JP2022035560A - Rubber composition for tire and tire - Google Patents

Abstract

To provide a rubber composition for a tire which can improve total performance of dry steering stability and wet steering stability, and a tire.SOLUTION: A rubber composition for a tire contains a rubber component containing styrene butadiene rubber and butadiene rubber, silica, carbon black, a resin component, and an ethylene copolymer, in which content of resin component>|content of silica-content of carbon black|, content of carbon black>content of butadiene rubber, and content of butadiene rubber>content of ethylene copolymer.SELECTED DRAWING: None

Description

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

Conventionally, various methods for improving steering stability on dry road surfaces (dry steering stability) and steering stability on wet road surfaces (wet steering stability) have been studied (see, for example, Patent Document 1). However, in recent years, further improvements in these performances have been required.

JP-A-2007-186567

An object of the present invention is to provide a rubber composition for a tire and a tire capable of solving the above problems and improving the overall performance of dry steering stability and wet steering stability.

The present invention contains a rubber component containing styrene-butadiene rubber and butadiene rubber, silica, carbon black, a resin component, and an ethylene copolymer, and the content of the resin component >>> the content of the silica-the above. It relates to a rubber composition for a tire, which is the content of carbon black |, the content of the carbon black> the content of the butadiene rubber, and the content of the butadiene rubber> the content of the ethylene copolymer.

The cis amount of the butadiene rubber is preferably 90% or less.

It is preferable that the rubber composition contains styrene-butadiene rubber and / or butadiene rubber which is soluble in acetone when immersed in acetone for 24 hours.

It is preferable that the content of the silica> the content of the carbon black.

The specific surface area of the silica with cetyltrimethylammonium bromide is preferably 180 m ² / g or more.

The ethylene copolymer is preferably a copolymer having ethylene units, styrene units and butadiene units.

It is preferable that the resin component contains a phenol-based resin.

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

The present invention contains a rubber component containing styrene-butadiene rubber and butadiene rubber, silica, carbon black, a resin component, and an ethylene copolymer, and the content of the resin component >>> Silica content-Carbon black Content |, carbon black content> butadiene rubber content, butadiene rubber content> ethylene copolymer content, which is a rubber composition for tires, so that it is dry steering stability and wet. The overall performance of steering stability is improved.

The rubber composition for a tire of the present invention contains a rubber component containing styrene-butadiene rubber and butadiene rubber, silica, carbon black, a resin component, and an ethylene copolymer, and the content of the resin component >> | Content-content of carbon black |, content of carbon black> content of butadiene rubber, content of butadiene rubber> content of ethylene copolymer.

The reason why the above-mentioned effect can be obtained with the above rubber composition is presumed as follows.
When silica and carbon black are blended, there is a concern that a domain in which only one of them is dispersed is generated due to the difference in dispersibility in each rubber, and the hardness in the system becomes non-uniform. On the other hand, in the above rubber composition, by setting the content of the resin component >> | the content of silica-the content of carbon black |, the rubber phase is made uniform (phase-solubilized) by the resin component, and at the same time. It is possible to reduce the difference in hardness within the system. As a result, it is considered that the dry steering stability and the wet steering stability are improved because the reaction force can be generated in the entire rubber composition.
Further, in the above rubber composition, by increasing the content of carbon black to be higher than the content of butadiene rubber, the amount of carbon black present in the styrene butadiene rubber phase increases, so that the styrene portion and carbon of the styrene butadiene rubber It is thought that the interaction with black is likely to occur, and the dry steering stability performance is further improved.
Further, in the above rubber composition, by reducing the content of the ethylene copolymer having an ethylene portion having a low polarity to the content of the butadiene rubber, it is possible to appropriately precipitate the resin component on the rubber surface. Become. As a result, it is considered that the adhesiveness of the rubber composition is exhibited, and good dry steering stability and wet steering stability can be obtained.
It is considered that the combination of these actions significantly improves the overall performance of dry steering stability and wet steering stability.

The rubber composition contains a rubber component.
Here, the rubber component is a component that contributes to crosslinking, and generally has a weight average molecular weight (Mw) of 10,000 or more.

The weight average molecular weight of the rubber component is preferably 50,000 or more, more preferably 150,000 or more, still more preferably 200,000 or more, and preferably 2 million or less, more preferably 1.5 million or less, still more preferably 1 million. It is as follows. Within the above range, the effect tends to be better obtained.

In the present specification, the weight average molecular weight (Mw) is a gel permeation chromatograph (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL manufactured by Tosoh Corporation. It can be obtained by standard polystyrene conversion based on the measured value by SUPERMULTIPORE HZ-M).

The total amount of styrene in the rubber component is preferably 15% by mass or more, more preferably 25% by mass or more, further preferably 28% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less. , More preferably 35% by mass or less. Within the above range, the effect tends to be better obtained.

Here, the total amount of styrene in the rubber component is the total content (unit: mass%) of the styrene portion contained in the total amount of the rubber component, and is Σ (content of each rubber component × amount of styrene in each rubber component). It can be calculated by / 100). For example, in 100% by mass of the rubber component, SBR having an amount of styrene: 40% by mass is 85% by mass, SBR having an amount of styrene: 25% by mass is 5% by mass, and BR having an amount of styrene: 0% by mass is 10% by mass. , The total amount of styrene in the rubber component is 35.25% by mass (= 85 × 40/100 + 5 × 25/100 + 10 × 0/100).

