Method for producing 1, 2-polybutadiene, and catalyst composition

Abstract

The purpose of the present invention is to provide: a method for producing 1, 2-polybutadiene with which it is possible to produce 1, 2-polybutadiene that has high solubility in a polymerization solvent and does not readily precipitate; this method for producing 1, 2-polybutadiene is characterized by comprising a step for polymerizing 1, 3-butadiene in the presence of a catalyst system containing (a) a carboxylic acid salt of a transition metal, (b) an aluminoxane compound, and (c) a phosphine compound represented by general formula (1). (In general formula (1), R1 and R2 each represent a substituted or unsubstituted aryl group having 6-30 carbon atoms, which are the same or different from each other, and R3 represents a substituted or unsubstituted branched alkyl group having 4-20 carbon atoms or a substituted cycloalkyl group having 6-30 carbon atoms.

Description

Technical Field

[0001] The present invention relates to a method for producing 1,2-polybutadiene by polymerizing 1,3-butadiene in the presence of a specific catalyst system to produce syndiotactic-1,2-polybutadiene, and a catalyst composition for the method of production. Background Technology

[0002] Syndiotactic-1,2-polybutadiene has a structure composed of highly crystalline regions and amorphous parts, thus possessing the functions of a thermoplastic elastomer. Furthermore, due to the abundance of chemically reactive carbon-carbon double bonds in its molecule, it also functions as a conventional vulcanized rubber or a thermosetting resin with increased crosslinking density. In addition, 1,2-polybutadiene exhibits excellent processability, and therefore is also used as a modifier for other resins or thermoplastic elastomers (e.g., for tire applications to improve strength) and as a polymer material for medical use.

[0003] Conventional methods for manufacturing 1,2-polybutadiene include: polymerizing 1,3-butadiene in the presence of a cis-polymerization catalyst to generate cis-1,4-polybutadiene; then polymerizing 1,3-butadiene in the presence of a 1,2-polymerization catalyst to finally generate polybutadiene (see, for example, Patent Document 1); and polymerizing butadiene or butadiene and a conjugated diene other than butadiene in the presence of a catalyst containing a cobalt compound and an aluminum oxane (see, for example, Patent Document 2).

[0004] However, in the aforementioned method for manufacturing 1,2-polybutadiene, polymer sometimes precipitates in the polymerization tank during the continued polymerization process. Furthermore, if polymer precipitation occurs in the polymerization tank, polymerization must be stopped and the tank cleaned, resulting in a decrease in productivity in terms of production time and output.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Publication No. 49-017667

[0008] Patent Document 2: Japanese Patent Application Publication No. 2006-089759 Summary of the Invention

[0009] The present invention is carried out based on the circumstances described above, and its object is to provide a method for manufacturing 1,2-polybutadiene that has high solubility in polymerization solvents and is not easily precipitated, as well as a catalyst composition for the manufacturing method.

[0010] In order to achieve the above-mentioned objective, the inventors of this invention have conducted in-depth research and discovered that by using a specific catalyst composition as a polymerization catalyst, it is possible to selectively synthesize 1,2-polybutadiene with high solubility in polymerization solvents and which is not easily precipitated, thus completing this invention.

[0011] The method for manufacturing 1,2-polybutadiene of the present invention is characterized by comprising the following steps: polymerizing 1,3-butadiene in the presence of a catalyst system containing (a) a carboxylate of a transition metal, (b) an aluminum oxane compound, and (c) a phosphine compound represented by the following general formula (1).

[0012]

Chemical Formula 1

[0013]

[0014] In the above general formula (1), R 1 and R 2 Aryl groups, representing substituted or unsubstituted carbon atoms with 6 to 30 carbon atoms, can be the same or different. Additionally, R... 3 This refers to a branched alkyl group with 4 to 20 carbon atoms, either substituted or unsubstituted, or a substituted cycloalkyl group with 6 to 30 carbon atoms.

[0015] In the method for manufacturing 1,2-polybutadiene of the present invention, the transition metal constituting the carboxylate of the transition metal in (a) is preferably cobalt.

