JP6988290B2 - Rubber composition for tires and pneumatic tires - Google Patents

Description

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

Conventionally, it has been required to reduce the rolling resistance of a tire from the viewpoint of low fuel consumption when the vehicle is running. Further, from the viewpoint of safety, improvement of wet grip performance (braking performance on wet road surface) is required. On the other hand, a method is known in which silica is blended with a rubber component constituting a tread portion of a tire to achieve both low rolling resistance and wet grip performance.
Further, in recent years, a technique using silica having a large specific surface area has been known in response to the demand for higher performance of tires.
However, since silica has a low affinity with the rubber component and has high agglomeration between silicas, the silica does not disperse even if silica is simply mixed with the rubber component, which has the effect of reducing rolling resistance and wet grip performance. There was a problem that the effect of improving was not sufficiently obtained.

Therefore, a method of adding a sulfur-containing silane coupling agent in order to enhance the dispersion of silica in the rubber composition is known.
Further, a method of adding hydrolyzable silane which functions as a coupling agent between a filler and a diene elastomer is known to a rubber composition.
For example, Patent Document 1 describes a diene elastomer composition containing a diene elastomer, a hydrolyzable silane, and a curing agent for the diene elastomer, wherein the hydrolyzable silane has a specific structure and is hydrolyzable. Described are diene elastomer compositions that are silanes.

Japanese Patent Publication No. 2015-502357

However, if a large amount of silica having a large specific surface area is blended in a rubber composition containing a diene-based rubber and a sulfur-containing silane coupling agent, the effect of blending silica is expected, but the silica tends to aggregate to that extent, which is effective. (For example, the Mooney viscosity of the unvulcanized rubber composition increases) and other problems are likely to occur.
Further, the wet grip performance of the rubber obtained from such a rubber composition may not satisfy the level required in recent years.

On the other hand, when a pneumatic tire is used as a winter tire that may be used on icy and snowy roads, it is required to have excellent icy and snowy road performance, that is, excellent braking performance on icy and snowy roads, in addition to wet grip performance. There is.

The present inventors prepared and evaluated a rubber composition containing a hydrolyzable silane having a piperazine ring with reference to Patent Document 1, and found that such a composition had a high Mooney viscosity and was a scorch. It was clarified that (burning of unvulcanized rubber) could not be prevented, the workability was low, and the performance on ice and snow roads was low (Comparative Example 5 in each table).
Therefore, the present invention has excellent workability (for example, Mooney viscosity and / or Mooney scorch is in an appropriate range), and can balance wet grip performance and ice / snow road performance at a high level when made into a tire. It is an object of the present invention to provide a rubber composition for tires and a pneumatic tire using the rubber composition for tires.

As a result of diligent research to solve the above problems, the present inventors have found that a heterocyclic compound having a specific structure is effective in terms of processability, and further, is effective in terms of wet grip performance, low rolling resistance and ice / snow road performance. I found that there is.
Further, the present inventors can solve the above-mentioned problems by blending the heterocyclic compound in a specific content when the average glass transition temperature of the diene rubber and the content of silica are in a predetermined range. And came to the present invention.
That is, the present invention can solve the above problem by the following configuration.

式（Ｉ）中、Ｘ₇が、窒素原子、酸素原子及び硫黄原子からなる群から選ばれる少なくとも１種を表し、
Ｘ₃、Ｘ₄、Ｘ₅及びＸ₆は、それぞれ独立に、水素原子又は炭化水素基を表す。
Ｘ₇が窒素原子である場合、ｎ３は１であり、Ｘ₁及びＸ₂のうちの一方又は両方が、それぞれ独立に、式（Ｉ−１）：−（Ａ₁）_n1-1−Ｒ_1-1を表し、
Ｘ₁及びＸ₂のうちの一方のみが式（Ｉ−１）を表す場合、残りの基が、水素原子、スルホン系保護基、カルバメート系保護基及び式（Ｉ−３）：−（Ｒ₂−Ｏ）_n2−Ｈからなる群から選ばれる少なくとも１種を表し、
式（Ｉ−３）中、Ｒ₂は、それぞれ独立に、２価の炭化水素基を表し、
ｎ２は、１〜１０を表す。
Ｘ₇が酸素原子及び硫黄原子からなる群から選ばれる少なくとも１種である場合、ｎ３は０を表し、Ｘ₁が、式（Ｉ−１）：−（Ａ₁）_n1-1−Ｒ_1-1を表す。
式（Ｉ−１）中、Ａ₁は、カルボニル基及び式（Ｉ−２）：−Ｒ_1-2（ＯＨ）−Ｏ−からなる群から選ばれる少なくとも１種を表し、
ｎ１−１は、０又は１を表し、
Ｒ_1-1は、炭素数３〜３０の炭化水素基を表し、
式（Ｉ−２）中、Ｒ_1-2は、３価の炭化水素基を表す。
３． 上記ヘテロ環化合物が、上記式（Ｉ）で表される化合物であり、Ｘ₇が窒素原子であり、ｎ３が１であり、
Ｘ₁及びＸ₂の両方が、それぞれ独立に、上記式（Ｉ−１）を表す、上記２に記載のタイヤ用ゴム組成物。
４． 上記ヘテロ環化合物が、上記式（Ｉ）で表される化合物であり、Ｘ₇が窒素原子であり、ｎ３が１であり、
Ｘ₁及びＸ₂のうちの一方のみが上記式（Ｉ−１）を表し、
残りの基が、水素原子、スルホン系保護基、カルバメート系保護基及び式（Ｉ−３）：−（Ｒ₂−Ｏ）_n2−Ｈからなる群から選ばれる少なくとも１種を表す、上記２に記載のタイヤ用ゴム組成物。式（Ｉ−３）中、Ｒ₂は、それぞれ独立に、２価の炭化水素基を表し、ｎ２は、１〜１０を表す。
５． 上記シリカのＣＴＡＢ吸着比表面積が、１５０〜３００ｍ²／ｇである、上記１〜４のいずれかに記載のタイヤ用ゴム組成物。
６． 上記ジエン系ゴムが、変性ジエン系ゴムを含み、
上記変性ジエン系ゴムの含有量が、上記ジエン系ゴム全量中の５０質量％を超える、上記１〜５のいずれかに記載のタイヤ用ゴム組成物。
７． 更に、硫黄含有シランカップリング剤を含有する、上記１〜６のいずれかに記載のタイヤ用ゴム組成物。
８． 上記１〜７のいずれかに記載のタイヤ用ゴム組成物をキャップトレッドに配置した空気入りタイヤ。
９． 冬用である、上記８に記載の空気入りタイヤ。 1. 1. With a diene rubber containing at least an aromatic vinyl-conjugated diene copolymer,
With silica
A heterocyclic compound having a hydrocarbon group having 3 to 30 carbon atoms and at least one heterocycle selected from the group consisting of a piperazine ring, a morpholine ring and a thiomorpholine ring (however, the above heterocyclic compound has a silicon atom). Does not contain) and
The average glass transition temperature of the diene rubber is -100 ° C or higher and lower than -50 ° C.
The silica content is 80 to 200 parts by mass with respect to 100 parts by mass of the diene rubber.
A rubber composition for a tire, wherein the content of the heterocyclic compound is 0.5 to 20% by mass with respect to the silica.
2. 2. The rubber composition for a tire according to 1 above, wherein the heterocyclic compound is a compound represented by the following formula (I).

In formula (I), X ₇ represents at least one selected from the group consisting of nitrogen atom, oxygen atom and sulfur atom.
X ₃ , X ₄ , X ₅ and X ₆ each independently represent a hydrogen atom or a hydrocarbon group.
When X ₇ is a nitrogen atom, n 3 is 1, and _{one or both of X 1} and X ₂ are independent of each other in the formula (I-1):-(A ₁ ) _n1-1 −R _{1. Represents -1}
If only one of X ₁ and X ₂ represents formula (I-1), the remaining groups are hydrogen atom, sulfone protecting group, carbamate protecting group and formula (I-3):-(R _2). −O) _Represents at least one species selected from the group consisting of n2 −H.
In formula (I-3), R ₂ independently represents a divalent hydrocarbon group.
n2 represents 1 to 10.
When X ₇ is at least one selected from the group consisting of oxygen atom and sulfur atom, n3 represents 0 and X ₁ is the formula (I-1):-(A ₁ ) _n1-1 -R _1-. Represents _1.
In formula (I-1), A ₁ represents at least one selected from the group consisting of a carbonyl group and formula (I-2): -R _{1-2 (OH) -O-.}
n1-1 represents 0 or 1 and represents
R _1-1 represents a hydrocarbon group having 3 to 30 carbon atoms.
In formula (I-2), R _1-2 represents a trivalent hydrocarbon group.
3. 3. The heterocyclic compound is a compound represented by the above formula (I), _{where X 7} is a nitrogen atom and n3 is 1.
The rubber composition for a tire according to 2 above, wherein both _{X 1} and X _{2 independently represent the formula (I-1).}
4. The heterocyclic compound is a compound represented by the above formula (I), _{where X 7} is a nitrogen atom and n3 is 1.
Only one of X ₁ and X ₂ represents the above equation (I-1).
The remaining groups are a hydrogen atom, a sulfonic-based protective group, carbamate protecting groups and formula _{(I-3) :-( R 2} -O) represents at least one selected from the group consisting of _n2 -H, to the above 2 The described rubber composition for tires. In formula (I-3), R ₂ independently represents a divalent hydrocarbon group, and n 2 represents 1 to 10.
5. The rubber composition for a tire according to any one of 1 to 4 above, wherein the silica has a CTAB adsorption specific surface area of 150 to 300 m ^{2 / g.}
6. The diene-based rubber contains a modified diene-based rubber.
The rubber composition for a tire according to any one of 1 to 5 above, wherein the content of the modified diene rubber exceeds 50% by mass in the total amount of the diene rubber.
7. The rubber composition for a tire according to any one of 1 to 6 above, which further contains a sulfur-containing silane coupling agent.
8. A pneumatic tire in which the rubber composition for a tire according to any one of 1 to 7 above is arranged on a cap tread.
9. The pneumatic tire according to 8 above, which is for winter.

