TWI545127B - Methods for preparing copolymers of ethylene and α-olefins using advanced transition metal catalytic systems - Google Patents

Description

Method for preparing a copolymer of ethylene and an α-olefin using an advanced transition metal catalyst system

The present invention relates to a homogeneous catalytic system for preparing an ethylene homopolymer or a copolymer of ethylene and an α-olefin; more particularly, a Group 4 transition metal catalyst in which a Group 4 transition metal is The cyclopentadienyl derivative and an electron-donating substituent are cross-linked, and the 3,4 position of the cyclopentadienyl derivative is substituted with an alkyl group. Furthermore, the present invention relates to a catalytic system comprising such a transition metal catalyst and a cocatalyst comprising one or more selected from the group consisting of an aluminoxane and a boron compound; the present invention is also directed to a process for preparing the catalyst system A method of ethylene homopolymer or a copolymer of ethylene and an alpha olefin.

In the past, a catalyst system called "Ziegler-Natta" was generally used to prepare an ethylene homopolymer or a copolymer with an α-olefin. The catalytic system contains a titanium as a main catalyst. Or a vanadium compound and an alkyl aluminum compound as a cocatalyst. Although the Ziegler-Natta catalytic system is highly active for the polymerization of ethylene, it has a non-uniform active site, resulting in a broad molecular weight distribution of the polymer produced; especially in ethylene and alpha-olefins. The copolymerization will have a non-uniform composition distribution.

Recently, a metallocene catalytic system has been developed which is composed of a metallocene compound of a Group 4 transition metal (e.g., titanium, zirconium, hafnium, etc.) in a periodic table and a cocatalyst (e.g., methyl aluminoxane). composition. Since the metallocene catalyst system is a homogeneous catalyst with a single active site, it can be used to prepare a narrower molecular weight distribution and more uniform than in the case of a conventional Ziegler-Natta catalytic system. Composition of the distribution of polyethylene. For example, European Patent Application Publication Nos. 320,762 and 3,726,325, Japanese Patent Laid-Open Publication No. Sho 63-092621 (Sho. 63-092621), and Japanese Patent Laid-Open Publication No. 02-84405 (Hei. 02-84405) and Diping 03-2347 (Hei. 03-2347) both disclose metallocene compounds, such as Cp ₂ TiCl ₂ , Cp ₂ ZrCl ₂ , Cp ₂ ZrMeCl, Cp ₂ ZrMe ₂ , ethylene (IndH _{4 2} ZrCl ₂ or the like, which is activated by a methylaluminoxane co-catalyst, and is highly polymerized by ethylene, thereby preparing a polyethylene having a molecular weight distribution (Mw/Mn) of 1.5 to 2.0. However, such a catalytic system is difficult to obtain a high molecular weight polymer. In particular, when it is applied to solution polymerization at a high temperature of at least 140 ° C, the polymerization activity is drastically reduced and mainly undergoes β-dehydrogenation. Therefore, it is understood that such a catalytic system is not suitable for preparing a weight average. A high molecular weight polymer having a molecular weight (Mw) of 100,000 or more.

U.S. Patent No. 5,084,534 (issued to Exxon) discloses the preparation of a copolymer having a narrow molecular weight distribution and a uniform composition distribution of from 1.8 to 3.0 by using (n-BuCp) ₂ ZrCl ₂ catalyst at 150 to 200 ° C. And a methylaluminoxane co-catalyst to polymerize ethylene alone or to polymerize ethylene with 1-hexene or 1-octene. In addition, European Patent No. 0416815 and No. 0420436 (owned by Dow Corporation) also disclose a catalyst whose structure is geometrically controlled by linking a cyclic amidino group to a cyclopentadienyl ligand, and It exhibits high catalytic activity when polymerizing ethylene alone or polymerizing ethylene and α-olefin under the conditions of slurry polymerization or solution polymerization, and can simultaneously increase the high reactivity with the comon, and thus can be used for preparing a uniform composition distribution. High molecular weight polymer. However, in the metallocene catalyst, the catalytic stability of the above catalyst and the comonomer are contained in a high-temperature solution polymerization condition of at least 140 ° C, which is proportionally greatly deteriorated as the temperature rises, and thus is caused by a high material. The cost is reduced, and the economic benefits are reduced, making it difficult to industrialize.

In view of the gist of the present invention, the inventors of the present invention conducted intensive and thorough research to solve the problems faced in the prior art, and found a geometrically constrained catalyst in which a Group 4 transition metal is a cyclopentadienyl derivative and a The cross-linking of the electron-donating substituent surrounds the 3,4 position of the cyclopentadienyl derivative via an alkyl group, and the catalyst can significantly enhance the conjugation of the comon, making it suitable for use at temperatures of at least 140 ° C. A solution of ethylene having a high molecular weight and high activity or a copolymer of an elastic ethylene and an α-olefin is prepared by solution polymerization.

Accordingly, it is an object of the present invention to provide a catalyst having a single active site which exhibits superior thermal stability and which enhances the co-monomers; and also provides a high temperature solution polymerization process using such a catalyst. From the industrial point of view, it is easy to produce an ethylene homopolymer having various characteristics or a copolymer of ethylene and an α-olefin.

In one aspect, in order to achieve the above object, the present invention provides a transition metal compound represented by the following Chemical Formula 1, wherein a Group 4 transition metal in the periodic table of the central metal is a cyclopentadiene derivative and an electron donor The substituent is crosslinked and the cyclopentadiene derivative is substituted with an alkyl group at the 3,4 position. Furthermore, the present invention also provides a catalyst composition comprising the above transition metal compound and a cocatalyst selected from the group consisting of an aluminum compound, a boron compound and a mixture thereof; and providing a catalyst A composition for preparing an ethylene homopolymer or a copolymer of ethylene and an α-olefin.

