Rubber composition for tire and tire

Abstract

To provide a rubber composition for a tire and a tire which can improve abrasion resistance.SOLUTION: A rubber composition for a tire contains a rubber component containing styrene butadiene rubber, carbon black and a filler containing silica, a silane coupling agent, and a calcium compound, in which a content of the styrene butadiene rubber in 100 mass% of the rubber component is 60 mass% or more, a content of the rubber component is equal to or smaller than a content of the filler, the silane coupling agent is a mercapto-based silane coupling agent, and a content of the carbon black is equal to or larger than a content in terms of elemental calcium of the calcium compound.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Conventionally, various methods for improving wear resistance have been investigated (for example, see Patent Document 1). However, in recent years, there has been a demand for further improvement in wear resistance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-141405 A 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 abrasion resistance. [Means for solving the problem]

[0005] The present invention relates to a rubber composition for tires, comprising a rubber component containing styrene-butadiene rubber, a filler containing carbon black and silica, a silane coupling agent, and a calcium compound, wherein the content of the styrene-butadiene rubber is 60% by mass or more in 100% by mass of the rubber component, the content of the rubber component is equal to or less than the content of the filler, the silane coupling agent is a mercapto-silane coupling agent, and the content of the carbon black is equal to or more than the content of the calcium compound in terms of calcium element.

[0006] The rubber composition preferably contains a resin.

[0007] The rubber composition preferably contains a dialkyldithiophosphate compound.

[0008] It is preferable that the rubber composition contains a butadiene rubber, and that the butadiene rubber has a cis content of 90 mass % or less.

[0009] The rubber composition preferably contains a dibenzylamine compound.

[0010] It is preferable that the rubber composition contains an isoprene-based rubber and a resin, and the content of the isoprene-based rubber is less than or equal to the content of the resin.

[0011] The rubber composition preferably contains a cyclopentadiene-based resin.

[0012] The average particle size of the silica is preferably 16 nm or less.

[0013] The present invention also relates to a tire having a tread using the above rubber composition. Effect of the Invention

[0014] The present invention provides a rubber composition for tires which contains a rubber component containing styrene-butadiene rubber, a filler containing carbon black and silica, a silane coupling agent, and a calcium compound, in which the content of styrene-butadiene rubber is 60% by mass or more in 100% by mass of the rubber component, the content of the rubber component is equal to or less than the content of the filler, the silane coupling agent is a mercapto-based silane coupling agent, and the content of carbon black is equal to or more than the content of the calcium compound in terms of calcium element, thereby providing excellent abrasion resistance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The rubber composition for tires of the present invention contains a rubber component containing styrene-butadiene rubber, a filler containing carbon black and silica, a silane coupling agent, and a calcium compound, and the content of the styrene-butadiene rubber is 60 mass% or more in 100 mass% of the rubber component, the content of the rubber component is equal to or less than the content of the filler, the silane coupling agent is a mercapto-based silane coupling agent, and the content of the carbon black is equal to or more than the content of the calcium compound in terms of calcium element.

[0016] The reason why the above-mentioned effects are obtained with the above-mentioned rubber composition is presumed to be as follows. In the above rubber composition, styrene-butadiene rubber, silica, carbon black, a mercapto-silane coupling agent, and a calcium compound are blended, and the amount of styrene-butadiene rubber is adjusted to a predetermined range, and the relationship of the rubber component content≦the filler content and the relationship of the carbon black content≧the calcium compound content converted into calcium element are satisfied, so that the interaction between the silica and carbon black and the rubber component is well exhibited, and the reaction of the mercapto-silane coupling agent proceeds well. It is believed that these actions allow the silica and carbon black to be uniformly dispersed (distributed) in the rubber component, effectively reinforcing the rubber composition and significantly improving the wear resistance.

[0017] 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.

[0018] The weight average molecular weight of the rubber component is preferably 50,000 or more, more preferably 150,000 or more, and even more preferably 200,000 or more, and is preferably 2,000,000 or less, more preferably 1,500,000 or less, even more preferably 1,000,000 or less, and particularly preferably 800,000 or less. Within the above ranges, the effect tends to be better obtained.

[0019] In this specification, the weight average molecular weight (Mw) can be determined by converting it into standard polystyrene based on the measured value obtained by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation).

[0020] The ratio of the total vinyl content in the rubber component to the total styrene content in the rubber component is preferably 0.6 or more, more preferably 0.8 or more, and even more preferably 0.9 or more, and is preferably 1.5 or less, more preferably 1.3 or less, and even more preferably 1.2 or less. Within the above ranges, the effect tends to be better obtained.

