JP2000313710A - Catalyst composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymerization catalyst for producing a polymer containing a high content of a cis 1,4-structure in its microstructure and having a narrow molecular weight distribution. SOLUTION: This catalyst composition for polymerizing a conjugated diene comprises (A) a metallocene complex of a rare-earth metal compound (e.g. a samarium complex or the like) and (B) an ionic compound consisting of a non-coordinating anion and a cation, e.g. triphenylcarbonium tetrakis(pentafluorophenyl)borate and/or aluminoxane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a catalyst composition for conjugated diene polymerization and a co-catalyst contained in the catalyst composition. The present invention also relates to a method for producing a conjugated diene polymer using the catalyst composition and a novel conjugated diene polymer obtained by the method.

[0002]

2. Description of the Related Art Numerous proposals have been made for polymerization catalysts for conjugated dienes, and they play an extremely important role industrially. In particular, in order to obtain conjugated diene polymers with improved thermal and mechanical properties, a number of polymerization catalysts that provide a high cis 1,4 bond content have been studied.
Has been developed. For example, composite catalyst systems based on transition metal compounds such as nickel, cobalt and titanium are known, some of which are already butadiene,
It is widely used industrially as a polymerization catalyst for isoprene and the like (End. Ing. Chem., 48, 784, 1956; JP-B-37-819).
No. 8).

On the other hand, in order to achieve a higher cis 1,4 bond content and excellent polymerization activity, a rare earth metal compound and
Research on composite catalyst systems consisting of organometallic compounds of Groups III to III
It has been developed and research on high stereospecific polymerization has been actively conducted (Makromol. Chem. Suppl, 4, 61, 1981;
Polym. Sci., Polym. Chem. Ed., 18, 3345, 1980; German Patent Application 2,848,964; Sci. Sinica., 2/3, 734, 198
0; see Rubber Chem. Technol., 58, 117, 1985). Among these catalyst systems, a composite catalyst containing a neodymium compound and an organoaluminum compound as main components has a high cis-content.
It has been confirmed that it has a 1,4 bond content and excellent polymerization activity, and has already been industrialized as a polymerization catalyst for butadiene and the like (Macromolecules, 15, 230, 1982; Makromol. Che.
m., 94, 119, 1981).

[0004] With the recent advancement of industrial technology, the market demand for polymer materials has become more and more advanced,
There has been a strong demand for the development of polymer materials having even higher thermal properties (such as thermal stability) and mechanical properties (such as tensile modulus and flexural modulus). One of the powerful means to solve this problem is to use a catalyst with high polymerization activity for conjugated dienes, and to use
Attempts have been made to produce polymers having a high 1,4-structure content and a narrow molecular weight distribution. However,
Heretofore, a method for producing a polymer having such characteristics has not been known.

[0005]

An object of the present invention is to provide a catalyst for polymerizing conjugated dienes. More specifically, an object of the present invention is to provide a polymerization catalyst for producing a polymer having a high content of a cis 1,4-structure in a microstructure and a narrow molecular weight distribution. Another object of the present invention is to provide a polymer having the above characteristics and a method for producing the polymer.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a rare earth metallocene-type polymerization catalyst and an ionic catalyst composed of a non-coordinating anion and a cation. By using a catalyst composition in which a compound and / or a co-catalyst containing an aluminoxane are used, the conjugated diene can be efficiently polymerized, and by using the above-described polymerization catalyst composition,
It has been found that a conjugated diene polymer having a very high cis 1,4-structure content in the microstructure and a narrow molecular weight distribution can be produced. The present invention has been completed based on these findings.

That is, the present invention provides a catalyst composition for the polymerization of a conjugated diene, comprising: (A) a metallocene complex of a rare earth metal compound; and (B) a non-coordinating anion and a cation. And / or an aluminoxane. According to a preferred embodiment of the present invention, the catalyst composition wherein the metallocene type complex is a samarium complex; the ionic compound is triphenylcarbonium tetrakis (pentafluorophenyl) borate, triphenylcarbonium tetrakis (tetrafluorophenyl) borate, The above catalyst composition, which is N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate, 1,1′-dimethylferrocenium tetrakis (pentafluorophenyl) borate;
And, the above catalyst composition further comprising an organometallic compound of an element of Groups I to III of the periodic table is provided.

