Rubber composition for tires and tire

Abstract

To provide a rubber composition for tires capable of improving overall performance of fuel economy and turning performance on a wet road surface, and to provide a tire.SOLUTION: The present invention relates to the rubber composition for tires which contains a rubber component containing an isoprene rubber, a butadiene rubber, and a styrene-butadiene rubber. The following relationships are satisfied: (the content of the silica) / ((the content of the butadiene rubber)+(the content of the styrene-butadiene rubber))<1; and (the total styrene content in the rubber component)>(the content of the butadiene rubber).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a rubber composition for a tire and a tire. [Background technology]

[0002] Various methods for improving fuel economy and turning performance 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 fuel economy and turning performance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-344955 [Patent Document 2] Japanese Patent Publication No. 2022-021085 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a rubber composition for a tire and a tire that can solve the above problems and improve overall performance including fuel economy and cornering performance on wet road surfaces. [Means for solving the problem]

[0005] The present invention relates to a rubber composition for tires, which contains a rubber component including an isoprene-based rubber, a butadiene rubber, and a styrene-butadiene rubber, wherein the silica content / (the butadiene rubber content+the styrene-butadiene rubber content) is less than 1, and the total styrene amount in the rubber component is greater than the butadiene rubber content. [Effects of the Invention]

[0006] The present invention relates to a rubber composition for tires that contains a rubber component including an isoprene-based rubber, a butadiene rubber, and a styrene-butadiene rubber, and has a ratio of silica content / (the butadiene rubber content+the styrene-butadiene rubber content)<1, and a total styrene amount in the rubber component>the butadiene rubber content, so that the overall performance of fuel economy and cornering performance on wet roads is good. DETAILED DESCRIPTION OF THE INVENTION

[0007] The rubber composition for tires of the present disclosure contains a rubber component including an isoprene-based rubber, a butadiene rubber, and a styrene-butadiene rubber, and the silica content / (the butadiene rubber content+the styrene-butadiene rubber content) is < 1, and the total styrene amount in the rubber component is > the butadiene rubber content.

[0008] The reason why the above-mentioned effects can be obtained with the above rubber composition is presumed to be as follows. By ensuring that the total content of butadiene rubber and styrene butadiene rubber in the rubber component and the content of silica satisfy the above-mentioned relationship, it is possible to obtain good adhesion while reducing heat buildup. Furthermore, by making the total amount of styrene in the rubber component and the content of butadiene rubber satisfy the above-mentioned relationship, the above-mentioned effects can be more easily obtained. It is believed that the above effects improve the overall performance of fuel economy and cornering performance on wet roads.

[0009] 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.

[0010] The weight average molecular weight of the rubber component is preferably 50,000 or more, more preferably 150,000 or more, and even more preferably 200,000 or more, and is preferably 2,000,000 or less, more preferably 1,500,000 or less, and even more preferably 1,000,000 or less. Within the above ranges, the effect tends to be more favorably obtained.

[0011] In this specification, the weight average molecular weight (Mw) can be determined in terms of standard polystyrene based on measurements obtained using a gel permeation chromatograph (GPC) (GPC-8000 series, manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M, manufactured by Tosoh Corporation).

[0012] The total styrene content in the rubber component is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, and is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably less than 25% by mass. Within the above ranges, the effect tends to be more favorably obtained.

[0013] Here, the total amount of styrene in the rubber component is the total content (unit: mass%) of styrene moieties contained in the entire rubber component, and can be calculated by Σ (content of each rubber component × amount of styrene in each rubber component / 100). For example, if 100 mass% of the rubber component contains 85 mass% styrene-butadiene rubber with a styrene content of 40 mass%, 5 mass% styrene-butadiene rubber with a styrene content of 25 mass%, and 10 mass% butadiene rubber with a styrene content of 0 mass%, the total amount of styrene in the rubber component is 35.25 mass% (= 85 × 40 / 100 + 5 × 25 / 100 + 10 × 0 / 100).

[0014] The total vinyl content in the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 14% by mass or more, and is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0015] Here, the total vinyl amount in the rubber component is the total content (unit: parts by mass) of vinyl bonds in the butadiene parts of the styrene-butadiene rubber and butadiene rubber contained in the rubber component when the total mass of the rubber component is taken as 100, and can be calculated by Σ (content of each rubber component × proportion [mass %] of vinyl bond amount in the butadiene parts of each rubber component to the total mass of the rubber component). For example, in the case where 100 parts by mass of the rubber component contains 85 parts by mass of styrene-butadiene rubber with a styrene content of 40% by mass and a vinyl content of 30% by mass, 5 parts by mass of styrene-butadiene rubber with a styrene content of 20% by mass and a vinyl content of 20% by mass, and 10 parts by mass of butadiene rubber with a vinyl content of 10% by mass, the total vinyl content in the rubber component is 17.1 parts by mass (= 85 × (100 [% by mass] - 40 [% by mass]) × 30 [% by mass] + 5 × (100 [% by mass] - 20 [% by mass]) × 20 [% by mass] + 10 × 10 [% by mass]).

[0016] The styrene content and vinyl content in each rubber component can be measured by nuclear magnetic resonance (NMR) spectroscopy. In the examples of this specification, the total styrene amount and the total vinyl amount in the rubber component are calculated according to the above-mentioned formula, but they may also be analyzed from the tire using, for example, a pyrolysis gas chromatograph mass spectrometer (Py-GC / MS) or the like.

[0017] The rubber composition contains an isoprene-based rubber as a rubber component. Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. NRs such as SIR20, RSS#3, and TSR20 are commonly used in the tire industry. IRs are not particularly limited, and examples of IRs such as IR2200 are commonly used in the tire industry. Modified NRs include deproteinized natural rubber (DPNR) and highly purified natural rubber (UPNR). Modified NRs include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Modified IRs include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more. NR is preferred.

[0018] The isoprene rubber preferably includes a liquid isoprene rubber that is liquid at 25° C. Commercially available liquid isoprene rubbers include those manufactured by Kuraray Co., Ltd. Among these, liquid isoprene rubber (liquid IR) is preferred in order to obtain better effects.

[0019] The content of the 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, and even more preferably 15% by mass or more, and is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less. Within the above ranges, the effects tend to be more favorably obtained.

[0020] In the rubber composition, the ratio of the content of isoprene-based rubber to the total amount of styrene in the rubber component is preferably 0.2 or more, more preferably 0.5 or more, and even more preferably 0.7 or more, and is preferably 1.5 or less, more preferably 1.2 or less, and even more preferably 0.9 or less. Within the above ranges, the effect tends to be more favorably obtained. In this relationship, the content of isoprene-based rubber and the total amount of styrene in the rubber component are the contents (unit: mass %) in 100% by mass of the rubber component.

[0021] The rubber composition contains a butadiene rubber (BR) as a rubber component. The BR is not particularly limited, and can be one commonly used in the tire industry, such as BRs with a high cis content, such as BR1220 manufactured by Zeon Corporation, BR150B manufactured by Ube Industries, Ltd., and BR1280 manufactured by LG Chem; BRs containing 1,2-syndiotactic polybutadiene crystals (SPB), such as VCR412 and VCR617 manufactured by Ube Industries, Ltd.; and butadiene rubber synthesized using a rare earth catalyst (rare earth-based BR). These may be used alone or in combination of two or more. Of these, rare earth-based BRs are preferred.

[0022] As the rare earth element catalyst used in the synthesis of rare earth BR, known catalysts can be used, but lanthanum series rare earth element compounds are preferred, and neodymium-containing compounds (Nd-based catalysts) are more preferred.

[0023] The BR may be an oil-extended rubber, a resin-extended rubber, or an extended rubber with other softeners. These may be used alone or in combination of two or more. The amount of softener in these extended rubbers is not particularly limited, but is usually about 5 to 50 parts by mass per 100 parts by mass of rubber solids. The oil used in the oil-extended rubber and the resin used in the resin-extended rubber are the same as those described below. Other softeners include liquid polymers, which will be described later.

[0024] The BR may be modified to introduce a functional group that interacts with a filler such as silica. Examples of the functional group include a silicon-containing group (-SiR3 (R are the same or different and are hydrogen, a hydroxyl group, a hydrocarbon group, an alkoxy group, or the like), an amino group, an amido 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, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imido group, a hydrazo group, an azo group, a diazo group, a carboxy group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, an epoxy group, or the like. These functional groups may have a substituent. Of these, a silicon-containing group is preferred, and -SiR3 (R are the same or different and are hydrogen, a hydroxyl group, a hydrocarbon group (preferably a hydrocarbon group having 1 to 6 carbon atoms (more preferably an alkyl group having 1 to 6 carbon atoms)), or an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms)), and at least one R is a hydroxyl group) is more preferred.

[0025] Specific examples of compounds (modifiers) that introduce the above-mentioned functional groups include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane.

[0026] As BR, hydrogenated BR to which hydrogen has been added can also be used. When the BR is hydrogenated BR, the hydrogenation method and reaction conditions are not particularly limited, and hydrogenation may be carried out by a known method and under known conditions. Typically, hydrogenation is carried out at 20 to 150°C under a hydrogen pressure of 0.1 to 10 MPa in the presence of a hydrogenation catalyst. Other production methods and conditions are also not particularly limited, and the contents of, for example, WO 2016 / 039005 can be applied. Note that hydrogenated BR has the same structure as an ethylene-butadiene copolymer as a result of hydrogen being added to the butadiene moiety of BR. Therefore, in this specification, hydrogenated BR includes not only hydrogenated BR but also ethylene-butadiene copolymers.

