JP2020063335A - Rubber composition for tread, and tire - Google Patents

Abstract

To provide a rubber composition for a tread excellent in overall performance including wet grip performance, low fuel consumption performance and abrasion resistance performance, and also to provide a tire equipped with a tread composed of the rubber composition for a tread.SOLUTION: A rubber composition for a tread includes, based on 100 pts.mass of a rubber component containing 60-80 mass% of a styrene-butadiene rubber and 20-40 mass% of a butadiene rubber: 1-40 pts.mass of carbon black; and 50-150 pts.mass of silica. In the rubber composition for a tread, tan δ is 0.60 or less at 0°C and at a dynamic strain amplitude of 0.5%, and peak temperature of the tan δ is -17°C or less. A tire is equipped with a tread composed of the rubber composition for a tread.SELECTED DRAWING: None

Description

  The present invention relates to a rubber composition for a tread and a tire provided with a tread composed of the rubber composition.

  In recent years, from the standpoints of resource saving, energy saving, and environmental protection as well, social demands for reducing carbon dioxide emissions have increased, and various measures such as weight reduction for automobiles and use of electric energy have been studied. ing. Therefore, it is required to reduce rolling resistance of an automobile tire and improve fuel economy, and it is also desired to improve performance such as abrasion resistance.

  For example, as a method for reducing rolling resistance, Patent Document 1 proposes a method using a diene rubber (modified rubber) modified with an organosilicon compound containing an amino group and an alkoxy group.

JP 2000-344955 A

  However, in the rubber composition of Patent Document 1, the reaction efficiency between silica and rubber is improved and the fuel economy is improved, while the bond between silica and rubber becomes too tight, resulting in wear resistance. There is room for improvement. In addition, a rubber composition for an automobile tire is required to have excellent wet grip performance from the viewpoint of safety.

  Therefore, the present invention provides a rubber composition for a tread excellent in overall performance such as wet grip performance, low fuel consumption performance and abrasion resistance, and a tire provided with a tread composed of the rubber composition for a tread. With the goal.

  As a result of intensive studies, the present inventors have found that a rubber composition for a tread containing a predetermined amount of carbon black and a predetermined amount of silica in 100 parts by mass of a rubber component containing a predetermined amount of styrene-butadiene rubber and a predetermined amount of BR. The tan δ at a dynamic strain amplitude of 0.5% at 0 ° C. is 0.60 or less, and the tan δ peak temperature is -17 ° C. or less to provide a tread rubber composition, whereby the above problems can be solved. The present invention has been completed through further studies.

（式中、Ｒ¹⁰¹〜Ｒ¹⁰³は、直鎖もしくは分岐鎖の炭素数１〜１２のアルキル基、直鎖もしくは分岐鎖の炭素数１〜１２のアルコキシ基、または−Ｏ−（Ｒ¹¹¹−Ｏ）_z−Ｒ¹¹²（ｚ個のＲ¹¹¹は、直鎖もしくは分岐鎖の炭素数１〜３０の２価の炭化水素基を表す。ｚ個のＲ¹¹¹は、それぞれ同一でも異なっていてもよい。Ｒ¹¹²は、直鎖もしくは分岐鎖の炭素数１〜３０のアルキル基、直鎖もしくは分岐鎖の炭素数２〜３０のアルケニル基、炭素数６〜３０のアリール基、または炭素数７〜３０のアラルキル基を表す。ｚは、１〜３０の整数を表す。）で表される基を表す。Ｒ¹⁰¹〜Ｒ¹⁰³はそれぞれ同一でも異なっていてもよい。Ｒ¹⁰⁴は、直鎖もしくは分岐鎖の炭素数１〜６のアルキレン基を表す。）

（式中、ｘは０以上の整数、ｙは１以上の整数である。Ｒ²⁰¹は、水素原子、ハロゲン原子、直鎖もしくは分岐鎖の炭素数１〜３０のアルキル基、直鎖もしくは分岐鎖の炭素数２〜３０のアルケニル基、直鎖もしくは分岐鎖の炭素数２〜３０のアルキニル基、または該アルキル基の末端の水素原子が水酸基もしくはカルボキシル基で置換されたものを表す。Ｒ²⁰²は、直鎖もしくは分岐鎖の炭素数１〜３０のアルキレン基、直鎖もしくは分岐鎖の炭素数２〜３０のアルケニレン基、または、直鎖もしくは分岐鎖の炭素数２〜３０のアルキニレン基を表す。Ｒ²⁰¹とＲ²⁰²とで環構造を形成してもよい。）、ならびに
［５］上記［１］〜［４］のいずれかに記載のトレッド用ゴム組成物で構成されるトレッドを備えるタイヤ
に関する。 That is, the present invention is
[1] 60-80% by mass of styrene-butadiene rubber, preferably 65-75% by mass, more preferably 65-70% by mass or 70-75% by mass and 20-40% by mass of butadiene rubber, preferably 25-35%. 100 parts by mass of the rubber component containing 30% by mass, more preferably 30 to 35% by mass,
Carbon black is 1 to 40 parts by mass, preferably 3 to 30 parts by mass, more preferably 5 to 20 parts by mass, and silica is 50 to 150 parts by mass, preferably 55 to 115 parts by mass, more preferably 60 to 100 parts by mass. Part, and tan δ at a dynamic strain amplitude of 0.5% at 0 ° C. is 0.60 or less, preferably 0.25 to 0.45, more preferably 0.25 to 0.40, and further preferably 0. 25 to 0.35, particularly preferably 0.25 to 0.30, and the peak temperature of tan δ is -17 ° C or lower, preferably -28 to -17 ° C, more preferably -28 to -18 ° C, and further preferably Is a rubber composition for a tread having a temperature of -23 to -18 ° C, particularly preferably -23 to -19 ° C,
[2] The rubber composition for a tread according to the above [1], which contains aluminum hydroxide,
[3] The rubber for tread according to the above [1] or [2], which contains 10 to 80 parts by mass, preferably 15 to 70 parts by mass, and more preferably 20 to 60 parts by mass of oil with respect to 100 parts by mass of the rubber component. Composition,
[4] A compound represented by the following formula (1) and / or a compound containing a binding unit A represented by the following formula (2) and a binding unit B represented by the following formula (3), mercapto. The rubber composition for a tread according to any one of the above [1] to [3], which contains a silane coupling agent having a group.

(In the formula, R ^{101 to} R ¹⁰³ are a linear or branched alkyl group having 1 to 12 carbon atoms, a linear or branched alkoxy group having 1 to 12 carbon atoms, or —O— (R ¹¹¹ —O ) _Z- R ¹¹² (z R ^{111 s} represent a linear or branched divalent hydrocarbon group having 1 to 30 carbon atoms. The Z R ^{111 s} may be the same or different. R ¹¹² is a linear or branched alkyl group having 1 to 30 carbon atoms, a linear or branched alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or a C 7 to 30 carbon atom. Represents an aralkyl group, z represents an integer of 1 to 30), R ^{101 to} R ¹⁰³ may be the same or different, and R ¹⁰⁴ represents a linear or branched chain. It represents an alkylene group having 1 to 6 carbon atoms.)

(In the formula, x is an integer of 0 or more and y is an integer of 1 or more. R ²⁰¹ is a hydrogen atom, a halogen atom, a linear or branched alkyl group having 1 to 30 carbon atoms, a linear or branched chain) alkenyl group having 2 to 30 carbon atoms, .R ²⁰² representing those straight or branched chain alkynyl group having 2 to 30 carbon atoms or a terminal hydrogen atom of the alkyl group is substituted with a hydroxyl group or a carboxyl group Represents a linear or branched alkylene group having 1 to 30 carbon atoms, a linear or branched alkenylene group having 2 to 30 carbon atoms, or a linear or branched alkynylene group having 2 to 30 carbon atoms. R ²⁰¹ and R ²⁰² may form a ring structure.), And [5] a tire provided with a tread composed of the rubber composition for a tread according to any one of the above [1] to [4]. ..

