JPH0780963B2 - Method for producing ethylene-based copolymer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an ethylene-based copolymer, and more specifically, an ethylene-based copolymer using a catalyst containing a specific chromium compound and an organometallic compound as main components. The present invention relates to a method for efficiently producing a coalescence.

[Prior Art and Problems to be Solved by the Invention] Conventionally, polyethylene has been excellent in water resistance, chemical resistance, electrical characteristics and the like, and has been used in a wide variety of applications. However, since they are chemically inert, they have the drawback of being inferior in adhesiveness, printability, and dyeability, and their use in applications requiring these properties has been limited.

Therefore, in order to improve such properties of polyethylene, a method of copolymerizing ethylene with an unsaturated carboxylic acid ester or the like is known. For example, JP-A-55-118905 or JP-A-59-80413 proposes a copolymerization method of an olefin and an unsaturated carboxylic acid ester, both of which have low copolymerization activity and unsaturated carboxylic acid. There is a problem that the conversion rate of the acid ester into a copolymer is low and the copolymer composition cannot be controlled arbitrarily.

Further, the present inventors have already proposed a method for improving the conversion rate of an unsaturated carboxylic acid ester into a copolymer by copolymerizing ethylene and an unsaturated carboxylic acid ester using a chromium-based catalyst (JP JP 61-278508 A, JP 6
2-86009 publication). However, even by this method, the copolymerization activity was still insufficient, and the content of the unsaturated carboxylic acid ester residue in the copolymer was not sufficient.

When a chromium-based catalyst is used, the chromium compound remaining in the copolymer is usually removed by a deashing treatment to render the copolymer harmless and prevent deterioration of physical properties.
Therefore, in order to avoid or reduce such a post-treatment, it is necessary that the copolymer yield per unit chromium (that is, the copolymerization activity) is as high as possible. Furthermore, if the content of the unsaturated carboxylic acid or its ester in the copolymer can be largely changed, the mechanical properties of the ethylene-based copolymer, for example, flexibility can be changed over a wide range. The field will expand.

[Means for Solving the Problems] As a result of intensive studies to solve such problems, the present inventors have found that the copolymerization activity and the copolymerization activity can be improved by carrying out the copolymerization using a specific catalyst. It was found that the content of unsaturated carboxylic acid or unsaturated carboxylic acid ester in the combined product can be further increased, and the present invention has been completed based on this finding.

That is, the present invention provides [A] a general formula CrL _m X ¹ _pm (ED) _n ... [I] [wherein L represents R ¹ OCO, CO, R ¹ or NR ¹ R ² (provided that R
¹ and R ² each represent an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group or an aralkyl group having 1 to 20 carbon atoms, which may be the same or different. ), X ¹ represents a halogen atom or a hydroxyl group. Further, ED represents water, a hydrocarbon having an aromatic ring, or an organic compound having a hetero atom. Furthermore, p is 2, 3, 4 or 6
, M is a real number that satisfies the expression 0 <m ≦ p, and n is an arbitrary integer. However, when both m and p are 3 and L is R ¹ OCO, n represents an integer of 1 or more. And a compound represented by the general formula R ³ _K MX ² _ik ... [II] [wherein R ³ is an alkyl group having 1 to 20 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group or an aralkyl group. Indicates. M is lithium, sodium, potassium, magnesium, zinc, cadmium, aluminum,
Indicates boron, gallium, silicon, tin, antimony or bismuth. Further, X ² represents a halogen atom.
Further, i is the valence of M, and k is a real number satisfying 0 <k ≦ i. ] The ethylene-based copolymer characterized by copolymerizing ethylene and unsaturated carboxylic acid or unsaturated carboxylic acid ester in the presence of a Lewis acid using a catalyst containing an organometallic compound represented by It provides a method.

First, in the method of the present invention, the chromium compound represented by the above general formula [I] is used as the transition metal component.

In the above general formula [I], L is R ¹ OCO, C as described above.
O, R ¹ or NR ¹ R ² is shown. However, R ¹ and R ² each represent an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group or an aralkyl group having 1 to 20 carbon atoms, and may be the same or different. Where R
Specific examples of ¹ and R ² include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, hexyl group, 2-ethylhexyl group and phenyl group.

X ¹ represents a halogen atom such as chlorine, bromine, iodine or a hydroxyl group.

