CN113614124B

CN113614124B - Composite supported metallocene catalyst and method for preparing polyethylene copolymer using the same

Info

Publication number: CN113614124B
Application number: CN202080023435.1A
Authority: CN
Inventors: 金葡殷; 李承美; 权眩志; 李琪树; 权龙雨
Original assignee: LG Chem Ltd
Current assignee: LG Chem Ltd
Priority date: 2019-11-20
Filing date: 2020-11-20
Publication date: 2023-06-20
Anticipated expiration: 2040-11-20
Also published as: KR102564398B1; CN113614124A; KR20210061954A

Abstract

The present invention provides a composite supported metallocene catalyst which can be used to prepare polyethylene copolymers exhibiting excellent process stability and high polymerization activity in ethylene polymerization and excellent mechanical properties by high comonomer incorporation (comonomer incorporation).

Description

Composite supported metallocene catalyst and method for preparing polyethylene copolymer using the same

Technical Field

Cross Reference to Related Applications

The present application claims the benefits of korean patent application No. 10-2019-0149717, filed on 11 months 20 in 2019, and korean patent application No. 10-2020-0155726, filed on 11 months 19 in 2020, the disclosures of which are incorporated herein by reference in their entirety.

The invention relates to a composite supported metallocene catalyst and a method for preparing a polyethylene copolymer by using the same.

Background

Olefin polymerization catalyst systems can be classified into Ziegler-Natta catalysts and metallocene catalysts, and these high activity catalyst systems have been developed based on their characteristics.

Ziegler-Natta catalysts have been widely used in commercial processes since their development in the 1950 s. However, since the Ziegler-Natta catalyst is a multi-active site catalyst mixed with a plurality of active sites, it is characterized in that the resulting polymer has a broad molecular weight distribution. Further, since the composition distribution of the comonomer is not uniform, there is a problem in that it is difficult to obtain desired physical properties.

Meanwhile, the metallocene catalyst includes a main catalyst having a transition metal compound as a main component and an organometallic compound cocatalyst having aluminum as a main component. Such catalysts are single active site catalysts (which are homogeneous complex catalysts) and provide polymers with narrow molecular weight distribution and uniform comonomer composition distribution due to the single active site nature. The stereoregularity, copolymerization characteristics, molecular weight, crystallinity, etc. of the resulting polymer can be controlled by changing the ligand structure and polymerization conditions of the catalyst.

Recently, due to the change in environmental awareness, attempts have been made to reduce the generation of Volatile Organic Compounds (VOCs) in many products. However, ziegler-Natta catalysts (Z/N) which are mainly used for preparing polyethylene have the problem of generating a large amount of VOC. In particular, various commercially available polyethylene products are mainly prepared using Ziegler-Natta catalysts, but recently, the conversion to products prepared by metallocene catalysts having low odor and low dissolution characteristics has been accelerated.

Meanwhile, linear Low Density Polyethylene (LLDPE) is produced by copolymerizing ethylene and α -olefin at low pressure using a polymerization catalyst. However, there is a problem in that it is difficult to improve the impact strength of the film because of the low comonomer incorporation property of the conventional catalyst itself, and the comonomer concentration in the high molecular weight portion of the polyethylene is low. In particular, when the concentration of a comonomer such as an α -olefin increases during copolymerization, there is a problem in that the morphology of the produced polymer becomes poor. In addition, the lower the density of LLDPE, the higher the impact strength of the film, but fouling often occurs during the production of low density polyethylene, deteriorating the process stability.

Therefore, there is a need for a catalyst for preparing low density polyethylene which is capable of producing a low density polyethylene resin product having excellent morphology and excellent dart impact strength, while having excellent comonomer incorporation properties and stable process during polyethylene production.

Disclosure of Invention

Technical problem

In the present invention, there is provided a composite supported metallocene catalyst which can be used to prepare a polyethylene copolymer having excellent mechanical properties due to excellent comonomer incorporation properties while maintaining high catalytic activity and stable process in ethylene polymerization.

In addition, a method for preparing a polyethylene copolymer using the composite supported metallocene catalyst is provided.

Technical proposal

In the present invention, there is provided a composite supported metallocene catalyst comprising at least one first metallocene compound selected from the group consisting of compounds represented by the following chemical formula 1; at least one second metallocene compound selected from the group consisting of compounds represented by the following chemical formula 2; and a support supporting the first and second metallocene compounds:

[ chemical formula 1]

(Cp ¹ R ^a ) _n (Cp ² R ^b )M ¹ Q ¹ _3-n

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

M ¹ is a group 4 transition metal;

Cp ¹ and Cp ² Are identical to or different from each other and are each independently any one selected from the group consisting of cyclopentadienyl, indenyl, 4,5,6, 7-tetrahydro-1-indenyl and fluorenyl, each of which has no substituent or is substituted with C _1-20 A hydrocarbon group;

R ^a and R is ^b Are identical or different from each other and are each independently hydrogen, C _1-20 Alkyl, C _1-20 Alkoxy, C _2-20 Alkoxyalkyl, C _6-20 Aryl, C _6-20 Aryloxy, C _2-20 Alkenyl, C _7-40 Alkylaryl, C _7-40 Arylalkyl, C ₈ - ₄₀ Arylalkenyl or C _2-10 Alkynyl, provided that R ^a And R is ^b At least one of which is not hydrogen;

Q ¹ each independently is halogen, C _1-20 Alkyl, C _2-20 Alkenyl, C _7-40 Alkylaryl, C _7-40 Arylalkyl, C _6-20 Aryl, C with or without substituents _1-20 Alkylene (alkylidene), amino with or without substituent, C _2-20 Alkoxyalkyl, C _2-20 Alkylalkoxy or C _7-40 An arylalkoxy group; and is also provided with

n is 1 or 0;

[ chemical formula 2]

In the chemical formula 2, the chemical formula is shown in the drawing,

M ² is a group 4 transition metal;

a is carbon (C), silicon (Si) or germanium (Ge);

X ¹ and X ² Are identical or different from one another and are each independently halogen or C _1-20 An alkyl group;

L ¹ and L ² Are identical or different from each other and are each independently C _1-20 An alkylene group;

D ¹ and D ² Is oxygen;

R ¹ and R is ² Are identical or different from each other and are each independently C _1-20 Alkyl, C _2-20 Alkenyl, C _6-20 Aryl, C ₇ - ₄₀ Alkylaryl or C _7-40 An arylalkyl group;

R ³ and R is ⁴ Are identical or different from each other and are each independently C _1-20 An alkyl group.

In the present invention, there is also provided a process for preparing a polyethylene copolymer comprising the step of copolymerizing ethylene and an α -olefin in the presence of the above-mentioned composite supported metallocene catalyst.

In the present invention, there is also provided a polyethylene copolymer obtained by the above method.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

Singular is also intended to include plural unless the context clearly indicates otherwise.

In the present disclosure, the terms "comprises," "comprising," or "having" are intended to specify the presence of stated features, integers, steps, components, or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof.

The terms "about" or "substantially" as used throughout the specification are intended to have a meaning approaching the value or range specified by the permissible error and to prevent any unreasonable third party from illegally or unfair use of the exact or absolute values disclosed for the understanding of the present invention.

Unless otherwise indicated herein, "copolymerization" refers to block, random, graft, or alternating copolymerization, and "copolymer" refers to block, random, graft, or alternating copolymer.

Also, as used herein, when referring to one layer or element being formed "on" another layer or element, the layer or element may be formed directly on the other layer or element, or other layers or elements may be additionally formed between layers, on the object, or on the substrate.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example and will herein be described in detail. It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed, and it is to be understood that the invention includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Hereinafter, the present invention will be described in detail.

According to an embodiment of the present invention, there is provided a composite supported metallocene catalyst comprising at least one first metallocene compound selected from the group consisting of compounds represented by the following chemical formula 1; at least one second metallocene compound selected from the group consisting of compounds represented by the following chemical formula 2; and a support supporting the first and second metallocene compounds:

[ chemical formula 1]

(Cp ¹ R ^a ) _n (Cp ² R ^b )M ¹ Q ¹ _3-n

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

M ¹ is a group 4 transition metal;

Q ¹ each independently is halogen, C _1-20 Alkyl, C _2-20 Alkenyl, C _7-40 Alkylaryl, C _7-40 Arylalkyl, C _6-20 Aryl, C with or without substituents _1-20 Alkylene, amino with or without substituents, C _2-20 Alkoxyalkyl, C _2-20 Alkylalkoxy or C _7-40 An arylalkoxy group; and is also provided with

n is 1 or 0;

[ chemical formula 2]

In the chemical formula 2, the chemical formula is shown in the drawing,

M ² is a group 4 transition metal;

a is carbon (C), silicon (Si) or germanium (Ge);

D ¹ and D ² Is oxygen;

Unless otherwise indicated herein, the following terms may be defined as follows.

The hydrocarbyl group is a monovalent functional group that removes hydrogen from the hydrocarbon and may include alkyl, alkenyl, alkynyl, aryl, aralkyl, aralkenyl, aralkynyl, alkylaryl, alkenylaryl, alkynylaryl, and the like. C (C) _1-30 The hydrocarbon radical may be C _1-20 Or C _1-10 A hydrocarbon group. For example, the hydrocarbyl group may be a straight chain, branched or cyclic alkyl group. More specifically, C _1-30 The hydrocarbyl group may be a straight, branched or cyclic alkyl group such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-pentyl, n-hexyl, n-heptyl and cyclohexyl; or aryl, such as phenyl, biphenyl, naphthyl, anthracenyl, phenanthrenyl, or fluorenyl. Furthermore, it may be alkylaryl groups such as methylphenyl, ethylphenyl, methylbiphenyl and methylnaphthyl, or arylalkyl groups such as phenylmethyl, phenylethyl, biphenylmethyl and naphthylmethyl. It may also be alkenyl, such as allyl, vinyl, propenyl, butenyl, and pentenyl.

Hydrocarbyloxy (hydrocarbyloxy group) is a functional group in which a hydrocarbon group is bonded to oxygen. Tool withIn the body, C _1-30 Hydrocarbyloxy groups may be C _1-20 Or C _1-10 Hydrocarbyloxy groups. For example, hydrocarbyloxy groups may be straight, branched or cyclic alkoxy groups. More specifically, C _1-30 Hydrocarbyloxy groups may be straight, branched or cyclic alkoxy groups such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, n-pentoxy, n-hexoxy, n-heptoxy and cyclohexyloxy; or aryloxy groups such as phenoxy and naphthoxy.

Hydrocarbyloxy hydrocarbyl (hydrocarbyloxyhydrocarbyl group) is a functional group in which at least one hydrogen of the hydrocarbyl group is replaced with at least one hydrocarbyloxy group. Specifically, C _2-30 The hydrocarbyloxyhydrocarbyl group may be C _2-20 Or C _2-15 Hydrocarbyloxyhydrocarbyl radicals. For example, the hydrocarbyloxyhydrocarbyl group may be a linear, branched, or cyclic hydrocarbyloxyhydrocarbyl group. More specifically, C _2-30 The hydrocarbyloxyhydrocarbyl group may be an alkoxyalkyl group such as methoxymethyl, methoxyethyl, ethoxymethyl, isopropoxymethyl, isopropoxyethyl, tert-butoxymethyl, tert-butoxyethyl and tert-butoxyhexyl; or an aryloxyalkyl group such as phenoxyhexyl.

Hydrocarbyl (oxy) silyl is-SiH ₃ 1 to 3 hydrogen groups substituted with 1 to 3 hydrocarbyl or hydrocarbyloxy groups. Specifically, C _1-30 The hydrocarbyl (oxy) silyl group may be C _1-20 、C _1-15 、C _1-10 Or C _1-5 Hydrocarbyl (oxy) silyl groups. More specifically, C _1-30 The hydrocarbyl (oxy) silyl group may be an alkylsilyl group, such as a methylsilyl group, a dimethylsilyl group, a trimethylsilyl group, a dimethylethylsilyl group, a diethylmethylsilyl group, or a dimethylpropylsilyl group; alkoxysilyl groups such as methoxysilyl, dimethoxysilyl, trimethoxysilyl or dimethoxyethoxysilyl; or an alkoxyalkylsilyl group such as a methoxydimethylsilyl group, a diethoxymethylsilyl group or a dimethoxypropylsilyl group.

