JP2010261027A - Branched conjugated diene-aromatic vinyl copolymer and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a branched conjugated diene-aromatic vinyl copolymer, of which the processability when processed into a vulcanizate is good and the vulcanizate has satisfying low hysteresis loss while exhibiting excellent wet skid resistance, thereby having an excellent balance between them, satisfies practically sufficient abrasion resistance and destructive characteristics, and further has excellent productivity, and a method for producing the same. <P>SOLUTION: The conjugated diene-aromatic vinyl copolymer (C) is a random copolymer. A bonding amount of the aromatic vinyl in the conjugated diene-aromatic vinyl copolymer (C) is 38-45 mass%, and a bonding amount of vinyl in the total bonding units of the conjugated diene is more than 43 mol% and equal to or less than 50 mol%. A weight-average molecular weight (Mw-C) of the conjugated diene-aromatic vinyl copolymer (C) is 700,000-1,000,000, and a ratio of the weight-average molecular weight (Mw-C) to a number-average molecular weight (Mn-C), ((Mw-C)/(Mn-C)), is 1.7-3.0. Mooney viscosity (ML-C) and Mooney relaxation rate (MSR-C) measured at 120°C satisfy relation in formula (1): ä195-(ML-C)}/300≤(MSR-C)≤ä235-(ML-C)}/300, wherein 90≤(ML-C)≤125. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a branched conjugated diene-aromatic vinyl copolymer and a method for producing the same.

  From the viewpoint of ensuring safety, it is important for automobile tires to use materials having excellent wet skid resistance and practically sufficient wear resistance and fracture characteristics. On the other hand, in recent years, environmental considerations such as the suppression of carbon dioxide emissions have become social demands, and the demand for lower fuel consumption for automobiles has also increased. Under such circumstances, the development of a material with low rolling resistance is required as a material for automobile tires, particularly tire treads in contact with the ground.

  In addition, from the viewpoint of the life cycle of a tire, there is an increasing interest in reducing energy consumption in the manufacturing process, and there is a demand for a rubber material having low energy consumption during compound kneading and good workability. Furthermore, in the production of raw synthetic rubber, it has been demanded that productivity is good and energy consumption is reduced.

  Styrene-butadiene rubber (SBR) is known as one of main materials for tire treads. The polymerization method of SBR includes emulsion polymerization SBR (E-SBR) in which a monomer suspended in water is radically polymerized, and solution polymerization SBR (S-BR) in which a monomer in a hydrocarbon solvent is anionically polymerized using an organic alkali metal. -SBR). Among these, the degree of freedom of polymer structure design is high, and the amount of solution polymerization SBR (S-SBR) used is particularly excellent in the balance between fuel saving performance and wet skid resistance in a tire using silica as a filler. Has increased.

  The polymerization process of solution polymerization SBR (S-SBR) is roughly classified into two types, a batch polymerization process and a continuous polymerization process.

  In the batch polymerization process, a functional group can be introduced relatively easily by adding a modifier to the active terminal of the polymer, and a rubber having a low rolling resistance when obtained as a tire tread material is obtained (for example, see Patent Document 1). .) On the other hand, due to the narrow molecular weight distribution and the bonding between the modifying group and a filler such as silica, the viscosity increases during kneading, so the processability is poor. Has the disadvantage of increasing energy consumption.

  On the other hand, in the continuous polymerization process, the heat generated by the exothermic reaction of the polymerization can also perform the heating necessary for the initiation and promotion of the polymerization, so the amount of energy used per production amount is less than that of the batch polymerization process. Since the molecular weight distribution is also widened, there is an advantage that processability is relatively good. However, solution-polymerized SBR (S-SBR) consumes a large amount of energy during compound kneading when producing a composition and processability compared to emulsion-polymerized SBR (E-SBR), which can branch a large amount during polymerization. Have the disadvantage of being inferior.

  Other techniques include, for example, a method of coupling a conjugated diene-aromatic vinyl copolymer that has been anionically polymerized by a continuous polymerization process with a trifunctional or higher functional silicon coupling agent such as silicon tetrachloride (see, for example, Patent Document 2). .), A method of coupling with a halogen-containing silicon compound, an alkoxysilane compound, an alkoxysulfide compound, etc. (see, for example, Patent Document 3), a method of coupling with a compound having two or more epoxy groups (for example, Patent Document) 4).

JP 2003-171418 A Japanese Patent Application Laid-Open No. 61-255917 JP-A-11-199712 International Publication No.01 / 23467

  However, it has good processability when used as a vulcanized product, has an excellent balance between low hysteresis loss and wet skid resistance when used as a vulcanized product, and has practically sufficient wear resistance and fracture characteristics. However, there is still room for improvement in order to obtain a conjugated diene-aromatic vinyl copolymer having both of these.

  Moreover, since all of the methods disclosed in Patent Documents 2 to 4 require polymerization under relatively low temperature conditions in order to obtain a high coupling rate, there is still room for improvement in productivity.

  The present invention has been made in view of the above circumstances, and has good processability when used as a vulcanizate, and when used as a vulcanizate, it exhibits excellent wet skid resistance and low hysteresis loss. The present invention provides a branched conjugated diene-aromatic vinyl copolymer that is excellent in balance between the two, satisfies practically sufficient wear resistance and fracture characteristics, and also has excellent productivity, and a method for producing the same. For the purpose.

  As a result of intensive studies to solve the above problems, the present inventor has found that the amount of aromatic vinyl bonds, the amount of vinyl bonds in all conjugated diene units, the weight average molecular weight (Mw-C), and the weight average molecular weight (Mw). -C) / number average molecular weight (Mn-C) is in a specific numerical range, and Mooney viscosity (ML-C) and Mooney relaxation rate (MSR-C) measured at 120 ° C. have a specific relational expression. The present inventors have found that the above problems can be solved by satisfying a branched conjugated diene-aromatic vinyl copolymer, and have completed the present invention.

That is, the present invention is as follows.
[1]
A random copolymer, a conjugated diene-aromatic vinyl copolymer (C),
The aromatic vinyl bond content in the conjugated diene-aromatic vinyl copolymer (C) is 38 to 45% by mass,
The vinyl bond amount in the conjugated diene total bond unit is more than 43 mol% and 50 mol% or less,
The conjugated diene-aromatic vinyl copolymer (C) has a weight average molecular weight (Mw-C) of 700,000 to 1,000,000,
The ratio of the weight average molecular weight (Mw-C) to the number average molecular weight (Mn-C) ((Mw-C) / (Mn-C)) is 1.7 to 3.0,
A branched conjugated diene-aromatic vinyl copolymer (C) in which the Mooney viscosity (ML-C) and Mooney relaxation rate (MSR-C) measured at 120 ° C. satisfy the relationship of the following formula (1).

{195- (ML-C)} / 300 ≦ (MSR-C) ≦ {235- (ML-C)} / 300 (1)
(Here, 90 ≦ (ML−C) ≦ 125 in the formula (1)).
[2]
The weight average molecular weight (Mw-I) is 500,000 to 700,000, and the Mooney viscosity (ML-I) and Mooney relaxation rate (MSR-I) measured at 120 ° C. are represented by the following formula (2). The branched conjugated diene-fragrance according to claim 1, wherein the conjugated diene-aromatic vinyl copolymer (I) satisfying the above is coupled using a polyfunctional modifier having four or more functional groups. Group vinyl copolymer (C).

{235- (ML-I)} / 300 ≦ (MSR-I) ≦ {270- (ML-I)} / 300 (2)
(Here, in formula (2), 60 ≦ (ML−I) ≦ 90)
[3]
The branched conjugated diene-aromatic vinyl copolymer (C) according to [1] or [2],
An inorganic filler;
A branched conjugated diene-aromatic vinyl copolymer composition comprising:
[4]
A method for producing the branched conjugated diene-aromatic vinyl copolymer (C) according to [1] or [2],
A solution containing a conjugated diene compound, an aromatic vinyl compound, and an anionic polymerization initiator is continuously supplied to the reactor to advance the polymerization reaction, thereby obtaining a solution of a conjugated diene-aromatic vinyl copolymer having an active end. Process,
Coupling the conjugated diene-aromatic vinyl copolymer using a polyfunctional modifier having four or more functional groups capable of reacting with the active terminal;
The manufacturing method of the branched conjugated diene-aromatic vinyl copolymer (C) which has these.
[5]
A method for producing the branched conjugated diene-aromatic vinyl copolymer (C) according to [1] or [2],
A step of continuously supplying a solution containing a conjugated diene compound, an aromatic vinyl compound, and an anionic polymerization initiator to a reactor equipped with a stirrer to advance the polymerization reaction;
Continuously obtaining a solution of a conjugated diene-aromatic vinyl copolymer having an active end from the outlet of the reactor;
Coupling the conjugated diene-aromatic vinyl copolymer with a polyfunctional modifier having four or more functional groups capable of reacting with the active terminal;
Have
In the polymerization reaction, a branched conjugated diene-aromatic vinyl copolymer that keeps the internal temperature at the outlet of the reactor at 90 to 100 ° C. and continuously proceeds the polymerization reaction with an average residence time of 20 minutes to 40 minutes. The manufacturing method of (C).
[6]
The polyfunctional modifier is used such that the total number of functional groups of the polyfunctional modifier is 0.1 to 0.5 times the number of moles of the anionic polymerization initiator [4] or The method for producing the branched conjugated diene-aromatic vinyl copolymer (C) according to [5].

  According to the present invention, the workability when making a vulcanizate is good, and the vulcanizate shows excellent wet skid resistance while also having a low hysteresis loss and an excellent balance between the two. In addition, it is possible to provide a branched conjugated diene-aromatic vinyl copolymer and a method for producing the same, which also satisfy sufficient wear resistance and fracture characteristics, and which are excellent in copolymer productivity.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. The following embodiment is an exemplification for explaining the present invention, and the present invention is not limited to the embodiment shown below. The present invention can be appropriately modified and implemented within the scope of the gist.

