KR100328682B1 - Preparation method of catalyst for producing ethylene polymer and preparation method of ethylene polymer using the catalyst - Google Patents

Abstract

PURPOSE: Provided are a preparation method of a catalyst for producing ethylene polymer in high yield and a preparation method of ethylene polymer using the catalyst. By using the catalyst, an ethylene polymer with sufficiently high molecular weight and good physical property can be prepared in high yield. CONSTITUTION: The catalyst comprises a main catalyst mixture consisting of an organic Mg compound, an organic Al compound, a Ti compound and a V compound activated by a heat treatment; and an organic Al compound as a cocatalyst. The process for producing ethylene polymer by using the catalyst comprises heat treating a polymerization main catalyst mixture consisting of an organic Mg compound, an organic Al compound, a Ti compound and a V compound as a main catalyst, followed by injecting it into a polymerization solution in which an organic Al compound as a cocatalyst is dissolved; and solution-polymerizing at the temperature of 20-320 deg.C and under the pressure of 1-800 atm.

Description

Method for preparing catalyst for producing ethylene polymer and method for preparing ethylene polymer using same

The present invention relates to a method for producing a catalyst capable of producing an ethylene polymer or a copolymer of ethylene and an alpha olefin and a method for producing an ethylene polymer or a copolymer of ethylene and an alpha olefin using the catalyst. In more detail, ethylene polymers having high molecular weight distribution and high molecular weight and linear low density polyethylene having high molecular weight distribution that can be easily applied to films, fibers, pipes, and other injection and extrusion moldings can be produced in high yield. It is suitable for the preparation of highly active catalyst components.

To date, numerous catalysts are known which are capable of copolymerizing ethylene alone or ethylene and alphaolefins. Usually, these catalysts are used to carry out polymerization in the gas phase or in a liquid solvent. In the latter case, the polymerization is carried out at a temperature at which the ethylene polymer is dissolved in a solvent at a temperature higher than the temperature at which the ethylene polymer is dissolved in a solvent. There is a solution polymerization method. As the polymerization temperature is higher, the activity of the catalyst and the molecular weight of the resulting polymer are generally reduced. Therefore, solution polymerization requires a special performance catalyst system. Solution polymerization at high temperatures is known to have advantages in terms of molecular weight control, ease of continuous processing and efficient use of energy (see US Pat. No. 4,768,428).

In general, in the solution polymerization method, the resulting ethylene polymer is dissolved in the polymerization solvent to increase the viscosity of the polymerization solution, so that the polymerization temperature is preferably as high as possible to facilitate the operation of the process. However, since the activity of the catalyst and the molecular weight of the polymer decreases as the polymerization temperature increases, the catalyst for high temperature solution polymerization should have a sufficiently high activity even at high temperature and be able to produce a polymer having a sufficiently high molecular weight. In particular, when the activity of the catalyst is low, a large amount of residue of the catalyst remains in the polymer after polymerization, which not only causes corrosion of metal parts of the processing equipment due to the catalyst residue during processing, but also the physical properties of the polymer, for example, resin during processing. Thermal stability of the final product and the stability of the final processed product against ultraviolet rays may be greatly reduced.

Therefore, a process for removing the catalyst residue in the polymer is required separately, and this process has a complicated and expensive disadvantage. Therefore, by increasing the high temperature stability of the catalyst, that is, the polymerization activity at a high temperature, the catalyst residue removal process is reduced or It is also desirable to make it unnecessary. In addition, if the polymerization time becomes too long at a high temperature, the catalyst may be deteriorated by heat, resulting in a change in the molecular weight distribution of the resulting polymer, and in addition, in the case of copolymerization, a change in the content of alpha olefins inserted into the polymer, Changes in distribution or the like result in the production of non-uniform copolymers. Therefore, the catalyst for high temperature solution polymerization should be able to produce the polymer in sufficiently high yield in a relatively short polymerization time. For this reason there has been an increasing need for catalysts that can be used at high temperatures. In addition, in recent years, regulations on the amount of transition metals in polymers have been tightened in relation to environmental regulations, and the need for development of a high activity catalyst is further increased.

Highly active catalysts for ethylene polymerization are prepared by immobilizing a transition metal component on a support mainly composed of a solid organic or inorganic substance by physical or chemical treatment.