C _1-20 Silyl hydrocarbyl is hydrocarbyl with at least one hydrogen being replaced bySilyl substituted functional groups. The silyl group may be-SiH ₃ Or a hydrocarbyl (oxy) silyl group. Specifically, C _1-20 Silyl hydrocarbyl groups may be C _1-15 Or C _1-10 Silyl hydrocarbyl groups. More specifically, C _1-20 The silylhydrocarbyl group may be a silylalkyl group, e.g., -CH ₂ -SiH ₃ The method comprises the steps of carrying out a first treatment on the surface of the Alkylsilylalkyl groups such as methylsilylmethyl, methylsilylethyl, dimethylsilylmethyl, trimethylsilylmethyl, dimethylethylsilylmethyl, diethylmethylsilylmethyl or dimethylpropylsilylmethyl; or an alkoxysilylalkyl group such as dimethylethoxysilylpropyl.

Halogen may be fluorine (F), chlorine (Cl), bromine (Br) or iodine (I).

C _1-20 The alkyl group may be a linear, branched or cyclic alkyl group. Specifically, C _1-20 The alkyl group may be C _1-20 A linear alkyl group; c (C) _1-15 A linear alkyl group; c (C) _1-5 A linear alkyl group; c (C) _3-20 Branched or cyclic alkyl; c (C) _3-15 Branched or cyclic alkyl; or C _3-10 Branched or cyclic alkyl groups. More specifically, C _1-20 The alkyl group may be methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, pentyl, hexyl, heptyl, octyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, or the like, but is not limited thereto.

C _2-20 Alkenyl groups may be straight chain, branched or cyclic alkenyl groups. Specifically, it may be allyl, vinyl, propenyl, butenyl, pentenyl, or the like, but is not limited thereto.

C _1-20 The alkoxy group may be methoxy, ethoxy, isopropoxy, n-butoxy, tert-butoxy, pentyloxy, cyclohexyloxy or the like, but is not limited thereto.

C _2-20 Alkoxyalkyl is a functional group in which at least one hydrogen of the above alkyl group is substituted with an alkoxy group, and it may be an alkoxyalkyl group such as methoxymethyl, methoxyethyl, ethoxymethyl, isopropoxymethyl, isopropoxyethyl, isopropoxypropyl,Isopropyl hexyl, t-butoxymethyl, t-butoxyethyl, t-butoxypropyl, t-butoxyhexyl, and the like, but is not limited thereto.

C _6-20 The aryloxy group may be a phenoxy group, a diphenoxy group, a naphthoxy group, or the like, but is not limited thereto.

C _7-40 The aryloxyalkyl group is a functional group in which at least one hydrogen of the above alkyl group is substituted with an aryloxy group, and it may be an aryloxyalkyl group such as phenoxymethyl, phenoxyethyl, phenoxyhexyl or the like, but is not limited thereto.

C _1-20 Alkylsilyl or C _1-20 Alkoxysilyl groups are-SiH ₃ A functional group in which 1 to 3 hydrogens are substituted with 1 to 3 of the above alkyl groups or alkoxy groups, and which may be an alkylsilyl group, such as a methylsilyl group, a dimethylsilyl group, a trimethylsilyl group, a dimethylethylsilyl group, a diethylmethylsilyl group, or a dimethylpropylsilyl group; alkoxysilyl groups such as methoxysilyl, dimethoxysilyl, trimethoxysilyl or dimethoxyethoxysilyl; or an alkoxyalkylsilyl group such as a methoxydimethylsilyl group, a diethoxymethylsilyl group or a dimethoxypropylsilyl group; etc., but is not limited thereto.

C _1-20 Silylalkyl is a functional group in which at least one hydrogen of the alkyl is replaced with a silyl group, and may be-CH ₂ -SiH ₃ Methyl silylmethyl, dimethyl ethoxysilylpropyl, etc., but is not limited thereto.

In addition, C _1-20 Alkylene or alkylidene (alkylidene) is the same as the above alkyl except that it is a divalent substituent, and it may be methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, cyclopropylene, cyclobutylene, cyclopentylene, cyclohexylene, cycloheptylene, cyclooctylene, or the like, but is not limited thereto.

C _6-20 Aryl groups may be monocyclic, bicyclic or tricyclic aromatic hydrocarbons. For example, C _6-20 Aryl may be phenyl, biphenyl, naphthaleneA group, an anthryl group, a phenanthryl group, a fluorenyl group, or the like, but is not limited thereto.

C _7-20 Alkylaryl may refer to a substituent of an aromatic ring in which at least one hydrogen is substituted with an alkyl group as described above. For example, C _7-20 The alkylaryl group may be methylphenyl, ethylphenyl, methylbiphenyl, methylnaphthyl, or the like, but is not limited thereto.

C _7-20 Arylalkyl may refer to a substituent of an alkyl group in which at least one hydrogen is replaced with an aryl group as described above. For example, C _7-20 The arylalkyl group may be phenylmethyl, phenylethyl, biphenylmethyl, naphthylmethyl, or the like, but is not limited thereto.

In addition, C _6-20 Arylene and aryliden are the same as the above aryl groups except that they are divalent substituents and they may be phenylene, biphenylene, naphthylene, anthrylene, phenanthrylene, fluorenylene, or the like, but are not limited thereto.

The group 4 transition metal may be titanium (Ti), zirconium (Zr), hafnium (Hf) or

(Rf), and may be titanium (Ti), zirconium (Zr) or hafnium (Hf) in particular. More specifically, it may be zirconium (Zr) or hafnium (Hf), but the present invention is not limited thereto.

Further, the group 13 element may be boron (B), aluminum (Al), gallium (Ga), indium (In), or thallium (Tl), and In particular may be boron (B) or aluminum (Al), but the present invention is not limited thereto.

The above substituents may be optionally substituted with one or more substituents selected from the group consisting of: a hydroxyl group; halogen; alkyl or alkenyl, aryl, alkoxy; an alkyl or alkenyl group containing at least one heteroatom from groups 14 to 16, an aryl group, an alkoxy group; a silyl group; alkylsilyl or alkoxysilyl groups; phosphino (phosphine group); phosphide groups; a sulfonic acid group; and a sulfone group.

Meanwhile, the composite supported metallocene catalyst of the present invention is prepared by the following process: the composite loading of the first metallocene compound capable of enhancing low molecular weight copolymerization and the second metallocene compound capable of increasing high molecular weight characteristics during ethylene polymerization exhibits excellent process stability and high activity for ethylene polymerization. In addition, by improving the copolymerization of ethylene (comonomer incorporation), it can be used to prepare polyethylene copolymers having excellent mechanical properties.

In particular, in the composite supported metallocene catalyst of the embodiment, the first metallocene compound represented by chemical formula 1 contributes to the production of a low molecular weight linear copolymer, and the second metallocene compound represented by chemical formula 2 contributes to the production of a high molecular weight linear copolymer. The composite supported metallocene catalyst can exhibit excellent supporting performance, catalytic activity and high comonomer incorporation by using a first metallocene compound having a low comonomer incorporation and a second metallocene compound having a high comonomer incorporation as a composite catalyst. In particular, when low density polyethylene is produced in a slurry process in the presence of a composite supported metallocene catalyst, the stability in the process is improved, so that the fouling problem occurring in the prior art can be prevented. In addition, by using a composite supported metallocene catalyst, polyethylene having excellent physical properties, such as low density polyethylene, can be provided.

Specifically, the first metallocene compound is characterized by having a form in which cyclopentadienyl, indenyl, or fluorenyl ligands are bridged with a group 4 transition metal, and these ligands are at least one of substituents other than hydrogen in formula 1. For example, the cyclopentadienyl, indenyl or fluorenyl ligands may be unsubstituted or substituted with C _1-20 Hydrocarbon or C _1-12 A hydrocarbon group. In particular, the cyclopentadienyl, indenyl or fluorenyl ligands are substituted with at least one alkyl or alkenyl, alkoxyalkyl or arylalkyl group, etc. Then, by using a cyclopentadienyl, indenyl or fluorenyl ligand having the above specific structure, catalytic activity and copolymerization properties can be improved, the molecular structure of the resulting polymer can be improved, and reactivity can be well controlled.

In chemical formula 1, M ¹ Zirconium (Zr) or hafnium (Hf) is possible, preferably zirconium (Zr).

Also, in chemical formula 1, cp ¹ And Cp ² Each may be cyclopentadienyl, indenyl or fluorenyl. Preferably Cp ¹ And Cp ² At least one of which is cyclopentadienyl or indenyl. More preferably Cp ¹ And Cp ² May be cyclopentadienyl.

Cp ¹ And Cp ² May have no substituent or at least one C _1-20 A hydrocarbon group. For example Cp ¹ And Cp ² Can be substituted with C _1-10 Hydrocarbon radicals, C _1-10 Hydrocarbyloxy or C _1-10 One or more of the hydrocarbyloxyl hydrocarbon groups. Specifically, cp ¹ And Cp ² May be substituted with one or more of methyl, ethyl, n-propyl, n-butyl, t-butyl, n-pentyl, n-hexyl, t-butoxyhexyl, butenyl, phenylpropyl, phenylhexyl, or phenyl.

More specifically, in the first metallocene compound, cp ¹ And Cp ² May be the same or different from each other. Preferably Cp ¹ And Cp ² May be identical to each other and include identical substituents to form a symmetrical structure.

In addition, R ^a And R is ^b Each is hydrogen, C _1-6 Straight-chain or branched alkyl, C _2-6 Alkynyl, C _1-6 Alkoxy substituted C _1-6 Alkyl, C _6-12 Aryl substituted C _1-6 Alkyl or C _6-12 Aryl, provided that R ^a And R is ^b Is not hydrogen. In particular, R ^a And R is ^b May be the same as or different from each other, e.g., R ^a And R is ^b May be identical to each other and may have a symmetrical structure in formula 1. For example, R ^a And R is ^b Each may be hydrogen, methyl (Me), ethyl (Et), n-propyl (n-Pr), isopropyl (i-Pr), n-butyl (n-Bu), t-butyl (t-Bu), n-pentyl (n-Pt), n-hexyl (n-Hex), t-butoxy (t-Bu-O) hexyl, butenyl, phenylpropyl, phenylhexyl, or phenyl (Ph).

In chemical formula 1, each Q1 may be halogen, such as chlorine.

In chemical formula 1, n is 1 or 0, preferably n is 1.

Meanwhile, the first metallocene compound may be represented by any one of the following chemical formulas 1-1 to 1-5.

[ chemical formula 1-1]

[ chemical formulas 1-2]

[ chemical formulas 1-3]

[ chemical formulas 1-4]

[ chemical formulas 1-5]

In chemical formulas 1-1 to 1-5,

M ¹ and Q ¹ As defined in the chemical formula 1,

R 'and R' are identical or different from each other and each independently represent hydrogen, C _1-20 Alkyl, C _1-20 Alkoxy, C _2-20 Alkoxyalkyl, C _6-20 Aryl, C _6-20 Aryloxy, C _2-20 Alkenyl, C _7-40 Alkylaryl, C _7-40 Arylalkyl, C _8-40 Arylalkenyl or C _2-10 Alkynyl, provided that at least one of R' and R "is not hydrogen;

each m1 is independently an integer from 1 to 8;

each m2 is independently an integer from 1 to 6.

More preferably, the first metallocene compound may be represented by chemical formula 1-1.

In chemical formulas 1-1 to 1-5, R 'and R' are each hydrogen, C _1-6 Straight-chain or branched alkyl, C _2-6 Alkynyl, C _1-6 Alkoxy substituted C _1-6 Alkyl, C _6-12 Aryl substituted C _1-6 Alkyl, or C _6-12 Aryl, provided that at least one of R 'and R' is not hydrogen. Preferably, at least one of R 'and R' is methyl (Me), ethyl (Et), n-propyl (n-Pr), isopropyl (i-Pr), n-butyl (n-Bu), t-butyl (t-Bu), n-pentyl (n-Pt), n-hexyl (n-Hex), t-butoxy (t-Bu-O) hexyl, butenyl, phenylpropyl, phenylhexyl or phenyl (Ph), the remainder being hydrogen.

In addition, in the chemical formulas 1-1 to 1-5, m1 and m2 are each an integer of 1 to 4, preferably 1 or 2, respectively.

In addition, the first metallocene compound may be represented by one of the following structural formulas.

The first metallocene compounds represented by the above structural formula can be synthesized by known reactions, and more detailed synthesis methods can be understood with reference to examples.

Meanwhile, the composite supported metallocene catalyst of the present invention is characterized in that it comprises a second metallocene compound represented by chemical formula 2 and the above-mentioned first metallocene compound.

