Rubber composition for tire and tire

Abstract

To provide a rubber composition for a tire and a tire capable of enhancing chipping resistance.SOLUTION: The present invention relates to a rubber composition for a tire containing a rubber component including butadiene rubber and styrene-butadiene rubber, and silica, wherein the silica content is 100 pts.mass or less per 100 pts.mass of the rubber component, the carbon black content is less than or equal to the butadiene rubber content, the butadiene rubber content is less than or equal to the total styrene amount in the rubber component, and the silica has an average particle diameter of 16 nm or less.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Hitherto, various methods for improving chipping resistance performance have been studied (see, for example, Patent Document 1). However, in recent years, further improvement of chipping resistance performance has been demanded.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a rubber composition for tires and a tire that solve the above problems and can improve chipping resistance performance.

Means for Solving the Problems

[0005] The present invention relates to a rubber composition for tires containing a rubber component including butadiene rubber and styrene-butadiene rubber, and silica, wherein the content of the silica is 100 parts by mass or less with respect to 100 parts by mass of the rubber component, the content of carbon black ≦ the content of the butadiene rubber, the content of the butadiene rubber ≦ the total styrene amount in the rubber component, and the average particle diameter of the silica is 16 nm or less.

Effects of the Invention

[0006] The present invention relates to a rubber composition for tires containing a rubber component including butadiene rubber and styrene-butadiene rubber, and silica, wherein the content of the silica is 100 parts by mass or less with respect to 100 parts by mass of the rubber component, the content of carbon black ≦ the content of the butadiene rubber, the content of the butadiene rubber ≦ the total styrene amount in the rubber component, and the average particle diameter of the silica is 16 nm or less. Therefore, the chipping resistance performance is excellent.

Embodiments for Carrying Out the Invention

[0007] The rubber composition for tires of the present disclosure contains a rubber component including butadiene rubber and styrene-butadiene rubber, and silica, wherein the content of the silica is 100 parts by mass or less with respect to 100 parts by mass of the rubber component, the content of carbon black ≦ the content of the butadiene rubber, the content of the butadiene rubber ≦ the total styrene amount in the rubber component, and the average particle diameter of the silica is 16 nm or less.

[0008] The reason why the above-mentioned effects can be obtained with the above rubber composition is presumed as follows. By containing an isoprene-based rubber and styrene-butadiene rubber as the rubber component and setting the content of silica within the above range, the dispersibility of silica in the rubber component is enhanced, and the mechanical strength is improved. Furthermore, by setting the content of carbon black, the content of butadiene rubber, and the total styrene amount in the rubber component to the above relationships, and using silica with a small average particle diameter, the above-mentioned effects can be obtained more easily. Due to the above actions, it is considered that the chipping resistance performance is improved.

[0009] The above rubber composition contains a rubber component. Here, the rubber component is a component that contributes to crosslinking and has a weight average molecular weight (Mw) of 120,000 or more.

[0010] The weight average molecular weight of the rubber component is preferably 150,000 or more, more preferably 200,000 or more, still more preferably 250,000 or more, and is preferably 2.5 million or less, more preferably 2 million or less, still more preferably 1.5 million or less. When it is within the above range, the effect tends to be obtained more favorably.

[0011] In this specification, the weight average molecular weight (Mw) can be determined by standard polystyrene conversion based on the measured value by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation).

[0012] The total styrene amount in the rubber component is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, and is preferably 40% by mass or less, more preferably 30% by mass or less, still more preferably 25% by mass or less. When it is within the above range, the effect tends to be obtained more favorably.

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

[0014] The total vinyl amount in the rubber component is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, and is preferably 40% by mass or less, more preferably 30% by mass or less, still more preferably 25% by mass or less. When it is within the above range, the effect tends to be obtained more favorably.

[0015] Here, the total vinyl content in the rubber component is the total content (unit: parts by mass) of vinyl bonds in the butadiene portions of 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 × ratio [mass%] of the vinyl bond amount in the butadiene portion of the rubber component to the total mass of each rubber component). For example, in 100 parts by mass of the rubber component, 85 parts by mass of styrene-butadiene rubber with a styrene content of 40 mass% and a vinyl content of 30 mass%, 5 parts by mass of styrene-butadiene rubber with a styrene content of 20 mass% and a vinyl content of 20 mass%, and 10 parts by mass of butadiene rubber with a vinyl content of 10 mass%, the total vinyl content in the rubber component is 17.1 parts by mass (= 85 × (100 [mass%] - 40 [mass%]) × 30 [mass%] + 5 × (100 [mass%] - 20 [mass%]) × 20 [mass%] + 10 × 10 [mass%]).

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

[0017] The above rubber composition contains butadiene rubber (BR) as the rubber component. BR is not particularly limited. For example, high cis content BR such as BR1220 manufactured by Nippon Zeon Co., Ltd., BR150B manufactured by Ube Industries, Ltd., BR1280 manufactured by LG Chem; BR containing 1,2-syndiotactic polybutadiene crystal (SPB) such as VCR412, VCR617 manufactured by Ube Industries, Ltd.; butadiene rubber synthesized using a rare earth element-based catalyst (rare earth-based BR), etc., which are common in the tire industry can be used. These may be used alone or in combination of two or more. Among them, rare earth-based BR is preferred.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] The cis amount (cis content) of the BR is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more, and is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% 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.

[0025] 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)).

[0026] 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.

[0027] In the rubber composition, the BR content is equal to or less than the total styrene content in the rubber component. The value of the BR content / total styrene content in the rubber component is preferably 0.8 or less, more preferably 0.6 or less, and even more preferably 0.5 or less, and is preferably 0.2 or more, more preferably 0.3 or more, and even more preferably 0.4 or more. Within the above ranges, the effect tends to be more favorable. In this relationship, the BR content and the total styrene content in the rubber component are the contents (unit: mass %) in 100% by mass of the rubber component.

[0028] The rubber composition contains styrene-butadiene rubber (SBR) as a rubber component. The SBR is not particularly limited, and for example, emulsion polymerization styrene butadiene rubber (E-SBR), solution polymerization styrene butadiene rubber (S-SBR), etc. can be used. Examples of commercially available products include those from Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc. The SBR may be used alone or in combination of two or more, but it is preferable to use two or more in combination.

[0029] The styrene content of the SBR is preferably 15% by mass or more, more preferably 25% by mass or more, still more preferably 30% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass or less, still more preferably 40% by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0030] The vinyl content of the SBR is preferably 25% by mass or more, more preferably 35% by mass or more, still more preferably 45% by mass or more, and is preferably 70% by mass or less, more preferably 60% by mass or less, still more preferably 50% by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0031] In addition, the styrene content of the above-mentioned SBR 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. The average styrene content of the SBR can be calculated by {Σ(content of each SBR × styrene content of each SBR)} / total content of all SBRs. For example, when in 100% by mass of the rubber component, 85% by mass of the SBR has a styrene content of 40% by mass and 5% by mass of the SBR has a styrene content of 25% by mass, the average styrene content of the SBR is 39.2% by mass (=(85×40 + 5×25) / (85 + 5)).

[0032] 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])}.

[0033] The glass transition temperature (Tg) of SBR is preferably -10°C or lower, more preferably -30°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.

[0034] 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. Incidentally, as a result of adding hydrogen to the butadiene portion of SBR, hydrogenated SBR has the same structure as a copolymer of ethylene, butadiene, and styrene. Therefore, in the present specification, hydrogenated SBR is considered to include not only hydrogenated products of copolymers of butadiene and styrene (SBR), but also copolymers of ethylene, butadiene, and styrene.

[0035] The hydrogenation rate of hydrogenated SBR, with the total butadiene units before hydrogenation taken as 100 mol%, is preferably 65 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, and is preferably 95 mol% or less, more preferably 92 mol% or less, still more preferably 90 mol% or less. When within the above range, the effect tends to be obtained more favorably. Incidentally, the hydrogenation rate 1 can be calculated from the spectral reduction rate of the unsaturated bond portion of the spectrum obtained by measuring 1H-NMR.

[0036] SBR may be oil-extended rubber extended with oil, resin-extended rubber extended with resin, or extended rubber extended with other softening agents. These may be used alone or in combination of two or more. The softening agent content in these extended rubbers is not particularly limited, but is usually about 5 to 50 parts by mass with respect to 100 parts by mass of the rubber solid content. Incidentally, the oil used for oil-extended rubber and the resin used for resin-extended rubber are the same as those described later. Further, examples of other softening agents include liquid polymers described later.