Wherein M is a Group 4 transition metal in the periodic table; R ¹ and R ² are independently a (C1-C7) alkyl group; D is -O-, -S-, -N(R ⁵ )- or - P(R ⁶ )-, wherein R ⁵ and R ⁶ are independently a hydrogen atom, (C1-C20)alkyl, (C3-C20)cycloalkyl, (C6-C30)aryl, (C6-C30) aryl a (C1-C20)alkyl group, a (C1-C20)alkylcarbonyl group, or a (C3-C20)cycloalkylcarbonyl group; R ³ and R ⁴ are independently a hydrogen atom, (C1-C20)alkyl group, (C6 -C30) aryl, (C6-C30) aryl (C1-C20) alkyl, (C1-C20) alkoxy, or substituted by (C1-C20)alkyl or (C3-C20)cycloalkyl Alkoxy; X is independently a halogen atom; (C1-C20)alkyl; (C6-C30) aryl; (C6-C30) aryl (C1-C20) alkyl; (C1-C20) alkoxy Alkyloxy substituted by (C1-C20)alkyl or (C3-C20)cycloalkyl; via (C1-C20)alkyl, (C6-C30)aryl, (C6-C30)aryl (C1 -C20)Alkyl or tri(C1-C20)alkylfluorenyl substituted amine; (C1-C20)alkyl, (C6-C30)aryl, (C6-C30)aryl (C1-C20) Alkyl or tri(C1-C20)alkylindenyl substituted guanamine; (C1-C20)alkyl, (C6-C30)aryl, (C6-C30)aryl(C1-C20)alkyl Or a tris(C1-C20)alkylindenyl substituted phosphino group; or via (C1-C20) An alkyl group, a (C6-C30) aryl group, a (C6-C30) aryl (C1-C20) alkyl group or a tris(C1-C20)alkylfluorenyl substituted phosphido group, which does not contain X It is a derivative of cyclopentadiene; ² in the alkyl group R ¹ and R; R ³ and R ⁴ are the alkyl, aryl, arylalkyl and alkoxy; R ⁵ and R ⁶ in the An alkyl group, a cycloalkyl group, an aryl group, an arylalkyl group, an alkylcarbonyl group and a cycloalkylcarbonyl group; the alkyl group, the aryl group, the arylalkyl group and the alkoxy group in X may be further selected from (C1- C20) one or more of an alkyl group, a (C3-C20) cycloalkyl group, a (C6-C30) aryl group, and a (C6-C30) aryl (C1-C20) alkyl group; and n is a 1 to An integer of 4.

In another aspect, the present invention provides a transition metal catalyst composition for preparing an ethylene homopolymer or a copolymer of ethylene and an α-olefin, comprising the foregoing transition metal compound and one selected from the group consisting of an aluminum compound, a boron compound, and the foregoing a cocatalyst of the mixture; and an ethylene homopolymer or a copolymer of ethylene and an α-olefin obtained by using the transition metal compound or the catalyst composition.

The invention will be described in detail below. In particular, M is preferably titanium, zirconium or hafnium. Meanwhile, R ¹ and R ² independently located at the 3, 4 position of the cyclopentadienyl group (which can form a η ⁵ bond with M) are (C1-C7) alkyl groups such as methyl, ethyl, n-propyl and iso A propyl group, a n-butyl group, a secondary butyl group, a tert-butyl group or a n-pentyl group is particularly useful as a methyl group.

Meanwhile, R ⁵ and R ⁶ are independently a hydrogen atom, a (C1-C20) alkyl group, a (C3-C20) cycloalkyl group, a (C6-C30) aryl group, or a (C6-C30) aryl group (C1-C20). Alkyl, (C1-C20)alkylcarbonyl, or (C3-C20)cycloalkylcarbonyl, more specifically methyl, ethyl, n-propyl, isopropyl, secondary butyl, tert-butyl , cyclohexyl, dicyclohexylmethyl, adamantyl group, phenyl, phenylmethyl, methylcarbonyl, ethylcarbonyl, n-propylcarbonyl, isopropylcarbonyl, tert-butylcarbonyl, Or adamantylcarbonyl. Particularly useful is a tertiary butyl group.

Meanwhile, R ³ and R ⁴ bonded to Si are independently a hydrogen atom, a (C1-C20) alkyl group, a (C6-C30) aryl group, a (C6-C30) aryl group (C1-C20) alkyl group, ( C1-C20) alkoxy group, or an oxiranyl group substituted by (C1-C20) alkyl group or (C3-C20) cycloalkyl group; examples of (C1-C20) alkyl group containing methyl group, ethyl group, positive Propyl, isopropyl, n-butyl, secondary butyl, tert-butyl, n-pentyl, neopentyl, amyl group, n-hexyl, n-octyl, n-decyl, n-xyl Alkyl, n-pentadecyl, or n-icosyl, particularly useful as methyl, ethyl, isopropyl, tert-butyl, or pentyl; (C6-C30) aryl or (C6- C30) Examples of aryl (C1-C20) alkyl groups include benzyl, (2-methylphenyl)methyl, (3-methylphenyl)methyl, (4-methylphenyl)methyl, (2,3-dimethylphenyl)methyl, (2,4-dimethylphenyl)methyl, (2,5-dimethylphenyl)methyl, (2,6-dimethyl Phenyl)methyl, (3,4-dimethylphenyl)methyl, (4,6-dimethylphenyl)methyl, (2,3,4-trimethylphenyl)methyl, (2,3,5-trimethylphenyl)methyl, (2,3,6-trimethylphenyl)methyl, (3,4,5-trimethylphenyl)methyl, (2 ,4,6-trimethyl Methyl, (2,3,4,5-tetramethylphenyl)methyl, (2,3,4,6-tetramethylphenyl)methyl, (2,3,5,6- Tetramethylphenyl)methyl, (pentamethylphenyl)methyl, (ethylphenyl)methyl, (n-propylphenyl)methyl, (isopropylphenyl)methyl, (positive Butylphenyl)methyl, (secondary butylphenyl)methyl, (tris-butylphenyl)methyl, (n-pentylphenyl)methyl, (neopentylphenyl)methyl, (n-hexylphenyl)methyl, (n-octylphenyl)methyl, (n-decylphenyl)methyl, (n-dodecylphenyl)methyl, (n-tetradecylphenyl) Methyl, naphthylmethyl, or lysylmethyl, particularly useful as benzyl; examples of (C1-C20) alkoxy include methoxy, ethoxy, n-propoxy, isopropoxy , n-butoxy, 2,4-butoxy, tert-butoxy, n-pentyloxy, neopentyloxy, n-hexyloxy, n-octyloxy, n-dodecyloxy, n-pentadecanyloxy Or n-esadecyloxy, particularly useful as methoxy, ethoxy, isopropoxy or tert-butoxy; via (C1-C20)alkyl or (C3-C20)cycloalkyl Examples of substituted methoxy groups include trimethyl methoxy, triethyl Base oxy, tri-n-propyl decyloxy; triisopropyl decyloxy, tri-n-butyl decyloxy; tri-n-butyl decyloxy, tri-tertiary butyl fluorenyloxy , tri-isobutyl decyloxy, tert-butyl dimethyl methoxy oxy, tri-n-pentyl decyloxy, tri-n-hexyl decyloxy, or tricyclohexyl decyloxy, particularly useful Trimethyl decyloxy or tert-butyl dimethyl decyloxy.

