Rubber composition for tires and tires

Abstract

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

Description

Technical Field

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

Background Art

[0002] Conventionally, various methods for improving wear resistance have been studied (see, for example, Patent Document 1). However, in recent years, further improvement in wear resistance has been demanded.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems 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 solve the above problems and can improve wear resistance.

Means for Solving the Problems

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

[0006] Preferably, the rubber composition contains a resin.

[0007] Preferably, the rubber composition contains a dialkyldithiophosphate compound.

[0008] It is preferable that the rubber composition contains butadiene rubber and the cis amount of the butadiene rubber is 90% by mass or less.

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

[0010] The rubber composition contains an isoprene rubber and a resin, and it is preferable that the content of the isoprene rubber ≤ the content of the resin.

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

[0012] It is preferable that the average particle diameter of the silica is 16 nm or less.

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

Advantages of the Invention

[0014] The present invention contains a rubber component containing styrene-butadiene rubber, a filler containing carbon black and silica, a silane coupling agent, and a calcium compound. In 100% by mass of the rubber component, the content of styrene-butadiene rubber is 60% by mass or more, the content of the rubber component ≤ the content of the filler, the silane coupling agent is a mercapto-based silane coupling agent, and the content of carbon black ≥ the content of calcium in terms of calcium element of the calcium compound. Since it is a rubber composition for a tire, excellent abrasion resistance can be obtained.

Embodiments for Carrying Out the Invention

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

[0016] The reason why the above rubber composition produces the aforementioned effects is presumed to be as follows. In the above rubber composition, styrene-butadiene rubber, silica, carbon black, a mercapto-silane coupling agent, and a calcium compound are blended. Furthermore, by adjusting the amount of styrene-butadiene rubber within a predetermined range, and satisfying the relationship between the rubber component content ≤ filler content and the carbon black content ≥ calcium element content of the calcium compound, the interaction between silica and carbon black and the rubber component is effectively exhibited, and the reaction of the mercapto-silane coupling agent proceeds smoothly. Due to these effects, silica and carbon black are uniformly dispersed (distributed) within the rubber component, which is thought to effectively reinforce the rubber composition and significantly improve its abrasion resistance.

[0017] The above rubber composition contains rubber components. 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, even more preferably 200,000 or more, and also preferably 2,000,000 or less, more preferably 1,500,000 or less, even more preferably 1,000,000 or less, and particularly preferably 800,000 or less. Within this range, a better effect tends to be obtained.

[0019] In this specification, the weight-average molecular weight (Mw) can be determined by converting the measured values ​​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) to standard polystyrene equivalents.

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

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

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

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

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

[0025] The amounts of styrene and vinyl in each rubber component can be measured by nuclear magnetic resonance (NMR) spectroscopy. Furthermore, while the total amount of styrene and total amount of vinyl in the rubber component are calculated in accordance with the above-described formula in the examples of this specification, they may also be analyzed from the tire using, for example, a pyrolysis gas chromatograph-mass spectrometer (Py-GC / MS).

[0026] The above rubber composition contains styrene-butadiene rubber (SBR) as a rubber component. SBR is not particularly limited; for example, emulsion polymerized styrene-butadiene rubber (E-SBR) and solution polymerized styrene-butadiene rubber (S-SBR) can be used. Commercially available products include those from Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation.

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

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

[0029] The styrene and vinyl content of SBRs mentioned above refer to the styrene and vinyl content of a single type of SBR if that type is used, and to the average styrene and vinyl content if there are multiple types of SBRs. The average styrene content of SBR can be calculated using the formula {Σ(content of each SBR × styrene content of each SBR)} / total content of all SBR. For example, if 85% of the rubber component is SBR with a styrene content of 40% by mass and 5% is SBR with a styrene content of 25% by mass, the average styrene content of the SBR is 39.2% by mass (=(85 × 40 + 5 × 25) / (85 + 5)). Similarly, the average vinyl content of SBR can be calculated as {Σ(content of each SBR × vinyl content of each SBR)} / total content of all SBR. For example, if 85% of the rubber component is SBR with a vinyl content of 30% by mass and 5% is SBR with a vinyl content of 20% by mass, the average vinyl content of the SBR is 29.4% by mass (=(85 × 30 + 5 × 20) / (85 + 5)).

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

[0031] Other rubber components that can be used besides SBR include isoprene rubber, butadiene rubber (BR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and diene rubbers such as styrene-isoprene-butadiene copolymer rubber (SIBR). These may be used individually or in combination of two or more. Among these, isoprene rubber and BR are preferred.

[0032] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. For NR, examples include SIR20, RSS#3, TSR20, etc., which are commonly used in the tire industry. For IR, there are no particular limitations; examples include IR2200, etc., which are commonly used in the tire industry. Examples of modified NR include deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR). 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 individually or in combination of two or more. Among these, NR is preferred.

[0033] The isoprene-based rubber content in 100% by mass of the rubber component is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, and also preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less. Within the above range, a better effect tends to be obtained.