[Branched Conjugated Diene-Aromatic Vinyl Copolymer]
The branched conjugated diene-aromatic vinyl copolymer (C) of this embodiment is
A random copolymer, a conjugated diene-aromatic vinyl copolymer (C),
The aromatic vinyl bond content in the conjugated diene-aromatic vinyl copolymer (C) is 38 to 45% by mass,
The vinyl bond amount in the conjugated diene total bond unit is more than 43 mol% and 50 mol% or less,
The conjugated diene-aromatic vinyl copolymer (C) has a weight average molecular weight (Mw-C) of 700,000 to 1,000,000,
The ratio of the weight average molecular weight (Mw-C) to the number average molecular weight (Mn-C) ((Mw-C) / (Mn-C)) is 1.7 to 3.0,
Mooney viscosity (ML-C) measured at 120 ° C. and Mooney relaxation rate (MSR-C) satisfy the relationship of the following formula (1).

{195- (ML-C)} / 300 ≦ (MSR-C) ≦ {235- (ML-C)} / 300 (1)
(Here, 90 ≦ (ML−C) ≦ 125 in the formula (1)).

  The branched conjugated diene-aromatic vinyl copolymer (C) of this embodiment is a random copolymer. Here, the random copolymer refers to those having little or no component having an aromatic vinyl chain length of 30 or more.

  The branched conjugated diene-aromatic vinyl copolymer in the present embodiment is not limited as long as it is a random copolymer of a conjugated diene compound and an aromatic vinyl compound. As the conjugated diene compound and the aromatic vinyl compound, compounds described later can be appropriately used. As the conjugated diene-aromatic vinyl copolymer, a styrene-butadiene copolymer, a styrene-isoprene copolymer, and a styrene-butadiene isoprene copolymer are preferable, and a styrene-butadiene copolymer is more preferable.

  For example, when the branched conjugated diene-aromatic vinyl copolymer is a butadiene-styrene copolymer, the method described in Kolthoff's method (IM KOLTHOFF, et al., J. Polym. Sci. 1, 429 (1946)). According to the method of decomposing a branched conjugated diene-aromatic vinyl copolymer (C) and analyzing the amount of polystyrene insoluble in methanol, the branched conjugated diene-aromatic vinyl copolymer (C ) Is preferably 5% by mass or less, and more preferably 3% by mass or less.

  According to the method of decomposing the branched conjugated diene-aromatic vinyl copolymer (C) by ozonolysis and analyzing the styrene chain distribution by gel permeation chromatography (GPC), isolated styrene (ie, It is preferable that styrene having a styrene unit chain of 1) is 40% by mass or more of the total bonded styrene, and long-chain block styrene (that is, styrene having 8 or more styrene unit chains) is 5% by mass or less of the total bonded styrene. It is more preferable that

  The amount of aromatic vinyl bonds in the branched conjugated diene-aromatic vinyl copolymer of this embodiment is 38 to 45% by mass, preferably 39 to 43% by mass. The amount of aromatic vinyl bonds can be determined by measuring the ultraviolet absorption of the phenyl group of the branched conjugated diene-aromatic vinyl copolymer (C).

  Moreover, the vinyl bond amount in the conjugated diene total bond unit exceeds 43 mol% and is 50 mol% or less, Preferably it is 44-48 mol%. For example, when the branched conjugated diene-aromatic vinyl copolymer (C) is a butadiene-styrene copolymer, it is described in the method of Hampton (RR Hampton, Analytical Chemistry 21, 923 (1949)). Method) can determine the vinyl bond amount (1,2-bond amount) in the butadiene bond unit.

  The conjugated diene-aromatic vinyl copolymer is generally mixed with natural rubber, butadiene rubber or the like to be further vulcanized, but each of the branched conjugated diene-aromatic vinyl copolymer (C) is often used. When the bond is in the above range, the rubber can be mixed with a good balance without being too compatible with the rubber or separated. Thereby, the vulcanizate excellent in the balance of low hysteresis loss property and wet skid resistance is obtained.

  The glass transition temperature of the branched conjugated diene-aromatic vinyl copolymer (C) of the present embodiment is preferably -20 to -5 ° C, more preferably -18 to -8 ° C. When the glass transition temperature is in this range, a vulcanizate that exhibits excellent wet skid resistance and good low hysteresis loss can be obtained. Regarding the glass transition temperature, in accordance with ISO 22768: 2006, a DSC curve is recorded while raising the temperature in a predetermined temperature range, and the peak top (Inflection point) of the DSC differential curve is defined as the glass transition temperature.

  As described above, the branched conjugated diene-aromatic vinyl copolymer of the present embodiment has a polystyrene-equivalent weight average molecular weight (Mw-C) of 700,000 to 1,000,000, preferably 750, 000 to 950,000. In order to obtain good wear resistance and strength, it is 700,000 or more, and in order to maintain good workability, it is 1,000,000 or less.

  The ratio of the weight average molecular weight (Mw-C) to the number average molecular weight (Mn-C) ((Mw-C) / (Mn-C)) is 1.7 to 3.0, preferably 2. 0-2.8. In order to obtain good workability, it is 1.7 or more, and in order to obtain good mechanical properties, it is 3.0 or less. The molecular weight and molecular weight distribution can be calculated by measuring the chromatogram using GPC and determining the molecular weight using a calibration curve using standard polystyrene.

The Mooney viscosity (ML-C) and Mooney relaxation rate (MSR-C) measured at 120 ° C. of the branched conjugated diene-aromatic vinyl copolymer (C) of this embodiment are represented by the following formula (1). Meet.

{195- (ML-C)} / 300 ≦ (MSR-C) ≦ {235- (ML-C)} / 300 (1)
(Here, 90 ≦ (ML−C) ≦ 125 in the formula (1)).

  The Mooney relaxation rate (MSR) is the torque (T) and time (t (t ()) from 1.6 seconds to 5 seconds after the rotor is stopped after measuring the Mooney viscosity by the method specified in ISO 289-4: 2003. Second)) and the logarithmic plot of the absolute value of the slope. When the Mooney viscosities are equal, this value decreases as the number of branches increases, and can be used as an index of the degree of branching. Specifically, it can be determined by the method described in Examples described later. The Mooney viscosity and Mooney relaxation rate are usually measured at 100 ° C., but in this embodiment, the Mooney viscosity and Mooney relaxation rate measured at 120 ° C. are employed.

  In Formula (1), when it has a sufficient degree of branching so as to be not more than the above upper limit value, it is excellent in workability, excellent in the balance between low hysteresis loss property of vulcanizate and wet skid resistance, and practically sufficient. Satisfies wear resistance and fracture characteristics. The higher the degree of branching and the lower the MSR-C, the better the workability, and the better the balance between the low hysteresis loss of the vulcanizate and the wet skid resistance. Therefore, productivity is lowered, which is not preferable for practical use.

  When the present inventor examined the behavior of the conjugated diene-aromatic vinyl copolymer, it has the same microstructure (the amount of aromatic vinyl bonds and the amount of vinyl bonds in the conjugated diene bond unit), and is in the same branched state. In the case of a copolymer, when ML-C of a copolymer having a changed molecular weight is plotted on the X axis and MSR-C is plotted on the Y axis, (MSR-C / ML-C) has a slope of -1/300. We found that it can be approximated. Further, when the branching state is changed by changing the polymerization temperature or changing the blending amount of the multibranching modifier, etc., the plotted straight line moves up and down (the slope is −1/300). It was found that only the Y intercept fluctuates while maintaining. From these findings, the MSR-C and ML-C of the conjugated diene-aromatic vinyl copolymer (C) can define a suitable branched state by satisfying the condition of the formula (1), and the vinyl bond amount and weight Processing to obtain a vulcanizate by controlling the average molecular weight (Mw-C) and the ratio of the weight average molecular weight to the number average molecular weight ((Mw-C) / (Mn-C)) within a specific range. When it is made into a vulcanizate, it has a good balance between low hysteresis loss and wet skid resistance, satisfies practically sufficient wear resistance and fracture characteristics, and is produced. It has been found that it can be made into a copolymer having excellent properties.

Furthermore, the relationship between ML-C and MSR-C preferably satisfies the following formula (1a). By satisfying the following formula (1a), the effect of the above-described embodiment becomes more remarkable.

{208- (ML-C)} / 300 ≦ (MSR-C) ≦ {222- (ML-C)} / 300 (1a)
(Here, 97 ≦ (ML−C) ≦ 110 in the formula (1a).)

  The branched conjugated diene-aromatic vinyl copolymer (C) of this embodiment is obtained by coupling a conjugated diene-aromatic vinyl copolymer using a polyfunctional modifier having 4 or more functional groups. It is preferable that As a result, the degree of branching and molecular weight can be effectively increased, the copolymer productivity and the processability when making a vulcanized product are good, and the copolymer has an excellent balance of vulcanized product performance. can do.

Furthermore, the branched conjugated diene-aromatic vinyl copolymer (C) of the present embodiment has a polystyrene equivalent weight average molecular weight (Mw-I) obtained by GPC of 500,000 to 700,000. The conjugated diene-aromatic vinyl copolymer (I) having a Mooney viscosity (ML-I) and Mooney relaxation rate (MSR-I) measured at 120 ° C. satisfying the relationship of the following formula (2): Is more preferable. As a result, the processability when vulcanized is good, and when vulcanized, the balance between low hysteresis loss and wet skid resistance is excellent, and practically sufficient wear resistance. In addition, it can be a copolymer that also satisfies fracture characteristics and is excellent in productivity.

