CN118475586A - Metal-ligand complex, catalyst composition containing the complex for preparing vinyl polymer, and method for preparing ethylene polymer using the complex - Google Patents

Abstract

Disclosed are a metal-ligand complex, and a catalyst composition for preparing a vinyl polymer and a method for preparing a vinyl polymer using the same. The metal-ligand complex improves the tolerance of the catalyst to oxygen, moisture and other impurities by introducing specific functional groups, and remarkably improves the high-temperature activity and stability.

Description

Metal-ligand complex, catalyst composition containing the complex for preparing vinyl polymer, and method for preparing ethylene polymer using the complex

Technical Field

The following disclosure relates to a metal-ligand complex, a catalyst composition containing the metal-ligand complex for preparing a vinyl polymer, and a method for preparing a vinyl polymer using the metal-ligand complex.

Background Art

Generally, in the preparation of vinyl polymers, such as copolymers of ethylene and α-olefins or copolymers of ethylene and olefin-dienes, a so-called Ziegler-Natta catalyst system is used, which generally comprises a titanium or vanadium compound as a main catalyst component and an alkylaluminum compound as a cocatalyst component.

U.S. Patent Nos. 3,594,330 and 3,676,415 disclose improved Ziegler-Natta catalysts. However, although the Ziegler-Natta catalyst system has high activity for ethylene polymerization, it also has disadvantages. Due to the heterogeneity of the catalyst active sites, the molecular weight distribution of the polymers prepared is generally broad, and in particular, the copolymers of ethylene and α-olefins have a non-uniform component distribution.

Since then, various studies have been conducted on metallocene catalyst systems, including metallocene compounds of transition metals of Group 4 in the periodic table, such as zirconium and hafnium, and methylaluminoxane as a cocatalyst. The metallocene catalyst system is a homogeneous catalyst with a single catalyst active site, and compared with the traditional Ziegler-Natta catalyst system, it can produce polyethylene with a narrow molecular weight distribution and uniform composition distribution.

For example, European Patent Publication Nos. ₃₂₀₇₆₂ and 372632 disclose that metallocene compounds can be activated in _{methylaluminoxane} in catalysts such as _Cp2TiCl2 , _{Cp2ZrCl2 ,} Cp2ZrMeCl, _Cp2ZrMe2 , ethylene( _IndH4 ) _{2ZrCl2 ,} etc. to polymerize ethylene with high activity to prepare polyethylene having a molecular weight distribution (Mw/ _Mn ) in the range of 1.5 to 2.0.

However, it is difficult to obtain high molecular weight polymers using the above catalyst systems.

That is, it is known that when a solution polymerization method performed at a high temperature is applied, the polymerization activity rapidly decreases and the β-dehydrogenation reaction dominates, which is not suitable for preparing a high molecular weight polymer.

At the same time, organometallic catalysts usually require expensive preparation costs due to the high difficulty and complexity of the preparation steps. In addition, the catalyst may be exposed to air during the preparation process or storage and transfer, at which time the activity of the catalyst may be significantly reduced. In the worst case, the catalyst may be discarded because it cannot be used. From the perspective of catalyst manufacturers or catalyst users, catalysts that are stable to oxygen or moisture in the air must have great advantages.

Therefore, there is still a need for catalysts and catalyst precursors with desired improved properties in the chemical industry. Therefore, it is urgent to develop a competitive catalyst with excellent stability, high temperature activity, reactivity with higher α-olefins and the ability to prepare high molecular weight polymers.

Summary of the invention

Technical issues

One embodiment of the present invention is directed to providing a metal-ligand complex having a specific functional group and a catalyst composition comprising the metal-ligand complex to alleviate the existing problems.

Another embodiment of the present invention is directed to a method for preparing a vinyl polymer using the catalyst composition according to the present invention.

Technical Solution

The present invention provides a metal-ligand complex having significantly improved high temperature activity due to improved tolerance of the catalyst to impurities such as oxygen and moisture and high temperature stability by introducing a specific functional group. In one aspect, the present invention provides a metal-ligand complex represented by the following chemical formula 1:

[Chemical formula 1]

In Chemical Formula 1,

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

Ar ₁ and Ar ₂ are each independently a C ₆ -C ₂₀ aryl group, and the aryl groups described in Ar ₁ and Ar ₂ may be further substituted by a C ₁ -C ₂₀ alkyl group;

_R1 to _R4 are each independently _C1 - _C20 alkyl, _C6 - _C20 aryl or _C6 - _C20 arylC1- _{C20 alkyl} ;

R ₅ and R ₆ are each independently C ₁ -C ₂₀ alkyl;

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

a, b, c, d, e and f are each independently an integer from 0 to 4; and

m is an integer ranging from 2 to 5.

