JPH0132847B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing polyolefin. More specifically, the present invention relates to a method for producing a low-density ethylene-α-olefin copolymer using a novel catalyst containing a magnesium compound and a titanium compound. It is known that a catalyst system containing a magnesium compound or a titanium compound can be used for the polymerization of olefins, and the present inventors also previously reported
131886 and JP-A-131887, he proposed a solid complex catalyst for olefin polymerization containing magnesium, titanium, and an electron donor compound. These catalyst systems have relatively high activity and the resulting polymers have a very narrow molecular weight distribution. When high-density polyethylene is produced by slurry polymerization, there are many advantages such as a high bulk density of the resulting polymer. However, this catalyst system causes deterioration of slurry properties when attempting to produce a low-density (0.930 g/cc or less) copolymer by copolymerizing ethylene and α-olefin using a slurry polymerization method. The disadvantage was that the bulk density of the polymer decreased. Therefore, as a result of intensive studies to improve these drawbacks, the inventors of the present invention discovered that the carbonized carbonization compound separated from the reaction mixture obtained by further reacting the above-mentioned solid complex containing magnesium, titanium, and an electron donor with an organoaluminum compound. Hydrogen-insoluble solids can be used as catalysts for olefin polymerization that are significantly more active than the solid complexes described above, and have a narrow molecular weight distribution, making them suitable for the production of low-density ethylene-α-olefin copolymers by slurry polymerization. The present invention was accomplished by discovering that a polymer with high bulk density can be obtained. That is ^{, the} gist of the present invention _is that the general _formula Mg _{l TiX} ¹ _2l [In the formula, X ¹ and X ² represent a halogen atom, R ¹ represents an alkyl group, an aryl group, or a cycloalkyl group, and D represents an electron donor compound selected from ether, carboxylic acid ester, alcohol, and amine. where l represents a number in the range of 0.1 to 100. m represents a number in the range of 2 to 4, n represents a number in the range of 0 to 1, and m+n is a number that corresponds to the valence of titanium. p is a number ranging from 2 to 200. ] and ^a solid complex represented by the general formula AlR ² _q X ³ _3-q [wherein R ² represents an alkyl group, aryl group or cycloalkyl group,
q indicates a number in the range of 1 to 3. A catalyst system comprising a combination of a hydrocarbon-insoluble solid catalyst component separated from a reaction mixture obtained by reacting an organoaluminum compound represented by ] with a cocatalyst organoaluminum compound, Ethylene-α with less than 0.935g/cc
- A method for producing an olefin copolymer. To further explain the present invention in detail, the general formula Mg _l TiX ¹ _2l X ² _n (OR ¹ ) _o ·(D) _p [ In the formula, X ¹ , X ² , R ¹ , D, l, m, n, p are
As shown above. ] As a solid complex represented by
X ¹ and X ² are chlorine atoms, D is ether,
Particularly preferred are compounds in which n is 0. D
As for R 1 , those exemplified as the electron donor compound shown below are as examples, and as R ¹ , those exemplified as R ⁴ in the general formula of the halogen-containing compound of titanium below are as examples.
The same can be mentioned. Such a solid complex is thus prepared by co-precipitating a halogen-containing compound of magnesium halide and titanium from an electron donor compound solution. Here, the magnesium halide has the general formula MgX ⁵ ₂ [wherein, X ⁵ represents a halogen atom]. ] is used. Specific examples include anhydrous magnesium chloride, anhydrous magnesium bromide, and anhydrous magnesium iodide. Among them, anhydrous magnesium chloride is preferred. On the other hand, a halogen-containing compound of titanium has the general formula TiX ⁶ _n (OR ⁴ ) _o [wherein, X ⁶ is a halogen atom, R ⁴ is an alkyl group,
Represents an aryl group or a cycloalkyl group, m is 2