The rubber composition for a tire of the present invention has excellent workability, and can balance wet grip performance and ice / snow road performance at a high level when made into a tire.
Further, according to the present invention, it is possible to provide a pneumatic tire.

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

The present invention will be described in detail below.
In addition, in this specification, (meth) acrylate represents acrylate or methacrylate, (meth) acryloyl represents acryloyl or methacryloyl, and (meth) acrylic represents acrylic or methacrylic.
Further, 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.
Unless otherwise specified in the present specification, each component is not particularly limited in its production method. For example, conventionally known ones can be mentioned.
In the present specification, unless otherwise specified, each component may be used alone or in combination of two or more kinds of substances corresponding to the component. When a component contains two or more substances, the content of the component means the total content of the two or more substances.
In the present specification, it is said that the effect of the present invention is more excellent when at least one of the workability, the wet grip performance and the ice / snow road performance is more excellent.

[Rubber composition for tires]
The rubber composition for a tire of the present invention (the composition of the present invention) is
With a diene rubber containing at least an aromatic vinyl-conjugated diene copolymer,
With silica
A heterocyclic compound having a hydrocarbon group having 3 to 30 carbon atoms and at least one heterocycle selected from the group consisting of a piperazine ring, a morpholine ring and a thiomorpholine ring (however, the above heterocyclic compound has a silicon atom). Does not contain) and
The average glass transition temperature of the diene rubber is -100 ° C or higher and lower than -50 ° C.
The silica content is 80 to 200 parts by mass with respect to 100 parts by mass of the diene rubber.
A rubber composition for a tire in which the content of the heterocyclic compound is 0.5 to 20% by mass with respect to the silica.

Since the composition of the present invention has such a structure, it is considered that a desired effect can be obtained. The reason is not clear, but it is presumed to be as follows.
The heterocyclic compound contained in the composition of the present invention has a hydrocarbon group having 3 to 30 carbon atoms and at least one heterocycle selected from the group consisting of a piperazine ring, a morpholine ring and a thiomorpholine ring.
It is considered that the hydrocarbon group has hydrophobicity and easily interacts with the diene rubber, and the heterocycle has hydrophilicity and easily interacts with silica.
As described above, the heterocyclic compound having the hydrocarbon group as the hydrophobic part and the heterocycle as the hydrophilic part functions like a surfactant in the composition containing the diene rubber and silica. The present inventors presume that the dispersibility of silica in the diene-based rubber is increased, thereby lowering the Mooney viscosity in the unhydrocarbonated rubber.
Further, the heterocyclic compound interacts with the diene rubber at the hydrocarbon group but does not form a chemical bond, and the heterocyclic compound interacts with silica in the heterocycle but contains a silicon atom. Since it does not exist, it is considered that the heterocyclic compound does not form a chemical bond with silica. Therefore, the present inventors presume that the heterocyclic compound can suppress scorch (burning) because the vulcanization promoting effect is not too high.
As described above, it is considered that the presence of the heterocyclic compound lowers the Mooney viscosity, suppresses scorch, and the composition of the present invention is excellent in processability.
Further, as described above, the heterocyclic compound enhances the dispersibility of silica in the diene rubber, so that the composition of the present invention does not impair the excellent wet grip performance and the ice-snow road performance when used as a tire. It is presumed that the wet grip performance and the performance on the ice and snow road can be balanced at a high level.
Hereinafter, each component contained in the composition of the present invention will be described in detail.

<< Diene rubber >>
The composition of the present invention contains at least a diene-based rubber containing an aromatic vinyl-conjugated diene-based copolymer. Further, in the present invention, the average glass transition temperature of the diene rubber is −100 ° C. or higher and lower than −50 ° C.

The diene-based rubber contains at least an aromatic vinyl-conjugated diene-based copolymer.
The aromatic vinyl-conjugated diene-based copolymer contained in the diene-based rubber is not particularly limited. For example, styrene butadiene rubber (SBR) and styrene isoprene rubber can be mentioned.
Further, the aromatic vinyl-conjugated diene-based copolymer can have a modifying group. Examples of the modifying group include a hydroxy group, a carboxy group, an aldehyde group, an amino group, an imino group, a thiol group, an epoxy group, a polysiloxane group such as a polyorganosiloxane group, a hydrocarbyloxysilane group such as an alkoxysilyl group, and a silanol group. , These combinations can be mentioned.
The above-mentioned modifying group and the aromatic vinyl-conjugated diene copolymer can be bonded either directly or via an organic group. The organic group is not particularly limited.
The aromatic vinyl-conjugated diene copolymer is an aromatic vinyl-conjugated diene copolymer having a modifying group, in which all or part of the aromatic vinyl-conjugated diene-based copolymer contained in the diene-based rubber is used. Hereinafter, it can be referred to as a modified aromatic vinyl-conjugated diene copolymer).

In addition to the aromatic vinyl-conjugated diene copolymer (including the modified aromatic vinyl-conjugated diene copolymer), the diene-based rubber further comprises a diene-based rubber other than the aromatic vinyl-conjugated diene copolymer. Can include.
Diene-based rubbers other than the above aromatic vinyl-conjugated diene copolymer are not particularly limited. For example, natural rubber (NR); isoprene rubber (IR), butadiene rubber, acrylonitrile-butadiene copolymer rubber (NBR), butyl rubber (IIR), halogenated butyl rubber (Br-IIR, Cl-IIR), chloroprene rubber (CR). And so on.
Of these, butadiene rubber is preferable.

(Denatured diene rubber)
The diene-based rubber can include a modified diene-based rubber. The modified diene rubber can have a modifying group. Examples of the modifying group include a hydroxy group, a carboxy group, an aldehyde group, an amino group, an imino group, a thiol group, an epoxy group, a polysiloxane group such as a polyorganosiloxane group, a hydrocarbyloxysilane group such as an alkoxysilyl group, and a silanol group. , These combinations can be mentioned.
The modified diene-based rubber may be either the above-mentioned modified aromatic vinyl-conjugated diene copolymer or a modified product of a diene-based rubber other than the aromatic vinyl-conjugated diene copolymer.
Examples of the main chain of the modified diene-based rubber include the same as the above-mentioned diene-based rubber other than the above-mentioned aromatic vinyl-conjugated diene copolymer and the above-mentioned aromatic vinyl-conjugated diene copolymer.
The modifying group and the main chain (aromatic vinyl-conjugated diene copolymer or the diene-based rubber) can be bonded directly or via an organic group. The organic group is not particularly limited.
As the modified diene-based rubber, a modified aromatic vinyl-conjugated diene copolymer rubber is preferable, and a modified SBR is more preferable.

The diene-based rubber preferably contains a modified aromatic vinyl-conjugated diene copolymer and an unmodified diene-based rubber or an unmodified aromatic vinyl-conjugated diene copolymer, which is modified with modified SBR. It is more preferable to include BR which is not used.

When the diene-based rubber contains a modified diene-based rubber, the content of the modified diene-based rubber is 50% by mass in the total amount of the diene-based rubber from the viewpoint of being superior in the effects of the present invention (particularly workability and wet grip performance). The amount is preferably more than, more preferably 60 to 100% by mass.
When the diene-based rubber contains a modified diene-based rubber, the content of the modified diene-based rubber can be 90% by mass or less of the total amount of the diene-based rubber.

In the present invention, the weight average molecular weight of each diene rubber can be 30,000 or more. The weight average molecular weight of the diene rubber can be 2 million or less.
The weight average molecular weight of the diene-based rubber is a standard polystyrene-equivalent value based on a value measured by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent.

<< Average glass transition temperature >>
In the present invention, the average glass transition temperature (average Tg) of the diene rubber is −100 ° C. or higher and lower than −50 ° C.
The average glass transition temperature is preferably −80 ° C. or higher and lower than −50 ° C., more preferably −70 ° C. or higher and lower than −50 ° C. from the viewpoint of being superior to the effects of the present invention (particularly, wet grip performance and ice / snow road performance). ..
The average Tg of the diene-based rubber is obtained by multiplying the glass transition temperature (Tg) of each diene-based rubber by the mass% of each diene-based rubber with respect to the entire diene-based rubber and adding them together.
When one kind of diene-based rubber is used as the diene-based rubber, the average glass transition temperature of the diene-based rubber is the glass transition temperature of the above-mentioned one kind of diene-based rubber.
The glass transition temperature of each diene rubber was measured at a heating rate of 20 ° C./min using a differential scanning calorimeter (DSC) and calculated by the midpoint method.

<< Silica >>
The silica contained in the composition of the present invention is not particularly limited. For example, conventionally known silica blended in a rubber composition for applications such as tires can be used.
Examples of the silica include wet silica, dry silica, fumed silica, and diatomaceous earth.

(CTAB adsorption specific surface area of silica)
CTAB adsorption specific surface area of the silica, the effect of the present invention (in particular, wet grip performance and ice and snow road performance) from the viewpoint of obtaining superior, preferably ^{150~300m 2 / g, 180~300m 2 /} g is more preferable.
In the present invention, the CTAB adsorption specific surface area of the silica can be less than ^{210 m 2 / g.}
Here, the CTAB adsorption specific surface area is a substitute property of the surface area that silica can be used for adsorption with the silane coupling agent, and the amount of CTAB (cetyltrimethylammonium bromide) adsorbed on the silica surface is JIS K6217-3: 2001 "No. It is a value measured according to "Part 3: How to obtain the specific surface area-CTAB adsorption method".