In another aspect, a catalyst composition for preparing a vinyl polymer comprises the metal-ligand complex according to the present invention and a cocatalyst.

In another aspect, a method for preparing an vinyl polymer comprises preparing the vinyl polymer by polymerizing ethylene or ethylene and an α-olefin in the presence of the catalyst composition for preparing the vinyl polymer according to the present invention.

Beneficial Effects

The metal-ligand complex according to the present invention introduces a specific functional group, so that the stability of the complex can be significantly improved, thereby promoting polymerization at a high polymerization temperature without reducing the catalytic activity.

In particular, the metal-ligand complex according to the present invention has relatively excellent resistance to impurities such as oxygen and moisture, and can produce a high molecular weight vinyl polymer at a high polymerization temperature.

That is, when preparing vinyl polymers, i.e., ethylene homopolymers or copolymers of ethylene and α-olefins, by using the catalyst composition containing the metal-ligand complex according to the present invention, ethylene homopolymers or copolymers of ethylene and α-olefins having high molecular weight and excellent catalytic activity can be effectively prepared even at a polymerization temperature of 220°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 resistance to impurities and excellent thermal stability, so that the metal-ligand complex has excellent copolymerization reactivity with olefins and can prepare high molecular weight ethylene-based polymers in high yield while maintaining high catalytic activity even at high temperatures.

Therefore, the metal-ligand complex of the present invention and the catalyst composition comprising the same can be effectively used to prepare a vinyl polymer having excellent physical properties.

Invention

Hereinafter, the present invention will describe the metal-ligand complex according to the present invention, a catalyst composition for preparing a vinyl polymer comprising the metal-ligand complex, and a method for preparing a vinyl polymer using the metal-ligand complex, but the technical terms and scientific terms used herein have the general meanings understood by those skilled in the art to which the present invention belongs unless otherwise defined, and descriptions of known functions and configurations that obscure the present invention will be omitted in the following description.

As used herein, the following terms are defined below, but are for illustrative purposes only and are not intended to limit the invention, application or uses.

As used herein, the terms "substituent," "radical," "group," "group," "moiety," and "fragment" are used interchangeably.

As used herein, the term " _CA - _CB " means "the number of carbon atoms is greater than or equal to A and less than or equal to B".

As used herein, the term "alkyl" refers to a straight or branched saturated monovalent hydrocarbon group consisting only of carbon and hydrogen atoms. The alkyl group may have 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, but the present invention is not limited thereto. Specific examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, isopentyl, methylbutyl, n-hexyl, tert-hexyl, methylpentyl, dimethylbutyl, heptyl, ethylpentyl, methylhexyl, dimethylpentyl, n-octyl, tert-octyl, dimethylhexyl, ethylhexyl, n-decyl, tert-decyl, n-dodecyl, tert-dodecyl, etc.

As used herein, the term "aryl" refers to a monovalent organic radical derived from an aromatic hydrocarbon by removing one hydrogen, and includes a monocyclic or condensed ring system, wherein each ring contains appropriately 4 to 7, preferably 5 or 6 ring atoms, and even includes a form in which multiple aryl groups are connected by single bonds. Specific examples of aryl include, but are not limited to, phenyl, naphthyl, biphenyl, fluorenyl, phenanthrenyl, anthracenyl, triphenyl, pyrenyl, Base, tetraphenyl, etc.

The term "alkylaryl" as used herein refers to an aryl group substituted by at least one alkyl group, wherein "alkyl" and "aryl" are as defined above. Specific examples of alkylaryl groups include, but are not limited to, tolyl and the like.

The term "arylalkyl" as used herein refers to an alkyl group substituted by at least one aryl group, wherein "alkyl" and "aryl" are as defined above. Specific examples of arylalkyl include, but are not limited to, tolyl and the like.

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:

[Chemical formula 1]

In Chemical Formula 1,

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

Ar ₁ and Ar ₂ are each independently a C ₆ -C ₂₀ aryl group, and the aryl groups described in Ar ₁ and Ar ₂ may be further substituted by a C ₁ -C ₂₀ alkyl group;

_R1 to _R4 are each independently _C1 - _C20 alkyl, _C6 - _C20 aryl or _C6 - _C20 arylC1- _{C20 alkyl} ;

R ₅ and R ₆ are each independently C ₁ -C ₂₀ alkyl;

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

a, b, c, d, e and f are each independently an integer from 0 to 4; and

m is an integer ranging from 2 to 5.

The metal-ligand complex according to the exemplary embodiment introduces a specific functional group aryloxy as a leaving group to increase the catalyst's tolerance to impurities such as oxygen and moisture, thereby forming a strong bond between the central transition metal and the ligand. Therefore, the stability of the complex can be significantly improved.

