Rubber composition for tires and tires

Abstract

To provide a tire rubber composition that can improve the overall performance of fuel economy at room temperature and low temperature, and provide a tire.SOLUTION: A tire rubber composition contains a rubber component including styrene-butadiene rubber, butadiene rubber and isoprene rubber, silica, a mercapto-based silane coupling agent, and carbon black, with the trans content+vinyl content of the butadiene rubber>the content of the carbon black.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Various methods for improving fuel economy have been studied in the past (see, for example, Patent Document 1). However, improvements in fuel economy at normal and low temperatures (reduction of rolling resistance) have not been sufficiently studied. [Prior art documents] [Patent documents]

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

[0004] An object of the present invention is to provide a rubber composition for a tire and a tire that can solve the above problems and improve the overall performance of fuel economy at normal and low temperatures. [Means for solving the problem]

[0005] The present invention relates to a rubber composition for tires, which contains a rubber component including a styrene-butadiene rubber, a butadiene rubber, and an isoprene-based rubber, silica, a mercapto-based silane coupling agent, and carbon black, and the trans content of the butadiene rubber plus the vinyl content is greater than the content of the carbon black.

[0006] It is preferable that the cis content of the butadiene rubber is less than the silica content.

[0007] The average particle size of the silica is preferably 16 nm or less.

[0008] The carbon black has a cetyltrimethylammonium bromide adsorption specific surface area of ​​110 m 2 / g or more is preferable.

[0009] The rubber composition preferably contains sulfur, and the sulfur content / isoprene-based rubber content is greater than 0.50.

[0010] The total amount of styrene in the rubber component is preferably 18% by mass or less.

[0011] The rubber composition preferably contains a dialkyldithiophosphate compound.

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

[0013] The present invention relates to a rubber composition for tires that contains a rubber component including styrene-butadiene rubber, butadiene rubber, and isoprene-based rubber, silica, a mercapto-based silane coupling agent, and carbon black, and the trans content of the butadiene rubber plus the vinyl content is greater than the carbon black content, thereby improving the overall fuel economy at normal and low temperatures. DETAILED DESCRIPTION OF THE INVENTION

[0014] The rubber composition for tires of the present invention contains a rubber component including styrene-butadiene rubber, butadiene rubber, and isoprene-based rubber, silica, a mercapto-based silane coupling agent, and carbon black, and the trans amount of the butadiene rubber plus the vinyl amount is greater than the carbon black content.

[0015] The reason why the above-mentioned effects can be obtained with the above rubber composition is presumed to be as follows. The rubber composition contains styrene-butadiene rubber, butadiene rubber, isoprene rubber, silica, a mercapto-silane coupling agent, and carbon black, and satisfies the relationship of trans content + vinyl content of butadiene rubber > carbon black content, which reduces the amount of trans and vinyl moieties of the highly mobile butadiene rubber that bond with carbon black and makes it easier for them to bond with silica, thereby reducing heat buildup and improving fuel economy. Furthermore, the highly reactive mercapto silane coupling agent promotes hydrophobicity of the silica surface, resulting in uniform dispersion of the silica and reducing the temperature dependency of heat buildup (tan δ). It is believed that the combination of these effects significantly improves the overall fuel economy at normal and low temperatures.

[0016] The rubber composition contains a rubber component. Here, the rubber component is a component that contributes to crosslinking, and generally has a weight average molecular weight (Mw) of 10,000 or more.

[0017] The weight average molecular weight of the rubber component is preferably 50,000 or more, more preferably 150,000 or more, and even more preferably 200,000 or more, and is preferably 2,000,000 or less, more preferably 1,700,000 or less, and even more preferably 1,400,000 or less. Within the above ranges, the effect tends to be more favorably obtained.

[0018] In this specification, the weight average molecular weight (Mw) can be determined in terms of standard polystyrene based on measurements obtained using a gel permeation chromatograph (GPC) (GPC-8000 series, manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M, manufactured by Tosoh Corporation).

[0019] The total styrene content in the rubber component is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 18% by mass or less, and is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. Within the above ranges, the effect tends to be more favorably obtained.

[0020] Here, the total styrene amount in the rubber component is the total content of styrene moieties contained in the entire rubber component (unit: mass%) and can be calculated by Σ (content of each rubber component × styrene amount in each rubber component / 100). For example, if 100% by mass of the rubber component contains 85% by mass of SBR with a styrene content of 40% by mass, 5% by mass of SBR with a styrene content of 25% by mass, and 10% by mass of BR with a styrene content 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).

[0021] The total vinyl content in the rubber component is preferably 35% by mass or less, more preferably 30% by mass or less, and even more preferably 28% by mass or less, and is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more. Within the above ranges, the effect tends to be more favorably obtained.