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

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

[0036] The cis amount of BR mentioned above refers to the cis amount of a single type of BR if there is only one type, and to the average cis amount if there are multiple types. The average cis content of BR can be calculated using the formula {Σ(content of each BR × cis content of each BR)} / total BR content. For example, if 20% of BR has a cis content of 90% and 10% has a cis content of 40% out of 100% of rubber components, the average cis content of BR is 73.3% (=(20 × 90 + 10 × 40) / (20 + 10)).

[0037] The BR content in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and also preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0038] The rubber component may have functional groups that interact with fillers such as silica introduced through modification. Examples of the above functional groups include amino groups, amide groups, silyl groups, alkoxysilyl groups, isocyanate groups, imino groups, imidazole groups, urea groups, ether groups, carbonyl groups, oxycarbonyl groups, mercapto groups, sulfide groups, disulfide groups, sulfonyl groups, sulfinyl groups, thiocarbonyl groups, ammonium groups, imide groups, hydrazo groups, azo groups, diazo groups, carboxyl groups, nitrile groups, pyridyl groups, alkoxy groups, hydroxyl groups, oxy groups, epoxy groups, and the like. These functional groups may have substituents. Among these, amino groups (preferably amino groups in which the hydrogen atoms of the amino group are substituted with C1-C6 alkyl groups), alkoxy groups (preferably alkoxy groups having C1-C6), and alkoxysilyl groups (preferably alkoxysilyl groups having C1-C6) are preferred.

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

[0040] The above rubber composition contains carbon black as a filler. The carbon black used is not particularly limited and includes N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. Commercially available products from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nippon Chemical Carbon Co., Ltd., Columbia Carbon, etc. can be used. These may be used individually or in combination of two or more types.

[0041] The specific surface area of ​​cetyltrimethylammonium bromide (CTAB) in carbon black is preferably 90 m². 2 / g or more, comfortably 100m 2 / g or more, more preferably 110m 2 It is 160m or more / g, and preferably 160m 2 / g or less, more preferably 140m 2 / g or less, more preferably 130m 2 It is less than or equal to / g. Within the above range, there is a tendency for better results to be obtained. The CTAB specific surface area of ​​carbon black is measured according to JIS K6217-3:2001.

[0042] The carbon black content 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, per 100 parts by mass of rubber component, and also preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less. Within the above range, a better effect tends to be obtained.

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

[0044] The average particle size of silica is preferably 20 nm or less, more preferably 17 nm or less, even more preferably 16 nm or less, and particularly preferably 15 nm or less. It is also preferably 6 nm or more, more preferably 9 nm or more, and even more preferably 12 nm or more. When the particle size is within the above range, a better effect tends to be obtained.

[0045] In this specification, the method for measuring the average particle size of silica is transmission electron microscopy (TEM) observation. Specifically, silica particles are photographed with a transmission electron microscope, and if the particle shape is spherical, the diameter of the sphere is defined as the particle size; if it is needle-shaped or rod-shaped, the shorter axis is defined as the particle size; if it is irregularly shaped, the average particle size from the center is defined as the particle size; and the average value of the particle sizes of 100 fine particles is defined as the average particle size.

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

[0047] Other fillers that can be used besides carbon black and silica include aluminum hydroxide, talc, mica, magnesium oxide, and magnesium sulfate, which are common in the tire industry. These may be used individually or in combination of two or more.

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

[0049] In the above rubber composition, the content of the rubber component is less than or equal to the content of the filler.

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

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

[0052] The above rubber composition contains a mercapto-silane coupling agent. Mercapto-silane coupling agents are silane coupling agents having a mercapto group, such as 3-mercaptopropyltrimethoxysilane and 2-mercaptoethyltriethoxysilane. Furthermore, compounds in which the mercapto group is protected by a protecting group (for example, compounds represented by the following formula (S1)) can also be used as mercapto-silane coupling agents.

[0053] Particularly preferred mercapto-based silane coupling agents include silane coupling agents represented by the following formula (S1), and silane coupling agents containing a bonding unit A represented by the following formula (I) and a bonding unit B represented by the following formula (II).

Chemical formula

Chemical formula

Chemical formula

[0054] In equation (S1), R 1005 , R 1006 , R 1007 and R 1008 Each of these is preferably independently selected from the group consisting of linear, cyclic, or branched alkyl groups, alkenyl groups, aryl groups, and aralkyl groups having 1 to 18 carbon atoms. 1002 If 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 The alkylene group is preferably linear, cyclic, or branched, and is particularly preferred to be linear. 1004 Examples of these include alkylene groups having 1 to 18 carbon atoms, alkenylene groups having 2 to 18 carbon atoms, cycloalkylene groups having 5 to 18 carbon atoms, cycloalkylalkylene groups having 6 to 18 carbon atoms, arylene groups having 6 to 18 carbon atoms, and aralkylene groups having 7 to 18 carbon atoms. The alkylene groups and alkenylene groups may be linear or branched, and the cycloalkylene groups, cycloalkylalkylene groups, arylene groups, and aralkylene groups may have functional groups such as lower alkyl groups on their rings. 1004 Preferably, the alkylene group has 1 to 6 carbon atoms, and in particular, linear alkylene groups such as methylene, ethylene, trimethylene, tetramethylene, pentamethylene, and hexamethylene groups are preferred.