  1 to 40 parts by mass of carbon black and 50 to 150 parts by mass of silica are contained in 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. The tan δ at a strain amplitude of 0.5% is 0.60 or less, and the tread rubber composition of the present invention having a tan δ peak temperature of -17 ° C. or less has a wet grip performance by using in a tread of a tire. A tire having excellent overall performance such as low fuel consumption performance and wear resistance performance can be obtained.

  A rubber composition for a tread, which is one embodiment, comprises 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 silica. It is characterized by containing 50 to 150 parts by mass, tan δ at a dynamic strain amplitude of 0.5% at 0 ° C. of 0.60 or less, and a tan δ peak temperature of −17 ° C. or less. With this feature, it is possible to dramatically improve the overall performance of the tire such as wet grip performance, low fuel consumption performance and wear resistance performance, as compared with a rubber composition using the same composition. Specifically, by setting the tan δ peak temperature to a low value of −17 ° C. or lower, energy loss at a tire temperature of 30 to 40 ° C. can be reduced, and RRC (rolling resistance coefficient) can be reduced. Conceivable. At this time, it is considered that the abrasion resistance can be improved by containing BR in an amount of 20% by mass or more and setting the tan δ peak temperature to be -17 ° C or less. As described above, the tan δ at a dynamic strain amplitude of 0.5% at 0 ° C. was 0.60 or less, and the peak temperature of tan δ was -17 ° C. or less, whereby the ultra-fuel-saving formulation was applied. Even in the case of a tire, it is considered that RRC can be further lowered at the same level of tan δ (30 ° C.), that is, fuel consumption can be reduced, as compared with a compound having a higher tan δ peak temperature.

  The tan δ (hereinafter also referred to as tan δ (0 ° C.)) at a dynamic strain amplitude of 0.5% at 0 ° C. of the rubber composition for a tread, which is one embodiment, is 0.60 or less, and 0.45 or less. It is preferably 0.40 or less, more preferably 0.35 or less, and particularly preferably 0.30 or less. If tan δ (0 ° C.) exceeds 0.60, the fuel efficiency in winter may deteriorate. Further, tan δ (0 ° C.) is preferably 0.25 or more. When tan δ is (0 ° C.) 0.25 or more, good wet grip performance tends to be obtained. It should be noted that tan δ (0 ° C.) is a value obtained by the measuring method described in Examples described later.

  The tan δ peak temperature of the rubber composition for a tread which is one embodiment is -17 ° C or lower, preferably -18 ° C or lower, and more preferably -19 ° C or lower. If the tan δ peak temperature exceeds -17 ° C, the fuel efficiency in winter may deteriorate. The tan δ peak temperature of the rubber composition for a tread of the present invention is preferably -28 ° C or higher, more preferably -23 ° C or higher. By setting the tan δ peak temperature to −28 ° C. or higher, good wet grip performance tends to be obtained. The tan δ peak temperature is a value obtained by the measuring method described in Examples below.

  In a rubber composition containing 1 to 40 parts by mass of carbon black and 50 to 150 parts by mass of silica in 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, tan δ Satisfying (0 ° C.) ≦ 0.60 and tan δ peak temperature ≦ −17 ° C. means that the Tg of the styrene-butadiene rubber or butadiene rubber used, specifically, the tread rubber based on the combined rubber components. The tan δ peak temperature of the composition is optimized and selected so as to be −9 ° C. or lower, and the amount of other compounding agents such as oil and resin is adjusted, thereby imposing an excessive burden on those skilled in the art. Can be done without.

(Rubber component)
In one embodiment, the rubber component contains 60 to 80 mass% of styrene-butadiene rubber (SBR) and 20 to 40 mass% of butadiene rubber (BR). In addition to SBR and BR, other rubber components include, for example, natural rubber (NR), deproteinized natural rubber (DPNR), high-purity natural rubber (HPNR), epoxidized natural rubber (ENR), isoprene rubber (IR). Etc. may be included, but only SBR and BR are preferred.

(SBR)
The SBR is not particularly limited, and examples thereof include solution polymerization SBR (S-SBR), emulsion polymerization SBR (E-SBR), and modified SBRs thereof (modified S-SBR, modified E-SBR) and the like. Examples of the modified SBR include SBR whose terminal and / or main chain is modified, modified SBR coupled with tin, a silicon compound or the like (condensate, one having a branched structure, etc.) and the like. Of these, S-SBR is preferable. Furthermore, hydrogenated products of these SBRs (hydrogenated SBRs) and the like can also be used. These SBRs may be used alone or in combination of two or more.

  Examples of the S-SBR that can be used in this embodiment include S-SBR manufactured and sold by JSR Corporation, Ube Industries, Ltd., Asahi Kasei Corporation, ZS Elastomer Co., Ltd., and the like.

From the viewpoint of grip performance, the styrene content of SBR is preferably 10% by mass or more, more preferably 15% by mass or more, and further preferably 20% by mass or more. If the styrene content is too large, the styrene groups are adjacent to each other, the polymer becomes too hard, and the cross-linking tends to become non-uniform, which may deteriorate the blowability during high-temperature running. Therefore, the stable styrene content of the SBR tends to be poor during running and in the latter half of the period, so that the styrene content of SBR is preferably 55% by mass or less, and more preferably 50% by mass or less. It is preferably 45% by mass or less. In the present specification, the styrene content of SBR is calculated by ¹ H-NMR measurement.

  The vinyl bond amount of SBR is preferably 10 mol% or more, more preferably 15 mol% or more, and further preferably 20 mol% or more, from the viewpoint of ensuring the reactivity with silica, rubber strength and abrasion resistance. Further, the vinyl bond content of SBR is preferably 70 mol% or less, more preferably 65 mol% or less, and 60 mol% or less from the viewpoint of prevention of increase in temperature dependence, grip performance, EB (durability), and abrasion resistance. The following is more preferable. In addition, in this specification, the vinyl bond amount (1,2-bond butadiene unit amount) of SBR is measured by an infrared absorption spectrum analysis method.

  The weight average molecular weight (Mw) of SBR is preferably 200,000 or more, more preferably 300,000 or more, further preferably 400,000 or more, and particularly preferably 500,000 or more from the viewpoint of wear resistance and grip performance. Further, Mw is preferably 2,000,000 or less, more preferably 150 or less, and further preferably 1,000,000 or less, from the viewpoint of crosslinking uniformity. In addition, Mw is based on the measured value by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMALTORE HZ-M manufactured by Tosoh Corporation). In addition, it can be determined by standard polystyrene conversion.

  The content of SBR in the rubber component is 60% by mass or more, preferably 65% by mass or more, and more preferably 70% by mass or more. When the content of SBR in the rubber component is less than 60% by mass, grip performance on wet road surfaces tends to be insufficient. Further, the content of SBR in the rubber component is 80% by mass or less, preferably 75% by mass or less, and more preferably 70% by mass or less. If the content of SBR in the rubber component exceeds 80% by mass, the abrasion resistance tends to be insufficient.

(BR)
The BR is not particularly limited, and examples thereof include BR having a cis 1,4 bond content of less than 50% (low cis BR), BR having a cis 1,4 bond content of 90% or more (high cis BR), and rare earth. Rare earth butadiene rubber synthesized using elemental catalyst (rare earth BR), BR containing syndiotactic polybutadiene crystals (SPB containing BR), modified BR (high cis modified BR, low cis modified BR) etc. Common in tire industry It is possible to use a specific one.

  Examples of the high cis BR include BR1220 manufactured by Nippon Zeon Co., Ltd., BR130B, BR150B, BR150L manufactured by Ube Industries, Ltd., BR730 manufactured by JSR Corporation, and the like. By containing high cis BR, low temperature characteristics and wear resistance can be improved. Examples of the rare earth BR include BUNA-CB25 manufactured by LANXESS Co., Ltd. and the like.

  Examples of the SPB-containing BR include those in which 1,2-syndiotactic polybutadiene crystals are not simply dispersed in BR, but are dispersed after being chemically bonded to BR. Examples of such SPB-containing BR include VCR-303, VCR-412 and VCR-617 manufactured by Ube Industries, Ltd.

  The modified BR is obtained by polymerizing 1,3-butadiene with a lithium initiator, and then added with a tin compound, and the modified BR molecule is further bound at its end with a tin-carbon bond (tin. Modified BR), butadiene rubber having a condensed alkoxysilane compound at the active end of butadiene rubber (modified BR for silica), and the like. Examples of such modified BR include BR1250H (tin modified) and S modified polymer (modified for silica) manufactured by ZS Elastomer Co., Ltd.