[0022] Here, the total vinyl content in the rubber component is the total content (unit: mass%) of vinyl moieties contained in the entire rubber component, and can be calculated by Σ (content of each rubber component × vinyl content in each rubber component / 100). For example, if 100 mass% of the rubber component contains 85 mass% SBR with a vinyl content of 30 mass%, 5 mass% SBR with a vinyl content of 20 mass%, and 10 mass% BR with a vinyl content of 10 mass%, the total vinyl content in the rubber component is 27.5 mass% (= 85 × 30 / 100 + 5 × 20 / 100 + 10 × 10 / 100).

[0023] From the viewpoint of overall performance such as fuel economy at normal and low temperatures, it is preferable that the total vinyl content in the rubber component of the rubber composition is greater than or equal to the total styrene content in the rubber component.

[0024] The ratio of the total vinyl content in the rubber component to the total styrene content in the rubber component is preferably 1.2 or more, more preferably 1.4 or more, and even more preferably 1.6 or more, and is preferably 3.5 or less, more preferably 2.5 or less, and even more preferably 2.0 or less. Within the above ranges, the effect tends to be more favorable.

[0025] The styrene content and vinyl content in each rubber component can be measured by nuclear magnetic resonance (NMR) spectroscopy. In the examples of this specification, the total styrene amount and the total vinyl amount in the rubber component are calculated according to the above-mentioned formula, but they may also be analyzed from the tire using, for example, a pyrolysis gas chromatograph mass spectrometer (Py-GC / MS) or the like.

[0026] The rubber composition contains, as rubber components, styrene butadiene rubber (SBR), butadiene rubber (BR), and isoprene-based rubber.

[0027] The SBR is not particularly limited, and examples thereof include emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc. Commercially available products include those from Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, and Zeon Corporation.

[0028] The styrene content of the SBR is preferably 10% by mass or more, more preferably 25% by mass or more, and even more preferably 35% by mass or more, and is preferably 60% by mass or less, more preferably 50% 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.

[0029] The vinyl content of the SBR is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. When it is within the above range, the effect tends to be more favorable.

[0030] The styrene content and vinyl content of the SBR mentioned above refer to the styrene content and vinyl content of the SBR when there is one type of SBR, and refer to the average styrene content and average vinyl content when there are multiple types of SBR. The average styrene amount of SBR can be calculated by {Σ(content of each SBR × styrene amount of each SBR)} / total content of all SBRs. For example, when 100% by mass of the rubber component contains 85% by mass of SBR with a styrene amount of 40% by mass and 5% by mass of SBR with a styrene amount of 25% by mass, the average styrene amount of the SBR is 39.2% by mass (=(85×40+5×25) / (85+5)). Similarly, the average vinyl content of the SBRs can be calculated by {Σ(content of each SBR × vinyl content of each SBR)} / total content of all SBRs. For example, when 100% by mass of the rubber component contains 85% by mass of SBRs with a vinyl content of 30% by mass and 5% by mass of SBRs with a vinyl content of 20% by mass, the average vinyl content of the SBRs is 29.4% by mass (=(85×30+5×20) / (85+5)).

[0031] The amount of SBR in 100% by mass of the rubber component is preferably 15% by mass or more, more preferably 45% by mass or more, and even more preferably 55% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 65% ​​by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0032] The BR is not particularly limited, and can be a high-cis BR, a low-cis BR, a BR containing syndiotactic polybutadiene crystals, etc. Commercially available products include those from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Zeon Corporation, etc.

[0033] The cis amount (cis content) of the BR is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, and is preferably 80% by mass or less, more preferably 75% by mass or less, and preferably 70% 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.

[0034] The vinyl content of the BR is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, and is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less. Within the above ranges, the effect tends to be more favorably obtained. The vinyl content of BR can be measured by infrared absorption spectroscopy.

[0035] The trans content of BR is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. Within the above ranges, the effect tends to be more favorably obtained. The trans content of BR can be measured by infrared absorption spectroscopy.

[0036] The above-mentioned cis content, vinyl content, and trans content of BR mean the cis content, vinyl content, and trans content of the BR when there is one type of BR, and mean the average cis content, average vinyl content, and average trans 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)). Similarly, the average vinyl content of BR can be calculated by {Σ(content of each BR × vinyl content of each BR)} / total content of all BRs, and the average trans content of BR can be calculated by {Σ(content of each BR × trans content of each BR)} / total content of all BRs.

[0037] The BR content in 100% by mass of the rubber component is preferably 15% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. Within the above ranges, the effects tend to be more favorably obtained.

[0038] 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 and IR are preferred.

[0039] The content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 1% by mass or more, more preferably 2% by mass or more, and is preferably 10% by mass or less, more preferably 6% by mass or less, and even more preferably 4% by mass or less. Within the above ranges, the effects tend to be more favorably obtained.

