JPH0786123B2 - Method for producing conjugated diene polymers - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a conjugated diene polymer having a high 1,4-trans bond content using a novel catalyst.

[Prior Art] The following two techniques are conventionally known as a method for producing a conjugated diene polymer using a polymerization catalyst containing a lanthanoid element compound as a component.

That is, (1) a method for producing a conjugated diene polymer using a composite catalyst composed of a lanthanoid element compound, an organoaluminum compound and a halogen compound, and (2) a conjugated diene using a composite catalyst composed of a lanthanoid element compound and an organomagnesium compound. It is a method for producing a polymer.

Among these, examples of the technique belonging to the category (1) include the technique described in JP-A-55-12189.
This technology uses a complex catalyst consisting of a lanthanide element carboxylate salt, an organoaluminum, and a Lewis base such as diethylaluminum chloride, and by carrying out solution polymerization of the conjugated dienes, the conjugated dienes having a high 1,4-cis bond content are obtained. Obtaining a polymer.

As an example of the classification technique (2), the technique described in JP-A-59-1508 can be mentioned. In this technique, a complex catalyst consisting of a salt or complex of lanthanoid elements, particularly praseodymium and neodymium, and organomagnesium is used, and a polymer having a high 1,4-trans bond content or 1,4 trans bond content is obtained by solution polymerization of conjugated dienes. -Conjugated diene polymers having various structures such as polymers having a high cis bond content have been obtained.

[Problems to be Solved by the Present Invention] In order to obtain a conjugated diene polymer having a high 1,4-trans bond content, which is the object of the present invention, the technique of classification (2) is preferable. In this kind of technology, organomagnesium,
In particular, the use of dialkylmagnesium is indispensable, but at present, it has been desired to substitute dialkylmagnesium with a more general-purpose organic metal because of its extremely high production cost. Further, in the production of this type of conjugated diene polymer using organomagnesium, the strong association property and valence of magnesium cause the solution viscosity at the time of polymerization to be extremely high, and stirring, transfer and heat removal of the heat of polymerization, etc. However, there is a need for improvement in this respect as well.

[Means and Actions for Solving the Problems] The present invention provides a homopolymer of a conjugated diene compound, a copolymer of a conjugated diene compound and another conjugated diene compound, or a copolymer of a conjugated diene compound and a vinyl aromatic compound. When a polymer is produced, it does not include organomagnesium as a catalyst component, and includes (a) an organic acid salt of a lanthanoid element, (b) an organic compound of lithium, and (c) Mendeleev's periodic table III _A organometallic compound of an element. The present invention provides a method for producing a conjugated diene polymer, which comprises subjecting the corresponding monomer to solution polymerization or bulk polymerization in the presence of the composite catalyst.

The essential component (a) of the composite catalyst of the present invention is an organic acid salt of a lanthanoid element. Lanthanoid elements include 15 elements from lanthanum with atomic number 57 to lutetium with atomic number 71. Among these, particularly, elements of the cerium group, that is, elements from lanthanum having an atomic number of 57 to samarium having an atomic number of 62 are preferable, and most preferable element is lanthanum. The organic acid compound used is represented by the following general formulas (I) to (VIII).

R ¹ -LH (I) (Here, R ¹ , R ² and R ^{5 to} R ⁸ represent an aliphatic hydrocarbon group or an aromatic hydrocarbon group, R ³ represents an aromatic hydrocarbon group, and R ⁴ represents an aliphatic hydrocarbon group. , R ^{9 to} R ¹² represent an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an alkoxy group or a phenoxy group, L represents an oxygen atom or a sulfur atom, and j, k, l and m are 1 or more and 6 or more. The following integers are represented.) The above general formula (I) represents alcohol, thioalcohol, phenol or thiophenol. Examples of these are methyl alcohol, ethyl alcohol, n-propyl alcohol, iso-propyl alcohol, tert-butyl alcohol, tert-amyl alcohol, n-hexyl alcohol, cyclohexyl alcohol, allyl alcohol, 2-butenyl alcohol, 3- Hexenyl alcohol, 2,5-decadienyl alcohol, benzyl alcohol, phenol, catechol, 1-naphthol, 2-
Naphthol, 2,6-di-tert-butylphenol, 2,6-
Di-tert-butyl-4-methylphenol, 2,4,6-tri-tert-butylphenol, 4-phenylphenol, ethanethiol, 1-butanethiol, 2-pentanethiol, 2-iso-butanethiol, thiophenol , 2-naphthalenethiol, cyclohexanethiol, 3-methylcyclohexanethiol, 2-naphthalenethiol, benzenemethanethiol, 2-naphthalenemethanethiol and the like.