[0055] R in equation (S1) 1002 , R 1005 , R 1006 , R 1007 and R 1008 Specific examples include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, cyclopentyl group, cyclohexyl group, vinyl group, propenyl group, allyl group, hexenyl group, octenyl group, cyclopentenyl group, cyclohexenyl group, phenyl group, tolyl group, xylyl group, naphthyl group, benzyl group, phenethyl group, naphthylmethyl group, and the like. R in equation (S1) 1009 Examples of linear alkylene groups include methylene, ethylene, n-propylene, n-butylene, and hexylene groups, while examples of branched alkylene groups include isopropylene, isobutylene, and 2-methylpropylene groups.

[0056] Specific examples of silane coupling agents represented by formula (S1) include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, 3-lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexanoylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthioethyltrimethoxysilane, 2-decanoylthioethyltrimethoxysilane, and 2-lauroylthioethyltrimethoxysilane. These may be used individually or in combination of two or more. Among them, 3-octanoylthiopropyltriethoxysilane is particularly preferred.

[0057] In a silane coupling agent containing a bonding unit A represented by formula (I) and a bonding unit B represented by formula (II), the content of bonding unit A is preferably 30 mol% or more, more preferably 50 mol% or more, preferably 99 mol% or less, and more preferably 90 mol% or less. The content of bonding unit B is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 10 mol% or more, preferably 70 mol% or less, more preferably 65 mol% or less, and even more preferably 55 mol% or less. The total content of bonding units A and B is preferably 95 mol% or more, more preferably 98 mol% or more, and particularly preferably 100 mol%. The content of bonding units A and B includes the amount when bonding units A and B are located at the ends of the silane coupling agent. The form of bonding units A and B when they are located at the ends of the silane coupling agent is not particularly limited, as long as they form units corresponding to formulas (I) and (II) that represent bonding units A and B.

[0058] R in equations (I) and (II) 11 Examples of halogens include chlorine, bromine, and fluorine. Examples of branched or unbranched alkyl groups with 1 to 30 carbon atoms include methyl and ethyl groups. Examples of branched or unbranched alkenyl groups with 2 to 30 carbon atoms include vinyl and 1-propenyl groups. Examples of branched or unbranched alkynyl groups with 2 to 30 carbon atoms include ethynyl and propynyl groups.

[0059] R in equations (I) and (II) 12 Regarding branched or unbranched alkylene groups with 1 to 30 carbon atoms, examples include ethylene and propylene groups. Regarding branched or unbranched alkenylene groups with 2 to 30 carbon atoms, examples include vinylene and 1-propenylene groups. Regarding branched or unbranched alkylene groups with 2 to 30 carbon atoms, examples include ethynylene and propynylene groups.

[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 sum of the number of repeats of bonding unit A (v) and the number of repeats of bonding unit B (w), (v+w), is preferably in the range of 3 to 300.

[0061] The above rubber composition may contain silane coupling agents other than mercapto-based agents. Examples of usable silane coupling agents 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, and bis(4-trimethoxysilyl Examples include sulfide compounds such as butyl disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; vinyl compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. These may be used individually or in combination of two or more.

[0062] Commercially available silane coupling agents include products from companies such as Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and Toray Dow Corning Co., Ltd.

[0063] The content of the 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 preferably 15 parts by mass or less, more preferably 12 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of silica. Within the above range, a better effect tends to be obtained.

[0064] The above rubber composition contains a calcium compound. Calcium compounds are compounds containing calcium, such as inorganic salts like calcium oxide, calcium hydroxide, and calcium carbide; and oxo salts like calcium carbonate, calcium nitrate, and calcium sulfate. Oxo salts also include fatty acid salts such as calcium acetate and calcium stearate. Other examples of substances containing calcium compounds include eggshells (main component: calcium carbonate) and WB16 manufactured by Structol (a mixture of calcium fatty acid, fatty acid amide, and fatty acid amide ester). These may be used individually or in combination of two or more. Among these, oxo salts are preferred, and fatty acid salts (calcium fatty acid) are more preferred.

[0065] In this specification, calcium compounds are included in rubber compositions regardless of type or application, and may also be included in fillers, as well as in other processing aids, etc.

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

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

[0068] In the above rubber composition, the carbon black content / calcium element content of the calcium compound is preferably 10 or more, more preferably 15 or more, even more preferably 20 or more, particularly preferably 25 or more, and also preferably 50 or less, more preferably 40 or less, and even more preferably 30 or less. When the ratio is within the above range, a better effect tends to be obtained.

