JP2003292515A - Method for producing styrene-butadiene rubber and high- cis-styrene-butadiene rubber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for stably producing a high-molecular weight styrene-butadiene rubber ≥60% in the cis-1,4-linkage fraction of the butadiene units using a transition metal metallocene as a catalytic component under mild conditions. <P>SOLUTION: The method for producing the styrene-butadiene rubber comprises carrying out a copolymerization between styrene and butadiene in the presence of (A) a transition metal metallocene catalyst, (B) at least one compound selected from organoaluminum compounds and aluminoxanes and (C) an electron-attracting compound. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD 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]

BACKGROUND OF THE INVENTION Styrene butadiene rubber (SBR) is
It is a widely used synthetic rubber, and is particularly widely used as a rubber material for a tread that is a road surface grounding portion of a tire for passenger cars. Conventional SBR has been produced by emulsion polymerization or solution anion polymerization.

However, the SBRs produced by the emulsion polymerization method and the anionic polymerization method each had a cis-1,4-bond fraction of butadiene of not more than 40%. Therefore, when it is used for a molded product that receives a dynamic stress, there is a problem in characteristics. Especially when used in the tread part of a tire, rolling resistance,
There is a problem in abrasion resistance, and SBR having a high cis-1,4-bond fraction of butadiene has been demanded.

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. P.
hys. , 201, 393, 2000).

[0005]

However, in the polymerization method using the above transition metal metallocene catalyst, the S
The molecular weight of BR was not high and the mechanical strength of the molded product was not sufficient, and it could not be used especially for applications requiring high strength such as tires.

An object of the present invention is to use a transition metal metallocene as a catalyst component and to obtain a high molecular weight polymer stably under mild conditions with a high and low cis 1,4-bond fraction. Another object of the present invention is to provide a method for polymerizing a novel styrene-butadiene rubber.

[0007]

The method for producing a styrene-butadiene rubber of the present invention comprises: (A) a transition metal metallocene catalyst; (B) at least one compound selected from an organoaluminum compound and an aluminoxane; and (C). It is characterized in that an electron-withdrawing compound is added to copolymerize styrene and butadiene.

The most characteristic feature of the present invention is that (C) an electron-withdrawing compound is added to copolymerize styrene and butadiene.

By the production method having such a constitution, 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.

The preferable addition amount of the components (A) to (C) is
For monomer (styrene + butadiene etc.) (A)
The component is monomer / (A) = 10 ² to 10 ⁵ (molar ratio). The ratio of (A) / (B) is 1 / 0.1 to 1 when an organoaluminum compound is used as the component (B).
/ 1000 (molar ratio) is preferable, and when aluminoxane is used as the component (B), it is 1/10.
It is preferably ˜1 / 5000. Also (A) /
The ratio of (C) is preferably 1 / 0.1 to 1/10.

In the above invention, the SBR obtained is obtained.
However, it is preferable that the weight average molecular weight is 200,000 or more and the cis 1,4-bond fraction is 60% or more.

When the weight average molecular weight is 200,000 or more, SBR having a high mechanical strength is obtained when it is used as a rubber molded product, and the cis 1,4-bond fraction is 60% or more. When used as a red material, SBR having excellent wear resistance and low rolling resistance can be obtained.

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.

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 butadiene constituting the polymer is 100%. (%). The cis 1,4-bond fraction of the present invention is measured by an infrared absorption spectrum method.

The method for producing a styrene-butadiene rubber of the present invention is preferably solution polymerization in which a polymerization reaction is carried out in an organic solvent.

Solution polymerization can easily produce a high molecular weight styrene-butadiene rubber.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, at least one selected from (A) a metallocene complex of a transition metal compound, (B) an organoaluminum compound and an aluminoxane.
SBR is obtained by copolymerizing styrene and butadiene using the compound of the kind and the electron-withdrawing compound (C).

(A) Metallocene type complex of transition metal compound
Are known compounds of transition metal compounds of Groups 4 to 8 of the periodic table.
Talocene-type complexes can be used. Specifically, titanium, di
Metallocene type of Group 4 transition metals such as ruconium
Complex (eg CpTiCl ₃ Etc.), vanadium, ni
Metalloces of transition metals of Group 5 of the periodic table, such as bromine and tantalum
Group-type complexes, Group 6 transition metal metallocene-type complexes such as chromium
Metals of Group 8 transition metals such as body, cobalt and nickel
Examples thereof include sen-type complexes.