[0037] SBR may have functional groups introduced therein by modification to interact 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.

[0038] 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.

[0039] The amount of SBR in 100% by mass of the rubber component is preferably 40% by mass or more, more preferably 55% by mass or more, and even more preferably 65% by mass or more, and is preferably 85% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0040] In the above rubber composition, the value of the content of SBR / the content of BR is preferably 3 or more, more preferably 5 or more, still more preferably 7 or more, and is preferably 10 or less, more preferably 9 or less, still more preferably 8 or less. When it is within the above range, the effect tends to be obtained more favorably. In this relationship, the content of SBR and the content of BR are the contents (unit: mass%) in 100 mass% of the rubber component.

[0041] The above rubber composition preferably contains an isoprene rubber as a rubber component. Examples of the isoprene rubber include natural rubber (NR), isoprene rubber (IR), modified NR, denatured NR, denatured IR, etc. As NR, for example, those generally used in the tire industry such as SIR20, RSS#3, TSR20, etc. can be used. IR is not particularly limited, and for example, those generally used in the tire industry such as IR2200, etc. can be used. Examples of modified NR include deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc., examples of denatured NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc., and examples of denatured IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, etc. These may be used alone or in combination of two or more. Among them, NR is preferred.

[0042] In 100 mass% of the rubber component, the content of the isoprene rubber is preferably 10 mass% or more, more preferably 20 mass% or more, still more preferably 25 mass% or more, and is preferably 45 mass% or less, more preferably 35 mass% or less, still more preferably 30 mass% or less. When it is within the above range, the effect tends to be obtained more favorably.

[0043] In the above rubber composition, it is preferable that the content of the isoprene rubber > the total styrene amount in the rubber component. In this case, the value of the content of isoprene-based rubber / the total amount of styrene in the rubber component is preferably 1.05 or more, more preferably 1.15 or more, and even more preferably 1.2 or more, and is preferably 2.5 or less, more preferably 2 or less, and even more preferably 1.5 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 and the total amount of styrene in the rubber component are the contents (unit: mass %) in 100% by mass of the rubber component.

[0044] In the rubber composition, the value of (isoprene rubber content + BR content) / SBR content is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.25 or more, still more preferably 0.4 or more, particularly preferably 0.5 or more, and is preferably 4 or less, more preferably 2 or less, even more preferably 1 or less, still more preferably 0.8 or less, particularly preferably 0.6 or less. When it is within the above range, the effect tends to be better obtained. In this relationship, the content of isoprene-based rubber, the content of BR, and the content of SBR are the contents (unit: mass %) in 100% by mass of the rubber component.

[0045] 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.

[0046] 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 softening agent content in these extended rubbers is not particularly limited, but is usually about 5 to 50 parts by mass with respect to 100 parts by mass of the rubber solid content. Note that the oil used in oil-extended rubber and the resin used in resin-extended rubber are the same as those described later. Further, examples of other softening agents include the liquid polymers described later.

[0047] Rubber components other than isoprene-based rubber, BR, and SBR may have functional groups introduced therein that interact with fillers such as silica by modification. Examples of the above functional groups include silicon-containing groups (-SiR3, where R is the same or different and is hydrogen, a hydroxyl group, a hydrocarbon group, an alkoxy group, etc.), amino groups, amide groups, isocyanate groups, imino groups, imidazole groups, urea groups, ether groups, carbonyl groups, oxycarbonyl groups, mercapto groups, sulfide groups, disulfide groups, sulfonyl groups, sulfinyl groups, thiocarbonyl groups, ammonium groups, imide groups, hydrazo groups, azo groups, diazo groups, carboxy groups, nitrile groups, pyridyl groups, alkoxy groups, hydroxyl groups, oxy groups, epoxy groups, etc. Note that these functional groups may have substituents. Among them, silicon-containing groups are preferred, and -SiR3 (where R is 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 of R is a hydroxyl group) is more preferred.

[0048] Specific examples of the compound (modifying agent) for introducing the above functional groups include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane, etc.

[0049] 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 and non-rubber products such as polystyrene. The monomers obtained by recycling (recycled monomers) are not particularly limited, and examples include recycled polyisoprene, recycled butadiene, and recycled aromatic vinyl. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl is not particularly limited, and examples include styrene. Among them, it is preferable to use recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) as raw materials.

[0050] The method for producing recycled monomers is not particularly limited. For example, it can be synthesized from recycled naphtha obtained by decomposing rubber products such as tires. Also, the method for producing recycled naphtha is not particularly limited. For example, rubber products such as tires may be decomposed under high temperature and high pressure, decomposed by microwaves, or extracted after mechanical pulverization.

[0051] Furthermore, the raw materials (monomers) for synthetic rubbers such as IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to substances derived from natural resources such as plants. Biomass is not particularly limited, and examples include agricultural and forestry products, sugars, wood chips, plant residues after obtaining useful components, ethanol derived from plants, biomass naphtha, and the like.

[0052] The biomass-derived monomers (biomass monomers) are not particularly limited, and examples include biomass-derived butadiene and biomass-derived aromatic vinyls. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl is not particularly limited, and examples thereof include styrene. The method for producing the biomass monomer is not particularly limited, and examples include those by biological and / or chemical and / or physical conversion of animals and plants. Fermentation by microorganisms is typical as the biological conversion, and examples of the chemical and / or physical conversion include those by a catalyst, high heat, high pressure, electromagnetic waves, a critical liquid, and combinations thereof.

[0053] The polymers synthesized from the biomass monomer components (biomass polymers) are not particularly limited, and examples include polybutadiene rubber synthesized from biomass-derived butadiene and aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyls. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0054] Whether the raw material of the polymer is derived from biomass can be determined by pMC (percent Modern Carbon) measured in accordance with ASTM D6866-10.

[0055] pMC is the ratio of the 14 C concentration of the sample to the 14 C concentration of the standard modern carbon (modern standard reference), and is a value used as an index indicating the biomass ratio of a compound. The significance of this value will be described below.

[0056] In one mole (6.02×10 23 pieces) of carbon atoms, there are about 6.02×10 11 pieces, which is about one trillionth of ordinary carbon atoms. 14C exists. 14 C 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 elements.

[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. 14The 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) is 14 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 the hard segment include polystyrene, polypropylene, polyester, polyamide, polyvinyl chloride, polyurethane, etc., and examples of the soft segment include vinyl-polydiene, polyisoprene, polybutadiene, polyethylene, polychloroprene, poly(2,3-dimethylbutadiene), etc. These may be used alone or in combination of two or more.

[0063] The thermoplastic elastomer may be used alone or in combination of two or more. As commercially available products, products of Kuraray Co., Ltd., Asahi Kasei Corporation, etc. can be used. In addition, 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 (styrenic thermoplastic elastomer). Specific examples of the styrenic thermoplastic elastomer include styrene-vinyl isoprene-styrene triblock copolymer (SIS), styrene-isobutylene diblock copolymer (SIB), styrene-butadiene-styrene triblock copolymer (SBS), styrene-ethylene·butylene-styrene triblock copolymer (SEBS), styrene-ethylene·propylene-styrene triblock copolymer (SEPS), styrene-ethylene·ethylene·propylene-styrene triblock copolymer (SEEPS), styrene-butadiene·butylene-styrene triblock copolymer (SBBS), etc. These may be used alone or in combination of two or more. Among them, styrene-ethylene·ethylene·propylene-styrene triblock copolymer (SEEPS) is more preferable.

[0065] The styrene content of the styrenic thermoplastic elastomer is preferably 2% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less, still more preferably 20% by mass or less. When it is within the above range, the effect tends to be obtained more favorably.

[0066] The content of the thermoplastic elastomer is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, still more preferably 10 parts by mass or more, and preferably 40 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 20 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0067] The above rubber composition contains silica as a filler. The silica is not particularly limited. For example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrous silica), etc., which are common in the tire industry, can be used. The raw material of the silica is not particularly limited. For example, it may be a raw material derived from a mineral such as quartz, or a raw material derived from a living organism such as rice husk (for example, silica using a biomass material such as rice husk as a raw material), or silica recycled from a product containing silica may be used. Among them, hydrous silica prepared by a wet method is preferable because it has many silanol groups. These silicas may be used alone or in combination of two or more. As commercially available products, products of Evonik, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Corporation, etc. can be used.

[0068] Silica using a biomass material as a raw material can be obtained, for example, by extracting a silicate from rice husk ash obtained by burning rice husk using a sodium hydroxide solution, and reacting the silicate with sulfuric acid in the same manner as conventional wet silica to precipitate silicon dioxide, followed by filtration, washing with water, drying, and pulverization.