Specifically, the second metallocene compound is characterized by having a form in which two indenyl ligands are bonded to each other via a group 4 transition metal bridge and a carbon or silicon bridge, and hydrogens at the 2-and 4-positions of the indenyl ligands are each substituted with a methyl group and an aryl group substituted with a hydrocarbyloxyhydrocarbyl group, respectively. In particular, it is characterized in that the two indenyl ligands having this particular substituent are contained in the same symmetrical structure with each other. Then, a bisindenyl ligand having a specific structure and substituent is applied, thereby improving process stability by reducing the ratio of ethylene and comonomer in the reaction system with high copolymerizability, and copolymerizing (comonomer incorporation amount) due to high comonomer in the polymer region of the resulting polyethylene molecular weight distribution map. Thus, a linear low density polyethylene product having excellent morphology and high impact strength can be produced.

In chemical formula 2, M ² Zirconium (Zr) or hafnium (Hf) is possible, preferably zirconium (Zr).

Also, in chemical formula 2, a may be silicon (Si).

In chemical formula 2, X ¹ And X ² Each may be halogen, in particular chlorine.

In addition, in chemical formula 2, L ¹ And L ² May each be C _1-3 Alkylene groups, and in particular may be methylene, ethylene or propylene.

In chemical formula 2, D ¹ And D ² Is oxygen (O).

In chemical formula 2, R ¹ And R is ² Each may be C _1-6 Straight-chain or branched alkyl, or C _6-12 Aryl groups. For example, R ¹ And R is ² May be identical to each other, and may each be methyl (Me), ethyl (Et), n-propyl (n-Pr), isopropyl (i-Pr), n-butyl (n-Bu), t-butyl (t-Bu), or phenyl (Ph).

Also, in chemical formula 2, R ³ And R is ⁴ Can each independently be a straight chain or branched chain C _1-6 An alkyl group. Specifically, R ³ And R is ⁴ Can be identical to one another and can each be straight-chain C _1-6 An alkyl group. For example, R ³ And R is ⁴ Each may be methyl (Me), ethyl (Et), n-propyl (n-Pr), n-butyl (n-Bu), n-pentyl (n-Pt), or n-hexyl (n-Hex).

Meanwhile, the second metallocene compound may be represented by the following chemical formula 2-1.

[ chemical formula 2-1]

In chemical formula 2-1, M ² 、A、X ¹ 、X ² 、R ¹ 、R ² 、R ³ And R is ⁴ The same definition as in chemical formula 2.

Specifically, the second metallocene compound may be represented by one of the following structural formulas.

/>

The second metallocene compounds represented by the above structural formula can be synthesized by known reactions, and more detailed synthesis methods can be understood with reference to examples.

Meanwhile, in the preparation method of the metallocene compound, the composite supported catalyst or the catalyst composition of the present invention, the equivalent (eq) means molar equivalent (eq/mol).

In particular, in the composite supported metallocene catalyst of the present invention, the first metallocene compound may be represented by any one of the following chemical formulas 1-1 to 1-5, and the second metallocene compound may be represented by the following chemical formula 2-1:

[ chemical formula 1-1]

[ chemical formulas 1-2]

[ chemical formulas 1-3]

[ chemical formulas 1-4]

[ chemical formulas 1-5]

In chemical formulas 1-1 to 1-5,

M ¹ and Q ¹ As defined in the chemical formula 1,

each m1 is independently an integer from 1 to 8;

each m2 is independently an integer from 1 to 6,

[ chemical formula 2-1]

In addition, the composite supported metallocene catalyst of the present invention may have a specific structure and substituent. Specifically, in chemical formulas 1-1 to 1-5, M ¹ Is Zr; q (Q) ¹ All are Cl; and at least one of R 'and R' is methyl (Me), ethyl (Et), n-propyl (n-Pr), isopropyl (i-Pr), n-butyl (n-Bu), t-butyl (t-Bu), n-pentyl (n-Pt), n-hexyl (n-Hex), t-butoxy (t-Bu-O) hexyl, butenyl, phenylpropyl, phenylhexyl, or phenyl (Ph), and the remainder of R 'and R' is hydrogen. Also, in the chemical formula2-1, M ² Is Zr; x is X ¹ And X ² Is Cl; r is R ¹ And R is ² Identical to each other and selected from methyl (Me), ethyl (Et), n-propyl (n-Pr), isopropyl (i-Pr), n-butyl (n-Bu), t-butyl (t-Bu) or phenyl (Ph); r is R ³ And R is ⁴ Are identical to each other and are selected from methyl (Me), ethyl (Et), n-propyl (n-Pr), n-butyl (n-Bu), n-pentyl (n-Pt) or n-hexyl (n-Hex).

In the present invention, the first metallocene compound and the second metallocene compound may be meso isomers, racemic isomers, or a mixture thereof.

In the present invention, "racemic form", "racemate" or "racemic isomer" means the same substituents on both cyclopentadienyl moieties relative to the inclusion of a moiety represented by M in chemical formula 1 or 2 ¹ Or M ² The plane of the transition metal (e.g., zirconium (Zr) or hafnium (Hf)) and the form in which the centers of the cyclopentadienyl moieties are located on opposite sides.

In addition, "meso form" or "meso isomer" refers to stereoisomers of the above racemates wherein the same substituents on the two cyclopentadienyl moieties are relative to the inclusion of a substituent represented by M in chemical formula 1 or 2 ¹ Or M ² The plane of the transition metal (e.g., zirconium (Zr) or hafnium (Hf)) is shown with the center of the cyclopentadienyl moiety on the same side.

Meanwhile, in the composite supported metallocene catalyst of the present invention, the first metallocene compound and the second metallocene compound may be supported at a molar ratio of about 0.3:1 to about 4:1. When the first and second metallocene compounds are contained in the above molar ratio, excellent loading properties, catalytic activity, and high comonomer incorporation can be exhibited. In particular, when low density polyethylene is produced in a slurry process in the presence of a composite supported metallocene catalyst, the stability in the process is improved, so that the fouling problem occurring in the prior art can be prevented. For example, when the loading ratio of the first metallocene compound and the second metallocene compound exceeds about 4:1, only the first metallocene compound plays a dominant role and the copolymerizability is reduced, and thus it may be difficult to produce low-density polyethylene. In addition, when the loading ratio is less than about 0.3:1, only the second metallocene compound plays a dominant role, and it may be difficult to obtain the resulting polymer of the desired molecular structure.

In particular, the composite supported metallocene catalyst supported by the first metallocene compound and the second metallocene compound in a molar ratio of about 0.5:1 to about 4:1, or about 1:1 to about 2:1 exhibits high activity and high comonomer incorporation in ethylene polymerization, and is preferably used for producing polyethylene having excellent mechanical properties.

That is, the composite supported metallocene catalyst of the present invention, in which the first metallocene compound and the second metallocene compound are supported in the above molar ratio, can further improve physical properties of polyethylene and its film due to interaction between two or more catalysts.

In the composite supported metallocene catalyst of the present invention, a carrier having hydroxyl groups on its surface may be used as a carrier for supporting the first metallocene compound and the second metallocene compound. Preferably, a carrier containing highly reactive hydroxyl and siloxane groups may be used, which has been dried to remove moisture on the surface.

For example, the carrier may be at least one selected from the group consisting of silica, silica-alumina or silica-magnesia dried at high temperature, and usually contains oxides, carbonates, sulfates and nitrates, such as Na ₂ O、K ₂ CO ₃ 、BaSO ₄ And Mg (NO) ₃ ) ₂ Etc.

The drying temperature of the support may preferably be about 200 to 800 ℃, more preferably about 300 to 600 ℃, most preferably about 300 to 400 ℃. When the drying temperature of the support is less than 200 ℃, the surface moisture may react with a cocatalyst described later due to excessive moisture. When it is more than 800 ℃, pores on the surface of the support may be incorporated, resulting in a reduction in surface area, and the surface may lose a large amount of hydroxyl groups and only siloxane groups remain, thereby reducing the reaction sites with the cocatalyst, which is not preferable.

The amount of hydroxyl groups on the support surface may preferably be about 0.1 to 10mmol/g, more preferably about 0.5 to 5mmol/g. The amount of hydroxyl groups on the surface of the support may be controlled by the preparation method and conditions of the support or drying conditions (e.g., temperature, time, vacuum or spray drying, etc.).

When the amount of hydroxyl groups is less than about 0.1mmol/g, the reaction sites with the cocatalyst may be small, and when it is more than about 10mmol/g, it may be caused by moisture in addition to hydroxyl groups on the surface of the carrier particle, which is not preferable.

For example, the total amount of the first and second metallocene compounds supported on the carrier (e.g., silica), i.e., the loading amount of the metallocene compound, may be 0.01mmol/g to 1mmol/g based on 1g of the carrier. That is, in view of the effect of the metallocene compound contributing to the catalyst, the amount is preferably controlled within the above range.

Meanwhile, the composite supported metallocene catalyst may be a catalyst in which at least one first metallocene compound and at least one second metallocene compound are supported on a carrier together with a cocatalyst compound. The cocatalyst can be any cocatalyst used for the polymerization of olefins in the presence of a general metallocene catalyst. This promoter forms a bond between the hydroxyl groups in the support and the group 13 transition metal. In addition, since the cocatalyst is present only on the surface of the support, it can contribute to the achievement of the inherent characteristics of the specific composite catalyst composition of the present invention without the fouling phenomenon that polymer particles agglomerate to the reactor wall or to each other.

In addition, the composite supported metallocene catalyst of the present invention may further comprise at least one cocatalyst selected from the group consisting of compounds represented by the following chemical formulas 3 to 5.

[ chemical formula 3]

-[Al(R ³¹ )-O] _c -

In the chemical formula 3, the chemical formula is shown in the drawing,

R ³¹ each independently is halogen, C _1-20 Alkyl or C _1-20 Haloalkyl, and

c is an integer of 2 or more;

[ chemical formula 4]

D(R ⁴¹ ) ₃

In the chemical formula 4, the chemical formula is shown in the drawing,

d is aluminum or boron, and

R ⁴¹ each independently is hydrogen, halogen, C _1-20 C of hydrocarbon radicals or substituted halogens _1-20 A hydrocarbon group,

[ chemical formula 5]

[L-H] ⁺ [Q(E) ₄ ] ^- Or [ L ]] ⁺ [Q(E) ₄ ] ^-

In the chemical formula 5, the chemical formula is shown in the drawing,

L is a neutral or cationic Lewis base;

[L-H] ⁺ is a Bronsted acid, and is preferably a Bronsted acid,

q is B ³⁺ Or Al ³⁺ And (2) and

e is each independently C _6-40 Aryl or C _1-20 Alkyl, provided that C _6-40 Aryl or C _1-20 The alkyl group may be unsubstituted or substituted with a member selected from the group consisting of halogen, C _1-20 Alkyl, C _1-20 Alkoxy or C _6-40 At least one substituent of the group consisting of aryloxy.

The compound represented by chemical formula 3 may be an alkylaluminoxane, for example, modified Methylaluminoxane (MMAO), methylaluminoxane (MAO), ethylaluminoxane, isobutylaluminoxane, butylaluminoxane, and the like.

The alkyl metal compound represented by chemical formula 4 may be trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, dimethylaluminum chloride, dimethylaluminum isobutyl aluminum, dimethylaluminum, diethylaluminum chloride, triisopropylaluminum, tri-sec-butylaluminum, tricyclopentylaluminum, tripentylaluminum, triisopentylaluminum, trihexylaluminum, ethylaluminum, methyldiethylaluminum, triphenylaluminum, tri-p-tolylaluminum, dimethylaluminum methoxide, dimethylaluminum ethoxide, trimethylboron, triethylboron, triisobutylboron, tripropylboron, tributylboron, or the like.

The compound represented by chemical formula 5 may be triethylammonium tetraphenyl boron, tributylammonium tetraphenyl boron, trimethylammonium tetraphenyl boron, tripropylammonium tetraphenyl boron, trimethylammonium tetrakis (p-tolyl) boron, tripropylammonium tetrakis (p-tolyl) boron, triethylammonium tetrakis (o, p-dimethylphenyl) boron, trimethylammonium tetrakis (o, p-dimethylphenyl) boron, tributylammonium tetrakis (p-trifluoromethylphenyl) boron, trimethylammonium tetrakis (p-trifluoromethylphenyl) boron, tributylammonium tetrapenta-fluorophenyl boron, N-dimethylanilinium tetraphenyl boron, N-diethylanilinium tetraphenyl boron, N, N-diethylaniline tetrakis (p-tolyl) boron, diethylammonium tetrakis (pentafluorophenyl) boron, triphenylphosphonium tetraphenyl boron, trimethylphosphonium tetraphenyl boron, triethylammonium tetraphenyl aluminum, tributylammonium tetraphenyl aluminum, trimethylammonium tetraphenyl aluminum, tripropylammonium tetraphenyl aluminum, trimethylammonium tetrakis (p-tolyl) aluminum, tripropylammonium tetrakis (p-tolyl) aluminum, triethylammonium tetrakis (o, p-dimethylphenyl) aluminum, tributylammonium tetrakis (p-trifluoromethylphenyl) aluminum, trimethylammonium tetrakis (p-trifluoromethylphenyl) aluminum, tributylammonium tetrapenta-pentafluorophenyl aluminum, N-dimethylanilinium tetraphenyl aluminum, N-diethylanilinium tetraphenyl aluminum, diethylammonium tetraphenyl aluminum, triphenylphosphonium tetraphenyl aluminum, trimethylphosphonium tetraphenyl aluminum, triphenylcarbonium tetraphenyl boron, triphenylcarbonium tetraphenyl aluminum, trimethylammonium tetraphenyl aluminum, triphenylcarbonium tetrakis (p-trifluoromethylphenyl) boron or triphenylcarbonium tetrapentafluorophenylboron, and the like.