[0016] In the method for manufacturing 1,2-polybutadiene of the present invention, the 1,2-vinyl bond content of the 1,2-polybutadiene is preferably 30% by mass or more.

[0017] The catalyst composition of the present invention is characterized by comprising: (a) a transition metal carboxylate, (b) an aluminum oxane compound, and (c) a phosphine compound represented by the following general formula (1).

[0018]

Chemical Formula 2

[0019]

[0020] In the above general formula (1), R 1 and R 2 Aryl groups, representing substituted or unsubstituted carbon atoms with 6 to 30 carbon atoms, can be the same or different. Additionally, R... 3 This refers to a branched alkyl group with 4 to 20 carbon atoms, either substituted or unsubstituted, or a substituted cycloalkyl group with 6 to 30 carbon atoms.

[0021] In the catalyst composition of the present invention, the transition metal constituting the carboxylate of the transition metal in (a) is preferably cobalt.

[0022] Invention Effects

[0023] According to the method for manufacturing 1,2-polybutadiene of the present invention, 1,2-polybutadiene has high solubility in the polymerization solvent at the desired polymerization temperature and is not easily precipitated in the polymerization tank during polymerization. As a result, it is not necessary to stop polymerization and clean the polymerization tank during the polymerization process, thus achieving high productivity.

[0024] The catalyst composition according to the present invention enables the production of the above-mentioned 1,2-polybutadiene with high solubility in polymerization solvents, and can reliably achieve high productivity. Detailed Implementation

[0025] The embodiments of the present invention will be described below.

[0026] The method for manufacturing 1,2-polybutadiene of the present invention includes the following steps: polymerizing 1,3-butadiene in the presence of a catalyst system consisting of a catalyst composition comprising (a) a carboxylate containing a transition metal, (b) an aluminoxane compound and (c) a phosphine compound represented by the above general formula (1) (hereinafter also referred to as "specific phosphine compound") (hereinafter also referred to as "specific catalyst composition").

[0027] Examples of transition metals that are carboxylates of (a) a transition metal constituting a specific catalyst composition include manganese, iron, cobalt, nickel, etc., with cobalt being preferred.

[0028] Specific examples of (a) transition metal carboxylates include: manganese (II) oxalate, manganese (II) formate, manganese (II) acetate, manganese (III) acetate, manganese (II) benzoate, manganese (II) 4-cyclohexylbutyrate, manganese (II) 2-ethylhexanoate, and their hydrates; ferric (II) oxalate, ferric (II) acetate, ferric fumarate, ferric lactate, ferric gluconate, sodium ferric (II) citrate, ferric (III) citrate, ferric (II) benzoate, ferric stearate (I) Cobalt(II) oxalate, cobalt(II) acetate, cobalt(II) fumarate, cobalt(II) lactate, cobalt(II) gluconate, cobalt(III) citrate, cobalt(II) benzoate, cobalt(II) stearate, cobalt(II) octoate, etc., and their hydrates; nickel(II) formate, nickel(II) oxalate, nickel(II) acetate, nickel(II) fumarate, nickel(II) lactate, nickel(II) gluconate, nickel(II) benzoate, nickel(II) stearate, etc., and their hydrates.

[0029] (b) Aluminoxane compounds that are specific catalyst compositions, for example, can be represented by compounds of the following general formula (2) or general formula (3).

[0030]

Chemical Formula 3

[0031]

[0032] [Chemical Formula 4]

[0033]

[0034] In aluminum oxane compounds represented by the above general formula (2) or the above general formula (3), R 4 ~R 9 Each group is independently a hydrocarbon group such as methyl, ethyl, propyl, or butyl, preferably methyl or ethyl, and particularly preferably methyl. Furthermore, m is an integer from 2 to 100, preferably 5 or more.

[0035] Specific examples of (b) aluminum oxane compounds include methyl aluminum oxane, ethyl aluminum oxane, propyl aluminum oxane, butyl aluminum oxane, etc., with methyl aluminum oxane being particularly preferred.

