Rubber composition for tread and tire

Abstract

The present invention provides: a tread rubber composition capable of improving overall fuel efficiency, wet grip performance, and wear resistance; and a tire. This tread rubber composition includes a styrene-butadiene rubber, silica, and a mercapto-based silane coupling agent. The styrene-butadiene rubber content is at least 50% by mass in 100% by mass of rubber component. The silica content is 30–120 parts by mass relative to 100 parts by mass of rubber component. The tread rubber composition fulfills formulas (1) and (2). (E*(0.5%) in formula (1) indicates the complex elastic modulus under the conditions of an initial distortion of 10%, a dynamic distortion of 0.5%, and a temperature of 0°C. E*(5%) indicates the complex elastic modulus under the conditions of an initial distortion of 10%, a dynamic distortion of 5%, and a temperature of 0°C.)　tan δ(70°C) ≤ 0.18　(2) (tan δ(70°C) in formula (2) indicates the loss tangent under conditions of an initial distortion of 10%, a dynamic distortion of 1%, and a temperature of 70°C.)

Description

[Technical field]

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

[0002] From the viewpoints of safety and the environment, various performances are required for the tread, such as wet grip performance during driving on wet roads, wear resistance, fuel economy, etc. For example, a method of using modified polymers has been proposed as a technology for improving the balance between wet grip performance and fuel economy, but since modified polymers generally have high viscosity and poor processability, low molecular weight polymers tend to be used, resulting in a problem of poor wear resistance.

[0003] Although improvements using existing silane coupling agents have been proposed, there is still room for improvement in terms of the balance between fuel economy, wet grip performance, and abrasion resistance (see Patent Document 1, etc.). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-34992 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to solve the above problems and to provide a rubber composition for a tread and a tire which improve the overall performance of fuel economy, wet grip performance and abrasion resistance. [Means for solving the problem]

[0006] The present invention relates to a rubber composition for treads, which contains a styrene-butadiene rubber, silica, and a mercapto-silane coupling agent, the content of the styrene-butadiene rubber in 100% by mass of a rubber component is 50% by mass or more, the content of the silica in 100 parts by mass of the rubber component is 30 to 120 parts by mass, and satisfies the following formulas (1) and (2):

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number

[0007] The rubber composition preferably satisfies the following formula (1-1).

number

[0008] The rubber composition preferably satisfies the following formula (1-2).

number

[0009] The styrene-butadiene rubber preferably contains a styrene content of 5 to 50% by mass and a weight average molecular weight of 100,000 to 1,600,000.

[0010] The rubber composition preferably contains butadiene rubber.

[0011] The mercapto-based silane coupling agent preferably contains a silane coupling agent represented by the following formula (2-1). [ka] (In formula (2-1), R 101 -Cl, -Br, -OR 106 , -O(O=)CR 106 , -ON=CR 106 R 107 , -NR 106 R107 and-(OSiR 106 R 107 ) h (OSiR 106 R 107 R 108 ) a monovalent group (R 106 , R 107 and R 108 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; 102 is R 101 , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, R 103 is -[O(R 109 O) j ]-group(R 109 is an alkylene group having 1 to 18 carbon atoms, and j is an integer of 1 to 4. 104 is a divalent hydrocarbon group having 1 to 18 carbon atoms, R 105 represents a monovalent hydrocarbon group having 1 to 18 carbon atoms, and xa, ya, and za are numbers that satisfy the relationship: xa+ya+2za=3, 0≦xa≦3, 0≦ya≦2, 0≦za≦1.

[0012] The mercapto-based silane coupling agent preferably contains a bonding unit A represented by the following formula (2-2) and a bonding unit B represented by the following formula (2-3). [ka] [ka] (In formulas (2-2) and (2-3), xb is an integer of 0 or more, and yb is an integer of 1 or more. R 201 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. 202R 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. 201 and R 202 may form a ring structure.)

[0013] The mercapto-based silane coupling agent preferably contains a silane coupling agent represented by the following formula (2-4). [ka] (In the formula, R 6 ~R 8 represents a branched or unbranched alkyl group having 1 to 12 carbon atoms, a branched or unbranched alkoxy group having 1 to 12 carbon atoms, or -O-(R 111 -O) z -R 112 (z R 111 represents a branched or unbranched divalent hydrocarbon group having 1 to 30 carbon atoms. 111 may be the same or different. 112 represents a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms. z represents an integer of 1 to 30. R 6 ~R 8 may be the same or different. 9 represents a branched or unbranched alkylene group having 1 to 6 carbon atoms.

[0014] The rubber composition preferably contains carbon black.

[0015] The rubber composition is preferably obtained by a manufacturing method including a step (I) of kneading silica and a mercapto-based silane coupling agent, and a step (II) of maintaining the kneaded mixture obtained in the step (I) at 130°C or higher.

[0016] The present invention also relates to a tire having a tread made of said rubber composition. Effect of the Invention

[0017] According to the present invention, the rubber composition for treads contains styrene-butadiene rubber, silica, and a mercapto-silane coupling agent, the content of the styrene-butadiene rubber in 100% by mass of the rubber component is 50% by mass or more, the content of the silica in 100 parts by mass of the rubber component is 30 to 120 parts by mass, and satisfies the formulas (1) and (2), so that the overall performance of fuel economy, wet grip performance, and abrasion resistance can be improved. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] [Rubber composition for tread] The rubber composition for treads of the present invention contains a styrene-butadiene rubber, silica, and a mercapto-silane coupling agent in a predetermined ratio and satisfies the above formulas (1) and (2), thereby significantly improving the overall performance of fuel economy, wet grip performance, and abrasion resistance.

[0019] The mechanism by which the above-mentioned effects are obtained is not entirely clear, but is presumed to be as follows. In the case where a mercapto-based silane coupling agent is used as a silane coupling agent in a silica compound containing styrene-butadiene rubber and the formulas (1) and (2) are satisfied, the mercapto-based silane coupling agent is used to provide a good processing, improving the dispersibility of the silica and the reaction rate of the silica and the silane coupling agent, and providing excellent fuel economy without impairing wet grip performance and abrasion resistance. Furthermore, by satisfying formula (2), good fuel economy is obtained. Therefore, it is presumed that the overall performance of fuel economy, wet grip performance, and abrasion resistance is significantly improved.

[0020] In this way, the present invention solves the problem (objective) of improving the overall performance of fuel economy, wet grip performance, and abrasion resistance by configuring a rubber composition for treads that satisfies formulas (1) and (2) in a formulation containing styrene-butadiene rubber, silica, and a mercapto-based silane coupling agent in a predetermined formulation. In other words, the parameters of formulas (1) and (2) do not define the problem (objective), and the problem of the present application is to improve the overall performance of fuel economy, wet grip performance, and abrasion resistance, and a configuration that satisfies the parameters is used as a means to achieve this.

[0021] The rubber composition (rubber composition after vulcanization) satisfies the following formula (1).

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[0022] From the viewpoints of fuel economy and abrasion resistance, the value (80) of formula (1) is preferably 75 or less, more preferably 71 or less, even more preferably 70 or less, particularly preferably 67 or less, and most preferably 66 or less. The upper limit may be 65 or less, 63 or less, 60 or less, 56 or less, 55 or less, 53 or less, 50 or less, 48 ​​or less, 47 or less, 46 or less, or 40 or less. The lower limit is not particularly limited, but from the viewpoints of wet grip performance and abrasion resistance, it is preferably 10 or more, more preferably 15 or more, and even more preferably 20 or more.

