Rubber composition for tires and tires

Abstract

To provide a tire rubber composition that achieves overall improvement in low fuel consumption performance as well as the performance of inhibiting the decrease of wet grip performance with time, and provide a tire.SOLUTION: A tire rubber composition contains a filler including silica, a silane coupling agent, and a liquid polymer and / or resin component. The silane coupling agent contains an organic silicon compound including alkoxysilyl groups and sulfur atoms, where, carbon atoms connecting the alkoxysilyl groups and sulfur atoms are 6 or more in number.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] As methods for achieving a balanced improvement in fuel economy and wet grip performance, a method using silica as a filler, a method incorporating a silane coupling agent, a method using a resin or a liquid polymer as a plasticizer, and the like have been proposed. However, further improvements, particularly improvements in preventing the deterioration of fuel economy and wet grip performance over time, are desired. Summary of the Invention [Problem to be solved by the invention]

[0003] An object of the present invention is to provide a rubber composition for tires and a tire which solves the above problems and improves the overall performance of fuel economy and suppression of deterioration in wet grip performance over time. [Means for solving the problem]

[0004] The present invention relates to a rubber composition for tires, which comprises a filler containing silica, a silane coupling agent, and a liquid polymer and / or resin component, wherein the silane coupling agent contains an organosilicon compound that contains an alkoxysilyl group and a sulfur atom and in which the number of carbon atoms connecting the alkoxysilyl group and the sulfur atom is 6 or more.

[0005] It is preferable that the content of the isoprene rubber is 15 to 40 mass%, the content of the styrene-butadiene rubber is 30 to 70 mass%, and the content of the butadiene rubber is 5 to 20 mass%, based on 100 mass% of the rubber component.

[0006] In the rubber composition for tires, it is preferable that the content of silica, and the total content of the liquid polymer and the resin component per 100 parts by mass of the rubber component satisfy the following formula: Silica content / total content of liquid polymer and resin components≦5.0

[0007] In the rubber composition for tires, it is preferable that the content of oil, the content of the liquid polymer and the total content of the resin component per 100 parts by mass of the rubber component satisfy the following formula: Oil content / total content of liquid polymer and resin components≦3.0

[0008] In the rubber composition for tires, it is preferable that the content of silica, and the total content of the liquid polymer and the resin component per 100 parts by mass of the rubber component satisfy the following formula: Silica content - total content of liquid polymer and resin components ≦ 45

[0009] In the rubber composition for tires, it is preferable that the content of oil, the content of the liquid polymer and the total content of the resin component per 100 parts by mass of the rubber component satisfy the following formula: Oil content - total content of liquid polymer and resin components ≦25

[0010] The rubber composition for tires preferably has a silica content of 50% by mass or more in 100% by mass of the filler.

[0011] Nitrogen adsorption specific surface area 160m 2 It is preferable that the silica content is at least 1 / g.

[0012] The amount of carbon black per 100 parts by mass of the rubber component is preferably 3 to 30 parts by mass.

[0013] The total content of the liquid polymer and the resin component per 100 parts by mass of the rubber component is preferably 15 parts by mass or more.

[0014] The present invention also relates to a tire using the above rubber composition in the tread. Effect of the Invention

[0015] According to the present invention, a rubber composition for tires includes a filler containing silica, a silane coupling agent, and a liquid polymer and / or resin component, and the silane coupling agent includes an organosilicon compound that contains an alkoxysilyl group and a sulfur atom and has 6 or more carbon atoms connecting the alkoxysilyl group and the sulfur atom, so that the overall performance of fuel economy and inhibition of deterioration of wet grip performance over time can be improved. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The present invention provides a rubber composition for tires, which comprises a filler containing silica, a silane coupling agent, and a liquid polymer and / or resin component, the silane coupling agent comprising an organosilicon compound containing an alkoxysilyl group and a sulfur atom, and the number of carbon atoms connecting the alkoxysilyl group and the sulfur atom being 6 or more. The rubber composition can improve the overall performance of fuel economy and suppression of deterioration of wet grip performance over time.

[0017] The reason why the above-mentioned effects are obtained is not entirely clear, but it is presumed that they are due to the following mechanism. Silica can be dispersed in each rubber phase by introducing an organic silicon compound containing an alkoxysilyl group and a sulfur atom as a silane coupling agent, and the number of carbon atoms connecting the alkoxysilyl group and the sulfur atom is 6 or more, i.e., a long-chain silane coupling agent. Furthermore, by blending a liquid polymer and / or a resin component, an interaction with the silica particles hydrophobized by the long-chain silane coupling agent occurs. Therefore, regardless of the compatibility of the resin component and the liquid polymer, it is possible to uniformly disperse the resin and / or liquid polymer at the same time as silica is dispersed in the rubber phase. Therefore, the uniform dispersion of silica reduces heat generation in the entire rubber and provides a good trackability to the road surface, and improves gripping properties due to adhesion on the rubber surface, and prevents phase separation over time, thereby suppressing the deterioration of wet grip performance over time. Therefore, it is presumed that the above-mentioned action and function significantly improves the overall performance of fuel efficiency and suppression of deterioration of wet grip performance over time.

[0018] (Rubber component) As the rubber component usable in the rubber composition, for example, diene rubber can be used. Examples of diene rubber include isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), styrene isoprene butadiene rubber (SIBR), ethylene propylene diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). In addition, butyl rubber and fluororubber can be used. These may be used alone or in combination of two or more. Among them, isoprene rubber, SBR, and BR are preferred from the viewpoint of the overall performance of fuel efficiency and suppression of deterioration of wet grip performance over time. When isoprene rubber, SBR, and BR are included as the rubber component, the dispersion of silica is usually non-uniform in the three components, but in the present invention, the dispersion of silica is increased, so that it is considered that a greater effect can be obtained in the three-component system, and as a result, it is presumed that the overall performance of fuel efficiency and suppression of deterioration of wet grip performance over time is significantly improved.

[0019] The diene rubber may be a non-modified diene rubber or a modified diene rubber. The modified diene rubber may be any diene rubber having a functional group that interacts with a filler such as silica. Examples of the modified diene rubber include terminal-modified diene rubber (terminal-modified diene rubber having the functional group at the terminal) in which at least one terminal of the diene rubber has been modified with a compound (modifier) ​​having the functional group, main-chain modified diene rubber having the functional group in the main chain, main-chain terminal-modified diene rubber having the functional group in the main chain and at least one terminal (for example, main-chain terminal-modified diene rubber having the functional group in the main chain and at least one terminal modified with the modifier), and terminal-modified diene rubber 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.

[0020] 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.

[0021] Examples of isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. Examples of NR include SIR20, RSS♯3, TSR20, and other rubber industry-standard rubbers. Examples of IR include IR2200 and other rubber industry-standard rubbers. Examples of modified NR include deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), and other rubbers. Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more.

