tire

Abstract

We offer tires with excellent wet grip performance. [Solution] A tire comprising a tread made of a rubber composition, wherein the tread has circumferential grooves, the rubber composition contains a rubber component having an amino group, a filler containing silica, and an ionic coupling agent, wherein when the maximum depth of the circumferential grooves is D (mm) and the silica content per 100 parts by mass of the rubber component is S (parts by mass), D × S > 300.

Description

[Technical Field]

[0001] This invention relates to tires. [Background technology]

[0002] In recent years, various methods have been investigated to improve the grip performance of tires (Patent Document 1). However, further improvements in grip performance are needed. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Special Publication No. 2013-544936 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The present invention aims to solve the aforementioned problems and provide a tire with excellent wet grip performance. [Means for solving the problem]

[0005] The present invention relates to a tire comprising a tread made of a rubber composition, wherein the tread has circumferential grooves, and the rubber composition contains a rubber component having an amino group, a filler containing silica, and an ionic coupling agent, and the maximum depth of the circumferential grooves is D (mm), and the silica content per 100 parts by mass of the rubber component is S (parts by mass), such that D × S > 300. [Effects of the Invention]

[0006] The present invention provides a tire with excellent wet grip performance, as it includes a tread made of a rubber composition, the tread having circumferential grooves, the rubber composition containing a rubber component having amino groups, a filler containing silica, and an ionic coupling agent, and when the maximum depth of the circumferential grooves is D (mm) and the silica content per 100 parts by mass of the rubber component is S (parts by mass), the tire satisfies D × S > 300. [Brief explanation of the drawing]

[0007] [Figure 1] This is a meridian-oriented cross-sectional view showing a portion of a pneumatic tire according to one embodiment of the present disclosure. [Figure 2] This is a cross-sectional view of the tire tread, cut along a plane that includes the tire axle. [Modes for carrying out the invention]

[0008] This disclosure relates to a tire comprising a tread made of a rubber composition, wherein the tread has circumferential grooves, the rubber composition contains a rubber component having an amino group, a filler containing silica, and an ionic coupling agent, and the maximum depth of the circumferential grooves is D (mm), and the silica content per 100 parts by mass of the rubber component is S (parts by mass), such that D × S > 300.

[0009] The reasons for the aforementioned effects are not entirely clear, but it is presumed that they are achieved through the following mechanism. Increasing the maximum depth of the circumferential grooves allows for better drainage of water between the wet road surface and the tire, thereby suppressing the occurrence of hydroplaning. A higher silica content improves the grip performance of the tire. By satisfying D×S>300, good wet grip performance can be obtained by increasing the silica content when the maximum depth of the circumferential grooves is small, and by increasing the maximum depth of the circumferential grooves when the silica content is small. Furthermore, by including an ionic coupling agent, when the tire comes into contact with water, bonds other than covalent bonds (primarily ionic bonds derived from the ionic coupling agent) are broken, resulting in good wet grip performance. For the reasons stated above, it is presumed that wet grip performance can be improved.

[0010] Thus, in a tire having a tread made of a rubber composition, wherein the tread has circumferential grooves, and the rubber composition contains a rubber component having amino groups, a filler containing silica, and an ionic coupling agent, the problem (objective) of improving wet grip performance is solved by providing a configuration that satisfies the condition that "the maximum depth D (mm) of the circumferential grooves and the silica content (S) are D × S > 300". In other words, the parameter "D×S>300" does not define the problem (objective); the problem of this application is to improve wet grip performance, and the configuration is designed to satisfy this parameter as a means of solving that problem.

[0011] One form of implementation of this disclosure will be described below with reference to the drawings, but this is only one form, and the tire of this disclosure is not limited to the following form.

[0012] In this specification, "rubber component" refers to a component that contributes to crosslinking, and is a solid rubber under the conditions of 1 atmosphere and 25°C. In other words, a liquid rubber under the conditions of 1 atmosphere and 25°C is not considered a "rubber component." Here, the rubber component is preferably a polymer with a weight-average molecular weight (Mw) of 50,000 or more.

[0013] The weight-average molecular weight of the rubber component is preferably 100,000 or more, more preferably 150,000 or more, even more preferably 200,000 or more, and also preferably 2,000,000 or less, more preferably 1,500,000 or less, and even more preferably 1,000,000 or less. Within this range, a better effect tends to be obtained.

[0014] In this specification, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) can be determined by converting the measured values ​​obtained by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation) to standard polystyrene equivalents.

[0015] The total styrene content in the rubber component is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and also preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less. Within the above range, a better effect tends to be obtained.

[0016] Here, the total amount of styrene in the rubber component is the total amount of styrene contained in the entire rubber component (unit: mass%), and can be calculated using the formula Σ(content of each rubber component × amount of styrene in each rubber component / 100). For example, if 100% by mass of rubber component consists of 85% by mass of styrene-butadiene rubber with a styrene content of 40% by mass, 5% by mass of styrene-butadiene rubber with a styrene content of 25% by mass, and 10% by mass of butadiene rubber with a styrene content of 0% by mass, then the total amount of styrene in the rubber component is 35.25% by mass (= 85 × 40 / 100 + 5 × 25 / 100 + 10 × 0 / 100).

[0017] In this specification, the amount of styrene in each rubber component is determined by pyrolysis gas chromatography or NMR measurement. 1 H-NMR and 13 It is calculated by 13C-NMR. The same applies to the styrene content and vinyl content of SBR described later. The amounts of these components are calculated using the complex modulus (E). * Unlike physical properties such as those mentioned above, there exists a true value that is independent of the measurement method, so it is preferable to use a measurement method that is as high-precision as possible. Furthermore, while the total amount of styrene in the rubber component is calculated in accordance with the formulas described herein in the examples, it may also be analyzed from the tire using, for example, Py-GC / MS.

[0018] The above rubber component preferably includes styrene-butadiene rubber (SBR). The above-mentioned 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 individually or in combination of two or more types.

[0019] The glass transition temperature (Tg) of the above-mentioned SBR is preferably 0°C or lower, more preferably -20°C or lower. The lower limit of the Tg of SBR is not particularly limited, but may be -90°C or higher, or -70°C or higher. When it is within the above range, the effect tends to be better obtained.

[0020] In this specification, the glass transition temperature is the value measured by differential scanning calorimetry (DSC) at a heating rate of 10°C / min in accordance with JIS K7121. Furthermore, when multiple SBRs are used, the weight average value obtained from the individual glass transition temperatures and their respective mixing ratios is treated as the glass transition temperature of the SBR. For example, if 40% by mass of SBR with a Tg of -80°C is included in 100 parts by mass of the rubber component, and 40% by mass of SBR with a Tg of -40°C is included in 100 parts by mass of the rubber component, the glass transition temperature of the SBR in the rubber composition will be -60°C (=(-80×40-40×40) / (40+40)).

[0021] The styrene content of SBR is preferably 5% by mass or more, more preferably 15% by mass or more, even more preferably 25% by mass or more, and also preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. Within the above range, a better effect tends to be obtained.

[0022] The styrene content of SBR refers to the styrene content of a single type of SBR if it is one type, and to the average styrene content if it is one of multiple types. The average styrene content of SBR can be calculated using the formula {Σ(content of each SBR × styrene content of each SBR)} / total content of all SBR. For example, if 85% of the rubber component is SBR with 40% styrene content and 5% is SBR with 25% styrene content, the average styrene content of the SBR is 39.2% (=(85 × 40 + 5 × 25) / (85 + 5)).