The general formula (II) represents a carboxylic acid or a sulfur congener.
Examples of these are isovaleric acid, caprylic acid, octanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, cyclopentanecarboxylic acid, naphthenic acid, ethylhexanoic acid, pivalic acid,
Versatic acid, (synthetic acid composed of a mixture of isomers of C10 monocarboxylic acid sold by Shell Chemistry), phenylacetic acid, benzoic acid, 2-naphthoic acid, hexanethiolic acid, 2,2-dimethylbutanethione Acid, decanothioic acid, tetradecanothioic acid, thiobenzoic acid and the like can be mentioned.

The general formula (III) represents alkylallyl sulfonic acid.
Examples thereof include dodecylbenzenesulfonic acid, tetradecylbenzenesulfonic acid, hexadecylbenzenesulfonic acid, octadecylbenzenesulfonic acid, dibutylnaphthalenesulfonic acid, n-hexylnaphthalenesulfonic acid and dibutylphenylsulfonic acid.

The general formula (IV) represents a monoalcohol ester of sulfuric acid. Examples of these are sulfuric acid monoester of lauryl alcohol, sulfuric acid monoester of oleyl alcohol,
Examples thereof include sulfuric acid monoesters of stearyl alcohol.

The general formula (V) represents a phosphoric acid diester of an ethylene oxide adduct of alcohol or phenol. Examples of these are phosphoric acid diesters of ethylene oxide adducts of dodecyl alcohol, phosphoric acid diesters of ethylene oxide adducts of octyl alcohol, phosphoric acid diesters of ethylene oxide adducts of stearyl alcohol, phosphoric acid diesters of ethylene oxide adducts of oleyl alcohol. Examples thereof include acid diesters, nonylphenol ethylene oxide adduct phosphoric acid esters, and dodecylphenol ethylene oxide adduct phosphoric acid esters.

The general formula (VI) represents a phosphite diester of an ethylene oxide adduct of alcohol or phenol. Examples thereof include phosphite diesters of dodecyl alcohol ethylene oxide adducts, phosphite diesters of stearyl alcohol ethylene oxide adducts, phosphite diesters of stearyl alcohol ethylene oxide adducts, nonylphenol ethylene oxide additions. Examples thereof include phosphite diesters of products, and phosphite diesters of ethylene oxide adducts of dodecylphenol.

The general formula (VII) represents a pentavalent organic phosphoric acid compound. Examples of this include dibutyl phosphate, dipentyl phosphate, dihexyl phosphate, diheptyl phosphate, dioctyl phosphate,
Bis (1-methylheptyl) phosphate, Bis (2-phosphate)
Ethylhexyl), dilauryl phosphate, dioleyl phosphate, diphenyl phosphate, bis (p-nonylphenyl) phosphate, (butyl) phosphate, (2-ethylhexyl), (1-methylheptyl) phosphate (2-ethylhexyl) ,
Phosphoric acid (2-ethylhexyl) (p-nonylphenyl), 2-ethylhexyl phosphonate monobutyl, 2-
Ethylhexylphosphonate mono-2-ethylhexyl,
Phenylphosphonate mono-2-ethylhexyl, 2-ethylhexylphosphonate mono-p-nonylphenyl, dibutylphosphinic acid, bis (2-ethylhexyl) phosphinic acid, bis (1-methylheptyl) phosphinic acid,
Dilaurylphosphinic acid, dioleylphosphinic acid, diphenylphosphinic acid, bis (p-nonylphenyl) phosphinic acid, butyl (2-ethylhexyl) phosphinic acid, (2-ethylhexyl) (1-methylheptyl) phosphinic acid, (2- Examples include ethylhexyl) (p-nonylphenyl) phosphinic acid and the like.

Formula (VIII) represents a trivalent phosphate compound. Examples thereof include bis (2-ethylhexyl) phosphate, bis (1-methylheptyl) phosphate, mono-2-ethylhexyl 2-ethylhexylphosphonate, and bis (2-ethylhexyl) phosphinic acid.