<< Silica content >>
In the present invention, the content of the silica is 80 to 200 parts by mass with respect to 100 parts by mass of the diene rubber.
The silica content is 80 to 150 parts by mass with respect to 100 parts by mass of the diene rubber from the viewpoint of being excellent in the effect of the present invention (particularly wet grip performance) and excellent in low rolling resistance. It is preferably 80 to 130 parts by mass, more preferably 80 to 130 parts by mass.
In the present invention, the content of the silica can be less than 150 parts by mass with respect to 100 parts by mass of the diene rubber.

<< Heterocyclic compound >>
The heterocyclic compound contained in the composition of the present invention is a compound having a hydrocarbon group having 3 to 30 carbon atoms and at least one heterocycle selected from the group consisting of a piperazine ring, a morpholine ring and a thiomorpholine ring. Is. In the present invention, the heterocyclic compound does not have a silicon atom.
The hydrocarbon group having 3 to 30 carbon atoms can function as a hydrophobic portion.
The heterocyclic compound may not have an enamine structure (NC = C).

<Hydrocarbon groups with 3 to 30 carbon atoms>
Examples of the hydrocarbon group having 3 to 30 carbon atoms include an aliphatic hydrocarbon group (including linear, branched and cyclic), an aromatic hydrocarbon group, and a combination thereof.
Of these, an aliphatic hydrocarbon group is preferable, and a saturated aliphatic hydrocarbon group is more preferable, from the viewpoint of being more excellent in processability.

The carbon number of the hydrocarbon group having 3 to 30 carbon atoms is preferably 8 to 22 and more preferably 8 to 18 from the viewpoint of being more excellent in processability.

One of the preferred embodiments is that the hydrocarbon group having 3 to 30 carbon atoms is composed only of a carbon atom and a hydrogen atom.
A hydrocarbon group having 3 to 30 carbon atoms is preferably monovalent.
One molecule of the heterocyclic compound may have one or a plurality of hydrocarbon groups having 3 to 30 carbon atoms, and it is preferable to have one or two hydrocarbon groups.

<Heterocycle>
In the present invention, the heterocyclic compound has at least one heterocycle selected from the group consisting of a piperazine ring, a morpholine ring and a thiomorpholine ring.
The heterocyclic compound 1 molecule may have one or more of the heterocycles, and it is preferable to have one.
The heterocycle is preferably a piperazine ring or a morpholine ring, and more preferably a piperazine ring, from the viewpoint of being more excellent in processability.

(Piperazine ring)
The piperazine ring means the skeleton of piperazine. A heterocyclic compound having a piperazine ring as a heterocycle may be hereinafter referred to as a “piperazine compound”. In the present invention, the piperazine ring does not contain a triethylenediamine skeleton (diazabicyclooctane skeleton).
(Morpholine ring)
The morpholine ring means the skeleton of morpholine. A heterocyclic compound having a morpholine ring as a heterocycle may be hereinafter referred to as a “morpholine compound”.
(Thiomorpholine ring)
The thiomorpholine ring means the skeleton of thiomorpholine. A heterocyclic compound having a thiomorpholine ring as a heterocycle may be hereinafter referred to as a “thiomorpholine compound”.

(Bond of hydrocarbon group with 3 to 30 carbon atoms and heterocycle)
A hydrocarbon group having 3 to 30 carbon atoms can be bonded to the nitrogen atom or carbon atom of the heterocycle of the heterocyclic compound directly or via an organic group.
One of the preferred embodiments is that the hydrocarbon group having 3 to 30 carbon atoms is bonded to the nitrogen atom of the heterocycle of the heterocyclic compound directly or via an organic group.
In the heterocyclic compound, when the heterocycle is a morpholine ring, a hydrocarbon group having 3 to 30 carbon atoms can be bonded to a nitrogen atom or a carbon atom in the morpholine ring directly or via an organic group. .. The same applies when the heterocycle is a thiomorpholine ring.

The organic group is not particularly limited. For example, a hydrocarbon group having an oxygen atom can be mentioned. Examples of the hydrocarbon group include the same groups as described above.
The oxygen atom may form, for example, a carbonyl group or a hydroxy group.
When the organic group is a hydrocarbon group having an oxygen atom at the terminal, the oxygen atom may be bonded to a hydrocarbon group having 3 to 30 carbon atoms to form an ether bond. The hydrocarbon group having an oxygen atom may further have a hydroxy group.

The piperazine compound may further have a hydrocarbon group having 3 to 30 carbon atoms and a substituent other than the piperazine ring. Examples of the substituent, for example, sulfone protecting group, carbamate protecting groups and formula (I-3) at least one can be cited selected from :-( R ₂ -O) group consisting of _n2 -H.
When the piperazine compound further has the above-mentioned substituent, the above-mentioned substituent can be bonded to the nitrogen atom of the piperazine ring of the piperazine compound.

Further, in the piperazine compound, one hydrocarbon group having 3 to 30 carbon atoms is bonded to one of the two nitrogen atoms of the piperazine ring, and a hydrogen atom or the above substitution is made to the remaining nitrogen atom of the piperazine ring. Atoms can be attached.

(Sulfone protecting group)
Examples of the sulfone-based protecting group include a methanesulfonyl group, a tosyl group and a nosyl group.

(Carbamate protecting group)
Examples of the carbamate-based protecting group include a tert-butoxycarbonyl group, an allyloxycarbonyl group, a benzyloxycarbonyl group and a 9-fluorenylmethyloxycarbonyl group.

(Equation (I-3))
In formula (I-3):-(R _2- O) _n2- H, R ₂ independently represents a divalent hydrocarbon group.
In the formula (I-3), the number of carbon atoms of the divalent hydrocarbon group is preferably 2 to 3.
The divalent hydrocarbon group is preferably an aliphatic hydrocarbon group. The aliphatic hydrocarbon group may be linear, branched, cyclic, or a combination thereof.
n2 represents 1 to 10, preferably 1 to 5.

式（Ｉ）中、Ｘ₇が、窒素原子、酸素原子及び硫黄原子からなる群から選ばれる少なくとも１種を表し、
Ｘ₃、Ｘ₄、Ｘ₅及びＸ₆は、それぞれ独立に、水素原子又は炭化水素基を表す。
Ｘ₇が窒素原子である場合、ｎ３は１であり、Ｘ₁及びＸ₂のうちの一方又は両方が、それぞれ独立に、式（Ｉ−１）：−（Ａ₁）_n1-1−Ｒ_1-1を表し、
Ｘ₁及びＸ₂のうちの一方のみが式（Ｉ−１）を表す場合、残りの基が、水素原子、スルホン系保護基、カルバメート系保護基及び式（Ｉ−３）：−（Ｒ₂−Ｏ）_n2−Ｈからなる群から選ばれる少なくとも１種を表し、
式（Ｉ−３）中、Ｒ₂は、それぞれ独立に、２価の炭化水素基を表し、
ｎ２は、１〜１０を表す。
Ｘ₇が酸素原子及び硫黄原子からなる群から選ばれる少なくとも１種である場合、ｎ３は０を表し、Ｘ₁が、式（Ｉ−１）：−（Ａ₁）_n1-1−Ｒ_1-1を表す。
式（Ｉ−１）中、Ａ₁は、カルボニル基及び式（Ｉ−２）：−Ｒ_1-2（ＯＨ）−Ｏ−からなる群から選ばれる少なくとも１種を表し、
ｎ１−１は、０又は１を表し、
Ｒ_1-1は、炭素数３〜３０の炭化水素基を表し、
式（Ｉ−２）中、Ｒ_1-2は、３価の炭化水素基を表す。 The heterocyclic compound is preferably a compound represented by the following formula (I) from the viewpoint of excellent processability and excellent dispersibility of silica.

In formula (I), X ₇ represents at least one selected from the group consisting of nitrogen atom, oxygen atom and sulfur atom.
X ₃ , X ₄ , X ₅ and X ₆ each independently represent a hydrogen atom or a hydrocarbon group.
When X ₇ is a nitrogen atom, n 3 is 1, and _{one or both of X 1} and X ₂ are independent of each other in the formula (I-1):-(A ₁ ) _n1-1 −R _{1. Represents -1}
If only one of X ₁ and X ₂ represents formula (I-1), the remaining groups are hydrogen atom, sulfone protecting group, carbamate protecting group and formula (I-3):-(R _2). −O) _Represents at least one species selected from the group consisting of n2 −H.
In formula (I-3), R ₂ independently represents a divalent hydrocarbon group.
n2 represents 1 to 10.
When X ₇ is at least one selected from the group consisting of oxygen atom and sulfur atom, n3 represents 0 and X ₁ is the formula (I-1):-(A ₁ ) _n1-1 -R _1-. Represents _1.
In formula (I-1), A ₁ represents at least one selected from the group consisting of a carbonyl group and formula (I-2): -R _{1-2 (OH) -O-.}
n1-1 represents 0 or 1 and represents
R _1-1 represents a hydrocarbon group having 3 to 30 carbon atoms.
In formula (I-2), R _1-2 represents a trivalent hydrocarbon group.

In formula (I), _{one or both of X 1} and X ₂ independently represent formula (I-1):-(A ₁ ) _n1-1- R _1-1.

(Equation (I-1))
In formula (I-1):-(A ₁ ) _n1-1- R _1-1 , A ₁ is a group consisting of a carbonyl group and formula (I-2): -R _1-2 (OH) -O-. Represents at least one selected from.
n1-1 represents 0 or 1.
R _1-1 represents a hydrocarbon group having 3 to 30 carbon atoms. The hydrocarbon group having 3 to 30 carbon atoms is the same as above.