[0023] The vinyl content of SBR is preferably 35% by mass or more, more preferably 45% by mass or more, even more preferably 55% by mass or more, and also preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0024] The vinyl content of SBR (amount of 1,2-bonded butadiene units) is the ratio of vinyl bonds to the total mass of the butadiene portion in the SBR, with the total mass being 100 (unit: mass%). The formula is: vinyl content [mass%] + cis content [mass%] + trans content [mass%] = 100 [mass%]. If there is only one type of SBR, it refers to the vinyl content of that SBR; if there are multiple types, it refers to the average vinyl content. The average vinyl content of SBR can be calculated using the formula: Σ{Content of each SBR × (100 [mass%] - Styrene content of each SBR [mass%]) × Vinyl content of each SBR [mass%]} / Σ{Content of each SBR × (100 [mass%] - Styrene content of each SBR [mass%])}. For example, if 100 parts by mass of rubber component, 75 parts by mass of SBR contain 40% by mass of styrene and 30% by mass of vinyl, and 25% by mass of vinyl, If 15 parts by mass of SBR have a 20% vinyl content and the remaining 10 parts by mass are other than SBR, the average vinyl content of the SBR is 28% by mass (= {75 × (100 [mass%] - 40 [mass%]) × 30 [mass%] + 15 × (100 [mass%] - 25 [mass%]) × 20 [mass%])} / {75 × (100 [mass%] - 40 [mass%]) + 15 × (100 [mass%] - 25 [mass%])}.

[0025] As mentioned above, hydrogenated styrene-butadiene copolymer (hydrogenated SBR) can also be used as SBR.

[0026] 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 as the above-mentioned SBR. Alternatively, SBR synthesized by known methods can also be used.

[0027] When the above rubber component contains SBR, the SBR content in 100% by mass of the rubber component is preferably 20% by mass or more, more preferably 40% by mass or more, even more preferably 60% by mass or more, even more preferably 70% by mass or more, and also preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less. When the content is within the above range, the effect tends to be better obtained. On the other hand, from the viewpoint of wear resistance, it is preferably 70% by mass or less.

[0028] The above rubber component preferably includes butadiene rubber (BR). The above-mentioned 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. A cis content of 95% by mass or more is more preferable. The cis content can be measured by infrared absorption spectroscopy.

[0029] The cis amount of the above BR refers to the cis amount of that BR if there is only one type of BR, and the average cis amount if there are multiple types. The average cis content of BR can be calculated using the formula {Σ(content of each BR × cis content of each BR)} / total BR content. For example, if 20% of BR has a cis content of 90% and 10% has a cis content of 40% out of 100% of rubber components, the average cis content of BR is 73.3% (=(20 × 90 + 10 × 40) / (20 + 10)).

[0030] Hydrogenated butadiene polymer (hydrogenated BR) can also be used as the above-mentioned BR.

[0031] For example, products from companies such as Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation can be used as BRs.

[0032] When the above rubber component contains BR, the BR content in 100% by mass of the rubber component is preferably 5% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and also preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less. When it is within the above range, the effect tends to be better obtained. On the other hand, from the viewpoint of wear resistance, it is preferably 20% by mass or less.

[0033] The above rubber component preferably includes isoprene-based rubber. 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, such as SIR20, RSS#3, and TSR20, can be used. For IR, there are no particular limitations; common types used in the rubber industry, such as IR2200, can be used. Examples of modified NR include deproteinized natural rubber (DPNR) and high-purity natural rubber. 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.

[0034] When the above rubber component includes isoprene-based rubber, the isoprene-based rubber content in 100% by mass of the rubber component is preferably 3% by mass or more, more preferably 6% by mass or more, even more preferably 10% by mass or more, and also preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less. Within the above range, a better effect tends to be obtained. On the other hand, from the viewpoint of wear resistance, it is preferably 10% by mass or less.

[0035] The raw materials (monomers) for synthetic rubbers such as IR, SBR, and BR may be derived from underground resources such as petroleum and natural gas, or they may be recycled from rubber products such as tires or non-rubber products such as polystyrene. The monomers obtained by recycling (recycled monomers) are not particularly limited, but examples include recycled polyisoprene, recycled butadiene, and recycled aromatic vinyl. Examples of butadiene include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl include styrene, but are not particularly limited. In particular, it is preferable to use recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) as raw materials.

[0036] The method for producing recycled monomer is not particularly limited, and for example, it can be synthesized from recycled naphtha obtained by decomposing rubber products such as tires. Furthermore, the method for producing recycled naphtha is not particularly limited, and for example, rubber products such as tires may be decomposed under high temperature and pressure, decomposed by microwaves, or extracted after mechanical grinding.

[0037] Furthermore, the raw materials (monomers) of synthetic rubbers such as IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to substances derived from natural resources such as plants. Biomass is not particularly limited, but examples include agricultural, forestry, and fishery products, sugars, wood chips, plant residues after obtaining useful components, plant-derived ethanol, and biomass naphtha.

[0038] The biomass-derived monomer (biomass monomer) is not particularly limited and includes biomass-derived butadiene and biomass-derived aromatic vinyl. The butadiene is 1,2-butadiene and 1,3-butadiene. The aromatic vinyl is not particularly limited but includes styrene. Furthermore, the method for producing the biomass monomer is not particularly limited and includes, for example, biological and / or chemical and / or physical transformations of plants and animals. A typical biological transformation is fermentation by microorganisms, while chemical and / or physical transformations include those by catalysts, high heat, high pressure, electromagnetic waves, critical liquids, and combinations thereof.

[0039] The polymer synthesized from biomass monomer components (biomass polymer) is not particularly limited, and examples include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0040] Whether the raw materials for a polymer are biomass-derived can be determined by measuring pMC (percent Modern Carbon) in accordance with ASTMD6866-10.

[0041] pMC stands for Modern Standard Reference Carbon. 14 Sample relative to C concentration 14 This is a ratio of C concentrations and is used as an indicator of the biomass ratio of a compound. The significance of this value is described below.

[0042] 1 mole of carbon atoms (6.02 × 10⁻¹⁰) 23 (Each) contains approximately 6.02 × 10¹⁶ atoms, which is about one trillionth of the amount of carbon atoms in a normal atom. 11 individual 14C exists. 14 C is called a radioactive isotope, and its half-life is 5730 years, decreasing regularly. It takes 226,000 years for all of them to decay. Therefore, after carbon dioxide in the atmosphere is taken up and fixed by plants, etc., in fossil fuels such as coal, oil, and natural gas, where more than 226,000 years have passed since fixation, at the beginning of fixation, 14 all of the C element has decayed. Therefore, in the current 21st century, fossil fuels such as coal, oil, and natural gas 14 contain no C element at all. Therefore, chemical substances produced from these fossil fuels 14 also contain no C element at all.

[0043] On the other hand, 14 C is constantly generated by cosmic rays undergoing nuclear reactions in the atmosphere, and is balanced with the decrease due to radioactive decay. In the earth's atmospheric environment, 14 the amount of C is a certain amount. Therefore, in the current environment, for substances derived from biomass resources that are undergoing material circulation, 14 the C concentration is about 1×10 -12 mol% with respect to the entire C atoms as described above. Therefore, by utilizing the difference between these values, the biomass ratio of a certain compound can be calculated.

[0044] This 14 C is generally measured as follows. Using accelerator mass spectrometry based on a tandem accelerator, 13 the C concentration ( 13 C / 12 C), 14 the C concentration ( 14 C / 12 C) is measured. In the measurement, 14 as a modern standard reference for the concentration of C, the 14The C concentration will be used. The specific standard material will be the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific radioactivity of carbon in this oxalic acid (per gram of carbon) will be used. 14 The radioactivity intensity of C is separated by carbon isotope, 13 The standard value is obtained by correcting C to a constant value and applying decay correction from 1950 AD to the measurement date. 14 This value is used as the C concentration value (100%). The ratio of this value to the value of the sample actually measured is the pMC value.

[0045] Therefore, if rubber is made from 100% biomass-derived materials, although there are regional differences, under normal conditions it will often not reach 100, and will show a value of approximately 110 pMC. On the other hand, regarding chemical substances derived from fossil fuels such as petroleum, 14 When the C concentration is measured, it will show a value of approximately 0 pMC (for example, 0.3 pMC). This value corresponds to a biomass ratio of 0% as mentioned above.

[0046] Based on the above, using materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in rubber compositions is preferable from an environmental protection standpoint.

