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 wet grip performance at high temperature.SOLUTION: A tire rubber composition contains a filler including silica and a silane coupling agent. 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. The tire rubber composition has a glass transition temperature of -18°C or higher.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Techniques for reducing rolling resistance by reducing the amount of silica or introducing a modified group into a polymer to reduce the molecular mobility are known. However, in view of the background of the high outside air temperature, a simple reduction in rolling resistance is a concern because the heat generation property of the rubber is poor and the wet grip performance at a high temperature is reduced. Therefore, it is desired to improve the low fuel consumption performance while ensuring the wet grip performance at a high temperature.

Summary of the Invention

Problems to be Solved by the Invention

[0003] An object of the present invention is to solve the above problems and provide a rubber composition for tires that improves the overall performance of low fuel consumption performance and wet grip performance at a high temperature.

Means for Solving the Problems

[0004] The present invention relates to a rubber composition for tires containing a filler containing silica and a silane coupling agent, the silane coupling agent containing an alkoxysilyl group and a sulfur atom and including an organosilicon compound in which the number of carbon atoms connecting the alkoxysilyl group and the sulfur atom is 6 or more, and having a glass transition temperature of -18°C or higher.

[0005] Preferably, the rubber composition for tires has a glass transition temperature of -16°C or higher.

[0006] Preferably, the total styrene amount in the rubber component of the rubber composition for tires is 30% by mass or less.

[0007] It is preferable that the content of styrene-butadiene rubber in 100% by mass of the rubber component is 60 to 95% by mass, and the content of butadiene rubber is 5 to 40% by mass.

[0008] It is preferable that the content of silica is 80 parts by mass or more with respect to 100 parts by mass of the rubber component.

[0009] It is preferable to contain silica having a nitrogen adsorption specific surface area of 160 m 2 / g or more.

[0010] It is preferable that the content of oil with respect to 100 parts by mass of the rubber component is 20 parts by mass or less.

[0011] It is preferable that the content of the resin component with respect to 100 parts by mass of the rubber component is 30 parts by mass or more.

[0012] It is preferable that the content of oil and the content of the resin component with respect to 100 parts by mass of the rubber component satisfy the following formula. Content of resin component / Content of oil ≧ 2.0

[0013] The present invention also relates to a tire having a tire member made of the rubber composition.

[0014] It is preferable that the tire member is a tread.

Advantages of the Invention

[0015] According to the present invention, since it is a rubber composition for a tire containing a filler containing silica and a silane coupling agent, the silane coupling agent contains an alkoxysilyl group and a sulfur atom, and contains an organosilicon compound in which the number of carbon atoms connecting the alkoxysilyl group and the sulfur atom is 6 or more, and the glass transition temperature is -18 ° C or higher, the overall performance of low fuel consumption performance and wet grip performance at high temperature can be improved.

Embodiments for Carrying Out the Invention

[0016] The present invention relates to a tire rubber composition comprising a silica-containing filler and a silane coupling agent, wherein the silane coupling agent comprises an organosilicon compound containing an alkoxysilyl group and a sulfur atom, and having six or more carbon atoms linking the alkoxysilyl group and the sulfur atom, and having a glass transition temperature (Tg) of -18°C or higher. The rubber composition can improve the overall performance of fuel efficiency and wet grip performance at high temperatures.

[0017] The reasons for the aforementioned effects are not entirely clear, but it is presumed that they are achieved through the following mechanism. Regarding the improvement of fuel efficiency, as previously mentioned, methods to reduce rolling resistance can be considered, such as reducing the amount of silica or introducing modifying groups into the polymer to decrease molecular mobility. However, given the rising ambient temperatures, simply reducing rolling resistance may lead to poor heat generation in the rubber, raising concerns about reduced wet grip performance at high temperatures. Therefore, by using an organosilicon compound containing an alkoxysilyl group and a sulfur atom as a silane coupling agent, and having six or more carbon atoms linking the alkoxysilyl group and sulfur atom—that is, a long-chain silane coupling agent—the silica can be efficiently hydrophobicized, improving dispersibility and reducing the heat generation at or near room temperature, which contributes to rolling resistance. Furthermore, by setting the glass transition temperature (Tg) of the rubber composition to -18°C or higher, the heat generation at temperatures slightly below room temperature can be improved without worsening rolling resistance, making it possible to achieve both high and low temperatures and good wet grip performance at high temperatures (e.g., around 40°C). Consequently, it is presumed that the overall performance of fuel efficiency and wet grip performance at high temperatures will be significantly improved by these functions.

[0018] Thus, the rubber composition, having a "Tg ≥ -18°C" temperature range and comprising a filler containing silica and a silane coupling agent containing an organosilicon compound having an alkoxysilyl group and sulfur atoms, with six or more carbon atoms linking the alkoxysilyl group and sulfur atoms, solves the problem (objective) of improving overall performance in terms of fuel efficiency and wet grip performance at high temperatures. In other words, the "Tg ≥ -18°C" configuration does not define the problem (objective); the problem of this application is to improve overall performance in terms of fuel efficiency and wet grip performance at high temperatures, and the configuration that satisfies this parameter is a means of solving this problem.

[0019] The rubber composition (rubber composition after vulcanization) has a glass transition temperature (Tg) of -18°C or higher. From the viewpoint of overall performance in terms of fuel efficiency and wet grip performance at high temperatures, a Tg of -17°C or higher is preferred, more preferably -16°C or higher, even more preferably -14°C or higher, and particularly preferred -13°C or higher. The upper limit of Tg is not particularly limited, but is preferably 0°C or lower, more preferably -2°C or lower, even more preferably -4°C or lower, and particularly preferably -5°C or lower. In this specification, Tg is the tanδ peak temperature, and this tanδ peak temperature refers to the temperature corresponding to the largest tanδ value in the tanδ temperature distribution curve obtained by viscoelasticity testing. Specifically, Tg, i.e., the tanδ peak temperature, can be measured by the method described in the examples below.

[0020] Furthermore, the Tg (tanδ peak temperature) of a rubber composition (rubber composition after vulcanization) can be adjusted by the type and amount of chemicals (especially rubber components, resin components, fillers, liquid plasticizers, etc.) blended into the rubber composition. For example, Tg tends to be higher when using styrene-butadiene rubber, especially styrene-butadiene rubber with high styrene and vinyl content, or when blending resins and plasticizer components with high softening points. In addition, Tg can be adjusted to -18°C or higher by adjusting the blending amounts of materials such as styrene-butadiene rubber, resin components, silica, and plasticizers.