  From the viewpoint of abrasion resistance and grip performance, the weight average molecular weight (Mw) of BR is preferably 300,000 or more, more preferably 400,000 or more, and further preferably 450,000 or more. Further, Mw is preferably 2,000,000 or less, and more preferably 1,000,000 or less from the viewpoint of cross-linking uniformity and the like. In addition, Mw is based on the measured value by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMALTORE HZ-M manufactured by Tosoh Corporation). In addition, it can be determined by standard polystyrene conversion.

  The content of BR in the rubber component is 20% by mass or more, preferably 25% by mass or more, and more preferably 30% by mass or more. When the content of BR in the rubber component is less than 20% by mass, abrasion resistance tends to be insufficient. Further, the content of BR in the rubber component is 40% by mass or less, preferably 35% by mass or less, and more preferably 30% by mass or less. If the content of BR in the rubber component exceeds 40% by mass, grip performance on wet road surfaces tends to be insufficient.

(Carbon black)
The carbon black is not particularly limited, and those commonly used in the tire industry such as GPF, FEF, HAF, ISAF and SAF can be used, and specifically, N110, N115, N120, N125, N134, N135, N219 and N220. , N231, N234, N293, N299, N326, N330, N339, N343, N347, N351, N356, N358, N375, N539, N550, N582, N630, N642, N650, N660, N683, N754, N762, N765, N765. , N774, N787, N907, N908, N990, N991 and the like can be preferably used, and in addition to these, in-house synthesized products and the like can also be preferably used. These may be used alone or in combination of two or more.

The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is preferably 50 m ² / g or more, more preferably 80 m ² / g or more, from the viewpoint of weather resistance and reinforcing property. Also, N ₂ SA of carbon black is low fuel consumption, dispersibility, preferably 250 meters ² / g or less from the viewpoint of fracture properties and durability, and more preferably at most 220 m ² / g. The N ₂ SA of carbon black in the present specification is in accordance with the method A of JIS K 6217-2 “Basic characteristics of carbon black for rubber-Part 2: Determination of specific surface area-Nitrogen adsorption method-single point method”. It is the value measured by

  The content of carbon black with respect to 100 parts by mass of the rubber component is 1 part by mass or more, preferably 3 parts by mass or more, and more preferably 5 parts by mass or more. If the content of carbon black is less than 1 part by mass, the weather resistance cannot be ensured and cracks due to ultraviolet rays may occur. The content of carbon black with respect to 100 parts by mass of the rubber component is 40 parts by mass or less, preferably 30 parts by mass or less, and more preferably 15 parts by mass or less. If the content of carbon black exceeds 40 parts by mass, sufficient fuel economy may not be realized.

(silica)
In one embodiment silica is used. By adding silica, it is possible to improve fuel economy, wear resistance and wet grip performance. The silica is not particularly limited, and for example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrous silica), or the like, which is commonly used in the tire industry, should be used. You can Of these, hydrous silica prepared by a wet method is preferable because it has many silanol groups. Silica may be used alone or in combination of two or more kinds.

BET specific surface area of the silica, from the viewpoint of durability and elongation at break is preferably at least ^{80m 2 / g, 100m 2 /} g or more, more preferably, 150 meters ² / g or more and more preferably, 180 m ² / g or more and particularly preferable. Further, BET specific surface area of the silica, from the viewpoint of fuel economy and workability, preferably 300 meters ² / g or less, more preferably 250m ² / g. The BET specific surface area of silica in the present specification is a value measured by the BET method according to ASTM D3037-93.

  The content of silica is 50 parts by mass or more, preferably 55 parts by mass or more, and more preferably 60 parts by mass or more with respect to 100 parts by mass of the rubber component. When the content of silica is less than 50 parts by mass, the effect of improving fuel economy by blending silica tends not to be sufficiently obtained, the effect of improving wear resistance performance tends not to be sufficiently obtained, and wet. It may not be possible to obtain sufficient grip performance on the road surface. The content of silica is 150 parts by mass or less, preferably 115 parts by mass or less, and more preferably 100 parts by mass or less with respect to 100 parts by mass of the rubber component. When the content of silica exceeds 150 parts by mass, the dispersibility of silica in rubber deteriorates, so that the fuel consumption performance and wear resistance tend to decrease, the processability of rubber deteriorates, and particularly the viscosity becomes too high for processing. Can be difficult.

  In the rubber composition for a tread according to one embodiment, in addition to the above components, a compounding agent generally used in the conventional tire industry, for example, a reinforcing filler other than carbon black and silica, a silane coupling agent, an oil. , Tackifying resins, waxes, processing aids, various antiaging agents, softening agents, vulcanizing agents such as zinc oxide, stearic acid and sulfur, various vulcanization accelerators and the like can be appropriately contained.

(Other reinforcing fillers)
As the reinforcing filler other than carbon black and silica, those conventionally used in rubber compositions for treads, such as aluminum hydroxide, calcium carbonate, alumina, clay and talc, can be blended.

(Aluminum hydroxide)
As the aluminum hydroxide, those commonly used in the tire industry can be used, and examples thereof include Heidilite (registered trademark) manufactured by Showa Denko KK and Apiral (registered trademark) manufactured by Navaltech Corporation. . The aluminum hydroxide in the present embodiment also includes alumina hydrate.

From the viewpoint of wet grip performance, the nitrogen adsorption specific surface area (N ₂ SA) of aluminum hydroxide is preferably 4 m ² / g or more, more preferably 5 m ² / g or more, and even more preferably 6 m ² / g or more. Also, N ₂ SA of the aluminum hydroxide, the dispersibility of the aluminum hydroxide, re aggregation preventing, from the viewpoint of abrasion resistance, preferably from 50 m ² / g or less, more preferably ^{45m 2 / g, 40m 2 /} g The following is more preferable. The N ₂ SA of aluminum hydroxide in the present specification is a value measured by the BET method according to ASTM D3037-81.

  The average particle diameter (D50) of aluminum hydroxide is preferably 0.1 μm or more, more preferably 0.2 μm or more, and more preferably 0.3 μm or more, from the viewpoints of dispersibility of aluminum hydroxide, prevention of re-aggregation, and abrasion resistance. More preferable. The average particle diameter (D50) of aluminum hydroxide is preferably 3.0 μm or less, and more preferably 2.0 μm or less, from the viewpoint of wear resistance performance. The average particle diameter (D50) in the present specification is the particle diameter at which the integrated mass value of the particle diameter distribution curve determined by the particle diameter distribution measuring device is 50%.

  When aluminum hydroxide is contained, the content with respect to 100 parts by mass of the rubber component is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, still more preferably 10 parts by mass or more. When the content of aluminum hydroxide is 3 parts by mass or more, the wet grip performance tends to be good. Further, the content of aluminum hydroxide with respect to 100 parts by mass of the rubber component is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and further preferably 15 parts by mass or less. By setting the content of aluminum hydroxide to 30 parts by mass or less, the abrasion resistance tends to be good.