[0069] Silica recycled from a product containing silica can be used, for example, silica recovered from products containing silica such as electronic components such as semiconductors, tires, desiccants, and filter materials such as diatomaceous earth. The recovery method is not particularly limited, and examples include thermal decomposition and decomposition by electromagnetic waves. Among them, silica recovered from electronic components such as semiconductors or tires is preferable.

[0070] When silica crystallizes, it becomes insoluble in water and the silicic acid that is its component cannot be utilized. By controlling the combustion temperature and combustion time, crystallization of silica in rice husk ash can be suppressed (see, for example, Japanese Patent Application Laid-Open No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol. 6, p. 216-222, etc.).

[0071] Amorphous silica extracted from rice husks can be those commercially available from Wilmar Co., Ltd. and the like.

[0072] The average particle diameter of silica is 16 nm or less. The average particle diameter of silica is preferably 15 nm or less, and preferably 6 nm or more, more preferably 9 nm or more, still more preferably 12 nm or more. When it is within the above range, the effect tends to be obtained more favorably.

[0073] In this specification, as the method for measuring the average particle diameter of silica, transmission electron microscope (TEM) observation is used. Specifically, silica particles are photographed with a transmission electron microscope. When the shape of the particles is spherical, the diameter of the sphere is taken as the particle diameter. When the particles are needle-shaped or rod-shaped, the minor axis is taken as the particle diameter. When the particles are amorphous, the average particle diameter from the center is taken as the particle diameter, and the average value of the particle diameters of 100 fine particles is taken as the average particle diameter.

[0074] The content of silica is 100 parts by mass or less with respect to 100 parts by mass of the rubber component. The content of silica is preferably 90 parts by mass or less, more preferably 80 parts by mass or less, still more preferably 70 parts by mass or less, even more preferably 60 parts by mass or less, and preferably 30 parts by mass or more, more preferably 45 parts by mass or more, still more preferably 55 parts by mass or more. When it is within the above range, the effect tends to be obtained more favorably.

[0075] In the above rubber composition, it is preferable that the content of silica ≤ the content of SBR. In this case, the ratio of silica content to SBR content is preferably 0.95 or less, more preferably 0.9 or less, and even more preferably 0.85 or less, and is preferably 0.6 or more, more preferably 0.7 or more, and even more preferably 0.8 or more. Within the above ranges, the effect tends to be better. 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.

[0076] In the rubber composition, the value of the silica content / total styrene content in the rubber component is preferably at least 1, more preferably at least 1.5, even more preferably at least 2.0, particularly preferably at least 2.5, and is preferably at most 10, more preferably at most 7, even more preferably at most 3, particularly preferably at most 2.7. Within the above ranges, 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 total styrene content is the content (unit: % by mass) in 100% by mass of the rubber component.

[0077] 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.

[0078] The cetyltrimethylammonium bromide (CTAB) specific surface area of the carbon black is preferably 70 m 2 / g or more, more preferably 90 m 2 / g or more, still more preferably 110 m 2 / g or more, and preferably 220 m 2 / g or less, more preferably 190 m 2 / g or less, still more preferably 170 m 2 / g or less. In addition, the CTAB specific surface area of the carbon black is a value measured in accordance with JIS K6217-3:2001.

[0079] The content of the carbon black is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, based on 100 parts by mass of the rubber component, and preferably 20 parts by mass or less, more preferably 15 parts by mass or less, still more preferably 10 parts by mass or less. When within the above range, the effect tends to be obtained more favorably.

[0080] In the above rubber composition, the content of the carbon black ≤ the content of BR. The value of the content of the carbon black / the content of BR is preferably 0.8 or less, more preferably 0.6 or less, still more preferably 0.5 or less, and preferably 0.2 or more, more preferably 0.3 or more, still more preferably 0.4 or more. When within the above range, the effect tends to be obtained more favorably. In this relationship, the content of the carbon black is the content (unit: part by mass) based on 100 parts by mass of the rubber component, and the total styrene amount in the rubber component is the content (unit: mass%) in 100 mass% of the rubber component.

[0081] Examples of fillers other than silica and carbon black include vulcanized rubber particles, aluminum hydroxide, talc, calcium compounds, short fibers, etc. These may be used alone or in combination of two or more.

[0082] The vulcanized rubber particles are particles made of vulcanized rubber. Specifically, rubber powder etc. specified in JIS K 6316:2017 can be used. From the viewpoints of environmental consideration and cost, recycled rubber powder produced from crushed waste tires etc. is preferable. These may be used alone or in combination of two or more kinds. The vulcanized rubber particles are not particularly limited, and may be non-modified vulcanized rubber particles or modified vulcanized rubber particles.

[0083] As commercially available products of vulcanized rubber particles, products of Lehigh, Muraoka Rubber Industry Co., Ltd. etc. can be used. In this specification, the vulcanized rubber particles are not included in the rubber component.

[0084] The average particle diameter of the vulcanized rubber particles is preferably 50 μm or more, more preferably 100 μm or more, still more preferably 200 μm or more, and is preferably 1000 μm or less, more preferably 900 μm or less, still more preferably 800 μm or less. The average particle diameter of the vulcanized rubber particles is the average particle diameter on a mass basis calculated from the particle size distribution measured in accordance with JIS Z 8815:1994.

[0085] The content of the vulcanized rubber particles is preferably 2 parts by mass or more, more preferably 6 parts by mass or more, still more preferably 10 parts by mass or more, and is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 20 parts by mass or less with respect to 100 parts by mass of the rubber component. When it is within the above range, the effect tends to be obtained more favorably.

[0086] In this specification, aluminum hydroxide means Al(OH)3 or Al2O3·3H2O. As commercially available products, products of Sumitomo Chemical Co., Ltd., Showa Denko K.K., Nabaltec AG etc. can be used. These may be used alone or in combination of two or more kinds.

[0087] The average particle size of aluminum hydroxide is preferably 0.1 μm or more, more preferably 0.5 μm or more, still more preferably 0.8 μm or more, and is preferably 5 μm or less, more preferably 3 μm or less, still more preferably 1 μm or less. When it is within the above range, the effect tends to be obtained more favorably. In addition, in this specification, as the method for measuring the average particle size of aluminum hydroxide, transmission electron microscope (TEM) observation is used. Specifically, aluminum hydroxide particles are photographed with a transmission electron microscope. When the shape of the particles is spherical, the diameter of the sphere is taken as the particle size; when the shape is needle-like or rod-like, the minor axis is taken as the particle size; when the shape is amorphous, the average particle size from the center is taken as the particle size, and the average value of the particle sizes of 100 fine particles is taken as the average particle size.

[0088] The BET specific surface area (nitrogen adsorption specific surface area, N2SA) of aluminum hydroxide is preferably 5 m 2 / g or more, more preferably 8 m 2 / g or more, still more preferably 10 m 2 / g or more, and is preferably 40 m 2 / g or less, more preferably 30 m 2 / g or less, still more preferably 20 m 2 / g or less. In addition, 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 with respect to 100 parts by mass of the rubber component.

[0090] The average particle size of talc is preferably 50 μm or less, more preferably 30 μm or less. The lower limit of the average particle size of talc is not particularly limited, but is preferably 1 μm or more.

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

[0092] A calcium compound is a compound containing calcium, and examples thereof include inorganic salts such as calcium oxide, calcium hydroxide, and calcium carbide; oxoacid salts such as calcium carbonate, calcium nitrate, and calcium sulfate. In addition, examples of those containing a calcium compound include eggshells (main component: calcium carbonate). These may be used alone or in combination of two or more. Among them, oxoacid salts are preferred, and calcium carbonate is more preferred. In the present specification, calcium fatty acid salts are treated as processing aids described later and are not included in the filler.

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

[0094] As the short fibers, for example, organic short fibers, inorganic short fibers, etc. can be used. Specific examples of the organic short fibers include nanocelluloses such as cellulose nanofibers (CNF) and cellulose nanocrystals (CNC); chitin nanofibers; biomass nanomaterials such as chitosan nanofibers, and specific examples of the inorganic short fibers include metal fibers, glass fiber systems, etc. Commercially available products include products of Nippon Paper Industries Co., Ltd., Sugino Machine Ltd., etc. These may be used alone or in combination of two or more. Among them, organic short fibers are preferred, and nanocellulose is more preferred.