[0023] From the viewpoint of overall performance such as fuel economy, wet grip performance, and abrasion resistance, the rubber composition (rubber composition after vulcanization) preferably satisfies the following formula (1-1).

number

[0024] From the viewpoint of overall performance such as fuel economy, wet grip performance, and abrasion resistance, the rubber composition (rubber composition after vulcanization) preferably satisfies the following formula (1-2).

number

[0025] The rubber composition (rubber composition after vulcanization) satisfies the following formula (2).

number

[0026] The upper limit of tan δ(70°C) is preferably 0.17 or less, more preferably 0.16 or less, even more preferably 0.15 or less, particularly preferably 0.14 or less, and most preferably 0.13 or less, from the viewpoint of low fuel consumption. The upper limit may be 0.12 or less. The lower limit is not particularly limited, but is more preferably 0.05 or more, even more preferably 0.08 or more, from the viewpoint of wet grip performance.

[0027] Here, E*(0.5%), E*(5%) and tan δ(70° C.) can be appropriately adjusted by changing the types and amounts of the rubber, filler and silane coupling agent. For example, E*(0.5%) and E*(5%) can be increased by using styrene-butadiene rubber as the rubber component or increasing the amount of the rubber, by using silica as a filler or increasing the amount of the rubber, by reducing the amount of the plasticizer, or by reducing the amount of the silane coupling agent. (E*(0.5%)-E*(5%)) can be reduced by using a modified rubber as the rubber component or increasing the amount of the modified rubber, by using silica as a filler or reducing the amount of the modified rubber, or by using a mercapto silane coupling agent as the silane coupling agent or increasing the amount of the mercapto silane coupling agent. Tan δ (70° C.) can be reduced by using a modified rubber as the rubber component, by using silica as the filler, by using a mercapto-based silane coupling agent as the silane coupling agent, or by increasing the amount of the agent.

[0028] Specifically, examples of the method for satisfying formula (1) include (a) a method of using a predetermined amount of styrene-butadiene rubber as a rubber component, (b) a method of using a predetermined amount of silica as a filler, and (c) a method of using a predetermined amount of a mercapto-based silane coupling agent, either alone or in combination as appropriate.

[0029] Methods for satisfying formula (2) include (a) a method of using a mercapto-based silane coupling agent as a silane coupling agent, (b) a method of using a modified rubber as a rubber component, and (c) a method of using a predetermined amount of silica as a filler, either alone or in appropriate combination.

[0030] The complex modulus E*(0.5%) of the rubber composition (rubber composition after vulcanization) under conditions of an initial strain of 10%, a dynamic strain of 0.5%, and a temperature of 0°C, the complex modulus E*(5%) under conditions of an initial strain of 10%, a dynamic strain of 5%, and a temperature of 0°C, and the loss tangent tan δ(70°C) under conditions of an initial strain of 10%, a dynamic strain of 1%, and a temperature of 70°C can each be measured by the method described later in the Examples.

[0031] (Rubber component) The rubber composition includes styrene-butadiene rubber (SBR). The content of SBR in 100% by mass of the rubber component is 50% by mass or more, preferably 60% by mass or more, more preferably 65% ​​by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more. By making it equal to or more than the lower limit, good abrasion resistance and wet grip performance tend to be obtained. The upper limit is not particularly limited, but from the viewpoint of obtaining good fuel economy, it is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less.

[0032] The SBR is not particularly limited, and for example, emulsion polymerized styrene butadiene rubber (E-SBR), solution polymerized styrene butadiene rubber (S-SBR), etc. can be used. These may be used alone or in combination of two or more kinds.

[0033] The styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and particularly preferably 21% by mass or more. The styrene content is preferably 50% by mass or less, more preferably 47% by mass or less, and even more preferably 45% by mass or less. When it is within the above range, it tends to provide good overall performance such as fuel economy, wet grip performance, and abrasion resistance. In this specification, the styrene content of SBR is H 1 - Calculated by NMR measurement.

[0034] The Mw of the SBR is preferably 100,000 or more, more preferably 200,000 or more, and even more preferably 240,000 or more. The Mw is preferably 1.6 million or less, more preferably 1.5 million or less, and even more preferably 1.4 million or less. Within the above range, there is a tendency for good overall performance in terms of fuel economy, wet grip performance, and abrasion resistance to be obtained. In this specification, the Mw of SBR can be determined in terms of 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 SUPERMALTPORE HZ-M, manufactured by Tosoh Corporation).

[0035] The SBR may be unmodified SBR or modified SBR, which may be used alone or in combination of two or more kinds. The modified SBR may be any SBR having a functional group that interacts with a filler such as silica, and examples thereof include terminal-modified SBR (terminal-modified SBR having a functional group at the terminal) in which at least one terminal of SBR has been modified with a compound having a functional group (modifier), main-chain-modified SBR having a functional group in the main chain, main-chain-terminal-modified SBR having functional groups in the main chain and at least one terminal (for example, main-chain-terminal-modified SBR having a functional group in the main chain and at least one terminal modified with a modifier), and terminal-modified SBR modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and having a hydroxyl group or epoxy group introduced therein. These may be used alone or in combination of two or more types.

[0036] 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.

[0037] As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., and the like can be used.

[0038] Examples of rubber components that can be used other than SBR include diene rubbers such as isoprene rubber, butadiene rubber (BR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR), and styrene-isoprene-butadiene copolymer rubber (SIBR). These may be used alone or in combination of two or more. Among these, BR and isoprene rubber are preferred, and BR is more preferred.

[0039] The BR is not particularly limited, and for example, BR having a high cis content, BR containing syndiotactic polybutadiene crystals, etc. may be used. These may be used alone or in combination of two or more.

[0040] The BR may be a non-modified BR or a modified BR, which may be used alone or in combination of two or more kinds. The modified BR may be a modified BR having a functional group introduced therein similar to the modified SBR described above.

[0041] As the BR, for example, products from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Zeon Corporation, etc. can be used.

[0042] 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, and even more preferably 15% by mass or more. The BR content is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and particularly preferably 20% by mass or less. By keeping the BR content within the above range, good overall performance in terms of fuel economy, wet grip performance, and abrasion resistance tends to be obtained.

[0043] Examples of isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, modified IR, etc. As NR, for example, SIR20, RSS♯3, TSR20, etc., which are common in the tire industry, can be used. As IR, there is no particular limitation, and for example, IR2200, etc., which are common in the tire industry can be used. As modified NR, deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc., as modified NR, epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc., as modified IR, epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, etc., can be used. These may be used alone or in combination of two or more.

[0044] When an isoprene-based rubber is compounded, the content may be appropriately selected, for example, from 5 to 50% by mass in 100% by mass of the rubber component.

[0045] (silica) Examples of silica include dry silica (anhydrous silica) and wet silica (hydrated silica). Among them, wet silica is preferred because it has a large number of silanol groups. These may be used alone or in combination of two or more.

[0046] The content of silica is 30 parts by mass or more, preferably 40 parts by mass or more, more preferably 50 parts by mass or more, even more preferably 60 parts by mass or more, and particularly preferably 75 parts by mass or more, based on 100 parts by mass of the rubber component. By making it equal to or more than the lower limit, good abrasion resistance and wet grip performance tend to be obtained. The upper limit of the content is 120 parts by mass or less, preferably 110 parts by mass or less, more preferably 105 parts by mass or less, and even more preferably 100 parts by mass or less. By making it equal to or less than the upper limit, good fuel economy tends to be obtained.