[0021] The total styrene content in the rubber component is preferably 35% by mass or less, more preferably 33% by mass or less, and even more preferably 32% by mass or less, and is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more. Within the above ranges, the effect tends to be better obtained.

[0022] Here, the total amount of styrene in the rubber component is the total content of styrene parts contained in the total amount of rubber component (unit: mass%), and can be calculated by Σ(content of each rubber component × amount of styrene in each rubber component / 100). For example, in a case where 100% by mass of rubber component contains 85% by mass of SBR with styrene content: 40% by mass, 5% by mass of SBR with styrene content: 25% by mass, and 10% by mass of BR with styrene content: 0% by mass, the total amount of styrene in the rubber component is 35.25% by mass (=85×40 / 100+5×25 / 100+10×0 / 100).

[0023] The total vinyl content in the rubber component is preferably 35% by mass or less, more preferably 33% by mass or less, and even more preferably 32% by mass or less, and is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 25% by mass or more, and particularly preferably 28% by mass or more. Within the above ranges, the effect tends to be better obtained.

[0024] Here, the total vinyl content in the rubber component is the total content of vinyl parts contained in the entire rubber component (unit: mass%) and can be calculated by Σ (content of each rubber component × vinyl content in each rubber component / 100). For example, in a 100% rubber component, when the rubber component contains 85% by mass of SBR with a vinyl content of 30% by mass, 5% by mass of SBR with a vinyl content of 20% by mass, and 10% by mass of BR with a vinyl content of 10% by mass, the total vinyl content in the rubber component is 27.5% by mass (=85×30 / 100+5×20 / 100+10×10 / 100).

[0025] The styrene amount and vinyl amount in each rubber component can be measured by a nuclear magnetic resonance (NMR) method. In addition, 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 styrene-butadiene rubber (SBR) as a rubber component. The SBR is not particularly limited, and for example, emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc. Commercially available products include those from Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc.

[0027] The styrene content of the SBR is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 38% by mass or more, and is preferably 55% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less. Within the above ranges, the effect tends to be better obtained.

[0028] The vinyl content of the SBR is preferably 20% by mass or more, more preferably 28% by mass or more, even more preferably 32% by mass or more, particularly preferably 35% by mass or more, and is preferably 55% by mass or less, more preferably 45% by mass or less, even more preferably 40% by mass or less. Within the above ranges, the effect tends to be better obtained.

[0029] The above-mentioned styrene amount and vinyl amount of SBR mean the styrene amount and vinyl amount of the SBR when there is one type of SBR, and mean the average styrene amount and average vinyl amount 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 SBR 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 SBR with a vinyl content of 30% by mass and 5% by mass of SBR with a vinyl content of 20% by mass, the average vinyl content of the SBR is 29.4% by mass (=(85×30+5×20) / (85+5)).

[0030] In 100% by mass of the rubber component, the content of SBR is 60% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less. When it is within the above range, the effect tends to be better obtained.

[0031] Examples of rubber components that can be used other than SBR include diene rubbers such as isoprene rubber, butadiene rubber (BR), 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. Among these, isoprene rubber and BR are preferred.

[0032] Examples of isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. Examples of NR include SIR20, RSS♯3, TSR20, and other rubbers that are common in the tire industry. Examples of IR include IR2200 and other rubbers that are common in the tire industry. Examples of modified NR include deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), and other rubbers. Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more. Among these, NR is preferred.

[0033] In 100% by mass of the rubber component, the content of the isoprene-based rubber 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 better obtained.

[0034] The BR is not particularly limited, and can be high cis content BR, low cis content BR, BR containing syndiotactic polybutadiene crystals, etc. Commercially available products include those from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Zeon Corporation, etc.

[0035] The cis amount (cis content) of BR is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 35% by mass or more, and is preferably 90% by mass or less, more preferably 70% by mass or less, and even more preferably 50% by mass or less. Within the above ranges, the effect tends to be better obtained. The cis content of BR can be measured by infrared absorption spectroscopy.

[0036] The above-mentioned cis amount of BR means the cis amount of the BR when there is one type of BR, and means the average cis amount when there are multiple types of BR. The average cis 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)).

[0037] In 100% by mass of the rubber component, the content of BR is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, and is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less. Within the above ranges, the effect tends to be better obtained.

[0038] 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 imide 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 them, 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), and an alkoxysilyl group (preferably an alkoxysilyl group having 1 to 6 carbon atoms) are preferred.

[0039] Specific examples of compounds (modifiers) having the above-mentioned functional groups include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane, and the like.

[0040] The rubber composition contains carbon black as a filler. 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 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 in combination of two or more kinds.