[0040] Usable rubber components other than SBR, BR, and isoprene-based rubber 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. Of these, BR is preferred.

[0041] The rubber component may be modified to introduce a functional group that interacts with a filler such as silica. Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, 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 the 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), and an alkoxysilyl group (preferably an alkoxysilyl group having 1 to 6 carbon atoms) are preferred.

[0042] Specific examples of compounds (modifiers) having the above functional groups include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane.

[0043] The rubber composition contains silica. Examples of silica include dry-process silica (silicic anhydride) and wet-process silica (hydrated silicic acid), with wet-process silica being preferred because it contains a large number of silanol groups. Commercially available products include those from EVONIK, Tosoh Silica Corporation, Solvay Japan, and Tokuyama Corporation. These may be used alone or in combination of two or more.

[0044] The average particle size of the silica is preferably 20 nm or less, more preferably 17 nm or less, even more preferably 16 nm or less, particularly preferably 15 nm or less, and is preferably 6 nm or more, more preferably 9 nm or more, even more preferably 12 nm or more. Within the above ranges, the effect tends to be more favorable.

[0045] In this specification, the average particle size of silica is measured by observation with a transmission electron microscope (TEM). Specifically, silica particles are photographed with a transmission electron microscope, and the particle size is the diameter of the sphere if the particle shape is spherical, the minor axis if the particle shape is needle-like or rod-like, or the average particle diameter from the center if the particle shape is irregular, and the average particle diameter of 100 fine particles is the average particle size.

[0046] The amount of silica per 100 parts by mass of the rubber component is preferably at least 40 parts by mass, more preferably at least 50 parts by mass, and even more preferably at least 60 parts by mass, and is preferably at most 100 parts by mass, more preferably at most 85 parts by mass, even more preferably at most 70 parts by mass, and particularly preferably at most 65 parts by mass. Within the above ranges, the effect tends to be more favorably obtained.

[0047] From the viewpoint of overall performance such as fuel economy at normal and low temperatures, it is preferable that the cis content of BR in the rubber composition is less than the silica content.

[0048] The cis ratio of silica content to BR is preferably 1.03 or more, and is preferably 1.50 or less, more preferably 1.30 or less, and even more preferably 1.10 or less. Within the above ranges, the effect tends to be more favorable.

[0049] In these relationships, the silica content is the content (unit: parts by mass) relative to 100 parts by mass of the rubber component. The cis content of BR is the cis content (unit: mass%) in 100% by mass of BR, and when there are multiple types of BR, it is the average cis content.

[0050] In the rubber composition, the ratio of the silica content to the isoprene-based rubber content is preferably 10 or more, more preferably 15 or more, and even more preferably 20 or more, and is preferably 35 or less, more preferably 28 or less, and even more preferably 24 or less. 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 isoprene-based rubber content is the content (unit: % by mass) in 100% by mass of the rubber component.

[0051] The rubber composition contains a mercapto-based silane coupling agent. The mercapto-based silane coupling agent is not particularly limited, and examples thereof include 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and the like. In addition to the above-mentioned compounds having a mercapto group, compounds having a structure in which the mercapto group is protected by a protecting group (for example, a compound represented by the following formula (S1)) can also be used as the mercapto-based silane coupling agent.

[0052] Particularly suitable mercapto-based silane coupling agents include silane coupling agents represented by the following formula (S1) and silane coupling agents containing a bonding unit A represented by the following formula (I) and a bonding unit B represented by the following formula (II). [ka] (In the formula, R 1001 -Cl, -Br, -OR 1006 , -O(O=)CR 1006 , -ON=CR 1006 R 1007 , -NR 1006 R 1007 and-(OSiR 1006 R 1007 ) h (OSiR 1006 R 1007 R 1008 a monovalent group (R 1006 , R 1007 and R1008 may be the same or different, and each represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, and h has an average value of 1 to 4; 1002 is R 1001 , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, R 1003 is -[O(R 1009 O) j ]-group(R 1009 is an alkylene group having 1 to 18 carbon atoms, and j is an integer of 1 to 4. 1004 is a divalent hydrocarbon group having 1 to 18 carbon atoms, R 1005 represents a monovalent hydrocarbon group having 1 to 18 carbon atoms, and x, y, and z are numbers that satisfy the relationships: x+y+2z=3, 0≦x≦3, 0≦y≦2, 0≦z≦1. [ka] [ka] (wherein v is an integer of 0 or more, and w is an integer of 1 or more. R 11 R represents hydrogen, halogen, a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, a branched or unbranched alkynyl group having 2 to 30 carbon atoms, or an alkyl group in which the terminal hydrogen atom has been substituted with a hydroxyl group or a carboxyl group. 12 represents a branched or unbranched alkylene group having 1 to 30 carbon atoms, a branched or unbranched alkenylene group having 2 to 30 carbon atoms, or a branched or unbranched alkynylene group having 2 to 30 carbon atoms. 11 and R 12 may form a ring structure with