[0027] The hydrogenation rate of the hydrogenated BR is preferably 65 mol% or more, more preferably 70 mol% or more, and even more preferably 80 mol% or more, and is preferably 95 mol% or less, more preferably 92 mol% or less, and even more preferably 90 mol% or less, based on 100 mol% of all butadiene units before hydrogenation. When the hydrogenation rate is within the above ranges, better effects tend to be obtained. The hydrogenation rate is 1 It can be calculated from the spectral reduction rate of the unsaturated bond portion of the spectrum obtained by measuring H-NMR.

[0028] The cis amount (cis content) of the BR is preferably 10% by mass or more, more preferably 25% by mass or more, and even more preferably 35% by mass or more, and is preferably 99% by mass or less, more preferably 90% by mass or less, and even more preferably 50% by mass or less. Within the above ranges, the effect tends to be more favorably obtained. The cis content of BR can be measured by infrared absorption spectroscopy.

[0029] The above-mentioned cis content of BR means the cis content of the BR when there is one type of BR, and means the average cis content when there are multiple types of BR. The average cis content of BR can be calculated by {Σ(content of each BR × cis content of each BR)} / total content of all BRs. For example, when 100% by mass of the rubber component contains 20% by mass of BR with a cis content of 90% by mass and 10% by mass of BR with a cis content of 40% by mass, the average cis content of BR is 73.3% by mass (=(20×90+10×40) / (20+10)).

[0030] In 100% by mass of the rubber component, the BR content is preferably 2% by mass or more, more preferably 6% by mass or more, and even more preferably 10% by mass or more, and is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less. Within the above ranges, the effects tend to be more favorably obtained.

[0031] In the above rubber composition, the total styrene content in the rubber component is greater than the BR content. The value of the total styrene content in the rubber component / the BR content is preferably 1.4 or more, more preferably 1.8 or more, and even more preferably 2.1 or more, and is preferably 3.5 or less, more preferably 3 or less, and even more preferably 2.5 or less. Within the above ranges, the effect tends to be more favorably obtained. In this relationship, the total amount of styrene in the rubber component and the content of BR are the contents (unit: mass %) in 100% by mass of the rubber component.

[0032] In the rubber composition, it is preferable that (content of isoprene-based rubber+content of BR) / total amount of styrene in the rubber component>1. In this case, the value of (isoprene rubber content + BR content) / total styrene content in the rubber component is preferably 1.05 or more, more preferably 1.1 or more, even more preferably 1.15 or more, and is preferably 1.5 or less, more preferably 1.3 or less, even more preferably 1.2 or less. When it is within the above range, the effect tends to be more favorable. In this relationship, the content of isoprene-based rubber, the content of BR, and the total amount of styrene in the rubber component are the contents (unit: mass %) in 100% by mass of the rubber component.

[0033] The rubber composition contains styrene-butadiene rubber (SBR) as a rubber component. The SBR is not particularly limited, and examples thereof include emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc. Commercially available products include those from Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, and Zeon Corporation. The SBR may be used alone or in combination of two or more types, but it is preferable to use two or more types in combination.

[0034] The styrene content of the SBR is preferably 15% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more, and is preferably 55% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0035] The vinyl content of the SBR is preferably 15% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more, and is preferably 60% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. When it is within the above range, the effect tends to be more favorable.

[0036] 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 amount of SBR can be calculated by {Σ(content of each SBR × styrene amount of each SBR)} / total content of all SBRs. For example, when 100% by mass of the rubber component contains 85% by mass of SBR with a styrene amount of 40% by mass and 5% by mass of SBR with a styrene amount of 25% by mass, the average styrene amount of the SBR is 39.2% by mass (=(85×40+5×25) / (85+5)).

[0037] The vinyl content of the above-mentioned SBR is the proportion of vinyl bonds (unit: mass%) when the total mass of the butadiene parts in the SBR is taken as 100, and is expressed as vinyl content [mass%] + cis content [mass%] + trans content [mass%] = 100 [mass%]. When there is one type of SBR, it means the vinyl content of that SBR, and when there are multiple types of SBR, it means the average vinyl content. The average vinyl content of the SBR can be calculated by Σ{content of each SBR × (100 [mass%] - styrene content of each SBR [mass%]) × vinyl content of each SBR [mass%]} / Σ{content of each SBR × (100 [mass%] - styrene content of each SBR [mass%])}. For example, in 100 parts by mass of the rubber component, 75 parts by mass of SBR with a styrene content of 40% by mass and a vinyl content of 30% by mass, 25 parts by mass of styrene, Vinyl content: In the case where 20% by mass of SBR is 15 parts by mass and the remaining 10 parts by mass is a component other than SBR, the average vinyl content of the SBR is 28% by mass (= {75 × (100 [% by mass] - 40 [% by mass]) × 30 [% by mass] + 15 × (100 [% by mass] - 25 [% by mass]) × 20 [% by mass])} / {75 × (100 [% by mass] - 40 [% by mass]) + 15 × (100 [% by mass] - 25 [% by mass])}.

[0038] The glass transition temperature (Tg) of SBR is preferably -10°C or lower, more preferably -20°C or lower, and preferably -80°C or higher, more preferably -65°C or higher. Within the above ranges, the effect tends to be more favorable. The glass transition temperature of SBR is a value measured in accordance with JIS-K7121 using a differential scanning calorimeter (Q200) manufactured by TA Instruments Japan at a heating rate of 10°C / min.

[0039] As SBR, hydrogenated SBR to which hydrogen has been added can also be used. When the SBR is hydrogenated SBR, the hydrogenation method and reaction conditions are not particularly limited, and hydrogenation may be performed by a known method and under known conditions. Typically, hydrogenation is performed at 20 to 150°C under a hydrogen pressure of 0.1 to 10 MPa in the presence of a hydrogenation catalyst. Other production methods and conditions are also not particularly limited, and the contents of the aforementioned International Publication No. 2016 / 039005 can be applied, for example. Hydrogenated SBR has the same structure as a copolymer of ethylene, butadiene, and styrene as a result of hydrogen being added to the butadiene portion of SBR. Therefore, in this specification, hydrogenated SBR includes not only hydrogenated products of copolymers of butadiene and styrene (SBR), but also copolymers of ethylene, butadiene, and styrene.

[0040] The hydrogenation rate of the hydrogenated SBR is preferably 65 mol% or more, more preferably 70 mol% or more, and even more preferably 80 mol% or more, and is preferably 95 mol% or less, more preferably 92 mol% or less, and even more preferably 90 mol% or less, based on 100 mol% of all butadiene units before hydrogenation. When the hydrogenation rate is within the above range, better effects tend to be obtained. The hydrogenation rate is 1 It can be calculated from the spectral reduction rate of the unsaturated bond portion of the spectrum obtained by measuring H-NMR.

[0041] The SBR may be an oil-extended rubber, a resin-extended rubber, or an extended rubber with other softeners. These may be used alone or in combination of two or more. The amount of softener in these extended rubbers is not particularly limited, but is usually about 5 to 50 parts by mass per 100 parts by mass of rubber solids. The oil used in the oil-extended rubber and the resin used in the resin-extended rubber are the same as those described below. Other softeners include liquid polymers, which will be described later.

[0042] SBR may be modified to introduce a functional group that interacts with fillers such as silica. Examples of the functional group include a silicon-containing group (-SiR3 (R are the same or different and are hydrogen, a hydroxyl group, a hydrocarbon group, an alkoxy group, or the like), an amino group, an amido 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, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imido group, a hydrazo group, an azo group, a diazo group, a carboxy group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, an epoxy group, or the like. These functional groups may have a substituent. Of these, a silicon-containing group is preferred, and -SiR3 (R are the same or different and are hydrogen, a hydroxyl group, a hydrocarbon group (preferably a hydrocarbon group having 1 to 6 carbon atoms (more preferably an alkyl group having 1 to 6 carbon atoms)), or an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms)), and at least one R is a hydroxyl group) is more preferred.

[0043] Specific examples of compounds (modifiers) that introduce the above-mentioned functional groups include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane.

[0044] The amount of SBR in 100% by mass of the rubber component is preferably 50% by mass or more, more preferably 65% ​​by mass or more, and even more preferably 75% by mass or more, and is preferably 95% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0045] In the rubber composition, the value of SBR content / (isoprene rubber content+BR content) is preferably at least 1, more preferably at least 2, and even more preferably at least 3, and is preferably at most 6, more preferably at most 5, and even more preferably at most 4. Within the above ranges, the effect tends to be better obtained. In this relationship, the SBR content, the isoprene-based rubber content, and the BR content are the contents (unit: mass %) in 100% by mass of the rubber component.

[0046] Examples of rubber components other than isoprene-based rubber, BR, and SBR include diene-based rubbers such as acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and styrene-isoprene-butadiene copolymer rubber (SIBR). These may be used alone or in combination of two or more.

[0047] The rubber components other than isoprene rubber, BR, and SBR may be oil-extended rubber, resin-extended rubber, or extended rubber with other softeners. These may be used alone or in combination of two or more. The amount of softener in these extended rubbers is not particularly limited, but is usually about 5 to 50 parts by mass per 100 parts by mass of rubber solids. The oil used in the oil-extended rubber and the resin used in the resin-extended rubber are the same as those described below. Other softeners include liquid polymers, which will be described later.

[0048] Rubber components other than isoprene-based rubber, BR, and SBR may be modified to introduce functional groups that interact with fillers such as silica. Examples of the functional group include a silicon-containing group (-SiR3 (R may be the same or different and is hydrogen, a hydroxyl group, a hydrocarbon group, an alkoxy group, or the like), an amino group, an amido 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, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imido group, a hydrazo group, an azo group, a diazo group, a carboxy group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, an epoxy group, or the like. These functional groups may have a substituent. Of these, a silicon-containing group is preferred, and -SiR3 (R may be the same or different and is hydrogen, a hydroxyl group, a hydrocarbon group (preferably a hydrocarbon group having 1 to 6 carbon atoms (more preferably an alkyl group having 1 to 6 carbon atoms)), or an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms)), and at least one R is a hydroxyl group) is more preferred.