(Equation (I-2))
In formula (I-2): -R _1-2 (OH) -O-, R _1-2 represents a trivalent hydrocarbon group.
The number of carbon atoms of the trivalent hydrocarbon group is preferably 3 to 30.
The trivalent hydrocarbon group is preferably an aliphatic hydrocarbon group. The aliphatic hydrocarbon group may be linear, branched, cyclic, or a combination thereof.

In formula (I-2), the hydroxy group may be bonded to any carbon atom constituting _{R 1-2.}

In the formula (I-1):-(A ₁ ) _n1-1- R _1-1 , n1-1 is 1, and A ₁ is the formula (I-2): -R _1-2 (OH) -O. When −, R _1-2 of the formula (I-2) is bonded to the nitrogen atom of the heterocycle, and the oxygen atom (—O−) of the formula (I-2) is bonded to _{R 1-1.} R _1-2 (trivalent hydrocarbon group) has 3 to 30 carbon atoms, and between the oxygen atom (-O-) and the nitrogen atom of the heterocycle, R _1-2 (trivalent hydrocarbon) One of the preferred embodiments is that three or more carbon atoms among the carbon atoms of the group) are arranged side by side.

(X ₃ , X ₄ , X ₅ and X ₆ )
In formula (I), X ₃ , X ₄ , X ₅ and X ₆ each independently represent a hydrogen atom or a hydrocarbon group.
The above hydrocarbon group is not particularly limited. The hydrocarbon group may be a hydrocarbon group having 3 to 30 carbon atoms, or may be another hydrocarbon group.
X ₃ , X ₄ , X ₅ and X ₆ are mentioned as one of preferred embodiments in which they are hydrogen atoms.

In formula (I), where X ₇ is a nitrogen atom, n 3 is 1, and _{only one of X 1} and X ₂ represents the above formula (I-1), the remaining groups are hydrogen atoms. It can represent at least one selected from the group consisting of a sulfone-based protecting group, a carbamate-based protecting group and the formula (I-3):-(R _2- O) _n2-H.
That is, when X ₁ represents the above formula (I-1), X ₂ is a hydrogen atom, a sulfone-based protecting group, a carbamate-based protecting group and the formula (I-3):-(R _2- O) _n2- H. It can represent at least one species selected from the group consisting of.
When X ₂ represents the above formula (I-1), X ₁ is a hydrogen atom, a sulfone-based protecting group, a carbamate-based protecting group, and the formula (I-3):-(R _2- O) _n2- H. It can represent at least one species selected from the group consisting of. The sulfone-based protecting group, the carbamate-based protecting group and the formula (I-3) are the same as described above, respectively.

(When the heterocyclic compound is a compound represented by the formula (I), X ₇ is a nitrogen atom, and n 3 is 1.)
The heterocyclic compound represented by the formula (I), where X ₇ is a nitrogen atom and n3 is 1, is represented by the following formula (II).

In formula (II), _{one or both of X 1} and X ₂ independently represent formula (I-1):-(A ₁ ) _n1-1- R _1-1.

(Equation (I-1))
In formula (I-1):-(A ₁ ) _n1-1- R _1-1 , A ₁ is a group consisting of a carbonyl group and formula (I-2): -R _1-2 (OH) -O-. Represents at least one selected from.
n1-1 represents 0 or 1.
R _1-1 represents a hydrocarbon group having 3 to 30 carbon atoms. The hydrocarbon group having 3 to 30 carbon atoms is the same as above.

(Equation (I-2))
In formula (I-2): -R _1-2 (OH) -O-, R _1-2 represents a trivalent hydrocarbon group.
The number of carbon atoms of the trivalent hydrocarbon group is preferably 3 to 30.
The trivalent hydrocarbon group is preferably an aliphatic hydrocarbon group. The aliphatic hydrocarbon group may be linear, branched, cyclic, or a combination thereof.

In formula (I-2), the hydroxy group may be bonded to any carbon atom constituting _{R 1-2.}

In the formula (I-1):-(A ₁ ) _n1-1- R _1-1 , n1-1 is 1, and A ₁ is the formula (I-2): -R _1-2 (OH) -O. When −, R _1-2 of the formula (I-2) is bonded to the nitrogen atom of the piperazine ring, and the oxygen atom (-O −) of the formula (I-2) is bonded to _{R 1-1.} R _1-2 (trivalent hydrocarbon group) has 3 to 30 carbon atoms, and between the oxygen atom (-O-) and the nitrogen atom of the piperazine ring, R _1-2 (trivalent hydrocarbon) One of the preferred embodiments is that three or more carbon atoms among the carbon atoms of the group) are arranged side by side.

(X ₃ , X ₄ , X ₅ and X ₆ )
In formula (II), X ₃ , X ₄ , X ₅ and X ₆ each independently represent a hydrogen atom or a hydrocarbon group.
The above hydrocarbon group is not particularly limited. The hydrocarbon group may be a hydrocarbon group having 3 to 30 carbon atoms, or may be another hydrocarbon group.
X ₃ , X ₄ , X ₅ and X ₆ are mentioned as one of preferred embodiments in which they are hydrogen atoms.

In formula (II), when _{only one of X 1} and X ₂ represents the above formula (I-1), the remaining groups are a hydrogen atom, a sulfone-based protecting group, a carbamate-based protecting group and a formula (I-). 3): At least one selected from the group consisting of _{− (R 2 −} O) _{n2 −H can be represented.}
That is, when X ₁ represents the above formula (I-1), X ₂ is a hydrogen atom, a sulfone-based protecting group, a carbamate-based protecting group and the formula (I-3):-(R _2- O) _n2- H. It can represent at least one species selected from the group consisting of.
When X ₂ represents the above formula (I-1), X ₁ is a hydrogen atom, a sulfone-based protecting group, a carbamate-based protecting group, and the formula (I-3):-(R _2- O) _n2- H. It can represent at least one species selected from the group consisting of. The sulfone-based protecting group, the carbamate-based protecting group and the formula (I-3) are the same as described above, respectively.

Specific embodiments of the piperazine compound include, for example, the following aspects 1 or 2.
(Aspect 1 of piperazine compound)
Aspect 1 of the piperazine compound is represented by the formula (II).
Both X ₁ and X ₂ are compounds that independently represent the above formula (I-1).
In the above aspect 1, hydrogen atoms are preferable for _{X 3} , X ₄ , X ₅ and X _6.

Specific examples of the above aspect 1 include piperazine compounds 3, 5 and 8 represented by the following formulas.

Piperazine compound 3

Piperazine compound 5

なお、ピペラジン化合物８は、両方のＲが−Ｃ₁₂Ｈ₂₅である化合物、両方のＲが−Ｃ₁₃Ｈ₂₇である化合物及び一方のＲが−Ｃ₁₂Ｈ₂₅であり残りのＲが−Ｃ₁₃Ｈ₂₇である化合物からなる群から選ばれる少なくとも２種の混合物であってもよい。 Piperazine compound 8 (R independently represents _{-C 12} H ₂₅ or -C ₁₃ H ₂₇₎

The piperazine compound 8 includes a compound in which both Rs are -C ₁₂ H ₂₅ , a compound in which both Rs are -C ₁₃ H ₂₇ , and one R is -C ₁₂ H ₂₅ and the remaining R is -C. may be a mixture of at least two selected from the group consisting of ₁₃ is H ₂₇ compound.

(Aspect 2 of piperazine compound)
Aspect 2 of the piperazine compound is represented by the formula (II).
Only one of X ₁ and X ₂ represents equation (I-1).
The remaining groups, being a compound represents at least one selected from a hydrogen atom, a sulfonic-based protective group, carbamate protecting group and the formula _{(I-3) :-( R 2} -O) group consisting of _n2 -H ..
In the above aspect 2, hydrogen atoms are preferable for _{X 3} , X ₄ , X ₅ and X _6.

Specific examples of the above aspect 2 include piperazine compounds 1, 2, 4, 6 and 7 represented by the following formulas.

Piperazine compound 1

Piperazine compound 2 (in the following structural formula, n is 1 to 10, preferably 1 to 5)

Piperazine compound 4

Piperazine compound 6

Piperazine compound 7 (R represents -C ₁₂ H ₂₅ or -C ₁₃ H _27. Piperazine compound 7 is a piperazine compound having R of -C ₁₂ H ₂₅ and a piperazine compound having R of -C ₁₃ H ₂₇ . It may be a mixture with.)

式（ＩＩＩ）において、Ｘ₁は上記式（Ｉ）の式（Ｉ−１）：−（Ａ₁）_n1-1−Ｒ_1-1と同じであり、Ｘ₃、Ｘ₄、Ｘ₅及びＸ₆は上記式（Ｉ）のＸ₃、Ｘ₄、Ｘ₅及びＸ₆とそれぞれ同じであり、Ｘ₈は酸素原子及び硫黄原子からなる群から選ばれる少なくとも１種である。 (When the heterocyclic compound is a compound represented by the formula (I), X ₇ is an oxygen atom or a sulfur atom, and n3 is 0).
The heterocyclic compound represented by the formula (I), where X ₇ is an oxygen atom or a sulfur atom and n3 is 0, is represented by the following formula (III).

In the formula (III), X ₁ is the same as the formula (I-1):-(A ₁ ) _n1-1- R _1-1 of the above formula (I), and X ₃ , X ₄ , X ₅ and X. ₆ is the same respectively X _3, X _4, X ₅ and X ₆ in the formula (I), X ₈ is at least one selected from the group consisting of oxygen and sulfur atoms.

