JP2014125553A - Rubber composition for base tread, and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for base tread, which improves mileage, rupture strength, and processability in a well balanced manner, and a pneumatic tire using the same.SOLUTION: The rubber composition for base tread contains rubber components, silica, and polyalkylene glycol having a branch structure. In 100 mass% of rubber components, the content of a conjugated diene polymer having the structural unit derived from a conjugated diene and the structural unit derived from a compound represented by the following formula (1) is 5 mass% or more. Relative to 100 mass parts of rubber components, the content of silica is 5 to 150 mass parts, and the content of polyalkylene glycol is 0.1 to 10 mass parts. [Formula 1]

Description

The present invention relates to a rubber composition for a base tread and a pneumatic tire produced using the rubber composition.

Conventionally, a method of blending silica as a filler is known as a technique for reducing rolling resistance of a tire (reducing fuel consumption of a vehicle). For example, rolling resistance can be reduced by blending silica in a tread. At the same time, WET traction performance can be improved at the same time. Patent Documents 1 to 3 disclose a method of improving fuel efficiency by blending two types of silica having different nitrogen adsorption specific surface areas and particle diameters into a tread. However, there is a limit to the improvement in fuel efficiency when only the tread is improved, and the base tread is also required to have excellent low heat generation.

Unlike the tread, carbon black having a large particle size has been used for the base tread in order to improve fuel efficiency. Therefore, even if part or all of the carbon black is replaced with silica, the effect of reducing rolling resistance is not so great. Moreover, there is also a problem that the workability and the fracture strength are reduced by the replacement. As another technique capable of reducing the rolling resistance, a method of reducing the content of the filler is also known, but this method also has a problem that the fracture resistance is lowered. Therefore, there is a demand for a method for improving fuel economy, fracture resistance and workability in a well-balanced manner.

JP 2006-233177 A JP 2008-50570 A JP 2008-101127 A

An object of the present invention is to solve the above-mentioned problems and provide a rubber composition for a base tread that can improve fuel economy, fracture resistance, and processability in a well-balanced manner, and a pneumatic tire using the same.

（式中、ｍは１又は２を表し、ｎは１又は２を表し、ｍ＋ｎは２又は３であり、Ｒ^１は重合性炭素−炭素二重結合を有するヒドロカルビル基を表し、Ｒ^２はヒドロカルビル基を表し、Ｒ^２が複数ある場合、複数あるＲ^２は同一でも異なっていてもよく、Ｒ^３は含酸素置換基を有していてもよいアリール基を表し、Ｒ^３が複数ある場合、複数あるＲ^３は同一でも異なっていてもよく、Ｒ^４はアルキル基、又は置換アミノ基を表す。） The present invention contains a rubber component, silica, and a polyalkylene glycol having a branched structure, and is based on a structural unit based on a conjugated diene and a compound represented by the following formula (1) in 100% by mass of the rubber component. The content of the conjugated diene polymer having a structural unit is 5% by mass or more, the content of the silica is 5 to 150 parts by mass, and the content of the polyalkylene glycol is 100 parts by mass of the rubber component. It is related with the rubber composition for base treads which is 0.1-10 mass parts.

(Wherein m represents 1 or 2, n represents 1 or 2, m + n is 2 or 3, R ¹ represents a hydrocarbyl group having a polymerizable carbon-carbon double bond, and R ² represents hydrocarbyl. represents a group, when R ² are a plurality, a plurality of R ² may be the same or different, R ³ represents an aryl group which may have an oxygen-containing substituent, if there are a plurality of R ^3, Multiple R ³ groups may be the same or different, and R ⁴ represents an alkyl group or a substituted amino group.)

（式中、ｐは０又は１であり、Ｒ^５は水素原子又はヒドロカルビル基を表し、Ｔはヒドロカルビレン基を表す。） M + n of the compound represented by the formula (1) is 3, R ¹ is a group represented by the following formula (2), R ² is a tertiary alkyl group, and R ³ has an alkyl group. It is preferably an optionally substituted phenyl group.

(In the formula, p is 0 or 1, R ⁵ represents a hydrogen atom or a hydrocarbyl group, and T represents a hydrocarbylene group.)

It is preferable that R ^{1 of the} compound represented by the formula (1) is a vinyl group.

It is preferable that 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 is 1.0 to 1.5.

The vinyl bond content of the conjugated diene polymer is preferably 20 mol% or more and 70 mol% or less, with the content of the structural unit based on diene being 100 mol%.

［式中、ｙ^１、ｙ^２及びｙ^３は、同一又は異なって、２〜４０の整数を表す。］ The polyalkylene glycol is preferably a compound represented by the following formula (I).

[Wherein, y ¹ , y ² and y ³ are the same or different and each represents an integer of 2 to 40. ]

The present invention also relates to a pneumatic tire produced using the rubber composition.

According to the present invention, since it is a rubber composition in which predetermined amounts of a conjugated diene polymer having a specific monomer unit, silica, and a polyalkylene glycol having a branched structure are blended, low fuel consumption and resistance A pneumatic tire having improved fracture strength and workability in a well-balanced manner can be provided.

（式中、ｍは１又は２を表し、ｎは１又は２を表し、ｍ＋ｎは２又は３であり、Ｒ^１は重合性炭素−炭素二重結合を有するヒドロカルビル基を表し、Ｒ^２はヒドロカルビル基を表し、Ｒ^２が複数ある場合、複数あるＲ^２は同一でも異なっていてもよく、Ｒ^３は含酸素置換基を有していてもよいアリール基を表し、Ｒ^３が複数ある場合、複数あるＲ^３は同一でも異なっていてもよく、Ｒ^４はアルキル基、又は置換アミノ基を表す。） The conjugated diene polymer according to the present invention has a monomer unit based on a conjugated diene and a monomer unit based on a monomer represented by the following formula (1).

(Wherein m represents 1 or 2, n represents 1 or 2, m + n is 2 or 3, R ¹ represents a hydrocarbyl group having a polymerizable carbon-carbon double bond, and R ² represents hydrocarbyl. represents a group, when R ² are a plurality, a plurality of R ² may be the same or different, R ³ represents an aryl group which may have an oxygen-containing substituent, if there are a plurality of R ^3, Multiple R ³ groups may be the same or different, and R ⁴ represents an alkyl group or a substituted amino group.)

As used herein, a hydrocarbyl group represents a hydrocarbon residue. The hydrocarbyloxy group represents a group in which a hydrogen atom of a hydroxyl group is substituted with a hydrocarbyl group. The hydrocarbylene group represents a divalent hydrocarbon residue.

Examples of the conjugated diene include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 1,3-hexadiene and the like, and one or more of these are used. . The conjugated diene is preferably 1,3-butadiene or isoprene.

R ¹ is a hydrocarbyl group having a polymerizable carbon-carbon double bond, and R ¹ is preferably a group represented by the following formula (2).

（式中、ｐは０又は１であり、Ｒ^５は水素原子又はヒドロカルビル基を表し、Ｔはヒドロカルビレン基を表す。）

(In the formula, p is 0 or 1, R ⁵ represents a hydrogen atom or a hydrocarbyl group, and T represents a hydrocarbylene group.)