[0047] The nitrogen adsorption specific surface area (N2SA) of the silica is preferably 80 m 2 / g or more, more preferably 120m 2 / g or more, more preferably 150m 2 / g or more, particularly preferably 170m 2 By making it equal to or higher than the lower limit, good abrasion resistance and wet grip performance tend to be obtained. In addition, the N2SA of silica is preferably 250m 2 / g or less, more preferably 220m 2 / g or less, more preferably 200m 2 By keeping the content below the upper limit, good dispersibility and low fuel consumption tend to be obtained. The N2SA of silica is a value measured by the BET method in accordance with ASTM D3037-93.

[0048] As the silica, for example, products manufactured by Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Corporation, etc. can be used.

[0049] (Mercapto-based silane coupling agent) The rubber composition uses a mercapto-based silane coupling agent as a silane coupling agent, which allows for suitable processing, improves the dispersibility of silica, and improves the reaction rate between silica and the silane coupling agent, thereby providing excellent fuel economy without impairing wet grip performance or wear resistance.

[0050] The content of the mercapto-based silane coupling agent is preferably 2 parts by mass or more, more preferably 4 parts by mass or more, even more preferably 6 parts by mass or more, and particularly preferably 8 parts by mass or more, based on 100 parts by mass of silica. If it is above the lower limit, it tends to obtain good overall performance such as low fuel consumption, wet grip performance, and abrasion resistance. In addition, the content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. If it is below the upper limit, it tends to obtain effects that correspond to the amount blended.

[0051] Examples of the mercapto-based silane coupling agent include a silane coupling agent having a mercapto group, a silane coupling agent in which the mercapto group is protected, etc. These may be used alone or in combination of two or more kinds.

[0052] Suitable mercapto-based silane coupling agents include (i) a silane coupling agent represented by the following formula (2-1), and (ii) a silane coupling agent containing a bond unit A represented by the following formula (2-2) and a bond unit B represented by the following formula (2-3). [ka] (In formula (2-1), R 101 -Cl, -Br, -OR 106 , -O(O=)CR 106 , -ON=CR 106 R 107 , -NR 106 R 107 and-(OSiR 106 R 107 ) h (OSiR 106 R 107 R 108 ) a monovalent group (R 106 , R 107 and R 108 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; 102 is R 101 , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, R 103is -[O(R 109 O) j ]-group(R 109 is an alkylene group having 1 to 18 carbon atoms, and j is an integer of 1 to 4. 104 is a divalent hydrocarbon group having 1 to 18 carbon atoms, R 105 represents a monovalent hydrocarbon group having 1 to 18 carbon atoms, and xa, ya, and za are numbers that satisfy the relationship: xa+ya+2za=3, 0≦xa≦3, 0≦ya≦2, 0≦za≦1. [ka] [ka] (In formulas (2-2) and (2-3), xb is an integer of 0 or more, and yb is an integer of 1 or more. R 201 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. 202 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. 201 and R 202 may form a ring structure.)

[0053] R in the above formula (2-1) 102 , R 105 , R 106 , R 107 and R 108 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 the above formula (2-1) 109 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.

[0054] Specific examples of the silane coupling agent represented by the above formula (2-1) 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. Among these, 3-octanoylthiopropyltriethoxysilane (NXT manufactured by Momentive Corp.) is particularly preferred. The above silane coupling agents may be used alone or in combination of two or more kinds.

[0055] Silane coupling agents containing the bond unit A represented by formula (2-2) and the bond unit B represented by formula (2-3) have a suppressed increase in viscosity during processing compared to polysulfide silanes such as bis-(3-triethoxysilylpropyl)tetrasulfide. This is thought to be because the sulfide portion of the bond unit A is a CSC bond, which is more thermally stable than tetrasulfides and disulfides, resulting in less increase in Mooney viscosity.

[0056] In addition, compared to mercaptosilanes such as 3-mercaptopropyltrimethoxysilane, the reduction in scorch time is suppressed. This is because the bond unit A has a mercaptosilane structure, but the -CH of the bond unit A 15 This is thought to be because the -SH group of the bonding unit B is covered by this moiety, making it less likely to react with the polymer and less likely to cause scorch.

[0057] In the silane coupling agent of the above structure, 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.In addition, 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, from the viewpoint of reactivity with silica.In addition, 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 (2-2) and (2-3) representing the bond units A and B.

[0058] R 201 Examples of the halogen include chlorine, bromine, and fluorine.

[0059] R 201 Examples of the branched or unbranched alkyl group having 1 to 30 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an iso-butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an octyl group, a nonyl group, a decyl group, etc. The number of carbon atoms of the alkyl group is preferably 1 to 12.

[0060] R 201Examples of the branched or unbranched alkenyl group having 2 to 30 carbon atoms include a vinyl group, a 1-propenyl group, a 2-propenyl group, a 1-butenyl group, a 2-butenyl group, a 1-pentenyl group, a 2-pentenyl group, a 1-hexenyl group, a 2-hexenyl group, a 1-octenyl group, etc. The number of carbon atoms of the alkenyl group is preferably 2 to 12.

[0061] R 201 Examples of the branched or unbranched alkynyl group having 2 to 30 carbon atoms include an ethynyl group, a propynyl group, a butynyl group, a pentynyl group, a hexynyl group, a heptynyl group, an octynyl group, a nonynyl group, a decynyl group, an undecynyl group, a dodecynyl group, etc. The number of carbon atoms of the alkynyl group is preferably 2 to 12.

[0062] R 202 Examples of the branched or unbranched alkylene group having 1 to 30 carbon atoms include an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, an undecylene group, a dodecylene group, a tridecylene group, a tetradecylene group, a pentadecylene group, a hexadecylene group, a heptadecylene group, an octadecylene group, etc. The number of carbon atoms of the alkylene group is preferably 1 to 12.

[0063] R 202 Examples of the branched or unbranched alkenylene group having 2 to 30 carbon atoms include a vinylene group, a 1-propenylene group, a 2-propenylene group, a 1-butenylene group, a 2-butenylene group, a 1-pentenylene group, a 2-pentenylene group, a 1-hexenylene group, a 2-hexenylene group, a 1-octenylene group, etc. The number of carbon atoms in the alkenylene group is preferably 2 to 12.

[0064] R 202 Examples of the branched or unbranched alkynylene group having 2 to 30 carbon atoms include an ethynylene group, a propynylene group, a butynylene group, a pentynylene group, a hexynylene group, a heptynylene group, an octynylene group, a nonynylene group, a decynylene group, an undecynylene group, a dodecynylene group, etc. The number of carbon atoms of the alkynylene group is preferably 2 to 12.

[0065] In a silane coupling agent containing a bonding unit A represented by formula (2-2) and a bonding unit B represented by formula (2-3), the total number of repetitions (xb+yb) of the bonding unit A and the bonding unit B is preferably in the range of 3 to 300. When it is in this range, the mercaptosilane of the bonding unit B is preferably -CH of the bonding unit A. 15 Since the rubber component is covered with the silica, the scorch time can be prevented from becoming shorter and good reactivity with the silica and rubber components can be ensured.

[0066] As the silane coupling agent containing the bond unit A represented by formula (2-2) and the bond unit B represented by formula (2-3), for example, NXT-Z30, NXT-Z45, NXT-Z60, etc. manufactured by Momentive Corp. can be used. These may be used alone or in combination of two or more kinds.

[0067] As the mercapto-based silane coupling agent, (iii) a silane coupling agent represented by the following formula (2-4) can also be suitably used.