Examples of the compound represented by the formula (III) include morpholine compounds 1 to 4 represented by the following formula.

(Morpholine compound 1)

(Morpholine compound 2)

(Morpholine compound 3)

モルホリン化合物４においてＲは−Ｃ₁₂Ｈ₂₅、又は、−Ｃ₁₃Ｈ₂₇を表す。モルホリン化合物４は、Ｒが−Ｃ₁₂Ｈ₂₅であるモルホリン化合物とＲが−Ｃ₁₃Ｈ₂₇であるモルホリン化合物との混合物であってもよい。 (Morpholine compound 4)

In morpholine compound 4, R represents -C ₁₂ H ₂₅ or -C ₁₃ H ₂₇ . The morpholine compound 4 may be a mixture of a morpholine compound having an R of −C ₁₂ H ₂₅ and a morpholine compound having an R of −C ₁₃ H ₂₇ .

The heterocyclic compound is not particularly limited in its production method. For example, conventionally known ones can be mentioned.
Specifically, for example, at least one selected from the group consisting of piperazine, morpholine and thiomorpholine which may have a substituent, a halogen atom (chlorine, bromine, iodine, etc.) and an acid halogen group (acidated compound group). , Acid bromide group, acid iodide group, etc.) and a hydrocarbon compound having at least one selected from the group consisting of a glucidyloxy group and having 3 to 30 carbon atoms are reacted in a solvent, if necessary. Can be obtained by The substituents are the same as above. The hydrocarbon group having 3 to 30 carbon atoms contained in the above hydrocarbon compound is the same as the above.
Further, as a method for producing the piperazine compound when the piperazine compound ₂ has the above formula (I-3):-(R2-O) _{n2-H, for example, hydroxy like the piperazine compound 1.} Examples thereof include a method of reacting a piperazine compound having a group with an alkylene oxide in the presence of a metal alkoxide.

<< Content of heterocyclic compound >>
In the present invention, the content of the heterocyclic compound is 0.5 to 20% by mass with respect to the content of the silica.
The content of the heterocyclic compound is preferably 1 to 15% by mass, more preferably 1 to 10% by mass, based on the content of the silica, from the viewpoint that the effect of the present invention is excellent and the dispersibility of silica is excellent. preferable.

(Silane coupling agent)
The composition of the present invention can further contain a silane coupling agent.
The silane coupling agent is not particularly limited. Silane coupling agents can have hydrolytic groups.
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. 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. 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 silane coupling agent can have, for example, a group having a sulfur atom in addition to the above-mentioned hydrolyzable group. The sulfur atom can form, for example, a sulfide group (including a monosulfide group and a polysulfide group), a mercapto group, and a carbonylthio group.
Examples of the silane coupling agent include a sulfur-containing silane coupling agent and a silane coupling agent having a polysiloxane skeleton.
The polysiloxane skeleton means a polymer having a plurality of- (Si-O) -repeating units. The polysiloxane skeleton can be any of linear, branched, and three-dimensional structures, or a combination thereof.
One of the preferred embodiments is that the silane coupling agent contains at least a sulfur-containing silane coupling agent. The sulfur-containing silane coupling agent may further have a polysiloxane skeleton, or may have no polysiloxane skeleton.

Examples of the silane coupling agent include bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, and bis (2-trimethoxy). Cyrilethyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (3-triethoxysilylpropyl) disulfide, bis (3-trimethoxysilylpropyl) Polysulfide silane like disulfide;
Silane coupling agent represented by the following formula (a);
Silane coupling agent represented by the following formula (b);
3- [ethoxybis (3,6,9,12,15-pentaoxaoctacosan-1-yloxy) silyl] -1-propanethiol (Si363 manufactured by Ebonic Degusa) is represented by the following formula (2). Examples thereof include silane coupling agents, γ-mercaptopropylmethyldimethoxysilane, and mercapto group-containing silane coupling agents such as γ-mercaptopropyltrimethoxysilane.

Among them, the silane coupling agent represented by the following formula (a) and the silane cup represented by the following formula (b) are excellent in terms of the effect of the present invention (particularly the wet grip performance) and the silica dispersibility. At least one selected from the group consisting of a ring agent and a mercapto group-containing silane coupling agent is preferable.

- formula (a) a silane coupling agent formula represented by (a) _{is, (C L H 2L + 1} O) 3 -Si- (CH 2) m -S-C (= O) - (C n H _{2n + 1} ).
In the formula (a), L is 1 to 3, m is 1 to 3, and n is 1 to 15.
C _L H 2 _{L + 1} may be linear or branched.
(C _n H _{2n + 1} ) may be linear, branched or cyclic, or may be a combination thereof.

Examples of the silane coupling agent represented by the formula (a) include 3-octanoylthio-1-propyltriethoxysilane.

-Silane coupling agent represented by the formula (b) The formula (b) is (A) _a (B) _b (C) _c (D) _d (R ¹ ) _e SiO _{(4-2a-bcde) / 2.} Is.
The formula (b) is an average composition formula.

In formula (b), A represents a divalent organic group containing a sulfide group. B represents a monovalent hydrocarbon group having 5 to 10 carbon atoms. C represents a hydrolyzable group. D represents an organic group containing a mercapto group. R ¹ represents a monovalent hydrocarbon group having 1 to 4 carbon atoms. a to e are 0 ≦ a <1, 0 <b <1, 0 <c <3, 0 ≦ d <1, 0 ≦ e <2, and satisfy the relational expression of 0 <2a + b + c + d + e <4.
However, this does not apply when a and d are 0 at the same time.

The silane coupling agent represented by the above formula (b) is preferably given as one of preferred embodiments having a polysiloxane skeleton.

(A)
In the above formula (b), A represents a divalent organic group containing a sulfide group (hereinafter, also referred to as a sulfide group-containing organic group). The organic group can be, for example, a hydrocarbon group which may have a heteroatom such as an oxygen atom, a nitrogen atom and a sulfur atom.
Above all, it is preferable that the group is represented by the following formula (4).
^* − (CH ₂ ) _n −S _x − (CH ₂ ) _n − ^* (4)
In the above formula (4), n represents an integer of 1 to 10, and more preferably an integer of 2 to 4.
In the above formula (4), x represents an integer of 1 to 6, and more preferably an integer of 2 to 4.
In the above equation (4), * indicates a bonding position.
Specific examples of the group represented by the above formula (4) include, for example, ^* −CH ₂ −S ₂ −CH ₂ − ^* , ^* −C ₂ H ₄ −S ₂ −C ₂ H ₄ − ^* , ^* −. C ₃ H ₆ −S ₂ −C ₃ H ₆ − ^* , ^* −C ₄ H ₈ −S ₂ −C ₄ H ₈ − ^* , ^* −CH ₂ −S ₄ −CH ₂ − ^* , ^* −C ₂ H ₄ −S ₄ −C ₂ H ₄ − ^* , ^* −C ₃ H ₆ −S ₄ −C ₃ H ₆ − ^* , ^* −C ₄ H ₈ −S ₄ −C ₄ H ₈ − ^*, etc.

(B)
In the above formula (b), B represents a monovalent hydrocarbon group having 5 to 10 carbon atoms, and specific examples thereof include a hexyl group, an octyl group, and a decyl group. B can protect the mercapto group.
B is preferably a monovalent hydrocarbon group having 8 to 10 carbon atoms from the viewpoint of being excellent in the effect (particularly processability) of the present invention and excellent in silica dispersibility.

(C)
In the above formula (b), C represents a hydrolyzable group, and specific examples thereof include an alkoxy group, a phenoxy group, a carboxyl group, and an alkenyloxy group. Above all, it is preferable that the group is represented by the following formula (5).
^* -OR ² (5)

In the above formula (5), R ² is an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 10 carbon atoms (arylalkyl group), or an alkenyl group having 2 to 10 carbon atoms. Represents. Among them, R ² is preferably an alkyl group having 1 to 5 carbon atoms.

Specific examples of the alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group, a decyl group and an octadecyl group.
Specific examples of the aryl group having 6 to 10 carbon atoms include a phenyl group and a tolyl group.
Specific examples of the aralkyl group having 7 to 10 carbon atoms include a benzyl group and a phenylethyl group.
Specific examples of the alkenyl group having 2 to 10 carbon atoms include a vinyl group, a propenyl group, a pentenyl group and the like.
In the above formula (5), * indicates a bonding position.

(D)
In the above formula (b), D represents an organic group containing a mercapto group. Above all, it is preferable that the group is represented by the following formula (6).
^* -(CH ₂ ) _m- SH (6)

In the above equation (6), m represents an integer of 1 to 10. Among them, m is preferably an integer of 1 to 5.
In the above formula (6), * indicates a bonding position.

Specific examples of the group represented by the above formula (6) include ^* -CH ₂ SH, ^* -C ₂ H ₄ SH, ^* -C ₃ H ₆ SH, ^* -C ₄ H ₈ SH, ^* -C ₅ Examples include H ₁₀ ^{SH, *} -C ₆ H ₁₂ SH, ^* -C ₇ H ₁₄ SH, ^* -C ₈ H ₁₆ SH, ^* -C ₉ H ₁₈ SH, and ^* -C ₁₀ H ₂₀ SH.

(R ¹ )
In the above formula (b), R ¹ represents a monovalent hydrocarbon group having 1 to 4 carbon atoms. For example, a methyl group, an ethyl group, a propyl group, and a butyl group can be mentioned.

(A to e)
In the above formula (b), a to e are 0 ≦ a <1, 0 <b <1, 0 <c <3, 0 ≦ d <1, and 0 ≦ e <2, 0 <2a + b + c + d + e <. Satisfy the relational expression of 4.