[0021] (Rubber component) Examples of rubber components that can be used in rubber compositions include diene-based rubbers. Examples of diene-based rubbers include isoprene-based 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). Butyl-based rubber and fluororubber are also examples. These may be used individually or in combination of two or more. Among these, SBR, BR, and isoprene-based rubbers are preferred from the viewpoint of overall performance in terms of fuel efficiency and wet grip performance at high temperatures, with SBR and BR being more preferred.

[0022] The above diene rubber may be either unmodified diene rubber or modified diene rubber. Modified diene rubbers can be any diene rubber having a functional group that interacts with a filler such as silica. Examples include end-modified diene rubbers (end-modified diene rubbers having the functional group at the end) in which at least one end of the diene rubber is modified with a compound (modifier) ​​having the functional group, main-chain modified diene rubbers having the functional group in the main chain, main-chain end-modified diene rubbers having the functional group in both the main chain and the end (for example, main-chain end-modified diene rubbers having the functional group in the main chain and at least one end modified with the modifier), and end-modified diene rubbers that are modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule, and in which hydroxyl groups or epoxy groups are introduced.

[0023] Examples of the above functional groups include amino groups, amide groups, silyl groups, alkoxysilyl groups, isocyanate groups, imino groups, imidazole groups, urea groups, ether groups, carbonyl groups, oxycarbonyl groups, mercapto groups, sulfide groups, disulfide groups, sulfonyl groups, sulfinyl groups, thiocarbonyl groups, ammonium groups, imide groups, hydrazo groups, azo groups, diazo groups, carboxyl groups, nitrile groups, pyridyl groups, alkoxy groups, hydroxyl groups, oxy groups, epoxy groups, and the like. These functional groups may have substituents. Among these, amino groups (preferably amino groups in which the hydrogen atoms of the amino group are substituted with C1-C6 alkyl groups), alkoxy groups (preferably alkoxy groups having C1-C6), and alkoxysilyl groups (preferably alkoxysilyl groups having C1-C6) are preferred.

[0024] The SBR is not particularly limited; for example, emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc., can be used. These may be used individually or in combination of two or more types.

[0025] The styrene content of 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 the content within the above range, the overall performance of fuel efficiency and wet grip performance at high temperatures tends to improve. In this specification, the styrene content is defined as follows: 1 It can be measured by 1H-NMR.

[0026] The vinyl bonding amount of 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 bonding amount 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, the overall performance of fuel efficiency and wet grip performance at high temperatures tends to improve. In this specification, the amount of vinyl bond (amount of 1,2-bonded butadiene units) can be measured by infrared absorption spectroscopy.

[0027] SBR can be either unmodified or modified. Modified SBR can be modified SBR with functional groups similar to those introduced in modified diene rubber. Hydrogenated styrene-butadiene copolymer (hydrogenated SBR) can also be used as SBR.

[0028] For example, SBR manufactured and sold by companies such as Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Co., Ltd. can be used.

[0029] The SBR content in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and particularly preferably 70% by mass or more. The upper limit is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less. By keeping it within the above range, the overall performance of fuel efficiency and wet grip performance at high temperatures tends to improve.

[0030] BR is not particularly limited, and for example, high-cis BR with a high cis content, BR containing syndiotactic polybutadiene crystals, and BR synthesized using a rare-earth catalyst (rare-earth BR) can be used. These may be used individually or in combination of two or more. In particular, it is preferable that the BR 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.

[0031] Furthermore, BR may be either unmodified BR or modified BR. Modified BR can be BR in which functional groups similar to those of modified diene rubber have been introduced. In addition, hydrogenated butadiene polymer (hydrogenated BR) can also be used as BR.

[0032] For example, products from companies such as Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation can be used as BRs.

[0033] The BR content in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. The upper limit is preferably 60% by mass or less, more preferably 40% by mass or less, even more preferably 35% by mass or less, and particularly preferably 30% by mass or less. Keeping it within the above range tends to improve the overall performance of fuel efficiency and wet grip performance at high temperatures.

[0034] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. For NR, common types used in the rubber industry can be used, such as SIR20, RSS#3, and TSR20. For IR, there are no particular limitations; common types used in the rubber industry can be used, such as IR2200. Examples of modified NR include deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR). Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used individually or in combination of two or more types.

[0035] When the rubber composition contains isoprene-based rubber, the isoprene-based rubber content in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 8% by mass or more, and even more preferably 10% by mass or more. The upper limit is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less. Keeping it within the above range tends to improve the overall performance of fuel efficiency and wet grip performance at high temperatures.

[0036] In a rubber composition, the total amount of styrene in the rubber component (the total amount of styrene contained in the entire rubber component) is preferably 30.0% by mass or less. This significantly improves the overall performance of fuel efficiency and wet grip performance at high temperatures.

[0037] The reasons for the aforementioned effects are not entirely clear, but it is presumed that they are achieved through the following mechanism. When the total amount of styrene in the rubber component is low, for example, the aggregation of SBRs and the steric hindrance during silica dispersion are reduced. Consequently, the silica hydrophobized by the long-chain silane coupling agent is more easily dispersed in the system, resulting in a reduction in heat generation at around room temperature, which contributes to rolling resistance, and an improvement in wet grip performance at high temperatures without worsening rolling resistance above Tg -18°C. It is presumed that this will significantly improve overall performance in terms of fuel efficiency and wet grip performance at high temperatures.

[0038] From the viewpoint of overall performance in terms of fuel efficiency and wet grip performance at high temperatures, the total styrene content is more preferably 25.0% by mass or less, even more preferably 23.0% by mass or less, and particularly preferably 21.0% by mass or less. The lower limit is preferably 5.0% by mass or more, more preferably 10.0% by mass or more, even more preferably 13.0% by mass or more, and particularly preferably 15.0% by mass or more.

[0039] Here, the total amount of styrene in the rubber component is Σ(amount of styrene in each styrene-containing rubber × amount of styrene in each styrene-containing rubber / 100). For example, if the rubber component consists of 40% by mass of SBR(A) (styrene content 27.5% by mass), 40% by mass of SBR(B) (styrene content 26.0% by mass), and 20% by mass of BR, the total amount of styrene in the rubber component is 21.4% by mass (= 40 × 27.5 / 100 + 40 × 26.0 / 100).

[0040] In a rubber composition, the total amount of vinyl in the rubber component (total content of vinyl in the total amount of rubber component) is preferably 30.0% by mass or more, from the viewpoint of overall performance in terms of fuel efficiency and wet grip performance at high temperatures. The total amount of vinyl is more preferably 40.0% by mass or more, even more preferably 43.0% by mass or more, and particularly preferably 45.0% by mass or more. The upper limit is preferably 70.0% by mass or less, more preferably 60.0% by mass or less, even more preferably 55.0% by mass or less, and particularly preferably 52.0% by mass or less.

