JP5604936B2 - Yttrium compound and conjugated diene polymerization catalyst using the same - Google Patents

Description

  The present invention relates to a novel yttrium compound having a bulky ligand and a conjugated diene polymerization catalyst using the same.

  Many proposals have been made on polymerization catalysts for conjugated dienes such as 1,3-butadiene and isoprene, some of which have been industrialized. For example, as a method for producing a conjugated diene polymer having a high cis-1,4 structure, a combination of a compound such as titanium, cobalt, nickel, or neodymium and organic aluminum is often used.

  Polymerization of conjugated dienes using a Group 3 element of the periodic table as a catalyst is known, and various polymerization methods have been proposed so far. For example, Japanese Patent Laid-Open No. 7-268013 (Patent Document 1) discloses a catalyst system comprising a rare earth metal salt, an organometallic compound of Group I to III elements of the periodic table, and a fluorine-containing organoboron compound. .

  JP-A-11-80222 (Patent Document 2) discloses a group IIIB metal compound of a periodic table, an ionic compound of a non-coordinating anion and a cation, and an organic metal of a group I to III element of the periodic table. A polymerization catalyst comprising a compound is disclosed.

  International Publication No. 2006/049016 (Patent Document 3) includes a yttrium compound having a bulky substituent, an ionic compound comprising a non-coordinating anion and a cation, and groups 2 and 12 of the periodic table. And a catalyst system comprising an organometallic compound of an element selected from Group 13 elements.

  Japanese Patent Application Laid-Open No. 2008-56584 (Patent Document 4) discloses an olefin or conjugated diene polymerization catalyst containing a scandium or yttrium cationic cyclopentadienyl complex. However, the activity is very low.

Japanese Patent Laid-Open No. 7-268013 Japanese Patent Laid-Open No. 11-80222 International Publication No. 2006/049016 Pamphlet JP 2008-56584 A

  The present invention provides a novel yttrium compound having a bulky ligand and a conjugated diene polymerization catalyst using the same, and particularly, a conjugated diene polymer having a high cis-1,4 structure content is produced with high efficiency. An object of the present invention is to provide a polymerization catalyst that can be used.

（但し、Ｒ^１〜Ｒ^６は炭素数１〜１２の置換基を表す。Ｏは酸素原子を表し、Ｙはイットリウム原子を表す。） The present invention is an yttrium compound having a bulky ligand represented by the following general formula (1).

(However, R < ¹ > -R < ⁶ > represents a C1-C12 substituent. O represents an oxygen atom and Y represents an yttrium atom.)

  The present invention also provides an yttrium compound (A) having the above-mentioned bulky ligand, an ionic compound (B) comprising a non-coordinating anion and a cation, groups 2, 12, and 13 in the periodic table. A process for producing a conjugated diene polymer, characterized by comprising a catalyst for conjugated diene polymerization comprising an organometallic compound (C) of an element selected from It is.

  By using the yttrium compound having a bulky ligand of the present invention, a polymerization catalyst capable of producing a conjugated diene polymer having a high cis-1,4 structure content with high activity can be provided.

（但し、Ｒ^１〜Ｒ^６は炭素数１〜１２の置換基を表す。Ｏは酸素原子を表し、Ｙはイットリウム原子を表す。） The yttrium compound of the present invention is an yttrium compound having a bulky ligand represented by the following general formula (1).

(However, R < ¹ > -R < ⁶ > represents a C1-C12 substituent. O represents an oxygen atom and Y represents an yttrium atom.)

Specific examples of the substituent having 1 to 12 carbon atoms in R ^{1 to} R ⁶ of the general formula (1) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, s-butyl group, Isobutyl group, t-butyl group, n-pentyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group, 2,2-dimethylpropyl group Group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, unsaturated hydrocarbon group such as dodecyl group, unsaturated hydrocarbon group such as vinyl group, 1-propenyl group, allyl group, cyclohexyl group, Alicyclic hydrocarbon groups such as methylcyclohexyl group and ethylcyclohexyl group, aromatic hydrocarbon groups such as phenyl group, benzyl group, toluyl group and phenethyl group And the like. Further, those in which a hydroxyl group, a carboxyl group, a carbomethoxy group, a carboethoxy group, an amide group, an amino group, an alkoxy group, a phenoxy group and the like are substituted at an arbitrary position are also included. Among them, a saturated hydrocarbon group having 1 to 12 carbon atoms is preferable, and a saturated hydrocarbon group having 1 to 6 carbon atoms is particularly preferable.