[0053] In formula (S1), R 1005 , R 1006 , R 1007 and R 1008 are each independently a group selected from the group consisting of a linear, cyclic or branched alkyl group, an alkenyl group, an aryl group and an aralkyl group having 1 to 18 carbon atoms. 1002When R is a monovalent hydrocarbon group having 1 to 18 carbon atoms, it is preferably a group selected from the group consisting of a linear, cyclic, or branched alkyl group, an alkenyl group, an aryl group, and an aralkyl group. 1009 R is preferably a linear, cyclic or branched alkylene group, and is particularly preferably a linear one. 1004 Examples of R include alkylene groups having 1 to 18 carbon atoms, alkenylene groups having 2 to 18 carbon atoms, cycloalkylene groups having 5 to 18 carbon atoms, cycloalkylalkylene groups having 6 to 18 carbon atoms, arylene groups having 6 to 18 carbon atoms, and aralkylene groups having 7 to 18 carbon atoms. The alkylene groups and alkenylene groups may be either linear or branched, and the cycloalkylene groups, cycloalkylalkylene groups, arylene groups, and aralkylene groups may have a functional group such as a lower alkyl group on the ring. 1004 As the alkylene group, an alkylene group having 1 to 6 carbon atoms is preferred, and a linear alkylene group such as a methylene group, ethylene group, trimethylene group, tetramethylene group, pentamethylene group, or hexamethylene group is particularly preferred.

[0054] R in formula (S1) 1002 , R 1005 , R 1006 , R 1007 and R 1008 Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a cyclopentyl group, a cyclohexyl group, a vinyl group, a propenyl group, an allyl group, a hexenyl group, an octenyl group, a cyclopentenyl group, a cyclohexenyl group, a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a benzyl group, a phenethyl group, and a naphthylmethyl group. R in formula (S1) 1009 Examples of the linear alkylene group include a methylene group, an ethylene group, an n-propylene group, an n-butylene group, and a hexylene group, and examples of the branched alkylene group include an isopropylene group, an isobutylene group, and a 2-methylpropylene group.

[0055] Specific examples of the silane coupling agent represented by formula (S1) include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, 3-lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexanoylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthioethyltrimethoxysilane, 2-decanoylthioethyltrimethoxysilane, and 2-lauroylthioethyltrimethoxysilane. These may be used alone or in combination of two or more. Among these, 3-octanoylthiopropyltriethoxysilane is particularly preferred.

[0056] In the silane coupling agent containing the bond unit A represented by formula (I) and the bond unit B represented by formula (II), the content of the bond unit A is preferably 30 mol% or more, more preferably 50 mol% or more, and preferably 99 mol% or less, more preferably 90 mol% or less. The content of the bond unit B is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 10 mol% or more, and preferably 70 mol% or less, more preferably 65 mol% or less, even more preferably 55 mol% or less. The total content of the bond units A and B is preferably 95 mol% or more, more preferably 98 mol% or more, particularly preferably 100 mol%. The content of the bonding units A and B includes the case where the bonding units A and B are located at the terminals of the silane coupling agent. When the bonding units A and B are located at the terminals of the silane coupling agent, the form of the bonding units A and B is not particularly limited, as long as they form units corresponding to the formulas (I) and (II) representing the bonding units A and B.

[0057] R in formulas (I) and (II) 11 With respect to the above, examples of halogen include chlorine, bromine, and fluorine. Examples of branched or unbranched alkyl groups having 1 to 30 carbon atoms include methyl and ethyl groups. Examples of branched or unbranched alkenyl groups having 2 to 30 carbon atoms include vinyl and 1-propenyl groups. Examples of branched or unbranched alkynyl groups having 2 to 30 carbon atoms include ethynyl and propynyl groups.

[0058] R in formulas (I) and (II) 12 Regarding the above, examples of branched or unbranched alkylene groups having 1 to 30 carbon atoms include an ethylene group, a propylene group, etc. Examples of branched or unbranched alkenylene groups having 2 to 30 carbon atoms include a vinylene group, a 1-propenylene group, etc. Examples of branched or unbranched alkynylene groups having 2 to 30 carbon atoms include an ethynylene group, a propynylene group, etc.

[0059] In a silane coupling agent containing a bonding unit A represented by formula (I) and a bonding unit B represented by formula (II), the total number of repetitions (v+w) of the bonding unit A (v) and the bonding unit B (w) is preferably in the range of 3 to 300.