[0022] The content of the isoprene-based rubber in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more. The upper limit is preferably 70% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less. By keeping the content within the above range, there is a tendency that the overall performance of fuel efficiency and suppression of deterioration in wet grip performance over time is improved.

[0023] 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.

[0024] The styrene content of the SBR is preferably 5.0% by mass or more, more preferably 8.0% by mass or more, and even more preferably 10.0% by mass or more. The styrene content is preferably 35.0% by mass or less, more preferably 30.0% by mass or less, even more preferably 28.0% by mass or less, and particularly preferably 27.0% by mass or less. By keeping it within the above range, there is a tendency that the overall performance of low fuel consumption and suppression of deterioration of wet grip performance over time is improved. In this specification, the styrene content is 1 It can be measured by H-NMR measurement.

[0025] The vinyl bond content of the SBR is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 45% by mass or more, and particularly preferably 50% by mass or more. The vinyl bond content is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 65% ​​by mass or less. By keeping it within the above range, there is a tendency that the overall performance of fuel efficiency and suppression of deterioration of wet grip performance over time is improved. In this specification, the vinyl bond amount (1,2-bonded butadiene unit amount) can be measured by infrared absorption spectroscopy.

[0026] The SBR may be unmodified or modified. Modified SBR includes modified SBR into which functional groups similar to those of modified diene rubbers have been introduced. Hydrogenated styrene-butadiene copolymers (hydrogenated SBR) can also be used as SBR.

[0027] 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.

[0028] The content of SBR in 100% by mass of the rubber component is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, and particularly preferably 50% by mass or more. The upper limit is preferably 95% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. By keeping the content within the above range, there is a tendency that the overall performance of fuel economy and suppression of deterioration of wet grip performance over time is improved.

[0029] The BR is not particularly limited, and for example, high cis BR with a high cis content, BR containing syndiotactic polybutadiene crystals, BR synthesized using a rare earth catalyst (rare earth BR), etc. can be used. These may be used alone or in combination of two or more. In particular, the BR preferably contains high cis BR with a cis content of 90% by mass or more. The cis content is more preferably 95% by mass or more. The cis content can be measured by infrared absorption spectroscopy.

[0030] The BR may be unmodified or modified. The modified BR may be modified BR having the same functional group as the modified diene rubber. The BR may be a hydrogenated butadiene polymer (hydrogenated BR).

[0031] As the BR, for example, products from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Zeon Corporation, etc. can be used.

[0032] The BR content in 100% by mass of the rubber component is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more. The upper limit is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less. By keeping the BR content within the above range, there is a tendency that the overall performance of fuel economy and suppression of deterioration in wet grip performance over time is improved.

[0033] (silica) Silica is blended as a filler in the rubber composition. Usable silica includes dry process silica (anhydrous silica) and wet process silica (hydrated silica). Among them, wet process silica is preferred because it has a large number of silanol groups. Commercially available products include those from Degussa, Rhodia, Tosoh Silica, Solvay Japan, and Tokuyama. These may be used alone or in combination of two or more.

[0034] The nitrogen adsorption specific surface area (N2SA) of the silica is preferably 50 m 2 / g or more, more preferably 150m 2 / g or more, more preferably 160m 2 / g or more, particularly preferably 180m 2 / g or more, 210m 2 The upper limit of the N2SA of the silica is not particularly limited, but is preferably 600 m 2 / g or less, more preferably 350m 2 / g or less, more preferably 260m 2 By keeping the value within the above range, there is a tendency for high-speed cornering performance on wet road surfaces to improve. The N2SA of silica is a value measured by the BET method in accordance with ASTM D3037-93.

[0035] In the rubber composition, the content of silica (total amount of silica) is preferably 5 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 40 parts by mass or more, and particularly preferably 50 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, even more preferably 100 parts by mass or less, and particularly preferably 80 parts by mass or less. By keeping it within the above range, there is a tendency that the overall performance of low fuel consumption and suppression of deterioration of wet grip performance over time is improved. The content of the fine silica particles is also preferably within the same range.

[0036] (Silane coupling agent) The silane coupling agent used in the rubber composition contains an organosilicon compound that contains an alkoxysilyl group and a sulfur atom, and the number of carbon atoms connecting the alkoxysilyl group and the sulfur atom is 6 or more. Such organosilicon compounds may be used alone or in combination of two or more. Among the organosilicon compounds, an organosilicon compound represented by the following average composition formula (I) is preferred. [ka] (In the formula, x represents the average number of sulfur atoms and is 3.5 or more. m represents an integer of 6 or more. 1 ~R 6 are the same or different and each represents an alkyl group or an alkoxy group having 1 to 6 carbon atoms; R 1 ~R 3 At least one of and R 4 ~R 6 At least one of R is the alkoxy group. 1 ~R 6 may be a ring structure formed by bonding the alkyl group or the alkoxy group.

[0037] x represents the average number of sulfur atoms in the organosilicon compound, and is preferably 3.5 or more and 12 or less. Here, the average number of sulfur atoms and the number of silicon atoms are values ​​calculated from the molecular weights of the sulfur and silicon atoms in the composition measured by fluorescent X-rays.

[0038] m represents an integer of 6 or more, and preferably 6 or more and 14 or less.

[0039] Alkyl group (R 1 ~R 6 The number of carbon atoms in the alkyl group is preferably 1 to 5. The alkyl group may be linear, branched, or cyclic. Specific examples 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, and a tert-butyl group.

[0040] Alkoxy group (R 1 ~R6 ) preferably has 1 to 5 carbon atoms. The hydrocarbon group in the alkoxy group may be linear, branched, or cyclic. Specific examples include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, and an n-butoxy group.

[0041] R 1 ~R 3 At least one of and R 4 ~R 6 At least one of R is an alkoxy group having 1 to 6 carbon atoms, and preferably R 1 ~R 3 , R 4 ~R 6 At least two of each of these are alkoxy groups having 1 to 6 carbon atoms.

[0042] In addition, R 1 ~R 6 may be a ring structure formed by bonding an alkyl group or an alkoxy group having 1 to 6 carbon atoms. For example, (i) R 1 is an ethoxy group, R 2 (ii) R 1 is an ethyl group, R 2 When R forms a ring structure with a methyl group bonded thereto, 1 and R 2 Examples of structures in which divalent groups such as "-O-C2H4-CH2-" and "-C2H4-CH2-" are formed and bonded to Si include

[0043] The organosilicon compound can be prepared, for example, by the manufacturing method described in JP 2018-65954 A. Specifically, the organosilicon compound can be produced by reacting a halogen-containing organosilicon compound of formula (I-1) described in JP 2018-65954 A, anhydrous sodium sulfide represented by Na2S, and sulfur as necessary. When carrying out the above reaction, the addition of sulfur is optional for adjusting the sulfide chain, and may be determined from the blending amount of the compound of the average composition formula (I-1), anhydrous sodium sulfide, and sulfur as necessary, so as to obtain a compound of the desired average composition formula (I). For example, if you want to make the x of the compound of the average composition formula (I) 3.5, you can react 1.0 mol of anhydrous sodium sulfide, 2.5 mol of sulfur, and 2.0 mol of the compound of formula (I-1).