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

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

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

[0098] The content of the filler is preferably 30 parts by mass or more, more preferably 50 parts by mass or more, still more preferably 60 parts by mass or more, and preferably 110 parts by mass or less, more preferably 90 parts by mass or less, still more preferably 70 parts by mass or less with respect to 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0099] The above rubber composition preferably contains a softening agent. The softening agent is a material that imparts plasticity to the rubber component, and is a concept including both a softening agent that is liquid at 25°C and a softening agent that is solid at 25°C. Examples of the softening agent include branched conjugated diene polymers, resins, oils, liquid polymers, ester plasticizers, etc. Among them, branched conjugated diene polymers, resins, and liquid polymers are preferred. These softening agents may be derived from mineral resources such as petroleum and natural gas, may be derived from biomass, or may be derived from naphtha recycled from rubber products or non-rubber products. Also, low molecular weight hydrocarbon components obtained by pyrolyzing and extracting used tires and products containing various components may be used as the softening agent. These softening agents may be used alone or in combination of two or more.

[0100] The branched conjugated diene polymer is a polymer having at least a branched conjugated diene compound as a structural unit. The branched conjugated diene compound may be used alone or in combination of two or more.

[0101] In this specification, the branched conjugated diene compound refers to a compound having a branched structure with a conjugated diene structure in which double bonds are separated by one single bond, and may be either a compound having another double bond or a compound not having another double bond.

[0102] Examples of the branched conjugated diene compound constituting the branched conjugated diene polymer include 2,3-dimethyl-1,3-butadiene, 2,4-dimethyl-1,3-pentadiene, 3-methyl-1,3-pentadiene, farnesene, myrcene, etc. Among them, from the viewpoint of obtaining better effects, farnesene and myrcene are preferred, and farnesene is more preferred. One or more kinds of the branched conjugated diene compound can be used.

[0103] Farnesene has isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene). Among them, (E)-β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene) having the following structure is preferred.

Chemical formula

[0104] Myrcene contains both α-myrcene (2-methyl-6-methyleneocta-1,7-diene) and β-myrcene. Among them, β-myrcene (7-methyl-3-methyleneocta-1,6-diene) having the following structure is preferred.

Chemical formula

[0105] The branched conjugated diene polymer is preferably a copolymer having at least a branched conjugated diene compound and butadiene as constituent units. As the butadiene, 1,3-butadiene is desirable.

[0106] In the branched conjugated diene polymer, the copolymerization ratio by mass (branched conjugated diene compound / butadiene) of the branched conjugated diene compound and butadiene is preferably 40 / 60 or more and 90 / 10 or less.

[0107] The weight average molecular weight (Mw) of the branched conjugated diene polymer is preferably 1000 or more, more preferably 10000 or more, still more preferably 50000 or more, and is preferably 500000 or less, more preferably 300000 or less, still more preferably 150000 or less. When within the above range, the effect tends to be obtained more favorably.

[0108] The branched conjugated diene polymer may be either in a liquid state or a solid state at 25°C. Among them, a solid branched conjugated diene polymer in a solid state at 25°C is desirable.

[0109] [[ID=1ó]]In the rubber composition, the content of the branched conjugated diene polymer is preferably 2 parts by mass or more, more preferably 6 parts by mass or more, still more preferably 10 parts by mass, and is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 20 parts by mass or less with respect to 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0110] Examples of the resin that can be used include resins such as C5-based resins, C5 / C9-based resins, coumarone-indene-based resins, aromatic-based resins, terpene-based resins, cyclopentadiene-based resins, and hydrogenated products thereof. These may be used alone or in combination of two or more. Among them, at least one selected from the group consisting of C5 / C9-based resins and terpene-based resins is preferable, and it is more preferable to use a C5 / C9-based resin and a terpene-based resin in combination. In the present specification, the resin may be solid or liquid at 25°C.

[0111] C5-based resins are polymers containing C5 fractions as constituent monomers. For example, there are homopolymers obtained by polymerizing a single C5 fraction alone, copolymers obtained by copolymerizing two or more C5 fractions, and copolymers of C5 fractions and other monomers copolymerizable therewith. Examples of C5 fractions include olefinic hydrocarbons such as 1-pentene, 2-pentene, 2-methyl-1-butene, and diolefinic hydrocarbons such as 2-methyl-1,3-butadiene, 1,2-pentadiene, 1,3-pentadiene, etc. These may be used alone or in combination of two or more. In this specification, polymers containing C5 fractions and aromatic monomers (C9 fractions) as constituent monomers are treated as C5 / C9-based resins.

[0112] The content of the C5-based resin is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, and preferably 25 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0113] C5 / C9-based resins are polymers containing C5 fractions and C9 fractions as constituent monomers. For example, there are polymers obtained by polymerizing a petroleum-derived C5 fraction and a C9 fraction using a Friedel-Crafts type catalyst such as AlCl3, BF3, etc. Specifically, copolymers mainly composed of styrene, vinyltoluene, α-methylstyrene, indene, etc. are included In this specification, C5 / C9-based resins are treated as aromatic resins, resins different from C5-based resins.

[0114] The content of the C5 / C9 resin is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, and preferably 25 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less, based on 100 parts by mass of the rubber component. When it is within the above range, the effect tends to be obtained more favorably.

[0115] The coumarone-indene resin is a polymer containing coumarone and indene as constituent monomers. For example, in addition to copolymers of coumarone and indene, copolymers of coumarone and indene with other monomers copolymerizable therewith are also included.

[0116] The content of the coumarone-indene resin is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, and preferably 25 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less, based on 100 parts by mass of the rubber component. When it is within the above range, the effect tends to be obtained more favorably.

[0117] The aromatic resin is a polymer containing an aromatic monomer as a constituent monomer. For example, in addition to a homopolymer obtained by polymerizing one aromatic monomer alone and a copolymer obtained by copolymerizing two or more aromatic monomers, copolymers of an aromatic monomer and other monomers copolymerizable therewith are also included.

[0118] Examples of the aromatic monomer 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 them, styrene-based monomers are preferred, and styrene and α-methylstyrene are more preferred.

[0119] Examples of other monomers include non-conjugated olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene. These may be used alone or in combination of two or more.

[0120] As the aromatic resin, α-methylstyrene resins (such as α-methylstyrene homopolymer, copolymer of styrene and α-methylstyrene, etc.) are preferred, and styrene-α-methylstyrene resin (copolymer of styrene and α-methylstyrene) is more preferred.

[0121] The content of the aromatic resin is preferably 15 parts by mass or more, more preferably 30 parts by mass or more, still more preferably 45 parts by mass or more, and preferably 90 parts by mass or less, more preferably 70 parts by mass or less, still more preferably 50 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0122] Terpene resins are polymers containing terpene compounds (terpene monomers) as constituent monomers. For example, homopolymers obtained by polymerizing one kind of terpene compound alone, copolymers obtained by copolymerizing two or more terpene compounds, and copolymers of terpene compounds and other monomers copolymerizable therewith are also included.

[0123] The terpene compound is a hydrocarbon represented by the composition of (C5H8) n and its oxygen-containing derivatives, and includes monoterpenes (C 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32) Compounds having a terpene as the basic skeleton and classified into, for example, α-pinene, β-pinene, dipentene, limonene, myrcene, allo-ocimene, ocimene, α-farnesene, 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.

[0124] 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. When the terpene resin is a homopolymer obtained by polymerizing one kind of terpene compound alone, β-pinene is preferred. 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 not an aromatic resin but is treated as a terpene resin.

[0125] The content of the terpene resin is preferably 1 part by mass or more, more preferably 5 parts by mass or more, still more preferably 10 parts by mass or more, and preferably 25 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0126] The cyclopentadiene resin is a polymer containing a cyclopentadiene monomer as a constituent monomer, and examples thereof include a homopolymer obtained by polymerizing one kind of cyclopentadiene monomer alone, a copolymer obtained by copolymerizing two or more cyclopentadiene monomers, and a copolymer of a cyclopentadiene monomer and another monomer copolymerizable therewith.

[0127] Examples of the cyclopentadiene-based monomer include cyclopentadiene, dicyclopentadiene, tricyclopentadiene, etc. These may be used alone or in combination of two or more. Among them, dicyclopentadiene is preferred. That is, the cyclopentadiene-based resin is preferably a polymer (DCPD-based resin) containing dicyclopentadiene (DCPD) as a constituent monomer, and a hydrogenated DCPD-based resin is more preferred.