Of these, particularly preferred organic acid compounds are those of general formula (VII)
To (VIII) are organic phosphoric acid compounds.

The polymerization activity of the composite catalyst of the present invention remarkably depends on the amount of the organic acid salt of the lanthanoid element of the essential component (a) which is the main component. That is, when the amount of the organic acid salt of the lanthanoid element used is increased, the usual polymerization activity is significantly increased. However, the use of more than the required amount increases the amount of ash remaining in the obtained polymer, which is not preferable because it causes deterioration of stability and various properties of the polymer. The amount used is generally in the range of 0.005 mmol to 10 mmol, preferably 0.05 mmol to 5 mmol, particularly preferably 0.1 mmol to 2 mmol per 100 g of the monomer.

The essential component (b) of the composite catalyst of the present invention is an organic compound of lithium. The organic compound of lithium has the following general formula (IX)
~ (XIV).

R ¹³ (Li) _n …… (IX) R ¹⁴ (OLi) _o …… (X) R ¹⁵ (OCH ₂ CH ₂ ) _p OLi …… (XI) (Here, R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ , R ¹⁷ , R ¹⁸ and R ¹⁹ represent an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and n, o, p and q are 1 or more and 6 or less. Represents an integer of). Examples of general formula (IX) include methyllithium, ethyllithium, n-propyllithium, isopropyllithium,
n-butyllithium, sec-butyllithium, tert-butyllithium, isoamyllithium, sec-amyllithium-n-hexyllithium, n-octyllithium,
Allyl lithium, benzyl lithium, phenyl lithium, 1,1-diphenyl lithium, tetramethylene dilithium, pentamethylene dilithium, 1,2-dilithio-1,
1,2,2-tetraphenylethane, 1,3-bis (1-lithio-1,3-dimethylpentyl) benzene and the like can be mentioned.

Examples of general formula (X) include ethyl alcohol, n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, iso-butyl alcohol, 2-butyl alcohol, tert-butyl alcohol, n-amyl alcohol, n-hexyl. Alcohol, n-heptyl alcohol, n-octyl alcohol, cyclohexyl alcohol, allyl alcohol, cyclopentyl alcohol, benzyl alcohol, phenol, 1-naphthol, 2,6
-Di-tert-butylphenol, 2,4,6-tri-tert-
Examples thereof include alcohols such as butylphenol, nonylphenol, and 4-phenylphenol, and lithium salts of phenol.

Examples of general formula (XI) include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monopropyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether. , Lithium salts such as diethylene glycol monophenyl ether.

Examples of general formula (XII) include lithium salts such as dimethylaminoethanol, diethylaminoethanol and di-n-propylaminoethanol.

Examples of the general formula (XIII) include lithium salts of secondary amines such as dimethylamine, diethylamine, di-n-propylamine, di-iso-propylamine, di-n-butylamine and di-n-hexylamine. To be

Examples of the general formula (XIV) include lithium salts of cyclic imines such as ethyleneimine, triethyleneimine, pyrrolidine, piperidine, and hexamethyleneimine.

A particularly preferable organic compound of lithium is an organic lithium compound represented by the general formula (IX), and more preferably n-butyllithium, sec-butyllithium and iso-.
It is an alkyl lithium compound such as amyl lithium.

In the composite catalyst of the present invention, it is possible to change the molecular weight and the binding mode of the obtained conjugated diene polymer, depending on the amount of the organic compound of lithium coexisting. Generally, the polymerization activity increases as the amount of the lithium organic compound used increases, while the molecular weight and 1,4-bond content of the obtained conjugated diene polymer decrease. Therefore, although the amount of the organic compound of lithium to be used varies depending on the desired polymer structure, it is generally 0.05 mmol to 20 mmol, preferably 0.1 mmol to 10 mmol per 100 g of the monomer.
It is in the range of 0.5 mmol, particularly preferably 0.5 mmol to 10 mmol.

Now one of the essential components of the composite catalyst of the present invention (c) is an organic metal compound of the Periodic Table III _B elements Mendeleev.
The following general formula is an organic metal compound III _B element can be used (X
V).

MR ²⁰ R ²¹ R ²² ...... (XV) (where M represents III _B metal, specifically boron, aluminum, gallium, indium or thallium. R ²⁰ and R ²¹ represent hydrogen, halogen atom, fat Represents a group hydrocarbon group or an aromatic hydrocarbon group, and R ²² represents an aliphatic hydrocarbon group or an aromatic hydrocarbon group.