X is independently a halogen atom; (C1-C20) alkyl; (C6-C30) aryl; (C6-C30) aryl (C1-C20) alkyl; (C1-C20) alkoxy; -C20)alkyl or (C3-C20)cycloalkyl substituted oxirane; (C1-C20)alkyl, (C6-C30) aryl, (C6-C30) aryl (C1-C20) alkane Amino group substituted with a tris(C1-C20)alkylfluorenyl group; via (C1-C20)alkyl, (C6-C30)aryl, (C6-C30)aryl(C1-C20)alkyl or tri (C1-C20)alkylmercapto-substituted guanamine; via (C1-C20)alkyl, (C6-C30)aryl, (C6-C30)aryl(C1-C20)alkyl or tri(C1) -C20)alkylthio-substituted phosphino group; or via (C1-C20)alkyl, (C6-C30)aryl, (C6-C30)aryl(C1-C20)alkyl or tri(C1-C20 An alkylphosphonium-substituted phosphorus bridging group in which the case where X is a cyclopentadienyl derivative is not included. Examples of the halogen atom include fluorine, chlorine, bromine or iodine; examples of the (C1-C20) alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, secondary butyl, and tertiary Butyl, n-pentyl, neopentyl, pentyl, n-hexyl, n-octyl, n-decyl, n-dodecyl, n-pentadecyl, or n-icosyl, particularly useful as methyl , ethyl, isopropyl, tert-butyl or pentyl; (C6-C30) aryl (C1-C20) alkyl examples include benzyl, (2-methylphenyl)methyl, ( 3-methylphenyl)methyl, (4-methylphenyl)methyl, (2,3-dimethylphenyl)methyl, (2,4-dimethylphenyl)methyl, ( 2,5-Dimethylphenyl)methyl, (2,6-dimethylphenyl)methyl, (3,4-dimethylphenyl)methyl, (4,6-dimethylbenzene Methyl, (2,3,4-trimethylphenyl)methyl, (2,3,5-trimethylphenyl)methyl, (2,3,6-trimethylphenyl) Methyl, (3,4,5-trimethylphenyl)methyl, (2,4,6-trimethylphenyl)methyl, (2,3,4,5-tetramethylphenyl) Methyl, (2,3,4,6-tetramethylphenyl)methyl, (2,3,5,6-tetramethylphenyl)methyl, (pentamethylphenyl)methyl, ( Ethylphenyl)methyl, (positive C Phenyl)methyl, (isopropylphenyl)methyl, (n-butylphenyl)methyl, (secondary butylphenyl)methyl, (tri-butylphenyl)methyl, (positive Butyl phenyl)methyl, (neopentylphenyl)methyl, (n-hexylphenyl)methyl, (n-octylphenyl)methyl, (n-decylphenyl)methyl, (正癸Phenyl)methyl, (n-tetradecylphenyl)methyl, naphthylmethyl, or lysylmethyl, particularly useful as benzyl; examples of (C1-C20) alkoxy include A Oxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, di-butoxy, tert-butoxy, n-pentyloxy, neopentyloxy, n-hexyloxy, n-octyl Oxyl, n-dodecyloxy, n-pentadecanyloxy, or n-esotecyloxy, particularly useful as methoxy, ethoxy, isopropoxy or tert-butoxy; Examples of (C1-C20)alkyl or (C3-C20)cycloalkyl-substituted anthraceneoxy groups include trimethyldecyloxy, triethyldecyloxy, tri-n-propyldecyloxy, triiso Propyl decyloxy, tri-n-butyl decyloxy, tri-n-butyl decyloxy, tri-tert-butyl decyloxy, tri-isobutyl decyloxy, tertiary butyl Dimethyl methoxy, tri-n-pentyl decyloxy, tri-n-hexyl decyloxy, or tricyclohexyl decyloxy, particularly useful as trimethyl decyloxy or tert-butyl dimethyl Alkoxy; an amine group substituted with (C1-C20)alkyl, (C6-C30)aryl, (C6-C30)aryl(C1-C20)alkyl or tri(C1-C20)alkyldecyl Examples include dimethylamino, diethylamino, di-n-propylamino, diisopropyl Amino, di-n-butylamino, di-secondary butylamino, di-tertiary butylamino, diisobutylamino, tert-butyl isopropylamino, di-n-hexyl Amino, di-n-octylamino, di-n-decylamino, diphenylamino, dibenzylamino, methylethylamino, methylphenylamino, benzylhexylamino , bistrimethyldecylamino or di-tert-butyldimethylmercaptoamine, particularly useful as dimethylamino or diethylamino; via (C1-C20)alkyl, Examples of C6-C30) aryl, (C6-C30) aryl (C1-C20) alkyl or tri(C1-C20)alkyl fluorenyl substituted guanamine groups include dibenzyl guanylamino, methyl Ethyl decylamino, methylphenyl decylamino, or benzylhexyl decylamino, particularly useful as diphenylguanidinyl; via (C1-C20)alkyl, (C6-C30)aryl, Examples of (C6-C30) aryl (C1-C20) alkyl or tri(C1-C20)alkylfluorenyl substituted phosphino groups include dimethylphosphino, diethylphosphino, di-n-propyl Phosphyl, diisopropylphosphino, di-n-butylphosphino, di-tertiary butylphosphino, di-tertiary butylphosphino, diisobutylphosphino, tert-butyl isopropyl phosphine , bis-n-hexylphosphino, di-n-octylphosphino, di-n-decylphosphino, diphenylphosphino, dibenzylphosphino, methylethylphosphino, methylphenylphosphino , benzylhexylphosphino, ditrimethyldecylphosphino or di-tert-butyldimethylmethylphosphino; (C1-C20)alkyl, (C6-C30)aryl, (C6- C30) Examples of aryl (C1-C20) alkyl or (C1-C20)alkylfluorenyl substituted phosphorus bridging groups include dibenzylphosphonium bridging, methylethylphosphoryl bridging, methylphenylphosphorus A bridging group, a benzylhexylphosphoryl bridging group or a ditrimethylphosphonium phosphorus bridging group.

Meanwhile, n is an integer of 1 to 4, which is selected from the oxidation number of the transition metal, preferably an integer of 1 or 2.

The present invention provides an ethylene homopolymer or a copolymer of ethylene and an α-olefin obtained by using the transition metal compound as a catalyst.

