JP2023077161A - Tire rubber composition and tire - Google Patents

Abstract

To provide a tire rubber composition and a tire which can achieve improvement in overall performance of low fuel consumption and wear resistance during high-speed traveling.SOLUTION: The present invention relates to a tire rubber composition that comprises a rubber component comprising styrene-butadiene rubber, silica, and a resin component. In the rubber component 100 mass%, a content of the styrene-butadiene rubber is more than 60 mass%, the styrene-butadiene rubber has a substantial vinyl content of more than 40 mass%, and the tire rubber composition has a specific gravity of less than 1.180, with the silica content/the substantial vinyl content of the styrene-butadiene rubber<2.0.SELECTED DRAWING: None

Description

The present disclosure relates to rubber compositions for tires and tires.

Various techniques for improving fuel efficiency and wear resistance have been studied so far (see, for example, Patent Documents 1 and 2). However, in recent years, there has been a demand for further improvements in these performances.

JP-A-2000-344955 JP 2017-141405 A

An object of the present disclosure is to solve the above problems and to provide a rubber composition for a tire and a tire that can improve the overall performance of low fuel consumption during high-speed driving and wear resistance.

The present disclosure contains a rubber component containing styrene-butadiene rubber, silica, and a resin component, the content of the styrene-butadiene rubber is more than 60% by mass in 100% by mass of the rubber component, and the styrene-butadiene rubber has a substantial vinyl content of more than 40% by mass, a specific gravity of less than 1.180, and a content of silica/substantial vinyl content of styrene-butadiene rubber<2.0.

The present disclosure contains a rubber component containing styrene-butadiene rubber, silica, and a resin component, the content of the styrene-butadiene rubber is more than 60% by mass in 100% by mass of the rubber component, and the styrene-butadiene rubber has a substantial vinyl content of more than 40% by mass, a specific gravity of less than 1.180, and a content of silica/substantial vinyl content of styrene-butadiene rubber <2.0, The overall performance of low fuel consumption during high-speed running and wear resistance is improved.

The rubber composition for a tire of the present disclosure contains a rubber component containing styrene-butadiene rubber, silica, and a resin component, and the content of the styrene-butadiene rubber exceeds 60% by mass in 100% by mass of the rubber component. The styrene-butadiene rubber has a substantial vinyl content of more than 40% by mass, a specific gravity of less than 1.180, and a silica content/substantial vinyl content of the styrene-butadiene rubber<2.0.

The reason why the aforementioned effects are obtained with the rubber composition is presumed as follows.
In the above rubber composition, it is believed that the silica is easily dispersed in the styrene-butadiene rubber (SBR) by covering the surface of the silica with the resin component during mixing. It is believed that this reduces heat build-up and provides sufficient reinforcement, thereby improving fuel economy and wear resistance.
In addition, it is believed that the interaction between the resin component and the styrene portion of the SBR forms a pseudo-network, further improving the wear resistance.
Furthermore, by setting the amount of silica/substantial amount of vinyl in SBR to < 2.0, the double bond portion (vinyl portion) that is closer to silica in SBR and silica are more likely to bond, and cannot be bonded to SBR. Since generation of excess silica is suppressed, it is thought that fuel economy and wear resistance are efficiently improved.
By adopting the above configuration, it becomes easier to obtain dispersion and bonding of silica in a microscopic state, and even at high speeds that are high frequency inputs, vibration of the polymer is suppressed and heat generation is reduced. Therefore, it is thought that fuel efficiency and wear resistance during high-speed driving are improved.
In addition, by setting the specific gravity of the rubber composition to less than 1.180, the inertia during rolling is suppressed, and the deformation applied to the rubber composition is reduced, resulting in improved fuel efficiency and wear resistance during high-speed running. expected to improve.
It is believed that due to the above effects, the overall performance of low fuel consumption during high-speed running and wear resistance is improved.

The rubber composition contains a rubber component.
Here, the rubber component is a component that contributes to cross-linking 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 is preferably 2,000,000 or less, more preferably 1,500,000 or less, and still more preferably 1,000,000. It is below. Within the above range, the effect tends to be obtained more favorably.

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 styrene content in the rubber component is preferably 30% by mass or less, more preferably less than 25% by mass, still more preferably 22% by mass or less, and is preferably 10% by mass or more, more preferably 15% by mass or more. , more preferably 20% by mass or more. Within the above range, the effect tends to be obtained more favorably.

Here, the total styrene content in the rubber component is the total content (unit: mass %) of the styrene part contained in the total amount of the rubber component, and Σ (content of each rubber component × styrene content in each rubber component /100). For example, in 100% by mass of the rubber component, SBR with a styrene content of 40% by mass is 85% by mass, SBR with a styrene content of 25% by mass is 5% by mass, and BR with a styrene content of 0% by mass is 10% by mass. , the total styrene content in the rubber component is 35.25% by mass (=85×40/100+5×25/100+10×0/100).

The total vinyl content in the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, and is 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 obtained more favorably.

Here, the total vinyl content in the rubber component is the total content of vinyl bonds in the butadiene portion of SBR and BR contained in the rubber component (unit: parts by mass) when the total mass of the rubber component is 100. . For example, in 100 parts by mass of the rubber component, 85 parts by mass of SBR containing 40% by mass of styrene and 30% by mass of vinyl, 5 parts by mass of SBR containing 20% by mass of styrene and 20% by mass of vinyl, and 5 parts by mass of vinyl Amount: When 10% by mass of BR is 10 parts by mass, the total amount of vinyl in the rubber component is 17.1 parts by mass (= 85 x (100 [mass%] - 40 [mass%]) x 30 [mass %]+5×(100 [mass %]−20 [mass %])×20 [mass %]+10×10 [mass %]).

The styrene content and vinyl content in each rubber component can be measured by a nuclear magnetic resonance (NMR) method.
Further, the total styrene content and total vinyl content in the rubber component are calculated according to the above-mentioned formulas in the examples of the present specification. MS), etc., may be analyzed from the tire.

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), etc. can be used. Examples of commercially available products include products of Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Co., Ltd., Nippon Zeon Co., Ltd., and the like.

The SBR may be oil-extended rubber extended with oil or resin-extended rubber extended with resin. These may be used alone or in combination of two or more.
The oil used for the oil-extended rubber and the resin used for the resin-extended rubber are the same as those described later. Although the oil content in the oil-extended rubber and the resin content in the resin-extended rubber are not particularly limited, they are usually about 5 to 50 parts by mass per 100 parts by mass of the rubber solid content.

The SBR may be modified to introduce functional groups that interact with fillers such as silica.
Examples of the above functional groups include silicon-containing groups (—SiR ₃ (R is the same or different, hydrogen, hydroxyl group, hydrocarbon group, alkoxy group, etc.), amino group, amide group, isocyanate group, imino group, imidazole group, urea group, ether group, carbonyl group, oxycarbonyl group, mercapto group, sulfide group, disulfide group, sulfonyl group, sulfinyl group, thiocarbonyl group, ammonium group, imide group, hydrazo group, azo group, diazo group, carboxyl group, nitrile group, pyridyl group, alkoxy group, hydroxyl group, oxy group, epoxy group, etc. These functional groups may have substituents, and among these, silicon-containing groups are preferred. —SiR ₃ (R is the same or different, hydrogen, hydroxyl group, hydrocarbon group (preferably hydrocarbon group having 1 to 6 carbon atoms (more preferably alkyl group having 1 to 6 carbon atoms)) or alkoxy group (preferably is an alkoxy group having 1 to 6 carbon atoms)), and at least one of R is more preferably a hydroxyl group).

Specific examples of the compound (modifier) that introduces the functional group include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltri ethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane and the like.

Hydrogenated SBR in which hydrogen is added can also be used as SBR.
When the SBR is hydrogenated SBR, the hydrogenation method and reaction conditions are not particularly limited, and hydrogenation may be carried out by a known method under known conditions. Usually, it is carried out at 20 to 150° C. under hydrogen pressure of 0.1 to 10 MPa in the presence of a hydrogenation catalyst. Other production methods and conditions are not particularly limited, and, for example, the contents described in International Publication No. 2016/039005 can be applied.
Hydrogenated SBR has the same structure as a copolymer of ethylene, butadiene, and styrene as a result of adding hydrogen to the butadiene portion of SBR. Therefore, in this specification, hydrogenated SBR includes not only a hydrogenated product of a copolymer of butadiene and styrene (SBR), but also a copolymer of ethylene, butadiene, and styrene.

The hydrogenation rate of the hydrogenated SBR is preferably 65 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, and preferably 100 mol% of the total butadiene units before hydrogenation. is 95 mol % or less, more preferably 92 mol % or less, still more preferably 90 mol % or less. Within the above range, the effect tends to be obtained more favorably.
The hydrogenation rate can be calculated from the spectrum reduction rate of the unsaturated bond portion of the spectrum obtained by measuring ¹ H-NMR.

The styrene content of SBR is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 25% by mass or more, and is preferably 40% by mass or less, more preferably 35% by mass or less, and still more preferably is 30% by mass or less. Within the above range, the effect tends to be obtained more favorably.

The actual vinyl content of SBR may be more than 40% by mass, preferably 41% by mass or more, more preferably 42% by mass or more, still more preferably 43% by mass or more, and preferably 70% by mass or less. , more preferably 60% by mass or less, and still more preferably 50% by mass or less. Within the above range, the effect tends to be obtained more favorably.