[0036] (c) In the above general formula (1) representing a specific phosphine compound of a specific catalyst composition, R 1 and R 2 Aryl groups, representing substituted or unsubstituted carbon atoms, numbering 6 to 30, can be the same or different from each other.

[0037] R 1 and R 2 Preferably, it is an aryl group with 6 to 15 carbon atoms, either substituted or unsubstituted.

[0038] Examples of substituents that can replace aryl groups include alkyl groups with 1 to 12 carbon atoms and alkoxy groups with 1 to 12 carbon atoms. When the number of substituents is 2 or more, they can be the same as each other or different.

[0039] Specific examples of aryl groups with 6 to 30 carbon atoms, whether substituted or unsubstituted, include: phenyl, 2-methylphenyl, 4-methylphenyl, 2-tert-butylphenyl, 2,4,6-trimethylphenyl, 2-isopropylphenyl, methoxyphenyl, 1,1-diphenylethyl, phenoxyphenyl, naphthyl, phenylnaphthyl, phenanthryl, and anthracene.

[0040] Specifically, R 1 and R 2 Preferably, all are phenyl.

[0041] In addition, in the above general formula (1), R 3 It refers to a branched alkyl group with 4 to 20 carbon atoms that has been substituted or unsubstituted, or a cyclic alkyl group with 6 to 30 carbon atoms that has been substituted.

[0042] R 3Preferably, it is a branched alkyl group with 4 to 15 carbon atoms, either substituted or unsubstituted, or a cyclic alkyl group with 6 to 15 carbon atoms, substituted.

[0043] Specific examples of branched alkyl groups with 4 to 20 carbon atoms, whether substituted or unsubstituted, include: tert-butyl, tert-pentyl, isopentyl, 3-ethyl-3-pentyl, and 3-methyl-3-pentyl.

[0044] Examples of substituents for cycloalkyl groups include alkyl groups with 1 to 12 carbon atoms, alkoxy groups with 1 to 12 carbon atoms, and alkylsilyl groups with 1 to 12 carbon atoms. When the number of substituents is 2 or more, they can be the same as or different from each other.

[0045] Specific examples of substituted cycloalkyl groups with 6 to 30 carbon atoms include: hexamethylcyclohexyl, 2-isopropyl-5-methylcyclohexyl (neomenthyl), pentamethylcyclopentyl, 2-cyclooctylethyl, methylcyclohexyl, methoxycyclohexyl, and phenylcyclohexyl.

[0046] Specifically, R 3 Preferred is tert-butyl or 2-isopropyl-5-methylcyclohexyl (neomenthyl).

[0047] In a specific catalyst composition, (c) the phosphorus atoms (P) of a specific phosphine compound do not form a complex.

[0048] Regarding the amount of a specific catalyst composition used, the molar ratio (BD / Al) of aluminum atoms (Al) in (b) the aluminoxane compound to 1,3-butadiene is preferably 400 to 4,000, more preferably 800 to 2,000. A (BD / Al) ratio below 400 is economically disadvantageous; a ratio above 4,000 may reduce polymerization activity.

[0049] In addition, regarding the amount of (b) aluminum oxane compound used, the molar ratio (Al / M) of aluminum atoms (Al) to transition metal atoms (M) of the carboxylate of (a) transition metal is preferably 4 to 200, more preferably 10 to 150.

[0050] Furthermore, regarding the amount of the specific phosphine compound used in (c), the molar ratio (P / M) of phosphorus atoms (P) to transition metal atoms (M) of the carboxylate of the transition metal in (a) is preferably 0.1 to 50, more preferably 0.5 to 20, and particularly preferably 1 to 20.

[0051] The method for manufacturing 1,2-polybutadiene of the present invention is carried out in the presence of a polymerization solvent, wherein a non-reactive organic solvent is used as the polymerization solvent. Examples of non-reactive organic solvents include: aromatic hydrocarbons such as benzene, toluene, xylene, and cumene; aliphatic hydrocarbons such as n-pentane, n-hexane, and n-butane; alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, and cyclohexane, and mixtures thereof.