The silane coupling agent represented by the formula (b) preferably has a larger than 0 (0 <a) from the viewpoint of being more excellent in the effect (particularly processability) of the present invention, and 0 <a ≦ 0. It is more preferably 50.

In the above formula (b), b is preferably 0.10 ≦ b ≦ 0.89 from the viewpoint of being excellent in the effect (particularly processability) of the present invention and excellent in silica dispersibility.

In the above formula (b), c is preferably 1.2 ≦ c ≦ 2.0 from the viewpoint of being superior in the effect (particularly processability) of the present invention and excellent in silica dispersibility.

In the above formula (b), d is preferably 0.1 ≦ d ≦ 0.8 from the viewpoint of being superior in the effect (particularly processability) of the present invention and excellent in silica dispersibility.

In the above formula (b), 0 <2a + b + c + d + e≤3 is preferable from the viewpoint of being superior in the effect (particularly processability) of the present invention and excellent in silica dispersibility.

From the viewpoint that the silane coupling agent represented by the formula (b) is excellent in the effect (particularly processability) of the present invention and the silica dispersibility is excellent, in the above formula (b), A is the above formula (4). It is preferable that C is a group represented by the above formula (5), D is a group represented by the above formula (6), and A is represented by the above formula (4). C is a group represented by the above formula (5), D is a group represented by the above formula (6), and B is a monovalent hydrocarbon group having 8 to 10 carbon atoms. It is more preferable to have.

The weight average molecular weight of the silane coupling agent represented by the formula (b) is preferably 500 to 2300, preferably 600 to 2300, from the viewpoint of being superior in the effect (particularly processability) of the present invention and excellent in silica dispersibility. It is more preferably 1500. The molecular weight of the silane coupling agent represented by the formula (b) is a weight average molecular weight determined in terms of polystyrene by gel permeation chromatography (GPC) using toluene as a solvent.

The mercapto equivalent by the acetic acid / potassium iodide / potassium iodate addition-sodium thiosulfate solution titration method of the silane coupling agent represented by the formula (b) is 550 to 1900 g / mol from the viewpoint of excellent brewing reactivity. It is preferably 600 to 1800 g / mol, and more preferably 600 to 1800 g / mol.

式（２）中、Ｒ²¹は、炭素数１〜８のアルコキシ基を表す。Ｒ²²は、末端に炭化水素基を有するポリエーテル基を表す。Ｒ²³は、水素原子または炭素数１〜８のアルキル基を表す。Ｒ²⁴は炭素数１〜３０のアルキレン基を表す。ｌは１〜２の整数を表し、ｍは１〜２の整数を表し、ｎは０〜１の整数を表し、ｌ、ｍおよびｎはｌ＋ｍ＋ｎ＝３の関係式を満たす。ｌが２である場合の複数あるＲ²¹はそれぞれ同一であっても異なっていてもよく、ｍが２である場合の複数あるＲ²²はそれぞれ同一であっても異なっていてもよい。 -Silane coupling agent represented by the formula (2) The formula (2) is as follows.

In formula (2), R ²¹ represents an alkoxy group having 1 to 8 carbon atoms. R ²² represents a polyether group having a hydrocarbon group at the terminal. R ²³ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R ²⁴ represents an alkylene group having 1 to 30 carbon atoms. l represents an integer of 1 to 2, m represents an integer of 1 to 2, n represents an integer of 0 to 1, and l, m and n satisfy the relational expression of l + m + n = 3. ^{The plurality of R 21s} when l is 2 may be the same or different from each other, and the plurality of R ^22s when m is 2 may be the same or different from each other.

(R ²¹ )
In the above formula (2), R ²¹ represents an alkoxy group having 1 to 8 carbon atoms, and among them, an alkoxy group having 1 to 3 carbon atoms is preferable because a tire having excellent low rolling resistance can be obtained. Examples of the alkoxy group having 1 to 3 carbon atoms include a methoxy group and an ethoxy group.
(R ²² )
In the above formula (2), R ²² represents a polyether group having a hydrocarbon group at the terminal. A polyether group is a group having two or more ether bonds.
A preferred embodiment of the polyether group having a hydrocarbon group at the terminal is a group represented by the following formula (5).

(R ⁵¹ )
In the above formula (5), R ⁵¹ represents a linear alkyl group, a linear alkenyl group, or a linear alkynyl group, and a linear alkyl group is preferable. As the linear alkyl group, a linear alkyl group having 1 to 20 carbon atoms is preferable, and a linear alkyl group having 8 to 15 carbon atoms is more preferable. Specific examples of the linear alkyl group having 8 to 15 carbon atoms include an octyl group, a nonyl group, a decyl group, an undecylic group, a dodecyl group, a tridecylic group, and the like, and a tridecylic group is preferable.
(R ⁵² )
In the above formula (5), R ⁵² represents a linear alkylene group, a linear alkaneylene group, or a linear alkynylene group, and a linear alkylene group is preferable. As the linear alkylene group, a linear alkylene group having 1 to 2 carbon atoms is preferable, and an ethylene group is more preferable.
(P)
In the above formula (5), p represents an integer of 1 to 10 and is preferably 3 to 7.
In the above formula (5), * indicates a bonding position.

(R ²³ )
In the above formula (2), R ²³ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.
(R ²⁴ )
In the above formula (2), R ²⁴ represents an alkylene group having 1 to 30 carbon atoms, of which an alkylene group having 1 to 12 carbon atoms is preferable, and an alkylene group having 1 to 5 carbon atoms is more preferable. Specific examples of the alkylene group having 1 to 5 carbon atoms include a methylene group, an ethylene group, a trimethylene group, a propylene group and the like.
(L, m, n)
In the above formula (2), l represents an integer of 1 to 2, and is preferably 1. In the above formula (2), m represents an integer of 1 to 2, and is preferably 2. n represents an integer of 0 to 1, and is preferably 0. l, m and n satisfy the relational expression l + m + n = 3.

Specific examples of the silane coupling agent represented by the formula (2) include 3- [ethoxybis (3,6,9,12,15-pentaoxaoctacosan-1-yloxy) silyl] -1-. Propanethiol (Si363 manufactured by Evonik Degussa) can be mentioned.

The method for producing the silane coupling agent is not particularly limited. For example, conventionally known ones can be mentioned.

The content of the silane coupling agent is preferably 2 to 20 parts by mass, preferably 5 to 20 parts by mass with respect to 100 parts by mass of the silica, from the viewpoint that the effect of the present invention (particularly processability) is excellent and the silica dispersibility is excellent. It is more preferably 15 parts by mass.

(Additive)
The composition of the present invention may further contain additives, if necessary, as long as the effects and purposes are not impaired. As additives, for example, rubber other than diene rubber, filler other than silica (for example, carbon black), vulcanization accelerator, resin, zinc oxide, stearic acid, antiaging agent, processing aid, oil, sulfur Examples thereof include those commonly used in rubber compositions for tires such as vulcanizing agents and peroxides. The content of the additive can be appropriately selected.

(Carbon black)
The composition of the present invention can further contain carbon black.
The carbon black is not particularly limited. Examples of carbon black include SAF (Super Abrasion Fuel. The same shall apply hereinafter) -HS (High Structure; the same shall apply hereinafter), SAF, ISAF (Intermediate Super Abrasion Furnace; the same shall apply hereinafter) -HS, ISAF, ISAF-SL. Various grades such as IISAF (Intermediate ISAF) -HS, HAF (High Abrasion Structure; the same shall apply hereinafter) -HS, HAF, HAF-LS, FEF (Fast Extruding Finance) and the like can be used.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably ^{50 to 200 m 2} / g from the viewpoint of being more excellent in processability. The nitrogen adsorption specific surface area of carbon black shall be measured according to JIS K6217-2.

The content of carbon black is preferably 1 to 50 parts by mass, more preferably 1 to 20 parts by mass with respect to 100 parts by mass of the diene rubber.

(Manufacturing method of rubber composition)
The method for producing the composition of the present invention is not particularly limited. Specific examples thereof include a method in which each of the above-mentioned components is mixed under a condition of 100 to 200 ° C. using a known method or device (for example, a Banbury mixer, a kneader, a roll, etc.).
Further, the composition of the present invention can be vulcanized or crosslinked under conventionally known vulcanization or crosslinking conditions, for example.
For example, a tire can be manufactured using the composition of the present invention.
The components of the pneumatic tire that can be produced by the composition of the present invention are not particularly limited. Examples of the member include a tire tread such as a cap tread; a sidewall; and a bead filler.

[Pneumatic tires]
The pneumatic tire of the present invention is a pneumatic tire in which the rubber composition for a tire of the present invention is arranged on a cap tread.
The rubber composition used for the cap tread is not particularly limited as long as it is the rubber composition for tires of the present invention (composition of the present invention).
The cap tread is the part of the pneumatic tire that comes into direct contact with the road surface.
The pneumatic tire of the present invention is not particularly limited except that the composition of the present invention is arranged on the cap tread (the cap tread is formed of the composition of the present invention).
FIG. 1 shows a schematic partial cross-sectional view of a tire showing an example of an embodiment of the pneumatic tire of the present invention. The present invention is not limited to the accompanying drawings.

In FIG. 1, the pneumatic tire has a bead portion 1, a sidewall portion 2, and a tire tread portion 3. 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 folded back from the inside to the outside of the tire around the bead core 5 and the bead filler 6. It has been rolled up. In the tire tread portion 3, the belt layer 7 is arranged on the outside of the carcass layer 4 over one circumference of the tire. In the bead portion 1, the rim cushion 8 is arranged at a portion in contact with the rim.
The tire tread portion 3 has a cap tread on the belt layer 7. An undertread may be arranged between the belt layer 7 and the cap tread.
The composition of the present invention described above is arranged on the cap tread in the tire tread portion 3.