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

[0070] The above rubber composition preferably contains a resin. Examples of resins include cyclopentadiene resins, aromatic resins, and terpene resins. These may be used individually or in combination of two or more. Hydrogenated resins may also be used. Among these, cyclopentadiene resins and aromatic resins are preferred, with cyclopentadiene resins being more preferred.

[0071] Cyclopentadiene resins are polymers that contain cyclopentadiene monomers as constituent monomers. Examples include homopolymers obtained by polymerizing one type of cyclopentadiene monomer alone, copolymers obtained by copolymerizing two or more types of cyclopentadiene monomers, and copolymers of cyclopentadiene monomers with other monomers that can copolymerize with it.

[0072] Examples of cyclopentadiene monomers include cyclopentadiene, dicyclopentadiene, and tricyclopentadiene. These may be used individually or in combination of two or more. Dicyclopentadiene is particularly preferred.

[0073] For the reason that the effects tend to be better obtained, the cyclopentadiene resin is preferably a polymer containing dicyclopentadiene (DCPD) as a constituent monomer (DCPD resin), more preferably a copolymer of DCPD and an aromatic monomer, and even more preferably a copolymer of DCPD and a C9 fraction (vinyltoluene, indene, etc.) (DCPD-C9 resin). In this specification, polymers containing cyclopentadiene monomers and aromatic monomers as constituent monomers, such as DCPD-C9 resin, are treated as cyclopentadiene resins, not aromatic resins.

[0074] The content of the cyclopentadiene resin is preferably 5 parts by mass or more, more preferably 8 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of the rubber component, and also 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. When the content is within the above range, the effect tends to be better obtained.

[0075] Aromatic resins are polymers that contain aromatic monomers as constituent monomers. Examples include homopolymers obtained by polymerizing one type of aromatic monomer alone, copolymers obtained by copolymerizing two or more types of aromatic monomers, and copolymers of aromatic monomers with other monomers that can copolymerize with them.

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

[0077] For the reason that the effects tend to be better obtained, aromatic resins are preferably polymers containing α-methylstyrene as a constituent monomer (α-methylstyrene resins), and copolymers of α-methylstyrene and styrene are more preferred.

[0078] The aromatic resin content 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, per 100 parts by mass of the rubber component, and also preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. Within the above range, a better effect tends to be obtained.

[0079] Commercially available resins from companies such as 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 Energy Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Industries, Ltd. can be used.

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

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

[0082] In the above rubber composition, the resin content / isoprene rubber content is preferably 1.0 or more, more preferably 1.5 or more, even more preferably 2.0 or more, and also preferably 4.0 or less, more preferably 3.0 or less, and even more preferably 2.5 or less. When the ratio is within the above range, a better effect tends to be obtained.

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

[0084] In the above rubber composition, the resin content / silica content is preferably 0.05 or more, more preferably 0.10 or more, and also preferably 0.25 or less, more preferably 0.20 or less, and even more preferably 0.15 or less. When the ratio is within the above range, a better effect tends to be obtained. In this relationship, the resin content and silica content are expressed as the content per 100 parts by mass of rubber component (unit: parts by mass).

[0085] The above rubber composition preferably contains a dialkyldithiophosphate compound. As dialkyldithiophosphate compounds, for example, salts of dialkyldithiophosphate with metals such as zinc and molybdenum can be used. Commercial products such as those from Rhein Chemie can be used. These may be used individually or in combination of two or more. Among these, the compound represented by the following formula (1) (zinc dialkyldithiophosphate) is preferred. [ka] (In the formula, R 1 ~R 4 Each of these independently represents a linear or branched alkyl group having 1 to 18 carbon atoms, or a cycloalkyl group having 5 to 12 carbon atoms.

[0086] In equation (1), R 1 ~R 4Examples of linear or branched alkyl groups represented by include methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, 4-methylpentyl group, 2-ethylhexyl group, octyl group, octadecyl group, etc., while examples of cycloalkyl groups include cyclopentyl group, cyclohexyl group, cyclooctyl group, etc. Among these, R is particularly suitable because it disperses easily in rubber compositions and is easy to manufacture. 1 ~R 4 The group is preferably a linear or branched alkyl group having 2 to 8 carbon atoms, more preferably an n-butyl group, an n-propyl group, an iso-propyl group, or an n-octyl group, and even more preferably an n-butyl group.

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

[0088] The above rubber composition preferably contains a dibenzylamine compound. Dibenzylamine compounds are compounds that have at least one group represented by the following formula (a dibenzylamine group). [ka]

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

[0090] The content of the dibenzylamine compound is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and even more preferably 1 part by mass or less, per 100 parts by mass of the rubber component. Within this range, a better effect tends to be obtained.

[0091] The above rubber composition may contain an anti-aging agent. Examples of anti-aging agents include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents 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 include p-phenylenediamine-based antioxidants such as 2,2,4-trimethyl-1,2-dihydroquinoline polymers and other quinoline-based antioxidants; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate]methane. 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 individually or in combination of two or more.