[0049] Specific examples of compounds (modifiers) that introduce the above-mentioned functional groups include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane.

[0050] The raw materials (monomers) for synthetic rubbers such as IR, SBR, and BR may be derived from underground resources such as petroleum and natural gas, or may be recycled from rubber products such as tires or non-rubber products such as polystyrene. Monomers obtained by recycling (recycled monomers) are not particularly limited, and examples include recycled polyisoprene, recycled butadiene, and recycled aromatic vinyls. Examples of butadienes include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyls include, but are not limited to, styrene. Among these, recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) are preferably used as raw materials.

[0051] The method for producing the recycled monomer is not particularly limited, and examples thereof include synthesis from recycled naphtha obtained by decomposing rubber products such as tires. The method for producing recycled naphtha is also not particularly limited, and examples thereof include decomposing rubber products such as tires under high temperature and pressure, decomposing with microwaves, or mechanically crushing and then extracting.

[0052] Furthermore, the raw materials (monomers) of synthetic rubbers such as IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to materials derived from natural resources such as plants. Examples of biomass include, but are not limited to, agricultural, forestry, and fishery products, sugar, wood chips, plant residues after useful components have been extracted, plant-derived ethanol, and biomass naphtha.

[0053] Monomers derived from biomass (biomass monomers) are not particularly limited and include biomass-derived butadiene and biomass-derived aromatic vinyl. Examples of butadienes include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyls include, but are not limited to, styrene. The method for producing biomass monomers is not particularly limited and includes, for example, biological and / or chemical and / or physical conversion of animals and plants. A representative example of biological conversion is fermentation by microorganisms, and examples of chemical and / or physical conversion include catalytic conversion, high heat conversion, high pressure conversion, electromagnetic wave conversion, critical fluid conversion, and combinations thereof.

[0054] The polymer synthesized from a biomass monomer component (biomass polymer) is not particularly limited, and examples thereof include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl / butadiene copolymer synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0055] Whether the raw material for a polymer is derived from biomass can be determined by the pMC (percent modern carbon) measured in accordance with ASTM D6866-10.

[0056] pMC is the modern standard reference 14 of sample against C concentration 14 This is the ratio of C concentrations and is a value used as an index of the biomass ratio of a compound. The significance of this value is explained below. 1 mole of carbon atoms (6.02 × 10 23 ) contains approximately 6.02 × 10 atoms, which is about one trillionth of the number of ordinary carbon atoms. 11 pieces 14 C exists. 14C is called a radioactive isotope, and its half-life is 5,730 years, and it decreases regularly. It takes 226,000 years for all of it to decay. Therefore, in fossil fuels such as coal, oil, and natural gas, which are thought to have been absorbed and fixed by plants and other organisms more than 226,000 years ago, C was also included in these when it was first fixed. 14 All C elements have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas contain 14 Therefore, chemicals produced from these fossil fuels do not contain any C element. 14 It does not contain any C element.

[0057] on the other hand, 14 C is produced continuously by nuclear reactions in the atmosphere caused by cosmic rays, and this balances with the decrease due to radioactive decay. In the Earth's atmospheric environment, 14 Therefore, the amount of carbon derived from biomass resources currently circulating in the environment is constant. 14 As mentioned above, the C concentration is approximately 1 × 10 -12 The value is approximately mol %. Therefore, the biomass ratio of a certain compound can be calculated by using the difference between these values.

[0058] this 14 C is typically measured using accelerator mass spectrometry based on a tandem accelerator. 13 C concentration ( 13 C / 12 C). 14 C concentration ( 14 C / 12 C) is measured. 14 The modern standard reference for the C concentration is the carbon circulating in nature as of 1950. 14 The specific standard substance used is the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific activity of carbon in this oxalic acid (per gram of carbon) is14 The radioactivity of C is separated into carbon isotopes, 13 The standard value is the value corrected for decay from 1950 to the measurement date. 14 This is used as the C concentration value (100%). The ratio of this value to the value of the actually measured sample is the pMC value.

[0059] Therefore, if rubber is made from 100% biomass-derived materials, although there are regional differences, under normal circumstances, it will usually not reach 100, and will show a value of approximately 110 pMC. On the other hand, for chemical substances derived from petroleum and other fossil fuels, 14 When the carbon concentration is measured, it will show a value of about 0 pMC (for example, 0.3 pMC), which corresponds to the biomass ratio of 0% mentioned above.

[0060] From the above, it is preferable in terms of environmental protection 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 a rubber composition.

[0061] 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 crosslinking points and soft segments that exhibit rubber elasticity, and are usually solid at 25°C.

[0062] Examples of hard segments include polystyrene, polypropylene, polyester, polyamide, polyvinyl chloride, polyurethane, etc., and examples of soft segments include vinyl-polydiene, polyisoprene, polybutadiene, polyethylene, polychloroprene, poly2,3-dimethylbutadiene, etc. These may be used alone or in combination of two or more types.

[0063] The thermoplastic elastomer may be used alone or in combination of two or more kinds. Commercially available products available from Kuraray Co., Ltd., Asahi Kasei Corporation, etc. may be used. In this specification, the thermoplastic elastomer is not included in the rubber component.

[0064] The thermoplastic elastomer is preferably a thermoplastic elastomer having a styrene block (a 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), and styrene-butadiene-butylene-styrene triblock copolymer (SBBS). These may be used alone or in combination. Among these, styrene-ethylene-ethylene-propylene-styrene triblock copolymer (SEEPS) is more preferred.

[0065] The styrene content of the styrene-based thermoplastic elastomer is preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, and is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0066] The content of the thermoplastic elastomer is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. Within the above ranges, better effects tend to be obtained.

[0067] The rubber composition preferably contains vulcanized rubber particles as a filler. The vulcanized rubber particles are particles made of vulcanized rubber, and specifically, rubber powder as specified in JIS K 6316:2017 can be used. From the standpoint of environmental considerations and cost, recycled rubber powder produced from crushed waste tires is preferred. These may be used alone or in combination of two or more types. The vulcanized rubber particles are not particularly limited, and may be unmodified vulcanized rubber particles or modified vulcanized rubber particles.

[0068] Commercially available vulcanized rubber particles include products from Lehigh Corporation and Muraoka Rubber Industry Co., Ltd. In this specification, vulcanized rubber particles are not included in the rubber component.

[0069] The average particle size of the vulcanized rubber particles is preferably 50 μm or more, more preferably 100 μm or more, and even more preferably 200 μm or more, and is preferably 1000 μm or less, more preferably 900 μm or less, and even more preferably 800 μm or less. The average particle size of the vulcanized rubber particles is an average particle size on a mass basis calculated from the particle size distribution measured in accordance with JIS Z 8815:1994.

[0070] The content of the vulcanized rubber particles is preferably 2 parts by mass or more, more preferably 6 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. Within the above ranges, better effects tend to be obtained.

[0071] The rubber composition may contain silica as a filler. The silica is not particularly limited, and can be, for example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrated silica), or other silica commonly used in the tire industry. The raw material for silica is not particularly limited, and can be, for example, a mineral-derived raw material such as quartz, a biological raw material such as rice husk (for example, silica made from biomass materials such as rice husk), or silica recycled from silica-containing products. Among these, hydrated silica prepared by a wet method is preferred because it contains a large number of silanol groups. These silicas can be used alone or in combination of two or more types, but it is preferable to use two or more types in combination. Commercially available products include those from EVONIK, Tosoh Silica Corporation, Solvay Japan, and Tokuyama Corporation.

[0072] Silica made from biomass materials can be obtained, for example, by extracting silicate from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and then reacting the silicate with sulfuric acid in the same manner as conventional wet-process silica to produce a silicon dioxide precipitate, which is then filtered, washed with water, dried, and pulverized.

[0073] Silica recycled from silica-containing products can be, for example, silica recovered from products containing silica, such as electronic components such as semiconductors, tires, desiccants, and filtering materials such as diatomaceous earth. The recovery method is not particularly limited, and examples include thermal decomposition and decomposition by electromagnetic waves. Among these, silica recovered from electronic components such as semiconductors or tires is preferred.

[0074] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and duration, it is possible to suppress the crystallization of silica in rice husk ash (see, for example, JP 2009-2594 A and Akita Prefectural University Web Journal B / 2019, vol. 6, pp. 216-222).

[0075] Amorphous silica extracted from rice husks may be commercially available from Wilmar Co., Ltd., etc.

[0076] The average particle size of the silica is preferably 24 nm or less, more preferably 17 nm or less, even more preferably 16 nm or less, particularly preferably 15 nm or less, and is preferably 6 nm or more, more preferably 9 nm or more, even more preferably 12 nm or more. Within the above ranges, the effect tends to be more favorable.

[0077] In this specification, the average particle size of silica is measured by observation with a transmission electron microscope (TEM). Specifically, silica particles are photographed with a transmission electron microscope, and the particle size is the diameter of the sphere if the particle shape is spherical, the minor axis if the particle shape is needle-like or rod-like, or the average particle diameter from the center if the particle shape is irregular, and the average particle size of 100 fine particles is the average particle size.

[0078] The content of silica is preferably 30 parts by mass or more, more preferably 45 parts by mass or more, even more preferably 55 parts by mass or more, and is preferably 90 parts by mass or less, more preferably 75 parts by mass or less, even more preferably 65 parts by mass or less. When the content is within the above range, the effect tends to be better.