[0068] [ka] (In the formula, R 6 ~R 8 represents a branched or unbranched alkyl group having 1 to 12 carbon atoms, a branched or unbranched alkoxy group having 1 to 12 carbon atoms, or -O-(R 111 -O) z -R 112 (z R 111 represents a branched or unbranched divalent hydrocarbon group having 1 to 30 carbon atoms. 111 may be the same or different. 112 represents a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms. z represents an integer of 1 to 30. R 6 ~R 8may be the same or different. 9 represents a branched or unbranched alkylene group having 1 to 6 carbon atoms.

[0069] R 6 ~R 8 represents a branched or unbranched alkyl group having 1 to 12 carbon atoms, a branched or unbranched alkoxy group having 1 to 12 carbon atoms, or -O-(R 111 -O) z -R 112 R represents a group represented by the formula: 6 ~R 8 has at least one -O-(R 111 -O) z -R 112 Preferably, two of the groups are represented by -O-(R 111 -O) z -R 112 and one of them is a branched or unbranched alkoxy group having 1 to 12 carbon atoms.

[0070] R 6 ~R 8 Examples of the branched or unbranched alkyl group having 1 to 12 carbon atoms (preferably 1 to 5 carbon atoms) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an iso-butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an octyl group, and a nonyl group.

[0071] R 6 ~R 8 Examples of the branched or unbranched alkoxy group having 1 to 12 carbon atoms (preferably 1 to 5 carbon atoms) include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an iso-butoxy group, a sec-butoxy group, a tert-butoxy group, a pentyloxy group, a hexyloxy group, a heptyloxy group, a 2-ethylhexyloxy group, an octyloxy group, and a nonyloxy group.

[0072] R 6 ~R 8 -O-(R111 -O) z -R 112 In R 111 represents a branched or unbranched divalent hydrocarbon group having 1 to 30 carbon atoms (preferably 1 to 15 carbon atoms, more preferably 1 to 3 carbon atoms). Examples of the hydrocarbon group include a branched or unbranched alkylene group having 1 to 30 carbon atoms, a branched or unbranched alkenylene group having 2 to 30 carbon atoms, a branched or unbranched alkynylene group having 2 to 30 carbon atoms, and an arylene group having 6 to 30 carbon atoms. Among these, a branched or unbranched alkylene group having 1 to 30 carbon atoms is preferred.

[0073] R 111 Examples of the branched or unbranched alkylene group having 1 to 30 carbon atoms (preferably 1 to 15 carbon atoms, more preferably 1 to 3 carbon atoms) include a methylene group, ethylene group, propylene group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, undecylene group, dodecylene group, tridecylene group, tetradecylene group, pentadecylene group, hexadecylene group, heptadecylene group, and octadecylene group.

[0074] R 111 Examples of the branched or unbranched alkenylene group having 2 to 30 carbon atoms (preferably 2 to 15 carbon atoms, more preferably 2 to 3 carbon atoms) include a vinylene group, a 1-propenylene group, a 2-propenylene group, a 1-butenylene group, a 2-butenylene group, a 1-pentenylene group, a 2-pentenylene group, a 1-hexenylene group, a 2-hexenylene group, and a 1-octenylene group.

[0075] R 111 Examples of the branched or unbranched alkynylene group having 2 to 30 carbon atoms (preferably having 2 to 15 carbon atoms, more preferably having 2 to 3 carbon atoms) include an ethynylene group, a propynylene group, a butynylene group, a pentynylene group, a hexynylene group, a heptynylene group, an octynylene group, a nonynylene group, a decynylene group, an undecynylene group, and a dodecynylene group.

[0076] R 111 Examples of the arylene group having 6 to 30 carbon atoms (preferably 6 to 15 carbon atoms) include a phenylene group, a tolylene group, a xylylene group, and a naphthylene group.

[0077] z represents an integer of 1 to 30 (preferably 2 to 20, more preferably 3 to 7, and further preferably 5 to 6).

[0078] R 112 represents a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms. Among these, a branched or unbranched alkyl group having 1 to 30 carbon atoms is preferred.

[0079] R 112 Examples of the branched or unbranched alkyl group having 1 to 30 carbon atoms (preferably 3 to 25 carbon atoms, more preferably 10 to 15 carbon atoms) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an iso-butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, and an octadecyl group.

[0080] R 112 Examples of the branched or unbranched alkenyl group having 2 to 30 carbon atoms (preferably 3 to 25 carbon atoms, more preferably 10 to 15 carbon atoms) include a vinyl group, a 1-propenyl group, a 2-propenyl group, a 1-butenyl group, a 2-butenyl group, a 1-pentenyl group, a 2-pentenyl group, a 1-hexenyl group, a 2-hexenyl group, a 1-octenyl group, a decenyl group, an undecenyl group, a dodecenyl group, a tridecenyl group, a tetradecenyl group, a pentadecenyl group, and an octadecenyl group.

[0081] R 112Examples of the aryl group having 6 to 30 carbon atoms (preferably 10 to 20 carbon atoms) include a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and a biphenyl group.

[0082] R 112 Examples of the aralkyl group having 7 to 30 carbon atoms (preferably 10 to 20 carbon atoms) include a benzyl group and a phenethyl group.

[0083] -O-(R 111 -O) z -R 112 Specific examples of the group represented by the formula are, for example, -O-(C2H4-O)5-C 11 H 23 , -O-(C2H4-O)5-C 12 H 25 , -O-(C2H4-O)5-C 13 H 27 , -O-(C2H4-O)5-C 14 H 29 , -O-(C2H4-O)5-C 15 H 31 , -O-(C2H4-O)3-C 13 H 27 , -O-(C2H4-O)4-C 13 H 27 , -O-(C2H4-O)6-C 13 H 27 , -O-(C2H4-O)7-C 13 H 27 Among them, -O-(C2H4-O)5-C 11 H 23 , -O-(C2H4-O)5-C 13 H 27 , -O-(C2H4-O)5-C 15 H 31 , -O-(C2H4-O)6-C 13 H 27 is preferred.

[0084] R 9 Examples of the branched or unbranched alkylene group having 1 to 6 carbon atoms (preferably 1 to 5 carbon atoms) include R 111Examples of the branched or unbranched alkylene group having 1 to 30 carbon atoms include the same groups as those mentioned above.

[0085] Examples of the compound represented by the above formula (2-4) include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and the compound represented by the following formula (Si363 manufactured by EVONIK-DEGUSSA), and the compound represented by the following formula can be preferably used. These may be used alone or in combination of two or more kinds. [ka]

[0086] Commercially available mercapto-based silane coupling agents include those manufactured by Degussa, Momentive, Shin-Etsu Silicones, Tokyo Chemical Industry, Azumax, and Dow Corning Toray.

[0087] (Other silane coupling agents) The rubber composition may further contain a silane coupling agent other than the mercapto-based silane coupling agent. By using the other silane coupling agent in combination, the effect of using the mercapto-based silane coupling agent can be suitably obtained while imparting good processability.

[0088] When a mercapto-based silane coupling agent and another silane coupling agent are used in combination, the mixing ratio (content of mercapto-based silane coupling agent / content of other silane coupling agent (mass ratio)) is preferably 5 / 95 to 50 / 50, more preferably 5 / 95 to 35 / 65, and even more preferably 5 / 95 to 25 / 75, from the viewpoint of overall performance such as fuel economy, wet grip performance, and abrasion resistance.