[0041] The cetyltrimethylammonium bromide (CTAB) specific surface area of ​​the carbon black is preferably 90 m 2 / g or more, more preferably 100m 2 / g or more, more preferably 110m 2 / g or more, and preferably 160m 2 / g or less, more preferably 140m 2 / g or less, more preferably 130m 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.

[0042] The amount of carbon black is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less, based on 100 parts by mass of the rubber component. When the amount is within the above range, the effect tends to be better obtained.

[0043] The rubber composition contains silica as a filler. Examples of silica include dry silica (anhydrous silicic acid) and wet silica (hydrated silicic acid), but wet silica is preferred because it has a large number of silanol groups. Commercially available products include those from EVONIK, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Co., Ltd., etc. These may be used alone or in combination of two or more.

[0044] The average particle size of 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. When it is within the above range, the effect tends to be better.

[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 when the particle shape is spherical, the diameter of the sphere is taken as the particle size, when the particle shape is needle-like or rod-like, the minor axis is taken as the particle size, when the particle shape is irregular, the average particle size from the center is taken as the particle size, and the average value of the particle sizes of 100 fine particles is taken as the average particle size.

[0046] The content of silica is preferably 80 parts by mass or more, more preferably 90 parts by mass or more, and even more preferably 100 parts by mass or more, relative to 100 parts by mass of the rubber component, and is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and even more preferably 110 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0047] Fillers that can be used other than carbon black and silica include those commonly used in the tire industry, such as aluminum hydroxide, talc, mica, magnesium oxide, magnesium sulfate, etc. These may be used alone or in combination of two or more.

[0048] The amount of the filler (total amount of carbon black, silica, and other fillers) is preferably 80 parts by mass or more, more preferably 90 parts by mass or more, and even more preferably 100 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 150 parts by mass or less, more preferably 130 parts by mass or less, and even more preferably 120 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0049] In the rubber composition, the rubber component content≦the filler content.

[0050] In the rubber composition, the filler content / rubber component content is preferably 1.0 or more, and is preferably 1.5 or less, more preferably 1.3 or less, and further preferably 1.2 or less. Within the above range, the effect tends to be better obtained.

[0051] In these relationships, the filler content is the content (unit: parts by mass) relative to 100 parts by mass of the rubber component, and the rubber component content is the total content of each rubber (unit: parts by mass), which is usually 100.

[0052] The rubber composition contains a mercapto-based silane coupling agent. The mercapto-based silane coupling agent is a silane coupling agent having a mercapto group, and examples thereof include 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, etc. In addition, as the mercapto-based silane coupling agent, a compound having a structure in which a mercapto group is protected by a protecting group (for example, a compound represented by the following formula (S1)) can also be used.

[0053] Particularly suitable mercapto-based silane coupling agents include silane coupling agents represented by the following formula (S1) and silane coupling agents containing a bond unit A represented by the following formula (I) and a bond unit B represented by the following formula (II). [ka] (In the formula, R 1001 -Cl, -Br, -OR 1006 , -O(O=)CR 1006 , -ON=CR 1006 R 1007 , -NR 1006 R 1007 and-(OSiR 1006 R 1007 ) h (OSiR 1006 R 1007 R 1008 ) a monovalent group (R 1006 , R 1007 and R 1008 may be the same or different, each is 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 relationship: x+y+2z=3, 0≦x≦3, 0≦y≦2, 0≦z≦1. [ka] [ka] (In the formula, v is an integer of 0 or more, and w is an integer of 1 or more. R 11R 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 R 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.)

[0054] In formula (S1), R 1005 , R 1006 , R 1007 and R 1008 are each preferably independently selected from the group consisting of a linear, cyclic or branched alkyl group, an alkenyl group, an aryl group and an aralkyl group having 1 to 18 carbon atoms. 1002 When R is a monovalent hydrocarbon group having 1 to 18 carbon atoms, it is preferably a group selected from the group consisting of linear, cyclic or branched alkyl groups, alkenyl groups, aryl groups and aralkyl groups. 1009 R is preferably a linear, cyclic or branched alkylene group, and particularly preferably a linear one. 1004 Examples of R include an alkylene group having 1 to 18 carbon atoms, an alkenylene group having 2 to 18 carbon atoms, a cycloalkylene group having 5 to 18 carbon atoms, a cycloalkylalkylene group having 6 to 18 carbon atoms, an arylene group having 6 to 18 carbon atoms, and an aralkylene group having 7 to 18 carbon atoms. The alkylene group and the alkenylene group may be either linear or branched, and the cycloalkylene group, the cycloalkylalkylene group, the arylene group, and the aralkylene group may have a functional group such as a lower alkyl group on the ring. 1004 As the alkylene group, an alkylene group having 1 to 6 carbon atoms is preferable, and a linear alkylene group such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, or a hexamethylene group is particularly preferable.