In the formula (2), p represents 0 or 1.

Examples of the hydrocarbyl group for R ⁵ include an alkyl group and an alkenyl group. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, and a tert-butyl group, and a methyl group is preferable. Examples of the alkenyl group include a vinyl group, an allyl group, a 1-propenyl group, and a 1-methylethenyl group, and a vinyl group is preferable.

R ⁵ is preferably a hydrogen atom, a methyl group, or a vinyl group, and more preferably a hydrogen atom.

Examples of the hydrocarbylene group for T include an alkylene group, an arylene group, and a group in which an arylene group and an alkylene group are bonded.

Examples of the alkylene group include a methylene group, an ethylene group, and a trimethylene group. Preferably, it is a methylene group or an ethylene group. Examples of the arylene group include a phenylene group, a naphthylene group, and a biphenylene group. A phenylene group is preferred.

Examples of the group in which an arylene group and an alkylene group are bonded include a group in which a phenylene group and an alkylene group are bonded, a group in which a naphthylene group and an alkylene group are bonded, and a group in which a biphenylene group and an alkylene group are bonded. . In a group in which a phenylene group and an alkylene group are bonded (phenylene-alkylene group), depending on the position of the carbon atom on the benzene ring from which the hydrogen atom is removed and the position of the carbon atom on the benzene ring to which the alkylene group is bonded, A para-phenylene-alkylene group (for example, a group represented by the following formula (2a)), a meta-phenylene-alkylene group (for example, a group represented by the following formula (2b)), an ortho-phenylene-alkylene group. (For example, a group represented by the following formula (2c)).

Further, as the group in which the arylene group and the alkylene group are bonded, it is preferable that the carbon atom of the arylene group of the group is bonded to the carbon atom to which R ^{5 in} the formula (2) is bonded.

（式中、ｒ、ｓ、ｔは、夫々、１〜１０の整数を表す。）

(Wherein, r, s, and t each represent an integer of 1 to 10)

The group in which an arylene group and an alkylene group are bonded (phenylene-alkylene group) is preferably a group in which a phenylene group and an alkylene group are bonded, more preferably a group represented by the above formula (2a), A group represented by the above formula (2b), more preferably a para-phenylene-methylene group (a group represented by the formula (2a) where r = 1), a meta-phenylene-methylene group (s = 1). A group represented by the formula (2b), a para-phenylene-ethylene group (a group represented by the formula (2a) where r = 2), a meta-phenylene-ethylene group (a formula where s = 2) Group represented by 2b).

When R ⁵ is a methyl group, p is preferably 1, and T is preferably a group in which an arylene group and an alkylene group are bonded or an arylene group, more preferably a phenylene group and an alkylene group. A bonded group (phenylene-alkylene group) or a phenylene group, more preferably a phenylene group, a para-phenylene-methylene group, a meta-phenylene-methylene group, a para-phenylene-ethylene group, or a meta-phenylene-ethylene group. is there.

When R ⁵ is a vinyl group and p is 1, T is preferably an alkylene group, more preferably a methylene group or an ethylene group.

The group represented by the formula (2) is preferably a group in which R ⁵ is a hydrogen atom, such as vinyl group, vinylmethyl group, vinylethyl group, 4-vinylphenyl group, 3-vinylphenyl group, (4- Vinylphenyl) methyl group, 2- (4-vinylphenyl) ethyl group, (3-vinylphenyl) methyl group, 2- (3-vinylphenyl) ethyl group, and R ⁵ is a methyl group, 4-isopropenylphenyl group, 3-isopropenylphenyl group, (4-isopropenylphenyl) methyl group, 2- (4-isopropenylphenyl) ethyl group, (3-isopropenylphenyl) methyl group, 2- (3 - isopropenyl phenyl) ethyl group and the like, as ^the radicals ^{R 5} is a vinyl group, 1-methylene-2-propenyl group, 2-methylene-3-butenyl group It is below.

R ¹ is preferably a vinyl group, a 4-vinylphenyl group, or a 3-vinylphenyl group, and more preferably a vinyl group.

Examples of the hydrocarbyl group for R ² include an alkyl group and an aryl group.

Examples of the alkyl group for R ² include a methyl group; a primary alkyl group such as an ethyl group, an n-propyl group, and an n-pentyl group (an alkyl group in which a carbon atom from which a hydrogen atom has been removed is a primary carbon atom); Secondary alkyl groups such as isopropyl group, sec-butyl group and 2-ethylhexyl group (alkyl groups in which a carbon atom from which a hydrogen atom has been removed is a secondary carbon atom); tert-butyl group, tert-pentyl group and the like A tertiary alkyl group (an alkyl group in which a carbon atom from which a hydrogen atom has been removed is a tertiary carbon atom) can be mentioned.

Examples of the aryl group for R ² include a phenyl group, a tolyl group, and a xylyl group.

The number of carbon atoms of the hydrocarbyl group represented by R ² is preferably 3 to 10, more preferably 4 to 8.

The hydrocarbyl group for R ² is preferably a secondary alkyl group or a tertiary alkyl group, more preferably a tertiary alkyl group, and still more preferably a tert-butyl group.

R ³ is an aryl group which may have an oxygen-containing substituent. Here, the aryl group having an oxygen-containing substituent represents a group in which a hydrogen atom of the aryl group is substituted with an oxygen-containing substituent.

The aryl group of R ³ includes a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a phenyl group substituted with an alkyl group, a 1-naphthyl group substituted with an alkyl group, and a 2-naphthyl substituted with an alkyl group. You can raise a group.

Examples of the alkyl group include: methyl group; primary alkyl group such as ethyl group, n-propyl group and n-butyl group; secondary alkyl group such as isopropyl group, sec-butyl group and 2-ethylhexyl group; And tertiary alkyl groups such as a tert-pentyl group.

Examples of the phenyl group substituted with an alkyl group include methylphenyl group, ethylphenyl group, n-propylphenyl group, isopropylphenyl group, n-butylphenyl group, sec-butylphenyl group, tert-butylphenyl group, and tert-pentyl. A phenyl group, a (2-ethylhexyl) phenyl group, etc. can be mentioned.

Examples of 1-naphthyl group substituted with an alkyl group include methyl-1-naphthyl group, ethyl-1-naphthyl group, n-propyl-1-naphthyl group, isopropyl-1-naphthyl group, and n-butyl-1-naphthyl group. Group, sec-butyl-1-naphthyl group, tert-butyl-1-naphthyl group, tert-pentyl-1-naphthyl group, (2-ethylhexyl) -1-naphthyl group, and the like.

Examples of the 2-naphthyl group substituted with an alkyl group include methyl-2-naphthyl group, ethyl-2-naphthyl group, n-propyl-2-naphthyl group, isopropyl-2-naphthyl group, and n-butyl-2-naphthyl group. Group, sec-butyl-2-naphthyl group, tert-butyl-2-naphthyl group, tert-pentyl-2-naphthyl group, (2-ethylhexyl) -2-naphthyl group and the like.