[0089] The content of the silane coupling agent (the total content of the mercapto-based silane coupling agent and other silane coupling agents) is preferably 2 parts by mass or more, more preferably 4 parts by mass or more, even more preferably 6 parts by mass or more, and particularly preferably 8 parts by mass or more, relative to 100 parts by mass of silica. If it is above the lower limit, there is a tendency for good overall performance in terms of fuel economy, wet grip performance, and abrasion resistance to be obtained. In addition, the content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. If it is below the upper limit, there is a tendency for effects commensurate with the blending amount to be obtained.

[0090] The other 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, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide. sulfide-based silane coupling agents such as vinyl triethoxysilane and vinyl trimethoxysilane; amino-based silane coupling agents such as 3-aminopropyl triethoxysilane and 3-aminopropyl trimethoxysilane; glycidoxy-based silane coupling agents such as γ-glycidoxypropyl triethoxysilane and γ-glycidoxypropyl trimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyl trimethoxysilane and 3-nitropropyl triethoxysilane; chloro-based silane coupling agents such as 3-chloropropyl trimethoxysilane and 3-chloropropyl triethoxysilane; polymer-type alkoxy oligomer type and multifunctional group type silane coupling agents;

[0091] Among other silane coupling agents, polymer-type alkoxy oligomer type and multifunctional group type silane coupling agents are preferred from the viewpoint of overall performance such as fuel economy, wet grip performance, and abrasion resistance. Specifically, methoxy / ethoxy group-containing oligomer type silane coupling agents having epoxy groups (KR-517 manufactured by Shin-Etsu Silicone Co., Ltd., etc.), methoxy group-containing oligomer type silane coupling agents having epoxy groups (KR-516 manufactured by Shin-Etsu Silicone Co., Ltd., etc.), methoxy / ethoxy group-containing oligomer type silane coupling agents having mercapto groups (X-41-1805 manufactured by Shin-Etsu Silicone Co., Ltd., etc.), methoxy group-containing oligomer type silane coupling agents having mercapto groups (X-41-1810 manufactured by Shin-Etsu Silicone Co., Ltd., etc.), ethoxy group-containing multifunctional group type silane coupling agents having amino groups, etc. Examples of suitable silane coupling agents include coupling agents (such as X-12-972F manufactured by Shin-Etsu Silicones), ethoxy group-containing multifunctional silane coupling agents having epoxy groups (such as X-12-981S manufactured by Shin-Etsu Silicones), ethoxy group-containing multifunctional silane coupling agents having epoxy groups (such as X-12-984S manufactured by Shin-Etsu Silicones), methoxy group-containing multifunctional silane coupling agents having mercapto groups (such as X-12-1154 manufactured by Shin-Etsu Silicones), and methoxy group-containing multifunctional silane coupling agents having isocyanate groups (such as X-12-1252 manufactured by Shin-Etsu Silicones).

[0092] (Carbon Black) The rubber composition preferably contains carbon black from the viewpoint of abrasion resistance, wet grip performance, etc. Examples of carbon black include, but are not limited to, GPF, FEF, HAF, ISAF, SAF, etc. 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., etc.

[0093] The carbon black content is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, based on 100 parts by mass of the rubber component. By making it equal to or more than the lower limit, there is a tendency to obtain an improved effect on abrasion resistance, wet grip performance, and the like. In addition, the carbon black content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. By making it equal to or less than the upper limit, there is a tendency to obtain good fuel economy, and the like.

[0094] The nitrogen adsorption specific surface area (N2SA) of carbon black is 65m 2 / g or more is preferable, and 90m 2 / g or more is more preferable, and 105m 2 / g or more is more preferable, and 110m 2 / g or more is particularly preferable, and 250m 2 / g or less is preferable, and 150m 2 / g or less is more preferable, and 130m 2 By keeping it within the above range, there is a tendency that good overall performance in terms of fuel economy, wet grip performance, and abrasion resistance can be obtained. The nitrogen adsorption specific surface area of ​​carbon black is determined in accordance with JIS K 6217-2:2001.

[0095] The dibutyl phthalate oil absorption (DBP) of the carbon black is preferably 50 ml / 100 g or more, more preferably 90 ml / 100 g or more, even more preferably 105 ml / 100 g or more, particularly preferably 110 ml / 100 g or more, and is preferably 250 ml / 100 g or less, more preferably 150 ml / 100 g or less, and even more preferably 135 ml / 100 g or less. By keeping it within the above range, there is a tendency that good overall performance such as low fuel consumption, wet grip performance, and abrasion resistance can be obtained. The DBP oil absorption of carbon black is measured in accordance with JIS K6217-4:2001.

[0096] (Liquid plasticizer) From the viewpoint of various physical properties of a tire, the rubber composition preferably contains a liquid plasticizer. The liquid plasticizer is not particularly limited as long as it is a plasticizer that is in a liquid state at room temperature (25°C), and examples thereof include oil, liquid diene polymer, liquid resin, etc. Among them, oil is preferred from the viewpoint of processability, etc. These may be used alone or in combination of two or more kinds.

[0097] The content (total amount) of the liquid plasticizer is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, even more preferably 7 parts by mass or more, particularly preferably 10 parts by mass or more, and most preferably 15 parts by mass or more, based on 100 parts by mass of the rubber component. By making the content equal to or more than the lower limit, good processability tends to be obtained. Moreover, the content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less. By making the content equal to or less than the upper limit, good abrasion resistance tends to be obtained. The content of the liquid plasticizer also includes the amount of oil (extending oil) contained in the rubber (oil-extended rubber).

[0098] As the oil, in addition to the above-mentioned extending oil, conventionally known oils such as process oils such as paraffin-based process oils, aromatic process oils, naphthene-based process oils, low PCA (polycyclic aromatic) process oils such as TDAE and MES, vegetable oils and fats, and mixtures thereof can be used. Examples of vegetable oils and fats 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. Among them, process oils are preferred. Examples of commercially available oils that can be used include products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H&R Co., Ltd., Toyokuni Oil Mills Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., and the like.

[0099] The liquid diene polymer has a weight average molecular weight (Mw) of 1.0×10 based on polystyrene standards, as measured by gel permeation chromatography (GPC). 3 ~2.0×105 Preferably, it is 3.0×10 3 ~1.5×10 4 It is more preferable that: In this specification, the Mw of the liquid diene polymer is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0100] Examples of liquid diene polymers include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), and liquid styrene-isoprene copolymer (liquid SIR).

[0101] The liquid resin is not particularly limited, but examples thereof include liquid aromatic vinyl polymers, coumarone-indene resins, indene resins, terpene resins, rosin resins, and hydrogenated products thereof.

[0102] Examples of the liquid aromatic vinyl polymer include resins obtained by polymerizing α-methylstyrene and / or styrene, etc. Specific examples include liquid resins such as homopolymers of styrene, homopolymers of α-methylstyrene, and copolymers of α-methylstyrene and styrene.

[0103] The liquid coumarone-indene resin is a resin containing coumarone and indene as main monomer components constituting the resin skeleton (main chain). Here, examples of monomer components that may be contained in the skeleton other than coumarone and indene include liquid resins such as styrene, α-methylstyrene, methylindene, and vinyltoluene.

[0104] The liquid indene resin is a liquid resin that contains indene as the main monomer component that constitutes the resin skeleton (main chain).

[0105] Liquid terpene resins are resins obtained by polymerizing terpene compounds such as α-pinene, β-pinene, camphor, and dipentene, and liquid terpene resins (terpene phenol resins, aromatic modified terpene resins, etc.) typified by terpene phenol, which is a resin obtained using terpene compounds and phenolic compounds as raw materials.

