Rubber composition for tires and tires

Abstract

To provide a rubber composition for tires and a tire which are capable of improving wet steering stability.SOLUTION: The present invention relates to the rubber composition for tires which contains: a rubber component containing a styrene-butadiene rubber, a butadiene rubber and an isoprene rubber; silica; a resin component; and a calcium compound. The following relations are satisfied: (the content of the styrene-butadiene rubber)>(the content of the isoprene rubber)>(the content of the butadiene rubber); and (the content of the resin component)>(the content of the calcium compound in terms of calcium element).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 steering stability on wet road surfaces (wet steering stability) have been studied (for example, see Patent Document 1). However, in recent years, there has been a demand for further improvement in wet steering stability performance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-334310 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 tires and a tire that can solve the above problems and improve wet steering stability. [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 resin component, and a calcium compound, wherein a content of the styrene-butadiene rubber > a content of the isoprene-based rubber > a content of the butadiene rubber, and a content of the resin component > a content of the calcium compound converted into calcium element.

[0006] It is preferable that the content of the silica is greater than the content of the styrene-butadiene rubber.

[0007] The butadiene rubber preferably has a cis content of 90% or less.

[0008] It is preferable that the resin amount of the resin component is greater than the total styrene amount in the rubber component.

[0009] The resin component preferably contains a styrene-based resin.

[0010] The cetyltrimethylammonium bromide adsorption specific surface area of ​​the silica is 180m 2 It is preferable that the molecular weight is 1 / g or more.

[0011] The rubber composition preferably contains a mercapto-based silane coupling agent.

[0012] The rubber composition preferably contains a dibenzylamine compound.

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

[0014] The present invention provides 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 resin component, and a calcium compound, and satisfies the following relationship: (Content of styrene-butadiene rubber)>(Content of isoprene-based rubber)>(Content of butadiene rubber) and (Content of resin component)>(Content of calcium compound converted into calcium element), thereby providing good wet steering stability. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The rubber composition for tires of the present invention contains a rubber component including a styrene-butadiene rubber, a butadiene rubber, and an isoprene-based rubber, silica, a resin component, and a calcium compound, and the content of the styrene-butadiene rubber > the content of the isoprene-based rubber > the content of the butadiene rubber, and the content of the resin component > 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, by making the content of styrene-butadiene rubber > the content of isoprene-based rubber > the content of butadiene rubber, it is possible to form an island-in-sea structure in which the highly heat-generating styrene-butadiene rubber is used as the sea phase, thereby improving the grip performance with the road surface. In addition, with regard to the isoprene-based rubber and butadiene rubber that form the island phase, since the isoprene-based rubber has a high molecular weight and hence has high rigidity under high strain, and the butadiene rubber has high resilience, the presence of these in the island phase makes it easier for a large reaction force to be generated when the rubber phase is deformed. In addition, by making the content of the resin component greater than the calcium element content of the calcium compound, the adhesion of the resin to the kneader during kneading is suppressed, and the shearing force of the kneader is efficiently applied to the resin and rubber component, promoting the dispersion of the resin. Furthermore, the interaction between the resin and silica also promotes the dispersion of silica, so that the silica is well dispersed in the styrene-butadiene rubber, butadiene rubber, and isoprene-based rubber, and the interaction between the rubber component and silica is easily generated. It is believed that these actions improve the grip performance with the road surface and the reaction force during deformation, thereby significantly improving wet driving stability.

[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, and even more preferably 1,000,000 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] From the viewpoint of wet steering stability and the like, it is preferable that the total styrene content in the rubber component of the rubber composition is less than the total vinyl content in the rubber component.

[0021] The ratio of the total vinyl content in the rubber component to the total styrene content in the rubber component is preferably 1.1 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 better obtained.

[0022] The total styrene content in the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 12% by mass or more, and is preferably 35% 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.

[0023] 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).

[0024] The total vinyl content in the rubber component is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less. Within the above ranges, the effect tends to be better obtained.

[0025] 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).

[0026] 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.

[0027] 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.

[0028] The styrene content of the SBR 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 45% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less. Within the above ranges, the effect tends to be better obtained.

[0029] The vinyl content of the SBR is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, and is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 55% by mass or less. Within the above ranges, the effect tends to be better obtained.

[0030] 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)).

[0031] In 100% by mass of the rubber component, the content of SBR is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 45% by mass or more, and is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 55% by mass or less. Within the above ranges, the effect tends to be better obtained.

[0032] The rubber composition contains a butadiene rubber (BR) as a rubber component. 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.