In addition, the metal-ligand complex according to the exemplary embodiment introduces an aryloxy group instead of a methyl group as a leaving group, so that the solubility in an organic solvent can be significantly improved, thereby more effectively improving the polymerization process.

Due to the above structural characteristics, the metal-ligand complex not only has significantly improved solubility in hydrocarbon solvents, but also has high resistance to impurities and excellent thermal stability, so that the metal-ligand complex can have excellent polymerization activity with other substances. It can maintain high catalytic activity even at high temperatures, and can prepare high molecular weight vinyl polymers in high yields. Therefore, compared with known metallocene-based and non-metallocene-based single-active site catalysts, the metal-ligand complex has high commercial applicability.

Preferably, according to an exemplary embodiment, in Chemical Formula 1, _Ar1 and _Ar2 may each independently be a _C6 - _C20 aryl group or a _C1 - _C20 alkyl- _C6 - _C20 aryl group; _R1 to _R4 may each independently be a _C1 - _C20 alkyl group; _R7 and _R8 may each independently be a halogen or a _C1 - _C20 alkyl group; a, b, c, d, e and f may each independently be an integer in the range of 1 to 3; and m may be an integer in the range of 3 to 5, more preferably, _Ar1 and _Ar2 may each independently be a _C6 - _C12 aryl group or a _C1 - _C20 alkyl- _C6 - _C12 aryl group; _R1 to _R4 may each independently be a _C1 - _C10 alkyl group; _R5 and _R6 may each independently be a _C1 - _C10 alkyl group; _R7 and _R8 may each independently be a halogen or a _C1- C12 alkyl group. a, b _, c, d, e and f may each independently be an integer of 1 or 2; and m may be an integer ranging from 3 to 5.

In a specific embodiment, M may be titanium, zirconium or hafnium.

In a specific embodiment, Ar ₁ and Ar ₂ may each independently be an aryl group which is unsubstituted or substituted with a C ₁ -C ₂₀ alkyl group, wherein the aryl group may be phenyl, biphenyl, naphthyl, anthracenyl, pyrenyl, phenanthrenyl or tetraenyl.

In a specific embodiment, R ₁ to R ₄ may each independently be a branched C ₃ -C ₁₀ alkyl group, a branched C ₃ -C ₇ alkyl group or a branched C ₃ -C ₄ alkyl group.

In terms of having stronger resistance, thermal stability and excellent catalytic activity, preferably, the metal-ligand complex according to an exemplary embodiment can be represented by the following Chemical Formula 2-1 or the following Chemical Formula 2-2:

[Chemical formula 2-1]

[Chemical formula 2-2]

In chemical formulas 2-1 and 2-2,

M is titanium, zirconium or hafnium;

Ar ₁ and Ar ₂ are each independently C ₆ -C ₂₀ aryl or C ₁ -C ₂₀ alkyl C ₆ -C ₂₀ aryl;

R ₁ to R ₄ are each independently C ₁ -C ₂₀ alkyl;

R ₅ and R ₆ are each independently C ₁ -C ₂₀ alkyl;

_X1 and _X2 are each independently halogen;

R' and R" are each independently hydrogen or _C1 - _C20 alkyl; and

m is an integer ranging from 3 to 5.

According to an exemplary embodiment, in Chemical Formulas 2-1 and 2-2, _Ar1 and _Ar2 may each independently be a _C6 - _C12 aryl group or a _C1 - _C20 alkyl _C6 - _C12 aryl group; _R1 to _R4 may each independently be a _C1 - _C10 alkyl group; _R5 and _R6 may each independently be a _C1 - _C10 alkyl group; and R' and R" may each independently be hydrogen or a _C1 - _C10 alkyl group; more preferably, _Ar1 and _Ar2 may be the same as each other and may be a _C6 - _C12 aryl group or a _C1 - _C20 alkyl _C6 - _C12 aryl group; _R1 to _R4 may be the same as each other and may be a _C1 - _C10 alkyl group; _R5 and _R6 may be the same as each other and may be a _C1 - _C10 alkyl group; R' and R" may be the same as each other and may be hydrogen or a _C1 - _C10 alkyl group.

In a specific embodiment, R ₁ to R ₄ may each independently be a branched C ₃ -C ₁₀ alkyl group, a branched C ₃ -C ₇ alkyl group or a branched C ₃ -C ₄ alkyl group.

More preferably, the metal-ligand complex according to the exemplary embodiment may be represented by the following Chemical Formula 3-1 or the following Chemical Formula 3-2:

[Chemical formula 3-1]

[Chemical formula 3-2]

In chemical formulas 3-1 and 3-2,

M is zirconium or hafnium;

Ar is C ₆ -C ₁₂ aryl or C ₁ -C ₂₀ alkyl C ₆ -C ₁₂ aryl;

R ₁₁ is a C ₁ -C ₅ alkyl group;

R ₁₂ is a C ₁ -C ₁₀ alkyl group;

X ₁₁ is fluorine or chlorine;

R''' is hydrogen or C ₁ -C ₁₀ alkyl; and

n is an integer ranging from 1 to 3.