Specific examples of the yttrium compound include tris (1,3-bis (2,4,6-trimethylphenyl) propane-1,3 diionato) yttrium and tris (1,3-bis (2,4,6-triethylphenyl). ) Propane-1,3 dionato) yttrium, tris (1,3-bis (2,4,6-tri-n-propylphenyl) propane-1,3 dionato) yttrium, tris (1,3-bis (2,4) , 6-triisopropylphenyl) propane-1,3 dionato) yttrium, tris (1,3-bis (2,4,6-tri-n-butylphenyl) propane-1,3 dionato) yttrium, tris (1,3 -Bis (2,4,6-triisobutylphenyl) propane-1,3 dionato) yttrium, tris (1,3-bis (2,6-di (t-butyl)) 4-methylphenyl) propane-1,3 dionato) yttrium, tris (1,3-bis (4- (t-butyl) -2,6-dimethylphenyl) propane-1,3 dionato) yttrium, tris (1, 3-bis (2,4,6-trimethylphenyl) -2-methylpropane-1,3 dionato) yttrium, tris (3-phenyl (2,4,6-trimethylphenyl) propane-1,3 dionato) yttrium, Etc.
Among these, tris (1,3-bis (2,4,6-trimethylphenyl) propane-1,3 dionato) yttrium is preferable.

  The yttrium compound (A) having a bulky ligand is an ionic compound (B) composed of a non-coordinating anion and a cation, an element selected from Groups 2, 12, and 13 of the periodic table. By combining with the organometallic compound (C), it can be used as a conjugated diene polymerization catalyst.

  In the ionic compound comprising a non-coordinating anion and a cation as the component (B) of the catalyst system, examples of the non-coordinating anion include tetra (phenyl) borate and tetra (fluorophenyl) borane. , Tetrakis (difluorophenyl) borate, tetrakis (trifluorophenyl) borate, tetrakis (tetrafluorophenyl) borate, tetrakis (pentafluorophenyl) borate, tetrakis (3,5-bistrifluoromethyl) Phenyl) borate, tetrakis (tetrafluoromethylphenyl) borate, tetra (triyl) borate, tetra (xylyl) borate, triphenyl (pentafluorophenyl) borate, tris (pentafluorophenyl) (Phenyl) borate, tridecahydride-7,8- Cal Bowne deca borate - DOO, tetrafluoroborate - DOO, hexafluorophosphate - such DOO and the like.

  On the other hand, examples of the cation include a carbonium cation, an oxonium cation, an ammonium cation, a phosphonium cation, a cycloheptatrienyl cation, and a ferrocenium cation.

  Specific examples of the carbonium cation include tri-substituted carbonium cations such as a triphenyl carbonium cation and a tri-substituted phenyl carbonium cation. Specific examples of the tri-substituted phenylcarbonium cation include tri (methylphenyl) carbonium cation and tri (dimethylphenyl) carbonium cation.

  Specific examples of ammonium cations include trialkylammonium cations, triethylammonium cations, tripropylammonium cations, tri (n-butyl) ammonium cations, tri (i-butyl) ammonium cations, and the like, N, N-dimethyl N, N-dialkylanilinium cations such as anilinium cation, N, N-diethylanilinium cation, N, N-2,4,6-pentamethylanilinium cation, di (i-propyl) ammonium cation, dicyclohexylammonium Mention may be made of dialkylammonium cations such as cations.

  Specific examples of phosphonium cations include triphenylphosphonium cation, tetraphenylphosphonium cation, tri (methylphenyl) phosphonium cation, tetra (methylphenyl) phosphonium cation, tri (dimethylphenyl) phosphonium cation, tetra (dimethylphenyl) phosphonium cation, etc. Of arylphosphonium cations.

  As the ionic compound, those arbitrarily selected and combined from the non-coordinating anions and cations exemplified above can be preferably used.

