JP2010209273A - Method of producing conjugated diene polymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel method of producing a conjugated diene polymer having a high vinyl content. <P>SOLUTION: This method of producing the conjugated diene polymer includes polymerizing a conjugated diene using, as a polymerization initiator, an organic metal compound represented by formula [I]: ter-BuR<SP>1</SP><SB>3</SB>ZnM<SP>1</SP><SB>2</SB>[I] or formula [II] ter-BuR<SP>2</SP><SB>3</SB>ZnM<SP>2</SP>(wherein ter-Bu is a tert-butyl group; R<SP>1</SP>and R<SP>2</SP>are each a substituent selected from substituent groups consisting of an alkyl group which may be substituted and an aryl group which may be substituted; Zn is a zinc atom; M<SP>1</SP>is an alkali metal; and M<SP>2</SP>is an alkaline earth metal) in the presence of a compound represented by formula [III]: R<SP>3</SP><SB>2</SB>NR<SP>4</SP>NR<SP>5</SP><SB>2</SB>and/or [IV]: R<SP>6</SP>OR<SP>7</SP>OR<SP>8</SP>(wherein R<SP>3</SP>, R<SP>5</SP>, R<SP>6</SP>, and R<SP>8</SP>are each a substituent selected from substituent groups consisting of an alkyl group which may be substituted and an aryl group which may be substituted; and R<SP>4</SP>and R<SP>7</SP>are each an alkylene group). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a conjugated diene polymer.

  As rubbers for automobile tire treads, conjugated diene polymer rubbers such as butadiene polymer rubber and butadiene-styrene copolymer rubber are widely used. The rubber for automobile tire tread is required to have a low rolling friction resistance and a high wet skid resistance from the viewpoint of fuel economy and safety.

  As rubbers satisfying such properties, Patent Documents 1 and 2 propose conjugated diene polymer rubbers having a high vinyl content. As a method for producing the rubbers, butyl lithium is used in the Patent Documents. A method for copolymerizing 1,3-butadiene and styrene in the presence of tetrahydrofuran using a polymerization initiator is described. Patent Document 3 describes a method of polymerizing isoprene in the presence of ethyltetrahydrofurfuryl ether using butyllithium as a polymerization initiator.

Japanese Examined Patent Publication No. 1-28802 Japanese Patent Publication No. 2-28605 JP-A-6-41212

  The problem to be solved by the present invention is to provide a novel method for producing a conjugated diene polymer having a high vinyl content.

The present invention uses an organometallic compound represented by the following general formula [I] or [II] as a polymerization initiator in the presence of a compound represented by the following general formula [III] and / or [IV]. The present invention relates to a method for producing a conjugated diene polymer for polymerizing a conjugated diene.
ter-BuR ¹ ₃ ZnM ¹ ₂ [I]
ter-BuR ² ₃ ZnM ² [II]
(In the above general formula [I] and [II], ter-Bu represents a tert- butyl group, R ¹ and R ² consists also aryl group is also substituted alkyl groups and substituted substituted Represents a substituent selected from a substituent group, and three R ¹ and three R ² may be the same or different, Zn represents a zinc atom, M ¹ represents an alkali metal, and And the two M ¹ may be the same or different, M ² represents an alkaline earth metal.)
R ³ ₂ NR ⁴ NR ⁵ ₂ [III]
R ⁶ OR ⁷ OR ⁸ [IV]
(In the above general formula [III] and ^{[IV], R 3, R} 5, R 6 and R ⁸ are selected from the substituent group consisting of which may aryl group is a substituted alkyl group and substituted also be substituted And two R ³ and two R ⁵ may be the same or different, and R ⁴ and R ⁷ each represent an alkylene group.)

  According to the present invention, a novel method for producing a conjugated diene polymer having a high vinyl content can be provided. In the present invention, when a conjugated diene and a vinyl aromatic compound are copolymerized, a copolymer having a high vinyl aromatic compound unit amount can be produced.

  In the present invention, the term “polymerization” includes not only homopolymerization but also copolymerization, and the term “polymer” includes not only homopolymers but also copolymers.