In another aspect, the present invention relates to a co-catalyst for use together with a catalyst for polymerizing a conjugated diene containing a metallocene complex of a rare earth metal compound, wherein the ionic compound comprises a non-coordinating anion and a cation. And / or a cocatalyst comprising an aluminoxane is provided by the present invention. From still another viewpoint, a method of polymerizing a conjugated diene in the presence of the above-mentioned polymerization catalyst composition; and a polymer obtainable by polymerizing a conjugated diene in the presence of the above-mentioned polymerization catalyst composition Is provided. In addition to these inventions, the content of the cis 1,4 structure in the microstructure is 80 mol% or more,
It is preferably at least 90 mol%, more preferably at least 95 mol%, particularly preferably at least 98 mol%, and the molecular weight distribution Mw / Mn is at most 2.00, preferably at most 1.80, more preferably at most 1.60, even more preferably at least 1.40. Below, a polymer having particularly preferably 1.30 or less is provided. This polymer can be produced by polymerizing a conjugated diene in the presence of the above-mentioned polymerization catalyst composition.

[0009]

The metallocene complex of the DETAILED DESCRIPTION OF THE INVENTION rare earth metal compounds, for example, the general formula _{(I): R a MX b} · L c or the general formula _{(II): R a MX b} QX b ( wherein, M Represents a rare earth metal; R represents a cyclopentadienyl group, a substituted cyclopentadienyl group, an indenyl group, a substituted indenyl group, a fluorenyl group, or a substituted fluorenyl group; X represents a hydrogen atom, a halogen atom, an alkoxide group, a thiolate L represents a Lewis basic compound; Q represents a Group III element of the periodic table; a represents an integer of 1, 2, or 3; B; 0, 1,
Or c represents an integer of 2; c represents an integer of 0, 1, or 2), and a divalent or trivalent rare earth metal compound represented by the formula:

In the general formula (I), as the rare earth metal represented by M, an element having an atomic number of 57 to 71 in the periodic table can be used. Specific examples of rare earth metals include, for example, lanthanum, cerium, praseodymium,
Neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium can be mentioned, among which samarium is preferred. When a is 2, two Rs may be the same or different. Similarly, when b or c is 2, two X or L may be the same or different.

The type, number, and position of the substituents in the substituted cyclopentadienyl group, the substituted indenyl group, and the substituted fluorenyl group are not particularly limited. Examples thereof include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. , N-butyl group, isobutyl group, sec-butyl group, tert-
In addition to a butyl group, a hexyl group, a phenyl group, a benzyl group and the like, a hydrocarbon group containing a silicon atom such as a trimethylsilyl group can be exemplified. R may be bonded to a part of X by a cross-linking group such as a dimethylsilyl group, a dimethylmethylene group, a methylphenylmethylene group, a diphenylmethylene group, an ethylene group, or a substituted ethylene group. They may be bonded by a cross-linking group such as a silyl group, a dimethylmethylene group, a methylphenylmethylene group, a diphenylmethylene group, an ethylene group, and a substituted ethylene group.