[0041] Here, the total amount of vinyl in the rubber component is Σ(amount of each vinyl-containing rubber × amount of vinyl in each vinyl-containing rubber / 100). For example, if the rubber component consists of 80% by mass of SBR (vinyl content 59.0% by mass) and 20% by mass of BR (vinyl content 1.0% by mass), the total amount of vinyl in the rubber component is 47.4% by mass (= 80 × 59.0 / 100 + 5 × 10 / 100 + 20 × 1.0 / 100).

[0042] From the viewpoint of overall performance in terms of fuel efficiency and wet grip performance at high temperatures, it is preferable that the total amount of styrene and the total amount of vinyl in the rubber component of the rubber composition satisfy the following formula (A). (A) 0.20 ≤ α1 / α2 ≤ 1.00 α1: Total styrene content in the rubber component [mass%] α2: Total vinyl content in the rubber component [mass%]

[0043] In formula (A), α1 / α2 is more preferably 0.30 or more, still more preferably 0.40 or more, particularly preferably 0.42 or more, and is more preferably 0.80 or less, still more preferably 0.60 or less, particularly preferably 0.55 or less. By being within the above range, the overall performance of low fuel consumption performance and wet grip performance at high temperatures tends to improve.

[0044] (Silica) Silica is incorporated as a filler in the rubber composition. Examples of usable silica include dry-process silica (anhydrous silica), wet-process silica (hydrous silica), etc. Among them, wet-process silica is preferred because of its large number of silanol groups. As commercially available products, products of Degussa, Rhodia, Tosoh Silica Corporation, Solvay Japan Co., Ltd., Tokuyama Corporation, etc. can be used. These may be used alone or in combination of two or more.

[0045] The nitrogen adsorption specific surface area (N2SA) of silica is preferably 50 m 2 / g or more, more preferably 150 m 2 / g or more, still more preferably 160 m 2 / g or more, particularly preferably 180 m 2 / g or more, and may be 210 m 2 / g or more. The upper limit of the N2SA of silica is not particularly limited, but is preferably 600 m 2 / g or less, more preferably 350 m 2 / g or less, still more preferably 260 m 2 / g or less, particularly preferably 200 m 2 / g or less. By being within the above range, the overall performance of low fuel consumption performance and wet grip performance at high temperatures tends to improve. The N2SA of silica is a value measured by the BET method in accordance with ASTM D3037-93.

[0046] In the rubber composition, the silica content is preferably 5 parts by mass or more, more preferably 50 parts by mass or more, even more preferably 70 parts by mass or more, and particularly preferably 80 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the silica content is preferably 250 parts by mass or less, more preferably 200 parts by mass or less, even more preferably 170 parts by mass or less, and particularly preferably 150 parts by mass or less. By keeping the silica content within the above range, the overall performance of fuel efficiency and wet grip performance at high temperatures tends to improve.

[0047] (Silane coupling agent) The silane coupling agent used in the rubber composition contains an organosilicon compound that includes an alkoxysilyl group and a sulfur atom, and has six or more carbon atoms linking the alkoxysilyl group and the sulfur atom. Such organosilicon compounds may be used alone or in combination of two or more. Among the organosilicon compounds, the 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 greater. m represents an integer of 6 or greater. R 1 ~R 6 R represents an alkyl or alkoxy group having 1 to 6 carbon atoms, either identical or different. 1 ~R 3 At least one of and R 4 ~R 6 At least one of them is the aforementioned alkoxy group. 1 ~R 6 (This may be a ring structure to which the alkyl group or alkoxy group is bonded.)

[0048] x represents the average number of sulfur atoms in the organosilicon compound. x is preferably between 3.5 and 12. Here, the average number of sulfur atoms and the number of silicon atoms are calculated by measuring the amount of sulfur and silicon in the composition using X-ray fluorescence and then converting them to their respective molecular weights.

[0049] m represents an integer greater than or equal to 6, preferably between 6 and 14.

[0050] Alkyl(R) 1 ~R 6 Regarding the number of carbon atoms in the alkyl group, it is preferably between 1 and 5 carbon atoms. The alkyl group may be linear, branched, or cyclic. Specifically, examples include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, iso-butyl group, sec-butyl group, tert-butyl group, etc.

[0051] Alkoxy group (R 1 ~R 6 The alkoxy group preferably has 1 to 5 carbon atoms. The hydrocarbon group in the alkoxy group may be linear, branched, or cyclic. Specifically, examples include methoxy, ethoxy, n-propoxy, isopropoxy, and n-butoxy groups.

[0052] R 1 ~R 3 At least one of and R 4 ~R 6 At least one of them is an alkoxy group having 1 to 6 carbon atoms, preferably R 1 ~R 3 , R 4 ~R 6 Each of these consists of at least two alkoxy groups with 1 to 6 carbon atoms.

[0053] Note, R 1 ~R 6 This may be a ring structure formed by the bonding of an alkyl group or 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 to which a methyl group is bonded, each of them is R 1 and R 2 One example is a structure in which divalent groups, "-O-C2H4-CH2-" and "-C2H4-CH2-", are formed and bonded to Si.

[0054] The organosilicon compound can be prepared, for example, by the manufacturing method described in Japanese Patent Publication No. 2018-65954. Specifically, the organosilicon compound can be produced by reacting a halogen group-containing organosilicon compound of formula (I-1) described in Japanese Patent Publication No. 2018-65954 with anhydrous sodium sulfide represented by Na2S, and optionally with sulfur. When carrying out the above reaction, the addition of sulfur is optional for adjusting the sulfide chain, and can be determined by the proportions of the compound of average composition formula (I-1), anhydrous sodium sulfide, and optionally sulfur, so that a compound of the desired average composition formula (I) is obtained. For example, if you want x of the compound of average composition formula (I) to be 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).

[0055] Furthermore, by using an organosilicon compound containing an alkoxysilyl group and a sulfur atom, and having six or more carbon atoms linking the alkoxysilyl group and sulfur atom, i.e., a long-chain silane coupling agent, the alkoxy group in the compound reacts with the hydroxyl group on the silica surface, hydrophobicizing the silica surface. Due to the long carbon chain of the compound, the hydrophobic effect is greater than with conventional silane coupling agents, significantly improving the dispersibility of silica and reducing the heat generation at around room temperature, which contributes to rolling resistance. Moreover, by setting the glass transition temperature (Tg) of the rubber composition to -18°C or higher, the heat generation at temperatures slightly below room temperature is improved without worsening rolling resistance, making it possible to achieve both high-temperature (e.g., around 40°C) wet grip performance and improved overall performance. Therefore, by using such a long-chain silane coupling agent, it is possible to improve the overall performance of fuel efficiency and wet grip performance at high temperatures.