The aryl group having an oxygen-containing substituent is an alkoxy group such as a methoxy group, an ethoxy group, an isopropoxy group or a tert-butoxy group; an alkoxyalkyl group such as a methoxymethyl group, an ethoxymethyl group, a methoxyethyl group or an ethoxyethyl group An aryl group having an alkoxyalkoxy group such as a methoxymethoxy group, an ethoxymethoxy group, a methoxyethoxy group, or an ethoxyethoxy group.

Examples of the phenyl group having an alkoxy group include a methoxyphenyl group, an ethoxyphenyl group, an isopropoxyphenyl group, and a tert-butoxyphenyl group. Examples of the phenyl group having an alkoxyalkyl group include (methoxymethyl) phenyl group, (ethoxymethyl) phenyl group, (methoxyethyl) phenyl group, and (ethoxyethyl) phenyl group. Examples of the phenyl group having an alkoxyalkoxy group include (methoxymethoxy) phenyl group, (ethoxymethoxy) phenyl group, (methoxyethoxy) phenyl group, and (ethoxyethoxy) phenyl group.

Examples of the 1-naphthyl group having an alkoxy group include a methoxy-1-naphthyl group, an ethoxy-1-naphthyl group, an isopropoxy-1-naphthyl group, and a tert-butoxy-1-naphthyl group. Examples of the 1-naphthyl group having an alkoxyalkyl group include (methoxymethyl) -1-naphthyl group, (ethoxymethyl) -1-naphthyl group, (methoxyethyl) -1-naphthyl group, and (ethoxyethyl) -1-naphthyl. You can raise a group. Examples of the 1-naphthyl group having an alkoxyalkoxy group include (methoxymethoxy) -1-naphthyl group, (ethoxymethoxy) -1-naphthyl group, (methoxyethoxy) -1-naphthyl group, and (ethoxyethoxy) -1-naphthyl. You can raise a group.

Examples of the 2-naphthyl group having an alkoxy group include a methoxy-2-naphthyl group, an ethoxy-2-naphthyl group, an isopropoxy-2-naphthyl group, and a tert-butoxy-2-naphthyl group. Examples of the 2-naphthyl group having an alkoxyalkyl group include (methoxymethyl) -2-naphthyl group, (ethoxymethyl) -2-naphthyl group, (methoxyethyl) -2-naphthyl group, and (ethoxyethyl) -2-naphthyl. You can raise a group. Examples of the 2-naphthyl group having an alkoxyalkoxy group include (methoxymethoxy) -2-naphthyl group, (ethoxymethoxy) -2-naphthyl group, (methoxyethoxy) -2-naphthyl group, and (ethoxyethoxy) -2-naphthyl. You can raise a group.

Examples of the mono-substituted phenyl group include a 2-substituted phenyl group, a 3-substituted phenyl group, and a 4-substituted phenyl group depending on the substitution position. The phenyl group substituted with the above alkyl group or oxygen-containing substituent may be a disubstituted or trisubstituted product, and depending on the substitution position and the number of substitutions, a 2,3-disubstituted phenyl group, 2, 4-disubstituted phenyl group, 2,5-disubstituted phenyl group, 2,6-disubstituted phenyl group, 3,4-disubstituted phenyl group, 3,5-disubstituted phenyl group, 2,3,4-tri Substituted phenyl group, 2,3,5-trisubstituted phenyl group, 2,4,5-trisubstituted phenyl group, 2,4,6-trisubstituted phenyl group, 3,4,5-trisubstituted phenyl group, etc. It is done.

The mono-substituted 1-naphthyl group may be a 2-substituted 1-naphthyl group, a 3-substituted 1-naphthyl group, a 4-substituted 1-naphthyl group, a 5-substituted 1-naphthyl group, or a 6-substituted, depending on the substitution position. A 1-naphthyl group can be mentioned. Further, the 1-naphthyl group substituted with the above alkyl group or oxygen-containing substituent may be a di- or 3-substituent, and may be a 4,5-disubstituted 1-naphthyl group, 4,8-di- Substituted 1-naphthyl group, 5,8-disubstituted 1-naphthyl group, 6,7-disubstituted 1-naphthyl group, 3,8-disubstituted 1-naphthyl group, 6,8-disubstituted 1-naphthyl group, 4,5,8-trisubstituted 1-naphthyl group and the like.

The mono-substituted 2-naphthyl group may be a 1-substituted 2-naphthyl group, a 3-substituted 2-naphthyl group, a 4-substituted 2-naphthyl group, a 5-substituted 2-naphthyl group, or a 6-substituted, depending on the substitution position. A 2-naphthyl group can be mentioned. Further, the 1-naphthyl group substituted with the above alkyl group or oxygen-containing substituent may be a di- or 3-substituent, such as a 3,5-disubstituted 2-naphthyl group, 3,8-di- Examples thereof include a substituted 2-naphthyl group, a 4,5-disubstituted 2-naphthyl group, and a 1,4,5-trisubstituted 2-naphthyl group.

The number of carbon atoms of R ³ is preferably 6 to 10, more preferably 6 to 8.

R ³ is preferably a phenyl group or a phenyl group substituted with an alkyl group. The phenyl group substituted with an alkyl group is preferably a 4-alkylphenyl group, more preferably a 4-methylphenyl group, a 4-ethylphenyl group, a 4-n-propylphenyl group, a 4-n- It is a butylphenyl group.

R ³ is more preferably a phenyl group, a 4-methylphenyl group or a 4-ethylphenyl group, and even more preferably a phenyl group.

Examples of the alkyl group for R ⁴ include a methyl group and an ethyl group.

（式中、Ｒ^６及びＲ^７は、それぞれ、ヒドロカルビル基、又は、トリヒドロカルビルシリル基を表し、あるいは、Ｒ^６とＲ^７は結合して、窒素原子及び／又は酸素原子をヘテロ原子として有していてもよいヒドロカルビレン基、又は、Ｒ^６とＲ^７は１つの基であって、窒素原子に二重結合で結合する基を表す。） Examples of the substituted amino group for R ⁴ include a group represented by the following formula (3).

(Wherein R ⁶ and R ⁷ each represent a hydrocarbyl group or a trihydrocarbylsilyl group, or R ⁶ and R ⁷ are bonded to each other and have a nitrogen atom and / or an oxygen atom as a hetero atom. And an optional hydrocarbylene group, or R ⁶ and R ⁷ are one group and represent a group bonded to a nitrogen atom by a double bond.)

Examples of the hydrocarbyl group of R ⁶ and R ⁷ include an alkyl group and an aryl group. Examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, and tert-butyl group. A phenyl group etc. can be mention | raise | lifted as an aryl group. Preferably it is an alkyl group, More preferably, it is a C1-C4 alkyl group.

Examples of the trihydrocarbylsilyl group of R ⁶ and R ⁷ include trialkylsilyl groups such as a trimethylsilyl group, a triethylsilyl group, a triisopropylsilyl group, and a tert-butyldimethylsilyl group. A trialkylsilyl group having 3 to 9 carbon atoms is preferable, and a trialkylsilyl group in which an alkyl group bonded to a silicon atom is an alkyl group having 1 to 3 carbon atoms is more preferable.