According to an exemplary embodiment, in Chemical Formulas 3-1 and 3-2, Ar may be a C ₆ -C ₁₂ aryl group or a C ₈ -C ₂₀ alkyl C ₆ -C ₁₂ aryl group; R ₁₁ may be a C ₃ -C ₅ alkyl group; R ₁₂ may be a C ₁ -C ₁₀ alkyl group; X ₁₁ may be fluorine or chlorine; R'' may be hydrogen or a C ₁ -C ₅ alkyl group; and n may be an integer from 1 to 3.

In a specific example, R ₁₁ may be a branched C ₃ -C ₄ alkyl group, specifically a tert-butyl group.

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

[Chemical formula 4-1]

[Chemical formula 4-2]

In chemical formulas 4-1 and 4-2,

M is zirconium or hafnium;

R is hydrogen or C ₈ -C ₂₀ alkyl;

R ₁₂ is a C ₁ -C ₁₀ alkyl group;

X ₁₁ is fluorine or chlorine;

R''' is hydrogen or C ₁ -C ₁₀ alkyl; and

n is an integer ranging from 1 to 3.

In one embodiment, R may be hydrogen.

In a specific example, R may be a linear or branched _C8 - _C20 alkyl group, and specifically may be n-octyl, tert-octyl, n-nonyl, tert-nonyl, n-decyl, tert-decyl, n-undecyl, tert-undecyl, undecyl, n-dodecyl, tert-dodecyl, n-tridecyl, tert-tridecyl, n-tetradecyl, tert-tetradecyl, n-pentadecyl or tert-pentadecyl.

In a specific example, R''' is hydrogen or C ₁ -C ₅ alkyl, specifically, hydrogen or methyl.

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

In the above compounds, M is zirconium or hafnium.

In addition, the present invention also provides a catalyst composition for preparing an ethylene polymer, wherein the ethylene polymer is selected from an ethylene homopolymer or a copolymer of ethylene and an α-olefin, and contains the metal-ligand complex according to the present invention and a cocatalyst.

According to exemplary embodiments, the co-catalyst may be a boron compound co-catalyst, an aluminum compound co-catalyst, and a mixture thereof.

According to an exemplary embodiment, the content of the co-catalyst may be 0.5 to 10000 mol relative to 1 mol of the metal-ligand complex, but is not limited thereto.

The boron compound that can be used as a co-catalyst may be a boron compound disclosed in U.S. Patent No. 5198401, specifically, may be one or a mixture of two or more selected from the 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 chemical formulas A to C,

B is a boron atom; R ²¹ is a phenyl group, and the phenyl group may be further substituted by 3 to 5 substituents selected from a fluorine atom, a C ₁ -C ₂₀ alkyl group, a C ₁ -C ₂₀ alkyl group substituted by a fluorine atom, a C ₁ -C ₂₀ alkoxy group and a C ₁ -C ₂₀ alkoxy group substituted by a fluorine atom; R ²² is a C ₅ -C ₇ aryl group, a C ₁ -C ₂₀ alkyl C ₆ -C ₂₀ aryl group or a C ₆ -C ₂₀ aryl C ₁ -C ₂₀ alkyl group, for example, a triphenylmethyl group; Z is a nitrogen or phosphorus atom; R ²³ is a C ₁ -C ₂₀ alkyl group or an anilino group substituted by two C ₁ -C ₁₀ alkyl groups together with a nitrogen atom; and q is an integer of 2 or 3.

The boron-based co-catalyst 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, borane, tris(3,4,5-trifluorophenyl)borane, tris(2,3,4-trifluorophenyl)borane, bis(pentafluorophenyl)(phenyl)borane, and the like.

The boron-based co-catalyst may be one or two or more boron compounds, whose borate anions are 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, tris(pentafluorophenyl)(phenyl)borate and tetrakis(3,5-bistrifluoromethylphenyl)borate.

The boron-based co-catalyst may be one or two or more boron compounds, whose cations are selected from triphenylmethylammonium, triethylammonium, tripropylammonium, tri(n-butyl)ammonium, N,N-dimethylammonium, N,N-diethylammonium, N,N-2,4,6-pentamethylammonium, diisopropylammonium, dicyclohexylammonium, triphenylphosphine, tri(methylphenyl)phosphine and tri(dimethylphenyl)phosphine.