n represents a number in the range of 0 to 1, where m+n corresponds to the valence of titanium. ] is used. Specifically, titanium tetrachloride, titanium trichloride, titanium tetrabromide, titanium tribromide, titanium tetraiodide, titanium triiodide, titanium tetrafluoride, titanium trifluoride, monoethoxytrichlortitanium, and monopropoxytrichlor. Examples include titanium, monobutoxytrichlorotitanium, and the like. Among them, titanium tetrachloride and titanium trichloride are preferred. Next, specific examples of electron donor compounds include aliphatic ethers such as diethyl ether and dibutyl ether, cyclic ethers such as tetrahydrofuran and tetrahydropyran, carboxylic acid esters such as ethyl acetate and ethyl benzoate, ethanol, butanol, etc. Among these, tetrahydrofuran is preferred. To produce a solid complex, the above halogen-containing compounds of magnesium halide and titanium are mixed in an appropriate ratio, then an excess of an electron donor compound is added, and the reaction is carried out at a temperature ranging from 0°C to the boiling point of the electron donor compound. to form a complex to obtain a solution of the electron donor compound, and then cool and crystallize the solution, evaporate and distill off the electron donor compound, or add a poor solvent such as a hydrocarbon, etc. , by co-precipitation. Alternatively, an electron donor compound complex of magnesium halide and an electron donor compound complex of a halogen-containing titanium compound are synthesized separately, and both are mixed and dissolved in the electron donor compound, and then the above method is performed. A solid complex can also be obtained by co-precipitation. The ratio of magnesium halide to the halogen-containing compound of titanium is Mg/Ti (atomic ratio) from 0.1 to
The range is 100. If this value is outside the above range, the polymerization activity of the resulting catalyst will be insufficient. Next ^, the solid complex produced by ^the above method was prepared in a hydrocarbon solvent with the general ^formula _AlR ² _q indicates a halogen atom,
q is a number ranging from 1 to 3. ] is reacted with an organoaluminum compound represented by Specific examples of the organoaluminum compounds used here include ethylaluminum dichloride, ethylaluminum sesquichloride, diethylaluminium monochloride, triethylaluminum, triisobutylaluminum, etc. Among them, ethylaluminum dichloride, ethylaluminum sesquichloride, diethylaluminium Monochloride is preferred. Although the treatment temperature is not particularly limited, it is usually carried out within a temperature range of room temperature to 65°C. Hydrocarbon solvents used include hexane,
Examples include aliphatic hydrocarbons such as heptane, alicyclic hydrocarbons such as cyclohexane, and aromatic hydrocarbons such as benzene and toluene. Particularly preferred are solvents in which the reaction product of the organic aluminum compound and the organic aluminum compound is soluble. Regarding the amount of the organoaluminum compound to be used, the molar ratio is 0.1<organoaluminum compound/electron donor compound<10, preferably 0.2<organoaluminum compound, in relation to the amount of the electron donor compound in the solid complex. Amounts are used such that compound/electron donor compound<5. A solid insoluble in the hydrocarbon solvent is thus obtained, and this solid is separated from the by-product reaction product of the organoaluminum compound and the electron donor compound. Specifically, the solid is separated from the reaction mixture by filtration, decantation, etc., and then washed with an inert hydrocarbon solvent, or an inert hydrocarbon solvent is added to the reaction mixture, and the washing treatment and separation are performed simultaneously. Good too. As the inert hydrocarbon solvent used here, the inert hydrocarbon solvent used previously in the reaction of the solid complex and the organoaluminum compound is used. The remaining amount of the electron donor compound component in the hydrocarbon-insoluble solid catalyst component obtained by this operation is determined by the molar ratio of the electron donor compound to the sum of magnesium atoms and titanium atoms: 0<electron donor compound/(Mg+Ti) <1.5. In this range, a catalyst for olefin polymerization can be obtained which has extremely high activity and a narrow molecular weight distribution, and which gives a polymer with high bulk density in slurry polymerization. Next ^, as an organoaluminum compound used as a cocatalyst ^, for example, ^the general formula _AlR ³ _r ,
r is 2 or 3. ] Examples include organoaluminum compounds represented by the following. Specifically, triethylaluminum, triisobutylaluminum,
Diethylaluminium monochloride is mentioned. The ratio of the hydrocarbon-insoluble solid catalyst component to the organoaluminum compound is usually within the range of 0.1 to 100, preferably 1 to 20, in terms of Al/Ti atomic ratio. The thus prepared catalyst system is used to copolymerize ethylene and α-olefin.
1, pentene-1 octene-1, and the like.