[0047] The above rubber composition may contain other rubber components in addition to isoprene rubber, BR, and SBR. Other usable rubber components include, for example, diene rubbers other than those mentioned above. Examples of diene rubbers other than isoprene rubber, BR, and SBR include styrene-isoprene butadiene rubber (SIBR), ethylene-propylene diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile butadiene rubber (NBR). Other rubber components include butyl rubber and fluororubber. The rubber components may be used individually or in combination of two or more. Furthermore, these rubber components may be subjected to modification treatment or hydrogenation treatment, and stretched rubber, which has been stretched with oil, resin, or liquid rubber components, may also be used.

[0048] The above rubber composition includes rubber having an amino group as a rubber component.

[0049] In this specification, rubber having an amino group is defined as rubber in a solid state under conditions of 1 atmosphere and 25°C. In rubber containing amino groups, "containing amino groups" means that the molecule of the diene rubber contains a functional group derived from an amino group.

[0050] Examples of rubber having the above-mentioned amino groups include end-modified rubber in which at least one end of the rubber is modified with the above-mentioned amino group compound (modifier), main-chain modified rubber having the above-mentioned amino group in the main chain, main-chain end-modified rubber having the above-mentioned amino group in the main chain and at the ends (for example, main-chain end-modified rubber having the above-mentioned amino group in the main chain and at least one end modified with the above-mentioned modifier), and modified rubber in which two or more amino groups are introduced into the molecule.

[0051] The above amino group may be a primary amino group (-NH2), a secondary amino group (-NHR), or a tertiary amino group (-NRR').

[0052] The above R and R' are monovalent hydrocarbon groups that may be substituted and may be linear, branched, or cyclic. The above R and R' may be saturated hydrocarbon groups or unsaturated hydrocarbon groups and may have heteroatoms such as oxygen.

[0053] The number of carbon atoms in R and R' is preferably 1 to 10, more preferably 1 to 8, and even more preferably 1 to 6.

[0054] Examples of R and R' above include aliphatic, alicyclic, aromatic, and other hydrocarbon groups that may contain heteroatoms or be substituted. Specifically, examples include linear alkyl groups, branched alkyl groups, cyclic alkyl groups, aryl groups, and aralkyl groups, which may contain heteroatoms or be substituted.

[0055] When R and R' are linear or branched alkyl groups that may contain heteroatoms and may be substituted, the number of carbon atoms is preferably 1 to 8, more preferably 1 to 4, and even more preferably 1 to 2. When R and R' are cyclic alkyl groups that may contain heteroatoms and may be substituted, the number of carbon atoms is preferably 3 to 12. When R and R' are aryl groups that may contain heteroatoms and may be substituted, the number of carbon atoms is preferably 6 to 10. When R and R' are aralkyl groups that may contain heteroatoms and may be substituted, the number of carbon atoms is preferably 7 to 10.

[0056] Examples of the linear and branched alkyl groups mentioned above include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, iso-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group, nonyl group, and decyl group. Examples of the above-mentioned cyclic alkyl groups include cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, adamantyl group, 1-ethylcyclopentyl group, and 1-ethylcyclohexyl group. Examples of the aryl groups mentioned above include phenyl, tolyl, xylyl, biphenyl, naphthyl, anthyl, and phenanthryl groups. Examples of the above-mentioned aralkyl groups include benzyl groups and phenethyl groups.

[0057] Examples of rubber skeletons having the above-mentioned amino groups include isoprene-based rubbers, BR, SBR, SIBR, EPDM, CR, NBR, and other diene-based rubbers. Among these, BR and SBR are preferred, with SBR being more preferred, from the viewpoint of obtaining better effects.

[0058] In the above rubber composition, the content of the rubber having the above amino group in 100% by mass of the rubber component is preferably 20% by mass or more, more preferably 40% by mass or more, even more preferably 60% by mass or more, even more preferably 70% by mass or more, and also preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less. When the content is within the above range, the effect tends to be better obtained. On the other hand, from the viewpoint of wear resistance, it is preferably 70% by mass or less.

[0059] The above rubber composition contains silica as a filler. In the above rubber composition, the silica that can be used is not particularly limited, and common silica used in the tire industry can be used, such as silica prepared by a dry process (anhydrous silica) or silica prepared by a wet process (hydrated silica). The raw material for silica is not particularly limited, and may be a mineral-derived raw material such as quartz, or a biological-derived raw material such as rice husks (for example, silica made from biomass materials such as rice husks), or silica recycled from silica-containing products may be used. Among these, hydrated silica prepared by a wet process is preferred because it has many silanol groups and many reaction sites with silane coupling agents. These silicas may be used individually or in combination of two or more types.

[0060] Silica derived from biomass materials can be obtained, for example, by extracting silicates from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and then using these silicates to react with sulfuric acid in the same way as conventional wet silica, the precipitate of silicon dioxide is filtered, washed with water, dried, and pulverized.

[0061] The silica recycled from silica-containing products can be, for example, silica recovered from products containing silica such as semiconductors and other electronic components, tires, desiccants, and diatomaceous earth and other filter materials. The recovery method is not particularly limited and can include thermal decomposition and decomposition by electromagnetic waves. Among these, silica recovered from semiconductors and other electronic components or tires is preferred.

[0062] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and combustion time, the crystallization of silica in rice husk ash can be suppressed (see Japanese Patent Publication No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol.6, pp.216-222, etc.).

[0063] Amorphous silica extracted from rice husks can be commercially available from companies such as Wilmar.

[0064] The N2SA (nitrogen adsorption specific surface area) of silica is preferably 130 m². 2 / g or more, more preferably 160m 2 It is 130m or more. N2SA is 130m 2 If the value is less than / g, the necessary rubber reinforcement for the tire cannot be secured, and the fracture strength and wear resistance cannot be ensured. Furthermore, the silica N2SA is preferably 300m 2 / g or less, more preferably 260m 2 It is less than / g. N2SA is 300m 2 If the value exceeds [amount] / g, the processability deteriorates and processing becomes difficult. Note that the N2SA value of silica is measured by the BET method in accordance with ASTM D3037-93.

[0065] The average particle size of silica is preferably 24 nm or less, more preferably 22 nm or less, even more preferably 20 nm or less, and even more preferably 17 nm or less, and also preferably 6 nm or more, more preferably 9 nm or more, and even more preferably 12 nm or more. Within the above range, a better effect tends to be obtained.

[0066] In this specification, the method for measuring the average particle size of silica is transmission electron microscopy (TEM) observation. Specifically, silica particles are photographed with a transmission electron microscope, and if the particle shape is spherical, the diameter of the sphere is defined as the particle size; if it is needle-shaped or rod-shaped, the shorter axis is defined as the particle size; if it is irregularly shaped, the average particle size from the center is defined as the particle size; and the average particle size of 100 fine particles is defined as the average particle size.

[0067] The above rubber composition may contain fillers other than silica. Other fillers are 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, as well as water-soluble fillers, biochar, and poorly dispersible fillers. These may be used individually or in combination of two or more. Among these, carbon black is preferred.

[0068] The carbon blacks mentioned above are not particularly limited and include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The raw materials for carbon black may be biomass materials such as lignin and vegetable oil, or pyrolysis oil obtained by thermal decomposition of waste tires. The manufacturing method for carbon black may be combustion such as the furnace method, hydrothermal carbonization (HTC), or thermal decomposition of methane such as the thermal black method. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., Columbia Carbon Corporation, etc. Carbon black may be used alone or in combination of two or more types.

[0069] N2SA carbon black is 50m 2 Preferably 80m / g or more. 2 More preferably 110m / g or more, 2 A value of 1 / g or more is even more preferable. Furthermore, the above CTAB is 200m2 Preferably less than / g, 180m 2 More preferably less than / g, 160m 2 A value of less than / g is even more preferable. Within the above range, there is a tendency to obtain better effects. Furthermore, the N2SA of carbon black is determined according to JIS K6217-2:2001.

