Rubber composition for tires and tires

Abstract

To provide a tire rubber composition and a pneumatic tire having excellent overall performances in terms of abrasion resistance during high-speed driving and wet grip performance during high-speed driving.SOLUTION: A tire rubber composition contains a rubber component including styrene-butadiene rubber, the tire rubber composition containing, per 100 pts.mass of the rubber component, 150 pts.mass or more of a white filler and 30 pts.mass or more of a resin.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Although attempts have been made to improve wet grip performance by blending aluminum hydroxide or resins or by blending large amounts of silica, this has the problem of worsening abrasion resistance. As such, abrasion resistance and wet grip performance are contradictory properties and it is currently difficult to achieve both. Summary of the Invention [Problem to be solved by the invention]

[0003] As a result of extensive research by the present inventors, it has been found that abrasion resistance and wet grip performance are mutually exclusive properties and are difficult to achieve at the same time, but with conventional technology, for example, when a large amount of silica is compounded, the temperature tends to rise during high-speed driving and abrasion resistance drops significantly, making it extremely difficult to achieve both abrasion resistance during high-speed driving and wet grip performance during high-speed driving at the same time. The present invention aims to solve the above-mentioned new problem discovered by the present inventors, and to provide a rubber composition for tires and a pneumatic tire that are excellent in overall performance, including abrasion resistance during high-speed driving and wet grip performance during high-speed driving. [Means for solving the problem]

[0004] The present invention relates to a rubber composition for tires containing 100 parts by mass of a rubber component containing styrene-butadiene rubber, 150 parts by mass or more of a white filler, and 30 parts by mass or more of a resin.

[0005] The resin is preferably a terpene-based resin or a styrene-based resin.

[0006] The rubber composition preferably contains 20 parts by mass or more of a styrene-based resin per 100 parts by mass of the rubber component, and the average styrene content of the styrene-butadiene rubber is preferably 30% by mass or more.

[0007] The rubber composition preferably contains 20 parts by mass or more of a terpene resin per 100 parts by mass of the rubber component, and the average styrene content of the styrene-butadiene rubber is preferably less than 20% by mass.

[0008] The rubber composition preferably contains 100 parts by mass or more of silica, more preferably 120 parts by mass or more, and even more preferably 150 parts by mass or more of silica, per 100 parts by mass of the rubber component.

[0009] The rubber composition preferably contains a sulfide-based silane coupling agent.

[0010] The rubber composition preferably contains an ester-based plasticizer.

[0011] The rubber composition preferably contains aluminum hydroxide.

[0012] The present invention also relates to a tire having a tread made using the above rubber composition. [Effects of the Invention]

[0013] According to the present invention, the rubber composition for tires contains 150 parts by mass or more of a white filler and 30 parts by mass or more of a resin relative to 100 parts by mass of a rubber component containing styrene-butadiene rubber, and therefore has excellent overall performance in terms of abrasion resistance during high-speed driving and wet grip performance during high-speed driving. DETAILED DESCRIPTION OF THE INVENTION

[0014] The rubber composition for a tire of the present invention contains 150 parts by mass or more of a white filler and 30 parts by mass or more of a resin per 100 parts by mass of a rubber component containing styrene-butadiene rubber, thereby improving overall performance including abrasion resistance during high-speed driving and wet grip performance during high-speed driving.

[0015] The rubber composition for a tire can provide the above-mentioned effects, and although the reason why such effects are obtained is not entirely clear, it is presumed as follows. The rubber composition for tires contains 150 parts by mass or more of a white filler and 30 parts by mass or more of a resin relative to 100 parts by mass of a rubber component containing styrene butadiene rubber (SBR). In rubber compositions with a high white filler content, the combined use of SBR and resin improves the dispersibility of the resin, synergistically improving the overall performance of both abrasion resistance at high speeds and wet grip performance at high speeds.

[0016] Chemicals that can be used in the rubber composition will be described below.

[0017] The rubber composition for tires contains styrene butadiene rubber (SBR) as a rubber component.

[0018] The SBR is not particularly limited, and for example, emulsion-polymerized SBR (E-SBR), solution-polymerized SBR (S-SBR), and other commonly used SBRs in the tire industry can be used. These may be used alone or in combination of two or more. Of these, S-SBR is preferred.

[0019] The average styrene content of the SBR is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, particularly preferably 20% by mass or more, most preferably 25% by mass or more, more preferably 30% by mass or more, more preferably 35% by mass or more, more preferably 38% by mass or more, and is preferably 50% by mass or less, more preferably 47% by mass or less, even more preferably 45% by mass or less. Within the above ranges, the effects tend to be more favorably obtained.

[0020] When a rubber composition contains multiple SBRs, the "average styrene content" in this specification refers to the average styrene content of the multiple SBRs. When a rubber composition contains only one type of SBR, it refers to the styrene content of that SBR. The average styrene content of the SBRs is {Σ(content of each SBR × styrene content of each SBR)} / total content of all SBRs. For example, when the rubber component consists of 90% by mass of SBR(A) (styrene content 40% by mass), 5% by mass of SBR(B) (styrene content 25% by mass), and 5% by mass of BR, the average styrene content is 39.21% by mass (=(90 × 40 + 5 × 25) / (90 + 5)).