[0060] The rubber composition may contain other silane coupling agents in addition to the mercapto-based silane coupling agent. Usable silane coupling agents are not particularly limited, and examples thereof include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, Examples of the silylsilylsilane include sulfide-based silylsilylsilanes such as 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyltetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide, vinyl-based silylsilanes such as vinyltriethoxysilane and vinyltrimethoxysilane, amino-based silylsilanes such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane, glycidoxy-based silylsilanes such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, nitro-based silylsilanes such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane, and chloro-based silylsilanes such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. These silylsilanes may be used alone or in combination of two or more.

[0061] Commercially available silane coupling agents include those manufactured by Degussa, Momentive, Shin-Etsu Silicones, Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and Dow Corning Toray Co., Ltd.

[0062] The content of the silane coupling agent is preferably 3 parts by mass or more, more preferably 6 parts by mass or more, and even more preferably 8 parts by mass or more, relative to 100 parts by mass of silica, and is preferably 15 parts by mass or less, more preferably 12 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above range, the effect tends to be more favorable.

[0063] The rubber composition contains carbon black. The carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available products that can be used include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nichika Carbon Co., Ltd., Columbia Carbon Co., Ltd., and the like. These may be used alone, or two or more types may be used in combination.

[0064] The cetyltrimethylammonium bromide (CTAB) specific surface area of ​​the carbon black is preferably 110 m 2 / g or more, more preferably 120m 2 / g or more, more preferably 130m 2 / g or more, and preferably 200m 2 / g or less, more preferably 160m 2 / g or less, more preferably 140m 2 Within the above range, there is a tendency for the effect to be better obtained. The CTAB specific surface area of ​​carbon black is a value measured in accordance with JIS K6217-3:2001.

[0065] The amount of carbon black per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and 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, better effects tend to be obtained.

[0066] In the above rubber composition, the trans amount of BR+vinyl amount>carbon black content.

[0067] The ratio (trans amount of BR+vinyl amount) / carbon black content is preferably 3 or more, more preferably 9 or more, and particularly preferably 12 or more, and is preferably 25 or less, more preferably 20 or less, and even more preferably 15 or less. Within the above ranges, better effects tend to be obtained.

[0068] In these relationships, the carbon black content is the content (unit: parts by mass) relative to 100 parts by mass of the rubber component. The trans and vinyl contents of BR are the trans and vinyl contents (unit: mass%) in 100% by mass of BR, but when there are multiple types of BR, they are the average trans and vinyl contents.

[0069] The rubber composition preferably contains a dialkyldithiophosphate compound. As the dialkyldithiophosphate compound, for example, a salt of dialkyldithiophosphate with a metal such as zinc or molybdenum can be used. Commercially available products include those from Rhein Chemie, etc. These may be used alone or in combination of two or more. Of these, the compound represented by the following formula (1) (zinc dialkyldithiophosphate) is preferred. [ka] (In the formula, R 1 ~R 4 each independently represents a linear or branched alkyl group having 1 to 18 carbon atoms, or a cycloalkyl group having 5 to 12 carbon atoms.

[0070] In formula (1), R 1 ~R 4Examples of the linear or branched alkyl group represented by R include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a 4-methylpentyl group, a 2-ethylhexyl group, an octyl group, and an octadecyl group, while examples of the cycloalkyl group include a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group. Among these, R is preferred because it is easily dispersed in the rubber composition and is easy to produce. 1 ~R 4 is preferably a linear or branched alkyl group having 2 to 8 carbon atoms, more preferably an n-butyl group, an n-propyl group, an isopropyl group or an n-octyl group, and even more preferably an n-butyl group.

[0071] The amount of the dialkyldithiophosphate compound is, per 100 parts by mass of the rubber component, preferably 0.5 parts by mass or more, more preferably 0.8 parts by mass or more, and even more preferably 1 part by mass or more, and is preferably 3 parts by mass or less, more preferably 2.5 parts by mass or less, and even more preferably 2 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0072] The rubber composition preferably contains sulfur. Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, and the like commonly used in the rubber industry. Commercially available products include those from Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanzuri Kogyo Co., Ltd., and Hosoi Chemical Industry Co., Ltd. These may be used alone or in combination of two or more.

[0073] The sulfur content, based on 100 parts by mass of the rubber component, is preferably 0.8 parts by mass or more, more preferably 1.4 parts by mass or more, and even more preferably 1.6 parts by mass or more, and is preferably 6 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0074] From the viewpoint of overall performance such as fuel economy at normal and low temperatures, the ratio of the sulfur content to the isoprene-based rubber content in the rubber composition is preferably more than 0.5, more preferably 0.6 or more, and is preferably 1.5 or less, more preferably 1.2 or less, and even more preferably 0.9 or less. Within the above ranges, the effect tends to be more favorable. In this relationship, the sulfur content is the content (unit: parts by mass) relative to 100 parts by mass of the rubber component, and the isoprene-based rubber content is the content (unit: % by mass) in 100% by mass of the rubber component.