(Silane coupling agent)
Since the rubber composition for a tread according to one embodiment contains silica, it is preferable to use a silane coupling agent together. The silane coupling agent is not particularly limited, and any silane coupling agent conventionally used in combination with silica in the tire industry can be used. Specific examples of the silane coupling agent include, for example, bis (3-triethoxysilylpropyl) tetrasulfide, bis (2-triethoxysilylethyl) tetrasulfide, bis (4-triethoxysilylbutyl) tetrasulfide, bis ( 3-trimethoxysilylpropyl) tetrasulfide, bis (2-trimethoxysilylethyl) tetrasulfide, bis (4-trimethoxysilylbutyl) tetrasulfide, bis (3-triethoxysilylpropyl) trisulfide, bis (2- Triethoxysilylethyl) trisulfide, bis (4-triethoxysilylbutyl) trisulfide, bis (3-trimethoxysilylpropyl) trisulfide, bis (2-trimethoxysilylethyl) trisulfide, bis (4-trimethoxy Cyril Chill) 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, 3-triethoxysilylpropyl-N, N-dimethyl Thiocarbamoyltetrasulfide, 2-triethoxysilylethyl-N, N-dimethylthiocarbamoyltetrasulfide, 2-trimethoxysilylethyl-N, N-dimethylthiocarbamoyltetrasulfide, 3-trimethoxy Silane coupling agents having a sulfide group such as silylpropyl benzothiazolyl tetrasulfide, 3-triethoxysilylpropyl benzothiazolyl tetrasulfide, and 3-trimethoxysilylpropyl methacrylate monosulfide; 3-mercaptopropyltrimethoxysilane, Mercapto such as 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, Si363 made by Evonik Degussa, NXT-Z30, NXT-Z45, NXT-Z60 made by Momentive. Group-containing silane coupling agent; 3-octanoylthio-1-propyltriethoxysilane, 3-hexanoylthio-1-propyltriethoxysilane, 3-octanoylthio-1-propyi Silane coupling agent having a thioester group such as rutrimethoxysilane; silane coupling agent having a vinyl group such as vinyltriethoxysilane; silane coupling agent having an amino group such as 3-aminopropyltriethoxysilane; γ-glyce Silane coupling agent having a glycidoxy group such as cidoxypropyltriethoxysilane; Silane coupling agent having a nitro group such as 3-nitropropyltrimethoxysilane; Silane cup having a chloro group such as 3-chloropropyltrimethoxysilane Examples thereof include a ring agent and the like, and a silane coupling agent having a mercapto group is preferable. These silane coupling agents may be used alone or in combination of two or more.

（式中、Ｒ¹⁰¹〜Ｒ¹⁰³は、直鎖もしくは分岐鎖の炭素数１〜１２のアルキル基、直鎖もしくは分岐鎖の炭素数１〜１２のアルコキシ基、または−Ｏ−（Ｒ¹¹¹−Ｏ）_z−Ｒ¹¹²（ｚ個のＲ¹¹¹は、直鎖もしくは分岐鎖の炭素数１〜３０の２価の炭化水素基を表す。ｚ個のＲ¹¹¹は、それぞれ同一でも異なっていてもよい。Ｒ¹¹²は、直鎖もしくは分岐鎖の炭素数１〜３０のアルキル基、直鎖もしくは分岐鎖の炭素数２〜３０のアルケニル基、炭素数６〜３０のアリール基、または炭素数７〜３０のアラルキル基を表す。ｚは、１〜３０の整数を表す。）で表される基を表す。Ｒ¹⁰¹〜Ｒ¹⁰³はそれぞれ同一でも異なっていてもよい。Ｒ¹⁰⁴は、直鎖もしくは分岐鎖の炭素数１〜６のアルキレン基を表す。）

（式中、ｘは０以上の整数、ｙは１以上の整数である。Ｒ²⁰¹は、水素原子、ハロゲン原子、直鎖もしくは分岐鎖の炭素数１〜３０のアルキル基、直鎖もしくは分岐鎖の炭素数２〜３０のアルケニル基、直鎖もしくは分岐鎖の炭素数２〜３０のアルキニル基、または該アルキル基の末端の水素原子が水酸基もしくはカルボキシル基で置換されたものを表す。Ｒ²⁰²は、直鎖もしくは分岐鎖の炭素数１〜３０のアルキレン基、直鎖もしくは分岐鎖の炭素数２〜３０のアルケニレン基、または、直鎖もしくは分岐鎖の炭素数２〜３０のアルキニレン基を表す。Ｒ²⁰¹とＲ²⁰²とで環構造を形成してもよい。） The silane coupling agent having a mercapto group is a compound represented by the following formula (1), and / or a bonding unit A represented by the following formula (2) and a bonding unit B represented by the following formula (3). It is preferable that the compound contains

(In the formula, R ^{101 to} R ¹⁰³ are a linear or branched alkyl group having 1 to 12 carbon atoms, a linear or branched alkoxy group having 1 to 12 carbon atoms, or —O— (R ¹¹¹ —O ) _Z- R ¹¹² (z R ^{111 s} represent a linear or branched divalent hydrocarbon group having 1 to 30 carbon atoms. The Z R ^{111 s} may be the same or different. R ¹¹² is a linear or branched alkyl group having 1 to 30 carbon atoms, a linear or branched alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or a C 7 to 30 carbon atom. Represents an aralkyl group, z represents an integer of 1 to 30), R ^{101 to} R ¹⁰³ may be the same or different, and R ¹⁰⁴ represents a linear or branched chain. It represents an alkylene group having 1 to 6 carbon atoms.)

(In the formula, x is an integer of 0 or more and y is an integer of 1 or more. R ²⁰¹ is a hydrogen atom, a halogen atom, a linear or branched alkyl group having 1 to 30 carbon atoms, a linear or branched chain) alkenyl group having 2 to 30 carbon atoms, .R ²⁰² representing those straight or branched chain alkynyl group having 2 to 30 carbon atoms or a terminal hydrogen atom of the alkyl group is substituted with a hydroxyl group or a carboxyl group Represents a linear or branched alkylene group having 1 to 30 carbon atoms, a linear or branched alkenylene group having 2 to 30 carbon atoms, or a linear or branched alkynylene group having 2 to 30 carbon atoms. R ²⁰¹ and R ²⁰² may form a ring structure.)

  Hereinafter, the compound represented by the above formula (1) will be described.

R ^{101 to} R ¹⁰³ are linear or branched alkyl groups having 1 to 12 carbon atoms, linear or branched alkoxy groups having 1 to 12 carbon atoms, or —O— (R ¹¹¹ —O) _z —R. It represents a group represented by ¹¹² . At least one of R ^{101 to} R ¹⁰³ is preferably a group represented by —O— (R ¹¹¹ —O) _z —R ¹¹² , and two of them are —O, from the viewpoint that desired effects can be satisfactorily obtained. More preferably, it is a group represented by — (R ¹¹¹ —O) _z —R ¹¹² , and one is a linear or branched alkoxy group having 1 to 12 carbon atoms.

Examples of the linear or branched alkyl group having 1 to 12 carbon atoms (preferably 1 to 5 carbon atoms) of R ^{101 to} R ¹⁰³ include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n- Examples thereof include a 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.

Examples of the linear or branched C 1-12 (preferably C 1-5) alkoxy group of R ^{101 to} R ¹⁰³ include, for example, a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, and n. Examples include -butoxy group, iso-butoxy group, sec-butoxy group, tert-butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, 2-ethylhexyloxy group, octyloxy group and nonyloxy group.

In —O— (R ¹¹¹ —O) _z —R ¹¹² of R ^{101 to} R ¹⁰³ , R ¹¹¹ represents a straight or branched chain having 1 to 30 carbon atoms (preferably having 1 to 15 carbon atoms, more preferably having 1 to 15 carbon atoms). 1 to 3) divalent hydrocarbon group. Examples of the hydrocarbon group include a linear or branched alkylene group having 1 to 30 carbon atoms, a linear or branched alkenylene group having 2 to 30 carbon atoms, and a linear or branched carbon atom having 2 to 30 carbon atoms. And the arylene group having 6 to 30 carbon atoms. Of these, a linear or branched alkylene group having 1 to 30 carbon atoms is preferable.

Examples of the linear or branched alkylene group having 1 to 30 carbon atoms (preferably 1 to 15 carbon atoms, more preferably 1 to 3 carbon atoms) of R ¹¹¹ include, for example, 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, octadecylene group and the like.

Examples of the straight chain or branched chain alkenylene group having 2 to 30 carbon atoms (preferably 2 to 15 carbon atoms, more preferably 2 or 3 carbon atoms) of R ¹¹¹ include, for example, vinylene group, 1-propenylene group, 2- Examples thereof include a 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.

Examples of the linear or branched alkynylene group of R ¹¹¹ having 2 to 30 carbon atoms (preferably 2 to 15 carbon atoms, more preferably 2 or 3 carbon atoms) include, for example, ethynylene group, propynylene group, butynylene group, pentynylene. Group, hexynylene group, heptynylene group, octynylene group, nonynylene group, decynylene group, undecynylene group, dodecynylene group and the like.