A representative example of such a support is magnesium chloride, and a large amount of TiCl ₄ is added to the fine spherical particles prepared by spray-drying of magnesium chloride added with alcohol as in US Pat. Nos. 4,421,674 and 4,481,342 in addition to the general ball mill or vibration mill method. There is a method of preparing a catalyst by treating.

The transition metal used in such a catalyst is a compound which generally shows high yield and high productivity, and other transition metal components such as V, Zr or Hf compounds may be used together with the Ti compound. Such examples are well known in US Pat. Nos. 4,109,071, 4,154,701, 4,192,772, 4,210,559, 4,226,964, and 4,245,071. However, such catalysts do not exhibit sufficient high activity in high temperature solution polymerization, which makes it difficult to apply the process. In particular, two-component catalyst systems consisting of Ti compounds and V compounds as ethylene polymerization catalysts are introduced in US Pat. Nos. 3,899,477 and 5,059,570, but are not suitable for high temperature solution polymerization as polymerization catalyst systems for low temperature slurries.

Although a catalyst system having a transition metal compound in chloride of magnesium in a catalyst system exhibiting high activity at high temperatures is known from Japanese Patent Application Laid-Open No. 60-101105, the production process is complicated and the process of washing unreacted compounds from the catalyst of the manufacturer Since it has to go through, there is a disadvantage that a separate catalyst manufacturing facility and a large amount of cleaning solvent are consumed.

Another two-component catalyst system is known from US Pat. No. 4,330,647, which polymerizes a precipitate obtained by reacting a solid product resulting from the reaction of an organic magnesium compound with a halogen compound with a transition metal and a metal compound together with an organoaluminum compound. Used for EP-A 132,288 also discloses a catalyst system in which a solid compound produced from the reaction of an organic magnesium compound with a chlorosilane compound is reacted again with an electron donor to obtain a precipitate to react with a transition metal compound.

However, a disadvantage of these catalyst systems is that they take a long time to prepare the primary reaction precipitate and the process is complicated. In particular, the efficiency and simplicity of the process operation are very important in the actual process application of the catalyst, but it is disadvantageous to the process application in the case of requiring a long time reaction or separate sediment in the production of the catalyst as described above.

U.S. Patent No. 5,013,701 describes a catalyst system using Ti and V compounds together with Mg compounds, wherein the polymerization activity is not sufficient for application to solution polymerization.

U.S. Patent No. 4,330,647 discloses a two-component catalyst system having high activity at high temperatures. The first component is obtained by reacting a reaction product of an organic Mg compound with a trichloride or tetrachloride hydrocarbon with a transition metal, but it takes a long time to prepare such a catalyst. In addition, since the sediments formed are not separated and supplied into the reactor as they are, there is a possibility that problems such as clogging of the raw material line may occur during the process application.

A new mixed catalyst using Ti and V compounds together as a transition metal in a magnesium halide carrier and using triethylaluminum as a promoter is known from US Pat. No. 4,612,300. The first component contains a trace amount of aluminum and magnesium The atomic ratio of aluminum to aluminum does not exceed 0.5, and the atomic ratio of aluminum to transition metal is also low. However, in order to obtain high activity at a high temperature, there are disadvantages in that various components must be mixed and reacted for a long time, and at high temperature polymerization of 180 ° C. or higher, catalytic activity is severely lowered, and thus it is necessary to remove the catalyst residue.

According to European Patent Publication No. 155,770, catalyst precipitates are obtained by the reduction of V compounds in magnesium chloride containing magnesium-carbon bonds and trace electron donors, where the reduction of V compounds is carried out without the addition of other reducing agents. It is made of a compound having a carbon bond. However, this reduction can be increased by adding a separate reducing agent or by changing the reaction conditions. That is, in order for the catalyst to have activity, the component ratio of the transition metal, aluminum, and halogen must be properly configured, and the transition metal must be treated with a reducing agent having a suitable reducing power in addition to these components. In addition, the catalytic activity may vary greatly depending on the reducing agent and transition metal or catalyst production conditions.

The present inventors have the advantage of being applicable to the continuous polymerization, but the catalyst manufacturing process is simple and does not require a separate manufacturing equipment, and is present in the polymer by showing higher activity than that by the methods known above under solution polymerization conditions. As a result of extensive research in order to provide a catalyst system capable of further reducing the catalyst residue, and at the same time, a polymer having a sufficiently high molecular weight, a method of producing a catalyst system having excellent performance has been found, leading to the present invention.