  Among these, as ionic compounds, triphenylcarbonium tetrakis (pentafluorophenyl) borate, triphenylcarbonium tetrakis (fluorophenyl) borate, N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate. And 1,1′-dimethylferrocenium tetrakis (pentafluorophenyl) borate are preferred. An ionic compound may be used independently and may be used in combination of 2 or more type.

In addition, alumoxane may be used in place of the ionic compound composed of the non-coordinating anion and cation as component (B). The alumoxane is obtained by bringing an organoaluminum compound and a condensing agent into contact with each other, and includes a chain aluminoxane represented by the general formula (—Al (R ′) O—) n or a cyclic aluminoxane. (R ′ is a hydrocarbon group having 1 to 10 carbon atoms, including those partially substituted with a halogen atom and / or an alkoxy group. N is the degree of polymerization and is 5 or more, preferably 10 or more) . Examples of R ′ include a methyl group, an ethyl group, a propyl group, and an isobutyl group, and a methyl group is preferable. Examples of the organoaluminum compound used as an aluminoxane raw material include trialkylaluminums such as trimethylaluminum, triethylaluminum, and triisobutylaluminum, and mixtures thereof.

  Among these, alumoxane using a mixture of trimethylaluminum and tributylaluminum as a raw material can be suitably used.

  Moreover, as a condensing agent, water is typically used, but in addition to this, an arbitrary one in which the trialkylaluminum undergoes a condensation reaction, for example, adsorbed water such as an inorganic substance, a diol, and the like.

  Examples of organometallic compounds of Group 2, 12 and 13 of the periodic table that are the component (C) of the catalyst system include organic magnesium, organic zinc, and organic aluminum. Preferred among these compounds are dialkyl magnesium, alkyl magnesium chloride, alkyl magnesium bromide, dialkyl zinc, trialkyl aluminum, dialkyl aluminum chloride, dialkyl aluminum bromide, alkyl aluminum sesquichloride, alkyl aluminum sesquibromide, alkyl aluminum dichloride, Dialkylaluminum hydride and the like.

  Specific compounds include alkyl magnesium halides such as methyl magnesium chloride, ethyl magnesium chloride, butyl magnesium chloride, hexyl magnesium chloride, octyl magnesium chloride, ethyl magnesium bromide, butyl magnesium bromide, butyl magnesium iodide, and hexyl magnesium iodide. Can be mentioned.

  Furthermore, dialkyl magnesium such as dimethylmagnesium, diethylmagnesium, dibutylmagnesium, dihexylmagnesium, dioctylmagnesium, ethylbutylmagnesium, and ethylhexylmagnesium can be exemplified.

  Furthermore, dialkyl zinc, such as dimethyl zinc, diethyl zinc, diisobutyl zinc, dihexyl zinc, dioctyl zinc, and didecyl zinc, can be mentioned.

  Furthermore, trialkylaluminums such as trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum, and the like can be given.

  In addition, dialkylaluminum chlorides such as dimethylaluminum chloride and diethylaluminum chloride, organoaluminum halogen compounds such as ethylaluminum sesquichloride and ethylaluminum dichloride, and hydrogenated organoaluminum compounds such as diethylaluminum hydride, diisobutylaluminum hydride and ethylaluminum sesquihydride. Can be mentioned.

  These organometallic compounds of Groups 2, 12, and 13 of the periodic table can be used alone or in combination of two or more.

  Although the conjugated diene can be polymerized using the above-mentioned catalyst, (1) hydrogen, (2) metal hydride compound, and (3) hydrogenated organometal as the molecular weight regulator of the resulting conjugated diene polymer. A compound selected from compounds can be used.

  Examples of the molecular weight regulator (2) metal hydride compound include lithium hydride, sodium hydride, potassium hydride, magnesium hydride, calcium hydride, borane, aluminum hydride, gallium hydride, silane, germane, Examples thereof include lithium borohydride, sodium borohydride, lithium aluminum hydride, sodium aluminum hydride, and the like.