Further, ED represents water, a hydrocarbon having an aromatic ring, or an organic compound having a hetero atom. Examples of the hydrocarbon having an aromatic ring include toluene, o-xylene, m-xylene, p-xylene, naphthylene and indene, and examples of the organic compound having a hetero atom include ethers, esters, ketones and amines. , Phosphines, nitriles,
Examples thereof include organic compounds having a complex forming ability with chromium compounds, such as thiols and pyridine.

Examples of such a chromium compound include compounds represented by the general formula [I]
When L is R ¹ OCO, Cr (CH ₃ COO) _7/3 (O
H) _2/3 , Cr [CH ₃ (CH ₂ ) ₁₆ COO] ₂ Cl, Cr [CH ₃ (CH ₂ ) ₁₆ CO
O] Cl ₂ , Cr [C ₁₁ H ₂₃ COO] ₂ Cl, Cr (C ₁₁ H ₂₃ COO) Cl ₂ , C
_{r (CH 3 COO) 2 Cl} , Cr (C 21 H 43 COO) 2 Cl, Cr (CH 3 COO) Cl
₂ , Cr (C ₂₁ H ₄₃ COO) Cl ₂ , Cr [CH ₃ (CH ₂ ) ₁₄ COO] ₂ Cl, Cr
Fatty acid salts such as [CH ₃ (CH ₂ ) ₁₄ COO] Cl ₂ and Cr [CH ₃
(CH ₂ ) ₁₆ COO] Cl ₂ · THF, Cr [CH ₃ (CH ₂ ) ₁₄ COO] Cl ₂ · T
HF, Cr (C ₁₁ H ₂₃ COO) Cl ₂・ THF, Cr (C ₂₁ H ₄₃ COO) Cl ₂
Examples thereof include THF (tetrahydrofuran) adducts of the above compounds such as THF, and adducts of chain ethers, esters, ketones and the like.

Then, when L is R ¹ OCO and p = m = 3, Cr (CH ₃ C
OO) ₃・ H ₂ O, Cr (CH ₃ COO) ₃・ Pph ₃ (however, ph is a phenyl group, the same applies hereinafter), _{Cr (CH 3 -COO) 3 ·} H 2 S, Cr (CH 3 -COO) 3 · N (CH 3) 3 and the like.

When L in the general formula [I] is CO, Cr (CO) ₆ , Cr
(CO) ₃ C ₆ H ₆ , Cr (CO) ₃ (CH ₃ OCOC ₆ H ₅ ), Cr (CO)
_{3 (P-CH 3 C 6} H 5 CH 3), Cr (CO) 3 [P (Oph) 3] 3, Cr
(CO) ₅ (Pph ₃ ), Cr (CO) ₃ (C ₅ H ₅ ), Cr (CO) ₃ [P
—ClC ₆ H ₅ CH ₃ ] and the like.

Further, in the case where L in the general formula [I] is R ¹ , Cr [CH ₂ C
_{(CH 3) 3] 4,} Cr [CH 2 C (CH 3) 2 ph] 4, Cr (CH 3) 4, Cr
_{(CH 2 Cph 3) 4,} Cr (C 2 H 5) 4, Cr (C 3 H 7) 4, Cr (CH 2 Si
Me ₃ ) ₄ (however, Me is a methyl group, the same applies hereinafter) and the like.

When L in the general formula [I] is NR ¹ R ² , Cr (NE
t ₂ ) ₄ (Et is an ethyl group, the same applies hereinafter), Cr (NEt ₂ ) ₃ , Cr
(NMeBu) ₄ (However, Bu is an n-butyl group, the same applies below), Cr (N
MeBu) ₃ , Cr (NPr ₂ ) ₄ (however, Pr is an n-propyl group, the same applies below), Cr (NPr ₂ ) ₃ , Cr (NC ₅ H ₁₀ ) ₄ , Cr (NC ₅ H ₁₀ ) ₃ , C
_{r [NCH (CH 3) 2} ] 4, Cr [NCH (CH 3) 2] 3, Cr (NMe 2) 4, C
r [N (C ₆ H ₁₁ ) ₂ ] _{4 and the} like.

Among these chromium compounds, particularly preferable compounds include halogenated carboxylic acid chromium compounds such as chromium acetate monohalide and chromium stearate monohalide, alkyl chromium compounds such as neopentyl chromium,
Tris (dialkylamido) chromium [III] -based compounds such as tris (dicyclohexylamide) chromium [III] and tris (di-normalpropylamide) chromium [III], and trilycarbonyl (η-p-xylene) chromium (O) And so on.