[0056] 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, per 100 parts by mass of silica. The upper limit of the content is preferably 50 parts by mass or less, 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 fuel efficiency and wet grip performance at high temperatures tends to improve. It is also desirable that the content of the organosilicon compound represented by the average composition formula (I) be within the same range.

[0057] The rubber composition may also contain other silane coupling agents other than organosilicon compounds, which include an alkoxysilyl group and a sulfur atom, and which have six or more carbon atoms linking the alkoxysilyl group and the sulfur atom. Other silane coupling agents are not limited to, but include, for example, 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-dimethylthio Examples include sulfide compounds such as rubamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and Momentive's NXT and NXT-Z; vinyl compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Commercially available products from companies such as Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and Toray Dow Corning Co., Ltd. can be used. These can be used individually or in combination of two or more types.

[0058] In the rubber composition, the content of the silane coupling agent (total amount of the organosilicon 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, per 100 parts by mass of silica. The upper limit of the content is preferably 50 parts by mass or less, 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 fuel efficiency and wet grip performance at high temperatures tends to improve.

[0059] (Other fillers) Other fillers besides silica are not particularly limited and can be materials known in the rubber field, such as inorganic fillers like carbon black, calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica. Among these, carbon black and aluminum hydroxide are preferred.

[0060] In the aforementioned rubber composition, the filler content (total filler content) is preferably 5 parts by mass or more, more preferably 50 parts by mass or more, even more preferably 80 parts by mass or more, and particularly preferably 90 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of this content is preferably 250 parts by mass or less, more preferably 200 parts by mass or less, even more preferably 170 parts by mass or less, and particularly preferably 150 parts by mass or less. By keeping the content within the above range, the overall performance of fuel efficiency and wet grip performance at high temperatures tends to improve.

[0061] In the aforementioned rubber composition, the silica content in 100% by mass of the filler is preferably 50% by mass or more, preferably 80% by mass or more, and more preferably 85% by mass or more, from the viewpoint of overall performance in terms of low fuel consumption and wet grip performance at high temperatures. There is no particular upper limit, but 98% by mass or less is preferred, and 95% by mass or less is more preferred.

[0062] The carbon black that can be used in the rubber composition is not particularly limited, but examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nippon Chemical Carbon Co., Ltd., and Columbia Carbon Corporation. These may be used individually or in combination of two or more types.

[0063] The specific surface area (N2SA) of carbon black for nitrogen adsorption is 50 m². 2 Preferably 70m / g or more. 2 More preferably 90m 2 More preferably, the amount of N2SA is 200m 2 Preferably less than / g, 150m 2 More preferably less than / g, 130m 2 A value of less than / g is even more preferable. Keeping the value within the above range tends to improve overall performance, including fuel efficiency and wet grip performance at high temperatures. The specific surface area for nitrogen adsorption of carbon black is determined according to JIS K6217-2:2001.

[0064] In the aforementioned rubber composition, the carbon black content is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit of the content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. By keeping it within the above range, the overall performance of fuel efficiency and wet grip performance at high temperatures tends to improve.

[0065] The aluminum hydroxide used is not particularly limited and can be any commonly used in the tire industry. These can be used individually or in combination of two or more types.

[0066] The average primary particle diameter of aluminum hydroxide is preferably 0.6 μm or more, more preferably 0.7 μm or more. Furthermore, the average primary particle diameter 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 these ranges, a better effect tends to be obtained. In this specification, the average primary particle diameter of aluminum hydroxide is the number-average particle diameter and is measured by a transmission electron microscope.

[0067] In the aforementioned rubber composition, the content of aluminum hydroxide is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, per 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 it within the above range, the overall performance of fuel efficiency and wet grip performance at high temperatures tends to improve.

[0068] (Plasticizer) The rubber composition may contain a plasticizer. A plasticizer is a material that imparts plasticity to the rubber component, and examples include liquid plasticizers (plasticizers that are liquid at room temperature (25°C)) and resin components (resins that are liquid at room temperature (25°C) and resins that are solid at room temperature (25°C)). In particular, when a resin component is added, it is possible to increase the heat generation at high temperatures and improve dispersibility during mixing by adsorption to the silica surface, thereby significantly improving the overall performance of fuel efficiency (rolling resistance) and wet grip performance at high temperatures.

[0069] In the aforementioned rubber composition, the plasticizer content (total amount of plasticizer) 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, the overall performance of fuel efficiency and wet grip performance at high temperatures tends to improve.

[0070] The liquid plasticizer (a plasticizer that is in a liquid state at room temperature (25°C)) that can be used in the rubber composition is not particularly limited, and examples include oils and liquid polymers. Examples of liquid polymers include liquid rubber and liquid farnesene polymers. These may be used alone or in combination of two or more.

[0071] In the rubber composition, the liquid plasticizer content (total amount of oil, liquid rubber, and liquid farnesene polymer) 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, 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 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, the overall performance of fuel efficiency and wet grip performance at high temperatures tends to improve.

[0072] Examples of oils include process oils, vegetable oils, or mixtures thereof. Examples of process oils include paraffinic process oils, aromatic process oils, and naphthenic process oils. Examples of vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. Commercial products from companies such as Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., and Nisshin Oillio Group Ltd. can be used. Among these, process oils (paraffinic process oils, aromatic process oils, naphthenic process oils, etc.) and vegetable oils are preferred.

[0073] Process oils are aromatic hydrocarbons (C) due to their molecular structure. A ), paraffinic hydrocarbons (C P ), naphthenic hydrocarbons (CN ) contains, and its content ratio C A (mass%), C P (mass%), C N The rubber composition is broadly classified into aromatic oils, paraffin oils, and naphthenic oils depending on the mass percentage, but it is desirable that the above rubber composition contains an oil in which aromatic hydrocarbons have a content of 20% by mass or more.

[0074] The aromatic hydrocarbon content of the above oil is preferably 25% by mass or more, more preferably 30% by mass or more. Furthermore, the content is preferably 70% by mass or less, more preferably 65% ​​by mass or less, and even more preferably 60% by mass or less. Keeping it within the above range tends to improve the overall performance of fuel efficiency and wet grip performance at high temperatures. In this specification, the aromatic hydrocarbon content of oil can be measured by the ring analysis method (ndM method) (ASTM D3238).

[0075] In the rubber composition, the oil content 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, per 100 parts by mass of rubber component. The upper limit of the content is preferably 70 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less. Keeping the content within the above range tends to improve the overall performance of fuel efficiency and wet grip performance at high temperatures. Note that the oil content also includes oil contained in the oil spreading oil.