In addition, the composite supported metallocene catalyst may comprise a cocatalyst and a first metallocene compound in a molar ratio of about 1:1 to about 1:10000, preferably about 1:1 to about 1:1000, more preferably about 1:10 to about 1:100.

In addition, the composite supported metallocene catalyst may comprise a cocatalyst and a second metallocene compound in a molar ratio of about 1:1 to about 1:10000, preferably about 1:1 to about 1:1000, more preferably about 1:10 to about 1:100.

At this time, if the molar ratio is less than about 1, the metal content of the promoter is too small, and thus the catalytically active species are not well formed, resulting in low activity. If the molar ratio exceeds about 10000, the metal of the promoter acts as a catalyst poison.

The loading of the cocatalyst can be from about 5mmol to about 20mmol based on 1g of the support.

Meanwhile, the composite supported metallocene catalyst may be prepared by a method comprising the steps of: loading a cocatalyst on a carrier; loading a first metallocene compound on a support loaded with a cocatalyst; and supporting a second metallocene compound on a support supporting the cocatalyst and the first metallocene compound.

Alternatively, the composite supported metallocene catalyst may be prepared by a method comprising the steps of: loading a cocatalyst on a carrier; loading a second metallocene compound on a support loaded with a cocatalyst; and supporting the first metallocene compound on a support supporting the cocatalyst and the second metallocene compound.

Alternatively, the composite supported metallocene catalyst may be prepared by a method comprising the steps of: supporting a first metallocene compound on a support; loading a cocatalyst on a carrier loaded with a first metallocene compound; and supporting a second metallocene compound on a support supporting the cocatalyst and the first metallocene compound.

In the above method, the loading conditions are not particularly limited, and the loading step may be performed within a range well known to those skilled in the art. For example, the loading step may be suitably performed at a high temperature and a low temperature. For example, the loading temperature may be in the range of about-30 ℃ to about 150 ℃, preferably in the range of about 50 ℃ to about 98 ℃, or about 55 ℃ to about 95 ℃. The loading time may be appropriately controlled according to the amount of the first metallocene compound to be loaded. The supported catalyst after the reaction may be used without further treatment after removing the reaction solvent by filtration or distillation under reduced pressure, or may be subjected to Soxhlet filtration using an aromatic hydrocarbon (e.g., toluene) if necessary.

The preparation of the supported catalyst may be carried out with or without a solvent. When a solvent is used, it may include aliphatic hydrocarbon solvents (e.g., hexane or pentane), aromatic hydrocarbon solvents (e.g., toluene or benzene), chlorinated hydrocarbon solvents (e.g., methylene chloride), ether solvents (e.g., diethyl ether or Tetrahydrofuran (THF)), and common organic solvents (e.g., acetone or ethyl acetate). Hexane, heptane, toluene or dichloromethane are preferably used.

Also, a method for preparing a polyethylene copolymer is provided, comprising the step of copolymerizing ethylene with an alpha-olefin in the presence of the above-mentioned composite supported metallocene catalyst.

The composite supported metallocene catalyst can show excellent supporting performance, catalytic activity and high comonomer incorporation. Therefore, even when low-density polyethylene is produced in a slurry process in the presence of a composite supported metallocene catalyst, the conventional problems of low productivity and fouling can be prevented and process stability can be improved.

The preparation of the polyethylene copolymer may be carried out by slurry polymerization using ethylene and alpha-olefin as raw materials in the presence of the above-mentioned composite supported metallocene catalyst using conventional apparatus and contact techniques.

The method for producing the polyethylene copolymer may be carried out by copolymerizing ethylene and an alpha-olefin using a continuous slurry polymerization reactor or a loop slurry reactor or the like, but is not limited thereto.

Specifically, the copolymerization reaction may be performed by reacting an α -olefin in an amount of about 0.45 mol or less or about 0.1 to about 0.45 mol based on 1 mol of ethylene. More specifically, the α -olefin is about 0.4 mole or less, or about 0.38 mole or less, or about 0.35 mole or less, or about 0.31 mole or less, and about 0.15 mole or more, or about 0.2 mole or more, or about 0.25 mole or more, or about 0.28 mole or more, based on 1 mole of ethylene.

In the production method of the polyethylene copolymer of the present invention, it is not necessary to increase the comonomer content to decrease the product density, so that the process can be stabilized and a high dart impact strength of the product can be obtained.

In addition, the α -olefin may be at least one selected from the group consisting of 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, and mixtures thereof. Preferably, the alpha-olefin may be 1-hexene.

Specifically, in the preparation of the polyethylene copolymer, for example, 1-hexene can be used as the α -olefin. Thus, in slurry polymerization, a low density polyethylene copolymer may be prepared by polymerizing ethylene and 1-hexene.

In addition, the polymerization may be carried out at a temperature of about 25 ℃ to about 500 ℃, about 25 ℃ to about 300 ℃, about 30 ℃ to about 200 ℃, about 50 ℃ to about 150 ℃, or about 60 ℃ to about 120 ℃. In addition, the polymerization may be conducted at a pressure of from about 1 bar to about 100 bar, or from about 5 bar to about 90 bar, or from about 10 bar to about 80 bar, or from about 15 bar to about 70 bar, or from about 20 bar to about 60 bar.

In addition, the supported metallocene catalyst may be dissolved or diluted in C _5-12 Aliphatic hydrocarbon solvents (e.g., pentane, hexane, heptane, nonane, decane) and isomers thereof, aromatic hydrocarbon solvents (e.g., toluene and benzene), or hydrocarbon solvents substituted with chlorine (e.g., methylene chloride and chlorobenzene), and injecting. The solvent used herein is preferably used after removing a small amount of water or air acting as a catalyst poison by treatment with a small amount of aluminum alkyl. Cocatalysts may be further used.

For example, the polymerization reaction may be conducted in the presence of hydrogen in an amount of about 800ppm or less, or about 0 to about 800ppm, or about 300ppm or less, or about 10ppm to about 300ppm, or about 100ppm or less, or about 15ppm to about 100ppm based on the ethylene content.

The transition metal compounds of the present invention may exhibit high catalytic activity during such ethylene polymerization. For example, the catalyst activity in the ethylene polymerization process is about 4.8kg PE/g.cat.hr or more, or about 4.8kg PE/g.cat.hr to about 50kg PE/g.cat.hr, or specifically 5.0kg PE/g.cat.hr or more, or about 5.0kg PE/g.cat.hr to about 40kg PE/g.cat.hr, or more specifically about 5.1kg PE/g.cat.hr or more, or about 5.1kg PE/g.cat.hr to about 35kg PE/g.cat.hr. Here, the catalyst activity is calculated as the ratio of the weight of polyethylene produced (kg PE) to the weight of supported catalyst used (g) on a unit time (h) basis.

As described above, the polyethylene copolymer of the present invention can be prepared by copolymerizing ethylene and an alpha-olefin using the above-mentioned supported metallocene catalyst.

The polyethylene to be prepared may here be an ethylene-1-hexene copolymer.

According to another embodiment of the present invention, there is provided a polyethylene copolymer obtained by the above method.

The preparation method of the polyethylene copolymer can provide a polyethylene copolymer having excellent mechanical properties by performing slurry polymerization in the presence of the above-mentioned composite supported metallocene catalyst.

Meanwhile, linear Low Density Polyethylene (LLDPE) is produced by copolymerizing ethylene and an alpha olefin at a low pressure using a polymerization catalyst. Linear low density polyethylene is a resin having a narrow molecular weight distribution and short chain branches of a predetermined length. In particular, the linear low density polyethylene film has high breaking strength and elongation as well as characteristics of general polyethylene, and has excellent tear strength and dart impact strength. Therefore, linear low density polyethylene films are increasingly used for stretched films, overlapped films, and the like, which are difficult to apply to conventional low density polyethylene or high density polyethylene.

Furthermore, it is generally known that the transparency and dart impact strength of conventional linear low density polyethylene increases as the density decreases. However, when a large amount of comonomer is used to produce low density polyethylene, the occurrence of fouling in the slurry polymerization process increases, and when a film comprising the same is produced, the amount of antiblocking agent must be increased due to tackiness. In addition, there is a problem in that the process is unstable during the production process or the morphology characteristics of the produced polyethylene are deteriorated, thereby lowering the bulk density.

In the present invention, the above-mentioned composite supported metallocene catalyst can provide a polyethylene copolymer having excellent mechanical properties and a high dart impact strength of a film using the same, while preventing problems associated with productivity degradation and fouling, which generally occur when preparing a low-density polyethylene copolymer by slurry polymerization.

Thus, the polyethylene copolymer may be of a density of about 0.930g/cm in accordance with ASTM D792, american society for Material and test (American Society for Testing and Materials) ³ The following low density polyethylenes. Specifically, the density was about 0.910g/cm ³ Above, or about 0.911g/cm ³ Above, or about 0.912g/cm ³ Above, or about 0.913g/cm ³ Above, or about 0.915g/cm ³ Above, and about 0.925g/cm ³ Below, about 0.923g/cm ³ Below, or about 0.920g/cm ³ Below, or about 0.918g/cm ³ Below, or about 0.917g/cm ³ Below, or about 0.9168g/cm ³ The following is given. The density of the polyethylene copolymer should satisfy the above range in terms of ensuring excellent transparency and high impact strength during film processing.

Melt Index (MI) of polyethylene copolymer measured according to American society for Material and test standard ASTM D1238 _2.16 190 ℃ under a load of 2.16 kg) is about 0.5g/10min to about 2.0g/10min. Specifically, melt index (MI _2.16 Measured at 190℃under a load of 2.16 kg) is about 0.7g/10min or more, about 0.8g/10min or more, about 0.9g/10min or more, or about 0.98g/10min or more, and about 1.8g/10min or less, or about 1.5g/10min or less.

In addition, the Bulk Density (BD) of the polyethylene copolymer, as measured in accordance with ASTM D1895, the American society for materials and testing, may be greater than about 0.2g/mL, or from about 0.2g/mL to about 0.7g/mL. Specifically, the bulk density is about 0.25g/mL or more, or about 0.3g/mL or more, or about 0.35g/mL or more, or about 0.4g/mL or more, or about 0.41g/mL or more, and about 0.6g/mL or less, or about 0.5g/mL or less, or about 0.48g/mL or less, or about 0.47g/mL or less, or about 0.46g/mL or less, or about 0.45g/mL or less. In order to ensure excellent morphology of the polyethylene copolymer, the bulk density should satisfy the above range.

In particular, the dart impact strength of polyethylene copolymer films prepared using the film applicator (BUR (blown up ratio) 2.3.3, 48 μm to 52 μm film thickness, e.g., 50 μm film thickness) of polyethylene copolymers measured in accordance with American society for materials and testing standard ASTM D1709 may be greater than 1200g, or about 1200g to about 3500g. Specifically, the dart impact strength may be about 1350g or more, or about 1500g or more, or about 1550g or more, or about 1600g or more, or about 1650g or more, or about 1700g or more. The higher the dart impact strength value, the better, so the upper limit is not particularly limited, but about 3200g or less, or about 3000g or less, or about 2800g or less, or about 2500g or less, or about 2200g or less, or about 2000g or less. The dart impact strength of the polyethylene copolymer should satisfy the above range in terms of ensuring high mechanical properties at the time of forming a film (e.g., a blown film) and excellent processability.

Further, a polyethylene copolymer film (BUR 2.3, film thickness 48 μm to 52 μm, for example, film thickness 50 μm) prepared using a film coater of a polyethylene copolymer measured in accordance with International organization for standardization standard ISO 13468 has a haze of 12% or less. Specifically, the haze may be about 11% or less, or about 10% or less, or about 9% or less. The lower limit is not particularly limited, but may be, for example, about 4% or more, or about 5% or more, or about 6% or more, as the haze value is lower.

