JP4062593B2 - Method for producing styrene-butadiene rubber and high-cis styrene-butadiene rubber - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a styrene butadiene rubber (hereinafter sometimes abbreviated as SBR) and a method for producing the same, particularly a solution polymerization SBR and a method for producing the same.
[0002]
[Prior art]
Styrene butadiene rubber (SBR) is a widely used synthetic rubber, and is particularly widely used as a rubber material for a tread which is a road surface ground portion of a tire for a passenger car. Conventional SBR has been produced by emulsion polymerization or solution anionic polymerization.
[0003]
However, SBR produced by the emulsion polymerization method and the anionic polymerization method did not have a butadiene 1, cis 1,4-bond fraction of 40% or more. For this reason, when it uses for the molded article which receives a dynamic stress, it has a problem on a characteristic. In particular, when used in a tread portion of a tire, there are problems in rolling resistance and wear resistance, and SBR having a high cis 1,4-bond fraction of butadiene has been demanded.
[0004]
As a method for producing SBR having a high cis 1,4-bond fraction, a production method using a transition metal metallocene catalyst is known (Macromol. Chem. Phys., 201, 393, 2000).
[0005]
[Problems to be solved by the invention]
However, in the polymerization method using the transition metal metallocene catalyst, the molecular weight of the obtained SBR is not high, the mechanical strength when formed into a molded product is not sufficient, and particularly high strength like a tire is required. It could not be used for the purpose.
[0006]
An object of the present invention is to use a transition metal metallocene as a catalyst component, a styrene butadiene having a high cis 1,4-bond fraction, a small amount, and capable of stably obtaining a high molecular weight polymer under mild conditions. The object is to provide a method for polymerizing rubber.
[0007]
[Means for Solving the Problems]
The method for producing a styrene butadiene rubber according to the present invention comprises adding (A) a transition metal metallocene catalyst, (B) at least one compound selected from organoaluminum compounds and aluminoxanes, and (C) chloranil which is an electron withdrawing compound. And styrene and butadiene are copolymerized.
[0008]
The most characteristic feature of the present invention is that (C) chloranil , which is an electron-withdrawing compound , is added to copolymerize styrene and butadiene.
[0009]
By the production method having such a structure, a copolymer having a high molecular weight and a practical mechanical strength and at the same time a high cis 1,4-bond fraction of butadiene can be obtained.
[0010]
A preferable addition amount of the components (A) to (C) is monomer / (A) = 10 ² to 10 ⁵ (molar ratio) with respect to the monomer (styrene + butadiene and the like). The ratio of (A) / (B) is preferably 1 / 0.1 to 1/1000 (molar ratio) when an organoaluminum compound is used as component (B), and aluminoxane as component (B). Is preferably 1/10 to 1/5000. The ratio (A) / (C) is preferably 1 / 0.1 to 1/10.
[0011]
In the above-described invention, it is preferable that the obtained SBR has a weight average molecular weight of 200,000 or more and a cis 1,4-bond fraction of 60% or more.
[0012]
When the weight average molecular weight is 200,000 or more, it becomes SBR having high mechanical strength when it is made into a rubber molded product, and when the cis 1,4-bond fraction is 60% or more, particularly tires and red materials. SBR having excellent wear resistance and low rolling resistance when used as
[0013]
Therefore, the styrene butadiene rubber of the present invention is characterized by having a weight average molecular weight of 200,000 or more and a cis 1,4-bond fraction of 60% or more.
[0014]
The cis 1,4-bond fraction is the fraction (%) when the total of cis 1,4-bond, trans 1,4-bond and 1,2-bond of the butadiene constituting the polymer is 100%. It is. The cis 1,4-bond fraction of the present invention is measured by an infrared absorption spectrum method.
[0015]
The method for producing a styrene butadiene rubber of the present invention is preferably solution polymerization in which a polymerization reaction is performed in an organic solvent.