On the other hand, in order to use the transition metal compound of Chemical Formula 1 as a catalyst component for activating olefin polymerization, when the ligand X in the transition metal compound of the present invention is separated and the center metal is cationized, a boron compound is used. The aluminum compound or the aforementioned mixture as a cocatalyst corresponds to a central ion (i.e., an anion) having a weak bonding ability. In this regard, in the case where the ligand X is a halogen, the aluminum compound responsible for removing a small amount of a polar material (for example, water as a catalytic poison) may function as an alkylating agent.

For use as a cocatalyst in the present invention, the boron compound may be selected from the following chemical formulas 2, 3 and 4, as disclosed in U.S. Patent No. 5,198,401.

[Chemical Formula 2]

B(R ⁷ ) ₃

[Chemical Formula 3]

[R ⁸ ] ⁺ [B(R ⁷ ) ₄ ] ^-

[Chemical Formula 4]

[(R ⁹ ) _q ZH] ⁺ [B(R ⁷ ) ₄ ] ^-

In Chemical Formulas 2 to 4, B is a boron atom; R ⁷ is a phenyl group, wherein the phenyl group may be further substituted with three to five substituents selected from the group consisting of a fluorine atom, a fluorine substitution or an unsubstituted a (C1-C20) alkyl group and a fluorine-substituted or unsubstituted (C1-C20) alkoxy group; R ⁸ is a (C5-C7) cycloalkyl radical, (C1-C20) alkyl group (C6- C20) an aryl radical or a (C6-C30) aryl (C1-C20) alkyl radical such as a triphenylmethyl radical; Z is a nitrogen atom or a phosphorus atom; and R ⁹ is a (C1-C20) alkane a radical or an aniline radical substituted with two (C1-C4) alkyl groups and a nitrogen atom; and q is an integer of 2 or 3.

Preferred examples of the boron-based co-catalyst include one or more selected from the group consisting of tris(pentafluorophenyl)borane, tris(2,3,5,6-tetrafluorophenyl)borane, Tris(2,3,4,5-tetrafluorophenyl)borane, tris(3,4,5-trifluorophenyl)borane, tris(2,3,4-trifluorophenyl)borane, Phenyl bis(pentafluorophenyl)borane, tetrakis(pentafluorophenyl)borate, tetrakis(2,3,5,6-tetrafluorophenyl)borate, tetrakis (2,3,4,5- Tetrafluorophenyl)borate, tetrakis(3,4,5-trifluorophenyl)borate, tetrakis(2,2,4-trifluorophenyl)borate, phenylbis(pentafluorophenyl)borate Salt and tetrakis(3,5-ditrifluoromethylphenyl)borate, the specific combinations of the foregoing examples include ferrocene tetrakis(pentafluorophenyl)borate, 1,1'-dimethylferrocene Tetrakis(pentafluorophenyl)borate, tetrakis(pentafluorophenyl)borate, triphenylmethyltetrakis(pentafluorophenyl)borate, triphenylmethyltetrakis(3,5-ditrifluoromethyl) Phenyl)borate, triethylammonium tetrakis(pentafluorophenyl)borate, tripropylammonium tetrakis(pentafluorophenyl)borate, tris(n-butyl)ammonium tetrakis(pentafluorophenyl)borate Salt, tri(n-butyl)ammonium tetrakis(3,5-ditrifluoromethylphenyl)borate, N,N-dimethylanilinium tetrakis(pentafluorobenzene) Borate, N,N-diethylanilinium tetrakis(pentafluorophenyl)borate, N,N-2,4,6-pentamethylanilinium tetrakis(pentafluorophenyl)borate, N, N-dimethylanilinium tetrakis(3,5-ditrifluoromethylphenyl)borate, diisopropylammonium tetrakis(pentafluorophenyl)borate, dicyclohexylammonium tetrakis(pentafluorophenyl) Borate, triphenylsulfonium tetrakis(pentafluorophenyl)borate, tris(methylphenyl)phosphonium tetrakis(pentafluorophenyl)borate, or tris(dimethylphenyl)phosphonium tetrakis(pentafluorobenzene) Boronate, particularly useful as N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, triphenylmethyltetrakis(pentafluorophenyl)borate or tris(pentafluorophenyl) Borane.

The aluminum compound used in the present invention may comprise an aluminoxane compound of the following Chemical Formula 5 or 6, an organoaluminum compound of the following Chemical Formula 7 or an organoaluminum based oxide compound of the following Chemical Formula 8 or 9.

[Chemical Formula 5] (-Al(R ¹⁰ )-O-) _m

[Chemical Formula 6]

(R ¹⁰ ) ₂ Al-(-O(R ¹⁰ )-) _p -(R ¹⁰ ) ₂

[Chemical Formula 7]

(R ¹¹ ) _r Al(E) _3-r

[Chemical Formula 8]

(R ¹² ) ₂ AlOR ¹³

[Chemical Formula 9]

R ¹² Al(OR ¹³ ) ₂

In Chemical Formulas 5 to 9, R ¹⁰ is a linear or non-linear (C1-C20) alkyl group, preferably a methyl group or an isobutyl group; m and p are independently an integer of 5 to 20; R ¹¹ and R ¹² is independently (C1-C20)alkyl; E is a hydrogen atom or a halogen atom; r is an integer of from 1 to 3; and R ¹³ is (C1-C20)alkyl or (C6-C30)aryl.

For use as a cocatalyst, the aluminum compound is one or more selected from the group consisting of aluminoxane and organoaluminum, and the aluminoxane compound may comprise methylaluminoxane, modified methyl aluminoxane or tetraiso Butyl aluminoxane; and the organoaluminum compound is selected from the group consisting of trialkyl aluminum, dialkyl aluminum chloride, alkyl aluminum dichloride, and dialkyl aluminum hydride. Specific examples of the organoaluminum compound include: trialkyl aluminum containing trimethyl aluminum, triethyl aluminum, tripropyl aluminum, triisobutyl aluminum, and trihexyl aluminum; containing dimethyl aluminum chloride, diethyl Base aluminum chloride, dipropyl aluminum chloride, diisobutyl aluminum chloride and dihexyl aluminum chloride dialkyl aluminum chloride; containing methyl aluminum dichloride, ethyl aluminum dichloride, C Alkali aluminum dichloride, isobutyl aluminum dichloride and alkyl aluminum dichloride of hexyl aluminum dichloride; and dimethyl aluminum hydride, diethyl aluminum hydride, dipropyl aluminum hydride a dialkyl aluminum hydride of diisobutylaluminum and dihexylaluminum hydride, particularly useful as a trialkylaluminum, more preferably triethylaluminum or triisobutylaluminum, wherein the central transition metal ( M) The molar ratio of aluminum atoms (Al) is 1:50 to 5,000.

