JPH0260907A - Production of conjugated diene polymer - Google Patents

Abstract

PURPOSE:To obtain a conjugated diene polymer having a high content of 1,4-trans bonding by polymerizing a monomer corresponding to a produced conjugated diene (co)polymer. CONSTITUTION:For producing a polymer of a conjugated diene compd., a copolymer consisting of a conjugated diene compd. and another conjugated diene compd. or a copolymer consisting of a conjugated diene compd. and a vinyl arom. compd., the corresponding monomers are soln.-or bulk-polymerized in the presence of a composite catalyst consisting of a salt of a lanthanoid element of an org. acid (a), an organolithium compd. (b) and an organometallic compd. (c) of the group IIIB element of the periodic table. The polymn. activity largely depends on the amt. of the salt of the lanthanoid element of the org. acid of said component (a). If more than the necessary amt. of the salt is used, it causes decreases in stability of the polymer and other characteristics, so that it is not pref. The amt. of loading is usually 0.005-10mmol per 100g of the monomer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a conjugated diene polymer having a high 1,4-trans bond ratio using a novel catalyst.

[Prior Art] The following two types of techniques are conventionally known as methods for producing conjugated diene polymers using polymerization catalysts containing lanthanoid element compounds.

That is, (i) a method for producing a conjugated diene polymer using a composite catalyst comprising a lanthanoid element compound, an organoaluminum compound, and a halogen compound; and (2) a method for producing a conjugated diene polymer using a composite catalyst comprising a lanthanide element compound and an organomagnesium compound. This is a method for producing polymers.

Among these, an example of a technique belonging to category (i) is the technique described in Japanese Unexamined Patent Publication No. 12189/1989. In this technology, carboxylates of lanthanide elements,
By solution polymerizing conjugated dienes using a composite catalyst consisting of an organoaluminum and a Lewis base such as diethylaluminum chloride, a conjugated diene polymer having a high 1,4-cis bond content has been obtained.

An example of classification technology (2) is JP-A-59-150.
The technique described in Publication No. 8 can be mentioned. This technology involves solution polymerization of conjugated dienes using a composite catalyst consisting of salts or complexes of lanthanide elements, especially praseodymium and neodymium, and organomagnesium.
Conjugated diene polymers with various structures have been obtained, such as polymers with a high 4-trans bond rate and polymers with a high 1,4 to cis bond rate.

[Problems to be Solved by the Present Invention] In order to obtain a conjugated diene polymer with a high 1,4-trans bond ratio, which is the object of the present invention, the technique of category (2) is preferable. In this type of technology, the use of organomagnesiums, especially dialkylmagnesiums, is essential;
At present, dialkylmagnesium is extremely expensive to produce, and it has been desired to replace it with a more general-purpose organic metal. In addition, in the production of this type of conjugated diene polymer using organomagnesium, due to the strong associative properties and valence of magnesium, the solution viscosity during polymerization becomes extremely high, making it difficult to stir, transfer, and remove the heat of polymerization. There are difficulties in
Improvement was desired from this aspect as well.

[Means and effects 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. In producing the compound, organic magnesium is not included as a catalyst component, and (a) an organic acid salt of a lanthanoid element, (b) an organic compound of lithium, and (c) an organic metal from the Mendeleev periodic table ■A element. The present invention provides a method for producing a conjugated diene polymer, which is characterized by carrying out solution polymerization or bulk polymerization of the corresponding monomer in the presence of a composite catalyst consisting of the compound.

The essential component (a) of the composite catalyst of the present invention is an organic acid salt of a lanthanide element. What is a lanthanoid element? Atomic number is 57
It contains 15 elements ranging from lanthanum with atomic number 71 to lutetium with atomic number 71. Among these, elements of the cerium group, ie, elements from lanthanum with atomic number 57 to samarium with atomic number 62, are particularly preferred, and the most preferred element is lanthanum. Further, the organic acid compound used is represented by the following general formula (I) to (■).

R'-LH・・・・・・・・・(I) ・・・・・・・・・(II) ・・・・・・・・・(V) (Hereafter the margin) P-OH / R8- 0(cHCH20)III ・・・・・・・・・ (VI) ＼ P-OH・・・・・・・・・ (■) R12/ (Here, R1, R2 and R5-R8 are aliphatic hydrocarbons group or an aromatic hydrocarbon group, R3 represents an aromatic hydrocarbon group, R4 represents an aliphatic hydrocarbon group, and R
9-R12 represents an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an alkoxy group or a phenoxy group. L represents an oxygen atom or a sulfur atom. Furthermore, j, to, I
I and m represent integers from 1 to 6. ) The above general formula (I) represents alcohol, thioalcohol, phenol or thiophenol.