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

  z is an integer of 1 to 30, preferably 2 to 20, more preferably 3 to 7, and further preferably 5 or 6.

R ¹¹² is a linear or branched alkyl group having 1 to 30 carbon atoms, a linear or branched alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl having 7 to 30 carbon atoms. Represents a group. Of these, a linear or branched alkyl group having 1 to 30 carbon atoms is preferable.

Examples of the straight-chain or branched-chain R ¹¹² 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, and an n-propyl group. , Isopropyl group, n-butyl group, iso-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group, nonyl group, decyl group, undecyl group, Examples thereof include dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, octadecyl group and the like.

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

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

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

-O- Specific examples of the group represented by (R ¹¹¹ -O) _z -R ^112, for _{example, -O- (C 2 H 4 -O} ) 5 -C 11 H 23, -O- (C 2 _{H 4 -O) 5 -C 12 H} 25, -O- (C 2 H 4 -O) 5 -C 13 H 27, -O- (C 2 H 4 -O) 5 -C 14 H 29, -O _{- (C 2 H 4 -O)} 5 -C 15 H 31, -O- (C 2 H 4 -O) 3 -C 13 H 27, -O- (C 2 H 4 -O) 4 -C 13 H _{27, -O- (C 2 H 4} -O) 6 -C 13 H 27, -O- (C 2 H 4 -O) 7 -C 13 H 27 and the like. Among them _{-O- (C 2 H 4 -O)} 5 -C 11 H 23, -O- (C 2 H 4 -O) 5 -C 13 H 27, -O- (C 2 H 4 -O) 5 _{-C 15 H 31, -O- (C} 2 H 4 -O) 6 -C 13 H 27 are preferable.

The linear or branched alkylene group having 1 to 6 carbon atoms (preferably 1 to 5 carbon atoms) of R ¹⁰⁴ is, for example, the same as the linear or branched alkylene group having 1 to 30 carbon atoms of R ^111. The following groups can be mentioned.

Examples of the compound represented by the above formula (1) include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and the following formulas. The compound represented by the formula (Si363 manufactured by Evonik Degussa) and the like can be mentioned, and the compound represented by the following formula can be preferably used. These may be used alone or in combination of two or more.

  Next, a compound containing the bonding unit A represented by the above formula (2) and the bonding unit B represented by the above formula (3) will be described.

  The compound containing the bonding unit A represented by the above formula (2) and the bonding unit B represented by the above formula (3) is processed more than a polysulfide silane such as bis- (3-triethoxysilylpropyl) tetrasulfide. Increase in viscosity is suppressed. It is considered that this is because the sulfide portion of the bond unit A is a C—S—C bond and is more thermally stable than tetrasulfide or disulfide, and thus the Mooney viscosity does not increase much.

Further, compared to mercaptosilane such as 3-mercaptopropyltrimethoxysilane, reduction in scorch time is suppressed. This is unit B has a mercaptosilane structure, since the -C ₇ H ₁₅ portion of the coupling unit A covers the -SH group of the unit B, less likely to react with polymers, hard scorching occurs It is thought to be because.

  The content of the bonding unit A in the silane coupling agent having the above structure is 30 mol% from the viewpoint that the effect of suppressing the increase in viscosity during processing and the effect of suppressing the reduction of the scorch time can be enhanced. The above is preferable, 50 mol% or more is more preferable, 99 mol% or less is preferable, and 90 mol% or less is more preferable. The content of the binding unit B is preferably 1 mol% or more, more preferably 5 mol% or more, further preferably 10 mol% or more, preferably 70 mol% or less, more preferably 65 mol% or less, 55 mol% % Or less is more preferable. The total content of the bonding units A and B is preferably 95 mol% or more, more preferably 98 mol% or more, and particularly preferably 100 mol%. In addition, the content of the bonding units A and B is an amount including the case where the bonding units A and B are located at the ends of the silane coupling agent. The form of the case where the bonding units A and B are located at the terminal of the silane coupling agent is not particularly limited, as long as it forms a unit corresponding to the formulas (2) and (3) showing the bonding units A and B. .

Examples of the halogen atom of R ²⁰¹ include a chlorine atom, a bromine atom, a fluorine atom and the like.

^Examples of the linear or branched alkyl group having 1 to 30 carbon atoms of R ²⁰¹ 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 and a tert. Examples include -butyl group, pentyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group, nonyl group and decyl group. The alkyl group preferably has 1 to 12 carbon atoms.

^Examples of the linear or branched alkenyl group having 2 to 30 carbon atoms of R ²⁰¹ include vinyl group, 1-propenyl group, 2-propenyl group, 1-butenyl group, 2-butenyl group, 1-pentenyl group, 2- A pentenyl group, a 1-hexenyl group, a 2-hexenyl group, a 1-octenyl group and the like can be mentioned. The alkenyl group preferably has 2 to 12 carbon atoms.

^Examples of the linear or branched alkynyl group having 2 to 30 carbon atoms of R ²⁰¹ include ethynyl group, propynyl group, butynyl group, pentynyl group, hexynyl group, heptynyl group, octynyl group, nonynyl group, decynyl group, undecynyl group. , Dodecynyl group and the like. The alkynyl group preferably has 2 to 12 carbon atoms.

^Examples of the linear or branched alkylene group having 1 to 30 carbon atoms of R ²⁰² include 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, octadecylene group and the like. The alkylene group preferably has 1 to 12 carbon atoms.

^Examples of the linear or branched alkenylene group having 2 to 30 carbon atoms of R ²⁰² include vinylene group, 1-propenylene group, 2-propenylene group, 1-butenylene group, 2-butenylene group, 1-pentenylene group, 2- Examples thereof include a pentenylene group, a 1-hexenylene group, a 2-hexenylene group, a 1-octenylene group and the like. The alkenylene group preferably has 2 to 12 carbon atoms.

Examples of the linear or branched alkynylene group having 2 to 30 carbon atoms of R ²⁰² 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, and an undecynylene group. , Dodecynylene group and the like. The alkynylene group preferably has 2 to 12 carbon atoms.

In the compound containing the bonding unit A represented by the above formula (2) and the bonding unit B represented by the above formula (3), the total of the repeating number (x) of the bonding unit A and the repeating number (y) of the bonding unit B. The repeating number (x + y) of is preferably in the range of 3 to 300. Within this range, the mercaptosilane of the bonding unit B is covered with —C ₇ H ₁₅ of the bonding unit A, so that it is possible to prevent the scorch time from being shortened, and to improve the reactivity with silica and the rubber component. Can be secured.

  As the compound containing the bonding unit A represented by the above formula (2) and the bonding unit B represented by the above formula (3), for example, NXT-Z30, NXT-Z45, NXT-Z60 manufactured by Momentive Co. is used. can do. These may be used alone or in combination of two or more.

  When the silane coupling agent is contained, the content relative to 100 parts by mass of silica is preferably 6 parts by mass or more, more preferably 8 parts by mass or more, still more preferably 10 parts by mass or more. When the content of the silane coupling agent with respect to 100 parts by mass of silica is 6 parts by mass or more, the effect of improving fuel economy and the like tends to be obtained, and the dispersibility of silica in rubber tends to be secured. When the silane coupling agent is contained, the content relative to 100 parts by mass of silica is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, and further preferably 15 parts by mass or less. By setting the content of the silane coupling agent to 100 parts by mass of silica to be 20 parts by mass or less, it is possible to suppress a decrease in rubber strength and wear resistance.

(oil)
Examples of oils include mineral oils such as aromatic oils, process oils and paraffin oils. Among them, it is preferable to use the process oil because it reduces the load on the environment.

  The content of 100 parts by mass of the rubber component when oil is contained is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and further preferably 20 parts by mass or more. By setting the content of oil to 10 parts by mass or more, there is a tendency that the hardness necessary for the tire can be secured and the workability can be ensured. Further, the content of 100 parts by mass of the rubber component when oil is contained is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and further preferably 60 parts by mass or less. When the content of oil is 80 parts by mass or less, workability tends to be ensured.

(Tackifying resin)
Examples of the tackifying resin include cyclopentadiene resin, coumarone resin, petroleum resin (aliphatic petroleum resin, aromatic petroleum resin, alicyclic petroleum resin, etc.), phenolic resin, rosin derivative, etc. Aromatic petroleum resins are preferred.