Of these, the use of a metallocene type complex of a transition metal of Group 5 of the periodic table is preferable. Examples of the metallocene-type complex of a transition metal compound of Group 5 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, and a is 0, 1 or 2) Among the above compounds, (1) RM · L _a , (4 ) RM
It is more preferable to use X ₃ · L _a and (5) RM (O) X ₂ · L _a . The metal M is preferably at least one of vanadium and titanium.

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. The substituent in the substituted cyclopentadienyl group, the substituted indenyl group or the substituted fluorenyl group is methyl, ethyl, propyl, i-propyl, n-butyl, i-butyl, sec-
Butyl, t-butyl, hexyl and other straight-chain aliphatic hydrocarbon groups or branched aliphatic hydrocarbon groups, phenyl, tolyl, naphthyl, aromatic hydrocarbon groups such as benzyl, hydrocarbons containing silicon atoms such as trimethylsilyl Groups and the like. In addition, the cyclopentadienyl ring is part of X and dimethylsilylene (Me ₂ Si), dimethylmethylene (Me ₂ C), methylphenylmethylene (P
hMeC), diphenylmethylene (Ph ₂ C), ethylene, and those bonded by a cross-linking group such as substituted ethylene are also included.

Specific examples of the substituted cyclopentadienyl group include methylcyclopentadienyl group, 1,2-dimethylcyclopentadienyl group, 1,3-dimethylcyclopentadienyl group, 1,2,3- Trimethylcyclopentadienyl group, 1-benzyl-2,3,4,5-tetramethylcyclopentadienyl group, 1-trimethylsilyl-
2,3,4,5-tetramethylcyclopentadienyl group and the like can be mentioned.

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 can be mentioned. Specific examples of the substituted fluorenyl group include a methylfluorenyl group and the like.

Among the Rs exemplified above, a cyclopentadienyl group, a methylcyclopentadienyl group, a pentamethylcyclopentadienyl group, an indenyl group, 1,2,
More preferred is the use of a 3-trimethylindenyl group.

In the general formulas (1) to (6), X is hydrogen, halogen (F, Cl, Br, I), and has 1 to 2 carbon atoms.
0 represents a hydrocarbon group, 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:
A linear or branched aliphatic hydrocarbon group such as methyl, ethyl, propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, hexyl, phenyl, tolyl, An aromatic hydrocarbon group such as naphthyl and benzyl. Among these, methyl,
Benzyl and the like are preferable. R may be a trimethylsilylmethyl group.

Examples of the alkoxy group include alkyloxy groups such as methoxy, ethoxy, phenoxy, propoxy and butoxy. Examples of the amino group include dimethylamino, diethylamino, diisopropylamino and the like.

In the general formulas (1) to (6), L is a Lewis base, which is a general Lewis basic inorganic or organic compound capable of coordinating with a metal. Compounds having no active hydrogen are particularly preferable, and specific examples thereof include ethers, esters, ketones, amines, phosphines, silyloxy compounds, olefins, dienes, aromatic compounds and alkynes.

In the general formula (6), R _n MX _3-n (NR ′), NR ′ is an imide group, and R ′ has 1 to 25 carbon atoms.
Is a hydrocarbon substituent. Specific examples of R'include methyl, ethyl, propyl, i-propyl, n-butyl, i.
-Butyl, sec-butyl, t-butyl, hexyl, octyl, neopentyl and other straight-chain aliphatic hydrocarbon groups or branched aliphatic hydrocarbon groups, phenyl, naphthyl, benzyl, 1-phenylethyl, 6-dimethylphenyl And aromatic hydrocarbon groups such as It may be an alkylsilyl group such as trimethylsilyl.

RM · L _{a of} the general formula (1), that is, the transition metal compound of Group 5 of the periodic table having a cycloalkadienyl group ligand and an oxidation number of +1 includes cyclopentadienyl (benzene) vanadium, Cyclopentadienyl (toluene) vanadium, cyclopentadienyl (xylene) vanadium, cyclopentadienyl (ferrocene)
Vanadium, tetramethyl cyclopentadienyl (benzene) vanadium, indenyl (benzene) vanadium, cyclopentadienyl tetracarbonyl vanadium, etc. can be mentioned.

Among the compounds represented by the general formula (2) R _n MX _2-n · L _a , when n = 1, that is, when one cycloalkadienyl group is used as a ligand, another sigma bond is used. As a hydrogen atom, a halogen atom such as chlorine,
Methyl group, phenyl group, benzyl group, neopentyl group,
It may have a hydrocarbon group such as a trimethylsilyl group, an alkoxy group such as a methoxy group, an ethoxy group and an isopropoxy group, and a dialkylamino group such as a dimethylamino group and a diisopropylamino group.