Specifically, the boron-based co-catalyst may be one or two or more boron compounds, whose cations are selected from triphenylmethylammonium, triethylammonium, tripropylammonium tri(n-butyl)ammonium, N,N-dimethylaniline, N,N-diethylaniline, N,N-2,4,6-pentamethylaniline, diisopropylammonium, dicyclohexylammonium, triphenylphosphine, tri(methylphenyl)phosphine and tri(dimethylphenyl)phosphine and the borate anion is 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, tris(pentafluorophenyl)(phenyl)borate and tetrakis(3,5-bistrifluoromethylphenyl)borate.

More specifically, the boron-based co-catalyst may be one or more selected from the following groups: triphenylmethylamine tetrakis (pentafluorophenyl) borate, tetrakis (3,5-bis trifluoromethylphenyl) borate, triethylamine tetrakis (pentafluorophenyl) borate, tripropylamine tetrakis (pentafluorophenyl) borate, tri(n-butyl)amine tetrakis (pentafluorophenyl) borate, tri(n-butyl)amine tetrakis (3,5-bis trifluoromethylphenyl) borate, N,N-dimethylaniline tetrakis (pentafluorophenyl) borate, N,N-diethylaniline tetrakis (pentafluorophenyl) borate, N,N-2,4,6-pentamethyl The invention further comprises the following: the at least one of the following: 1,2-diphenylamine tetrakis(pentafluorophenyl)borate, ...

Examples of aluminum compounds that can be used as a co-catalyst in the catalyst composition according to an exemplary embodiment of the present invention include aluminoxane compounds of Formula D or E, organic aluminum compounds of Formula F, and organic aluminum alkyl oxides or organic aluminum aryloxide compounds of 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 A10R ³⁴

[Chemical formula H]

R ³³ Al(OR ³⁴ ) ₂

In chemical formulae D to H,

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

Specific examples that can be used as aluminum compounds include aluminoxane compounds such as methylaluminoxane, modified methylaluminoxane and tetraisobutyldialuminoxane; and organoaluminum compounds such as trialkylaluminum including trimethylaluminum, triethylaluminum, tripropylaluminum, triisobutylaluminum and trihexylaluminum; dialkylaluminum chlorides including dimethylaluminum 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, and alkyl alkoxyaluminum including methyldimethoxyaluminum, dimethylmethoxyaluminum, ethyldiethoxyaluminum, diethylethoxyaluminum, isobutyldibutoxyaluminum, diisobutylbutoxyaluminum, hexyldimethoxyaluminum, dihexylmethoxyaluminum and dioctylmethoxyaluminum. Preferably, aluminoxane compounds, trialkylaluminum and mixtures thereof can be used as cocatalysts. Specifically, methylaluminoxane, modified methylaluminoxane, tetraisobutyldialuminoxane, trimethylaluminum, triethylaluminum and triisobutylaluminum can be used alone or in a mixture thereof. More preferably, tetraisobutyldialuminoxane, triisobutylaluminum and a mixture thereof can be used.

Preferably, in the catalyst composition according to an exemplary embodiment of the present invention, when an aluminum compound is used as a co-catalyst, in the co-catalyst composition, the ratio between the transition metal (M) in the metal-ligand complex: the aluminum atom (Al) may preferably be in the range of 1:10 to 10000 based on a molar ratio.

Preferably, in the catalyst composition according to an exemplary embodiment of the present invention, when both an aluminum compound and a boron compound are used as co-catalysts, according to the present invention, the ratio of transition metal (M): boron atom (B): aluminum atom (Al) in the metal-ligand complex, based on a molar ratio, may be in the range of 1:0.1 to 200:10 to 1000, more preferably in the range of 1:0.5 to 100:25 to 5000.

Within the above range, the ratio of the metal-ligand complex to the co-catalyst according to the present invention has excellent catalytic activity for preparing vinyl polymers, and the ratio range varies according to the different reaction purity.

As another aspect according to an exemplary embodiment of the present invention, a method for preparing a vinyl polymer using a catalyst composition for preparing a vinyl polymer can be carried out by contacting a metal-ligand complex, a cocatalyst and ethylene or, if necessary, a comonomer in the presence of an appropriate organic solvent. In this case, the precatalyst, i.e., the metal-ligand complex, and the cocatalyst components can be injected into the reactor separately or by premixing the components, and are not limited by mixing conditions such as the introduction order, temperature, concentration, etc.

Preferred organic solvents used in the preparation method may be C3-C20 hydrocarbons, specific examples of which include n-butane, isobutane, n-pentane, n-hexane, n-heptane, n-octane, isooctane, nonane, decane, dodecane, cyclohexane, methylcyclohexane, benzene, toluene and xylene.