Examples of these include methyl alcohol, ethyl alcohol, n-propyl alcohol, 1so-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-tert-butylphenol, 2,6-tert
-butyl-4-methylphenol, 2,4.6-)-tert-butylphenol, 4-phenylphenol, ethanethiol, 1-butanethiol, 2-pentanethiol, 2-1so-butanethiol, thiophenol, 2-naphthalenethiol , cyclohexanethiol,
Examples include 3-methylcyclohexanethiol, 2-naphthalenethiol, benzenemethanethiol, 2-naphthalenemethanethiol, and the like.

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, and versatic acid. , (CIO sold by Shell Chemical)
synthetic acids consisting of a mixture of isomers of monocarboxylic acids), phenylacetic acid, benzoic acid, 2-naphthoic acid, hexanethiolic acid, 2,2-dimethylbutanethionic acid, decanethionic acid, tetradecanethionic acid, thio Examples include benzoic acid.

General formula (III) represents alkylarylsulfonic acid. Examples include dodecylbenzenesulfonic acid, tetradecylbenzenesulfonic acid, hexadecylbenzenesulfonic acid, octadecylbenzenesulfonic acid, dibutylnaphthalenesulfonic acid, n-hexylnaphthalenesulfonic acid, dibutylphenylsulfonic acid, and the like.

The general formula (■) represents a monoalcohol ester of sulfuric acid. Examples of these include sulfuric monoester of lauryl alcohol, sulfuric monoester of oleyl alcohol, sulfuric monoester of stearyl alcohol, and the like.

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

General formula (Vl) represents a phosphorous acid diester of an ethylene oxide adduct of alcohol or phenol. Examples of these include phosphite diester of ethylene oxide adduct of dodecyl alcohol, phosphite diester of ethylene oxide adduct of stearyl alcohol,
Examples include phosphite diester of ethylene oxide adduct of stearyl alcohol, phosphite diester of ethylene oxide adduct of nonylphenol, and phosphite diester of ethylene oxide adduct of dodecylphenol.

The general formula (■) represents a pentavalent organic phosphoric acid compound. Examples include dibutyl phosphate, dipentyl phosphate, dihexyl phosphate, diheptyl phosphate, dioctyl phosphate, bis(i-methylheptyl) phosphate, bis(2-ethylhexyl) phosphate, dilauryl phosphate, and dioleyl phosphate. , diphenyl phosphate, bis(p-nonylphenyl) phosphate, (butyl) phosphate, (2-ethylhexyl), (i-methylheptyl) phosphate (2-ethylhexyl), (2-ethylhexyl) phosphate (p -nonylphenyl),
Monobutyl 2-ethylhexylphosphonate, mono-2-ethylhexyl 2-ethylhexylphosphonate, mono-2-ethylhexyl phenylphosphonate, mono-p-nonylphenyl 2-ethylhexylphosphonate, dibutylphosphinic acid, bis (2-ethylhexyl)phosphinic acid, bis(l-methylheptyl)phosphinic acid, dilaurylphosphinic acid, dioleylphosphinic acid, diphenylphosphinic acid, bis(p-nonylphenyl)phosphinic acid, butyl(2-ethylhexyl)phosphinic acid ,(
2-ethylhexyl)(i-methylheptyl)phosphinic acid, (2-ethylhexyl)(p-nonylphenyl)
Examples include phosphinic acid.

The general formula (■) represents a trivalent phosphoric acid compound.

Examples include bis(2-ethylhexyl) phosphate, bis(i-methylheptyl) phosphate, mono-2-ethylhexyl 2-ethylhexylphosphonate, and bis(2-ethylhexyl)phosphinic acid.

Among these, particularly preferred organic acid compounds are organic phosphoric acid compounds represented by general formulas (■) to (■).

The polymerization activity of the composite catalyst of the present invention is significantly dependent on the amount of the organic acid salt of the lanthanoid element, which is the main component (a). That is, if the amount of the organic acid salt of a lanthanoid element used is increased, the polymerization activity thereof usually increases significantly. However, using more than the necessary amount increases the amount of ash remaining in the resulting polymer, which is undesirable as it causes a decrease in stability and various properties of the polymer. The amount used is generally 0.005 per 100 g of monomer.
The range is from mmol to 10 mmol, preferably from 0.05 mmol to 5 mmol, particularly preferably from 0.1 mmol to 2 mmol.