The total amount of vinyl in the rubber component is preferably 15% by mass or more, more preferably 25% by mass or more, further preferably 30% by mass or more, and preferably 55% by mass or less, more preferably 45% by mass or less. , More preferably 40% by mass or less. Within the above range, the effect tends to be better obtained.

Here, the total amount of vinyl in the rubber component is the total content (unit: mass%) of the vinyl portion contained in the total amount of the rubber component, and is Σ (content of each rubber component × amount of vinyl in each rubber component). It can be calculated by / 100). For example, when the SBR having a vinyl content of 30% by mass is 85% by mass, the SBR having a vinyl content of 20% by mass is 5% by mass, and the BR having a vinyl content of 10% by mass is 10% by mass in 100% by mass of the rubber component. , The total amount of vinyl in the rubber component is 27.5% by mass (= (85 × 30/100 + 5 × 20/100 + 10 × 10/100)).

From the viewpoint of overall performance of dry steering stability and wet steering stability, it is preferable that the total amount of vinyl in the rubber component ≥ the total amount of styrene in the rubber component in the rubber composition.

The total amount of vinyl in the rubber component / the total amount of styrene in the rubber component is preferably 1.1 or more, preferably 2.5 or less, more preferably 1.8 or less, still more preferably 1.5 or less. Is. Within the above range, the effect tends to be better obtained.

The amount of styrene and the amount of vinyl in each rubber component can be measured by a nuclear magnetic resonance (NMR) method.
Further, the total amount of styrene and the total amount of vinyl in the rubber component are calculated according to the above-mentioned calculation formula in the examples of the present specification. For example, a pyrolysis gas chromatograph mass spectrometer (Py-GC / It may be analyzed from the tire by MS) or the like.

The rubber composition contains styrene-butadiene rubber (SBR) as a rubber component.
The SBR is not particularly limited, and for example, emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR) and the like can be used. Examples of commercially available products include products such as Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Co., Ltd., and Zeon Corporation.

The amount of styrene in the SBR is preferably 15% by mass or more, more preferably 25% by mass or more, further preferably 30% by mass or more, particularly preferably 35% by mass or more, and preferably 55% by mass or less, more preferably. Is 45% by mass or less, more preferably 40% by mass or less. Within the above range, the effect tends to be better obtained.

The vinyl content of SBR is preferably 15% by mass or more, more preferably 25% by mass or more, further preferably 30% by mass or more, particularly preferably 35% by mass or more, and preferably 55% by mass or less, more preferably. Is 45% by mass or less, more preferably 40% by mass or less. Within the above range, the effect tends to be better obtained.

The above-mentioned styrene amount and vinyl amount of SBR mean the styrene amount and vinyl amount of the SBR when there is only one type of SBR, and the average styrene amount and average vinyl amount when there are a plurality of types.
The average amount of styrene in SBR can be calculated by {Σ (content of each SBR x amount of styrene in each SBR)} / total content of all SBR, for example, styrene amount: 40% by mass in 100% by mass of rubber component. When the SBR is 85% by mass and the amount of styrene: 25% by mass, the average amount of styrene of SBR is 39.2% by mass (= (85 × 40 + 5 × 25) / (85 + 5)). ..
Similarly, the average vinyl content of SBR can be calculated by {Σ (content of each SBR × vinyl content of each SBR)} / total content of all SBR, for example, vinyl content in 100% by mass of rubber component: 30. When the mass% SBR is 85% by mass and the vinyl content: 20 mass% SBR is 5 mass%, the average vinyl content of SBR is 29.4 mass% (= (85 × 30 + 5 × 20) / (85 + 5)). ).

The content of SBR in 100% by mass of the rubber component is preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, and preferably 95% by mass or less, more preferably 95% by mass or less. It is 90% by mass or less, more preferably 85% by mass or less. Within the above range, the effect tends to be better obtained.

The rubber composition contains butadiene rubber (BR) as a rubber component.
The BR is not particularly limited, and BR having a high cis content, BR having a low cis content, BR containing syndiotactic polybutadiene crystals, and the like can be used. Examples of commercially available products include products such as Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation.

The cis amount (cis content) of BR is preferably 20% by mass or more, more preferably 30% by mass or more, further preferably 35% by mass or more, and preferably 90% by mass or less, more preferably 60% by mass. Hereinafter, it is more preferably 50% by mass or less. Within the above range, the effect tends to be better obtained.
The amount of BR cis can be measured by infrared absorption spectrum analysis.

The above-mentioned cis amount of BR means the cis amount of the BR when there is one kind of BR, and means the average cis amount when there are a plurality of kinds of BR.
The average cis amount of BR can be calculated by {Σ (content of each BR × cis amount of each BR)} / total content of all BR, for example, cis amount: 90% by mass in 100% by mass of rubber component. When BR is 20% by mass and cis amount: 40% by mass, the average cis amount of BR is 73.3% by mass (= (20 × 90 + 10 × 40) / (20 + 10)). ..