[0079] In the rubber composition, the silica content / (BR content+SBR content)<1. The value of silica content / (BR content+SBR content) is preferably 0.9 or less, more preferably 0.75 or less, and even more preferably 0.65 or less, and is preferably 0.3 or more, more preferably 0.5 or more, and even more preferably 0.6 or more. Within the above ranges, better effects tend to be obtained. In this relationship, the silica content is the content (unit: parts by mass) relative to 100 parts by mass of the rubber component, and the BR content and SBR content are the contents (unit: % by mass) in 100% by mass of the rubber component.

[0080] In the rubber composition, the value of the silica content / SBR content is preferably 0.5 or more, more preferably 0.6 or more, and even more preferably 0.7 or more, and is preferably 1 or less, more preferably 0.9 or less, and even more preferably 0.8 or less. When the ratio is within the above range, the effect tends to be better obtained. In this relationship, the silica content is the content (unit: parts by mass) relative to 100 parts by mass of the rubber component, and the SBR content is the content (unit: % by mass) in 100% by mass of the rubber component.

[0081] In the rubber composition, the value of the silica content / total styrene content in the rubber component is preferably 1.8 or more, more preferably 2.2 or more, even more preferably 2.5 or more, and is preferably 4 or less, more preferably 3.5 or less, even more preferably 3 or less. When it is within the above range, the effect tends to be more favorably obtained. In this relationship, the silica content is the content (unit: parts by mass) relative to 100 parts by mass of the rubber component, and the total styrene content is the content (unit: % by mass) in 100% by mass of the rubber component.

[0082] The rubber composition may contain carbon black as a filler. Carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. The raw material for carbon black may be a biomass material such as lignin or vegetable oil, or pyrolysis oil obtained by pyrolysis of waste tires. Carbon black may be produced by combustion, such as in a furnace process, by hydrothermal carbonization (HTC), or by pyrolysis of methane, such as in a thermal black process. Commercially available carbon black products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., and Columbia Carbon Co., Ltd. These carbon blacks may be used alone or in combination.

[0083] The cetyltrimethylammonium bromide (CTAB) specific surface area of ​​the carbon black is preferably 70 m 2 / g or more, more preferably 90m 2 / g or more, more preferably 110m 2 / g or more, and preferably 220m 2 / g or less, more preferably 190m 2 / g or less, more preferably 170m 2 / g or less. The CTAB specific surface area of ​​carbon black is a value measured in accordance with JIS K6217-3:2001.

[0084] The amount of carbon black is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above ranges, better effects tend to be obtained.

[0085] Fillers other than vulcanized rubber particles, silica, and carbon black include aluminum hydroxide, talc, calcium compounds, short fibers, etc. These may be used alone or in combination of two or more.

[0086] In this specification, aluminum hydroxide refers to Al(OH)3 or Al2O3·3H2O. Commercially available products include those from Sumitomo Chemical Co., Ltd., Showa Denko K.K., Nabaltec, etc. These may be used alone or in combination of two or more.

[0087] The average particle size of the aluminum hydroxide is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 0.8 μm or more, and is preferably 5 μm or less, more preferably 3 μm or less, and even more preferably 1 μm or less. Within the above ranges, better effects tend to be obtained. In this specification, the average particle size of aluminum hydroxide is measured by observation with a transmission electron microscope (TEM). Specifically, aluminum hydroxide particles are photographed with a transmission electron microscope, and the particle size is taken as the diameter of the sphere if the particles are spherical, the minor axis if the particles are needle-like or rod-like, or the average particle size from the center if the particles are irregular, and the average particle size of 100 fine particles is taken as the average particle size.

[0088] The BET specific surface area (nitrogen adsorption specific surface area, N2SA) of the aluminum hydroxide is preferably 5 m 2 / g or more, more preferably 8m 2 / g or more, more preferably 10m 2 / g or more, and preferably 40m 2 / g or less, more preferably 30m 2 / g or less, more preferably 20m 2 / g or less. The BET specific surface area of ​​aluminum hydroxide is a value measured by the BET method in accordance with ASTM D3037-81.

[0089] The content of aluminum hydroxide is preferably 1 to 30 parts by mass based on 100 parts by mass of the rubber component.

[0090] The average particle size of the talc is preferably 50 μm or less, more preferably 30 μm or less. There is no particular lower limit to the average particle size of the talc, but it is preferably 1 μm or more.

[0091] The content of talc is preferably 1 to 50 parts by mass based on 100 parts by mass of the rubber component.

[0092] The 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. Examples of calcium compounds include eggshells (main component: calcium carbonate). These may be used alone or in combination of two or more. Of these, oxoacid salts are preferred, and calcium carbonate is more preferred. In this specification, calcium fatty acid salts are treated as processing aids, which will be described later, and are not included in fillers.

[0093] The content of the calcium compound is preferably 1 to 30 parts by mass based on 100 parts by mass of the rubber component.

[0094] Examples of short fibers that can be used include organic short fibers and inorganic short fibers. Specific examples of organic short fibers include nanocelluloses such as cellulose nanofibers (CNF) and cellulose nanocrystals (CNC); biomass nanomaterials such as chitin nanofibers and chitosan nanofibers; and specific examples of inorganic short fibers include metal fibers and glass fibers. Commercially available products include those from Nippon Paper Industries Co., Ltd. and Sugino Machine Ltd. These may be used alone or in combination of two or more. Of these, organic short fibers are preferred, and nanocellulose is more preferred.

[0095] The particle size of nanocellulose is preferably 10 nm or more, more preferably 20 nm or more, even more preferably 25 nm or more, particularly preferably 28 nm or more, and preferably 50 nm or less, more preferably 40 nm or less, even more preferably 35 nm or less, particularly preferably 32 nm or less. Within the above range, the effect tends to be better.

[0096] The particle size of nanocellulose is the average fiber diameter measured by image analysis using scanning electron microscope photographs, transmission electron microscope photographs, atomic force microscope photographs, X-ray scattering data analysis, pore electrical resistance method (Coulter principle method), etc. In this specification, the average fiber diameter of nanocellulose (cellulose fiber) is typically the average fiber diameter of an aggregate of cellulose fibers formed by the aggregation of cellulose molecules.

[0097] The content of the short fibers is preferably 1 to 40 parts by mass based on 100 parts by mass of the rubber component.

[0098] The amount of the filler per 100 parts by mass of the rubber component is preferably 30 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 60 parts by mass or more, and is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and even more preferably 70 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0099] The rubber composition preferably contains a softener. A softener is a material that imparts plasticity to a rubber component, and the concept includes both softeners that are liquid at 25°C and softeners that are solid at 25°C. Examples of softeners include resins, oils, liquid polymers, and ester-based plasticizers. Of these, resins are preferred. These softeners may be derived from mineral resources such as petroleum or natural gas, biomass, or naphtha recycled from rubber or non-rubber products. Low-molecular-weight hydrocarbon components obtained by pyrolysis and extraction of used tires or products containing various components may also be used as softeners. These softeners may be used alone or in combination.

[0100] Examples of resins that can be used include C5 resins, C5 / C9 resins, coumarone-indene resins, aromatic resins, terpene resins, cyclopentadiene resins, and hydrogenated versions of these. These may be used alone or in combination of two or more, but it is preferable to use two or more. In this specification, the resin may be solid or liquid at 25°C.

[0101] C5 resins are polymers containing a C5 fraction as a constituent monomer, and examples thereof include homopolymers obtained by polymerizing one type of C5 fraction alone, copolymers obtained by copolymerizing two or more types of C5 fractions, and copolymers of a C5 fraction with other monomers that can be copolymerized with it. Examples of C5 fractions include olefinic hydrocarbons such as 1-pentene, 2-pentene, and 2-methyl-1-butene, and diolefinic hydrocarbons such as 2-methyl-1,3-butadiene, 1,2-pentadiene, and 1,3-pentadiene. These may be used alone or in combination of two or more. In this specification, a polymer containing a C5 fraction and an aromatic monomer (C9 fraction) as constituent monomers is referred to as a C5 / C9 resin.

[0102] The amount of the C5 resin is preferably at least 1 part by mass, more preferably at least 3 parts by mass, and even more preferably at least 5 parts by mass, per 100 parts by mass of the rubber component, and is preferably at most 25 parts by mass, more preferably at most 20 parts by mass, and even more preferably at most 15 parts by mass. Within the above ranges, better effects tend to be obtained.

[0103] C5 / C9 resins are polymers containing C5 and C9 fractions as constituent monomers, and examples thereof include polymers obtained by polymerizing petroleum-derived C5 and C9 fractions using a Friedel-Crafts catalyst such as AlCl3 or BF3. Specific examples include copolymers containing styrene, vinyltoluene, α-methylstyrene, indene, or the like as main components. In this specification, C5 / C9 resins are treated as resins separate from aromatic resins and C5 resins.

[0104] The amount of the C5 / C9 resin, relative to 100 parts by mass of the rubber component, is preferably at least 2 parts by mass, more preferably at least 8 parts by mass, and even more preferably at least 12 parts by mass, and is preferably at most 30 parts by mass, more preferably at most 25 parts by mass, and even more preferably at most 20 parts by mass. Within the above ranges, better effects tend to be obtained.

[0105] The coumarone-indene resin is a polymer containing coumarone and indene as constituent monomers, and examples thereof include copolymers of coumarone and indene, as well as copolymers of coumarone and indene with other monomers copolymerizable therewith.

[0106] The content of the coumarone-indene resin is preferably at least 1 part by mass, more preferably at least 3 parts by mass, and even more preferably at least 5 parts by mass, per 100 parts by mass of the rubber component, and is preferably at most 25 parts by mass, more preferably at most 20 parts by mass, and even more preferably at most 15 parts by mass. Within the above ranges, better effects tend to be obtained.