[0044] And, when an organic silicon compound containing an alkoxysilyl group and a sulfur atom and having 6 or more carbon atoms connecting the alkoxysilyl group and the sulfur atom is used as a silane coupling agent, that is, a long-chain silane coupling agent, the alkoxy group in the compound reacts with the hydroxyl group on the silica surface to hydrophobize the silica surface, and the effect of hydrophobization is greater than that of conventional silane coupling agents due to the long carbon chain of the compound, so that the dispersibility of silica is significantly improved and silica can be dispersed in each rubber phase. Furthermore, by blending a liquid polymer and / or a resin component, an interaction with the silica particles hydrophobized by the long-chain silane coupling agent occurs, and the resin and / or liquid polymer can be uniformly dispersed at the same time as the silica is dispersed in the rubber phase, regardless of the compatibility of the resin component and the liquid polymer. Therefore, the heat generation of the entire rubber is reduced and the rubber can follow the road surface due to the uniform dispersion of silica, and the gripping property is improved due to adhesion on the rubber surface, and phase separation over time is also prevented, so that the deterioration of wet grip performance over time can be suppressed. Therefore, by using such a long-chain silane coupling agent, it is possible to improve the overall performance of fuel economy and suppression of deterioration of wet grip performance over time.

[0045] In the rubber composition, the content of the organosilicon compound is preferably 0.1 parts by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more, based on 100 parts by mass of silica. The upper limit of the content is preferably 50 parts by mass, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. By keeping it within the above range, there is a tendency that the overall performance of low fuel consumption and suppression of deterioration of wet grip performance over time is improved. In addition, the content of the organosilicon compound represented by the average composition formula (I) is also preferably in the same range.

[0046] The rubber composition may contain a silane coupling agent other than the organosilicon compound that contains an alkoxysilyl group and a sulfur atom and has 6 or more carbon atoms connecting the alkoxysilyl group and the sulfur atom. 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-dimethylthiocarbamate, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide ...3-trimethoxysilylpropyl-N,N-dimethylthiocarbamate, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, bis(2-trimethoxysilylpropyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysil Examples of such silanes include sulfide-based silanes such as rubamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based silanes such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and Momentive's NXT and NXT-Z; vinyl-based silanes such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silanes such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based silanes such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silanes such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based silanes such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Commercially available products include those manufactured by Degussa, Momentive, Shin-Etsu Silicones, Tokyo Chemical Industry, Azumax, and Dow Corning Toray Co., Ltd. These may be used alone or in combination of two or more.

[0047] In the rubber composition, the content of the silane coupling agent (the total amount of the organic silicon compound and other silane coupling agents) is preferably 0.1 parts by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more, based on 100 parts by mass of silica. The upper limit of the content is preferably 50 parts by mass, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. By keeping it within the above range, the overall performance of low fuel consumption and suppression of deterioration of wet grip performance over time tends to improve.

[0048] (Other filling materials) The filler other than silica is not particularly limited, and materials known in the rubber field can be used, such as inorganic fillers such as carbon black, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica. Of these, carbon black and aluminum hydroxide are preferred.

[0049] In the rubber composition, the content of the filler (total content of the fillers) is preferably 5 parts by mass or more, more preferably 30 parts by mass or more, even more preferably 40 parts by mass or more, and particularly preferably 50 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, even more preferably 120 parts by mass or less, and particularly preferably 100 parts by mass or less. By keeping the content within the above range, the overall performance of low fuel consumption and suppression of deterioration of wet grip performance over time tends to be improved.

[0050] In the rubber composition, the silica content in 100% by mass of the filler is preferably 50% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more, from the viewpoint of the overall performance of fuel economy and suppression of deterioration of wet grip performance over time. The upper limit is not particularly limited, but is preferably 98% by mass or less, and more preferably 95% by mass or less.

[0051] The carbon black that can be used in the rubber composition is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shinnikka Carbon Co., Ltd., Columbia Carbon Co., Ltd., and the like. These may be used alone or in combination of two or more kinds.

[0052] The nitrogen adsorption specific surface area (N2SA) of carbon black is 50m 2 / g or more is preferable, and 70m 2 / g or more is more preferable, and 90m 2 / g or more is more preferable. 2 / g or less is preferable, and 150m 2 / g or less is more preferable, and 130m 2 By setting the value within the above range, there is a tendency that the overall performance of fuel economy and suppression of deterioration in wet grip performance over time is improved. The nitrogen adsorption specific surface area of ​​carbon black can be determined in accordance with JIS K6217-2:2001.

[0053] In the rubber composition, the content of carbon black is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less. By keeping the content within the above range, the overall performance of fuel efficiency and suppression of deterioration of wet grip performance over time tends to be improved.

[0054] The aluminum hydroxide is not particularly limited, and any aluminum hydroxide commonly used in the tire industry can be used. These may be used alone or in combination of two or more kinds.

[0055] The average primary particle size of aluminum hydroxide is preferably 0.6 μm or more, more preferably 0.7 μm or more. The average primary particle size of aluminum hydroxide is preferably 10 μm or less, more preferably 5 μm or less, even more preferably 1.3 μm or less, and particularly preferably 1.2 μm or less. Within the above range, the effect tends to be better obtained. In this specification, the average primary particle size of aluminum hydroxide is a number average particle size, which is measured by a transmission electron microscope.

[0056] In the rubber composition, the content of aluminum hydroxide is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less. By keeping the content within the above range, there is a tendency that the overall performance of fuel efficiency and suppression of deterioration of wet grip performance over time is improved.

[0057] (Plasticizer) The rubber composition includes a liquid polymer and / or a resin component. The liquid polymer and the resin component are materials that impart plasticity to the rubber component. The liquid polymer is a polymer that is in a liquid state at room temperature (25°C). The resin component is a resin that is in a liquid state at room temperature (25°C) or a resin that is in a solid state at room temperature (25°C). These may be used alone or in combination of two or more kinds.

[0058] In the rubber composition, the content of the liquid polymer (total amount of the liquid rubber and liquid farnesene polymer described below) is preferably 5 parts by mass or more, more preferably 8 parts by mass or more, and even more preferably 10 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 60 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 25 parts by mass or less, and particularly preferably 15 parts by mass or less. By keeping the content within the above range, there is a tendency that the overall performance of fuel efficiency and suppression of deterioration of wet grip performance over time is improved.

[0059] Examples of liquid polymers include liquid rubber and liquid farnesene-based polymers.