[0106] Examples of liquid rosin resins include liquid rosin-based resins such as natural rosin, polymerized rosin, modified rosin, ester compounds thereof, and hydrogenated products thereof.

[0107] As commercially available liquid diene polymers and liquid resins, for example, products from CRAY VALLEY, KURARAY CO., LTD., etc. can be used.

[0108] (Resin) The rubber composition may contain a resin (solid resin: a resin that is in a solid state at room temperature (25° C.)).

[0109] Examples of resins (solid resins) include aromatic vinyl polymers, coumarone-indene resins, indene resins, rosin resins, terpene resins, and acrylic resins. Commercially available products include those from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Co., Ltd., Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., JXTG Energy Corporation, Arakawa Chemical Industries Co., Ltd., Taoka Chemical Co., Ltd., and Toagosei Co., Ltd. These may be used alone or in combination of two or more. Among these, aromatic vinyl polymers, coumarone-indene resins, terpene resins, and rosin resins are preferred, and coumarone-indene resins are more preferred.

[0110] The content of the resin (solid resin) is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, based on 100 parts by mass of the rubber component. The content is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less. By keeping the content within the above range, good abrasion resistance and the like tend to be obtained.

[0111] The softening point of the resin (solid resin) is preferably 30° C. or higher, more preferably 60° C. or higher, and even more preferably 80° C. or higher. The softening point is preferably 200° C. or lower, and more preferably 160° C. or lower. By keeping the softening point within the above range, good abrasion resistance and the like tend to be obtained. The softening point of the resin is the temperature at which the ball drops when the softening point specified in JIS K 6220-1:2001 is measured using a ring and ball softening point tester.

[0112] (Other ingredients) 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. These may be used alone or in combination of two or more. Among them, petroleum waxes are preferred, and paraffin wax is more preferred.

[0113] As the wax, for example, products available from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., etc. can be used.

[0114] When the wax is contained, the amount thereof is preferably 0.3 part by mass or more, more preferably 0.5 part by mass or more, and preferably 20 parts by mass or less, more preferably 10 parts by mass or less, based on 100 parts by mass of the rubber component.

[0115] 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. Among them, p-phenylenediamine antioxidants and quinoline antioxidants are preferred.

[0116] In the case where an antioxidant is contained, the content thereof is preferably 0.5 part by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the rubber component.

[0117] The rubber composition may contain stearic acid. As the stearic acid, any known stearic acid can be used, for example, products available from NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., and the like.

[0118] When stearic acid is contained, the amount thereof is preferably 0.5 part by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, per 100 parts by mass of the rubber component.

[0119] The rubber composition may contain zinc oxide. As the zinc oxide, any known zinc oxide can be used, for example, products available from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., and the like.

[0120] When zinc oxide is contained, the content thereof is preferably 0.5 part by mass or more, more preferably 1 part by mass or more, and preferably 10 parts by mass or less, more preferably 5 parts by mass or less, based on 100 parts by mass of the rubber component.

[0121] The rubber composition preferably contains 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. These may be used alone or in combination of two or more kinds.

[0122] As sulfur, for example, products from Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanritsu Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

[0123] In the case where sulfur is contained, the amount thereof is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and is preferably 10.0 parts by mass or less, more preferably 5.0 parts by mass or less, and even more preferably 3.0 parts by mass or less, based on 100 parts by mass of the rubber component.

[0124] The rubber composition preferably contains a vulcanization accelerator. Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenyl guanidine, di-orthotolyl guanidine, and orthotolyl biguanidine. These may be used alone or in combination of two or more. Among them, sulfenamide vulcanization accelerators and guanidine vulcanization accelerators are preferred.

[0125] When a vulcanization accelerator is contained, the content thereof is preferably 1.0 part by mass or more, more preferably 2.0 parts by mass or more, and preferably 10.0 parts by mass or less, more preferably 7.0 parts by mass or less, based on 100 parts by mass of the rubber component.

[0126] In addition to the above components, the rubber composition may further contain other compounding agents (such as organic crosslinking agents) that are generally used in the tire industry. The content of these compounding agents is preferably 0.1 to 200 parts by mass per 100 parts by mass of the rubber component.

[0127] 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.

[0128] 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 70 to 180°C, preferably 80 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.

[0129] Among these, the method for producing the rubber composition is preferably a method including a step (I) of kneading a rubber component containing SBR, silica, and a mercapto-based silane coupling agent, and a step (II) of maintaining the kneaded mixture obtained in the step (I) at a high temperature.

[0130] The kneading in step (I) can be performed by a known method capable of kneading each component while controlling the temperature. The kneading temperature in step (I) is preferably 70 to 130°C, more preferably 80 to 125°C, and even more preferably 80 to 120°C. By setting the temperature at or above the lower limit, good abrasion resistance and the like tend to be obtained. By setting the temperature at or below the upper limit, the dispersibility of silica during kneading tends to be improved.

[0131] The kneading time in step (I) is preferably 30 seconds to 10 minutes, more preferably 2 to 8 minutes, and even more preferably 3 to 7 minutes. By making it equal to or greater than the lower limit, good abrasion resistance and the like tend to be obtained. By making it equal to or less than the upper limit, the dispersibility of silica during kneading tends to be improved.

[0132] In step (II), the kneaded material obtained in step (I) is held (left stationary) at a high temperature. The holding method is not particularly limited as long as it can control the temperature, and for example, a thermostatic device such as an oven can be suitably used. Also, the high temperature holding may be performed in the kneader used in step (I).

[0133] The holding temperature in step (II) is preferably 130°C or higher, more preferably 135°C or higher, even more preferably 140°C or higher, particularly preferably 145°C or higher, and most preferably 150°C or higher. By setting it to the lower limit or higher, the reaction between the silane coupling agent and the silica is promoted, and the dispersibility of the silica is improved, which tends to improve fuel efficiency. The holding temperature is preferably 185°C or lower, more preferably 170°C or lower, and even more preferably 160°C or lower. By setting it to the upper limit or lower, it tends to prevent the reaction between the silica and the silane coupling agent from proceeding too far, causing the rubber composition to gel and making it difficult to mold a tire.

[0134] The retention time of step (II) is preferably 30 seconds or more, more preferably 70 seconds or more, even more preferably 100 seconds or more, and particularly preferably 150 seconds or more. By making it equal to or greater than the lower limit, the reaction between the silane coupling agent and silica tends to be promoted. The upper limit of the retention time is not particularly limited, but even if it exceeds 300 seconds, performance improvement cannot be obtained, so it is preferably 300 seconds or less.

[0135] After carrying out step (II), sulfur, a vulcanization accelerator, and the like are further added and kneaded by a known method, and then vulcanized to obtain the rubber composition (rubber composition after vulcanization). The vulcanization temperature may be appropriately set, and the vulcanization temperature described above can be used.

[0136] 〔tire〕 The tire of the present invention is produced by a conventional method using the above rubber composition. That is, the rubber composition is extruded in an unvulcanized state to match the shape of the tread, and molded together with other tire components in a tire building machine by a normal method to form an unvulcanized tire. The unvulcanized tire is then heated and pressurized in a vulcanizer to obtain a tire.