As the copolymer of ethylene and other α-olefin, a copolymer of ethylene and other α-olefin containing up to 20% by weight, preferably 15% by weight of α-olefin other than ethylene is produced. In this case, the density of the copolymer is approximately 0.91 g/cc, although it varies depending on the type of α-olefin.The polymerization reaction is carried out by solution polymerization or slurry polymerization in an inert solvent, or gas phase polymerization carried out in the absence of a solvent. Either method can be used. This is usually carried out by supplying the olefin or olefin mixture in the presence of an inert solvent and maintaining it at a predetermined temperature and pressure. Examples of inert solvents include aliphatic hydrocarbon solvents, specifically propane, isobutane, normal butane, normal pentane, normal hexane, normal octane, etc., or mixtures thereof, and alicyclic hydrocarbon solvents such as cyclopentane, cyclohexane, etc. Among these, aliphatic hydrocarbons having 4 to 6 carbon atoms are preferred. Polymerization reactions are usually carried out at room temperature
The temperature is selected from the range of 250°C and the pressure of normal pressure to 100 atmospheres. Further, in the method of the present invention, when hydrogen is present in the polymerization reaction zone, the effect of controlling the molecular weight by hydrogen is large, and a polymer having a desired molecular weight can be easily obtained. The amount of hydrogen to be present varies depending on the polymerization conditions, the desired molecular weight of the olefin polymer, etc., and therefore it is necessary to adjust the amount of hydrogen introduced accordingly. Furthermore, in addition to the above method, the effects of the present invention can be further enhanced by pre-treating or prepolymerizing the catalyst component for olefin polymerization with olefin prior to olefin polymerization. In the present invention, examples of olefins that can be used in the pretreatment or prepolymerization of catalyst components with olefins include those previously used in the polymerization of olefins and mixtures thereof. Further, the olefin used in the pretreatment or prepolymerization may be different from the olefin used in the polymerization. The ratio of the hydrocarbon-insoluble solid catalyst component and organoaluminum compound that make up the catalyst system used in prepolymerization is usually 0.001 to 0.001 in terms of Al/Ti atomic ratio.
100, preferably 0.01 to 50, more preferably
It ranges from 0.1 to 10. If the proportion of the organoaluminum compound used is outside the above range, the prepolymerization activity may be too low or the polymerization activity in the main polymerization may decrease, which is not preferable. The amount of polymerization in the prepolymerization is 1 to 200 g, preferably 1 to 100 g, and more preferably 5 to 50 g per 1 g of the hydrocarbon-insoluble catalyst component constituting the catalyst system. If the amount of prepolymerization is too small, no effect will be observed, and if the amount of prepolymerization is too large, fish eyes will occur in the polyethylene or ethylene copolymer produced, which is undesirable. There are no particular restrictions on the temperature, pressure, time, monomer feed rate, catalyst concentration, presence or absence of a molecular weight regulator such as hydrogen, and whether or not the prepolymerization catalyst is washed after prepolymerization, but the polymerization temperature is usually , -40°C to 100°C, preferably 0°C to 90°C. The pressure may be 50 atmospheres or less, and the polymerization time may be several minutes to several hours, but usually a small amount of prepolymerization is sufficient, so high pressure and long periods of time are not required. Also, the addition of a molecular weight regulator such as hydrogen during prepolymerization improves the uniformity of the polyethylene or ethylene copolymer produced.
Washing the prepolymerization catalyst is effective in preventing polymer adhesion to the polymerization reactor during main polymerization. According to the method of the present invention as described above, the catalyst system has extremely high activity and the obtained polymer has a high bulk density. Especially low density ethylene by slurry polymerization method ~
Even when producing an α-olefin copolymer, the resulting polymer has good slurry properties and a high bulk density, so it is possible to carry out stable continuous polymerization over a long period of time. In addition, the resulting polymer has a narrow molecular weight distribution, and even when copolymerizing higher α-olefins, the copolymerizability is good, so even if the amount of α-olefin used is small, a polymer with a high α-olefin content can be produced. It has the advantage of being able to obtain Furthermore, by pre-treating or prepolymerizing with olefin prior to polymerization of olefin, the slurry properties of the polymer can be further improved and a polymer powder with a high bulk density can be obtained. Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. Also, the first
The figure is a flowchart diagram to help understand the technical content included in the present invention, and the present invention is not limited in any way by the flowchart diagram as long as it does not depart from the gist thereof. In addition, in the examples,
The polymerization activity K of the catalyst is K=(g polymer)/(g・
(catalyst) (hr) (Kg/cm ² olefin pressure), and the polymerization activity per titanium, KTi, is KTi = (g polymer)/(g・Ti) (hr) (Kg・cm ² olefin pressure)
It was expressed as Also, the melt index
216Kg at 190℃ based on ASTM・D・1238・57T
Expressed in MI measured by load. Furthermore, the flow rate ratio (hereinafter abbreviated as FR), which is a measure of molecular weight distribution, is a value that indicates the dependence of solution viscosity on shear stress, and is a value specified by ASTM.