The content of BR in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, further preferably 15% by mass or more, and preferably 40% by mass or less, more preferably. It is 30% by mass or less, more preferably 20% by mass or less. Within the above range, the effect tends to be better obtained.

As rubber components that can be used other than SBR and BR, diene rubbers such as isoprene rubber, acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and styrene-isoprene-butadiene copolymer rubber (SIBR). Can be mentioned. These may be used alone or in combination of two or more.

The rubber component may be modified to introduce a functional group that interacts with a filler such as silica.
Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group and a disulfide. Examples thereof include a group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imide group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group and an epoxy group. .. In addition, these functional groups may have a substituent. Among them, an amino group (preferably an amino group in which the hydrogen atom of the amino group is replaced with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), and an alkoxysilyl group (preferably an alkoxy group having 1 to 6 carbon atoms). An alkoxysilyl group having 1 to 6 carbon atoms) is preferable.

Specific examples of the above-mentioned compound having a functional group (modifier) include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, and 3-dimethylaminopropyltriethoxy. Examples thereof include silane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane.

The rubber composition contains silica.
Examples of silica include dry silica (silicic anhydride) and wet silica (hydrous silicic acid), but wet silica is preferable because it has a large amount of silanol groups. As commercially available products, products such as EVONIK, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., and Tokuyama Corporation can be used. These may be used alone or in combination of two or more.

The specific surface area of the cetyltrimethylammonium bromide (CTAB) of silica is preferably 160 m ² / g or more, more preferably 180 m ² / g or more, still more preferably 190 m ² / g or more, and preferably 250 m ² / g or less. , More preferably 230 m ² / g or less, still more preferably 210 m ² / g or less. Within the above range, the effect tends to be better obtained.
The CTAB specific surface area of silica is measured according to ASTM D3765-92.

The silica content is preferably 20 parts by mass or more, more preferably 40 parts by mass or more, still more preferably 50 parts by mass or more, and preferably 80 parts by mass or less, based on 100 parts by mass of the rubber component. It is preferably 70 parts by mass or less, more preferably 60 parts by mass or less. Within the above range, the effect tends to be better obtained.

The rubber composition contains carbon black.
The carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. As commercial products, products such as Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin Nikka Carbon Co., Ltd., Columbia Carbon Co., Ltd. are used. can. These may be used alone or in combination of two or more.

The specific surface area of carbon black cetyltrimethylammonium bromide (CTAB) is preferably 110 m ² / g or more, more preferably 120 m ² / g or more, still more preferably 130 m ² / g or more, and preferably 180 m ² / g or more. Below, it is more preferably 160 m ² / g or less, still more preferably 150 m ² / g or less. Within the above range, the effect tends to be better obtained.
The CTAB specific surface area of carbon black is a value measured in accordance with JIS K6217-3: 2001.

The content of carbon black is preferably 20 parts by mass or more, more preferably 35 parts by mass or more, still more preferably 45 parts by mass or more, and preferably 80 parts by mass or less with respect to 100 parts by mass of the rubber component. It is more preferably 65 parts by mass or less, still more preferably 55 parts by mass or less. Within the above range, the effect tends to be better obtained.

In the above rubber composition, the content of carbon black> the content of BR.

The carbon black content / BR content is preferably 1.5 or more, more preferably 2.0 or more, still more preferably 2.2 or more, and preferably 5.0 or less, more preferably 4 It is 0.0 or less, more preferably 3.0 or less. Within the above range, the effect tends to be better obtained.

In these relations, the content of carbon black is the content (unit: parts by mass) with respect to 100 parts by mass of the rubber component, and the content of BR is the content (unit: mass) in 100% by mass of the rubber component. %).

From the viewpoint of overall performance of dry steering stability and wet steering stability, it is preferable that the content of silica> the content of carbon black in the rubber composition.

The silica content / carbon black content is preferably 1.1 or more, preferably 2.5 or less, more preferably 1.8 or less, still more preferably 1.5 or less. Within the above range, the effect tends to be better obtained.

In these relations, the content of carbon black and the content of silica are the contents (unit: parts by mass) with respect to 100 parts by mass of the rubber component.

The rubber composition preferably contains a silane coupling agent.
The silane coupling agent is not particularly limited, and for example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) tetrasulfide, and the like. Bis (3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (2-triethoxysilylethyl) trisulfide, bis (4-trimethoxysilylbutyl) trisulfide, bis ( 3-Triethoxysilylpropyl) disulfide, bis (2-triethoxysilylethyl) disulfide, bis (4-triethoxysilylbutyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (2-trimethoxysilylethyl) ) Disulfide, bis (4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N, N-dimethylthiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyltetrasulfide, 3- Sulfide type such as triethoxysilylpropyl methacrylate monosulfide, mercapto type such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, vinyl type such as vinyltriethoxysilane and vinyltrimethoxysilane, 3-aminopropyl Amino-based such as triethoxysilane and 3-aminopropyltrimethoxysilane, glycidoxy-based such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, 3-nitropropyltrimethoxysilane, 3- Examples thereof include nitro type such as nitropropyltriethoxysilane, chloro type such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. As commercially available products, for example, products such as Degussa, Momentive, Shinetsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., Toray Dow Corning Co., Ltd. can be used. These may be used alone or in combination of two or more. Of these, the sulfide system is preferable.

