Rubber composition for tires and tires

Abstract

To provide a rubber composition for tires and a tire which are capable of improving overall performance of fuel economy and wet grip performance.SOLUTION: The present invention relates to the rubber composition for tires which contains a rubber component containing a styrene-butadiene rubber and an isoprene rubber, silica, a resin component, and a calcium compound. The following relations are satisfied: (the amount of acetone extraction)>(the content of the isoprene rubber); (the content of the isoprene rubber)>(the content of the resin component); 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 fuel economy and grip performance have been studied (for example, see Patent Documents 1 and 2). However, in recent years, further improvements in these performances have been required. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2000-344955 A [Patent Document 2] Patent No. 6033786 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 the overall performance of fuel economy and wet grip performance. [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 and an isoprene-based rubber, silica, a resin component, and a calcium compound, wherein the acetone extractable amount > the content of the isoprene-based rubber, the content of the isoprene-based rubber > the content of the resin component, and the content of the resin component > the content of the calcium compound in terms of calcium element.

[0006] The calcium compound is preferably a fatty acid salt.

[0007] The average particle size of the silica is preferably 18 nm or less.

[0008] The rubber composition preferably contains a mercapto-based silane coupling agent.

[0009] The content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 20 to 50% by mass.

[0010] It is preferable that the content of the resin component is 50% by mass or more in 100% by mass of the acetone extract.

[0011] The resin component preferably contains a terpene resin.

[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 and an isoprene-based rubber, silica, a resin component, and a calcium compound, and satisfies the following relationships: acetone extractable amount > isoprene-based rubber content, the isoprene-based rubber content > resin component content, and the resin component content > calcium compound content in terms of calcium element, thereby achieving good overall performance in terms of fuel economy and wet grip performance. 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 and an isoprene-based rubber, silica, a resin component, and a calcium compound, and satisfies the following conditions: acetone extractable amount > content of isoprene-based rubber, content of isoprene-based rubber > content of resin component, and content of resin component > content of 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 acetone extractable amount > isoprene-based rubber content > resin component content, the high molecular weight isoprene-based rubber is sufficiently plasticized and the resin component is easily incorporated into the isoprene-based rubber phase, which is thought to increase adhesion and improve wet grip performance. In addition, in the above rubber composition, by satisfying the relationship of "content of resin component>content of calcium compound converted into calcium element," it is possible to suppress adhesion of the resin component to rolls, etc. during kneading, and to apply sufficient mechanical shear to the kneaded material. These actions promote uniform mixing of the polymer (rubber component) phase and dispersion of silica and resin in the polymer phase, improving silica-polymer interaction and adhesion, which is believed to result in a significant improvement in overall fuel economy and wet grip performance.

[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 overall performance such as fuel economy and wet grip performance, it is preferable that the total styrene amount in the rubber component of the rubber composition is less than the total vinyl amount 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 1.5 or more, more preferably 2.0 or more, and even more preferably 2.4 or more, and is preferably 4.5 or less, more preferably 3.5 or less, and even more preferably 3.0 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 15% by mass or more, more preferably 25% by mass or more, and even more preferably 30% 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 15% by mass or more, and even more preferably 20% 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 35% by mass or more, more preferably 45% by mass or more, and even more preferably 55% by mass or more, and is preferably 75% by mass or less, more preferably 70% by mass or less, and even more preferably 65% ​​by mass or less. Within the above ranges, the effect tends to be 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 50% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. Within the above ranges, the effect tends to be better obtained.

[0032] 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.

[0033] In 100% by mass of the rubber component, the content of the isoprene-based rubber is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, and is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 45% by mass or less. Within the above ranges, the effect tends to be better obtained.

[0034] Examples of rubber components that can be used other than SBR and isoprene-based rubber include diene-based rubbers such as 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, BR is preferred.

[0035] 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.

[0036] The cis amount (cis content) of BR is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, and is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less. Within the above ranges, the effect tends to be better obtained. The cis content of BR can be measured by infrared absorption spectroscopy.

[0037] 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)).

[0038] In 100% by mass of the rubber component, the content of BR is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, and is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less. Within the above ranges, the effect tends to be better obtained.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] The average particle size of silica is preferably 24 nm or less, more preferably 17 nm or less, even more 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.

[0043] 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.

[0044] The content of silica is preferably 50 parts by mass or more, more preferably 65 parts by mass or more, and even more preferably 75 parts by mass or more, and is preferably 120 parts by mass or less, more preferably 90 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.

[0045] 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.

[0046] 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.

[0047] 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.)

[0048] 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. This R 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] The rubber composition contains a resin component. The resin component is not particularly limited, but aromatic resins and terpene resins can be preferably used. These may be used alone or in combination of two or more. Among them, terpene resins are preferred.

[0057] 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.

[0058] 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.

[0059] From the viewpoint of overall performance such as fuel economy and wet grip performance, the aromatic resin is preferably an α-methylstyrene resin (such as an α-methylstyrene homopolymer or a copolymer of α-methylstyrene and styrene), and more preferably a copolymer of α-methylstyrene and styrene.