[0016]
High-molecular weight styrene butadiene rubber can be easily produced by solution polymerization.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, (A) a metallocene complex of a transition metal compound, (B) at least one compound selected from an organoaluminum compound and an aluminoxane, and (C) chloranil which is an electron-withdrawing compound are added to styrene. And butadiene are copolymerized to form SBR.
[0018]
(A) As a metallocene type complex of a transition metal compound, a known metallocene type complex of a transition metal compound of Group 4 to 8 of the periodic table can be used. Specifically, metallocene complexes of Group 4 transition metals such as titanium and zirconium (for example, CpTiCl ₃ ), metallocene complexes of Group 5 transition metals such as vanadium, niobium, and tantalum, chromium, etc. Group 6 transition metal metallocene complexes, and metallocene complexes of group 8 transition metals such as cobalt and nickel.
[0019]
Among these, use of a metallocene complex of a transition metal of Group 5 transition metal is preferable. Examples of the metallocene type complex of the Group 5 transition metal compound of the periodic table include compounds represented by the following general formula.
(1) RM · L _a
(2) R _n MX _2-n · L _a
(3) R _n MX _3-n · L _a
(4) RMX ₃ · L _a
(5) RM (O) X ₂ · L _a
(6) R _n MX _3-n (NR ′)
(Wherein n is 1 or 2, a is 0, 1 or 2)
Among the above _{compounds, (1) RM · L a} , (4) RMX 3 · L a, (5) use of the _{RM (O) X 2 · L} a is more preferable. The metal M is preferably at least one of vanadium and titanium.
[0020]
In the general formulas (1) to (6), R represents a cyclopentadienyl group (Cp), a substituted cyclopentadienyl group, an indenyl group, a substituted indenyl group, a fluorenyl group, or a substituted fluorenyl group. Examples of the substituent in the substituted cyclopentadienyl group, substituted indenyl group or substituted fluorenyl group include methyl, ethyl, propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, hexyl and the like. Examples thereof include chain aliphatic hydrocarbon groups or branched aliphatic hydrocarbon groups, aromatic hydrocarbon groups such as phenyl, tolyl, naphthyl, and benzyl, and hydrocarbon groups containing silicon atoms such as trimethylsilyl. Further, a cyclopentadienyl ring and a part of X and each other dimethylsilylene (Me ₂ Si), dimethylmethylene (Me ₂ C), methylphenylmethylene (PhMeC), diphenylmethylene (Ph ₂ C), ethylene, substituted ethylene, etc. And those bonded with a cross-linking group.
[0021]
Specific examples of the substituted cyclopentadienyl group include methylcyclopentadienyl group, 1,2-dimethylcyclopentadienyl group, 1,3-dimethylcyclopentadienyl group, 1,2,3-trimethylcyclopenta Examples thereof include a dienyl group, 1-benzyl-2,3,4,5-tetramethylcyclopentadienyl group, 1-trimethylsilyl-2,3,4,5-tetramethylcyclopentadienyl group.
[0022]
Specific examples of the substituted indenyl group include 1,2,3-trimethylindenyl group, heptamethylindenyl group, 1,2,4,5,6,7-hexamethylindenyl group and the like. Specific examples of the substituted fluorenyl group include a methyl fluorenyl group.
[0023]
Among the Rs exemplified above, use of a cyclopentadienyl group, a methylcyclopentadienyl group, a pentamethylcyclopentadienyl group, an indenyl group, or a 1,2,3-trimethylindenyl group is more preferable.
[0024]
In the general formulas (1) to (6), X represents hydrogen, halogen (F, Cl, Br, I), a hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group, or an amino group. All Xs may be the same or different from each other. Specific examples of the hydrocarbon group having 1 to 20 carbon atoms include linear aliphatic carbonization such as methyl, ethyl, propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl and hexyl. A hydrogen group or a branched aliphatic hydrocarbon group, an aromatic hydrocarbon group such as phenyl, tolyl, naphthyl, benzyl and the like; Of these, methyl, benzyl and the like are preferable. R may be a trimethylsilylmethyl group.