{235- (ML-I)} / 300 ≦ (MSR-I) ≦ {270- (ML-I)} / 300 (2)
(Here, in formula (2), 60 ≦ (ML−I) ≦ 90)

Furthermore, the Mooney viscosity (ML-I) measured at 120 ° C. and the Mooney relaxation rate (MSR-I) measured at 120 ° C. preferably satisfy the relationship of the following formula (2a).

{241- (ML-I)} / 300 ≦ (MSR-I) ≦ {256- (ML-I)} / 300 (2a)
(Here, in formula (2a), 68 ≦ (ML−I) ≦ 79).

[Method for producing branched conjugated diene-aromatic vinyl copolymer (C)]
A preferred method for producing the branched conjugated diene-aromatic vinyl copolymer (C) of the present embodiment is as follows:
A solution containing a conjugated diene compound, an aromatic vinyl compound, and an anionic polymerization initiator is continuously supplied to the reactor to advance the polymerization reaction, thereby obtaining a solution of a conjugated diene-aromatic vinyl copolymer having an active end. Process,
Coupling the conjugated diene-aromatic vinyl copolymer with a polyfunctional modifier having four or more functional groups capable of reacting with the active terminal;
Have

As a more preferable production method of the branched diene-aromatic vinyl copolymer (C) of the present embodiment,
A step of continuously supplying a solution containing a conjugated diene compound, an aromatic vinyl compound and an anionic polymerization initiator to a reactor equipped with a stirrer to advance the polymerization reaction;
Continuously obtaining a solution of a conjugated diene-aromatic vinyl copolymer having an active end from the outlet of the reactor;
Coupling with a polyfunctional modifier having 4 or more functional groups capable of reacting with the active end;
Have

  According to the manufacturing method described above, the processability when vulcanized is good, and when vulcanized, the balance between low hysteresis loss and wet skid resistance is excellent and practically sufficient. The branched conjugated diene-aromatic vinyl copolymer (C) of the present embodiment that can satisfy satisfactory wear resistance and fracture characteristics can be produced efficiently. For example, in the past, an internal mixer such as a Banbury mixer has been used to knead the compound containing SBR described above, but a small-capacity mixer (for example, a capacity of several liters or less) used at the laboratory level is used. Compared with the case of using a mixer having a large capacity (for example, a capacity of several hundred liters or more) used in the manufacturing process of rubber products such as tires, the kneading processability is greatly reduced. Therefore, the problem of workability becomes more remarkable. As a result, there is a tendency that the viscosity of the compound increases and the skin and edges of the compound fabric become rough. Since the manufacturing method of the present embodiment can maintain excellent processability even when scaled up in this way, the branched conjugated diene-aromatic vinyl copolymer is efficiently produced without causing the above-described problems. (C) can be manufactured.

(Conjugated diene compounds)
It does not specifically limit as a conjugated diene compound used for manufacture of the branched conjugated diene-aromatic vinyl copolymer (C) of this embodiment, For example, 1,3-butadiene, isoprene, 2,3-dimethyl- Examples include 1,3-butadiene, 1,3-pentadiene, 3-methyl-1,3-pentadiene, 1,3-heptadiene, 1,3-hexadiene, and the like. These may be used alone or in combination of two or more. Among these, 1,3-butadiene and isoprene are preferable from the viewpoint of availability and economy.

(Aromatic vinyl compound)
Examples of the aromatic vinyl compound used in the production of the branched conjugated diene-aromatic vinyl copolymer (C) of the present embodiment include styrene, p-methylstyrene, α-methylstyrene, vinylethylbenzene, vinylxylene, Examples include vinyl naphthalene and diphenylethylene. These may be used alone or in combination of two or more. Among these, styrene is preferable.

  Allenes and acetylenes, which may be contained as impurities in the conjugated diene compound and aromatic vinyl compound, are an inhibiting factor in the polymerization reaction and coupling reaction, so the concentration in all monomers is less than 200 ppm. It is preferable.

(Polymerization solvent)
In this embodiment, the conjugated diene compound and the aromatic vinyl compound are usually copolymerized in a solvent. The solvent is not particularly limited, and for example, a hydrocarbon solvent such as a saturated hydrocarbon or an aromatic hydrocarbon is used. Specifically, linear and branched aliphatic hydrocarbons such as butane, pentane, hexane and heptane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane and methylcyclohexane; benzene, toluene and xylene And hydrocarbons composed of aromatic hydrocarbons and mixtures thereof.

(Monomer concentration)
In this embodiment, the monomer concentration of the conjugated diene compound and the aromatic vinyl compound in the polymerization solution for performing the polymerization reaction is not particularly limited, but is preferably 5 to 50% by mass, and more preferably 10 to 30% by mass. .

(Anionic polymerization initiator)
The anionic polymerization initiator that can be used in the polymerization reaction of the present embodiment is not particularly limited, and for example, an alkali metal initiator, an alkaline earth metal initiator, and the like can be used. As the alkali metal initiator or alkaline earth metal initiator, any alkali metal initiator or alkaline earth metal initiator capable of initiating polymerization can be used. Among these, it is preferable to include at least one compound of an organic alkali metal compound and an organic alkaline earth metal compound.

  The organic alkali metal compound is not particularly limited, but an organic lithium compound is preferable from the viewpoint of reactivity and the like. As an organic lithium compound, a low molecular weight compound, a solubilized oligomeric organic lithium compound, a compound having a single lithium in a molecule, a compound having a plurality of lithiums in a molecule, and a bonding mode between an organic group and lithium Examples thereof include a compound having a carbon-lithium bond, a compound having a nitrogen-lithium bond, and a compound having a tin-lithium bond.

  Specifically, examples of the monoorganolithium compound include n-butyllithium, sec-butyllithium, tert-butyllithium, n-hexyllithium, benzyllithium, phenyllithium, and stilbenelithium.

  Examples of polyfunctional organolithium compounds include 1,4-dilithiobutane, a reaction product of sec-butyllithium and diisopropenylbenzene, 1,3,5-trilithiobenzene, n-butyllithium, 1,3-butadiene, and divinylbenzene. And a reaction product of n-butyllithium and a polyacetylene compound.

  Examples of the compound having a nitrogen-lithium bond include lithium dimethylamide, lithium diethylamide, lithium dipropylamide, lithium di-n-hexylamide, lithium diisopropylamide, lithium hexamethylene imide, lithium pyrrolidide, lithium piperidide, and lithium heptamethylene. Examples thereof include imide and lithium morpholide.

  Furthermore, organic alkali metal compounds disclosed in US Pat. No. 5,708,092, British Patent 2,241,239, US Pat. No. 5,527,753, etc. can also be used. . Particularly preferred are n-butyllithium and sec-butyllithium. The above-described organolithium compounds may be used alone or in combination of two or more.

Examples of other organic alkali metal compounds include organic sodium compounds, organic potassium compounds, organic rubidium compounds, and organic cesium compounds. Specific examples include sodium naphthalene and potassium naphthalene. In addition, lithium, sodium, potassium alkoxides, sulfonates, carbonates, amides, and the like are used.
The organic alkali metal compound may be used in combination with other organic metal compounds.

  The alkaline earth metal compound is not particularly limited, and examples thereof include organic magnesium compounds, organic calcium compounds, and organic strontium compounds. Specific examples include dibutyl magnesium, ethyl butyl magnesium, propyl butyl magnesium, and the like. Further, alkaline earth metal alkoxides, sulfonates, carbonates, amides and the like can also be used. These organic alkaline earth metal compounds may be used in combination with the above organic alkali metal initiators and other organic metal compounds.

(Polar compound)
In the production method of the branched conjugated diene-aromatic vinyl copolymer (C) of the present embodiment, the purpose of randomly copolymerizing the aromatic vinyl compound with the conjugated diene compound, and the microscopic amount of the conjugated diene part of the copolymer. It is preferable to add a small amount of a polar compound such as a Lewis base for the purpose of using it as a vinylating agent for controlling the structure or for the purpose of improving the polymerization rate.

  Although it does not specifically limit as a polar compound, For example, tetrahydrofuran, diethyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, dimethoxybenzene, 2,2-bis (2-oxolanyl) propane, etc. Ethers of: tertiary amine compounds such as tetramethylethylenediamine, dipiperidinoethane, trimethylamine, triethylamine, pyridine, quinuclidine; potassium tert-amylate, potassium tert-butylate, sodium tert-butylate, sodium amylate Alkali metal alkoxide compounds such as potassium dodecylbenzenesulfonate, sodium dodecylbenzenesulfonate, etc. Metal salts of the machine acid; phosphine compounds such as triphenylphosphine and the like. These polar compounds may be used alone or in combination of two or more.

  The amount of the polar compound used is selected according to the purpose and degree of effect, and is not particularly limited, but is usually 0.01 to 100 mol per 1 mol of alkali metal or alkaline earth metal atom in the anionic polymerization initiator. It is.

  The polar compound can be used in an appropriate amount depending on the desired vinyl bond amount as a regulator of the microstructure of the polymer diene moiety. Thereby, the vinyl bond amount in the conjugated diene total bond unit can be controlled. Many polar compounds also have an effective randomizing effect in the copolymerization of conjugated diene compounds and aromatic vinyl compounds. By using polar compounds, the distribution of aromatic vinyl compounds in the copolymer And the amount of block of the aromatic vinyl compound (for example, the amount of styrene block) can be adjusted.