[0128] The content of the cyclopentadiene-based resin is preferably 1 part by mass or more, more preferably 5 parts by mass or more, still more preferably 10 parts by mass or more, and preferably 25 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0129] The resin is preferably a modified resin (functionalized resin) into which a functional group is introduced. The modified resin can be produced by known methods, for example, it can be prepared by a slurry method, a metathesis method, etc. Specifically, for example, it can be produced by reacting a polymer serving as the polymer skeleton of the modified resin with a functional compound capable of introducing a functional group by a known method.

[0130] The polymer serving as the polymer skeleton is not particularly limited, and may be, for example, the above-mentioned C5-based resin, aromatic-based resin, terpene-based resin, or other resins. These may be used alone or in combination of two or more. Among them, an aromatic-based resin is preferred, an α-methylstyrene-based resin is more preferred, and a styrene α-methylstyrene resin (a copolymer of styrene and α-methylstyrene) is still more preferred.

[0131] As the functional group, a functional group containing at least one element selected from the group consisting of oxygen, silicon, and nitrogen is preferred, and a functional group containing silicon is more preferred.

[0132] The content of the modified resin is preferably 2 parts by mass or more, more preferably 6 parts by mass or more, still more preferably 10 parts by mass or more, and preferably 40 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 20 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0133] As commercially available products of the above resin, for example, products of Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical, Nippon Paint Co., Ltd., Nippon Catalyst Co., Ltd., ENEOS Co., Ltd., Arakawa Chemical Industries, Ltd., Tago Chemical Industry Co., Ltd., etc. can be used.

[0134] The content of the resin is preferably 2 parts by mass or more, more preferably 6 parts by mass or more, still more preferably 10 parts by mass or more, and preferably 40 parts by mass or less, more preferably 30 parts by mass or less, still more preferably 20 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0135] In the above rubber composition, the value of the content of the resin / the total styrene amount in the rubber component is preferably 2 or less, more preferably 1 or less, still more preferably 0.7 or less, particularly preferably 0.5 or less. The lower limit is not limited and may be 0, but is preferably 0.1 or more, more preferably 0.2 or more, still more preferably 0.3 or more, particularly preferably 0.4 or more. When within the above range, the effect tends to be obtained more favorably. In this relationship, the content of the resin is the content (unit: part by mass) based on 100 parts by mass of the rubber component, and the total styrene amount in the rubber component is the content (unit: mass%) in 100 mass% of the rubber component.

[0136] The liquid polymer is a (co)polymer in a liquid state at 25°C, and examples include liquid rubber and liquid resin. In addition, the liquid polymer may be subjected to a modification treatment or a hydrogenation treatment. As commercially available products, products from Cray Valley, Kuraray Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

[0137] The weight average molecular weight (Mw) of the liquid polymer is less than 120,000, preferably 110,000 or less, more preferably 100,000 or less, and preferably 100 or more, more preferably 1000 or more, still more preferably 2000 or more. When within the above range, the effect tends to be obtained more favorably. In this specification, the liquid polymer is not included in the rubber component.

[0138] As the liquid rubber, at least one diene-based (co)polymer selected from the group consisting of butadiene, isoprene, styrene, farnesene and their derivatives can be used. Specific examples include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), liquid styrene-isoprene copolymer (liquid SIR), liquid farnesene polymer, liquid farnesene-butadiene copolymer and other liquid diene-based polymers. Among them, branched conjugated diene-based polymers such as liquid farnesene polymer and liquid farnesene-butadiene copolymer are preferred.

[0139] The liquid rubber may be modified with a functional group that interacts with silica, and may be modified with a functional group containing at least one element selected from the group consisting of oxygen, nitrogen, silicon and phosphorus at the terminal and / or main chain. Also, the liquid rubber may be either non-hydrogenated or hydrogenated.

[0140] The content of the liquid rubber is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, and preferably 30 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 10 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably contains triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxy group of glycerin and a fatty acid are ester-bonded. The acylglycerol is not particularly limited, and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Further, the acylglycerol may be a monomer, a dimer, or a multimer of trimer or higher. Note that acylglycerols of dimer or higher can be obtained by thermal polymerization, oxidative polymerization, or the like. Also, the acylglycerol may be liquid or solid at 25°C.

[0148] As a method for confirming whether the acylglycerol is contained in the rubber composition, it is not particularly limited, but 1 it can be confirmed by 1H-NMR measurement. For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at 25°C for 24 hours. After removing the rubber composition, 1 1H-NMR is measured. When the signal of tetramethylsilane (TMS) is set to 0.00 ppm, signals around 5.26 ppm, around 4.28 ppm, and around 4.15 ppm are observed, and these signals are presumed to be signals derived from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In this paragraph, "around" means a range of ±0.10 ppm.

[0149] The fatty acid is not particularly limited, and may be an unsaturated fatty acid or a saturated fatty acid. Examples of the unsaturated fatty acid include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of the saturated fatty acid include butyric acid and lauric acid.

[0150] Among these, as the fatty acid, it is desirable to contain a fatty acid with few double bonds, that is, a saturated fatty acid or a monounsaturated fatty acid, and oleic acid is preferred. As the vegetable oil containing such a fatty acid, for example, a vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid may be used, or a vegetable oil subjected to modification such as transesterification may be used. Further, in order to produce a vegetable oil containing such a fatty acid, plants may be improved by variety improvement, genetic recombination, genome editing, or the like.

[0151] As the vegetable oil, for example, those commercially available from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Co., Ltd., Oryz Oy, H&R, Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0152] The content of the vegetable oil is preferably 2 parts by mass or more, more preferably 6 parts by mass or more, still more preferably 10 parts by mass or more, and preferably 30 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0153] As the commercially available oil, products of Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Co., Ltd., Oryz Oy, H&R, Toyokuni Oil Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0154] The content of the oil is preferably 2 parts by mass or more, more preferably 6 parts by mass or more, still more preferably 10 parts by mass or more, and preferably 35 parts by mass or less, more preferably 25 parts by mass or less, still more preferably 15 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0155] The ester plasticizer is not particularly limited as long as it is a compound having an ester group in a liquid state at 25°C. For example, phthalic acid derivatives, long-chain fatty acid derivatives, phosphoric acid derivatives, sebacic acid derivatives, adipic acid derivatives, etc. may be mentioned. These may be used alone or in combination of two or more. Among them, phosphoric acid derivatives, sebacic acid derivatives, and adipic acid derivatives are preferred, and sebacic acid derivatives are more preferred. The phthalic acid derivatives are not particularly limited, and examples thereof include phthalic acid esters such as di-2-ethylhexyl phthalate (DOP) and diisodecyl phthalate (DIDP). The long-chain fatty acid derivatives are not particularly limited, and examples thereof include long-chain fatty acid glycerol esters. The phosphoric acid derivatives are not particularly limited, and examples thereof include phosphate esters such as tris(2-ethylhexyl) phosphate (TOP) and tributyl phosphate (TBP). The sebacic acid derivatives are not particularly limited, and examples thereof include sebacic acid esters such as di(2-ethylhexyl) sebacate (DOS) and diisooctyl sebacate (DIOS). The adipic acid derivatives are not particularly limited, and examples thereof include adipic acid esters such as di(2-ethylhexyl) adipate (DOA) and diisooctyl adipate (DIOA). Among them, phosphate esters, sebacic acid esters, and adipic acid esters are preferred, and sebacic acid esters are more preferred. Also, as specific compounds, TOP, DOS, and DOA are preferred, and DOS is more preferred. As the ester plasticizer, for example, products of Daihachi Chemical Industry Co., Ltd., Tago Chemical Industry Co., Ltd., etc. can be used.

[0156] The glass transition temperature (Tg) of the ester plasticizer is preferably -110°C or higher, more preferably -100°C or higher, still more preferably -80°C or higher, and preferably -20°C or lower, more preferably -40°C or lower, still more preferably -55°C or lower. By being within the above range, there is a tendency that the above effect can be obtained more suitably. In this specification, the glass transition temperature of the ester plasticizer was measured using a differential scanning calorimeter (Q200) manufactured by TA Instruments Japan Co., Ltd. in accordance with JIS-K7121 under the condition of a heating rate of 10 °C / min.

[0157] The content of the ester plasticizer is preferably 1 to 20 parts by mass with respect to 100 parts by mass of the rubber component.