The styrene content of the SBR mentioned above means the styrene content of the SBR when there is one type of SBR, and means the average styrene content when there are multiple types of SBR.
The average styrene content of SBR can be calculated by Σ (content of each SBR × styrene content of each SBR) / total content of all SBRs. 85% by mass, styrene content: 25% by mass SBR is 5% by mass, the average styrene content of SBR is 39.2% by mass (=(85×40+5×25)/(85+5)).

In addition, the vinyl content of SBR is usually the ratio of vinyl bonds to 100% by mass of the butadiene portion of SBR. is the ratio of vinyl bonds in parts (unit: mass %).
When SBR is one type, the actual vinyl content of SBR can be calculated by (100 [mass%] - styrene content of SBR [mass%]) x vinyl content of SBR [mass%].
When there are multiple types of SBR, the "substantial vinyl content of SBR" means the average value, Σ {content of each SBR × (100 [mass%] - styrene content of each SBR [mass%]) × each SBR vinyl content [% by mass]}/Σ (content of each SBR). For example, in 100 parts by mass of the rubber component, 75 parts by mass of SBR containing 40% by mass of styrene and 30% by mass of vinyl, 15 parts by mass of SBR containing 25% by mass of styrene and 20% by mass of vinyl, and the remainder When 10 parts by mass is other than SBR, the actual vinyl content of SBR is 17.5% by mass (= {75 x (100 [mass%] - 40 [mass%]) x 30 [mass%] + 15 x (100 [% by mass]−25 [% by mass])×20 [% by mass]}/(75+15)).

The content of SBR in 100% by mass of the rubber component may be more than 60% by mass, preferably 70% by mass or more, more preferably 80% by mass or more. Within the above range, the effect tends to be obtained more favorably. The upper limit is not particularly limited, and may be 100% by mass, preferably 95% by mass or less, more preferably 90% by mass or less.

The rubber composition preferably contains an isoprene-based rubber as a rubber component.
The isoprene rubber includes natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR, and the like. As NR, for example, those commonly used in the tire industry, such as SIR20, RSS#3, and TSR20, can be used. The IR is not particularly limited, and for example IR2200 or the like commonly used in the tire industry can be used. Modified NR includes deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc. Modified NR includes epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, and the like. These may be used alone or in combination of two or more. Among them, NR is preferred.

The content of isoprene-based rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 15% by mass or more, and preferably less than 40% by mass, more It is preferably 30% by mass or less, more preferably 20% by mass or less. Within the above range, the effect tends to be obtained more favorably.

Rubber components that can be used in addition to SBR and isoprene rubber include butadiene rubber (BR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), styrene-isoprene-butadiene copolymer rubber (SIBR), etc. diene rubber. These may be used individually by 1 type, and may use 2 or more types together. Among them, BR is preferable.

The BR is not particularly limited, for example, BR1220 manufactured by Nippon Zeon Co., Ltd., BR150B manufactured by Ube Industries, Ltd., BR1280 manufactured by LG Chem, etc. BR containing 1,2-syndiotactic polybutadiene crystals (SPB) such as VCR412 and VCR617, and butadiene rubber (rare earth-based BR) synthesized using a rare earth catalyst, which are commonly used in the tire industry can be used. . These may be used individually by 1 type, and may use 2 or more types together.

BR may be oil-extended rubber extended with oil or resin-extended rubber extended with resin. These may be used alone or in combination of two or more.
The oil used for the oil-extended rubber and the resin used for the resin-extended rubber are the same as those described later. Although the oil content in the oil-extended rubber and the resin content in the resin-extended rubber are not particularly limited, they are usually about 5 to 50 parts by mass per 100 parts by mass of the rubber solid content.

BR may be modified to introduce a functional group that interacts with a filler such as silica.
Examples of the above functional groups include silicon-containing groups (—SiR ₃ (R is the same or different, hydrogen, hydroxyl group, hydrocarbon group, alkoxy group, etc.), amino group, amide group, isocyanate group, imino group, imidazole group, urea group, ether group, carbonyl group, oxycarbonyl group, mercapto group, sulfide group, disulfide group, sulfonyl group, sulfinyl group, thiocarbonyl group, ammonium group, imide group, hydrazo group, azo group, diazo group, carboxyl group, nitrile group, pyridyl group, alkoxy group, hydroxyl group, oxy group, epoxy group, etc. These functional groups may have substituents, and among these, silicon-containing groups are preferred. —SiR ₃ (R is the same or different, hydrogen, hydroxyl group, hydrocarbon group (preferably hydrocarbon group having 1 to 6 carbon atoms (more preferably alkyl group having 1 to 6 carbon atoms)) or alkoxy group (preferably is an alkoxy group having 1 to 6 carbon atoms)), and at least one of R is more preferably a hydroxyl group).

Specific examples of the compound (modifier) that introduces the functional group include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltri ethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane and the like.

Hydrogenated BR to which hydrogen is added can also be used as BR.
When BR is hydrogenated BR, the hydrogenation method and reaction conditions are not particularly limited, and hydrogenation may be performed by a known method under known conditions. Usually, it is carried out at 20 to 150° C. under hydrogen pressure of 0.1 to 10 MPa in the presence of a hydrogenation catalyst. Other production methods and conditions are not particularly limited, and, for example, the contents described in International Publication No. 2016/039005 can be applied.
Hydrogenated BR has the same structure as a copolymer of ethylene and butadiene as a result of adding hydrogen to the butadiene portion of BR. Therefore, in this specification, hydrogenated BR includes not only hydrogenated BR but also copolymers of ethylene and butadiene.

The hydrogenation rate of hydrogenated BR is preferably 65 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, and preferably 100 mol% of the total butadiene units before hydrogenation. is 95 mol % or less, more preferably 92 mol % or less, still more preferably 90 mol % or less. Within the above range, the effect tends to be obtained more favorably.
The hydrogenation rate can be calculated from the spectrum reduction rate of the unsaturated bond portion of the spectrum obtained by measuring ¹ H-NMR.

The cis amount (cis content) of BR is preferably 80% by mass or more, more preferably 85% by mass or more, still more preferably 90% by mass or more, and is preferably 99% by mass or less, more preferably 98% by mass. 97% by mass or less, more preferably 97% by mass or less. Within the above range, the effect tends to be obtained more favorably.
The cis amount of BR can be measured by infrared absorption spectrometry.

The above-mentioned cis amount of BR means the cis amount of the BR when there is one type of BR, and means the average cis amount when there are multiple types 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 BRs. When BR is 20% by mass and BR is 10% by mass with a cis amount of 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 1% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more, and is preferably 20% by mass or less, more preferably It is 15% by mass or less, more preferably 10% by mass or less. Within the above range, the effect tends to be obtained more favorably.

In the above rubber composition, it is preferable that the content of BR<the total amount of styrene in the rubber component.
Further, the ratio of BR content/total styrene content in the rubber component is preferably 0.1 or more, more preferably 0.2 or more, and is preferably 0.8 or less, more preferably 0.6 or less, More preferably, it is 0.4 or less. Within the above range, the effect tends to be obtained more favorably.
In these relationships, the content of BR and the total amount of styrene in the rubber component are the content (unit: mass %) in 100 mass % of the rubber component.

Rubber components other than isoprene-based rubber, SBR, and BR may be oil-extended rubber extended with oil or resin-extended rubber extended with resin. These may be used alone or in combination of two or more.
The oil used for the oil-extended rubber and the resin used for the resin-extended rubber are the same as those described below for the plasticizer. Although the oil content in the oil-extended rubber and the resin content in the resin-extended rubber are not particularly limited, they are usually about 5 to 50 parts by mass per 100 parts by mass of the rubber solid content.

Rubber components other than isoprene-based rubber, SBR, and BR may be modified to introduce functional groups that interact with fillers such as silica.
Examples of the above functional groups include silicon-containing groups (—SiR ₃ (R is the same or different, hydrogen, hydroxyl group, hydrocarbon group, alkoxy group, etc.), amino group, amide group, isocyanate group, imino group, imidazole group, urea group, ether group, carbonyl group, oxycarbonyl group, mercapto group, sulfide group, disulfide group, sulfonyl group, sulfinyl group, thiocarbonyl group, ammonium group, imide group, hydrazo group, azo group, diazo group, carboxyl group, nitrile group, pyridyl group, alkoxy group, hydroxyl group, oxy group, epoxy group, etc. These functional groups may have substituents, and among these, silicon-containing groups are preferred. —SiR ₃ (R is the same or different, hydrogen, hydroxyl group, hydrocarbon group (preferably hydrocarbon group having 1 to 6 carbon atoms (more preferably alkyl group having 1 to 6 carbon atoms)) or alkoxy group (preferably is an alkoxy group having 1 to 6 carbon atoms)), and at least one of R is more preferably a hydroxyl group).

Specific examples of the compound (modifier) that introduces the functional group include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltri ethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane and the like.

Raw materials (monomers) for synthetic rubbers such as SBR and BR may be petroleum-derived or biomass-derived. Whether or not the raw material is derived from biomass can be determined by pMC (percent modern carbon) measured according to ASTM D6866-10.