[0021] The SBR may be unmodified or modified. The modified SBR may be any SBR having a functional group that interacts with a filler such as silica, and examples thereof include terminal-modified SBR in which at least one terminal of the SBR has been modified with a compound (modifier) ​​having the above functional group (terminal-modified SBR having the above functional group at the terminal), main-chain-modified SBR in which the main chain has the above functional group, main-chain-terminal-modified SBR in which the main chain and terminals have the above functional group (for example, main-chain-terminal-modified SBR in which the main chain has the above functional group and at least one terminal has been modified with the above modifier), and terminal-modified SBR modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and into which hydroxyl groups or epoxy groups have been introduced. These may be used alone or in combination of two or more.

[0022] Examples of the functional group include an amino group, an amido group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, 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 carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, and an epoxy group. These functional groups may have a substituent. Among these, an amino group (preferably an amino group in which a hydrogen atom of an amino group is substituted with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), an alkoxysilyl group (preferably an alkoxysilyl group having 1 to 6 carbon atoms), and an amide group are preferred.

[0023] As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc. can be used.

[0024] The content of SBR in 100% by mass of the rubber component is preferably 20% by mass or more, more preferably 40% by mass or more, even more preferably 60% by mass or more, particularly preferably 80% by mass or more, and most preferably 90% by mass or more, and may be 100% by mass. When it is within the above range, the effect tends to be better obtained.

[0025] Usable rubber components other than SBR include diene rubbers such as isoprene rubber, butadiene rubber (BR), styrene-isoprene-butadiene rubber (SIBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), and butyl rubber (IIR). The rubber components may be used alone or in combination of two or more. Among these, diene rubbers are preferred, and isoprene rubber and BR are more preferred.

[0026] Here, the rubber component is a rubber having a weight average molecular weight (Mw) of preferably 150,000 or more, more preferably 350,000 or more. There is no particular upper limit for Mw, but it is preferably 4,000,000 or less, more preferably 3,000,000 or less.

[0027] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. NRs such as SIR20, RSS#3, and TSR20 are commonly used in the tire industry. IRs are not particularly limited, and examples of IRs such as IR2200 are commonly used in the tire industry. Modified NRs include deproteinized natural rubber (DPNR) and highly purified natural rubber (UPNR). Modified NRs include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Modified IRs include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more. NR is preferred.

[0028] The BR is not particularly limited, and those commonly used in the tire industry can be used, such as high-cis BR with a high cis content, low-cis BR with a low cis content, BR containing syndiotactic polybutadiene crystals, and BR synthesized using a rare earth catalyst (rare earth BR). Crystalline BR such as syndiotactic 1,2-polybutadiene can also be used. These can be used alone or in combination of two or more.

[0029] As the BR, for example, products from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used.

[0030] In this specification, the weight average molecular weight (Mw) and number average molecular weight (Mn) can be determined in terms of standard polystyrene based on measurements obtained using a gel permeation chromatograph (GPC) (GPC-8000 series, manufactured by Tosoh Corporation; detector: differential refractometer; column: TSKGEL SUPERMULTIPORE HZ-M, manufactured by Tosoh Corporation). The amount of styrene is 1 It can be measured by H-NMR measurement.

[0031] The rubber composition contains a resin. The resin is not particularly limited, but examples thereof include alkylphenol resins, styrene resins, coumarone-indene resins, terpene resins, rosin resins, acrylic resins, dicyclopentadiene resins (DCPD resins), C5 resins, and C9 resins. These may be used alone or in combination of two or more. Among these, styrene resins and terpene resins are preferred, and styrene resins are more preferred.

[0032] The softening point of the resin is preferably 20° C. or higher, more preferably 60° C. or higher, and preferably 200° C. or lower, more preferably 160° C. or lower, even more preferably 140° C. or lower, and particularly preferably 130° C. or lower. Within the above range, the effect tends to be better obtained. In this specification, the softening point of a resin is the temperature at which the ball drops when the softening point specified in JIS K 6220-1:2001 is measured using a ring and ball softening point tester.

[0033] Examples of resins that can be used include products from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., JXTG Nippon Oil & Energy Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Co., Ltd.

[0034] The resin content is 30 parts by mass or more, preferably 40 parts by mass or more, per 100 parts by mass of the rubber component. The content is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 65 parts by mass or less. Within the above range, the effect tends to be more favorable.

[0035] When a large amount of silica is compounded, the temperature is likely to rise during high-speed driving, and abrasion resistance is significantly reduced. However, the present inventors have discovered that when a large amount of silica is compounded with a resin, abrasion resistance is drastically reduced when the tire temperature reaches near the softening point of the resin during high-speed driving. Furthermore, as a result of extensive research, the present inventors have discovered the following. (1) When the average styrene content of styrene-butadiene rubber is high, compounding a styrene-based resin makes the SBR and the resin compatible, making the tan δ peak high and sharp, and achieving both wet grip performance and abrasion resistance at high speeds. This improves the overall performance of abrasion resistance at high speeds and wet grip performance at high speeds. (2) When the average styrene content of styrene-butadiene rubber is low, compounding a terpene resin makes the SBR and resin compatible, making the tan δ peak higher and sharper, achieving both wet grip performance and abrasion resistance at high speeds, and improving the overall performance of abrasion resistance at high speeds and wet grip performance at high speeds.

[0036] To explain the above finding (1) more specifically, when the average styrene content of the styrene-butadiene rubber is 30% by mass or more, it is preferable to compound a styrene-based resin. The average styrene content of the SBR is preferably 35% by mass or more, more preferably 38% by mass or more, and is preferably 50% by mass or less, more preferably 47% by mass or less, and even more preferably 45% by mass or less. Within the above ranges, the effect tends to be more favorably obtained. The amount of the styrene resin is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 40 parts by mass or more, per 100 parts by mass of the rubber component. The amount is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 65 parts by mass or less. Within the above range, the effect tends to be more favorable.