With respect to the ratio of the transition metal compound to the cocatalyst, the molar ratio of the central transition metal (M) to the boron atom (B) to the aluminum atom (Al) is from 1:0.1 to 100:10 to 1,000, more preferably 1 : 0.5 to 5:25 to 500. Ethylene homopolymers or copolymers of ethylene and alpha-olefins may be prepared in the above ranges, which may vary depending on the purity of the reaction.

In another aspect, the present invention provides an ethylene homopolymer or a copolymer of ethylene and an α-olefin obtained by using the transition metal compound as a catalyst composition, which is produced in a solution phase by The transition metal compound, the cocatalyst, and the ethylene or alpha-olefin comon are contacted with one another in the presence of a suitable solvent. In this regard, the transition metal compound and the co-catalyst component may be separately added to the reactor, or the components may be previously mixed and introduced into the reactor.

The organic solvent used in the production method is preferably a (C3-C20) hydrocarbon, and specific examples thereof include butane, isobutane, pentane, hexane, heptane, octane, isooctane, decane, hydrazine. Alkanes, dodecane, cyclohexane, methylcyclohexane, benzene, toluene and xylene.

Specifically, in the preparation of the ethylene homopolymer, an ethylene monomer can be used alone, and the ethylene pressure in the present invention is from 1 to 1,000 atm., preferably from 10 to 150 atm. When the pressure falls within the above range, a reactor made of a thin material can be used without additional compression treatment, thereby generating economic benefits and increasing polymer yield. The polymerization temperature is from 60 to 300 ° C, preferably from 80 to 250 ° C. If the polymerization temperature is 80 ° C or higher, a low density polymer can be obtained by enhancing the comonomer. On the other hand, if the polymerization temperature is 250 ° C or lower, the conversion of ethylene into a polymer can be increased, thereby obtaining a polymer having a high density.

Meanwhile, in the method of using the transition metal catalyst composition to prepare an ethylene homopolymer or a copolymer of ethylene and an α-olefin, the eupolymer polymerized with ethylene may comprise an α-olefin of a (C3-C18) hydrocarbon, Preferably, it is selected from the group consisting of propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-111 Alkene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and eicosene. More specifically, 1-butene, 1-hexene, 1-octene or 1-decene can be copolymerized with ethylene. In this case, it is preferred that the ethylene pressure and the polymerization temperature are the same as those for preparing the high-density polyethylene, and the ethylene content in the ethylene copolymer obtained by the method of the present invention is 50% by weight or more, preferably 60. The weight % or more, more preferably 60 to 99% by weight. As described above, when the (C4-C10) hydrocarbon α-olefin is used as a comonomer, the obtained linear low-density polyethylene (LLDPE) has a density of 0.850 to 0.950 g/cm 3 , more preferably a density of 0.860. An olefin copolymer of up to 0.940 g/cm 3 .

According to the present invention, in order to adjust the molecular weight in the preparation of the ethylene homopolymer or copolymer, hydrogen can be used as the molecular weight modifier, the weight average molecular weight (Mw) is from 80,000 to 500,000, and the molecular weight distribution (weight average molecular weight / number average molecular weight) The ratio (Mw/Mn) is from 1.5 to 4.1.

The catalyst composition of the present invention is in a homogeneous form in the polymerization reactor, and therefore it is preferred to apply solution polymerization at a temperature not lower than the melting point of the corresponding polymer. However, as disclosed in U.S. Patent No. 4,752,597, a homogeneous catalytic system produced by supporting the above transition metal compound and a cocatalyst with a porous metal oxide support can also be used in slurry polymerization or gas phase polymerization.

According to the present invention, a transition metal compound or a catalyst composition containing the transition metal compound can be easily and efficiently produced by reducing the number of alkyl groups (except for a specific portion of cyclopentadiene) using a simple method. Therefore, it produces economic benefits. Further, the catalyst is thermally stable and thus maintains high catalytic activity in the polymerization of an olefin under high-temperature solution polymerization conditions, and at the same time, a high molecular weight polymer can be produced in a high yield. Further, the catalyst has higher industrial availability because it enhances the conjugation of the comonomer compared to the conventional metallocene or non-metallocene catalyst having a single active site.

Therefore, the transition metal catalyst composition of the present invention and the preparation method can be effectively utilized to prepare a copolymer of ethylene and an α-olefin having various characteristics and elastic modulus.

The invention is further understood by the following examples, which are intended to be illustrative and not restrictive.

Unless otherwise stated, all ligand and catalyst synthesis tests were carried out under nitrogen atmosphere using Schlenk or glove box technology, and the organic solvent used in the reaction was carried out in the presence of sodium metal and benzophenone. Reflux to remove water and then distillate before use. ¹ H-NMR analysis of the synthesized ligand and catalyst was carried out using a Bruker 500 megahertz spectrometer at room temperature.

In the case of a polymerization solvent, cyclohexane is continuously passed through a Q-5 catalyst (commercially available from BASF) in a reactor, a ceria gel and activated alumina, and is aerated with high purity nitrogen gas ( Bubbled), thereby sufficiently removing water, oxygen and other catalyst poisoning materials for subsequent use.

The obtained polymer was analyzed by the following method.

1. Melt Flow Index (MI)

Measurements were made in accordance with ASTM D 2839.

2. Density

Measurements were made using a density gradient tube according to ASTM D 1505.

3. Melting point analysis (Tm)

The measurement was carried out using a Dupont DSC2910 under a nitrogen atmosphere at a second-order heating condition at a rate of 10 ° C/min.

4. Molecular weight and molecular weight distribution

Using PL100 GPC equipped with PL Mixed-BX2+preCol, measuring at 135 ° C at a rate of 1.0 ml / min and in the presence of 1,2,3-trichlorobenzene solvent, and using PL polystyrene standards The material corrects the molecular weight.

5. α-olefin content in the copolymer (% by weight)

Using a Bruker DRX500 NMR spectrometer, in a ¹³ C-NMR mode at 120 ° C, at 125 MHz, in the presence of 1,2,4-trichlorobenzene/C ₆ D ₆ (7/3 by weight) measuring.