The pMC is the ratio of ^{the 14} C concentration of the sample to the ¹⁴ C concentration of the modern standard reference, and this value is used as an index showing the biomass ratio of the compound (rubber). The significance of this value will be described below.

In 1 mol (6.02×10 ²³ ) of carbon atoms, there are about 6.02×10 ^{11 14} C atoms, which is about 1/1 trillion of normal carbon atoms. ¹⁴ C is called a radioactive isotope and its half-life is 5730 years and decreases regularly. It takes 226,000 years for all of these to collapse. Therefore, in fossil fuels such as coal, petroleum, and natural gas, it is thought that more than 226,000 years have passed since carbon dioxide, etc. in the atmosphere was taken in and fixed by plants. All of the ¹⁴ C elements that were also included in the have collapsed. Therefore, at present, which is the 21st century, fossil fuels such as coal, petroleum, and natural gas do not contain ^{the 14} C element at all. Therefore, chemical substances produced using these fossil fuels as raw materials do not contain the ¹⁴ C element at all.

On the other hand, ¹⁴ C is continuously produced by cosmic ray nuclear reactions in the atmosphere, and the amount of 14 C is in balance with the decrease due to radioactive decay, and the amount of ¹⁴ C is constant in the earth's atmospheric environment. Therefore, the ¹⁴ C concentration of biomass resource-derived substances circulating in the current environment is about 1×10 ⁻¹² mol % with respect to all C atoms, as described above. Therefore, using the difference between these values, it is possible to calculate the ratio (biomass ratio) of natural resource-derived compounds (biomass resource-derived compounds) in a certain compound (rubber).

This ¹⁴ C is generally measured as follows. ¹³ C concentration ( ¹³ C/ ¹² C), ¹⁴ C concentration ( ¹⁴ C/ ¹² C) measurements are performed using tandem accelerator-based accelerator mass spectrometry. In the measurement, ^{the 14} C concentration in circulating carbon in nature in 1950 is adopted as a modern standard reference for ^{the 14} C concentration. As a specific standard substance, an oxalic acid standard provided by NIST (National Institute of Standards and Technology) is used. The specific radioactivity of carbon in this oxalic acid (the radioactivity intensity of ¹⁴ C per 1 g of carbon) is fractionated for each carbon isotope, corrected to a constant value for ¹³ C, and the decay from 1950 AD to the date of measurement. The corrected value is used as the standard ¹⁴ C concentration value (100%). The pMC value is the ratio of this value to the value of the sample actually measured.

Therefore, if the rubber is made of 100% biomass (natural)-derived substances, it will show a value of about 110 pMC, although there are regional differences (currently, it does not reach 100 pMC). often). On the other hand, when this ¹⁴ C concentration is measured for chemical substances derived from fossil fuels such as petroleum, it indicates approximately 0 pMC (for example, 0.3 pMC). This value corresponds to the above-mentioned biomass ratio of 0%.

From the above, it is preferable to use a material such as rubber having a high pMC value, that is, a material such as rubber having a high biomass ratio, in the rubber composition from the standpoint of environmental protection.

The rubber composition may contain a thermoplastic elastomer as an elastomer other than the rubber component.
Thermoplastic elastomers are copolymers (block copolymers) composed of hard segments that act as cross-linking points and soft segments that exhibit rubber elasticity, and are usually solid at room temperature (25° C.).

Examples of hard segments include polystyrene, polypropylene, polyester, polyamide, polyvinyl chloride, and polyurethane. Examples of soft segments include vinyl-polydiene, polyisoprene, polybutadiene, polyethylene, polychloroprene, poly-2,3-dimethylbutadiene, and the like. is mentioned. These may be one kind or two or more kinds.

The thermoplastic elastomer may be used alone or in combination of two or more. As commercially available products, products of Kuraray Co., Ltd., Asahi Kasei Co., Ltd., etc. can be used.
In addition, in this specification, the thermoplastic elastomer is not included in the rubber component.

The thermoplastic elastomer is preferably a thermoplastic elastomer having a styrene block (styrene-based thermoplastic elastomer).
Specific examples of styrene-based thermoplastic elastomers include styrene-vinylisoprene-styrene triblock copolymer (SIS), styrene-isobutylene diblock copolymer (SIB), styrene-butadiene-styrene triblock copolymer (SBS ), styrene-ethylene/butylene-styrene triblock copolymer (SEBS), styrene-ethylene/propylene-styrene triblock copolymer (SEPS), styrene-ethylene/ethylene/propylene-styrene triblock copolymer (SEEPS ), styrene-butadiene/butylene-styrene triblock copolymer (SBBS), and the like. These may be used individually by 1 type, and may use 2 or more types together. Among them, copolymers having styrene blocks at both ends are preferred, and styrene-ethylene/propylene-styrene triblock copolymers (SEPS) are more preferred.
The SEPS may be a hydrogenated SIS obtained by adding hydrogen to a styrene-vinylisoprene-styrene triblock copolymer (SIS).

The styrene content of the styrene-based thermoplastic elastomer is preferably 5% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass. 30% by mass or less, more preferably 30% by mass or less. Within the above range, the effect tends to be obtained more favorably.

The content of the thermoplastic elastomer is preferably 1 to 30 parts by mass with respect to 100 parts by mass of the rubber component.

The rubber composition contains silica.
Examples of silica include dry silica (anhydrous silicic acid) and wet silica (hydrated silicic acid), but wet silica is preferred because it contains many silanol groups. The raw material of silica may be water glass (sodium silicate) or a biomass material such as rice husks. Commercially available products of Evonik Degussa, Tosoh Silica, Solvay Japan, Tokuyama, etc. can be used. These may be used individually by 1 type, and may use 2 or more types together.

The average particle size of silica is preferably 24 nm or less, more preferably 17 nm or less, still more preferably 16 nm or less, particularly preferably 14 nm or less, and is preferably 6 nm or more, more preferably 9 nm or more, and still more preferably 12 nm or more. is. Within the above range, the effect tends to be obtained more favorably.

In this specification, transmission electron microscope (TEM) observation is used as a method for measuring the average particle size of silica. Specifically, the silica particles are photographed with a transmission electron microscope. In the case of a standard type, the average particle size from the center is taken as the particle size, and the average value of the particle sizes of 100 fine particles is taken as the average particle size.

The content of silica is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, still more preferably 65 parts by mass or more, and preferably 100 parts by mass or less, or more, relative to 100 parts by mass of the rubber component. It is preferably 80 parts by mass or less, more preferably 70 parts by mass or less. Within the above range, the effect tends to be obtained more favorably.

In the rubber composition, the silica content/SBR content is preferably 0.2 or more, more preferably 0.4 or more, still more preferably 0.6 or more, and preferably 3 or less and more It is preferably 2 or less, more preferably 1 or less. Within the above range, the effect tends to be obtained more favorably.
In this relationship, the content of silica is the content (unit: parts by mass) per 100 parts by mass of the rubber component, and the content of SBR is the content (unit: mass%) in 100% by mass of the rubber component. is.

In the rubber composition, the silica content/substantial vinyl content of SBR may be less than 2.0, but is preferably 1.9 or less, more preferably 1.8 or less, and still more preferably 1.7 or less. is preferably 0.7 or more, more preferably 1.1 or more, and still more preferably 1.3 or more. Within the above range, the effect tends to be obtained more favorably.
In this relationship, the content of silica is the content (unit: parts by mass) per 100 parts by mass of the rubber component, and the actual vinyl content of SBR is the content of vinyl bonds relative to 100% by mass of SBR (unit: mass % ).

The rubber composition may contain carbon black.
Examples of carbon black include, but are not limited to, N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. The raw material of carbon black may be a biomass material such as lignin or vegetable oil, or may be obtained by recycling tires. Further, the method for producing carbon black may be combustion such as a furnace method, or may be hydrothermal carbonization (HTC). Commercially available products include Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Corporation, Shin Nikka Carbon Co., Ltd., and Columbia Carbon Co., Ltd. can. These may be used alone or in combination of two or more.

The cetyltrimethylammonium bromide (CTAB) specific surface area of carbon black is preferably 90 m ² /g or more, more preferably 100 m ² /g or more, still more preferably 110 m ² /g or more, and preferably 160 m ² /g. Below, more preferably 140 m ² /g or less, still more preferably 120 m ² /g or less. Within the above range, the effect tends to be obtained more favorably.
The CTAB specific surface area of carbon black is a value measured according to JIS K6217-3:2001.

The content of carbon black is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, and preferably 30 parts by mass or less, with respect to 100 parts by mass of the rubber component. It is more preferably 20 parts by mass or less, still more preferably 10 parts by mass or less. Within the above range, the effect tends to be obtained more favorably.

The rubber composition may contain a silane coupling agent.
The silane coupling agent is not particularly limited, and examples thereof include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, 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-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3- Sulfides such as triethoxysilylpropyl methacrylate monosulfide, mercaptos such as 3-mercaptopropyltrimethoxysilane and 2-mercaptoethyltriethoxysilane, vinyls such as vinyltriethoxysilane and vinyltrimethoxysilane, and 3-aminopropyl Amino compounds such as triethoxysilane and 3-aminopropyltrimethoxysilane, glycidoxy compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, 3-nitropropyltrimethoxysilane, 3- Examples include nitro-based solvents such as nitropropyltriethoxysilane, and chloro-based solvents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Commercially available products such as Evonik Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., Dow Corning Toray Co., Ltd., etc. can be used. These may be used alone or in combination of two or more. Among them, mercapto-based compounds are preferred.