  (3) Examples of hydrogenated organometallic compounds include alkylboranes such as methylborane, ethylborane, propylborane, butylborane, and phenylborane; dialkylboranes such as dimethylborane, diethylborane, dipropylborane, dibutylborane, and diphenylborane; methyl Alkyl aluminum dihydride such as aluminum dihydride, ethylaluminum dihydride, propylaluminum dihydride, butylaluminum dihydride, phenylaluminum dihydride, dimethylaluminum hydride, diethylaluminum hydride, dipropylaluminum hydride, dibutylaluminum hydride, diphenylaluminum hydride Dialkyl aluminum high dry Silanes such as methylsilane, ethylsilane, propylsilane, butylsilane, phenylsilane, dimethylsilane, diethylsilane, dipropylsilane, dibutylsilane, diphenylsilane, trimethylsilane, triethylsilane, tripropylsilane, tributylsilane, triphenylsilane, Germanium such as methyl germane, ethyl germane, propyl germane, butyl germane, phenyl germane, dimethyl germane, diethyl germane, dipropyl germane, dibutyl germane, diphenyl germane, trimethyl germane, triethyl germane, tripropyl germane, tributyl germane, triphenyl germane And the like.

  Among these, diisobutylaluminum hydride and diethylaluminum hydride are preferable, and diethylaluminum hydride is particularly preferable.

  The order of addition of the catalyst components is not particularly limited, but can be performed, for example, in the following order.

  (1) In an inert organic solvent, the component (C) is added in the presence or absence of the conjugated diene compound monomer to be polymerized, and the components (A) and (B) are added in any order.

  (2) In the inert organic solvent, the component (C) is added in the presence or absence of the conjugated diene compound monomer to be polymerized, the molecular weight regulator is added, and then the components (A) and (B ) Add ingredients in any order.

  (3) After adding the component (A) in the presence or absence of the conjugated diene compound monomer to be polymerized in an inert organic solvent, and adding the component (C) and the molecular weight regulator described above in any order. , (B) component is added.

  (4) After adding the component (B) in the presence or absence of the conjugated diene compound monomer to be polymerized in an inert organic solvent, and adding the component (C) and the molecular weight regulator described above in any order. , (A) component is added.

  (5) After adding component (C) in the presence or absence of a conjugated diene compound monomer to be polymerized in an inert organic solvent, and adding components (A) and (B) in any order Add the above-described molecular weight regulator.

  Moreover, you may age | cure and use each component previously. Especially, it is preferable to age | cure (A) component and (C) component.

  As aging conditions, the component (A) and the component (C) are mixed in an inert solvent in the presence or absence of the conjugated diene compound monomer to be polymerized. The aging temperature is -50 to 80 ° C, preferably -10 to 50 ° C, and the aging time is 0.01 to 24 hours, preferably 0.05 to 5 hours, particularly preferably 0.1 to 1 hour.

  In the present invention, each catalyst component may be supported on an inorganic compound or an organic polymer compound.

  Conjugated diene compound monomers include 1,3-butadiene, isoprene, 1,3-pentadiene, 2-ethyl-1,3-butadiene, 2,3-dimethylbutadiene, 2-methylpentadiene, 4-methylpentadiene, 2 , 4-hexadiene and the like. Among these, a conjugated diene compound monomer mainly composed of 1,3-butadiene is preferable.

  These monomer components may be used singly or in combination of two or more.

  Here, the conjugated diene compound monomer to be polymerized may be the total amount or a part of the monomer. In the case of part of the monomer, the above contact mixture can be mixed with the remaining monomer or the remaining monomer solution. In addition to conjugated dienes, olefins such as ethylene, propylene, allene, 1-butene, 2-butene, 1,2-butadiene, pentene, cyclopentene, hexene, cyclohexene, octene, cyclooctadiene, cyclododecatriene, norbornene, norbornadiene, etc. A compound or the like may be contained.

  The polymerization method is not particularly limited, and bulk polymerization (bulk polymerization) using a conjugated diene compound monomer such as 1,3-butadiene itself as a polymerization solvent, or solution polymerization can be applied. Solvents for solution polymerization include aliphatic hydrocarbons such as butane, pentane, hexane, and heptane, alicyclic hydrocarbons such as cyclopentane and cyclohexane, aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene, Examples thereof include olefinic hydrocarbons such as olefin compounds and cis-2-butene and trans-2-butene.