[0092] The amount of the antioxidant is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, and preferably 8 parts by mass or less, more preferably 6 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of the rubber component. When the amount is within the above range, a better effect tends to be obtained.

[0093] The above rubber composition may contain oil. Examples of oils include process oils, vegetable oils, or mixtures thereof. Examples of process oils include paraffinic process oils, aromatic process oils, naphthenic process oils, etc. Examples of vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, tung oil, etc. Commercial products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., JXTG Energy Corporation, Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., etc. may be used. These may be used individually or in combination of two or more types.

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

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

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

[0097] In these relationships, the total amount of styrene in the rubber component is the total amount of styrene contained in the entire rubber component (unit: mass%), and the oil content is the amount per 100 mass parts of the rubber component (unit: mass parts).

[0098] The above rubber composition may contain wax. The wax is not particularly limited and can be any petroleum-based wax such as paraffin wax or microcrystalline wax; a natural wax such as plant-based wax or animal-based wax; or a synthetic wax such as polymers of ethylene or propylene. Commercially available products from companies such as Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Seiko Chemical Co., Ltd. can be used. These can be used individually or in combination of two or more types.

[0099] The wax content is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 10 parts by mass or less, and more preferably 6 parts by mass or less, per 100 parts by mass of rubber component. Within this range, a better effect tends to be obtained.

[0100] The above rubber composition may contain stearic acid. Conventional known stearic acid can be used, and commercially available products from companies such as NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries Ltd., and Chiba Fatty Acid Co., Ltd. can be used. These may be used individually or in combination of two or more types.

[0101] The stearic acid content is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 10 parts by mass or less, and more preferably 6 parts by mass or less, per 100 parts by mass of the rubber component. Within this range, a better effect tends to be obtained.

[0102] The above rubber composition may contain zinc oxide. Conventional known zinc oxides can be used, and commercially available products from companies such as Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., and Sakai Chemical Industry Co., Ltd. can be used. These may be used individually or in combination of two or more types.

[0103] The zinc oxide content is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and preferably 10 parts by mass or less, and more preferably 6 parts by mass or less, per 100 parts by mass of the rubber component. Within this range, a better effect tends to be obtained.

[0104] The above rubber composition may contain sulfur. Examples of sulfur commonly used in the rubber industry include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur. Commercially available products from companies such as Tsurumi Chemical Industries, Karuizawa Sulfur Co., Ltd., Shikoku Chemicals Co., Ltd., Flexis Co., Ltd., Nippon Dry Distillation Co., Ltd., and Hosoi Chemical Industry Co., Ltd. can be used. These may be used individually or in combination of two or more types.

[0105] The sulfur content is preferably 0.8 parts by mass or more, more preferably 1.2 parts by mass or more, even more preferably 1.6 parts by mass or more, per 100 parts by mass of rubber component, and also 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. Within the above range, a better effect tends to be obtained.

[0106] The above rubber composition may contain a vulcanization accelerator. Examples of vulcanization accelerators include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole and di-2-benzothiazolyl disulfide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD) and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiadylsulfenamide (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, dioltotolylguanidine, and orthotolylbiguanidine. Commercially available products include those from Sumitomo Chemical Co., Ltd. and Ouchi Shinko Chemical Co., Ltd. These may be used individually or in combination of two or more.

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

[0108] In addition to the above components, the above rubber composition may further contain additives commonly used in the tire industry, such as organic peroxides; fillers such as talc, alumina, clay, aluminum hydroxide, and mica. The content of these additives is preferably 0.1 to 200 parts by mass per 100 parts by mass of the rubber component.

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

[0110] Regarding the mixing conditions, in the base mixing step where additives other than the vulcanizing agent and vulcanization accelerator are mixed, the mixing temperature is usually 100 to 180°C, preferably 120 to 170°C. In the finish mixing step where the vulcanizing agent and vulcanization accelerator are mixed, the mixing temperature is usually 120°C or lower, preferably 85 to 110°C. Furthermore, the composition mixed with the vulcanizing agent and vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 140 to 190°C, preferably 150 to 185°C. The vulcanization time is usually 5 to 15 minutes.

[0111] The above rubber composition can be used (as a tire rubber composition) in tire components such as the tread (cap tread), sidewall, base tread, under tread, shoulder, clinch, bead apex, breaker cushion rubber, carcass cord covering rubber, insulation, chafer, inner liner, etc., as well as the side reinforcement layer of run-flat tires. It is particularly suitable for use in treads.

[0112] The tire of the present invention is manufactured by conventional methods using the above-mentioned rubber composition. Specifically, the rubber composition is extruded to match the shape of the tread at the unvulcanized stage, and then molded together with other tire components in a conventional manner on a tire molding machine to form an unvulcanized tire. This unvulcanized tire is then heated and pressurized in a vulcanizing machine to obtain a tire.