The pneumatic tire of the present invention can be manufactured, for example, according to a conventionally known method.
The pneumatic tire of the present invention is preferably a pneumatic tire used in winter (pneumatic tire for winter) as one of the preferred embodiments.
As the gas to be filled in the pneumatic tire of the present invention, for example, in addition to normal or adjusted oxygen partial pressure, an inert gas such as nitrogen, argon or helium can be used.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.
<< Manufacture of piperazine compounds >>
<Synthesis of piperazine compound 1>
33.3 g of 1-bromooctadecane (manufactured by Tokyo Chemical Industry Co., Ltd.) and 13.0 g of 1- (2-hydroxyethyl) piperazine (hydroxyethyl piperazine manufactured by Nippon Emulsifying Co., Ltd.) were added in tetrahydrofuran and dichloromethane at room temperature. Was reacted for 1 hour. The reaction solution was washed with aqueous potassium carbonate solution, extracted with dichloromethane, and dehydrated with anhydrous magnesium sulfate. Anhydrous magnesium sulfate was filtered off and concentrated to obtain piperazine compound 1 represented by the following formula.
(Piperazine compound 1)

<Synthesis of piperazine compound 2>
The piperazine compound 1 obtained as described above was reacted with 39.6 g, ethylene oxide 13.2 g, and sodium methoxide 0.004 g. The reaction solution was neutralized with phosphoric acid and filtered to obtain piperazine compound 2 represented by the following formula. In the following formula, n is 3.
(Piperazine compound 2)

<Synthesis of piperazine compound 3>
1-bromooctadecane (manufactured by Tokyo Chemical Industry Co., Ltd.) 66.6 g and piperazine hexahydrate (piperazine hexahydrate manufactured by Nippon Emulsifying Co., Ltd.) 19.04 g in tetrahydrofuran and dichloromethane at room temperature for 1 hour. It was reacted. The reaction solution was washed with aqueous potassium carbonate solution, extracted with dichloromethane, and dehydrated with anhydrous magnesium sulfate. Anhydrous magnesium sulfate was filtered off and concentrated to obtain piperazine compound 3 represented by the following formula.
(Piperazine compound 3)

<Synthesis of piperazine compound 4>
30.3 g of stearoyl chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), 13.0 g of 1- (2-hydroxyethyl) piperazine (hydroxyethyl piperazine manufactured by Nippon Emulsifying Co., Ltd.), and 15.2 g of triethylamine in toluene. , 0 ° C. for 1 hour. The reaction solution was washed with aqueous sodium carbonate solution, extracted with toluene, and dehydrated with anhydrous magnesium sulfate. Anhydrous magnesium sulfate was filtered off and concentrated to obtain piperazine compound 4 represented by the following formula.
(Piperazine compound 4)

<Synthesis of piperazine compound 5>
60.6 g of stearoyl chloride (manufactured by Tokyo Chemical Industry Co., Ltd.), 19.04 g of piperazine hexahydrate (piperazine hexahydrate manufactured by Nippon Emulsifier Co., Ltd.) and 30.4 g of triethylamine in toluene at 0 ° C. The reaction was carried out for 1 hour under the conditions of. The reaction solution was washed with aqueous sodium carbonate solution, extracted with toluene, and dehydrated with anhydrous magnesium sulfate. Anhydrous magnesium sulfate was filtered off and concentrated to obtain a piperazine compound 5 represented by the following formula.
(Piperazine compound 5)

<Synthesis of piperazine compound 6>
18.5 g of 2-ethylhexyl glycidyl ether (Epogoose (registered trademark) 2EH manufactured by Yokkaichi Chemical Co., Ltd.) and 13.0 g of 1- (2-hydroxyethyl) piperazine (hydroxyethyl piperazine manufactured by Nippon Embroidery Co., Ltd.) were added. By reacting under the condition of 60 ° C. for 4 hours, the piperazine compound 6 represented by the following formula was obtained.

^{The results of 1} H-NMR of piperazine compound 6 are as follows.
^{1 1} H-NMR (400MHz, CDCl ₃ ): δ 3.85 (m, 1H), 3.60 (t, 2H), 3.30-3.47 (m, 4H), 2.65 (m, 2H) ), 2.54 (t, 4H), 2.46 (t, 2H), 2.38 (dd, 2H), 1.52 (q, 1H), 1.26-1.41 (m, 8H) , 0.89 (t, 5H), 0.85 (s, 1H)
(Piperazine compound 6)

<Synthesis of piperazine compound 7>
C12-13 mixed alcohol glycidyl ether (Epogoose (registered trademark) EN manufactured by Yokkaichi Chemical Co., Ltd. A mixture of C12 alcohol glycidyl ether and C13 alcohol glycidyl ether) 28.4 g and 1- (2-hydroxyethyl) piperazine ( By reacting 13.0 g of hydroxyethyl piperazine manufactured by Nippon Emulsium Co., Ltd. under the condition of 60 ° C. for 4 hours, the piperazine compound 7 (R is -C ₁₂ H _{25 or-) represented by the following formula is expressed.} Representing C ₁₃ H _27. Piperazine compound 7 is a mixture of a piperazine compound having R of -C ₁₂ H ₂₅ and a piperazine compound having R of -C ₁₃ H ₂₇ ).
(Piperazine compound 7)

<Synthesis of piperazine compound 8>
56.8 g of C12-13 mixed alcohol glycidyl ether (Epogoose (registered trademark) EN manufactured by Yokkaichi Chemical Co., Ltd.) and 19.04 g of piperazine hexahydrate (piperazine 6 water salt manufactured by Nippon Emulsifier Co., Ltd.) are mixed with ethanol. The reaction was carried out under the condition of medium and 60 ° C. for 6 hours. The reaction solution was washed with saturated brine, extracted with ethyl acetate, and dehydrated with anhydrous magnesium sulfate. Anhydrous magnesium sulfate was filtered off and concentrated to obtain piperazine compound 8 represented by the following formula (R independently represents -C ₁₂ H ₂₅ or -C ₁₃ H ₂₇ , respectively).
(Piperazine compound 8)

<Synthesis of Morpholine Compound 3>
Reaction of 18.5 g of 2-ethylhexyl glycidyl ether (Epogoose registered trademark 2EH manufactured by Yokkaichi Chemical Co., Ltd.) and 8.7 g of morpholine (manufactured by Tokyo Chemical Industry Co., Ltd.) for 4 hours under the condition of 60 ° C. Morpholine compound 3 (structure below) was obtained.
(Morpholine compound 3)

<< Manufacturing of tire compositions >>
Each component in Table 1 below was blended in the composition (part 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 150 ° C. using a 1.7 liter sealed Banbury mixer, and then 5 After mixing for minutes, 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 a tire.
Regarding the amount of S-SBR-1 in Table 1, the value in the upper row is the amount of rubber (oil spread product) (unit: parts by mass), and the value in the lower row is the net amount of rubber (unit: mass). Department). The same applies to Table 2.

As for Table 2, rubber compositions for tires were produced in the same manner as in Table 1.

<Evaluation>
The following evaluation was performed using the composition produced as described above. The results are shown in Tables 1 and 2, respectively. In each table, for each evaluation item, the evaluation result of each example is expressed as an index with respect to the evaluation result (100) of the standard example.

(Moony viscosity)
_{Mooney viscosity (ML 1 + 4} ) at 100 ° C. was measured according to the method of JIS K6300-1: 2013. The smaller the index, the better the workability.
When the index is less than 100 in the present invention, it is considered that the workability is excellent.
The smaller the index of Mooney viscosity, the better the workability, but it is preferably 90 or more.

(Moony Scoach)
For the composition (unvulcanized) produced as described above, the scorch time was measured under the condition of a test temperature of 125 ° C. using an L-shaped rotor according to JIS K6300-1: 2013.
In the present invention, when the index of Mooney scorch is 90 to 105, it is said that the scorch time is long, the scorch resistance is excellent, and the workability is excellent.

(Wet grip performance)
The obtained rubber composition for tires (unvulcanized) was press-vulcanized in a mold (15 cm × 15 cm × 0.2 cm) at 160 ° C. for 20 minutes to prepare a vulcanized rubber sheet.
The vulcanized rubber sheet produced was subjected to conditions of a stretch deformation strain rate of 10% ± 2%, a frequency of 20 Hz, and a temperature of 0 ° C. using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho Co., Ltd.) in accordance with JIS K6394: 2007. Then, tan δ (0 ° C.) was measured.
The larger the index, the larger the tan δ (0 ° C.), and the better the wet grip performance when used as a tire.
In the present invention, when the index of tan δ (0 ° C.) exceeds 100, it is considered that the wet grip performance when made into a tire is excellent.

(Low rolling resistance)
Instead of measuring under the condition of temperature 0 ° C., tan δ (60 ° C.) was measured according to the same procedure as the above-mentioned wet grip performance except that the measurement was performed under the condition of temperature 60 ° C.
The smaller the index, the smaller the tan δ (60 ° C.), and the better the wet grip performance when used as a tire.
In the present invention, when the index of tan δ (60 ° C.) is less than 100, it is said that the tire has excellent low rolling resistance (fuel efficiency).

(Pain effect)
The rubber composition for tires produced as described above is vulcanized under the condition of 160 ° C. for 20 minutes, and the obtained vulcanized rubber is used in accordance with ASTM D6204 and under the condition of 110 ° C., RPA2000 (α). -Strain shear stress G'(0.56%) with a strain of 0.56% and strain shear stress G'(100%) with a strain of 100% were measured with a strain shear stress measuring machine manufactured by Technology Co., Ltd., and ΔG' = G'(0.56%) -G'(100%) was calculated.
In the present invention, the smaller the index of ΔG', the better the reduction or suppression of the Pain effect (the better the dispersibility of silane).