Specific examples of the substituted cyclopentadienyl group include, for example, methylcyclopentadienyl group, benzylcyclopentadienyl group, vinylcyclopentadienyl group, 2-methoxyethylcyclopentadienyl group, trimethylsilylcyclo Pentadienyl group, tert-butylcyclopentadienyl group, ethylcyclopentadienyl group, phenylcyclopentadienyl group, 1,2-dimethylcyclopentadienyl group, 1,3-dimethylcyclopentadienyl group, 1,3-di (tert-butyl) cyclopentadienyl group, 1,2,3-trimethylcyclopentadienyl group, 1,2,3,
4-tetramethylcyclopentadienyl group, pentamethylcyclopentadienyl group, 1-ethyl-2,3,4,5-tetramethylcyclopentadienyl group, 1-benzyl-2,3,4,5- Tetramethylcyclopentadienyl group, 1-phenyl-2,3,
4,5-tetramethylcyclopentadienyl group, 1-trimethylsilyl-2,3,4,5-tetramethylcyclopentadienyl group, 1-trifluoromethyl-2,3,4,5-tetramethylcyclopenta And a dienyl group. Specific examples of the substituted indenyl group include, for example, a 1,2,3-trimethylindenyl group, a heptamethylindenyl group, and a 1,2,4,5,6,7-hexamethylindenyl group. R is preferably a pentamethylcyclopentadienyl group.

The alkoxide group represented by X includes aliphatic alkoxy groups such as methoxy group, ethoxy group, propoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, phenoxy group, 2,6 -Di-tert-butylphenoxy group, 2,6-diisopropylphenoxy group,
Aryl oxide groups such as 2,6-dineopentylphenoxy group, 2-tert-butyl-6-isopropylphenoxy group, 2-tert-butyl-6-neopentylphenoxy group, and 2-isopropyl-6-neopentylphenoxy group Or a 2,6-di-tert-butylphenoxy group.

The thiolate group represented by X includes thiomethoxy, thioethoxy, thiopropoxy, thion-
Butoxy group, thioisobutoxy group, thiosec-butoxy group, aliphatic thiolate group such as thiotert-butoxy group,
Thiophenoxy group, 2,6-di-tert-butylthiophenoxy group, 2,6-diisopropylthiophenoxy group, 2,6-dineopentylthiophenoxy group, 2-tert-butyl-6-isopropylthiophenoxy group, 2-tert-butyl-6-thioneopentylphenoxy group, 2-isopropyl-6-thioneopentylphenoxy group, or any of arylthiolate groups such as 2,4,6-triisopropylthiophenoxy group,
A 2,4,6-triisopropylthiophenoxy group is preferred.

Examples of the amide group include an aliphatic amide group such as a dimethylamide group, a diethylamide group, and a diisopropylamide group, a phenylamide group, a 2,6-di-tert-butylphenylamide group, and a 2,6-diisopropylphenylamide group. ,
2,6-dineopentylphenylamide group, 2-tert-butyl-
Arylamide groups such as 6-isopropylphenylamide group, 2-tert-butyl-6-neopentylphenylamide group, 2-isopropyl-6-neopentylphenylamide group, and 2,4,6-tert-butylphenylamide group Or a 2,4,6-tert-butylphenylamide group is preferred.

The halogen atom represented by X is a fluorine atom,
Any of a chlorine atom, a bromine atom and an iodine atom may be used, but a chlorine atom and an iodine atom are preferred. 1 to 20 carbon atoms
Specific examples of the hydrocarbon group of, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group,
Isobutyl group, sec-butyl group, tert-butyl group, neopentyl group, hexyl group, linear or branched aliphatic hydrocarbon group such as octyl, phenyl group, tolyl group, aromatic hydrocarbon group such as naphthyl group, In addition to an aralkyl group such as a benzyl group, a hydrocarbon group containing a silicon atom such as a trimethylsilylmethyl group and a bistrimethylsilylmethyl group may be used. Among these, a methyl group, an ethyl group, an isobutyl group, a trimethylsilylmethyl group and the like are preferable. X is preferably a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 20 carbon atoms.

The Lewis basic compound represented by L is not particularly limited as long as it is a Lewis basic compound capable of coordinating a metal with a counter electron, and may be an inorganic compound or an organic compound. As Lewis basic compounds, for example, ether compounds, ester compounds, ketone compounds,
An amine compound, a phosphine compound, a silyloxy compound, or the like can be used, but is not limited thereto. In the general formula (II), Q represents a Group III element in the periodic table, and specific examples of the element include boron, aluminum, and gallium, with aluminum being preferred.