(Reference: Randal, JC JMS-Rev. Macromol. Chem. Phys . 1980, C29 , 201)

[Preparation Example 1]

Synthesis of (dichloro) (tertiary butylamino) (3,4-dimethylcyclopentadienyl) (dimethyl decane) titanium (IV)

(1) Synthesis of isopropyl crotonate

In a 2 liter flask, crotonic acid (193.7 grams, 2.25 moles) was dissolved in 2-propanol (860 ml, 11.25 moles), followed by thorough agitation, and sulfuric acid was slowly added dropwise to the mixture. 24 ml, 0.45 m) and reflux for up to 48 hours or longer. The stirred mixture was cooled to room temperature, and then the obtained mixture was washed with distilled water (1000 ml), and the organic layer was separated, neutralized, and subjected to atmospheric distillation (80 ° C), thereby obtaining 220 g (1.71 mol, Yield 76.3%) of isopropyl crotonic acid.

¹ H-NMR(C ₆ D ₆ )δ=1.01~1.06(d,6H), 1.26~1.37(q,3H), 5.01~5.08(m,1H), 5.70~5.79(m,1H),6.82~ 6.93 (m, 1H) ppm

(2) Synthesis of 3,4-dimethyl-2-cyclopentenone

1 liter of polyphosphoric acid was added to a 2 liter flask and nitrogen gas was passed therethrough, followed by refluxing at 100 ° C, followed by dropwise addition of isopropyl crotonate (76.9 g, 0.6 mol), and the mixture was stirred. Up to 3 hours to turn dark brown. The mixture thus obtained was mixed with ice water (500 ml), followed by neutralization with sodium carbonate, and the organic layer was extracted with diethyl ether and then subjected to vacuum distillation (105 ° C, 40 Torr), whereby 56 g (0.51 mol) was obtained. Ear, yield 84.7%), 3,4-dimethyl-2-cyclopentenone as a colorless transparent liquid.

¹ H-NMR (CDCl ₃ ) δ = 1.05~1.09 (d, 3H), 1.83~1.87 (q, 1H), 1.98 (s, 3H), 2.45~2.51 (q, 1H), 2.67~2.70 (m, 1H), 5.73(s,1H) ppm

(3) Synthesis of tert-butyl-1-(3,4-dimethylcyclopentadienyl)-1,1-dimethyldecylamine

Lithium aluminum hydride (6.07 g, 0.16 mol) was dissolved in diethyl ether (250 ml) under nitrogen atmosphere, and 3,4-dimethyl-2-cyclopentane was slowly added dropwise at 0 °C. Enone (33.95 grams, 0.31 moles) was added to it. The reflux was carried out for 30 minutes and cooled to 0 ° C by room temperature, and then distilled water (15 ml) was slowly added dropwise thereto and the unreacted lithium aluminum hydride was removed therefrom. The reaction mixture was slowly added dropwise to dilute sulfuric acid and the organic layer was extracted with diethyl ether, followed by vacuum distillation, whereby 21.2 g of 2,3-dimethylcyclopentadiene as a yellow liquid was obtained. This solution was transferred to a flask and dissolved in pentane (200 ml), and then n-butyllithium (141 ml, 0.225 mol, 1.6 M) was slowly added dropwise thereto at -78 °C. The temperature was increased to room temperature and then the reaction was carried out for 12 hours, whereby 10.5 g (yield 46.9%) of 1,2-dimethylcyclopentadienyllithium which was a white powder was obtained. 5.45 g (54.5 mmol) of the powder was placed in a flask containing diethyl ether (80 ml), followed by dropwise addition of dichlorodimethylsilane (6.8 ml, 54.5 mmol) at -78 °C. To it. Subsequently, the temperature was raised to room temperature, and then the reaction was carried out for 12 hours or more. Diethyl ether was removed by vacuum distillation and the obtained product was washed with pentane, whereby 6.35 g (yield: 62.4%) of dimethyl decyl-3,4-dimethylcyclopentane as a yellow liquid was obtained. Dienyl chloride. This liquid was transferred to a flask without purification and dissolved in tetrahydrofuran (90 ml), followed by slowly dropwise addition of lithium-tertiary butylamine (2.69 g, 34.0 mmol) at -78 °C. ) to it. The reaction was carried out at room temperature for 12 hours or more and vacuum drying was used to completely remove the solvent, followed by extraction of the obtained product with purified pentane, whereby 6.15 g (27.5 mmol, yield 80.9%) was obtained. , a yellow liquid of tertiary butyl-1-(3,4-dimethylcyclopentadienyl)-1,1-dimethyldecylamine.

¹ H NMR (C ₆ D ₆ ): δ = 0.00 (s, 6H), 0.28 (s, 3H), 1.05 (s, 3H), 1.07 (s, 9H), 1.09 (s, 3H), 1.85 (s) , 2H), 1.94 (s, 2H), 1.98 (s, 6H), 2.89 (t, 1H), 3.17 (t, 1H), 6.16 (s, 2H), 6.31 to 6.70 (m, 1H) ppm

(4) Synthesis of (dichloro) (tertiary butylamino) (3,4-dimethylcyclopentadienyl) (dimethyl decane) titanium (IV)

Tert-butyl-1-(3,4-dimethylcyclopentadienyl)-1,1-dimethyldecylamine (6.15 g, 27.5 mmol) was placed in a flask under nitrogen It was dissolved in diethyl ether (100 ml), and then n-butyllithium (22.0 ml) was slowly added dropwise thereto at -78 °C. The temperature was gradually raised to room temperature and the reaction was carried out for 12 hours or longer. Vacuum drying was used to completely remove the flux and the obtained product was washed with pentane, thereby obtaining 5.24 g (yield 81.0%) of lithium (tris-butylamino) (3,4-dimethyl) as a white powder. Cyclopentadienyl) dimethyl decane. 3.00 g (12.8 mmol) of this powder was placed in a beaker with tetrachlorobis(tetrahydrofuran)titanium (IV) (4.26 g, 12.8 mmol) and toluene (50 ml) was added thereto to give The reaction was carried out at ° C for 24 hours or longer. The temperature was lowered to room temperature and filtered, thereby removing lithium chloride, followed by removal of the solvent by vacuum drying, followed by extraction of the obtained product with pentane and recrystallization, whereby 1.73 g (yield 39.9%) was obtained. (Dichloro) (tertiary butylamino) (3,4-dimethylcyclopentadienyl) (dimethyl decane) titanium (IV) as a yellow solid.