[0033] The cis amount (cis content) of BR is preferably 90% by mass or less, more preferably 60% by mass or less, and even more preferably 40% by mass or less, and is preferably 5% 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 better obtained. The cis content of BR can be measured by infrared absorption spectroscopy.

[0034] 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)).

[0035] 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.

[0036] The rubber composition contains an isoprene-based rubber as a rubber component. 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.

[0037] In 100% by mass of the rubber component, the content of the isoprene-based rubber is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, and is preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less. Within the above ranges, the effect tends to be better obtained.

[0038] In the above rubber composition, the SBR content>the isoprene-based rubber content>the BR content.

[0039] The ratio of the SBR content to the isoprene rubber content is preferably 1.1 or more, and is preferably 2.5 or less, more preferably 2.0 or less, and further preferably 1.5 or less. Within the above range, the effect tends to be better obtained.

[0040] The ratio of the isoprene rubber content to the BR content is preferably 1.5 or more, more preferably 2.0 or more, and even more preferably 2.5 or more, and is preferably 5.0 or less, more preferably 4.0 or less, and even more preferably 3.0 or less. Within the above ranges, the effect tends to be better obtained.

[0041] In these relationships, the SBR content, the isoprene-based rubber content, and the BR content are the contents in 100% by mass of the rubber component (unit: mass %).

[0042] Examples of rubber components that can be used 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.

[0043] 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.

[0044] 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.

[0045] The rubber composition contains silica. 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.

[0046] The CTAB specific surface area of ​​the silica is preferably 160 m 2 / g or more, more preferably 180m 2 / g or more, more preferably 200m 2 / g or more, and preferably 250m 2 / g or less, more preferably 230m 2 / g or less, more preferably 220m 2 Within the above range, there is a tendency for the effect to be better obtained. The CTAB specific surface area of ​​silica is measured in accordance with ASTM D3765-92.

[0047] The content of silica is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 60 parts by mass or more, and is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 80 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.

[0048] From the viewpoint of wet steering stability and the like, it is preferable that the silica content in the rubber composition is greater than the SBR content.

[0049] The silica content / SBR content is preferably 1.1 or more, more preferably 1.3 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 range, the effect tends to be better.

[0050] In these relationships, the silica content is the content (unit: parts by mass) relative to 100 parts by mass of the rubber component, and the SBR content is the content (unit: % by mass) in 100% by mass of the rubber component.

[0051] The rubber composition preferably contains a silane coupling agent. The silane coupling agent is not particularly limited, and examples thereof include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl, mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane and 2-mercaptoethyltriethoxysilane; vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. As commercially available products, for example, products from Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., Toray Dow Corning Co., Ltd., etc. can be used. These may be used alone or in combination of two or more. Among them, mercapto-based products are preferred.

[0052] As the mercapto-based silane coupling agent, in addition to a compound having a mercapto group, a compound having a structure in which the mercapto group is protected by a protecting group (for example, a compound represented by the following formula (S1)) can also be used.

[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 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 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. 1004As 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 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.

[0062] The rubber composition contains a resin component. The resin component is not particularly limited, but a styrene-based resin can be suitably used. The styrene-based resin is a polymer containing a styrene-based monomer as a constituent monomer, and examples thereof include a homopolymer obtained by polymerizing one type of styrene-based monomer alone, a copolymer obtained by copolymerizing two or more types of styrene-based monomers, and a copolymer of a styrene-based monomer and another monomer that can be copolymerized therewith.

[0063] Examples of styrene monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, and p-chlorostyrene. These may be used alone or in combination of two or more. Among them, styrene and α-methylstyrene are preferred.

[0064] Examples of other monomers include terpene compounds (terpene monomers) such as α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol, and non-conjugated olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene. These may be used alone or in combination of two or more.

[0065] From the viewpoint of wet steering stability, etc., the styrene-based resin may suitably be a copolymer of α-methylstyrene and styrene, a copolymer of a terpene compound and styrene, or a copolymer of styrene and ethylene, and a copolymer of a terpene compound and styrene is particularly preferred.

[0066] The amount of the styrene resin is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, and is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, 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.

[0067] The rubber composition may contain a resin other than the styrene-based resin.

[0068] 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.

[0069] The content of the resin component (when multiple types of resins are used in combination, the total content thereof) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, relative to 100 parts by mass of the rubber component, and is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. Within the above ranges, the effect tends to be better obtained.

[0070] From the viewpoint of wet steering stability and the like, it is preferable that in the rubber composition, the resin amount of the resin component is greater than the total styrene amount in the rubber component.

