JP7102926B2 - Rubber composition for tire tread and pneumatic tire - Google Patents

Description

The present invention relates to a rubber composition for a tire tread and a pneumatic tire.

In recent years, improvement of tire rolling performance (low rolling resistance) has been required from the viewpoint of low fuel consumption when the vehicle is running. On the other hand, there is known a method of blending silica with a rubber component constituting a tread portion of a tire to improve rolling performance.
However, since silica has a low affinity with the rubber component and has high cohesiveness between the silicas, even if silica is simply mixed with the rubber component, the silica does not disperse, and the effect of improving the rolling performance is sufficiently obtained. There was a problem that it could not be done.

Under such circumstances, for example, in claim 1 of Patent Document 1, a rubber composition for a tire tread containing a conjugated diene-based rubber produced by a method for producing a conjugated diene-based rubber including steps A, B, and C in this order. The thing is disclosed. Patent Document 1 describes that the tire tread rubber composition exhibits excellent rolling performance when made into a tire.

Japanese Unexamined Patent Publication No. 2016-47887

Recently, with the improvement of the required safety level, it is desired to improve the wear resistance performance of the tire. Further, due to environmental problems and resource problems, further improvement of tire rolling performance is required. Further, from the viewpoint of manufacturing efficiency, improvement of workability (reduction of viscosity) of the rubber composition for tire tread used for the tire tread portion is also required.

Under these circumstances, the present inventors prepared a rubber composition for a tire tread with reference to the examples of Patent Document 1, and evaluated the wear resistance performance when made into a tire, the rolling performance when made into a tire, and the workability. As a result, it became clear that further improvement is desirable in consideration of the demands that will increase further in the future.

Therefore, the present invention provides a rubber composition for a tire tread, which is excellent in wear resistance when made into a tire, rolling performance when made into a tire, and workability, and a pneumatic tire using the above rubber composition for tire tread. The challenge is to provide.

As a result of diligent studies on the above problems, the present inventors have found that the above problems can be solved by using a specific conjugated diene rubber and a specific modified butadiene polymer in combination, and have reached the present invention.
That is, the present inventors have found that the above problems can be solved by the following configuration.

(1) A conjugated diene rubber containing 10% by mass or more of a specific conjugated diene rubber having a weight average molecular weight of more than 100,000, and a conjugated diene rubber.
With silica
Silane coupling agent and
Containing with specific modified butadiene polymer,
The silica content is 30 parts by mass or more with respect to 100 parts by mass of the conjugated diene rubber.
The content of the silane coupling agent is 3 to 30% by mass with respect to the content of the silica.
In the first step, the specific conjugated diene-based rubber polymerizes a monomer containing a conjugated diene compound in an inert solvent using a polymerization initiator to obtain a conjugated diene-based polymer chain having an active terminal. The polyorganosiloxane represented by the general formula (1) described later is added to the conjugated diene polymer chain having the active terminal in the polyorganosiloxane with respect to 1 mol of the polymerization initiator used in the first step. The second step of adding and reacting the siloxane structure (-Si-O-) in a ratio of 1 mol or more in terms of the number of repeating units, and the conjugated diene system obtained by reacting the polyorganosiloxane obtained in the second step. A conjugated diene-based rubber produced by a method for producing a conjugated diene-based rubber, which comprises a third step of reacting a polymer chain with a compound represented by the general formula (2) described later.
The specific modified butadiene polymer has a functional group containing a nitrogen atom and a silicon atom at the end, has a weight average molecular weight of 1,000 or more and 100,000 or less, and has a molecular weight distribution of 2.0 or less. A rubber composition for tire treads.
(2) The rubber composition for tire tread according to (1) above, wherein the viscosity of the specific modified butadiene polymer is 150 to 240% with respect to the viscosity of the butadiene polymer before modification. However, the above viscosity shall be measured using a cone plate type viscometer.
(3) The rubber composition for tire tread according to (1) or (2) above, wherein the content of the specific modified butadiene polymer is 1 to 25% by mass with respect to the content of silica.
(4) The specific conjugated diene rubber is
A polymer block (A) containing 80 to 100% by mass of an isoprene monomer unit and 0 to 20% by mass of an aromatic vinyl monomer unit, and
It has a structure in which a polymer block (B) containing 50 to 100% by mass of a 1,3-butadiene monomer unit and 0 to 50% by mass of an aromatic vinyl monomer unit is continuously formed. A rubber composition for a tire tread according to any one of 1) to (3).
(5) A pneumatic tire including a tire tread portion manufactured by using the rubber composition for tire tread according to any one of (1) to (4) above.

As shown below, according to the present invention, the wear resistance performance when made into a tire (hereinafter, also simply referred to as "wear resistance performance") and the rolling performance when made into a tire (hereinafter, also simply referred to as "rolling performance"). ) And a rubber composition for a tire tread having excellent workability, and a pneumatic tire using the rubber composition for a tire tread.

It is a partial cross-sectional schematic diagram of an example of embodiment of the pneumatic tire of this invention.

Hereinafter, the rubber composition for tire tread of the present invention and the pneumatic tire using the rubber composition for tire tread will be described.
The numerical range represented by using "-" in the present specification means a range including the numerical values before and after "-" as the lower limit value and the upper limit value.
Further, each component contained in the rubber composition for tire tread of the present invention may be used alone or in combination of two or more. Here, when two or more kinds of each component are used in combination, the content of the component means the total content unless otherwise specified.
Further, in the present specification, "(meth) acrylic" is a notation representing "acrylic" or "methacrylic", and "(meth) acrylonitrile" is a notation representing "acrylonitrile" or "methacrylonitrile". ..

[I] Rubber Composition for Tire Tread The rubber composition for tire tread of the present invention (hereinafter, also referred to as "composition of the present invention") is
Conjugated diene rubber containing 10% by mass or more of specific conjugated diene rubber having a weight average molecular weight of more than 100,000, and
With silica
Silane coupling agent and
Contains a specific modified butadiene polymer.
Here, the content of the silica is 30 parts by mass or more with respect to 100 parts by mass of the conjugated diene rubber, and the content of the silane coupling agent is 3 to 30% by mass with respect to the content of the silica. be.
Further, the specific conjugated diene-based rubber is the first step of polymerizing a monomer containing a conjugated diene compound in an inert solvent using a polymerization initiator to obtain a conjugated diene-based polymer chain having an active terminal. The polyorganosiloxane represented by the general formula (1) described later is added to the conjugated diene polymer chain having the active terminal with respect to 1 mol of the polymerization initiator used in the first step. The second step of adding and reacting the siloxane structure (-Si-O-) in the siloxane at a ratio of 1 mol or more in terms of the number of repeating units, and the conjugate obtained by reacting the polyorganosiloxane obtained in the second step. It is a conjugated diene-based rubber produced by a method for producing a conjugated diene-based rubber, which comprises a third step of reacting a diene-based polymer chain with a compound represented by the general formula (2) described later.
Further, the specific modified butadiene polymer has a functional group containing a nitrogen atom and a silicon atom at the terminal, has a weight average molecular weight of 1,000 or more and 100,000 or less, and has a molecular weight distribution of 2.0 or less. It is a butadiene polymer.
Since the composition of the present invention has such a structure, it is considered that the above-mentioned effects can be obtained. The reason is not clear, but it is presumed to be as follows.

As mentioned above, the compositions of the present invention contain silica. Excellent rolling performance is expected by using silica, but as described above, silica tends to aggregate, and there is a problem that the above effect is not actually exhibited satisfactorily. Further, there is a problem that the abrasion resistance and workability are deteriorated due to the aggregation of silica.
On the other hand, since the specific conjugated diene rubber contained in the composition of the present invention has a polyorganosiloxane structure having a structure similar to that of silica, the polyorganosiloxane structure is compatible with silica and prevents silica from agglomerating. Conceivable. In addition, since the specific conjugated diene rubber also has a structure derived from nitrogen atom-containing silane such as aminosilane, it is considered that this promotes silanization between the silane coupling agent and silica and further suppresses the aggregation of silica. .. As a result, it is considered that the effect of improving the rolling performance of silica is sufficiently exhibited, and the wear resistance and workability are also improved.

Hereinafter, each component contained in the composition of the present invention will be described in detail.

[1] Conjugated Diene Rubber The conjugated diene rubber contained in the composition of the present invention is a conjugated diene rubber having a weight average molecular weight of more than 100,000 and containing 10% by mass or more of a specific conjugated diene rubber. ..
First, a specific conjugated diene-based rubber will be described.

[Specific conjugated diene rubber]
The specific conjugated diene-based rubber contained in the composition of the present invention is a conjugated diene-based rubber produced by a method for producing a conjugated diene-based rubber, which comprises the following first to third steps.
(1) First step (1) First step (2) First step (2) First step of polymerizing a monomer containing a conjugated diene compound in an inert solvent using a polymerization initiator to obtain a conjugated diene polymer chain having an active terminal. 2 steps The polyorganosiloxane represented by the general formula (1) described later is added to the conjugated diene polymer chain having an active end with respect to 1 mol of the polymerization initiator used in the first step. 2nd step (3) 3rd step to add and react at a ratio of 1 mol or more in terms of the number of repeating units of the siloxane structure (-Si-O-) in the 3rd step The polyorganosiloxane obtained in the above 2nd step is reacted. The third step of reacting the conjugated diene polymer chain with the compound represented by the general formula (2) described later.

First, the reason for specifying the specific conjugated diene rubber by the manufacturing method as described above will be described.
As described above, in the third step, the compound represented by the general formula (2) described later is reacted with the conjugated diene-based polymer chain obtained by reacting the polyorganosiloxane obtained in the second step. Here, A1 contained in the compound represented by the general formula (2) reacts with a reaction residue generated by the reaction of the conjugated diene polymer chain having ^an active terminal and polyorganosiloxane and binds to each other. However, as will be described later, the reaction residue generated by the reaction between the conjugated diene polymer chain having an active terminal and polyorganosiloxane can have various structures, and therefore the reaction residue is represented by the general formula (2). The structure of a compound after it has reacted is extremely complex, and it is technically impossible to analyze the structure, or the cost and time required to identify the structure are significantly excessive. Needs. Therefore, it is a so-called "impossible / impractical situation" to describe a specific conjugated diene rubber as "a conjugated diene rubber manufactured by a method for producing a conjugated diene rubber having the first to third steps". exist.

Hereinafter, each step will be described.

[First step]
The first step is a step of polymerizing a monomer containing a conjugated diene compound in an inert solvent using a polymerization initiator to obtain a conjugated diene-based polymer chain having an active terminal.
First, each component and the like used in the first step will be described.

<Conjugated diene compound>
The conjugated diene compound used as a monomer in order to obtain a conjugated diene polymer chain having an active terminal in the first step is not particularly limited, but is limited to 1,3-butadiene, isoprene, and 2,3-dimethyl-. 1,3-butadiene, 2-phenyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 4,5-diethyl-1,3-octadien, Examples thereof include 3-butyl-1,3-octadien. Among these, 1,3-butadiene and isoprene are preferable because the effect of the present invention is more excellent. These conjugated diene compounds may be used alone or in combination of two or more.

<Aromatic vinyl compound>
Further, in the first step, an aromatic vinyl compound may be used together with the conjugated diene compound as the monomer used for the polymerization. Examples of the aromatic vinyl compound used as the monomer include styrene, methylstyrene, ethylstyrene, t-butylstyrene, α-methylstyrene, α-methyl-p-methylstyrene, chlorostyrene, bromostyrene, methoxystyrene, and dimethylamino. Examples thereof include methylstyrene, dimethylaminoethylstyrene, diethylaminomethylstyrene, diethylaminoethylstyrene, cyanoethylstyrene, vinylnaphthalene and the like. Among these, styrene is preferable because the effect of the present invention is more excellent.

The conjugated diene-based polymer chain having an active terminal obtained in the first step preferably contains 50 to 100% by mass of a conjugated diene monomer unit, and 52 to 95% by mass, for the reason that the effect of the present invention is more excellent. It is more preferable that it contains%, and it is preferable that it contains 0 to 50% by mass of an aromatic vinyl monomer unit, and more preferably it contains 5 to 48% by mass.

<Other copolymerizable compounds>
Further, in the first step, a compound that is copolymerizable with the conjugated diene compound (other copolymerizable compound) other than the aromatic vinyl compound may be used together with the conjugated diene compound. Examples of the compound copolymerizable with such a conjugated diene compound include a chain olefin compound such as ethylene, propylene and 1-butene; a cyclic olefin compound such as cyclopentene and 2-norbornene; 1,5-hexadiene and 1,6- Non-conjugated diene compounds such as heptadiene, 1,7-octadien, dicyclopentadiene, 5-ethylidene-2-norbornene; (meth) methyl acrylate, ethyl (meth) acrylate, butyl (meth) acrylate and the like ( Meta) acrylic acid esters; other (meth) acrylic acid derivatives such as (meth) acrylonitrile, (meth) acrylamide; and the like. For the reason that the effect of the present invention is more excellent, the compound copolymerizable with these conjugated diene compounds has 10 as a monomer unit in the conjugated diene polymer chain having an active terminal obtained in the first step. It is preferably mass% or less, and more preferably 5 mass% or less.

<Inactive solvent>
The inert solvent used for the polymerization is usually used in solution polymerization and is not particularly limited as long as it does not inhibit the polymerization reaction. Specific examples of the inert solvent include chain aliphatic hydrocarbons such as butane, pentane, hexane and heptane; alicyclic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as benzene, toluene and xylene; And so on. These inert solvents may be used alone or in combination of two or more. The amount of the inert solvent used is not particularly limited, but the monomer concentration is, for example, 1 to 50% by mass, and is preferably 10 to 40% by mass because the effect of the present invention is more excellent. The quantity.

<Polymer initiator>
The polymerization initiator used for the polymerization is not particularly limited as long as it can polymerize a monomer containing a conjugated diene compound to give a conjugated diene-based polymer chain having an active terminal. Specific examples thereof include a polymerization initiator using an organic alkali metal compound, an organic alkaline earth metal compound, a lanthanum series metal compound, or the like as a main catalyst. Examples of the organic alkali metal compound include organic monolithium compounds such as n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, and stillbenzylene; dilithiomethane, 1,4-dilithiobtan, 1, Organic polyvalent lithium compounds such as 4-dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene, 1,3,5-tris (lithiomethyl) benzene; organic sodium compounds such as sodium naphthalene; organic such as potassium naphthalene Potassium compounds; and the like. Examples of the organic alkaline earth metal compound include di-n-butylmagnesium, di-n-hexylmagnesium, diethoxycalcium, calcium distearate, dit-butoxystrontium, diethoxybarium, and diisopropoxy. Examples thereof include barium, diethyl mercaptobarium, dit-butoxybarium, diphenoxybarium, diethylaminobarium, barium distearate, and diketyl barium. Examples of the polymerization initiator using a lanthanum-series metal compound as a main catalyst include lanthanum-series metals such as lanthanum, cerium, placeodim, neodym, samarium, and gadrinium, and lanthanum-series metals composed of carboxylic acids and phosphorus-containing organic acids. Examples thereof include a polymerization initiator composed of the salt of the above as a main catalyst and a co-catalyst such as an alkylaluminum compound, an organic aluminum hydride compound, and an organic aluminum halide compound. Among these polymerization initiators, an organic monolithium compound and an organic polyvalent lithium compound are preferably used, an organic monolithium compound is more preferably used, and n-butyllithium is particularly preferable, because the effect of the present invention is more excellent. It is preferably used.
The organic alkali metal compound is previously reacted with a secondary amine compound such as dibutylamine, dihexylamine, dibenzylamine, pyrrolidine, piperidine, hexamethyleneimine, and heptamethyleneimine to obtain an organic alkali metal amide compound. You may use it. These polymerization initiators may be used alone or in combination of two or more.

Examples of the organic alkali metal amide compound include those obtained by reacting an organic alkali metal compound with a secondary amine compound, and among them, for the reason that the effect of the present invention is more excellent, the following general formula (3) is used. The represented compound can be preferably used.