As the mercapto-based silane coupling agent, in addition to a compound having a mercapto group, a compound having a structure in which the mercapto group is protected by a protecting group (for example, a compound represented by the following formula (S1)) can also be used. .

（式中、Ｒ^１００１は－Ｃｌ、－Ｂｒ、－ＯＲ^１００６、－Ｏ（Ｏ＝）ＣＲ^１００６、－ＯＮ＝ＣＲ^１００６Ｒ^１００７、－ＮＲ^１００６Ｒ^１００７及び－（ＯＳｉＲ^１００６Ｒ^１００７）_ｈ（ＯＳｉＲ^１００６Ｒ^１００７Ｒ^１００８）から選択される一価の基（Ｒ^１００６、Ｒ^１００７及びＲ^１００８は同一でも異なっていても良く、各々水素原子又は炭素数１～１８の一価の炭化水素基であり、ｈは平均値が１～４である。）であり、Ｒ^１００２はＲ^１００１、水素原子又は炭素数１～１８の一価の炭化水素基、Ｒ^１００３は－［Ｏ（Ｒ^１００９Ｏ）_ｊ］－基（Ｒ^１００９は炭素数１～１８のアルキレン基、ｊは１～４の整数である。）、Ｒ^１００４は炭素数１～１８の二価の炭化水素基、Ｒ^１００５は炭素数１～１８の一価の炭化水素基を示し、ｘ、ｙ及びｚは、ｘ＋ｙ＋２ｚ＝３、０≦ｘ≦３、０≦ｙ≦２、０≦ｚ≦１の関係を満たす数である。）

（式中、ｖは０以上の整数、ｗは１以上の整数である。Ｒ^１１は水素、ハロゲン、分岐若しくは非分岐の炭素数１～３０のアルキル基、分岐若しくは非分岐の炭素数２～３０のアルケニル基、分岐若しくは非分岐の炭素数２～３０のアルキニル基、又は該アルキル基の末端の水素が水酸基若しくはカルボキシル基で置換されたものを示す。Ｒ^１２は分岐若しくは非分岐の炭素数１～３０のアルキレン基、分岐若しくは非分岐の炭素数２～３０のアルケニレン基、又は分岐若しくは非分岐の炭素数２～３０のアルキニレン基を示す。Ｒ^１１とＲ^１２とで環構造を形成してもよい。） Particularly suitable mercapto-based silane coupling agents include a silane coupling agent represented by the following formula (S1), or a combination of a bonding unit A represented by the following formula (I) and a bonding unit B represented by the following formula (II). silane coupling agents containing.

(wherein R ¹⁰⁰¹ is —Cl, —Br, —OR ¹⁰⁰⁶ , —O(O=)CR ¹⁰⁰⁶ , —ON=CR ¹⁰⁰⁶ R ¹⁰⁰⁷ , —NR ¹⁰⁰⁶ R ¹⁰⁰⁷ and —(OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ ) _h (OSiR ¹⁰⁰⁶ R ¹⁰⁰⁷ R ¹⁰⁰⁸ ) (R ¹⁰⁰⁶ , R ¹⁰⁰⁷ and R ¹⁰⁰⁸ may be the same or different, and each is a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms; , h has an average value of 1 to 4.), R ¹⁰⁰² is R ¹⁰⁰¹ , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, R ¹⁰⁰³ is —[O(R ¹⁰⁰⁹ O) _j ]-group (R ¹⁰⁰⁹ is an alkylene group having 1 to 18 carbon atoms, j is an integer of 1 to 4.), R ¹⁰⁰⁴ is a divalent hydrocarbon group having 1 to 18 carbon atoms, and R ¹⁰⁰⁵ is 1 carbon atom to 18 monovalent hydrocarbon groups, and x, y and z are numbers satisfying the relationships x+y+2z=3, 0≤x≤3, 0≤y≤2, 0≤z≤1.)

(Wherein, v is an integer of 0 or more, w is an integer of 1 or more, R ¹¹ is hydrogen, halogen, a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched C 2 to A 30 alkenyl group, a branched or unbranched alkynyl group having 2 to 30 carbon atoms, or an alkyl group in which the terminal hydrogen is substituted with a hydroxyl group or a carboxyl group, where R ¹² is a branched or unbranched carbon number represents an alkylene group having 1 to 30 carbon atoms, a branched or unbranched alkenylene group having 2 to 30 carbon atoms, or a branched or unbranched alkynylene group having 2 to 30 carbon atoms, wherein R ¹¹ and R ¹² form a ring structure; may be used.)

In formula (S1), R ¹⁰⁰⁵ , R ¹⁰⁰⁶ , R ¹⁰⁰⁷ and R ¹⁰⁰⁸ are each independently selected from linear, cyclic or branched alkyl, alkenyl, aryl and aralkyl groups having 1 to 18 carbon atoms. It is preferably a group selected from the group consisting of When R ¹⁰⁰² is a monovalent hydrocarbon group having 1 to 18 carbon atoms, it is selected from the group consisting of linear, cyclic or branched alkyl groups, alkenyl groups, aryl groups and aralkyl groups. It is preferably a group. R ¹⁰⁰⁹ is preferably a linear, cyclic or branched alkylene group, particularly preferably a linear one. R ¹⁰⁰⁴ is, for example, an alkylene group having 1 to 18 carbon atoms, an alkenylene group having 2 to 18 carbon atoms, a cycloalkylene group having 5 to 18 carbon atoms, a cycloalkylalkylene group having 6 to 18 carbon atoms, or an arylene group having 6 to 18 carbon atoms. and an aralkylene group having 7 to 18 carbon atoms. Alkylene groups and alkenylene groups may be linear or branched, and cycloalkylene groups, cycloalkylalkylene groups, arylene groups and aralkylene groups have functional groups such as lower alkyl groups on their rings. You may have R ¹⁰⁰⁴ is preferably an alkylene group having 1 to 6 carbon atoms, more preferably a linear alkylene group such as methylene, ethylene, trimethylene, tetramethylene, pentamethylene and hexamethylene.

Specific examples of R ¹⁰⁰² , R ¹⁰⁰⁵ , R ¹⁰⁰⁶ , R ¹⁰⁰⁷ and R ¹⁰⁰⁸ in formula (S1) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group and sec-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, cyclopentyl group, cyclohexyl group, vinyl group, propenyl group, allyl group, hexenyl group, octenyl group, cyclopentenyl group, cyclohexenyl group , phenyl group, tolyl group, xylyl group, naphthyl group, benzyl group, phenethyl group, naphthylmethyl group and the like.
Examples of R ¹⁰⁰⁹ in the formula (S1) include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, a hexylene group and the like as linear alkylene groups, and branched alkylene groups such as isopropylene group, isobutylene group, 2-methylpropylene group and the like.

Specific examples of the silane coupling agent represented by formula (S1) include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, 3- Lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexanoy Luthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthio Ethyltrimethoxysilane, 2-decanoylthioethyltrimethoxysilane, 2-lauroylthioethyltrimethoxysilane and the like can be mentioned. These may be used alone or in combination of two or more. Among them, 3-octanoylthiopropyltriethoxysilane is particularly preferred.

In the silane coupling agent containing the linking unit A represented by the formula (I) and the linking unit B represented by the formula (II), the content of the linking unit A is preferably 30 mol% or more, more preferably 50 mol. % or more, preferably 99 mol % or less, more preferably 90 mol % or less. The content of the binding unit B is preferably 1 mol% or more, more preferably 5 mol% or more, still more preferably 10 mol% or more, preferably 70 mol% or less, more preferably 65 mol% or less, More preferably, it is 55 mol % or less. Also, the total content of the binding units A and B is preferably 95 mol % or more, more preferably 98 mol % or more, and particularly preferably 100 mol %.
In addition, the content of the bonding units A and B is the amount including the case where the bonding units A and B are positioned at the terminal of the silane coupling agent. When the bonding units A and B are located at the ends of the silane coupling agent, the form is not particularly limited as long as they form units corresponding to the formulas (I) and (II) representing the bonding units A and B. .

Halogen for R ¹¹ in formulas (I) and (II) includes chlorine, bromine, and fluorine. Examples of the branched or unbranched alkyl group having 1 to 30 carbon atoms include a methyl group and an ethyl group. Examples of the branched or unbranched alkenyl group having 2 to 30 carbon atoms include a vinyl group and a 1-propenyl group. Examples of the branched or unbranched alkynyl group having 2 to 30 carbon atoms include ethynyl group and propynyl group.

Examples of the branched or unbranched alkylene group having 1 to 30 carbon atoms for R ¹² in formulas (I) and (II) include ethylene group and propylene group. Examples of the branched or unbranched alkenylene group having 2 to 30 carbon atoms include vinylene group and 1-propenylene group. Examples of the branched or unbranched alkynylene group having 2 to 30 carbon atoms include an ethynylene group and a propynylene group.

In a silane coupling agent containing a bonding unit A represented by formula (I) and a bonding unit B represented by formula (II), the number of repetitions (v) of bonding unit A and the repetition number (w) of bonding unit B The total number of repetitions (v+w) is preferably in the range of 3-300.