[0137] The tire may be a pneumatic tire, an airless (solid) tire, or the like, with the pneumatic tire being preferred. The tire may be used as a passenger car tire, a large passenger car tire, a large SUV tire, a heavy-duty tire such as a truck or a bus tire, a light truck tire, a two-wheeled vehicle tire, or a racing tire (high-performance tire). The tire may also be used as an all-season tire, a summer tire, or a studless tire (winter tire). EXAMPLES

[0138] The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[0139] SBR: NS616 manufactured by Zeon Co., Ltd. (non-oil extended SBR, styrene content 21% by mass, vinyl content 66 mol%, Tg-23°C, Mw 240,000) BR: BR150B (cis content: 97% by mass) manufactured by Ube Industries, Ltd. Carbon black: Diablack I (N220, N2SA114m) manufactured by Mitsubishi Chemical Corporation 2 / g, DBP114ml / 100g) Silica: Ultrasil VN3 (N2SA175m) manufactured by Evonik Degussa 2 / g) Mercapto-based 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 %)) Mercapto-based silane coupling agent 2: NXT (3-octanoylthiopropyltriethoxysilane) manufactured by Momentive Mercapto-based silane coupling agent 3: Si363 manufactured by Evonik Degussa (a silane coupling agent represented by the following formula (R 6 =-O-(C2H4-O)5-C 13 H 27 , R 7 =C2H5-O-, R 8 =-O-(C2H4-O)5-C 13 H 27 , R9 =-C3H6-)) [ka] Sulfide-based silane coupling agent: Degussa's Si69 (bis(3-triethoxysilylpropyl)tetrasulfide) Oil: H&R VIVATEC 400 / 500 (TDAE oil) Stearic acid: Camellia made by NOF Corporation Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Antiaging agent: Antigen 6C (antiaging agent, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd. Wax: Ozoace 0355 made by Nippon Seiro Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Noccela NS (N-tert-butyl-2-benzothiazylsulfenamide (TBBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Noccelaer D (N,N'-diphenylguanidine (DPG)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0140] <Examples and Comparative Examples> Using a Banbury mixer, materials other than sulfur and vulcanization accelerator shown in step (I) of each table were kneaded for 5 minutes under the conditions of a set temperature of 90 ° C and a final reaching temperature of about 120 ° C to obtain a kneaded product. Next, the kneaded product obtained in step (I) was held at a high temperature in the kneader used in step (I) at the holding temperature in each table and left for a predetermined time (step (II)). Thereafter, sulfur and vulcanization accelerator shown in step (III) of each table were added to the kneaded product taken out of the kneader, and 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 press-vulcanized in a 0.5 mm thick mold at 170 ° C for 20 minutes to obtain a vulcanized rubber composition.

[0141] The vulcanized rubber composition (rubber composition after vulcanization) was used to carry out the following evaluations. The results are shown in the tables. The reference comparative examples in Tables 1, 2, and 3 are Comparative Examples 1-1, 2-1, and 3-1, respectively.

[0142] <Viscoelasticity test> (1) Measurement of complex elastic modulus For the vulcanized rubber composition (test piece with width 4 mm, length 2 mm, thickness 2 mm), a viscoelasticity spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.) was used to measure the complex modulus of elasticity (E*(0.5%)) under conditions of initial strain of 10%, dynamic strain of 0.5%, and temperature of 0°C, and the complex modulus of elasticity (E*(5%)) under conditions of initial strain of 10%, dynamic strain of 5%, and temperature of 0°C. (2) Loss tangent measurement For the vulcanized rubber composition (test piece with width 4 mm, length 2 mm, and thickness 2 mm), the loss tangent (tan δ(70°C)) was measured under conditions of initial strain of 10%, dynamic strain of 1%, and temperature of 70°C using a viscoelasticity spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.).

[0143] <Fuel-efficient> The tan δ (70°C) values ​​obtained in the viscoelasticity test were expressed as an index using the following calculation formula, with the tan δ (70°C) of the reference comparative example set at 100. A larger index indicates smaller rolling resistance and better fuel economy. (Rolling resistance index) = (tan δ (70°C) of the standard comparative example) / (tan δ (70°C) of each compound) x 100

[0144] <Wet grip performance> For the vulcanized rubber composition, tan δ was measured using a viscoelasticity spectrometer VES (manufactured by Iwamoto Seisakusho Co., Ltd.) under conditions of a frequency of 10 Hz, a strain of 0.1%, and a temperature of 0° C. The tan δ of the reference comparative example was expressed as an index of 100. A larger index value indicates better wet grip performance.

[0145] <Wear resistance> The abrasion amount of the vulcanized rubber composition was measured using a Lambourn abrasion tester under the conditions of room temperature, a load of 1.0 kgf, and a slip rate of 30%. The reciprocal of the abrasion amount was expressed as an index, with the reference comparative example being set at 100. The larger the value, the more excellent the abrasion resistance.

[0146] [Table 1]

[0147] [Table 2]

[0148] [Table 3]

[0149] From each table, it can be seen that the examples which contained SBR, silica and a mercapto-based silane coupling agent in a specified blend ratio and satisfied the above formulas (1) and (2) had significantly superior overall performance (expressed as the average of the three indices of fuel economy, wet grip performance and abrasion resistance) in terms of fuel economy, wet grip performance and abrasion resistance.

Claims

1. Contains styrene butadiene rubber, silica and a mercapto-based silane coupling agent, The content of the styrene-butadiene rubber in 100% by mass of the rubber component is 50% by mass or more, The content of the silica per 100 parts by mass of the rubber component is 30 to 120 parts by mass, A rubber composition for a tread which satisfies the following formulas (1) and (2): [0010] [0025]

2. A composition comprising styrene-butadiene rubber, silica, and a mercapto-based silane coupling agent, The content of the styrene-butadiene rubber in 100% by mass of the rubber component is 50% by mass or more, The content of the silica per 100 parts by mass of the rubber component is 30 to 120 parts by mass, A rubber composition for a tread that satisfies the following formulas (1) and (2) (excluding the rubber compositions for a tread of (1) to (4) below). [0030] [0045] (1) A rubber composition for a tread, comprising an alkylene group having 3 or more carbon atoms, a polysulfide group bonded to the alkylene group, and a crosslinking agent having a functional group containing a benzene ring. (2) A rubber composition for treads, comprising at least one surfactant selected from the group consisting of polyoxyalkylene alkenyl ether sulfates and polyoxyalkylene alkyl ether sulfates. (3) A rubber composition for treads, comprising a conjugated diene-based polymer having a structural unit based on a conjugated diene and a structural unit represented by the following formula (I), in which at least one end of the polymer is modified with a compound represented by the following formula (II): 【number】 [In the formula, X 1 , X 2 and X 3 each independently represent a group represented by the following formula (Ia), a hydroxyl group, a hydrocarbyl group or a substituted hydrocarbyl group, and at least one of X 1 , X 2 and X 3 is a group represented by the following formula (Ia) or a hydroxyl group.] 【number】 [In the formula, R 1 and R 2 each independently represent a hydrocarbyl group having 1 to 6 carbon atoms, a substituted hydrocarbyl group having 1 to 6 carbon atoms, a silyl group, or a substituted silyl group, and R 1 and R 2 may be bonded to form a ring structure together with the nitrogen atom.] 【number】 [In the formula, n represents an integer of 1 to 10, R 3 , R 4 and R 5 each independently represent a hydrocarbyl group having 1 to 4 carbon atoms or a hydrocarbyloxy group having 1 to 4 carbon atoms, at least one of R 3 , R 4 and R 5 is a hydrocarbyloxy group, and A represents a functional group having a nitrogen atom.] (4) A rubber composition for treads obtained by kneading an amine-based antioxidant in a separate kneading step after kneading the rubber component and all of the silane coupling agents.