Preferred examples thereof include trimethyl aluminum, triethyl aluminum, triisopropyl aluminum, triisobutyl aluminum, trihexyl aluminum, tricyclohexyl aluminum, diethyl aluminum hydride, diisobutyl aluminum hydride, ethyl aluminum dihydride, isobutyl aluminum dihydride, diethyl aluminum chloride, Examples thereof include sesquiethyl aluminum chloride, ethyl aluminum dichloride, diethyl aluminum bromide, sesquiethyl aluminum bromide, and ethyl aluminum dibromide. Particularly preferred are triethyl aluminum, triisobutyl aluminum, diethyl aluminum hydride, diisobutyl aluminum hydride and sesquiethyl aluminum chloride.

In the composite catalyst of the present invention, the polymerization activity usually depends on the amount of organoaluminum to be coexisted, and the molecular weight of the resulting polymer depends inversely. However, the amount used too much is
Decrease polymerization activity. Therefore, the amount of organoaluminum to be used varies depending on the structure such as the molecular weight of the intended polymer, but generally 0.01 mmol to 100 mmol per 100 g of the monomer.
It is in the range of 50 mmol, preferably 0.1 mmol to 10 mmol, particularly preferably 0.5 mmol to 10 mmol.

The structures of the components of the composite catalyst and the ranges of the amounts used are described above, but in order to effectively exhibit the performance of the composite catalyst of the present invention, it is preferable to further specify the composition thereof. That is, the preferable composition ratio of the component (b) to the component (a) of the composite catalyst is (b) / (a) = 0.1 to 3
The range is 0, particularly preferably 1 to 10. A preferable composition ratio of the component (c) to the component (a) is (c) / (a) =
The range is 0.5 to 50, particularly preferably 1 to 10.

The composite catalyst of the present invention has the above-mentioned essential components (a), (b), for the purpose of further increasing the polymerization activity of the composite catalyst.
In addition to (c), as component (d), (i) aprotic polar organic compound, (ii) protic polar organic compound, (iii) protic polar organic compound and Mendeleev's Periodic Table I _A It is also possible to coexist a salt of the II _A element, (iv) an inorganic compound containing a Cl, Br or I element soluble in an organic solvent or an organic compound containing a Cl, Br or I element.

Aprotic polar organic compounds are ether compounds,
Thioether compounds and tertiary amine compounds.

Protic polar organic compounds include alcohol compounds, thioalcohol compounds, phenol compounds, thiophenol compounds, carboxylic acid compounds, organic sulfonic acid compounds, sulfuric acid monoester compounds of alcohols, and organic phosphoric acid compounds. is there.

Protic polar organic compounds and Mendeleev's periodic table
And various protic polar compounds such listed above with a salt of I _A and II _A elements, lithium is I _A metals, sodium,
It is a salt with an element selected from magnesium, calcium, strontium and barium among potassium, rubidium cesium and II _A metal.

Examples of inorganic compounds containing Cl, Br or I element soluble in an organic solvent include these halogen compounds and silicon,
Examples thereof include salts with germanium, tin, aluminum chloride, boron and the like.

The organic compound containing Cl, Br or I element is represented by the following general formula.

(In the formula, X is Cl, Br or I, and R ²³ , R ²⁴ and R ²⁵ are H, C
It is selected from l, Br, I, alkyl groups, aryl groups, vinyl groups, alkoxy groups, halogenated alkyl groups and halogenated aryl groups. ) Components (a), (b), which constitute the composite catalyst of the present invention,
Of course, (c) or further (d) may be a mixture of two or more kinds of compounds selected from the group constituting the component, or may contain a small amount of impurities.

In the composite catalyst of the present invention, two or three components out of the catalyst components (a), (b) and (c) may be present in the presence or absence of a conjugated diene monomer prior to polymerization, in the case of Thus, the component (c) can be further added to carry out a preliminary reaction. This makes it possible to increase the polymerization activity of the composite catalyst and to narrow the molecular weight of the resulting conjugated diene polymer.