[0060] Examples of liquid rubber include liquid diene rubber that can be extracted with acetone. Specific examples include liquid diene rubbers such as liquid styrene butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), liquid styrene isoprene copolymer (liquid SIR), liquid styrene butadiene styrene block copolymer (liquid SBS block polymer), and liquid styrene isoprene styrene block copolymer (liquid SIS block polymer) that are liquid at 25°C. The ends or main chains of these may be modified with polar groups. Hydrogenated products of these may also be used.

[0061] In the rubber composition, the content of the liquid rubber is preferably 5 parts by mass or more, more preferably 8 parts by mass or more, and even more preferably 10 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 60 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 25 parts by mass or less, and particularly preferably 15 parts by mass or less. By keeping it within the above range, there is a tendency that the overall performance of low fuel consumption and suppression of deterioration of wet grip performance over time is improved. The content of the liquid diene rubber is also preferably within the same range.

[0062] Liquid farnesene polymers are polymers obtained by polymerizing farnesene and have structural units based on farnesene. Farnesene has isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene), but (E)-β-farnesene, which has the following structure, is preferred. [ka]

[0063] The liquid farnesene-based polymer may be a homopolymer of farnesene (farnesene homopolymer) or a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer).

[0064] Examples of vinyl monomers include aromatic vinyl compounds such as styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-tert-butylstyrene, 5-t-butyl-2-methylstyrene, vinylethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, tert-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethylether, N,N-dimethylaminoethylstyrene, N,N-dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-t-butylstyrene, 3-t-butylstyrene, 4-t-butylstyrene, vinylxylene, vinylnaphthalene, vinyltoluene, vinylpyridine, diphenylethylene, and tertiary amino group-containing diphenylethylene, as well as conjugated diene compounds such as butadiene and isoprene. These may be used alone or in combination of two or more. Among these, butadiene is preferred. That is, the farnesene-vinyl monomer copolymer is preferably a copolymer of farnesene and butadiene (farnesene-butadiene copolymer).

[0065] In the farnesene-vinyl monomer copolymer, the copolymerization ratio by mass of farnesene and vinyl monomer (farnesene / vinyl monomer) is preferably 40 / 60 to 90 / 10.

[0066] The liquid farnesene-based polymer that can be suitably used has a weight average molecular weight (Mw) of 3000 to 300,000. The Mw of the liquid farnesene-based polymer is preferably 8000 or more, more preferably 10,000 or more, and is preferably 100,000 or less, more preferably 60,000 or less, and even more preferably 50,000 or less.

[0067] In the rubber composition, the content of the liquid farnesene polymer is preferably 5 parts by mass or more, more preferably 8 parts by mass or more, and even more preferably 10 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 60 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 25 parts by mass or less, and particularly preferably 15 parts by mass or less. By keeping the content within the above range, the overall performance of fuel efficiency and suppression of deterioration of wet grip performance over time tends to be improved.

[0068] On the other hand, in the rubber composition, the content of the resin components (the total amount of resins in a liquid state at room temperature (25° C.) and resins in a solid state at room temperature (25° C.)) is preferably 5 parts by mass or more, more preferably 8 parts by mass or more, and even more preferably 10 parts by mass or more. The upper limit of the content is preferably 60 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 25 parts by mass or less, and particularly preferably 15 parts by mass or less. By keeping it within the above range, there is a tendency that the overall performance of fuel efficiency and suppression of deterioration in wet grip performance over time is improved.

[0069] Examples of resin components that are in a liquid state at room temperature (25°C) include liquid resins. The liquid resin may be one that has a softening point below room temperature and is in a liquid state at room temperature. Examples of liquid resins include terpene resins (including terpene phenol resins and aromatic modified terpene resins), rosin resins, styrene resins, C5 resins, C9 resins, C5 / C9 resins, dicyclopentadiene (DCPD) resins, coumarone-indene resins (including coumarone and indene simple resins), phenol resins, olefin resins, polyurethane resins, and acrylic resins. Hydrogenated versions of these resins can also be used.

[0070] In the rubber composition, the content of the liquid resin is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, even more preferably 50 parts by mass or less, and particularly preferably 35 parts by mass or less. By keeping the content within the above range, the overall performance of fuel efficiency and suppression of deterioration of wet grip performance over time tends to be improved.

[0071] Examples of the resin component that is in a solid state at room temperature (25°C) (hereinafter also referred to as "solid resin") include aromatic vinyl polymers, coumarone-indene resins, coumarone resins, indene resins, phenolic resins, rosin resins, petroleum resins, terpene resins, and acrylic resins that are in a solid state at room temperature (25°C). The resins may be hydrogenated. These may be used alone or in combination of two or more. Among these, aromatic vinyl polymers, terpene resins, petroleum resins, and hydrogenated versions of these are preferred from the viewpoint of overall performance in terms of fuel economy and suppression of deterioration of wet grip performance over time.

[0072] In the rubber composition, the content of the solid resin is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 100 parts by mass or less, more preferably 70 parts by mass or less, even more preferably 50 parts by mass or less, and particularly preferably 35 parts by mass or less. By keeping it within the above range, there is a tendency that the overall performance of fuel efficiency and suppression of deterioration of wet grip performance over time is improved. In addition, the content of aromatic vinyl polymer, the content of terpene resin, the content of petroleum resin, and the content of hydrogenated products thereof are also preferably in the same range.

[0073] The softening point of the solid resin is preferably 60° C. or higher, more preferably 70° C. or higher, and even more preferably 80° C. or higher. The upper limit is preferably 160° C. or lower, more preferably 130° C. or lower, and even more preferably 115° C. or lower. By keeping the softening point within the above range, there is a tendency for the overall performance of low fuel consumption and suppression of deterioration of wet grip performance over time to improve. The softening point of the resin component is the temperature at which the ball drops when the softening point specified in JIS K6220-1:2001 is measured using a ring and ball softening point tester.

[0074] The aromatic vinyl polymer is a polymer containing an aromatic vinyl monomer as a structural unit. For example, it can be a resin obtained by polymerizing α-methylstyrene and / or styrene, and specifically, it can be a homopolymer of styrene (styrene resin), a homopolymer of α-methylstyrene (α-methylstyrene resin), a copolymer of α-methylstyrene and styrene, a copolymer of styrene and another monomer, etc.

[0075] The coumarone-indene resin is a resin containing coumarone and indene as main monomer components constituting the resin skeleton (main chain). Other monomer components contained in the skeleton besides coumarone and indene include styrene, α-methylstyrene, methylindene, vinyltoluene, etc. The content of the coumarone-indene resin is preferably 1 to 200 parts by mass based on 100 parts by mass of the rubber component.

[0076] The coumarone resin is a resin containing coumarone as a main monomer component constituting the skeleton (main chain) of the resin.

[0077] The indene resin is a resin containing indene as a main monomer component constituting the skeleton (main chain) of the resin.