[0075] The rubber composition may contain a processing aid. Examples of processing aids include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, fatty acid esters, mixtures of fatty acid metal salts and amide esters, and mixtures of fatty acid metal salts and fatty acid amides. Commercially available products include those from Rhein Chemie and Struktol. These may be used alone or in combination of two or more. Of these, fatty acid metal salts are preferred.

[0076] Examples of fatty acids constituting the fatty acid metal salt include saturated or unsaturated fatty acids (preferably saturated or unsaturated fatty acids having 6 to 28 carbon atoms (more preferably 10 to 25 carbon atoms, and even more preferably 14 to 20 carbon atoms)), such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidic acid, behenic acid, and nervonic acid. These can be used alone or in combination of two or more. Of these, saturated fatty acids are preferred, and saturated fatty acids having 14 to 20 carbon atoms are more preferred.

[0077] Examples of metals constituting fatty acid metal salts include alkali metals such as potassium and sodium, alkaline earth metals such as magnesium, calcium and barium, zinc, nickel, molybdenum, etc. These may be used alone or in combination of two or more. Of these, zinc is preferred.

[0078] The content of the processing aid is preferably 1 part by mass or more, more preferably 1.5 parts 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 8 parts by mass or less, more preferably 6 parts by mass or less, and even more preferably 4 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0079] The rubber composition may contain a resin. The resins that can be used are not particularly limited as long as they are those commonly used in the tire industry, and examples thereof include aromatic resins, terpene resins, etc. These may be used alone or in combination of two or more.

[0080] Examples of commercially available 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.

[0081] The amount of the resin, relative to 100 parts by mass of the rubber component, is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more, and is preferably 50 parts by mass or less, more preferably 35 parts by mass or less, and even more preferably 25 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0082] 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 antioxidants such as quinolone; quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol 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. Commercially available products include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., and Flexis. These antioxidants may be used alone or in combination of two or more.

[0083] The content of the antioxidant is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 4 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 12 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0084] The rubber composition may contain oil. 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. Commercially available products include those from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., JXTG Nippon Oil & Energy Corporation, Oriso Co., Ltd., H&R Corporation, Toyokuni Oil Mills Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., and the like. These may be used alone or in combination of two or more.

[0085] 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, and even more preferably at least 25 parts by mass, and is preferably at most 50 parts by mass, more preferably at most 40 parts by mass, and even more preferably at most 30 parts by mass. Within the above ranges, better effects tend to be obtained.

[0086] From the viewpoint of overall performance such as fuel economy at normal temperature and low temperature, it is preferable that the oil content of the rubber composition is equal to or greater than the total styrene content in the rubber component.

[0087] The ratio of oil content to total styrene content in the rubber component is preferably 1.2 or more, more preferably 1.4 or more, and even more preferably 1.5 or more, and is preferably 3.0 or less, more preferably 2.5 or less, and even more preferably 2.0 or less. Within the above ranges, the effect tends to be more favorable.

[0088] In these relationships, the total styrene amount in the rubber component is the total content (unit: mass%) of styrene parts contained in the entire rubber component, and the oil content is the content (unit: mass parts) per 100 parts by mass of the rubber component.

[0089] The rubber composition may contain a 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. Commercially available products include those from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., etc. These may be used alone or in combination of two or more.

[0090] The amount of wax per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 6 parts by mass or less. Within the above ranges, better effects tend to be obtained.

[0091] The rubber composition may contain stearic acid. As the stearic acid, conventionally known ones can be used, and commercially available products that can be used include products from NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc. These may be used alone or in combination of two or more.

[0092] The content of stearic acid is preferably 1 part by mass or more, more preferably 2.5 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 6 parts by mass or less, per 100 parts by mass of the rubber component. When the content is within the above range, better effects tend to be obtained.

[0093] The rubber composition may contain zinc oxide. As the zinc oxide, conventionally known ones can be used, and commercially available products include those available from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. These may be used alone or in combination of two or more.

[0094] The content of zinc oxide is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 6 parts by mass or less, per 100 parts by mass of the rubber component. When the content is within the above range, better effects tend to be obtained.

[0095] The rubber composition may contain a vulcanization accelerator. Examples of vulcanization accelerators include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole and di-2-benzothiazolyl disulfide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD) and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazyl sulfenamide (CBS), N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS), N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, di-orthotolylguanidine, and orthotolylbiguanidine. Commercially available products include those from Sumitomo Chemical Co., Ltd. and Ouchi Shinko Chemical Industry Co., Ltd. These may be used alone or in combination.