Specific examples of the metallocene complex of the rare earth metal compound represented by the formula (I) include, for example, bispentamethylcyclopentadienyl bistetrahydrofuransamarium, methylbispentamethylcyclopentadienyl tetrahydrofuransamarium, chlorobis Pentamethylcyclopentadienyl tetrahydrofuransamarium, or iodobispentamethylcyclopentadienyl tetrahydrofuransamarium and the like, the formula (II)
As a specific example of the metallocene complex of the rare earth metal compound represented by the following formula, for example, dimethylaluminum (μ-dimethyl) bis (pentamethylcyclopentadienyl) samarium and the like can be mentioned.

The ionic compound used as the co-catalyst is not particularly limited as long as it is composed of a non-coordinating anion and a cation. For example, the ionic compound can react with the rare earth metal compound to form a cationic transition metal compound. Ionic compounds and the like can be mentioned. Non-coordinating anions include, for example, tetra (phenyl) borate, tetrakis (monofluorophenyl) borate, tetrakis (difluorophenyl) borate, tetrakis (trifluorophenyl) borate, tetrakis (trifluorophenyl) borate, tetrakis (penta) (Fluorophenyl) borate, tetrakis (tetrafluoromethylphenyl) borate, tetra (tolyl) borate, tetra (xylyl) borate, (triphenyl, pentafluorophenyl) borate, [tris (pentafluorophenyl), phenyl] borate, trideca Hydride
And -7,8-dicarboundecaborate.

Examples of the cation include a carbonium cation, an oxonium cation, an ammonium cation, a phosphonium cation, a cycloheptatrienyl cation, and a ferrocenium cation having a transition metal. Specific examples of the carbonium cation include a trisubstituted carbonium cation such as a triphenylcarbonium cation and a trisubstituted phenylcarbonium cation. Specific examples of the tri-substituted phenylcarbonium cation include a tri (methylphenyl) carbonium cation and a tri (dimethylphenyl) carbonium cation. Specific examples of ammonium cations include trimethylammonium cation, triethylammonium cation, tripropylammonium cation, tributylammonium cation, trialkylammonium cation such as tri (n-butyl) ammonium cation, N, N-diethylanilinium cation, N And N, N-dialkylanilinium cations such as N, 2,4,6-pentamethylanilinium cation, dialkylammonium cations such as di (isopropyl) ammonium cation and dicyclohexylammonium cation. Specific examples of the phosphonium cation include triarylphosphonium cations such as triphenylphosphonium cation, tri (methylphenyl) phosphonium cation, and tri (dimethylphenyl) phosphonium cation.

As the ionic compound, a non-coordinating anion and a cation which are arbitrarily selected and combined can be preferably used. For example, ionic compounds include triphenylcarbonium tetrakis (pentafluorophenyl) borate and triphenylcarbonium tetrakis (tetrafluorophenyl)
Borates, N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate, 1,1′-dimethylferrocenium tetrakis (pentafluorophenyl) borate and the like are preferable. The ionic compounds may be used alone or in combination of two or more. As a Lewis acid capable of producing a cationic transition metal compound by reacting with a transition metal compound, B (C ₆ F ₅ ) ₃ , Al (C ₆ F ₅ ) ₃ or the like can be used, and these are the ionic compounds described above. May be used in combination.

As the aluminoxane used as the cocatalyst, for example, an aluminoxane obtained by contacting an organic aluminum compound with a condensing agent can be used. More specifically, an aluminoxane represented by the general formula (-Al (R ')) A chain aluminoxane or a cyclic aluminoxane represented by O-) _n can be used. In the above formula, R ′ is a hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group may be substituted with a halogen atom and / or an alkoxy group. n indicates the degree of polymerization, and is preferably 5 or more, more preferably 10 or more. R ′ is a methyl group, an ethyl group, a propyl group,
Examples include an isobutyl group, and a methyl group is preferred. Examples of the organoaluminum compound used as a raw material for the aluminoxane include trialkylaluminums such as trimethylaluminum, triethylaluminum, and triisobutylaluminum, and mixtures thereof. Particularly preferred is trimethylaluminum. Aluminoxane using a mixture of trimethylaluminum and tributylaluminum as a raw material can also be suitably used. Aluminoxanes may be used in combination with ionic compounds.