  Examples of the aromatic petroleum resin include the following aromatic vinyl-based resins and C9-based petroleum resins other than the aromatic vinyl-based resins, and the aromatic vinyl-based resins are preferable.

  In the aromatic vinyl-based resin, examples of the aromatic vinyl monomer (unit) include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene, 2 , 4,6-trimethylstyrene and the like are used, and each may be a homopolymer of each monomer or a copolymer of two or more monomers. Moreover, what modified | denatured these may be sufficient.

  As the aromatic vinyl resin, α-methylstyrene or a styrene homopolymer or a copolymer of α-methylstyrene and styrene is economical, easy to process, and excellent in wet grip performance. A copolymer of α-methylstyrene and styrene is more preferable. As the aromatic vinyl resin, for example, commercially available products such as SYLVARES SA85, SA100, SA120, SA140 manufactured by Arizona Chemical Co., Ltd. and R2336 manufactured by Eastman Chemical Co. are suitably used. As the copolymer of α-methylstyrene and styrene, for example, SYLVATRAXX4401 manufactured by Arizona Chemical Co., Ltd. is preferably used.

  The softening point of the tackifying resin is preferably 40 ° C. or higher, more preferably 60 ° C. or higher. By setting the softening point to 40 ° C. or higher, sufficient grip performance tends to be obtained. The softening point is preferably 120 ° C or lower, more preferably 100 ° C or lower. By setting the softening point to 120 ° C. or lower, sufficient grip performance tends to be obtained. In addition, the softening point of the resin in this specification is the temperature at which the sphere is lowered when the softening point defined in JIS K 6220-1: 2001 is measured with a ring and ball softening point measuring device.

  From the viewpoint of wet grip performance and dry grip performance, the content of the tackifying resin, particularly the aromatic vinyl resin, relative to 100 parts by mass of the rubber component is preferably 1 part by mass or more, and 2 parts by mass or more. More preferably, 3 parts by mass or more is further preferable, and 4 parts by mass or more is particularly preferable. Further, the content of the tackifying resin, particularly the aromatic vinyl-based resin, relative to 100 parts by mass of the rubber component is 50 parts by mass or less from the viewpoint of wear resistance and fuel economy, and from the viewpoint of brittle fracture at low temperature. Is preferred, 40 parts by mass or less is more preferred, 35 parts by mass or less is still more preferred, and 10 parts by mass or less is particularly preferred.

(Processing aid)
Examples of the processing aid include fatty acid metal salt, fatty acid amide, amide ester, silica surfactant, fatty acid ester, mixture of fatty acid metal salt and amide ester, mixture of fatty acid metal salt and fatty acid amide, and the like. These may be used alone or in combination of two or more. Among them, a fatty acid metal salt, an amide ester, a mixture of a fatty acid metal salt and an amide ester or a fatty acid amide is preferable, and a mixture of a fatty acid metal salt and a fatty acid amide is particularly preferable. Specific examples thereof include fatty acid soap-based processing aids such as EF44 and WB16 manufactured by Structol.

  The content of 100 parts by mass of the rubber component when the processing aid is contained is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, from the viewpoint of exerting the effect of improving the processability. In addition, the content of 100 parts by mass of the rubber component when the processing aid is contained is preferably 10 parts by mass or less, and more preferably 8 parts by mass or less, from the viewpoint of wear resistance and breaking strength.

(Anti-aging agent)
The antiaging agent is not particularly limited, but for example, an amine-based, quinoline-based, phenol-based, imidazole-based compound, or an antiaging agent such as metal carbamate may be appropriately selected and blended. These antioxidants may be used alone or in combination of two or more. Among them, amine-based antioxidants are preferable, and N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, N-isopropyl-N'-phenyl-p-phenylenediamine, N, N'- Diphenyl-p-phenylenediamine, N, N'-di-2-naphthyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, N, N'-bis (1-methylheptyl)- p-phenylenediamine, N, N'-bis (1,4-dimethylpentyl) -p-phenylenediamine, N, N'-bis (1-ethyl-3-methylpentyl) -p-phenylenediamine, N-4 -Methyl-2-pentyl-N'-phenyl-p-phenylenediamine, N, N'-diaryl-p-phenylenediamine, hindered diaryl-p-phenylene More preferred are p-phenylenediamine systems such as phenyldiamine, phenylhexyl-p-phenylenediamine, phenyloctyl-p-phenylenediamine, and among these, N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine. Is particularly preferable.

  The content of the anti-aging agent with respect to 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, and more preferably 0.8 parts by mass or more, from the viewpoint of exerting an anti-aging effect. In addition, the content with respect to 100 parts by mass of the rubber component when the antioxidant is contained is preferably 2.0 parts by mass or less and 1.5 parts by mass or less from the viewpoint of preventing browning of the rubber derived from the antioxidant. Is more preferable.

(Softener)
Examples of the softening agent include liquid polymers and low temperature plasticizers. The plasticizer component may be used alone or in combination of two or more kinds. Above all, it is preferable to use the liquid polymer because the abrasion resistance and the grip performance can be improved in a well-balanced manner.

  Examples of the liquid polymer include liquid SBR, liquid BR, liquid IR, liquid SIR, and the like. Above all, it is preferable to use liquid SBR because the durability and the grip performance can be improved in a well-balanced manner.

  Examples of the low temperature plasticizer include liquid components such as dioctyl phthalate (DOP), dibutyl phthalate (DBP), tris (2 ethylhexyl) phosphate (TOP), and bis (2 ethylhexyl) sebacate (DOS).

  The content of the softening agent with respect to 100 parts by mass of the rubber component is preferably 15 to 250 parts by mass, and more preferably 20 to 200 parts by mass, because the effect as a softening agent is sufficiently obtained. More preferable.

  In addition, as the wax, zinc oxide, and stearic acid, those conventionally used in the tire industry can be used.

(Vulcanizing agent)
The vulcanizing agent is not particularly limited, and those generally used in the tire industry can be used, but those containing a sulfur atom are preferable, for example, powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, Insoluble sulfur etc. are mentioned.

  The content of the vulcanizing agent with respect to 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 0.8 part by mass or more, and further preferably 1.0 part by mass or more. The content of the vulcanizing agent with respect to 100 parts by mass of the rubber component is 3.0 parts by mass or less, preferably 2.5 parts by mass or less, and more preferably 2.0 parts by mass or less.

(Vulcanization accelerator)
The vulcanization accelerator is not particularly limited, for example, sulfenamide-based, thiazole-based, thiuram-based, thiourea-based, guanidine-based, dithiocarbamic acid-based, aldehyde-amine-based or aldehyde-ammonia-based, imidazoline System, xanthate-based vulcanization accelerators are preferable, and among them, sulfenamide-based vulcanization accelerators and thiuram-based vulcanization accelerators are preferable from the viewpoint that desired effects can be obtained more suitably, and these two types are used in combination. More preferably.

  Examples of the sulfenamide vulcanization accelerator include CBS (N-cyclohexyl-2-benzothiazylsulfenamide), TBBS (Nt-butyl-2-benzothiazylsulfenamide), N-oxyethylene- 2-benzothiazyl sulfenamide, N, N'-diisopropyl-2-benzothiazyl sulfenamide, N, N-dicyclohexyl-2-benzothiazyl sulfenamide and the like can be mentioned. Examples of the thiazole vulcanization accelerator include 2-mercaptobenzothiazole and dibenzothiazolyl disulfide. Examples of thiuram-based vulcanization accelerators include tetramethylthiuram monosulfide, tetramethylthiuram disulfide, and tetrabenzylthiuram disulfide (TBzTD). Examples of the guanidine-based vulcanization accelerator include diphenylguanidine (DPG), diortotolylguanidine, orthotolylbiguanidine, and the like. These may be used alone or in combination of two or more. Among them, the combination of CBS and TBzTD is particularly preferable in that the desired effect can be obtained more suitably.