[0055] 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.

[0056] Specific examples of the silane coupling agent represented by formula (S1) include 3-hexanoylthiopropyl triethoxysilane, 3-octanoylthiopropyl triethoxysilane, 3-decanoylthiopropyl triethoxysilane, 3-lauroylthiopropyl triethoxysilane, 2-hexanoylthioethyl triethoxysilane, 2-octanoylthioethyl triethoxysilane, 2-decanoylthioethyl triethoxysilane, 2-lauroylthioethyl triethoxysilane, 3-hexanoylthiopropyl trimethoxysilane, 3-octanoylthiopropyl trimethoxysilane, 3-decanoylthiopropyl trimethoxysilane, 3-lauroylthiopropyl trimethoxysilane, 2-hexanoylthioethyl trimethoxysilane, 2-octanoylthioethyl trimethoxysilane, 2-decanoylthioethyl trimethoxysilane, and 2-lauroylthioethyl trimethoxysilane. These may be used alone or in combination of two or more kinds. Among them, 3-octanoylthiopropyltriethoxysilane is particularly preferable.

[0057] 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, and particularly preferably 100 mol%. The content of the bond units A and B includes the case where the bond units A and B are located at the terminals of the silane coupling agent. When the bond units A and B are located at the terminals of the silane coupling agent, the form is not particularly limited, and it is sufficient that they form units corresponding to the formulas (I) and (II) representing the bond units A and B.

[0058] R in formula (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.

[0059] R in formula (I) and (II) 12 Regarding the above, examples of the branched or unbranched alkylene group having 1 to 30 carbon atoms include an ethylene group, a propylene group, etc. Examples of the branched or unbranched alkenylene group having 2 to 30 carbon atoms include a vinylene group, a 1-propenylene group, etc. Examples of the branched or unbranched alkynylene group having 2 to 30 carbon atoms include an ethynylene group, a propynylene group, etc.

[0060] 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 and the bonding unit B is preferably in the range of 3 to 300.

[0061] The rubber composition may contain a silane coupling agent other than a mercapto-based one. Examples of the silane coupling agent that can be used 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-trimethoxysilyl butyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, 3-triethoxysilylpropyl methacrylate monosulfide and other sulfide-based compounds, vinyl triethoxysilane, vinyl trimethoxysilane and other vinyl-based compounds, 3-aminopropyl triethoxysilane, 3-aminopropyl trimethoxysilane and other amino-based compounds, γ-glycidoxypropyl triethoxysilane, γ-glycidoxypropyl trimethoxysilane and other glycidoxy-based compounds, 3-nitropropyl trimethoxysilane, 3-nitropropyl triethoxysilane and other nitro-based compounds, 3-chloropropyl trimethoxysilane, 3-chloropropyl triethoxysilane and other chloro-based compounds, etc. These compounds may be used alone or in combination of two or more.

[0062] As commercially available silane coupling agents, for example, products from Degussa, Momentive, Shin-Etsu Silicones, Tokyo Chemical Industry, Azumax, Dow Corning Toray, etc. can be used.

[0063] The content of silane coupling agent is preferably 3 parts by mass or more, more preferably 6 parts by mass or more, even more preferably 8 parts by mass or more, and is preferably 15 parts by mass or less, more preferably 12 parts by mass or less, even more preferably 10 parts by mass or less, based on 100 parts by mass of silica.When it is within the above range, the effect tends to be better obtained.

[0064] The rubber composition contains a calcium compound. The calcium compound is a compound containing calcium, and examples thereof include inorganic salts such as calcium oxide, calcium hydroxide, and calcium carbide; and oxoacid salts such as calcium carbonate, calcium nitrate, and calcium sulfate. The oxoacid salts also include fatty acid salts such as calcium acetate and calcium stearate. Examples of calcium compounds that contain calcium compounds include eggshells (main component: calcium carbonate) and WB16 (a mixture of fatty acid calcium, fatty acid amide, and fatty acid amide ester) manufactured by Struktol. These may be used alone or in combination of two or more. Among these, oxoacid salts are preferred, and fatty acid salts (fatty acid calcium) are more preferred.

[0065] In this specification, the calcium compound is included in the rubber composition regardless of the type or application, and may be included in the filler or other processing aids.

[0066] In the rubber composition, the calcium compound content in terms of calcium element is preferably 0.1 parts by mass, more preferably 0.2 parts by mass or more, and preferably 1.2 parts by mass or less, more preferably 0.8 parts by mass or less, and further preferably 0.4 parts by mass or less, based on 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better obtained.