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 16 parts by mass or less with respect to 100 parts by mass of silica. , more preferably 14 parts by mass or less, and still more preferably 12 parts by mass or less. Within the above range, the effect tends to be obtained more favorably.

The rubber composition preferably contains aluminum hydroxide.
As used herein, aluminum _hydroxide means Al(OH) ₃ or _{Al2O3.3H2O .} As commercially available products, products of Sumitomo Chemical Co., Ltd., Showa Denko Co., Ltd., Nabaltec, etc. can be used. These may be used alone or in combination of two or more.

The average particle size of aluminum hydroxide is preferably 0.1 μm or more, more preferably 0.5 μm or more, still more preferably 0.8 μm or more, and is preferably 5 μm or less, more preferably 3 μm or less, and still more preferably It is 1 μm or less. Within the above range, the effect tends to be obtained more favorably.
In addition, the average particle size of aluminum hydroxide is a value measured by the same method as the average particle size of silica.

The BET specific surface area (nitrogen adsorption specific surface area, N ₂ SA) of aluminum hydroxide is preferably 5 m ² /g or more, more preferably 8 m ² /g or more, still more preferably 10 m ² /g or more, and preferably is 40 m ² /g or less, more preferably 30 m ² /g or less, still more preferably 20 m ² /g or less.
The BET specific surface area of aluminum hydroxide is a value measured by the BET method according to ASTM D3037-81.

The content of aluminum hydroxide is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, and preferably 20 parts by mass or less with respect to 100 parts by mass of the rubber component. , more preferably 15 parts by mass or less, and still more preferably 10 parts by mass or less. Within the above range, the effect tends to be obtained more favorably.

The rubber composition preferably contains water-soluble particles.
Water-soluble particles are not particularly limited as long as they are particles that are soluble in water. For example, a material having a solubility in water at normal temperature (20° C.) of 1 g/100 g water or more can be used.

Examples of water-soluble particles include water-soluble inorganic salts and water-soluble organic substances. Water-soluble inorganic salts include metal sulfates such as magnesium sulfate and potassium sulfate; metal chlorides such as potassium chloride and sodium chloride; metal hydroxides such as potassium hydroxide and sodium hydroxide; carbonates; phosphates such as sodium hydrogen phosphate and sodium dihydrogen phosphate; These may be used alone or in combination of two or more. Among them, water-soluble inorganic salts are preferred, metal sulfates are more preferred, and magnesium sulfate is even more preferred.

As commercially available water-soluble particles, products of Umai Kasei Kogyo Co., Ltd., Tokyo Kasei Kogyo Co., Ltd., and the like can be used.

The median particle size (median diameter, D50) of the water-soluble particles is preferably 1 µm or more, more preferably 2 µm or more, still more preferably 3 µm or more, and is preferably 800 µm or less, more preferably 500 µm or less, and still more preferably It is 300 μm or less. Within the above range, the effect tends to be obtained more favorably.
As used herein, the median particle size can be measured by a laser diffraction method.

The content of the water-soluble particles is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, and preferably 20 parts by mass or less with respect to 100 parts by mass of the rubber component. , more preferably 15 parts by mass or less, and still more preferably 10 parts by mass or less. Within the above range, the effect tends to be obtained more favorably.

The rubber composition preferably contains vulcanized rubber particles.
The vulcanized rubber particles are particles made of vulcanized rubber, and specifically, rubber powder or the like defined in JIS K 6316:2017 can be used. Recycled rubber powder produced from pulverized waste tires or the like is preferable from the viewpoint of environmental consideration and cost. These may be used individually by 1 type, and may use 2 or more types together.

As commercial products of vulcanized rubber particles, products of Lehigh, Muraoka Rubber Industry Co., Ltd., etc. can be used.

The average particle size of the vulcanized rubber particles is preferably 50 µm or more, more preferably 100 µm or more, still more preferably 200 µm or more, and is preferably 1000 µm or less, more preferably 900 µm or less, still more preferably 800 µm or less.
The average particle size of the vulcanized rubber particles is the mass-based average particle size calculated from the particle size distribution measured according to JIS Z 8815:1994.

The content of the vulcanized rubber particles is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, and preferably 30 parts by mass with respect to 100 parts by mass of the rubber component. Below, more preferably 20 parts by mass or less, still more preferably 10 parts by mass or less. Within the above range, the effect tends to be obtained more favorably.

The rubber composition may contain talc.
The average particle size of talc is preferably 50 μm or less, more preferably 30 μm or less. Although the lower limit of the average particle size of talc is not particularly limited, it is preferably 1 μm or more.

The content of talc is preferably 1 to 50 parts by mass with respect to 100 parts by mass of the rubber component.

The rubber composition may contain a calcium compound.
A calcium compound is a compound containing calcium, and examples thereof include inorganic salts such as calcium oxide, calcium hydroxide, and calcium carbide; and oxoacid salts such as calcium carbonate, calcium nitrate, and calcium sulfate. Oxoacid salts also include fatty acid salts such as calcium acetate and calcium stearate. Examples of products containing a calcium compound include eggshell (main component: calcium carbonate) and WB16 (mixture of fatty acid calcium, fatty acid amide and fatty acid amide ester) manufactured by Structol. These may be used individually by 1 type, and may use 2 or more types together. Of these, oxoacid salts are preferred, and calcium carbonate is more preferred.

The content of the calcium compound is preferably 1 to 30 parts by mass with respect to 100 parts by mass of the rubber component.

The rubber composition may contain short fibers.
As short fibers, for example, organic short fibers, inorganic short fibers, and the like can be used. Specific examples of organic short fibers include nanocelluloses such as cellulose nanofibers (CNF) and cellulose nanocrystals (CNC); chitin nanofibers; and biomass nanomaterials such as chitosan nanofibers. Examples thereof include metal fiber, glass fiber, and the like. Commercially available products include Nippon Paper Industries Co., Ltd., Sugino Machine Co., Ltd., and the like. These may be used individually by 1 type, and may be used in mixture of 2 or more types. Among them, organic short fibers are preferred, and nanocellulose is more preferred.

The particle size of nanocellulose is preferably 10 nm or more, more preferably 20 nm or more, still more preferably 25 nm or more, particularly preferably 28 nm or more, and is preferably 50 nm or less, more preferably 40 nm or less, and still more preferably 35 nm or less. , and particularly preferably 32 nm or less. Within the above range, the effect tends to be obtained more favorably.

The particle size of nanocellulose can be determined by image analysis using scanning electron micrographs, image analysis using transmission electron micrographs, image analysis using atomic force micrographs, analysis of X-ray scattering data, pore electric resistance method (Coulter It is the average fiber diameter measured by the principle method). In this specification, the average fiber diameter of nanocellulose (cellulose fibers) is typically the average fiber diameter of aggregates of cellulose fibers formed by aggregation of cellulose molecules.

The content of short fibers is preferably 1 to 40 parts by mass with respect to 100 parts by mass of the rubber component.

The rubber composition contains a resin component.
As the resin component, for example, a cyclopentadiene-based resin, an aromatic-based resin, a terpene-based resin, or the like can be used. Among them, aromatic resins are preferred. In addition, one resin component may be used alone, or two or more may be used in combination, but it is preferable to use two or more in combination, and an aromatic resin and a terpene resin may be used in combination. is more preferred.

A cyclopentadiene-based resin is a polymer containing a cyclopentadiene-based monomer as a constituent monomer. In addition to copolymers obtained by copolymerizing the above, copolymers of cyclopentadiene-based monomers and other monomers copolymerizable therewith can also be used.

Cyclopentadiene-based monomers include, for example, cyclopentadiene, dicyclopentadiene, tricyclopentadiene, and the like. These may be used individually by 1 type, and may use 2 or more types together. Among them, dicyclopentadiene is preferable.

Other monomers include, for example, C9 fractions such as vinyltoluene, indene and methylindene. These may be used individually by 1 type, and may use 2 or more types together.

From the viewpoint of better obtaining the effect, the cyclopentadiene-based resin is preferably a polymer (DCPD-based resin) containing dicyclopentadiene (DCPD) as a constituent monomer.

The content of the cyclopentadiene-based resin 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 15 parts by mass with respect to 100 parts by mass of the rubber component. Below, more preferably 10 parts by mass or less, still more preferably 5 parts by mass or less. Within the above range, the effect tends to be obtained more favorably.

Aromatic resin is a polymer containing an aromatic monomer as a constituent monomer, for example, a homopolymer obtained by polymerizing one aromatic monomer alone, two or more aromatic monomers In addition to copolymers obtained by copolymerizing the above, copolymers of aromatic monomers and other monomers copolymerizable therewith may also be used.

Examples of aromatic monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, Styrenic monomers such as o-chlorostyrene, m-chlorostyrene and p-chlorostyrene; Phenolic monomers such as phenol, alkylphenol and alkoxyphenol; Naphthol monomers such as naphthol, alkylnaphthol and alkoxynaphthol ; coumarone, indene, and the like. These may be used individually by 1 type, and may use 2 or more types together. Among them, styrene-based monomers are preferred, and styrene and α-methylstyrene are more preferred.