[0078] The phenolic resin may be a known polymer obtained by reacting phenol with an aldehyde such as formaldehyde, acetaldehyde, or furfural in the presence of an acid or alkali catalyst. Among these, those obtained by reacting with an acid catalyst (such as novolac-type phenolic resin) are preferred.

[0079] The rosin resin may be a rosin-based resin such as natural rosin, polymerized rosin, modified rosin, their ester compounds, or their hydrogenated products, etc. The content of the rosin resin is preferably 1 to 200 parts by mass based on 100 parts by mass of the rubber component.

[0080] Examples of the petroleum resin include C5 resin, C9 resin, C5 / C9 resin, dicyclopentadiene (DCPD) resin, and hydrogenated versions of these resins. Of these, DCPD resin and hydrogenated DCPD resin are preferred.

[0081] The terpene resin is a polymer containing terpene as a structural unit. For example, polyterpene resin obtained by polymerizing a terpene compound, aromatic modified terpene resin obtained by polymerizing a terpene compound and an aromatic compound, etc. can be mentioned. Hydrogenated products of these can also be used.

[0082] The polyterpene resin is a resin obtained by polymerizing a terpene compound. The terpene compound is (C5H8) n The hydrocarbons and their oxygen-containing derivatives represented by the composition 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32), and examples thereof include α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0083] Examples of the polyterpene resin include pinene resin, limonene resin, dipentene resin, pinene / limonene resin, etc., which are made from the above-mentioned terpene compounds. Among them, pinene resin is preferable. Pinene resin usually contains both α-pinene and β-pinene, which are isomers, but depending on the components contained, it is classified into β-pinene resin mainly composed of β-pinene and α-pinene resin mainly composed of α-pinene.

[0084] Examples of the aromatic modified terpene resin include terpene phenol resins made from the above terpene compounds and phenolic compounds, and terpene styrene resins made from the above terpene compounds and styrene compounds. Terpene phenol styrene resins made from the above terpene compounds, phenolic compounds, and styrene compounds can also be used. Examples of the phenolic compounds include phenol, bisphenol A, cresol, and xylenol. Examples of the styrene compounds include styrene and α-methylstyrene.

[0085] The acrylic resin is a polymer containing an acrylic monomer as a constituent unit. For example, a styrene-acrylic resin having a carboxyl group and obtained by copolymerizing an aromatic vinyl monomer component and an acrylic monomer component, such as a styrene-acrylic resin, can be used. Among them, a solventless carboxyl group-containing styrene-acrylic resin can be preferably used.

[0086] The solvent-free carboxyl group-containing styrene-acrylic resin is a (meth)acrylic resin (polymer) synthesized by a high-temperature continuous polymerization method (high-temperature continuous bulk polymerization method) (methods described in U.S. Pat. No. 4,414,370, JP-A-59-6207, JP-B-5-58005, JP-A-1-313522, U.S. Pat. No. 5,010,166, Toa Gosei Kenkyuu Nenpo TREND 2000 Vol. 3, p. 42-45, etc.) with minimal use of auxiliary raw materials such as polymerization initiators, chain transfer agents, and organic solvents. In this specification, (meth)acrylic means methacryl and acrylic.

[0087] Examples of the acrylic monomer components constituting the acrylic resin include (meth)acrylic acid, (meth)acrylic acid esters (alkyl esters such as 2-ethylhexyl acrylate, aryl esters, aralkyl esters, etc.), (meth)acrylamide, (meth)acrylic acid derivatives such as (meth)acrylamide derivatives, etc. (Meth)acrylic acid is a general term for acrylic acid and methacrylic acid.

[0088] Examples of the aromatic vinyl monomer component constituting the acrylic resin include aromatic vinyls such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene.

[0089] As the monomer components constituting the acrylic resin, other monomer components may be used in addition to the (meth)acrylic acid, (meth)acrylic acid derivatives, and aromatic vinyl.

[0090] Examples of the plasticizer that can be used include products from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., Taoka Chemical Co., Ltd., Novares Rutgers, and the like.

[0091] In the rubber composition, the total content (parts by mass) of the liquid polymer and the resin component per 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 15 parts by mass or more, and particularly preferably 20 parts by mass or more per 100 parts by mass of the rubber component. The upper limit of the content is preferably 100 parts by mass or less, more preferably 60 parts by mass or less, even more preferably 40 parts by mass or less, and particularly preferably 35 parts by mass or less. By keeping it within the above range, the overall performance of low fuel consumption and suppression of deterioration of wet grip performance over time tends to be improved.

[0092] The rubber composition may further contain a plasticizer other than the liquid polymer and the resin component.

[0093] In the rubber composition, the content of the plasticizer (the total amount of the liquid polymer, the resin component, and other plasticizers) is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, and particularly preferably 40 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 200 parts by mass or less, more preferably 150 parts by mass or less, even more preferably 100 parts by mass or less, and particularly preferably 75 parts by mass or less. By keeping the content within the above range, there is a tendency that the overall performance of fuel efficiency and suppression of deterioration of wet grip performance over time is improved.

[0094] The other plasticizers include plasticizers that are in a liquid state at room temperature (25° C.) other than the liquid polymers. Specific examples include oils.

[0095] Examples of the oil include process oil, vegetable oil, or a mixture thereof. Examples of the process oil include paraffin-based process oil, aromatic process oil, naphthenic process oil, etc. Examples of the vegetable oil include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. Examples of commercially available products include products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H&R Co., Ltd., Toyokuni Oil Mill Co., Ltd., Fuji Kosan Co., Ltd., and Nisshin Oillio Group Co., Ltd. Among these, process oils (paraffin-based process oils, aromatic process oils, naphthenic process oils, etc.) and vegetable oils are preferred.

[0096] In the rubber composition, the oil content is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 35 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit of the content is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 50 parts by mass or less. By keeping the content within the above range, there is a tendency that the overall performance of fuel efficiency and suppression of deterioration of wet grip performance over time is improved. The oil content includes the oil contained in the oil extension oil.

[0097] In the rubber composition, the content of the liquid plasticizer (total amount of liquid rubber, liquid farnesene polymer, and oil) is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 35 parts by mass or more, and particularly preferably 45 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, even more preferably 70 parts by mass or less, and particularly preferably 60 parts by mass or less. By keeping it within the above range, the overall performance of low fuel consumption and suppression of deterioration of wet grip performance over time tends to be improved.