Next, in the method of the present invention, the organometallic compound represented by the general formula [II] is used as the organometallic component [B]. R ³ in the general formula [II] represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group or an aralkyl group. Specific examples of R ³ include methyl group, ethyl group, n-propyl group, i-propyl group, n-
Examples thereof include a butyl group, an i-butyl group, a hexyl group, a 2-ethylhexyl group, and a phenyl group. Further, M represents lithium, sodium, potassium, magnesium, zinc, cadmium, aluminum, boron, gallium, silicon, tin, antimony or bismuth. Further, X ² represents a halogen atom, that is, chlorine, bromine, iodine or the like. i
Is the valence of M and is usually a real number from 1 to 5. k is a real number satisfying 0 <k ≦ i and indicates various values.

Specific examples of the compound represented by the general formula [II] include alkyllithium such as methyllithium, ethyllithium, propyllithium and butyllithium, diethylmagnesium, ethylbutylmagnesium, dinormalbutylmagnesium, ethylchloromagnesium, etc. Alkylmagnesium, dimethylzinc, diethylzinc, dipropylzinc, dibutylzinc, etc. dialkylzinc, trimethylgallium, triethylgallium, tripropylgallium, tributylgallium, etc. alkylgallium compounds, triethylboron, tripropylboron, tributylboron, etc. Alkyl such as boron compound, tetraethyltin, tetraethylpropyltin, tributylchlorotin, tetraphenyltin, triphenylchlorotin 'S compounds. In addition, there are various examples of the compound when M is aluminum, and specifically, trialkylaluminum compounds such as trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, trioctylaluminum and cyethyl. Dialkyl aluminum monohalides such as aluminum monochloride, diethyl aluminum monobromide, diethyl aluminum monoiodide, diisopropyl aluminum monochloride, diisobutyl aluminum monochloride, dioctyl aluminum monochloride, methyl aluminum sesquichloride, ethyl aluminum sesquichloride, ethyl aluminum sesquibromide. , Butyl aluminum sesquichloride, etc. A preferred iodonium sesquihalides, also mixtures thereof may be mentioned as preferable. Furthermore, an alkyl group-containing aluminoxane produced by the reaction of alkylaluminum and water can also be used.

Furthermore, specific examples of the compound represented by the above general formula [II] include triphenylbismuth, triethylbismuth,
Examples thereof include bismuth compounds such as trimethylbismuth and triisobutylbismuth.

Among these, especially aluminum compounds, tin compounds,
Bismuth compounds and magnesium compounds are preferably used.

In the method of the present invention, the above-mentioned [A] chromium compound,
The ratio of the organometallic compound represented by the above general formula [II] used as the organometallic component [B] is not particularly limited, but usually the number of moles of chromium atom in the former is (a) and the metal atom in the latter is When the number of moles of is (b), the value of (b) / (a) may be 0.1 to 5000, preferably 1 to 1000.

In the method of the present invention, an ethylene-based copolymer is produced by copolymerizing ethylene with an unsaturated carboxylic acid or an unsaturated carboxylic acid ester in the presence of a Lewis acid using the above catalyst.

Examples of the Lewis acid include Lewis acid compounds capable of forming a complex with a lone pair of polar groups, for example, halogenated compounds of Groups I to V or VIII of the periodic table. In particular, halogenated compounds such as aluminum, boron, zinc, tin, magnesium, antimony, such as aluminum chloride, aluminum bromide, ethyl aluminum dichloride, diethyl aluminum monochloride, boron trichloride, zinc chloride, tin tetrachloride, alkyl tin halides, Magnesium chloride, antimony pentachloride, antimony trichloride, etc. are preferred, but aluminum chloride,
Examples include aluminum bromide and ethylaluminum dichloride.

As ethylene, which is the main raw material of the copolymer according to the present invention, ethylene is used alone, and an α-olefin having 3 to 20 carbon atoms is produced in consideration of the purpose of use of the copolymer. For example, a material added in an amount sufficient to change the crystallinity may be used.

The unsaturated carboxylic acid or ester thereof to be copolymerized with ethylene is not particularly limited, The compound represented by This general formula [III]
R ⁴ represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group or an aralkyl group, and R ⁵ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, An alkenyl group, a cycloalkyl group, an aryl group or an aralkyl group is shown. Also, l
Represents an integer of 0 to 20.