In the production method of the present invention, an organometallic compound represented by the following general formula [I] or [II] is used as a polymerization initiator.
ter-BuR ¹ ₃ ZnM ¹ ₂ [I]
ter-BuR ² ₃ ZnM ² [II]
(In the above general formula [I] and [II], ter-Bu represents a tert- butyl group, R ¹ and R ² consists also aryl group is also substituted alkyl groups and substituted substituted Represents a substituent selected from a substituent group, and three R ¹ and three R ² may be the same or different, Zn represents a zinc atom, M ¹ represents an alkali metal, and And the two M ¹ may be the same or different, M ² represents an alkaline earth metal.)

  In the general formulas [I] and [II], ter-Bu represents a tert-butyl group.

In the general formulas [I] and [II], R ¹ and R ² represent a substituent selected from a substituent group consisting of an optionally substituted alkyl group and an optionally substituted aryl group. The three R ^{1 s in} the general formula [I] may be the same or different, and the three R ^{2 s in} the general formula [II] may be the same or different. Good.

  Examples of the alkyl group include a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, neopentyl group, isopentyl group, n-hexyl group, 2-ethylhexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group N-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group and n-eicosyl group.

  The number of carbon atoms in the alkyl group is preferably 1 to 4. The alkyl group is preferably a methyl group, an ethyl group, an isopropyl group, or a tert-butyl group.

  Examples of the aryl group include phenyl group, 2-tolyl group, 3-tolyl group, 4-tolyl group, 2,3-xylyl group, 2,4-xylyl group, 2,5-xylyl group, 2,6- Xylyl group, 3,4-xylyl group, 3,5-xylyl group, 2,3,4-trimethylphenyl group, 2,3,5-trimethylphenyl group, 2,3,6-trimethylphenyl group, 2,4 , 6-trimethylphenyl group, 3,4,5-trimethylphenyl group, 2,3,4,5-tetramethylphenyl group, 2,3,4,6-tetramethylphenyl group, 2,3,5,6 -Tetramethylphenyl group, pentamethylphenyl group, ethylphenyl group, n-propylphenyl group, isopropylphenyl group, n-butylphenyl group, sec-butylphenyl group, tert-butylphenyl group, n-pen Butylphenyl group, neopentyl phenyl group, n- hexylphenyl group, n- octylphenyl group, n- decyl phenyl group, n- dodecyl phenyl group, n- tetradecyl phenyl group, a naphthyl group, and an anthracenyl group.

  The number of carbon atoms in the aryl group is preferably 6-12. The aryl group is preferably a phenyl group.

Of the three R ^{1 s in} the general formula [I], at least one R ¹ is preferably a tert-butyl group. In general formula [II] of the three R ^2, at least one R ² is preferably a tert- butyl group.

  In the general formula [I], Zn represents a zinc atom.

In the general formula [I], M ¹ represents an alkali metal, and two M ¹ may be the same or different. Examples of M ¹ include a lithium atom, a sodium atom, a potassium atom, a rubidium atom, and a cesium atom. M ¹ is preferably a lithium atom or a sodium atom.

In the general formula [II], M ² represents an alkaline earth metal. Examples of M ² include a beryllium atom, a magnesium atom, a calcium atom, a strontium atom, and a barium atom. M ² is preferably a magnesium atom.

  Examples of the organometallic compound represented by the general formula [I] include dilithium tetra-tert-butyl zincate, dilithium di-tert-butyldimethyl zincate, dilithium di-tert-butyl diethyl zincate, dilithium di-tert-butyl diisopropyl zincate, Examples thereof include dilithium di-tert-butyl diphenyl zincate, dilithium-tert-butyl trimethyl zincate, dilithium tri-tert-butyl methyl zincate, and compounds of these compounds in which lithium is sodium. The organometallic compound represented by the general formula [I] is preferably dilithium tetra-tert-butyl zincate, dilithium di-tert-butyldimethyl zincate, dilithium di-tert-butyl diethyl zincate, dilithium di-tert-butyl diisopropyl zincate. is there.

  Examples of the organometallic compound represented by the general formula [II] include magnesium tetra-tert-butyl zincate, magnesium di-tert-butyldimethyl zincate, magnesium di-tert-butyl diethyl zincate, magnesium di-tert-butyldiisopropyl. Examples include zincate and magnesium di-tert-butyldiphenyl zincate.

  Examples of the method for producing the organometallic compound represented by the general formulas [I] and [II] include a method described in JP-A No. 2004-292328. Moreover, as a manufacturing method of the organometallic compound represented by the general formula [I], a method in which an organozinc compound and an organoalkali metal compound are reacted at a molar ratio of 1: 2 in a hydrocarbon solvent or an ether compound solvent. As a method for producing the organometallic compound represented by the general formula [II], a molar ratio of an organozinc compound and an organoalkaline earth metal compound in a hydrocarbon solvent or an ether compound solvent is 1: 1. The method of making it react can be mention | raise | lifted.