[0070] The median particle size (median diameter, D50) of the water-soluble filler is preferably 0.4 μm or larger, more preferably 0.6 μm or larger, and even more preferably 1.0 μm or larger. The upper limit is preferably 200 μm or smaller, more preferably 150 μm or smaller, even more preferably 50 μm or smaller, and particularly preferably 20 μm or smaller. Within the above range, better effects tend to be obtained. In this specification, the median particle size of a water-soluble filler can be measured by laser diffraction, and refers to the particle size of the 50% integrated value in the mass-based particle size distribution curve obtained by laser diffraction scattering. The median particle size of water-soluble fillers is measured by the following method. [Measurement of median particle size (median diameter) of water-soluble fillers] The measurement will be performed using the SALD-2000J model manufactured by Shimadzu Corporation, employing the laser diffraction method. The operating procedure is as follows: <Measurement Procedure> A water-soluble filler is dispersed at room temperature in a mixed solution of a dispersion solvent (toluene) and a dispersant (10% by mass of di-2-ethylhexyl sodium sulfosuccinate / toluene solution). The resulting dispersion is stirred for 5 minutes while being irradiated with ultrasound to obtain a test solution. The test solution is transferred to a batch cell and measured after 1 minute. (Refractive index: 1.70-0.20i)

[0071] Examples of water-soluble fillers include water-soluble inorganic salts and water-soluble organic substances. These may be used individually or in combination of two or more.

[0072] Examples of water-soluble inorganic salts include metal sulfates such as magnesium sulfate, sodium sulfate, and potassium sulfate; metal chlorides such as potassium chloride, sodium chloride, calcium chloride, and magnesium chloride; metal hydroxides such as potassium hydroxide and sodium hydroxide; carbonates such as potassium carbonate, sodium carbonate, and calcium bicarbonate; and phosphates such as sodium hydrogen phosphate and sodium dihydrogen phosphate.

[0073] Examples of water-soluble organic substances include lignin derivatives and sugars. Suitable lignin derivatives include lignin sulfonic acid and lignin sulfonate salts. The lignin derivative may be obtained by either the sulfite pulp method or the kraft pulp method.

[0074] Examples of ligninsulfonates include alkali metal salts, alkaline earth metal salts, ammonium salts, and alcoholamine salts of ligninsulfonic acid. Among these, alkali metal salts (potassium salts, sodium salts, etc.) and alkaline earth metal salts (calcium salts, magnesium salts, lithium salts, barium salts, etc.) of ligninsulfonic acid are preferred.

[0075] The lignin derivative preferably has a sulfonation degree of 1.5 to 8.0 / OCH3. In this case, the lignin derivative includes ligninsulfonic acid and / or ligninsulfonate salts in which at least a portion of lignin and / or its decomposition products are substituted with sulfon groups (sulfonated groups), and the sulfon groups of the ligninsulfonic acid may be in an unionized state, or the hydrogen of the sulfon group may be substituted with an ion such as a metal ion. The sulfonation degree is more preferably 3.0 to 6.0 / OCH3. The effect tends to be more favorably obtained by keeping it within the above range.

[0076] The degree of sulfonation of lignin derivative particles (the lignin derivatives that constitute the particles) is the rate of introduction of sulfo groups and can be calculated using the following formula. Sulfonation degree ( / OCH3) = S (moles) in the sulfone group in the lignin derivative / methoxyl group (moles) in the lignin derivative

[0077] Sugars have no particular restrictions on the number of carbon atoms they consist of and can be monosaccharides, oligosaccharides, or polysaccharides. Examples of monosaccharides include trisaccharides such as aldotrioose and ketotriose; tetrasaccharides such as erythrose and threose; pentoses such as xylose and ribose; hexoses such as mannose, allose, altrose, and glucose; and heptasaccharides such as sedoheptulose. Examples of oligosaccharides include disaccharides such as sucrose and lactose; trisaccharides such as raffinose and melegitose; tetrasaccharides such as acarbose and stachyose; and oligosaccharides such as xylooligosaccharides and cellooligosaccharides. Examples of polysaccharides include glycogen, starch (amylose, amylopectin), cellulose, hemicellulose, dextrin, and glucan.

[0078] Among water-soluble fillers, water-soluble inorganic salts are preferred, metal sulfates are more preferred, and magnesium sulfate is even more preferred. Among magnesium sulfates, anhydrous magnesium sulfate, magnesium sulfate dihydrate, and magnesium sulfate trihydrate are preferred, and anhydrous magnesium sulfate is more preferred.

[0079] It is presumed that when the above rubber composition contains a water-soluble filler, the overall performance, including fuel efficiency during city driving and lane change performance during high-speed driving, tends to improve.

[0080] Examples of the poorly dispersible fillers mentioned above include short fibers and gel-like compounds. Among these, short fibers are preferred.

[0081] Examples of short fibers that can be used include organic short fibers and inorganic short fibers. Specific examples of organic short fibers include nanocellulose such as cellulose nanofibers (CNF) and cellulose nanocrystals (CNC); biomass nanomaterials such as chitin nanofibers and chitosan nanofibers; and specific examples of inorganic short fibers include metal fibers and glass fiber systems. Commercially available products include those from Nippon Paper Industries Co., Ltd. and Sugino Machine Co., Ltd. These may be used individually or in mixtures of two or more. Among these, organic short fibers are preferred, and nanocellulose is more preferred.

[0082] The particle size of the nanocellulose is preferably 10 nm or larger, more preferably 20 nm or larger, even more preferably 25 nm or larger, and particularly preferably 28 nm or larger. It is also preferably 50 nm or smaller, more preferably 40 nm or smaller, even more preferably 35 nm or smaller, and particularly preferably 32 nm or smaller. When the particle size is within the above range, a better effect tends to be obtained.

[0083] The particle size of nanocellulose is the average fiber diameter measured by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X-ray scattering data analysis, and pore electrical resistance method (Culter principle method). In this specification, the average fiber diameter of nanocellulose (cellulose fiber) is typically the average fiber diameter of an aggregate of cellulose fibers formed by the aggregation of cellulose molecules.

[0084] In the above rubber composition, the filler content (total amount of fillers such as silica and carbon black) is preferably 60 parts by mass or more, more preferably 65 parts by mass or more, even more preferably 80 parts by mass or more, even more preferably 100 parts by mass or more, and even more preferably 130 parts by mass or more, per 100 parts by mass of the rubber component, and also preferably 200 parts by mass or less, more preferably 180 parts by mass or less, and even more preferably 160 parts by mass or less. When the content is within the above range, a better effect tends to be obtained. On the other hand, from the viewpoint of fuel efficiency, the amount is preferably 130 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 65 parts by mass or less.

[0085] In the above rubber composition, the silica content is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 55 parts by mass or more, even more preferably 90 parts by mass or more, and even more preferably 120 parts by mass or more. If the silica content is less than 5 parts by mass, the necessary reinforcing properties for the tire cannot be obtained. Furthermore, the silica content is preferably 200 parts by mass or less, more preferably 180 parts by mass or less, and even more preferably 150 parts by mass or less. If the silica content exceeds 200 parts by mass, the processability deteriorates and processing becomes difficult. On the other hand, from the viewpoint of fuel efficiency, the amount is preferably 120 parts by mass or less, more preferably 90 parts by mass or less, and even more preferably 55 parts by mass or less.

[0086] When the above rubber composition contains carbon black, the carbon black content is preferably 3 parts by mass or more, more preferably 6 parts by mass or more, even more preferably 10 parts by mass or more, and also preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0087] In the above rubber composition, the carbon black content / silica content ratio is preferably 0.25 or less, more preferably 0.15 or less, even more preferably 0.10 or less, and also preferably 0.04 or more, more preferably 0.06 or more, and even more preferably 0.08 or more. When the ratio is within the above range, a better effect tends to be obtained. In this context, the carbon black and silica content are expressed as the content per 100 parts by mass of rubber component (unit: parts by mass).

[0088] When the above rubber composition contains a water-soluble filler, the content of the water-soluble filler is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and also preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. When the content is within the above range, a better effect tends to be obtained. On the other hand, from the viewpoint of improving wear resistance, the amount is preferably 10 parts by mass or less, more preferably 5 parts by mass or less.