Examples of the hydrocarbylene group which may have a nitrogen atom and / or an oxygen atom bonded to R ⁶ and R ⁷ as a hetero atom include an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, and the like An alkylene group; a group represented by —CH ₂ CH ₂ —NH—CH ₂ —, a group represented by —CH ₂ CH ₂ —N═CH—, and a group represented by —CH═CH—N═CH—. Group, a hydrocarbylene group having a nitrogen atom such as a group represented by —CH ₂ CH ₂ —NH—CH ₂ CH ₂ —; a group represented by —CH ₂ CH ₂ —O—CH ₂ CH ₂ —, etc. And a hydrocarbylene group having an oxygen atom.

In the present specification, the hydrocarbylene group having an X atom as a hetero atom represents a group having a structure in which a hydrogen atom and / or a carbon atom of the hydrocarbylene group is replaced with an X atom. For example, examples of the hydrocarbylene group having a nitrogen atom as a hetero atom include a group having a structure in which CH in the hydrocarbylene group is replaced with N. Examples of the hydrocarbylene group having an oxygen atom as a hetero atom include a group having a structure in which CH ₂ is replaced with O and a group having a structure in which two hydrogen atoms are replaced with O.

Examples of one group in which R ⁶ and R ⁷ are bonded to the nitrogen atom by a double bond include ethylidene group, propylidene group, butylidene group, 1-methylethylidene group, 1-methylpropylidene group, 1,3-dimethylbutylidene Group.

R ⁴ is preferably an alkyl group such as a methyl group or an ethyl group, or a dialkylamino group such as a dimethylamino group, a diethylamino group, a di (n-propyl) amino group, or a di (n-butyl) amino group.

In the formula (1), n represents 1 or 2, and m + n is 2 or 3. Preferably m + n is 3. More preferably, m is 1 and n is 2.

As the compound represented by the formula (1), as a compound in which R ⁵ is a hydrogen atom and p = 0,
tert-butoxydiphenylvinylsilane,
tert-pentoxydiphenylvinylsilane,
Di (tert-butoxy) phenylvinylsilane,
Di (tert-pentoxy) phenylvinylsilane,
tert-butoxymethylphenylvinylsilane,
tert-butoxyethylphenylvinylsilane,
Dimethylamino tert-butoxyphenylvinylsilane,
Diethylamino tert-butoxyphenylvinylsilane,
Etc.

Moreover, as a compound represented by Formula (1), as a compound whose R < ⁵ > is a hydrogen atom and p = 1,
tert-butoxydiphenyl-4-vinylphenylsilane,
tert-butoxydiphenyl-3-vinylphenylsilane,
Di (tert-butoxy) phenyl-4-vinylphenylsilane,
Di (tert-butoxy) phenyl-3-vinylphenylsilane,
tert-butoxymethylphenyl-4-vinylphenylsilane,
tert-butoxymethylphenyl-3-vinylphenylsilane,
tert-butoxyethylphenyl-4-vinylphenylsilane,
tert-butoxyethylphenyl-3-vinylphenylsilane,
Dimethylamino tert-butoxyphenyl-4-vinylphenylsilane,
Dimethylamino tert-butoxyphenyl-3-vinylphenylsilane,
Diethylamino tert-butoxyphenyl-4-vinylphenylsilane,
Diethylamino tert-butoxyphenyl-3-vinylphenylsilane,
Etc.

As a compound represented by the formula (1), R ⁵ is a methyl group, and p = 1,
tert-butoxydiphenyl-4-isopropenylphenylsilane,
tert-butoxydiphenyl-3-isopropenylphenylsilane,
Di (tert-butoxy) phenyl-4-isopropenylphenylsilane,
Di (tert-butoxy) phenyl-3-isopropenylphenylsilane,
tert-butoxymethylphenyl-4-isopropenylphenylsilane,
tert-butoxymethylphenyl-3-isopropenylphenylsilane,
tert-butoxyethylphenyl-4-isopropenylphenylsilane,
tert-butoxyethylphenyl-3-isopropenylphenylsilane,
Dimethylamino tert-butoxyphenyl-4-isopropenylphenylsilane,
Dimethylamino tert-butoxyphenyl-3-isopropenylphenylsilane,
Diethylamino tert-butoxyphenyl-4-isopropenylphenylsilane,
Diethylamino tert-butoxyphenyl-3-isopropenylphenylsilane,
Etc.

The compound represented by the formula (1) is preferably a compound in which R ⁵ is a hydrogen atom and p = 0.
More preferably,
tert-butoxydiphenylvinylsilane,
Di (tert-butoxy) phenylvinylsilane,
tert-butoxymethylphenylvinylsilane,
Dimethylamino-tert-butoxyphenylvinylsilane,
Diethylamino-tert-butoxyphenylvinylsilane;
More preferably, tert-butoxydiphenylvinylsilane,
Di (tert-butoxy) phenylvinylsilane,
Particularly preferred is tert-butoxydiphenylvinylsilane.

The content of the monomer unit based on the compound represented by the formula (1) is preferably 0.01% by mass or more, more preferably, per 100% by mass of the conjugated diene polymer in order to increase the strength. It is 0.02 mass% or more. Moreover, in order to improve economical efficiency, Preferably it is 2 mass% or less, More preferably, it is 1 mass% or less.

In the conjugated diene polymer according to the present invention, the monomer unit based on the monomer represented by the formula (1) is present in the chain, that is, the partial chain having the monomer unit based on the conjugated diene. (The partial chain does not have a monomer unit based on the monomer represented by the formula (1).) And a partial chain having a monomer unit based on a conjugated diene (the partial chain includes The monomer unit based on the monomer represented by the formula (1), or the monomer unit based on the monomer represented by the formula (1) It is preferable to have a partial chain composed of monomer units based on the monomer represented by (1).

The conjugated diene polymer according to the present invention preferably has monomer units (vinyl aromatic hydrocarbon units) based on vinyl aromatic hydrocarbons in order to increase strength. Examples of the vinyl aromatic hydrocarbon include styrene, α-methylstyrene, vinyl toluene, vinyl naphthalene, divinyl benzene, trivinyl benzene, and divinyl naphthalene. Styrene is preferable.

As the content of the vinyl aromatic hydrocarbon unit, the total amount of the conjugated diene unit and the vinyl aromatic hydrocarbon unit is 100% by mass, preferably 10% by mass or more (the content of the conjugated diene unit is 90% by mass or less). More preferably, it is 15% by mass or more (the content of the conjugated diene unit is 85% by mass or less). In order to improve fuel economy, the content of vinyl aromatic hydrocarbon units is preferably 50% by mass or less (the content of conjugated diene units is 50% by mass or more), more preferably 45% by mass or less. (The content of the conjugated diene unit is 55% by mass or more).

The Mooney viscosity (ML _{1 + 4} ) of the conjugated diene polymer according to the present invention is preferably 10 or more, more preferably 20 or more, in order to increase the strength. Moreover, in order to improve workability, Preferably it is 200 or less, More preferably, it is 150 or less. The Mooney viscosity (ML _{1 + 4} ) is measured at 100 ° C. according to JIS K6300 (1994).