Further, as another ligand, a neutral Lewis base such as amine, amide, phosphine, ether, ketone, ester, olefin, diene, aromatic hydrocarbon and alkyne can be contained. Lewis bases without active hydrogen are preferred.

In the compound represented by the general formula (2) R _n MX _2-n · L _a , when n = 2, that is, when two cycloalkadienyl groups are used as ligands, each cycloalkadiene The enyl rings may be linked to each other by a bridging group such as dimethylsilylene, dimethylmethylene, methylphenylmethylene, diphenylmethylene, ethylene and substituted ethylene.

Among the compounds represented by R _n MX _2-n · L _a (2) of the present invention, n = 1 and a specific example of the periodic table group 5 transition metal compound having an oxidation number of +2 is chloro. Cyclopentadienyl (tetrahydrofuran) vanadium,
Chlorocyclopentadienyl (trimethylphosphine)
Examples include vanadium.

(2) Of the compounds represented by R _n MX _2-n · L _a of the present invention, n = 2, that is, the periodic table having an oxidation number of +2 having two cycloalkadienyl groups as ligands. 5
Specific examples of the group transition metal compound include biscyclopentadienyl vanadium, bis (methylcyclopentadienyl) vanadium, and bis (1,2-dimethylcyclopentadienyl) vanadium.

(3) Of the specific compounds represented by R _n MX _3-n · L _a , compounds having n = 1 include cyclopentadienyl vanadium dichloride, methylcyclopentadienyl vanadium dichloride, and fullerene. Examples thereof include dichlorides such as oleyl vanadium dichloride, and methyls obtained by substituting the chlorine atom of these compounds with a methyl group.

(3) Examples of the compound represented by R _n MX _3-n · L _a include cyclopentadienyl vanadium dimethoxide and cyclopentadienyl vanadium dii.
-Propoxide, cyclopentadienyl vanadium dit-butoxide, cyclopentadienyl vanadium diphenoxide, cyclopentadienyl vanadium methoxy chloride, cyclopentadienyl vanadium i-
Examples thereof include alkoxides such as propoxycyclolide, cyclopentadienyl vanadium t-butoxycyclolide, and cyclopentadienyl vanadium phenoxycyclolide, and methyl compounds in which chlorine atoms of these compounds are substituted with methyl groups.

(3) Among the specific compounds represented by R _n MX _3-n · L _a , as the compound of n = 2, dicyclopentadienyl vanadium chloride and bis (methylcyclopentadienyl) Chloride such as vanadium chloride, bis (1,3-dimethylcyclopentadienyl) vanadium chloride, bis (trimethylsilylcyclopentadienyl) vanadium chloride, diindenyl vanadium chloride, or the chlorine atom of these compounds with a methyl group Examples include substituted methyl compounds.

In the compound represented by the general formula (3) R _n MX _3-n · L _a , R may be bonded by a hydrocarbon group or a silyl group. Examples of such compounds include chlorides such as dimethylbis (η5-cyclopentadienyl) silanevanadium chloride and dimethylbis (tetramethyl-η5-cyclopentadienyl) silanevanadium chloride, or chlorine atoms of these compounds in which a methyl group is used. And a methyl form substituted with.

[0038] As a general formula (4) Specific compound represented by RMX ₃ · L _a include compounds of the following (i) ~ (vii).

(I) Cyclopentadienyl vanadium trichloride, mono-substituted cyclopentadienyl vanadium trichloride, cyclopentadienyl titanium trichloride (ii) 1,2- or 1,3-disubstituted cyclopentadienyl vanadium Trichloride, 1,2- or 1,3-
Tri-substituted cyclopenta such as di-substituted cyclopentadienyl titanium trichloride (iii) (1,2,3-trimethylcyclopentadienyl) vanadium trichloride, 1,2,4-trimethylcyclopentadienyl) vanadium trichloride Dienyl vanadium trichloride may be mentioned.