[0067] In the rubber composition, the carbon black content is equal to or greater than the calcium element content of the calcium compound.

[0068] In the rubber composition, the ratio of the carbon black content to the calcium compound content in terms of calcium element is preferably 10 or more, more preferably 15 or more, even more preferably 20 or more, particularly preferably 25 or more, and is preferably 50 or less, more preferably 40 or less, and even more preferably 30 or less. Within the above ranges, the effect tends to be better obtained.

[0069] In these relationships, the carbon black content and the calcium compound content calculated as calcium element are the contents (unit: parts by mass) per 100 parts by mass of the rubber component.

[0070] The rubber composition preferably contains a resin. Examples of the resin include cyclopentadiene resins, aromatic resins, and terpene resins. These may be used alone or in combination of two or more. They may also be hydrogenated (hydrogenated resins). Among these, cyclopentadiene resins and aromatic resins are preferred, and cyclopentadiene resins are more preferred.

[0071] The cyclopentadiene-based resin is a polymer containing a cyclopentadiene-based monomer as a constituent monomer, and examples thereof include homopolymers obtained by polymerizing one type of cyclopentadiene-based monomer alone, copolymers obtained by copolymerizing two or more types of cyclopentadiene-based monomers, and copolymers of a cyclopentadiene-based monomer and another monomer that can be copolymerized therewith.

[0072] Examples of the cyclopentadiene monomer include cyclopentadiene, dicyclopentadiene, tricyclopentadiene, etc. These may be used alone or in combination of two or more. Among them, dicyclopentadiene is preferred.

[0073] Because there is a tendency for the effect to be better obtained, the cyclopentadiene-based resin is preferably a polymer containing dicyclopentadiene (DCPD) as a constituent monomer (DCPD-based resin), more preferably a copolymer of DCPD and an aromatic monomer, and even more preferably a copolymer of DCPD and a C9 fraction (vinyl toluene, indene, etc.) (DCPD-C9 resin). In this specification, a polymer containing a cyclopentadiene-based monomer and an aromatic-based monomer as constituent monomers, such as DCPD-C9 resin, is treated as a cyclopentadiene-based resin, not an aromatic resin.

[0074] The amount of the cyclopentadiene resin is preferably 5 parts by mass or more, more preferably 8 parts by mass or more, and even more preferably 10 parts by mass or more, relative to 100 parts by mass of the rubber component, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0075] An aromatic resin is a polymer containing an aromatic monomer as a constituent monomer, and examples of such a resin include a homopolymer obtained by polymerizing one type of aromatic monomer alone, a copolymer obtained by copolymerizing two or more types of aromatic monomers, and a copolymer of an aromatic monomer and another monomer that can be copolymerized with the aromatic monomer.

[0076] Examples of aromatic monomers include styrene monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, and p-chlorostyrene; phenol monomers such as phenol, alkylphenol, and alkoxyphenol; naphthol monomers such as naphthol, alkylnaphthol, and alkoxynaphthol; coumarone, indene, and the like. These may be used alone or in combination of two or more. Among them, styrene monomers are preferred, and styrene and α-methylstyrene are more preferred.

[0077] Because there is a tendency for the effect to be better obtained, the aromatic resin is preferably a polymer containing α-methylstyrene as a constituent monomer (α-methylstyrene-based resin), and more preferably a copolymer of α-methylstyrene and styrene.

[0078] The content of the aromatic resin is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, and is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less, based on 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better obtained.

[0079] 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, Nippon Paint Chemical Co., Ltd., Nippon Shokubai Co., Ltd., JXTG Nippon Oil & Energy Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Co., Ltd.

[0080] The amount of the resin (when a plurality of resins are used in combination, the total amount) is preferably 5 parts by mass or more, more preferably 8 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the rubber component, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less. Within the above range, the effect tends to be better obtained.

[0081] In the rubber composition, from the viewpoint of abrasion resistance and the like, it is preferable that the content of the isoprene-based rubber is equal to or less than the content of the resin.

[0082] In the rubber composition, the resin content / isoprene-based rubber content is preferably 1.0 or more, more preferably 1.5 or more, and even more preferably 2.0 or more, and is preferably 4.0 or less, more preferably 3.0 or less, and even more preferably 2.5 or less. Within the above ranges, the effect tends to be better obtained.

[0083] In these relationships, the isoprene-based rubber content is the content (unit: mass %) in 100% by mass of the rubber component, and the resin content is the content (unit: mass parts) relative to 100 parts by mass of the rubber component.