Meanwhile, the molecular weight distribution (Mw/Mn) of the polyethylene copolymer may be about 2.0 to about 6.0, or about 2.0 to about 5.0, or about 2.0 to about 4.0.

For example, the molecular weight distribution (Mw/Mn) can be calculated by the following procedure: the weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured using gel permeation chromatography (GPC, manufactured by Water), and then the weight average molecular weight (Mw) was divided by the number average molecular weight (Mn).

Specifically, the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polyethylene copolymer can be measured by Gel Permeation Chromatography (GPC) in terms of polystyrene standard samples. For example, PL-GPC220 manufactured by Waters can be used as a Gel Permeation Chromatography (GPC) instrument, and a Polymer Laboratories PLgel MIX-B300 mm long column can be used. The evaluation temperature may be 160℃and 1,2, 4-trichlorobenzene may be used as the solvent at a flow rate of 1mL/min. Each polyethylene sample may be pretreated by dissolving in 1,2, 4-trichlorobenzene containing 0.0125% BHT at 160℃for 10 hours using GPC analyzer (PL-GP 220), and a sample having a concentration of 10mg/10mL may be supplied in an amount of 200. Mu.L. Mw and Mn can be obtained using calibration curves formed using polystyrene standards. 9 polystyrene standards may be used, with weight average molecular weights of 2000g/mol, 10000g/mol, 30000g/mol, 70000g/mol, 200000g/mol, 700000g/mol, 2000000g/mol, 4000000g/mol and 10000000g/mol.

The weight average molecular weight of the polyethylene copolymer may be from about 50000g/mol to about 200000g/mol. Specifically, the weight average molecular weight of the polyethylene copolymer may be about 60000g/mol or more, or about 65000g/mol or more, or about 70000g/mol or more, and about 190000g/mol or less, or about 180000g/mol or less, or about 150000g/mol or less.

Thus, the polyethylene copolymers of the invention are useful in a variety of applications requiring such physical properties. In particular, it is useful in agricultural/industrial and packaging applications where high dart impact resistance is required. It can also be used for shrink films where conventional low density polyethylene or high density polyethylene is difficult to apply.

Advantageous effects

The composite supported metallocene catalyst of the present invention exhibits excellent process stability and high activity for ethylene polymerization, and can prepare a polyethylene copolymer having excellent mechanical properties by increasing the comonomer incorporation during ethylene polymerization.

Detailed Description

Hereinafter, the action and effect of the present invention will be described in more detail by means of specific examples. However, these examples are for illustrative purposes only, and the present invention is not intended to be limited to these examples.

Examples (example)

< preparation of first metallocene Compound >

Synthesis example 1

N-butyl chloride is reacted with sodium cyclopentadienyl (NaCp) to obtain n-butylcyclopentadiene (n-BuCp). Thereafter, n-BuCp was dissolved in Tetrahydrofuran (THF) at-78℃to which n-butyllithium (n-BuLi, 2.5M in hexane) was slowly added, and then the temperature was raised to room temperature, followed by reaction for 8 hours. The prepared lithium salt solution was cooled to-78 ℃ and slowly added to ZrCl at this temperature ₄ (THF) ₂ (1.70 g,4.50 mmol)/THF (30 mL). Then, the reaction mixture was warmed to room temperature, followed by reaction for 6 hours. Thereafter, the reaction was removed by vacuum dryingAll volatile materials should be mixed and a hexane solvent is added to the obtained oily liquid material, followed by filtration to obtain a solution containing the reaction product. After drying the filtered solution in vacuo, hexane was added to initiate precipitation at low temperature (-20 ℃). The obtained precipitate was filtered at low temperature to obtain [ (CH) as a white solid ₃ )(CH ₂ ) ₃ -C ₅ H ₄ ] ₂ ZrCl ₂ (yield 50%).

Synthesis example 2

tert-butyl-O- (CH) ₂ ) ₆ Cl is prepared by the process described in literature (Tetrahedron Lett.2951, 1988) using 6-chlorohexanol and reacting it with sodium cyclopentadienyl (NaCp) to obtain tert-butyl-O- (CH) ₂ ) ₆ -C ₅ H ₅ (yield 60%, b.p.80 ℃ C./0.1 mmHg).

In addition, tert-butyl-O- (CH) is reacted at-78deg.C ₂ ) ₆ -C ₅ H ₅ Dissolved in Tetrahydrofuran (THF), to which n-butyllithium (n-BuLi, 2.5M in hexane) was slowly added, and then the temperature was raised to room temperature, followed by reaction for 8 hours. The prepared lithium salt solution was cooled to-78 ℃ and slowly added to ZrCl at this temperature ₄ (THF) ₂ (1.70 g,4.50 mmol)/THF (30 mL). Then, the reaction mixture was warmed to room temperature, followed by reaction for 6 hours. Thereafter, all volatile matters of the reaction mixture were removed by vacuum drying, and a hexane solvent was added to the obtained oily liquid matter, followed by filtration to obtain a solution containing a reaction product. After drying the filtered solution in vacuo, hexane was added to induce precipitation at low temperature (-20 ℃). The precipitate obtained was filtered at low temperature to obtain [ tert-butyl-O- (CH) as a white solid ₂ ) ₆ -C ₅ H ₄ ] ₂ ZrCl ₂ ](yield 92%).

¹ H-NMR(300MHz,CDCl ₃ ,ppm):δ6.28(t,J＝2.6Hz,2H),6.19(t,J＝2.6Hz,2H),3.31(t,6.6Hz,2H),2.62(t,J＝8Hz),1.7–1.3(m,8H),1.17(s,9H)。

¹³ C-NMR(300MHz,CDCl ₃ ,ppm):δ135.09,116.66,112.28,72.42,61.52,30.66,30.31,30.14,29.18,27.58,26.00。

Comparative Synthesis example 1

Synthesis of (6-t-Butoxyhexyl) (fluorenyl) methylsilane

tert-butyl-O- (CH) ₂ ) ₆ Cl and Mg (0) in diethyl ether (Et) ₂ O) to obtain 0.14mol of Grignard reagent tBu-O- (CH) ₂ ) ₆ MgCl solution. At a temperature of-100deg.C, methyltrichlorosilane (MeSiCl ₃ ) The compound (24.7 mL,0.21 mol) was then stirred at room temperature for 3 hours or more. After completion of the reaction, filtration was performed, and the filtered solution was dried in vacuo to obtain (6-t-butoxyhexyl) dichloromethylsilane [ tBu-O- (CH) ₂ ) ₆ SiMeCl ₂ ](yield 84%). A solution of fluorenyllithium (4.82 g,0.028 mol) in hexane (150 mL) was slowly added to tBu-O- (CH) over 2 hours at-78deg.C ₂ ) ₆ SiMeCl ₂ (7.7 g,0.028 mol) in hexane (50 mL). Then, the white precipitate (LiCl) was filtered off and the desired product was extracted with hexane. After all volatiles were removed from the hexane solution by vacuum drying, (6- (tert-butoxy) hexyl) fluorenylmethylsilane [ tBu-O- (CH) was obtained as a pale yellow oil ₂ ) ₆ )SiMe(9-C ₁₃ H ₁₀ )]Compound (99% yield).

Synthesis of (t-butoxyhexyl) (cyclopentadienyl) (fluorenyl) methylsilane

THF solvent (50 mL) was added to the above compound and reacted with C at room temperature ₅ H ₅ Li (2.0 g,0.028 mol)/THF (50 mL) solution was reacted for more than 3 hours. After removal of all volatile materials from the reaction product by vacuum drying, the dried product is extracted with hexane to obtain the final ligand compoundAnd (3) the following substances: (tert-Butoxyhexyl) (cyclopentadienyl) (fluorenyl) methylsilane [ (tBu-O- (CH) in the form of an orange oil ₂ ) ₆ )(CH ₃ )Si(C ₅ H ₅ )(9-C ₁₃ H ₁₀ )](yield 95%). The structural passage of the ligand ¹ H-NMR confirmation.

Synthesis of (t-butoxyhexyl) (methyl) silane (cyclopentadienyl) (fluorenyl) zirconium dichloride

In addition, 2 equivalents of n-BuLi are added to (tert-butoxyhexyl) (cyclopentadienyl) (fluorenyl) methylsilane [ (tBu-O- (CH) at a temperature of-78 ] ₂ ) ₆ )(CH ₃ )Si(C ₅ H ₅ )(9-C1 ₃ H ₁₀ )](12 g,0.028 mol)/THF (100 mL). After the completion of the addition, the reaction temperature was raised to room temperature and allowed to proceed for more than 4 hours to obtain (tBu-O- (CH) as an orange solid ₂ ) ₆ )(CH ₃ )Si(C ₅ H ₅ Li)(9-C ₁₃ H ₁₀ Li) dilithium salt (yield 81%). Thereafter, a solution of dilithium salt (2.0 g,4.5 mmol)/diethyl ether (30 mL) was slowly added to ZrCl at a temperature of-78deg.C ₄ (1.05 g,4.50 mmol) in diethyl ether (30 mL). The reaction was further carried out at room temperature for 3 hours. After all volatile matters in the resulting solution were removed by vacuum drying, a methylene chloride solvent was added to the obtained oily liquid matter, and filtration was performed to remove some solid matters. After drying the filtered solution in vacuo, hexane was added to induce a precipitate. The resulting precipitate was washed several times with hexane. Then, rac- (t-Bu-O- (CH) in the form of a red solid was obtained as rac- (tert-butoxyhexyl) (methyl) silyl (cyclopentadienyl) (fluorenyl) zirconium dichloride ₂ ) ₆ )(CH ₃ )Si(C ₅ H ₄ )(9-C ₁₃ H ₉ )ZrCl ₂ ](yield 54%).

Comparative Synthesis example 2

Indene (5 g,0.043 mol) was dissolved in hexane (150 mL) and thoroughly mixed. Thereafter, the temperature of the reaction was cooled to-30℃and a 2.5M solution of n-butyllithium (n-BuLi) in hexane (17 ml,0.043 mol) was added dropwise to the reaction. Then, the reaction temperature was gradually raised to room temperature, followed by stirring at room temperature for 12 hours. The resulting white suspension was filtered through a glass filter to obtain a white solid compound. The white solid compound was sufficiently dried, and then indene lithium salt was obtained (yield: 99% yield).

Cyclopentadienyl zirconium trichloride (Cp-ZrCl) ₃ 2.24g,8.53 mmol) was slowly dissolved in diethyl ether (30 mL) and the reaction temperature was then cooled to-30 ℃. To contain CpZrCl ₃ To the diethyl ether solution of the above indene lithium salt (1.05 g,8.53 mmol) in diethyl ether (15 mL) was added dropwise and then stirred overnight. Then, indenyl (cyclopentadienyl) zirconium dichloride [ indenyl (cyclopentadienyl) ZrCl ] was obtained ₂ ](yield: 97%).

Comparative Synthesis example 3

Synthesis of (6-t-Butoxyhexyl) dichloromethylsilane

100mL of t-butoxyhexyl magnesium chloride solution (0.14 mol, diethyl ether) was added dropwise to 100mL of a solution of trichloromethylsilane (0.21 mol, hexane) at-100℃over 3 hours. Then, the reaction temperature was raised to room temperature, followed by stirring at room temperature for 3 hours.

After separating the transparent organic layer from the mixed solution, the separated transparent organic layer was vacuum-dried to remove the excess trichlorosilane. Thus, a transparent liquid (6-t-butoxyhexyl) dichloromethylsilane was obtained (yield 84%).

¹ H NMR(500MHz,CDCl ₃ ,7.24ppm):δ0.76(3H,s),1.11(2H,t),1.18(9H,s),1.32-1.55(8H,m),3.33(2H,t)。

Synthesis of (6- (tert-butoxy) hexyl) (4- (4- (tert-butyl) phenyl) -2-methyl-1H-inden-1-yl) (methyl) (2-isopropyl-4- (4- (tert-butyl) phenyl) -1H-inden-1-yl) silane

20g (76.222 mmol) of 2-methyl-4- (4- (tert-butyl) phenyl) indene are dissolved in 640mL of a mixed solvent of hexane and methyl tert-butyl ether (MTBE) (Hex/MTBE=15/1 volume ratio). Thereafter, 33.5mL of n-BuLi (2.5M in hexane) was added dropwise to the solution at-20 ℃. After the resulting reaction mixture was stirred at room temperature for one day, a solution of 19.7g (72.411 mmol) (6-t-butoxyhexyl) of dichloromethylsilane in hexane at-20℃was slowly added to the resulting reaction mixture. The resulting reaction mixture was then stirred at room temperature for one day. After volatile solvents in the resulting reaction mixture were removed by vacuum drying, hexane was added to the dried reaction mixture and vacuum filtration was performed again. After drying the filtered solution, a silane compound is obtained.