According to D・1238・57T, it is expressed as the ratio of melt index measured at shear stress of 10 ⁶ dyne/cm ² and 10 ⁵ dyne/cm ² , and the larger the FR, the broader the molecular weight distribution, and the smaller the molecular weight distribution. If so, it is considered narrow.
Further, the density ρ of the polymer was measured by the JIS K6760 density gradient tube method, and the bulk density ρB was measured by JIS K6721. Production example (a) Production of MgCl ₂ 1.5THF Using a Soxhlet extractor, 10 g of commercially available bulk anhydrous MgCl ₂ was extracted under reflux with 250 ml of dehydrated and deoxygenated tetrahydrofuran (hereinafter abbreviated as "THF") under a nitrogen gas atmosphere. I went there. about 20
After some time, almost no MgCl ₂ solids were visible. This extract was concentrated to about 100 ml, allowed to cool to room temperature, and then dried under a stream of dry nitrogen gas to obtain a white powder solid. The chemical analysis values (weight %) of the obtained solid were as follows.

[Table] (B) Production of TiCl ₄ 2THF 300 ml of dehumidified and deoxidized n-hexane and 60 mmol of TiCl ₄ are supplied to a four-necked flask under a nitrogen gas atmosphere. Place the flask in a water bath and bring the internal temperature to 0.
When 180 mmol of THF is added dropwise while stirring while maintaining the temperature at ~5°C, a yellow precipitate is formed. Stirring was continued for about 30 minutes, and the solid powder formed was thoroughly washed repeatedly with purified n-hexane. This was dried under reduced pressure at room temperature to obtain a yellow powder. The analytical values (weight %) are as follows.

[Table] (c) Production of TiCl _3.3THF Using a Soxhlet extractor, 6 g of TiCl ₃ (TiCl ₄ reduced with hydrogen) in a nitrogen gas atmosphere.
was extracted under reflux with 300 ml of dehydrated and deoxygenated THF. After about 10 hours, most of the TiCl ₃ has dissolved.
The THF phase became a deep purple-brown color. Blue solid crystals were precipitated by cooling this for a day and night, washed with purified n-hexane, and dried at room temperature under a stream of dry nitrogen gas to obtain a sky blue solid powder. This is done using purified THF.
Analysis value of solid obtained by multiple recrystallization (wt%)
shows. Ti Cl Analytical value 13.1 28.6 Calculated value 13.0 28.7 (as TiCl _3.3THF ) Example 1 _24.3 mmol of MgCl 2.1.5THF synthesized in Production Example (a) is charged into a flask that has been purged with nitrogen.
Next, add 52 ml of dehumidified and deoxygenated THF.
Dissolve _MgCl2・1.5THF. Next, separately, a manufacturing example
Charge _12.2 mmol of TiCl 4.2THF synthesized in (b).
Next, add 75 ml of dehumidified and deoxidized THF and add TiCl ₄ .
Dissolve 2THF. Next, both of the above solutions are mixed and reacted at 60° C. for 1 hour, then allowed to cool to room temperature, and 510 ml of purified normal hexane is added dropwise at room temperature over 20 minutes with stirring to form a yellow precipitate. The obtained precipitate was thoroughly washed with purified normal hexane to obtain a normal hexane slurry. [Mg+
Ti] concentration was 0.1 mol/n-hexane. The chemical analysis values (weight %) of the obtained precipitate were as follows. Mg Ti Cl 6.40 3.95 30.1 The composition formula calculated assuming that the balance is THF corresponds to Mg _3.2 TiCl _10.3 (THF) ₁₀ . To this n-hexane slurry, 62 mmol of diethylaluminum chloride was added dropwise over 20 minutes while stirring at room temperature. The mixture was then stirred at 60°C for 1 hour. The obtained precipitate was thoroughly washed with purified normal hexane to obtain a normal hexane slurry of the solid catalyst component. Next, 5 mg of the above solid catalyst component and purified mixed butane were placed in a 2-autoclave that had been purged with nitrogen in advance.