[0107] Aromatic resins are polymers containing aromatic monomers as constituent monomers, and examples thereof include homopolymers obtained by polymerizing one type of aromatic monomer alone, copolymers obtained by copolymerizing two or more types of aromatic monomers, and copolymers of an aromatic monomer and another monomer copolymerizable therewith.

[0108] Examples of aromatic monomers include styrene-based monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, and p-chlorostyrene; phenol-based monomers such as phenol, alkylphenol, and alkoxyphenol; naphthol-based monomers such as naphthol, alkylnaphthol, and alkoxynaphthol; coumarone, indene, and the like. These may be used alone or in combination of two or more. Among these, styrene-based monomers are preferred, and styrene and α-methylstyrene are more preferred.

[0109] Examples of other monomers include non-conjugated olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, etc. These may be used alone or in combination of two or more.

[0110] The aromatic resin is preferably an α-methylstyrene resin (such as an α-methylstyrene homopolymer or a copolymer of styrene and α-methylstyrene), and more preferably a styrene α-methylstyrene resin (a copolymer of styrene and α-methylstyrene).

[0111] The content of the aromatic resin is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0112] Terpene resins are polymers containing terpene compounds (terpene monomers) as constituent monomers, and include, for example, homopolymers obtained by polymerizing one type of terpene compound alone, copolymers obtained by copolymerizing two or more types of terpene compounds, and copolymers of a terpene compound and another monomer that can be copolymerized with it.

[0113] Terpene compounds are (C5H8) n The hydrocarbons and their oxygen-containing derivatives are represented by the following composition: monoterpenes (C 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 ), and examples thereof include α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol, etc. These may be used alone or in combination of two or more.

[0114] The terpene resin is preferably a homopolymer obtained by polymerizing one kind of terpene compound alone, or a copolymer of a terpene compound and an aromatic monomer. Furthermore, when the terpene resin is a homopolymer formed by polymerizing one type of terpene compound alone, β-pinene is preferred, and when the terpene resin is a copolymer of a terpene compound and an aromatic monomer, a copolymer of a terpene compound and styrene (terpene styrene resin) is preferred. 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, not an aromatic resin.

[0115] The amount of the terpene resin is preferably at least 1 part by mass, more preferably at least 5 parts by mass, and even more preferably at least 10 parts by mass, per 100 parts by mass of the rubber component, and is preferably at most 25 parts by mass, more preferably at most 20 parts by mass, and even more preferably at most 15 parts by mass. Within the above ranges, better effects tend to be obtained.

[0116] The cyclopentadiene-based resin is a polymer containing a cyclopentadiene-based monomer as a constituent monomer, and examples thereof include a homopolymer obtained by polymerizing one type of cyclopentadiene-based monomer alone, a copolymer obtained by copolymerizing two or more types of cyclopentadiene-based monomers, and a copolymer of a cyclopentadiene-based monomer and another monomer copolymerizable therewith.

[0117] Examples of cyclopentadiene-based monomers include cyclopentadiene, dicyclopentadiene, and tricyclopentadiene. These may be used alone or in combination of two or more. Among these, dicyclopentadiene is preferred. That is, the cyclopentadiene-based resin is preferably a polymer (DCPD-based resin) containing dicyclopentadiene (DCPD) as a constituent monomer, and more preferably a hydrogenated DCPD-based resin.

[0118] The amount of the cyclopentadiene resin is preferably at least 1 part by mass, more preferably at least 5 parts by mass, and even more preferably at least 10 parts by mass, per 100 parts by mass of the rubber component, and is preferably at most 25 parts by mass, more preferably at most 20 parts by mass, and even more preferably at most 15 parts by mass. Within the above ranges, the effect tends to be better obtained.

[0119] The resin is preferably a modified resin (functionalized resin) into which a functional group has been introduced. The modified resin can be produced by a known method, for example, by a slurry method, a metathesis method, etc. Specifically, for example, the modified resin can be produced by reacting a polymer that will become the polymer skeleton of the modified resin with a functional compound that can introduce a functional group, by a known method.

[0120] The polymer that forms the polymer backbone is not particularly limited, and may be, for example, the above-mentioned C5 resin, aromatic resin, terpene resin, or other resin. 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.

[0121] The functional group is preferably a functional group containing at least one element selected from the group consisting of oxygen, silicon, and nitrogen, and more preferably a functional group containing silicon.

[0122] The amount of the modified resin is preferably 2 parts by mass or more, more preferably 6 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0123] Commercially available resins include those manufactured by Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Co., Ltd.

[0124] The amount of the resin, relative to 100 parts by mass of the rubber component, is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, and is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0125] In the rubber composition, the value of the resin content / total styrene content in the rubber component is preferably 11.5 or less, more preferably 1 or less, and even more preferably 0.8 or less. There is no lower limit and it may be 0, but it is preferably 0.2 or more, more preferably 0.5 or more, and even more preferably 0.7 or more. Within the above range, the effect tends to be better obtained. In this relationship, the resin content is the content (unit: parts by mass) relative to 100 parts by mass of the rubber component, and the total styrene amount in the rubber component is the content (unit: % by mass) in 100% by mass of the rubber component.

[0126] The liquid polymer is a (co)polymer that is in a liquid state at 25° C., and examples thereof include liquid rubber and liquid resin. The liquid polymer may be modified or hydrogenated. Commercially available products include those from Cray Valley, Kuraray Co., Ltd., etc. These may be used alone or in combination of two or more.

[0127] The weight average molecular weight (Mw) of the liquid polymer is less than 10,000, preferably not more than 9,000, more preferably not more than 6,000, and even more preferably not more than 4,500, and is preferably not less than 100, more preferably not less than 1,000, and even more preferably not less than 2,000. Within the above ranges, better effects tend to be obtained. In this specification, the liquid polymer is not included in the rubber component.

[0128] As the liquid rubber, at least one diene-based (co)polymer selected from the group consisting of butadiene, isoprene, styrene, farnesene, and derivatives thereof can be used. Specific examples include liquid diene-based polymers such as 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, and liquid farnesene-butadiene copolymer.

[0129] The liquid rubber may be modified with a functional group that interacts with silica, or the terminals and / or the main chain may be modified with a functional group containing at least one element selected from the group consisting of oxygen, nitrogen, silicon, and phosphorus. The liquid rubber may be either non-hydrogenated or hydrogenated.

[0130] The content of the liquid rubber is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the rubber component. When the content is within the above range, better effects tend to be obtained.

[0131] The liquid resin is a resin that is liquid at 25° C., and the above-mentioned types of resins can be used. One type of liquid resin may be used alone, or two or more types of liquid resins may be used in combination.

[0132] The content of the liquid resin is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0133] The content of the liquid polymer is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0134] Examples of oils include mineral oil, vegetable oil, animal oil, etc. From the viewpoint of life cycle assessment, waste oils used in rubber mixers or engines, or refined waste cooking oils used in restaurants may also be used.

[0135] As used herein, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oil (mineral oil), naphthenic oil, and aromatic oil. Specific examples of mineral oil include mild extract solvated (MES), distillate aromatic extract (DAE), treated distillate aromatic extract (TDAE), treated residual aromatic extract (TRAE), and residual aromatic extract (RAE). Furthermore, as an environmental measure, oils with a low content of polycyclic aromatic compounds (PCA) can also be used. Examples of low PCA oils include MES, TDAE, and heavy naphthenic oil.

[0136] As used herein, examples of vegetable oils include linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grapeseed oil, and Japan wax. Further examples of vegetable oils include refined oils (such as salad oil) obtained by refining the above oils, interesterified oils obtained by interesterifying the above oils, hardened oils obtained by hydrogenating the above oils, thermally polymerized oils obtained by thermally polymerizing the above oils, oxidatively polymerized oils obtained by oxidizing the above oils, and waste edible oils recovered from edible oils and the like. Vegetable oils may be liquid or solid at 25°C. These may be used alone or in combination of two or more.

[0137] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxyl group of glycerin is esterified with a fatty acid. The acylglycerol is not particularly limited and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Furthermore, the acylglycerol may be a monomer, a dimer, or a polymer (trimer or higher). Dimer or higher acylglycerols can be obtained by thermal polymerization, oxidative polymerization, or the like. The acylglycerol may be liquid or solid at 25°C.

[0138] The method for confirming whether the rubber composition contains the acylglycerol is not particularly limited, but may be any of the following: 1 For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at 25°C for 24 hours, and after removing the rubber composition, the 1 When H-NMR was measured, signals were observed around 5.26 ppm, 4.28 ppm, and 4.15 ppm when the signal of tetramethylsilane (TMS) was set at 0.00 ppm. These signals are presumed to be signals derived from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atoms of the ester group. In this paragraph, "around" refers to a range of ±0.10 ppm.

[0139] The fatty acid is not particularly limited and may be either an unsaturated fatty acid or a saturated fatty acid. Examples of unsaturated fatty acids include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of saturated fatty acids include butyric acid and lauric acid.

[0140] Among these, it is desirable that the fatty acid contains a fatty acid with few double bonds, i.e., a saturated fatty acid or a monounsaturated fatty acid, and oleic acid is preferred. As a vegetable oil containing such a fatty acid, for example, vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid may be used, or vegetable oil modified by ester exchange or the like may be used. Furthermore, in order to produce vegetable oil containing such a fatty acid, plants may be improved by breeding, genetic modification, genome editing, or the like.

[0141] As the vegetable oil, for example, commercially available products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoi Co., Ltd., H&R Corporation, Toyokuni Oil Mills Co., Ltd., Fuji Kosan Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0142] The amount of the vegetable oil per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, and is preferably 25 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less. When the amount is within the above range, better effects tend to be obtained.

[0143] Commercially available oils that can be used include products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoi Co., Ltd., H&R Corporation, Toyokuni Oil Mills Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., Nisshin Oillio Group Co., Ltd., and the like.