The catalyst composition of the present invention comprises the above components (A) and (B), and further comprises, as component (C), Periodic Tables I to III
It may contain an organometallic compound of a group element. Examples of the organic metal compound include an organic aluminum compound, an organic lithium compound, an organic magnesium compound, an organic zinc compound, an organic boron compound, and the like. More specifically, methyllithium, butyllithium, phenyllithium, benzyllithium, neopentyllithium, trimethylsilylmethyllithium, bistrimethylsilylmethyllithium, dibutylmagnesium, dihexylmagnesium, diethylzinc, dimethylzinc, trimethylaluminum, triethylaluminum, triethylaluminum Isobutyl aluminum, trihexyl aluminum, trioctyl aluminum, tridecyl aluminum, and the like can be used. Further, organic metal halides such as ethyl magnesium chloride, butyl magnesium chloride, dimethyl aluminum chloride, diethyl aluminum chloride, sesquiethyl aluminum chloride, ethyl aluminum dichloride, etc .; and hydrogenated organic metals such as diethyl aluminum hydride and sesquiethyl aluminum hydride. Compounds may be used. You may use these organometallic compounds in combination of 2 or more types.

The above component (A) in the catalyst composition of the present invention.
The proportion of (B) and (B) can be appropriately selected depending on the type of the monomer to be polymerized and the type and conditions of the reaction. Generally, in a composition containing a rare earth metal compound and an aluminoxane, the component (A): component (B) (molar ratio) is 1: 1.
11: 10000, preferably 1:10 to 1: 1000, and more preferably about 1:50 to 1: 500. In a composition containing a rare earth metal compound and an ionic compound, the components
(A): Component (B) (molar ratio) is 1: 0.1 to 1:10, preferably
The ratio may be about 1: 0.2 to 1: 5, more preferably about 1: 0.5 to 1: 2. In the catalyst composition containing the component (C), the mixing ratio (molar ratio) of the rare earth metal compound and the component (C) is, for example, 1: 0.1 to 1: 1000, and preferably 1: 0.2 to 1: 500. ,
More preferably, it is about 1: 0.5 to 1:50.

The type of the conjugated diene compound monomer that can be polymerized by the polymerization method of the present invention is not particularly limited.
Examples include 1,3-butadiene, isoprene, 1,3-pentadiene, 2-ethyl-1,3-butadiene, 2,3-dimethylbutadiene, 2-methylpentadiene, 4-methylpentadiene, and 2,4-hexadiene. Of these, 1,3-
Butadiene is preferred. These monomer components may be used alone or in combination of two or more.

The polymerization method of the present invention may be carried out in the presence or absence of a solvent. When a solvent is used, its type is not particularly limited as long as the solvent is substantially inert in the polymerization reaction and has sufficient solubility in the monomer and the catalyst composition. For example, butane,
Saturated aliphatic hydrocarbons such as pentane, hexane and heptane; saturated alicyclic hydrocarbons such as cyclopentane and cyclohexane; monoolefins such as 1-butene and 2-butene; aromatic hydrocarbons such as benzene and toluene; Methylene,
Examples thereof include halogenated hydrocarbons such as chloroform, carbon tetrachloride, trichloroethylene, perchlorethylene, 1,2-dichloroethane, chlorobenzene, bromobenzene, and chlorotoluene. Of these, toluene is preferable. Further, two or more solvents may be used in combination.