[0037] To explain the above finding (2) more specifically, when the average styrene content of the styrene-butadiene rubber is less than 20% by mass, it is preferable to blend a terpene resin. Here, the average styrene content of the SBR is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. When it is within the above range, better effects tend to be obtained. The amount of the terpene resin is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 40 parts by mass or more, based on 100 parts by mass of the rubber component. The amount is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 65 parts by mass or less. Within the above range, the effect tends to be more favorably obtained.

[0038] By combining highly compatible resin types in accordance with the average styrene content of the SBR, it is possible to achieve both abrasion resistance at high speeds and wet grip performance at high speeds. This makes it possible to compound large amounts of white filler and resin, further improving the overall performance of abrasion resistance at high speeds and wet grip performance at high speeds.

[0039] Styrenic resins are polymers containing styrene-based monomers as constituent monomers, and examples thereof include polymers obtained by polymerizing styrene-based monomers as the main component (50% by mass or more). Specific examples include homopolymers obtained by polymerizing styrene-based monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.) individually, copolymers obtained by copolymerizing two or more styrene-based monomers, and copolymers of styrene-based monomers and other monomers copolymerizable therewith. These may be used alone or in combination of two or more.

[0040] Examples of other monomers include acrylonitriles such as acrylonitrile and methacrylonitrile, unsaturated carboxylic acids such as acrylics and methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, terpene compounds, conjugated dienes such as chloroprene and butadiene isoprene, olefins such as 1-butene and 1-pentene, α,β-unsaturated carboxylic acids or acid anhydrides thereof such as maleic anhydride, etc. These may be used alone or in combination of two or more.

[0041] Because the above-mentioned overall performance tends to be good, the styrene-based resin is preferably an α-methylstyrene-based resin (such as an α-methylstyrene homopolymer or a copolymer of α-methylstyrene and styrene) or a copolymer of a styrene-based monomer and a terpene compound, and more preferably an α-methylstyrene-based resin. Furthermore, the α-methylstyrene-based resin is more preferably a copolymer of α-methylstyrene and styrene.

[0042] The softening point of the styrene resin is preferably 60° C. or higher, more preferably 75° C. or higher, and is preferably 160° C. or lower, more preferably 120° C. or lower, and even more preferably 95° C. or lower. Within the above ranges, the effect tends to be more favorably obtained.

[0043] Terpene resins are polymers containing terpene compounds as constituent monomers, and examples thereof include polymers obtained by polymerizing terpene compounds as the main component (50% by mass or more). Specifically, polyterpene resins obtained by polymerizing terpene compounds, and aromatic modified terpene resins obtained by polymerizing terpene compounds and aromatic compounds can be used. Hydrogenated products of these resins can also be used. These resins can be used alone or in combination of two or more. Among these, polyterpene resins are preferred.

[0044] Polyterpene resin is a resin obtained by polymerizing terpene compounds. Terpene compounds are (C5H8) n The hydrocarbons and their oxygen-containing derivatives are represented by the following composition: monoterpenes (C 10 H16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 ), and examples thereof include α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0045] Examples of polyterpene resins include pinene resins, limonene resins, dipentene resins, and pinene / limonene resins, which are made from the above-mentioned terpene compounds. Among these, pinene resins are preferred. Pinene resins usually contain both α-pinene and β-pinene, which are isomers, but are classified into β-pinene resins containing β-pinene as the main component and α-pinene resins containing α-pinene as the main component, depending on the components contained.

[0046] Examples of aromatic modified terpene resins include terpene phenol resins made from terpene compounds and phenolic compounds as raw materials, and terpene styrene resins made from terpene compounds and styrene compounds as raw materials. Terpene phenol styrene resins made from terpene compounds, phenolic compounds, and styrene compounds as raw materials can also be used.

[0047] The softening point of the terpene resin is preferably 100° C. or higher, more preferably 120° C. or higher, and is preferably 160° C. or lower, more preferably 130° C. or lower. Within the above ranges, the effect tends to be more favorably obtained.

[0048] The rubber composition contains a white filler. Examples of white fillers include those commonly used in the rubber industry, such as silica, calcium carbonate, mica such as sericite, aluminum hydroxide, magnesium oxide, clay, talc, alumina, titanium oxide, and magnesium sulfate. These may be used alone or in combination of two or more. Of these, silica and aluminum hydroxide are preferred, and a combination of silica and aluminum hydroxide is more preferred.

[0049] The amount of the white filler (preferably the total amount of silica and aluminum hydroxide) is 150 parts by mass or more, preferably 155 parts by mass or more, more preferably 160 parts by mass or more, even more preferably 170 parts by mass or more, particularly preferably 180 parts by mass or more, and most preferably 185 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 200 parts by mass or less, more preferably 195 parts by mass or less, and even more preferably 190 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0050] Examples of silica include dry-process silica (silicic anhydride) and wet-process silica (hydrated silicic acid), but wet-process silica is preferred because it contains a large number of silanol groups. These may be used alone or in combination of two or more.

[0051] The nitrogen adsorption specific surface area (N2SA) of silica is 40m 2 / g or more, preferably 50m 2 / g or more, more preferably 100m 2 / g or more, more preferably 130m 2 / g or more, particularly preferably 160m 2 / g or more. In addition, the N2SA is preferably 500m 2 / g or less, more preferably 300m 2 / g or less, more preferably 250m 2 / g or less, particularly preferably 200m 2 Within the above range, the effect tends to be more favorably obtained. The N2SA of silica is a value measured by the BET method in accordance with ASTM D3037-81.