[0144] The amount of oil per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, and is preferably 25 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above ranges, better effects tend to be obtained.

[0145] The ester plasticizer is not particularly limited as long as it is a compound having an ester group that is liquid at 25°C, and examples thereof include phthalic acid derivatives, long-chain fatty acid derivatives, phosphoric acid derivatives, sebacic acid derivatives, and adipic acid derivatives. These may be used alone or in combination of two or more. Among these, phosphoric acid derivatives, sebacic acid derivatives, and adipic acid derivatives are preferred, and sebacic acid derivatives are more preferred. The phthalic acid derivatives are not particularly limited, but examples thereof include phthalate esters such as di-2-ethylhexyl phthalate (DOP) and diisodecyl phthalate (DIDP). The long-chain fatty acid derivatives are not particularly limited, but examples thereof include long-chain fatty acid glycerin esters. The phosphoric acid derivatives are not particularly limited, but examples thereof include phosphoric acid esters such as tris(2-ethylhexyl)phosphate (TOP) and tributyl phosphate (TBP). The sebacic acid derivatives are not particularly limited, but examples thereof include sebacic acid esters such as di(2-ethylhexyl)sebacate (DOS) and diisooctylsebacate (DIOS). The adipic acid derivatives are not particularly limited, but examples thereof include adipic acid esters such as di(2-ethylhexyl)adipate (DOA) and diisooctyladipate (DIOA). Among these, phosphate ester, sebacate ester, and adipate ester are preferred, and sebacate ester is more preferred. Specific compounds are preferably TOP, DOS, and DOA, and more preferably DOS. As the ester-based plasticizer, for example, products manufactured by Daihachi Chemical Industry Co., Ltd., Taoka Chemical Industry Co., Ltd., etc. can be used.

[0146] The glass transition temperature (Tg) of the ester-based plasticizer is preferably −110° C. or higher, more preferably −100° C. or higher, even more preferably −80° C. or higher, and is preferably −20° C. or lower, more preferably −40° C. or lower, even more preferably −55° C. or lower. By keeping the Tg within the above range, the above-mentioned effects tend to be more suitably obtained. In this specification, the glass transition temperature of the ester-based plasticizer is a value measured in accordance with JIS-K7121 using a differential scanning calorimeter (Q200) manufactured by TA Instruments Japan at a heating rate of 10°C / min.

[0147] The content of the ester plasticizer is preferably 1 to 20 parts by mass based on 100 parts by mass of the rubber component.

[0148] The content of the softener, relative to 100 parts by mass of the rubber component, is preferably at least 5 parts by mass, more preferably at least 15 parts by mass, and even more preferably at least 20 parts by mass, and is preferably at most 50 parts by mass, more preferably at most 35 parts by mass, and even more preferably at most 25 parts by mass. Within the above ranges, the effect tends to be more favorably obtained.

[0149] In the rubber composition, the value of the softener content / filler content is preferably 0.15 or more, more preferably 0.2 or more, even more preferably 0.3 or more, and is preferably 0.6 or less, more preferably 0.45 or less, even more preferably 0.35 or less. Within the above ranges, the effect tends to be better. In this relationship, the contents of the softener and filler are the contents (unit: parts by mass) relative to 100 parts by mass of the rubber component.

[0150] 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, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl Examples include sulfide-based compounds such as propyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane and 2-mercaptoethyltriethoxysilane; vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Among these, mercapto-based compounds are preferred. Commercially available products that can be used include, for example, products from Degussa, Momentive, Shin-Etsu Silicones Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and Dow Corning Toray Co., Ltd. These may be used alone or in combination of two or more.

[0151] 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.

[0152] Particularly suitable mercapto-based silane coupling agents include silane coupling agents represented by the following formula (S1) and silane coupling agents containing a bonding unit A represented by the following formula (I) and a bonding unit B represented by the following formula (II). [ka] (In the formula, R 1001 -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 a monovalent group (R 1006 , R 1007 and R 1008 may be the same or different, and each represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and h has an average value of 1 to 4; 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, and j is an integer of 1 to 4. 1004 is a divalent hydrocarbon group having 1 to 18 carbon atoms, R 1005 represents a monovalent hydrocarbon group having 1 to 18 carbon atoms, and x, y, and z are numbers that satisfy the relationships: x+y+2z=3, 0≦x≦3, 0≦y≦2, 0≦z≦1. [ka] [ka] (wherein v is an integer of 0 or more, and w is an integer of 1 or more. R 11 R represents hydrogen, halogen, a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, a branched or unbranched alkynyl group having 2 to 30 carbon atoms, or an alkyl group in which the terminal hydrogen atom has been substituted with a hydroxyl group or a carboxyl group. 12 represents a branched or unbranched 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. 11 and R 12 may form a ring structure with

[0153] In formula (S1), R 1005 , R 1006 , R 1007 and R 1008 are each independently a group selected from the group consisting of a linear, cyclic or branched alkyl group, an alkenyl group, an aryl group and an aralkyl group having 1 to 18 carbon atoms. 1002 When R is a monovalent hydrocarbon group having 1 to 18 carbon atoms, it is preferably a group selected from the group consisting of a linear, cyclic, or branched alkyl group, an alkenyl group, an aryl group, and an aralkyl group. 1009 R is preferably a linear, cyclic or branched alkylene group, and is particularly preferably a linear one. 1004 Examples of R include alkylene groups having 1 to 18 carbon atoms, alkenylene groups having 2 to 18 carbon atoms, cycloalkylene groups having 5 to 18 carbon atoms, cycloalkylalkylene groups having 6 to 18 carbon atoms, arylene groups having 6 to 18 carbon atoms, and aralkylene groups having 7 to 18 carbon atoms. The alkylene groups and alkenylene groups may be either linear or branched, and the cycloalkylene groups, cycloalkylalkylene groups, arylene groups, and aralkylene groups may have a functional group such as a lower alkyl group on the ring. 1004As the alkylene group, an alkylene group having 1 to 6 carbon atoms is preferred, and a linear alkylene group such as a methylene group, ethylene group, trimethylene group, tetramethylene group, pentamethylene group, or hexamethylene group is particularly preferred.

[0154] R in formula (S1) 1002 , R 1005 , R 1006 , R 1007 and R 1008 Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a cyclopentyl group, a cyclohexyl group, a vinyl group, a propenyl group, an allyl group, a hexenyl group, an octenyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a benzyl group, a phenethyl group, and a naphthylmethyl group. R in formula (S1) 1009 Examples of the linear alkylene group include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, and a hexylene group, and examples of the branched alkylene group include an isopropylene group, an isobutylene group, and a 2-methylpropylene group.

[0155] 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-hexanoylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthioethyltrimethoxysilane, 2-decanoylthioethyltrimethoxysilane, and 2-lauroylthioethyltrimethoxysilane. These may be used alone or in combination of two or more. Among these, 3-octanoylthiopropyltriethoxysilane is particularly preferred.

[0156] In the silane coupling agent containing the bond unit A represented by formula (I) and the bond unit B represented by formula (II), the content of the bond unit A is preferably 30 mol% or more, more preferably 50 mol% or more, and preferably 99 mol% or less, more preferably 90 mol% or less. The content of the bond unit B is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 10 mol% or more, and preferably 70 mol% or less, more preferably 65 mol% or less, even more preferably 55 mol% or less. The total content of the bond units A and B is preferably 95 mol% or more, more preferably 98 mol% or more, particularly preferably 100 mol%. The content of the bonding units A and B includes the case where the bonding units A and B are located at the terminals of the silane coupling agent. When the bonding units A and B are located at the terminals of the silane coupling agent, the form of the bonding units A and B is not particularly limited, as long as they form units corresponding to the formulas (I) and (II) representing the bonding units A and B.

[0157] R in formulas (I) and (II)11 With respect to the above, examples of halogen include chlorine, bromine, and fluorine. Examples of branched or unbranched alkyl groups having 1 to 30 carbon atoms include methyl and ethyl groups. Examples of branched or unbranched alkenyl groups having 2 to 30 carbon atoms include vinyl and 1-propenyl groups. Examples of branched or unbranched alkynyl groups having 2 to 30 carbon atoms include ethynyl and propynyl groups.

[0158] R in formulas (I) and (II) 12 Regarding the above, examples of branched or unbranched alkylene groups having 1 to 30 carbon atoms include an ethylene group, a propylene group, etc. Examples of branched or unbranched alkenylene groups having 2 to 30 carbon atoms include a vinylene group, a 1-propenylene group, etc. Examples of branched or unbranched alkynylene groups having 2 to 30 carbon atoms include an ethynylene group, a propynylene group, etc.

[0159] In a silane coupling agent containing a bonding unit A represented by formula (I) and a bonding unit B represented by formula (II), the total number of repetitions (v+w) of the bonding unit A (v) and the bonding unit B (w) is preferably in the range of 3 to 300.

[0160] The content of the silane coupling agent is preferably 2 parts by mass or more, more preferably 6 parts by mass or more, and even more preferably 10 parts by mass or more, relative to 100 parts by mass of silica, and is preferably 20 parts by mass or less, more preferably 16 parts by mass or less, and even more preferably 14 parts by mass or less. Within the above range, the effect tends to be more favorable.

[0161] The rubber composition may contain a processing aid. Examples of processing aids include metal salts (compounds in which the hydrogen atoms of an acid are substituted with metal ions), fatty acid amides, amide esters, and fatty acid esters. These may be used alone or in combination of two or more. Of these, metal salts are preferred.

[0162] Examples of metals used in metal salts include alkali metals such as potassium and sodium, and alkaline earth metals such as calcium and barium. Magnesium, zinc, nickel, molybdenum, etc. can also be used. Of these, zinc is preferred.