Specifically, when preparing ethylene homopolymer, ethylene is used alone as a monomer, and when preparing a copolymer of ethylene and α-olefin, C3 to C18 α-olefins can be used as comonomers together with ethylene. Specific examples of C3 to C18 α-olefins 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 above-mentioned C3 to C18 α-olefins can be homopolymerized with ethylene, or copolymerized with two or more olefins, and more preferably 1-ene, 1-hexene, 1-octene or 1-decene is copolymerized with ethylene.

The pressure of ethylene may be 1 to 1000 atm, and more preferably 5 to 100 atm. In addition, the polymerization reaction may be effectively carried out at 80° C. or higher, preferably at 100° C. or higher, and more preferably at 160° C. to 250° C. The temperature and pressure conditions during the polymerization may be determined in consideration of the efficiency of the polymerization reaction according to the type of reaction and the type of reactor used.

Generally, when the solution polymerization process is carried out at the above-mentioned high temperature, it is difficult to obtain a polymer having the desired physical properties because the catalyst deforms or deteriorates with the increase in temperature, thereby reducing the activity of the catalyst. However, when the catalyst composition of the present invention is used to prepare a vinyl polymer, a stable catalytic activity can be exhibited even at a higher polymerization temperature.

The ethylene-based polymer is an ethylene homopolymer or a copolymer of ethylene and an α-olefin. The copolymer of ethylene and an α-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, the density range of the linear low density polyethylene (LLDPE) prepared using C4 to C10 alpha-olefins as comonomers is 0.940 g/cc or less, and can be extended to very low density polyethylene (VLDPE) or ultra low density polyethylene (ULDPE) or olefin elastomers with a density range of 0.900 g/cc or less. In addition, when preparing the ethylene copolymer according to the present invention, hydrogen can be used as a molecular weight regulator to adjust the molecular weight, and the weight average molecular weight (Mw) of the ethylene copolymer is generally 80,000 to 500,000.

Since the catalyst composition in the present invention is present in a homogeneous form in the polymerization reactor, it is preferably applied to a solution polymerization process carried out at a temperature equal to or higher than the melting point of the polymer. However, as disclosed in U.S. Pat. No. 4,752,597, the catalyst composition can be used in a slurry polymerization or gas phase polymerization process in the form of a heterogeneous catalyst composition obtained by supporting a precatalyst and a cocatalyst as a metal-ligand complex on a porous metal oxide support.

The present invention will be described in detail below through the following examples, but the scope of the present invention is not limited thereto.

Unless otherwise stated, all ligand and catalyst synthesis experiments were performed under nitrogen atmosphere using standard Schlenk or glove box techniques, and the organic solvents used in the reactions were refluxed under the action of sodium metal and benzophenone to remove water and were distilled immediately before use. The synthesized ligands and catalysts were analyzed by ¹ H-NMR using a Bruker 400 or 500 MHz at room temperature.

Methylcyclohexane and n-heptane were used as polymerization solvents, and then The tubes are filled with molecular sieves and activated alumina and are bubbled with high purity nitrogen to fully remove moisture, oxygen and other catalyst poisons.

[Comparative Example 1] Synthesis of Precatalyst C1

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

[Example 1] Synthesis of precatalyst C2

The reaction was carried out in a glove box under a nitrogen atmosphere. Pre-catalyst C1 (1.17 g, 0.87 mmol) and toluene (40 mL) were added to a 100 mL flask, and 3-pentadecylphenol (0.53 g, 1.74 mmol) was added, and the mixture was stirred at room temperature for 2 hours, and then the solvent was removed. The mixture was dissolved in 50 mL of n-hexane, and then filtered with a filter filled with dry zeolite to remove solids. The filtered solution was vacuum dried to obtain pre-catalyst C2 (1.52 g, 91%) as a white solid.

¹ H NMR (CDCl ₃ ): 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).

[Example 2] Synthesis of precatalyst C3

Precatalyst A was prepared in the same manner as in Comparative Example 1, except that 4-methylphenol was used instead of 4-tert-octylphenol.

¹ H NMR (CDCl ₃ ): 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).

Precatalyst C3 (white solid, 1.36 g, 90%) was prepared in the same manner as Example 1, except that precatalyst A was used instead of precatalyst C1.

¹ H NMR (CDCl ₃ ): 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), 1.56-1.26( m, 52H), 1.56 (s, 4H), 1.51 (s, 18H), 1.40 (s, 18H), 0.90 (m, 6H).

[Example 3] Synthesis of precatalyst C4

Precatalyst B was prepared in the same manner as 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.

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

¹ H NMR (CDCl3): δ8.31 (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).