Specific examples of the unsaturated carboxylic acid represented by the general formula [III] include acrylic acid, methacrylic acid, α-chloroacrylic acid, 3-butenoic acid, 4-pentenoic acid, 6-heptenoic acid and 8-nonenoic acid. , 10-undecenoic acid and the like.

Specific examples of unsaturated carboxylic acid esters include acrylic acid esters such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, and benzyl acrylate: Α-Substituted acrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, α-chloroacrylic acid metal, α-chloroacrylic acid ethyl ester; methyl 3-butenoate, Ethyl 3-butenoate, Methyl 4-pentenoate, Ethyl 6-heptenoate, 8-
Methyl nonenate, Methyl 10-undecenoate, Propyl 10-undecenoate, Butyl 10-undecenoate, Hexyl 10-undecenoate, Octyl 10-undecenoate, Decyl 10-undecenoate, Cyclohexyl 10-undecenoate, 10-Undecenoic acid Examples thereof include carboxylic acid esters having a terminal double bond such as phenyl, and these can be used alone or in admixture of two or more.

The ratio of the unsaturated carboxylic acid or ester thereof to ethylene as described above may be arbitrarily selected according to the physical properties required for the target copolymer.

The ratio of the Lewis acid to the unsaturated carboxylic acid or its ester used is 0.1 to 10 (molar ratio) of Lewis acid, preferably 0.2 to 1 (molar ratio) with respect to 1 unsaturated carboxylic acid or its ester. Is.

The type of polymerization is not particularly limited, and slurry polymerization, solution polymerization, gas phase polymerization, etc. are all possible, and continuous polymerization,
Any discontinuous polymerization is possible. In this case, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons and carbon halides are used as the polymerization solvent. Specifically, pentane, hexane, heptane, octane, decane, dodecane, cyclohexane, benzene, toluene, xylene, ethylbenzene, chlorobenzene,
Ethylene dichloride, tetrachloroethylene, kerosene, etc. are used. As for the polymerization conditions, the reaction pressure is atmospheric pressure to 100 kg / cm.
^{It is 2} G, preferably normal pressure to 30 kg / cm ² G, and the reaction temperature is -80 to 200 ° C, preferably -50 to 100 ° C. The reaction time is arbitrary, but it may be appropriately selected usually from 1 minute to 10 hours. The molecular weight at the time of polymerization can be adjusted by a known means such as hydrogen.

EXAMPLES Next, the present invention will be described in more detail with reference to examples.

Example 1 (1) Preparation of Catalyst Component [Tris (dicyclohexylamide) chromium (III)] 5.16 g of lithium dicyclohexylamide was dissolved in dehydrated tetrahydrofuran under an argon atmosphere. While cooling this solution with an ice bath, 1.46 g of anhydrous chromium trichloride
Was gradually added. After the addition, the mixture was reacted at room temperature for 5 hours.
After completion of the reaction, tetrahydrofuran was completely distilled off under reduced pressure, and the remaining solid component was extracted with dehydrated heptane to obtain 5.00 g of a black-red solid.

As a result of elemental analysis, this solid was confirmed to be tris (dicyclohexylamido) chromium (III). 160 g of 4 g of this tris (disiclohexylamide) chromium (III)
It was dissolved again in ml of dehydrated heptane and used as a catalyst component in the following reaction.

(2) Manufacture of copolymer Toluene (3) was placed in a 500 ml pressure-resistant glass container replaced with argon.
00 ml, 0.87 ml of ethyl acrylate (8 mmol) and 8 mmol of aluminum trichloride ball-milled under a stream of argon were added, and then 0.5 mmol of diethylaluminum monochloride and 0.00235 mmol of the chromium catalyst component prepared in the above (1) were added. . Then, ethylene was introduced into the glass container, and the polymerization reaction was carried out at 20 ° C. for 3 hours while maintaining 3 kg / cm ² G. After completion of the reaction, ethylene was depressurized and the product was poured into methanol to cause precipitation. The obtained solid copolymer was separately collected, deashed with a hydrochloric acid-methanol mixed solution, and extracted with acetone for 5 hours to remove the amorphous polymer. The extraction residue was dried under reduced pressure at 80 ° C. for 2 hours to obtain 5.90 g of a white copolymer. The catalytic activity (polymerization activity) of this product was 48.3 kg / g.chrome. When the obtained copolymer was subjected to infrared absorption spectrum analysis, the absorption by the carbonyl group at a position of 1730 cm ^-1 was found to be 1160.
Absorption by an ether bond was observed at the position of cm ^-1 . From these absorptions, it was found that the content of ethyl acrylate in the copolymer was 5.1 wt% and the conversion of ethyl acrylate to the copolymer was 37.7%. Furthermore, when the melting point of this copolymer was measured, it was 131 ° C, which is lower than the melting point of 135 ° C of polyethylene produced with the same catalyst, and ethyl acrylate was introduced into the ethylene polymer chain in a form that disturbed the crystals. It is considered that The above results are shown in Table 1.