Meanwhile, in another flask, 22.1g (76.222 mmol) of 2-isopropyl-4- (4- (tert-butyl) phenyl) indene and 136.5mg (1.525 mmol) of CuCN were dissolved in 200mL of diethyl ether. Thereafter, 33.5mL of n-butyllithium solution (2.5M in hexane) was added dropwise to the diethyl ether solution at-20 ℃. Then, after the resulting reaction mixture was stirred at room temperature for one day, the monosilane prepared above was dissolved in 180mL of diethyl ether and added to the resulting reaction mixture. Thereafter, the resulting reaction mixture was stirred at room temperature for one day, the organic material was extracted with water and MTBE, and dried in vacuo. The dried product was then purified by column chromatography to give the final ligand in 67% yield.

Synthesis of 6- (tert-Butoxy) hexyl) (4- (4- (tert-butyl) phenyl) -2-methyl-1H-inden-1-yl) (methyl) (2-isopropyl-4- (4- (tert-butyl) phenyl) -1H-inden-1-yl) silane zirconium dichloride

1.00g (1.331 mmol) of the (6- (t-butoxy) hexyl) (4- (4- (t-butyl) phenyl) -2-methyl-1H-inden-1-yl) (methyl) (2-isopropyl-4- (4- (t-butyl) phenyl) -1H-inden-1-yl) silane prepared above was dissolved in 33mL of diethyl ether, and then 1.1mL of an n-butyllithium solution (2.5M in hexane) was added dropwise to the above diethyl ether solution. After the obtained reaction mixture was stirred at room temperature for about 4 hours, a catalyst prepared by adding 706mg (1.331 mmol) of bis (N, N' -diphenyl-1, 3-malonamido) zirconium dichloride bis (tetrahydrofuran) [ Zr (C) ₅ H ₆ NCH ₂ CH ₂ CH ₂ NC ₅ H ₆ )Cl ₂ (C ₄ H ₅ O) ₂ ]The solution prepared by dissolving in 33mL of diethyl ether was then stirred for 1 day. Thereafter, the red reaction solution was cooled to-20 ℃, and 4 equivalents of 1M HCl diethyl ether solution was added dropwise to the cooled solution, and then the resulting solution was stirred again at room temperature for 1 hour. After filtration and vacuum drying, the obtained solid was dissolved in pentane, and then solid crystals were precipitated for 48 hours. After filtration under reduced pressure, the solid was dried and crystallized to obtain an orange transition metal compound, (6- (tert-butoxy) hexyl) (4- (4- (tert-butyl) phenyl) -2-methyl-1H-inden-1-yl) (methyl) (2-isopropyl-4- (4- (tert-butyl) phenyl) -1H-inden-1-yl) silane zirconium dichloride in 8% yield (racemic alone).

¹ H NMR(500MHz,CDCl ₃ ,7.26ppm):δ1.05(3H,d),1.09(3H,d),1.20(3H,s),1.34(9H,s),1.50-1.93(10H,m),2.27-2.31(1H,m),3.37(2H,t),6.48(1H,s)6.98(1H,s),7.01(1H,s),7.09-7.12(2H,m),7.34-7.70(12H,m)。

< preparation of second metallocene Compound >

Synthesis example 3

Synthesis of 1-bromo-4- (tert-butoxymethyl) benzene

Will H ₂ SO ₄ (1.47 mL) and anhydrous MgSO ₄ (12.9 g,107 mmol) CH is added ₂ Cl ₂ (80 mL) and then stirred at room temperature for 15 minutes. In another flask, 4-bromobenzyl alcohol (5.0 g,26.7 mmol) and t-butanol (12.8 mL,134 mmol) were dissolved in CH ₂ Cl ₂ (30 mL) and then the above mixture was added thereto. The mixture was then stirred at room temperature overnight, then saturated NaHCO was added ₃ . With anhydrous MgSO ₄ The water was removed, and the resulting solution was concentrated under reduced pressure, followed by purification by column chromatography (E/h=1/20) to obtain 1-bromo-4- (tert-butoxymethyl) benzene (5.9 g, 90%) as a white solid.

¹ H NMR(500MHz,CDCl ₃ ,7.24ppm):δ1.28(9H,s),4.39(2H,s),7.22(2H,d),7.44(2H,d)。

Synthesis of 7- ((4-tert-butoxymethyl) phenyl) -2-methyl-1H-indene

1-bromo-4- (tert-butoxymethyl) benzene (4.52 g,18.6 mmol) was dissolved in anhydrous THF (20 mL) under argon (Ar). The temperature was reduced to-78 ℃ and n-butyllithium solution (n-BuLi, 2.5M in hexane, 8.2 mL) was added followed by stirring at room temperature for 30 minutes. The temperature was again reduced to-78 ℃, trimethyl borate (6.2 ml,55.6 mmol) was added, and then stirred at room temperature overnight. Adding saturated NH to the reaction solution ₄ Cl solution (sat. NH) ₄ Cl) and then extracted with MTBE. Adding anhydrous MgSO ₄ And the water was removed by filtration. The solution was concentrated under reduced pressure and the subsequent reaction was carried out without further purification.

The compound obtained above was combined with 7-bromo-2-methyl-1H-indene (3.87 g,18.6 mmol) and Na ₂ CO ₃ (5.91 g,55.8 mmol) toluene (40 mL), H were added ₂ O (20 mL) and EtOH (20 mL) and stirring. Pd (PPh) was added to the above solution ₃ ) ₄ (1.07 g,0.93 mmol) and then stirred at 90℃overnight. After the reaction was completed, MTBE and water were added and the organic layer was separated. With anhydrous MgSO ₄ Removing water. The obtained solution was concentrated under reduced pressure, and then purified by column chromatography (E/h=1/30) to obtain 7- ((4-tert-butoxymethyl) phenyl) -2-methyl-1H-indene (2.9 g, 53%).

¹ H NMR(500MHz,CDCl ₃ ,7.24ppm):δ1.33(9H,s),2.14(3H,s),3.36(2H,s),4.50(2H,s),6.53(1H,s),7.11-7.45(7H,m)。

Synthesis of bis (4- (4-tert-butoxymethyl) phenyl) -2-methyl-1H-inden-1-yl) dimethylsilane

7- ((4-t-Butoxymethyl) phenyl) -2-methyl-1H-indene (2.88 g,9.85 mmol) and CuCN (44 mg,0.49 mmol) were dissolved in toluene (18 mL) and THF (2 mL) under argon (Ar). The solution was cooled to-30 ℃ and n-BuLi (2.5M in hexanes, 4.1 mL) was slowly added. After stirring at this temperature for about 20 minutes, the temperature was raised to room temperature and stirred for 2.5 hours. To this solution was added dichlorodimethylsilane (0.59mL,4.89 mmol) and then stirred at room temperature overnight. After the reaction was completed, MTBE and water were added and the organic layer was separated. The obtained organic layer was subjected to anhydrous MgSO ₄ Dried to remove water and concentrated under reduced pressure, and then purified by column chromatography (hexane) to obtain bis (4- (4-t-butoxymethyl) phenyl) -2-methyl-1H-inden-1-yl) dimethylsilane (2.95 g, 93%) as a white solid.

¹ H NMR(500MHz,CDCl ₃ ,7.24ppm):δ-0.20(6H,s),1.35(18H,s),2.19(3H,s),2.25(3H,s),3.81(2H,s),4.53(4H,s),6.81(2H,s),7.18-7.52(14H,m)。

Synthesis of dimethylsilyl-bis (4- (4-t-butoxymethyl) phenyl) -2-methyl-1H-inden-1-yl) zirconium dichloride

Bis (4- (4-t-butoxymethyl) phenyl) -2-methyl-1H-inden-1-yl) -dimethyl-silane (2.0 g,3.12 mmol) was added to a 50mL Schlenk flask under argon (Ar) and dissolved by injection of diethyl ether (20 mL). The temperature was reduced to-78 ℃, n-BuLi (2.5M in hexane, 2.7 mL) was added, and then stirred at room temperature for 2 hours. The solvent was distilled under vacuum/reduced pressure, and ZrCl was added in the glove box ₄ (THF) ₂ (1.18 g,3.12 mmol) and the temperature was reduced to-78 ℃. Diethyl ether (20 mL) was added to the mixture, and the temperature was then raised to room temperature, followed by stirring overnight. The solvent was distilled under reduced pressure and dissolved in CH ₂ Cl ₂ To remove solids. The solution was concentrated under reduced pressure, and the obtained solid was purified with toluene and CH ₂ Cl ₂ Washed to obtain dimethylsilyl-bis (4- (4-t-butoxymethyl) phenyl) -2-methyl-1H-inden-1-yl) zirconium dichloride (260 mg,10%, r/m about 16/1) as a racemic-rich yellow solid.

¹ H NMR(500MHz,CDCl ₃ ,7.24ppm):δ1.28(18H,s),1.33(6H,s),2.24(6H,s),4.46(4H,s),6.93(2H,s),7.08–7.65(14H,m)。

Synthesis example 4

Synthesis of 1-bromo-4- (methoxymethyl) benzene

To the flask was added DMSO (117 mL)/KOH (214 mmol,12 g), 4-bromobenzyl alcohol (53.5 mmol,10.0 g) and then stirred at room temperature for 1 hour. To the reaction product was added MeI (107 mmol,6.6 mL) and then stirred for 10 min. After the reaction was completed, the reaction mixture was poured into H ₂ O, then using CH ₂ Cl ₂ And (5) extracting. The organic layer was dried over anhydrous MgSO ₄ Dried, and then vacuum dried to obtain 1-bromo-4-methoxymethylbenzene (10.6 g, 99%).

¹ H NMR(500MHz,CDCl ₃ ,7.24ppm):δ3.41(3H,s),4.39(2H,s),7.11-7.53(4H,m)。

Synthesis of 7- (4-methoxymethyl) phenyl) -2-methyl-1H-indene

1-bromo-4- (methoxymethyl) benzene (9.3 g,46.3 mmol) was dissolved in anhydrous THF (40 mL) under argon (Ar). The temperature was reduced to-78 ℃, n-butyllithium solution (n-BuLi, 2.5M in hexane, 20.4 mL) was added, followed by stirring at room temperature for 30 min. The temperature was again lowered to-78 ℃, trimethyl borate (15.5 mL,139 mmol) was added, and then stirred at room temperature overnight. Adding saturated NH to the reaction solution ₄ Cl and then extracted with MTBE. Adding anhydrous MgSO ₄ And the water was removed by filtration. The solution was concentrated under reduced pressure and the subsequent reaction was carried out without further purification.

The compound obtained above, 7-bromo-2-methyl-1H-indene (9.63 g,46.3 mmol) and Na ₂ CO ₃ Toluene (80 mL), H were added (14.7 g,139 mmol) ₂ O (40 mL) and EtOH (40 mL) and stirring. Pd (PPh) was added to the above solution ₃ ) ₄ (1.07 g,2.32 mmol) and then stirred at 90℃overnight. After the reaction was completed, MTBE and water were added and the organic layer was separated. With anhydrous MgSO ₄ Removing water. The obtained solution was concentrated under reduced pressure, and then purified by column chromatography (E/h=1/30) to obtain 7- (4- (methoxymethyl) phenyl) -2-methyl-1H-indene (6.9 g, 60%).

¹ H NMR(500MHz,CDCl ₃ ,7.24ppm):δ2.15(3H,s),3.35(2H,s),3.38(3H,s),4.48(2H,s),6.55(1H,s),7.05-7.44(7H,m)。

Synthesis of bis (4- (4-methoxymethyl) phenyl) -2-methyl-1H-inden-1-yl) dimethylsilane

7- (4-methoxymethyl) phenyl) -2-methyl-1H-indene (4.21 g,16.8 mmol) and CuCN (75 mg,0.84 mmol) were dissolved in toluene (36 mL) and THF (4 mL) under argon (Ar). The solution was cooled to-30 ℃ and n-BuLi (2.5M in hexanes, 7.4 mL) was slowly added. After stirring at this temperature for about 20 minutes, the temperature was raised to room temperature and then stirred for 2.5 hours. To this solution was added dichlorodimethylsilane (1.01 mL,8.4 mmol) and then stirred at room temperature overnight. After the reaction was completed, MTBE and water were added and the organic layer was separated. The obtained organic layer was subjected to anhydrous MgSO ₄ Dried to remove moisture, concentrated under reduced pressure, and then purified by column chromatography (hexane) to obtain bis (4- (4-methoxymethyl) phenyl) -2-methyl-1H-inden-1-yl) dimethylsilane (4.21 g, 90%) as a white solid.