  Examples of the organic zinc compound include dimethyl zinc, diethyl zinc, di-n-propyl zinc, diisopropyl zinc, di-n-butyl zinc, diisobutyl zinc, di-sec-butyl zinc, di-tert-butyl zinc, di- Examples thereof include n-pentyl zinc, dineopentyl zinc, diisopentyl zinc, di-n-hexyl zinc, di-2-ethylhexyl zinc, diphenyl zinc, ethylmethyl zinc, methylisopropyl zinc, methylphenyl zinc, and ethylisopropyl zinc. The organic zinc compound is preferably dimethyl zinc, diethyl zinc, diisopropyl zinc, or di-tert-butyl zinc.

  The organozinc compound is obtained by a known production method. For example, an organic alkali metal compound such as n-butyllithium and zinc chloride are reacted at a molar ratio of 2: 1, or an organic alkaline earth metal compound and zinc chloride are reacted at a molar ratio of 1: 1. Is obtained.

  Examples of the organic alkali metal compound include methyl lithium, ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, isobutyl lithium, sec-butyl lithium, tert-butyl lithium, n-pentyl lithium, neopentyl lithium, Mention may be made of isopentyllithium, n-hexyllithium, 2-ethylhexyllithium, phenyllithium and their corresponding sodium compounds. The organic alkali metal compound is preferably tert-butyllithium.

  Examples of the organic alkaline earth metal compound include dimethyl magnesium, diethyl magnesium, di-n-propyl magnesium, diisopropyl magnesium, di-n-butyl magnesium, diisobutyl magnesium, di-sec-butyl magnesium, and di-tert-butyl magnesium. , Di-n-pentylmagnesium, dineopentylmagnesium, diisopentylmagnesium, di-n-hexylmagnesium, di-2-ethylhexylmagnesium, diphenylmagnesium, ethylmethylmagnesium, methylisopropylmagnesium, methylphenylmagnesium, ethylisopropylmagnesium Can give. The organic alkaline earth metal compound is preferably di-n-butylmagnesium.

  In the reaction between the organic zinc compound and the organic alkali metal compound and the reaction between the organic zinc compound and the organic alkaline earth metal compound, the reaction temperature is usually 0 ° C. or lower.

  In the polymerization, after the organometallic compound represented by the general formula [I] or [II] is prepared in advance, the organometallic compound represented by the general formula [I] or [II] is supplied to the polymerization reaction tank. Also good. An organozinc compound and an organoalkali metal compound are supplied to a polymerization reaction tank, and the organozinc compound and the organoalkali metal compound are reacted in the polymerization reaction tank to obtain an organometallic compound represented by the general formula [I]. It may be prepared. The organic zinc compound and the organic alkaline earth metal compound are supplied to the polymerization reaction tank, and the reaction between the organic zinc compound and the organic alkaline earth metal compound is performed in the polymerization reaction tank. Organometallic compounds may be prepared. In addition, zinc chloride and an organic alkali metal compound are supplied to a polymerization reaction tank, the reaction between zinc chloride and the organic alkali metal compound in the polymerization reaction tank, and the reaction between the organic zinc compound generated by the reaction and the organic alkali metal compound. To prepare an organometallic compound represented by the general formula [I]. Zinc chloride and an organic alkaline earth metal compound are supplied to a polymerization reactor, and the reaction between zinc chloride and the organic alkaline earth metal compound in the polymerization reactor and the organic zinc compound and organic alkaline earth produced by the reaction are performed. An organometallic compound represented by the general formula [II] may be prepared by reacting with a metal compound.

In the production method of the present invention, the conjugated diene is polymerized in the presence of a compound represented by the following general formula [III] and / or [IV].
R ³ ₂ NR ⁴ NR ⁵ ₂ [III]
R ⁶ OR ⁷ OR ⁸ [IV]
(In the above general formulas [III] and [IV], R ³ , R ⁵ , R ⁶ and R ⁸ are selected from a substituent group consisting of an optionally substituted alkyl group and an optionally substituted aryl group. The two R ³ and the two R ⁵ may be the same or different, and R ⁴ and R ⁷ each represent an alkylene group.