Comparative Example 1 Example 1 was repeated except that the chromium catalyst was replaced by chromium stearate. The results are shown in Table 1.

Example 2 (1) Preparation of catalyst component [tetrakis (noopentyl) chromium (IV)] It was synthesized by the method described in the following literature.

J.Chem.Soc.Dalton.Trans.1973,770. 0.55 g of the obtained tetrakis (neopentyl) chromium (IV) was added to dehydrated hexane 1
It was dissolved in 00 ml to obtain a catalyst component.

(2) Manufacture of Copolymer In Example 1, 0.005 mmol of tetrakis (neopentyl) chromium (IV) obtained in (1) above was used as the chromium catalyst component, and the ethylene pressure was 2 kg / cm ² G. The procedure was the same as in Example 1 except for the above. The results are shown in Table 1.

Example 3 (1) Preparation of catalyst component (chromium acetate-hydrate) A commercially available chromium acetate-hydrate was dried under reduced pressure at room temperature to remove adsorbed water. After drying under reduced pressure, ball milling was performed and used as a catalyst component as a toluene slurry. The slurry concentration is 0.
It was 03 mol / l.

(2) Production of Copolymer The procedure of Example 2 was repeated, except that the chromium catalyst component obtained in (1) above was used instead of the chromium catalyst component. The results are shown in Table 1.

Example 4 (1) Preparation of catalyst component (chromium monochloride distearate) Chromium trichloride tetrahydrofuran complex [CrCl ₃ (TH
F) ₃ ] 3.75 g was dissolved in dehydrated tetrahydrofuran,
A solution of 5.69 g of stearic acid in tetrahydrofuran was added. After stirring at the boiling point for 1 hour, THF was distilled off. Furthermore, the temperature was raised to 90 ° C. and THF was completely distilled off under reduced pressure. Hydrogen chloride was generated at this time, and the completion of the reaction was confirmed from the quantitative value. Furthermore, it was confirmed that the product obtained by elemental analysis was chromium monochloride distearate. This product was dissolved in dehydrated toluene to give a chromium catalyst component.

(2) Production of Copolymer The procedure of Example 2 was repeated, except that the chromium catalyst component obtained in (1) above was used instead of the chromium catalyst component. The results are shown in Table 1.

Example 5 (1) Catalyst component [tricarbonyl (η-p-xylene)
Chromium (O)] was prepared by the method described in the following literature.

Organometallic Syntheses, voll, p137. Academic Press (1965) 1.88 g (7.77 m.mol) of yellow crystals of the obtained tricarbonyl (η-p-xylene) chromium (O) was added to dehydrated toluene 15
It was dissolved in 0 ml to give a chromium catalyst component.

(2) Production of Copolymer The procedure of Example 2 was repeated, except that the chromium catalyst component obtained in (1) above was used instead of the chromium catalyst component. The results are shown in Table 1.

Comparative Example 2 The procedure of Example 2 was repeated, except that the chromium catalyst component was changed to chromium stearate. The results are shown in Table 1.

Examples 6-9 and Comparative Examples 3-8 Example 2 except that the unsaturated carboxylic acid (ester) and / or organometallic compound was changed as shown in Table 1.
It carried out similarly to. The results are shown in Table 1.

Example 10 In Example 2, octene was added before introducing ethylene.
Example 2 was repeated except that 2.9 g of 1 was added and terpolymerization was performed at 30 ° C. Absorption of the resulting copolymer 1730 cm ^-1 to a carbonyl group was infrared absorption spectral analyzes are also observed the absorption obtained by combining methylene group 4 or more to 1160 cm ^-1. Also ¹³ C-NM
As a result of R analysis, absorption corresponding to the hexyl branch of octene-1 was observed at around 13.4, 22.2, 29.4, 31.6, 34.4, 27.0 ppm. The composition of the terpolymer was determined by ¹ H-NMR. The reaction results are shown in Table 1.