[0158] The content of the softening agent is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, still more preferably 20 parts by mass or more, and preferably 50 parts by mass or less, more preferably 40 parts by mass or less, still more preferably 30 parts by mass or less with respect to 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0159] In the above rubber composition, the value of the content of the softening agent / the content of the filler is preferably 0.1 or more, more preferably 0.2 or more, still more preferably 0.25 or more, particularly preferably 0.3 or more, and preferably 1 or less, more preferably 0.7 or less, still more preferably 0.5 or less, particularly preferably 0.35 or less. When within the above range, the effect tends to be obtained more favorably. In this relationship, the contents of the softening agent and the filler are the contents (unit: parts by mass) with respect to 100 parts by mass of the rubber component.

[0160] The above rubber composition may contain a silane coupling agent. The silane coupling agent is not particularly limited. For example, bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide and other sulfide-based ones, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane and other mercapto-based ones, vinyltriethoxysilane, vinyltrimethoxysilane and other vinyl-based ones, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane and other amino-based ones, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane and other glycidoxy-based ones, 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane and other nitro-based ones, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane and other chloro-based ones can be mentioned. As commercially available products, for example, products of Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azmax Co., Ltd., Toray Dow Corning Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

[0161] In addition, as the mercapto-based silane coupling agent, in addition to the compound having a mercapto group, a compound having a structure in which the mercapto group is protected by a protecting group (for example, the compound represented by the following formula (S1)) can also be used.

[0162] Particularly preferred mercapto-based silane coupling agents include the silane coupling agent represented by the following formula (S1) and the silane coupling agent containing the bonding unit A represented by the following formula (I) and the bonding unit B represented by the following formula (II).

Chemical formula

Chemical formula

Chemical formula

[0163] In formula (S1), R 1005 , R 1006 , R 1007 and R 1008 are each independently preferably a group selected from the group consisting of linear, cyclic or branched alkyl groups, alkenyl groups, aryl groups and aralkyl groups having 1 to 18 carbon atoms. Further, when R 1002 is a monovalent hydrocarbon group having 1 to 18 carbon atoms, it is preferably a group selected from the group consisting of linear, cyclic or branched alkyl groups, alkenyl groups, aryl groups and aralkyl groups. R 1009 is preferably a linear, cyclic or branched alkylene group, particularly preferably a linear one. R 1004 may be, for example, an alkylene group having 1 to 18 carbon atoms, an alkenylene group having 2 to 18 carbon atoms, a cycloalkylene group having 5 to 18 carbon atoms, a cycloalkylalkylene group having 6 to 18 carbon atoms, an arylene group having 6 to 18 carbon atoms, or an aralkylene group having 7 to 18 carbon atoms. The alkylene group and the alkenylene group may be either linear or branched, and the cycloalkylene group, the cycloalkylalkylene group, the arylene group and the aralkylene group may have a functional group such as a lower alkyl group on the ring. This R 1004As for this, an alkylene group having 1 to 6 carbon atoms is preferable, and a linear alkylene group, for example, a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group is particularly preferable.

[0164] R in formula (S1) 1002 , R 1005 , R 1006 , R 1007 and R 1008 Specific examples of these 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, a naphthylmethyl group and the like. R in formula (S1) 1009 Examples of R in formula (S1) include linear alkylene groups such as a methylene group, an ethylene group, an n-propylene group, an n-butylene group, a hexylene group, and branched alkylene groups such as an isopropylene group, an isobutylene group, a 2-methylpropylene group.

[0165] 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, 2-lauroylthioethyltrimethoxysilane, and the like. These may be used alone or in combination of two or more. Among them, 3-octanoylthiopropyltriethoxysilane is particularly preferred.

[0166] In the silane coupling agent containing the bonding unit A represented by formula (I) and the bonding unit B represented by formula (II), the content of the bonding unit A is preferably 30 mol% or more, more preferably 50 mol% or more, preferably 99 mol% or less, and more preferably 90 mol% or less. Also, the content of the bonding unit B is preferably 1 mol% or more, more preferably 5 mol% or more, still more preferably 10 mol% or more, preferably 70 mol% or less, more preferably 65 mol% or less, and still more preferably 55 mol% or less. Further, the total content of the bonding units A and B is preferably 95 mol% or more, more preferably 98 mol% or more, and particularly preferably 100 mol%. Note that the contents of the bonding units A and B are amounts including the case where the bonding units A and B are located at the terminals of the silane coupling agent. The form when the bonding units A and B are located at the terminals of the silane coupling agent is not particularly limited as long as it forms a unit corresponding to the formulas (I) and (II) representing the bonding units A and B.

[0167] R in formulas (I) and (II)11 Regarding this, examples of the halogen include chlorine, bromine, fluorine, etc. Examples of the branched or unbranched alkyl group having 1 to 30 carbon atoms include a methyl group, an ethyl group, etc. Examples of the branched or unbranched alkenyl group having 2 to 30 carbon atoms include a vinyl group, a 1-propenyl group, etc. Examples of the branched or unbranched alkynyl group having 2 to 30 carbon atoms include an ethynyl group, a propynyl group, etc.

[0168] R in formulas (I) and (II) 12 Regarding this, examples of the branched or unbranched alkylene group having 1 to 30 carbon atoms include an ethylene group, a propylene group, etc. Examples of the branched or unbranched alkenylene group having 2 to 30 carbon atoms include a vinylene group, a 1-propenylene group, etc. Examples of the branched or unbranched alkynylene group having 2 to 30 carbon atoms include an ethynylene group, a propynylene group, etc.

[0169] In the silane coupling agent containing the bonding unit A represented by formula (I) and the bonding unit B represented by formula (II), the total number of repetitions (v + w) of the number of repetitions (v) of the bonding unit A and the number of repetitions (w) of the bonding unit B is preferably in the range of 3 to 300.

[0170] The content of the silane coupling agent is preferably 2 parts by mass or more, more preferably 6 parts by mass or more, still more preferably 10 parts by mass or more, and preferably 20 parts by mass or less, more preferably 16 parts by mass or less, still more preferably 14 parts by mass or less with respect to 100 parts by mass of silica. When it is within the above range, the effect tends to be obtained more favorably.

[0171] The above rubber composition may contain a processing aid. Examples of the processing aid include metal salts (compounds in which the hydrogen atom of an acid is replaced by a metal ion), fatty acid amides, amide esters, fatty acid esters, etc. These may be used alone or in combination of two or more. Among them, metal salts are preferred.

[0172] Examples of the metal used in the metal salt include alkali metals such as potassium and sodium, alkaline earth metals such as calcium and barium, etc. Magnesium, zinc, nickel, molybdenum, etc. can also be used. Among them, zinc is preferred.

[0173] Examples of the acid used in the metal salt include fatty acids such as lauric acid, myristic acid, palmitic acid, etc. Boric acid, carbonic acid, hydrochloric acid, nitric acid, sulfuric acid, etc. can also be used. Among them, fatty acids are preferred.

[0174] As commercially available products of the processing aid, products of Kinoshita Chemical Co., Ltd., Ken-ei Pharmaceutical Co., Ltd., Struktol, Performance Additives, etc. can be used.

[0175] The content of the processing aid is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more, still more preferably 2 parts by mass or more, and preferably 20 parts by mass or less, more preferably 10 parts by mass or less, still more preferably 6 parts by mass or less, based on 100 parts by mass of the rubber component. When it is within the above range, the effect tends to be obtained more favorably.

[0176] The above rubber composition may contain an antioxidant. The anti-aging agent is not particularly limited, but examples include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine-based anti-aging agents such as 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), N,N'-ditoly-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based anti-aging agents such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based anti-aging agents such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; bis, tris, polyphenol-based anti-aging agents such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, etc. Among them, p-phenylenediamine-based anti-aging agents and quinoline-based anti-aging agents are preferred, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and polymers of 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. As commercially available products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Industry Co., Ltd., Flexsys, etc. can be used. These may be used alone or in combination of two or more.

[0177] The content of the anti-aging agent is preferably 0.2 parts by mass or more, more preferably 0.6 parts by mass or more, still more preferably 1 part by mass or more, and preferably 15 parts by mass or less, more preferably 10 parts by mass or less, still more preferably 5 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0178] The above rubber composition may contain wax. The wax is not particularly limited, and any wax commonly used in the tire industry can be preferably used. For example, mineral waxes, plant-derived waxes, etc. can be mentioned. 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 them, mineral waxes are preferred. Examples of plant-derived waxes include rice wax, carnauba wax, candelilla wax, etc. Examples of mineral waxes include paraffin wax, microcrystalline wax, these selected special waxes, etc., and paraffin wax is preferred. Note that the wax according to this embodiment does not contain stearic acid. As the wax, for example, those commercially available from Ouchi Shinsei Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramoelt Co., etc. can be used. These waxes may be used alone or in combination of two or more.