In the general formula (3), M ¹ represents an alkali metal atom, and R ¹¹ and R ¹² are independently alkyl groups, cycloalkyl groups, aryl groups, aralkyl groups, amino group protective groups, or hydrolysis. R ¹¹ and R ¹² may be bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded, and when the ring structure is formed, they are bonded to each other. In addition to the nitrogen atoms to be bonded, a ring structure may be formed with heteroatoms other than the nitrogen atoms to which they are bonded.

The alkyl group is not particularly limited, but an alkyl group having 1 to 20 carbon atoms is preferable, and an alkyl group having 1 to 10 carbon atoms is more preferable, for the reason that the effect of the present invention is more excellent. Examples of such an alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group and n-. Examples thereof include a xyl group, an n-heptyl group, an n-octyl group and an n-decyl group.

The cycloalkyl group is not particularly limited, but a cycloalkyl group having 3 to 20 carbon atoms is preferable, and a cycloalkyl group having 3 to 12 carbon atoms is more preferable, for the reason that the effect of the present invention is more excellent. Examples of such a cycloalkyl group include a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclododecyl group and the like.

The aryl group is not particularly limited, but an aryl group having 6 to 12 carbon atoms is preferable, and an aryl group having 6 to 10 carbon atoms is more preferable, for the reason that the effect of the present invention is more excellent. Examples of such an aryl group include a phenyl group, a 1-naphthyl group, a 2-naphthyl group and the like.

The aralkyl group is not particularly limited, but an aralkyl group having 7 to 13 carbon atoms is preferable, and an aralkyl group having 7 to 9 carbon atoms is more preferable, for the reason that the effect of the present invention is more excellent. Examples of such an aralkyl group include a benzyl group and a phenethyl group.

The protecting group for the amino group is not particularly limited as long as it is a group that acts as a protecting group for the amino group, and examples thereof include an alkylsilyl group. Examples of such an alkylsilyl group include a trimethylsilyl group, a triethylsilyl group, a triphenylsilyl group, a methyldiphenylsilyl group, an ethylmethylphenylsilyl group, a tert-butyldimethylsilyl group and the like.
When R ¹¹ and / or R ¹² are amino group protecting groups, at one end of the polymer chain forming the obtained conjugated diene rubber by removing the amino group protecting group, A structure in which R ¹³ and / or R ¹⁴ in the general formula (5) described later is a hydrogen atom can be introduced.

The group capable of hydrolyzing to generate a hydroxyl group is not particularly limited, and may be a group that produces a hydroxyl group by hydrolysis in the presence of an acid or the like. For example, an alkoxyalkyl group or an epoxy group. Examples include groups containing.
Examples of the alkoxyalkyl group include a methoxymethyl group, an ethoxymethyl group, an ethoxyethyl group, a propoxymethyl group, a butoxymethyl group, a butoxyethyl group, a propoxyethyl group and the like.
Examples of the group containing an epoxy group include a group represented by the following general formula (4).
-Z ¹ -Z ² -E ¹ (4)
In the general formula (4), Z ¹ is an alkylene group or an alkylarylene group having 1 to 10 carbon atoms, Z ² is a methylene group, a sulfur atom or an oxygen atom, and E ¹ is a glycidyl group.

Further, R ¹¹ and R ¹² may be bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded. In this case, R ¹¹ and R ¹² are formed by the nitrogen atom bonded thereto. Specific examples of the structure to be formed include an azetidine ring (R ¹¹ and R ¹² are propylene groups), a pyrrolidine ring (R ¹¹ and R ¹² are butylene groups), and a piperidine ring (R ¹¹ and R ¹² are pentylene groups). , Hexamethylene imine ring (R ¹¹ and R ¹² are hexylene groups) and the like.
When R ¹¹ and R ¹² are bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded, the ring structure is preferably a 4- to 8-membered ring structure.

Further, in the general formula (3), M ¹ is an alkali metal atom, and examples of such an alkali metal atom include a lithium atom, a sodium atom, and a potassium atom. Among these, from the viewpoint of polymerization activity. , Lithium atom is preferred.

When a compound represented by the general formula (3) is used as the polymerization initiator in the first step, the amine structure forming the organic alkali metal amide compound remains in a state of being bonded to the polymerization initiation terminal of the polymer chain. Will be done. Therefore, when a compound represented by the general formula (3) is used as the polymerization initiator, a structure represented by the following general formula (5) is attached to one end of the polymer chain forming the obtained conjugated diene rubber. Is introduced.

In the general formula (5), R ¹³ and R ¹⁴ can independently generate a hydroxyl group by hydrogen atom, alkyl group, cycloalkyl group, aryl group, aralkyl group, amino group protective group, or hydrolysis. Representing a group, R ¹³ and R ¹⁴ may be bonded to each other to form a ring structure with the nitrogen atom to which they are bonded, and in the case of forming the ring structure, in addition to the nitrogen atom to which they are bonded. , They may form a ring structure together with hetero atoms other than the nitrogen atom to which they are bonded.

Examples of the alkyl group, cycloalkyl group, aryl group, aralkyl group, amino group protective group, or group capable of hydrolyzing to generate a hydroxyl group as R ¹³ and R ¹⁴ are R ¹¹ and R ¹² in the general formula (3). Also, when R ¹³ and R ¹⁴ are bonded to each other to form a ring structure together with the nitrogen atom to which they are bonded, R ¹¹ and R ¹² in the general formula (3) can be mentioned. Can be the same.
The hydrogen atoms that can become R ¹³ and R ¹⁴ are introduced when the protecting group of the amino group is removed.

When an organic alkali metal amide compound is used as the polymerization initiator, the obtained specific conjugated diene rubber has an amine structure at one end and a specific structure derived from the modifier at the other end. Can be. As a result, the effect of the present invention becomes more excellent due to the effect of such an amine structure.

The method of adding the organic alkali metal amide compound as the polymerization initiator to the polymerization system is not particularly limited, and the organic alkali metal compound is reacted with the secondary amine compound in advance to obtain the organic alkali metal amide compound. , This can be mixed with a monomer containing a conjugated diene compound to allow the polymerization reaction to proceed. Alternatively, the organic alkali metal compound and the secondary amine compound are separately added to the polymerization system and mixed with a monomer containing a conjugated diene compound to generate an organic alkali metal amide compound in the polymerization system. Therefore, a method of advancing the polymerization reaction may be adopted. The reaction conditions such as the reaction temperature are not particularly limited, and may be, for example, according to the target polymerization reaction conditions.

The amount of the secondary amine compound used may be determined according to the amount of the desired polymerization initiator added, but is usually 0.01 to 1.5 mmol, preferably 0.1 per 1 mmol of the organic alkali metal compound. It is in the range of ~ 1.2 mmol, more preferably 0.5 ~ 1.0 mmol.

The amount of the polymerization initiator used may be determined according to the molecular weight of the target conjugated diene-based polymer chain, but is usually 1 to 50 mmol, preferably 1.5 to 20 mmol per 1000 g of the monomer. It is preferably in the range of 2 to 15 mmol.

<Polymerization temperature, etc.>
The polymerization temperature is usually −80 to + 150 ° C., preferably 0 to 100 ° C., more preferably 30 to 90 ° C. for the reason that the effect of the present invention is more excellent. As the polymerization mode, any mode such as batch type or continuous type can be adopted, but when the conjugated diene compound and the aromatic vinyl compound are copolymerized, the conjugated diene monomer unit and the aromatic vinyl monomer are used. The batch type is preferable because it is easy to control the randomness of the combination with the unit.

<Polar compound>
When polymerizing a monomer containing a conjugated diene compound, a polar compound is added to an inert organic solvent in order to adjust the vinyl bond content in the conjugated diene monomer unit in the obtained conjugated diene polymer chain. Is preferable. Examples of the polar compound include ether compounds such as dibutyl ether, tetrahydrofuran and 2,2-di (tetrahydrofuryl) propane; tertiary amines such as tetramethylethylenediamine; alkali metal alkoxides; phosphine compounds; and the like. Among these, ether compounds and tertiary amines are preferable, tertiary amines are more preferable, and tetramethylethylenediamine is particularly preferable, for the reason that the effect of the present invention is more excellent. These polar compounds may be used alone or in combination of two or more. The amount of the polar compound to be used may be determined according to the target vinyl bond content, preferably 0.001 to 100 mol, more preferably 0.01 to 10 mol, based on 1 mol of the polymerization initiator. be. When the amount of the polar compound used is in this range, the vinyl bond content in the conjugated diene monomer unit can be easily adjusted, and problems due to deactivation of the polymerization initiator are unlikely to occur.

<Vinyl bond content>
The vinyl bond content in the conjugated diene monomer unit in the conjugated diene polymer chain having an active terminal obtained in the first step is preferably 1 to 90% by mass because the effect of the present invention is more excellent. It is more preferably 3 to 80% by mass, and particularly preferably 5 to 70% by mass.

<Molecular weight>
The weight average molecular weight (Mw) of the conjugated diene polymer chain having an active terminal obtained in the first step is not particularly limited, but is measured by polystyrene-equivalent gel permeation chromatography for the reason that the effect of the present invention is more excellent. The value to be obtained is preferably 100,000 to 1,000,000, more preferably 150,000 to 700,000, and particularly preferably 150,000 to 500,000.

Further, the molecular weight distribution represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the conjugated diene polymer chain having an active terminal obtained in the first step is also particularly limited. Although not, it is preferably 1.0 to 3.0, and more preferably 1.0 to 2.5. When the molecular weight distribution (Mw / Mn) of the conjugated diene polymer chain having an active terminal is within the above range, the conjugated diene rubber can be easily produced.

<Preferable aspect>
The first step is preferably the following step because the effect of the present invention is more excellent.
That is, isoprene, or a monomer containing isoprene and an aromatic vinyl compound, is polymerized with a polymerization initiator in an inert solvent, and isoprene monomer unit 80 to 100% by mass and aromatic vinyl monomer unit 0. Step A for forming the polymer block (A) having an active terminal containing ~ 20% by mass, and
The polymer block (A) having the active terminal is mixed with 1,3-butadiene, or a monomer containing 1,3-butadiene and an aromatic vinyl compound to continue the polymerization reaction, and 1,3 A polymer block (B) having an active terminal containing 50 to 100% by mass of a butadiene monomer unit and 0 to 50% by mass of an aromatic vinyl monomer unit is formed in succession with the polymer block (A). It is preferable that the step B of obtaining a conjugated diene-based polymer chain having an active terminal is provided.

By adopting such a step, the conjugated diene-based polymer chain having an active terminal obtained in the first step can be obtained in an isoprene monomer unit of 80 to 100% by mass and an aromatic vinyl monomer unit of 0 to 20% by mass. The polymer block (A) containing% and the polymer block (B) containing 1,3-butadiene monomer unit 50 to 100% by mass and aromatic vinyl monomer unit 0 to 50% by mass are continuous. (Hereinafter, also referred to as “PI block”) can be included. In this case, the obtained specific conjugated diene rubber also has a PI block.
Hereinafter, such an embodiment will be described.

(Step A)
The polymer block (A) formed in the step A may contain 80 to 100% by mass of an isoprene monomer unit and 0 to 20% by mass of an aromatic vinyl monomer unit in the polymer block (A). However, for the reason that the effect of the present invention is more excellent, it is preferable that the isoprene monomer unit contains 85 to 95% by mass and the aromatic vinyl monomer unit 5 to 15% by mass, and the isoprene monomer unit 89. More preferably, it contains ~ 95% by mass and 5 to 11% by mass of the aromatic vinyl monomer unit.

As the aromatic vinyl compound used to form the aromatic vinyl monomer unit contained in the polymer block (A), the same aromatic vinyl compound as described above can be used, and the effect of the present invention can be obtained. Of these, styrene is preferred for better reasons. In addition, these aromatic vinyl compounds may be used individually by 1 type, and may be used in combination of 2 or more type.

The polymer block (A) is preferably composed of only the isoprene monomer unit, or the isoprene monomer unit and the aromatic vinyl monomer unit, for the reason that the effect of the present invention is more excellent, but it is desirable. Therefore, in addition to the isoprene monomer unit, or the isoprene monomer unit and the aromatic vinyl monomer unit, other monomer units may be contained. Other compounds used to compose other monomeric units include 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1,3. -Pentadiene and conjugated diene compounds other than isoprene such as 1,3-hexadiene; α, β-unsaturated nitriles such as acrylonitrile and methacrylonitrile; unsaturated carboxylic acids such as acrylic acid, methacryl test, and maleic anhydride. Or acid anhydrides; unsaturated carboxylic acid esters such as methyl methacrylate, ethyl acrylate, and butyl acrylate; 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, dicyclopentadiene, and 5 -Ethidiene-2-Non-conjugated diene such as norbornen; etc. Among these, 1,3-butadiene is preferable because the effect of the present invention is more excellent. These other monomers can be used alone or in combination of two or more. The content ratio of the other monomer units in the polymer block (A) is preferably 20% by mass or less, more preferably 10% by mass or less, for the reason that the effect of the present invention is more excellent. , 6% by mass or less is more preferable.

In the present invention, the polymer block (A) in the conjugated diene-based polymer chain is obtained by polymerizing a monomer containing isoprene or an isoprene and an aromatic vinyl compound in an inert solvent with a polymerization initiator. It is formed. The polymer block (A) formed has an active terminal.

As the inert solvent used for polymerizing isoprene or a monomer containing isoprene and an aromatic vinyl compound in order to form the polymer block (A), the same inert solvent as described above may be used. can. The amount of the inert solvent used is such that the monomer concentration is preferably 1 to 80% by mass, more preferably 10 to 50% by mass, for the reason that the effect of the present invention is more excellent. ..

As the polymerization initiator used for forming the polymer block (A), isoprene or a monomer containing isoprene and an aromatic vinyl compound may be polymerized to give a polymer chain having an active terminal. If it can be done, it is not particularly limited. As a specific example thereof, the same polymerization initiator as described above can be used.

The amount of the polymerization initiator used may be determined according to the target molecular weight, but isoprene or 100 g of a monomer containing isoprene or an aromatic vinyl compound is preferable because the effect of the present invention is more excellent. Is in the range of 4 to 250 mmol, more preferably 6 to 200 mmol, and particularly preferably 10 to 70 mmol.

The polymerization temperature when polymerizing isoprene or a monomer containing isoprene and an aromatic vinyl compound is preferably −80 to + 150 ° C., more preferably 0 to 100 ° C., because the effect of the present invention is more excellent. More preferably, it is in the range of 20 to 90 ° C. As the polymerization mode, any mode such as a batch type or a continuous type can be adopted. Further, as the bonding mode, various bonding modes such as a block shape, a tapered shape, and a random shape can be used.

Further, for the reason that the effect of the present invention is more excellent, in order to adjust the vinyl bond content in the isoprene monomer unit in the polymer block (A), a polar compound may be added to the inert solvent during the polymerization. preferable. As the polar compound, the same polar compound as described above can be used. The amount of the polar compound to be used may be determined according to the target vinyl bond content, and is preferably 0.01 to 30 mol, more preferably 0.05 to 10 mol, with respect to 1 mol of the polymerization initiator. When the amount of the polar compound used is within the above range, the vinyl bond content in the isoprene monomer unit can be easily adjusted, and problems due to deactivation of the polymerization initiator are unlikely to occur. Further, by increasing the amount of the polar compound used within the above range, the vinyl bond content in the isoprene monomer unit can be increased.

The vinyl bond content in the isoprene monomer unit in the polymer block (A) is preferably 5 to 90% by mass, more preferably 5 to 80% by mass, for the reason that the effect of the present invention is more excellent. In the present specification, the vinyl bond content in the isoprene monomer unit has an isoprene monomer unit having a 1,2-structure and a 3,4-structure in the isoprene monomer unit. It shall refer to the ratio of the total amount of isoprene monomer units.

The weight average molecular weight (Mw) of the polymer block (A) is preferably 500 to 15,000 as a polystyrene-equivalent value measured by gel permeation chromatography because the effect of the present invention is more excellent. It is more preferably 1000 to 12,000, and particularly preferably 1,500 to 10,000.