The vinyl bond content of the conjugated diene polymer according to the present invention is preferably 80 mol% or less, more preferably 70 mol%, in order to improve fuel efficiency, with the content of the conjugated diene unit being 100 mol%. It is as follows. Moreover, in order to improve grip property, Preferably it is 10 mol% or more, More preferably, it is 15 mol% or more, More preferably, it is 20 mol% or more, Most preferably, it is 40 mol% or more. The vinyl bond amount is determined from the absorption intensity in the vicinity of 910 cm ^−1, which is the absorption peak of the vinyl group, by infrared spectroscopy.

The molecular weight distribution of the conjugated diene polymer according to the present invention is preferably 1.0 to 5.0, and more preferably 1.0 to 1.5 in order to improve fuel economy. The molecular weight distribution is determined by measuring the number average molecular weight (Mn) and the weight average molecular weight (Mw) by gel permeation chromatography (GPC) method and dividing Mw by Mn.

As a preferred method for producing a conjugated diene polymer according to the present invention, a monomer component containing a conjugated diene and a compound represented by the above formula (1) is polymerized with an alkali metal catalyst in a hydrocarbon solvent. Can be given.

Examples of the alkali metal catalyst include alkali metals, organic alkali metal compounds, complexes of alkali metals and polar compounds, oligomers having alkali metals, and the like. Examples of the alkali metal include lithium, sodium, potassium, rubidium, cesium and the like. Examples of the organic alkali metal compound include ethyl lithium, n-propyl lithium, iso-propyl lithium, n-butyl lithium, sec-butyl lithium, t-octyl lithium, n-decyl lithium, phenyl lithium, 2-naphthyl lithium, 2 -Butylphenyllithium, 4-phenylbutyllithium, cyclohexyllithium, 4-cyclopentyllithium, dimethylaminopropyllithium, diethylaminopropyllithium, t-butyldimethylsiloxypropyllithium, N-morpholinopropyllithium, lithium hexamethyleneimide, lithium pyrrole Zido, lithium piperidide, lithium heptamethylene imide, lithium dodecamethylene imide, 1,4-dilithio-2-butene, sodium naphthalenide, sodium Bifenirido, such as potassium napthalenide can be mentioned. Examples of the complex of alkali metal and polar compound include potassium-tetrahydrofuran complex and potassium-diethoxyethane complex. Examples of the oligomer having alkali metal include sodium salt of α-methylstyrene tetramer. Can do. An organic lithium compound or an organic sodium compound is preferable, and an organic lithium compound having 2 to 20 carbon atoms or an organic sodium compound having 2 to 20 carbon atoms is more preferable.

The hydrocarbon solvent is a solvent that does not deactivate the organic alkali metal compound catalyst, and examples thereof include aliphatic hydrocarbons, aromatic hydrocarbons, and alicyclic hydrocarbons. Examples of the aliphatic hydrocarbon include propane, n-butane, iso-butane, n-pentane, iso-pentane, n-hexane, propene, 1-butene, iso-butene, trans-2-butene, cis-2- Examples include butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene and the like. Examples of the aromatic hydrocarbon include benzene, toluene, xylene, and ethylbenzene. Examples of the alicyclic hydrocarbon include cyclopentane and cyclohexane. One or more of these may be used, and the hydrocarbon solvent may be a mixture of various components such as industrial hexane. Preferably, it is a hydrocarbon having 2 to 12 carbon atoms.

In a hydrocarbon solvent, a monomer component containing a conjugated diene and the compound represented by the above formula (1) is polymerized with an alkali metal catalyst, and the monomer unit based on the conjugated diene and the above formula (1) A polymer having a monomer unit based on the represented compound is produced. Examples of the conjugated diene include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, and 1,3-hexadiene. One or more of these are used. 1,3-butadiene and isoprene are preferred.

The amount of the compound represented by the formula (1) is preferably 0.01% by mass or more in order to increase the strength, with the total amount of the monomer components used in the polymerization being 100% by mass. Preferably it is 0.02 mass% or more. Moreover, in order to improve economical efficiency, Preferably it is 2 mass% or less, More preferably, it is 1 mass% or less.

As the monomer, the conjugated diene and the compound represented by the formula (1) may be polymerized by combining vinyl aromatic hydrocarbons. Examples of the vinyl aromatic hydrocarbon include styrene, α-methylstyrene, Examples thereof include vinyl toluene, vinyl naphthalene, divinyl benzene, trivinyl benzene, divinyl naphthalene and the like. Styrene is preferable.

The amount of vinyl aromatic hydrocarbon used is 0% by mass or more (the amount of conjugated diene used is 100% by mass or less), where the total amount of conjugated diene and vinyl aromatic hydrocarbon is 100% by mass. In order to increase it, it is preferably 10% by mass or more (the amount of conjugated diene used is 90% by mass or less), more preferably 15% by mass or more (the amount of conjugated diene used is 85% by mass or less). In order to improve fuel efficiency, the amount of vinyl aromatic hydrocarbon used is preferably 50% by mass or less (the amount of conjugated diene used is 50% by mass or more), more preferably 45% by mass or less (conjugated). The amount of diene used is 55% by mass or more).

Polymerization reaction is an agent that adjusts the amount of vinyl bonds of conjugated diene units, an agent that adjusts the distribution of monomer units based on monomers other than conjugated diene units and conjugated dienes in the conjugated diene polymer chain , Generally referred to as “regulators”). Examples of such agents include ether compounds, tertiary amines, and phosphine compounds. Examples of the ether compound include cyclic ethers such as tetrahydrofuran, tetrahydropyran, and 1,4-dioxane; aliphatic monoethers such as diethyl ether and dibutyl ether; ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, and diethylene glycol diethyl ether. And aliphatic ethers such as diethylene glycol dibutyl ether; aromatic ethers such as diphenyl ether and anisole. Examples of the tertiary amine include triethylamine, tripropylamine, tributylamine, N, N, N ′, N′-tetramethylethylenediamine, N, N-diethylaniline, pyridine, quinoline and the like. Examples of the phosphine compound include trimethylphosphine, triethylphosphine, triphenylphosphine, and the like. One or more of these are used.

The polymerization temperature is usually 25 to 100 ° C, preferably 35 to 90 ° C, more preferably 50 to 80 ° C. The polymerization time is usually 10 minutes to 5 hours.

In the production method of the present invention, a coupling agent may be added to the hydrocarbon solution of the conjugated diene polymer from the start of polymerization of the monomer using an alkali metal catalyst to the termination of polymerization as necessary. An example of the coupling agent is a compound represented by the following formula (4).

（式中、Ｒ^１１はアルキル基、アルケニル基、シクロアルケニル基またはアリール基を表し、Ｍはケイ素原子またはスズ原子を表し、Ｌはハロゲン原子またはヒドロカルビルオキシ基を表し、ａは０〜２の整数を表す。）

Wherein R ¹¹ represents an alkyl group, an alkenyl group, a cycloalkenyl group or an aryl group, M represents a silicon atom or a tin atom, L represents a halogen atom or a hydrocarbyloxy group, and a is an integer of 0 to 2. Represents.)