  When the vulcanization accelerator is contained, the content is preferably 1 part by mass or more and more preferably 2 parts by mass or more with respect to 100 parts by mass of the rubber component. The content of the vulcanization accelerator with respect to 100 parts by mass of the rubber component is preferably 8 parts by mass or less, more preferably 7 parts by mass or less, and further preferably 6 parts by mass or less. By setting the content of the vulcanization accelerator within the above range, breaking strength and elongation tend to be secured.

(Method for producing rubber composition for tread)
The method for producing the rubber composition for tread is not particularly limited, and a known method can be used. For example, using a rubber kneading device such as an open roll, a Banbury mixer, a kneader, or a closed kneader, the components other than the vulcanizing agent and the vulcanization accelerator are kneaded (kneading step 1) and then kneaded. It can be produced by a method such as adding a vulcanizing agent and a vulcanization accelerator and further kneading (kneading step 2) to obtain an unvulcanized rubber composition for tread, and then vulcanizing (vulcanization step).

  For example, in the kneading step 1, after kneading at a discharge temperature of 150 to 160 ° C. for 1 to 10 minutes, in the kneading step 2, a vulcanizing agent and a vulcanization accelerator can be added and kneaded using an open roll or the like. . In the vulcanization step, for example, vulcanization can be performed at 150 to 170 ° C. for 10 to 35 minutes.

(tire)
A tire according to one embodiment comprises a tread composed of the rubber composition for a tread, a tire for a passenger car, a high-performance tire for a passenger car, a tire for a heavy load such as a truck or a bus, a tire for a motorcycle, a competition. It can be used for general tires such as tires for use. The high performance tire in the present specification is a tire having particularly excellent grip performance, and is a concept including a competition tire used for a competition vehicle.

(Tire manufacturing method)
A tire provided with a tread composed of the rubber composition for tread can be produced by a usual method using the rubber composition for tread. That is, an unvulcanized rubber composition in which each of the above components is blended as necessary with respect to the rubber component is extruded in accordance with the shape of the tread, and is bonded together with other tire members on a tire molding machine. A tire can be manufactured by forming an unvulcanized tire by molding by the method of 1, and heating and pressurizing the unvulcanized tire in a vulcanizer.

  Hereinafter, the present invention will be described based on examples, but the present invention is not limited to these examples.

Hereinafter, various chemicals used in Examples and Comparative Examples will be summarized.
SBR1: TRINSEO SLR6430 (S-SBR, styrene content: 40 mass%, vinyl bond content: 18 mol%, Mw: 146,000, Tg: -39 ° C., oil content: 37.5 parts by weight based on 100 parts by weight of rubber component) (Including oil products)
SBR2: Modified SBR synthesized in Production Example 1 described later (styrene content: 38 mass%, vinyl bond content: 39 mol%, Mw: 800,000, Tg: -25 ° C)
SBR3: Modified solution-polymerized SBR produced in Production Example 2 described later (styrene content: 42 mass%, vinyl bond content: 36 mol%, Mw: 800,000, Tg: -21 ° C)
SBR4: Modified solution polymerization SBR produced in Production Example 3 described later (styrene content: 30 mass%, vinyl bond content: 52 mol%, Mw: 250,000, Tg: -23 ° C)
BR1: Modified BR produced in Production Example 4 described later (vinyl bond amount: 12 mol%, cis 1,4-content: 38%, Mw: 500,000)
BR2: UBEPOL BR (registered trademark) 150B manufactured by Ube Industries, Ltd. (vinyl bond content: 1.5 mol%, cis 1,4-content 97%, Mw: 440,000)
Carbon black: Show black N220 (N ₂ SA: 111 m ² / g) manufactured by Cabot Japan Co., Ltd.
Silica: Evonik Degussa Corporation of ^{ultra-Cyr-9000GR (BET: 240m 2 / g} , CTAB: 200m 2 /g,pH:6.9)
Silane coupling agent: NXT-Z45 manufactured by Momentive Co. (copolymer of bonding unit A and bonding unit B (bonding unit A: 55 mol%, bonding unit B: 45 mol%))
Aluminum hydroxide: H-43 manufactured by Showa Denko KK (N ₂ SA: 6.7 m ² / g, average primary particle diameter: 800 nm)
Oil: VivaTec 400 (TDAE oil, Tg: -58 ° C) manufactured by H & R Co., Ltd.
Tackifying resin: Sylvares SA85 (α-methylstyrene / styrene resin, softening point: 85 ° C.) manufactured by Arizona Chemical Co., Ltd.
Wax: Ozoace 0355 (paraffin type) manufactured by Nippon Seiro Co., Ltd.
Processing aid: Schill & Seilacher tractol WB16 (mixture of fatty acid calcium salt, fatty acid monoethanolamide and ester of fatty acid monoethanolamide).
Anti-aging agent: Antigen 6C (N- (1,3-dimethylbutyl) -N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd.
Zinc oxide: Zinc Hua No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Beads manufactured by NOF Corporation Stem acid Tsubaki Sulfur: HK-200-5 (5% oil-containing powder manufactured by Hosoi Chemical Co., Ltd.) sulfur)
・ Vulcanization accelerator 1: Nocceller CZ (N-cyclohexyl-2-benzothiazolylsulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
・ Vulcanization accelerator 2: Sanshinra TBZTD (tetrabenzyl thiuram disulfide (TBzTD)) manufactured by Sanshin Chemical Industry Co., Ltd.

Production Example 1: Synthesis of SBR2 Two autoclaves each having an inner volume of 10 liters, an inlet at the bottom and an outlet at the head, a stirrer and a jacket were connected as reactors in series, and butadiene, styrene, and cyclohexane were each added. Mix in the given ratio. This mixed solution was mixed with n-butyllithium in a static mixer in order to remove impurities through a dehydration column packed with activated alumina, and then continuously supplied from the bottom of the first reactor. 2,2-bis (2-oxolanyl) propane as a polar substance and n-butyllithium as a polymerization initiator were continuously supplied at a predetermined rate from the bottom of the first reactor, and the temperature inside the reactor was adjusted to 95. Hold at ℃. The polymer solution was continuously withdrawn from the reactor head and fed to the second reactor. The temperature of the second reactor was kept at 95 ° C., and a mixture of tetraglycidyl-1,3-bisaminomethylcyclohexane (monomer) as a modifier and its oligomer component (hereinafter referred to as “modifier A”). .) Was continuously added as a 1000-fold diluted solution of cyclohexane at a predetermined rate to carry out a denaturing reaction. This polymer solution was continuously withdrawn from the reactor, an antioxidant was continuously added with a static mixer, and 25 parts by mass of Japan Energy extender NC140 was added to 100 parts by mass of the polymer. After mixing by mixing, the solvent was removed to obtain SBR2.

Production Example 2: Synthesis of SBR3 A nitrogen-substituted autoclave reactor was charged with cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene. After adjusting the temperature of the contents of the reactor to 20 ° C., n-butyllithium was added to initiate polymerization. Polymerization under adiabatic conditions reached a maximum temperature of 85 ° C. When the polymerization conversion rate reached 99%, 1,3-butadiene was added, and after polymerization for 5 minutes, N, N-bis (trimethylsilyl) -3-aminopropyltrimethoxysilane was added as a modifier. The reaction was carried out. After the completion of the polymerization reaction, 2,6-di-tert-butyl-p-cresol was added. Next, 10 parts by mass of the extending oil was added to 100 parts by mass of the polymer, the solvent was removed by steam stripping, and the product was dried by a hot roll whose temperature was adjusted to 110 ° C. to obtain SBR3.

Production Example 3: Synthesis of SBR4 A nitrogen-substituted autoclave reactor was charged with cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene. After adjusting the temperature of the contents of the reactor to 20 ° C., n-butyllithium was added to initiate polymerization. Polymerization under adiabatic conditions reached a maximum temperature of 85 ° C. When the polymerization conversion rate reached 99%, 1,3-butadiene was added, and after polymerization for 5 minutes, N, N-bis (trimethylsilyl) -3-aminopropyltrimethoxysilane was added as a modifier. The reaction was carried out. After the completion of the polymerization reaction, 2,6-di-tert-butyl-p-cresol was added. Then, the solvent was removed by steam stripping, and dried by a hot roll whose temperature was adjusted to 110 ° C. to obtain SBR4.