The content of the silane coupling agent is preferably 3 parts by mass or more, more preferably 6 parts by mass or more, still more preferably 8 parts by mass or more, and preferably 15 parts by mass or less with respect to 100 parts by mass of silica. , More preferably 12 parts by mass or less, still more preferably 10 parts by mass or less. Within the above range, the effect tends to be better obtained.

The rubber composition contains a resin component.
Examples of the resin component include aromatic resins and terpene resins. These may be used alone or in combination of two or more. Of these, aromatic resins are preferable.

The aromatic resin is a polymer containing an aromatic monomer as a constituent monomer. For example, a homopolymer obtained by polymerizing one aromatic monomer alone, or two or more aromatic monomers. In addition to the copolymer obtained by copolymerizing the above, examples thereof include an aromatic monomer and a copolymer with another monomer capable of copolymerizing with the aromatic monomer.

Examples of the aromatic monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, and the like. Styrene-based monomers such as o-chlorostyrene, m-chlorostyrene, p-chlorostyrene; phenol-based monomers such as phenol, alkylphenol and alkoxyphenol; naphthol-based monomers such as naphthol, alkylnaphthol and alkoxynaphthol. ; Kumaron, Phenol, etc. can be mentioned. These may be used alone or in combination of two or more.

The aromatic resin is a polymer containing a phenol-based monomer as a constituent monomer (phenol-based resin), a polymer containing kumaron, and an inden as a constituent monomer (Kumaron Inden) because the effect tends to be obtained better. (Based resin) is preferable, and phenol-based resin is more preferable.

As the phenol-based resin, a phenol-aldehyde condensed resin obtained by reacting a phenol-based monomer with aldehydes such as formaldehyde, acetaldehyde, and furfural with an acid or an alkali catalyst; a phenol-based monomer and acetylene, etc. Examples thereof include a phenol alkyne condensed resin obtained by reacting with an alkyne; a modified phenol resin obtained by modifying these resins with a compound such as cashew oil; and the like. Of these, a phenol alkyne condensed resin is preferable, and an alkylphenol / acetylene condensed resin is more preferable.

Examples of commercial products of the above-mentioned resins include Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Toso Co., Ltd., Rutgers Chemicals Co., Ltd., BASF Co., Ltd., Arizona Chemical Co., Ltd., and Nikko Chemical Co., Ltd. ), Nippon Shokubai Co., Ltd., JXTG Energy Co., Ltd., Arakawa Chemical Industry Co., Ltd., Taoka Chemical Industry Co., Ltd., etc. can be used.

The content of the resin component (when a plurality of types of resins are used in combination, the total content thereof) is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and further preferably 20 parts by mass with respect to 100 parts by mass of the rubber component. It is 5 parts by mass or more, preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and further preferably 30 parts by mass or less. Within the above range, the effect tends to be better obtained.

In the above rubber composition, the content of the resin component >> | the content of silica-the content of carbon black |.

The content of the resin component / | the content of silica-the content of carbon black | is preferably 1.2 or more, more preferably 2.0 or more, still more preferably 3.0 or more, and particularly preferably 3.5 or more. It is preferably 5.0 or less, more preferably 4.5 or less, still more preferably 4.0 or less. Within the above range, the effect tends to be better obtained.

In these relations, the content of the resin component, the content of silica, and the content of carbon black are the contents (unit: parts by mass) with respect to 100 parts by mass of the rubber component.

In the rubber composition, the content of the resin component / the content of silica is preferably 0.2 or more, more preferably 0.3 or more, still more preferably 0.4 or more, and preferably 1.2. Below, it is more preferably 0.8 or less, still more preferably 0.6 or less. Within the above range, the effect tends to be better obtained.
In this relationship, the content of the resin component and the content of silica are the contents (unit: parts by mass) with respect to 100 parts by mass of the rubber component.

In the rubber composition, the content of the resin component / the content of carbon black is preferably 0.2 or more, more preferably 0.3 or more, still more preferably 0.4 or more, and preferably 1. It is 2 or less, more preferably 0.8 or less, still more preferably 0.6 or less. Within the above range, the effect tends to be better obtained.
In this relationship, the content of the resin component and the content of carbon black are the contents (unit: parts by mass) with respect to 100 parts by mass of the rubber component.

The rubber composition contains an ethylene copolymer.
The ethylene copolymer is a copolymer containing a structural unit derived from ethylene (ethylene unit), and is, for example, a copolymer of ethylene and an aromatic monomer (for example, styrene), ethylene, or an aromatic simple substance. Examples thereof include polymers of merits and conjugated diene-based monomers (for example, 1,3-butadiene). Specific examples include an ethylene-styrene copolymer, an ethylene-styrene-butadiene copolymer, and the like, and as a commercially available product, a product of Stratol Co., Ltd. or the like can be used. These may be used alone or in combination of two or more.
The ethylene copolymer is not included in the resin component.

