H), 3.91 (m, 4H), 2.04 (m, 2H), 1.70 (s, 4H), 1.40 (s, 36H), 1.35 (s, 12H), 0.80 (s, 18H)

Synthesis of precatalyst C1

The reaction was carried out in a glove box under a nitrogen atmosphere. ZrCl ₄ (0.55 g, 2.36 mmol) and toluene (100 mL) were added to a 100 mL flask to prepare a slurry. The slurry was cooled to -20°C for 30 min in a glove box freezer. To the cold, stirring slurry, 3.0 M methylmagnesium bromide (3.25 mL, 12.8 mmol) in diethyl ether was added. The mixture was stirred vigorously for 30 min. The solid dissolved, but the reaction solution turned cloudy yellow. Ligand L1 (3.2 g, 1.98 mmol) was dissolved in toluene (70 mL) and slowly added to the mixture. After warming the reaction flask to room temperature and stirring for 12 h, the reaction mixture was filtered using a syringe attached to a membrane filter. The filtered yellow-brown solution was dried in a vacuum and recrystallized using hexane (15 mL), and the precatalyst C1 was obtained as a white solid by filtration (1.96 g, 57.2% yield).

¹ H NMR (CDCl ₃ ): δ 8.18 (s, 2H), 7.89 (s, 2H), 7.79 (s, 4H), 7.72 (s, 2H), 7.48 (m, 2H), 7.36-7.10 (m, 12H), 6.65 (m, 2H), 4.62 (d, 2H), 3.77 (m, 2H), 3.31 (m, 2H), 1.65-1.40 (m, 6H), 1.45 (s, 18H), 1.25 (s, 6H), 1.18 (s, 6H), 1.17 (s, 18H), 0.63 (s, 18H), -1.66 (s, 6H).

[Comparative Manufacturing Example 1] Synthesis of 1,3-bis(4-fluoro-2-iodophenoxy)propane (Compound B)

Synthesis of 4-Fluoro-2-iodophenol (compound b-1)

4-Fluorophenol (40 mmol, 4.9 g), NaI, and NaOH were added in equivalent amounts to a round-bottomed flask, and MeOH (60 mL) was added thereto, and the temperature was adjusted to 0 to 4°C using an ice bath. NaOCl (1 equiv.) was added over 1 hour using a syringe pump. After all of the NaOCl was added, the mixture was stirred at the same temperature for 3 hours. Afterwards, 10% sodium thiosulfate solution (30 mL) was added thereto, the pH was adjusted to 5 to 6 with 5% HCl solution, and extracted with diethyl ether. The extracted filtrate was purified by column chromatography (eluent EA/n-Hex = 1/30 v/v) to obtain compound b-1 as a pale yellow solid (5.2 g, 54%).

¹ H NMR (CDCl ₃ ): δ 7.39 (d, 1H), 7.01 (m, 1H), 6.98 (m, 1H), 5.10 (s, 1H)

Synthesis of 1,3-bis(4-fluoro-2-iodophenoxy)propane (Compound B)

Compound a-5 (2.5 mmol, 961 mg) and compound b-1 (5 mmol, 1.2 g) were placed in a round-bottomed flask, and K ₂ CO ₃ (1.5 equiv.) and acetone (20 mL) were added. The mixture was heated and refluxed for 24 h. After the reaction was completed, the mixture was cooled to room temperature, acetone was removed by distillation under reduced pressure, and extracted with MC (methylene chloride) and water. The extracted filtrate was purified by column chromatography (eluent EA/n-Hex = 1/10 v/v) to obtain compound B as a yellow solid (1.03 g, 80%).

¹ H NMR (CDCl ₃ ): δ 7.49 (d, 2H), 7.02 (m, 2H), 6.80 (m, 2H), 4.25 (t, 4H), 2.34 (q, 2H)

[Comparative Example 1] Synthesis of precatalyst C2

Synthesis of 2-Iodo-4-octylphenol (Compound 2-1)

4-n-Octylphenol (20 mmol, 4.1 g), NaI (1.1 equiv.), and NaOH (1.2 equiv.) were added to a round-bottomed flask, and MeOH (120 mL) was added thereto. The mixture was adjusted to 0 to 4°C using an ice bath. NaOCl (1 equiv.) was slowly added thereto using a syringe pump over 1 h, and the mixture was stirred for an additional 3 h at the same temperature. After adding 10% sodium thiosulfate solution (30 mL), the pH was adjusted to 5 to 6 using 5% HCl solution, and extracted with diethyl ether. After removing the solvent from the extracted filtrate, column chromatography (eluent: EA/n-Hex = 1/30 v/v) was used to obtain compound 2-1 (2.9 g, 65%) as a colorless liquid.