(Polymerization process)
The polymerization reaction of the conjugated diene compound and the aromatic vinyl compound is carried out by adding the above-described conjugated diene compound, aromatic vinyl compound, anionic polymerization initiator, polymerization solvent, and a small amount of polar compound as necessary to a reactor equipped with a predetermined stirrer. It can carry out by supplying continuously, and it can carry out by making the solution of a conjugated diene-aromatic vinyl copolymer flow out continuously from the exit of a reactor. In addition, the monomer and / or polymerization solvent is brought into contact with the organometallic compound at a stage before being supplied to the reactor by a method as disclosed in JP-A No. 2002-284814, so that the polymerization inhibitory action due to a small amount of impurities is prevented. It can also be activated.

  The supply position of the monomer solution and the outflow position of the copolymer solution are not particularly limited and may be any position of the bottom of the reactor, the top, and any position in between. It is preferable to supply the monomer solution from a close position and to let the copolymer solution flow out from a position close to the top. In general, in anionic copolymerization, a conjugated diene compound is preferentially polymerized over an aromatic vinyl compound, and therefore a part of the conjugated diene compound can be supplied from the upper part of the reactor for the purpose of randomization.

  The polymerization reaction is preferably carried out while maintaining the internal temperature at the reactor outlet at 90 to 100 ° C. and an average residence time of 20 minutes to 40 minutes. Here, the internal temperature at the reactor outlet refers to the temperature of the copolymer solution at the reactor outlet. The internal temperature at the outlet of the reactor is 90 ° C or higher in order to increase the reaction rate, improve productivity, and promote the thermal branching reaction by metalation to form an appropriate branched structure even before the coupling reaction. It is preferable that On the other hand, in order to prevent the coupling reaction from being inhibited by inactivation due to excessive metallation reaction or the like, the temperature is preferably set to 100 ° C. or lower. The internal temperature can be adjusted by heat exchange such as external heat exchange or internal heat exchange, or temperature control of the monomer solution to be supplied.

  Furthermore, the internal temperature at the lower part of the reactor is preferably 3 to 15 ° C. lower than the internal temperature at the reactor outlet. Here, the internal temperature at the lower part of the reactor is a position where 1/3 of the total volume of liquid is immersed in the reactor, and the influence of the flow of the monomer solution supplied to the reactor The temperature measured by a thermometer installed at a position that does not directly receive When the inside of the reactor is in a completely mixed state, the internal temperature at the lower part of the reactor becomes substantially the same as the internal temperature at the outlet of the reactor. On the contrary, in the plug flow state, a larger temperature difference occurs between the internal temperature at the lower part of the reactor and the internal temperature at the reactor outlet. By controlling the stirring state and carrying out the polymerization so that the difference between the internal temperature at the bottom of the reactor and the internal temperature at the outlet of the reactor is in the range of 3 to 15 ° C., an appropriate residence time distribution is generated, The thermal branching reaction of the coalescence can proceed appropriately.

  Further, from the viewpoint of obtaining a conversion ratio of a certain monomer or more and further allowing the thermal branching reaction to proceed sufficiently, the average residence time is preferably set to 20 minutes or more. From the viewpoint of productivity and coupling due to deactivation From the viewpoint of suppressing the influence on the reaction, it is preferably 40 minutes or less.

  The monomer conversion rate at the outlet of the reactor is preferably 95% or higher, more preferably 98% or higher, more preferably 99% or higher. The higher the conversion rate, the better the basic unit, and the less the load on the solvent recovery process, the better the productivity. Here, the conversion rate can be obtained by the method described in Examples described later.

  The polystyrene-reduced weight average molecular weight (Mw-I) obtained by GPC of the conjugated diene-aromatic vinyl copolymer (I) obtained in the polymerization step in the previous step of the coupling step is not particularly limited. , Preferably from 000 to 700,000. From the viewpoint of obtaining good wear resistance and strength, it is preferably 500,000 or more, and from the viewpoint of productivity and workability of the conjugated diene-aromatic vinyl copolymer of the present embodiment obtained after coupling. Therefore, it is preferably 700,000 or less.

Further, the conjugated diene-aromatic vinyl copolymer (I) obtained in the polymerization step in the previous step of the coupling step has a Mooney viscosity (ML-I) and Mooney relaxation rate (MSR-I) measured at 120 ° C. ) Preferably satisfies the relationship of the following formula (2).

{235- (ML-I)} / 300 ≦ (MSR-I) ≦ {270- (ML-I)} / 300 (2)
(Here, in formula (2), 60 ≦ (ML−I) ≦ 90)

  In order that the branched conjugated diene-aromatic vinyl copolymer (C) obtained after coupling has a sufficient degree of branching, in the above formula (2), it is preferable to set the upper limit value or less. In order to secure a sufficient active terminal for the coupling reaction to be performed later, it is preferable to carry out the polymerization reaction so as to be not less than the above lower limit value.

As described above, the polyfunctional modifier having four or more functional groups capable of reacting with the active terminal is added to the solution of the conjugated diene-aromatic vinyl copolymer having the active terminal that has flowed out from the reactor outlet. The branched conjugated diene-aromatic vinyl copolymer of this embodiment is obtained by making it contact and coupling-react.

  The reactor may be a tank reactor with a stirrer similar to the polymerization reactor, a tank reactor with a stirrer smaller than the polymerization reactor, or a static mixer. When the solution of the conjugated diene-aromatic vinyl copolymer and the polyfunctional modifier are sufficiently mixed to obtain a sufficient residence time for the reaction, from this point of view, when a tank reactor with a stirrer is used In the method, the volume of the reactor is preferably 1/20 to 1/5 of the polymerization vessel under turbulent flow conditions.

  Although a residence time is not specifically limited, From the said viewpoint, 1 minute-1 hour are preferable, and 1 minute-15 minutes are more preferable. Although the reaction temperature of a coupling reaction is not specifically limited, From the said viewpoint, 50-110 degreeC is preferable and 70-110 degreeC is more preferable.

(Multifunctional modifier having 4 or more functional groups)
The polyfunctional modifier having 4 or more functional groups that can react with the active end of the conjugated diene-aromatic vinyl copolymer having an active end used in the present embodiment is not particularly limited. Epoxy group, carbonyl group, carboxylic acid ester group, carboxylic acid amide group, acid anhydride group, phosphoric acid ester group, phosphite group, epithio group, thiocarbonyl group, thiocarboxylic acid ester group, dithiocarboxylic acid ester group, A compound having one or more functional groups selected from the group consisting of a thiocarboxylic acid amide group, an imino group, an ethyleneimino group, a halogen group, an alkoxysilyl group, an isocyanate group, a thioisocyanate group, a conjugated diene group, and an arylvinyl group Is mentioned.

  In calculating the number of moles of the functional group, in view of the reactivity with the active end of the conjugated diene-aromatic vinyl copolymer having an active end, an epoxy group, a carbonyl group, an epithio group, a thiocarbonyl group, an imino group , An ethyleneimino group, a halogen group, a conjugated diene group, an arylvinyl group, and an alkoxysilyl group, each alkoxy group is monofunctional as a carboxylic acid ester group, a carboxylic acid amide group, an acid anhydride group, and a thiocarboxylic acid ester group. , Dithiocarboxylic acid ester group, thiocarboxylic acid amide group, isocyanate group and thioisocyanate group are calculated as bifunctional, and phosphoric acid ester group and phosphite group are calculated as trifunctional. The polyfunctional modifier used in the present embodiment has a sum of the functional numbers of the above functional groups in one molecule of 4 or more.

  Examples of the polyfunctional modifier having an epoxy group include polyepoxy compounds such as polyepoxidized liquid polybutadiene; tetraglycidylmetaxylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, tetraglycidyl-1,3- Glycidylamino compounds such as bisaminomethylcyclohexane; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltributoxysilane, epoxidized soybean oil, epoxidized linseed oil, etc. And compounds having an epoxy group and other functional groups.

  Examples of the polyfunctional modifier having an alkoxysilyl group include tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, bis (triethoxysilyl) methane, bis (trimethoxysilyl) ethane, and 1,6-bis (trimethoxy). Silyl) hexane, bis (triethoxysilyl) octane, bis (triethoxysilyl) ethylene, 1,1-bis (trimethoxysilylmethyl) ethylene, 1,4-bis (triethoxysilyl) benzene, bis (3-tri Alkoxysilane compounds such as methoxysilylpropyl) -N-methylamine, N- (1,3-dimethylbutylidene) -3- (triethoxysilyl) -1-propanamine, N- (1,3-dimethylbutylidene ) -3- (Tributoxysilyl) -1-propanamine, N- (1-methyl) (Ropyridene) -3- (triethoxysilyl) -1-propanamine, N-ethylidene-3- (triethoxysilyl) -1-propanamine, N- (3-triethoxysilylpropyl) -4,5-dihydroimidazole And compounds having an imino group and an alkoxysilyl group.

  Furthermore, as the polyfunctional modifier having a halogen group, silicon tetrachloride, silicon tetrabromide, silicon tetraiodide, bistrichlorosilylethane, 2,2,4,4,6,6-hexachloro-2,4, Halogenated silane compounds such as 6-trisilaheptane, 1,2,3,4,5,6-hexakis [2- (methyldichlorosilyl) ethyl] benzene; monochlorotrimethoxysilane, monobromotrimethoxysilane, dichlorodimethoxy Examples thereof include alkoxyhalogenated silane compounds such as silane, dibromodimethoxysilane, trichloromethoxysilane, and tribromomethoxysilane.

  Furthermore, tin halide compounds such as tin tetrachloride, tin tetrabromide, and bistrichlorostannyl ethane; polyhalogenated phosphorus compounds such as trichlorophosphine and tribromophosphine, and the like.