In the ethylene copolymer, the ethylene unit may be formed by hydrogenation to a structural unit (butadiene unit) derived from 1,3-butadiene. That is, the ethylene copolymer may be a hydrogenated product of a (co) polymer having a butadiene unit.

The ethylene copolymer has a styrene-derived structural unit (styrene unit) and a 1,3-butadiene-derived structural unit (butadiene unit) together with the ethylene unit because the effect tends to be better obtained. The copolymer is preferable, the hydrogenated product of the ethylene-styrene-butadiene copolymer and the styrene-butadiene copolymer is more preferable, and the hydrogenated product of the styrene-butadiene copolymer is further preferable.

When the ethylene copolymer is a hydrogenated product of a styrene-butadiene copolymer, the hydrogenation rate is preferably 30 mol% or more, more preferably 40 mol%, with the total butadiene unit before hydrogenation being 100 mol%. % Or more, more preferably 50 mol% or more, preferably 80 mol% or less, more preferably 70 mol% or less, still more preferably 60 mol% or less. Within the above range, the effect tends to be better obtained.
The hydrogenation rate can be calculated from the spectral reduction rate of the unsaturated bond portion of the spectrum obtained by measuring ¹ H-NMR.

The content of the ethylene copolymer is preferably 5 parts by mass or more, more preferably 8 parts by mass or more, still more preferably 10 parts by mass or more, and preferably 30 parts by mass with respect to 100 parts by mass of the rubber component. Hereinafter, it is more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less. Within the above range, the effect tends to be better obtained.

In the above rubber composition, the content of BR> the content of the ethylene copolymer.

The BR content / ethylene copolymer is preferably 1.5 or more, more preferably 1.8 or more, still more preferably 2.0 or more, and preferably 4.0 or less, more preferably 3. It is 0 or less, more preferably 2.5 or less. Within the above range, the effect tends to be better obtained.

In these relations, the content of BR is the content (unit: mass%) in 100% by mass of the rubber component, and the content of the ethylene copolymer is the content (unit) with respect to 100 parts by mass of the rubber component. : Mass part).

The rubber composition preferably contains SBR and / or BR soluble in acetone when immersed in acetone for 24 hours.
In the present specification, SBR and BR soluble in acetone when immersed in acetone for 24 hours are the above-mentioned rubber compositions after vulcanization, which are extracted with acetone for 24 hours by a method based on JIS K 6229: 2015. At the same time, at least a part of SBR and BR is eluted in acetone. The SBR and BR are not included in the rubber component and the resin component.

As the SBR and BR soluble in acetone when immersed in acetone for 24 hours, liquid SBR and BR (hereinafter, also referred to as liquid SBR and liquid BR) at room temperature (25 ° C.) can be used, and are commercially available products. , Crayvalley Co., Ltd., Kuraray Co., Ltd. and other products can be used.

The weight average molecular weight (Mw) of SBR, BR (liquid SBR, liquid BR) soluble in acetone when immersed in acetone for 24 hours is preferably 9000 or less, more preferably 6000 or less, still more preferably 4500 or less, and also. It is preferably 100 or more, more preferably 1000 or more, and further preferably 2000 or more. Within the above range, the effect tends to be better obtained.

The content of SBR and BR (liquid SBR, liquid BR) soluble in acetone when immersed in acetone for 24 hours is preferably 5 parts by mass or more, more preferably 8 parts by mass or more, based on 100 parts by mass of the rubber component. It is more preferably 10 parts by mass or more, preferably 30 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less. Within the above range, the effect tends to be better obtained.

The rubber composition preferably contains a borate compound as a processing aid.
Examples of the borate compound include alkali metal salts such as sodium borate and potassium borate, alkaline earth metal salts such as magnesium borate, and hydrates thereof. These may be used alone or in combination of two or more. Of these, alkali metal salts and their hydrates are preferable, sodium borate and its hydrates are more preferable, and sodium tetraborate decahydrate (borax) is even more preferable.

As commercially available borate compounds, products such as Kishida Chemical Co., Ltd. and Kenei Pharmaceutical Co., Ltd. can be used.

The content of the borate compound is preferably 0.8 parts by mass or more, more preferably 1.2 parts by mass or more, further preferably 1.5 parts by mass or more, and preferably 4.5 parts by mass or less. , More preferably 3.5 parts by mass or less, still more preferably 2.5 parts by mass or less. Within the above range, the effect tends to be better obtained.

The rubber composition may contain oil.
Examples of the oil include process oils, vegetable oils and fats, or mixtures thereof. As the process oil, for example, a paraffin-based process oil, an aroma-based process oil, a naphthenic process oil, or the like can be used. Vegetable oils and fats include castor oil, cottonseed oil, sesame oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut oil, rosin, pine oil, pineapple, tall oil, corn oil, rice oil, beni flower oil, and sesame oil. Examples thereof include olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. Commercial products include Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., JXTG Energy Co., Ltd., Orisoi Co., Ltd., H & R Co., Ltd., Toyokuni Seiyu Co., Ltd., Showa Shell Sekiyu Co., Ltd., Fuji Kosan Co., Ltd., etc. Products can be used. These may be used alone or in combination of two or more.