¹ H NMR (C ₆ D ₆ ): δ = 0.26 (s, 6H), 1.40 (s, 9H), 2.04 (s, 6H), 5.91 (s, 2H) ppm; ¹³ C NMR (C ₆ D ₆ ) : δ = 0.97, 13.41, 33.18, 105.91, 123.05, 127.84, 128.22, 133.45 ppm

[Preparation Example 2]

Synthesis of (dichloro) (tertiary butylamino) (3,4-dimethylcyclopentadienyl) (dimethyl decane) zirconium (IV)

Lithium (tertiary butylamino) 3,4-dimethylcyclopentadienyl dimethyl decane (0.9 g, 3.83 mmol) and zirconium chloride (IV) (0.891 g, 3.83 mmol) The flask was placed together and toluene (20 ml) was added to carry out the reaction at 80 ° C for 24 hours or longer. The temperature was lowered to room temperature and filtered, thereby removing lithium chloride and removing the solvent using vacuum drying, followed by extracting the obtained product with pentane and performing recrystallization, thereby obtaining 0.89 g (yield 60.5%), (Dichloro) (tertiary butylamino) (3,4-dimethylcyclopentadienyl) (dimethyl decane) zirconium (IV) as a white-brown solid.

¹ H NMR (C ₆ D ₆ ): δ = 0.30 (s, 6H), 1.31 (s, 9H), 2.00 (s, 6H), 5.90 (s, 2H) ppm; ¹³ C NMR (C ₆ D ₆ ) :δ=0.07,14.36,32.65,107.74,126.86,126.91,128.82,139.34ppm

[Comparative Preparation Example 1]

Synthesis of (dichloro) (tertiary butylamino) (2,3,4,5-tetramethylcyclopentadienyl) (dimethyl decane) titanium (IV)

(1) Synthesis of (tris-butylamino) (2,3,4,5-tetramethylcyclopenta-2,4-dienyl) dimethyl decane

2,3,4,5-Tetramethylcyclopenta-2,4-diene (3.67 g, 30 mmol) was added to a flask containing tetrahydrofuran (100 ml), and n-butyl was added dropwise at 0 °C. Lithium base (12 To the solution, the reaction temperature was gradually raised to room temperature to carry out the reaction for 8 hours. The solution was cooled to -78 ° C, and dichloromethyl decane (3.87 g, 30 mmol) was slowly added dropwise thereto, followed by a reaction for 12 hours. After the reaction, the volatile material was removed and the obtained product was extracted with hexane (100 mL), and then the volatile material was removed, thereby obtaining 5.5 g of (chloro) (dimethyl) as a white-yellow oil. 2,3,4,5-Tetramethylcyclopentadienyl)decane. The (chloro)(dimethyl)(2,3,4,5-tetramethylcyclopentadienyl)decane thus obtained was dissolved in tetrahydrofuran (100 ml) without further purification. Subsequently, lithium tributyl decylamine (2.02 g) was added dropwise at 0 ° C and the reaction was carried out at room temperature for 2 hours. After the reaction, the volatile material was removed, and the product obtained therefrom was extracted with hexane (100 ml), whereby 6.09 g (yield: 81%) of white yellow oil (tris-butylamino) was obtained. (2,3,4,5-Tetramethylcyclopenta-2,4-dienyl)dimethyloxane.

¹ H-NMR (C ₆ D ₆ ) δ = 0.11 (s, 6H), 1.11 (s, 9H), 1.86 (s, 6H), 2.00 (s, 6H) 2.78 (s, 1H) ppm

(2) Synthesis of (dichloro) (tertiary butylamino) (2,3,4,5-tetramethylcyclopentadienyl) (dimethyl decane) titanium (IV)

(Tris-butylamino)(2,3,4,5-tetramethylcyclopenta-2,4-dienyl)dimethyloxane (6.09 g, 24.2 mmol) dissolved in diethyl Into the ether (100 ml), n-butyllithium (9.7 ml) was added dropwise thereto at -78 ° C, and then the reaction temperature was gradually raised to room temperature and the reaction was carried out for 12 hours. After the reaction, the volatile material was removed, and the obtained product was extracted with hexane (100 ml), whereby 6.25 g of an orange solid was obtained. The solid thus obtained was dissolved in toluene (100 ml), and titanium tetrachloride (IV) (4.50 g, 23.7 mmol) was added dropwise thereto at -78 ° C, followed by a reaction temperature system. The temperature was raised to room temperature and the reaction was carried out for 7 hours. After the completion of the reaction, the volatile material was removed, and the obtained product was extracted with purified pentane (100 ml) and recrystallized at -35 ° C, filtered and then dried in vacuo, whereby 0.87 g (yield 10%) was obtained. (Dichloro) (tertiary butylamino) (2,3,4,5-tetramethylcyclopentadienyl) (dimethyl decane) titanium (IV) in an orange solid.

¹ H-NMR (C ₆ D ₆ ) δ = 0.43 (s, 6H), 1.43 (s, 9H), 2.00 (s, 6H), 2.01 (s, 6H) ppm

[Comparative Preparation Example 2]

Synthesis of (dichloro) (tertiary butylamino) (2,3,4,5-tetramethylcyclopentadienyl) (dimethyl decane) zirconium (IV)

In the same manner as in Comparative Preparation Example 1, except that 5.52 g (23.7 mmol) of zirconium tetrachloride (IV) was used to synthesize 1.3 g (yield 13.3%) of (dichloro) (tertiary butylamino group). (2,3,4,5-tetramethylcyclopentadienyl) (dimethyl decane) zirconium (IV).

¹ H-NMR (C ₆ D ₆ ) δ = 0.40 (s, 6H), 1.40 (s, 9H), 1.97 (s, 6H), 2.00 (s, 6H) ppm

[Example 1]

Ethylene and 1-octene were copolymerized by the following procedure using a batch polymerization apparatus. Specifically, 1170 ml of cyclohexane and 30 ml of 1-octene were added to a 2000 ml, fully dried and nitrogen purged stainless steel reactor, followed by 22.1 ml of the modified methyl group. Aluminoxane-7 (commercially available from Akzo Nobel, modified MAO-7, 7 wt% Al Isopar solution) 54.2 mM toluene solution was fed to the reactor. The temperature of the reactor was raised to 80 ° C, followed by the sequential addition of 0.4 Preparation of (dichloro) (tertiary butylamino) (3,4-dimethylcyclopentadienyl) (dimethyl decane) titanium (IV) (5.0 mM toluene solution) prepared in Example 1 And 2.0 ml of triphenylmethyltetrakis(pentafluorophenyl)borate (99%, Boulder Scientific) 10 mM toluene solution, to adjust the internal pressure of the reactor to up to 30 kg / cm ^ 2 with ethylene, followed by polymerization effect. During the 5 minute reaction time, the temperature was up to 162.2 °C. After 5 minutes, 100 ml of ethanol containing 10% by volume aqueous hydrochloric acid solution was added thereto, whereby the polymerization was terminated, followed by stirring with 1.5 liters of ethanol for 1 hour, followed by filtration and separation of the reaction product. The recovered reaction product was dried in a vacuum oven at 60 ° C for 8 hours to yield 62.8 g of polymer. The polymer has a melting point of 117.48 ° C, a melt index of 0.016 and a density of 0.9124 g/cm 3 ; analysis by gel chromatography, weight average molecular weight (Mw) of 202,000 g/mole, molecular weight distribution (Mw) /Mn) was 4.05 and the content of 1-octene was 7.68 wt%.