An object of the present invention is to provide a method for producing a catalyst for ethylene polymerization that can solve the above problems and disadvantages.

In addition, another object of the present invention to provide a method for producing an ethylene polymer in a high yield using a catalyst prepared for the above production method.

A method for preparing the catalyst for ethylene polymerization of the present invention for achieving the above object is to heat the main catalyst consisting of a mixture of a transition metal compound, an organic Mg compound, an organic Al compound, and then injected into a polymerization promoter of an organic Al compound. Is done.

Hereinafter, the present invention will be described in more detail.

The main catalyst mixture obtained by adding the organic Mg compound, the organic Al compound, the Ti compound, and the V compound was heat-treated at a temperature of 25 to 250 ° C. for 10 seconds to 60 minutes, and then polymerized in which the organic Al compound as a polymerization promoter was dissolved. Injection into the reaction solution can yield ethylene alone or a copolymer of ethylene and single wave olefin in high yield.

Such a polymer prepared by the present invention has a sufficiently high molecular weight, and depending on the use, it is possible to control the temperature at the time of polymerization, and to control the molecular weight by the component ratio of hydrogen or the components of the catalyst, stabilizers, crosslinking agents Alternatively, additives such as fillers may be contained and applied.

The catalyst system is composed of a polymerization main catalyst component and a polymerization promoter component. The polymerization main catalyst component is a component obtained by heat-treating a mixture of a Ti compound, a V compound, an organic Mg compound, and an organic Al compound, and the polymerization promoter component is an organic Al. Compound.

The Ti compound is a compound represented by the following general formula (I),

TiX _n (OR ¹ ) _4-n (I)

Wherein n is an integer of 0 to 4, R ¹ represents an identical or different hydrocarbon group having 1 to 18 carbon atoms, preferably an alkyl group of 2 to 8, and X represents a halogen atom such as Cl or Br.

Examples of such compounds include TiCl (On-Bu) ₃ , TiCl ₂ (On-Bu) ₂ , TiCl ₃ (On-Bu), TiCl ₄ , Ti (Oi-Pr) ₄ or Ti (OEt) ₄ , wherein n -Bu is a normal butyl group, i-Pr is an isopropyl group, Et is an ethyl group, which is used in the same sense, preferably TiCl ₄ or Ti (On-Bu) ₄ , it is also possible to use a mixture of the two It is possible.

The V compound is a compound represented by the following general formula (II) or (III),

VO (OR ² ) _3-p X _p (II)

VX ₄ (III)

In the above formula, p is an integer of 0 to 3, R ² represents the same or different hydrocarbon group of 1 to 18 tin atoms, preferably an alkyl group of 1 to 18, and X represents a halogen atom such as Cl or Br.

Examples of such compounds are VOCl ₃ , VO (OEt) Cl ₂ , VO (OEt) ₂ Cl, VO (On-Bu) Cl ₂ , VO (On-Bu) ₂ Cl, VO (On-Bu) ₃ or VCl ₄ . , Preferably VOCl ₃ .

The organic Mg compound is a compound represented by the following general formula (IV) or (V),

MgR ³ R ⁴ (IV)

(MgR ³ R ⁴ ) zAlR ⁵ ₃ (V)

In the above formula, R ³ , R ⁴ and R ⁵ represent the same or different alkyl group having 1 to 18 carbon atoms, alkoxy group or aryl group having 6 to 18 carbon atoms, and z is an integer of 1 or more.

Examples of such compounds are dioctyl magnesium, dihexyl magnesium, dibutyl magnesium, butyl octyl magnesium, butyl ethyl magnesium, and the like, preferably butyl ethyl magnesium.

The organic Al compound in the main catalyst component is used by mixing at least one base or two bases selected from the compounds represented by the following general formula (VI) or (VII),

R ⁶ ₃ -qAlXq (VI)

R ⁷ ₃ Al ₂ X ₃ (VII)

Wherein q is 1 or 2, R ⁶ , R ⁷ are the same or different alkyl groups having 1 to 12 carbon atoms, and X represents a halogen atom such as Cl, Br and the like.

Examples of such compounds are EtAlCl ₂ , Et ₃ Al ₂ Cl ₃ , Et ₂ AlCl or BuAlCl ₂ , more preferably Et ₃ Al ₂ Cl ₃ or EtAlCl ₂ .