The oil content is preferably 15 parts by mass or more, more preferably 25 parts by mass or more, still more preferably 30 parts by mass or more, and preferably 60 parts by mass or less, based on 100 parts by mass of the rubber component. It is preferably 50 parts by mass or less, more preferably 40 parts by mass or less. Within the above range, the effect tends to be better obtained.

The rubber composition may contain an anti-aging agent.
Examples of the antiaging agent include naphthylamine-based antiaging agents such as phenyl-α-naphthylamine; diphenylamine-based antiaging agents such as octylated diphenylamine and 4,4'-bis (α, α'-dimethylbenzyl) diphenylamine; N. -Isopropyl-N'-phenyl-p-phenylenediamine, N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, N, N'-di-2-naphthyl-p-phenylenediamine, etc. P-Phenylenediamine-based anti-aging agent; quinoline-based anti-aging agent such as a polymer of 2,2,4-trimethyl-1,2-dihydroquinolin; 2,6-di-t-butyl-4-methylphenol, Monophenolic antioxidants such as styrenated phenol; tetrakis- [methylene-3- (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] bis, tris, polyphenolic aging such as methane Examples include preventive agents. As commercial products, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

The content of the antiaging agent is preferably 1 part by mass or more, more preferably 2 parts by mass or more, still more preferably 3 parts by mass or more, and preferably 10 parts by mass or less with respect to 100 parts by mass of the rubber component. , More preferably 8 parts by mass or less, still more preferably 6 parts by mass or less. Within the above range, the effect tends to be better obtained.

The rubber composition may contain wax.
The wax is not particularly limited, and examples thereof include petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as plant waxes and animal waxes; synthetic waxes such as polymers such as ethylene and propylene. As commercial products, products such as Ouchi Shinko Kagaku Kogyo Co., Ltd., Nippon Seiro Co., Ltd., and Seiko Kagaku Co., Ltd. can be used. These may be used alone or in combination of two or more.

The content of the wax is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and preferably 10 parts by mass or less, more preferably 6 parts by mass or less, based on 100 parts by mass of the rubber component. .. Within the above range, the effect tends to be better obtained.

The rubber composition may contain stearic acid.
As the stearic acid, conventionally known ones can be used, and as commercially available products, products such as NOF Corporation, Kao Corporation, Wako Pure Chemical Industries, Ltd., and Chiba Fatty Acid Co., Ltd. can be used. These may be used alone or in combination of two or more.

The content of stearic acid is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and preferably 10 parts by mass or less, more preferably 6 parts by mass or less, based on 100 parts by mass of the rubber component. be. Within the above range, the effect tends to be better obtained.

The rubber composition may contain zinc oxide.
Conventionally known zinc oxide can be used, and commercially available products include Mitsui Metal Mining Co., Ltd., Toho Zinc Co., Ltd., HakusuiTech Co., Ltd., Shodo Chemical Industry Co., Ltd., and Sakai Chemical Industry Co., Ltd. Products such as can be used. These may be used alone or in combination of two or more.

The content of zinc oxide is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 6 parts by mass or less, based on 100 parts by mass of the rubber component. be. Within the above range, the effect tends to be better obtained.

The rubber composition may contain sulfur.
Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur, which are generally used in the rubber industry. As commercial products, products such as Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Industry Co., Ltd., Flexis Co., Ltd., Nippon Inui Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

The sulfur content is preferably 0.8 parts by mass or more, more preferably 1.2 parts by mass or more, still more preferably 1.5 parts by mass or more, and preferably 1.5 parts by mass or more with respect to 100 parts by mass of the rubber component. It is 6 parts by mass or less, more preferably 4 parts by mass or less, and further preferably 3 parts by mass or less. Within the above range, the effect tends to be better obtained.

The rubber composition may contain a vulcanization accelerator.
Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and dibenzothiazolyl disulfide (MBTS); tetramethylthiuram disulfide (TMTD), tetrakis ( 2-Ethylhexyl) Thiuram-based vulcanization accelerators such as thiuram disulfide (TOT-N); N-cyclohexyl-2-benzothiadylsulfenamide (CBS), N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-oxyethylene-2-benzothiazolesulfenamide, N, N'-diisopropyl-2-benzothiazolesulfenamide and other sulfenamide-based vulcanization accelerators; diphenylguanidine, dioltotrilguanidine, Examples thereof include guanidine-based vulcanization accelerators such as orthotrilbiguanidine. As commercial products, products such as Sumitomo Chemical Co., Ltd. and Ouchi Shinko Chemical Industry Co., Ltd. can be used. These may be used alone or in combination of two or more.

The content of the vulcanization accelerator is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 4 parts by mass or more, and preferably 10 parts by mass with respect to 100 parts by mass of the rubber component. Hereinafter, it is more preferably 8 parts by mass or less, still more preferably 6 parts by mass or less. Within the above range, the effect tends to be better obtained.

In addition to the above components, additives generally used in the tire industry, such as organic peroxides, may be further added to the rubber composition. The content of the additive is preferably 0.1 to 200 parts by mass with respect to 100 parts by mass of the rubber component.