Synthesis of 2-(2-iodo-4-octylphenoxy)tetrahydro-2H-pyran (compound 2-2)

Compound 2-1 (35.7 mmol, 7.8 g) and p-TsOH (0.1 equiv.) were placed in a round-bottomed flask, DCM (50 mL) was added, DHP (Dihydropyran, 3 equiv.) was added, and the mixture was stirred at room temperature for 30 minutes. After extraction with 1 M K ₂ CO ₃ solution, the mixture was purified by column chromatography (eluent: EA/n-Hex = 1/30 v/v) to obtain compound 2-2 as a colorless liquid (9.2 g, 85%).

¹ H NMR (CDCl ₃ ): δ 7.46 (s, 1H), 7.05 (d, 1H), 6.90 (d, 1H), 5.13 (s, 1H), 2.49 (t, 3H), 1.55 (m, 2H), 1.28 (m, 10H), 0.88 (t, 3H)

Synthesis of 3,6-Di-tert-butyl-9-(5-octyl-2-((tetrahydro-2H-pyran-2-yl)oxy)phenyl)-9H-carbazole (Compound 2-3)

In a two-neck round-bottomed flask, 3,6-di-tert-butyl-9H-carbazole (5 mmol, 1.4 g) and compound 2-2 (1.8 equiv.) were placed. CuI (3 mol%), N,N-dimethylethylenediamine (3 mol%), and K ₃ PO ₄ (3.8 equiv.) were added, and nitrogen conditions were prepared using a shrink line. Toluene (25 mL) was added and the mixture was heated and refluxed at 125°C for 4 days. After the reaction was completed, the mixture was cooled to room temperature and the catalyst was removed through a silica filter. THF was used as the washing solution. The solvent was removed by distillation under reduced pressure, and recrystallization was performed using acetonitrile (5 mL) to obtain compound 2-3 (0.94 g, 51%) as a colorless solid.

¹ H NMR (CDCl ₃ ): δ 8.13 (s, 2H), 7.43 (m, 2H), 7.31 (m, 2H), 7.29 (m, 1H), 7.17 (m, 1H), 7.13 (m, 1H), 5.21 (m, 1H), 4.15 (m, 1H), 3.74(m, 1H), 3.70(m, 1H), 2.62(m, 2H), 1.62(m, 2H), 1.47(s, 20H), 1.38 ~ 1.25(m, 18H), 0.88(m, 3H)

Synthesis of 3,6-Di-tert-butyl-9-(5-octyl-2-((tetrahydro-2H-pyran-2-yl)oxy)-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-9H-carbazole (Compound 2-4)

Under a nitrogen atmosphere, compound 2-3 (4 mmol, 2.3 g) was placed in a round-bottom flask, THF (45 mL) was added, and n-BuLi (1.1 equiv.) was added very slowly at 0°C and stirred for 4 hours. After 4 hours, 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (i-PrO-B(pin), 2.5 equiv.) was added very slowly, the temperature was raised to room temperature, and the mixture was stirred for 12 hours. After the reaction was completed, a cold saturated aqueous solution of NaHCO ₃ (35 mL) was added, stirred for 10 minutes, and extracted using DCM. The solid formed after extraction was purified by silica gel short column chromatography with EA, and the solvent was evaporated again. The white solid obtained was added to acetonitrile (10 mL) and stirred for 1 hour. After stirring, the compound obtained by filtration was dried to obtain compound 2-4 as a colorless solid (1.1 g, 41%).

¹ H NMR (CDCl ₃ ): δ 8.13 (s, 2H), 7.94 (s, 1H), 7.55 (s, 1H), 7.45 (d, 2H), 7.35 (s, 1H), 7.17 (m, 1H), 7.13 (d, 2H), 2.58 (t, 2H), 1.61 (m, 3H), 1.44 ~ 1.37(m, 20H), 1.35(s, 12H), 1.27(m, 10H), 0.87(m, 3H)

Synthesis of ligand L2

Under a nitrogen atmosphere, compounds 2-4 (2 mmol, 1.2 g), compound B (0.5 equiv.), and NaOH (3 equiv.) were added to a two-neck round-bottom flask. DME (40 mL), THF (20 mL), and H ₂ O (10 mL) were sequentially added and refluxed at 100°C for 48 h. After the reaction was completed, the mixture was cooled to room temperature and the catalyst was removed through a silica filter. The solvent was removed by distillation under reduced pressure, and the remaining solvent was removed using a vacuum.