This preliminary reaction is preferably carried out at a reaction temperature of 0 to 100 ° C. If the temperature is lower than this, the preliminary reaction is insufficient. On the other hand, if the temperature exceeds 100 ° C., the molecular weight distribution is widened, which is not preferable. A particularly preferred temperature is 20-80 ° C. The reaction time is preferably 0.01 to 24 hours. If the reaction time is shorter than this, the preliminary reaction is insufficient, and the reaction time longer than this is unnecessary. Particularly preferable conditions are 0.05 to 5 hours. It is also possible to allow a conjugated diene monomer to be present when carrying out this preliminary reaction,
In that case, the obtained conjugated diene polymer has a narrower molecular weight distribution. The preferred amount of conjugated diene monomer to be used is shown in molar ratio to lanthanum metal atom,
It is 1 to 1000. Below or above this,
The effect of the presence of the conjugated diene monomer is small. Moreover, when the conjugated diene monomer is present in the above molar ratio or more, it becomes difficult to control the temperature in the preliminary reaction due to rapid polymerization of the conjugated diene monomer. A particularly preferred molar ratio is 5 to 200. The monomer used in the present invention is a conjugated diene monomer,
It is selected from the group consisting of a mixture of a conjugated diene monomer and another conjugated diene, or a mixture of a conjugated diene and an aromatic vinyl hydrocarbon. Examples of preferably used conjugated dienes include 1,3-butadiene, isoprene and 2,3-dimethyl-
1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene, 2-phenyl-1,3-butadiene and the like can be mentioned. Preferred examples of aromatic vinyl hydrocarbons include styrene, α-methylstyrene, vinyltoluene, methoxystyrene, divinylbenzene, 1-vinylnaphthalene and the like. The most preferred practical polymerization mode of the present invention is butadiene homopolymerization, isoprene homopolymerization, butadiene-isoprene copolymerization, or butadiene-styrene copolymerization.

The polymerization in the present invention can be carried out without a solvent or in the presence of a solvent. In the latter case, the solvent used is preferably an aliphatic or alicyclic hydrocarbon such as n-pentane, n-hexane, n-heptane or cyclohexane, or an aromatic hydrocarbon such as benzene or toluene. These may be a mixture of two or more kinds, or may contain a small amount of impurities. The polymerization temperature is -30 to 150 ° C, preferably 10
Performed at ~ 120 ° C. Further, the polymerization reaction system may be either a batch method or a continuous method.

After polymerization, anion coupling agents such as ester compounds, polyvalent epoxy compounds, polyvalent halogenated hydrocarbon compounds, polyvalent silicon halide compounds, and polyvalent tin compounds, or polyfunctional monomers such as divinylbenzene may be used during the polymerization. Alternatively, it is also possible to add a branched structure to the polymer chain or expand the molecular weight distribution by a method such as adding to the polymerization system after the completion.

After the polymerization reaction reaches a predetermined polymerization rate, a known polymerization terminator may be added to the reaction system to stop the polymerization, and the usual steps of solvent removal and drying in the production of the conjugated diene polymer may be performed.

[Advantages of the Invention] The present invention uses the above-mentioned novel composite catalyst composed of a general-purpose organometallic compound to produce a conjugated diene polymer having a high 1,4-trans bond content as a bonding mode at a low solution viscosity and a high solution viscosity. It provides a method of gaining activity. In the production method of the present invention, the conjugated diene polymer obtained by the catalyst composition
The ratio of cis to trans bonds in the 1,4-bond can be widely varied. Furthermore, it is also possible to adjust the molecular weight of the polymer obtained by increasing or decreasing the amount of catalyst used.

The applications of the polymers obtained by the process of the present invention are widespread due to their polymer structure and properties. For example, when the polymer has a high molecular weight and a slightly low 1,4-trans bond and is rubber-like, it can be used as a rubber-like polymer for tire treads, carcasses, sidewalls, etc., and has wear resistance and heat generation property. Etc. show excellent properties. When the polymer has a high molecular weight and a high 1,4-trans bond content of 80% or more and is crystalline, it can be used as a resin material for golf ball skins, sanitary materials, etc., and the polymer has a relatively low molecular weight. And if it is crystalline, NBR, chloroprene rubber, etc. processability improver,
It can be used as a hot melt adhesive.