  Among these, benzene, toluene, cyclohexane, or a mixture of cis-2-butene and trans-2-butene is preferably used.

  The polymerization temperature is preferably in the range of -30 to 150 ° C, particularly preferably in the range of 30 to 100 ° C. The polymerization time is preferably in the range of 1 minute to 12 hours, particularly preferably 5 minutes to 5 hours.

  After performing the polymerization for a predetermined time, the inside of the polymerization tank is released as necessary, and post-treatment such as washing and drying steps is performed.

  The conjugated diene polymer obtained in the present invention is preferably cis-1,4-polybutadiene having a cis-1,4 structure of 90% or more, more preferably 92% or more, particularly preferably 96% or more. . [Η] of the conjugated diene polymer is preferably 0.1 to 10, more preferably 1 to 7, and particularly preferably 1.5 to 5.

Examples according to the present invention will be specifically described below. The polymerization conditions and polymerization results are summarized in Table 1. Measuring methods for physical properties and the like are as follows.
1) NMR spectrum: Measured using a JNM / AL400 spectrum meter manufactured by JEOL.
2) Measurement of Y content: Measured by ICP emission spectrometry. For the measurement, Vista MPX type manufactured by Varian Japan was used.
3) Elemental analysis: The CHN coder MT-5 manufactured by Yanaco was used.
4) Microstructure: Performed by infrared absorption spectrum analysis. The microstructure was calculated from the absorption intensity ratio of cis 740 cm-1, trans 967 cm-1, and vinyl 910 cm-1.
5) Intrinsic viscosity ([η]): Measured at 30 ° C. using a toluene solution of the polymer.

(Synthesis Example 1)
To a 300 ml pear-shaped two-necked flask were added 0.91 g (3.43 mmol) of triisopropoxy yttrium manufactured by High Purity Chemical Laboratory and 40 ml of dehydrated toluene, and the mixture was stirred with a magnetic stirrer. Separately, a solution prepared by dissolving 3.24 g (10.5 mmol) of 1,3-bis (2,4,6-trimethylphenyl) -1,3-propanedione in 80 ml of dehydrated toluene was prepared, and triisopropoxy yttrium was prepared. The solution was added dropwise to a toluene solution. The reaction was carried out under reflux of toluene for 23 hours, and toluene was distilled off and dried under reduced pressure. 5 ml of dehydrated toluene was added to the obtained solid, and the mixture was heated to reflux for 1 hour. After adding 10 ml of heptane to this solution, it was cooled with dry ice and the supernatant was removed. The obtained precipitate was dried under reduced pressure to obtain tris (1,3-bis (2,4,6-trimethylphenyl) propane-1,3-dionato) yttrium. Yield 1.49 g (1.47 mmol), 43% yield.
As a result of nuclear magnetic resonance spectrum (NMR) of the product, ¹ H-NMR δ (ppm): 6.6 (12H), 5.7 (3H), 2.3 (36H), 2.1 (18H) The measurement solvent used was C ₆ D ₆ .
The Y content of the product was 8.8%, the C content was 74.7%, and the H content was 6.9%.

Example 1
The inside of the autoclave having an internal volume of 2 L was purged with nitrogen, charged with a solution consisting of 260 ml of toluene and 140 ml of butadiene, the temperature of the solution was adjusted to 30 ° C., and 0.7 ml of a toluene solution of triethylaluminum (TEA) (2 mol / L) was added. The mixture was added and stirred at 500 rpm for 3 minutes. Next, 1 ml of a toluene solution (20 mmol / L) of tris (1,3-bis (2,4,6-trimethylphenyl) propane-1,3 dionato) yttrium was added and stirred for 4 minutes. The temperature was raised and 0.1 ml of a toluene solution (0.43 mol / L) of triphenylcarbenium tetrakispentafluorophenylborate was added to initiate polymerization. After polymerization for 24 minutes at 40 ° C., 5 ml of an ethanol / heptane (1/1) solution containing an anti-aging agent was added to terminate the polymerization. After releasing the pressure inside the autoclave, the polymerization solution was put into ethanol to recover polybutadiene. The recovered polybutadiene was then vacuum dried at 80 ° C. for 3 hours. The polymerization results are shown in Table 1.