[0089] When the above rubber composition contains a poorly dispersible filler, the content of the poorly dispersible filler is preferably 1 part by mass or more, more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component. The above content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0090] The above rubber composition contains an ionic coupling agent. As an ionic coupling agent, any material having a site that can react with silica and a site that can form ionic bonds can be used, for example, a site that reacts with silanol groups on the silica surface, such as OCR. 1 (R 1 A compound having a moiety represented by (where represents a monovalent organic group) and an ionic functional group is preferred. The above ionic functional group is not particularly limited as long as it is a functional group containing anionic or cationic species, but for example, sulfate ester base (-OSO3 - X + ), sulfonic acid base (-SO3 - X + ), phosphate ester base (-OPO(O - X + )2) Phosphosphate base (-PO(O - X + 2) Carboxylic acid base (-COO - X + ), boronic acid base (-B(O - X + )2) anionic groups such as (X +represents a cation. ), quaternary ammonium group (-(NR 35 R 36 R 37 ) + Y - )(wherein, R 35 ~R 37 This will be discussed later. ) Cationic groups (Y - ) represents an anion. Examples include ). The above ionic coupling agent may have one of these ionic functional groups or two or more. The above X + The cation represented by may be an organic ion or an inorganic ion, and is not particularly limited, but examples include metal ions such as lithium ions, sodium ions, and potassium ions, and ammonium groups. - The anion represented by may be an organic ion or an inorganic ion, and is not particularly limited, but examples include chloride ions, as described later.

[0091] In particular, the ionic coupling agent is preferably at least one selected from the group consisting of a compound represented by the following formula (1), a hydrolysate of the compound represented by the following formula (1), and a hydrolyzed condensate of the compound represented by the following formula (1).

[0092] [ka]

[0093] In formula (1), R 31 and R 32 Each of these independently represents a monovalent organic group. 33 and R 34Each of these independently represents an organic group having a group selected from the group consisting of alkyl groups, vinyl groups, epoxy groups, styryl groups, (meth)acrylic groups, amino groups, isocyanurate groups, ureido groups, mercapto groups, sulfide groups, polyalkylene oxyalkyl groups, carboxyl groups, sulfate ester bases, sulfonic acid bases, phosphate ester bases, phosphonic acid bases, carboxylic acid bases, boronic acid bases, and quaternary ammonium groups, and the above R 34 At least one of the groups is an organic group having a group selected from the group consisting of sulfate ester bases, sulfonic acid bases, phosphate ester bases, phosphonic acid bases, carboxylic acid bases, boronic acid bases, and quaternary ammonium groups. m independently represents an integer from 0 to 2. n represents an integer. In this specification, an organic group means a group having one or more carbon atoms.

[0094] The hydrolysate of the compound represented by formula (1) is a compound in which at least some of the substituents on the silicon atom of the compound represented by formula (1) have been hydrolyzed to form a silanol group. Furthermore, the hydrolysis condensate of the compound represented by formula (1) is a compound obtained by the condensation of two or more compounds selected from the group consisting of the compound represented by formula (1) and the hydrolysis product of the compound represented by formula (1).

[0095] In formula (1), m is preferably 1 or 2, and more preferably 2. In equation (1), n ​​is preferably an integer between 2 and 20.

[0096] R in equation (1) 31 and R 32 The monovalent organic group preferably has 1 to 6 carbon atoms. R 31 and R 32The C1-C6 organic group in the formula may be linear, branched, or have a cyclic structure. Examples of C1-C6 organic groups include alkyl groups and alkenyl groups, with alkyl groups being preferred. Examples of C1-C6 alkyl groups include methyl, ethyl, propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, n-hexyl, and cyclohexyl groups.

[0097] R in equation (1) 31 and R 32 Each of these is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, even more preferably a methyl group or an ethyl group, and particularly preferably a methyl group.

[0098] R in equation (1) 33 Each of these is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, even more preferably a methyl group or an ethyl group, and particularly preferably a methyl group.

[0099] R in equation (1) 34 Preferably, at least one of the organic groups has a quaternary ammonium group. Examples of groups having a quaternary ammonium group include the group represented by the following formula. [ka]

[0100] In the formula, R 35 ~R 37 Each of these independently represents a monovalent organic group. 38 Each of these independently represents a divalent organic group. - k represents an anion. k represents an integer.

[0101] R 35 ~R 37Examples of the monovalent organic group include monovalent hydrocarbon groups, and examples of the monovalent hydrocarbon groups include alkyl groups having 1 to 18 carbon atoms, alkenyl groups having 2 to 12 carbon atoms, and the like. R 35 ~R 37 The number of carbon atoms of ~R is preferably 1 to 12, more preferably 1 to 7, still more preferably 1 to 5, and particularly preferably 1 to 3. R 35 ~R 37 The monovalent organic group of ~R is particularly preferably a methyl group or an ethyl group.

[0102] R 38 Examples of the divalent organic group of R include divalent hydrocarbon groups, and examples of the divalent hydrocarbon groups include alkylene groups having 1 to 12 carbon atoms, alkenylene groups having 2 to 12 carbon atoms, and the like. R 38 The number of carbon atoms of R is preferably 1 to 12, more preferably 1 to 7, still more preferably 1 to 5, and particularly preferably 1 to 3. R 38 The divalent organic group of R is particularly preferably a methylene group or an ethylene group.

[0103] k is preferably 0 to 5, more preferably 0 to 3, still more preferably 0 to 1, and particularly preferably 0.

[0104] Y -is not particularly limited, and examples thereof include halide ions (chloride ions, bromide ions, iodide ions, etc.); carboxylate ions (formate ions, acetate ions, trifluoroacetate ions, lactate ions, propionate ions, benzoate ions, oxalate ions, succinate ions, stearate ions, etc.); methyl sulfate ions (alkyl sulfate ions, etc.); sulfonate ions (methanesulfonate ions, benzenesulfonate ions, trifluoromethanesulfonate ions, toluenesulfonate ions, naphthalenesulfonate ions, nitrobenzenesulfonate ions, dodecylbenzenesulfonate ions, ethanesulfonate ions, etc.); sulfonimide ions (bis(trifluoromethanesulfonate)imide ions, etc.); borate ions (tetrafluoroborate ions, tetraphenylborate ions, butyltriphenylborate ions, etc.); phosphate ions (hexafluorophosphate ions, etc.); antimonate ions (hexafluoroantimonate ions, etc.); arsenate ions (hexafluoroarsenate ions, etc.); perhalate ions (perchlorate ions, periodate ions, etc.); thiocyanate ions, nitrate ions, and the like.

[0105] Among the compound represented by the above formula (1), the hydrolyzate of the compound represented by the above formula (1), and the hydrolysis condensate of the compound represented by the above formula (1), from the viewpoint of obtaining better effects, the compound represented by the following formula (1-1) is desirable.

[0106]

Chemical formula

[0107] In formula (1-1), R 35 ~R 37 each independently represents the same group as the above R 35 ~R 37 R 38 each independently represents the same group as the above R 38 Y - each independently represents the same anion as the above Y - k each independently represents the same integer as the above k.

[0108] In equation (1-1), R 35 ~R 37 , R 38 , Y - The preferred example of k is the same as described above.

[0109] The ionic coupling agent mentioned above can be a commercially available product such as X-12-1126 or KBM-9418-40 manufactured by Shin-Etsu Chemical Co., Ltd.

[0110] In the above rubber composition, the total content of the ionic coupling agent is preferably 2 parts by mass or more, more preferably 5.5 parts by mass or more, even more preferably 9 parts by mass or more, and even more preferably 12 parts by mass or more, per 100 parts by mass of the rubber component, and also preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less. When the content is within the above range, a better effect tends to be obtained. On the other hand, from the viewpoint of wear resistance, the amount is preferably 12 parts by mass or less, more preferably 9 parts by mass or less, and even more preferably 5.5 parts by mass or less.

[0111] If the above rubber composition contains silica, it is preferable that it further contains a silane coupling agent. The silane coupling agent is not particularly limited and any known in the rubber field can be used, 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, Examples include sulfide-based compounds such as N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and Momentive's NXT and NXT-Z; vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based 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.

[0112] In addition to compounds containing a mercapto group, compounds in which the mercapto group is protected by a protecting group (for example, compounds represented by the following formula (S1)) can also be used as mercapto-silane coupling agents.