[0113] Furthermore, the tread of the tire may be composed of at least a portion of the above-mentioned rubber composition, or it may be composed entirely of the above-mentioned rubber composition.

[0114] The above-mentioned tires (pneumatic tires, etc.) can be used for passenger car tires; truck and bus tires; motorcycle tires; high-performance tires; winter tires such as studless tires; run-flat tires with side reinforcement layers; tires with sound-absorbing materials such as sponges inside the tire cavity; tires with sealing materials that can be sealed in the event of a puncture inside the tire or tire cavity; and tires with electronic components that have electronic components such as sensors and wireless tags inside the tire or tire cavity, and are particularly suitable for passenger car tires.

[0115] The tire sizes mentioned above are not particularly limited; for example, tire widths can be selected within the range of 100-400mm, aspect ratios within the range of 25-85%, and rim diameters within the range of 10-25 inches, as appropriate. 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, 295 / 45R20, etc.

[0116] The above-mentioned tire preferably satisfies the following relationship between the tire outer diameter Dt and the tire section width Wt.

number

[0117] 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, etc.

[0118] Tires that satisfy the above formula are preferably applied to pneumatic tires for passenger cars. This is because pneumatic tires for passenger cars that satisfy the above formula tend to be more suitable for solving the problems of this invention. [Examples]

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

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

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

[0122] (Chemicals other than rubber components) Carbon Black: N220 (CTAB: 111m) 2 / g) Silica 1: Evonik DeGussa's UltraSil 9100GR (average particle size: 15nm) Silica 2: UltraSil VN3 manufactured by Evonik DeGussa (average particle size: 17nm) Silane coupling agent 1: NXT-Z45 manufactured by Momentive (a copolymer of bond unit A and bond unit B (bond unit A: 55 mol%, bond unit B: 45 mol%)) Silane coupling agent 2: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik DeGussa. Oil: H&R VIVATEC500 (TDAE oil) Resin 1: Oppera PR-395 (hydrogenated DCPD-C9 resin) manufactured by Exxon Mobil Resin 2: Sylvatraxx 4401 (α-methylstyrene-based resin (polymer of α-methylstyrene and styrene)) manufactured by Arizona Chemical Corporation. Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd. Anti-aging agent 1: Nocrack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Anti-aging agent 2: Antigen FR manufactured by Sumitomo Chemical Co., Ltd. (a quinoline-based anti-aging agent produced by purifying the reaction product of amines and ketones, with no residual amines) Stearic acid: Stearic acid "Tsubaki" manufactured by NOF Corporation Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Processing aid: WB16 manufactured by Structol (a mixture of calcium fatty acid, fatty acid amide, and fatty acid amide ester; calcium element content: approximately 5% by mass) Sulfur: HK-200-5 (5% by mass oil-containing powdered sulfur) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator: Noxellar CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Dibenzylamine compound: Sunceller TBzTD (tetrabenzyl thiuram disulfide) manufactured by Sanshin Chemical Industry Co., Ltd. Dialkyldithiophosphate compounds: TP-50 (a mixture of zinc dithiophosphate and polymer, formula (1)) manufactured by Rhein Chemie. 1 ~R 4 n-butyl group, active ingredient 50% by mass

[0123] (Manufacturing Example 1) Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were charged into a nitrogen-purged autoclave reactor. After adjusting the temperature of the reactor contents to 20°C, n-butyllithium was added to initiate polymerization. Polymerization proceeded under adiabatic conditions, reaching a maximum temperature of 85°C. When the polymerization conversion rate reached 99%, 1,3-butadiene was added, and polymerization was continued for another 5 minutes. Then, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane was added as a modifier to carry out the reaction. After the polymerization reaction was complete, 2,6-di-tert-butyl-p-cresol was added. Subsequently, the solvent was removed by steam stripping, and the mixture was dried using a heated roller at 110°C to obtain SBR3.

[0124] (Manufacturing example 2) Two autoclaves, each with a 10-liter internal volume, an inlet at the bottom, and an outlet at the top, equipped with a stirrer and jacket, were connected in series as reactors. Butadiene, styrene, and cyclohexane were mixed in predetermined ratios. This mixed solution was passed through a dehydration column packed with activated alumina, and n-butyllithium was mixed in a static mixer to remove impurities. This mixture was then continuously supplied from the bottom of the first reactor. Subsequently, 2,2-bis(2-oxolanil)propane was continuously supplied from the bottom of the first reactor at predetermined rates as a polar substance, and n-butyllithium was continuously supplied as a polymerization initiator. The reactor temperature was maintained at 95°C. The polymer solution was continuously withdrawn from the top of the reactor and supplied to the second reactor. The temperature of the second reactor was maintained at 95°C, and a mixture of tetraglycidyl-1,3-bisaminomethylcyclohexane (monomer) and an oligomer component (hereinafter referred to as "modifier A") was continuously added at a predetermined rate as a 1000-fold dilution of cyclohexane to carry out the modification reaction. This polymer solution was continuously withdrawn from the reactor, an antioxidant was continuously added using a static mixer, and then the solvent was removed to obtain SBR4.