[0076] Examples of liquid rubbers include liquid diene rubbers that can be extracted with acetone. Specifically, these include liquid styrene-butadiene copolymers (liquid SBR), liquid butadiene polymers (liquid BR), liquid isoprene polymers (liquid IR), liquid styrene-isoprene copolymers (liquid SIR), liquid styrene-butadiene-styrene block copolymers (liquid SBS block polymers), and liquid styrene-isoprene-styrene block copolymers (liquid SIS block polymers), which are liquid at 25°C. These may have polar groups modifying their ends or main chains. Hydrogenated versions of these rubbers can also be used.

[0077] In the rubber composition, the liquid rubber content 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, 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 70 parts by mass or less, even more preferably 50 parts by mass or less, and particularly preferably 35 parts by mass or less. Keeping the content within the above range tends to improve the overall performance of fuel efficiency and wet grip performance at high temperatures. It is also desirable that the liquid diene rubber content be within a similar range.

[0078] Liquid farnesene polymers are polymers obtained by polymerizing farnesene and have constituent 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]

[0079] The liquid farnesene polymer may be a farnesene homopolymer (farnesene homopolymer) or a farnesene-vinyl monomer copolymer (farnesene-vinyl monomer copolymer).

[0080] 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)dimethylaminoethyl ether, 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 individually or in combination of two or more. Among these, butadiene is preferred. In other words, a copolymer of farnesene and butadiene (farnesene-butadiene copolymer) is preferred as the farnesene-vinyl monomer copolymer.

[0081] In farnesene-vinyl monomer copolymers, the mass-based copolymerization ratio (farnesene / vinyl monomer) of farnesene to vinyl monomer is preferably 40 / 60 to 90 / 10.

[0082] Liquid farnesene polymers with a weight-average molecular weight (Mw) of 3,000 to 300,000 are preferably used. The Mw of the liquid farnesene polymer is preferably 8,000 or more, more preferably 10,000 or more, and also preferably 100,000 or less, more preferably 60,000 or less, and even more preferably 50,000 or less.

[0083] In the rubber composition, the content of liquid farnesene polymer 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, 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 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 wet grip performance at high temperatures tends to improve.

[0084] In the rubber composition, the liquid polymer content (total amount of liquid rubber and liquid farnesene polymer) 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, per 100 parts by mass of the rubber component. The upper limit of this 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, the overall performance of fuel efficiency and wet grip performance at high temperatures tends to improve.

[0085] In the rubber composition, the content of the resin component (total amount of resin in a liquid state and resin in a solid state at room temperature (25°C)) 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. The upper limit of the content is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, even more preferably 80 parts by mass or less, and particularly preferably 65 parts by mass or less. By keeping it within the above range, the overall performance of fuel efficiency and wet grip performance at high temperatures tends to improve.

[0086] Examples of resins that are liquid at room temperature (25°C) include liquid resins. Liquid resins may also be those that are liquid at room temperature or below, with a softening point below room temperature. Examples of liquid resins include terpene resins (including terpene phenol resins and aromatically modified terpene resins), rosin resins, styrene resins, C5 resins, C9 resins, C5 / C9 resins, dicyclopentadiene (DCPD) resins, coumarone-indene resins (including coumarone and indene-only resins), phenolic resins, olefin resins, polyurethane resins, and acrylic resins. Hydrogenated versions of these resins can also be used.

[0087] In the rubber composition, the liquid resin content 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, 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 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 wet grip performance at high temperatures tends to improve.

[0088] Examples of resin components that are solid at room temperature (25°C) (hereinafter also referred to as "solid resins") include aromatic vinyl polymers, coumarone indene resins, coumarone resins, indene resins, phenolic resins, rosin resins, petroleum resins, terpene resins, and acrylic resins that are solid at room temperature (25°C). The resins may also be hydrogenated. These may be used individually or in combination of two or more. Among these, aromatic vinyl polymers, terpene resins, petroleum resins, and hydrogenated versions thereof are preferred from the viewpoint of overall performance in terms of low fuel consumption and wet grip performance at high temperatures.

[0089] In the rubber composition, the solid resin content is preferably 5 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 25 parts by mass or more, and particularly preferably 30 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 65 parts by mass or less, and particularly preferably 55 parts by mass or less. By keeping the content within the above range, the overall performance of fuel efficiency and wet grip performance at high temperatures tends to improve. It is also desirable that the content of aromatic vinyl polymer, terpene resin, and petroleum resin be within the same range.

[0090] 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. Keeping it within the above range tends to improve overall performance, including fuel efficiency and wet grip performance at high temperatures. The softening point of the resin component is determined by measuring the softening point specified in JIS K6220-1:2001 using a ring-type softening point measuring device, and the temperature at which the sphere descends is the measured temperature.

[0091] The above-mentioned aromatic vinyl polymer is a polymer containing aromatic vinyl monomers as constituent units. Examples include resins obtained by polymerizing α-methylstyrene and / or styrene, specifically, homopolymers of styrene (styrene resin), homopolymers of α-methylstyrene (α-methylstyrene resin), copolymers of α-methylstyrene and styrene, copolymers of styrene and other monomers.

[0092] The above-mentioned coumarone-indene resin is a resin that contains coumarone and indene as the main monomer components that constitute the resin's backbone (main chain). Other monomer components that can be included in the backbone besides coumarone and indene include styrene, α-methylstyrene, methylindene, and vinyltoluene. The content of the above-mentioned coumarone-indene resin is preferably 1 to 200 parts by mass per 100 parts by mass of the rubber component.

[0093] The coumarone resin described above is a resin that contains coumarone as the main monomer component that constitutes the resin's backbone (main chain).

[0094] The above-mentioned indene resin is a resin that contains indene as the main monomer component that constitutes the resin's backbone (main chain).

[0095] As the phenolic resin mentioned above, known polymers such as those obtained by reacting phenol with aldehydes such as formaldehyde, acetaldehyde, and furfural using an acid or alkali catalyst can be used. Among these, those obtained by reaction with an acid catalyst (such as novolac-type phenolic resins) are preferred.

[0096] Examples of the rosin resins mentioned above include natural rosin, polymerized rosin, modified rosin, ester compounds thereof, and rosin-based resins represented by hydrogenated versions thereof. The content of the rosin resin is preferably 1 to 200 parts by mass per 100 parts by mass of the rubber component.

[0097] Examples of the above petroleum resins include C5 resins, C9 resins, C5 / C9 resins, dicyclopentadiene (DCPD) resins, and hydrogenated versions thereof. Among these, DCPD resins and hydrogenated DCPD resins are preferred.

[0098] The above-mentioned terpene resins are polymers containing terpenes as constituent units. Examples include polyterpene resins obtained by polymerizing terpene compounds, and aromatically modified terpene resins obtained by polymerizing terpene compounds and aromatic compounds. Hydrogenated versions of these can also be used.