[0060] The content of the aromatic resin is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more, and is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, and even more preferably 30 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.

[0061] Terpene resins are polymers that contain a terpene compound (terpene monomer) as a constituent monomer, and examples of such resins include homopolymers in which one type of terpene compound is polymerized alone, copolymers in which two or more types of terpene compounds are copolymerized, and copolymers of a terpene compound and another monomer that can be copolymerized with the terpene compound.

[0062] Terpene compounds are (C5H8) n The hydrocarbons and their oxygen-containing derivatives represented by the composition 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 ), and examples thereof include α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol, etc. These may be used alone or in combination of two or more.

[0063] From the viewpoint of overall performance such as fuel economy and wet grip performance, the terpene resin is preferably a copolymer of a terpene compound and an aromatic monomer (aromatic modified terpene resin), and more preferably a copolymer of a terpene compound and styrene (terpene styrene resin). In this specification, a polymer containing a terpene compound and an aromatic monomer as constituent monomers, such as a terpene styrene resin, is treated as a terpene resin rather than an aromatic resin.

[0064] The amount of the terpene resin is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more, and is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, and even more preferably 30 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.

[0065] 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.

[0066] The content of the resin component (when multiple types of resins are used in combination, the total content) is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 25 parts by mass or more, particularly preferably 30 parts by mass or more, and is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less, based on 100 parts by mass of the rubber component. Within the above range, the effect tends to be better obtained.

[0067] In the above rubber composition, the content of the isoprene-based rubber is greater than the content of the resin component.

[0068] The ratio of the isoprene rubber content to the resin component content is preferably 1.5 or more, more preferably 1.8 or more, even more preferably 2.0 or more, and particularly preferably 2.2 or more, and is preferably 4.5 or less, more preferably 3.5 or less, and even more preferably 3.0 or less. Within the above ranges, the effect tends to be better obtained.

[0069] In these relationships, the isoprene-based rubber content is the content (unit: mass %) in 100% by mass of the rubber component, and the resin component content is the content (unit: mass parts) relative to 100 parts by mass of the rubber component.

[0070] In the rubber composition, the resin component content / silica content is preferably 0.05 or more, more preferably 0.10 or more, and even more preferably 0.20 or more, and is preferably 0.80 or less, more preferably 0.60 or less, even more preferably 0.40 or less, and particularly preferably 0.30 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.

[0071] 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.

[0072] In the rubber composition, the content of the calcium compound is, calculated as calcium element, preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, even more preferably 0.05 parts by mass or more, and is preferably 0.40 parts by mass or less, more preferably 0.25 parts by mass or less, even more preferably 0.15 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.

[0073] In the above rubber composition, the content of the resin component is greater than the content of the calcium compound calculated as calcium element.

[0074] The ratio of the resin component content to the calcium compound content in terms of calcium element is preferably 10 or more, more preferably 100 or more, even more preferably 200 or more, particularly preferably 300 or more, and is preferably 600 or less, more preferably 500 or less, and even more preferably 400 or less. Within the above ranges, the effect tends to be better obtained.

[0075] 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.

[0076] 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]

[0077] 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.

[0078] The content of the dibenzylamine compound is preferably 0.1 parts by mass or more, preferably 0.3 parts by mass or more, 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.

[0079] 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.

[0080] The cetyltrimethylammonium bromide (CTAB) specific surface area of ​​the carbon black is preferably 110 m 2 / g or more, more preferably 120m 2 / g or more, more preferably 130m 2 / g or more, and preferably 200m 2 / g or less, more preferably 160m 2 / g or less, more preferably 140m 2 Within the above range, there is a tendency for the effect to be better obtained. The CTAB specific surface area of ​​carbon black is a value measured in accordance with JIS K6217-3:2001.

[0081] 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.

[0082] 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.

[0083] 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 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. Within the above ranges, the effect tends to be better obtained.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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 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.

[0096] 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.

[0097] In the rubber composition, the amount of acetone extraction is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 45 parts by mass or less, and is preferably 10 parts by mass or more, more preferably 25 parts by mass or more, even more preferably 35 parts by mass or more, and particularly preferably 40 parts by mass or more, based on 100 parts by mass of the rubber component. When it is within the above range, the effect tends to be better obtained. The acetone extractable amount (phr (parts by mass)) can be calculated by the following formula using the value (% by mass) measured by extracting the above-mentioned rubber composition after vulcanization with acetone for 24 hours using a method in accordance with JIS K 6229:2015 and the amount (% by mass) of rubber components determined by acetone extractable amount thermogravimetric analysis (TGA) or the like. Acetone extractables (phr) = Acetone extractables (mass%) / Amount of rubber component (mass%) × 100

[0098] In 100% by mass of the acetone extract, the content of the resin component is preferably 10% by mass or more, more preferably 25% by mass or more, even more preferably 40% by mass or more, particularly preferably 50% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. Within the above ranges, the effect tends to be better obtained. The content of resin components in 100% by mass of acetone extract can be calculated from the analysis results of the acetone extract and the blended amount of resin components. In addition, if the type of resin (terpene, styrene, etc.) is known, it can also be estimated using a standard sample prepared by varying the amount of the same type of resin.