[0052] The polymerization temperature is typically -50°C to 120°C, preferably -20°C to 100°C. The polymerization reaction is preferably a continuous polymerization involving multiple groups linked in series. It should be noted that the monomer concentration in the solvent is typically 5-50% by mass, preferably 10-35% by mass. Furthermore, to produce 1,2-polybutadiene, it is necessary to carefully avoid the introduction of deactivating compounds such as oxygen, water, or carbon dioxide into the polymerization system to prevent deactivation of the catalyst and polymer.

[0053] It should be noted that in the method for manufacturing 1,2-polybutadiene of the present invention, approximately 10% or less of a conjugated diene other than 1,3-butadiene may also be used. Examples of conjugated dienes include 4-alkyl-substituted 1,3-butadiene and 2-alkyl-substituted 1,3-butadiene. Examples of 4-alkyl-substituted 1,3-butadiene include 1,3-pentadiene, 1,3-hexadiene, 1,3-heptadiene, 1,3-octadiene, 1,3-nonadiene, and 1,3-decadiene. In addition, representative substances of 2-alkyl-substituted 1,3-butadiene include: 2-methyl-1,3-butadiene (isoprene), 2-ethyl-1,3-butadiene, 2-propyl-1,3-butadiene, 2-isopropyl-1,3-butadiene, 2-butyl-1,3-butadiene, 2-isobutyl-1,3-butadiene, 2-pentyl-1,3-butadiene, 2-isopentyl-1,3-butadiene, 2-hexyl-1,3-butadiene, 2-cyclohexyl-1,3-butadiene, 2-isohexyl-1,3-butadiene, 2-heptyl-1,3-butadiene, 2-isoheptyl-1,3-butadiene, 2-octyl-1,3-butadiene, and 2-isooctyl-1,3-butadiene. Among these conjugated dienes, preferred conjugated dienes for use in combination with 1,3-butadiene include isoprene and 1,3-pentadiene.

[0054] When the polymerization reaction proceeds to the desired stage, polymerization inhibitors such as alcohols, anti-aging agents, antioxidants, and ultraviolet absorbers can be added to the reaction mixture. Next, the generated polymer is separated, cleaned, and dried according to conventional methods to obtain the target 1,2-polybutadiene.

[0055] [Products]

[0056] The 1,2-polybutadiene obtained by the above manufacturing method contains 30% by mass or more, preferably 35% by mass or more, and more preferably 40% by mass or more. The method for determining the 1,2-vinyl bond content is as described in the examples below.

[0057] In addition, the precipitation index temperature difference of 1,2-polybutadiene, calculated as (polymerization temperature - precipitation index temperature), is preferably 5 to 50°C, more preferably 10 to 50°C, and particularly preferably 30 to 40°C.

[0058] Regarding the precipitation index temperature, the polymer solution obtained by the above manufacturing method (1,2-polybutadiene) was diluted with cyclohexane to achieve the solid component concentration required for polymerization. The solution viscosity was measured every 5°C. Logarithmic plots were performed from the high-temperature side to the low-temperature side. When a point where linearity was lost was reached, the temperature of the high-temperature side preceding that point was determined as the precipitation index temperature.

[0059] By ensuring that the precipitation index temperature difference is within the aforementioned range, the solubility of 1,2-polybutadiene in the polymerization solvent is high at the desired polymerization temperature. Therefore, it is less likely to precipitate in the polymerization tank during polymerization. As a result, there is no need to stop polymerization and clean the polymerization tank during the polymerization process, thus achieving higher productivity in the above manufacturing method.

[0060] It should be noted that when the temperature difference between the precipitation index and the polymerization temperature is below 0℃, i.e. above the polymerization temperature, the precipitation will clearly occur in the polymerization tank during polymerization, requiring cleaning of the polymerization tank.

[0061] Furthermore, the melting point of 1,2-polybutadiene is preferably above 126°C, more preferably above 130°C, and particularly preferably above 135°C. The melting point is determined according to the method described in the examples below.