[0099] The above polyterpene resin is a resin obtained by polymerizing a terpene compound. The terpene compound is (C5H8) n A hydrocarbon and its oxygen-containing derivative represented by the following composition, monoterpene (C 10 H 16 ), sesquiterpenes (C 15 H 24), diterpene (C 20 H 32 These are compounds with a terpene as their basic skeleton, classified as such, and examples include α-pinene, β-pinene, dipentene, limonene, myrcene, allocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0100] Examples of the polyterpene resins mentioned above include pinene resin, limonene resin, dipentene resin, and pinene / limonene resin, which are made from the terpene compounds described above. Among these, pinene resin is preferred. Pinene resin usually contains both α-pinene and β-pinene, which are isomers of each other, but depending on the difference in the components it contains, it is classified into β-pinene resin, which has β-pinene as the main component, and α-pinene resin, which has α-pinene as the main component.

[0101] Examples of the above-mentioned aromatically modified terpene resins include terpene-phenol resins made from the above-mentioned terpene compounds and phenolic compounds, and terpene-styrene resins made from the above-mentioned terpene compounds and styreneic compounds. In addition, terpene-phenol-styrene resins made from the above-mentioned terpene compounds, phenolic compounds, and styreneic compounds can also be used. Examples of phenolic compounds include phenol, bisphenol A, cresol, and xylenol. Examples of styreneic compounds include styrene and α-methylstyrene.

[0102] The above-mentioned acrylic resin is a polymer containing acrylic monomers as constituent units. Examples include styrene-acrylic resins such as styrene-acrylic resin, which have carboxyl groups and are obtained by copolymerizing an aromatic vinyl monomer component with an acrylic monomer component. Among these, solvent-free carboxyl group-containing styrene-acrylic resins can be suitably used.

[0103] The above-mentioned solvent-free carboxyl group-containing styrene-acrylic resin is a (meth)acrylic resin (polymer) synthesized by high-temperature continuous polymerization (high-temperature continuous mass polymerization) (as described in U.S. Patent No. 4,414,370, Japanese Patent Publication No. 59-6207, Japanese Patent Publication No. 5-58005, Japanese Patent Publication No. 1-313522, U.S. Patent No. 5,010,166, Toa Gosei Research Annual Report TREND2000 No. 3, pp. 42-45, etc.) with minimal use of polymerization initiators, chain transfer agents, organic solvents, etc. as auxiliary raw materials. In this specification, (meth)acrylic means methacrylic and acrylic.

[0104] Examples of acrylic monomer components constituting the above-mentioned acrylic resin include (meth)acrylic acid, (meth)acrylic acid esters (alkyl esters such as 2-ethylhexyl acrylate, aryl esters, aralkyl esters, etc.), (meth)acrylamide, and (meth)acrylic acid derivatives such as (meth)acrylamide derivatives. Note that (meth)acrylic acid is a general term for acrylic acid and methacrylic acid.

[0105] Examples of aromatic vinyl monomer components that constitute the above-mentioned acrylic resin include aromatic vinyls such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene.

[0106] In addition, other monomer components may be used as monomer components constituting the above-mentioned acrylic resin, along with (meth)acrylic acid, (meth)acrylic acid derivatives, and aromatic vinyl.

[0107] In a rubber composition, it is preferable that the oil content (content of the oil per 100 parts by mass of rubber component (parts by mass)) and the resin component content (content of the resin component per 100 parts by mass of rubber component (parts by mass)) satisfy the following formula. Resin component content / Oil content ≥ 1.0 The resin component content / oil content is preferably 2.0 or higher, more preferably 3.0 or higher, even more preferably 3.5 or higher, and particularly preferably 4.0 or higher. There is no particular upper limit, but it is preferably 12.0 or lower, more preferably 10.0 or lower, even more preferably 8.0 or lower, and particularly preferably 6.0 or lower. Keeping it within the above range tends to improve overall performance in terms of fuel efficiency and wet grip performance at high temperatures.

[0108] Examples of plasticizers that can be used include products from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nippon Paint Chemical Co., Ltd., Nippon Shokubai Co., Ltd., JXTG Energy Corporation, Arakawa Chemical Industries, Ltd., Taoka Chemical Industries, Novales-Rutgers, and others.

[0109] (Other materials) The aforementioned rubber composition preferably contains an anti-aging agent from the viewpoint of crack resistance, ozone resistance, etc.

[0110] While not particularly limited, the following are examples of anti-aging agents: naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, and N,N'-di-2-naphthyl-p-phenylenediamine. Examples of anti-aging agents include p-phenylenediamine-based anti-aging agents such as amines; quinoline-based anti-aging agents such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based anti-aging agents such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis, tris, and polyphenol-based anti-aging agents such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine-based anti-aging agents and quinoline-based anti-aging agents are preferred, and polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. Commercial products such as those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and Flexis Co., Ltd. can be used.

[0111] In the rubber composition, the content of the anti-aging agent is preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more, per 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.

[0112] The rubber composition preferably contains stearic acid. In the rubber composition, the stearic acid content is preferably 0.5 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0113] In addition, conventionally known stearic acid can be used, such as products from NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Corporation, Chiba Fatty Acid Co., Ltd.

[0114] The rubber composition preferably contains zinc oxide. In the rubber composition, the zinc oxide content is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0115] In addition, conventionally known zinc oxides can be used, such as products from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., and Sakai Chemical Industry Co., Ltd.

[0116] The rubber composition may contain wax. In the rubber composition, the wax content is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of the rubber component.

[0117] The type of wax used is not particularly limited and includes petroleum-based waxes, natural waxes, and synthetic waxes obtained by refining or chemically processing multiple waxes. These waxes may be used individually or in combination of two or more types.

[0118] Examples of petroleum-based waxes include paraffin wax and microcrystalline wax. Examples of natural waxes are not limited to those derived from non-petroleum resources, and include plant-based waxes such as candelilla wax, carnauba wax, wood wax, rice wax, and jojoba wax; animal-based waxes such as beeswax, lanolin, and whale wax; mineral waxes such as ozokerite, ceresin, and petrolactam; and refined products thereof. Commercially available products include those from companies such as Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Seiko Chemical Co., Ltd.

[0119] It is preferable to incorporate sulfur into the rubber composition in such a way that it forms appropriate cross-linked chains in the polymer chains and imparts good performance.

[0120] In the rubber composition, the sulfur content is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, per 100 parts by mass of the rubber component. The content 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.

[0121] Examples of sulfur commonly used in the rubber industry include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur. Commercially available products include those from Tsurumi Chemical Industries, Karuizawa Sulfur Co., Ltd., Shikoku Chemicals Co., Ltd., Flexis Co., Ltd., Nippon Dry Distillation Co., Ltd., and Hosoi Chemical Industry Co., Ltd. These can be used individually or in combination of two or more types.