Further, the molecular weight distribution represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polymer block (A) is 1.0 because the effect of the present invention is more excellent. It is preferably about 1.5, and more preferably 1.0 to 1.3. When the value (Mw / Mn) of the molecular weight distribution of the polymer block (A) is within the above range, the conjugated diene rubber can be more easily produced.

(Step B)
The polymer block (B) in the conjugated diene polymer chain formed in step B is 50 to 100% by mass of 1,3-butadiene monomer unit and a single amount of aromatic vinyl in the polymer block (B). It may contain 0 to 50% by mass of body units, but for the reason that the effect of the present invention is more excellent, 1,3-butadiene monomer units 52 to 95% by mass and aromatic vinyl monomer units 5 to 5 to It preferably contains 48% by mass. When the content ratio of the 1,3-butadiene monomer unit and the aromatic vinyl monomer unit is within the above range, the production of the conjugated diene rubber becomes easier.

As the aromatic vinyl compound used to form the aromatic vinyl monomer unit contained in the polymer block (B), the same aromatic vinyl compounds as those described above can be used, and among these, the present invention Styrene is preferred because of the greater effect of the invention.

The polymer block (B) is composed of only 1,3-butadiene monomer units, or 1,3-butadiene monomer units and aromatic vinyl monomer units for the reason that the effect of the present invention is more excellent. However, as long as the essential properties in the present invention are not impaired, 1,3-butadiene monomer units, or 1,3-butadiene monomer units and aromatic vinyl monomers are optionally used. In addition to the units, other monomeric units may be included. As the other monomer used to form the other monomer unit, the same compound as the compound exemplified in the above-mentioned polymer block (A) (excluding 1,3-butadiene) is used. be able to. Further, in the polymer block (B), isoprene can be used as another monomer. The content ratio of the other monomer units in the polymer block (B) is preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 35% by mass or less. preferable.

The polymer block (B) in the conjugated diene-based polymer chain contains the above-mentioned polymer block (A) having an active terminal and 1,3-butadiene, or 1,3-butadiene and an aromatic vinyl compound. By mixing the polymer and the polymer and continuing the polymerization reaction, it is formed in succession with the polymer block (A). The polymer block (B) formed has an active terminal. On the other hand, the active terminal disappears from the polymer block (A).

The Inactive used to polymerize the polymer block (A) with a monomer containing 1,3-butadiene, or 1,3-butadiene and an aromatic vinyl compound to form the polymer block (B). The solvent is not particularly limited, and the same solvent as the above-mentioned inert solvent can be used.

The amount of the polymer block (A) having an active terminal used in forming the polymer block (B) may be determined according to the target molecular weight, but for the reason that the effect of the present invention is more excellent, it may be determined. Per 100 g of monomer containing 1,3-butadiene, or 1,3-butadiene and aromatic vinyl compounds, preferably 0.1-5 mmol, more preferably 0.15-2 mmol, even more preferably 0.2. It is in the range of ~ 1.5 mmol.

The method for mixing the polymer block (A) with 1,3-butadiene, or a monomer containing 1,3-butadiene and an aromatic vinyl compound is not particularly limited, and is 1,3-butadiene, or 1,3. -The polymer block (A) having an active end may be added to the solution of the monomer containing butadiene and the aromatic vinyl compound, or 1,3 may be added to the solution of the polymer block (A) having the active end. -Butadiene, or monomers containing 1,3-butadiene and aromatic vinyl compounds may be added. From the viewpoint of controlling polymerization, a method of adding the polymer block (A) having an active terminal to a solution of 1,3-butadiene or a monomer containing 1,3-butadiene and an aromatic vinyl compound is preferable.

The polymerization temperature when polymerizing a monomer containing 1,3-butadiene or a monomer containing 1,3-butadiene and an aromatic vinyl compound is preferably −80 to + 150 ° C., because the effect of the present invention is more excellent. The temperature is preferably in the range of 0 to 100 ° C, more preferably 20 to 90 ° C. As the polymerization mode, any mode such as a batch type or a continuous type can be adopted. When the polymer block (B) is a copolymer chain, a batch type is preferable because it is easy to control the randomness of the bond.

When the polymer block (B) is a copolymer chain, the bonding mode of each monomer can be, for example, various bonding modes such as a block shape, a tapered shape, and a random shape. Among these, the random shape is preferable because the effect of the present invention is more excellent. When the bonding mode of 1,3-butadiene and the aromatic vinyl compound is randomized, the total amount of 1,3-butadiene and the aromatic vinyl compound in the polymerization system is due to the superior effect of the present invention. 1,3-butadiene or 1,3-butadiene and the aromatic vinyl compound are continuously or intermittently supplied into the polymerization system for polymerization so that the ratio of the aromatic vinyl compound to the amount does not become too high. Is preferable.

Further, for the reason that the effect of the present invention is more excellent, a single amount of isoprene in the polymer block (A) is used to adjust the vinyl bond content in the 1,3-butadiene monomer unit in the polymer block (B). As in the case of adjusting the vinyl bond content in the body unit, it is preferable to add a polar compound to the inert solvent during the polymerization. However, when preparing the polymer block (A), an amount of polar compound sufficient to adjust the vinyl bond content in the 1,3-butadiene monomer unit in the polymer block (B) was added to the inert solvent. When is added, it is not necessary to add a new polar compound. As the polar compound used for adjusting the vinyl bond content, the same polar compound as described above can be used. The amount of the polar compound used may be determined according to the desired vinyl bond content, and the polymerization initiation used in the initial polymerization reaction (polymerization reaction for forming the first polymer block (A)) may be started. It may be adjusted in the range of preferably 0.01 to 100 mol, more preferably 0.1 to 30 mol, with respect to 1 mol of the agent. When the amount of the polar compound used is within this range, the vinyl bond content in the 1,3-butadiene monomer unit can be easily adjusted, and problems due to deactivation of the polymerization initiator are unlikely to occur.

The vinyl bond content in the 1,3-butadiene monomer unit in the polymer block (B) is preferably 1 to 90% by mass, more preferably 3 to 80% by mass because the effect of the present invention is more excellent. , Particularly preferably 5 to 70% by mass.

In this way, a conjugated diene-based polymer chain having an active terminal having a polymer block (A) and a polymer block (B) can be obtained. From the viewpoint of productivity, the conjugated diene-based polymer chain having an active end is composed of a polymer block (A) and a polymer block (B), and the end of the polymer block (B) is the active end. It is preferable, but it may have a plurality of polymer blocks (A) or may have other polymer blocks. For example, a conjugated diene-based polymer chain having an active terminal such as polymer block (A) -polymer block (B) -polymer block (A) can be mentioned. In this case, the active terminal is formed at the end of the polymer block (A) formed following the polymer block (B). When the polymer block (A) is formed on the active terminal side of the conjugated diene-based polymer chain, the amount of isoprene used is determined by the initial polymerization reaction (first polymer block) because the effect of the present invention is more excellent. It is preferably 10 to 100 mol, more preferably 15 to 70 mol, and 20 to 35 mol with respect to 1 mol of the polymerization initiator used in (polymerization reaction for forming (A)). Is particularly preferred.

Mass ratio of polymer block (A) to polymer block (B) in a conjugated diene polymer chain having an active terminal (when a plurality of polymer blocks (A) and polymer blocks (B) are present, each (Mass ratio based on the total mass of) is 0.001 to 0 in (mass of polymer block (A)) / (mass of polymer block (B)) because the effect of the present invention is more excellent. It is preferably 0.1, more preferably 0.003 to 0.07, and particularly preferably 0.005 to 0.05.

With the total monomer unit of the isoprene monomer unit and the 1,3-butadiene monomer unit in the conjugated diene polymer chain having the polymer block (A) and the polymer block (B) and having an active terminal. , The content ratio with the aromatic vinyl monomer unit is the isoprene monomer unit and the 1,3-butadiene monomer in the conjugated diene polymer chain having an active terminal because the effect of the present invention is more excellent. The total monomer unit is preferably 50 to 100% by mass and the aromatic vinyl monomer unit is preferably 0 to 50% by mass, and the total unit amount of the isoprene monomer unit and the 1,3-butadiene monomer unit is sufficient. More preferably, the body unit is 52 to 95% by mass, and the aromatic vinyl monomer unit is 5 to 48% by mass. Further, vinyl bonds in the isoprene monomer unit and the 1,3-butadiene monomer unit in the conjugated diene-based polymer chain having the polymer block (A) and the polymer block (B) and having an active terminal. The content is preferably in the same range as the vinyl bond content in the 1,3-butadiene monomer unit in the polymer block (B) described above, for the reason that the effect of the present invention is more excellent.

[Second step]
In the second step, the polymerization initiator 1 in which the polyorganosiloxane represented by the following general formula (1) was used in the conjugated diene polymer chain having the active terminal obtained in the first step in the first step. This is a step of adding and reacting the siloxane structure (-Si-O-) in the polyorganosiloxane at a ratio of 1 mol or more in terms of the number of repeating units to the molars.

In the general formula (1), R ¹ to R ⁸ are an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and these may be the same or different from each other. X ¹ and X ⁴ are composed of an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and a group having 4 to 12 carbon atoms containing an epoxy group. Any group selected from the group, which may be the same or different from each other. X ² is an alkoxy group having 1 to 5 carbon atoms or a group having 4 to 12 carbon atoms containing an epoxy group, and a plurality of X ² may be the same as or different from each other. X ³ is a group containing repeating units of 2 to 20 alkylene glycols, and when there are a plurality of X ³ , they may be the same or different from each other. m is an integer of 3 to 200, n is an integer of 0 to 200, k is an integer of 0 to 200, and m + n + k is 3 or more.

In the polyorganosiloxane represented by the general formula (1), examples of the alkyl group having 1 to 6 carbon atoms capable of forming R ¹ to R ⁸ , X ¹ and X ⁴ in the general formula (1) are methyl. Examples thereof include a group, an ethyl group, an n-propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group and a cyclohexyl group. Examples of the aryl group having 6 to 12 carbon atoms include a phenyl group and a methylphenyl group. Among these, a methyl group and an ethyl group are preferable from the viewpoint of easiness of producing the polyorganosiloxane itself.

Further, in the polyorganosiloxane represented by the general formula (1), examples of the alkoxy group having 1 to 5 carbon atoms that can constitute X ¹ , X ² and X ⁴ include a methoxy group, an ethoxy group, and a propoxy group. Examples thereof include an isopropoxy group and a butoxy group. Among these, a methoxy group and an ethoxy group are preferable from the viewpoint of easiness of producing the polyorganosiloxane itself.

Further, in the polyorganosiloxane represented by the general formula (1), examples of the group having 4 to 12 carbon atoms containing an epoxy group capable of forming X ¹ , X ² and X ⁴ include the following general formula (6). ) Can be mentioned.
-Z ³ -Z ⁴ -E ² (6)
In the general formula (6), Z ³ is an alkylene group or an alkylarylene group having 1 to 10 carbon atoms, Z ⁴ is a methylene group, a sulfur atom, or an oxygen atom, and E ² is a carbon having an epoxy group. It is a hydrocarbon group of several 2 to 10.

As the group represented by the general formula (6), it is preferable that Z ⁴ is an oxygen atom, Z ⁴ is an oxygen atom, and E ² is a glycidyl group, for the reason that the effect of the present invention is more excellent. Some are more preferable, and Z ³ is an alkylene group having 1 to 3 carbon atoms, Z ⁴ is an oxygen atom, and E ² is a glycidyl group.

Further, in the polyorganosiloxane represented by the general formula (1), X ¹ and X ⁴ are groups having 4 to 12 carbon atoms containing an epoxy group for the reason that the effect of the present invention is more excellent than the above. , Or an alkyl group having 1 to 6 carbon atoms is preferable. Further, as X2, among the above, a group having ⁴ to 12 carbon atoms containing an epoxy group is preferable because the effect of the present invention is more excellent. Further, for the reason that the effect of the present invention is more excellent, it is more preferable that X ¹ and X ⁴ are alkyl groups having 1 to 6 carbon atoms and X ² is a group having 4 to 12 carbon atoms containing an epoxy group. ..

Further, in the polyorganosiloxane represented by the general formula (1), as a group containing a repeating unit of X ³ , that is, 2 to 20 alkylene glycols, the following general formula (1) is given because the effect of the present invention is more excellent. The group represented by 7) is preferable.

In the general formula (7), t is an integer of 2 to 20, X ⁵ is an alkylene group or an alkylarylene group having 2 to 10 carbon atoms, R ¹⁵ is a hydrogen atom or a methyl group, and X ⁶ is a carbon. The number 1 to 10 is an alkoxy group or an aryloxy group. Among these, it is preferable that t is an integer of 2 to 8, X ⁵ is an alkylene group having 3 carbon atoms, R ¹⁵ is a hydrogen atom, and X ⁶ is a methoxy group. In the general formula (7), * is a coupling position.

In the polyorganosiloxane represented by the general formula (1), m is an integer of 3 to 200, preferably an integer of 20 to 150, and more preferably an integer of 30 to 120. When m is 3 or more, the coupling rate of the obtained conjugated diene rubber is high, and as a result, the effect of the present invention is more excellent. Further, when m is 200 or less, the polyorganosiloxane itself represented by the general formula (1) can be more easily produced, its viscosity does not become too high, and it becomes easier to handle.

Further, in the polyorganosiloxane represented by the general formula (1), n is an integer of 0 to 200, preferably an integer of 0 to 150, and more preferably an integer of 0 to 120. k is an integer of 0 to 200, preferably an integer of 0 to 150, and more preferably an integer of 0 to 130. The total number of m, n and k is 3 or more, preferably 3 to 400, more preferably 20 to 300, and particularly preferably 30 to 250. When the total number of m, n and k is 3 or more, the reaction between the polyorganosiloxane represented by the general formula (1) and the conjugated diene polymer chain having an active terminal is likely to proceed, and further, m, When the total number of n and k is 400 or less, the polyorganosiloxane itself represented by the general formula (1) can be easily produced, its viscosity does not become too high, and it is easy to handle.

The amount of polyorganosiloxane used in the second step is the number of repeating units of the siloxane structure (-Si-O-) in the polyorganosiloxane with respect to 1 mol of the polymerization initiator used for polymerization in the first step described above. It is preferably 1 to 2.5 mol, more preferably 1.1 to 2 mol, for the reason that the effect of the present invention is more excellent.

By setting the amount of polyorganosiloxane used to 1 mol or more in terms of the number of repeating units of the siloxane structure (-Si-O-) with respect to 1 mol of the polymerization initiator, the active terminal obtained in the first step can be obtained. Of the active ends of the conjugated diene-based polymer chain having, substantially all the active ends can be reacted with polyorganosiloxane, which is preferable. That is, the alkyl metal group as the active end of the conjugated diene polymer chain having the active end obtained in the first step, that is, -R ^- M ⁺ (R is a hydrocarbon group forming the polymer chain end). , M can be in a state in which a group represented by an alkali metal atom, an alkaline earth metal atom, or a lanthanum series metal atom) does not substantially remain.

As a result, when the compound represented by the general formula (2) is reacted in the third step described later, the compound represented by the general formula (2) is the active terminal obtained by the first step. It is possible to substantially suppress the direct reaction with the active end of the conjugated diene polymer chain having. As a result, with respect to the reaction residue generated by reacting the compound represented by the general formula (2) with the conjugated diene polymer chain and the polyorganosiloxane represented by the general formula (1). It can be reacted appropriately. As a result, a modified structure of the compound represented by the general formula (2) is appropriately introduced into the conjugated diene-based polymer chain via the structure derived from the polyorganosiloxane represented by the general formula (1). It is possible to realize the effect of introducing such a modified structure, that is, excellent wet performance, rolling performance and workability.