[0062] The molecular weight of 1,2-polybutadiene, expressed as a weight-average molecular weight converted from polystyrene, is generally preferably between 100,000 and 600,000. If it is below 100,000, the strength properties deteriorate; on the other hand, if it exceeds 600,000, the processability deteriorates. The molecular weight can be adjusted by the ratio of (b) aluminum atoms (Al) in the aluminoxane compound to (a) transition metal atoms (M) in the carboxylate of the transition metal.

[0063] Furthermore, the 1,2-polybutadiene obtained by the above manufacturing method can achieve sufficient strength even when it is alone and not cross-linked, so it is suitable for non-cross-linked molding applications such as injection molding, extrusion molding, industrial parts, and film applications.

[0064] Furthermore, due to its excellent crosslinking reactivity, it is also preferred for applications in crosslinked rubber and as a reaction aid in vulcanized rubber. In this case, there are no particular restrictions on the processing method; it can be achieved through melt mixing using rollers, kneaders, closed mixers, screw extruders, rotor feed extruders, etc., commonly used in resin and rubber processing.

[0065] Furthermore, 1,2-polybutadiene obtained in this way can be preferably used as a modifier for other thermoplastic elastomers or resins.

[0066] Example

[0067] The following describes specific embodiments of the present invention; however, the present invention is not limited to these embodiments. It should be noted that in the embodiments, unless otherwise specified, "parts" and "%" refer to weight.

[0068] In addition, the various measurements in the embodiments utilize the methods described below.

[0069] Regarding the solids concentration ratio, the solids concentration was measured when polymerization was carried out under conditions where the polymerization conversion rate reached 90% or higher, and expressed as an index with Example 1 set as 100. For the determination of solids concentration, a sample was collected and placed in an aluminum pan of pre-measured mass. The pan was heated using a hot plate at 170°C for 5 minutes, and the solids concentration in the sample was determined based on the mass before and after heating.

[0070] The vinyl bond content (1,2-bond content) and cis bond content (cis-1,4-bond content) of 1,2-polybutadiene were determined by infrared absorption spectroscopy (Morrello method).

[0071] Regarding the weight-average molecular weight (Mw), the converted value of polystyrene was determined by gel permeation chromatography (GPC) at 135°C using o-dichlorobenzene as the solvent.

[0072] Regarding the melting point, it was determined using a DSC measuring device and the ASTM method. The temperature at which the endothermic peak reaches its minimum value was set as the melting point.

[0073] The precipitation index temperature was measured as described above. Furthermore, if the precipitation index temperature is below the polymerization temperature, the precipitation index is rated as "A", and if the precipitation index temperature is above the polymerization temperature, the precipitation index is rated as "B".

[0074] [Example 1]

[0075] <Polymerization of 1,3-butadiene>

[0076] In a dry nitrogen atmosphere, 30 g of 1,3-butadiene (BD) and 114 g of cyclohexane (S / M = 3.8) were placed in a 300 ml pressure-resistant bottle. 0.5% toluene solution of cobalt octoate (as Co atoms), 1.0% toluene solution of (S)-(+)-neomenthyl diphenylphosphine, and 1.0% toluene solution of methylaluminoxane (as Al atoms) were added in the same manner as BD / Al (molar ratio) = 500, Al / Co (atomic ratio) = 25, and P / Co = 1.0, respectively. Polymerization was carried out in a constant temperature water bath at 80 °C for 120 minutes.

[0077] A small amount of ethanol was added as a polymerization inhibitor to stop the reaction.

[0078] Next, 0.3 parts of 2,6-di-tert-butyl-p-cresol were added relative to 100 parts of the polymer, and the mixture was heated on a hot plate to remove the solvent, thereby obtaining the polymer. The polymerization conversion rate was determined based on the yield. The results are shown in Table 1.