[0125] (Examples and Comparative Examples) According to the formulation shown in Table 1, all materials except the dibenzylamine compound, sulfur, and vulcanization accelerator were mixed for 5 minutes at 150°C using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd. to obtain a mixture. Next, the dibenzylamine compound, sulfur, and vulcanization accelerator were added to the mixture and mixed for 5 minutes at 80°C using an open roll to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was molded into a tread shape and bonded together with other tire components to form an unvulcanized tire. The tire was then press-vulcanized for 12 minutes at 150°C to produce a test tire (size: 175 / 60R18). The obtained test tire was evaluated as follows, and the results are shown in Table 1. In Table 1, the rubber content in the oil-applied rubber is listed in the "rubber" column, and the oil content in the oil-applied rubber is added to the "oil" column.

[0126] (Abrasion resistance) Each test tire was mounted on a vehicle, and the groove depth of the tread was measured after 50,000 km of driving. From the measured values, the amount of tread wear was calculated and expressed as an index with Comparative Example 1 set to 100. A higher index indicates less wear and better wear resistance.

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

[0128] [Table 1]

[0129] Table 1 shows that the examples exhibited superior abrasion resistance compared to the comparative examples. Furthermore, the example demonstrated superior overall performance (sum of all indices) in terms of wear resistance and wet grip performance compared to the comparative example.

Claims

1. It contains a rubber component including styrene-butadiene rubber, a filler containing carbon black and silica, a silane coupling agent, and a calcium compound. The content of styrene-butadiene rubber is 60% by mass or more in 100% by mass of the aforementioned rubber component. The content of the rubber component is less than or equal to the content of the filler. The silane coupling agent is a mercapto-silane coupling agent. A tire rubber composition in which the carbon black content is greater than or equal to the calcium element content of the calcium compound (excluding the rubber compositions shown in (1) to (8) below). (1) A tread rubber composition comprising 100 parts by mass of a rubber component containing 60 to 85% by mass of styrene-butadiene rubber and 15 to 40% by mass of butadiene rubber, 1 to 40 parts by mass of carbon black, and 50 to 150 parts by mass of silica, satisfying the following formulas (A) to (C). (Formula A) tan δ (0°C) ≦0.60 (Formula B) tan δ (15°C) ≦0.20 (Formula C) | tan δ (15°C) - tan δ (30°C) | ≦0.08 (tanδ(0°C), tanδ(15°C), and tanδ(30°C) represent the tanδ at a dynamic strain amplitude of 0.5% at 0°C, 15°C, and 30°C, respectively.) (2) A tread rubber composition comprising 100 parts by mass of a rubber component containing 60 to 80% by mass of styrene-butadiene rubber and 20 to 40% by mass of butadiene rubber, 1 to 40 parts by mass of carbon black, and 50 to 150 parts by mass of silica, wherein the tanδ at a dynamic strain amplitude of 0.5% at 0°C is 0.60 or less, and the peak temperature of tanδ is -17°C or less. (3) A rubber composition for tires comprising a rubber component having a styrene-butadiene rubber content of 60 to 90% by mass and a butadiene rubber content of 10 to 30% by mass, and silica in an amount of 80 parts by mass or more per 100 parts by mass of the rubber component, wherein the styrene-butadiene rubber is composed of multiple styrene-butadiene rubbers, and the difference in vinyl content between each of the multiple styrene-butadiene rubbers is 20% by mass or more. (4) A rubber composition comprising 45 parts by mass of styrene-butadiene rubber having a styrene content of 25% by mass and a vinyl content of 60% by mass, 40 parts by mass of styrene-butadiene rubber having a styrene content of 41% by mass and a vinyl content of 47% by mass, 15 parts by mass of butadiene rubber, 25 parts by mass of carbon black, 85 parts by mass of silica, 6 parts by mass of silane coupling agent, 20 parts by mass of oil, 20 parts by mass of styrene-based resin, 2 parts by mass of wax, 3.5 parts by mass of antioxidant, 1 part by mass of processing aid, 2 parts by mass of stearic acid, 2 parts by mass of zinc oxide, 1.5 parts by mass of sulfur, and 4.5 parts by mass of vulcanization accelerator. (5) A tire rubber composition comprising a rubber component (A) containing at least two types of rubber components, a compound (B) represented by the following formula (1), and a silane coupling agent (C) having a mercapto group, wherein the tire rubber composition is obtained by kneading a first rubber component from the rubber component (A) with the compound (B) to obtain a kneaded product, adding the silane coupling agent (C) and kneading, and then adding a second rubber component from the rubber component (A) to the resulting kneaded product and kneading, wherein the activation ability of the first rubber component for mercapto groups is smaller than that of the second rubber component. 【Chemistry 1】 (In the formula, R １ ~R ４ Each of these independently represents a linear or branched alkyl group having 1 to 18 carbon atoms, or a cycloalkyl group having 5 to 12 carbon atoms. The activation ability of the above-mentioned rubber components towards mercapto groups refers to the reactivity of the rubber components towards mercapto groups. The activation ability of each rubber component towards mercapto groups is evaluated using the surface roughness of a sheet fabric made with a silane coupling agent containing mercapto groups as an indicator. Surface roughness is measured using a surface roughness meter in accordance with the arithmetic mean roughness Ra of JIS B 0601. A specific amount of the silane coupling agent containing a specific mercapto group is added to 100 parts by mass of the rubber component to be evaluated and kneaded to produce a rubber sheet. Furthermore, a reference rubber component is determined from the obtained results, and the average surface roughness (Ra) obtained with that rubber component is set to 100 to determine the index (activation ability index) of each rubber component. The activation ability of each rubber component towards mercapto groups is then compared using this index. (6) A rubber composition comprising 80 parts by mass of styrene-butadiene rubber having a styrene content of 40% by mass and a vinyl content of 18 mol%, 20 parts by mass of butadiene rubber, 2 parts by mass of TP-50, 5 parts by mass of carbon black, 100 parts by mass of silica, 2 parts by mass of wax, 5 parts by mass of processing aid, 8 parts by mass of silane coupling agent, 41 parts by mass of oil, 10 parts by mass of styrene-based resin, 3 parts by mass of stearic acid, 1.5 parts by mass of sulfur, 4.5 parts by mass of vulcanization accelerator, 2 parts by mass of zinc oxide, and 4 parts by mass of anti-aging agent. (7) A rubber composition comprising 80 parts by mass of styrene-butadiene rubber having a styrene content of 25% by mass and a vinyl content of 44 mol%, 20 parts by mass of butadiene rubber, 2 parts by mass of TP-50, 5 parts by mass of carbon black, 100 parts by mass of silica, 2 parts by mass of wax, 5 parts by mass of processing aid, 8 parts by mass of silane coupling agent, 11 parts by mass of oil, 10 parts by mass of styrene-based resin, 3 parts by mass of stearic acid, 1.5 parts by mass of sulfur, 4.5 parts by mass of vulcanization accelerator, 2 parts by mass of zinc oxide, and 4 parts by mass of anti-aging agent. (8) A rubber composition comprising 60 parts by mass of styrene-butadiene rubber having a styrene content of 40% by mass and a vinyl content of 18 mol%, 40 parts by mass of butadiene rubber, 2 parts by mass of TP-50, 5 parts by mass of carbon black, 100 parts by mass of silica, 2 parts by mass of wax, 5 parts by mass of processing aid, 8 parts by mass of silane coupling agent, 33.5 parts by mass of oil, 10 parts by mass of styrene-based resin, 3 parts by mass of stearic acid, 1.5 parts by mass of sulfur, 4.5 parts by mass of vulcanization accelerator, 2 parts by mass of zinc oxide, and 4 parts by mass of anti-aging agent. In (6) to (8), TP-50 refers to Rhenogran® TP-50 manufactured by Rhein Chemie, and includes compounds in which R1 to R4 in the following formula (1) are n-butyl groups. 【Chemistry 2】