[0113] Particularly suitable mercapto-silane coupling agents include silane coupling agents represented by the following formula (S1), and silane coupling agents containing a bonding unit A shown in the following formula (I) and a bonding unit B shown in the following formula (II). [ka] (In the formula, R 1001 -Cl, -Br, -OR 1006 -O(O=)CR 1006 , -ON=CR 1006 R 1007 , -NR 1006 R 1007 and -(OSiR 1006 R 1007 ) h (OSiR 1006 R 1007 R 1008 A monovalent group (R) selected from ) 1006 , R 1007 and R 1008 They may be the same or different, and each is a hydrogen atom or a monovalent hydrocarbon group with 1 to 18 carbon atoms, and the average value of h is 1 to 4. 1002 is R 1001 , hydrogen atom or monovalent hydrocarbon group having 1 to 18 carbon atoms, R 1003 is -[O(R 1009 O) j ]-group(R 1009 is an alkylene group with 1 to 18 carbon atoms, and j is an integer from 1 to 4. ), R 1004 R is a divalent hydrocarbon group having 1 to 18 carbon atoms. 1005 (where represents a monovalent hydrocarbon group with 1 to 18 carbon atoms, and x, y, and z are numbers that satisfy the relationships x + y + 2z = 3, 0 ≤ x ≤ 3, 0 ≤ y ≤ 2, and 0 ≤ z ≤ 1.) [ka] [ka] (In the formula, v is a non-negative integer and w is a non-negative integer. 11 R represents hydrogen, halogen, branched or unbranched C1-C30 alkyl group, branched or unbranched C2-C30 alkenyl group, branched or unbranched C2-C30 alkynyl group, or an alkyl group in which the terminal hydrogen is substituted with a hydroxyl group or a carboxyl group. 12 R represents a branched or unbranched alkylene group having 1 to 30 carbon atoms, a branched or unbranched alkenylene group having 2 to 30 carbon atoms, or a branched or unbranched alkynylene group having 2 to 30 carbon atoms. 11 and R 12 (They may form a ring structure.)

[0114] In equation (S1), R 1005 , R 1006 , R 1007 and R 1008 Each of these is preferably independently selected from the group consisting of linear, cyclic, or branched alkyl groups, alkenyl groups, aryl groups, and aralkyl groups having 1 to 18 carbon atoms. 1002 If is a monovalent hydrocarbon group having 1 to 18 carbon atoms, it is preferably a group selected from the group consisting of linear, cyclic, or branched alkyl groups, alkenyl groups, aryl groups, and aralkyl groups. 1009 The alkylene group is preferably linear, cyclic, or branched, and is particularly preferred to be linear. 1004 Examples of these include alkylene groups having 1 to 18 carbon atoms, alkenylene groups having 2 to 18 carbon atoms, cycloalkylene groups having 5 to 18 carbon atoms, cycloalkylalkylene groups having 6 to 18 carbon atoms, arylene groups having 6 to 18 carbon atoms, and aralkylene groups having 7 to 18 carbon atoms. The alkylene groups and alkenylene groups may be linear or branched, and the cycloalkylene groups, cycloalkylalkylene groups, arylene groups, and aralkylene groups may have functional groups such as lower alkyl groups on their rings. 1004Preferably, the alkylene group has 1 to 6 carbon atoms, and in particular, linear alkylene groups such as methylene, ethylene, trimethylene, tetramethylene, pentamethylene, and hexamethylene groups are preferred.

[0115] R in equation (S1) 1002 , R 1005 , R 1006 , R 1007 and R 1008 Specific examples include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, cyclopentyl group, cyclohexyl group, vinyl group, propenyl group, allyl group, hexenyl group, octenyl group, cyclopentenyl group, cyclohexenyl group, phenyl group, tolyl group, xylyl group, naphthyl group, benzyl group, phenethyl group, naphthylmethyl group, and the like. R in equation (S1) 1009 Examples of linear alkylene groups include methylene, ethylene, n-propylene, n-butylene, and hexylene groups, while examples of branched alkylene groups include isopropylene, isobutylene, and 2-methylpropylene groups.

[0116] Specific examples of silane coupling agents represented by formula (S1) include 3-hexanoylthiopropyltriethoxysilane, 3-octanoylthiopropyltriethoxysilane, 3-decanoylthiopropyltriethoxysilane, 3-lauroylthiopropyltriethoxysilane, 2-hexanoylthioethyltriethoxysilane, 2-octanoylthioethyltriethoxysilane, 2-decanoylthioethyltriethoxysilane, 2-lauroylthioethyltriethoxysilane, 3-hexanoylthiopropyltrimethoxysilane, 3-octanoylthiopropyltrimethoxysilane, 3-decanoylthiopropyltrimethoxysilane, 3-lauroylthiopropyltrimethoxysilane, 2-hexanoylthioethyltrimethoxysilane, 2-octanoylthioethyltrimethoxysilane, 2-decanoylthioethyltrimethoxysilane, and 2-lauroylthioethyltrimethoxysilane. These may be used individually or in combination of two or more. Among them, 3-octanoylthiopropyltriethoxysilane is particularly preferred.

[0117] In a silane coupling agent containing a bonding unit A represented by formula (I) and a bonding unit B represented by formula (II), the content of bonding unit A is preferably 30 mol% or more, more preferably 50 mol% or more, preferably 99 mol% or less, and more preferably 90 mol% or less. The content of bonding unit B is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 10 mol% or more, preferably 70 mol% or less, more preferably 65 mol% or less, and even more preferably 55 mol% or less. The total content of bonding units A and B is preferably 95 mol% or more, more preferably 98 mol% or more, and particularly preferably 100 mol%. The content of bonding units A and B includes the amount when bonding units A and B are located at the ends of the silane coupling agent. The form of bonding units A and B when they are located at the ends of the silane coupling agent is not particularly limited, as long as they form units corresponding to formulas (I) and (II) that represent bonding units A and B.

[0118] R in equations (I) and (II)11 Examples of halogens include chlorine, bromine, and fluorine. Examples of branched or unbranched alkyl groups with 1 to 30 carbon atoms include methyl and ethyl groups. Examples of branched or unbranched alkenyl groups with 2 to 30 carbon atoms include vinyl and 1-propenyl groups. Examples of branched or unbranched alkynyl groups with 2 to 30 carbon atoms include ethynyl and propynyl groups.

[0119] R in equations (I) and (II) 12 Regarding branched or unbranched alkylene groups with 1 to 30 carbon atoms, examples include ethylene and propylene groups. Regarding branched or unbranched alkenylene groups with 2 to 30 carbon atoms, examples include vinylene and 1-propenylene groups. Regarding branched or unbranched alkylene groups with 2 to 30 carbon atoms, examples include ethynylene and propynylene groups.

[0120] In a silane coupling agent containing a bonding unit A represented by formula (I) and a bonding unit B represented by formula (II), the sum of the number of repeats of bonding unit A (v) and the number of repeats of bonding unit B (w), (v+w), is preferably in the range of 3 to 300.

[0121] In the above rubber composition, the content of the silane coupling agent is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 4 parts by mass or more, and preferably 16 parts by mass or less, more preferably 12 parts by mass or less, and even more preferably 8 parts by mass or less, per 100 parts by mass of silica. When the content is within the above range, a better effect tends to be obtained.

[0122] In the above rubber composition, the content of the silane coupling agent is preferably 2 parts by mass or more, more preferably 4 parts by mass or more, even more preferably 6 parts by mass or more, and even more preferably 7 parts by mass or more, per 100 parts by mass of the rubber having an amino group, and also preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0123] The above rubber composition preferably contains a softening agent. In this specification, "softener" refers to a material that imparts softening properties to rubber components, and is a concept that includes both liquid softeners and solid softeners under conditions of 1 atmosphere and 25°C. Examples of softeners include resins, oils, liquid rubbers, and ester-based softeners. Among these, oils and liquid rubbers are preferred. These softeners may be derived from mineral resources such as petroleum and natural gas, from biomass, or from naphtha recycled from rubber or non-rubber products. Alternatively, low molecular weight hydrocarbon components obtained by thermal decomposition and extraction of used tires or products containing various components may be used as softeners. These softeners may be used individually or in combination of two or more.