The organic Al compound which is the polymerization promoter component includes one of the compounds of the following general formulas (VII) to (X), including the above-mentioned organic Al compound component,

R ⁸ ₃ -sAlXs (VII)

R ⁹ ₂ AlO (R ⁹ AlO) tAlR ⁹ ₂ (IX)

R ¹⁰ _3-u Al (OR ¹⁰ ) _u (X)

Wherein s is 0, 1 or 2, t is an integer of 0 or more, u is 1 or 2, and R ⁸ , R ⁹ , R ¹⁰ are the same or different hydrocarbon groups having 1 to 18 carbon atoms, preferably For example, 2 to 6 identical or different alkyl, cycloalkyl, aryl groups, and X represents a halogen atom such as Cl or Br.

Examples of such compounds are AlEt ₃ , Al (i-Bu) ₃ , (i-Bu) ₂ AlOAl (i-Bu) ₂ , Et ₂ AlOEt, Al (i-Bu) ₃ , Al (n-Hex) ₃ , Al (n-Oct) ₃ and the like, and preferably Et ₂ AlOEt, (i-Bu) ₂ AlOAl (i-Bu) ₂ , and Al (i-Bu) ₃ . It is also possible to use these polymerization promoters in combination with other organic Al compounds.

The atomic ratio of Ti to V is 0.01-10, Preferably it is 0.5-2. The atomic ratio of Mg to the total transition metal of Ti and V is 0.1-20, preferably 0.5-10. If the composition ratio of Mg to the transition metal is out of such a range, the catalytic activity is lowered during polymerization, and in particular, when used at a too low ratio, the polymer may be colored due to low catalytic activity. The atomic ratio of Al in the main catalyst component to the total transition metal of Ti and V is 1 to 100, preferably 2 to 50. The atomic ratio of the polymerization promoter Al to the total transition metals of Ti and V is 0.1 to 200, preferably 0.5 to 100. If the composition ratio of Al to the transition metal is out of this range, the catalytic activity decreases during polymerization. The amount of catalyst used in the polymerization is 0.001 to 2.5 mmol / 1, preferably 0.01 to 1 mmol / 1 in combination with the Ti compound and the V compound. Also larger amounts may be used depending on the reaction conditions.

The solvent used for the polymerization reaction is, for example, aliphatic hydrocarbons such as pentane, hexane, heptane, octane, dodecane and aromatic hydrocarbons such as benzene, toluene, xylene, chlorobenzene, or cyclohexane, methylcyclohexane, cyclopentane Alicyclic hydrocarbons, such as these, These can be used individually or in mixture. The diluent used in the preparation of the catalyst component may be suitably applied to the solvent depending on the preparation conditions of the catalyst, but most preferably dodecane or hexadecane is used.

In the practice of the present invention, the polymerization main catalyst mixture of each component is heat-treated before mixing with the polymerization promoter or before injecting into the polymerization reactor, after mixing some or all of the main catalyst components at a temperature lower than 50 ° C. It means heating between 25 to 250 ° C., preferably between 80 to 200 ° C. for 10 seconds to 60 minutes, preferably for 30 seconds to 5 minutes. Through such a heat treatment process, the bonding state between the metal components and the particle structure and size of the catalyst are appropriately changed to increase the polymerization activity.

Each polymerization main catalyst component can be supplied separately or in combination to the heat treatment feeder, although the mixing order of each component does not significantly affect the catalytic activity, but preferably the organic Mg compound and organic Al in the main catalyst component It is preferable to heat-process by mixing a compound first, and then adding a Ti compound and a V compound.

The heat treatment temperature affecting the activity of the catalyst can be changed depending on the catalyst component. For example, the heat treatment temperature is also changed by the composition ratio of Ti and V, the amount and type of organic Al compound, and especially the type of Ti compound. In general, to increase the activity of the catalyst requires a higher heat treatment temperature when using Ti (OR ⁹ ) ₄ than when using TiX ₄ .