As the coupling agent represented by the formula (4), silicon tetrachloride, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, tin tetrachloride, methyltrichlorotin, dimethyldichlorotin, trimethylchlorotin, tetramethoxysilane, methyl Examples include trimethoxysilane, dimethoxydimethylsilane, methyltriethoxysilane, ethyltrimethoxysilane, dimethoxydiethylsilane, diethoxydimethylsilane, tetraethoxysilane, ethyltriethoxysilane, and diethoxydiethylsilane.

The addition amount of the coupling agent is preferably 0.03 mol or more, more preferably 0.05 mol or more, per 1 mol of alkali metal derived from the alkali metal catalyst in order to improve the processability of the conjugated diene polymer. It is. Moreover, in order to improve low-fuel-consumption property, Preferably it is 0.4 mol or less, More preferably, it is 0.3 mol or less.

Conjugated diene polymers can be recovered using known recovery methods, for example, (1) a method of adding a coagulant to a hydrocarbon solution of a conjugated diene polymer, By this method, the conjugated diene polymer can be recovered from the hydrocarbon solution. The recovered conjugated diene polymer may be dried by a known dryer such as a band dryer or an extrusion dryer.

The conjugated diene polymer can be used as a rubber component, and the rubber composition of the present invention can be obtained by blending other rubber components and additives such as silica.

The content of the conjugated diene polymer in 100% by mass of the rubber component is 5% by mass or more, preferably 10% by mass or more, and more preferably 15% by mass or more. If the amount is less than 5% by mass, the effect of improving fuel economy tends to be difficult to obtain. Further, the content of the conjugated diene polymer is preferably 90% by mass or less, more preferably 70% by mass or less. When it exceeds 90% by mass, the fracture strength decreases and the cost tends to increase.

The rubber component that can be used in addition to the conjugated diene polymer is not limited. For example, natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR). ), Chloroprene rubber (CR), butyl rubber (IIR) and the like. These rubber components may be used alone or in combination of two or more. Among these, NR and BR are preferable because they exhibit low fuel consumption, fracture strength and workability in a well-balanced manner.
These rubber components are not particularly limited, and those generally used in the tire industry can be used.

The content of NR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 25% by mass or more, and further preferably 45% by mass or more. If the amount is less than 5% by mass, sufficient fuel economy tends not to be obtained. The NR content is preferably 90% by mass or less, more preferably 70% by mass or less. When it exceeds 90 mass%, workability tends to deteriorate.

The content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 15% by mass or more. If it is less than 5% by mass, sufficient fracture strength tends not to be obtained. Further, the BR content is preferably 60% by mass or less, more preferably 40% by mass or less. When it exceeds 60% by mass, fuel efficiency tends to deteriorate.

The rubber composition of the present invention uses silica as a reinforcing agent. Examples of the silica include dry silica (anhydrous silicic acid), wet silica (hydrous silicic acid), colloidal silica, precipitated silica, calcium silicate, and aluminum silicate. One or more of these can be used. The BET specific surface area of silica is preferably 50 to 250 m ² / g. The BET specific surface area is measured according to ASTM D1993-03. As commercial products of silica, trade names such as Degussa's trade name Ultrasil VN3-G, Tosoh Silica's trade names VN3, AQ, ER, RS-150, Rhodia's trade names, Zeosil 1115MP, 1165MP, etc. can be used. .

The content of silica is 5 to 150 parts by mass with respect to 100 parts by mass of the rubber component. The content is preferably 15 parts by mass or more, more preferably 25 parts by mass or more, in order to improve fuel efficiency. Moreover, in order to improve fracture strength and workability, Preferably it is 100 mass parts or less, More preferably, it is 50 mass parts or less.

The rubber composition of the present invention contains a polyalkylene glycol having a branched structure. The polyalkylene glycol interacts with the hydroxyl groups on the surface of the silica particles, thereby suppressing reaggregation of silica and promoting dispersion of silica in the rubber matrix.

［式中、ｙ^１、ｙ^２及びｙ^３は、同一又は異なって、２〜４０の整数を表す。］ The polyalkylene glycol is not particularly limited as long as it has a branched structure, and examples thereof include polyethylene glycol, polypropylene glycol, and polybutylene glycol. Further, it may be a copolymer of ethylene glycol, propylene glycol, or butylene glycol. The branched structure can be introduced by copolymerizing a tri- or higher functional monomer. The polyalkylene glycol is preferably a three-branched structure because of its excellent processability, and is a compound represented by the following formula (I) (polyethylene glycol having a three-branched structure) because of its high polarity. More preferably.

[Wherein, y ¹ , y ² and y ³ are the same or different and each represents an integer of 2 to 40. ]

y ^{1, y 2} and ^{y 3} is an integer from 2 to 40. If it is less than 2, bleeding tends to occur, and if it exceeds 40, the rubber composition tends to be too hard. From the viewpoint of low fuel consumption and processability, the lower limit of y ¹ , y ² and y ³ is preferably 15, more preferably 20, and the upper limit is preferably 35, more preferably 30.

It is preferable that y ¹ , y ² and y ³ are the same integer from the viewpoint that silica is well dispersed and fuel economy, fracture strength and processability can be improved in a well-balanced manner.

Content of polyalkylene glycol which has a branched structure is 0.1-10 mass parts with respect to 100 mass parts of rubber components. If the amount is less than 0.1 parts by mass, the dispersion of silica tends not to be sufficiently promoted. If the amount exceeds 10 parts by mass, blooming is likely to occur, or low fuel consumption is caused by the contribution of the viscosity of polyalkylene glycol. There is a tendency to deteriorate. From the viewpoint of low fuel consumption, fracture strength, and processability, the lower limit of the content is preferably 1 part by mass, and the upper limit is preferably 8 parts by mass.

The rubber composition of the present invention may contain additives other than the above-mentioned chemicals. Known additives can be used, such as sulfur vulcanizing agents; thiazole vulcanization accelerators, thiuram vulcanization accelerators, sulfenamide vulcanization accelerators, guanidine vulcanization accelerators. Vulcanization accelerators such as stearic acid and zinc oxide; organic peroxides such as dicumyl peroxide and ditertiary butyl peroxide; reinforcing agents such as carbon black; calcium carbonate, talc and alumina Examples thereof include fillers such as clay, aluminum hydroxide and mica; silane coupling agents; extension oils; processing aids; anti-aging agents;

Examples of the sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur. The content of sulfur is preferably 0.1 to 15 parts by mass, more preferably 0.3 to 10 parts by mass, and still more preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the rubber component. It is.

Examples of the vulcanization accelerator include 2-mercaptobenzothiazole, dibenzothiazyl disulfide, and thiazole vulcanization accelerators such as N-cyclohexyl-2-benzothiazylsulfenamide; tetramethylthiuram monosulfide, tetramethylthiuram. Thiuram vulcanization accelerators such as disulfides; N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazole sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, N -Sulfenamide vulcanization accelerators such as oxyethylene-2-benzothiazole sulfenamide and N, N'-diisopropyl-2-benzothiazole sulfenamide; diphenylguanidine, diortolylguanidine, orthotolylbiguanidine What guanidine-based vulcanization accelerator and the like. The content of the vulcanization accelerator is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass with respect to 100 parts by mass of the rubber component.