The method for reacting the polyorganosiloxane with the conjugated diene polymer chain having an active terminal is not particularly limited, and examples thereof include a method of mixing these in a solvent in which each of them can be dissolved. As the solvent used at this time, those exemplified as the inert solvent used in the first step described above can be used. Further, in this case, a method of adding polyorganosiloxane to the polymerization solution used for the polymerization for obtaining the conjugated diene-based polymer chain having an active terminal is convenient and preferable. In this case, the polyorganosiloxane is preferably dissolved in an inert solvent and added to the polymerization system, and the solution concentration is preferably in the range of 1 to 50% by mass. The reaction temperature is not particularly limited, but is usually 0 to 120 ° C., and the reaction time is also not particularly limited, but is usually 1 minute to 1 hour.

The timing of adding the polyorganosiloxane to the solution containing the conjugated diene polymer chain having an active end is not particularly limited, but the polymerization reaction is not completed and the conjugated diene polymer chain having an active end is contained. In a state where the solution to be prepared also contains a monomer, more specifically, a solution containing a conjugated diene polymer chain having an active terminal is a single amount of 100 ppm or more, more preferably 300 to 50,000 ppm. It is desirable to add the polyorganosiloxane to this solution with the body contained. By adding the polyorganosiloxane in this way, it is possible to suppress side reactions between the conjugated diene polymer chain having an active terminal and impurities contained in the polymerization system, and to control the reaction satisfactorily. It becomes.

In the second step, polyorganosiloxane as a modifier is reacted with the active end of the conjugated diene-based polymer chain having the active end obtained in the first step described above, but the conjugated diene-based weight The active end of the coalesced chain will react with the silicon atom in the siloxane structure. Alternatively, a part of the active terminals of the conjugated diene polymer chain is an alkoxy group or an epoxy group of the side chain of the polyorganosiloxane (an alkoxy group or an epoxy group forming X2 which is included as essential in the general formula ( ¹ )). It will react with the group etc.). Then, according to the second step, a modified structure with siloxane is introduced into the conjugated diene-based polymer chain by such a reaction.

Specifically, the active end of the conjugated diene polymer chain reacts with the silicon atom in the siloxane structure, so that the conjugated diene polymer chain is formed by the silicon atom in the siloxane structure and the conjugated diene polymer chain. A new bond is formed between the active end and the modified structure by siloxane is introduced at the end of the conjugated diene polymer chain, and the oxygen atom in the siloxane structure and the active end of the conjugated diene polymer chain are introduced. A group represented by -O ^- M ⁺ (M is an alkali metal atom, an alkaline earth metal atom, or a lanthanum series metal atom) as these reaction residues with the metal atom forming the above. Is considered to be formed.

Alternatively, the active end of the conjugated diene polymer chain reacts with the epoxy group of the side chain of the polyorganosiloxane to open the epoxy group, and the carbon atom of the portion where the epoxy group is opened and the conjugated diene weight. A new bond is formed with the active end of the coalesced chain, a siloxane structure is introduced at the end of the conjugated diene polymer chain, and the oxygen atom in the epoxy group and the activity of the conjugated diene polymer chain are active. It is considered that a group represented by −O ⁻ M ⁺ is formed as these reaction residues with the metal atom forming the terminal. Alternatively, the active end of the conjugated diene polymer chain reacts with the alkoxy group of the side chain of the polyorganosiloxane to eliminate the alkoxy group, and the conjugated diene polymer chain is conjugated with the silicon atom in the siloxane structure. A new bond is formed at the active end of the diene-based polymer chain, and a siloxane structure is introduced at the end of the conjugated diene-based polymer chain.

In particular, in the second step, the amount of polyorganosiloxane used is 1 mol or more in terms of the number of repeating units of the siloxane structure (-Si-O-) with respect to 1 mol of the polymerization initiator. Among the conjugated diene-based polymer chains having active terminals obtained in the first step, a modified structure with siloxane can be introduced into almost all the conjugated diene-based polymer chains. Therefore, the alkyl metal group as the active terminal of the conjugated diene-based polymer chain having the active terminal obtained in the first step, that is, -R ^- M ⁺ , can be brought into a state in which almost all of them do not remain. Instead, a group represented by −O ⁻ M ⁺ as a reaction residue will be formed. However, in the present invention, if it is a very small amount (for example, 5% by mass or less), it may contain a conjugated diene polymer chain having an unmodified active terminal that has not been modified with siloxane (for example, 5% by mass or less). That is, if the amount is very small, the alkyl metal group as the active terminal of the conjugated diene-based polymer chain having the active terminal obtained in the first step, that is, the one in which -R ^- M ⁺ remains is contained. Often), it does not rule out such cases.

In the second step, the effect of the present invention is not impaired in the state before the polyorganosiloxane represented by the general formula (1) is reacted with the conjugated diene polymer chain having an active terminal. , Even if a part of the active end of the conjugated diene polymer chain having an active end is added to the polymerization system with a coupling agent or a modifier which is usually used conventionally to perform coupling or modification. good.

[Third step]
The third step is a step of reacting the conjugated diene polymer chain obtained by reacting the polyorganosiloxane obtained in the second step with a compound represented by the following general formula (2).

In the general formula (2), R ⁹ is a hydrocarbyl group, and A ¹ is a group capable of reacting with a reaction residue generated by a reaction between a conjugated diene polymer chain having an active terminal and a polyorganosiloxane. , A ² is a group containing a nitrogen atom, p is an integer of 0 to 2, q is an integer of 1 to 3, r is an integer of 1 to 3, and p + q + r = 4.

According to the present invention, in the above-mentioned second step, substantially of the alkyl metal group as the active end of the conjugated diene polymer chain having the active end obtained in the first step, that is, −R ⁻ M ⁺ . It is assumed that all of them are in a state where they do not remain, and instead, they have a group represented ^by −OM ⁺ as a reaction residue by the reaction with the polyorganosiloxane represented by the general formula (1). Therefore, according to the third step of the present invention, the compound represented by the general formula (2) has a group (−O ⁻ M ⁺ ) represented by −O ⁻ M ⁺ as such a reaction residue. It can be appropriately reacted with (including those in which the represented group is hydrolyzed and converted into a hydroxyl group).

That is, according to the present invention, the compound represented by the general formula (2) reacts with the group represented by −R ⁻ M ⁺ , so that the conjugated diene polymer chain is directly subjected to the general formula. It is possible to appropriately suppress the introduction of the modified structure due to the compound represented by (2), whereby the conjugated diene-based polymer chain becomes a polyorganosiloxane represented by the general formula (1). The modified structure of the compound represented by the general formula (2) can be appropriately introduced through the derived structure. As a result, excellent wet performance, rolling performance and workability can be realized.

However, the conjugated diene polymer chain obtained by reacting the polyorganosiloxane used in the third step may be one that has undergone the second step described above, and is a conjugated diene polymer having a modified structure with siloxane introduced therein. In addition to the chains, if the amount is very small (for example, 5% by mass or less), a conjugated diene polymer chain having an unmodified active terminal into which a siloxane-modified structure has not been introduced may remain (for example, 5% by mass or less). That is, if the amount is very small, the alkyl metal group as the active terminal of the conjugated diene polymer chain having the active terminal obtained in the first step, that is, the one in which -R ^- M ⁺ remains is contained. In addition, a part of −O ⁻ M ⁺ as a reaction residue formed as a result of introducing a modified structure with siloxane was hydrolyzed and converted into a hydroxyl group. May be good.

In the compound represented by the general formula (2), R ⁹ in the general formula (2) is a hydrocarbyl group, and examples thereof include an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group and an aralkyl group. , An alkyl group having 1 to 6 carbon atoms is preferable because the effect of the present invention is more excellent. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group and the like, and among these, the effect of the present invention is more effective. A methyl group and an ethyl group are more preferable for excellent reasons.

In the compound represented by the general formula (2), A ¹ in the general formula (2) is a reaction residue (typically) generated by the reaction of a conjugated diene polymer chain having an active terminal with polyorganosiloxane. Is a group ^capable of reacting with −O ⁻ M ⁺ ), and is preferably a group represented by −OR ¹⁰ (R10 is a hydrogen atom or a hydrocarbyl group). Examples of the hydrocarbyl group that can constitute R ¹⁰ include an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an aralkyl group and the like, and from the viewpoint of reactivity with the above reaction residue, the number of carbon atoms is 1 to 1. It is preferably an alkyl group of 6. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group and the like, and among these, the effect of the present invention is more effective. A methyl group and an ethyl group are more preferable for excellent reasons.

In the compound represented by the general formula (2), A ² in the general formula (2) is a group containing a nitrogen atom, and is not particularly limited as long as it is a group containing a nitrogen atom, but has a nitrogen atom. It is preferably an organic group, for example, 3-aminopropyl group, 4-aminobutyl group, 3- (2-aminoethylamino) propyl group, 2-dimethylaminoethyl group, 3-dimethylaminopropyl group, 3- Diethylaminopropyl group, 3-dipropylaminopropyl group, 3-dibutylaminopropyl group, 3-phenylmethylaminopropyl group, 3- (4-methylpiperazinyl) propyl group, N, N-bis (trimethylsilyl) aminopropyl Examples include groups, N, N-bis (triethylsilyl) aminopropyl groups, N, N', N'-tris (trimethylsilyl) -N- (2-aminoethyl) -3-aminopropyl groups and the like. Among these, primary amino groups having an active hydrogen atom, such as 3-aminopropyl group, 4-aminobutyl group, and 3- (2-aminoethylamino) propyl group, and primary amino groups having an active hydrogen atom, for the reason that the effect of the present invention is more excellent. / Or a group containing a secondary amino group having an active hydrogen atom is preferable. The "active hydrogen atom" refers to a hydrogen atom bonded to an atom other than a carbon atom, and preferably has a lower bond energy than the carbon-hydrogen bond of a polymethylene chain.

In the compound represented by the general formula (2), p is an integer of 0 to 2, q is an integer of 1 to 3, r is an integer of 1 to 3, and p + q + r = 4. From the viewpoint of reactivity between the conjugated diene polymer chain having an active terminal and the reaction residue generated by the reaction with polyorganosiloxane, p is preferably an integer of 0 to 1 and q is an integer of 2 to 3. Yes, r is an integer of 1-2, more preferably p = 0, q = 3, r = 1. When p is 2, the groups represented by R ⁹ contained in one molecule of the compound represented by the general formula (2) may be the same or different from each other. It may be. Similarly, when q is 2 or 3, the groups represented by A1 contained in ^a plurality of compounds represented by the general formula (2) may be the same or mutually. It may be different, and when r is 2 or 3, the groups represented by A ² contained in one molecule of the compound represented by the general formula (2) are the same. It may be different from each other.

Specific examples of the compound represented by the general formula (2) are not particularly limited, but for example, A ² in the general formula (2) is a primary amino group having an active hydrogen atom and / or an active hydrogen atom. As a compound which is a group containing a secondary amino group, 3-aminopropyldimethylmethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyldimethylethoxysilane, 3-aminopropyl Compounds having a 3-aminopropyl group as ^A2 such as methyldiethoxysilane and 3-aminopropyltriethoxysilane; 4-aminobutyldimethylmethoxysilane, 4-aminobutylmethyldimethoxysilane, 4-aminobutyltrimethoxysilane , 4-Aminobutyldimethylethoxysilane, 4-aminobutylmethyldiethoxysilane, 4-aminobutyltriethoxysilane, and other compounds having a 4-aminobutyl group as A2; 3- ( ² -aminoethylamino) propyldimethyl Methoxysilane, 3- (2-aminoethylamino) propylmethyldimethoxysilane, 3- (2-aminoethylamino) propyltrimethoxysilane, 3- (2-aminoethylamino) propyldimethylethoxysilane, 3- (2-) Examples of A2 such as aminoethylamino) propylmethyldiethoxysilane and 3- ( ² -aminoethylamino) propyltriethoxysilane; include compounds having a 3- (2-aminoethylamino) propyl group; and the like.

Further, as a compound in which A ² in the general formula (2) is a group other than a primary amino group having an active hydrogen atom and / or a group containing a secondary amino group having an active hydrogen atom, 3-dimethylamino. Propyltrimethoxysilane, 3-dimethylaminopropylmethyldimethoxysilane, 3-dimethylaminopropyldimethylmethoxysilane, 3-dimethylaminopropyltriethoxysilane, 3-dimethylaminopropylmethyldiethoxysilane, 3-dimethylaminopropyldimethylethoxysilane Such as A ² , a compound having a 3-dimethylaminopropyl group; 3-diethylaminopropyltrimethoxysilane, 3-diethylaminopropylmethyldimethoxysilane, 3-diethylaminopropyldimethylmethoxysilane, 3-diethylaminopropyltriethoxysilane, 3- Compounds having a 3-diethylaminopropyl group as ^A2 such as diethylaminopropylmethyldiethoxysilane and 3-diethylaminopropyldimethylethoxysilane; 3-dipropylaminopropyltrimethoxysilane, 3-dipropylaminopropylmethyldimethoxysilane, 3 -As ^A2 of dipropylaminopropyldimethylmethoxysilane, 3-dipropylaminopropyltriethoxysilane, 3-dipropylaminopropylmethyldiethoxysilane, 3-dipropylaminopropyldimethylethoxysilane, etc., 3-dipropylamino Compounds with propyl groups; 3-dibutylaminopropyltrimethoxysilane, 3-dibutylaminopropylmethyldimethoxysilane, 3-dibutylaminopropyldimethylmethoxysilane, 3-dibutylaminopropyltriethoxysilane, 3-dibutylaminopropylmethyldiethoxy Compounds having a 3-dibutylaminopropyl group as ^A2 such as silane, 3-dibutylaminopropyldimethylethoxysilane; 3-phenylmethylaminopropyltrimethoxysilane, 3-phenylmethylaminopropylmethyldimethoxysilane, 3-phenylmethyl A 3-phenylmethylaminopropyl group is used as ^A2 of aminopropyldimethylmethoxysilane, 3-phenylmethylaminopropyltriethoxysilane, 3-phenylmethylaminopropylmethyldiethoxysilane, 3-phenylmethylaminopropyldimethylethoxysilane, etc. Compounds; 3- (4-Methylpiperadi) Nyl) propyltrimethoxysilane, 3- (4-methylpiperazinyl) propylmethyldimethoxysilane, 3- (4-methylpiperazinyl) propyldimethylmethoxysilane, 3- (4-methylpiperazinyl) propyltriethoxy 3- (4-Methylpiperazinyl) propyl group as ^A2 such as silane, 3- (4-methylpiperazinyl) propylmethyldiethoxysilane, 3- (4-methylpiperazinyl) propyldimethylethoxysilane, etc. Compounds with;

N, N-bis (trimethylsilyl) aminopropyltrimethoxysilane, N, N-bis (trimethylsilyl) aminopropyltriethoxysilane, N, N-bis (trimethylsilyl) aminopropylmethyldimethoxysilane, N, N-bis (trimethylsilyl) Compounds having N, N-bis (trimethylsilyl) aminopropyl group as ^A2 such as aminopropylmethyldiethoxysilane; N, N-bis (triethylsilyl) aminopropyltrimethoxysilane, N, N-bis (trimethylsilyl) N, N-bis (triethylsilyl) as ^A2 of aminopropyltriethoxysilane, N, N-bis (triethylsilyl) aminopropylmethyldimethoxysilane, N, N-bis (triethylsilyl) aminopropylmethyldiethoxysilane, etc. ) Compounds with aminopropyl groups; N, N', N'-tris (trimethylsilyl) -N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N, N', N'-tris (trimethylsilyl) -N- (2-aminoethyl) -3-aminopropyltriethoxysilane, N, N', N'-tris (trimethylsilyl) -N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N, As ^A2 such as N', N'-tris (trimethylsilyl) -N- (2-aminoethyl) -3-aminopropylmethyldiethoxysilane, N, N', N'-tris (trimethylsilyl) -N- ( 2-Aminoethyl) -3-aminopropyl group-bearing compounds; and the like.