[0052] As silica, for example, products from Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Corporation, etc. can be used.

[0053] The content of silica, relative to 100 parts by mass of the rubber component, is preferably 100 parts by mass or more, more preferably 105 parts by mass or more, more preferably 110 parts by mass or more, even more preferably 120 parts by mass or more, particularly preferably 140 parts by mass or more, most preferably 150 parts by mass or more, and most preferably 155 parts by mass or more, and is preferably 180 parts by mass or less, more preferably 175 parts by mass or less, even more preferably 170 parts by mass or less, and particularly preferably 160 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0054] The aluminum hydroxide is not particularly limited, and any aluminum hydroxide commonly used in the tire industry can be used. These may be used alone or in combination of two or more.

[0055] The average primary particle size of aluminum hydroxide is preferably 0.6 μm or more, more preferably 0.7 μm or more. The average primary particle size of aluminum hydroxide is preferably 10 μm or less, more preferably 5 μm or less, even more preferably 1.3 μm or less, and particularly preferably 1.2 μm or less. Within the above ranges, better effects tend to be obtained. In this specification, the average primary particle size of aluminum hydroxide is a number average particle size, which is measured using a transmission electron microscope.

[0056] The content of aluminum hydroxide is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, based on 100 parts by mass of the rubber component. The content of aluminum hydroxide is preferably 60 parts by mass or less, more preferably 40 parts by mass or less. Within the above range, better effects tend to be obtained.

[0057] When the rubber composition contains silica, it is preferable that the rubber composition further contains a silane coupling agent. The silane coupling agent is not particularly limited, and examples thereof include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl-N Examples of such compounds include sulfide-based compounds such as N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane and 2-mercaptoethyltriethoxysilane; vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Commercially available products that can be used include those from Degussa, Momentive, Shin-Etsu Silicones, Tokyo Chemical Industry Co., Ltd., AZMAX Corporation, and Dow Corning Toray Co., Ltd. These may be used alone or in combination of two or more. Of these, sulfide-based silane coupling agents are more preferred because they tend to produce better effects.

[0058] The content of the silane coupling agent is preferably 3 parts by mass or more, more preferably 6 parts by mass or more, and is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 12 parts by mass or less, relative to 100 parts by mass of silica. When the content is within the above range, the effect tends to be better.

[0059] The rubber composition preferably contains carbon black. The carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. These may be used alone or in combination of two or more.

[0060] The nitrogen adsorption specific surface area (N2SA) of the carbon black is preferably 80 m 2 / g or more, more preferably 100m 2 / g or more, more preferably 120m 2 / g or more, and preferably 200m 2 / g or less, more preferably 180m 2 / g or less, more preferably 155m 2 Within the above range, there is a tendency for the effect to be better obtained. In this specification, the N2SA of carbon black is a value measured in accordance with JIS K6217-2:2001.

[0061] The maximum frequency diameter (Dmod) of the distribution curve of the Stokes equivalent diameter, which is an aggregate characteristic of carbon black, is preferably 120 nm or less, more preferably 80 nm or less, and although there is no particular lower limit, it is preferably 35 nm or more, more preferably 40 nm or more. When it is within the above range, better effects tend to be obtained. In this specification, the Dmod of carbon black is a value measured by the following method. A precisely weighed carbon black sample was added to a 20% aqueous ethanol solution containing a surfactant (Sigma Chemical's Nonidet P-40) to prepare a sample solution with a carbon black concentration of 0.01 wt%. This sample solution was dispersed for 5 minutes using an ultrasonic disperser (Ultrasonic Industries' Ultrasonic Generator USV-500V) at a frequency of 200 kHz and an output of 100 W to prepare a carbon black slurry. Ten milliliters of spin solution (pure water) and 1 milliliter of buffer solution (20 vol% aqueous ethanol solution) were then poured into a centrifugal particle size analyzer (Brook Haven Instruments' BI-DCP Particulate Sizer). Then, 1 milliliter of each of the prepared carbon black slurries was poured. The Stokes-equivalent diameter was measured by centrifugal sedimentation at 8,000 rpm, and a histogram of the frequency of occurrence relative to the Stokes-equivalent diameter was prepared. The intersection point of a line parallel to the Y axis passing through the peak (A) of the histogram and the X axis of the histogram is defined as C. The Stokes diameter at C is defined as the maximum frequency Stokes equivalent diameter (Dmod).

[0062] The dibutyl phthalate oil absorption (DBP) of the carbon black is preferably 50 ml / 100 g or more, more preferably 100 ml / 100 g or more. The DBP is preferably 200 ml / 100 g or less, more preferably 135 ml / 100 g or less. Within the above range, better effects tend to be obtained. The DBP of carbon black can be measured in accordance with JIS-K6217-4:2001.

[0063] As carbon black, for example, products manufactured by Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nichika Carbon Co., Ltd., Columbia Carbon Company, etc. can be used.

[0064] The amount of carbon black is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and is preferably 80 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 30 parts by mass or less, particularly preferably 20 parts by mass or less, and most preferably 15 parts by mass or less, per 100 parts by mass of the rubber component. Within the above ranges, better effects tend to be obtained.

[0065] The rubber composition preferably contains sulfur as a cross-linking agent (vulcanizing agent). Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. These may be used alone or in combination of two or more. Examples of vulcanizing agents other than sulfur include organic peroxides.