The heat treated main catalyst component may be mixed with the polymerization promoter component or separately introduced into the polymerization reactor. In the case of continuously supplying the catalyst to the reactor, the heat treatment method is to heat the main catalyst component supplied in the heat treatment apparatus or to supply the solvent heated up to the heat treatment temperature into the catalyst supply line to which the main catalyst component is supplied. The heat-treated main catalyst component can be used as it is without separating liquid and solid materials, and after washing 1 to 5 times with inert hydrocarbon, the solid component is a hydrocarbon solvent such as pentane, hexane, heptane, octane, dode It can be diluted in a cell or the like and injected into the reactor. In this case, there was little catalytic polymerization activity by the liquid component, and it was found that the solid component was most of the catalytically active component. In addition, when the solid slurry thus washed is used as a catalyst, there is a possibility of further reducing the content of metal components such as Al in the intermediate body.

A method for preparing an ethylene polymer for achieving another object of the present invention is to prepare a mixture of ethylene or ethylene and alpha olefin having 3 to 16 carbon atoms of up to 10% by weight in a slurry, solution or gas phase at a temperature of 20 to 320 ℃ It consists of superposing | polymerizing using the catalyst mentioned above under the pressure of -800 atmosphere, Preferably it can carry out on conditions which are 110-260 degreeC of polymerization temperature, and 10-300 atmosphere of polymerization reactor pressure. The polymerization can be carried out by a batch method or a continuous polymerization method.

The present invention will be described in more detail with reference to the following examples, but the following examples are only specific embodiments of the present invention, and are not intended to limit the present invention.

Example 1

Preparation of catalyst

The rotor was placed in a sufficiently dried small glass bottle (20 ml), and the inside was replaced with a nitrogen atmosphere. Then, 76 μmol (2.0 vol.% Solution) of butyl ethyl magnesium (BEM) diluted with dodecane and 625 μmol of ethyl aluminum dichloride (EADC) were added. (1.0 vol% solution) was mixed. Next, a mixture of TiCl ₄ 7.75 μmol (0.1 vol.% Solution) and VOCl ₃ 9.05 μmol (0.1 vol.% Solution) was injected, followed by heat treatment at 120 ° C. for 3 minutes to obtain a heated brown slurry composition. The atomic ratio of each component in the catalyst composition is Ti / V = 0.856, Mg / (Ti + V) = 4.52, Al / (Ti + V) = 33.9.

Polymerization

The polymerization was carried out in a 4L stainless steel pressure reactor, 2L of normal hexane and 1.98 mmol of tetraisobutylaluminum (TIBA), a polymerization promoter, were heated to 140 ° C, and the reactor was filled with ethylene to maintain a pressure of 140 psig. All of the prepared catalyst composition was injected and polymerized for 10 minutes while maintaining ethylene pressure at 160 psig. Thereafter, 10 ml of isopropyl alcohol was added to terminate the polymerization, and then cooled to obtain a white solid polymer. The polymer was filtered and dried in a vacuum oven maintained at 60 ° C. for 18 hours. The weight of the polymer was 60 g, and the catalytic activity was 72.1 kg / g-Ti, V per weight of the transition metal (Ti + V).

Comparative Example 1

In the catalyst preparation and polymerization method of Example 1, a BEM solution, an EADC solution, and a mixed solution of TiCl ₄ and VOCl ₃ were performed in the same manner except that the mixture was directly used for ethylene polymerization without undergoing a heat treatment process.

The weight of the dried polymer was 19 g, and the catalytic activity was 19.6 kg / g-Ti, V per weight of the transition metal (Ti + V).

The weight average molecular weight (Mw) of the polymer measured by gel chromatography was 424,515, the molecular weight distribution (Mw / Mn) was 5.32, and the melt flow index Ml (21.6 kg load, g / 10 min) was 0.2.

Comparative Example 2

In the above catalyst preparation and polymerization method, VOCl ₃ was not used as the main catalyst component, except that 16.8 μmol of TiCl ₄ was used instead.

The weight of the dried polymer was 25 g, and the catalytic activity was 30.0 kg / g-Ti per weight of the transition metal.

The melt flow index MI (21.6 kg load, g / 10 min) of the polymer was 0.5.

Comparative Example 3

In the catalyst preparation and polymerization method of Example 1, TiCl ₄ was not used as the main catalyst component, and instead of using 16.8 μmol of VOCl ₃ , the same method was used.

The weight of the dried polymer was 8 g, and the catalytic activity was 9.3 kg / g-V per weight of the transition metal.

The melt flow index MI (21.6 kg load, g / 10 min) of the polymer was 0.10.