[0084] In the rubber composition, the resin content / silica content is preferably 0.05 or more, more preferably 0.10 or more, and is preferably 0.25 or less, more preferably 0.20 or less, and further preferably 0.15 or less. Within the above range, the effect tends to be better obtained. In this relationship, the resin content and the silica content are the contents (unit: parts by mass) relative to 100 parts by mass of the rubber component.

[0085] 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. As a commercially available product, a product from Rhein Chemie or the like can be used. These may be used alone or in combination of two or more. Among them, a 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.

[0086] 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 1 ~R 4 is preferably a linear or branched alkyl group having 2 to 8 carbon atoms, more preferably an n-butyl group, an n-propyl group, an iso-propyl group, or an n-octyl group, and further preferably an n-butyl group.

[0087] The content of the dialkyldithiophosphate compound is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, and is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and even more preferably 1 part by mass or less, based on 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better obtained.

[0088] The rubber composition preferably contains a dibenzylamine compound. The dibenzylamine compound is a compound having at least one group (dibenzylamine group) represented by the following formula. [ka]

[0089] Specific examples of the dibenzylamine compound include dibenzylamine, tetrabenzylthiuram disulfide (TBzTD), zinc dibenzyldithiocarbamate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, etc. Commercially available products include those from Sanshin Chemical Industry Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., LANXESS, etc. These may be used alone or in combination of two or more. Among them, a compound having two dibenzylamine groups is preferred, and tetrabenzylthiuram disulfide is more preferred.

[0090] The content of the dibenzylamine compound is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and further preferably 1 part by mass or less, based on 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better obtained.

[0091] 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 the antioxidant include p-phenylenediamine antioxidants such as quinolinone; 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 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 Co., Ltd., and Flexis Co., Ltd. These may be used alone or in combination of two or more.

[0092] The content of the antioxidant is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, and is preferably 8 parts by mass or less, more preferably 6 parts by mass or less, and even 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, the effect tends to be better.

[0093] The rubber composition may contain oil. Examples of the oil include process oil, vegetable oil, and mixtures thereof. Examples of the process oil include paraffin-based process oil, aromatic process oil, and naphthenic process oil. Examples of the vegetable oil 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 oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. Examples of commercially available products include products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., JXTG Nippon Oil & Energy Corporation, Orisoi Co., Ltd., H&R Co., Ltd., Toyokuni Oil Mill 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.

[0094] The content of the oil is preferably 10 parts by mass or more, more preferably 25 parts by mass or more, and even more preferably 35 parts by mass or more, and is preferably 80 parts by mass or less, more preferably 65 parts by mass or less, and even more preferably 55 parts by mass or less, based on 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better obtained.

[0095] In the rubber composition, from the viewpoint of abrasion resistance and the like, it is preferable that the oil content is equal to or greater than the total styrene content in the rubber component.

[0096] In the rubber composition, the oil content / total styrene content in the rubber component is preferably 1.1 or more, and is preferably 3.5 or less, more preferably 2.5 or less, even more preferably 1.8 or less, and particularly preferably 1.5 or less. Within the above range, the effect tends to be better obtained.

[0097] 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.

[0098] 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 kinds.

[0099] The amount of the wax 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, based on 100 parts by mass of the rubber component. Within the above ranges, the effect tends to be better obtained.

[0100] The rubber composition may contain stearic acid. As the stearic acid, a conventionally known one can be used, and as a commercially available product, a product from NOF Corp., Kao Corp., Fujifilm Wako Pure Chemical Corp., Chiba Fatty Acid Corp., etc. can be used. These may be used alone or in combination of two or more kinds.

[0101] The content of stearic acid 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, based on 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better obtained.

[0102] The rubber composition may contain zinc oxide. As the zinc oxide, a conventionally known one can be used, and as a commercially available product, it is possible to use 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. These may be used alone or in combination of two or more kinds.

[0103] The amount of zinc oxide is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 6 parts by mass or less, based on 100 parts by mass of the rubber component. Within the above ranges, the effect tends to be better obtained.

[0104] The rubber composition may contain sulfur. 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. 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., Hosoi Chemical Industry Co., Ltd., etc. These may be used alone or in combination of two or more kinds.

[0105] The amount of sulfur is preferably 0.8 parts by mass or more, more preferably 1.2 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 4 parts by mass or less, and even more preferably 3 parts by mass or less, based on 100 parts by mass of the rubber component. Within the above ranges, the effect tends to be better obtained.

[0106] The rubber composition may contain a vulcanization accelerator. Examples of the vulcanization accelerator 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-benzothiazylsulfenamide (CBS), N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-oxyethylene-2-benzothiazolesulfenamide and N,N'-diisopropyl-2-benzothiazolesulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, di-orthotolylguanidine, and orthotolylbiguanidine. Commercially available products include products from Sumitomo Chemical Co., Ltd. and Ouchi Shinko Chemical Co., Ltd. These may be used alone or in combination of two or more.