[0066] As sulfur, for example, products from Tsurumi Chemical Industry Co., Ltd., Karuizawa Iso Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanritsu Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

[0067] The content of the vulcanizing agent (preferably sulfur) is preferably 0.1 part by mass or more, more preferably 0.2 part by mass or more, even more preferably 0.3 part by mass or more, particularly preferably 0.5 part by mass or more, and is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 2 parts by mass or less, particularly preferably 1.5 parts by mass or less, per 100 parts by mass of the rubber component. Within the above ranges, better effects tend to be obtained.

[0068] The rubber composition preferably contains a vulcanization accelerator. Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, di-orthotolylguanidine, and orthotolylbiguanidine. These may be used alone or in combination of two or more. Among these, thiuram vulcanization accelerators and guanidine vulcanization accelerators are preferred, and a combination of thiuram vulcanization accelerators and guanidine vulcanization accelerators is more preferred.

[0069] As the vulcanization accelerator, for example, products manufactured by Kawaguchi Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., Rhein Chemie AG, etc. can be used.

[0070] The content of the vulcanization accelerator is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0071] The rubber composition may contain a softener. The softener is not particularly limited, but examples thereof include oil, liquid diene polymer, and ester-based plasticizer. These may be used alone or in combination of two or more. Among these, oil and ester-based plasticizer are preferred, and ester-based plasticizer is more preferred. It is also preferred to use oil and ester-based plasticizer in combination.

[0072] Examples of oils include process oils, vegetable oils, and mixtures thereof. Examples of process oils that can be used include paraffin-based process oils, aromatic process oils, and naphthenic process oils. Examples of vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. These may be used alone or in combination of two or more. Among these, process oils are preferred because they provide better effects, and aromatic process oils are more preferred.

[0073] As the oil, for example, products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H&R Co., Ltd., Toyokuni Oil Mills Co., Ltd., Showa Shell Sekiyu KK, Fuji Kosan Co., Ltd., etc. can be used.

[0074] The amount of oil per 100 parts by mass of the rubber component is preferably at least 5 parts by mass, more preferably at least 15 parts by mass, even more preferably at least 30 parts by mass, particularly preferably at least 50 parts by mass, and is preferably at most 150 parts by mass, more preferably at most 145 parts by mass, even more preferably at most 140 parts by mass, particularly preferably at most 120 parts by mass, and most preferably at most 100 parts by mass. Within the above ranges, the effect tends to be better obtained. In this specification, the oil content includes the amount of oil contained in rubber (oil-extended rubber).

[0075] The liquid diene polymer is a diene polymer that is in a liquid state at room temperature (25°C). The weight average molecular weight (Mw) of the liquid diene polymer is preferably 3.0×10 3 More preferably, 4.0 × 10 3 or more, preferably 1.0 × 10 5 Less than or equal to 1.5 × 10 4 Within the above range, the effect tends to be more favorably obtained.

[0076] Examples of liquid diene polymers include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), and liquid styrene-isoprene copolymer (liquid SIR). These may be used alone or in combination of two or more. Among these, liquid SBR is preferred because it provides the most suitable effect.

[0077] As the liquid diene polymer, for example, products manufactured by Sartomer Co., Ltd., Kuraray Co., Ltd., etc. can be used.

[0078] As the ester-based plasticizer, for example, one containing at least one compound selected from the group consisting of phosphate esters, phthalate esters, aliphatic polybasic acid esters, trimellitate esters, acetate esters, and ricinoleate esters can be suitably used. These may be used alone or in combination of two or more. Among them, phosphate esters, phthalate esters, and aliphatic polybasic acid esters are preferred because they provide better effects. Furthermore, aliphatic polybasic acid esters are suitable because they can reduce the amount of phosphorus used.

[0079] The SP value of the above compound is preferably 8.3 or more, more preferably 8.5 or more. The SP value is preferably 9.5 or less, more preferably 9.0 or less, and even more preferably 8.8 or less. By adjusting the SP value within the above range, compatibility with diene rubbers such as SBR is ensured, and the effect tends to be more favorably obtained. Here, the SP value means the solubility parameter calculated using the Hansen formula.

[0080] The solidification temperature of the compound is preferably −100° C. or higher, more preferably −80° C. or higher. The solidification temperature is preferably −10° C. or lower, more preferably −15° C. or lower. When the solidification temperature is within the above range, better effects tend to be obtained. In this specification, the solidification temperature is a value measured by the following method. The sample was sealed in an aluminum cell, and the aluminum cell was inserted into the sample holder of a differential scanning calorimeter (DSC-60A, manufactured by Shimadzu Corporation). The sample holder was then heated to 150°C at a rate of 10°C / min under a nitrogen atmosphere while observing the endothermic peak, which was taken as the freezing point.

[0081] As the phosphate ester, known phosphate ester-based plasticizers such as mono-, di-, or triesters of phosphoric acid with a monoalcohol having 1 to 12 carbon atoms or its (poly)oxyalkylene adduct can be used. Specific examples include tris(2-ethylhexyl) phosphate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, and 2-ethylhexyl diphenyl phosphate.

[0082] As the phthalate ester, a known phthalate ester-based plasticizer can be used, such as a diester of phthalic acid with an alcohol having about 1 to 13 carbon atoms. Specific examples include bis(2-ethylhexyl) phthalate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisodecyl phthalate, butyl benzyl phthalate, diisononyl phthalate, and ethyl phthalyl ethyl glycolate.