(Ice and snow road performance)
A tire of size 205 / 55R16 manufactured by using the obtained rubber composition for tires in the tread part was mounted on a vehicle equipped with an ABS with a displacement of 2000 cc, and the air pressure of both the front tire and the rear tire was set to 220 kPa, and ice and snow. The braking stop distance from a speed of 40 km was measured on the road surface.
The larger the index of the braking stop distance, the shorter the braking distance and the better the performance on ice and snow roads.
In the present invention, when the index of the braking stop distance exceeds 100, it is considered that the performance on ice and snow roads is excellent.

The details of each component shown in each of the above tables are as follows.
S-SBR-1: Styrene butadiene rubber having a hydroxy group as a terminal modifying group for silica, produced by solution polymerization. Toughden E580 (oil-extended product (containing 37.5 parts by mass of oil-extended oil with respect to 100 parts by mass of net modified SBR. Net modified SBR in S-SBR-1 is 72.7% by mass), containing styrene. Amount: 37% by mass, vinyl bond amount: 42%, Tg: -27 ° C., weight average molecular weight: 1,260,000, manufactured by Asahi Kasei Co., Ltd.) S-SBR-1 contains a hydroxy group as a terminal modifying group for silica. Since it is a styrene-butadiene rubber having, it can interact with or react with silica at the above-mentioned modifying group.

S-SBR-2: Modified styrene-butadiene rubber having a hydroxy group-containing polyorganosiloxane structure at the end, which is produced by solution polymerization. S-SBR-2 corresponds to a modified diene rubber. Nipol NS612, styrene content: 15% by mass, vinyl bond amount: 30%, Tg: -62 ° C, weight average molecular weight: 780,000, manufactured by Zeon Corporation)

BR: Butadiene rubber, Nipol 1220 (butadiene rubber, manufactured by Zeon Corporation), Tg-105 ° C. The BR corresponds to a diene rubber. The BR has no modifying group.

・ CB: Carbon black, N339 (N ₂ SA = 93m ² / g, manufactured by Tokai Carbon Co., Ltd.)

-Silica: Zeosil 1165MP (CTAB adsorption specific surface area = 159m ² / g, manufactured by Rhodia)

-Silane coupling agent 1: Si69 (bis (3-triethoxysilylpropyl) tetrasulfide, manufactured by Evonik Degussa)

-Silane coupling agent 2: Silane coupling agent having a mercapto group represented by the following formula, Si363, manufactured by Evonik Degussa.

・ Process oil: Extract No. 4 S (manufactured by Showa Shell Sekiyu Co., Ltd.)
・ Anti-aging agent: 6PPD (manufactured by Flexis)
・ Zinc oxide: 3 types of zinc oxide (manufactured by Shodo Chemical Industry Co., Ltd.)
・ Stearic acid: Beaded stearic acid YR (manufactured by NOF CORPORATION)

Piperazine compound 7: Piperazine compound 7 synthesized as described above.

-Morpholine compound 3: Morpholine compound 3 synthesized as described above

-Comparative piperazine compound 1: Hydroxyethyl piperazine manufactured by Nippon Emulsifier, 1- (2-hydroxyethyl) piperazine-Comparative piperazine compound 2: Reagent [3- (1-piperazinyl) propyl] triethoxysilane) Comparative piperazine compound 2 is silicon Has an atom.

・ Vulcanization accelerator 1: Noxeller D (vulcanization accelerator DPG, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.)
-Vulcanization accelerator 2: Noxeller CZ-G (vulcanization accelerator CBS, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.)
・ Sulfur: Fine sulfur powder containing Jinhua Ink oil (manufactured by Tsurumi Chemical Industry Co., Ltd.)

As is clear from the results shown in Table 1, Comparative Example 1 in which the silica content was less than the predetermined range was inferior in wet grip performance to the standard example.
Comparative Example 2 in which the silica content was higher than the predetermined range was inferior in processability because the scorch time was long and the Mooney viscosity was higher than that of the standard example. Further, Comparative Example 2 was inferior in low rolling resistance to the standard example.
Comparative Example 3 containing a predetermined heterocyclic compound in an amount exceeding a predetermined range had a short scorch time and was inferior in processability, and was inferior in ice-snow road performance to the standard example.
Comparative Example 4 which did not contain a predetermined heterocyclic compound and instead contained a piperazine compound having a hydroxyethyl group had a short scorch time and was inferior in processability, and was inferior in ice-snow road performance to the standard example.
Comparative Example 5 which does not contain a predetermined heterocyclic compound and instead contains a piperazine compound having a silicon atom is inferior in processability because the scorch time is short and the Mooney viscosity is higher than that of the standard example, and ice and snow is lower than that of the standard example. Inferior in road performance.

On the other hand, the composition of the present invention was excellent in processability and was able to balance wet grip performance and ice / snow road performance at a high level. Moreover, the composition of the present invention was excellent in low rolling resistance.

As is clear from the results shown in Table 2, Comparative Example 1 in which the silica content was less than the predetermined range was inferior in wet grip performance to the standard example.
Comparative Example 2 in which the silica content was higher than the predetermined range was inferior in processability because the scorch time was long and the Mooney viscosity was higher than that of the standard example. Further, Comparative Example 2 was inferior in low rolling resistance to the standard example.
Comparative Example 3 containing a predetermined heterocyclic compound in an amount exceeding a predetermined range had a short scorch time and was inferior in processability, and was inferior in ice-snow road performance to the standard example.
Comparative Example 4 which did not contain a predetermined heterocyclic compound and instead contained a piperazine compound having a hydroxyethyl group had a short scorch time and was inferior in processability, and was inferior in ice-snow road performance to the standard example.
Comparative Example 5 which does not contain a predetermined heterocyclic compound and instead contains a piperazine compound having a silicon atom is inferior in processability because the scorch time is short and the Mooney viscosity is higher than that of the standard example, and ice and snow is lower than that of the standard example. Inferior in road performance.

On the other hand, the composition of the present invention was excellent in processability and was able to balance wet grip performance and ice / snow road performance at a high level. Moreover, the composition of the present invention was excellent in low rolling resistance.

1 Bead part 2 Side wall part 3 Tire tread part 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Rim cushion

Claims (8)

With a diene rubber containing at least an aromatic vinyl-conjugated diene copolymer,
With silica
It contains a hydrocarbon group having 8 to 30 carbon atoms and a heterocyclic compound having a piperazine ring, a morpholine ring or a thiomorpholine ring (however, the heterocyclic compound does not have a silicon atom).
The average glass transition temperature of the diene rubber is −100 ° C. or higher and lower than −50 ° C.
The silica content is 80 to 200 parts by mass with respect to 100 parts by mass of the diene rubber.
The content of the heterocyclic compound, relative to the silica, Ri 0.5-20% by mass,
A rubber composition for a tire, wherein the heterocyclic compound is a compound represented by the following formula (I).

In formula (I), X ₇ represents a nitrogen atom, an oxygen atom or a sulfur atom.
X ₃ , X ₄ , X ₅ and X ₆ each independently represent a hydrogen atom or a hydrocarbon group.
When X ₇ is a nitrogen atom, n 3 is 1, and _{one or both of X 1} and X ₂ are independent of each other in the formula (I-1):-(A ₁ ) _n1-1 −R _1. It represents a _-1,
If only one of X ₁ and X ₂ represents formula (I-1), the remaining groups are hydrogen atom, sulfone protecting group, carbamate protecting group and formula (I-3):-(R _2). −O) _Represents at least one species selected from the group consisting of n2 −H.
In formula (I-3), R ₂ independently represents a divalent hydrocarbon group.
n2 represents 1 to 10.
When X ₇ is an oxygen atom or a sulfur atom, n3 represents 0 and X ₁ represents the formula (I-1):-(A ₁ ) _n1-1- R _1-1 .
In formula (I-1), A ₁ represents at least one selected from the group consisting of a carbonyl group and formula (I-2): -R _{1-2 (OH) -O-.}
n1-1 represents 0 or 1 and represents
R _1-1 represents a hydrocarbon group having 8 to 30 carbon atoms.
In formula (I-2), R _1-2 represents a trivalent hydrocarbon group. The heterocyclic compound is a compound represented by the formula (I), X ₇ is a nitrogen atom, n3 is 1.
Both X ₁ and X ₂ are, each independently, represent the formula (I-1), tire rubber composition according to claim 1. The heterocyclic compound is a compound represented by the formula (I), X ₇ is a nitrogen atom, n3 is 1.
Only one of X ₁ and X ₂ represents the formula (I-1).
The remaining groups, represents at least one hydrogen atom, sulfone protecting groups, carbamate protecting groups and formula (I-3) is selected from :-( R ₂ -O) group consisting of _n2 -H, claim 1 The rubber composition for a tire according to. In formula (I-3), R ₂ independently represents a divalent hydrocarbon group, and n 2 represents 1 to 10. The rubber composition for a tire according to any one of claims 1 to 3 , wherein the silica has a CTAB adsorption specific surface area of 150 to 300 m ^{2 / g.} The diene-based rubber contains a modified diene-based rubber.
The rubber composition for a tire according to any one of claims 1 to 4 , wherein the content of the modified diene-based rubber exceeds 50% by mass in the total amount of the diene-based rubber. The rubber composition for a tire according to any one of claims 1 to 5 , further comprising a sulfur-containing silane coupling agent. A pneumatic tire in which the rubber composition for a tire according to any one of claims 1 to 6 is arranged on a cap tread. The pneumatic tire according to claim 7 , which is for winter use.

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