Among these, more preferred polyfunctional modifiers are compounds having a functional group having a high affinity with silica, 4- to 6-functional polyepoxy compounds having a large effect of improving the molecular weight by coupling, or a total of 4 to 6 Examples thereof include compounds having both a functional epoxy group and an alkoxysilyl group. More preferable polyfunctional modifiers include glycidyl compounds having an amino group in the molecule, and compounds having two or three diglycidylamino groups in one molecule. For example, tetraglycidyl metaxylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, tetraglycidyl-1,3-bisaminomethylcyclohexane and the like can be mentioned.
The polyfunctional modifier mentioned above may be used independently and may use 2 or more types together.

  The addition amount of these polyfunctional modifiers is preferably 0.1 to 0.5 times the total number of functional groups of the polyfunctional modifier, preferably 0.1 to 0.5 times the number of moles of the anionic polymerization initiator, 0.2 to 0.4 times. In order to improve processability by imparting branching and to improve strength by increasing molecular weight, it is preferably added 0.1 times or more, and preferably 0.5 times or less from the viewpoint of economy.

  As described above, a polyfunctional modifier having 4 or more functional groups capable of reacting with active ends is brought into contact with a solution of a conjugated diene-aromatic vinyl copolymer having active ends to cause a coupling reaction. Thereby, the branched conjugated diene-aromatic vinyl copolymer (C) of this embodiment is obtained.

  As described above, after performing the coupling reaction, a predetermined deactivator, a neutralizing agent, or the like may be added to the solution as necessary. Examples of the quenching agent include alcohols such as water, methanol, ethanol, and isopropanol. Examples of the neutralizing agent include carboxylic acids such as stearic acid, oleic acid, and versatic acid, an aqueous solution of an inorganic acid, carbon dioxide gas, and the like.

  Moreover, since the branched conjugated diene-aromatic vinyl copolymer (C) of this embodiment itself may have a high viscosity, the viewpoint of preventing gelation in the finishing step after polymerization, or processing From the viewpoint of improving the stability at the time, 2,6-di-tert-butyl-4-hydroxytoluene (BHT), n-octadecyl-3- (4'-hydroxy-3 ', 5'- It is preferable to add known rubber stabilizers such as di-tert-butylphenol) propinate and 2-methyl-4,6-bis [(octylthio) methyl] phenol.

  From the viewpoint of further improving the workability of the branched conjugated diene-aromatic vinyl copolymer (C) of the present embodiment, it is preferable to add an extending oil. The method of addition is not particularly limited, but it is preferable to remove the solvent obtained by adding the extension oil to the polymer solution and mixing it to obtain an oil-extended copolymer solution. The extending oil is not particularly limited, and for example, aroma oil, naphthenic oil, paraffin oil and the like can be used, and an aroma substitute oil having a polycyclic aromatic component of 3% by mass or less by the IP346 method is preferable. Among these, the use of an aroma substitute oil having a polycyclic aromatic component of 3% by mass or less is more preferable as an aroma substitute oil from the viewpoint of environmental safety, prevention of oil bleeding, and wet grip characteristics. In addition to TDAE (Treated Distillate Aromatic Extracts), MES (Middle Extraction Solvate), etc., shown in Kautschuk Gummi Kunststoff 52 (12) 799 (1999). The amount of the extender oil used is not particularly limited, but usually it is preferably 10 to 60 parts by mass with respect to 100 parts by mass of the branched conjugated diene-aromatic vinyl copolymer (C) of the present embodiment. It is more preferably 20 to 37.5 parts by mass.

  The method for obtaining the branched conjugated diene-aromatic vinyl copolymer (C) of the present embodiment from the polymerization solution is not particularly limited, and conventionally known methods can be applied. For example, after separating the solvent by steam stripping or the like, the polymer is separated by filtration, further dehydrated and dried to obtain the polymer, concentrated in a flushing tank, and further devolatilized by a vent extruder or the like. The method, the method of directly devolatilizing with a drum dryer, etc. are applicable.

[Branched Conjugated Diene-Aromatic Vinyl Copolymer Composition]
The branched conjugated diene-aromatic vinyl copolymer composition refers to a mixture of a predetermined material with the above-described branched conjugated diene-aromatic vinyl copolymer of the present embodiment. Examples of this material include rubbery polymers other than branched conjugated diene-aromatic vinyl copolymers, inorganic fillers, metal oxides and metal hydroxides, silane coupling agents, rubber softeners, vulcanization And other fillers such as vulcanization agents, vulcanization accelerators and vulcanization aids. Among these, those containing at least an inorganic filler are preferable. That is, a branched conjugated diene-aromatic vinyl copolymer composition containing the branched conjugated diene-aromatic vinyl copolymer (C) of this embodiment and an inorganic filler is preferable.

  Examples of the rubber-like polymer other than the branched conjugated diene-aromatic vinyl copolymer (C) include, for example, a conjugated diene polymer or a hydrogenated product thereof, a random copolymer of a conjugated diene compound and a vinyl aromatic compound. Examples thereof include a polymer or a hydrogenated product thereof, a block copolymer of a conjugated diene compound and a vinyl aromatic compound, or a hydrogenated product thereof; a non-diene polymer, a natural rubber, and the like.

  Specifically, butadiene rubber or hydrogenated product thereof, isoprene rubber or hydrogenated product thereof, styrene-butadiene rubber or hydrogenated product thereof, styrene-butadiene block copolymer or hydrogenated product thereof, styrene-isoprene block copolymerized Examples thereof include styrene-based elastomers such as coalescence or hydrogenated products thereof, acrylonitrile-butadiene rubber, or hydrogenated products thereof.

  Examples of the non-diene polymer include ethylene-propylene rubber, ethylene-propylene-diene rubber, ethylene-butene-diene rubber, ethylene-butene rubber, ethylene-hexene rubber, ethylene-octene rubber and other olefin-based elastomers, butyl rubber, brominated butyl rubber, Acrylic rubber, fluororubber, silicone rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, α, β-unsaturated nitrile-acrylic ester-conjugated diene copolymer rubber, urethane rubber, polysulfide rubber and the like can be mentioned.

The rubbery polymer described above may be a modified rubbery polymer having a functional group. The molecular weight is preferably 2,000 to 2,000,000, and more preferably 5,000 to 1,500,000. A so-called liquid rubber having a low molecular weight can also be used.
These rubbery polymers may be used alone or in combination of two or more.

  When the above-described rubber-like polymer is combined with the branched conjugated diene-aromatic vinyl copolymer (C) of this embodiment, the mass ratio is not particularly limited, but low hysteresis loss and wet skid resistance. From the viewpoint of obtaining a vulcanizate that is excellent in balance with the material and satisfies practically sufficient wear resistance and fracture characteristics, the branched conjugated diene-aromatic vinyl copolymer (C) / the rubbery polymer described above 20/80 to 100/0 is preferable, 30/70 to 90/10 is more preferable, and 50/50 to 80/20 is further preferable.

  Examples of the inorganic filler include silica-based inorganic filler and carbon black.

The silica-based inorganic filler, for example, SiO _2, or the solid particles, and the like as a main component constituent units Si ₃ Al. Here, a main component means the component which occupies 50 mass% or more of a silica type inorganic filler. Specific examples of the silica-based inorganic filler include inorganic fibrous materials such as silica, clay, talc, mica, diatomaceous earth, wollastonite, montmorillonite, zeolite, and glass fiber. Further, a silica-based inorganic filler having a hydrophobic surface or a mixture of a silica-based inorganic filler and a non-silica inorganic filler can also be used. Among these, silica and glass fiber are preferable, and silica is more preferable. The silica is not particularly limited, and dry silica, wet silica, synthetic silicate silica and the like can be used. Among these, wet silica is preferable because it has excellent effects of improving the fracture characteristics and achieving both wet skid resistance.

In the branched conjugated diene-aromatic vinyl copolymer composition, from the viewpoint of obtaining practically good wear resistance and fracture characteristics, the nitrogen adsorption specific surface area required by the BET adsorption method of the silica-based inorganic filler described above is: preferably 100~300m is ² / g, and more preferably 170~250m ² / g.

If necessary, a silica-based inorganic filler having a relatively small specific surface area (for example, a specific surface area of less than 200 m ² / g) and a silica-based material having a relatively large specific surface area (for example, 200 m ² / g or more). By using in combination with an inorganic filler, it is possible to highly balance good wear resistance and fracture characteristics with low hysteresis loss.

  The blending amount of the silica-based inorganic filler in the branched conjugated diene-aromatic vinyl copolymer composition is not particularly limited, but 100 parts by mass of a rubber component containing the branched conjugated diene-aromatic vinyl copolymer (C). On the other hand, 0.5-300 mass parts is preferable, 5-200 mass parts is more preferable, and 20-100 mass parts is further more preferable. Addition of 0.5 parts by mass or more is preferable from the viewpoint of manifesting the effect of addition as a filler. On the other hand, the silica-based inorganic filler is sufficiently dispersed to make the workability and mechanical strength of the composition sufficiently practical. From the viewpoint, it is preferably 300 parts by mass or less.

The carbon black is not particularly limited, and carbon black of each class such as SRF, FEF, HAF, ISAF, SAF can be used, the nitrogen adsorption specific surface area is 50 m ² / g or more, and the DBP oil absorption is 80 mL / 100 g or more. Carbon black is preferred.

  The blending amount of carbon black is preferably 0.5 to 100 parts by weight, more preferably 3 to 100 parts by weight, and more preferably 5 to 50 parts by weight with respect to 100 parts by weight of the rubber component containing the branched conjugated diene-aromatic vinyl copolymer. Part by mass is more preferable. It is preferable to add 0.5 parts by mass or more from the viewpoint of expressing the performance required for applications such as dry grip performance and electrical conductivity, and it is preferable to add 100 parts by mass or less from the viewpoint of dispersibility.