[0122] The rubber composition preferably contains a vulcanization accelerator. In the aforementioned rubber composition, there are no particular restrictions on the content of the vulcanization accelerator, and it can be freely determined according to the desired vulcanization rate and crosslinking density. However, it is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, per 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.

[0123] There are no particular restrictions on the type of vulcanization accelerator; commonly used ones can be used. Examples of vulcanization accelerators include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiadylsulfenamide; 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-benzothiazolesulfenamide, Nt-butyl-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, and N,N'-diisopropyl-2-benzothiazolesulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, diortotrilguanidine, and orthotrilbiguanidine. These may be used individually or in combination of two or more. Among them, sulfenamide, guanidine, and benzothiazole vulcanization accelerators are preferred.

[0124] In addition to the components mentioned above, the rubber composition may also contain other compounding agents commonly used in the tire industry, such as mold release agents.

[0125] As for the method of producing the rubber composition, known methods can be used. For example, the rubber composition can be produced by kneading each of the components using a rubber kneading device such as an open roll or Banbury mixer, and then vulcanizing them.

[0126] Regarding the mixing conditions, in the base mixing step where additives other than the vulcanizing agent and vulcanization accelerator are mixed, the mixing temperature is usually 50 to 200°C, preferably 80 to 190°C, and the mixing time is usually 30 seconds to 30 minutes, preferably 1 minute to 30 minutes. In the finish mixing step where the vulcanizing agent and vulcanization accelerator are mixed, the mixing temperature is usually 100°C or lower, preferably room temperature to 80°C. Furthermore, the composition mixed with the vulcanizing agent and vulcanization accelerator is usually subjected to a vulcanization treatment such as press vulcanization. The vulcanization temperature is usually 120 to 200°C, preferably 140 to 180°C.

[0127] The rubber composition can be suitably applied to various components of a pneumatic tire, including the tread (cap tread), sidewall, base tread, bead apex, clinch apex, inner liner, under tread, breaker topping, pry topping, and tread. In particular, it is suitably used for the tread (cap tread).

[0128] Tires are manufactured using a rubber composition by conventional methods. Specifically, a rubber composition containing the above components is extruded to the shape of a tread or other components at an unvulcanized stage, and then molded together with other tire components on a tire molding machine in a conventional manner to form an unvulcanized tire. A tire is then obtained by heating and pressurizing this unvulcanized tire in a vulcanizing machine.

[0129] Tires include pneumatic tires and non-pneumatic tires. Of these, pneumatic tires are preferred. The tires can be used for passenger cars, large passenger cars, large SUVs, heavy-duty trucks and buses, light trucks, motorcycles, and racing tires (high-performance tires). In particular, they are suitable for passenger cars, large passenger cars, and large SUVs. [Examples]

[0130] The present invention will be specifically described based on the examples provided, but the present invention is not limited to these examples.

[0131] The various chemicals used in the examples and comparative examples are described below. SBR1: HPR850 manufactured by JSR Corporation (styrene content 27.5% by mass, vinyl bond content 59.0% by mass) SBR2: Europrene SOL R C2525 manufactured by Versalis (styrene content 25% by mass, vinyl bond content 19% by mass) SBR3: Toughden 3830 manufactured by Asahi Kasei Corporation (styrene content 33% by mass, vinyl bond content 23% by mass, oil content 37.5 parts by mass per 100 parts by mass of rubber solids) SBR4: Trinseo SLR6430 (styrene content 40% by mass, vinyl bond content 12% by mass) BR: Ubepol BR150B manufactured by Ube Industries, Ltd. (Cis content 98% by mass, vinyl bond content 1% by mass) Carbon black: Seest N220 (N2SA114m) manufactured by Mitsubishi Chemical Corporation. 2 / g) Silica 1: Evonik De Gussa's Ultrazil VN3 (N2SA175m 2 / g) Silica 2: Evonik Degussa's UltraSil 9100GR (N2SA235m 2 / g) Organosilicon compound 1: Silane coupling agent synthesized in the following manufacturing example 1. Organosilicon compound 2: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik De Gussa. Solid resin 1: SYLVARES SA85 manufactured by Arizona Chemical (a copolymer of α-methylstyrene and styrene, Tg 43°C, softening point 85°C) Solid resin 2: YS Resin PX1150 manufactured by Yasuhara Chemical Co., Ltd. (Polyterpene (β-pinene resin), softening point 115℃) Solid resin 3: PR120 (hydrogenated DCPD resin, softening point 120°C) manufactured by ExxonMobile. Oil: A / O mix manufactured by Sankyo Yuka Kogyo Co., Ltd. (oil, aromatic hydrocarbon content 29% by mass) Stearic acid: Paulownia wood manufactured by NOF Corporation. Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. Anti-aging agent: Nocrack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Wax: OzoAce wax manufactured by Nippon Seiro Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industries Co., Ltd. Vulcanization accelerator NS: Noxellar NS (N-tert-butyl-2-benzothiadylsulfenamide (TBBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator DPG: Noxellar D (diphenylguanidine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0132] (Manufacturing Example 1: Synthesis of Organosilicon Compound 1) In a 2 L separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, 78.0 g (1.0 mol) of anhydrous sodium sulfide, 80.3 g (2.5 mol) of sulfur, and 480 g of ethanol were charged and heated to 80°C. 566 g (2.0 mol) of 6-chlorohexyltriethoxysilane was added dropwise, and the mixture was heated and stirred at 80°C for 10 hours. The reaction solution was subjected to pressure filtration using a filter plate to obtain a filtrate from which the salts formed during the reaction had been removed. The obtained filtrate was heated to 100°C, and the ethanol was removed by distillation under reduced pressure of 10 mmHg or less to obtain organosilicon compound 1 (silane coupling agent) as the reaction product. The obtained organosilicon compound 1 contained 18.5% by mass of sulfur, the average number of sulfur atoms X in one molecule of organosilicon compound 1 was 3.5, and the value of m was 6.

[0133] <Examples and Comparative Examples> According to the formulations shown in each table, polymers and compounding agents were added using a 1.7L Banbury mixer and kneaded at 150°C for 3 minutes to obtain a mixture. Sulfur and a vulcanization accelerator were added and kneaded using an open roll at 100°C for 2 minutes to obtain an unvulcanized rubber composition. Each of the obtained unvulcanized rubber compositions was molded into the shape of a cap tread, bonded together with other tire components, and vulcanized at 170°C for 15 minutes to produce a test tire (tire size: 195 / 65R15).

[0134] The obtained test tires were evaluated as follows. The evaluation results are shown in each table. Tables 1 and 2 use Comparative Examples 1-2 and 2-2 as the reference comparative examples, respectively.