[0083] Examples of aliphatic polybasic acid esters include aliphatic dibasic acid esters, aliphatic tribasic acid esters, etc. Among these, aliphatic dibasic acid esters such as adipates, azelates, sebacates, maleates, and fumarates are preferred in terms of achieving better effects.

[0084] Among these aliphatic dibasic acid esters, the compound represented by the following formula (1) can be particularly preferably used. [ka] [In formula (1), R 11represents a divalent saturated or unsaturated hydrocarbon group. 12 and R 13 are the same or different and are branched or unbranched alkyl groups, or -(R 14 -O) n -R 15 (n R 14 are the same or different and represent a branched or unbranched alkylene group. 15 represents a branched or unbranched alkyl group. n represents an integer. represents a group represented by the formula:

[0085] R 11 The divalent saturated or unsaturated hydrocarbon group may be branched or unbranched, and examples thereof include an alkylene group, an alkenylene group, an arylene group, etc. The saturated or unsaturated hydrocarbon group preferably has 1 to 10 carbon atoms, and more preferably 6 to 10 carbon atoms. Specific examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, etc.; examples of the alkenylene group include a vinylene group, a 1-propenylene group, a 2-propenylene group, etc.; and examples of the arylene group include a phenylene group, a tolylene group, a xylylene group, etc.

[0086] R 12 and R 13 With regard to the above, the number of carbon atoms in the branched or unbranched alkyl group is preferably 1 to 15, the lower limit is more preferably 4 or more, and the upper limit is more preferably 10 or less. Specific examples 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, a heptyl group, an octyl group, an ethylhexyl group, a nonyl group, and a decyl group.

[0087] R 12 and 13 No-(R 14 -O) n -R 15 For the group represented by R 14 The branched or unbranched alkylene group preferably has 1 to 3 carbon atoms. 15The branched or unbranched alkyl group preferably has 1 to 10 carbon atoms, with the lower limit being more preferably 2 or more and the upper limit being more preferably 6 or less. Specific examples of the alkylene group and the alkyl group include those similar to those mentioned above. The integer n is preferably 1 to 10, more preferably 1 to 5, and even more preferably 1 to 3.

[0088] Among them, R is the most suitable because it provides the best results. 11 is preferably an alkylene group, and R 12 and 13 At least one of the groups is preferably a branched alkyl group, and it is more preferable that both of them are such groups.

[0089] Suitable examples of the aliphatic dibasic acid ester represented by the formula (1) include bis(2-ethylhexyl) sebacate, di-n-butyl adipate, diisobutyl adipate, and the -(R 14 -O) n -R 15 and bis(alkoxyalkoxyalkyl)adipates having a group represented by the following formula: These may be used alone or in combination of two or more kinds.

[0090] As the trimellitic acid ester, a known trimellitic acid ester-based plasticizer can be used, such as a triester of trimellitic acid and a saturated aliphatic alcohol having 8 to 13 carbon atoms. Specific examples include tri-2-ethylhexyl trimellitate, tri-n-octyl trimellitate, tridecyl trimellitate, triisodecyl trimellitate, and di-n-octyl-n-decyl trimellitate.

[0091] As the acetate ester, known acetate ester-based plasticizers such as esters of acetic acid and mono- or polyglycerin can be used. Specific examples include glyceryl triacetate, 2-ethylhexyl acetate, and polyglycerin acetate esters having a degree of polymerization of 2 to 4 and an acetylation rate of 50 to 100%.

[0092] Examples of ricinoleic acid esters include known ricinoleic acid ester-based plasticizers, such as alkyl acetylricinoleates (alkyl group: carbon number 1 to 10) such as methyl acetylricinoleate and butyl acetylricinoleate.

[0093] The ester-based plasticizer may contain other components in addition to the above compounds, such as known plasticizers other than the above compounds, and polyalkylene glycol alkyl ethers such as diethylene glycol monobutyl ether.

[0094] The content of the compound in 100% by mass of the ester-based plasticizer is preferably 80% by mass or more, more preferably 90% by mass or more, and may be 100% by mass. By blending the compound in the above content, the effect tends to be more favorably obtained.

[0095] Examples of the ester-based plasticizer include tris(2-ethylhexyl)phosphate (TOP, freezing temperature −70° C. or lower, flash point 204° C., SP value 8.1, Mw 435), bis(2-ethylhexyl)sebacate (DOS, freezing temperature −62° C., flash point 222° C., SP value 8.4, Mw 427), bis(2-ethylhexyl)phthalate (DOP, freezing temperature −51° C., flash point 218° C., SP value 8.9, Mw 391), and bis[2-(2-butoxyethoxyethyl)ethyl]adipate (BXA, freezing temperature −19° C., flash point 207° C., SP value 8.7, Mw 435). Among these, DOS, TOP, and BXA are preferred because of their excellent compatibility with rubber components, flash points of 200° C. or higher, and weight-average molecular weights of 400 or higher.

[0096] The content of the ester plasticizer is, per 100 parts by mass of the rubber component, preferably 3 parts by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, even more preferably 30 parts by mass or less, particularly preferably 25 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0097] The content of the softener (preferably the total content of the oil and the ester-based plasticizer) per 100 parts by mass of the rubber component is preferably 8 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, particularly preferably 50 parts by mass or more, and most preferably 70 parts by mass or more, and is preferably 200 parts by mass or less, more preferably 170 parts by mass or less, even more preferably 140 parts by mass or less, particularly preferably 120 parts by mass or less, and most preferably 100 parts by mass or less. Within the above ranges, better effects tend to be obtained. In this specification, the content of the softener also includes the amount of oil contained in the rubber (oil-extended rubber).