[0079] [Comparative Example 1]

[0080] In a dry nitrogen atmosphere, 30g of 1,3-butadiene (BD) and 114g of cyclohexane (S / M = 3.8) were placed in a 300ml pressure-resistant bottle. A 0.5% toluene solution of cobalt octoate (as Co atoms), a 1.0% toluene solution of cyclohexyl diphenylphosphine, and a 1.0% toluene solution of methylaluminoxane (as Al atoms) were added to the bottle at BD / Al (molar ratio) = 500, Al / Co (atomic ratio) = 30, and P / Co = 1.0, respectively. The mixture was polymerized in a constant temperature water bath at 40℃ for 120 minutes. As a result, the polymer solution showed reduced fluidity due to precipitation.

[0081] A small amount of ethanol was added as a polymerization inhibitor to stop the reaction.

[0082] Next, 0.3 parts of 2,6-di-tert-butyl-p-cresol were added relative to 100 parts of the polymer, and the mixture was heated on a hot plate to remove the solvent, thereby obtaining the polymer. The polymerization conversion rate was determined based on the yield. The results are shown in Table 1.

[0083] [Comparative Example 2]

[0084] In a dry nitrogen atmosphere, 24 g of 1,3-butadiene (BD) and 132 g of cyclohexane (S / M = 5.5) were placed in a 300 ml pressure-resistant bottle. 0.5% cobalt octoate toluene solution (as Co atoms), 1.0% cyclohexyl diphenylphosphine toluene solution, and 1.0% methylaluminoxane toluene solution (as Al atoms) were added in the same manner as BD / Al (molar ratio) = 500, Al / Co (atomic ratio) = 30, and P / Co = 1.0, respectively. Polymerization was carried out in a constant temperature water bath at 40 °C for 120 minutes.

[0085] A small amount of ethanol was added as a polymerization inhibitor to stop the reaction.

[0086] Next, 0.3 parts of 2,6-di-tert-butyl-p-cresol were added relative to 100 parts of the polymer, and the mixture was heated on a hot plate to remove the solvent, thereby obtaining the polymer. The polymerization conversion rate was determined based on the yield. The results are shown in Table 1.

[0087] [Comparative Example 3]

[0088] In a dry nitrogen atmosphere, 30 g of 1,3-butadiene (BD) and 114 g of cyclohexane (S / M = 3.8) were placed in a 300 ml pressure-resistant bottle. 0.5% cobalt octoate toluene solution (as Co atoms), 1.0% cyclohexyl diphenylphosphine toluene solution, and 1.0% methylaluminoxane toluene solution (as Al atoms) were added in the same manner as BD / Al (molar ratio) = 500, Al / Co (atomic ratio) = 50, and P / Co = 1.0, respectively. Polymerization was carried out in a constant temperature water bath at 70 °C for 120 minutes.

[0089] A small amount of ethanol was added as a polymerization inhibitor to stop the reaction.

[0090] Next, 0.3 parts of 2,6-di-tert-butyl-p-cresol were added relative to 100 parts of the polymer, and the mixture was heated on a hot plate to remove the solvent, thereby obtaining the polymer. The polymerization conversion rate was determined based on the yield. The results are shown in Table 1.

[0091] [Example 2]

[0092] <Polymerization of 1,3-butadiene>

[0093] In a dry nitrogen atmosphere, 30 g of 1,3-butadiene (BD) and 114 g of cyclohexane (S / M = 3.8) were placed in a 300 ml pressure-resistant bottle. 0.5% toluene solution of cobalt octoate (as Co atoms), 0.5% toluene solution of (S)-(+)-neomenthyl diphenylphosphine and 1.0% toluene solution of methylaluminoxane (as Al atoms) were added in the same manner as BD / Al (molar ratio) = 500, Al / Co (atomic ratio) = 20 and P / Co = 1.0, respectively. Polymerization was carried out in a constant temperature water bath at 70 °C for 120 minutes.

[0094] A small amount of ethanol was added as a polymerization inhibitor to stop the reaction.

[0095] Next, 0.3 parts of 2,6-di-tert-butyl-p-cresol were added relative to 100 parts of the polymer, and the mixture was heated on a hot plate to remove the solvent, thereby obtaining the polymer. The polymerization conversion rate was determined based on the yield. The results are shown in Table 1.