Examples 2-11

In the catalyst preparation and polymerization method of Example 1, the same method was used except that the amounts of BEM and EADC were changed, respectively, and the results are shown in Table 1 below.

TABLE 1

Note) BEM: Butyl ethyl magnesium EADC: Ethyl aluminum dichloride MI (Melt Flow Index): g / 10 min, measured at 21.6 kg load.

Example 12

In the catalyst preparation and polymerization method of Example 1, 9.98 µmol of Ti (On-Bu) ₄ was used instead of TiCl ₄ , and 1.3 mmol of tetraisobutyldialuminum oxide (TIBAO) was used instead of TIBA as a polymerization promoter. The same procedure was followed except for the above.

The weight of the dried polymer was 46 g, and the catalytic activity was 47.2 kg / g-Ti, V per weight of the transition metal.

The weight average molecular weight (Mw) of the polymer measured by gel chromatography was 435,056, the molecular weight distribution (Mw / Mn) was 5.31, and the melt flow index MI (21.6 kg load, g / 10 min) was 0.15.

Examples 13-16

In the catalyst preparation and polymerization method of Example 12, instead of using the Ti (On-Bu) ₄ to Ti (On-Bu) ₄ and TiCl ₄ were used and mixed in various ratios as shown in the following Table 2 The same procedure was followed except that the amount of BEM and EADC was changed. The results are shown in Table 2 below.

TABLE 2

Note) TBT: Tetra-n-butoxy titanium (Ti (On-Bu) ₄ )

MI (Melt Flow Index): g / 10 min, measured at 21.6 kg load.

Example 17

Solid components were separated from the main catalyst components in the slurry state prepared in the same manner as in Example 1, washed three times with 10 ml of dodecane, and a solid catalyst was obtained. Composition Mg obtained by elemental analysis of a solid component; 6.5 wt%, Ti; 1.42 wt%, V; 1.71 wt%, Al; 11.5 wt%. A solid catalyst was prepared in the same manner, and ethylene polymerization was carried out in the same manner as described in the polymerization method of Example 1. The weight of the dried polymer was 67 g, and the activity of the converted catalyst per weight of the transition metal (Ti + V) was 85.6 kg / g-Ti, V. The weight average molecular weight (Mw) of the polymer measured by gel chromatography was 403,053, the molecular weight distribution Mw / Mn was 4.98, and the melt flow index MI (21.6 kg load, g / 10 min) was 0.20.

Example 18

In the catalyst production and polymerization method of Example 1, the same method was used except that 570 µmol of Et ₃ Al ₂ Cl ₃ (EASC) was used in place of EADC in the main catalyst component. The weight of the dried polymer was 59 g and the activity of the converted catalyst per weight of the transition metal (Ti + V) was 70.9 kg / g-Ti, V.

The weight average molecular weight (Mw) of the polymer measured by gel chromatography was 295,309, the molecular weight distribution (Mw / Mn) was 4.78, and the melt flow index MI (21.6 kg load, g / 10 min) was 0.65.

Claims (9)