Comparative Example 9 The procedure of Example 10 was repeated, except that the chromium catalyst component was changed to chromium stearate. The results are shown in Table 1.

Example 11 In Example 2, tris (dicyclohexylamido) chromium (III) was used as the chromium catalyst component, 4-methylpentene-14.6 g was added before introducing ethylene, and terpolymerization was carried out at 30 ° C. The procedure was the same as in Example 2 except for the above. The result of infrared absorption spectrum analysis of the obtained copolymer was the same as that of the copolymer obtained in Example 10. As a result of ¹³ C-NMR analysis, 4-methylpentene-1
Absorption corresponding to side chains was observed around 22.5, 25.2, 44.3 ppm. The composition of the terpolymer was determined by ¹ H-NMR. The reaction results are shown in Table 1.

Comparative Example 10 The procedure of Example 11 was repeated, except that the chromium catalyst component was changed to chromium stearate. The results are shown in Table 1.

* 1 Add 2.9 g of octene-1 in addition to ethylene * 2 Add 4.6 g of 4-methylpentene-1 in addition to ethylene * 3 EA; Ethyl acrylate EHA; 2-Ethylhexyl acrylate 10-UME; 10- Methyl undecenoate * 4 TDCAC; Tris (dicyclohexylamide)
Chromium (III) CrSt ₃ ; Chromium stearate TNPC; Tetrakis (neopentyl) chromium (IV) Cr (OAc) ₃ H ₂ O; Chromium acetate-hydrate CDAMC; Chromium monochloride distearate TCη-XC; Tricarbonyl (η -P-xylene) Chromium (O) Cr (acac) ₃ ; Trisacetylacetonatochromium * 5 DEAC; Diethylaluminum Monochloride Biφ ₃ ; Triphenylbismuth SnEt ₄ ; Tetraethyltin [Effect of the Invention] According to the method of the present invention. For example, by using [A] a specific chromium compound and using the organometallic compound represented by the above general formula [II] as the organometallic component [B], it is possible to perform copolymerization with high activity and high yield. In addition, the deashing load can be reduced, and the conversion rate of unsaturated carboxylic acid or its ester into a copolymer can be improved. Therefore, a copolymer containing these unsaturated carboxylic acids or their esters at a high rate can be obtained even in a low charge region.

In addition, since the content of unsaturated carboxylic acid or its ester in the copolymer can be greatly changed, printability, adhesiveness, low temperature flexibility, low temperature impact resistance, bending crack resistance, weather resistance, etc. An ethylene-based copolymer having various properties adjusted widely can be easily obtained.

[Brief description of drawings]

FIG. 1 is a drawing showing the steps for preparing a catalyst used in the method of the present invention.

Claims (1)

[Claims] 1. [A] General formula CrL _m X ¹ _pm (ED) _n [wherein L represents R ¹ OCO, CO, R ¹ or NR ¹ R ² (provided that
R ¹ and R ² each represent an alkyl group having 1 to 20 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group or an aralkyl group, and may be the same or different. ), X ¹ represents a halogen atom or a hydroxyl group. Further, ED represents water, a hydrocarbon having an aromatic ring, or an organic compound having a hetero atom. Furthermore, p is 2, 3, 4 or 6
, M is a real number that satisfies the expression 0 <m ≦ p, and n is an arbitrary integer. However, when both m and p are 3 and L is R ¹ OCO, n represents an integer of 1 or more. And a compound represented by the general formula R ³ _K MX ² _ik [wherein R ³ represents an alkyl group, alkenyl group, cycloalkyl group, aryl group or aralkyl group having 1 to 20 carbon atoms]. M is lithium, sodium, potassium, magnesium, zinc, cadmium, aluminum,
Indicates boron, gallium, silicon, tin, antimony or bismuth. Further, X ² represents a halogen atom.
Further, i is the valence of M, and k is a real number satisfying 0 <k ≦ i. ] The ethylene-based copolymer characterized by copolymerizing ethylene and unsaturated carboxylic acid or unsaturated carboxylic acid ester in the presence of a Lewis acid using a catalyst containing an organometallic compound represented by Method.