The amount of the compound represented by the general formula (2) is not particularly limited, but is preferably 0.1 with respect to 1 mol of the polymerization initiator used in the first step because the effect of the present invention is more excellent. It is ~ 5 mol, more preferably 0.2 ~ 2 mol, still more preferably 0.4 ~ 1.5 mol.

The timing for adding the compound represented by the general formula (2) to the solution containing the conjugated diene polymer chain is after the addition of the polyorganosiloxane represented by the general formula (1) in the second step described above. If so, there is no particular limitation. For example, as in the second step described above, the polymerization reaction is not completed, and the solution containing the conjugated diene polymer chain also contains the monomer, more specifically, the conjugated diene. The compound represented by the general formula (2) is added to this solution in a state where the solution containing the system polymer chain contains 100 ppm or more, more preferably 300 to 50,000 ppm of monomer. Can be done. By adding the compound represented by the general formula (2) in this way, side reactions between the conjugated diene polymer chain and impurities contained in the polymerization system are suppressed, and the reaction is satisfactorily controlled. It becomes possible. Alternatively, by adding an alcohol such as water or methanol to the solution containing the conjugated diene polymer chain before or after adding the compound represented by the general formula (2), the solution can be used. A modification reaction in a state where the group represented by −O ⁻ M ⁺ as a reaction residue formed by the reaction with the polyorganosiloxane represented by the general formula (1) is hydrolyzed and converted into a hydroxyl group. May be done. When the compound represented by the general formula (2) is added to the solution containing the conjugated diene polymer chain, the compound represented by the general formula (2) may be added after being dissolved in the inert solvent. However, it may be added directly without being dissolved in the inert solvent. The reaction temperature and reaction time are the same as in the first step.

Then, after reacting the compound represented by the general formula (2), if necessary, a known polymerization terminator or the like is added to inactivate the reaction system, and then, if desired, a phenol-based stabilizer. , Anti-aging agents such as phosphorus-based stabilizers and sulfur-based stabilizers, crumbing agents, and anti-scale agents are added to the reaction solution, and then the polymerization solvent is separated from the reaction solution by direct drying or steam stripping. Then, the conjugated diene-based rubber is collected. Before separating the polymerization solvent from the reaction solution, a spreading oil may be mixed with the polymerization solution and the conjugated diene rubber may be recovered as the oil spreading rubber.

Examples of the spreading oil used when recovering the conjugated diene-based rubber as an oil-extended rubber include paraffin-based, aromatic and naphthen-based petroleum-based softeners, plant-based softeners, and fatty acids. When a petroleum-based softener is used, the content of polycyclic aromatics extracted by the method of IP346 (inspection method of THE INSTITUTE PETROLEUM in the United Kingdom) is preferably less than 3%. When the spreading oil is used, the amount used is preferably 5 to 100 parts by mass, more preferably 10 to 60 parts by mass, and further preferably 20 to 50 parts by mass with respect to 100 parts by mass of the conjugated diene rubber. ..

As described above, in the specific conjugated diene-based rubber, the polyorganosiloxane represented by the general formula (1) as a modifier in the above-mentioned second step is used with respect to 1 mol of the polymerization initiator used in the first step. Then, the siloxane structure (-Si-O-) in the polyorganosiloxane is added at a ratio of 1 mol or more in terms of the number of repeating units to carry out the reaction, and then, in the above-mentioned third step, it is generally used as a modifier. It is obtained by carrying out the reaction using the compound represented by the formula (2). Therefore, the specific conjugated diene rubber includes one in which a modified structure by siloxane and a modified structure by a compound represented by the general formula (2) are introduced at the end of the polymer chain. , The polymer chain terminal may include one in which only a modified structure with siloxane is introduced. Further, as long as the effect of the present invention is not impaired, for example, only the modified structure by the compound represented by the general formula (2) is introduced at the end of the polymer chain, or any modified structure is introduced. It may contain something that does not exist. In particular, in the present invention, from the viewpoint of more appropriately realizing the effects of the present invention, a modified structure with siloxane and a modified structure with a compound represented by the general formula (2) are introduced at the end of the polymer chain. The ratio is preferably 10% by mass or more, and more preferably 20% by mass or more. The upper limit is not particularly limited.

[Monomer unit content]
The specific conjugated diene-based rubber preferably contains 50 to 100% by mass of the conjugated diene monomer unit, more preferably 52 to 95% by mass, and is aromatic because the effect of the present invention is more excellent. Those containing 0 to 50% by mass of a vinyl monomer unit (particularly a styrene monomer unit) are preferable.

[Vinyl bond content]
The vinyl bond content in the conjugated diene monomer unit in the specific conjugated diene rubber is preferably 1 to 90% by mass, more preferably 3 to 80% by mass, and particularly preferably 3 to 80% by mass because the effect of the present invention is more excellent. It is 5 to 70% by mass.

[Coupling rate]
The coupling ratio of the specific conjugated diene rubber is not particularly limited, but is preferably 10% by mass or more, more preferably 20% by mass or more, and particularly preferably 40% by mass or more because the effect of the present invention is more excellent. It is preferably 80% by mass or less, more preferably 75% by mass or less, and particularly preferably 70% by mass or less. The coupling rate is determined by reacting with a polyorganosiloxane represented by the general formula (1), a compound represented by the general formula (2), and a coupling agent or other modifier used as necessary. It is the mass fraction of the polymer molecule having a molecular weight of 1.8 times or more the peak top molecular weight of the conjugated diene polymer chain having the previous active end with respect to the total amount of the finally obtained conjugated diene rubber. The molecular weight at this time shall be determined as a polystyrene-equivalent molecular weight by gel permeation chromatography.

[Molecular weight]
The weight average molecular weight (Mw) of the specific conjugated diene rubber is a value measured by gel permeation chromatography in terms of polystyrene, which is more than 100,000. Among them, it is preferably more than 100,000 and 3,000,000 or less, more preferably 150,000 to 2,000,000, and particularly preferably 200,000 to 1,500,000. By setting the weight average molecular weight of the conjugated diene rubber within the above range, silica can be easily blended into the conjugated diene rubber, the processability of the rubber composition can be further improved, and the effects of the present invention can be further improved. Will be better.

The molecular weight distribution represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the specific conjugated diene rubber is 1.1 to 3. It is preferably 0, more preferably 1.2 to 2.5, and particularly preferably 1.2 to 2.2.

〔viscosity〕
Further, the Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the specific conjugated diene rubber is preferably 20 to 100, more preferably 30 to 90, and particularly preferably 35 to 80 because the effect of the present invention is more excellent. .. When the conjugated diene rubber is an oil-extended rubber, the Mooney viscosity of the oil-extended rubber is preferably in the above range.

〔Content〕
As described above, the content of the specific conjugated diene rubber in the conjugated diene rubber is 10% by mass or more.
The upper limit of the content of the specific conjugated diene rubber in the conjugated diene rubber is not particularly limited and is 100% by mass. The content of the specific conjugated diene rubber in the conjugated diene rubber is preferably 30 to 90% by mass, more preferably 50 to 80% by mass, for the reason that the effect of the present invention is more excellent.

[Other rubber components]
The conjugated diene-based rubber may contain a rubber component (other rubber component) other than the specific conjugated diene-based rubber. Such other rubber components include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), and the like. Examples thereof include butyl halide rubber (Br-IIR, Cl-IIR) and chloroprene rubber (CR). Of these, butadiene rubber (BR) is preferable because the effect of the present invention is more excellent.
The weight average molecular weight (Mw) of the other rubber components is a value measured by gel permeation chromatography in terms of polystyrene, which is more than 100,000. Among them, it is preferably more than 100,000 and 3,000,000 or less, more preferably 150,000 to 2,000,000, and particularly preferably 200,000 to 1,500,000. By setting the weight average molecular weight of the other rubber components within the above range, silica can be easily blended into the conjugated diene-based rubber, the processability of the rubber composition can be further improved, and the effects of the present invention can be further improved. Will be better.
The content of other rubber components in the conjugated diene rubber is not particularly limited, but is preferably 0 to 50% by mass, more preferably 10 to 40% by mass, for the reason that the effect of the present invention is more excellent. preferable.

[Molecular weight]
The weight average molecular weight (Mw) of all the rubber components contained in the conjugated diene rubber is a value measured by gel permeation chromatography in terms of polystyrene, which is more than 100,000. Among them, it is preferably more than 100,000 and 3,000,000 or less, more preferably 150,000 to 2,000,000, and particularly preferably 200,000 to 1,500,000. By setting the weight average molecular weight of the rubber component within the above range, it becomes easy to mix silica into the conjugated diene-based rubber, the processability of the rubber composition can be further improved, and the effect of the present invention is further enhanced. It will be excellent.

[2] Silica The silica contained in the composition of the present invention is not particularly limited, and any conventionally known silica blended in the rubber composition for applications such as tires can be used.
Examples of the silica include wet silica, dry silica, fumed silica, and diatomaceous earth. As the silica, one kind of silica may be used alone, or two or more kinds of silica may be used in combination.

The specific surface area for adsorption of cetyltrimethylammonium bromide (CTAB) of the silica is not particularly limited, but it is preferably 100 to 400 m ² / g, preferably 120 to 350 m ² / g, for the reason that the effect of the present invention is more excellent. Is more preferable, and 150 to 300 m ² / g is even more preferable.
In the present specification, the CTAB adsorption specific surface area is a value obtained by measuring the amount of CTAB adsorbed on the silica surface according to JIS K6217-3: 2001 "Part 3: How to obtain the specific surface area-CTAB adsorption method".

In the composition of the present invention, the content of silica is 30 parts by mass or more with respect to 100 parts by mass of the conjugated diene rubber. Among them, 40 parts by mass or more is preferable, and 50 parts by mass or more is more preferable, for the reason that the effect of the present invention is more excellent.
The upper limit of the silica content is not particularly limited, but for the reason that the effect of the present invention is more excellent, it is preferably 250 parts by mass or less, preferably 200 parts by mass or less, with respect to 100 parts by mass of the above-mentioned conjugated diene rubber. Is more preferable.

[3] Silane Coupling Agent The silane coupling agent contained in the composition of the present invention is not particularly limited as long as it is a silane compound having a hydrolyzable group and an organic functional group.
The hydrolyzable group is not particularly limited, and examples thereof include an alkoxy group, a phenoxy group, a carboxyl group, and an alkenyloxy group. Of these, an alkoxy group is preferable because the effect of the present invention is more excellent. When the hydrolyzable group is an alkoxy group, the number of carbon atoms of the alkoxy group is preferably 1 to 16 and more preferably 1 to 4 for the reason that the effect of the present invention is more excellent. Examples of the alkoxy group having 1 to 4 carbon atoms include a methoxy group, an ethoxy group, a propoxy group and the like.

The organic functional group is not particularly limited, but is preferably a group capable of forming a chemical bond with an organic compound, for example, an epoxy group, a vinyl group, an acryloyl group, a methacryloyl group, an amino group, a sulfide group, a mercapto group, or a block. Examples thereof include a mercapto group (protected mercapto group) (for example, an octanoylthio group), and among them, a sulfide group (particularly, a disulfide group and a tetrasulfide group), a mercapto group, and a blocked mercapto group for the reason that the effect of the present invention is more excellent. Is preferable.

Specific examples of the above silane coupling agent include bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (3-triethoxysilylpropyl) disulfide, and mercaptopropyltrimethoxy. Silane, mercaptopropyl triethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyl-tetrasulfide, trimethoxysilylpropyl-mercaptobenzothiazole tetrasulfide, triethoxysilylpropyl-methacrylate-monosulfide, dimethoxymethylsilyl Examples thereof include propyl-N, N-dimethylthiocarbamoyl-tetrasulfide, 3-octanoylthio-1-propyltriethoxysilane, etc., and one of them may be used alone or two or more thereof may be used in combination. ..

The silane coupling agent is preferably a compound represented by the following general formula (S) because the effect of the present invention is more excellent.
(C _n H _{2n + 1} O) ₃ -Si-C _m H _2m -S-CO-C _k H _{2k + 1} General formula (S)
In the general formula (S), n represents an integer of 1 to 3, m represents an integer of 1 to 5 (preferably an integer of 2 to 4), and k represents an integer of 1 to 15 (preferably 5 to 5 to 5). (An integer of 10).

In the composition of the present invention, the content of the silane coupling agent is 3 to 30% by mass with respect to the content of silica described above. Among them, 5 to 20% by mass is preferable because the effect of the present invention is more excellent.

Further, in the composition of the present invention, the content of the silane coupling agent is 1 to 50 parts by mass with respect to 100 parts by mass of the above-mentioned conjugated diene rubber because the effect of the present invention is more excellent. It is preferably 2 to 45 parts by mass, more preferably 4 to 40 parts by mass.

[4] Specific modified BR
The modified butadiene polymer contained in the composition of the present invention has a functional group containing a nitrogen atom and a silicon atom (hereinafter, also referred to as “specific functional group”) at the terminal, and has a weight average molecular weight of 1,000 or more and 100, It is a butadiene polymer (butadiene polymer) having a molecular weight distribution of 000 or less and a molecular weight distribution of 2.0 or less.
Hereinafter, the modified butadiene polymer is also referred to as "specifically modified BR".

In the present invention, it is considered that the dispersibility of silica becomes extremely excellent by using the specific modified BR, and as a result, excellent rolling performance, wear resistance performance and workability are achieved.
The reason is not clear in detail, but it is considered that the nitrogen atom and the silicon atom in the specific functional group of the specific modified BR interact with silica to prevent the aggregation of silica. Here, as a result of the studies by the present inventors, it is known that a criticality is observed between the size (weight average molecular weight, molecular weight distribution) of the modified butadiene polymer (modified BR) and the dispersibility of silica. This makes it extremely easy to intervene in the gaps between the aggregates of silica when the size of the modified BR (weight average molecular weight, molecular weight distribution) is within the above-mentioned specific range, and as a result, the dispersibility of silica is significantly increased. It is presumed to improve.

Hereinafter, the specific modified BR will be described in detail.
As described above, the specific modified BR has a functional group (specific functional group) containing a nitrogen atom and a silicon atom at the end, has a weight average molecular weight of 1,000 or more and 100,000 or less, and has a molecular weight distribution of 2.0. The following are butadiene polymers (modified butadiene polymers).

[Specific functional group]
As described above, the specific modified BR has a functional group (specific functional group) containing a nitrogen atom and a silicon atom at the end. The specific functional group may be present at at least one terminal.

[Preferable mode]
The specific functional group is not particularly limited as long as it is a functional group containing a nitrogen atom and a silicon atom, but for the reason that the effect of the present invention is more excellent, the nitrogen atom is an amino group (-NR ₂ : R is a hydrogen atom or a hydrocarbon group). It is preferable that the silicon atom is contained as a hydrocarbyloxysilyl group (≡SiOR: R is a hydrocarbon group).

The specific functional group is preferably a group represented by the following formula (M) for the reason that the effect of the present invention is more excellent.

In the above formula (M), R ₁ and R ₂ each independently represent a hydrogen atom or a substituent.
In the above formula (M), L represents a divalent organic group.

The above-mentioned substituent is not particularly limited as long as it is a monovalent substituent, and for example, a halogen atom, a hydroxy group, a nitro group, a carboxy group, an alkoxy group, an amino group, a mercapto group, an acyl group, an imide group, a phosphino group, and a phosphinyl. Examples thereof include a group, a silyl group, and a hydrocarbon group which may have a hetero atom.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
Examples of the heteroatom of the hydrocarbon group which may have the heteroatom include an oxygen atom, a nitrogen atom, a sulfur atom and a phosphorus atom.
Examples of the hydrocarbon group which may have the heteroatom include an aliphatic hydrocarbon group, an aromatic hydrocarbon group, and a group in which these are combined.
The aliphatic hydrocarbon group may be linear, branched or cyclic. Specific examples of the aliphatic hydrocarbon group include a linear or branched alkyl group (particularly 1 to 30 carbon atoms), a linear or branched alkenyl group (particularly 2 to 30 carbon atoms), and the like. Examples thereof include a linear or branched alkynyl group (particularly, having 2 to 30 carbon atoms).
Examples of the aromatic hydrocarbon group include an aromatic hydrocarbon group having 6 to 18 carbon atoms such as a phenyl group, a tolyl group, a xsilyl group and a naphthyl group.