(Example 2)
Polymerization was carried out in the same manner as in Example 1 except that the amount of triethylaluminum (TEA) added was 1 ml of a toluene solution (2 mol / L). The polymerization results are shown in Table 1.

(Example 3)
Polymerization was carried out in the same manner as in Example 1 except that the amount of triethylaluminum (TEA) added was 2 ml of a toluene solution (2 mol / L) and the polymerization time was 30 minutes. The polymerization results are shown in Table 1.

Example 4
Polymerization was carried out in the same manner as in Example 3 except that the amount of triethylaluminum (TEA) added was 3 ml of a toluene solution (2 mol / L). The polymerization results are shown in Table 1.

(Example 5)
Triethylaluminum (TEA) in toluene solution (2 mol / L) 0.6 ml, Tris (1,3-bis (2,4,6-trimethylphenyl) propane-1,3 dionato) yttrium in toluene solution (20 mmol / L) Polymerization was carried out in the same manner as in Example 3 except that 0.6 ml and 0.06 ml of a toluene solution of triphenylcarbenium tetrakispentafluorophenylborate (0.43 mol / L) were added. The polymerization results are shown in Table 1.

(Example 6)
Polymerization was carried out in the same manner as in Example 5 except that the amount of triethylaluminum (TEA) added was 1.2 ml of a toluene solution (2 mol / L). The polymerization results are shown in Table 1.

(Example 7)
Polymerization was carried out in the same manner as in Example 5 except that the amount of triethylaluminum (TEA) added was 1.8 ml of a toluene solution (2 mol / L). The polymerization results are shown in Table 1.

(Example 8)
The inside of the autoclave having an internal volume of 2 L was purged with nitrogen, charged with a solution consisting of 260 ml of toluene and 140 ml of butadiene, the temperature of the solution was adjusted to 30 ° C., and 1.2 ml of a toluene solution (2 mol / L) of triethylaluminum (TEA) was added. The mixture was added and stirred at 500 rpm for 3 minutes. Next, the temperature was raised to 40 ° C., and 0.6 ml of a toluene solution (20 mmol / L) of tris (1,3-bis (2,4,6-trimethylphenyl) propane-1,3 dionato) yttrium was added. After stirring at 40 ° C. for 1 minute, 0.06 ml of a toluene solution (0.43 mol / L) of triphenylcarbenium tetrakispentafluorophenylborate was added to initiate polymerization. After polymerization at 40 ° C. for 30 minutes, 5 ml of an ethanol / heptane (1/1) solution containing an antiaging agent was added to terminate the polymerization. After releasing the pressure inside the autoclave, the polymerization solution was put into ethanol to recover polybutadiene. The recovered polybutadiene was then vacuum dried at 80 ° C. for 3 hours. The polymerization results are shown in Table 1.

Example 9
The inside of the autoclave having an internal volume of 2 L was purged with nitrogen, charged with a solution consisting of 260 ml of toluene and 140 ml of butadiene, the temperature of the solution was adjusted to 30 ° C., and then 1.2 ml of a toluene solution of triethylaluminum (TEA) (2 mol / L) was added. The mixture was added and stirred at 500 rpm for 3 minutes. Next, 0.6 ml of a toluene solution (20 mmol / L) of tris (1,3-bis (2,4,6-trimethylphenyl) propane-1,3 dionato) yttrium was added and stirred at 30 ° C. for 30 minutes. Thereafter, the temperature was raised to 40 ° C., and 0.06 ml of a toluene solution (0.43 mol / L) of triphenylcarbenium tetrakispentafluorophenylborate was added to initiate polymerization. After polymerization at 40 ° C. for 30 minutes, 5 ml of an ethanol / heptane (1/1) solution containing an antiaging agent was added to terminate the polymerization. After releasing the pressure inside the autoclave, the polymerization solution was put into ethanol to recover polybutadiene. The recovered polybutadiene was then vacuum dried at 80 ° C. for 3 hours. The polymerization results are shown in Table 1.