3. A composition comprising styrene-butadiene rubber, silica, and a mercapto-based silane coupling agent, The content of the styrene-butadiene rubber in 100% by mass of the rubber component is 50% by mass or more, The content of the silica per 100 parts by mass of the rubber component is 30 to 120 parts by mass, A rubber composition for a tread that satisfies the following formulas (1) and (2) (excluding the rubber compositions for a tread of (1) to (4) below). [0050] [006] (1) A rubber composition for treads, comprising: a rubber component including a butadiene polymer having a trans content of 45% by mass or more and a vinyl content of 20% by mass or less; silica; a silane coupling agent having two or more functional groups including a sulfur atom capable of bonding to a diene rubber; and a crosslinking agent having an alkylene group having 3 or more carbon atoms, a polysulfide group bonded to the alkylene group, and a functional group including a benzene ring. (2) A rubber composition for treads, comprising a rubber component containing 30 mass% or more of styrene-butadiene rubber having an SiOR group (R is a hydrogen atom or a hydrocarbon group), 50 mass% or more of silica having a nitrogen adsorption specific surface area of ​​210 m2 / g or more per 100 mass% of the rubber component, and at least one surfactant selected from the group consisting of polyoxyalkylene alkenyl ether sulfate salts and polyoxyalkylene alkyl ether sulfate salts. (3) A rubber composition for a tread comprising a rubber component, silica and a silane coupling agent, In 100% by mass of the rubber component, the content of a conjugated diene-based polymer having a structural unit based on a conjugated diene and a structural unit represented by the following formula (I), at least one end of the polymer being modified with a compound represented by the following formula (II), is 5% by mass or more, The content of the silica per 100 parts by mass of the rubber component is 5 to 150 parts by mass, A rubber composition for a tread, wherein the silane coupling agent has a mercapto group. 【number】 [In the formula, X 1 , X 2 and X 3 each independently represent a group represented by the following formula (Ia), a hydroxyl group, a hydrocarbyl group or a substituted hydrocarbyl group, and at least one of X 1 , X 2 and X 3 is a group represented by the following formula (Ia) or a hydroxyl group.] 【number】 [In the formula, R 1 and R 2 each independently represent a hydrocarbyl group having 1 to 6 carbon atoms, a substituted hydrocarbyl group having 1 to 6 carbon atoms, a silyl group, or a substituted silyl group, and R 1 and R 2 may be bonded to form a ring structure together with the nitrogen atom.] 【number】 [In the formula, n represents an integer of 1 to 10, R 3 , R 4 and R 5 each independently represent a hydrocarbyl group having 1 to 4 carbon atoms or a hydrocarbyloxy group having 1 to 4 carbon atoms, at least one of R 3 , R 4 and R 5 is a hydrocarbyloxy group, and A represents a functional group having a nitrogen atom.] (4) A rubber composition for treads, which contains 60 to 200 parts by mass of silica, 1.5 to 5.0 parts by mass of an amine-based antioxidant, and at least one silane coupling agent selected from the group consisting of silane coupling agent 1 having a carbonylthio group (-S-C(=O)-) and no mercapto group (-SH), and silane coupling agent 2 having a mercapto group, relative to 100 parts by mass of a rubber component containing a copolymer obtained by copolymerizing an aromatic vinyl compound and a conjugated diene compound, and which is obtained by kneading the amine-based antioxidant in a separate kneading step after kneading the rubber component and all of the silane coupling agents.

4. A rubber composition comprising styrene butadiene rubber, butadiene rubber, silica, carbon black, and a mercapto-based silane coupling agent, the rubber component is composed only of the styrene-butadiene rubber and the butadiene rubber, a content of the styrene-butadiene rubber in 100% by mass of the rubber component is 50% by mass or more and 80% by mass or less, and a content of the butadiene rubber is 20% by mass or more and 50% by mass or less, the content of the silica is 30 to 120 parts by mass and the content of the carbon black is 10 parts by mass or more relative to 100 parts by mass of the rubber component, A rubber composition for a tread which satisfies the following formulas (1) and (2): [0070] [0080]

5. The rubber composition for treads according to any one of claims 1 to 4, which satisfies the following formula (1-1): [0090]

6. The rubber composition for treads according to any one of claims 1 to 5, which satisfies the following formula (1-2): [0010]

7. The rubber composition for treads according to any one of claims 1 to 6, wherein the styrene-butadiene rubber contains a styrene content of 5 to 50 mass % and a weight average molecular weight of 100,000 to 1,600,000.

8. The rubber composition for a tread according to any one of claims 1 to 7, which contains a butadiene rubber.

9. The rubber composition for treads according to any one of claims 1 to 8, wherein the mercapto-based silane coupling agent contains a silane coupling agent represented by the following formula (2-1): 【Chemistry 7】 (In formula (2-1), R １０１ is -Cl, -Br, -OR １０６ , -O(O=)CR １０６ , -ON=CR １０６ R １０７ , -NR １０６ R １０７ and -(OSiR １０６ R １０７ ) ｈ (OSiR １０６ R １０７ R １０８ A monovalent group (R １０６ , R １０７ and R １０８ 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; １０２ is R １０１ , a hydrogen atom or a monovalent hydrocarbon group having 1 to 18 carbon atoms, R １０３ is - [O(R １０９ O) ｊ ]-group (R １０９ is an alkylene group having 1 to 18 carbon atoms, and j is an integer of 1 to 4. １０４ is a divalent hydrocarbon group having 1 to 18 carbon atoms, R １０５ represents a monovalent hydrocarbon group having 1 to 18 carbon atoms, and xa, ya, and za are numbers that satisfy the relationship: xa+ya+2za=3, 0≦xa≦3, 0≦ya≦2, 0≦za≦1.

10. The mercapto-based silane coupling agent includes a silane coupling agent having a bond unit A represented by the following formula (2-2) and a bond unit B represented by the following formula (2-3). The rubber composition for tread according to any one of claims 1 to 9. 【Chemistry 8】 【Chemistry 9】 (In formulas (2-2) and (2-3), xb is an integer of 0 or more, and yb is an integer of 1 or more. R ２０１ 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 whose terminal hydrogen atom has been substituted with a hydroxyl group or a carboxyl group. ２０２ 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. ２０１ and R ２０２ may form a ring structure.)

11. The rubber composition for treads according to any one of claims 1 to 10, wherein the mercapto-based silane coupling agent includes a silane coupling agent represented by the following formula (2-4): 【Chemistry 10】 (In the formula, R ６ ~R ８ represents a branched or unbranched alkyl group having 1 to 12 carbon atoms, a branched or unbranched alkoxy group having 1 to 12 carbon atoms, or -O-(R １１１ -O) ｚ -R １１２ (z R １１１ represents a branched or unbranched divalent hydrocarbon group having 1 to 30 carbon atoms. １１１ may be the same or different. １１２ represents a branched or unbranched alkyl group having 1 to 30 carbon atoms, a branched or unbranched alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms; z represents an integer of 1 to 30. ６ ~R ８ may be the same or different. ９ represents a branched or unbranched alkylene group having 1 to 6 carbon atoms.

12. The rubber composition for a tread according to any one of claims 1 to 11, which contains carbon black.

13. The rubber composition for tread according to any one of claims 1 to 12, which is obtained by a manufacturing method including: a step (I) of kneading silica and a mercapto-based silane coupling agent; and a step (II) of maintaining the kneaded mixture obtained in the step (I) at 130°C or higher.

14. A tire having a tread made of the rubber composition according to any one of claims 1 to 13.

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