[0025]
Examples of the alkoxy group include alkyloxy groups such as methoxy, ethoxy, phenoxy, propoxy, butoxy. Examples of amino groups include dimethylamino, diethylamino, diisopropylamino and the like.
[0026]
In the general formulas (1) to (6), L is a Lewis base, and is a Lewis basic general inorganic or organic compound capable of coordinating to a metal. Compounds having no active hydrogen are particularly preferred, and specific examples include ethers, esters, ketones, amines, phosphines, silyloxy compounds, olefins, dienes, aromatic compounds, alkynes, and the like.
[0027]
In the general formula (6) R _n MX _3-n (NR ′), NR ′ is an imide group, and R ′ is a hydrocarbon substituent having 1 to 25 carbon atoms. Specific examples of R ′ include linear aliphatic hydrocarbon groups such as methyl, ethyl, propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, hexyl, octyl and neopentyl, Examples thereof include branched aliphatic hydrocarbon groups and aromatic hydrocarbon groups such as phenyl, naphthyl, benzyl, 1-phenylethyl, 6-dimethylphenyl and the like. It may be an alkylsilyl group such as trimethylsilyl.
[0028]
As the general formula (1) RM · L _a , that is, an oxidation number +1 group 5 transition metal compound having a cycloalkadienyl group ligand, cyclopentadienyl (benzene) vanadium, cyclopentadi Enil (toluene) vanadium, cyclopentadienyl (xylene) vanadium, cyclopentadienyl (ferrocene) vanadium, tetramethylcyclopentadienyl (benzene) vanadium, indenyl (benzene) vanadium, cyclopentadienyl tetracarbonyl vanadium, etc. Can be mentioned.
[0029]
Formula (2) Among the compounds represented by _{R n MX 2-n · L} a, n = 1, that is, when having one cycloalkadienyl group as the ligand, other sigma binding coordination As hydrogen atoms, halogen atoms such as chlorine, methyl groups, phenyl groups, benzyl groups, neopentyl groups, trimethylsilyl groups and other hydrocarbon groups, methoxy groups, ethoxy groups, isopropoxy groups and other alkoxy groups, dimethylamino groups, It can have a dialkylamino group such as a diisopropylamino group.
[0030]
Further, the other ligand may have a neutral Lewis base such as amine, amide, phosphine, ether, ketone, ester, olefin, diene, aromatic hydrocarbon, alkyne and the like. Lewis bases without active hydrogen are preferred.
[0031]
In the general formula (2) compound represented by _{R n MX 2-n · L} a, n = 2, that is, when having two cycloalkadienyl groups as the ligand, each of cycloalkadienyl ring They may be bonded to each other through a cross-linking group such as dimethylsilylene, dimethylmethylene, methylphenylmethylene, diphenylmethylene, ethylene, substituted ethylene.
[0032]
Among _{(2) R n MX 2-} n · L a compound represented by the present invention, n = 1, specific examples of the periodic table Group 5 transition metal compound having an oxidation number of +2, chloro cyclopentadienyl Examples include enil (tetrahydrofuran) vanadium, chlorocyclopentadienyl (trimethylphosphine) vanadium, and the like.
[0033]
Among (2) compounds represented by _{R n MX 2-n · L} a of the present invention, n = 2, i.e. the periodic table group 5 transition oxidation number +2 having two cycloalkadienyl groups as the ligand Specific examples of the metal compound include biscyclopentadienyl vanadium, bis (methylcyclopentadienyl) vanadium, bis (1,2-dimethylcyclopentadienyl) vanadium, and the like.