[Example 4] Copolymerization of ethylene and 1-octene to measure the oxygen sensitivity of the resulting transition metal compounds

10 μmol of the precatalyst C2 prepared in Example 1 was exposed to air at 22.1° C. and 31% humidity for about 1 hour, the precatalyst C2 was dissolved in 10 mL of toluene to obtain a saturated solution, and ethylene and 1-octene were copolymerized using a batch polymerization apparatus, the steps being as follows:

600mL of methylcyclohexane and 50mL of 1-octene were injected into a stainless steel reactor with a capacity of 1500mL. After being fully dried, the inside of the reactor was purged with nitrogen, and then 2mL of triisobutylaluminum 1.0M hexane solution was added to the reactor. Subsequently, the reactor temperature was heated to 100°C, and 1mL of a saturated solution of precatalyst C2 (i.e., a saturated solution of 1.0μmol precatalyst C2 in 1mL toluene) and 40μmol of triphenylmethyltetrakis (pentafluorophenyl) borate were added in sequence, and ethylene was filled into the reactor to make its pressure reach 20bar, and then ethylene was continuously supplied for polymerization. The reaction was carried out for 5 minutes, and then the recovered reaction product was dried in a vacuum oven at 40°C for 8 hours. The polymerization results are shown in Table 1.

[Example 5]

The copolymerization of ethylene and 1-octene was carried out in the same manner as in Example 4, except that the precatalyst C2 (Example 1) which was not exposed to air was used. The polymerization conditions and polymerization results are shown in Table 1.

[Comparative Example 2]

The copolymerization of ethylene and 1-octene was carried out in the same manner as in Example 4, except that precatalyst C1 (Comparative Example 1) was used instead of precatalyst C2 (Example 1). The polymerization conditions and polymerization results are shown in Table 1.

[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 air was used instead of precatalyst C2 (Example 1). The polymerization conditions and polymerization results are shown in Table 1.

[Table 1]

Table 1 shows the results of observation of the temperature change (ΔT) of the precatalyst C2 of Example 1 and the precatalyst C1 of Comparative Example 1 as catalysts in the polymerization of ethylene and 1-octene, depending on whether the precatalyst is exposed to air. From the results, it can be confirmed that the precatalyst C2 of Example 1 exhibits a constant temperature change during the polymerization process, regardless of whether it is exposed to air, while the precatalyst C1 of Comparative Example 1 exhibits a significantly reduced temperature change when exposed to air.

Specifically, it can be seen from the polymerization results in Table 1 that since the precatalyst C2 (Example 1) of the present invention has a structure in which an alkyl-substituted phenoxy leaving group, such as a pentadecyl group, is introduced, unlike the precatalyst C1 (Comparative Example 1) in which an alkyl leaving group, such as a methyl group, is introduced, the precatalyst C2 is relatively less sensitive to impurities such as oxygen and moisture in the air, resulting in a decrease in activity, that is, relatively fewer impurities that may affect the reaction process, resulting in excellent stability of the catalyst, which may be advantageous in commercial plant applications.

As described above, it can be confirmed that the tolerance of the catalyst to impurities such as oxygen and moisture as well as the stability and activity are significantly changed due to the structure of the polymerization catalyst.

[Examples 6 to 8 and Comparative Example 4] Copolymerization of ethylene and 1-octene at high temperature by continuous solution polymerization

The copolymerization of ethylene and 1-octene was carried out in a temperature-controlled continuous polymerization reactor equipped with a mechanical stirrer.

Precatalysts C2, C3, C4 and C1 prepared in Examples 1, 2 and 3 and Comparative Example 1 were used as catalysts, n-heptane was used as solvent, and modified methylaluminoxane (20wt%, Nouryon) was used as a cocatalyst. The amount of catalyst is shown in Table 2. Each catalyst was dissolved in toluene at a concentration of 0.2 g/L and then injected to polymerize with 1-octene as a comonomer. When only one polymer was polymerized under each reaction condition, the conversion rate of the reactor was estimated by the reaction conditions 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 the 1-octene content. Conditions and results are shown in Table 2.

Melt Index (MI): The melt index (MI) was measured using the ASTM D1238 analysis method at 190°C and a load of 2.16 kg.

Density: Density was measured by ASTM D792 analysis method.

[Table 2]

It can be seen from the polymerization results in Table 2 that in Examples 6, 7 and 8 using the precatalyst C2 (Example 1), precatalyst C3 (Example 2) and precatalyst C4 (Example 3) of the present invention as polymerization catalysts, compared with Comparative Example 4 (Comparative Example 1) using the known precatalyst C1, although the amount of catalyst is reduced at a high temperature of 220°C, the excellent activity is still maintained, and the catalytic activity is significantly improved compared with the existing catalysts.

Therefore, it can be understood that the metal-ligand complex according to the present invention can effectively prepare high molecular weight copolymers of ethylene and α-olefins, and due to the structural characteristics of the introduction of specific functional groups, it has significantly excellent catalytic activity and stability even at high temperatures.