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
) to (XIV).

R13 (Li) ・・・・・・・・・
...(IX)R'(OLi)...
・・・・・・・・・(X)\shi1 (=, knee cR13, R14, R15, R16, R17
, R18 and R19 represent an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and n, o, p and q represent an integer of 1 or more and 6 or less. ) Examples of general formula (IX) include methyllithium, ethyllithium, n-propyllithium, isopropyllithium, n-butyllithium, 5eC-butyllithium, t
ert-butyllithium, isoamyllithium, 5ec
-Amyllithium-n-hexyllithium, n-octyllithium, allyllithium, benzyllithium, phenyllithium, 1,1-diphenyllithium, tetramethylene dilithium, pentamethylene dilithium, 1,2
- dilithio 1.1,2.2-tetraphenylethane,
1,3-bis(ilithio-1,3-dimethylpentyl)
Examples include benzene, etc.

Examples of general formula (X) include ethyl alcohol, n-propyl alcohol, 1so-propyl alcohol, n-butyl alcohol, 1so-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-tert-butylphenol, 2.4
．． Examples include lithium salts of alcohols and phenols such as 6-tert-butylphenol, nonylphenol, and 4-phenylphenol.

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, and triethylene glycol monobutyl ether. and 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 general formula (Xm) include lithium salts of secondary amines such as dimethylamine, diethylamine, di-n-propylamine, di-1so-propylamine, di-n-butylamine, and di-n-hexylamine.

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

A particularly preferred organic compound of lithium is represented by the general formula (IX)
It is an organic lithium compound represented by the formula, and more preferably an alkyllithium compound such as n-butyllithium, See-butyllithium, and 1so-amyllithium.

In the composite catalyst of the present invention, it is possible to change the molecular weight and bonding mode of the conjugated diene polymer obtained by changing the amount of the lithium organic compound coexisting. Generally, as the amount of the organic lithium compound used increases, the polymerization activity increases, but on the other hand, the molecular weight and 1,4-bond content of the resulting conjugated diene polymer decrease. Therefore, the amount of lithium organic compound to be used varies depending on the desired polymer structure, but generally it is 0 per 100 g of monomer.
．． 0.05 mmol to 20 mmol, preferably 0.05 mmol to 20 mmol. L
The range is from mmol to 10 mmol, particularly preferably from 0.5 mmol to 10 mmol.

Another essential component (c) of the composite catalyst of the present invention is an organometallic compound of elements IIIB of Mendeleev's periodic table. The organometallic compound of element IIIB that can be used is represented by the following general formula (XV).

MR2°R21R22・・・・・・・・・・・・(XV
) (Here, M represents a IIIB metal, specifically boron, aluminum, gallium, indium or thallium. R20 and R21 represent hydrogen, a halogen atom, an aliphatic hydrocarbon group or an aromatic hydrocarbon group, R22 represents an aliphatic hydrocarbon group or an aromatic hydrocarbon group.

Preferred examples include trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, trihexylaluminum, tricyclohexylaluminum, diethylaluminum hydride, diisobutylaluminum hydride, ethylaluminum sibide, isobutylaluminum sibide, diethylaluminum chloride, Examples include ethylaluminum sesquichloride, ethylaluminum dichloride, diethylaluminum bromide, ethylaluminum sesquibromide, and ethylaluminum tribromide. Particularly preferred are triethylaluminum, triisobutylaluminum, diethylaluminum hydride, diisobutylaluminum hydride, and ethylaluminum sesquichloride.

In the composite catalyst of the present invention, the polymerization activity usually depends on the amount of organic aluminum coexisting, and the molecular weight of the resulting polymer depends inversely. However, its excessive usage
Decrease polymerization activity.

Therefore, the amount of organoaluminum to be used varies depending on the molecular weight and structure of the target polymer, but generally it is 0.01 mmol to 50 mmol, preferably 0.1 mmol to 10 mmol, per 100 g of monomer. , particularly preferably in the range from 0.5 mmol to 10 mmol.

Although the structure and range of usage of each component of the composite catalyst are described above, in order to effectively exhibit the performance of the composite catalyst of the present invention, it is preferable to further specify its composition. That is, the preferred composition ratio of component (b) to component (a) of the composite catalyst is (b)/(a) = 0.
It ranges from 1 to 30, particularly preferably from 1 to 10. The preferred composition ratio of component (c) to component (a) is (c)/
(a) = 0.5-50, particularly preferably 1-10.