The rubber composition can be produced, for example, by kneading each of the above components using a rubber kneading device such as an open roll or a Banbury mixer, and then vulcanizing.

As the kneading conditions, in the base kneading step of kneading additives other than the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 100 to 180 ° C., preferably 120 to 170 ° C. In the finish kneading step of kneading the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 120 ° C. or lower, preferably 85 to 110 ° C. Further, the composition in which the vulcanizing agent and the vulcanization accelerator are kneaded is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 140 to 190 ° C, preferably 150 to 185 ° C. The vulcanization time is usually 5 to 15 minutes.

The rubber composition includes, for example, tread (cap tread), sidewall, base tread, under tread, shoulder, clinch, bead apex, breaker cushion rubber, carcass cord covering rubber, insulation, chafer, inner liner and the like. It can also be used as a tire member (as a rubber composition for a tire) such as a side reinforcing layer of a run-flat tire. Above all, it is suitable for tread.

The tire of the present invention is manufactured by a usual method using the above rubber composition.
That is, the unvulcanized tire is formed by extruding the rubber composition according to the shape of a tread or the like at the unvulcanized stage and molding the rubber composition together with other tire members by a normal method on a tire molding machine. Form. A tire is obtained by heating and pressurizing this unvulcanized tire in a vulcanizer.

The above tires (pneumatic tires, etc.) are passenger car tires; truck / bus tires; two-wheeled vehicle tires; high-performance tires; winter tires such as studless tires; run-flat tires having side reinforcing layers; sound absorbing members such as sponges. Tire with sound absorbing member provided in the tire cavity; Tire with a sealing member provided inside the tire or inside the tire cavity with a sealant that can be sealed at the time of puncture; Electronic parts such as sensors and wireless tags are provided inside the tire or inside the tire cavity. It can be used for tires with electronic parts and the like, and is suitable for passenger car tires.

The size of the tire is not particularly limited, and for example, the tire width can be appropriately selected within the range of 100 to 400 mm, the flatness within the range of 25 to 85%, and the rim diameter within the range of 10 to 25 inches. Is. Specific examples include 105 / 50R16, 115 / 50R17, 125 / 55R20, 135 / 45R21, 145 / 45R21, 155 / 45R18, 165 / 45R22, 175 / 45R23, 185 / 60R20, 195 / 55R14, 205 / 40R16, 215. / 40R16, 225 / 40R17, 235 / 40R17, 245 / 40R16, 255 / 40R17, 265 / 40R17, 275 / 35R18, 285 / 30R19, 295 / 45R20 and the like.

The present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

Hereinafter, various chemicals used in Examples and Comparative Examples will be described.

(Rubber component)
SBR1: Modified SBR synthesized in Production Example 1 below (styrene amount: 25% by mass, vinyl amount: 55% by mass, Mw: 450,000)
SBR2: Modified SBR synthesized in Production Example 2 below (styrene amount: 40% by mass, vinyl amount: 30% by mass, Mw: 950,000)
SBR3: Buna VSL5025-2HM manufactured by LANXESS (styrene amount: 25% by mass, vinyl amount: 50% by mass, oil content 37.5 parts by mass with respect to 100 parts by mass of rubber solid content)
SBR4: Buna VSL 2438-2 HM manufactured by LANXESS (styrene amount: 38% by mass, vinyl amount: 24% by mass, oil content 37.5 parts by mass with respect to 100 parts by mass of rubber solid content)
BR1: BR150B manufactured by Ube Industries, Ltd. (cis amount: 97% by mass, vinyl amount: 1% by mass)
BR2: N103 manufactured by Asahi Kasei Chemicals Co., Ltd. (cis amount: 38% by mass, vinyl amount: 12% by mass)

(Chemicals other than rubber components)
Carbon black: N134 (CTAB: 135m ² / g)
Silica 1: Ultrasil VN3 manufactured by Evonik Degussa (CTAB: 165m ² / g)
Silica 2: Zeosil Premium 200MP (CTAB: 203m ² / g) manufactured by Rhodia.
Silane coupling agent: Si266 (bis (3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa.
Liquid SBR: Ricon100 manufactured by Crayvalley (Liquid SBR, Mw: 4500)
Resin 1: Knit resin Kumaron V-120 (Kumaron inden resin) manufactured by Nikko Kagaku Co., Ltd.
Resin 2: BASF's cholesterol (pt-butylphenol / acetylene condensed resin)
Oil: A / O mixed wax manufactured by Sankyo Yuka Kogyo Co., Ltd .: Ozo Ace 0355 manufactured by Nippon Seiro Co., Ltd.
Anti-aging agent 1: Nocrack 6C (N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Anti-aging agent 2: Nocrack RD (Poly (2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Ethylene copolymer 1: Stractol 40MS (ethylene-styrene copolymer) manufactured by Stractol.
Ethylene copolymer 2: Hydrogenated product of Ricon 100 manufactured by Crayvalley (hydrogenated styrene-butadiene copolymer, hydrogenation rate: 50 mol%)
Borate compound: Tenhydrate of sodium tetraborate manufactured by Kishida Chemical Co., Ltd. Stearic acid: Stearic acid "Tsubaki" manufactured by NOF CORPORATION
Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Metal Mining Co., Ltd. Sulfur: Powdered sulfur vulcanization accelerator manufactured by Tsurumi Chemical Industry Co., Ltd. 1: Noxeller CZ (N-cyclohexyl-) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. 2-Benzothiazolyl vulcan amide)
Vulcanization accelerator 2: Noxeller D (diphenylguanidine) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.