¹ H NMR(500MHz,CDCl ₃ ,7.24ppm):δ-0.21(6H,s),2.20(3H,s),2.23(3H,s),3.40(6H,s),3.82(2H,s),4.50(4H,s),6.79(2H,s),7.15-7.53(14H,m)。

Synthesis of dimethylsilyl-bis (4- (4-methoxymethyl) phenyl) -2-methyl-1H-inden-1-yl) zirconium dichloride

Bis (4- (4-methoxymethyl) phenyl) -2-methyl-1H-inden-1-yl) -dimethyl-silane (3.0 g,5.39 mmol) was added to a 50mL Schlenk flask under argon (Ar) and dissolved by injection of diethyl ether (30 mL). The temperature was reduced to-78 ℃, n-BuLi (2.5M in hexane, 4.7 mL) was added, and then stirred at room temperature for 2 hours. The solvent was distilled under reduced pressure, and ZrCl was added to the glove box ₄ (THF) ₂ (2.04 g,5.39 mmol) and the temperature was reduced to-78 ℃. Diethyl ether (30 mL) was added to the mixture, the temperature was raised to room temperature, and stirred overnight. The solvent was distilled under reduced pressure and dissolved in CH ₂ Cl ₂ To remove solids. The solution was concentrated under reduced pressure, and the obtained solid was purified with toluene and CH ₂ Cl ₂ Washed to obtain dimethylsilyl-bis (4- (4-methoxymethyl) phenyl) -2-methyl-1H-inden-1-yl) zirconium dichloride (425 mg,11%, r/m about 10/1) as a racemic-rich yellow solid.

¹ H NMR(500MHz,CDCl ₃ ,7.24ppm):δ1.31(6H,s),2.22(6H,s),3.39(6H,s),4.43(4H,s),6.91(2H,s),7.09-7.64(14H,m)。

Synthesis example 5

Synthesis of 1-bromo-4- (tert-butoxymethyl) benzene

Synthesis of 7- (4-tert-butoxymethyl) phenyl) -2-methyl-1H-indene

The compound obtained above was combined with 7-bromo-2-methyl-1H-indene (3.87 g,18.6 mmol) and Na ₂ CO ₃ (5.91 g,55.8 mmol) toluene (40 mL), H were added ₂ O (20 mL) and EtOH (20 mL) and stirring. Pd (PPh) was added to the above solution ₃ ) ₄ (1.07 g,0.93 mmol) and then stirred at 90℃overnight. After the reaction was completed, MTBE and water were added and the organic layer was separated. With anhydrous MgSO ₄ Removing water. The obtained solution was concentrated under reduced pressure, and then purified by column chromatography (E/h=1/30) to obtain 7- (4-t-butoxymethyl) phenyl) -2-methyl-1H-indene (2.9 g, 53%).

Synthesis of bis (4- (4-tert-butoxymethyl) phenyl) -2-methyl-1H-inden-1-yl) diethylsilane

7- (4-tert-Butoxymethyl) phenyl) -2-methyl-1H-indene (2.88 g,9.85 mmol) and CuCN (44 mg,0.49 mmol) were dissolved in toluene (18 mL) and THF (2 mL) under argon (Ar). The solution was cooled to-30 ℃ and n-BuLi (2.5M in hexanes, 4.1 mL) was slowly added. After stirring at this temperature for about 20 minutes, the temperature was raised to room temperature and stirred for 2.5 hours. To this solution was added dichlorodiethylsilane (0.73 mL,4.89 mmol) and then stirred at room temperature overnight. After the reaction was completed, MTBE and water were added and the organic layer was separated. The obtained organic layer was subjected to anhydrous MgSO ₄ Dried to remove moisture, concentrated under reduced pressure, and then purified by column chromatography (hexane) to obtain bis (4- (4-t-butoxymethyl) phenyl) -2-methyl-1H-inden-1-yl) diethylsilane (2.95 g, 93%) as a white solid.

Synthesis of Diethylsilyl-bis (4- (4-tert-butoxymethyl) phenyl) -2-methyl-1H-inden-1-yl) zirconium dichloride

Bis (4- (4-t-butoxymethyl) phenyl) -2-methyl-1H-inden-1-yl) -diethyl-silane (2.0 g,3.12 mmol) was added to a 50mL Schlenk flask under argon (Ar) and dissolved by injection of diethyl ether (20 mL). The temperature was reduced to-78 ℃, n-BuLi (2.5M in hexane, 2.7 mL) was added, and then stirred at room temperature for 2 hours. The solvent was distilled under vacuum/reduced pressure, and ZrCl was added in the glove box ₄ (THF) ₂ (1.18 g,3.12 mmol) and the temperature was reduced to-78 ℃. Diethyl ether (20 mL) was added to the mixture, and the temperature was then raised to room temperature, followed by stirring overnight. The solvent was distilled under reduced pressure and dissolved in CH ₂ Cl ₂ To remove solids. The solution was concentrated under reduced pressure, and the obtained solid was purified with toluene and CH ₂ Cl ₂ Washed to obtain diethyl silyl-bis (4- (4-t-butoxymethyl) phenyl) -2-methyl-1H-inden-1-yl) zirconium dichloride (260 mg,10%, r/m about 16/1) as a racemic-rich yellow solid.

Comparative Synthesis example 4

Synthesis of methyl (6-t-butoxyhexyl) dichlorosilane

50g of Mg(s) were added to a 10L reactor at room temperature, followed by 300mL of THF. Adding 0.5. 0.5g I ₂ And the reactor temperature was maintained at 50 ℃. After the reactor temperature had stabilized, 250g of 6-t-butoxyhexyl chloride (6-t-butoxyhexyl chloride) were added to the reactor at a rate of 5mL/min using a feed pump. With the addition of 6-t-butoxyhexyl chloride, an increase in the reactor temperature of about 4℃to 5℃was observed. 6-t-butoxyhexyl chloride was continuously added while the mixture was stirred for 12 hours to obtain a black reaction solution. 2mL of a black solution was taken, and water was added thereto to obtain an organic layer. By passing through ¹ H-NMR confirmed that the organic layer was 6-t-butoxyhexane. From this, it was confirmed that the grignard reaction proceeded well. Thus, 6-t-butoxyhexyl magnesium chloride was synthesized.

500g of MeSiCl ₃ And 1L of THF were added to the reactor, and the reactor temperature was then cooled to-20 ℃. Using feed pumps560g of previously synthesized 6-tert-butoxyhexyl magnesium chloride were added to the reactor at a rate of 5 mL/min. After the completion of the grignard feed, the mixture was stirred for 12 hours while the reactor temperature was slowly raised to room temperature, and it was confirmed that white MgCl was formed ₂ And (3) salt. To this was added 4L of hexane and the salt was removed by labdori to obtain a filtered solution. After the filtered solution was added to the reactor, hexane was removed at 70 ℃ to obtain a pale yellow liquid. The obtained liquid was confirmed by 1H-NMR to be the desired methyl (6-t-butoxyhexyl) dichlorosilane.

¹ H-NMR(500MHz,CDCl ₃ ):δ3.3(t,2H),1.5(m,3H),1.3(m,5H),1.2(s,9H),1.1(m,2H),0.7(s,3H)。

Synthesis of methyl (6-t-butoxyhexyl) (tetramethyl cyclopentadienyl) -t-butylaminosilane

1.2mol (150 g) of tetramethylcyclopentadiene and 2.4L of THF were charged into the reactor, and the reactor temperature was then cooled to-20 ℃. 480mL of n-BuLi (2.5M in hexane) was added to the reactor at a rate of 5mL/min using a feed pump. After the addition of n-BuLi, the mixture was stirred for 12 hours while the reactor temperature was slowly raised to room temperature. Thereafter, an equivalent of methyl (6-t-butoxyhexyl) dichlorosilane (326 g,350 mL) was added quickly to the reactor. The mixture was stirred for 12 hours while the reactor temperature was slowly raised to room temperature. The reactor temperature was then cooled again to 0℃and 2 equivalents of t-BuNH were added ₂ . The mixture was stirred for 12 hours while the reactor temperature was slowly raised to room temperature. Then, THF was removed and 4L of hexane was added to obtain a filtered solution with salt removed by labdori. The filtered solution was again added to the reactor and hexane was removed at 70 ℃ to obtain a yellow solution. By passing through ¹ H-NMR was found to be methyl (6-t-butoxyhexyl) (tetramethyl CpH) t-butylaminosilane.

Synthesis of (t-Butoxyhexyl) methylsilane-based (tetramethyl cyclopentadienyl) (t-butylamino) titanium dichloride

10mmol TiCl at-78℃ ₃ (THF) ₃ Rapidly added to the dilithium salt of the ligand, consisting of n-BuLi and dimethyl (tetramethyl CpH) The tertiary butylaminosilane ligands are synthesized in THF solution. The reaction solution was stirred for 12 hours while the temperature was slowly raised from-78 ℃ to room temperature. Then adding equivalent PbCl at room temperature ₂ (10 mmol) and the mixture was stirred for 12 hours to obtain a bluish, deep black solution. After THF was removed from the resulting reaction solution, hexane was added to filter the product. Hexane was removed from the filtered solution and then passed through ¹ H-NMR confirmed the product as the desired tBu-O- (CH) ₂ ) ₆ ](CH ₃ )Si(C ₅ (CH ₃ ) ₄ )(tBu-N)TiCl ₂ 。

¹ H-NMR(500MHz,CDCl ₃ ):δ3.3(s,4H),2.2(s,6H),2.1(s,6H),1.8-0.8(m),1.4(s,9H),1.2(s,9H),0.7(s,3H)。

Comparative Synthesis example 5

Synthesis of 7-phenyl-2-methyl-1H-indene

Bromobenzene (2.92 g,18.6 mmol) was dissolved in anhydrous THF (20 mL) under argon (Ar). The temperature was reduced to-78 ℃ and n-butyllithium solution (n-BuLi, 2.5M in hexane, 8.2 mL) was added followed by stirring at room temperature for 30 minutes. The temperature was again reduced to-78 ℃, trimethyl borate (6.2 ml,55.6 mmol) was added, and then stirred at room temperature overnight. Adding saturated NH to the reaction solution ₄ Cl solution (sat. NH) ₄ Cl) and then extracted with MTBE. Adding anhydrous MgSO ₄ And the water was removed by filtration. The solution was concentrated under reduced pressure and the subsequent reaction was carried out without further purification.

The compound obtained above was combined with 7-bromo-2-methyl-1H-indene (3.87 g,18.6 mmol) and Na ₂ CO ₃ (5.91 g,55.8 mmol) toluene (40 mL), H were added ₂ O (20 mL) and EtOH (20 mL) and stirring. Pd (PPh) was added to the above solution ₃ ) ₄ (1.07 g,0.93 mmol) and then stirred at 90℃overnight. After the reaction was completed, MTBE and water were added and the organic layer was separated. With anhydrous MgSO ₄ Removing water.The obtained solution was concentrated under reduced pressure, and then purified by column chromatography (E/h=1/30) to obtain 7-phenyl-2-methyl-1H-indene (2.9 g, 53%).

Synthesis of bis (4-phenyl-2-methyl-1H-inden-1-yl) dimethylsilane

7-phenyl-2-methyl-1H-indene (2.02 g,9.85 mmol) and CuCN (44 mg,0.49 mmol) were dissolved in toluene (18 mL) and THF (2 mL) under argon (Ar). The solution was cooled to-30 ℃ and n-BuLi (2.5M in hexanes, 4.1 mL) was slowly added. After stirring at this temperature for about 20 minutes, the temperature was raised to room temperature and stirred for 2.5 hours. To this solution was added dichlorodimethylsilane (0.59 mL,4.89 mmol) and then stirred at room temperature overnight. After the reaction was completed, MTBE and water were added and the organic layer was separated. The obtained organic layer was subjected to anhydrous MgSO ₄ Dried to remove moisture, concentrated under reduced pressure, and then purified by column chromatography (hexane) to obtain bis (4-phenyl-2-methyl-1H-inden-1-yl) -dimethylsilane as a white solid.