The polymerization temperature in the polymerization method of the present invention is, for example, in the range of -100 to 100 ° C, preferably in the range of -50 to 80 ° C. The polymerization time is, for example, about 1 minute to 12 hours, preferably about 5 minutes to 5 hours. However, these reaction conditions can be appropriately selected according to the type of the monomer and the type of the catalyst composition, and are not limited to the ranges exemplified above. After the polymerization reaction reaches a predetermined polymerization rate, a known polymerization terminator is added to the polymerization system to stop the polymerization, and then the produced polymer can be separated from the reaction system according to a usual method. The content of the cis structure in the microstructure of the polymer of the present invention is usually 80 mol% or more, preferably 90 mol% or more, more preferably 95 mol%.
Above, particularly preferably 98 mol% or more. Further, regarding the molecular weight distribution, Mw / Mn is 2.00 or less, preferably 1.80
Or less, more preferably 1.60 or less, still more preferably 1.
It is 40 or less, particularly preferably 1.30 or less. Since the polymer of the present invention is expected to have high thermal properties (thermal stability, etc.) and mechanical properties (tensile modulus, flexural modulus, etc.), it is used for various uses as a polymer material. It is possible.

Hereinafter, the present invention will be described more specifically with reference to Examples, but the scope of the present invention is not limited to these Examples. The microstructure of the polybutadiene in the examples is the peak [ ¹ H obtained by ¹ H NMR and ¹³ C NMR.
NMR: δ 4.8-5.0 (= CH _{2 in} 1,2-vinyl unit), 5.2-
5.8 (-CH = of 1,4-unit and -CH of 1,2-vinyl unit
=), ¹³ C NMR: δ 27.4 (1,4-cis unit), 32.7 (1,4
-Transformer unit), 127.7-131.8 (1,4-unit), 11
3.8-114.8 and 143.3-144.7 (1,2-vinyl unit)]. The weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) were determined by GPC using polystyrene as a standard substance.

Example 1 Drying well in a glove box under a nitrogen atmosphere
In a 30 ml pressure-resistant glass bottle, add bispentamethylcyclopentadienyl bistetrahydrofuransamarium [(Cp ^* )
₂ Sm (THF) ₂ ] (Cp ^* : pentamethylcyclopentadienyl ligand) was charged in an amount of 0.01 mmol, and dissolved in 6 ml of toluene. Then, MMAO (toluene-soluble aluminoxane sold by Tosoh Akzo) was added so that Al / Sm = 200 element ratio, and the bottle was stoppered. Then remove the bottle from the glove box and add 1.5 g of 1,3-butadiene
The polymerization was carried out at 50 ° C. for 5 minutes. After polymerization, 10 wt%
The reaction was stopped by adding 10 ml of methanol containing BHT [2,6-bis (tert-butyl) -4-methylphenol], and the polymer was separated with a large amount of a mixed solvent of methanol / hydrochloric acid.
And vacuum dried. The yield of the obtained polymer was 65 wt%. The microstructure of the polymer has a cis content of 98.8 mol%
The number average molecular weight was 401,000, and Mw / Mn was 1.82.

Example 2 Drying well in a glove box under a nitrogen atmosphere
In a 30 ml pressure-resistant glass bottle, add methylbispentamethylcyclopentadienyltetrahydrofuransamarium [(Cp
^* ) ₂ SmMe (THF)] was added to 0.01 mmol and dissolved in 6 ml of toluene. Then, MMAO was added so that the Al / Sm = 200 element ratio was obtained, and the bottle was stoppered. Then remove the bottle from the glove box, charge 1.5 g of 1,3-butadiene,
Polymerization was carried out at 15 ° C for 15 minutes. After the polymerization, the reaction was stopped by adding 10 ml of methanol containing 10 wt% of BHT, and the polymer was separated with a large amount of a mixed solvent of methanol / hydrochloric acid and dried at 60 ° C. in vacuo. The yield of the obtained polymer was 86 wt%. The microstructure of the polymer was found to have a cis content of 98.0 mol%, a number average molecular weight of 1,260,000 and Mw / Mn of 1.69.