[0071] The resin amount of the resin component / the total styrene amount in the rubber component is preferably 1.1 or more, and preferably 2.5 or less, more preferably 2.0 or less, and even more preferably 1.5 or less. Within the above range, the effect tends to be better obtained.

[0072] In these relationships, the content of the resin component is the content (unit: parts by mass) relative to 100 parts by mass of the rubber component, and the total amount of styrene in the rubber component is the total content of styrene parts contained in the total amount of the rubber component (unit: mass%).

[0073] In the rubber composition, the resin component content / silica content is preferably 0.1 or more, more preferably 0.2 or more, and is preferably 0.8 or less, more preferably 0.6 or less, and even more preferably 0.4 or less. Within the above ranges, the effect tends to be better obtained. In this relationship, the resin component content and the silica content are the contents (unit: parts by mass) relative to 100 parts by mass of the rubber component.

[0074] 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.

[0075] In the rubber composition, the content of the calcium compound is preferably 0.1 parts by mass or more, and preferably 1.5 parts by mass or less, more preferably 0.8 parts by mass or less, and further preferably 0.5 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.

[0076] In the above rubber composition, the content of the resin component is greater than the content of the calcium compound calculated as calcium element.

[0077] The ratio of the resin component content to the calcium compound content in terms of calcium element is preferably 50 or more, more preferably 100 or more, and even more preferably 150 or more, and is preferably 300 or less, more preferably 250 or less, and even more preferably 200 or less. Within the above ranges, the effect tends to be better obtained.

[0078] In these relationships, the content of the resin component and the content of the calcium compound converted to elemental calcium are the contents (unit: parts by mass) relative to 100 parts by mass of the rubber component.

[0079] 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]

[0080] 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.

[0081] The content of the dibenzylamine 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 4 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.

[0082] The rubber composition preferably contains carbon black. The carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. 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.

[0083] The cetyltrimethylammonium bromide (CTAB) specific surface area of ​​the carbon black is preferably 80 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.

[0084] The amount of carbon black is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, 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, 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.

[0085] The rubber composition preferably contains a borate compound as a processing aid. Examples of borate compounds include alkali metal salts such as sodium borate and potassium borate, alkaline earth metal salts such as magnesium borate, and hydrates thereof. These may be used alone or in combination of two or more. Among these, alkali metal salts and hydrates thereof are preferred, sodium borate and hydrates thereof are more preferred, and sodium tetraborate decahydrate (borax) is even more preferred.

[0086] As commercially available borate compounds, products from Kishida Chemical Co., Ltd., Kenei Pharmaceutical Co., Ltd., etc. can be used.

[0087] The content of the borate compound is 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 5 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 3 parts by mass or less. When the content is within the above range, the effect tends to be better.

[0088] 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.

[0089] The content of the oil is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 6 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. Within the above ranges, the effect tends to be better obtained.

[0090] 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.

[0091] 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, 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. Within the above ranges, the effect tends to be better.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] The amount 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, based on 100 parts by mass of the rubber component. Within the above ranges, the effect tends to be better obtained.

[0098] 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.

[0099] 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 1.5 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. When the amount is within the above range, the effect tends to be better obtained.

[0100] 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.

[0101] 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, 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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 normal method to form an unvulcanized tire. The unvulcanized tire is then heated and pressurized in a vulcanizer to obtain a tire.

[0107] 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.

[0108] 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.

[0109] It is preferable that the tire outer diameter Dt and the tire section width Wt of the tire satisfy the following relational expression.

number

[0110] 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.

[0111] 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

[0112] The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[0113] The various chemicals used in the examples and comparative examples will be described below.

[0114] (Rubber component) Natural rubber: TSR20 SBR1: Synthesized according to Production Example 1 below (styrene content: 25% by mass, vinyl content: 60% by mass, Mw: 300,000) SBR2: Buna VSL 5228-2 manufactured by LANXESS (styrene content: 28% by mass, vinyl content: 52% by mass, contains 37.5 parts by mass of oil per 100 parts by mass of rubber solids) SBR3: JSR0122 manufactured by JSR Corporation (styrene content: 37% by mass, vinyl content: 14% by mass, contains 34 parts by mass of oil per 100 parts by mass of rubber solids) BR1: BR150B manufactured by Ube Industries, Ltd. (cis content: 97% by mass, vinyl content: 1% by mass) BR2: N103 manufactured by Asahi Kasei Chemicals Corporation (cis content: 38% by mass, vinyl content: 12% by mass)