[0034]
(3) Of the specific compounds represented by _{R n MX 3-n · L} a, as the compound n = 1, the cyclopentadienyl vanadium dichloride, methylcyclopentadienyl vanadium dichloride, fluorenyl vanadium Examples thereof include dichlorides such as dichloride, and methyls in which the chlorine atom of these compounds is substituted with a methyl group.
[0035]
(3) Examples of the compound represented by _{R n MX 3-n · L} a, further cyclopentadienyl vanadium di methoxide, cyclopentadienyl vanadium di i- propoxide, cyclopentadienyl vanadium di t- butoxide Alkoxides such as cyclopentadienyl vanadium diphenoxide, cyclopentadienyl vanadium methoxy chloride, cyclopentadienyl vanadium i-propoxy chloride, cyclopentadienyl vanadium t-butoxy chloride, cyclopentadienyl vanadium phenoxy chloride, Or the methyl body etc. which substituted the chlorine atom of these compounds with the methyl group etc. are illustrated.
[0036]
(3) Of the specific compounds represented by _{R n MX 3-n · L} a, as the compound n = 2, the dicyclopentadienyl vanadium dichloride, bis (methylcyclopentadienyl) vanadium chloride, Chlorides such as bis (1,3-dimethylcyclopentadienyl) vanadium chloride, bis (trimethylsilylcyclopentadienyl) vanadium chloride, diindenyl vanadium chloride, or methyl in which the chlorine atom of these compounds is substituted with a methyl group The body is mentioned.
[0037]
In the general formula _{(3) R n MX 3-} n · L a compound represented by _a, R is a hydrocarbon group, or may be linked by a silyl group. Such compounds include chlorides such as dimethylbis (η5-cyclopentadienyl) silane vanadium chloride, dimethylbis (tetramethyl-η5-cyclopentadienyl) silane vanadium chloride, or the chlorine atom of these compounds with a methyl group. And the methyl form substituted with.
[0038]
The general formula (4) Specific compound represented by RMX ₃ · L _a, include compounds of the following (i) ~ (vii).
[0039]
(I) cyclopentadienyl vanadium trichloride, mono-substituted cyclopentadienyl vanadium trichloride, cyclopentadienyl titanium trichloride (ii) 1,2- or 1,3-di-substituted cyclopentadienyl vanadium trichloride, 1,2- or 1,3-disubstituted cyclopentadienyl titanium trichloride (iii) (1,2,3-trimethylcyclopentadienyl) vanadium trichloride, 1,2,4-trimethylcyclopentadienyl) Examples include tri-substituted cyclopentadienyl vanadium trichloride such as vanadium trichloride.
[0040]
(Iv) tetra-substituted or penta-substituted cyclopentadienyl vanadium trichloride (v) indenyl vanadium trichloride, (vi) substituted indenyl vanadium trichloride (vii); chlorine atoms of compounds (i) to (vi) Specific compounds represented by the general formula (5) RM (O) X ₂ such as monoalkoxide, dialkoxide, trialkoxide substituted with an alkoxy group include cyclopentadienyloxovanadium dichloride, methylcyclopentadienyloxo. Examples include vanadium dichloride, benzylcyclopentadienyloxovanadium dichloride, (1,3-dimethylcyclopentadienyl) oxovanadium dichloride, and the like. The methyl body which substituted the chlorine atom of each said compound with the methyl group is also mentioned.
[0041]
Examples of the compound represented by the general formula (5) RM (O) X ₂ include cyclopentadienyloxovanadium dimethoxide, cyclopentadienyloxovanadium dii-propoxide, and the like. Examples include methyl forms in which the chlorine atom of each compound is substituted with a methyl group, (cyclopentadienyl) bis (diethylamido) oxovanadium, (cyclopentadienyl) bis (dii-propylamido) oxovanadium, and the like.
[0042]
Specific compounds represented by the general formula (6) R _n MX _3-n (NR ′) include cyclopentadienyl (methylimido) vanadium dichloride, cyclopentadienyl (phenylimide) vanadium dichloride, cyclopentadiyl. And enyl (2,6-dimethylphenylimide) vanadium dichloride.