Example 3 Drying well in a glove box under a nitrogen atmosphere
In a 30 ml pressure-resistant glass bottle, add bispentamethylcyclopentadienyl bistetrahydrofuransamarium [(Cp ^* )
₂ Sm (THF) ₂ ] was charged in an amount of 0.01 mmol and dissolved in 6 ml of toluene. Then, 0.1 mmol of triisobutylaluminum and 0.01 mmol of triphenylcarbonium tetrakis (pentafluorophenyl) borate (Ph ₃ CB (C ₆ F ₅ ) ₄ ) were added, and the bottle was stoppered. After that, remove the bottle from the glove box, charge 1.5 g of 1,3-butadiene, and
For 10 minutes. After the polymerization, the reaction was stopped by adding 10 ml of methanol containing 10 wt% of BHT, and the polymer was separated with a large amount of a mixed solvent of methanol / hydrochloric acid and dried at 60 ° C. under vacuum. The yield of the obtained polymer was 78 wt%. The microstructure of the polymer was found to have a cis content of 95.0 mol%, a number average molecular weight of 263,000, and Mw / Mn of 1.34.

Example 4 Drying well in a glove box under a nitrogen atmosphere
Dimethyl aluminum (μ-
Dimethyl) bis (pentamethylcyclopentadienyl)
0.01 mmol of samarium [(Cp ^* ) ₂ Sm (μ-Me) ₂ AlMe ₂ ] was charged and dissolved in 6 ml of toluene. Then, triisobutylaluminum 0.03 mmol, triphenylcarbonium tetrakis (pentafluorophenyl) borate (Ph ₃ CB (C ₆
F ₅ ) ₄ ) The bottle was stoppered by adding 0.01 mmol. afterwards,
The bottle was taken out of the glove box, 1.5 g of 1,3-butadiene was charged, and polymerization was performed at 50 ° C. for 5 minutes. After polymerization,
The reaction was stopped by adding 10 ml of methanol containing 10 wt% of BHT, and the polymer was separated with a large amount of a mixed solvent of methanol / hydrochloric acid and dried at 60 ° C. under vacuum. The yield of the obtained polymer is
It was 94 wt%. The microstructure of the polymer has a cis content of 90.0
mol%, the number average molecular weight was 429,500, and Mw / Mn was 1.56.

[0033]

By using the catalyst composition of the present invention, it is possible to produce a polymer having a very high cis 1,4-structure content in the microstructure and a narrow molecular weight distribution.

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Claims (9)

[Claims] 1. A catalyst composition for polymerizing a conjugated diene, comprising: (A) a metallocene complex of a rare earth metal compound; and (B) an ionic compound comprising a non-coordinating anion and a cation. A composition comprising a compound and / or an aluminoxane. 2. The catalyst composition according to claim 1, wherein the metallocene complex is a samarium complex. 3. The method according to claim 1, wherein the ionic compound is triphenylcarbonium tetrakis (pentafluorophenyl) borate,
3. The compound according to claim 1, wherein the compound is triphenylcarbonium tetrakis (tetrafluorophenyl) borate, N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate, or 1,1'-dimethylferrocenium tetrakis (pentafluorophenyl) borate. 3. The catalyst composition according to 1. 4. The catalyst composition according to claim 1, further comprising an organometallic compound of an element of Groups I to III of the periodic table. 5. A co-catalyst for use together with a catalyst for polymerizing a conjugated diene containing a metallocene complex of a rare earth metal compound, comprising an ionic compound comprising a non-coordinating anion and a cation and / or an aluminoxane. Promoter. 6. A method for polymerizing a conjugated diene in the presence of the catalyst composition according to claim 1. Description: 7. A polymer obtainable by polymerizing a conjugated diene in the presence of the catalyst composition according to claim 1. Description: 8. The polymer according to claim 7, wherein the content of the cis 1,4-structure in the microstructure is 80 mol% or more, and the molecular weight distribution has Mw / Mn of 2.00 or less. 9. A conjugated diene polymer having a cis 1,4-structure content of at least 80 mol% in the microstructure and a molecular weight distribution Mw / Mn of at most 2.00.