[0124] Resin is a material that imparts plasticity to rubber components, and the concept includes both liquid resins and solid resins under the same conditions of 1 atmosphere and 25°C. The resin may be used alone, or two or more types may be used in combination. In this specification, resin and rubber (rubber component or liquid rubber) are considered different materials.

[0125] The resin is not particularly limited, but resins commonly used in the tire industry can be used. Examples include adhesive resins such as C5 resins, C9 resins, C5C9 resins, aromatic vinyl resins, dicyclopentadiene resins, coumarone resins, indene resins, terpene resins, rosin resins, and phenolic resins. These resins may be used individually or in combination of two or more.

[0126] C5 resins refer to resins obtained by polymerizing C5 fractions, and may be hydrogenated or modified versions of these resins. Examples of C5 fractions include petroleum fractions with 4 to 5 carbon atoms, such as cyclopentadiene, isoprene, pentane, isopentane, neopentane, pentene, and pentadiene. These C5 resins may be used individually or in combination of two or more types.

[0127] C9 resins refer to resins obtained by polymerizing a C9 fraction, and may be obtained by polymerizing the C9 fraction alone, or as copolymers obtained by copolymerizing the C9 fraction with other components. They may also be hydrogenated or modified. Examples of C9 fractions include petroleum fractions with 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, coumarone, indene, and methylindene. These C9 resins may be used individually or in combination of two or more types.

[0128] C5C9 resins refer to resins obtained by copolymerizing the C5 fraction and the C9 fraction, and may be hydrogenated or modified versions of these resins. As C5C9 petroleum resins, for example, those commercially available from Tosoh Corporation, LUHUA, etc., can be used. These C5C9 resins may be used individually or in combination of two or more types.

[0129] Aromatic vinyl resins refer to resins containing aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and p-chlorostyrene as the most abundant monomer component, and may also be hydrogenated or modified versions of these compounds. For aromatic vinyl resins, α-methylstyrene or a homopolymer of styrene, or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred, due to their economical nature, ease of processing, and excellent heat generation properties. Aromatic vinyl resins that can be used are commercially available from companies such as Kraton, Eastman Chemical Company, and Mitsui Chemicals, Inc. These aromatic vinyl resins may be used individually or in combination of two or more types.

[0130] Dicyclopentadiene resins refer to resins containing cyclopentadiene (CPD) or dicyclopentadiene (DCPD) as monomer components, and may be hydrogenated or modified. Examples of dicyclopentadiene resins include DCPD / C9 resins containing dicyclopentadiene and C9 fraction as monomer components (these DCPD / C9 resins may be hydrogenated or modified), with DCPD / C9 resins containing dicyclopentadiene and styrene as monomer components being preferred, and DCPD / C9 resins containing dicyclopentadiene, styrene, and indene as monomer components being particularly preferred. Dicyclopentadiene resins that are commercially available from companies such as ExxonMobil, ENEOS Corporation, Nippon Zeon Corporation, and Maruzen Petrochemical Co., Ltd. can be used. These dicyclopentadiene resins may be used individually or in combination of two or more types.

[0131] Coumarone-based resins refer to resins containing coumarone as a monomer component, and may be hydrogenated or modified resins. Examples of coumarone resins include coumarone-indene resins containing coumarone and indene as monomer components, and coumarone-indene-styrene resins containing coumarone, indene, and styrene as monomer components. These coumarone-based resins may be used individually or in combination of two or more types.

[0132] Indene resins refer to resins containing indene as a monomer component, and may be hydrogenated or modified resins. Examples of indene resins include coumarone-indene resins containing coumarone and indene as monomer components, and coumarone-indene-styrene resins containing coumarone, indene, and styrene as monomer components. These indene resins may be used individually or in combination of two or more types.

[0133] Terpene resins are resins that contain terpene compounds such as α-pinene, β-pinene, limonene, and dipentene as the most abundant monomer component, and may be hydrogenated or modified versions of these compounds. Specific examples of terpene resins include, for example, polyterpene resins containing only one or more of the aforementioned terpene compounds as monomer components; aromatically modified terpene resins containing the aforementioned terpene compounds and aromatic compounds as monomer components; and terpene-phenol resins containing the aforementioned terpene compounds and phenolic compounds as monomer components. Examples of aromatic compounds that serve as monomer components in aromatically modified terpene resins include styrene, α-methylstyrene, vinyltoluene, and divinyltoluene. Examples of phenolic compounds that serve as monomer components in terpene-phenol resins include phenol, bisphenol A, cresol, and xylenol. These terpene resins may be used individually or in combination of two or more types.

[0134] Rosin-based resins refer to resins containing rosin acid compounds such as abietic acid, neoabietic acid, palastic acid, and isopimal acid, and may be hydrogenated or modified versions of these compounds. Rosin-based resins are not particularly limited, but examples include natural resin rosin and rosin-modified resins obtained by hydrogenation, disproportionation, dimerization, esterification, etc. These rosin-based resins may be used individually or in combination of two or more types.

[0135] Phenolic resins are resins that contain phenol compounds such as phenol and cresol as the most abundant monomer component. Phenolic resins are not particularly limited, but examples include phenol-formaldehyde resins, alkylphenol-formaldehyde resins, alkylphenol-acetylene resins, and oil-modified phenol-formaldehyde resins. These phenolic resins may be used individually or in combination of two or more types.

[0136] The resin may be a modified resin (functionalized resin) into which functional groups have been introduced. Modified resins can be produced by known methods, such as slurry methods and metathesis methods. Specifically, they can be produced, for example, by reacting a polymer that forms the polymer backbone of the modified resin with a functional compound that allows for the introduction of functional groups, using known methods.

[0137] The polymer forming the polymer backbone is not particularly limited and may be, for example, the C5 resin, aromatic resin, or terpene resin mentioned above, or other resins. These may be used alone or in combination of two or more. Among these, aromatic resins are preferred, α-methylstyrene resins are more preferred, and styrene-α-methylstyrene resin (a copolymer of styrene and α-methylstyrene) is even more preferred.

[0138] The functional group is preferably one containing at least one element selected from the group consisting of oxygen, silicon, and nitrogen, and more preferably one containing silicon.

[0139] Commercially available resins from companies such as Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nippon Paint Chemical Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Industries, Ltd. can be used.

[0140] Examples of oils include mineral oil, vegetable oil, and animal oil. Furthermore, from a life cycle assessment perspective, refined waste oil from rubber mixers and engines, or waste cooking oil from restaurants, may also be used. Vegetable oil is particularly preferred.

[0141] In this specification, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oils (mineral oil), naphthenic oils, and aromatic oils. Specific examples of mineral oil include MES (Mild Extract Sollvates), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), and RAE (Residual Aromatic Extract). Furthermore, for environmental reasons, oils with a low content of polycyclic aromatic compounds (PCA) can be used. Examples of such low-PCA oils include MES, TDAE, and heavy naphthenic oils.

[0142] In this specification, vegetable oils include, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grapeseed oil, and wood wax. Furthermore, vegetable oils may also include refined oils obtained by refining the above oils (such as salad oil), transesterified oils obtained by transesterifying the above oils, hydrogenated oils obtained by hydrogenating the above oils, thermally polymerized oils obtained by thermally polymerizing the above oils, oxidized polymerized oils obtained by oxidizing the above oils, and waste cooking oils recovered from use as edible oils. Note that vegetable oils may be liquid or solid at 25°C. These vegetable oils may be used individually or in combination of two or more types.

[0143] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably contains triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxyl group of glycerin and a fatty acid are ester-bonded. The acylglycerol is not particularly limited and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Furthermore, the acylglycerol may be a monomer, a dimer, or a polymer of three or more. Note that acylglycerols of two or more forms can be obtained by thermal polymerization, oxidative polymerization, etc. Also, the acylglycerol may be a liquid or a solid at 25°C.

[0144] The method for confirming whether the rubber composition contains the acylglycerol is not particularly limited, 1 This can be confirmed by 1H-NMR measurement. For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at 25°C for 24 hours, and after removing the rubber composition, it is measured at room temperature. 1When 1H-NMR was measured and the tetramethylsilane (TMS) signal was set to 0.00 ppm, signals were observed around 5.26 ppm, 4.28 ppm, and 4.15 ppm. These signals are presumed to originate from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In this paragraph, "around" refers to a range of ±0.10 ppm.