[0098] From the viewpoint of overall performance of fuel economy and suppression of deterioration in wet grip performance over time, it is preferable that the rubber composition has the silica content (parts by mass) per 100 parts by mass of the rubber component and the total content (parts by mass) of the liquid polymer and the resin component per 100 parts by mass of the rubber component satisfy the following formula: Silica content / total content of liquid polymer and resin components≦8.0 The silica content / total content of liquid polymer and resin components is preferably 6.0 or less, more preferably 5.0 or less, even more preferably 4.0 or less, and particularly preferably 3.5 or less. The lower limit is not particularly limited, but is preferably 1.0 or more, more preferably 2.0 or more, even more preferably 2.3 or more, and particularly preferably 2.3 or more. In particular, when the relationship of silica content / total content of liquid polymer and resin components≦5.0 is satisfied, one of the six faces of the front, back, left, right, top and bottom of the silica particles hydrophobized with the above-mentioned long-chain silane coupling agent will be in contact with the liquid polymer and / or resin component, which makes it easier to disperse the liquid polymer and resin component together with the silica, and as a result, it is presumed that the overall performance of fuel efficiency and suppression of deterioration of wet grip performance over time will be significantly improved.

[0099] From the viewpoint of the overall performance of fuel economy and suppression of deterioration in wet grip performance over time, it is preferable that the content (parts by mass) of the oil per 100 parts by mass of the rubber component and the total content (parts by mass) of the liquid polymer and the resin component per 100 parts by mass of the rubber component satisfy the following formula: Oil content / total content of liquid polymer and resin components≦6.0 The ratio of the oil content to the total content of the liquid polymer and the resin component is preferably 4.0 or less, more preferably 3.0 or less, even more preferably 2.0 or less, and particularly preferably 1.8 or less. The lower limit is not particularly limited, but is preferably 0.5 or more, more preferably 0.7 or more, even more preferably 0.8 or more, and particularly preferably 1.0 or more.

[0100] In the rubber composition, from the viewpoint of the overall performance of fuel economy and suppression of deterioration in wet grip performance over time, it is preferable that the content of the silica (the content of the silica (parts by mass) per 100 parts by mass of the rubber component) and the total content of the liquid polymer and the resin component (the total content (parts by mass) of the liquid polymer and the resin component per 100 parts by mass of the rubber component) satisfy the following formula: Silica content - total content of liquid polymer and resin components ≦80 The content of silica (the total content of the liquid polymer and the resin component) is preferably 70 parts by mass or less, more preferably 55 parts by mass or less, and even more preferably 45 parts by mass or less. The lower limit is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 35 parts by mass or more.

[0101] In the rubber composition, from the viewpoint of the overall performance of fuel economy and suppression of deterioration in wet grip performance over time, it is preferable that the oil content (the oil content (parts by mass) per 100 parts by mass of the rubber component) and the total content of the liquid polymer and the resin component (the liquid polymer and the resin component total content (parts by mass) per 100 parts by mass of the rubber component) satisfy the following formula: Oil content - total content of liquid polymer and resin components ≦50 The oil content (total content of the liquid polymer and the resin component) is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, even more preferably 25 parts by mass or less, and particularly preferably 15 parts by mass or less. The lower limit is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more.

[0102] (Processing aids) The rubber composition preferably contains a processing aid. Examples of processing aids include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, fatty acid esters, mixtures of fatty acid metal salts and amide esters, mixtures of fatty acid metal salts and fatty acid amides, etc. These may be used alone or in combination of two or more. Among them, at least one selected from the group consisting of fatty acid metal salts, amide esters, and mixtures of fatty acid metal salts and amide esters or fatty acid amides is preferred, and fatty acid metal salts are more preferred.

[0103] The fatty acid constituting the fatty acid metal salt is not particularly limited, but examples thereof include saturated or unsaturated fatty acids (preferably saturated or unsaturated fatty acids having 6 to 28 carbon atoms (more preferably 10 to 25 carbon atoms, and even more preferably 14 to 20 carbon atoms)), such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidic acid, behenic acid, and nervonic acid. These may be used alone or in combination of two or more. Of these, saturated fatty acids are preferred, and saturated fatty acids having 14 to 20 carbon atoms are more preferred.

[0104] Examples of metals constituting fatty acid metal salts include alkali metals such as potassium and sodium, alkaline earth metals such as magnesium, calcium and barium, zinc, nickel, molybdenum, etc. These may be used alone or in combination of two or more. Among these, zinc and calcium are preferred, and zinc is more preferred.

[0105] Examples of the amide ester include fatty acid amide esters having the above-mentioned saturated or unsaturated fatty acids as constituents, etc. These may be used alone or in combination of two or more kinds.

[0106] The fatty acid amide may be a saturated fatty acid amide or an unsaturated fatty acid amide. These may be used alone or in combination of two or more. Examples of the saturated fatty acid amide include N-(1-oxooctadecyl)sarcosinamide, stearic acid amide, and behenic acid amide. Examples of the unsaturated fatty acid amide include oleic acid amide and erucic acid amide.

[0107] A specific example of the mixture of a fatty acid metal salt and an amide ester is Aflux 16 manufactured by Rhein Chemie, which is a mixture of a fatty acid calcium salt and an amide ester.

[0108] A specific example of the mixture of a fatty acid metal salt and a fatty acid amide is WB16 manufactured by Struktol, which is a mixture of fatty acid calcium salt and a fatty acid amide.

[0109] As the processing aid, for example, products available from Rhein Chemie, Struktol, etc. can be used.

[0110] The content of the processing aid is preferably 0.5 parts by mass or more, more preferably 1.5 parts by mass or more, and preferably 10 parts by mass or less, more preferably 6 parts by mass or less, based on 100 parts by mass of the rubber component. By keeping the content within the above range, there is a tendency that the overall performance of fuel economy and suppression of deterioration of wet grip performance over time is improved.

[0111] (Other materials) From the viewpoints of crack resistance, ozone resistance, and the like, the rubber composition preferably contains an antioxidant.

[0112] The antiaging agent is not particularly limited, and examples thereof include naphthylamine-based antiaging agents such as phenyl-α-naphthylamine; diphenylamine-based antiaging agents such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine, Examples of the antioxidant include p-phenylenediamine antioxidants such as amines; quinoline antioxidants such as polymerized 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. Among these, p-phenylenediamine antioxidants and quinoline antioxidants are preferred, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and polymerized 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. Commercially available products include, for example, products from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and Flexis Co., Ltd.

[0113] In the rubber composition, the content of the antioxidant is preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more, based on 100 parts by mass of the rubber component. The content is preferably 7.0 parts by mass or less, more preferably 4.0 parts by mass or less.

[0114] The rubber composition preferably contains stearic acid. The content of stearic acid in the rubber composition is preferably 0.5 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the rubber component.

[0115] 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.

[0116] The rubber composition preferably contains zinc oxide. The content of zinc oxide in the rubber composition is preferably 0.5 to 10 parts by mass, and more preferably 1 to 5 parts by mass, based on 100 parts by mass of the rubber component.

[0117] 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., etc.

[0118] The rubber composition may contain wax. The content of the wax in the rubber composition is preferably 0.5 to 10 parts by mass, and more preferably 1 to 5 parts by mass, based on 100 parts by mass of the rubber component.