[0096] The content of the vulcanization accelerator is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 4.5 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 6 parts by mass or less. Within the above ranges, the effect tends to be more favorably obtained.

[0097] In addition to the above components, the rubber composition may further contain additives commonly used in the tire industry, such as organic peroxides, fillers such as talc, alumina, clay, aluminum hydroxide, mica, etc. The content of these additives is preferably 0.1 to 200 parts by mass per 100 parts by mass of the rubber component.

[0098] The rubber composition can be produced, for example, by kneading the above-mentioned components using a rubber kneading device such as an open roll or a Banbury mixer, followed by vulcanization.

[0099] As for kneading conditions, in the base kneading step in which additives other than the vulcanizing agent and vulcanization accelerator are kneaded, the kneading temperature is usually 100 to 180°C, preferably 120 to 170°C. In the finish kneading step in which the vulcanizing agent and vulcanization accelerator are kneaded, the kneading temperature is usually 120°C or lower, preferably 85 to 110°C. Furthermore, the composition kneaded with the vulcanizing agent and vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 140 to 190°C, preferably 150 to 185°C. The vulcanization time is usually 5 to 15 minutes. From the viewpoint of overall performance such as fuel economy at room temperature and low temperature, it is preferable that the isoprene-based rubber is kneaded with a vulcanizing agent such as sulfur to form a masterbatch, and then kneaded in the final kneading step.

[0100] The rubber composition can be used (as a rubber composition for tires) for tire components such as treads (cap treads), sidewalls, base treads, undertreads, shoulders, clinches, bead apexes, breaker cushion rubbers, carcass cord covering rubbers, insulation, chafers, inner liners, and side reinforcing layers of run-flat tires, among others. Among these, the rubber composition is particularly suitable for treads.

[0101] The tire of the present invention is produced by a conventional method using the above rubber composition. That is, the rubber composition is extruded in an unvulcanized state to match the shape of the tread, etc., and molded together with other tire components in a tire building machine by a conventional method to form an unvulcanized tire. This unvulcanized tire is then heated and pressurized in a vulcanizer to obtain a tire.

[0102] The above-mentioned tires (pneumatic tires, etc.) can be used for passenger car tires; truck and bus tires; motorcycle tires; high-performance tires; winter tires such as studless tires; run-flat tires with side reinforcing layers; tires with sound-absorbing material that have sound-absorbing material such as sponge in the tire cavity; tires with sealing material that have a sealant inside the tire or in the tire cavity that can seal in the event of a puncture; and tires with electronic components that have electronic components such as sensors and wireless tags inside the tire or in the tire cavity, and are suitable for passenger car tires.

[0103] The size of the tire is not particularly limited, and can be appropriately selected, for example, from a tire width in the range of 100 to 400 mm, an aspect ratio in the range of 25 to 85%, and a rim diameter in the range of 10 to 25 inches. Specific examples include 105 / 50R16, 115 / 50R17, 125 / 55R20, 135 / 45R21, 145 / 45R21, 155 / 45R18, 165 / 45R22, 175 / 45R23, 185 / 60R20, 195 / 55R14, 205 / 40R16, 215 / 40R16, 225 / 40R17, 235 / 40R17, 245 / 40R16, 255 / 40R17, 265 / 40R17, 275 / 35R18, 285 / 30R19, and 295 / 45R20.

[0104] It is preferable that the tire outer diameter Dt and the tire section width Wt of the tire satisfy the following relational expression.

number

[0105] Specific examples of tires that can satisfy the above formula include 145 / 60R18, 145 / 60R19, 155 / 55R18, 155 / 55R19, 155 / 70R17, 155 / 70R19, 165 / 55R20, 165 / 55R21, 165 / 60R19, 165 / 65R19, 165 / 70R18, 175 / 55R19, 175 / 55R20, 175 / 55R22, 175 / 60R18, 185 / 55R19, 185 / 60R20, 195 / 50R20, 195 / 55R20, and the like.

[0106] A tire satisfying the above formula is preferably applied to a pneumatic tire for a passenger vehicle, because a pneumatic tire for a passenger vehicle satisfying the above formula tends to be more suitable for solving the problem of the present invention. [Example]

[0107] The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[0108] The various chemicals used in the examples and comparative examples will be explained below.