The residue from which the solvent had been removed above was placed in a round-bottomed flask, and p-TsOH (1 mol%) was added thereto. 100 mL each of MeOH and THF were added, and the mixture was heated and refluxed at 80°C for 8 hours. After the reaction was completed, it was cooled to room temperature and extracted with water. The extracted filtrate was purified by column chromatography (eluent EA/n-Hex = 1/50 v/v) and then recrystallized using EA (5 mL) to obtain ligand L2 (0.7 g, 29%).

¹ H NMR (CDCl ₃ ): δ 8.22 (s, 4H), 7.43 (m, 4H), 7.36 (s, 2H), 7.32 (s, 2H), 7.12 (m, 6H), 7.03 (s, 2H), 6.54 (m, 2H), 6.05 (m, 2H), 5.47 (s, 2H), 3.83 (m, 4H), 2.59 (m, 4H), 2.08 (m, 2H), 1.35-1.27 (m, 66H), 0.90 (m, 6H).

Synthesis of precatalyst C2

The reaction was carried out in a glove box under a nitrogen atmosphere. ZrCl ₄ (0.45 g, 1.93 mmol) and toluene (80 mL) were added to a 100 mL flask to prepare a slurry. The slurry was cooled to -20°C in a glove box freezer for 30 min. To the cold, stirring slurry, 3.0 M methylmagnesium bromide (2.6 mL, 10.2 mmol) in diethyl ether was added. The mixture was stirred vigorously for 30 min. The solid dissolved, but the reaction solution turned a cloudy yellow. Ligand L2 (2.0 g, 1.6 mmol) was slowly added as a solid to the mixture. The reaction flask was warmed to room temperature and stirred for 12 h. The reaction mixture was then filtered using a syringe equipped with a membrane filter. The filtered solution was dried in vacuo to obtain the precatalyst C2 as a brown solid (2.04 g, 93.2% yield).

¹ H NMR (CDCl ₃ ): δ 8.31 (s, 2H), 8.08 (s, 2H), 7.47-7.32 (m, 10H), 7.05-6.98 (m, 4H), 6.28 (m, 2H), 4.58 (m, 2H), 3.78 (m, 2H), 3.39 (m, 2H), 2.62 (m, 4H), 2.0-1.3 (m, 26H), 1.54 (s, 18H), 1.39 (s, 18H), 0.87 (t, 6H), -1.47 (s, 6H)

[Comparative Example 2] Synthesis of precatalyst C3

Synthesis of ligand L3

Under a nitrogen atmosphere, compounds 1-4 (2.5 mmol), compound B (0.5 equiv.), Pd(PPh ₃ ) ₄ (0.3 mol%), and NaOH (3 equiv.) were added to a two-neck round-bottom flask. DME (40 mL), THF (20 mL), and H ₂ O (10 mL) were sequentially added thereto, and the mixture was heated and refluxed at 100°C for 48 h. After the reaction was completed, the mixture was cooled to room temperature, the catalyst was removed through a silica filter, and the solvent was removed by distillation under reduced pressure, and the remaining solvent was removed using a vacuum.

The residue from which the solvent was removed above was added to a round-bottomed flask, and p-TsOH (1 mol%) was added thereto, followed by 100 mL each of MeOH and THF, and heated and refluxed at 80°C for 8 hours. After the reaction was completed, the mixture was cooled to room temperature, extracted with water, and separated and purified by column chromatography (eluent EA/n-Hex = 1/50 v/v), followed by recrystallization using EA (5 mL) to obtain ligand L3 (1.1 g, 70%).

¹ H NMR (CDCl ₃ ): δ8.23 (s, 4H), 7.45 (d, 4H), 7.43 (s, 2H), 7.39 (d, 2H), 7.25 (d, 4H), 6.95 (d, 2H), 6.53 (m, 2H), 5.95 (m, 2H), 5.40 (s, 2H), 3.80 (t, 4H), 1.99 (m, 2H), 1.71 (s, 4H), 1.49 (s, 36H), 1.36 (s, 12H), 0.80 (s, 18H)

Synthesis of precatalyst C3

Precatalyst 3 was prepared in the same manner as in Example 1, except that ligand L3 was used instead of ligand L1 in Example 1.