In the general formulas [III] and [IV], R ³ , R ⁵ , R ⁶ and R ⁸ are a substituent selected from a substituent group consisting of an optionally substituted alkyl group and an optionally substituted aryl group. Represents a group. Two R ³ and two R ⁵ in the general formula [III] may be the same or different.

  Examples of the alkyl group include a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, neopentyl group, isopentyl group, n-hexyl group, 2-ethylhexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group N-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group and n-eicosyl group.

  The number of carbon atoms in the alkyl group is preferably 1 to 4. The alkyl group is preferably a methyl group, an ethyl group, a propyl group, or a butyl group.

  Examples of the aryl group include phenyl group, 2-tolyl group, 3-tolyl group, 4-tolyl group, 2,3-xylyl group, 2,4-xylyl group, 2,5-xylyl group, 2,6- A xylyl group, a 3,4-xylyl group, and a 3,5-xylyl group can be exemplified.

  The number of carbon atoms in the aryl group is preferably 6-12. The aryl group is preferably a phenyl group.

In the general formulas [III] and [IV], R ⁴ and R ⁷ represent an alkylene group.

  Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, and a hexamethylene group.

  The number of carbon atoms of the alkylene group is preferably 2 to 4. The alkylene group is preferably an ethylene group, a trimethylene group, or a tetramethylene group.

  Examples of the compound represented by the general formula [III] include N, N, N ′, N′-tetramethylethylenediamine and N, N, N ′, N′-tetraethylethylenediamine.

  Examples of the compound represented by the general formula [IV] include ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and ethylene glycol dibutyl ether.

  The amount of the compound represented by the general formula [III] is preferably 0.1 to 100 mol, more preferably 0.5 to 80 mol, and still more preferably 1 per 1 mol of the polymerization initiator. ~ 50 moles.

  The amount of the compound represented by the general formula [IV] is preferably 0.1 to 100 mol, more preferably 0.5 to 80 mol, still more preferably 1 per 1 mol of the polymerization initiator. ~ 50 moles.

  When the conjugated diene and the vinyl aromatic compound are copolymerized by the production method of the present invention, it is more preferable to use the compound represented by the general formula [III] from the viewpoint of high randomness of the copolymer to be synthesized. .

  In the production method of the present invention, conjugated diene is polymerized. Examples of the conjugated diene include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, and 1,3-hexadiene. These may be used alone or in combination of two or more. From the viewpoint of availability, 1,3-butadiene and 2-methyl-1,3-butadiene are preferable.

  The production method of the present invention is suitable for producing a polymer having a vinyl group content of 5 to 90% by weight, more suitable for producing a polymer having a vinyl group content of 10 to 85% by weight, It is further suitable for producing a polymer having a content of 15 to 80% by weight. Here, the content of the vinyl group is a value in which the content of the conjugated diene unit in the polymer is 100% by weight.

  In the production method of the present invention, copolymerization of a conjugated diene and another monomer may be performed. Examples of other monomers include aromatic vinyl compounds, vinyl nitriles, unsaturated carboxylic acid esters, and the like. Examples of the aromatic vinyl compound include styrene, α-methylstyrene, vinyl toluene, vinyl naphthalene, divinyl benzene, trivinyl benzene, and divinyl naphthalene. Examples of the vinyl nitrile include acrylonitrile, and examples of the unsaturated carboxylic acid ester include methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate. In these, an aromatic vinyl compound is preferable and a styrene is preferable from a viewpoint of availability.

  When copolymerizing a conjugated diene and an aromatic vinyl compound, the production method of the present invention is suitable for producing a polymer having an aromatic vinyl compound unit content of 1 to 99% by weight. Suitable for production of a polymer having a unit content of 3 to 80% by weight, and more suitable for production of a polymer having an aromatic vinyl compound unit content of 5 to 80% by weight. Is particularly suitable for the production of a polymer having a content of 20 to 40% by weight. Here, the content of the aromatic vinyl compound unit is a value in which the conjugated diene copolymer is 100% by weight.

  The solvent used in the production method of the present invention is preferably a hydrocarbon. Examples of the hydrocarbon include aliphatic hydrocarbons, aromatic hydrocarbons, and alicyclic hydrocarbons. Examples of the aliphatic hydrocarbon include propane, n-butane, isobutane, n-pentane, isopentane, and n-hexane. Examples of the aromatic hydrocarbon include benzene, toluene, xylene, and ethylbenzene. Examples of the alicyclic hydrocarbon include cyclopentane and cyclohexane. These may be used alone or in combination of two or more. Of these, hydrocarbons having 3 to 12 carbon atoms are preferred.