Production Example 4: Synthesis of BR1 <Preparation of terminal modifying agent B>
Under a nitrogen atmosphere, 23.6 g of 3- (N, N-dimethylamino) propyltrimethoxysilane (manufactured by Asmax Co., Ltd.) was placed in a 100 mL volumetric flask, and anhydrous hexane (manufactured by Kanto Kagaku Co., Ltd.) was further added to make a total amount. To 100 mL to prepare denaturant B.

<Preparation of modified BR>
18 L of n-hexane, 2000 g of butadiene, and 2 mmol of tetramethylethylenediamine (TMEDA) were added to a 30 L pressure-resistant container that had been sufficiently replaced with nitrogen, and the temperature was raised to 60 ° C. Next, after adding 10.3 mL of butyl lithium, the temperature was raised to 50 ° C. and the mixture was stirred for 3 hours. Next, 11.5 mL of denaturant B was added and stirred for 30 minutes. After 15 mL of methanol and 0.1 g of 2,6-tert-butyl-p-cresol were added to the reaction solution, the reaction solution was placed in a stainless steel container containing 18 L of methanol to collect aggregates. The obtained aggregate was dried under reduced pressure for 24 hours to obtain BR1.

Examples 1-13 and Comparative Examples 1-7
According to the formulation shown in Table 1 or 2, using a 1.7 L closed Banbury mixer, the chemicals other than sulfur and the vulcanization accelerator are kneaded for 1 to 10 minutes until the discharge temperature reaches 150 to 160 ° C, A kneaded product was obtained. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product using a biaxial open roll, and the mixture was kneaded for 4 minutes to 105 ° C. to obtain an unvulcanized rubber composition. The unvulcanized rubber composition obtained was press-vulcanized at 170 ° C. for 12 minutes to prepare a test rubber composition. In addition, in Tables 1 and 2, when the rubber component is an oil-extended rubber, the amount of the rubber component excluding the oil component is described as the compounding amount of the rubber component such as “SBR1”, and the oil component is separately compounded. The total amount is shown as the amount of "oil" added.

  Further, the unvulcanized rubber composition is extruded into the shape of a tire tread by an extruder equipped with a die having a predetermined shape, and is bonded together with other tire members to form an unvulcanized tire under conditions of 170 ° C. Test tires (size: 195 / 65R15) were made by press vulcanizing under 12 minutes.

  The following evaluations were performed on the vulcanized rubber compositions and test tires obtained in each of the examples and comparative examples. The results are shown in Table 1 or 2.

<Tan δ (0 ° C.) and tan δ peak temperature>
Using a spectrometer manufactured by Ueshima Seisakusho Co., Ltd., a vulcanized rubber composition was prepared in a temperature range of dynamic strain amplitude 0.5%, frequency 10 Hz, temperature rising rate 2 ° C./min, and measurement temperature −80 ° C. to 80 ° C. tan δ was measured, and the temperature at which tan δ peaked was defined as the tan δ peak temperature.

<Wet grip performance>
Wet grip performance was evaluated using a flat belt abrasion tester (FR5010 type) manufactured by Kamijima Seisakusho. A cylindrical rubber test piece having a width of 20 mm and a diameter of 100 mm of each vulcanized rubber composition was used as a sample, and the slip ratio of the sample to the road surface was 0 to 70 under the conditions of a speed of 20 km / hour, a load of 4 kgf and a road surface temperature of 20 ° C. %, And the maximum value of the friction coefficient detected at that time was read. Then, the measurement result was displayed as an index by the following calculation formula. The larger the index, the better the wet grip performance.
(Wet grip performance index)
= (Maximum value of friction coefficient of each composition) / (maximum value of friction coefficient of Comparative Example 1) x 100

<Abrasion resistance>
The test tire was mounted on a domestic FR vehicle with a displacement of 2000 cc, and the vehicle was run on a dry asphalt test course. The groove depth of the tire tread portion after a mileage of 10,000 km was measured, the mileage when the tire groove depth decreased by 1 mm was calculated, and it was expressed as an index by the following formula. The larger the index, the better the wear resistance.
(Abrasion resistance index) = (mileage of each composition) / (mileage of Comparative Example 1) × 100

<Low fuel consumption index>
A strip-shaped test piece having a width of 4 mm, a length of 50 mm and a thickness of 2 mm was punched out from the sheet-shaped vulcanized rubber composition and used for the test. The loss tangent (tan δ) of the vulcanized rubber sheet was measured at a dynamic strain amplitude of 1%, a frequency of 10 Hz, a temperature of 50 ° C. and a temperature of 22.5 ° C. using a spectrometer manufactured by Ueshima Seisakusho Co., Ltd., and the reciprocal value of tan δ. Was displayed as an index (fuel efficiency index) with Comparative Example 1 as 100. The results obtained at 50 ° C. and 22.5 ° C. were designated as low fuel consumption indexes A and B, respectively. The higher the value, the lower the rolling resistance and the better the fuel economy.
(Fuel efficiency index) = (tan δ of Comparative Example 1) / (tan δ of each blend) × 100

  From the results of Tables 1 and 2, 100 parts by mass of a rubber component containing 60 to 80% by mass of SBR 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 are contained. However, in Examples 1 to 13 in which tan δ at a dynamic strain amplitude of 0.5% at 0 ° C. is 0.60 or less and the peak temperature of tan δ is -17 ° C. or less, a comparative example in which the content of BR is small. 1 and 2, Comparative Example 5 having a high BR content, Comparative Example 6 having a low silica content, Comparative Example 7 containing no carbon black, and tan δ (0 ° C.) ≦ 0.60 and tan δ in the same formulation. Compared with Comparative Examples 3 and 4 in which at least one of the peak temperatures ≦ −17 ° C. is not satisfied, the overall performance such as wet grip performance, wear resistance and fuel economy is improved. Hunt.

Claims (5)

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,
It contains 1 to 40 parts by mass of carbon black and 50 to 150 parts by mass of silica, has a tan δ at 0 ° C. of 0.5% dynamic strain amplitude of 0.60 or less, and has a tan δ peak temperature of -17 ° C. The following rubber composition for treads. The rubber composition for a tread according to claim 1, which contains aluminum hydroxide. The rubber composition for a tread according to claim 1 or 2, which contains 10 to 80 parts by mass of oil with respect to 100 parts by mass of the rubber component. A compound represented by the following formula (1) and / or a compound containing a binding unit A represented by the following formula (2) and a binding unit B represented by the following formula (3), which has a mercapto group. The rubber composition for a tread according to claim 1, further comprising a silane coupling agent.

(In the formula, R ^{101 to} R ¹⁰³ are a linear or branched alkyl group having 1 to 12 carbon atoms, a linear or branched alkoxy group having 1 to 12 carbon atoms, or —O— (R ¹¹¹ —O ) _Z- R ¹¹² (z R ^{111 s} represent a linear or branched divalent hydrocarbon group having 1 to 30 carbon atoms. The Z R ^{111 s} may be the same or different. R ¹¹² is a linear or branched alkyl group having 1 to 30 carbon atoms, a linear or branched alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or a C 7 to 30 carbon atom. Represents an aralkyl group, z represents an integer of 1 to 30), R ^{101 to} R ¹⁰³ may be the same or different, and R ¹⁰⁴ represents a linear or branched chain. It represents an alkylene group having 1 to 6 carbon atoms.)

(In the formula, x is an integer of 0 or more and y is an integer of 1 or more. R ²⁰¹ is a hydrogen atom, a halogen atom, a linear or branched alkyl group having 1 to 30 carbon atoms, a linear or branched chain) alkenyl group having 2 to 30 carbon atoms, .R ²⁰² representing those straight or branched chain alkynyl group having 2 to 30 carbon atoms or a terminal hydrogen atom of the alkyl group is substituted with a hydroxyl group or a carboxyl group Represents a linear or branched alkylene group having 1 to 30 carbon atoms, a linear or branched alkenylene group having 2 to 30 carbon atoms, or a linear or branched alkynylene group having 2 to 30 carbon atoms. R ²⁰¹ and R ²⁰² may form a ring structure.) A tire comprising a tread composed of the rubber composition for a tread according to any one of claims 1 to 4.