[0096] [Example 3]

[0097] <Polymerization of 1,3-butadiene>

[0098] In a dry nitrogen atmosphere, 30 g of 1,3-butadiene (BD) and 114 g of cyclohexane (S / M = 3.8) were placed in a 300 ml pressure-resistant bottle. 0.5% toluene solution of cobalt octoate (as Co atoms), 0.5% toluene solution of (S)-(+)-neomenthyl diphenylphosphine and 1.0% toluene solution of methylaluminoxane (as Al atoms) were added in the same manner as BD / Al (molar ratio) = 500, Al / Co (atomic ratio) = 140 and P / Co = 0.3, respectively. Polymerization was carried out in a constant temperature water bath at 50 °C for 120 minutes.

[0099] A small amount of ethanol was added as a polymerization inhibitor to stop the reaction.

[0100] Next, 0.3 parts of 2,6-di-tert-butyl-p-cresol were added relative to 100 parts of the polymer, and the mixture was heated on a hot plate to remove the solvent, thereby obtaining the polymer. The polymerization conversion rate was determined based on the yield. The results are shown in Table 1.

[0101] Table 1

[0102]

[0103] As shown in Table 1, in Examples 1 to 3, it was confirmed that 1,2-polybutadiene with the desired melting point could be produced in the desired yield (solid component concentration ratio) without the precipitation of polymer solution.

[0104] On the other hand, in Comparative Example 1, where cyclohexyldiphenylphosphine was used as the phosphine compound, in order to produce 1,2-polybutadiene with the same melting point and production yield as in Example 1, the polymerization temperature needed to be lowered to 40°C. However, lowering the polymerization temperature resulted in reduced fluidity of the polymer solution due to precipitation. Furthermore, in Comparative Example 2, where cyclohexyldiphenylphosphine was used as the phosphine compound, in order to produce the same polymer using existing technology without polymer solution precipitation, the solids concentration ratio (S / M) of 5.5, an indicator of polymer productivity, needed to be reduced. Additionally, in Comparative Example 3, where cyclohexyldiphenylphosphine was used as the phosphine compound and the polymerization temperature was set to 70°C to prevent polymer solution precipitation, the melting point of the obtained polymer decreased as the polymerization temperature increased, making it impossible to obtain the desired polymer.

Claims

1. A method for manufacturing 1,2-polybutadiene, characterized in that, It has the following processes: 1,3-Butadiene is polymerized in the presence of a catalyst system containing (a) a carboxylate of a transition metal, (b) an aluminoxane compound, and (c) a phosphine compound represented by the following general formula (1). 【Chemical Formula 1】 In the above general formula (1), R 1 and R 2 Aryl groups representing substituted or unsubstituted carbon atoms, with 6 to 30 carbon atoms, can be the same or different. Additionally, R... 3 It refers to a branched alkyl group with 4 to 20 carbon atoms that has been substituted or unsubstituted, or a cyclic alkyl group with 6 to 30 carbon atoms that has been substituted.

2. The method for manufacturing 1,2-polybutadiene according to claim 1, characterized in that, The transition metal constituting the carboxylate of the transition metal in (a) is cobalt.

3. The method for manufacturing 1,2-polybutadiene according to claim 1, characterized in that, The 1,2-polybutadiene has a 1,2-vinyl bond content of 30% by mass or more.

4. A catalyst composition, characterized in that, Contains: (a) a transition metal carboxylate, (b) an aluminum oxane compound, and (c) a phosphine compound represented by the following general formula (1), 【Chemical Formula 2】 In the above general formula (1), R 1 and R 2 Aryl groups representing substituted or unsubstituted carbon atoms, with 6 to 30 carbon atoms, can be the same or different. Additionally, R... 3 It refers to a branched alkyl group with 4 to 20 carbon atoms that has been substituted or unsubstituted, or a cyclic alkyl group with 6 to 30 carbon atoms that has been substituted.

5. The catalyst composition according to claim 4, characterized in that, The transition metal constituting the carboxylate of the transition metal in (a) is cobalt.

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