  The polymerization temperature in the production method of the present invention is usually -80 to 150 ° C, preferably 0 to 100 ° C.

  The polymerization time in the production method of the present invention is usually 5 minutes to 48 hours, preferably 30 minutes to 24 hours.

  After completion of the polymerization, a known recovery method, for example, (1) a method of adding a coagulant to the polymerization reaction solution, (2) a method of adding steam to the polymerization reaction solution, (3) from the polymerization reaction solution using an oven dryer The conjugated diene polymer can be recovered from the polymerization reaction solution by the method of removing the solvent. The recovered conjugated diene polymer may be dried by a known dryer such as a band dryer or an extrusion dryer.

  The conjugated diene polymer may be blended with other polymers or additives to form a polymer composition.

  Other polymers include conjugated diene polymers produced by methods other than the production method of the present invention, natural rubber, ethylene-propylene copolymers, ethylene-1-butene copolymers, ethylene-1-hexene copolymers. Examples thereof include a polymer, a propylene-1-butene copolymer, and an ethylene-propylene-1-butene copolymer. These polymers may be used in combination of two or more.

  Known additives may be used, such as sulfur vulcanizing agents; vulcanization accelerators such as thiazole vulcanization accelerators, thiuram vulcanization accelerators, sulfenamide vulcanization accelerators; Vulcanization activators such as stearic acid and zinc oxide; organic peroxides; reinforcing agents such as carbon black and silica; fillers such as calcium carbonate and talc; silane coupling agents; extension oils; processing aids; Agents: Lubricants can be exemplified.

  The conjugated diene polymer of the present invention is suitably used for tires, belts, hoses, footwear and the like.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

The polymerization reaction and evaluation of the polymer were performed by the following methods.
1. Polymerization reaction rate The weight ratio of the produced polymer to the total amount of monomers added in the polymerization reaction vessel was determined.
2. Styrene unit content Measured according to JIS K-6383 (refractive index method).
3. Vinyl group content Measured by infrared spectroscopy (Morello method). In the measurement, the absorption intensity in the vicinity of 910 cm ^−1, which is the vinyl group absorption peak, was measured with an infrared spectrophotometer.

Example 1
(Synthesis of Et ₂ tert-Bu ₂ ZnLi ₂ )
The inside of the 100 ml eggplant flask was replaced with dry nitrogen. In an eggplant flask, 20 ml of diethyl ether and 1.0 mmol of diethyl zinc were added, and then 2.0 mmol of tert-butyllithium was added at -78 ° C. The solution in the eggplant flask was stirred at 0 ° C. for 30 minutes to obtain a diethyl ether solution of Et ₂ tert-Bu ₂ ZnLi ₂ .
(Copolymerization of 1,3-butadiene / styrene)
The interior of the stainless steel polymerization reactor having an internal volume of 5 liters was washed and dried and replaced with dry nitrogen. Next, 3.75 L of hexane, 20 mL of diethyl ether, 1.04 mL of N, N, N ′, N′-tetramethylethylenediamine, 375 g of 1,3-butadiene, 125 g of styrene, 1.0 mmol of Et ₂ ^t Bu ₂ ZnLi were added, Polymerization was carried out at 65 ° C. for 3 hours under stirring. At 1 hour and 2 hours after the start of polymerization, a very small amount of the polymerization solution was extracted, the polymerization solution was dried under reduced pressure, the polymer was taken out from the polymerization solution, and the amount of polymer produced in the unit polymerization solution was determined. Further, the content of styrene units in the polymer was measured. After completion of the polymerization, the polymerization reaction solution in the polymerization reaction tank was taken out, 3 g of an antioxidant (Sumitomo Chemical Co., Ltd. GM 2 g, Sumitomo Chemical Co., Ltd., Sumitizer TP-D 1 g) was added, and most of the hexane was evaporated. The polymer was dried under reduced pressure for 12 hours at a temperature to obtain a polymer, and the physical properties of the polymer were measured. The results are shown in Table 1.

Example 2
The same procedure as in Example 1 was performed except that 1.05 mL of ethylene glycol diethyl ether was added instead of N, N, N ′, N′-tetramethylethylenediamine. Table 1 shows the measurement results of the physical properties of the polymer.