[0179] The content of the wax is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 8 parts by mass or less, more preferably 5 parts by mass or less with respect to 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0180] The above rubber composition may contain stearic acid. As the stearic acid, conventionally known ones can be used, and as commercially available products, products of Nippon Oil Co., Ltd., Kao Corporation, Fuji Film Wako Pure Chemical Industries, Ltd., Chiba Fatty Acids Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

[0181] The content of stearic acid is preferably 1 part by mass or more, more preferably 2.5 parts by mass or more, and preferably 8 parts by mass or less, more preferably 5 parts by mass or less with respect to 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0182] The above rubber composition may contain zinc oxide. As the zinc oxide, those conventionally known can be used. As commercially available products, products of Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Sho Do Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

[0183] The content of zinc oxide is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less with respect to 100 parts by mass of the rubber component. When it is within the above range, the effect tends to be obtained more favorably.

[0184] The above rubber composition may contain sulfur. Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, soluble sulfur, etc., which are generally used as crosslinking agents in the rubber industry. As commercially available products, products of Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexsys, Nippon Retort Industry Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

[0185] The content of sulfur is preferably 0.5 part by mass or more, more preferably 1.2 parts by mass or more, still more preferably 1.7 parts by mass or more, and preferably 8 parts by mass or less, more preferably 6 parts by mass or less, still more preferably 4 parts by mass or less with respect to 100 parts by mass of the rubber component. When it is within the above range, the effect tends to be obtained more favorably.

[0186] The above 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.

Chemical formula

[0187] Specific examples of the dibenzylamine compound include dibenzylamine, tetrabenzylthiuram disulfide (TBzTD), zinc dibenzyldithiocarbamate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, and the like. As commercially available products, products of Sanshin Chemical Industry Co., Ltd., Ouchi Shinsei Chemical Industry Co., Ltd., Rancess Co., Ltd., etc. can be used. These may be used alone or in combination of two or more. Among them, a compound having two dibenzylamine groups is preferable, and tetrabenzylthiuram disulfide is more preferable.

[0188] The content of the dibenzylamine compound is preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, still more preferably 0.5 part by mass or more, and preferably 5 parts by mass or less, more preferably 3 parts by mass or less, still more preferably 2 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0189] The above rubber composition may contain a dialkyldithiophosphoric acid compound. As the dialkyldithiophosphoric acid compound, for example, salts of dialkyldithiophosphoric acid with metals such as zinc and molybdenum can be used. As commercially available products, products such as TP-50 manufactured by Rhein Chemie can be used. These may be used alone or in combination of two or more. Among them, the compound represented by the following formula (1) (zinc dialkyldithiophosphate) is preferable.

Chemical formula

[0190] In formula (1), R 1 ~R 4Examples of the linear or branched alkyl group represented by [it] include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, a 4-methylpentyl group, a 2-ethylhexyl group, an octyl group, an octadecyl group, etc. On the other hand, examples of the cycloalkyl group include a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, etc. Among them, from the viewpoints of easy dispersion in the rubber composition and easy production, R 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 iso-propyl group, or an n-octyl group, and even more preferably an n-butyl group.

[0191] The content of the dialkyldithiophosphate compound is preferably 0.5 part by mass or more, more preferably 1.5 parts by mass or more, even more preferably 2 parts by mass or more, and preferably 8 parts by mass or less, more preferably 6 parts by mass or less, even more preferably 4 parts by mass or less, based on 100 parts by mass of the rubber component. When within the above range, the effect tends to be obtained more favorably.

[0192] The above rubber composition may contain a vulcanization accelerator. Examples of the vulcanization accelerator include benzothiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole and di-2-benzothiazolyldisulfide; 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-benzothiazylsulfenamide (CBS), N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-oxyethylene-2-benzothiazolesulfenamide, and N,N'-diisopropyl-2-benzothiazolesulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, diorthotolylguanidine, and orthotolylbiguanidine. As commercially available products, products of Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., etc. can be used. These may be used alone or in combination of two or more.

[0193] The content of the vulcanization accelerator is preferably 2 parts by mass or more, more preferably 4 parts by mass or more, still more preferably 5.1 parts by mass or more, and preferably 20 parts by mass or less, more preferably 15 parts by mass or less, still more preferably 10 parts by mass or less, based on 100 parts by mass of the rubber component. When it is within the above range, the effect tends to be obtained more favorably.

[0194] In addition to the above components, the rubber composition may further contain additives generally used in the tire industry, such as organic peroxides. The content of these additives is preferably 0.1 to 200 parts by mass based on 100 parts by mass of the rubber component.

[0195] In this specification, various materials containing carbon atoms (for example, rubber, oil, resin, vulcanization accelerator, anti-aging agent, surfactant, etc.) may be derived from carbon dioxide in the atmosphere. As a method for obtaining the above mixture from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process for synthesizing methane from carbon dioxide may be converted.

[0196] 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, and then vulcanizing.

[0197] As the kneading conditions, in the base kneading step of kneading additives other than the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 100 to 180°C, preferably 120 to 170°C. In the finishing kneading step of kneading the vulcanizing agent and the vulcanization accelerator, the kneading temperature is usually 120°C or lower, preferably 85 to 110°C. Further, the composition kneaded with the vulcanizing agent and the 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.

[0198] The above rubber composition can be used (as a rubber composition for tires) in tire members such as, for example, treads, sidewalls, undertreads, shoulders, clinches, bead apexes, breaker cushion rubbers, carcass cord cover rubbers, insulations, chafers, inner liners, etc., and side reinforcement layers of run-flat tires. Among them, it is suitable for treads. Further, when the tread has a multi-layer structure, it can be used for both the surface layer (cap tread) and the inner layer (base tread), but it is particularly suitable for the cap tread.

[0199] The tire of the present disclosure is manufactured by a normal method using the above rubber composition. That is, the above rubber composition is extruded into a shape such as a tread at the unvulcanized stage, and together with other tire members, an unvulcanized tire is formed by molding in a normal manner on a tire molding machine. The unvulcanized tire is heated and pressurized in a vulcanizer to obtain a tire.

[0200] The above tire (such as a pneumatic tire) 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 having a side reinforcement layer; tires with a sound-absorbing member such as sponge provided in the tire cavity; tires with a sealing member having a sealant that can be sealed when punctured provided inside the tire or in the tire cavity; tires with electronic components such as sensors and wireless tags provided inside the tire or in the tire cavity, etc., and is suitable for passenger car tires.

[0201] The size of the above tire is not particularly limited. For example, the tire width can be appropriately selected within the range of 100 to 400 mm, the aspect ratio within the range of 25 to 85%, and the rim diameter within the range of 10 to 25 inches. Specific examples include 105 / 50R16, 115 / 50R17, 125 / 55R20, 135 / 45R21, 145 / 45R21, 155 / 45R18, 165 / 45R22, 175 / 45R23, 185 / 60R20, 195 / 55R14, 205 / 40R16, 215 / 40R16, 225 / 40R17, 235 / 40R17, 245 / 40R16, 255 / 40R17, 265 / 40R17, 275 / 35R18, 285 / 30R19, 295 / 45R20, etc.

[0202] It is preferable that the above tire satisfies the relational expression of the following formula for the tire outer diameter Dt and the tire section width Wt.

Equation

[0203] 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, etc.

[0204] The tire that satisfies the above formula is preferably applied to a pneumatic tire for a passenger car. This is because a pneumatic tire for a passenger car that satisfies the above formula tends to be more suitable for solving the problems of this case.

Example

[0205] The following shows examples (Examples) that are considered preferable for implementation, but the scope of the present invention is not limited to the Examples.

[0206] The various chemicals used in the Examples and Comparative Examples will be described below.