[0115] (Chemicals other than rubber components) Carbon black: N220 (CTAB: 111m 2 / g) Silica 1: Ultrasil VN3 (CTAB: 165 m) manufactured by Evonik Degussa 2 / g) Silica 2: Rhodia Zeosil Premium 200MP (CTAB:203m 2 / g) Silane coupling agent 1: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa Silane coupling agent 2: NXT (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive Oil: H&R VIVATEC 500 (TDAE oil) Resin 1: Sylvatraxx 4401 (α-methylstyrene resin (copolymer of α-methylstyrene and styrene)) manufactured by Arizona Chemical Company Resin 2: YS Resin TO125 (terpene styrene resin (copolymer of terpene compounds and styrene)) manufactured by Yasuhara Chemical Co., Ltd. Resin 3: Struktol 40MS (a copolymer of styrene and ethylene) manufactured by Struktol Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd. Antioxidant 1: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Antioxidant 2: Nocrac RD (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Calcium compound: WB16 manufactured by Struktol (mixture of fatty acid calcium, fatty acid amide and fatty acid amide ester, calcium element content: approximately 5% by mass) Processing aid: Sodium tetraborate decahydrate manufactured by Kishida Chemical Co., Ltd. Stearic acid: NOF Corporation's "Tsubaki" stearic acid Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi 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: Noccelaer D (diphenyl guanidine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Dibenzylamine compound: Sancerer TBzTD (tetrabenzyl thiuram disulfide) manufactured by Sanshin Chemical Industry Co., Ltd.

[0116] (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-(3-dimethylaminopropyl)acrylamide was added as a modifier and the reaction was continued. 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 SBR1.

[0117] 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.

[0118] (Wet driving stability) The lap time was measured when a vehicle fitted with the above test tires on all wheels ran 10 laps around a test course on a wet road surface. A reference tire with a longer lap time than any of the examples and comparative examples was also used to run under similar conditions. The difference in lap time between each example and comparative example and the reference tire was expressed as an index, with Comparative Example 2 being set at 100. The larger the index, the larger the difference from the lap time of the reference tire (reduction in lap time) and the more excellent the wet steering stability (steering stability on a wet road surface).

[0119] [Table 1]

[0120] As can be seen from Table 1, the Examples were superior to the Comparative Examples in terms of the desired wet steering stability.

Claims

1. The rubber component includes a styrene-butadiene rubber, a butadiene rubber, and an isoprene-based rubber, and the rubber component includes silica, a resin component, and a calcium compound, the content of the styrene-butadiene rubber>the content of the isoprene-based rubber>the content of the butadiene rubber, A rubber composition for a tire, wherein the content of the resin component is greater than the content of the calcium compound calculated as calcium element, the resin amount in the resin component is greater than the total styrene amount in the rubber component, The rubber composition for tires, wherein the calcium compound is fatty acid calcium.

2. The rubber component includes a styrene-butadiene rubber, a butadiene rubber, and an isoprene-based rubber, and the rubber component includes silica, a resin component, and a calcium compound, the content of the styrene-butadiene rubber>the content of the isoprene-based rubber>the content of the butadiene rubber, A rubber composition for tires, wherein the content of the resin component is greater than the content of the calcium compound calculated as calcium element. The cetyltrimethylammonium bromide adsorption specific surface area of ​​the silica is 180 m ２ / g or more, The rubber composition for tires, wherein the calcium compound is fatty acid calcium.

3. The rubber component includes a styrene-butadiene rubber, a butadiene rubber, and an isoprene-based rubber, and the rubber component includes silica, a resin component, and a calcium compound, the content of the styrene-butadiene rubber>the content of the isoprene-based rubber>the content of the butadiene rubber, A rubber composition for a tire, wherein the content of the resin component is greater than the content of the calcium compound calculated as calcium element, Contains mercapto-based silane coupling agent, The rubber composition for tires, wherein the calcium compound is fatty acid calcium.

4. The rubber composition for tires according to any one of claims 1 to 3, wherein the content of said silica is greater than the content of said styrene-butadiene rubber.

5. The rubber composition for tires according to any one of claims 1 to 4, wherein the cis content of the butadiene rubber is 90% or less.

6. 4. The rubber composition for tires according to claim 2, wherein the resin amount of the resin component is greater than the total styrene amount in the rubber component.

7. The rubber composition for tires according to any one of claims 1 to 6, wherein the resin component contains a styrene-based resin.

8. The cetyltrimethylammonium bromide adsorption specific surface area of ​​the silica is 180 m ２ The rubber composition for tires according to claim 1 or 3, wherein the viscosity is 1 / g or more.

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

10. The rubber composition for tires according to any one of claims 1 to 9, which contains a dibenzylamine compound.

11. A tire using the rubber composition according to any one of claims 1 to 10.

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