Examples of the carbon black include furnace black, acetylene black, thermal black, channel black, and graphite. Carbon blacks include channel carbon blacks such as EPC, MPC and CC; furnace carbon blacks such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF and ECF; FT and MT Thermal carbon black such as acetylene carbon black is exemplified. One or more of these can be used.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 5 to 200 m ² / g, and the dibutyl phthalate (DBP) absorption amount of carbon black is preferably 5 to 300 ml / 100 g. . The nitrogen adsorption specific surface area is measured according to ASTM D4820-93, and the DBP absorption is measured according to ASTM D2414-93. As a commercial item, Mitsubishi Chemical Corporation trade name Dia Black N339, Tokai Carbon Co., Ltd. trade name Seast 6, Seast 7HM, Seast KH, Degussa Corporation trade name CK3, Special Black 4A, etc. can be used.

The content of carbon black is preferably 1 to 50 parts by mass with respect to 100 parts by mass of the rubber component. Further, the content is more preferably 10 parts by mass or more, and still more preferably 15 parts by mass or more, in order to increase the fracture resistance. Moreover, in order to improve low-fuel-consumption property, More preferably, it is 45 mass parts or less, More preferably, it is 40 mass parts or less.

The content of the reinforcing agent is preferably 10 to 150 parts by mass with respect to 100 parts by mass of the rubber component. Further, the content is more preferably 20 parts by mass or more, and still more preferably 30 parts by mass or more, in order to increase the fracture resistance. Moreover, in order to improve low fuel consumption, More preferably, it is 120 mass parts or less, More preferably, it is 100 mass parts or less.

The mass ratio of the silica content and the carbon black content used as the reinforcing agent (silica content: carbon black content) is preferably 0.1: 1 to 10: 1. The mass ratio is more preferably 0.5: 1 to 2: 1 in order to enhance fuel efficiency and enhance reinforcement.

Examples of the silane coupling agent include vinyltrichlorosilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and γ-glycidoxypropyltrimethoxysilane. , Γ-methacryloxypropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-phenyl-γ- Aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, bis (3- (triethoxysilyl) propyl) disulfide, bis (3- (triethoxy Cyril) Pills) tetrasulfide, .gamma.-trimethoxysilylpropyl dimethylthiocarbamoyl tetrasulfide, and the like .gamma.-trimethoxysilylpropyl benzothiazyl tetrasulfide. One or more of these are used. As commercial products, trade names Si69, Si75, etc., manufactured by Degussa Corporation can be used.

The content of the silane coupling agent is preferably 1 to 20 parts by mass, more preferably 2 to 15 parts by mass, and further preferably 5 to 10 parts by mass with respect to 100 parts by mass of silica.

Examples of the extending oil include aromatic mineral oil (viscosity specific gravity constant (VGC value) 0.900 to 1.049), naphthenic mineral oil (VGC value 0.850 to 0.899), paraffinic mineral oil (VGC value 0.790 to 0.849), and the like. The polycyclic aromatic content of the extender oil is preferably less than 3% by mass, more preferably less than 1% by mass. The polycyclic aromatic content is measured according to the British Petroleum Institute 346/92 method. Moreover, the aromatic compound content (CA) of the extending oil is preferably 20% by mass or more. One or more of these extending oils are used.

As a method for producing the rubber composition of the present invention, a known method, for example, a method of kneading each component with a known mixer such as a roll or Banbury can be used.

As kneading conditions, when additives other than the vulcanizing agent and the vulcanization accelerator are blended, the kneading temperature is usually 50 to 200 ° C., preferably 80 to 190 ° C., and the kneading time is usually 30 seconds. -30 minutes, preferably 1-30 minutes. When blending a vulcanizing agent and a vulcanization accelerator, the kneading temperature is usually 100 ° C. or lower, preferably room temperature to 80 ° C. A composition containing a vulcanizing agent and a vulcanization accelerator is usually used after vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 120 to 200 ° C, preferably 140 to 180 ° C.

The rubber composition of the present invention has a high balance between low fuel consumption, fracture resistance and processability.

The rubber composition of the present invention is used for a tire tread.

The pneumatic tire of the present invention is produced by a usual method using the rubber composition. That is, a rubber composition blended with various additives as necessary is extruded according to the shape of the base tread of the tire at an unvulcanized stage, and molded by a normal method on a tire molding machine, Bonding together with other tire members forms an unvulcanized tire. This unvulcanized tire can be heated and pressurized in a vulcanizer to produce the pneumatic tire of the present invention.

The pneumatic tire of the present invention can be suitably used as a tire for passenger cars.

The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

<Polymer Production Example 1>
The inside of the stainless steel polymerization reactor with an internal volume of 5 liters equipped with a stirrer was washed, dried and replaced with dry nitrogen. Next, 2.55 kg of industrial hexane (density 680 kg / m ³ ), 137 g of 1,3-butadiene, 0.81 g of tert-butoxydiphenylvinylsilane, 1.52 ml of tetrahydrofuran, and 1.18 ml of ethylene glycol diethyl ether were added to the polymerization reactor. It was thrown into. Next, 2.88 mmol of n-butyllithium was charged into the polymerization reactor as an n-hexane solution to start the polymerization reaction.

Copolymerization of 1,3-butadiene and tert-butoxydiphenylvinylsilane was carried out for 2 hours while the stirring speed was 130 rpm, the temperature in the polymerization reactor was 65 ° C., and the monomer was continuously fed into the polymerization reactor. It was. The supply amount of 1,3-butadiene was 205 g. In addition, in the total amount of monomers charged / supplied to the polymerization reactor, the charged amount of tert-butoxydiphenylvinylsilane was 0.18% by mass.

10 ml of a hexane solution containing 0.2 ml of methanol was added to the polymer solution, and the polymer solution was further stirred for 5 minutes.

2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumilyzer GM) was added to the polymer solution. 8 g, 0.9 g of pentaerythrityltetrakis (3-laurylthiopropionate) (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumilizer TP-D) was added, and then the polymer solution was stirred at room temperature for 24 hours. Evaporated and further dried under reduced pressure at 55 ° C. for 12 hours to obtain a polymer 1.

<Polymer Production Example 2>
A stainless polymerization reactor with an internal volume of 20 liters equipped with a stirrer was washed, dried and replaced with dry nitrogen. Next, 10.2 kg of industrial hexane (density 680 kg / m ³ ), 608 g of 1,3-butadiene, 6.1 ml of tetrahydrofuran, and 4.0 ml of ethylene glycol diethyl ether were charged into the polymerization reactor. Next, 12.40 mmol of n-butyllithium was charged into the polymerization reactor as an n-hexane solution to initiate the polymerization reaction.

The stirring rate was 130 rpm, the temperature in the polymerization reactor was 65 ° C., and the copolymerization reaction of 1,3-butadiene was carried out for 3 hours while continuously supplying the monomer into the polymerization reactor. The supply amount of 1,3-butadiene was 912 g. 20 ml of hexane solution containing 0.8 ml of methanol was added to the polymer solution, and the polymer solution was further stirred for 5 minutes.