(Iv) tetra-substituted or penta-substituted cyclopentadienyl vanadium trichloride (v) indenyl vanadium trichloride, (vi)
Substituted indenyl vanadium trichloride (vii); monoalkoxides, dialkoxides, trialkoxides etc. in which the chlorine atom of the compounds of (i) to (vi) are substituted with an alkoxy group are represented by the general formula (5) RM (O) X ₂ . Specific examples of the compound include cyclopentadienyloxovanadium dichloride, methylcyclopentadienyloxovanadium dichloride, benzylcyclopentadienyloxovanadium dichloride, (1,3-dimethylcyclopentadienyl) oxovanadium dichloride, etc. Is mentioned. Also included are methyl compounds in which the chlorine atom of each of the above compounds is replaced with a methyl group.

Examples of the compound represented by the general formula (5) RM (O) X ₂ include cyclopentadienyloxovanadium dimethoxide and cyclopentadienyloxovanadium di-propoxide. A methyl form in which the chlorine atom of each of the above compounds is replaced with a methyl group,
(Cyclopentadienyl) bis (diethylamido) oxovanadium, (Cyclopentadienyl) bis (di-
Propylamido) oxovanadium and the like.

Specific examples of the compound represented by the general formula (6) R _n MX _3-n (NR ′) include cyclopentadienyl (methylimido) vanadium dichloride, cyclopentadienyl (phenylimido) vanadium dichloride, Examples thereof include cyclopentadienyl (2,6-dimethylphenylimide) vanadium dichloride.

(6) The compound represented by R _n MX _3-n (NR ′) further includes cyclopentadienyl vanadium (phenylimido) dimethoxide, cyclopentadienyl vanadium (phenylimido) di i-propoxide. Cyclopentadienyl vanadium (phenylimide) (i-propoxy) chloride, (cyclopentadienyl) bis (diethylamido) vanadium (phenylimide), (cyclopentadienyl) bis (di-propylamido) vanadium (phenylimide) ) And the like.

As the organoaluminum compound used as the component (B) in the present invention, known organoaluminum compounds can be used. Specific examples include trialkylaluminum such as trimethylaluminum, triethylaluminum and triisobutylaluminum, and dialkylhalides such as diethylaluminum chloride.

The chain aluminoxane usable as the component (B) is obtained by contacting an organoaluminum compound with a condensing agent, and has a general formula (-Al (R ') O-). The chain | strand-shaped aluminoxane shown by n is mentioned. 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 methyl, ethyl, propyl and isobutyl groups. Of these, a methyl group and an ethyl group are preferable. Examples of the organoaluminum compound used as a raw material for the aluminoxane include the above-mentioned trialkylaluminums such as trimethylaluminum, triethylaluminum and triisobutylaluminum, and mixtures thereof.

Typical examples of the condensing agent used for producing the chain aluminoxane include water, but in addition to this, any condensing agent with which the trialkylaluminum undergoes a condensation reaction, for example, adsorbed water such as an inorganic substance, or geo- -Ru and the like.

As the electron-withdrawing compound (C) of the present invention, known electron-withdrawing compounds can be used. Specific examples thereof include acetic acid derivatives such as trichloroacetic acid and trifluoroacetic acid, tetrachlorobenzoquinone (chloranil), benzoquinone derivatives such as tetrafluorobenzoquinone, and tetracyanoquinodimethane (TCNQ). These electron-withdrawing compounds may be used alone or in combination of two or more kinds.

In the method for producing SBR of the present invention, styrene and butadiene are used as monomers,
Copolymerization with other monomers within a range that does not impair the properties of the SBR obtained is a preferred embodiment from the viewpoint of improving the properties. Such other copolymerizable monomers include isoprene, 1,3-pentadiene, 2,3
-Conjugated diene monomers such as dimethyl butadiene, 2,4-hexadiene, 4-methyl pentadiene, ethylene,
Examples include monoolefins such as propylene, butene-1, butene-2, isobutene, pentene-1, hexene-1 and octene-1, cyclic monoolefins such as norbornene, and aromatic monoolefins such as α-methylstyrene. .

As the solvent used in the method for producing a styrene-butadiene rubber of the present invention, any known solvent used in the polymerization of styrene-butadiene rubber can be used without limitation. Specifically, aromatic solvents such as toluene, xylene and tetralin, and aliphatic or alicyclic solvents such as n-hexane, n-pentane, n-heptane, cyclohexane, cyclopentane, cycloheptane and decalin. Is exemplified as a suitable solvent.

As a polymerization method for producing SBR, a known method can be used. The polymerization may be either solution polymerization or bulk polymerization, but is preferably solution polymerization as described above.

The solution polymerization method is carried out, for example, by charging an organic solvent, a styrene monomer and a butadiene monomer in a predetermined ratio into a reaction vessel, adjusting the temperature to a predetermined temperature, and adding a catalyst.