In addition to the silica-based inorganic filler and carbon black described above, a metal oxide or a metal hydroxide may be added to the branched conjugated diene-aromatic vinyl copolymer composition. Here, the metal oxide refers to solid particles having a chemical unit M _x O _y (M is a metal atom, x and y each represent an integer of 1 to 6) as a main component of a structural unit, for example, , Alumina, titanium oxide, magnesium oxide, zinc oxide and the like. Moreover, the mixture containing inorganic fillers other than a metal oxide and a metal oxide can also be used. The metal hydroxide is not particularly limited, and examples thereof include aluminum hydroxide, magnesium hydroxide, and zirconium hydroxide.

  In the branched conjugated diene-aromatic vinyl copolymer composition, a silane coupling agent may be added. The silane coupling agent has a function to close the interaction between the rubber component and the silica-based inorganic filler, and has an affinity or binding group for each of the rubber component and the silica-based inorganic filler. In general, a compound having a sulfur bond portion, an alkoxysilyl group, and a silanol group portion in one molecule is used. From the above viewpoint, the silane coupling agent is preferably used in combination with the silica-based inorganic filler described above.

  Specific examples of the silane coupling agent include bis- [3- (triethoxysilyl) -propyl] -tetrasulfide, bis- [3- (triethoxysilyl) -propyl] -disulfide, bis- [2- (tri Ethoxysilyl) -ethyl] -tetrasulfide and the like.

  0.1-30 mass parts is preferable with respect to 100 mass parts of silica type inorganic fillers mentioned above, as for the compounding quantity of a silane coupling agent, 0.5-20 mass parts is more preferable, and 1-15 mass parts is. Further preferred. The blending amount of the silane coupling agent is preferably 0.1 parts by mass or more from the viewpoint of blending effects, and is preferably 30 parts by mass or less from the viewpoint of economy.

  In order to improve processability, the branched conjugated diene-aromatic vinyl copolymer composition may contain a rubber softener. Examples of rubber softeners include mineral oil or liquid or low molecular weight synthetic softeners. The mineral oil rubber softener called process oil or extender oil used for softening, increasing volume and improving processability of rubber is a mixture of aromatic ring, naphthene ring and paraffin chain. A paraffin chain having 50% or more carbon atoms in the total carbon is called paraffinic, a naphthene ring having 30 to 45% carbon is naphthenic, and an aromatic carbon having more than 30% aromatic is aromatic. It is called a system. As the softener for rubber used together with the branched conjugated diene-aromatic vinyl copolymer (C), those suitably containing an aromatic compound are well known and preferable.

  The blending amount of the rubber softening agent is preferably 0 to 100 parts by mass, more preferably 10 to 90 parts by mass with respect to 100 parts by mass of the rubber component containing the branched conjugated diene-aromatic vinyl copolymer (C). Preferably, 30 to 90 parts by mass are more preferable. It is preferable that the blending amount of the rubber softener is 100 parts by mass or less with respect to 100 parts by mass of the rubber component because bleeding out can be further suppressed and stickiness on the composition surface can be further suppressed.

  Various additives such as branched conjugated diene-aromatic vinyl copolymer (C) and other rubbery polymers, silica-based inorganic fillers, carbon black and other fillers, silane coupling agents, rubber softeners, etc. The method of mixing is not particularly limited. For example, a melt kneading method using a general blender such as an open roll, a Banbury mixer, a kneader, a single screw extruder, a twin screw extruder, a multi-screw extruder, etc. The method of removing by heating, etc. are mentioned. Among these, from the viewpoint of productivity and good kneadability, a melt kneading method using a roll, a Banbury mixer, a kneader, and an extruder in combination is preferable. Either a method of kneading the conjugated diene-aromatic vinyl copolymer and various compounding agents at a time or a method of mixing in a plurality of times may be used.

  The branched conjugated diene-aromatic vinyl copolymer composition described above may be a vulcanized composition that has been vulcanized with a vulcanizing agent. The vulcanizing agent is not particularly limited, and for example, radical generators such as organic peroxides and azo compounds, oxime compounds, nitroso compounds, polyamine compounds, sulfur and sulfur compounds can be used. Examples of the sulfur compound include sulfur monochloride, sulfur dichloride, a disulfide compound, and a polymer polysulfur compound.

  Although the usage-amount of a vulcanizing agent is not specifically limited, Usually, 0.01-20 mass parts is preferable with respect to 100 mass parts of rubber components containing a branched conjugated diene-aromatic vinyl copolymer (C), 0.1-15 mass parts is more preferable.

  The vulcanization method is not particularly limited, and a conventionally known method can be applied. The vulcanization temperature is, for example, 120 to 200 ° C, preferably 140 to 180 ° C. In vulcanization, a vulcanization accelerator or a vulcanization aid may be used as necessary. The vulcanization accelerator is not particularly limited, and conventionally known materials can also be used. Examples thereof include vulcanization accelerators such as sulfenamide, guanidine, thiuram, aldehyde-amine, aldehyde-ammonia, thiazole, thiourea, and dithiocarbamate. The vulcanization aid is not particularly limited, and conventionally known materials can also be used. Examples thereof include zinc white and stearic acid.

  The amount of the vulcanization accelerator used is usually 0.01 to 20 parts by mass with respect to 100 parts by mass of the rubber component containing the branched conjugated diene-aromatic vinyl copolymer (C). -15 mass parts is preferable. Although the usage-amount of a vulcanization auxiliary agent is not specifically limited, 1-10 mass parts is preferable with respect to 100 mass parts of rubber components mentioned above.

  In the branched conjugated diene-aromatic vinyl copolymer composition, a softener, a filler, a heat stabilizer, an antistatic agent, a weather stabilizer, other than those described above, as long as the purpose of the present embodiment is not impaired. You may use various additives, such as anti-aging agent, a coloring agent, and a lubricant. Specific examples of the filler include calcium carbonate, magnesium carbonate, aluminum sulfate, and barium sulfate. Known materials can be applied as the heat resistance stabilizer, antistatic agent, weather resistance stabilizer, anti-aging agent, colorant, and lubricant.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. In addition, this invention is not limited to a following example. The physical property measurement method and evaluation method applied to the examples and comparative examples are shown below.

  The measurement sample was a chloroform solution, and the amount of bound styrene (% by mass) was measured by UV 254 nm absorption by the phenyl group of styrene using an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation, UV-2450).

(2) Microstructure of butadiene part (vinyl bond amount)
The sample for measurement was a carbon disulfide solution, and the infrared spectrum was measured in the range of 600 to 1000 cm ⁻¹ using a Fourier transform infrared spectrophotometer (manufactured by JASCO Corporation, FT-IR230) using a solution cell. Then, the microstructure (vinyl bond amount) of the butadiene portion was determined from the absorbance at a predetermined wave number according to the calculation formula of the Hampton method.

(3) Mooney viscosity and Mooney relaxation rate Using a Mooney viscometer (manufactured by Ueshima Seisakusho, VR1132), the Mooney viscosity and Mooney relaxation rate were measured based on ISO 289-1 and ISO 289-4 at a temperature of 120 ° C. First, after preheating the sample at 120 ° C. for 1 minute, the rotor was rotated at 2 rpm, the torque after 4 minutes was measured, and the Mooney viscosity (ML _{1 + 4} ) was obtained. After that, the rotation of the rotor is stopped immediately, the torque every 0.1 seconds for 1.6 to 5 seconds after the stop is recorded in Mooney units, and the slope of the straight line when the torque and time (seconds) are logarithmically plotted. The absolute value thereof was taken as the Mooney relaxation rate (MSR).

(4) Weight average molecular weight and molecular weight distribution Using a GPC measuring apparatus in which three columns with polystyrene gel as a filler were connected, a chromatogram was measured, and a weight average molecular weight based on a calibration curve using standard polystyrene. Asked. Furthermore, molecular weight distribution (weight average molecular weight / number average molecular weight) was determined from the ratio of the weight average molecular weight to the number average molecular weight.

  Tetrahydrofuran (THF) was used as the eluent. As the column, guard column: Tosoh TSKguardcolumn HHR-H, column: Tosoh TSKgel G6000HHR, TSKgel G5000HHR, TSKgel G4000HHR were used. An RI detector (manufactured by Tosoh Corporation, HLC8020) was used under the conditions of an oven temperature of 40 ° C. and a THF flow rate of 1.0 mL / min. 10 mg of a sample for measurement was dissolved in 10 mL of THF to prepare a measurement solution, and 200 μL of the measurement solution was injected into a GPC measurement device and measured.

(5) Glass transition temperature (Tg)
In accordance with ISO 22768: 2006, measurement was performed using a DSC3200S manufactured by Mac Science. A DSC curve was recorded while increasing the temperature from −100 ° C. to 20 ° C./min under a flow of helium at 50 mL / min, and the peak top (Inflection point) of the DSC differential curve was taken as the glass transition temperature.

(6) Conversion Rate About 20 mL of the polymer solution obtained from the reactor outlet is injected into a 100 mL bottle sealed with 0.50 mL of n-propylbenzene as an internal standard and about 20 mL of toluene to prepare a sample for measurement. did. The obtained sample was measured by gas chromatography (GC) equipped with a packed column carrying Apiezon grease. From the calibration curve of 1,3-butadiene monomer and styrene monomer obtained in advance, The amount of residual monomers was determined, and the conversion rates of 1,3-butadiene monomer and styrene monomer were determined.

[Example 1]
Autoclave with internal volume 10L, ratio of internal height (L) to diameter (D) (L / D) of 4, inlet at bottom, outlet at top, stirrer and jacket for temperature adjustment Were connected in series, and the first group was used as a polymerization reactor and the second group as a coupling reactor.