Example 3
The same procedure as in Example 1 was performed except that 1.56 mL of ethylene glycol dibutyl ether was added instead of N, N, N ′, N′-tetramethylethylenediamine. Table 1 shows the measurement results of the physical properties of the polymer.

Comparative Example 1
The same procedure as in Example 1 was performed except that N, N, N ′, N′-tetramethylethylenediamine was not added and the amount of Et ₂ ^t Bu ₂ ZnLi added was changed to 2.5 mmol. Table 1 shows the measurement results of the physical properties of the polymer.

＊）TMEDA：Ｎ，Ｎ，Ｎ’，Ｎ’−テトラメチルエチレンジアミン
DECS：エチレングリコールジエチルエーテル
EGDBE：エチレングリコールジブチルエーテル

*) TMEDA: N, N, N ′, N′-tetramethylethylenediamine
DECS: Ethylene glycol diethyl ether
EGDBE: Ethylene glycol dibutyl ether

Claims (6)

An organometallic compound represented by the following general formula [I] or [II] is used as a polymerization initiator, and a conjugated diene is formed in the presence of a compound represented by the following general formula [III] and / or [IV]. A method for producing a conjugated diene polymer to be polymerized.
ter-BuR ¹ ₃ ZnM ¹ ₂ [I]
ter-BuR ² ₃ ZnM ² [II]
(In the above general formula [I] and [II], ter-Bu represents a tert- butyl group, R ¹ and R ² consists also aryl group is also substituted alkyl groups and substituted substituted Represents a substituent selected from a substituent group, and three R ¹ and three R ² may be the same or different, Zn represents a zinc atom, M ¹ represents an alkali metal, and And the two M ¹ may be the same or different, M ² represents an alkaline earth metal.)
R ³ ₂ NR ⁴ NR ⁵ ₂ [III]
^{R 6 OR 7 OR 8 [IV} ]
(In the above general formulas [III] and [IV], R ³ , R ⁵ , R ⁶ and R ⁸ are selected from a substituent group consisting of an optionally substituted alkyl group and an optionally substituted aryl group. The two R ³ and the two R ⁵ may be the same or different, and R ⁴ and R ⁷ each represent an alkylene group. An organometallic compound represented by the following general formula [I] or [II] is used as a polymerization initiator, and in the presence of a compound represented by the following general formula [III] and / or [IV], A method for producing a conjugated diene polymer which is copolymerized with a vinyl aromatic compound.
ter-BuR ¹ ₃ ZnM ¹ ₂ [I]
ter-BuR ² ₃ ZnM ² [II]
(In the above general formula [I] and [II], ter-Bu represents a tert- butyl group, R ¹ and R ² consists also aryl group is also substituted alkyl groups and substituted substituted Represents a substituent selected from a substituent group, and three R ¹ and three R ² may be the same or different, Zn represents a zinc atom, M ¹ represents an alkali metal, and And the two M ¹ may be the same or different, M ² represents an alkaline earth metal.)
_{^{R 3 2 NR 4 NR 5 2}} [III]
R ⁶ OR ⁷ OR ⁸ [IV]
(In the above general formulas [III] and [IV], R ³ , R ⁵ , R ⁶ and R ⁸ are selected from a substituent group consisting of an optionally substituted alkyl group and an optionally substituted aryl group. And two R ³ and two R ⁵ may be the same or different, and R ⁴ and R ⁷ each represent an alkylene group.) The method for producing a conjugated diene polymer according to claim 1 or 2, wherein M ¹ is a lithium atom or a sodium atom, and M ² is a magnesium atom. R ³ , R ⁵ , R ⁶ and R ⁸ are substituents selected from a substituent group consisting of an alkyl group having 1 to 4 carbon atoms and an aryl group having 6 to 12 carbon atoms, and R ⁴ and R ⁷ are The method for producing a conjugated diene polymer according to any one of claims 1 to 3, which is an alkylene group having 2 to 4 carbon atoms.   The method for producing a conjugated diene polymer according to any one of claims 1 to 4, wherein the polymerization is carried out in a hydrocarbon solvent.   The conjugated diene-based heavy component according to any one of claims 1 to 5, wherein the conjugated diene is at least one conjugated diene selected from the conjugated diene group consisting of 1,3-butadiene and 2-methyl-1,3-butadiene. Manufacturing method of coalescence.