[0098] The resin content / softener content (preferably the total content of oil and ester-based plasticizer) is preferably 0.2 or more, more preferably 0.3 or more, even more preferably 0.4 or more, even more preferably 0.5 or more, particularly preferably 0.6 or more, and most preferably 0.7 or more, and although there is no particular upper limit, it is preferably 1.0 or less, more preferably 0.9 or less, and even more preferably 0.8 or less. Within the above range, better effects tend to be obtained.

[0099] The ratio of (resin content + softener content (preferably the total content of oil and ester-based plasticizer)) / white filler content is preferably 1.05 or less, more preferably 0.95 or less, even more preferably 0.90 or less, and particularly preferably 0.85 or less. There is no particular lower limit, but it is preferably 0.40 or more, more preferably 0.50 or more, even more preferably 0.60 or more, particularly preferably 0.70 or more, and most preferably 0.75 or more. Within the above range, better effects tend to be obtained. It is also preferable that the resin content / softener content (preferably the total content of oil and ester-based plasticizer) be within the above range, and that the (resin content + softener content (preferably the total content of oil and ester-based plasticizer)) / white filler content be within the above range, which tends to produce better effects. In this specification, the content of each component means the content relative to 100 parts by mass of the rubber component.

[0100] The rubber composition may contain wax. The wax is not particularly limited, and examples thereof include petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as vegetable wax and animal wax; and synthetic waxes such as polymers of ethylene, propylene, etc. These may be used alone or in combination of two or more. Of these, petroleum waxes are preferred, and paraffin wax is more preferred.

[0101] As the wax, for example, products from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., etc. can be used.

[0102] The amount of wax per 100 parts by mass of the rubber component is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, and is preferably 20 parts by mass or less, more preferably 10 parts by mass or less. Within the above ranges, better effects tend to be obtained.

[0103] The rubber composition may contain an antioxidant. Examples of the antioxidant include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, and N,N'-di-2-naphthyl-p-phenylenediamine. Examples of antioxidants include p-phenylenediamine-based antioxidants such as quinoline; quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. These antioxidants may be used alone or in combination of two or more. Among these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, and p-phenylenediamine-based antioxidants are more preferred.

[0104] As the antioxidant, for example, products available from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis, etc. can be used.

[0105] The content of the antioxidant is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, per 100 parts by mass of the rubber component. Within the above ranges, the effect tends to be more favorable.

[0106] The rubber composition may contain stearic acid. As the stearic acid, conventionally known ones can be used, for example, products available from NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc.

[0107] The content of stearic acid is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the rubber component. When the content is within the above range, better effects tend to be obtained.

[0108] The rubber composition may contain zinc oxide. As the zinc oxide, conventionally known products can be used, for example, products from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

[0109] The amount of zinc oxide per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less. Within the above ranges, better effects tend to be obtained.

[0110] In addition to the above components, the rubber composition may further contain additives commonly used in the tire industry. The content of these additives is preferably 0.1 to 200 parts by mass per 100 parts by mass of the rubber component.

[0111] The rubber composition can be produced, for example, by kneading the components using a rubber kneading device such as an open roll or a Banbury mixer, followed by vulcanization.

[0112] As for kneading conditions, in the base kneading step in which additives other than the vulcanizing agent and vulcanization accelerator are kneaded, the kneading temperature is usually 100 to 180°C, preferably 120 to 170°C. In the finish kneading step in which the vulcanizing agent and vulcanization accelerator are kneaded, the kneading temperature is usually 120°C or lower, preferably 80 to 110°C. Furthermore, the composition kneaded with the vulcanizing agent and vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 140 to 190°C, preferably 150 to 185°C. The vulcanization time is usually 5 to 15 minutes.

[0113] The rubber composition can be used (as a rubber composition for tires) for tire components such as treads (cap treads), sidewalls, base treads, undertreads, clinches, bead apexes, breaker cushion rubbers, carcass cord covering rubbers, insulations, chafers, inner liners, and side reinforcing layers of run-flat tires, among others. Among these, it is particularly suitable for use in treads.

[0114] The tire (pneumatic tire, etc.) of the present invention is manufactured by a conventional method using the above rubber composition. That is, the rubber composition, to which various additives are optionally blended, is extruded in an unvulcanized state to match the shapes of the tire components (particularly the tread (cap tread)), molded in a conventional method on a tire building machine, and laminated together with other tire components to form an unvulcanized tire, which is then heated and pressurized in a vulcanizer to manufacture the tire.

[0115] The tire is not particularly limited, and examples thereof include pneumatic tires, solid tires, airless tires, etc. Among these, pneumatic tires are preferred.

[0116] The above-mentioned tires are suitably used as passenger car tires, large passenger car tires, large SUV tires, truck and bus tires, motorcycle tires, racing tires, studless tires (winter tires), all-season tires, run-flat tires, aircraft tires, mining tires, etc. Among these, the above-mentioned tires are more suitably used as racing tires, particularly wet racing tires for wet roads that can exhibit good grip performance on wet road surfaces. In this specification, racing tires refer to tires used in competitions such as karts. [Example]