[0207] (Rubber component) NR: TSR20 BR: BR150B manufactured by Ube Industries, Ltd. (vinyl content: 1 mass%, cis content: 97 mass%) SBR1: Modified SBR synthesized in Production Example 1 below (styrene content: 38 mass%, vinyl content: 30 mass%, Tg: -25°C, Mw: 2 million) SBR2: Modified SBR synthesized in Production Example 2 below (styrene content: 25 mass%, vinyl content: 61 mass%, Tg: -24°C, Mw: 300,000) SBR3: Modified SBR synthesized in Production Example 3 below (styrene content: 40 mass%, vinyl content: 25 mass%, Tg: -34°C, Mw: 1.2 million)

[0208] (Chemicals other than rubber components) Carbon black: N220 (CTAB specific surface area: 111 m 2 / g) Silica 1: Ultrasil VN3 manufactured by Evonik (average particle diameter: 17 nm) Silica 2: ULTRASIL 9100GR manufactured by Evonik (average particle diameter: 15 nm) Silane coupling agent: Si266 manufactured by Evonik Degussa (bis(3-triethoxysilylpropyl) disulfide) Resin 1: Sylvatraxx 4401 manufactured by Arizona Chemical (styrene α-methylstyrene resin (copolymer of styrene and α-methylstyrene)) Resin 2: YS Resin TO125 manufactured by Yasuhara Chemical Co., Ltd. (terpene styrene resin (copolymer of terpene compound and styrene)) Resin 3: Petrotack 100V manufactured by Tosoh Corporation (C5 / C9 resin) Resin 4: A modified styrene α-methylstyrene resin (copolymer of styrene and α-methylstyrene) synthesized in Production Example 4 below Branched conjugated diene polymer: FBR-746 manufactured by Kuraray Co., Ltd. (farnesene-butadiene copolymer, Mw: 100,000, in a liquid state at 25°C) Oil 1: VIVATEC 500 manufactured by H&R (aromatic oil) Oil 2: Sunflower oil (vegetable oil) manufactured by Nisshin Oillio Group, Ltd. Wax: Ozace 0355 manufactured by Nippon Seiro Co., Ltd. Antioxidant 1: Nocrack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Antioxidant 2: Nocrack RD (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Processing aid: ULTRA-FLOW 440 (zinc fatty acid) manufactured by Performance Additives Stearic acid: Stearic acid "Tsubaki" manufactured by NOF Corporation Zinc oxide: Zinc white No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Nocceler CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Nocceler D (N,N'-diphenylguanidine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Dibenzylamine compound: Sanseler TBzTD (tetrabenzylthiuram disulfide) manufactured by Sanshin Chemical Industry Co., Ltd.

[0209] (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 SBR1.

[0210] (Production Example 2) 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. N-(3-dimethylaminopropyl)acrylamide 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 SBR2.

[0211] (Production Example 3) 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. N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane 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.

[0212] (Production Example 4) Aluminum chloride and toluene are added to an inert gas-substituted glass flask, and styrene and α-methylstyrene are added dropwise. Then, an isoprene / toluene solution to which allyltriethoxysilane is added is added dropwise to the reaction solution by the slurry method, and water is added to the reaction solution to stop the reaction. The step of removing the aqueous layer by liquid separation is repeated, and the organic layer obtained by liquid separation is dried by blowing air to volatilize toluene, and then dried under reduced pressure to obtain a modified styrene α-methylstyrene resin (resin 4).

[0213] (Examples and Comparative Examples) According to the formulation contents shown in Tables 1 to 3, using a 1.7 L Banbury mixer manufactured by Kobe Steel, Ltd., materials other than sulfur, vulcanization accelerator, and dibenzylamine compound are kneaded at 150 °C for 5 minutes to obtain a kneaded product. Next, sulfur, vulcanization accelerator, and dibenzylamine compound are added to the kneaded product, and it is kneaded at 80 °C for 5 minutes using an open roll to obtain an unvulcanized rubber composition. Next, the unvulcanized rubber composition is formed into the shape of a cap tread, bonded together with other tire members to form an unvulcanized tire, and press-vulcanized at 150 °C for 12 minutes to manufacture a test tire (size: 175 / 60R18). The test tires thus manufactured are examined, and the results calculated based on the following evaluation methods are shown in Tables 1 to 3.

[0214] Also, in the following evaluation methods, the evaluation criteria when calculating the index are as follows. Table 1: Comparative Example 2 Table 2: Comparative Example 5 Table 3: Comparative Example 6

[0215] (Chipping Resistance Performance) Each test tire is mounted on a vehicle, and the number of chipping occurrence locations in the tread part after traveling a predetermined distance is counted, and the index is displayed with the evaluation criterion as 100. The larger the index, the fewer the chipping occurrence locations, indicating excellent chipping resistance performance.

[0216]

Table 1

[0217]

Table 2

[0218]

Table 3

[0219] The present invention (1) contains a rubber component including butadiene rubber and styrene-butadiene rubber, and silica, wherein the content of the silica is 100 parts by mass or less with respect to 100 parts by mass of the rubber component, content of carbon black ≦ content of the butadiene rubber, content of the butadiene rubber ≦ total styrene amount in the rubber component, and is a rubber composition for tires in which the average particle diameter of the silica is 16 nm or less.

[0220] The present invention (2) is the rubber composition for tires according to the present invention (1) containing a resin.

[0221] The present invention (3) is the rubber composition for tires according to the present invention (1) or (2) containing two or more styrene-butadiene rubbers.

[0222] The present invention (4) is a rubber composition for tires in any combination with any one of the present inventions (1) to (3) wherein the content of the silica ≦ the content of the styrene-butadiene rubber.

[0223] The present invention (5) is a rubber composition for tires in any combination with any one of the present inventions (1) to (4) wherein the rubber component contains isoprene rubber.

[0224] The present invention (6) is a rubber composition for tires in any combination with any one of the present inventions (1) to (5) containing at least one resin selected from the group consisting of C5 / C9 resins and terpene resins.

[0225] The present invention (7) is a rubber composition for tires, which is any combination with any of the present inventions (1) to (6), wherein the content of the isoprene-based rubber is greater than the total amount of styrene in the rubber component.

[0226] The present invention (8) is a rubber composition for tires containing a dibenzylamine compound in any combination with any of the present inventions (1) to (7).

[0227] The present invention (11) is a rubber composition for tires containing a modified resin in any combination with any of the present inventions (1) to (8).

[0228] The present invention (10) is a rubber composition for tires containing a branched conjugated diene polymer in any combination with any of the present inventions (1) to (9).

[0229] The present invention (11) is a rubber composition for tires in any combination with any of the present inventions (1) to (10), in which the value of the content of the butadiene rubber / the total amount of styrene in the rubber component is 0.5 or less.

[0230] The present invention (12) is a rubber composition for tires in any combination with any of the present inventions (1) to (11), in which the value of the content of the styrene butadiene rubber / the content of the butadiene rubber is 8 or less.

[0231] The present invention (13) is a rubber composition for tires, which is any combination with any of the present inventions (1) to (12), in which (content of isoprene-based rubber+content of the butadiene rubber) / content of the styrene-butadiene rubber ≦0.6.

[0232] The present invention (14) is a tire using a rubber composition in any combination with any of the present inventions (1) to (13).

Claims

1. A rubber composition containing a rubber component including butadiene rubber and styrene-butadiene rubber, and silica, wherein the content of the silica is 100 parts by mass or less with respect to 100 parts by mass of the rubber component, the content of carbon black ≤ the content of the butadiene rubber, the content of the butadiene rubber ≤ the total styrene amount in the rubber component, and a rubber composition for a tire wherein the average particle diameter of the silica is 16 nm or less.

2. The rubber composition for a tire according to Claim 1, containing a resin.

3. The rubber composition for a tire according to Claim 1 or 2, containing two or more kinds of the styrene-butadiene rubber.

4. The rubber composition for a tire according to Claim 1 or 2, wherein the content of the silica ≤ the content of the styrene-butadiene rubber.

5. The rubber composition for a tire according to Claim 1 or 2, wherein the rubber component contains an isoprene-based rubber.

6. The rubber composition for a tire according to Claim 1 or 2, containing at least one resin selected from the group consisting of a C5 / C9-based resin and a terpene-based resin.

7. The rubber composition for a tire according to Claim 1 or 2, wherein the content of the isoprene-based rubber > the total styrene amount in the rubber component.

8. The rubber composition for a tire according to Claim 1 or 2, containing a dibenzylamine compound.

9. The rubber composition for a tire according to Claim 1 or 2, containing a modified resin.

10. The rubber composition for a tire according to Claim 1 or 2, containing a branched conjugated diene polymer.

11. The rubber composition for a tire according to Claim 1 or 2, wherein the value of (the content of the butadiene rubber) / (the total styrene amount in the rubber component) is 0.5 or less.

12. The rubber composition for a tire according to Claim 1 or 2, wherein the value of (the content of the styrene-butadiene rubber) / (the content of the butadiene rubber) is 8 or less.

13. The rubber composition for a tire according to Claim 1 or 2, wherein (the content of the isoprene-based rubber + the content of the butadiene rubber) / (the content of the styrene-butadiene rubber) ≤ 0.

6.

14. A tire using the rubber composition according to Claim 1 or 2.

Images