[0043]
(6) Examples of the compound represented by R _n MX _3-n (NR ′) include cyclopentadienyl vanadium (phenylimide) dimethoxide, cyclopentadienyl vanadium (phenylimide) di i-propoxide, cyclopentadiene. Enilvanadium (phenylimide) (i-propoxy) chloride, (cyclopentadienyl) bis (diethylamide) vanadium (phenylimide), (cyclopentadienyl) bis (dii-propylamido) vanadium (phenylimide), etc. Can be mentioned.
[0044]
In the present invention, as the organoaluminum compound to be used as the component (B), a known organoaluminum compound can be used. Specific examples include trialkylaluminums such as trimethylaluminum, triethylaluminum, and triisobutylaluminum, and dialkyl halides such as diethylaluminum chloride.
[0045]
The chain aluminoxane that can be used as the component (B) is obtained by bringing an organoaluminum compound and a condensing agent into contact with each other, and is represented by the general formula (—Al (R ′) O—) n. And a chain aluminoxane. R ′ is a hydrocarbon group having 1 to 10 carbon atoms and includes those partially substituted with a halogen atom and / or an alkoxy group. n is the degree of polymerization of the chain aluminoxane, and is 5 or more, preferably 10 or more. Examples of R ′ include a methyl, ethyl, propyl, and isobutyl group. Among these, a methyl group and an ethyl group are preferable. Examples of organoaluminum compounds used as aluminoxane raw materials include trialkylaluminums such as trimethylaluminum, triethylaluminum and triisobutylaluminum described above, and mixtures thereof.
[0046]
A typical example of the condensing agent used in the production of the chain aluminoxane is water, but in addition to this, any one that undergoes a condensation reaction with the trialkylaluminum, for example, adsorbed water such as inorganic substances, diol, etc. Is mentioned.
[0047]
As the electron-withdrawing compound (C) of the present invention, known electron-withdrawing compounds can be used. Specific examples include acetic acid derivatives such as trichloroacetic acid and trifluoroacetic acid, benzoquinone derivatives such as tetrachlorobenzoquinone (chloranil) and tetrafluorobenzoquinone, and tetracyanoquinodimethane (TCNQ). These electron withdrawing compounds may be used alone or in combination of two or more.
[0048]
In the method for producing SBR of the present invention, styrene and butadiene are used as monomers, but it is preferable to copolymerize other monomers within the range that does not impair the characteristics of the obtained SBR from the viewpoint of improving the characteristics. It is a mode. Such other copolymerizable monomers include isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2,4-hexadiene, conjugated diene monomers such as 4-methylpentadiene, ethylene, propylene, butene- Examples include monoolefins such as 1, butene-2, isobutene, pentene-1, hexene-1, and octene-1, cyclic monoolefins such as norbornene, and aromatic monoolefins such as α-methylstyrene.
[0049]
As the solvent used in the method for producing the styrene butadiene rubber of the present invention, a known solvent used in the polymerization of styrene butadiene rubber can be used without limitation. Specifically, aromatic solvents such as toluene, xylene and tetralin, aliphatic or alicyclic solvents such as n-hexane, n-pentane, n-heptane, cyclohexane, cyclopentane, cycloheptane and decalin Is exemplified as a suitable solvent.
[0050]
A known method can be used as a polymerization method for producing SBR. The polymerization may be either solution polymerization or bulk polymerization, but is preferably solution polymerization as described above.
[0051]
The solution polymerization method is performed, for example, by charging an organic solvent and a styrene monomer and a butadiene monomer in a predetermined ratio in a reaction vessel, adjusting the temperature to a predetermined temperature, and adding a catalyst.
[0052]
The polymerization temperature is about -10 ° C to 150 ° C, and more preferably 0 to 120 ° C. The polymerization time is appropriately set according to the temperature and the target molecular weight, but is about 3 minutes to 10 hours.