Pour 750ml and raise the temperature to 80℃. Hydrogen after heating
Introduced 0.8Kg/ ^cm2 , triethylaluminum 0.08
mmol and 28 g of 1-butene are introduced together with ethylene to initiate polymerization. As the polymerization progresses, absorption of ethylene is observed, but additional ethylene is introduced so that the total pressure becomes 14.5 Kg/cm ² . After 1 hour, ethanol was introduced under pressure to stop the polymerization. The results obtained are shown in Table-1. Example 2 22.1 mmol of MgCl ₂ .1.5THF synthesized in Production Example (a) is charged into a flask that has been purged with nitrogen.
Next, inject 47ml of dehumidified and deoxygenated THF.
The MgCl ₂ 1.5THF powder dissolves immediately to form a colorless homogeneous solution. Similarly, in another flask, synthesized in Production Example (b)
Charge _11.1 mmol of TiCl 4.2THF. Then dehumidify,
When 68ml of deoxygenated THF is injected, it becomes a yellow homogeneous solution. Next, both of the above solutions were mixed and reacted at 60°C for 1 hour, and then heated to room temperature using purified n-hexane 460°C.
ml dropwise over 20 minutes with stirring, a yellow precipitate forms. The obtained precipitate is thoroughly washed with purified normal hexane, and then the normal hexane is removed under a nitrogen stream. The chemical analysis values (weight %) of the obtained precipitate were almost the same as in Example 1. Thereafter, 300 ml of purified benzene is added to form a benzene slurry, and 56 mmol of ethylene aluminum dichloride is added over 15 minutes at 0°C to 5°C while stirring. The mixture was then stirred at the same temperature for 1 hour, and a brownish white precipitate was obtained. This precipitate was thoroughly washed with purified benzene and further washed with purified normal hexane to obtain 241 g of a solid catalyst component in the form of a brownish white powder. The remaining amount of THF in the solid catalyst component is the molar ratio of THF to the sum of magnesium atoms and titanium atoms.
(Mg+Ti)=0.53. Next, nitrogen was replaced with 2
5 mg of the above solid catalyst component and 750 ml of purified mixed butane were charged into an autoclave, and the temperature was raised to 80°C.
After raising the temperature, 1.0 kg/cm ² of hydrogen was introduced, and 0.08 mmol of triethylaluminum and 16 g of 1-butene were introduced together with ethylene to start polymerization. As the polymerization progresses, absorption of ethylene is observed, but additional ethylene is introduced so that the total pressure becomes 14.5 Kg/cm ² . After 1 hour, ethanol was introduced under pressure to stop the polymerization. The results obtained are shown in Table-1. Example 3 13.5 mmol of MgCl ₂ .1.5THF synthesized in Production Example (a) is charged into a flask that has been purged with nitrogen.
Next, inject 35ml of dehumidified and deoxygenated THF.
The MgCl ₂ 1.5THF powder dissolves immediately to form a colorless homogeneous solution. Similarly, prepare an example in another flask.
Charge _1.33 mmol of TiCl 3.2THF synthesized in (c).
Next, 30 ml of dehumidified and deoxidized THF is injected to form a purple-brown homogeneous solution. Next, both of the above solutions are mixed and reacted at 60°C for 1 hour. Purified Norman hexane at room temperature after reaction
When 260 ml was slowly added dropwise over 20 minutes with stirring, a pale sky blue precipitate was formed. The obtained precipitate was thoroughly washed with purified normal hexane to obtain a normal hexane slurry. The [Mg+Ti] concentration in the slurry at this time was 0.1 ml/NHX. The chemical analysis values (weight %) of the obtained precipitate were as follows. Mg Ti Cl 10.1 2.0 33.9 The balance was calculated as THF. The composition formula is approximately
Compatible with Mg ₁₀ TiCl ₂₃・(THF) ₁₈ . 25.0 ml of diethylaluminum chloride was added dropwise to this n-hexane slurry at room temperature while stirring, and the mixture was reacted at 65°C for 1 hour. After cooling, the mixture was thoroughly washed with n-hexane to obtain 2.21 g of solid catalyst component. The remaining amount of THF in the solid catalyst component is
The molar ratio of THF to the sum of magnesium atoms and titanium atoms was THF/(Mg+Ti)=0.76. Polymerization was carried out under exactly the same polymerization conditions as in Example 1 using the hydrocarbon-insoluble solid catalyst component produced above. The results obtained are shown in Table-1. Example 4 600 ml of purified mixed butane was charged into two autoclaves that had been purged with nitrogen in advance. Next, Example 3
Hydrocarbon-insoluble solid catalyst component 11 produced in
After charging 0.8 kg of hydrogen, the temperature was raised to 80℃ and 0.8 kg of hydrogen was charged.