7. 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumilyzer GM) in the polymer solution 0 g, pentaerythrityltetrakis (3-laurylthiopropionate) (Sumitomo Chemical Co., Ltd., trade name: Sumilyzer TP-D) 4.0 g was added, and then the polymer solution was added at room temperature for 24 hours. Evaporated and further dried under reduced pressure at 55 ° C. for 12 hours to obtain a polymer 2.

The obtained polymers 1 and 2 were analyzed by the following method. The results are shown in Table 1.

(Mooney viscosity (ML _{1 + 4} ))
According to JIS K6300 (1994), the Mooney viscosity of the polymer was measured at 100 ° C.

(Vinyl bond amount (unit: mol%))
The amount of vinyl bonds (vinyl content) of the polymer was determined from the absorption intensity around 910 cm ^−1, which is the vinyl group absorption peak, by infrared spectroscopy.

(Molecular weight distribution (Mw / Mn))
The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured by gel permeation chromatography (GPC) method under the following conditions (i) to (viii), and the molecular weight distribution (Mw / Mn) was determined.
(I) Apparatus: HLC-8220 manufactured by Tosoh Corporation
(Ii) Separation column: HM-H manufactured by Tosoh Corporation (two in series)
(Iii) Measurement temperature: 40 ° C
(Iv) Carrier: Tetrahydrofuran (v) Flow rate: 0.6 mL / min (vi) Injection volume: 5 μL
(Vii) Detector: differential refraction (viii) Molecular weight standard: Standard polystyrene

Below, various chemical | medical agents used by the Example and the comparative example are demonstrated.
Natural rubber (NR): RSS # 3
Butadiene rubber (BR): Ubepol BR150B manufactured by Ube Industries, Ltd.
Polymers 1 and 2: Synthesis by the above method KA9202: KA9202 manufactured by LANXESS (polyethylene glycol having a three-branch structure, y ¹ = 25, y ² = 25, y ³ = 25)
Carbon black: Diablack N220 manufactured by Mitsubishi Chemical Corporation (N ₂ SA: 111 m ² / g, DBP absorption: 115 ml / 100 g)
Silica: Ultrasil VN3 manufactured by Degussa (N ₂ SA: 175 m ² / g)
Silane coupling agent: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide) manufactured by Degussa
Anti-aging agent: Antigen 3C manufactured by Sumitomo Chemical Co., Ltd.
Wax: Sunnock N manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Oil: X-140 manufactured by Japan Energy Co., Ltd.
Stearic acid: Beads manufactured by NOF Corporation Zinc stearate zinc oxide: Zinc flower No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Sulfur powder vulcanization accelerator manufactured by Tsurumi Chemical Co., Ltd. CZ: Sumitomo Chemical ( Soxinol CZ manufactured by

(Examples and Comparative Examples)
According to the blending content shown in Table 2, materials other than sulfur and vulcanization accelerator were kneaded for 5 minutes at 150 ° C. using a 1.7 L Banbury mixer manufactured by Kobe Steel Co., Ltd. Obtained. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and kneaded for 5 minutes under the condition of 80 ° C. using an open roll to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was press vulcanized with a 0.5 mm thick mold at 170 ° C. for 20 minutes to obtain a vulcanized rubber composition.

The following evaluation was performed about the obtained unvulcanized rubber composition and vulcanized rubber composition.

<Evaluation items and test methods>
<Mooney viscosity>
According to JIS K6300: 1994, the Mooney viscosity of the unvulcanized rubber composition was measured at 100 ° C. and expressed as an index when Comparative Example 1 was taken as 100. The larger the index, the smaller the Mooney viscosity and the better the workability.

<Tan δ>
A strip-shaped test piece having a width of 1 mm or 2 mm and a length of 40 mm was punched out from the sheet-like vulcanized molded body and subjected to the test. The measurement is performed by measuring the loss tangent (tan δ (70 ° C.)) of the test piece at a temperature of 70 ° C. under the conditions of a strain of 1% and a frequency of 10 Hz using a viscoelasticity measuring device (manufactured by Ueshima Seisakusho Co., Ltd.) The reciprocal of tan δ in Example 1 is taken as 100, and the result is shown as an index. The larger the index, the better the fuel efficiency.

<Destructive strength>
The vulcanized rubber sheet was subjected to a tensile test using a No. 3 dumbbell according to JIS K6251 and measured for breaking strength (TB) and elongation at break (EB) (%). The numerical value of TB × EB / 2 was used as the fracture resistance, and the index was expressed as an index with the fracture resistance of Comparative Example 1 as 100. The larger the index, the better the fracture strength.

As shown in Table 2, an example in which a specific conjugated diene polymer (Polymer 1) and a polyalkylene glycol having a branched structure were blended was less fuel efficient than the rubber composition of Comparative Example, The fracture strength and workability improved synergistically, and these performances were obtained in a high dimension and in a well-balanced manner.

Claims (7)

Containing a rubber component, silica, and a polyalkylene glycol having a branched structure;
In 100% by mass of the rubber component, the content of a conjugated diene polymer having a structural unit based on a conjugated diene and a structural unit based on a compound represented by the following formula (1) is 5% by mass or more.
A rubber composition for a base tread, wherein the content of the silica is 5 to 150 parts by mass and the content of the polyalkylene glycol is 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component.

(Wherein m represents 1 or 2, n represents 1 or 2, m + n is 2 or 3, R ¹ represents a hydrocarbyl group having a polymerizable carbon-carbon double bond, and R ² represents hydrocarbyl. represents a group, when R ² are a plurality, a plurality of R ² may be the same or different, R ³ represents an aryl group which may have an oxygen-containing substituent, if there are a plurality of R ^3, Multiple R ³ groups may be the same or different, and R ⁴ represents an alkyl group or a substituted amino group.) M + n of the compound represented by the formula (1) is 3, R ¹ is a group represented by the following formula (2), R ² is a tertiary alkyl group, and R ³ has an alkyl group. The rubber composition for a base tread according to claim 1, wherein the rubber composition is an optionally substituted phenyl group.

(In the formula, p is 0 or 1, R ⁵ represents a hydrogen atom or a hydrocarbyl group, and T represents a hydrocarbylene group.) The rubber composition for base treads according to claim 1 or 2, wherein R ^{1 of the} compound represented by the formula (1) is a vinyl group. 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 is 1.0 to 1.5. A rubber composition for a base tread according to claim 1. 5. The base tread according to claim 1, wherein the vinyl bond content of the conjugated diene polymer is 20 mol% or more and 70 mol% or less, with the content of the constituent unit based on diene being 100 mol%. Rubber composition. The rubber composition for base tread according to any one of claims 1 to 5, wherein the polyalkylene glycol is a compound represented by the following formula (I).

[Wherein, y ¹ , y ² and y ³ are the same or different and each represents an integer of 2 to 40. ] The pneumatic tire produced using the rubber composition in any one of Claims 1-6.