The polymerization temperature is about -10 ° C to 150 ° C, more preferably 0 to 120 ° C. The polymerization time is appropriately set depending on the temperature and the target molecular weight, but is about 3 minutes to 10 hours.

The polymerization reaction is stopped by adding a solvent such as alcohol or a solvent containing an inhibitor to the polymerization system and stirring. After the completion of the polymerization, the SBR can be obtained by, for example, reprecipitating the solution in a non-solvent of SBR, filtering and then drying, or removing the solvent from the solution after the polymerization.

[0054]

EXAMPLES 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 was used as a solvent, and cyclopentadienyl titanium trichloride (CpTiCl 2).
₃ ) 2.1 mmol, methylaluminoxane (MA
O) 210 mmol, chloranil 2.1 mmol
(CpTiCl ₃ / chloranil = 1/1 (molar ratio)) was charged, and 37.5 ml of butadiene and 37.5 ml of styrene.
Was added and polymerization was carried out at 60 ° C. for 30 minutes. 10 minutes after the initiation of the polymerization, a methanol solution in which a small amount of pt-butylcatechol as a polymerization inhibitor was dissolved was added to the polymerization solution,
The polymerization reaction was stopped. By removing toluene from this solution, an SBR polymer was obtained.

Example 2 The amount of chloranil added was 21 m.
An SBR polymer was obtained in the same manner as in Example 1 except that mol (CpTiCl ₃ / chloranil = 1/10 (molar ratio)) was used.

Comparative Example 1 An SBR polymer was obtained in the same manner as in Example 1 except that chloranil was not added.

Comparative Example 2 As a catalyst component, n-butyllithium 3 was used instead of the components (A) to (C) of the present invention.
1.2 mmol and tetrahydrofuran 31.2 mmol
SBR as in Example 1 except that the mixture of
A polymer was obtained.

<Evaluation> (Measurement of molecular weight) GPC LC-10 (manufactured by Shimadzu Corporation)
Tetrahydrofuran (THF) as mobile phase
Was used to measure the weight average molecular weight and number average molecular weight in terms of standard polystyrene.

(Microstructure) cis 1,4-bond fraction,
The 1,2-bond fraction was measured by infrared absorption spectroscopy. Paragon 1000 (manufactured by Perkin Elmer) was used for the measurement. The measurement was performed by the transmission method. The result is 7 attributed to the cis 1,4-bond of the butadiene unit.
Absorption intensity of 35 cm ^-1, the absorption intensity of 967 cm ^-1 attributed to trans 1,4-bonds, the absorption intensity of 911 cm ^-1 attributed to 1,2-bonds were measured, it was determined from the intensity ratio .

The evaluation results are shown in Table 1. From the results in this table, the SBR according to the present invention has a weight average molecular weight of 36.
5,000 (Example 1), 431,000 (Example 2)
It has a high molecular weight and has a cis 1,4-bond fraction of 60% or more. On the other hand, the SBR of Comparative Example 1 in which the electron-withdrawing compound (structure (C)) is not used
Has a cis 1,4-bond ratio of 62.2% but a low weight average molecular weight of 35,000, and the SBR of Comparative Example 2 has a high weight average molecular weight of 223,000,
The cis 1,4-bond fraction was as low as 22.5%.

[0061]

[Table 1]

Continued front page    F-term (reference) 4J100 AB02Q AS02P CA04 CA15                       DA01 DA04 FA10 JA29                 4J128 AA01 AB00 AB01 AC10 AC28                       AC31 AC39 AC42 AC47 AC48                       AD01 AD02 AD05 AD06 AD16                       AD19 AE01 AE05 BA00A                       BA01B BB00A BB01B BC15B                       BC16B BC25B CB53C CB54C                       CB68C EA01 EB13 EB21                       EC02 FA02 GA01 GA06 GA11

Claims (4)

[Claims] 1. A transition metal metallocene catalyst (A), (B)
A method for producing a styrene-butadiene rubber, which comprises adding at least one compound selected from an organoaluminum compound and an aluminoxane, and (C) an electron-withdrawing compound to copolymerize styrene and butadiene. 2. 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. 3. The method for producing a styrene-butadiene rubber according to claim 1, wherein the polymerization reaction is carried out in an organic solvent. 4. A weight average molecular weight of 200,000 or more and cis 1,
Styrene-butadiene rubber having a 4-bond content of 60% or more.