[0135] <Glass transition temperature (Tg)> Viscoelasticity measurement samples measuring 20 mm in length, 4 mm in width, and 1 mm in thickness were taken from the tread area of ​​each test tire, with the tire circumference being the longer side. Using a GABO iplexer series, the temperature distribution curve of tanδ was measured in the temperature range of -70 to 70°C, under conditions of a frequency of 10 Hz, initial strain of 10%, amplitude of ±0.5%, and heating rate of 2°C / min. The temperature at which tanδ reached its maximum value was determined and defined as the glass transition point (Tg).

[0136] <Rolling resistance (fuel efficiency)> Each test tire was mounted on all wheels of a vehicle (a domestically produced front-wheel-drive vehicle with a 2000cc engine), and after being inflated to the standard internal pressure (250kPa), the vehicle was driven on a dry test course at a speed of 80km / h for 15 minutes. After releasing the accelerator, the distance the vehicle traveled from the moment the accelerator was released until it came to a stop was measured as rolling resistance, with Comparative Examples 1-2 and 2-2 used as the baseline comparative examples. A higher value indicates a longer distance from the moment the accelerator is released until the vehicle comes to a stop, lower rolling resistance, and superior fuel efficiency. Rolling resistance = [(Measurement result of test tire) / (Measurement result of reference comparison)] × 100

[0137] <Wet grip performance at high temperatures (actual vehicle)> Test tires were fitted to all wheels of a domestically produced 2000cc automobile, and the braking distance on a wet road surface was measured under ambient temperature conditions of 35°C. The wet grip performance was then indexed using the following formula. A higher index indicates better wet grip performance at high temperatures. Wet grip performance index (35°C) = Braking distance of the standard comparison example / Braking distance of each compound × 100

[0138] [Table 1]

[0139] [Table 2]

[0140] From each table, the example comprising a silica-containing filler and a silane coupling agent, wherein the silane coupling agent contains an organosilicon compound having an alkoxysilyl group and a sulfur atom, and the number of carbon atoms linking the alkoxysilyl group and the sulfur atom is 6 or more, and the glass transition temperature is -18°C or higher, showed excellent overall performance in fuel efficiency and wet grip performance at high temperatures (expressed as the sum of two indices: fuel efficiency index and wet grip performance index (35°C)).

Claims

1. It contains rubber components, a silica-containing filler, and a silane coupling agent. The silane coupling agent includes an organosilicon compound comprising an alkoxysilyl group and a sulfur atom, and having six or more carbon atoms linking the alkoxysilyl group and the sulfur atom. A rubber composition for tires having a glass transition temperature of -18°C or higher, The silica content is 90 parts by mass or more per 100 parts by mass of the rubber component. The content of the organosilicon compound is 0.1 parts by mass or more and 50 parts by mass per 100 parts by mass of silica. A rubber composition for tires, wherein the total amount of styrene in the rubber component is 10.0% by mass or more and 23.0% by mass or less. (However, it contains rubber components, silica, and a liquid resin with a softening point of 7-15°C.) Of the aforementioned rubber components, the natural rubber content is 10 to 30% by mass. (Excluding tire rubber compositions in which the silica content is 105 to 160 parts by mass per 100 parts by mass of the rubber component, the liquid resin content is 30 to 50 parts by mass, and the total content of resins and oils excluding the liquid resin is 0 to 5 parts by mass)

2. It contains rubber components, a silica-containing filler, a silane coupling agent, a resin component, and oil. The silane coupling agent includes an organosilicon compound comprising an alkoxysilyl group and a sulfur atom, and having six or more carbon atoms linking the alkoxysilyl group and the sulfur atom. A rubber composition for tires having a glass transition temperature of -18°C or higher, The silica content is 50 parts by mass or more per 100 parts by mass of the rubber component. The content of the organosilicon compound is 0.1 parts by mass or more and 50 parts by mass per 100 parts by mass of silica. A tire rubber composition in which the content of the oil (parts by mass) per 100 parts by mass of the rubber component and the content of the resin component (parts by mass) per 100 parts by mass of the rubber component satisfy the following formula. 1.8 ≤ resin component content / oil content ≤ 10.0

3. It contains rubber components, a silica-containing filler, a silane coupling agent, a resin component, and oil. The silane coupling agent includes an organosilicon compound comprising an alkoxysilyl group and a sulfur atom, and having six or more carbon atoms linking the alkoxysilyl group and the sulfur atom. A rubber composition for tires having a glass transition temperature of -18°C or higher, The silica content is 90 parts by mass or more per 100 parts by mass of the rubber component. The content of the organosilicon compound is 0.1 parts by mass or more and 50 parts by mass per 100 parts by mass of silica. The total amount of styrene in the aforementioned rubber component is 10.0% by mass or more and 23.0% by mass or less. A tire rubber composition in which the content of the oil (parts by mass) per 100 parts by mass of the rubber component and the content of the resin component (parts by mass) per 100 parts by mass of the rubber component satisfy the following formula. 1.0 ≤ Resin component content / Oil content ≤ 10.0

4. A rubber composition for tires according to any one of claims 1 to 3, wherein the glass transition temperature is -16°C or higher.

5. The tire rubber composition according to claim 2, wherein the total amount of styrene in the rubber component is 30% by mass or less.

6. A tire rubber composition according to any one of claims 1 to 5, wherein the content of styrene-butadiene rubber is 60 to 95% by mass and the content of butadiene rubber is 5 to 40% by mass in 100% by mass of the rubber component.

7. The tire rubber composition according to claim 2, wherein the silica content is 80 parts by mass or more per 100 parts by mass of rubber component.

8. Nitrogen adsorption specific surface area: 160 m² ２ A tire rubber composition according to any one of claims 1 to 7, comprising silica of 1g or more.

9. A tire rubber composition according to any one of claims 1 to 8, wherein the oil content is 20 parts by mass or less per 100 parts by mass of rubber component.

10. A tire rubber composition according to any one of claims 1 to 9, wherein the content of the resin component is 30 parts by mass or more per 100 parts by mass of the rubber component.

11. A tire rubber composition according to any one of claims 1 to 10, wherein the oil content and resin content per 100 parts by mass of rubber component satisfy the following formula. Resin content / Oil content ≥ 2.0

12. The rubber composition for tires according to any one of claims 1 to 11, 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 greater. m represents an integer of 6 or greater. R1 to R6 represent the same or different alkyl or alkoxy groups having 1 to 6 carbon atoms, and at least one of R1 to R3 and at least one of R4 to R6 are the alkoxy groups. Note that R1 to R6 may also form a ring structure in which the alkyl or alkoxy groups are bonded.)

13. A tire having a tire member made of the rubber composition according to any one of claims 1 to 12.

14. The tire according to claim 13, wherein the tire component is a tread.

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