[0107] The content of the vulcanization accelerator is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more, and even more preferably 1.8 parts by mass or more, 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, based on 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better.

[0108] 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.

[0109] The rubber composition can be produced, for example, by kneading the above-mentioned components using a rubber kneading device such as an open roll or a Banbury mixer, and then vulcanizing the mixture.

[0110] As for the kneading conditions, in the base kneading step in which additives other than the vulcanizing agent and the 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 the 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 the vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 140 to 190°C, preferably 150 to 185°C. The vulcanization time is usually 5 to 15 minutes.

[0111] The rubber composition can be used (as a rubber composition for tires) for tire components such as treads (cap treads), sidewalls, base treads, under treads, shoulders, clinches, bead apexes, breaker cushion rubbers, carcass cord covering rubbers, insulations, chafers, inner liners, and side reinforcing layers of run-flat tires. Among these, the rubber composition is particularly suitable for treads.

[0112] 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, and molded together with other tire components in a tire building machine by a normal method to form an unvulcanized tire. The unvulcanized tire is then heated and pressurized in a vulcanizer to obtain a tire.

[0113] The tread of the tire may be at least partially made of the rubber composition, and may be entirely made of the rubber composition.

[0114] The above 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 having a sound-absorbing material such as sponge in the tire cavity; tires with sealing material having a sealant inside or in the tire cavity that can seal in the event of a puncture; tires with electronic components having electronic components such as sensors and wireless tags inside or in the tire cavity, etc., and are suitable for passenger car tires.

[0115] 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.

[0116] It is preferable that the tire outer diameter Dt and the tire section width Wt of the tire satisfy the following relational expression.

number

[0117] 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.

[0118] 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. EXAMPLES

[0119] The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[0120] The various chemicals used in the examples and comparative examples will be described below.

[0121] (Rubber component) Isoprene rubber: TSR20 (NR) SBR1: Buna VSL 2438-2 HM manufactured by LANXESS (styrene content: 38% by mass, vinyl content: 24% by mass, contains 37.5 parts by mass of oil per 100 parts by mass of rubber solids) SBR2: Nipol NS522 manufactured by Zeon Co., Ltd. (styrene content: 38% by mass, vinyl content: 40% by mass, contains 37.5 parts by mass of oil per 100 parts by mass of rubber solids) SBR3: Modified SBR synthesized in Production Example 1 below (styrene content: 40% by mass, vinyl content: 30% by mass, Mw: 950,000) SBR4: Modified SBR synthesized in Production Example 2 below (styrene content: 40% by mass, vinyl content: 40% by mass, Mw: 750,000) BR: N103 manufactured by Asahi Kasei Chemicals Corporation (cis content: 38% by mass, vinyl content: 12% by mass)

[0122] (Chemicals other than rubber components) Carbon black: N220 (CTAB: 111m 2 / g) Silica 1: Ultrasil 9100GR (average particle size: 15 nm) manufactured by Evonik Degussa Silica 2: Ultrasil VN3 manufactured by Evonik Degussa (average particle size: 17 nm) Silane coupling agent 1: NXT-Z45 manufactured by Momentive (a copolymer of bonding unit A and bonding unit B (bonding unit A: 55 mol %, bonding unit B: 45 mol %)) Silane coupling agent 2: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa Oil: H&R VIVATEC 500 (TDAE oil) Resin 1: Oppera PR-395 (hydrogenated DCPD-C9 resin) manufactured by Exxon Mobil Resin 2: Sylvatraxx 4401 (α-methylstyrene resin (copolymer of α-methylstyrene and styrene)) manufactured by Arizona Chemical Company 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. Anti-aging agent 2: Antigen FR manufactured by Sumitomo Chemical Co., Ltd. (a quinoline-based anti-aging agent, purified from the reaction product of amines and ketones, with no residual amines) Stearic acid: NOF Corporation's "Tsubaki" stearic acid Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Processing aid: WB16 manufactured by Struktol (mixture of fatty acid calcium, fatty acid amide and fatty acid amide ester, calcium element content: approximately 5% by mass) Sulfur: HK-200-5 (powdered sulfur containing 5% oil by mass) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator: Noccela CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Dibenzylamine compound: Sancerer TBzTD (tetrabenzyl thiuram disulfide) manufactured by Sanshin Chemical Industry Co., Ltd. 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 weight

[0123] (Production Example 1) Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were charged into a nitrogen-substituted autoclave reactor. After adjusting the temperature of the reactor contents to 20°C, n-butyllithium was added to initiate polymerization. Polymerization was performed 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 another 5 minutes, after which N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane was added as a modifier to carry out the reaction. After the polymerization reaction was completed, 2,6-di-tert-butyl-p-cresol was added. Next, the solvent was removed by steam stripping, and the mixture was dried with a heated roll adjusted to 110°C to obtain SBR3.