In the above formula (M), R ₁ has a hydrogen atom, an alkyl group (preferably 1 to 10 carbon atoms), and an alkylsilyl group (preferably 1 to 10 carbon atoms) because the effect of the present invention is more excellent. , Aromatic hydrocarbon groups (preferably 6 to 18 carbon atoms), more preferably hydrogen atoms.
A plurality of R _1s may be the same or different.

R ₂ is preferably a hydrocarbyloxy group (-OR group: R is a hydrocarbon group) and preferably an alkoxy group (preferably 1 to 10 carbon atoms) because the effect of the present invention is more excellent. More preferred.

As described above, in the above formula (M), L represents a single bond or a divalent organic group.
Examples of the divalent organic group include an aliphatic hydrocarbon group (for example, an alkylene group, preferably 1 to 10 carbon atoms), an aromatic hydrocarbon group (for example, an arylene group, preferably 6 to 18 carbon atoms). -O-, -S-, -SO _2- , -N (R)-(R: alkyl group), -CO-, -NH-, -COO-, -CONH-, or a group combining these (for example, , Alkyleneoxy group (-Cm H _2m O-: _m is a positive integer), alkyleneoxycarbonyl group, alkylenecarbonyloxy group, etc.) and the like.
L is preferably an alkylene group (preferably having 1 to 10 carbon atoms) for the reason that the effect of the present invention is more excellent.

In the above equation (M), n represents an integer of 0 to 2.
n is preferably 2 for the reason that the effect of the present invention is more excellent.

In the above equation (M), m represents an integer of 1 to 3.
m is preferably 1 for the reason that the effect of the present invention is more excellent.

In the above equation (M), n and m satisfy the relational expression of n + m = 3.

In the above formula (M), * represents a bonding position.

[Weight average molecular weight]
As described above, the weight average molecular weight (Mw) of the specific modified BR is 1,000 or more and 100,000 or less. Among them, for the reason that the effect of the present invention is more excellent, it is preferably 1,000 or more and 50,000 or less, and more preferably 5,000 or more and 15,000 or less.

[Number average molecular weight]
The number average molecular weight of the specific modified BR is not particularly limited as long as the weight average molecular weight and the molecular weight distribution of the specific modified BR are within a specific range, but it is 1,000 or more and 100,000 or less for the reason that the effect of the present invention is more excellent. It is preferable, it is more preferably 1,000 or more and 50,000 or less, and further preferably 5,000 or more and 15,000 or less.

[Molecular weight distribution]
As described above, the molecular weight distribution (Mw / Mn) of the specific modified BR is 2.0 or less. Among them, for the reason that the effect of the present invention is more excellent, it is preferably 1.7 or less, more preferably 1.5 or less, and further preferably 1.3 or less.
The lower limit is not particularly limited, but is usually 1.0 or more.

In the present specification, the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the specific modified BR are standard polystyrene-equivalent values obtained by gel permeation chromatography (GPC) measurement under the following conditions.
・ Solvent: Tetrahydrofuran ・ Detector: RI detector

[Micro structure]
[Vinyl structure]
In the specific modified BR, the proportion of the vinyl structure (vinyl bond content) is not particularly limited, but is preferably 10 to 50% by mass, preferably 20 to 40% by mass, for the reason that the effect of the present invention is more excellent. Is more preferable.
Here, the ratio of the vinyl structure means the ratio (mass%) of the repeating units having a vinyl structure to the repeating units derived from butadiene.

[1,4-Transformer structure]
In the specific modified BR, the ratio of the 1,4-trans structure is not particularly limited, but is preferably 10 to 70% by mass, more preferably 30 to 50% by mass, for the reason that the effect of the present invention is more excellent. preferable.
Here, the ratio of the 1,4-trans structure means the ratio (mass%) of the repeating units having the 1,4-trans structure among all the repeating units derived from butadiene.

[1,4-cis structure]
In the specific modified BR, the ratio of the 1,4-cis structure is not particularly limited, but is preferably 10 to 50% by mass, more preferably 20 to 40% by mass, for the reason that the effect of the present invention is more excellent. preferable.
Here, the ratio of the 1,4-cis structure means the ratio (mass%) of the repeating units having the 1,4-cis structure to all the repeating units derived from butadiene.

Hereinafter, "ratio of vinyl structure (mass%), ratio of 1,4-trans structure (mass%), ratio of 1,4-cis structure (mass%)" is also referred to as "vinyl / trans / cis". ..

[Glass-transition temperature]
The glass transition temperature (Tg) of the specific modified BR is not particularly limited, but is preferably −100 to −60 ° C., more preferably −90 to −70 ° C. for the reason that the effect of the present invention is more excellent. , -85 to -75 ° C., more preferably.
In the present specification, the glass transition temperature (Tg) is measured at a heating rate of 10 ° C./min using a differential scanning calorimeter (DSC) and calculated by the midpoint method.

[viscosity]
The viscosity of the specific modified BR is not particularly limited, but is preferably 1,000 to 10,000 mPa · s, more preferably 3,000 to 6,000 mPa · s, for the reason that the effect of the present invention is more excellent. preferable.
The viscosity of the butadiene polymer before modification of the specific modified BR is not particularly limited, but is preferably 500 to 5,000 mPa · s, preferably 1,500 to 3,000 mPa, for the reason that the effect of the present invention is more excellent. -S is more preferable.
Further, the viscosity of the specific modified BR is preferably 150 to 240% with respect to the viscosity of the butadiene polymer before modification because the effect of the present invention is more excellent. Hereinafter, the viscosity of the characteristic modified BR after modification with respect to the specific modified BR before modification is also referred to as "viscosity (after modification / before modification)".
In this specification, the viscosity is measured using a cone plate type viscometer according to JIS K5600-2-3.

[Manufacturing method of specific modified BR]
The method for producing the specific modified BR is not particularly limited, and a conventionally known method can be used. The method for limiting the molecular weight and the molecular weight distribution in a specific range is not particularly limited, and examples thereof include a method for adjusting the amount ratio of the initiator, the monomer, and the terminator, the reaction temperature, the rate at which the initiator is added, and the like.

[Preferable mode]
A preferred embodiment of the method for producing the specific modified BR is, for example, a method of polymerizing butadiene using an organic lithium compound and then terminating the polymerization using an electrophile containing a nitrogen atom and a silicon atom (hereinafter, hereafter. Also referred to as "the method of the present invention"). When the specific modified BR obtained by the method of the present invention is used, the composition of the present invention exhibits better rolling performance, wear resistance and workability.

<Organolithium compound>
The above-mentioned organolithium compound is not particularly limited, and specific examples thereof include monoorganolithium compounds such as n-butyllithium, sec-butyllithium, tert-butyllithium, n-propyllithium, iso-propyllithium, and benzyllithium; 1,4-dilithiobutane, 1,5-dilithiopentane, 1,6-dilithiohexane, 1,10-dilithiodecane, 1,1-dilithiodiphenylene, dilithiopolybutadiene, dilithiopolyisoprene, 1,4-dilithio Benzene, 1,2-dilithio-1,2-diphenylethane, 1,4-dilithio-2-ethylcyclohexane, 1,3,5-trilithiobenzene, 1,3,5-trilithio-2,4,6- Examples thereof include polyfunctional organolithium compounds such as triethylbenzene. Of these, monoorganolithium compounds such as n-butyllithium, sec-butyllithium, and tert-butyllithium are preferable because the effects of the present invention are more excellent.

The amount of the organic lithium compound used is not particularly limited, but is preferably 0.001 to 10 mol% with respect to butadiene for the reason that the effect of the present invention is more excellent.

<Copolymerization of butadiene>
The method for polymerizing butadiene using an organic lithium compound is not particularly limited, but the above-mentioned organic lithium compound is added to an organic solvent solution containing butadiene, and the temperature range is 0 to 120 ° C (preferably 30 to 100 ° C). Examples include a method of stirring.

<Specific electrophile>
In the method of the present invention, the polymerization of butadiene is stopped by using an electrophile containing a nitrogen atom and a silicon atom (hereinafter, also referred to as “specific electrophile”). By terminating the polymerization with a specific electrophile, a modified butadiene polymer having the above-mentioned specific functional group at the end can be obtained.
The specific electrophilic agent is not particularly limited as long as it is a compound containing a nitrogen atom and a silicon atom, but for the reason that the effect of the present invention is more excellent, the nitrogen atom is an amino group (-NR ₂ : R is a hydrogen atom or a hydrocarbon group). It is preferable to include a silicon atom as a hydrocarbyloxysilyl group (≡SiOR: R is a hydrocarbon group).

The specific electrophile is preferably silazane, more preferably cyclic silazane, for the reason that the effect of the present invention is more excellent. Here, silazane is intended to be a compound having a structure in which a silicon atom and a nitrogen atom are directly bonded (a compound having a Si—N bond).

The cyclic silazane is preferably a compound represented by the following formula (S) for the reason that the effect of the present invention is more excellent.

In the above formula (S), R ₁ to R ₃ independently represent a hydrogen atom or a substituent. Specific examples and preferred embodiments of the substituent are the same as those of R ₁ and R ₂ in the above formula (M).
In the above formula (S), L represents a divalent organic group. Specific examples and preferred embodiments of the divalent organic group are the same as L in the above-mentioned formula (M).

In the above formula (S), R ₁ has an alkyl group (preferably 1 to 10 carbon atoms), an alkylsilyl group (preferably 1 to 10 carbon atoms), and an aromatic group because the effect of the present invention is more excellent. It is preferably a hydrocarbon group (preferably 6 to 18 carbon atoms), and more preferably an alkylsilyl group.

In the above formula (S), R ₂ and R ₃ are preferably hydrocarbyloxy groups (-OR group: R is a hydrocarbon group) independently of each other, and are alkoxy groups, for the reason that the effect of the present invention is more excellent. (Preferably, the number of carbon atoms is 1 to 10).

In the above formula (S), L is preferably an alkylene group (preferably 1 to 10 carbon atoms, more preferably 2 to 8 carbon atoms, still more preferably 3 to 5 carbon atoms) for the reason that the effect of the present invention is more excellent. ..

Examples of the compound represented by the above formula (S) include Nn-butyl-1,1-dimethoxy-2-azasilacyclopentane and N-phenyl-1,1-dimethoxy-2-azasilacyclopentane. , N-Trimethylsilyl-1,1-dimethoxy-2-azasilacyclopentane, N-trimethylsilyl-1,1-diethoxy-2-azasilacyclopentane and the like.
The silicon atom of cyclic silazane is considered to exhibit electrophilicity.

The amount of the specific electrophile with respect to the organolithium compound is not particularly limited, but for the reason that the effect of the present invention is more excellent, the molar ratio is preferably 0.1 to 10 and more preferably 1 to 5. ..

[Content]
In the composition of the present invention, the content of the specific modified BR is not particularly limited, but for the reason that the effect of the present invention is more excellent, it is preferably 1 to 25% by mass with respect to the above-mentioned silica content. More preferably, it is 2.0 to 10.0% by mass.
Further, the content of the specific modified BR is preferably 1 part by mass or more and less than 10 parts by mass with respect to 100 parts by mass of the above-mentioned conjugated diene rubber because the effect of the present invention is more excellent.

[4] Optional components The composition of the present invention may contain components (arbitrary components) other than the above-mentioned components, if necessary.
Such components include, for example, fillers other than silica (eg, carbon black), terpene resins (preferably aromatic-modified terpene resins), thermoexpandable microcapsules, zinc oxide (zinc oxide), stearic acid, and the like. Various additives commonly used in rubber compositions such as anti-aging agents, waxes, processing aids, process oils, liquid polymers, thermosetting resins, vulcanizing agents (eg sulfur), vulcanization accelerators, etc. Can be mentioned.

[Carbon black]
The composition of the present invention preferably contains carbon black for the reason that the effect of the present invention is more excellent.
The carbon black is not particularly limited, and for example, various grades such as SAF-HS, SAF, ISAF-HS, ISAF, ISAF-LS, IISAF-HS, HAF-HS, HAF, HAF-LS, FEF, GPF, SRF and the like. Can be used.
The nitrogen adsorption specific surface area (N ₂ SA) of the carbon black is not particularly limited, but is preferably 50 to 200 m ² / g, preferably 70 to 150 m ² / g, for the reason that the effect of the present invention is more excellent. Is more preferable.
Here, the nitrogen adsorption specific surface area (N ₂ SA) is the amount of nitrogen adsorbed on the carbon black surface according to JIS K6217-2: 2001 "Part 2: How to obtain the specific surface area-Nitrogen adsorption method-Single point method". It is a measured value.

In the composition of the present invention, the content of carbon black is not particularly limited, but for the reason that the effect of the present invention is more excellent, it may be 1 to 100 parts by mass with respect to 100 parts by mass of the above-mentioned conjugated diene rubber. It is preferably 2 to 10 parts by mass, and more preferably 2 to 10 parts by mass.

[Preparation method of rubber composition for tire tread]
The method for producing the composition of the present invention is not particularly limited, and as a specific example thereof, each of the above-mentioned components is kneaded using a known method or apparatus (for example, Banbury mixer, kneader, roll, etc.). The method etc. can be mentioned. When the composition of the present invention contains sulfur or a vulcanization accelerator, components other than sulfur and the vulcanization accelerator are first mixed at a high temperature (preferably 100 to 160 ° C.), cooled, and then sulfur or It is preferable to mix the vulcanization accelerator.
In addition, the composition of the present invention can be vulcanized or crosslinked under conventionally known vulcanization or crosslinking conditions.

[II] Pneumatic Tire The pneumatic tire of the present invention is a pneumatic tire manufactured by using the composition of the present invention described above. Among them, it is preferable that the tire is a pneumatic tire in which the composition of the present invention is used (arranged) for the tire tread (cap tread).
FIG. 1 shows a schematic partial cross-sectional view of a pneumatic tire showing an example of an embodiment of the pneumatic tire of the present invention, but the pneumatic tire of the present invention is not limited to the embodiment shown in FIG.

In FIG. 1, reference numeral 1 represents a bead portion, reference numeral 2 represents a sidewall portion, and reference numeral 3 represents a tire tread portion.
Further, a carcass layer 4 in which a fiber cord is embedded is mounted between the pair of left and right bead portions 1, and the end portion of the carcass layer 4 is placed around the bead core 5 and the bead filler 6 from the inside to the outside of the tire. It is folded back and rolled up.
Further, in the tire tread portion 3, a belt layer 7 is arranged on the outside of the carcass layer 4 over one circumference of the tire.
Further, in the bead portion 1, the rim cushion 8 is arranged at a portion in contact with the rim.
The tire tread portion 3 is formed by the composition of the present invention described above.

The pneumatic tire of the present invention can be manufactured, for example, according to a conventionally known method. Further, as the gas to be filled in the pneumatic tire, an inert gas such as nitrogen, argon or helium can be used in addition to normal or adjusted oxygen partial pressure.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[Manufacturing of specific conjugated diene rubber and comparative conjugated diene rubber]
Specific conjugated diene rubbers 1 to 5 and comparative conjugated diene rubbers 1 to 3 were produced as follows.
Here, the specific conjugated diene rubbers 1 to 5 are conjugated diene rubbers produced by the method for producing a conjugated diene rubber including the first to third steps described above, and correspond to the specific conjugated diene rubbers described above. Further, the specific conjugated diene rubbers 1 to 3 include the above-mentioned steps A and B in the first step, and the specific conjugated diene rubber has a PI block.
On the other hand, the comparative conjugated diene rubbers 1 and 3 are conjugated diene rubbers produced by the method for producing a conjugated diene rubber having the above-mentioned first and second steps (not including the above-mentioned third step), and are described above. Not applicable to specific conjugated diene rubber. Further, the comparative conjugated diene rubber 2 does not correspond to the specific conjugated diene rubber described above because the amount of the polyorganosiloxane added does not satisfy the second step described above.