Other monomers include, for example, non-conjugated olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene and 1-octene. These may be used individually by 1 type, and may use 2 or more types together.

From the viewpoint of obtaining the effect better, the aromatic resin is preferably an α-methylstyrene resin (α-methylstyrene homopolymer, copolymer of styrene and α-methylstyrene, etc.), styrene α-methyl Styrene resin (a copolymer of styrene and α-methylstyrene) is more preferred.

The content of the aromatic resin is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, still more preferably 8 parts by mass or more, and preferably 20 parts by mass with respect to 100 parts by mass of the rubber component. Below, more preferably 15 parts by mass or less, still more preferably 10 parts by mass or less. Within the above range, the effect tends to be obtained more favorably.

A terpene-based resin is a polymer containing a terpene compound (terpene-based monomer) as a constituent monomer. Copolymers, as well as copolymers of terpene compounds and other monomers copolymerizable therewith, are also included.

Terpene compounds are hydrocarbons represented by the composition (C ₅ H ₈ ) _n and their oxygen-containing derivatives, such as monoterpene (C ₁₀ H ₁₆ ), sesquiterpene (C ₁₅ H ₂₄ ), diterpene (C ₂₀ H ₃₂ ), etc., and have a terpene as a basic skeleton. , 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol and the like. These may be used individually by 1 type, and may use 2 or more types together.

From the viewpoint of obtaining better effects, the terpene-based resin is preferably a copolymer of a terpene compound and an aromatic monomer, and more preferably a copolymer of a terpene compound and styrene (terpene-styrene resin).
In this specification, a polymer containing a terpene compound and an aromatic monomer as constituent monomers, such as a terpene styrene resin, is treated as a terpene resin rather than an aromatic resin.

The content of the terpene resin is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, still more preferably 8 parts by mass or more, and preferably 20 parts by mass or less with respect to 100 parts by mass of the rubber component. , more preferably 15 parts by mass or less, and still more preferably 10 parts by mass or less. Within the above range, the effect tends to be obtained more favorably.

The resin may be a modified resin into which functional groups have been introduced (functionalized resin).
The modified resin can be produced by a known method, for example, slurry method, metathesis method, or the like. Specifically, it can be produced, for example, by reacting a polymer, which is the polymer skeleton of the modified resin, with a functional compound capable of introducing a functional group by a known method.

The polymer that forms the polymer skeleton is not particularly limited, and may be, for example, the aforementioned cyclopentadiene-based resin, aromatic-based resin, terpene-based resin, or other resins. These may be used alone or in combination of two or more. Among them, aromatic resins are preferred, α-methylstyrene resins are more preferred, and styrene α-methylstyrene resins (copolymers of styrene and α-methylstyrene) are even more preferred.

The functional group is preferably a functional group containing at least one element selected from the group consisting of oxygen, silicon and nitrogen, more preferably a functional group containing silicon.

The content of the modified resin is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, still more preferably 8 parts by mass or more, and preferably 20 parts by mass or less, based on 100 parts by mass of the rubber component. It is more preferably 15 parts by mass or less, still more preferably 10 parts by mass or less. Within the above range, the effect tends to be obtained more favorably.

In the rubber composition, the content of the modified resin/total styrene content in the rubber component is preferably 0.1 or more, more preferably 0.2 or more, still more preferably 0.3 or more, and preferably It is 0.6 or less, more preferably 0.5 or less, and still more preferably 0.4 or less.
Within the above range, the effect tends to be obtained more favorably.
In this relationship, the content of the modified resin is the content (unit: parts by mass) per 100 parts by mass of the rubber component, and the total styrene content in the rubber component is the content in 100 mass% of the rubber component (unit: :% by mass).

Commercially available products of the above-mentioned resin component include, for example, Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical, Nichinuri Chemical ( Co., Ltd., Nippon Shokubai Co., Ltd., JXTG Energy Co., Ltd., Arakawa Chemical Co., Ltd., Taoka Chemical Co., Ltd., etc. can be used.

The content of the resin component is preferably 3 parts by mass or more, more preferably 8 parts by mass or more, still more preferably 16 parts by mass or more, and preferably 40 parts by mass or less, based on 100 parts by mass of the rubber component. It is more preferably 30 parts by mass or less, still more preferably 20 parts by mass or less. Within the above range, the effect tends to be obtained more favorably.

In the rubber composition, the ratio of silica content/resin component content is preferably 1 or more, more preferably 3 or more, still more preferably 4 or more, and is preferably 30 or less, more preferably 20 or less. More preferably less than 10. Within the above range, the effect tends to be obtained more favorably.
In this relationship, the content of the resin component and the content of silica are the contents (unit: parts by mass) per 100 parts by mass of the rubber component.

The rubber composition may contain oil.
Oils include, for example, process oils, vegetable oils, or mixtures thereof. As the process oil, for example, paraffinic process oil, aromatic process oil, naphthenic process oil, or the like can be used. Vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, Olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, tung oil and the like. Moreover, it may be a waste oil obtained by recovering vegetable oils and fats as edible oils. Commercial products include Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., JXTG Energy Co., Ltd., Orisoi, H&R, Toyokuni Oil Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., etc. products can be used. These may be used individually by 1 type, and may use 2 or more types together.

The content of the oil 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 40 parts by mass or less, and more preferably 40 parts by mass or less, with respect to 100 parts by mass of the rubber component. It is preferably 30 parts by mass or less, more preferably 20 parts by mass or less. Within the above range, the effect tends to be obtained more favorably.

The rubber composition may contain a liquid polymer.
The liquid polymer is a (co)polymer that is in a liquid state at normal temperature (25° C.). Specific examples include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), liquid styrene-isoprene copolymer (liquid SIR), liquid farnesene polymer, liquid farnesene butadiene copolymer, and the like. Further, the liquid polymer may be subjected to modification treatment or hydrogenation treatment. As commercially available products, products of Cray Valley, Kuraray Co., Ltd., etc. can be used. These may be used individually by 1 type, and may use 2 or more types together.

The weight average molecular weight (Mw) of the liquid polymer is preferably 9000 or less, more preferably 6000 or less, still more preferably 4500 or less, and is preferably 100 or more, more preferably 1000 or more, and still more preferably 2000 or more. . Within the above range, the effect tends to be obtained more favorably.
In this specification, the liquid polymer is not included in the rubber component.

The content of the liquid polymer is preferably 0.5 to 30 parts by mass with respect to 100 parts by mass of the rubber component.

The rubber composition may contain an ester plasticizer.
The ester plasticizer is not particularly limited as long as it is a compound having an ester group that is in a liquid state at room temperature (25° C.). derivatives and the like. These may be used alone or in combination of two or more. Among them, phosphoric acid derivatives, sebacic acid derivatives, and adipic acid derivatives are preferred, and sebacic acid derivatives are more preferred.
The phthalic acid derivative is not particularly limited, and examples thereof include phthalate esters such as di-2-ethylhexyl phthalate (DOP) and diisodecyl phthalate (DIDP). The long-chain fatty acid derivative is not particularly limited. , For example, long-chain fatty acid glycerol esters can be mentioned, and the phosphoric acid derivative is not particularly limited. , The sebacic acid derivative is not particularly limited, but examples thereof include sebacate esters such as di(2-ethylhexyl) sebacate (DOS) and diisooctyl sebacate (DIOS). Examples include, but are not limited to, adipates such as di(2-ethylhexyl)adipate (DOA) and diisooctyladipate (DIOA).
Among them, phosphate, sebacate and adipate are preferred, and sebacate is more preferred. Moreover, as a specific compound, TOP, DOS, and DOA are preferable, and DOS is more preferable.
As the ester plasticizer, for example, products of Daihachi Chemical Industry Co., Ltd., Taoka Chemical Industry Co., Ltd., etc. can be used.

The glass transition temperature (Tg) of the ester plasticizer is preferably −110° C. or higher, more preferably −100° C. or higher, still more preferably −80° C. or higher, preferably −20° C. or lower, more preferably −40. °C or below, more preferably -55°C or below. By setting it within the above range, there is a tendency that the above effect can be obtained more preferably.
In this specification, the glass transition temperature is measured according to JIS-K7121 using a differential scanning calorimeter (Q200) manufactured by TA Instruments Japan under the condition of a temperature increase rate of 10° C./min. It is a measured value.

The content of the ester plasticizer is preferably 1 to 20 parts by mass with respect to 100 parts by mass of the rubber component.

The rubber composition may contain processing aids.
Processing aids include metal salts (compounds in which hydrogen atoms of acids are substituted with metal ions), fatty acid amides, amide esters, fatty acid esters, and the like. These may be used alone or in combination of two or more. Among them, metal salts and fatty acid amides are preferred, and metal salts are more preferred.

Examples of metals used in metal salts include alkali metals such as potassium and sodium, alkaline earth metals such as calcium and barium, and the like. Magnesium, zinc, nickel, molybdenum, etc. can also be used. Among them, alkali metals and alkaline earth metals are preferred.

Acids used in metal salts include, for example, fatty acids such as lauric acid, myristic acid and palmitic acid. Boric acid, carbonic acid, hydrochloric acid, nitric acid, sulfuric acid, etc. can also be used.

As commercially available processing aids, products of Kishida Chemical Co., Ltd., Kenei Pharmaceutical Co., Ltd., Structol, Performance Additives, etc. can be used.