[Embodiment 2]

Ethylene and 1-octene were copolymerized in the same manner as in Example 1, except that the reaction temperature was raised up to 140 ° C before the addition of the catalyst. During the 5 minute reaction time, the temperature system was up to 180.9 ° C and finally 48.04 grams of polymer was obtained. The polymer has a melting point of 119.02 ° C, a melt index of 1.5, and a density of 0.9152 g/cm 3 , which can be obtained by gel chromatography, Mw of 109,100 g/m, Mw/Mn of 2.33 and 1-octene. The content was 4.98 wt%.

[Example 3]

Ethylene and 1-octene were copolymerized in the same manner as in Example 1, except that 0.4 ml of (dichloro) (tertiary butylamino) (3,4-dimethyl) synthesized in Preparation Example 2 was added. base Cyclopentadienyl) (dimethyl decane) zirconium (IV) (5.0 mM, toluene solution) and the reaction time was set to 10 minutes. During the 10 minute reaction time, the temperature system was up to 98.2 ° C and finally 4.62 grams of polymer was obtained. The polymer has a melting point of 133.28 ° C, a melt index of 0.165, a density of 0.9370 g/cm 3 , and Mw of 211,600 g/m, Mw/Mn of 3.13 and 1-, as determined by gel chromatography. The content of octene was 0.82% by weight.

[Comparative Example 1]

Ethylene and 1-octene were copolymerized in the same manner as in Example 1, except that (dichloro) (tertiary butylamino) (2,3,4,5-tetramethyl) synthesized in Comparative Preparation Example 1 was added. (cyclopentadienyl) (dimethyl decane) titanium (IV). During the reaction time of 5 minutes, the temperature was up to 163.0 ° C, and finally 66.68 grams of polymer was obtained. The polymer has a melting point of 116.35 ° C, a melt index of 0.004, a density of 0.9420 g/cm 3 , and is obtainable by gel chromatography, Mw of 247,800 g/mole, Mw/Mn of 7.30 and 1-octene. The content was 6.55 wt%.

[Comparative Example 2]

Ethylene and 1-octene were copolymerized in the same manner as in Example 1, except that the reaction temperature was raised up to 140 ° C before the addition of the catalyst and the (dichloro) (dichloro) synthesized in Comparative Preparation Example 1 was added. Amino) (2,3,4,5-tetramethylcyclopentadienyl) (dimethyl decane) titanium (IV). During the 5 minute reaction time, the temperature was up to 184.4 ° C and finally 40.03 grams of polymer was obtained. The polymer has a melting point of 116.21 ° C, a melt index of 0.56, a density of 0.9218 g/cm 3 , and is obtainable by gel chromatography, Mw of 106,000 g/mole, Mw/Mn of 4.31 and 1-octene. The content was 6.34% by weight.

[Comparative Example 3]

Ethylene and 1-octene were copolymerized in the same manner as in Example 1, except that 0.4 ml of (dichloro) (tertiary butylamino) (2, 3, 4, 5) synthesized in Example 2 was prepared. -Tetramethylcyclopentadienyl) (dimethyl decane) zirconium (IV) (5.0 mM solution in toluene) and the reaction time was set to 10 minutes. During the 10 minute reaction time, the temperature reached up to 102.1 ° C and finally 16.49 grams of polymer was obtained. The polymer has a melting point of 125.93 ° C, a melt index of 0.087, a density of 0.9405 g/cm 3 , and is obtainable by gel chromatography, Mw of 426,800 g/mole, Mw/Mn of 3.31 and 1-octyl. The content of the alkene was 2.2% by weight.

As is apparent from the above examples, in the polymerization of the individual ethylene and the combined 1-octene under the aforementioned polymerization conditions, a high yield of the polymer can be produced and obtained under the same conditions as compared with the comparative examples. A higher 1-octene content olefin copolymer. In particular, low density copolymers can be successfully prepared from ethylene and 1-octene.

While the preferred embodiment of the present invention has been described by the embodiments of the present invention, it will be understood by those skilled in the art that various changes, additions and substitutions can be made without departing from the scope and spirit of the invention. The scope of the disclosure.

Claims (3)

A method for preparing a copolymer of ethylene and an α -olefin, which comprises using a transition metal catalyst composition comprising a transition metal compound of the following Chemical Formula 1 and a cocatalyst selected from the group consisting of an aluminum compound and a boron compound And mixtures thereof: Wherein M is titanium; R ¹ and R ² are independently (C1-C7)alkyl, which are independently located at the 3,4 position of a cyclopentadienyl group capable of forming an η ⁵ bond with M; D-N-R ⁵ )-, wherein R ⁵ is (C1-C20)alkyl; R ³ and R ⁴ are independently (C1-C20)alkyl; X is independently a halogen atom or (C1-C20)alkyl; and n is An integer of 2; wherein the pressure of the ethylene in the reactor is 6 to 150 atm, and the polymerization temperature is 60 to 250 ° C; wherein the α -olefin is selected from the group consisting of propylene, 1-butene, 1-pentene, 1- One or more of hexene, 1-heptene, 1-octene and 1-decene, and the ethylene content of the copolymer of ethylene and α -olefin is 50% by weight or more, and the melting point is 117.48 ° C. To 119.02 ° C, the density is from 0.860 to 0.940 g/cm 3 , the weight average molecular weight is from 80,000 to 500,000, and the molecular weight distribution (Mw/Mn) is from 1.5 to 4.1. The method of claim 1, wherein R ¹ and R ² are independently selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, dibutyl, tert-butyl and n-pentyl; R ⁵ is selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, secondary butyl, and tertiary butyl. The method of claim 1, wherein the aluminum compound comprises a cocatalyst selected from one or more of aluminoxane and organoaluminum, and is selected from the group consisting of methylaluminoxane and modified methylaluminoxane. , tetraisobutylaluminoxane, trialkylaluminum, dialkylaluminum chloride, alkylaluminum dichloride, dialkylaluminum hydride, and mixtures thereof; and the boron compound cocatalyst is selected from N,N - dimethylaniline tetrakis(pentachlorophenyl)borate, triphenylmethyltetrakis(pentafluorophenyl)borate and mixtures thereof.