[0053]
The polymerization reaction is stopped by, for example, adding a solvent such as alcohol or a solvent containing an inhibitor to the polymerization system and stirring. After the completion of the polymerization, for example, the solution can be reprecipitated in a non-solvent of SBR, filtered and then dried, or the solvent can be removed from the solution after polymerization to obtain SBR.
[0054]
【Example】
Examples of the present invention will be described below.
Example 1
A 1.5 L autoclave equipped with a stirrer was replaced with nitrogen, 300 ml of toluene as a solvent, 2.1 mmol of cyclopentadienyl titanium trichloride (CpTiCl ₃ ), 210 mmol of methylaluminoxane (MAO), 2.1 mmol of chloranil ( CpTiCl ₃ / chloranil = 1/1 (molar ratio)), 37.5 ml of butadiene and 37.5 ml of styrene were added, and polymerization was performed at 60 ° C. for 30 minutes.
Ten minutes after the start of polymerization, a methanol solution in which a small amount of pt-butylcatechol as a polymerization inhibitor was dissolved was added to the polymerization solution to stop the polymerization reaction. The SBR polymer was obtained by removing toluene from this solution.
[0055]
(Example 2)
An SBR polymer was obtained in the same manner as in Example 1 except that the addition amount of chloranil was 21 mmol (CpTiCl ₃ / chloranil = 1/10 (molar ratio)).
[0056]
(Comparative Example 1)
An SBR polymer was obtained in the same manner as in Example 1 except that chloranil was not added.
[0057]
(Comparative Example 2)
An SBR polymer was obtained in the same manner as in Example 1 except that instead of the components (A) to (C) of the present invention, a mixture of 31.2 mmol of n-butyllithium and 31.2 mmol of tetrahydrofuran was used as the catalyst component. .
[0058]
<Evaluation>
(Measurement of molecular weight)
GPC LC-10 (manufactured by Shimadzu Corporation) was used, tetrahydrofuran (THF) was used as a mobile phase, and measurement was performed at 40 ° C. to obtain a weight average molecular weight and a number average molecular weight in terms of standard polystyrene.
[0059]
(Micro structure)
The cis 1,4-bond fraction and 1,2-bond fraction were measured by an infrared absorption spectrum method. For the measurement, Paragon 1000 (manufactured by PerkinElmer) was used. The measurement was performed by the transmission method.
The result is absorption intensity of 735cm ^-1 attributed to cis 1,4 bond of butadiene units, absorption intensity of 967 cm ^-1 attributed to trans 1,4 bond, attributed to 1,2-linked 911cm ^-1 absorption intensity was measured and determined from the intensity ratio.
[0060]
The evaluation results are shown in Table 1. From the results of this table, the SBR according to the present invention has a high molecular weight with a weight average molecular weight of 365,000 (Example 1) and 431,000 (Example 2), and a cis 1,4-bond content. All the rates are 60% or more. On the other hand, the SBR of Comparative Example 1 that does not use an electron-withdrawing compound (configuration (C)) has a cis 1,4-bond fraction of 62.2%, but a weight average molecular weight of 35,000. Yes, the SBR of Comparative Example 2 had a high weight average molecular weight of 223,000, but a low cis 1,4-bond fraction of 22.5%.
[0061]
[Table 1]

Claims (3)

  Styrene butadiene copolymerized with styrene and butadiene by adding (A) transition metal metallocene catalyst, (B) at least one compound selected from organoaluminum compounds and aluminoxanes, and (C) chloranil as an electron-withdrawing compound Rubber production method.   The method for producing a styrene butadiene rubber according to claim 1, wherein the obtained styrene butadiene rubber has a weight average molecular weight of 200,000 or more and a cis 1,4-bond content of 60% or more.   The method for producing a styrene butadiene rubber according to claim 1 or 2, wherein the polymerization reaction is carried out in an organic solvent.