(Manufacturing Example 1)
A nitrogen-substituted autoclave reactor was charged with cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene. After adjusting the temperature of the contents of the reactor to 20 ° C., n-butyllithium was added to initiate polymerization. Polymerization was carried out under adiabatic conditions, and the maximum temperature reached 85 ° C. When the polymerization conversion rate reached 99%, 1,3-butadiene was added, and after further polymerization for 5 minutes, 3-diethylaminopropyltrimethoxysilane was added as a denaturing agent to carry out the reaction. After completion of the polymerization reaction, 2,6-di-tert-butyl-p-cresol was added. Then, the solvent was removed by steam stripping and dried by a heat roll adjusted to 110 ° C. to obtain SBR1.

(Manufacturing Example 2)
A nitrogen-substituted autoclave reactor was charged with cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene. After adjusting the temperature of the contents of the reactor to 20 ° C., n-butyllithium was added to initiate polymerization. Polymerization was carried out under adiabatic conditions, and the maximum temperature reached 85 ° C. When the polymerization conversion reaches 99%, 1,3-butadiene is added, and after further polymerization for 5 minutes, N, N-bis (trimethylsilyl) -3-aminopropyltriethoxysilane is added as a denaturant. The reaction was carried out. After completion of the polymerization reaction, 2,6-di-tert-butyl-p-cresol was added. Then, the solvent was removed by steam stripping and dried by a heat roll adjusted to 110 ° C. to obtain SBR2.

(Examples and comparative examples)
According to the formulation shown in Table 1, using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd., knead the materials other than sulfur and the vulcanization accelerator for 5 minutes under the condition of 150 ° C. to knead the kneaded product. Obtained. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and the mixture was kneaded under the condition of 80 ° C. for 5 minutes using an open roll to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition is formed into a tread shape and bonded together with other tire members to form an unvulcanized tire, which is press-vulcanized for 12 minutes under the condition of 150 ° C. to obtain a test tire (test tire). Size: 175 / 60R18) was manufactured. The following evaluations were performed using the obtained test tires, and the results are shown in Table 1.
In Table 1, the rubber content in the oil-extended rubber is described in the rubber column, and the oil content in the oil-extended rubber is added to the oil column.

(Dry steering stability)
The lap time when the vehicle equipped with the above test tires on all wheels ran 10 laps on a test course on a dry road surface was measured. In addition, the tires were run under the same conditions using reference tires having a longer lap time than in any of the examples and comparative examples. Then, the difference in the lap time between each Example and Comparative Example and the reference tire is expressed exponentially with Comparative Example 3 as 100. The larger the index, the larger the difference from the lap time of the reference tire (the amount of shortening of the lap time), indicating that the dry steering stability (steering stability on a dry road surface) is excellent.

(Wet steering stability)
The lap time when the vehicle equipped with the above test tires on all wheels ran 10 laps on a test course on a wet road surface was measured. In addition, the tires were run under the same conditions using reference tires having a longer lap time than in any of the examples and comparative examples. Then, the difference in the lap time between each Example and Comparative Example and the reference tire is expressed exponentially with Comparative Example 4 as 100. The larger the index, the larger the difference from the lap time of the reference tire (the amount of shortening of the lap time), indicating that the wet steering stability (steering stability on a wet road surface) is excellent.

From Table 1, the examples were superior to the comparative examples in the overall performance (total of each index) of the target dry steering stability and wet steering stability.

Claims (8)

It contains a rubber component containing styrene-butadiene rubber and butadiene rubber, silica, carbon black, a resin component, and an ethylene copolymer.
The content of the resin component >> | the content of the silica-the content of the carbon black |
The content of the carbon black> the content of the butadiene rubber.
A rubber composition for a tire in which the content of the butadiene rubber> the content of the ethylene copolymer. The rubber composition for a tire according to claim 1, wherein the cis amount of the butadiene rubber is 90% or less. The rubber composition for a tire according to claim 1 or 2, which contains a styrene-butadiene rubber and / or a butadiene rubber that is soluble in acetone when immersed in acetone for 24 hours. The rubber composition for a tire according to any one of claims 1 to 3, wherein the content of silica> the content of carbon black. The rubber composition for a tire according to any one of claims 1 to 4, wherein the silica has a specific surface area of cetyltrimethylammonium bromide of 180 m ² / g or more. The rubber composition for a tire according to any one of claims 1 to 5, wherein the ethylene copolymer is a copolymer having an ethylene unit, a styrene unit and a butadiene unit. The rubber composition for a tire according to any one of claims 1 to 6, wherein the resin component contains a phenol-based resin. A tire using the rubber composition according to any one of claims 1 to 7.