2. A rubber composition for tires according to claim 1, containing a resin.

3. It contains a rubber component including styrene-butadiene rubber, a filler containing carbon black and silica, a silane coupling agent, a calcium compound, a resin, and an oil. The content of styrene-butadiene rubber is 60% by mass or more in 100% by mass of the aforementioned rubber component. The content of the rubber component is less than or equal to the content of the filler. The silane coupling agent is a mercapto-silane coupling agent. The carbon black content is greater than or equal to the calcium compound content in terms of calcium element, The carbon black content / calcium element content of the calcium compound is 10 or more and 30 or less. The ratio of the resin content to the silica content is 0.05 or more and 0.25 or less. The oil content is greater than or equal to the total amount of styrene in the rubber component. A rubber composition for tires in which the total amount of vinyl in the rubber component / the total amount of styrene in the rubber component is 0.6 or more and 1.5 or less.

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

5. It contains butadiene rubber, The tire rubber composition according to any one of claims 1 to 4, wherein the cis content of the butadiene rubber is 90% by mass or less.

6. A tire rubber composition according to any one of claims 1 to 5, containing a dibenzylamine compound.

7. It contains isoprene-based rubber and resin, The tire rubber composition according to any one of claims 1 to 6, wherein the content of the isoprene-based rubber is less than or equal to the content of the resin.

8. A tire rubber composition according to any one of claims 1 to 7, comprising a cyclopentadiene resin.

9. The tire rubber composition according to any one of claims 1 to 8, wherein the average particle size of the silica is 16 nm or less.

10. A tire having a tread made of the rubber composition described in any one of claims 1 to 9.

Images