Synthesis of dimethylsilyl-bis (4-phenyl-2-methyl-1H-inden-1-yl) zirconium dichloride

Bis (4-phenyl-2-methyl-1H-inden-1-yl) -dimethylsilane (2.0 g,3.12 mmol) was added to a 50mL Schlenk flask and dissolved by injection of diethyl ether (20 mL) under argon (Ar). The temperature was reduced to-78 ℃, n-BuLi (2.5M in hexane, 2.7 mL) was added, and then stirred at room temperature for 2 hours. Vacuum/reduced pressure distillation of the solvent, and ZrCl ₄ (THF) ₂ (1.18 g,3.12 mmol) was placed in a glove box and the temperature was reduced to-78 ℃. Diethyl ether (20 mL) was added to the mixture, and the temperature was then raised to room temperature, followed by stirring overnight. The solvent was distilled under reduced pressure and dissolved in CH ₂ Cl ₂ To remove solids. The solution was concentrated under reduced pressure, and the obtained solid was purified with toluene and CH ₂ Cl ₂ Washed to obtain dimethylsilyl-bis (4-phenyl-2-methyl-1H-inden-1-yl) zirconium dichloride (260 mg,10%, r/m about 16/1) as a racemic-rich yellow solid.

< preparation of Supported catalyst >

Example 1: preparation of composite supported metallocene catalyst

First, silica (SP 952 manufactured by Grace Davison) was dehydrated and dried under vacuum at a temperature of 250 ℃ for 12 hours to prepare a support.

Then, 3.0kg of toluene solution was charged into a 20L high pressure stainless steel (sus) reactor, 1000g of silica (Grace Davison, SP 952) prepared in advance was added thereto, and the reactor temperature was raised to 40℃while stirring. After the silica was well dispersed for 60 minutes, 8kg of a 10 wt% Methylaluminoxane (MAO)/toluene solution was added, and the mixture was slowly reacted under stirring at 200rpm for 12 hours. Thereafter, the temperature of the reactor was increased to 60℃and then 0.1mmol of the first metallocene compound prepared in Synthesis example 1 dissolved in toluene in the form of a solution was added. The reaction mixture was then reacted at 50℃for 2 hours with stirring at 200 rpm.

After the completion of the reaction, 0.05mmol of the second metallocene compound prepared in Synthesis example 3 was dissolved in toluene and reacted at 50℃for 2 hours with stirring at 200 rpm.

When the reaction was completed, stirring was stopped, and the reaction solution was decanted after standing for 30 minutes. After washing with a sufficient amount of toluene, 50mL of toluene was added again. Then, stirring was stopped after 10 minutes, and washing was performed with a sufficient amount of toluene to remove the compounds that did not participate in the reaction. Thereafter, 3.0kg of hexane was added to the reactor and stirred, and the hexane slurry was transferred to a filter for filtration.

The composite supported metallocene catalyst was obtained by drying under reduced pressure at room temperature for 5 hours and then drying under reduced pressure at 50℃for 4 hours.

Example 2: preparation of composite supported metallocene catalyst

A composite supported metallocene catalyst was produced in the same manner as in example 1, except that 0.2mmol of the metallocene compound produced in Synthesis example 1 and 0.05mmol of the metallocene compound produced in Synthesis example 4 were each added.

Example 3: preparation of composite supported metallocene catalyst

A composite supported metallocene catalyst was produced in the same manner as in example 1, except that 0.08mmol of the metallocene compound produced in Synthesis example 2 and 0.08mmol of the metallocene compound produced in Synthesis example 3 were each added.

Example 4: preparation of composite supported metallocene catalyst

A composite supported metallocene catalyst was produced in the same manner as in example 1, except that 0.1mmol of the metallocene compound produced in Synthesis example 1 and 0.05mmol of the metallocene compound produced in Synthesis example 5 were each added.

Comparative example 1: preparation of composite supported metallocene catalyst

A composite supported metallocene catalyst was produced in the same manner as in example 1, except that 0.1mmol of the metallocene compound produced in comparative Synthesis example 1 and 0.05mmol of the metallocene compound produced in Synthesis example 3 were each added.

Comparative example 2: preparation of composite supported metallocene catalyst

A composite supported metallocene catalyst was produced in the same manner as in example 1, except that 0.1mmol of the metallocene compound produced in comparative Synthesis example 2 and 0.05mmol of the metallocene compound produced in Synthesis example 3 were each added.

Comparative example 3: preparation of composite supported metallocene catalyst

A composite supported metallocene catalyst was produced in the same manner as in example 1, except that 0.1mmol of the metallocene compound produced in comparative Synthesis example 3 and 0.05mmol of the metallocene compound produced in Synthesis example 3 were each added.

Comparative example 4: preparation of composite supported metallocene catalyst

A composite supported metallocene catalyst was produced in the same manner as in example 1, except that 0.1mmol of the metallocene compound produced in Synthesis example 2 and 0.05mmol of the metallocene compound produced in comparative Synthesis example 4 were each added.

Comparative example 5: preparation of composite supported metallocene catalyst

A composite supported metallocene catalyst was produced in the same manner as in example 1, except that the metallocene compound (catalyst G) produced in comparative Synthesis example 5 was added as a second precursor, namely a second metallocene compound, in place of the metallocene compound produced in Synthesis example 3.

< test example >

Test example 1: preparation of polyethylene

Ethylene-1-hexene was slurry polymerized in the presence of the supported catalyst prepared in one of the examples and comparative examples under the conditions shown in table 1 below.

At this time, a continuous polymerization reactor of isobutane (i-C4) loop slurry process (slurry loop process) was used, the reactor volume was 140L, and the reaction flow rate was about 7m/s. The gases required for the polymerization (ethylene, hydrogen) and 1-hexene as comonomer are continuously added and the flow rate is adjusted according to the desired product. The concentrations of all gases and comonomer (1-hexene) were confirmed by an on-line gas chromatograph. The supported catalyst was introduced into the isobutane slurry, the reactor pressure was maintained at about 40 bar and the polymerization temperature was about 85 ℃.

TABLE 1

/>

Test example 2: evaluation of the Activity of the composite Supported catalyst, process stability and physical Properties of polyethylene

The activities, process stability and physical properties of the polyethylene copolymers of examples and comparative examples were measured by the following methods, and the results are shown in table 2 below.

(1) Activity (kg PE/g. Cat. Hr)

It is calculated as the ratio of the weight of the polyethylene copolymer produced per unit time (h) (kg PE) to the weight of the supported catalyst used (g.Cat).

(2) Melt index (g/10 min, MI)

Melt index (MI _2.16 ) Measured at 190℃under a load of 2.16kg according to ASTM D1238 and expressed as the weight (g) of the polymer melted for 10 minutes.

(3) Density of

Density (g/cm) was measured according to ASTM D792 ³ )。

(4) Bulk Density (BD)

Bulk density was measured according to ASTM D1895.

(5) Process stability depending on whether fouling is occurring or not

In the process of preparing the polyethylene copolymer, it was checked whether or not fouling occurred, i.e., whether or not solid products and the like were entangled on the internal devices and walls of the reactor. Thereafter, when no fouling occurred, the process stability was rated as "good". On the other hand, when fouling occurred, the process stability was rated as "poor". The results are shown in table 2 below.

(6) Dart impact strength

Polyethylene copolymer films (BUR 2.3, film thickness 48 to 52 μm) were prepared using a film coater, and the dart impact strength of each film sample was measured more than 20 times in accordance with ASTM D1709[ method a ], and averaged.

TABLE 2

As shown in table 2, it can be seen that the examples of the present invention ensure excellent process stability and high polymerization activity in ethylene polymerization reaction while having high comonomer incorporation performance, since the specific composite supported catalysts of examples 1 to 4 are used, compared to the composite supported catalysts of comparative examples 1 to 5. In addition, it can be seen that embodiments of the present invention can provide a low density polyethylene copolymer for preparing a film having excellent processability as well as high mechanical properties and dart impact resistance.

Claims

1. A composite supported metallocene catalyst comprising

At least one first metallocene compound selected from the group consisting of compounds represented by the following chemical formula 1;

at least one second metallocene compound selected from the group consisting of compounds represented by the following chemical formula 2; and

a support carrying a first metallocene compound and a second metallocene compound:

[ chemical formula 1]

(Cp ¹ R ^a ) _n (Cp ² R ^b )M ¹ Q ¹ _3-n

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

M ¹ is a group 4 transition metal;

R ^a and R is ^b Are identical or different from each other and are each independently hydrogen, C _1-20 Alkyl, C _1-20 Alkoxy, C _2-20 Alkoxyalkyl, C _6-20 Aryl, C _6-20 Aryloxy, C _2-20 Alkenyl, C _7-40 Alkylaryl, C _7-40 Arylalkyl, C _8-40 Arylalkenyl or C _2-10 Alkynyl, provided that R ^a And R is ^b At least one of which is not hydrogen;

n is 1;

[ chemical formula 2]

In the chemical formula 2, the chemical formula is shown in the drawing,

M ² is a group 4 transition metal;

a is carbon (C), silicon (Si) or germanium (Ge);

D ¹ and D ² Is oxygen;

R ¹ and R is ² Are identical or different from each other and are each independently C _1-20 Alkyl, C _2-20 Alkenyl, C _6-20 Aryl, C _7-40 Alkylaryl or C _7-40 An arylalkyl group; and is also provided with

2. The composite supported metallocene catalyst of claim 1, wherein

M ¹ Is zirconium (Zr) or hafnium (Hf),

Cp ¹ and Cp ² Each independently is a cyclopentadienyl, indenyl, or fluorenyl group;

R ^a and R is ^b Each independently is hydrogen, C _1-6 Straight-chain or branched alkyl, C _2-6 Alkynyl, substituted with C _1-6 C of alkoxy groups _1-6 Alkyl, substituted with C _6-12 C of aryl groups _1-6 Alkyl, or C _6-12 Aryl, provided that R ^a And R is ^b At least one of which is not hydrogen; and is also provided with

Q ¹ Each independently is halogen.

3. The composite supported metallocene catalyst of claim 1, wherein the first metallocene compound is represented by any one of the following structural formulas:

4. the composite supported metallocene catalyst of claim 1, wherein

M ² Is zirconium (Zr) or hafnium (Hf),

a is silicon (Si), and

X ¹ and X ² Each independently is halogen.

5. The composite supported metallocene catalyst of claim 1, wherein

L ¹ And L ² Each independently is C _1-3 An alkylene group;

R ¹ and R is ² Each independently is C _1-6 Straight-chain or branched alkyl or C _6-12 Aryl groups.

6. The composite supported metallocene catalyst of claim 1, wherein R ³ And R is ⁴ Each independently is C _1-6 An alkyl group.

7. The composite supported metallocene catalyst of claim 1, wherein the second metallocene compound is represented by any one of the following structural formulas:

8. the composite supported metallocene catalyst of claim 1, wherein the first metallocene compound and the second metallocene compound are supported in a molar ratio of 0.3:1 to 4:1.

9. The composite supported metallocene catalyst according to claim 1, wherein the support contains hydroxyl groups and siloxane groups on its surface.

10. The composite supported metallocene catalyst of claim 9, wherein the support is at least one selected from the group consisting of silica, silica-alumina, and silica-magnesia.

11. A process for preparing a polyethylene copolymer comprising the step of copolymerizing ethylene and an α -olefin in the presence of the composite supported metallocene catalyst of claim 1.

12. The method for producing a polyethylene copolymer according to claim 11, wherein the copolymerizing step is performed by reacting the α -olefin in an amount of 0.45 mol or less based on 1 mol of the ethylene.

13. The method for preparing a polyethylene copolymer according to claim 11, wherein the α -olefin is at least one selected from the group consisting of 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosene.

14. A polyethylene copolymer obtainable by the process of claim 11, wherein the polyethylene copolymer is an ethylene-1-hexene copolymer and has a melt index MI measured according to ASTM D1238 at 190 ℃ under a load of 2.16kg _2.16 0.5g/10min to 2.0g/10min, and

wherein a polyethylene copolymer film produced using a film applicator has a dart impact strength of 1700g or more, as measured according to ASTM D1709, and the polyethylene copolymer film has a BUR of 2.3 and a film thickness of 48 μm to 52 μm.

15. The polyethylene copolymer according to claim 14, wherein the bulk density measured according to ASTM D1895 is 0.2g/mL or more.

16. The polyethylene copolymer of claim 14, wherein the melt index MI measured according to ASTM D1238 at 190 ℃ under a load of 2.16kg _2.16 From 0.7g/10min to 2.0g/10min, a bulk density of 0.4g/mL or more as measured according to ASTM D1895, and

wherein a polyethylene copolymer film prepared using a film applicator has a dart impact strength of 1700g or more, measured according to ASTM D1709, the film having a BUR of 2.3 and a film thickness of 48 μm to 52 μm.