The composite catalyst of the present invention further contains the above-mentioned essential component (a) for the purpose of increasing the polymerization activity of the composite catalyst.

In addition to (b) and (c), (i
) Aprotic polar organic compounds, (II) Protic polar organic compounds, (lii) Protic polar organic compounds and salts of Mendeleev's periodic table IA and ■A, (i■) organic Solvent-soluble C (i, Br or ■
Inorganic compounds containing the elements or C (i, Br or ■
It is also possible to coexist an organic compound containing the element.

Aprotic polar organic compounds include ether compounds,
These are thioether compounds and tertiary amine compounds.

Protic polar organic substances include alcohol compounds, thioalcohol compounds, phenolic compounds, thiophenol compounds, carboxylic acid compounds, organic sulfonic acid compounds, alcohol sulfuric acid monoester compounds, and organic phosphoric acid compounds. be.

Protic polar organic compounds and Mendeleev's periodic table IA and salts of elements The various protic polar compounds listed above and IA gold metals lithium, sodium, potassium, rubidium cesium and ■A It is a salt with an element selected from magnesium, calcium, strontium, and barium in gold metal.

Examples of inorganic compounds containing CΩ, Br, or ■ elements that are soluble in organic solvents include salts of these halogen compounds with silicon, germanium, tin, aluminum chloride, boron, and the like.

Organic compounds containing CΩ, Br or I elements (in the formula
is CΩ, Br or l, and R23R24R25 is selected from H, CΩ, Br, I, an alkyl group, an aryl group, a vinyl group, an alkoxy group, a halogenated alkyl group and a halogenated aryl group. ) Components (a) and (b) constituting the composite catalyst of the present invention
.

Naturally, (c) or even (d) may be a mixture of two or more compounds selected from the group constituting its components, or may contain a small amount of impurities.

In the composite catalyst of the present invention, prior to polymerization, its catalyst components (
2 or 3 of a), (b), and (c)
It is possible to pre-react by adding a component, optionally further component (c). This makes it possible to increase the polymerization activity of the composite catalyst and 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 will be insufficient, while if the temperature exceeds 100°C, the molecular weight distribution will expand, which is undesirable. A particularly preferable temperature is 20 to 80
It is ℃. Further, the reaction time is preferably 0.01 to 24 hours. If the reaction time is shorter than this, the preliminary reaction is insufficient, and a longer reaction time is unnecessary. Particularly preferred conditions are 0.05 to 5 hours. Further, it is also possible to make a conjugated diene monomer exist when performing this preliminary reaction, and in that case, the obtained conjugated diene polymer will have an even narrower molecular weight distribution. The preferred amount of conjugated diene monomer to be used, expressed as a molar ratio to lanthanum metal atoms, is from 1 to 1000. Whether it is less than or more than this, the effect due to the presence of the conjugated diene monomer is small. Furthermore, if a conjugated diene monomer exists in a molar ratio higher than that shown above, it becomes difficult to control the temperature in the preliminary reaction because the conjugated diene monomer may rapidly polymerize. A particularly preferred molar ratio is 5-200. The monomers used in the present invention are
It is selected from the group consisting of a conjugated diene monomer, 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 conjugated dienes preferably used include 1.3-
Butadiene, isoprene, 2,3-dimethyl-1,3-
Examples include butadiene, 1,3-pentadiene, 2,4-hexadiene, 2-phenyl-1,3-butadiene, and the like. Preferred examples of aromatic vinyl hydrocarbons include styrene, α-methylstyrene, vinyltoluene, methoxystyrene, divinylbenzene, and 1-vinylnaphthalene.

The most preferred practical polymerization form 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
Preferred are aliphatic or alicyclic hydrocarbons such as pentane, n-hexane, n-hebutane, and cyclohekiline, and aromatic hydrocarbons such as benzene and toluene. These may be a mixture of two or more types, or may contain a small amount of impurities.

In addition, the polymerization temperature is -30 to 150°C, preferably 10 to 1
Performed at 20°C. Furthermore, the polymerization reaction format may be either a batch method or a continuous method.

In addition, after polymerization, 7-ion coupling agents such as ester compounds, polyvalent epoxy compounds, polyvalent halogenated hydrocarbon compounds, polyvalent silicon halide compounds, and polyvalent tin halide compounds, or polyfunctional monomers such as divinylbenzene are added. If necessary, it is also possible to impart a branched structure to the polymer chain or to expand the molecular weight distribution by adding it to the polymerization system during or after completion of the polymerization.