The content of the processing aid is preferably 1 to 15 parts by mass with respect to 100 parts by mass of the rubber component.

The rubber composition may contain an antioxidant.
Examples of anti-aging agents include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4′-bis(α,α′-dimethylbenzyl)diphenylamine; -Isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine, etc. p-phenylenediamine-based antioxidants; quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; 2,6-di-t-butyl-4-methylphenol, Monophenol anti-aging agents such as styrenated phenol; inhibitors and the like. As commercially available products, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Kagaku Kogyo Co., Ltd., Flexis, etc. can be used. These may be used individually by 1 type, and may use 2 or more types together.

The content of the anti-aging agent is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 4.5 parts by mass or more, and preferably 10 parts by mass with respect to 100 parts by mass of the rubber component. parts or less, more preferably 8 parts by mass or less, and even more preferably 6 parts by mass or less. Within the above range, the effect tends to be obtained more favorably.

The rubber composition may contain wax.
The wax is not particularly limited, and includes petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as plant waxes and animal waxes; synthetic waxes such as polymers of ethylene and propylene. As commercially available products, products of Ouchi Shinko Kagaku Kogyo Co., Ltd., Nippon Seiro Co., Ltd., Seiko Kagaku Co., Ltd., etc. can be used. These may be used individually by 1 type, and may use 2 or more types together.

The wax content 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, relative to 100 parts by mass of the rubber component. . Within the above range, the effect tends to be obtained more favorably.

The rubber composition may contain stearic acid.
As the stearic acid, conventionally known ones can be used, and commercially available products such as NOF Corporation, Kao Corporation, Fuji Film Wako Pure Chemical Industries, Ltd., Chiba Fatty Acids Co., Ltd. can be used. These may be used individually by 1 type, and may use 2 or more types together.

The stearic acid content 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, relative to 100 parts by mass of the rubber component. be. Within the above range, the effect tends to be obtained more favorably.

The rubber composition may contain zinc oxide.
As zinc oxide, conventionally known ones can be used, and commercially available products are available from Mitsui Kinzoku Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd. etc. products can be used. These may be used individually by 1 type, and may use 2 or more types together.

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, relative to 100 parts by mass of the rubber component. be. Within the above range, the effect tends to be obtained more favorably.

The rubber composition may contain sulfur.
Sulfur includes powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are generally used as cross-linking agents in the rubber industry. As commercially available products, products of Tsurumi Chemical Industry Co., Ltd., Karuizawa Io Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexis Co., Ltd., Nippon Kantan 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 0.5 parts by mass or more, more preferably 1 part by mass or more, still more preferably 1.4 parts by mass or more, and preferably 3.5 parts by mass or more, based on 100 parts by mass of the rubber component. It is 5 parts by mass or less, more preferably 2.8 parts by mass or less, and even more preferably 2.5 parts by mass or less. Within the above range, the effect tends to be obtained more favorably.

In the rubber composition, the ratio of zinc oxide/sulfur is preferably 0.2 or more, more preferably 0.8 or more, still more preferably 1.4 or more, and more preferably 5 or less, more preferably is 3 or less, more preferably 2 or less. Within the above range, the effect tends to be obtained more favorably.
In this relationship, the zinc oxide compounding amount and the sulfur compounding amount are contents (unit: parts by mass) per 100 parts by mass of the rubber component.

The rubber composition may contain an organic cross-linking agent.
Examples of the organic cross-linking agent include, but are not limited to, maleimide compounds, alkylphenol/sulfur chloride condensates, organic peroxides, and amine organic sulfides. These may be used alone or in combination of two or more.

The content of the organic cross-linking agent is preferably 1 to 15 parts by mass with respect to 100 parts by mass of the rubber component.

The rubber composition may contain a vulcanization accelerator.
Vulcanization accelerators include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole and di-2-benzothiazolyl disulfide; N) and other thiuram-based vulcanization accelerators; N-cyclohexyl-2-benzothiazylsulfenamide (CBS), N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-oxyethylene- Sulfenamide-based vulcanization accelerators such as 2-benzothiazolesulfenamide and N,N'-diisopropyl-2-benzothiazolesulfenamide; Sulfur accelerators may be mentioned. As commercially available products, products of Sumitomo Chemical Co., Ltd., Ouchi Shinko Kagaku Kogyo Co., Ltd., etc. 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 5 parts by mass or more, and preferably 10 parts by mass with respect to 100 parts by mass of the rubber component. Below, 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 obtained more favorably.

In addition to the above components, the rubber composition may further contain additives commonly used in the tire industry. The content of these additives is preferably 0.1 to 200 parts by mass with respect to 100 parts by mass of the rubber component.

The rubber composition may have a specific gravity of less than 1.180, preferably 1.170 or less, more preferably 1.150 or less, preferably 1 or more, more preferably 1.120 or more, and further Preferably it is 1.140 or more. Within the above range, the effect tends to be obtained more favorably.
The specific gravity of the rubber composition is measured by the method described in Examples below.

The rubber composition can be produced, for example, by kneading the above components using a rubber kneading device such as an open roll mixer or a Banbury mixer, followed by vulcanization.

As for the kneading conditions, the kneading temperature is usually 100 to 180°C, preferably 120 to 170°C in the base kneading step in which additives other than the vulcanizing agent and the vulcanization accelerator are kneaded. In the finishing 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. A composition obtained by kneading a vulcanizing agent and a vulcanization accelerator is usually subjected to vulcanization treatment such as press vulcanization. The vulcanization temperature is generally 140-190°C, preferably 150-185°C. Vulcanization time is usually 5 to 15 minutes.

Examples of the rubber composition include tread, sidewall, base tread, undertread, shoulder, clinch, bead apex, breaker cushion rubber, carcass cord covering rubber, insulation, chafer, inner liner, runflat It can be used for tire members such as tire side reinforcing layers (as a rubber composition for tires). Among others, it is suitable for the tread (in particular, the portion (cap tread) that comes into contact with the road surface during running).

A tire of the present disclosure is manufactured by a conventional method using the above rubber composition.
That is, the rubber composition is extruded according to the shape of the tread or the like in an unvulcanized stage, and molded together with other tire members on a tire molding machine by a conventional method to obtain an unvulcanized tire. to form A tire is obtained by heating and pressurizing this unvulcanized tire in a vulcanizer.

Tires for trucks and buses; tires for motorcycles; high-performance tires; winter tires such as studless tires; run-flat tires with side reinforcing layers; A tire with a sound absorbing member provided in the tire cavity; A tire with a sealing member provided with a sealant that can be sealed in the tire interior or in the tire cavity in the event of a puncture; Electronic parts such as sensors and wireless tags provided in the tire interior or the tire cavity It can be used for tires with electronic parts, etc., and is suitable for passenger car tires.

The size of the tire is not particularly limited. For example, the tire width can be selected within the range of 100 to 400 mm, the aspect ratio within the range of 25 to 85%, and the rim diameter within the range of 10 to 25 inches. is. Specific examples of /40R16, 225/40R17, 235/40R17, 245/40R16, 255/40R17, 265/40R17, 275/35R18, 285/30R19, 295/45R20 and the like.

なお、タイヤ外径（Ｄｔ）とは、タイヤを適用リムに装着して内圧２５０ｋＰａ・無負荷とした状態のタイヤの外径である。タイヤ断面幅（Ｗｔ）とは、タイヤを適用リムに装着して内圧２５０ｋＰａ・無負荷とした状態のタイヤ側面の模様又は文字など全てを含むサイドウォール間の直線距離、つまり総幅からタイヤの側面の模様、文字などを除いた幅である。 In the tire described above, the tire outer diameter Dt and the tire cross-sectional width Wt preferably satisfy the following relational expressions.

The tire outer diameter (Dt) is the outer diameter of the tire when the tire is mounted on an applicable rim and the internal pressure is 250 kPa with no load. The tire cross-sectional width (Wt) is the linear distance between the sidewalls including all patterns and letters on the tire side when the tire is mounted on the applicable rim and the internal pressure is 250 kPa and no load, that is, the total width to the tire side. This is the width excluding patterns, characters, etc.

Specific examples of tires that satisfy the above formula include 145/60R18, 145/60R19, 155/55R18, 155/55R19, 155/70R17, 155/70R19, 165/55R20, 165/55R21, 165/60R19, 165/65R19, 165/70R18, 175/55R19, 175/55R20, 175/55R22, 175/60R18, 185/55R19, 185/60R20, 195/50R20, 195/55R20 and the like.

A tire that satisfies the above formula is preferably applied to a pneumatic tire for a passenger car. This is because pneumatic tires for passenger cars that satisfy the above formula tend to be more suitable for solving the problems of this case.

The present disclosure will be specifically described based on Examples, but the present disclosure is not limited thereto.

Various chemicals used in Examples and Comparative Examples are described below.