(Reference Example 1)
The inside of the autoclave with an internal volume of 2 L was purged with nitrogen, charged with a solution consisting of 390 ml of toluene and 210 ml of butadiene, the temperature of the solution was adjusted to 30 ° C., and then 3 ml of a toluene solution (1 mol / L) of triethylaluminum (TEA) was added. The mixture was stirred for 3 minutes at 550 rpm. Next, 1.5 ml of a toluene solution (20 mmol / L) of yttrium (III) tris (2,2,6,6-tetramethyl-3,5-heptanedionato) was added and stirred for 4 minutes, and then up to 40 ° C. The temperature was raised and 0.14 ml of a toluene solution (0.43 mol / L) of triphenylcarbenium tetrakispentafluorophenylborate was added to initiate polymerization. After polymerization at 40 ° C. for 30 minutes, 5 ml of an ethanol / heptane (1/1) solution containing an antiaging agent was added to terminate the polymerization. After releasing the pressure inside the autoclave, the polymerization solution was put into ethanol to recover polybutadiene. The recovered polybutadiene was then vacuum dried at 80 ° C. for 3 hours. The polymerization results are shown in Table 1.

(Example 10)
The inside of the autoclave having an internal volume of 2 L was purged with nitrogen, charged with a solution consisting of 260 ml of toluene and 140 ml of butadiene, the temperature of the solution was adjusted to 30 ° C., and then a toluene solution of diethylaluminum hydride (DEAH) (2 mol / L) 0.2 ml And stirred for 3 minutes at 500 rpm. Next, 1 ml of a toluene solution (20 mmol / L) of tris (1,3-bis (2,4,6-trimethylphenyl) propane-1,3 dionato) yttrium was added and stirred for 4 minutes. The temperature was raised and 0.1 ml of a toluene solution (0.43 mol / L) of triphenylcarbenium tetrakispentafluorophenylborate was added to initiate polymerization. After polymerization at 40 ° C. for 30 minutes, 5 ml of an ethanol / heptane (1/1) solution containing an antiaging agent was added to terminate the polymerization. After releasing the pressure inside the autoclave, the polymerization solution was put into ethanol to recover polybutadiene. The recovered polybutadiene was then vacuum dried at 80 ° C. for 3 hours. The polymerization results are shown in Table 2.

(Example 11)
Polymerization was carried out in the same manner as in Example 10 except that the amount of diethylaluminum hydride (DEAH) added was 0.3 ml of a toluene solution (2 mol / L). The polymerization results are shown in Table 2.

(Example 12)
Polymerization was conducted in the same manner as in Example 10 except that the amount of diethylaluminum hydride (DEAH) added was 0.4 ml of a toluene solution (2 mol / L). The polymerization results are shown in Table 2.

(Example 13)
Polymerization was carried out in the same manner as in Example 10 except that the amount of diethylaluminum hydride (DEAH) added was 0.5 ml of a toluene solution (2 mol / L). The polymerization results are shown in Table 2.

  As described above, by using the conjugated diene polymerization catalyst containing the yttrium compound of the present invention, a conjugated diene polymer having a high cis-1,4 structure content can be produced with high activity.

Claims (6)

An yttrium compound having a bulky ligand represented by the following general formula (1).

^(However, R 1 to R ⁶ is .O representing a saturated hydrocarbon radical of from 1 to 6 carbon represents an oxygen atom, Y represents yttrium atom.) Tris (1,3-bis (2,4,6-trimethylphenyl) propane-1,3-dionato) yttrium. The yttrium compound (A) having a bulky ligand according to any one of claims 1 to 2 , an ionic compound (B) comprising a non-coordinating anion and a cation, groups 2 and 12 of the periodic table A catalyst for conjugated diene polymerization, comprising an organometallic compound (C) of an element selected from Group 13. The conjugated diene polymerization catalyst according to claim 3 , wherein the non-coordinating anion of component (B) is a boron-containing compound and the cation is a carbonium ion. The catalyst for conjugated diene polymerization according to claim 3 , wherein the component (C) is an organoaluminum compound. A method for producing a conjugated diene polymer, comprising polymerizing a conjugated diene compound using the conjugated diene polymerization catalyst according to any one of claims 3 to 5 .