[0117] The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[0118] The various chemicals used in the examples and comparative examples will be collectively described below. SBR1: T4850 manufactured by Asahi Kasei Corporation (S-SBR, styrene content: 40 mass%, oil-extended rubber containing 50 mass parts of oil per 100 mass parts of rubber solids) SBR2: SL7518 manufactured by LANXESS (S-SBR, styrene content: 18% by mass, oil-extended rubber containing 15 parts by mass of oil per 100 parts by mass of rubber solids) BR: BR150B manufactured by Ube Industries, Ltd. Silica: Uratosil VN3 (N2SA: 175 ml) manufactured by Evonik Degussa 2 / g) Silane coupling agent: Evonik Degussa Si69 (sulfide-based silane coupling agent) Aluminum hydroxide: Hijilite H-43 (average primary particle size: 1 μm) manufactured by Showa Denko K.K. Carbon black: SEA ST 9 (SAF, N2SA: 142 ml) manufactured by Tokai Carbon Co., Ltd. 2 / g, DBP: 115ml / 100g) Oil: H&R VIVATEC 500 (TDAE oil) Styrene-based resin: Sylvatraxx 4401 (α-methylstyrene-based resin (copolymer of α-methylstyrene and styrene), softening point: 85°C) manufactured by Arizona Chemical Co. Terpene resin: TR7125 (softening point: 125°C, polyterpene) manufactured by Arizona Chemical Co. Anti-aging agent: Antigen 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd. Wax: Sunnock N manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Ester-based plasticizer: DOS (bis(2-ethylhexyl) sebacate (aliphatic dibasic acid ester, solidification temperature -62°C, SP value 8.5) manufactured by Daihachi Chemical Co., Ltd. Stearic acid: NOF Corporation's "Tsubaki" stearic acid Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Metals Co., Ltd. Sulfur: Powdered sulfur manufactured by Karuizawa Sulfur Co., Ltd. Vulcanization accelerator DPG: Noccela D (N,N'-diphenylguanidine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator TOT: Noccela TOT-N (tetrakis(2-ethylhexyl)thiuram disulfide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0119] Examples and Comparative Examples According to the formulation shown in Table 1, chemicals other than sulfur and vulcanization accelerator were kneaded for 5 minutes at 150°C using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd. to obtain a kneaded mixture. Next, sulfur and vulcanization accelerator were added to the obtained kneaded mixture, and the mixture was kneaded for 5 minutes at 80°C using an open roll to obtain an unvulcanized rubber composition. Furthermore, the obtained unvulcanized rubber composition was molded into the shape of a cap tread and laminated together with other tire components to produce an unvulcanized tire. This was then vulcanized for 10 minutes at 170°C to obtain a test tire (size: 205 / 65R15).

[0120] The test tires obtained were evaluated as follows, and the results are shown in Table 1.

[0121] <Wet grip performance at high speeds> The test tire was mounted on a 2000cc domestic FR vehicle, and the vehicle was driven 10 laps on a wet asphalt test course (high-speed driving: average speed of 120km / h). The test driver performed a sensory evaluation of the grip performance during the best lap, and the result was expressed as an index, with Comparative Example 1 being set at 100. The higher the index, the better the wet grip performance during high-speed driving.

[0122] <Wear resistance at high speeds> After the wet grip performance test, the remaining groove depth of the tire tread rubber was measured (15 mm when new) and the average value for four tires was calculated. The remaining groove depth of Comparative Example 1 was expressed as an index, with 100 being the remaining groove depth. A larger value indicates better wear resistance during high-speed driving.

[0123] [Table 1]

[0124] From Table 1, it can be seen that the examples containing 150 parts by mass or more of white filler and 30 parts by mass or more of resin per 100 parts by mass of rubber component containing styrene-butadiene rubber have excellent abrasion resistance during high-speed driving and overall performance of wet grip performance during high-speed driving (expressed as the sum of two indices: abrasion resistance during high-speed driving and wet grip performance during high-speed driving).

Claims

1. A rubber composition for a tire, comprising 150 parts by mass or more of a white filler and 30 parts by mass or more and 80 parts by mass or less of a resin relative to 100 parts by mass of a rubber component containing a styrene-butadiene rubber, The rubber composition contains 100 parts by mass or more of silica per 100 parts by mass of the rubber component, The rubber composition contains 20 parts by mass or more of a styrene-based resin per 100 parts by mass of the rubber component, the styrene-butadiene rubber has an average styrene content of 30% by mass or more, The rubber composition for tires has a styrene-butadiene rubber content of 90% by mass or more based on 100% by mass of the rubber component.

2. A rubber composition for a tire, comprising 150 parts by mass or more of a white filler and 30 parts by mass or more and 80 parts by mass or less of a resin relative to 100 parts by mass of a rubber component containing a styrene-butadiene rubber, The rubber composition contains 100 parts by mass or more of silica per 100 parts by mass of the rubber component, The rubber composition contains a terpene resin in an amount of 20 parts by mass or more per 100 parts by mass of the rubber component, the styrene-butadiene rubber has an average styrene content of less than 20% by mass, The rubber composition for tires has a styrene-butadiene rubber content of 90% by mass or more based on 100% by mass of the rubber component.

3. 3. The rubber composition for tires according to claim 1, comprising 120 parts by mass or more of silica per 100 parts by mass of the rubber component.

4. 3. The rubber composition for tires according to claim 1, comprising 150 parts by mass or more of silica per 100 parts by mass of the rubber component.

5. The rubber composition for a tire according to any one of claims 1 to 4, further comprising a sulfide-based silane coupling agent.

6. The rubber composition for a tire according to any one of claims 1 to 5, further comprising an ester-based plasticizer.

7. The rubber composition for a tire according to any one of claims 1 to 6, which contains aluminum hydroxide.

8. A tire having a tread made using the rubber composition according to any one of claims 1 to 7.

Images