¹ H NMR (CDCl ₃ ): δ8.31 (s, 2H), 8.07 (s, 2H), 7.57 (m, 2H), 7.46-7.15 (m, 10H), 6.98 (m, 2H), 6.27 (m, 2H), 4.58 (m, 2H), 3.75 (m, 2H), 3.35 (m, 2H), 1.73 (m, 4H), 1.57-1.54 (m, 2H), 1.54 (s, 18H), 1.40 (s, 6H), 1.37 (s, 18H), 1.34 (s, 6H), 0.79 (s, 18H), -1.50 (s, 6H)

[Example 2] Copolymerization of ethylene and 1-octene

Copolymerization of ethylene and 1-octene was performed as follows using a batch polymerization apparatus.

After sufficient drying, 600 mL of methylcyclohexane and 80 mL of 1-octene were placed in a 1500 mL stainless steel reactor that was purged with nitrogen, and then 2 mL of a 1.0 M hexane solution of triisobutylaluminum was added to the reactor. After that, the temperature of the reactor was heated to 100°C, and 0.5 μmol of the precatalyst C1 prepared in Example 1 and triphenylmethyllinium tetrakis(pentafluorophenyl)borate were added. 40 μmol were sequentially injected, and then the pressure inside the reactor was filled with ethylene to 20 bar, and then continuously supplied to polymerize. After the reaction was carried out for 5 minutes, the recovered reaction product was dried in a vacuum oven at 40°C for 8 hours. The polymerization results are shown in Table 1 below.

Melt flow index (MI): Measured at 190℃ with a load of 2.16 kg using the ASTM D1238 analysis method.

Density: Measured using ASTM D792 method.

[Comparative Example 3]

Copolymerization of ethylene and 1-octene was performed in the same manner as in Example 2, except that 0.5 μmol of the precatalyst C2 prepared in Comparative Example 1 was added. The polymerization reaction conditions and polymerization results are shown in Table 1 below.

[Comparative Example 4]

Copolymerization of ethylene and 1-octene was performed in the same manner as in Example 2, except that 0.5 μmol of the precatalyst C3 prepared in Comparative Example 2 was added. The polymerization reaction conditions and polymerization results are shown in Table 1 below.

Batch polymerization reaction results polymerization polymerization catalyst ΔT
(℃) Catalytic activity
(Polymer (kg)/Catalyst usage (mmol)) polymer density
(g/cc) MI Example 2 Precatalyst C1
(Example 1) 36.7 180.2 0.861 21.16 Comparative Example 3 Precatalyst C2
(Comparative Example 1) 15.5 80.6 0.887 0.14 Comparative Example 4 Precatalyst C3
(Comparative Example 2) 29.0 151.0 0.879 0.36 ^* Polymerization catalyst: triphenylmethylinium tetrakis(pentafluorophenyl)borate: triisobutylaluminum molar ratio = 1:80:4000

From the polymerization results in Table 1 above, it can be confirmed that the catalytic activity and polymer properties significantly differ depending on the structure of the polymerization catalyst.

Specifically, in Example 2, which used the precatalyst C1 of Example 1, in which a phenyl group substituted with a perfluoroalkyl group such as a trifluoromethyl group was introduced, as a polymerization catalyst, the catalytic activity was significantly increased compared to the cases of Comparative Examples 3 and 4, in which the precatalyst C2 of Comparative Example 1 and the precatalyst C3 of Comparative Example 2, which had structures in which a fluoro group was introduced at the same position, were used, and a copolymer of ethylene and 1-octene with a high MI value, which means low density and low molecular weight, was produced.

That is, it can be seen that when the precatalyst C1 of the present invention was used, the MI value was significantly higher than that of the precatalysts C2 and C3 of the comparative examples. From this, it can be seen that the copolymer produced using the metal-ligand complex of the present invention as a polymerization catalyst has a lower molecular weight than the comparative examples. It can be seen that the production of such a low-density and low-molecular-weight copolymer is due to the structural characteristics of the polymerization catalyst.

Therefore, the metal-ligand complex according to the present invention can be useful for the development of high value-added products because it can effectively produce low-density and low-molecular-weight copolymers of ethylene and alpha-olefins with surprisingly excellent catalytic activity even at high temperatures due to the structural characteristics resulting from the introduction of a phenyl group substituted with a perfluoroalkyl group as an electron-withdrawing group of a highly controlled bulky form.