Introducing cm ² . Then triethyl aluminum 0.175
mmol and 1.70 g of hexene were introduced together with ethylene, and the total pressure was set to 13.5 Kg/cm ² to initiate polymerization. Ethylene absorption is observed as the polymerization progresses, but the total pressure
Additional ethylene was introduced to bring the amount to 13.5Kg/cm ² .
After 1 hour, ethanol was introduced under pressure to stop the polymerization.
The results obtained are shown in Table-1. Example 5 Anhydrous in a flask purged with nitrogen in advance
Charge 13.5 mmol of MgCl ₂ . Next, 35 ml of dehumidified and deoxidized ethyl acetate is added to dissolve MgCl ₂ to form a colorless homogeneous solution. Similarly in another flask
TiCl ₃ (TiCl ₄ reduced with hydrogen) 1.33 mmol
and then dissolve it in 30 ml of dehumidified and deoxidized ethyl acetate. Next, the above two solutions are mixed and reacted at 60°C for 1 hour. 260ml of purified Norman hexane at room temperature after reaction
was slowly added dropwise over 20 minutes with stirring, and a pale sky blue precipitate was formed. The obtained precipitate was thoroughly washed with purified normal hexane to obtain a normal hexane slurry. [Mg+
Ti] concentration is 0.1 mol/NHX. Chemical analysis values (wt%) of the obtained precipitate were Mg 8.0%, Ti 1.57
%, Cl26.30%. The compositional formula calculated assuming that the remainder was ethyl acetate approximately corresponded to Mg ₁₀ TiCl ₂₃ (ethyl acetate) ₂₂ . To this n-hexane slurry, 33 mmol of diethylaluminum monochloride was added dropwise with stirring at room temperature, and the mixture was reacted at 65° C. for 1 hour. After cooling, the mixture was thoroughly washed with n-hexane to obtain 23 g of solid catalyst component. Using the solid catalyst component produced above,
Polymerization was carried out under exactly the same polymerization conditions as in Example 4.
The results obtained are shown in Table-1.

【table】

[Table] Comparative example _4.1 g of TiCl 3.3THF produced in production example (c) and 130 ml of purified THF in a 4-necked flask under purified nitrogen.
Add and dissolve while stirring. To this was added 7.3 g of MgCl ₂ .1.5THF produced in Production Example (a), and the mixture was stirred and dissolved at 60°C for 2 hours. After cooling to room temperature, 500 ml of dehydrated and deoxygenated purified normal hexane was added dropwise. The precipitate was separated by decantation, further washed with purified normal hexane, and then dried to obtain a catalyst powder. The chemical analysis values (weight %) of this powder were as follows. Mg Ti Cl 9.5 5.0 41 The composition formula calculated assuming that the balance is THF corresponds to Mg _3.7 TiCl _11.1 ·(THF) _5.9 . When polymerization was carried out under exactly the same polymerization conditions as in Example 4 using the catalyst powder produced above, the polymerization activity was K=2710, KTi=9.02×10 ⁴ ,
MI=0.25g/10min, FR=20, ρ=0.925g/ ^cm3 ,
A copolymer with ρB=0.21 g/cm ³ was obtained.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing one embodiment of the present invention.

Claims (1)

[Claims] 1 General formula MglTiX ¹ _2l X ² _n (OR ¹ ) _o ·(D) _p [Formula Among them, X ¹ and X ² represent a halogen atom, R ¹ represents an alkyl group, aryl group or cycloalkyl group, and D represents an electron donor compound selected from ether, carboxylic acid ester, alcohol and amine. l represents a number in the range of 0.1 to 100. m represents a number in the range of 2 to 4, n represents a number in the range of 0 to 1, and m+n is a number that corresponds to the valence of titanium. p is a number ranging from 2 to 200. ] and ^a solid complex represented by the general formula AlR ² _q X ³ _3-q [wherein R ² represents an alkyl group, aryl group or cycloalkyl group,
q represents a number in the range of 1 to 3. A catalyst system comprising a hydrocarbon-insoluble solid catalyst separated from a reaction mixture obtained by reacting with an organoaluminum compound represented by ] and a cocatalyst organoaluminum compound is used. A method for producing an ethylene-α-olefin copolymer having an ethylene-α-olefin copolymer of 0.935 g/cc or less. 2. The production method according to claim 1, wherein the hydrocarbon-insoluble solid catalyst is washed with an inert hydrocarbon solvent.