[Examples] Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

Examples 1 to 8 A sufficiently dried 700 ml pressure-resistant glass bottle was capped, and the inside was purged with dry nitrogen for 3 hours. A 300 g n-hexane mixed solution containing 60 g of 1,3-butadiene was sealed in a bottle, and an organic phosphate compound of a rare earth metal, Ln (P ₁ ) ₃ per 100 g of 1,3-butadiene, where Ln is a lanthanoid metal , And P ₁ is 0.4 mmol, butyllithium, 2.0 mmol and 1.0 mmol triethylaluminum were added, and polymerization was carried out at 60 ° C. for 24 hours. After the polymerization, methanol was added to stop the reaction, and the polymer was precipitated and separated with a large amount of methanol, and then vacuum dried at 50 ° C. The conversion, and the microstructure and molecular weight of the polymer thus obtained are shown in Table 1.

Examples 9 and 10 The same operations as in Examples 1 to 8 were carried out except that the lanthanum salt of the organic acid shown in the table was used as the organic acid salt of the lanthanoid element. The results are shown in Table 2.

Examples 11 and 12 The procedure of Example 1 was repeated, except that the compounds listed in the table were used as the organic compounds of lithium. The results are shown in Table 3.

Examples 13 and 14 Mendeleev's periodic table III It carried out like Example 1 except using the organoaluminum shown in the table as an organometallic compound of _B element. The results are shown in Table 4.

Examples 15 to 18 As the composite catalyst component, the component (d) described in the table was further added to 1.
The same procedure as in Example 1 was carried out except that 0 mmol was added. The results are shown in Table 5.

Examples 19 to 24 Examples 19 to 24 were carried out in the same manner as in Example 1 except that lanthanum-containing organic phosphoric acid compounds, butyllithium and triethylaluminum were added per 100 g of 1,3-butadiene as the composite catalyst component. The results are shown in Table 6.

Comparative Examples 1 to 6 The same procedure as in Example 1 was carried out except that some of the essential components of the composite catalyst were omitted as described in the table. The results are shown in Table 7.

Example 25 The procedure of Example 1 was repeated, except that the monomer components were 45 g of 1,3-butadiene and 15 g of isoprene. 8th result
Shown in the table.

Example 26 Example 1 was repeated except that the mollymer component was 45 g of 1,3-butadiene and 15 g of styrene. The results are shown in Table 9.

[Brief description of drawings]

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

Claims (4)

[Claims] 1. When producing a polymer of a conjugated diene compound or a copolymer of a conjugated diene compound and another conjugated diene compound or a copolymer of a conjugated diene compound and a vinyl aromatic compound, the following (a) ), (B) and (c) in the presence of a composite catalyst, the corresponding monomer is solution-polymerized or bulk-polymerized to produce a conjugated diene polymer. (A) Organic acid salt of lanthanoid element (b) Organic compound of lithium (c) Mendeleev's Periodic Table III Organometallic compound of element _B 2. The composite catalyst contains, in addition to the components (a), (b) and (c), at least one component (d) selected from the group consisting of (i) to (iv) shown below. The method for producing a conjugated diene polymer according to claim 1, which is characterized in that. (D); (i) aprotic polar organic compound selected from ether compounds, thioether compounds and tertiary amine compounds (ii) alcohol compounds, thioalcohol compounds, phenol compounds, thiophenol compounds, Protic polar organic compounds selected from carboxylic acid compounds, organic sulfonic acid compounds, sulfuric acid monoester compounds of alcohols, and organic phosphoric acid compounds (iii) Various protic polar compounds mentioned in (ii) above, lithium is I _a metals, sodium, potassium, rubidium, cesium and II magnesium of _a metals, calcium, strontium, polar organic compound protic selected from a salt of an element selected from barium and Mendeleev periodic table I soluble Cl _a or salt II _a elements (iv) an organic solvent, Br if Inorganic compounds are shown below containing I element or an organic compound Cl, Br or compounds and silicon, germanium, tin, an organic compound represented by the inorganic compound of the general formula selected from salts with aluminum chloride, boron, etc. I (In the formula, X is Cl, Br or I, and R ²³ , R ²⁴ and R ²⁵ are H, C
It is selected from l, Br, I, alkyl groups, aryl groups, vinyl groups, alkoxy groups, halogenated alkyl groups and halogenated aryl groups. ) 3. The method for producing a conjugated diene polymer according to claim 1 or 2, wherein the lanthanoid element is a cerium group metal. 4. The method for producing a conjugated diene polymer according to claim 1 or 2, wherein the lanthanoid element is lanthanum.