[0099] In the above rubber composition, the acetone extractable amount is greater than the content of isoprene-based rubber.

[0100] The acetone extractable amount / isoprene rubber content is preferably 1.1 or more, and is preferably 4.0 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.

[0101] In these relationships, the acetone extractable amount is the amount (unit: parts by mass) relative to 100 parts by mass of the rubber component, and the isoprene-based rubber content is the content (unit: mass %) in 100% by mass of the rubber component.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] It is preferable that the tire outer diameter Dt and the tire section width Wt of the tire satisfy the following relational expression.

number

[0109] 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.

[0110] 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

[0111] The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[0112] The various chemicals used in the examples and comparative examples will be described below.

[0113] (Rubber component) Natural rubber: TSR20 SBR1: 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) SBR2: JSR1502 manufactured by JSR Corporation (styrene content: 24% by mass, vinyl content: 16% by mass) SBR3: Modified SBR synthesized in Production Example 1 below (styrene content: 25% by mass, vinyl content: 60% by mass, Mw: 150,000) SBR4: Modified SBR synthesized in Production Example 2 below (styrene content: 10% by mass, vinyl content: 40% by mass, Mw: 200,000) BR: BR150B manufactured by Ube Industries, Ltd. (cis content: 97% by mass, vinyl content: 1% by mass)

[0114] (Chemicals other than rubber components) Carbon black: N134 (CTAB: 135m 2 / g) Silica 1: ZEOSIL 1115MP manufactured by Rhodia (average particle size: 24 nm) Silica 2: Ultrasil VN3 manufactured by Evonik Degussa (average particle size: 17 nm) Silica 3: Ultrasil 9100GR (average particle size: 15 nm) manufactured by Evonik Degussa Silane coupling agent 1: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa Silane coupling agent 2: NXT (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive 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. 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 1: Takehara Chemical Industry Co., Ltd.'s Tankal #200 (calcium carbonate, calcium element content: about 40% by mass) Calcium compound 2: WB16 manufactured by Struktol (a mixture of fatty acid calcium, fatty acid amide and fatty acid amide ester, calcium element content: approximately 5% by mass) 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 NS (N-tert-butyl-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.

[0115] (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%, butadiene was added, and polymerization was continued for another 5 minutes, after which 3-diethylaminopropyltrimethoxysilane was added as a modifier and the reaction was continued for 15 minutes. 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.

[0116] (Production Example 2) 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%, butadiene was added, and polymerization was continued for another 5 minutes, after which 3-dimethylaminopropyltriethoxysilane was added as a modifier and the reaction was continued for 15 minutes. 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 SBR4.

[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] (Acetone extractables) A sample (vulcanized rubber composition) was taken from the tread of the test tire, and the sample was subjected to acetone extraction for 24 hours according to a method in accordance with JIS K 6229: 2015 to measure the amount of acetone extracted. The amount of acetone extracted (phr (parts by mass)) per 100 parts by mass of the rubber component was calculated using the amount of acetone extracted (% by mass) obtained and the amount of rubber component in the sample (% by mass) determined by TGA.

[0119] (low fuel consumption) Using a rolling resistance tester, the rolling resistance of each test tire was measured when it was run at a speed (80 km / h), and the rolling resistance was expressed as an index with Comparative Example 1 being set at 100. A higher index indicates lower rolling resistance and better fuel economy.

[0120] (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 1 being set at 100. A higher index indicates a shorter braking distance and better wet grip performance.

[0121] [Table 1]

[0122] As can be seen from Table 1, the Examples were superior to the Comparative Examples in the overall performance (total of each index) of the targeted fuel economy and wet grip performance.

Claims

1. The composition contains a rubber component including a styrene-butadiene rubber and an isoprene-based rubber, silica, a resin component, a calcium compound, and a dibenzylamine compound, the amount of acetone extractables is greater than the content of the isoprene-based rubber, the content of the isoprene-based rubber is greater than the content of the resin component, The rubber composition for tires, wherein the content of the resin component is greater than the content of the calcium compound calculated as calcium element.

2. 2. The rubber composition for tires according to claim 1, wherein the calcium compound is a fatty acid salt.

3. 3. The rubber composition for tires according to claim 1, wherein the average particle size of the silica is 18 nm or less.

4. The rubber composition for tires according to any one of claims 1 to 3, further comprising a mercapto-based silane coupling agent.

5. 5. The rubber composition for tires according to claim 1, wherein the content of the isoprene-based rubber is 20 to 50 mass % based on 100 mass % of the rubber component.

6. 6. The rubber composition for tires according to claim 1, wherein the content of the resin component is 50% by mass or more based on 100% by mass of the acetone extractable amount.

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

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

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