[0124] (Production Example 2) Two autoclaves with an internal volume of 10 liters, an inlet at the bottom and an outlet at the top, and an agitator and a jacket were connected in series as reactors, and butadiene, styrene, and cyclohexane were mixed in a predetermined ratio. This mixed solution was passed through a dehydration column filled with activated alumina, and after mixing with n-butyllithium in a static mixer to remove impurities, it was continuously fed from the bottom of the first reactor, and further 2,2-bis(2-oxolanyl)propane as a polar substance and n-butyllithium as a polymerization initiator were continuously fed from the bottom of the first reactor at a predetermined rate, respectively, and the temperature inside the reactor was maintained at 95°C. The polymer solution was continuously withdrawn from the top of the reactor and fed to the second reactor. The temperature of the second reactor was kept at 95°C, and a mixture of tetraglycidyl-1,3-bisaminomethylcyclohexane (monomer) and oligomer components (hereinafter referred to as "modifier A") was added continuously at a specified rate as a 1000-fold diluted solution of cyclohexane to carry out the modification reaction. This polymer solution was continuously withdrawn from the reactor, and an antioxidant was continuously added using a static mixer, after which the solvent was removed to obtain SBR4.

[0125] Examples and Comparative Examples According to the formulation shown in Table 1, materials other than the dibenzylamine compound, sulfur, and vulcanization accelerator were kneaded for 5 minutes under the condition of 150 ° C using a 1.7 L Banbury mixer manufactured by Kobe Steel, Ltd. to obtain a kneaded product. Next, the dibenzylamine compound, sulfur, and vulcanization accelerator were added to the obtained kneaded product, and the mixture was kneaded for 5 minutes under the condition of 80 ° C using an open roll to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was molded into a tread shape, and laminated together with other tire components to form an unvulcanized tire, which was press-vulcanized for 12 minutes under the condition of 150 ° C to produce a test tire (size: 175 / 60R18). The following evaluations were performed using the obtained test tire, and the results are shown in Table 1. In Table 1, the rubber content in oil-extended rubber is listed in the rubber column, and the oil content in oil-extended rubber is added to the oil column.

[0126] (Wear resistance) Each test tire was mounted on a vehicle, and the groove depth of the tread portion was measured after driving 50,000 km. The amount of wear of the tread portion was calculated from the measured values, and expressed as an index with Comparative Example 1 being set at 100. The larger the index, the smaller the amount of wear and the better the wear resistance.

[0127] (Wet grip performance) Each test tire was mounted on a vehicle, and the braking distance from an initial speed of 80 km / h on a wet asphalt road surface was determined, and expressed as an index with Comparative Example 2 being set at 100. A higher index indicates a shorter braking distance and better wet grip performance.

[0128] [Table 1]

[0129] As can be seen from Table 1, the Examples were superior in the desired wear resistance to the Comparative Examples. Furthermore, the Examples were superior to the Comparative Examples in terms of overall performance (total of all indexes) in terms of abrasion resistance and wet grip performance.

Claims

1. It contains rubber components including styrene-butadiene rubber and isoprene-based rubber, fillers including carbon black and silica, a silane coupling agent, a calcium compound, and a resin. The content of styrene-butadiene rubber is 60% by mass or more in 100% by mass of the aforementioned rubber component. The content of the rubber component is less than or equal to the content of the filler. The silane coupling agent is a mercapto-silane coupling agent. The carbon black content is greater than or equal to the calcium compound content in terms of calcium element, A rubber composition for tires in which the content of the isoprene-based rubber is less than or equal to the content of the resin.

2. The tire rubber composition according to claim 1, comprising a dialkyldithiophosphate compound.

3. It contains butadiene rubber, The tire rubber composition according to claim 1 or 2, wherein the cis content of the butadiene rubber is 90% by mass or less.

4. A tire rubber composition according to any one of claims 1 to 3, containing a dibenzylamine compound.

5. A tire rubber composition according to any one of claims 1 to 4, comprising a cyclopentadiene resin.

6. The tire rubber composition according to any one of claims 1 to 5, wherein the average particle size of the silica is 16 nm or less.

7. A tire having a tread made of the rubber composition described in any one of claims 1 to 6.