  In advance, impurities such as moisture were removed, and 1,3-butadiene was mixed at an addition rate of 22.0 g / min, styrene 14.8 g / min, and n-hexane 167.5 g / min to obtain a mixed solution. . For the resulting mixed solution, n-butyllithium (treated n-butyllithium) was mixed at a rate of addition of 0.103 mmol / min using a static mixer for impurity inactivation treatment. This mixed solution was continuously supplied to the bottom of the first polymerization reactor, and 2,2-bis (2-oxolanyl) propane as a polar substance was added at a rate of 0.052 g / min. N-butyllithium is added to the bottom of the first polymerization reactor at an addition rate of 0.170 mmol / min, and the polymerization reaction is controlled by controlling the internal temperature of the outlet of the polymerization reactor to be 93 ° C. Continued. At this time, the average residence time in the reactor was 33 minutes.

  The polymer solution was continuously taken out from the top of the first polymerization reactor and supplied to the bottom of the second coupling reactor. In a state where the polymerization reaction in the first polymerization reactor is steady, a small amount of the polymer solution is taken from the inlet of the second coupling reactor while being careful not to contact with air. Each was extracted and added to a mixed solution of about 1 mL of methanol and about 30 mL of cyclohexane. Then, after adding an antioxidant (BHT: 2,6-di-t-butyl-4-hydroxytoluene) to the mixed solution so as to be 0.2 g per 100 g of the polymer, the solvent is removed with a drum dryer. A sample (conjugated diene-aromatic vinyl copolymer) for measuring the molecular weight, Mooney viscosity and Mooney relaxation rate was obtained. The Mooney viscosity and Mooney relaxation rate were measured after passing 10 times through a 6 inch roll set at 110 ° C.

  The sample (conjugated diene-aromatic vinyl copolymer (I)) had a Mooney viscosity (ML-I) at 120 ° C. of 68.8 and a Mooney relaxation rate (MSR-I) of 0.624, which was measured by GPC. The weight average molecular weight (Mw-I) in terms of polystyrene was 614,000. The polymerization conversion rate at the inlet of the second coupling reactor was 99% for 1,3-butadiene and 98% for styrene.

  The temperature of the second coupling reactor was kept at 85 ° C., and tetraglycidyl-1,3-bisaminomethylcyclohexane was added from the bottom of the second coupling reactor at an addition rate of 0.0205 mmol / min. The coupling reaction was carried out. Tetraglycidyl-1,3-bisaminomethylcyclohexane is a compound having 4 epoxy groups in one molecule, and the ratio (equivalent ratio) between the total number of moles of the functional groups and the number of moles of n-butyllithium added. Was 0.30. Antioxidant (BHT) was continuously added to the polymer solution taken out from the top of the second coupling reactor at a rate of 0.074 g / min (n-hexane solution) so as to be 0.2 g per 100 g of the polymer. Then, the coupling reaction was terminated. Thereafter, the solvent was removed to obtain a branched conjugated diene-aromatic vinyl copolymer (C).

  The branched conjugated diene-aromatic vinyl copolymer (C) after this coupling had a Mooney viscosity (ML-C) at 120 ° C. of 98.5, a Mooney relaxation rate (MSR-C) of 0.411, and GPC The polystyrene-reduced weight average molecular weight (Mw-C) was 802,000, and the ratio of the weight average molecular weight to the number average molecular weight ((Mw-C) / (Mn-C)) was 2.38. The amount of bound styrene was 40% by mass, the amount of 1,2-bond in the butadiene bond unit was 46 mol%, and the glass transition temperature measured by DSC was −13 ° C.

  Further, 37.5 parts by mass of S-RAE oil (NC-140 manufactured by Japan Energy Co., Ltd.) per 100 parts by mass of the polymer was added to the branched conjugated diene-aromatic vinyl copolymer solution, and then the solvent was removed. As a result, an oil-extended copolymer (sample a) was obtained. The properties of the copolymer are shown in Table 1.

[Example 2]
Polymerization initiation n-butyllithium, 2,2-bis (2-oxolanyl) propane and tetraglycidyl-1,3-bisaminomethylcyclohexane were used under the conditions shown in Table 1. Other conditions were the same as in Example 1, and an oil-extended copolymer (sample b) was obtained. The properties of the copolymer are shown in Table 1.

Example 3
As shown in Table 1, the monomer supply amount was changed from the method of Example 1 without changing the amount ratio of butadiene and styrene. The average residence time was 25 minutes, and the internal temperature at the reactor outlet was 97 ° C. The supply amount of other materials was also changed as shown in Table 1. The polymerization reaction and the coupling reaction were carried out in the same manner as in Example 1, and the oil was added and the solvent was removed to obtain an oil-extended copolymer (sample c). The properties of the copolymer are shown in Table 1.

Example 4
As shown in Table 1, the amount of tetraglycidyl-1,3-bisaminomethylcyclohexane added was changed. For other conditions, the polymerization reaction and the coupling reaction were carried out in the same manner as in Example 3, the oil was added and the solvent was removed, and an oil-extended copolymer (sample d) was obtained. The properties of the copolymer are shown in Table 1.

[Examples 5 and 6]
As shown in Table 1, without changing the monomer supply amount, the addition amount of polymerization initiation n-butyl lithium, 2,2-bis (2-oxolanyl) propane and tetraglycidyl-1,3-bisaminomethylcyclohexane was changed. changed. The other conditions were the same as in Example 4, in which a polymerization reaction and a coupling reaction were performed, and oil was added and the solvent was removed to obtain an oil-extended copolymer (samples e and f). The properties of the copolymer are shown in Table 1.

[Comparative Example 1]
As shown in Table 2, from the method of Example 1, the monomer supply amount was changed without changing the amount ratio of butadiene and styrene, the average residence time was 45 minutes, the internal temperature of the reactor outlet was 85 ° C. The polymerization amount was changed as shown in Table 2 to carry out the polymerization reaction. Since the addition of tetraglycidyl-1,3-bisaminomethylcyclohexane was made zero, in Examples 1-6, the polymerization reaction was carried out in one reactor, whereas in this case two reactions were carried out. The polymerization reaction was carried out in a vessel. The polymerization conversion was measured with a copolymer solution obtained from the top of the second reactor. Thereafter, addition of oil and desolvation were carried out in the same manner as in Example 1 to obtain an oil-extended copolymer (sample g). The properties of the copolymer are shown in Table 2.

[Comparative Example 2]
As shown in Table 2, from the method of Example 1, the monomer supply amount was changed without changing the amount ratio of butadiene and styrene, the average residence time was 45 minutes, the internal temperature of the reactor outlet was 85 ° C. The supply amount of the substance was changed as shown in Table 2 to carry out the polymerization reaction and the coupling reaction, and the oil was added and the solvent was removed to obtain an oil-extended copolymer (sample h). The polymerization conversion rate and the like were measured by the same method as in Example 1. The properties of the copolymer are shown in Table 2.

[Comparative Example 3]
As shown in Table 2, the polymerization reaction and the coupling reaction were carried out in the same manner as in Comparative Example 2 except that the addition amount of tetraglycidyl-1,3-bisaminomethylcyclohexane was changed, and the addition and desorption of oil were performed. Solvent was used to obtain an oil-extended copolymer (sample i). The properties of the copolymer are shown in Table 2.

[Comparative Example 4]
As shown in Table 2, from the method of Example 1, the monomer supply amount was changed without changing the quantitative ratio of butadiene and styrene, the average residence time was 22 minutes, the internal temperature of the reactor outlet was 105 ° C, The supply amount of other substances was also changed as shown in Table 2, and the polymerization reaction and the coupling reaction were performed. Thereafter, oil addition and desolvation were performed in the same manner as in Example 1 to obtain an oil-extended copolymer (sample j). The properties of the copolymer are shown in Table 2.

[Comparative Example 5]
As shown in Table 2, the amount ratio of butadiene and styrene was changed from the method of Example 1, the monomer supply amount was changed, the average residence time was 25 minutes, the internal temperature of the reactor outlet was 97 ° C, The supply amount of the substance was also changed as shown in Table 2, and the polymerization reaction and the coupling reaction were performed in the same manner as in Example 1. Then, oil addition and desolvation were performed in the same manner as in Example 1 to obtain an oil-extended copolymer (sample k). The properties of the copolymer are shown in Table 2.

[Examples 7 to 10], [Comparative Examples 6 to 10]
Using the samples shown in the above table (samples a, c to e, g to k) as raw rubber, rubber compositions containing the respective raw rubbers were prepared according to the formulation shown below.

Oil-extended styrene-butadiene copolymer (samples a, c to e, g to k): 96.25 parts by mass Polybutadiene rubber having a high 1,4-cis content (hereinafter referred to as high cis polybutadiene rubber) ( Ube Industries, UBEPOL-150): 30.00 parts by mass Silica (Degussa, Ultrasil VN3): 75.00 parts by mass Carbon black (Tokai Carbon, N339): 5.00 parts by mass Coupling agent (Degussa, Si75): 6.00 parts by mass S-RAE oil (Japan Energy, JOMO process NC140): 15.75 parts by mass, zinc white: 2.50 parts by mass, stearic acid: 2.00 parts by mass, wax (manufactured by Ouchi Shinsei Chemical Co., Ltd., Sunnock N): 1.50 parts by mass, antioxidant (N-isopropyl-N′-phenyl-p- (Enylenediamine): 2.00 parts by mass, sulfur: 2.20 parts by mass, vulcanization accelerator (N-cyclohexyl-2-benzothiazylsulfinamide): 1.70 parts by mass, vulcanization accelerator (diphenylguanidine): 2.00 parts by mass total: 241.90 parts by mass

The rubber composition was kneaded by the following method.
Using a closed kneader (with an internal volume of 0.3 L) equipped with a temperature control device, as the first stage kneading, under the conditions of a filling rate of 72% and a rotor rotational speed of 50/57 rpm, the raw rubber (samples a, c to c) e, g to k, high-cis butadiene rubber), silica, organosilane coupling agent, and process oil were kneaded. At this time, the temperature of the closed mixer was controlled, and the rubber composition was obtained at a discharge temperature (compound) of 155 to 160 ° C.