[0163] Examples of acids used in metal salts include fatty acids such as lauric acid, myristic acid, and palmitic acid. Also usable are boric acid, carbonic acid, hydrochloric acid, nitric acid, and sulfuric acid. Of these, fatty acids are preferred.

[0164] As commercially available processing aids, products from Kishida Chemical Co., Ltd., Kenei Pharmaceutical Co., Ltd., Struktol Co., Ltd., Performance Additives Co., Ltd., etc. can be used.

[0165] The content of the processing aid is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 1.5 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0166] The rubber composition may contain an antioxidant. The antioxidant is not particularly limited, and examples thereof include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants 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 (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), and N,N'-ditolyl-p-phenylenediamine. p-phenylenediamine antioxidants such as N-isopropyl-N'-phenyl-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline antioxidants such as 2,2,4-trimethyl-1,2-dihydroquinoline polymers; monophenol antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, and polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. Commercially available products include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis, and the like. These may be used alone or in combination of two or more.

[0167] The content of the antioxidant is preferably at least 1 part by mass, more preferably at least 2.5 parts by mass, and even more preferably at least 3.5 parts by mass, per 100 parts by mass of the rubber component, and is preferably at most 15 parts by mass, more preferably at most 10 parts by mass, and even more preferably at most 6 parts by mass. Within the above ranges, the effect tends to be more favorably obtained.

[0168] The rubber composition may contain a wax. The wax is not particularly limited, and any wax commonly used in the tire industry can be suitably used. Examples include mineral waxes and plant-derived waxes. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Plant-derived waxes refer to waxes derived from natural resources such as plants. Among these, mineral waxes are preferred. Examples of plant-derived waxes include rice wax, carnauba wax, and candelilla wax. Examples of mineral waxes include paraffin wax, microcrystalline wax, and selected special waxes thereof, with paraffin wax being preferred. The wax according to this embodiment does not contain stearic acid. Waxes that can be used include those commercially available from, for example, Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., Ltd., etc. These waxes may be used alone or in combination of two or more. The wax is not particularly limited, and any wax commonly used in the tire industry can be suitably used. Examples include mineral waxes and plant-derived waxes. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Plant-derived waxes refer to waxes derived from natural resources such as plants. Among these, mineral waxes are preferred. Examples of plant-derived waxes include rice wax, carnauba wax, and candelilla wax. Examples of mineral waxes include paraffin wax, microcrystalline wax, and selected special waxes thereof, with paraffin wax being preferred. The wax according to this embodiment does not contain stearic acid. Waxes that can be used include those commercially available from, for example, Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., Ltd., etc. These waxes may be used alone or in combination of two or more.

[0169] The amount of wax per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and is preferably 8 parts by mass or less, more preferably 5 parts by mass or less. Within the above ranges, better effects tend to be obtained.

[0170] The rubber composition may contain stearic acid. As the stearic acid, conventionally known ones can be used, and commercially available products that can be used include products from NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc. These may be used alone or in combination of two or more.

[0171] The content of stearic acid is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, and preferably 8 parts by mass or less, more preferably 5 parts by mass or less, per 100 parts by mass of the rubber component. Within the above ranges, better effects tend to be obtained.

[0172] The rubber composition may contain zinc oxide. As the zinc oxide, conventionally known ones can be used, and commercially available products include those available from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. These may be used alone or in combination of two or more.

[0173] The content of zinc oxide is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, per 100 parts by mass of the rubber component. When the content is within the above range, better effects tend to be obtained.

[0174] 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 commonly used as crosslinking agents in the rubber industry. Commercially available products include those from Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanzuri Kogyo Co., Ltd., and Hosoi Chemical Industry Co., Ltd. These may be used alone or in combination of two or more.

[0175] The amount of sulfur per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.2 parts by mass or more, and even more preferably 1.8 parts by mass or more, and is preferably 8 parts by mass or less, more preferably 6 parts by mass or less, and even more preferably 4 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0176] The rubber composition preferably contains a dibenzylamine compound. The dibenzylamine compound is a compound having at least one group (dibenzylamine group) represented by the following formula: [ka]

[0177] Specific examples of dibenzylamine compounds include dibenzylamine, tetrabenzylthiuram disulfide (TBzTD), zinc dibenzyldithiocarbamate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, etc. Commercially available products include those from Sanshin Chemical Industry Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Lanxess, etc. These may be used alone or in combination of two or more. Of these, compounds having two dibenzylamine groups are preferred, and tetrabenzylthiuram disulfide is more preferred.

[0178] The content of the dibenzylamine compound is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 0.8 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0179] The rubber composition may contain a dialkyldithiophosphate compound. As the dialkyldithiophosphate compound, for example, a salt of dialkyldithiophosphate with a metal such as zinc or molybdenum can be used. Commercially available products include TP-50 manufactured by Rhein Chemie. These may be used alone or in combination of two or more. Of these, the compound represented by the following formula (1) (zinc dialkyldithiophosphate) is preferred. [ka] (In the formula, R 1 ~R 4 each independently represents a linear or branched alkyl group having 1 to 18 carbon atoms, or a cycloalkyl group having 5 to 12 carbon atoms.

[0180] In formula (1), R 1 ~R 4 Examples of the linear or branched alkyl group represented by R include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a 4-methylpentyl group, a 2-ethylhexyl group, an octyl group, and an octadecyl group, while examples of the cycloalkyl group include a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group. Among these, R is preferred because it is easily dispersed in the rubber composition and is easy to produce. 1 ~R 4 is preferably a linear or branched alkyl group having 2 to 8 carbon atoms, more preferably an n-butyl group, an n-propyl group, an isopropyl group or an n-octyl group, and even more preferably an n-butyl group.

[0181] The amount of the dialkyldithiophosphate compound is, per 100 parts by mass of the rubber component, preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more, and even more preferably 2 parts by mass or more, and is preferably 8 parts by mass or less, more preferably 6 parts by mass or less, and even more preferably 4 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0182] The rubber composition may contain a vulcanization accelerator. Examples of vulcanization accelerators include benzothiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole and di-2-benzothiazolyl disulfide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD) and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazyl sulfenamide (CBS), N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS), N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, di-orthotolylguanidine, and orthotolylbiguanidine. Commercially available products include those from Sumitomo Chemical Co., Ltd. and Ouchi Shinko Chemical Industry Co., Ltd. These may be used alone or in combination.

[0183] The content of the vulcanization accelerator is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 4.3 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0184] In addition to the above components, the rubber composition may further contain additives commonly used in the tire industry, such as organic peroxides, etc. The content of these additives is preferably 0.1 to 200 parts by mass per 100 parts by mass of the rubber component.

[0185] In this specification, various materials containing carbon atoms (e.g., rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from atmospheric carbon dioxide. As a method for obtaining the above-mentioned compound from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process in which methane is synthesized from carbon dioxide may be converted.

[0186] The rubber composition can be produced, for example, by kneading the above-mentioned components using a rubber kneading device such as an open roll or a Banbury mixer, followed by vulcanization.

[0187] As for kneading conditions, in the base kneading step in which additives other than the vulcanizing agent and vulcanization accelerator are kneaded, the kneading temperature is usually 100 to 180°C, preferably 120 to 170°C. In the finish kneading step in which the vulcanizing agent and vulcanization accelerator are kneaded, the kneading temperature is usually 120°C or lower, preferably 85 to 110°C. Furthermore, the composition kneaded with the vulcanizing agent and vulcanization accelerator 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.

[0188] The rubber composition can be used (as a rubber composition for tires) in tire components such as treads, sidewalls, undertreads, shoulders, clinches, bead apexes, breaker cushion rubbers, carcass cord covering rubbers, insulation, chafers, inner liners, and side reinforcing layers of run-flat tires. It is particularly suitable for treads. When the tread has a multi-layer structure, it can be used for either the surface layer (cap tread) or the inner layer (base tread), but is particularly suitable for cap treads.

[0189] The tire of the present disclosure is manufactured by a conventional method using the above rubber composition. That is, the rubber composition is extruded in an unvulcanized state to match the shape of the tread, etc., and molded together with other tire components in a tire building machine by a conventional method to form an unvulcanized tire. This unvulcanized tire is then heated and pressurized in a vulcanizer to obtain a tire.

[0190] The above-mentioned tires (pneumatic tires, etc.) can be used for passenger car tires; truck and bus tires; motorcycle tires; high-performance tires; winter tires such as studless tires; run-flat tires with side reinforcing layers; tires with sound-absorbing material that have sound-absorbing material such as sponge in the tire cavity; tires with sealing material that have a sealant inside the tire or in the tire cavity that can seal in the event of a puncture; and tires with electronic components that have electronic components such as sensors and wireless tags inside the tire or in the tire cavity, and are suitable for passenger car tires.

[0191] The size of the tire is not particularly limited, and can be appropriately selected, for example, from a tire width in the range of 100 to 400 mm, an aspect ratio in the range of 25 to 85%, and a rim diameter in the range of 10 to 25 inches. 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, and 295 / 45R20.

[0192] It is preferable that the tire outer diameter Dt and the tire section width Wt of the tire satisfy the following relational expression.

number

[0193] Specific examples of tires that can 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.

[0194] A tire that satisfies the above formula is preferably applied to a pneumatic tire for a passenger vehicle, because a pneumatic tire for a passenger vehicle that satisfies the above formula tends to be more suitable for solving the problem of the present invention. [Example]

[0195] Below, examples (embodiments) that are considered preferable for implementation will be shown, but the scope of the present invention is not limited to the examples.

[0196] The various chemicals used in the examples and comparative examples will be explained below.