A catalyst for ethylene polymerization, which is prepared by heat-treating a polymerization main catalyst mixture composed of an organic Mg compound, an organic Al compound, a Ti compound, and a V compound, and then injecting it into a polymerization solution in which an organic Al compound promoter is dissolved. Manufacturing Method: The Ti compound is represented by the following general formula (I), TiX _n (OR ¹ ) _4-n (I) Wherein n is an integer of 0 to 4, R ¹ is the same or different hydrocarbon group having 1 to 18 carbon atoms, and X represents a halogen atom; The said V compound is represented by the following general formula (II) or (III), VO (OR ² ) _3-p X _p (II) VX ₄ (III) Wherein p is an integer of 0 to 3, R ² is the same or different hydrocarbon group having 1 to 18 carbon atoms, and X represents a halogen atom; The organic Mg compound is represented by the following general formula (IV) or (V), MgR ³ R ⁴ (IV) _{^{(MgR 3 R 4) z ·}} AIR 5 3 (V) Wherein R ³ , R ⁴ and R ⁵ represent the same or different alkyl groupalkoxy group having 1 to 18 carbon atoms or aryl group having 6 to 18 carbon atoms, and z is an integer of 1 or more; The organic Al compound in the main catalyst component is used by mixing one or two or more selected from the compounds represented by the following general formulas (VI) and (VII), R ⁶ _3-q AlX _q (VI) R ⁷ ₃ Al ₂ X ₃ (VII) Wherein q is 1 or 2, R ⁶ and R ⁷ are the same or different alkyl groups having 1 to 12 carbon atoms, and X represents a halogen atom; And The organic Al compound cocatalyst component is one of the compounds of the following general formulas (VIII) to (X). R ⁸ ₃ -sAlX _s (VIII) R ⁹ ₂ AlO (R ⁹ AlO) _t AlR ⁹ ₂ (IX) R ¹⁰ _3-u Al (OR ¹⁰ ) _u (X) Wherein s is 0, 1 or 2, t is an integer of 0 or more, u is 1 or 2, and R ⁸ , R ⁹ and R ¹⁰ represent the same or different hydrocarbon groups having 1 to 18 carbon atoms, X represents a halogen atom. The method for producing an ethylene polymerization catalyst according to claim 1, wherein the atomic ratio of Ti to V is 0.01 to 10. The method for producing an ethylene polymerization catalyst according to claim 1, wherein the atomic ratio of Mg to the sum of Ti and V is 0.1 to 20. The method for producing an ethylene polymerization catalyst according to claim 1, wherein the atomic ratio of Al in the main catalyst component to the sum of Ti and V is 1 to 100. The method for producing an ethylene polymerization catalyst according to claim 1, wherein the atomic ratio of the polymerization promoter component Al to the total of Ti and V is 0.1 to 200. The ethylene polymerization according to claim 1, wherein the mixture of the respective main catalyst components is activated by heat treatment at 25 to 250 DEG C for 10 seconds to 60 minutes before injection into the polymerization reactor or before mixing with the polymerization promoter. Method for preparing a catalyst. After heat-treating the polymerization main catalyst mixture consisting of the organic Mg compound, the organic Al compound, the Ti compound and the V compound, it is ethylene or ethylene in which the organic Al compound promoter is dissolved and an alpha-olefin having 3 to 16 carbon atoms of up to 10% by weight. Method of producing an ethylene polymer, characterized in that it is injected into the polymerization solution of the solution and solution polymerization at a temperature of 20 to 320 ℃ and pressure of 1 to 800 atm. The Ti compound is represented by the following general formula (I), TiX _n (OR ¹ ) _4-n (I) Wherein n is an integer of 0 to 4, R ¹ is the same or different hydrocarbon group having 1 to 18 carbon atoms, and X represents a halogen atom; The said V compound is represented by the following general formula (II) or (III), VO (OR ² ) _3-p X _p (II) VX ₄ (III) Wherein p is an integer of 0 to 3, R ² is the same or different hydrocarbon group having 1 to 18 carbon atoms, and X represents a halogen atom; The organic Mg compound is represented by the following general formula (IV) or (V), MgR ³ R ⁴ (IV) _{^{(MgR 3 R 4) z ·}} AlR 5 3 (V) In which R ³ , R ⁴ and R ⁵ represent the same or different alkyl groups, alkoxy groups or aryl groups having 6 to 18 carbon atoms, and z is an integer of 1 or more; The organic Al compound in the main catalyst component is used by mixing one or two or more selected from the compounds represented by the following general formulas (VI) and (VII), R ⁶ _3-q AlX _q (VI) R ⁷ ₃ Al ₂ X ₃ (VII) Wherein q is 1 or 2, R ⁶ and R ⁷ are the same or different alkyl groups having 1 to 12 carbon atoms, and X represents a halogen atom; And Said organic Al compound cocatalyst component is one of the compounds of the following general formulas (VIII) to (X): R ⁸ _3-s AlX _s (VIII) R ⁹ ₂ AlO (R ⁹ AlO) _t AlR ⁹ ₂ (IX) R ¹⁰ _3-u Al (OR ¹⁰ ) _u (X) Wherein s is 0, 1 or 2, t is an integer of 0 or more, u is 1 or 2, and R ⁸ , R ⁹ and R ¹⁰ represent the same or different hydrocarbon groups having 1 to 18 carbon atoms, X represents a halogen atom. 8. The method of claim 7, wherein the main catalyst component is mixed with a cocatalyst and introduced into the polymerization reactor or separately introduced into the polymerization reactor. The method of claim 7, wherein the main catalyst is supplied in a liquid phase together with a solvent or in a solid phase after washing with an inert solvent.