<Specific conjugated diene rubber 1>
To a nitrogen-substituted 800 ml ampol bottle, 74.3 g of cyclohexane and 0.48 mmol of tetramethylethylenediamine were added, and 4.76 mmol of n-butyllithium (tetramethylethylenediamine as a polar compound with respect to 1 mol of n-butyllithium) was added. The amount of the above is 0.10 mol) was added. Then, 17.3 g of isoprene and 1.3 g of styrene were slowly added and reacted in an ampoule bottle at 50 ° C. for 120 minutes to obtain a polymer block (A) having an active terminal. The weight average molecular weight (Mw) of this polymer block (A) is 6,500, the molecular weight distribution (Mw / Mn) is 1.12, the styrene monomer unit content is 7.0% by mass, and the isoprene monomer unit. The content was 93.0% by mass, and the vinyl bond content was 7.5% by mass.

After charging 4000 g of cyclohexane, 3.57 mmol of tetramethylethylenediamine, 252 g of 1,3-butadiene, and 348 g of styrene in an autoclave with a stirrer under a nitrogen atmosphere, the polymer block (A) having the active terminal obtained above was charged. Was added and polymerization was started at 50 ° C. (the amount of tetramethylethylenediamine as a polar compound present in the reaction system was 0.85 mol with respect to 1 mol of n-butyllithium used). After 15 minutes from the start of the polymerization, 338 g of 1,3-butadiene and 62 g of styrene were continuously added over 60 minutes. The maximum temperature during the polymerization reaction was 70 ° C. After the completion of continuous addition, the polymerization reaction was continued for another 15 minutes, and after confirming that the polymerization conversion rate was in the range of 95% to 100%, 40 polyorganosiloxane represented by the following formula (11) was added. In the state of a xylene solution having a mass% concentration, 1.51 g (1.1 times the molar amount of n-butyllithium used in terms of the number of repeating units of the siloxane structure (-Si-O-) in the polyorganosiloxane) (Amount corresponding to) was added and reacted for 30 minutes. Then, 4.76 mmol of 3- (2-aminoethylamino) propyltrimethoxysilane (amount corresponding to 1.0 times the molar amount of n-butyllithium used) was added, and the mixture was reacted for 10 minutes. Then, as a polymerization inhibitor, methanol corresponding to twice the molar amount of n-butyllithium used was added to obtain a solution containing a conjugated diene rubber. To this solution, 0.15 part of Irganox 1520L (manufactured by BASF) as an anti-aging agent was added to 100 parts of conjugated diene rubber, the solvent was removed by steam stripping, and the temperature was 60 ° C. for 24 hours. Vacuum drying was performed to obtain a solid conjugated diene rubber. The obtained conjugated diene-based rubber is designated as the specific conjugated diene-based rubber 1. The weight average molecular weight (Mw) of the specific conjugated diene rubber 1 was 530,000, the coupling rate was 45.0%, the styrene monomer unit content was 41% by mass, and the vinyl bond content was 34% by mass. ..

In the above formula (11), X ¹ , X ⁴ , R ¹ to R ³ and R ⁵ to R ⁸ are methyl groups. In the above formula (11), m is 80 and k is 120. In the above formula (11), X ² is a group represented by the following formula (12) (where * represents a bonding position).

<Comparative conjugated diene rubber 1>
Cyclohexane (35 g) and tetramethylethylenediamine (1.4 mmol) were added to a nitrogen-substituted 100 mL ampoule bottle, and n-butyllithium (4.3 mmol) was further added. Then, isoprene (21.6 g) and styrene (3.1 g) were slowly added and reacted in an ampoule bottle at 50 ° C. for 120 minutes to obtain a polymer block (A) having an active terminal. The weight average molecular weight, molecular weight distribution, aromatic vinyl monomer unit content, isoprene monomer unit content, and 1,4-bond content of this polymer block (A) were measured. As a result, the weight average molecular weight was measured. 8,700, molecular weight distribution 1.10, aromatic vinyl monomer unit content 12.6% by mass, isoprene monomer unit content 87.4% by mass, 1,4-bond content It was 58.0% by mass.
Next, cyclohexane (4000 g), 1,3-butadiene (474.0 g), and styrene (126.0 g) are charged into an autoclave with a stirrer under a nitrogen atmosphere, and then the autoclave has the active terminal obtained above. The entire amount of the polymer block (A) was added, and polymerization was started at 50 ° C. After confirming that the polymerization conversion rate was in the range of 95% to 100%, the polyorganosiloxane represented by the above formula (11) was then subjected to an epoxy group content of 1.42 mmol (n used). -It was added in the state of a xylene solution having a concentration of 20% by mass so as to be (corresponding to 0.33 times the molar amount of butyllithium), and reacted for 30 minutes. Then, as a polymerization inhibitor, methanol corresponding to twice the molar amount of n-butyllithium used was added to obtain a solution containing a conjugated diene rubber. A small amount of anti-aging agent (Irganox 1520, manufactured by BASF) was added to this solution, and Fuccole Eramic 30 (manufactured by Nippon Oil Co., Ltd.) was added as a spreading oil to 25 parts by mass of 100 parts by mass of the specified conjugated diene rubber. After adding by mass, the solid rubber was recovered by the steam stripping method. The obtained solid rubber was dehydrated with a roll and dried in a dryer to obtain a solid conjugated diene rubber. The obtained conjugated diene rubber is designated as the comparative conjugated diene rubber 1.
When the weight average molecular weight, molecular weight distribution, coupling rate, styrene monomer unit content, vinyl bond content, and Mooney viscosity of the comparative conjugated diene rubber 1 were measured, the weight average molecular weight was 660,000, and the molecular weight distribution. The coupling rate was 1.7, the coupling rate was 12.5% by mass, the styrene monomer unit content was 43% by mass, the vinyl bond content was 31% by mass, and the Mooney viscosity (ML _{1 + 4} , 100 ° C.) was 58. ..

<Specific conjugated diene rubber 2>
To a nitrogen-substituted 100 ml ampoule bottle, 50.0 g of cyclohexane and 0.66 mmol of tetramethylethylenediamine were added, and 6.6 mmol of n-butyllithium was further added. Then, 11.61 g of isoprene and 0.87 g of styrene were slowly added and reacted in an ampoule bottle at 50 ° C. for 120 minutes to obtain a polymer block (A) having an active terminal. The weight average molecular weight (Mw) of this polymer block (A) is 3,500, the molecular weight distribution (Mw / Mn) is 1.10, the styrene monomer unit content is 7.0% by mass, and the isoprene monomer unit. The content was 93.0% by mass, and the vinyl bond content was 7.7% by mass.

Next, in an autoclave with a stirrer, in a nitrogen atmosphere, 4000 g of cyclohexane and tetramethylethylenediamine 11. After charging 393.0 g of l mmol, 1,3-butadiene, and 207.0 g of styrene, all of the polymer block (A) having the active terminal obtained above was added, and polymerization was started at 40 ° C. After 10 minutes from the start of the polymerization, 337.0 g of 1,3-butadiene and 63.0 g of styrene were continuously added over 40 minutes. The maximum temperature during the polymerization reaction was 60 ° C. After the completion of continuous addition, the polymerization reaction was continued for another 20 minutes, and after confirming that the polymerization conversion rate was in the range of 95% to 100%, the polyorganosiloxane represented by the above formula (11) was added to 40. In the state of a xylene solution having a mass% concentration, 2.13 g (1.1 times the molar amount of n-butyllithium used in terms of the number of repeating units of the siloxane structure (-Si-O-) in the polyorganosiloxane) (Amount corresponding to) was added and reacted for 30 minutes. Then, 6.6 mmol of 3- (2-aminoethylamino) propyltrimethoxysilane (amount corresponding to 1.0 times the molar amount of n-butyllithium used) was added, and the mixture was stirred for 10 minutes. Then, as a polymerization inhibitor, methanol corresponding to twice the molar amount of n-butyllithium used was added to obtain a solution containing a conjugated diene rubber. To this solution, 0.15 part of Irganox 1520L (manufactured by Ciba Speciality Chemicals) as an anti-aging agent was added to 100 parts of conjugated diene rubber, and then the solvent was removed by steam stripping at 60 ° C. Vacuum drying was performed for 24 hours to obtain a solid conjugated diene-based rubber. The obtained conjugated diene-based rubber is designated as a specific conjugated diene-based rubber 2. The weight average molecular weight (Mw) of the specific conjugated diene rubber 2 was 430,000, the coupling rate was 60.2%, the styrene monomer unit content was 27% by mass, and the vinyl bond content was 60% by mass. ..

<Comparative conjugated diene rubber 2>
In an autoclave with a stirrer, 800 g of cyclohexane, 1.42 mmol of tetramethylethylenediamine, 87.6 g of 1,3-butadiene, and 32.4 g of styrene were charged under a nitrogen atmosphere, 0.79 mmol of n-butyllithium was added, and the temperature was 60 ° C. Polymerization was started at. After continuing the polymerization reaction for 60 minutes and confirming that the polymerization conversion rate was in the range of 95% to 100%, the polyorganosiloxane represented by the above formula (11) was added to a xylene solution having a concentration of 40% by mass. In the state of, 0.16 g (amount corresponding to 0.7 times the molar amount of n-butyllithium used in terms of the number of repeating units of the siloxane structure (-Si-O-) in the polyorganosiloxane) was added. And reacted for 30 minutes. Then, 0.79 mmol of 3-aminopropyltrimethoxysilane (amount corresponding to 1.0 times the molar amount of n-butyllithium used) was added, and the mixture was stirred for 10 minutes. Then, as a polymerization inhibitor, methanol corresponding to twice the molar amount of n-butyllithium used was added to obtain a solution containing a conjugated diene rubber. To this solution, 0.15 part of Irganox 1520L (manufactured by Ciba Speciality Chemicals) as an anti-aging agent was added to 100 parts of conjugated diene rubber, and then the solvent was removed by steam stripping to remove the solvent at 60 ° C. The mixture was vacuum-dried for 24 hours to obtain a solid conjugated diene-based rubber. The obtained conjugated diene rubber is designated as the comparative conjugated diene rubber 2. The weight average molecular weight (Mw) of the comparative conjugated diene rubber 2 is 430,000, the coupling rate is 34.4%, the styrene monomer unit content is 27% by mass, the vinyl bond content is 60% by mass, and the glass transition. The temperature (Tg) was −22 ° C., and the molecular weight distribution (Mw / Mn) was 1.4.

<Specific conjugated diene rubber 3>
To a nitrogen-substituted 800 ml ampol bottle, 70.0 g of cyclohexane and 0.77 mmol of tetramethylethylenediamine were added, and 7.69 mmol of n-butyllithium (amount of tetramethylethylenediamine as a polar compound with respect to 1 mol of n-butyllithium) was added. (Amount of which is 0.10 mol) was added. Then, 27.9 g of isoprene and 2.1 g of styrene were slowly added and reacted in an ampoule bottle at a temperature of 50 ° C. for 120 minutes to obtain a polymer block (A) having an active terminal. The weight average molecular weight (Mw) of this polymer block (A) is 6,500, the molecular weight distribution (Mw / Mn) is 1.10, the styrene monomer unit content is 7.0% by mass, and the isoprene monomer unit. The content was 93.0% by mass, and the vinyl bond content was 7.7% by mass.

After charging 4000 g of cyclohexane, 2.69 mmol of tetramethylethylenediamine, 474 g of 1,3-butadiene, and 126 g of styrene in an autoclave with a stirrer under a nitrogen atmosphere, the polymer block (A) having the active terminal obtained above was charged. Was added and polymerization was started at 50 ° C. (the amount of tetramethylethylenediamine as a polar compound present in the reaction system was 0.45 mol with respect to 1 mol of n-butyllithium used). After 10 minutes from the start of the polymerization, 376 g of 1,3-butadiene and 24 g of styrene were continuously added over 60 minutes. The maximum temperature during the polymerization reaction was 75 ° C. After the completion of continuous addition, the polymerization reaction was continued for another 10 minutes, and after confirming that the polymerization conversion rate was in the range of 95% to 100%, the polyorganosiloxane represented by the above formula (11) was added to 40. In the state of a xylene solution having a mass% concentration, 2.44 g (equivalent to 1.1 times the molar amount of n-butyllithium used in terms of the number of repeating units of the siloxane structure (-Si-O-) in the polyorganosiloxane). The amount to be added) was added, and the mixture was reacted for 30 minutes. Then, 7.69 mmol of 3- (2-aminoethylamino) propyltrimethoxysilane (amount corresponding to 1.0 times the molar amount of n-butyllithium used) was added, and the mixture was reacted for 10 minutes. Then, as a polymerization inhibitor, methanol corresponding to twice the molar amount of n-butyllithium used was added to obtain a solution containing a conjugated diene rubber. To this solution, 0.15 part of Irganox 1520L (manufactured by BASF) as an anti-aging agent was added to 100 parts of conjugated diene rubber, the solvent was removed by steam stripping, and the temperature was 60 ° C. for 24 hours. Vacuum drying was performed to obtain a solid conjugated diene rubber. The obtained conjugated diene-based rubber is designated as the specific conjugated diene-based rubber 3. The weight average molecular weight (Mw) of the specific conjugated diene rubber 3 is 420,000, the coupling rate is 58.0%, the styrene monomer unit content is 15% by mass, the vinyl bond content is 31% by mass, and the glass transition. The temperature (Tg) was −63 ° C., and the molecular weight distribution (Mw / Mn) was 1.6.

<Comparative conjugated diene rubber 3>
A solid conjugated diene rubber was obtained by the same procedure as in the specific conjugated diene rubber 3 except that 7.69 mmol of 3- (2-aminoethylamino) propyltrimethoxysilane was not added. The obtained conjugated diene rubber is designated as the comparative conjugated diene rubber 3. The weight average molecular weight (Mw) of the comparative conjugated diene rubber 3 is 420,000, the coupling rate is 56.8%, the styrene monomer unit content is 15% by mass, the vinyl bond content is 31% by mass, and the glass transition. The temperature (Tg) was −63 ° C., and the molecular weight distribution (Mw / Mn) was 1.6.

<Specific conjugated diene rubber 4>
After charging 800 g of cyclohexane and 120 g of 1,3-butadiene in an autoclave equipped with a stirrer under a nitrogen atmosphere, 1.00 mmol of n-butyllithium was added, and polymerization was started at 80 ° C. After continuing the polymerization reaction for 90 minutes and confirming that the polymerization conversion rate was in the range of 95% to 100%, 0.32 g of the polyorganosiloxane represented by the above formula (11) (in the polyorganosiloxane) In terms of the number of repeating units of the siloxane structure (—SO—), an amount corresponding to 1.1 times the molar amount of n-butyllithium used) was added and reacted for 30 minutes. Then, 1.00 mmol of 3- (2-aminoethylamino) propyltrimethoxysilane (amount corresponding to 1.0 times the molar amount of n-butyllithium used) was added, and the mixture was reacted for 10 minutes. Then, as a polymerization inhibitor, methanol corresponding to twice the molar amount of n-butyllithium used was added to obtain a solution containing a conjugated diene rubber. To this solution, 0.15 part of Irganox 1520L (manufactured by BASF) as an anti-aging agent was added to 100 parts of conjugated diene rubber, the solvent was removed by steam stripping, and the temperature was 60 ° C. for 24 hours. Vacuum drying was performed to obtain a solid conjugated diene rubber. The obtained conjugated diene-based rubber is designated as a specific conjugated diene-based rubber 4. The weight average molecular weight (Mw) of the specific conjugated diene rubber 4 was 490,000, the coupling rate was 55.5%, and the vinyl bond content was 10% by mass.