After the polymerization reaction reaches a predetermined polymerization rate, a publicly available polymerization terminator is added to the reaction system to stop the reaction, and the usual steps of solvent removal and drying in the production of conjugated diene polymers can be carried out.

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

The applications of the polymers obtained by the process of the invention are wide based on their polymer structure and properties.

For example, if the polymer has a high molecular weight, a slightly low 1,4-trans bond, and is rubber-like, it can be used as a rubber-like polymer for tire treads, carcass, sidewalls, etc., and has good wear resistance and heat generation properties. It shows excellent properties such as If the polymer has a high molecular weight, has a high 1.4-trans bond ratio of 80% or more, and is crystalline, it can be used as a resin material for golf ball skins, hygiene materials, etc., and if the polymer has a relatively low molecular weight. If it is crystalline, it can be used as a processability improver for NBR, chloroprene rubber, etc., and as a hot melt adhesive.

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

Examples 1 to 8 A sufficiently dried 700ml pressure-resistant glass bottle was capped,
The interior was further purged with dry nitrogen for 3 hours. 60g of I
, after sealing 300 g of hexane mixture containing S-butadiene in a bottle, a rare earth metal organophosphate compound, Ln(P,)3 [where Ln represents a lanthanide metal, Pl 0.4 mmol of aluminum, 2.0 mmol of butyllithium, and 1.0 mmol of 1-ethylaluminum were added, and polymerization was carried out at 60° C. for 24 hours. After polymerization, methanol is added to stop the reaction, and the polymer is precipitated with methanol between the columns.
After separation, it was vacuum dried at 50°C.

The conversion rate of the polymer obtained in this way, and the
The structure and molecular weight are shown in Table 1.

(The following is a blank space) Example 9, 1° The same procedure as in Examples 1 to 8 was carried out except that the lanthanum salt of the organic acid listed in the table was used as the organic acid salt of the lanthanoid element. The results are shown in Table 2.

(Left space below) Example 11.12 One experiment was carried out in the same manner as in Example 1, except that the compound listed in the table was used as the organic compound of lithium. The results are shown in Table 3.

(Left below) Example 13.14 Example 1 except that the organic aluminum listed in the table was used as the organometallic compound of element IIIB of Mendeleev's periodic table.
It was carried out in the same way. The results are shown in Table 4.

(The following is a blank space) Examples 15 to 18 As a composite catalyst component, 1 % of the component (d) listed in the table was added.
．． The same procedure as in Example 1 was carried out except that 0 mmol was added. The results are shown in Table 5.

(Leaving space below) Examples 19 to 24 The same procedure as in Example 1 was carried out except that lanthanum organic phosphoric acid compound, butyl lithium, and triethyl aluminum were added in the amounts listed in the table per 100 g of 1,3-butadiene as composite catalyst components. . The results are shown in Table 6.

(The following is a blank space) 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 shown in the table. The results are shown in Table 7.

(Left below) Example 25 Monomer components: 45g of 1,3-butadiene and 15g
The same procedure as in Example 1 was conducted except that isoprene was used. The results are shown in Table 8.

(Left below) Example 26 Molimer component: 45g of 1,3-butadiene and 15g
The same procedure as in Example 1 was conducted except that styrene was used. The results are shown in Table 9.

(Margin below)

Claims (1)

[Claims] 1. In producing a polymer 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, the following A method for producing a conjugated diene polymer, which comprises carrying out solution polymerization or bulk polymerization of corresponding monomers in the presence of a composite catalyst consisting of components (a), (b), and (c) shown below. (a) Organic acid salt of lanthanide element (b) Organic compound of lithium (c) Organometallic compound of element III_B of Mendeleev's periodic table 2, composite catalyst of components (a), (b) and (c) other,
Furthermore, (
2. The method for producing a conjugated diene polymer according to claim 1, which comprises at least one component d). (d); (i) Aprotic polar organic compounds (ii) Protic polar organic compounds (iii) Protic polar organic compounds and salts of elements I_A and II_A of the Mendeleev periodic table (iv) 3. The method for producing a conjugated diene polymer according to claim 1 or 2, wherein the inorganic compound or organic compound 3 containing Cl, Br or I elements soluble in an organic solvent and the lanthanoid element are cerium group metals. 4. The method for producing a conjugated diene polymer according to claim 1 or 2, wherein the lanthanoid element is lanthanum.