While the embodiments of the present invention have been described in detail above, those skilled in the art will appreciate that various modifications and variations can be made to the present invention without departing from the scope of the invention as defined in the appended claims. Therefore, modifications to future embodiments of the present invention will not depart from the scope of the invention.

Claims (11)

A metal-ligand complex represented by the following chemical formula 1:
[Chemical Formula 1]

(In the above chemical formula 1,
M is a transition metal in group 4 of the periodic table;
R' and R'' are independently C ₁ -C ₂₀ alkyl, C ₆ -C ₂₀ aryloxy or C ₁ -C ₂₀ alkylC ₆ -C ₂₀ aryloxy;
R ₁ and R ₂ are independently hydrogen or -C _n F _2n+1 ;
R ₃ to R ₆ are each independently C ₁ -C ₂₀ alkyl, C ₆ -C ₂₀ aryl or C ₆ -C ₂₀ arylC ₁ -C ₂₀ alkyl;
R ₇ and R ₈ are independently C ₁ -C ₂₀ alkyl or C ₁ -C ₂₀ alkoxy;
R ₉ and R ₁₀ are independently hydrogen or C ₁ -C ₂₀ alkyl;
a, b and n are independently integers from 1 to 3;
m is an integer from 2 to 5.) In paragraph 1,
A metal-ligand complex wherein a and b are integers of 1. In paragraph 1,
wherein R' and R'' are independently C ₁ -C ₂₀ alkyl or C ₁ -C ₂₀ alkylC ₆ -C ₂₀ aryloxy;
R ₁ and R ₂ are independently hydrogen or -CF ₃ ;
R ₃ to R ₆ are each independently C ₁ -C ₂₀ alkyl;
R ₇ and R ₈ are independently C ₁ -C ₂₀ alkyl or C ₁ -C ₂₀ alkoxy;
R ₉ and R ₁₀ are independently hydrogen or C ₁ -C ₂₀ alkyl;
A metal-ligand complex, wherein m is an integer from 3 to 5. In paragraph 1,
A metal-ligand complex represented by the following chemical formula 2:
[Chemical Formula 2]

(In the above chemical formula 2,
M is titanium, zirconium or hafnium;
R' and R'' are independently C ₁ -C ₂₀ alkyl or C ₁ -C ₂₀ alkylC ₆ -C ₂₀ aryloxy;
R ₁ and R ₂ are independently hydrogen or -CF ₃ ;
R ₃ to R ₆ are each independently C ₁ -C ₂₀ alkyl;
R ₇ and R ₈ are independently C ₁ -C ₂₀ alkyl or C ₁ -C ₂₀ alkoxy;
R ₉ and R ₁₀ are independently hydrogen or C ₁ -C ₂₀ alkyl;
m is an integer between 3 and 5.) In paragraph 4,
wherein R' and R'' are the same as each other and are C ₁ -C ₅ alkyl;
R ₁ and R ₂ are the same as each other and are hydrogen or -CF ₃ ;
R ₃ to R ₆ are the same as each other and are C ₁ -C ₅ alkyl;
R ₇ and R ₈ are independently C ₈ -C ₂₀ alkyl;
A metal-ligand complex wherein R ₉ and R ₁₀ are the same and are hydrogen or C ₁ -C ₅ alkyl. In paragraph 1,
A metal-ligand complex represented by the following chemical formula 3:
[Chemical Formula 3]

(In the above chemical formula 3,
M is zirconium or hafnium;
R ₁₁ is hydrogen or -CF ₃ ;
R ₁₂ is C ₈ -C ₂₀ alkyl;
R ₁₃ is hydrogen or methyl;
p is an integer of 1 or 2.) A metal-ligand complex according to any one of claims 1 to 6; and
A catalyst composition for producing an ethylene polymer, comprising a cocatalyst. In paragraph 7,
A catalyst composition for producing an ethylene polymer, wherein the cocatalyst is an aluminum compound cocatalyst, a boron compound cocatalyst, or a mixture thereof. In paragraph 7,
A catalyst composition for producing an ethylene polymer, wherein the above cocatalyst is used in an amount of 0.5 to 10,000 moles per mole of the metal-ligand complex. A method for producing an ethylene polymer, comprising the step of producing an ethylene polymer by polymerizing ethylene or ethylene and alpha-olefin in the presence of a catalyst composition for producing an ethylene polymer of claim 7. In paragraph 10,
A method for producing an ethylene polymer, wherein the above polymerization is performed at 100 to 250°C.