[0119] The wax is not particularly limited, and examples thereof include petroleum waxes, natural waxes, etc. Also, synthetic waxes obtained by refining or chemically treating multiple waxes can be used. These waxes may be used alone or in combination of two or more kinds.

[0120] Examples of petroleum waxes include paraffin wax and microcrystalline wax. Examples of natural waxes are not particularly limited as long as they are derived from resources other than petroleum, and include, for example, vegetable waxes such as candelilla wax, carnauba wax, Japan wax, rice wax, and jojoba wax; animal waxes such as beeswax, lanolin, and spermaceti; mineral waxes such as ozokerite, ceresin, and petrolactam; and refined products thereof. Examples of commercially available products include products from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Seiko Chemical Co., Ltd.

[0121] It is preferable to compound sulfur in the rubber composition, in order to form an appropriate amount of crosslinked chains in the polymer chains and to impart good performance.

[0122] In the rubber composition, the amount of sulfur is preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, and even more preferably 0.5 part by mass or more, based on 100 parts by mass of the rubber component. The amount is preferably 4.0 parts by mass or less, more preferably 3.0 parts by mass or less, and even more preferably 2.0 parts by mass or less.

[0123] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. Commercially available products include those from Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanzuri Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. These may be used alone or in combination of two or more kinds.

[0124] The rubber composition preferably contains a vulcanization accelerator. In the rubber composition, the content of the vulcanization accelerator is not particularly limited and may be freely determined according to the desired vulcanization speed and crosslink density, but is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 1.5 parts by mass or more, based on 100 parts by mass of the rubber component. The upper limit is preferably 8.0 parts by mass or less, more preferably 6.0 parts by mass or less, and even more preferably 5.0 parts by mass or less.

[0125] The type of vulcanization accelerator is not particularly limited, and any commonly used accelerator can be used. 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-based, guanidine-based and benzothiazole-based vulcanization accelerators are preferred.

[0126] In addition to the above-mentioned components, the rubber composition may contain compounding agents generally used in the tire industry, such as materials such as a mold release agent, as appropriate.

[0127] The rubber composition can be produced by a known method, for example, by kneading the components using a rubber kneading device such as an open roll or a Banbury mixer, followed by vulcanization.

[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 50 to 200°C, preferably 80 to 190°C, and the kneading time is usually 30 seconds to 30 minutes, preferably 1 minute to 30 minutes. In the finish kneading step in which the vulcanizing agent and the vulcanization accelerator are kneaded, the kneading temperature is usually 100°C or lower, preferably room temperature to 80°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 120 to 200°C, preferably 140 to 180°C.

[0129] The rubber composition can be preferably used for each component of a pneumatic tire such as a tread (cap tread), a sidewall, a base tread, a bead apex, a clinch apex, an inner liner, an under tread, a breaker topping, a braid topping, a tread, etc. Among them, the rubber composition can be preferably used for a tread (cap tread).

[0130] A tire is manufactured by a conventional method using a rubber composition. That is, the rubber composition containing the above-mentioned components is extruded in an unvulcanized state to match the shape of a tread, etc., and molded together with other tire components in a conventional manner on a tire building machine to form an unvulcanized tire. The unvulcanized tire is heated and pressurized in the vulcanizer to obtain a tire.

[0131] Examples of the tire include pneumatic tires and non-pneumatic tires. Among them, pneumatic tires are preferred. The tire can be used as a passenger car tire, a large passenger car tire, a large SUV tire, a heavy load tire such as a truck or a bus tire, a light truck tire, a two-wheeled vehicle tire, a racing tire (high performance tire), etc. Among them, it can be preferably used as a passenger car tire. EXAMPLES

[0132] The present invention will be specifically described based on examples, but the present invention is not limited to these examples.

[0133] Various chemicals used in the examples and comparative examples will be collectively described below. NR:TSR20 SBR: HPR850 manufactured by JSR Corporation (styrene content 27.5% by mass, vinyl bond content 59.0% by mass, Tg-24°C) BR: Ubepol BR150B (cis content 98% by mass, vinyl bond content 1% by mass) manufactured by Ube Industries, Ltd. Carbon black: Mitsubishi Chemical Corporation's Seast N220 (N2SA114m 2 / g) Silica 1: Ultrasil VN3 (N2SA175m) manufactured by Evonik Degussa 2 / g) Silica 2: Ultrasil 9100GR (N2SA235m) manufactured by Evonik Degussa 2 / g) Organosilicon compound 1: Silane coupling agent synthesized in Production Example 1 below Organosilicon compound 2: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa Oil: Diana Process NH-70S (aromatic process oil) manufactured by Idemitsu Kosan Co., Ltd. Wax: Ozoace wax made by Nippon Seiro Co., Ltd. Antioxidant 1: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Antioxidant 2: Nocrac RD (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Stearic acid: NOF Corporation's "Tsubaki" stearic acid Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Processing aid: EF44 (zinc salt of saturated fatty acid) manufactured by Struktol Solid resin 1: Sylvares 4401 manufactured by Arizona Chemical Company (a copolymer of α-methylstyrene and styrene, softening point 85°C, Tg 43°C) Solid resin 2: YS Resin PX1150 (polyterpene (β-pinene resin), softening point 115°C) manufactured by Yasuhara Chemical Co., Ltd. Solid resin 3: ExxonMobil PR120 (hydrogenated DCPD resin, softening point 120°C) Liquid polymer 1: Licon 150 (liquid butadiene polymer, Mn5200) manufactured by Sartomer Liquid polymer 2: Kuraray's L-FBR-742 (liquid farnesene butadiene copolymer, SP value 8.1) Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Co., Ltd. Vulcanization accelerator NS: Noccela NS (N-tert-butyl-2-benzothiazylsulfenamide (TBBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator DPG: Noccelaer D (N,N'-diphenylguanidine (DPG)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator M: Noccela M (2-mercaptobenzothiazole) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0134] (Production Example 1: Synthesis of Organosilicon Compound 1) In a 2L separable flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer, 78.0g (1.0 mol) of anhydrous sodium sulfide, 80.3g (2.5 mol) of sulfur and 480g of ethanol were charged and heated to 80°C. 566g (2.0 mol) of 6-chlorohexyltriethoxysilane was added dropwise therein and heated and stirred at 80°C for 10 hours. The reaction liquid was filtered under pressure using a filter plate to obtain a filtrate from which the salt generated as the reaction proceeded was removed. The obtained filtrate was heated to 100°C, and ethanol was distilled off under a reduced pressure of 10mmHg or less to obtain an organosilicon compound 1 (silane coupling agent) as a reaction product. The obtained organosilicon compound 1 had a sulfur content of 18.5% by mass, the average number of sulfur atoms x contained in one molecule of the organosilicon compound was 3.5, and the value of m was 6.