[0197] (rubber component) NR:TSR20 Liquid IR: LIR-50 (liquid isoprene rubber, Mw: 54000) manufactured by Kuraray Co., Ltd. BR1: BR150B manufactured by Ube Industries, Ltd. (vinyl content: 1% by mass, cis content: 97% by mass) BR2: N103 manufactured by Asahi Kasei Chemicals Corporation (vinyl content: 12% by mass, cis content: 38% by mass) SBR1: Nipol-NS540 manufactured by Zeon Corporation (styrene content: 42% by mass, vinyl content: 29% by mass, Tg: -27°C, contains 25 parts by mass of oil per 100 parts by mass of rubber solids) SBR2: HPR850 manufactured by JSR Corporation (styrene content: 27.5% by mass, vinyl content: 59% by mass, Tg: -24°C) SBR3: Modified SBR synthesized in Production Example 1 below (styrene content: 25% by mass, vinyl content: 25% by mass, Tg: -50°C, Mw: 1,000,000)

[0198] (Chemicals other than rubber components) Carbon black: N220 (CTAB specific surface area: 111 m 2 / g) Vulcanized rubber particles: Lehigh's Ekodyne (rubber crumb) Silica 1: ZEOSIL 1115MP manufactured by Solvay (average particle size: 24 nm) Silica 2: Ultrasil VN3 manufactured by Evonik (average particle size: 17 nm) Silica 3: ULTRASIL 9100GR (average particle size: 15 nm) manufactured by Evonik Silane coupling agent 1: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa Silane coupling agent 2: NXT (3-octanoylthiopropyl) manufactured by Momentive Resin 1: Sylvatraxx 4401 (styrene α-methylstyrene resin (copolymer of styrene and α-methylstyrene)) manufactured by Arizona Chemical Company Resin 2: Petrotack 90 (C5 / C9 resin) manufactured by Tosoh Corporation Resin 3: Modified styrene α-methylstyrene resin (copolymer of styrene and α-methylstyrene) synthesized in Production Example 2 below Oil 1: H&R VIVATEC 500 (aromatic process oil) Oil 2: Sunflower oil (vegetable oil) manufactured by Nisshin Oillio Group Co., Ltd. Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd. Antioxidant 1: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Antioxidant 2: Nocrac RD (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Processing aid: ULTRA-FLOW 440 (fatty acid zinc salt) manufactured by Performance Additives Stearic acid: NOF Corporation's "Tsubaki" stearic acid Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: HK-200-5 (powdered sulfur containing 5% oil by mass) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Noccela NS (N-tert-butyl-2-benzothiazolyl sulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Noccelaer D (N,N'-diphenylguanidine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Dibenzylamine compound: Sancerer TBzTD (tetrabenzylthiuram disulfide) manufactured by Sanshin Chemical Industry Co., Ltd.

[0199] (Production Example 1) Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene are charged into a nitrogen-purged autoclave reactor. The temperature of the reactor contents is adjusted, and n-butyllithium is added to initiate polymerization. Polymerization is carried out under adiabatic conditions, and when the polymerization conversion rate reaches 99%, 1,3-butadiene is added and further polymerization is carried out. 3-dimethylaminopropyltriethoxysilane is added as a modifier to carry out the reaction. After the polymerization reaction is complete, 2,6-di-tert-butyl-p-cresol is added. The solvent is then removed by steam stripping, and the mixture is dried on a heated roll to obtain SBR3.

[0200] (Production Example 2) Aluminum chloride and toluene are added to a glass flask purged with an inert gas, and styrene and α-methylstyrene are added dropwise. The reaction mixture is then added dropwise to an isoprene / toluene solution to which allyltriethoxysilane has been added using the slurry method, and water is added to the reaction mixture to terminate the reaction. The process of removing the aqueous layer by separation is repeated, and the organic layer obtained by separation is dried with air to volatilize the toluene, and then dried under reduced pressure to obtain a modified styrene α-methylstyrene resin (Resin 3).

[0201] Examples and Comparative Examples According to the formulations shown in Tables 1 to 3, materials other than sulfur, vulcanization accelerator, and dibenzylamine compound are kneaded for 5 minutes at 150°C using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd. To the kneaded mixture, sulfur, vulcanization accelerator, and dibenzylamine compound are then added, and the mixture is kneaded for 5 minutes at 80°C using an open roll to obtain an unvulcanized rubber composition. Next, the unvulcanized rubber composition is molded into the shape of a cap tread, and is laminated together with other tire components to form an unvulcanized tire. The unvulcanized tire is press-vulcanized at 150°C for 12 minutes to produce a test tire (size: 175 / 60R18). The test tires manufactured in this manner were examined, and the results calculated based on the following evaluation methods are shown in Tables 1 to 3.

[0202] In Table 1, the rubber content in oil-extended rubber is listed in the rubber column, and the oil content in oil-extended rubber is added to the Oil 1 column. In Table 2, the rubber content in oil-extended rubber is listed in the rubber column, and the oil content in oil-extended rubber is added to the Oil 2 column.

[0203] In the evaluation methods below, the evaluation criteria for calculating the index are as follows: Table 1: Comparative Example 3 Table 2: Comparative Example 5 Table 3: Comparative Example 6

[0204] (low fuel consumption) Using a rolling resistance tester, the rolling resistance of each test tire is measured when it is run at 80 km / h, and the result is expressed as an index with the evaluation standard being 100. The higher the index, the lower the rolling resistance and the better the fuel economy.

[0205] (Turning performance on wet roads) Each test tire is mounted on a vehicle, and cornering performance is evaluated sensorily on a 5-point scale (maximum of 5 points) when driven on a test course in wet conditions. Evaluations are made by 20 test drivers, and the total score is expressed as an index, with the evaluation standard being 100. The higher the index, the better the cornering performance on wet roads.

[0206] [Table 1]

[0207] [Table 2]

[0208] [Table 3]

[0209] As can be seen from Tables 1 to 3, the Examples are superior to the Comparative Examples in overall performance (sum of indexes) of the targeted low fuel consumption and cornering performance on wet roads.

[0210] The present invention (1) comprises a rubber component including an isoprene-based rubber, a butadiene rubber, and a styrene-butadiene rubber, the silica content / (the butadiene rubber content+the styrene-butadiene rubber content)<1, The rubber composition for tires has a total styrene content in the rubber component that is greater than the content of the butadiene rubber.

[0211] The present invention (2) is a rubber composition for tires according to the present invention (1), which contains two or more types of the styrene-butadiene rubber.

[0212] The present invention (3) is a rubber composition for tires according to the present invention (1) or (2), which contains a resin.

[0213] The present invention (4) is a rubber composition for tires containing two or more resins in any combination with any of the present inventions (1) to (3).

[0214] The present invention (5) is a rubber composition for tires containing two or more types of silica in any combination with any of the present inventions (1) to (4).

[0215] The present invention (6) is a rubber composition for tires containing a mercapto-based silane coupling agent in any combination with any of the present inventions (1) to (5).

[0216] The present invention (7) is a rubber composition for tires in any combination with any of the present inventions (1) to (6), wherein the rubber component contains a liquid isoprene-based rubber.

[0217] The present invention (8) is a rubber composition for tires in any combination with any of the present inventions (1) to (7), wherein the total amount of styrene in the rubber component is less than 25% by mass.

[0218] The present invention (9) is a rubber composition for tires, which is any combination with any of the present inventions (1) to (8), in which (the content of the isoprene-based rubber + the content of the butadiene rubber) / the total amount of styrene in the rubber component>1.

[0219] The present invention (10) is a rubber composition for tires containing a dibenzylamine compound in any combination with any of the present inventions (1) to (9).

[0220] The present invention (11) is a rubber composition for tires containing silica having an average particle size of 16 nm or less, in any combination with any of the present inventions (1) to (10).

[0221] The present invention (12) is a rubber composition for tires containing vulcanized rubber particles in any combination with any of the present inventions (1) to (11).

[0222] The present invention (13) is a rubber composition for tires containing a modified resin in any combination with any of the present inventions (1) to (12).

[0223] The present invention (14) is a rubber composition for tires in any combination with any of the present inventions (1) to (13), wherein the value of the silica content / total styrene amount in the rubber component is 3 or less.

[0224] The present invention (15) is a tire using a rubber composition in any combination with any of the present inventions (1) to (14).

Claims

1. The rubber component contains isoprene rubber, butadiene rubber, and styrene-butadiene rubber, the silica content / (the butadiene rubber content+the styrene-butadiene rubber content)<1, A rubber composition for tires, wherein the total amount of styrene in the rubber component is greater than the content of the butadiene rubber.

2. 2. The rubber composition for tires according to claim 1, comprising two or more types of styrene-butadiene rubber.

3. The rubber composition for a tire according to claim 1 or 2, which contains a resin.

4. 3. The rubber composition for a tire according to claim 1, which contains two or more resins.

5. 3. The rubber composition for tires according to claim 1, which contains two or more types of silica.

6. 3. The rubber composition for tires according to claim 1, further comprising a mercapto-based silane coupling agent.

7. 3. The rubber composition for a tire according to claim 1, wherein the rubber component contains a liquid isoprene-based rubber.

8. 3. The rubber composition for a tire according to claim 1, wherein the total amount of styrene in the rubber component is less than 25% by mass.

9. 3. The rubber composition for tires according to claim 1, wherein (content of said isoprene-based rubber+content of said butadiene rubber) / total amount of styrene in said rubber component>1.

10. 3. The rubber composition for tires according to claim 1, which contains a dibenzylamine compound.

11. 3. The rubber composition for tires according to claim 1, which contains silica having an average particle size of 16 nm or less.

12. 3. The rubber composition for tires according to claim 1, which contains vulcanized rubber particles.

13. 3. The rubber composition for tires according to claim 1, which contains a modified resin.

14. 3. The rubber composition for tires according to claim 1, wherein the ratio of the silica content to the total styrene content in the rubber component is 3 or less.

15. A tire using the rubber composition according to claim 1 or 2.

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