  Next, as the second stage of kneading, the blend obtained above was cooled to room temperature, and then carbon black, zinc white, stearic acid, wax and anti-aging agent were added and kneaded again. Also in this case, the discharge temperature (formulation) was adjusted to 155 to 160 ° C. by controlling the temperature of the mixer. After cooling, as a third stage of kneading, sulfur and a vulcanization accelerator were added and kneaded with an open roll set at 70 ° C. Then, it shape | molded and vulcanized with the vulcanization press for 20 minutes at 160 degreeC. After vulcanization, the physical properties of the rubber composition were measured. The physical property measurement results are shown in Table 3.

The physical properties of the rubber composition were measured by the following methods.
(1) Bound rubber amount The compound (about 0.2 g) after completion of the second stage kneading step was cut into a square of about 1 mm, put into a Harris basket (manufactured by 100 mesh wire mesh), and the weight was measured. Then, after being immersed in toluene at 23 ° C. for 24 hours, a drying treatment was performed, and the weight of the toluene insoluble component was measured. The weight of the rubber bound to the filler (branched conjugated diene-aromatic vinyl copolymer + high cis butadiene rubber) was calculated from the weight of the undissolved component and bound to the filler relative to the amount of rubber in the initial formulation. The percentage of rubber was determined.

(2) Compound Mooney Viscosity Using a Mooney viscometer and preheating for 1 minute at 130 ° C. in accordance with JIS K6300-1, the rotor was rotated at 2 revolutions per minute (2 rpm), and after 4 minutes The viscosity of was measured. The smaller the Mooney viscosity, the smaller the energy consumption during kneading and the better the workability.

(3) Tensile strength Measured according to the tensile test method of JIS K6251. The measured value of Comparative Example 6 was indexed as 100.

(4) Viscoelastic parameters Viscoelastic parameters were measured in a torsion mode using a viscoelasticity tester (ARES) manufactured by Rheometrics Scientific. Each measured value was indexed with the measured value of Comparative Example 6 as 100. Tan δ (loss tangent) measured at a frequency of 10 Hz and a strain of 1% at 0 ° C. was used as an index of wet skid resistance. It shows that wet skid resistance is so favorable that a value is large.

  Further, tan δ (loss tangent) measured at 50 ° C. with a frequency of 10 Hz and a strain of 3% was used as an index of fuel saving characteristics. It shows that low hysteresis loss property is so favorable that a value is small. Further, G ′ (storage modulus) measured under the same conditions was used as an indicator of steering stability. The larger the value and the higher the rigidity, the better the stability.

(5) Abrasion resistance An Akron abrasion tester (manufactured by Yasuda Seiki Seisakusho) was used, and the amount of wear at a load of 44.1 N and 1000 rotations was measured according to JIS-K6264-2. The measured value of Comparative Example 6 was indexed as 100. A larger index indicates better wear resistance.

  Examples 7 to 10 and Comparative Example 6 are compared. In Examples 7 to 10 using Samples a and c to e, the compound Mooney viscosity was low and the processability was excellent. As seen from tan δ at 50 ° C. and 0 ° C., low hysteresis loss and wet skid resistance It has been found that the material has an excellent balance of tensile strength and wear resistance, and also satisfies practically sufficient wear resistance and fracture characteristics. On the other hand, the copolymer g of Comparative Example 1 produced without performing the coupling reaction had a high Mooney relaxation rate as the degree of branching was low, and did not satisfy the requirement of the above formula (1). Comparative Example 6 using this copolymer g was inferior to Examples 7 to 10 in the above characteristics.

  Examples 7 to 10 and Comparative Example 7 are compared. Comparative Example 7 has a low compound Mooney viscosity, excellent processability, excellent balance between low hysteresis loss and wet skid resistance, good tensile strength and wear resistance, and practically sufficient wear resistance Also satisfy the fracture characteristics. However, in Comparative Example 7, the copolymer h of Comparative Example 2 is used, and the copolymer h has a low polymerization temperature, so that branching does not proceed sufficiently and the degree of branching is reduced. The Mooney relaxation rate became high and the requirement (1) was not satisfied. The copolymer h of Comparative Example 2 inevitably increases the residence time in the reactor in order to obtain a polymerization addition rate equivalent to the copolymers a and c to e of Examples 1 and 3 to 5. As a result, the productivity of the copolymer was inferior. Therefore, it was found that the rubber composition of Comparative Example 7 was inferior at least in terms of productivity as compared with Examples 7-10.

  Examples 7 to 10 and Comparative Example 8 are compared. Comparative Example 8 uses the copolymer i prepared in Comparative Example 3, but the copolymer g has a large addition amount of tetraglycidyl-1,3-bisaminomethylcyclohexane, and the coupling amount increases. The Mooney viscosity was high, the blend viscosity of the rubber composition of Comparative Example 8 using this was high, and at least the processability was inferior. Further, since the polymerization reaction needs to be performed at a relatively low temperature in order to increase the coupling efficiency, the residence time in the reactor becomes longer, and the productivity of the copolymer i is low.

  Examples 7 to 10 and Comparative Example 9 are compared. Comparative Example 9 uses the copolymer j produced in Comparative Example 4, but the copolymer j has a high polymerization temperature and a molecular weight distribution that is too wide, and the rubber composition of Comparative Example 9 using this copolymer j. Was found to be inferior in at least tensile strength and abrasion resistance as compared with Examples 7-10.

  Examples 7 to 10 and Comparative Example 10 are compared. Comparative Example 10 uses the copolymer k produced in Comparative Example 5, but the copolymer k has a low vinyl bond content and a low bond styrene content, and the rubber composition of Comparative Example 10 using the copolymer k is As compared with Examples 7 to 10, it was found that tan δ at 0 ° C. was low, and at least wet skid resistance was inferior.

  The conjugated diene-aromatic vinyl copolymer of the present invention has industrial applicability as a material for tire treads, footwear, industrial articles and the like.

Claims (6)

A random copolymer, a conjugated diene-aromatic vinyl copolymer (C),
The aromatic vinyl bond content in the conjugated diene-aromatic vinyl copolymer (C) is 38 to 45% by mass,
The vinyl bond amount in the conjugated diene total bond unit is more than 43 mol% and 50 mol% or less,
The conjugated diene-aromatic vinyl copolymer (C) has a weight average molecular weight (Mw-C) of 700,000 to 1,000,000,
The ratio of the weight average molecular weight (Mw-C) to the number average molecular weight (Mn-C) ((Mw-C) / (Mn-C)) is 1.7 to 3.0,
A branched conjugated diene-aromatic vinyl copolymer (C) in which the Mooney viscosity (ML-C) and Mooney relaxation rate (MSR-C) measured at 120 ° C. satisfy the relationship of the following formula (1).
{195- (ML-C)} / 300 ≦ (MSR-C) ≦ {235- (ML-C)} / 300 (1)
(Here, 90 ≦ (ML−C) ≦ 125 in the formula (1)). The weight average molecular weight (Mw-I) is 500,000 to 700,000, and the Mooney viscosity (ML-I) and Mooney relaxation rate (MSR-I) measured at 120 ° C. are represented by the following formula (2). The branched conjugated diene-fragrance according to claim 1, wherein the conjugated diene-aromatic vinyl copolymer (I) satisfying the above is coupled using a polyfunctional modifier having four or more functional groups. Group vinyl copolymer (C).

{235- (ML-I)} / 300 ≦ (MSR-I) ≦ {270- (ML-I)} / 300 (2)
(Here, in formula (2), 60 ≦ (ML−I) ≦ 90) The branched conjugated diene-aromatic vinyl copolymer (C) according to claim 1 or 2,
An inorganic filler;
A branched conjugated diene-aromatic vinyl copolymer composition comprising: A method for producing the branched conjugated diene-aromatic vinyl copolymer (C) according to claim 1 or 2,
A solution containing a conjugated diene compound, an aromatic vinyl compound, and an anionic polymerization initiator is continuously supplied to the reactor to advance the polymerization reaction, thereby obtaining a solution of a conjugated diene-aromatic vinyl copolymer having an active end. Process,
Coupling the conjugated diene-aromatic vinyl copolymer using a polyfunctional modifier having four or more functional groups capable of reacting with the active terminal;
The manufacturing method of the branched conjugated diene-aromatic vinyl copolymer (C) which has these. A method for producing the branched conjugated diene-aromatic vinyl copolymer (C) according to claim 1 or 2,
A step of continuously supplying a solution containing a conjugated diene compound, an aromatic vinyl compound, and an anionic polymerization initiator to a reactor equipped with a stirrer to advance the polymerization reaction;
Continuously obtaining a solution of a conjugated diene-aromatic vinyl copolymer having an active end from the outlet of the reactor;
Coupling the conjugated diene-aromatic vinyl copolymer with a polyfunctional modifier having four or more functional groups capable of reacting with the active terminal;
Have
In the polymerization reaction, a branched conjugated diene-aromatic vinyl copolymer that keeps the internal temperature at the outlet of the reactor at 90 to 100 ° C. and continuously proceeds the polymerization reaction with an average residence time of 20 minutes to 40 minutes. The manufacturing method of (C).   The said polyfunctional modifier is used so that the total number of moles of the functional group of the said polyfunctional modifier may be 0.1 to 0.5 time with respect to the mol number of the said anionic polymerization initiator. 5. The method for producing a branched conjugated diene-aromatic vinyl copolymer (C) according to 5.