[0135] <Examples and Comparative Examples> According to the compounding recipes shown in each table, polymers and compounding chemicals were added using a 1.7 L Banbury mixer, and the mixture was kneaded for 3 minutes at 150°C to obtain a kneaded product. Sulfur and a vulcanization accelerator were added, and the mixture was kneaded for 2 minutes at 100°C using an open roll to obtain an unvulcanized rubber composition. Each of the obtained unvulcanized rubber compositions was molded into the shape of a cap tread, laminated together with other tire components, and vulcanized at 170°C for 15 minutes to produce a test tire (tire size: 195 / 65R15).

[0136] The obtained test tires were subjected to the following evaluations. The evaluation results are shown in the tables. In Tables 1 and 2, Comparative Examples 1-4 and 2-4 were used as the reference comparative examples, respectively.

[0137] <Rolling resistance (low fuel consumption performance)> Using a rolling resistance tester, the rolling resistance of each test tire was measured when it was run with a rim (15x6JJ), internal pressure (230kPa), load (3.43kN), and speed (80km / h), and the results were expressed as an index (fuel economy performance index), with the standard comparative example being set at 100. The higher the index, the more excellent the fuel economy performance.

[0138] <Prevention of deterioration of wet grip performance over time (actual vehicle)> Each test tire was driven on a road course in a new condition, and the grip performance (braking / turning) of each tire on a wet road surface was evaluated on a scale of 1 to 10 based on the driver's feeling, and the same evaluation was performed by 10 drivers, and the total score was calculated as the wet grip performance score in the new condition. Each test tire was then heat-treated in an oven at 80°C for 2 weeks, and evaluated in the same way as when it was new, to obtain a score for the wet grip performance after aging. From the scores obtained in each test, a wet grip performance degradation suppression index was calculated according to the following calculation method, with the reference comparative example being set at 100. Wet grip deterioration index of test tire = Score of wet grip performance of test tire after aging / Score of wet grip performance of test tire when new Wet grip performance degradation prevention index of test tire = Wet grip degradation index of test tire / Wet grip degradation index of standard comparative example × 100

[0139] [Table 1]

[0140] [Table 2]

[0141] As can be seen from each table, the examples containing a filler containing silica, a silane coupling agent containing an alkoxysilyl group and a sulfur atom and having 6 or more carbon atoms connecting the alkoxysilyl group and the sulfur atom, and a liquid polymer and / or resin component were excellent in overall performance in terms of fuel economy and inhibition of deterioration in wet grip performance over time (expressed as the sum of two indices of fuel economy and inhibition of deterioration in wet grip performance over time).

Claims

1. The composition includes a filler containing silica, a silane coupling agent, and a liquid polymer and / or resin component, The silane coupling agent includes an organosilicon compound that contains an alkoxysilyl group and a sulfur atom, and the number of carbon atoms connecting the alkoxysilyl group and the sulfur atom is 6 or more, The rubber composition for tires, wherein the organosilicon compound is an organosilicon compound represented by the following average composition formula (I): 【Chemistry 1】 (In the formula, x represents the average number of sulfur atoms and is 3.5 or more. m represents an integer of 6 or more. R １ ~R ６ are the same or different and each represents an alkyl group or an alkoxy group having 1 to 6 carbon atoms; R １ ~R ３ and R ４ ~R ６ At least one of R is the alkoxy group. １ ~R ６ may be a ring structure formed by bonding the alkyl group or the alkoxy group.

2. The content of the organosilicon compound is 0.1 to 50 parts by mass based on 100 parts by mass of silica, 2. The rubber composition for tires according to claim 1, wherein the content of silica, the liquid polymer and the total content of the resin component per 100 parts by mass of the rubber component satisfy the following formula: Silica content / total content of liquid polymer and resin component≦8.0

3. 3. The rubber composition for tires according to claim 1 or 2, wherein the content of the isoprene-based rubber is 15 to 40 mass%, the content of the styrene-butadiene rubber is 30 to 70 mass%, and the content of the butadiene rubber is 5 to 20 mass%, based on 100 mass% of the rubber component.

4. The composition includes a filler containing silica, a silane coupling agent, and a liquid polymer and / or resin component, The silane coupling agent includes an organosilicon compound which contains an alkoxysilyl group and a sulfur atom, and in which the number of carbon atoms connecting the alkoxysilyl group and the sulfur atom is 6 or more, the organosilicon compound is an organosilicon compound represented by the following average composition formula (I), and the content of silica and the total content of the liquid polymer and the resin component per 100 parts by mass of the rubber component satisfy the following formula: Silica content / total content of liquid polymer and resin component≦3.5 【Chemistry 2】 (In the formula, x represents the average number of sulfur atoms and is 3.5 or more; m represents an integer of 6 or more; R 1 to R 6 are the same or different and represent an alkyl group or an alkoxy group having 1 to 6 carbon atoms, and at least one of R 1 to R 3 and at least one of R 4 to R 6 is the alkoxy group. Note that R 1 to R 6 may form a ring structure by bonding the alkyl groups or alkoxy groups.)

5. 5. The rubber composition for tires according to claim 4, wherein the content of said organosilicon compound is 0.1 to 50 parts by mass based on 100 parts by mass of silica.

6. 6. The rubber composition for tires according to claim 1, wherein the content of the oil, the liquid polymer and the resin component in total relative to 100 parts by mass of the rubber component satisfies the following formula: Oil content / total content of liquid polymer and resin components≦3.0

7. 7. The rubber composition for tires according to claim 1, wherein the content of the oil, the liquid polymer and the total content of the resin component per 100 parts by mass of the rubber component satisfy the following formula: 1.0≦oil content / total content of liquid polymer and resin component≦3.0

8. 8. The rubber composition for tires according to claim 1, wherein the content of silica, the liquid polymer and the resin component in total relative to 100 parts by mass of the rubber component satisfy the following formula: Silica content - total content of liquid polymer and resin component ≦ 45

9. 9. The rubber composition for tires according to claim 1, wherein the content of the oil, the liquid polymer and the total content of the resin component per 100 parts by mass of the rubber component satisfy the following formula: Oil content - total content of liquid polymer and resin components ≦25

10. The rubber composition for tires according to any one of claims 1 to 9, wherein the content of the oil, the liquid polymer and the total content of the resin component per 100 parts by mass of the rubber component satisfy the following formula: 3≦Oil content−total content of liquid polymer and resin components≦25

11. The rubber composition for tires according to any one of claims 1 to 10, wherein the silica content in 100% by mass of the filler is 50% by mass or more.

12. Nitrogen adsorption specific surface area: 160 m ２ The rubber composition for tires according to any one of claims 1 to 11, comprising at least one silica component per gram (g).

13. 13. The rubber composition for tires according to claim 1, wherein the content of the carbon black is 3 to 30 parts by mass based on 100 parts by mass of the rubber component.

14. 14. The rubber composition for tires according to claim 1, wherein the total content of the liquid polymer and the resin component is 15 parts by mass or more per 100 parts by mass of the rubber component.

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

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