Claims (11)

1. A metal-ligand complex represented by the following chemical formula 1:

[ chemical formula 1]

In the chemical formula 1, the chemical formula is shown in the drawing,

M is a transition metal of group 4 of the periodic Table;

Ar ₁ and Ar ₂ are each independently C ₆-C₂₀ aryl, and the aryl groups described in Ar ₁ and Ar ₂ may be further substituted with C ₁-C₂₀ alkyl;

R ₁ to R ₄ are each independently C ₁-C₂₀ alkyl, C ₆-C₂₀ aryl or C ₆-C₂₀ aryl-C ₁-C₂₀ alkyl;

R ₅ and R ₆ are each independently C ₁-C₂₀ alkyl;

R ₇ and R ₈ are each independently halogen or C ₁-C₂₀ alkyl;

a, b, c, d, e and f are each independently integers from 0 to 4; and

M is an integer in the range of 2 to 5.

2. The metal-ligand complex of claim 1, wherein

Ar ₁ and Ar ₂ are each independently C ₆-C₂₀ aryl or C ₁-C₂₀ alkyl C ₆-C₂₀ aryl;

R ₁ to R ₄ are each independently C ₁-C₂₀ alkyl;

R ₇ and R ₈ are each independently halogen or C ₁-C₂₀ alkyl;

a, b, c, d, e and f are each independently integers from 1 to 3; and

M is an integer ranging from 3 to 5.

3. The metal-ligand complex of claim 1, wherein the metal-ligand complex is represented by chemical formula 2-1 or chemical formula 2-2 as follows:

[ chemical formula 2-1]

[ Chemical formula 2-2]

In chemical formulas 2-1 and 2-2,

M is titanium, zirconium or hafnium;

Ar ₁ and Ar ₂ are each independently C ₆-C₂₀ aryl or C ₁-C₂₀ alkyl C ₆-C₂₀ aryl;

R ₁ to R ₄ are each independently C ₁-C₂₀ alkyl;

R ₅ and R ₆ are each independently C ₁-C₂₀ alkyl;

x ₁ and X ₂ are each independently halogen;

R 'and R' are each independently hydrogen or C ₁-C₂₀ alkyl; and

M is an integer ranging from 3 to 5.

4. A metal-ligand complex according to claim 3, wherein

Ar ₁ and Ar ₂ are each independently C ₆-C₁₂ or C ₁-C₂₀ alkyl C ₆-C₁₂ aryl;

R ₁ to R ₄ are each independently C ₁-C₁₀ alkyl;

R ₅ and R ₆ are each independently C ₁-C₁₀ alkyl; and

R 'and R' are each independently hydrogen or C ₁-C₁₀ alkyl.

5. The metal-ligand complex of claim 1, wherein the metal-ligand complex is formula 3-1 or formula 3-2 as shown below:

[ chemical formula 3-1]

[ Chemical formula 3-2]

In chemical formulas 3-1 and 3-2,

M is zirconium or hafnium;

ar is C ₆-C₁₂ aryl or C ₁-C₂₀ alkyl C ₆-C₁₂ aryl;

R ₁₁ is C ₁-C₅ alkyl;

r ₁₂ is C ₁-C₁₀ alkyl;

x ₁₁ is fluorine or chlorine;

r' "is hydrogen or C ₁-C₁₀ alkyl; and

N is an integer in the range of 1 to 3.

6. The metal-ligand complex of claim 1, wherein the metal-ligand complex is formula 4-1 or formula 4-2 as shown below:

[ chemical formula 4-1]

[ Chemical formula 4-2]

In chemical formulas 4-1 and 4-2,

M is zirconium or hafnium;

R is hydrogen or C ₈-C₂₀ alkyl;

r ₁₂ is C ₁-C₁₀ alkyl;

x ₁₁ is fluorine or chlorine;

r' "is hydrogen or C ₁-C₁₀ alkyl; and

N is an integer in the range of 1 to 3.

7. A catalyst composition for preparing a vinyl polymer comprising:

the metal-ligand complex of any one of claims 1 to 6; and

And (3) a cocatalyst.

8. The catalyst composition of claim 7, wherein the promoter is an aluminum compound promoter, a boron compound promoter, or a mixture thereof.

9. The catalyst composition of claim 7, wherein the cocatalyst is used in an amount of 0.5 to 10000mol relative to 1mol of the metal-ligand complex.

10. A process for producing a vinyl polymer, which comprises polymerizing ethylene or ethylene and an α -olefin in the presence of the catalyst composition for producing a vinyl polymer according to claim 7 to obtain a vinyl polymer.

11. The process of claim 10, wherein the polymerization is carried out at 100 ℃ to 250 ℃.