(rubber component)
NR: TSR20
SBR1: Modified SBR synthesized in Production Example 1 below (styrene content: 25% by mass, vinyl content (ratio to 100% by mass of butadiene portion): 59% by mass)
SBR2: SLR6430 manufactured by TRINSEO (styrene content: 40% by mass, vinyl content (proportion to 100% by mass of butadiene portion): 24% by mass, oil content of 37.5 parts by mass per 100 parts by mass of rubber solid content)
SBR3: HPR850 manufactured by JSR Corporation (styrene content: 27.5% by mass, vinyl content (ratio to 100% by mass of butadiene portion): 59% by mass)
BR: BR1280 manufactured by LG Chem (vinyl content: 2% by mass, cis content: 96% by mass)

(Chemicals other than rubber components)
Carbon black: N220 (CTAB specific surface area: 111 m ² /g)
Silica 1: Ultrasil VN3 manufactured by Evonik Degussa (average particle size: 17 nm)
Silica 2: ZEOSIL PREMIUM 200MP manufactured by Solvay (average particle size: 14 nm)
Aluminum hydroxide: APYRAL 120E manufactured by Nabaltec (average particle size: 0.8 μm, BET specific surface area: 11 m ² /g)
Silane coupling agent 1: Si266 (bis (3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa
Silane coupling agent 2: NXT (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive
Vulcanized rubber particles: Ekodyne from Lehigh
Resin 1: Marukaretsu M-890A (cyclopentadiene resin) manufactured by Maruzen Petrochemical Co., Ltd.
Resin 2: YS resin TO125 manufactured by Yasuhara Chemical Co., Ltd. (terpene styrene resin (copolymer of styrene and terpene compound))
Resin 3: Modified styrene α-methylstyrene resin produced in Production Example 2 below Resin 4: Arizona Chemical Co. Sylvatraxx 4401 (styrene α-methylstyrene resin (a copolymer of styrene and α-methylstyrene))
Oil 1: A/O mixed oil manufactured by Sankyo Yuka Kogyo Co., Ltd. 2: PS-32 (mineral oil) manufactured by Idemitsu Kosan Co., Ltd.
Extension oil: Oil content in oil-extended rubber Magnesium sulfate: USN-00 manufactured by Umai Kasei Kogyo Co., Ltd. (ultrafine magnesium sulfate, median particle size (median diameter): 3 μm)
Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd.
Stearic acid: stearic acid "Tsubaki" manufactured by NOF Corporation
Antiaging agent 1: Nocrack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Antiaging agent 2: Nocrac RD (poly (2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Zinc oxide: Zinc white No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: HK-200-5 manufactured by Hosoi Chemical Industry Co., Ltd. (powder sulfur containing 5% by mass of oil)
Vulcanization accelerator 1: Noxceler CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
Vulcanization accelerator 2: Noxceler D (N,N'-diphenylguanidine) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.

(Production example 1)
A nitrogen purged 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 the 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 the mixture was further polymerized for 5 minutes, after which N-(3-dimethylaminopropyl)acrylamide was added as a modifier 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 with a hot roll adjusted to 110° C. to obtain SBR1.

(Production example 2)
Aluminum chloride and toluene were added to a glass flask that was replaced with an inert gas, and styrene and α-methylstyrene were added dropwise. Thereafter, an isoprene/toluene solution added with allyltriethoxysilane by a slurry method was added dropwise to the reaction liquid, and water was added to the reaction liquid to stop the reaction. After repeating the step of removing the aqueous layer by liquid separation, the organic layer obtained by liquid separation was air dried to volatilize toluene and dried under reduced pressure to obtain a modified styrene α-methylstyrene resin (resin 3).

(Examples and Comparative Examples)
According to the formulation shown in Tables 1 and 2, using a 1.7 L Banbury mixer manufactured by Kobe Steel, Ltd., materials other than sulfur and vulcanization accelerator were kneaded for 5 minutes at 150 ° C. and mixed. I got the paste. Next, sulfur and a vulcanization accelerator were added to the resulting kneaded material, and the mixture was kneaded at 80° C. for 5 minutes using an open roll to obtain an unvulcanized rubber composition. The resulting unvulcanized rubber composition was molded into a tread shape, laminated with other tire members to form an unvulcanized tire, press-vulcanized at 150 ° C. for 12 minutes, and a test tire ( Size: 175/60R18) was manufactured. The obtained test tires were used for the following evaluations, and the results are shown in Tables 1 and 2.

In Tables 1 and 2, the rubber content in the oil-extended rubber is listed in the rubber column, and the oil content in the oil-extended rubber is added to the extended oil column.

In addition, in the evaluation below, the evaluation criteria for calculating the index are as follows.
(Low fuel consumption during high-speed driving)
Table 1: Comparative Example 3
Table 2: Example 10 is Comparative Example 7, Example 11 is Comparative Example 8, and Example 12 is Comparative Example 9
(wear resistance)
Table 1: Comparative Example 2
Table 2: Example 10 is Comparative Example 7, Example 11 is Comparative Example 8, and Example 12 is Comparative Example 9

(specific gravity)
A test piece was cut out from the tread of the test tire, and the specific gravity was measured by a method according to JIS K 6268:1998 "Vulcanized rubber - Density measurement".

(Low fuel consumption during high-speed driving)
Using a rolling resistance tester, the rolling resistance was measured when each test tire was run at a speed of 100 km/h, and was expressed as an index based on the evaluation standard of 100. The larger the index, the smaller the rolling resistance and the better the fuel efficiency during high-speed running.

(wear resistance)
Each test tire was mounted on a vehicle, and the groove depth of the tread portion was measured after running 50,000 km. From the measured values, the wear amount of the tread portion was calculated and expressed as an index based on the evaluation standard of 100. A larger index indicates less wear and better wear resistance.

As can be seen from Tables 1 and 2, the examples were superior to the comparative examples in terms of overall performance (total of each index) of low fuel consumption during high-speed running and wear resistance.

The present disclosure (1) contains a rubber component containing a styrene-butadiene rubber, silica, and a resin component, the content of the styrene-butadiene rubber is more than 60% by mass in 100% by mass of the rubber component, and the styrene A rubber composition for a tire, wherein the butadiene rubber has a substantial vinyl content of more than 40% by mass, a specific gravity of less than 1.180, and wherein the silica content/substantial vinyl content of the styrene-butadiene rubber is <2.0. .

The present disclosure (2) is the rubber composition for tires according to the present disclosure (1), wherein the rubber component has a total styrene content of less than 25% by mass.

The present disclosure (3) is the rubber composition for tires according to the present disclosure (1) or (2), wherein the resin component contains an aromatic resin.

The present disclosure (4) is a rubber composition for tires, which is any combination with any one of the present disclosures (1) to (3), wherein the silica content/the resin component content <10.

(5) of the present disclosure is a rubber composition for tires in any combination with any one of (1) to (4) of the present disclosure, wherein the silica has an average particle size of 16 nm or less.

The present disclosure (6) is a tire in any combination with any one of the present disclosure (1) to (5), wherein the content of isoprene-based rubber is 10% by mass or more and less than 40% by mass in 100% by mass of the rubber component. It is a rubber composition for

(7) of the present disclosure is a rubber composition for tires which is any combination with any one of (1) to (6) of the present disclosure containing a mercapto-based silane coupling agent.

(8) of the present disclosure is a rubber composition for tires in any combination with any one of (1) to (7) of the present disclosure, wherein the resin component contains two or more resins.

The present disclosure (9) is a tire rubber composition in any combination with any of the present disclosures (1) to (8) containing aluminum hydroxide.

The present disclosure (10) is a rubber composition for tires in any combination with any one of the present disclosures (1) to (9), wherein the resin component contains a modified resin.

The present disclosure (11) is a rubber composition for tires in any combination with any of the present disclosures (1) to (10) containing water-soluble particles.

The present disclosure (12) is a rubber composition for tires in any combination with any of the present disclosures (1) to (11) containing vulcanized rubber particles.

The present disclosure (13) is a tire using a rubber composition of any combination of the present disclosure (1) to (12).

Claims (13)

containing a rubber component containing styrene-butadiene rubber, silica, and a resin component,
The content of the styrene-butadiene rubber is more than 60% by mass in 100% by mass of the rubber component,
The styrene-butadiene rubber has a substantial vinyl content of more than 40% by mass,
has a specific gravity of less than 1.180,
A rubber composition for tires wherein the content of silica/substantial vinyl content of the styrene-butadiene rubber<2.0. 2. The rubber composition for tires according to claim 1, wherein the total styrene content of said rubber component is less than 25% by mass. The rubber composition for tires according to claim 1 or 2, wherein the resin component contains an aromatic resin. The rubber composition for a tire according to any one of claims 1 to 3, wherein the content of silica/the content of resin component<10. The rubber composition for tires according to any one of claims 1 to 4, wherein the silica has an average particle size of 16 nm or less. The rubber composition for tires according to any one of claims 1 to 5, wherein the content of the isoprene-based rubber is 10% by mass or more and less than 40% by mass in 100% by mass of the rubber component. The rubber composition for tires according to any one of claims 1 to 6, which contains a mercapto-based silane coupling agent. The rubber composition for tires according to any one of claims 1 to 7, wherein the resin component contains two or more resins. The rubber composition for tires according to any one of claims 1 to 8, which contains aluminum hydroxide. The rubber composition for tires according to any one of claims 1 to 9, wherein the resin component contains a modified resin. The rubber composition for tires according to any one of claims 1 to 10, which contains water-soluble particles. The rubber composition for tires according to any one of claims 1 to 11, which contains vulcanized rubber particles. A tire using the rubber composition according to any one of claims 1 to 12.