<Specific conjugated diene rubber 5>
In an autoclave with a stirrer, 800 g of cyclohexane, 1.42 mmol of tetramethylethylenediamine, 87.6 g of 1,3-butadiene, and 32.4 g of styrene were charged under a nitrogen atmosphere, 0.79 mmol of n-butyllithium was added, and the temperature was 60 ° C. Polymerization was started at. After continuing the polymerization reaction for 60 minutes and confirming that the polymerization conversion rate was in the range of 95% to 100%, the polyorganosiloxane represented by the above formula (11) was added to a xylene solution having a concentration of 40% by mass. 0.26 g (amount corresponding to 1.1 times the molar amount of n-butyllithium used in terms of the number of repeating units of the siloxane structure (-Si-O-) in the polyorganosiloxane) was added. And reacted for 30 minutes. Then, 0.79 mmol of 3- (2-aminoethylamino) propyltrimethoxysilane (amount corresponding to 1.0 times the molar amount of n-butyllithium used) was added, and the mixture was stirred for 10 minutes. Then, as a polymerization inhibitor, methanol corresponding to twice the molar amount of n-butyllithium used was added to obtain a solution containing a conjugated diene rubber. To this solution, 0.15 part of Irganox 1520L (manufactured by Ciba Speciality Chemicals) as an anti-aging agent was added to 100 parts of conjugated diene rubber, and then the solvent was removed by steam stripping to remove the solvent at 60 ° C. The mixture was vacuum-dried for 24 hours to obtain a solid conjugated diene-based rubber. The obtained conjugated diene-based rubber is designated as the specific conjugated diene-based rubber 5. The weight average molecular weight (Mw) of the specific conjugated diene rubber 5 was 470,000, the coupling rate was 54.4%, the styrene monomer unit content was 27% by mass, and the vinyl bond content was 59% by mass. ..

[Manufacturing of specific modified BR]
Specific modified BR1 and 2 and comparative modified BR1 were produced as follows.
Here, each of the specific modified BRs 1 and 2 has a functional group represented by the formula (m1) described later corresponding to the specific functional group at the terminal, and has an Mw of 1000 or more and 100,000 or less, and Mw /. Since it is a modified BR having Mn of 2.0 or less, it corresponds to the above-mentioned "specific modified BR". On the other hand, the comparatively modified BR1 is a modified BR having a functional group represented by the formula (m1) described later at the end and having an Mw of 1000 or more and 100,000 or less, but a Mw / Mn of more than 2.0. Therefore, it does not correspond to the above-mentioned "specific modified BR".

<Specific denatured BR1>
n-BuLi (manufactured by Kanto Chemical Co., Inc .: 1.60 mol / L (hexane solution), 27 mL, 43.2 mmol), 1,3-butadiene (205 g, 3786 mmol) and 2,2-di (2-tetrahydrofuryl) propane ( It was added to a mixed solution of cyclohexane (2.96 kg) of Tokyo Kasei Co., Ltd. (0.1 mL, 0.55 mmol), and the mixture was stirred at room temperature for 6 hours. After the reaction, N-trimethylsilyl-1,1-dimethoxy-2-azasilacyclopentane (hereinafter referred to as the structure) (15 g, 137 mmol) was added to terminate the polymerization.

The resulting solution was removed and concentrated under reduced pressure. The concentrated solution was poured into methanol (10 L) to separate methanol-insoluble components. As a result, a modified BR (specific modified BR1) (199 g, Mn = 7,600, Mw = 8,100) having a functional group represented by the following formula (m1) (where * represents a binding position) at the end. , Mw / Mn = 1.1) was obtained in a yield of 97%. It was estimated by IR analysis that cis / trans / vinyl = 24/40/36. The Tg was −80 ° C. The viscosity (after modification / before modification) was 204%.

<Specific denatured BR2>
n-BuLi (manufactured by Kanto Chemical Co., Inc .: 1.60 mol / L (hexane solution), 17 mL, 27.2 mmol), 1,3-butadiene (256 g, 4732 mmol) and 2,2-di (2-tetrahydrofuryl) propane ( It was added to a mixed solution of cyclohexane (3.5 kg) of Tokyo Kasei Co., Ltd. (0.1 mL, 0.55 mmol), and the mixture was stirred at room temperature for 3 hours. Then, 17 mL of n-BuLi was added and the mixture was stirred for 3 hours. After the reaction, N-trimethylsilyl-1,1-dimethoxy-2-azasilacyclopentane (25 g, 114 mmol) was added to terminate the polymerization. The resulting solution was removed and concentrated under reduced pressure. The concentrated solution was poured into methanol (5.0 L) to separate methanol-insoluble components. As a result, 95 modified BR (specific modified BR2) (740 g, Mn = 6,300, Mw = 9,400, Mw / Mn = 1.5) having a functional group represented by the above formula (m1) at the end. Obtained in% yield. It was estimated by IR analysis that cis / trans / vinyl = 24/38/38. The Tg was −76 ° C. The viscosity (after modification / before modification) was 181%.

<Comparative denatured BR1>
n-BuLi (manufactured by Kanto Chemical Co., Inc .: 1.60 mol / L (hexane solution), 23.2 mL, 37.2 mmol), 1,3-butadiene (461 g, 8518 mmol) and 2,2-di (2-tetrahydrofuryl) Propane (manufactured by Tokyo Kasei Co., Ltd., 0.2 mL, 1.09 mmol) was added to a mixed solution of cyclohexane (4.20 kg), and the mixture was stirred at room temperature. Every 1 hour and 30 minutes, 23.2 mL of n-BuLi was added, for a total of 92.8 mL. Six hours after the reaction was started, N-trimethylsilyl-1,1-dimethoxy-2-azasilacyclopentane was added. (60 g, 274 mmol) was added to terminate the polymerization. The resulting solution was removed and concentrated under reduced pressure. The concentrated solution was poured into methanol (10 L) to separate methanol-insoluble components. As a result, 97 modified BR (comparative modified BR1) (740 g, Mn = 4,000, Mw = 8,800, Mw / Mn = 2.2) having a functional group represented by the above formula (m1) at the end. It was obtained in a yield of%. It was estimated by IR analysis that cis / trans / vinyl = 23/38/39. The Tg was −77 ° C.

[Preparation of rubber composition for tire tread]
The components shown in Table 1 below were blended in the proportions (parts by mass) shown in the same table.
Specifically, first, among the components shown in Table 1 below, the components excluding sulfur and the vulcanization accelerator are raised to around 140 ° C. using a 1.7 liter sealed Banbury mixer, and then for 5 minutes. After mixing, it was released and cooled to room temperature to obtain a masterbatch. Further, using the above-mentioned Banbury mixer, sulfur and a vulcanization accelerator were mixed with the obtained masterbatch to obtain a rubber composition for tire tread.
When the rubber component is an oil-extended product, the mass portion represents the net amount of rubber (the amount excluding oil).

〔evaluation〕
The obtained rubber composition for tire tread was evaluated as follows.

<Making a vulcanized rubber sheet>
The obtained rubber composition for tire tread (unvulcanized) was press-vulcanized in a mold (15 cm × 15 cm × 0.2 cm) at 160 ° C. for 40 minutes to prepare a vulcanized rubber sheet.

<Rolling performance>
The obtained vulcanized rubber sheet was subjected to a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho Co., Ltd.) in accordance with JIS K6394: 2007 under the conditions of a stretch deformation strain rate of 10% ± 2%, a frequency of 20 Hz, and a temperature of 60 ° C. Tan δ (60 ° C.) was measured.
The results are shown in Table 1. The results were expressed as an index with Comparative Example 1 as 100. The smaller the index, the better the rolling performance (low rolling resistance). Practically, it is preferably 96 or less.

<Abrasion resistance>
The amount of wear of the obtained vulcanized rubber sheet was measured using a Ramborn wear tester (manufactured by Iwamoto Seisakusho) in accordance with JIS K6264-1, 2: 2005 under the conditions of a temperature of 20 ° C. and a slip ratio of 50%. ..
The results are shown in Table 1. The result shows the one indexed by the following equation with the wear amount of Comparative Example 1 as 100. The larger the index, the smaller the amount of wear and the better the wear resistance performance. Practically, it is preferably 100 or more.
Abrasion resistance = (Amount of wear in Comparative Example 1 / Amount of wear of sample) x 100

<Viscosity>
The obtained rubber composition for tire tread was subjected to Mooney viscosity under the conditions of preheating time 1 minute, rotor rotation time 4 minutes, and test temperature 100 ° C. using an L-shaped rotor according to JIS K6300-1: 2013. It was measured.
The results are shown in Table 1. The results were expressed as an index with Comparative Example 1 as 100. The smaller the index, the smaller the viscosity and the better the workability. Practically, it is preferably 100 or less.

Details of each component in Table 1 above are as follows.
-Specific conjugated diene rubber 1: Specific conjugated diene rubber manufactured as described above 1
-Comparative conjugated diene rubber 1: Comparative conjugated diene rubber manufactured as described above 1
-Specific conjugated diene rubber 2: Specific conjugated diene rubber 2 manufactured as described above.
-Comparative conjugated diene rubber 2: Comparative conjugated diene rubber 2 manufactured as described above.
-Specific conjugated diene rubber 3: Specific conjugated diene rubber 3 manufactured as described above.
-Comparative conjugated diene rubber 3: Comparative conjugated diene rubber 3 manufactured as described above.
-Specific conjugated diene rubber 4: Specific conjugated diene rubber 4 manufactured as described above.
-Specific conjugated diene rubber 5: Specific conjugated diene rubber 5 manufactured as described above.
-BR1220: Nipol BR1220 (butadiene rubber, glass transition temperature: -106 ° C, manufactured by Zeon Corporation)
-Specific modified BR1: Specific modified BR1 manufactured as described above.
-Specific modified BR2: Specific modified BR2 manufactured as described above.
Comparative modified BR1: Comparative modified BR1 manufactured as described above.
7000GR: ULTRASIL 7000GR (silica, CTAB adsorption specific surface area: 160m ² / g, manufactured by Evonik)
・ N339: Show Black N339 (Carbon Black, manufactured by Cabot Japan)
-Si69: Si69 (silane coupling agent, bis (3-triethoxysilylpropyl) tetrasulfide)
・ Zinc oxide: 3 types of zinc oxide (manufactured by Shodo Chemical Industry Co., Ltd.)
・ Stearic acid: Beaded stearic acid (manufactured by NOF CORPORATION)
-Processing aid: Actiplast ST (manufactured by Rhein Chemie)
・ Anti-aging agent: Ozonon 6C (manufactured by Seiko Kagaku Co., Ltd.)
・ Process oil: Extract No. 4 S (manufactured by Showa Shell Sekiyu Co., Ltd.)
-Sulfur: Fine powdered sulfur with Jinhua stamp oil (sulfur content 95.24% by mass, manufactured by Tsurumi Chemical Industry Co., Ltd.)
-Vulcanization accelerator (CZ): Noxeller CZ-G manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
-Vulcanization accelerator (DPG): 1,3-diphenylguanidine (Soxinol DG, manufactured by Sumitomo Chemical Co., Ltd.)

In Table 1, "St" and "Vn" are the content (mass%) of the aromatic vinyl monomer (styrene monomer) unit and the conjugated diene in the conjugated diene rubber or the specific modified BR, respectively. It means the vinyl bond content (% by mass) in the monomer unit. Further, "Mw", "Tg" and "Mw / Mn" are the weight average molecular weight (Mw), glass transition temperature (Tg) (° C.) and molecular weight distribution (Mw /) of the conjugated diene rubber or the specific modified BR, respectively. Mn) means.

As can be seen from Table 1, Examples 1 to 6 in which the specific conjugated diene rubber and the specific modified BR are used in combination showed excellent rolling performance, wear resistance and workability. Among them, Examples 1 to 3 and 6 in which the content of the specific conjugated diene rubber in the conjugated diene rubber was 50% by mass or more showed more excellent rolling performance.
From the comparison between Examples 1 and 2 (contrast between modes in which only the type of the specific modified BR is different), Example 1 in which the Mw / Mn of the specific modified BR is 1.3 or less has better rolling performance and resistance. It showed wear performance and workability.
Further, from the comparison between Examples 3 and 6 (contrast between modes having the same aromatic vinyl monomer unit content of the specific conjugated diene rubber), Example 3 in which the specific conjugated diene rubber contains a PI block. Showed better rolling performance, wear resistance and workability.

On the other hand, Comparative Example 1 containing a specific conjugated diene rubber but not containing a specific modified BR, Comparative Example 2 containing a specific conjugated diene rubber and a specific modified BR, and a specific conjugated diene rubber containing a specific modified BR. Comparative Examples 3 to 5 which do not contain the specific conjugated diene rubber and Comparative Example 6 which contains the specific conjugated diene rubber but does not contain the specific modified BR and contains the modified BR having a molecular weight distribution exceeding 2.0 have rolling performance and abrasion resistance. At least one of performance and workability was inadequate.

1 bead part 2 sidewall part 3 tire tread part 4 carcass layer 5 bead core 6 bead filler 7 belt layer 8 rim cushion

Claims (4)

Conjugated diene rubber containing 10% by mass or more of specific conjugated diene rubber having a weight average molecular weight of more than 100,000, and
With silica
Silane coupling agent and
Containing with specific modified butadiene polymer,
The silica content is 30 parts by mass or more with respect to 100 parts by mass of the conjugated diene rubber.
The content of the silane coupling agent is 3 to 30% by mass with respect to the content of the silica.
In the first step, the specific conjugated diene-based rubber polymerizes a monomer containing a conjugated diene compound in an inert solvent using a polymerization initiator to obtain a conjugated diene-based polymer chain having an active terminal. The polyorganosiloxane represented by the following general formula (1) is added to the conjugated diene polymer chain having the active terminal with respect to 1 mol of the polymerization initiator used in the first step, in the polyorganosiloxane. The second step of adding and reacting the siloxane structure (-Si-O-) at a ratio of 1 mol or more in terms of the number of repeating units, and the conjugated diene-based weight obtained by reacting the polyorganosiloxane obtained in the second step. A conjugated diene-based rubber produced by a method for producing a conjugated diene-based rubber, which comprises a third step of reacting a coalesced chain with a compound represented by the following general formula (2).
The specific modified butadiene polymer has a functional group containing a nitrogen atom and a silicon atom at the end, has a weight average molecular weight of 1,000 or more and 100,000 or less, and has a molecular weight distribution of 2.0 or less. A rubber composition for tire treads.

In the general formula (1), R ¹ to R ⁸ are an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, and these may be the same or different from each other.
In the general formula (1), X ¹ and X ⁴ contain an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and an epoxy group. Any group selected from the group consisting of 4 to 12 groups, which may be the same or different from each other.
In the general formula (1), X ² is an alkoxy group having 1 to 5 carbon atoms or a group having 4 to 12 carbon atoms containing an epoxy group, and a plurality of X ^2s are different even if they are the same as each other. May be.
In the general formula (1), X ³ is a group containing repeating units of 2 to 20 alkylene glycols, and when there are a plurality of X ³ , they may be the same or different from each other.
In the general formula (1), m is an integer of 3 to 200, n is an integer of 0 to 200, k is an integer of 0 to 200, and m + n + k is 3 or more.

In the general formula (2), R ⁹ is a hydrocarbyl group.
In the general formula (2), A ¹ is a group capable of reacting with a reaction residue generated by a reaction between a conjugated diene polymer chain having an active terminal and polyorganosiloxane.
In the general formula (2), A ² is a group containing a nitrogen atom.
In the general formula (2), p is an integer of 0 to 2, q is an integer of 1 to 3, r is an integer of 1 to 3, and p + q + r = 4. The rubber composition for a tire tread according to claim 1 , wherein the content of the specific modified butadiene polymer is 1 to 25% by mass with respect to the content of the silica. The specific conjugated diene rubber
A polymer block (A) containing 80 to 100% by mass of an isoprene monomer unit and 0 to 20% by mass of an aromatic vinyl monomer unit, and
The claim has a structure in which a polymer block (B) containing 50 to 100% by mass of a 1,3-butadiene monomer unit and 0 to 50% by mass of an aromatic vinyl monomer unit is formed in succession. Rubber composition for tire tread in 1 or 2 . A pneumatic tire including a tire tread portion manufactured by using the rubber composition for tire tread according to any one of claims 1 to 3 .

Images