[0109] (rubber component) SBR: Synthesized according to Production Example 1 below (styrene content: 35% by mass, vinyl content: 50% by mass, Mw: 600,000) BR1: N103 manufactured by Asahi Kasei Chemicals Corporation (cis content: 38% by mass, vinyl content: 12% by mass, trans content: 50% by mass) BR2: BR150B manufactured by Ube Industries, Ltd. (cis content: 97% by mass, vinyl content: 1% by mass, trans content: 2% by mass) Liquid IR: LIR-50 manufactured by Kuraray Co., Ltd. NR:TSR20

[0110] (Chemicals other than rubber components) Carbon Black 1: N220 (CTAB: 111m 2 / g) Carbon Black 2: N134 (CTAB: 135m 2 / g) Silica 1: Ultrasil VN3 (average particle size: 17 nm) manufactured by Evonik Degussa Silica 2: Ultrasil 9100GR (average particle size: 15 nm) manufactured by Evonik Degussa Silane coupling agent 1: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa Silane coupling agent 2: NXT (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive Silane coupling agent 3: NXT-Z45 (a copolymer of bonding unit A and bonding unit B (bonding unit A: 55 mol %, bonding unit B: 45 mol %)) manufactured by Momentive Dialkyldithiophosphate compound: TP-50 (a mixture of zinc dithiophosphate and polymer, R of formula (1)) manufactured by Rhein Chemie 1 ~R 4 n-butyl group, active ingredient 50% by mass Oil: Sankyo Yuka Kogyo Co., Ltd. A / O Mix Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd. Antioxidant 1: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Antioxidant 2: Antigen FR manufactured by Sumitomo Chemical Co., Ltd. (a quinoline-based antioxidant, purified from the reaction product of amine and ketone, with no residual amine) Processing aid: Struktol EF44 (zinc salt of saturated fatty acid) Stearic acid: NOF Corporation's "Tsubaki" stearic acid Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: HK-200-5 (powdered sulfur containing 5% oil by mass) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Noccela CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Noccela D (diphenyl guanidine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0111] (Production Example 1) Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were charged into a nitrogen-purged autoclave reactor. After adjusting the temperature of the reactor contents to 20°C, n-butyllithium was added to initiate polymerization. Polymerization was carried out under adiabatic conditions, with the maximum temperature reaching 85°C. When the polymerization conversion reached 99%, 1,3-butadiene was added, and polymerization was continued for an additional 5 minutes. 3-Diethylaminopropyltriethoxysilane was then added as a modifier, and the reaction was continued. After the polymerization reaction was completed, 2,6-di-tert-butyl-p-cresol was added. The solvent was then removed by steam stripping, and the mixture was dried on a heated roll heated to 110°C to obtain SBR (modified SBR).

[0112] Examples and Comparative Examples According to the formulation shown in Table 1, materials other than the isoprene-based rubber, 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 product (base kneading step). Next, the isoprene-based rubber, sulfur, and vulcanization accelerator were added to the obtained kneaded product, and the mixture was kneaded for 5 minutes at 80°C using an open roll to obtain an unvulcanized rubber composition (finish kneading step). The obtained unvulcanized rubber composition was molded into a tread shape and laminated with other tire components to form an unvulcanized tire. This was then press-vulcanized for 12 minutes at 150°C to produce a test tire (size: 175 / 60R18). The obtained test tire was subjected to the following evaluations, and the results are shown in Table 1. The isoprene-based rubber (liquid IR, NR) was kneaded in advance with sulfur to form a masterbatch, which was then kneaded in the finishing kneading step. In addition, in Table 1, the rubber content in the oil-extended rubber is listed in the rubber column, and the oil content in the oil-extended rubber is added to the oil column.

[0113] (low fuel consumption) Using a rolling resistance tester, the rolling resistance of each test tire was measured when it was run at a speed (80 km / h), and the rolling resistance was expressed as an index, with Comparative Example 2 being set at 100. The measurements were carried out at 30°C and 0°C. A larger index indicates lower rolling resistance and better fuel economy.

[0114] [Table 1]

[0115] From Table 1, it can be seen that the Examples were superior to the Comparative Examples in overall fuel economy performance (total of all indexes) at the targeted normal temperature (30°C) and low temperature (0°C).

Claims

1. The rubber composition contains a rubber component including styrene-butadiene rubber, butadiene rubber, and isoprene-based rubber, silica, a mercapto-based silane coupling agent, and carbon black, the trans amount of the butadiene rubber plus the vinyl amount is greater than the carbon black content, The rubber composition for tires has a ratio of the content of silica to the content of isoprene-based rubber of 10 or more and 35 or less.

2. 2. The rubber composition for tires according to claim 1, wherein the cis content of the butadiene rubber is less than the content of the silica.

3. 3. The rubber composition for tires according to claim 1, wherein the average particle size of the silica is 16 nm or less.

4. The carbon black has a cetyltrimethylammonium bromide adsorption specific surface area of ​​110 m ２ The rubber composition for a tire according to any one of claims 1 to 3, wherein the viscosity is 1 / g or more.

5. The rubber composition for a tire according to any one of claims 1 to 4, wherein the total amount of styrene in the rubber component is 18% by mass or less.

6. A tire using the rubber composition according to any one of claims 1 to 5.

Images