[0145] The aforementioned fatty acids are not particularly limited and may be either unsaturated or saturated fatty acids. Examples of unsaturated fatty acids include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of saturated fatty acids include butyric acid and lauric acid.

[0146] In particular, it is desirable that the fatty acid contains fatty acids with few double bonds, i.e., saturated fatty acids or monounsaturated fatty acids, and oleic acid is preferred. As a vegetable oil containing such fatty acids, for example, a vegetable oil containing saturated fatty acids or monounsaturated fatty acids may be used, or a vegetable oil that has been modified by transesterification or other means may be used. Furthermore, in order to produce a vegetable oil containing such fatty acids, plants may be improved by breeding, genetic modification, genome editing, etc.

[0147] As for the oil, commercially available products from companies such as Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kosan Co., Ltd., and Nisshin Oillio Group Ltd. can be used.

[0148] As the liquid rubber, at least one diene-based (co)polymer selected from the group consisting of butadiene, isoprene, styrene, farnesene, and their derivatives can be used. Specific examples include liquid diene-based polymers 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 farnesene polymer, and liquid farnesene-butadiene copolymer. Among these, liquid IR is preferred.

[0149] The liquid rubber may be modified with functional groups that interact with silica, or its terminals and / or main chain may be modified with functional groups containing at least one element selected from the group consisting of oxygen, nitrogen, silicon, and phosphorus. The liquid rubber may also be unhydrogenated or hydrogenated.

[0150] In the above rubber composition, the content of the softening agent (total amount of softening agent such as resin and liquid rubber) is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, and even more preferably 47 parts by mass or more, per 100 parts by mass of the rubber component, and also preferably 80 parts by mass or less, more preferably 65 parts by mass or less, and even more preferably 55 parts by mass or less. When the content is within the above range, a better effect tends to be obtained. On the other hand, from the viewpoint of wear resistance, the amount is preferably 47 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less.

[0151] In the above rubber composition, the ratio of the softening agent content to the filler content is preferably 0.10 or higher, more preferably 0.20 or higher, even more preferably 0.30 or higher, and even more preferably 0.35 or higher. Furthermore, it is preferably 0.90 or lower, more preferably 0.70 or lower, and even more preferably 0.50 or lower. When the ratio is within the above range, a better effect tends to be obtained. In this relationship, the content of softeners and fillers is expressed as the content per 100 parts by mass of rubber components (unit: parts by mass).

[0152] When the above rubber composition contains a solid softener in a solid state under conditions of 1 atmosphere and 25°C, the content of the solid resin is preferably 1 to 60 parts by mass per 100 parts by mass of the rubber component.

[0153] When the above rubber composition contains a liquid softener in a liquid state under conditions of 1 atmosphere and 25°C, the content of the liquid softener is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, and even more preferably 47 parts by mass or more, per 100 parts by mass of the rubber component, and also preferably 80 parts by mass or less, more preferably 65 parts by mass or less, and even more preferably 55 parts by mass or less. When the content is within the above range, a better effect tends to be obtained. Furthermore, the liquid softener content includes the amount of oil contained in the oil-stretched rubber and the amount of liquid resin in the resin-stretched rubber that has been stretched with liquid resin.

[0154] If the above rubber composition contains resin, the resin content (total amount of resin in a solid state and resin in a liquid state under 1 atmosphere and 25°C conditions) is preferably 1 to 50 parts by mass.

[0155] When the above rubber composition contains oil in a liquid state under conditions of 1 atmosphere and 25°C, the oil content is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 20 parts by mass or more, and also preferably 35 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 15 parts by mass or less, per 100 parts by mass of the rubber component. When the oil content is within the above range, a better effect tends to be obtained. Note that the oil content also includes the amount of oil contained in the oil-applied rubber.

[0156] When the above rubber composition contains liquid rubber in a liquid state under conditions of 1 atmosphere and 25°C, the content of the liquid rubber is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 27 parts by mass or more, and also preferably 55 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 35 parts by mass or less, per 100 parts by mass of the rubber component. When the content is within the above range, the effect tends to be better obtained.

[0157] The above rubber composition may contain a fatty acid derivative. Examples of the above-mentioned fatty acid derivatives include fatty acid metal salts, amide esters, fatty acid esters, fatty acid amides, mixtures of fatty acid metal salts and amide esters, and mixtures of fatty acid metal salts and fatty acid amides. These may be used individually or in combination of two or more. In particular, it is preferable that at least one is 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, more preferably fatty acid metal salts, mixtures of fatty acid metal salts and fatty acid amides, and even more preferably a mixture of fatty acid metal salts and fatty acid amides.

[0158] The fatty acids that make up the fatty acid metal salt are not particularly limited, but 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)). Examples include lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidic acid, behenic acid, and nervonic acid. These can be used individually or in combination of two or more. Among these, saturated fatty acids are preferred, and saturated fatty acids having 14 to 20 carbon atoms are more preferred.

[0159] Examples of metals that make up fatty acid metal salts include alkali metals such as potassium and sodium, alkaline earth metals such as magnesium, calcium and barium, zinc, nickel, and molybdenum. These may be used individually or in combination of two or more. Among these, zinc and calcium are preferred.

[0160] Examples of amide esters include fatty acid amide esters, which are composed of the saturated or unsaturated fatty acids mentioned above. These may be used individually or in combination of two or more types.

[0161] Examples of fatty acid esters include fatty acid esters comprising the saturated or unsaturated fatty acids mentioned above. These may be used individually or in combination of two or more types.

[0162] The fatty acid amide can be either saturated or unsaturated. These may be used individually or in combination of two or more. Examples of saturated fatty acid amides include N-(1-oxooctadecyl)sarcosinamide, stearic acid amide, and behenic acid amide. Examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide.

[0163] Specific examples of mixtures of fatty acid metal salts and amide esters include Aflux16, manufactured by Rhein Chemie, which is a mixture of fatty acid calcium salt and amide ester.

[0164] Specific examples of mixtures of fatty acid metal salts and fatty acid amides include WB16, manufactured by Structol, which is a mixture of fatty acid calcium and fatty acid amide.

[0165] Examples of the above-mentioned fatty acid derivatives include products from companies such as Rhein Chemie and Structol.

[0166] The content of the above fatty acid derivative is preferably 2 parts by mass or more, more preferably 4 parts by mass or more, and even more preferably 6 parts by mass or more, per 100 parts by mass of the rubber component, and also preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0167] The above rubber composition may contain an anti-aging agent. While not particularly limited, examples of anti-aging agents include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), and N,N'-ditril-p-phenylenediamine. Examples include p-phenylenediamine-based antioxidants such as methyl amine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, with polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline being more preferred. Commercially available products include those from companies such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and Flexis.

[0168] In the above rubber composition, the content of the anti-aging agent is preferably 2.0 parts by mass or more, more preferably 3.5 parts by mass or more, even more preferably 4.5 parts by mass or more, and preferably 12 parts by mass or less, and more preferably 6 parts by mass or less, per 100 parts by mass of the rubber component. When the content is within the above range, a better effect tends to be obtained.

[0169] The above rubber composition may contain stearic acid. In the above rubber composition, the stearic acid content is preferably 1.0 part by mass or more, more preferably 2.0 parts by mass or more, and preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of the rubber component. Within this range, a better effect tends to be obtained.

[0170] In addition, conventionally known stearic acid can be used, such as products from NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Corporation, Chiba Fatty Acid Co., Ltd.

[0171] The above rubber composition may contain zinc oxide. In the above rubber composition, the zinc oxide content is preferably 1.0 part by mass or more, more preferably 2.0 parts by mass or more, and preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of the rubber component. Within this range, a better effect tends to be obtained.

[0172] 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.

[0173] The above rubber composition may contain sulfur. In the above rubber composition, the sulfur content is preferably 1.0 part by mass or more, more preferably 1.7 parts by mass or more, even more preferably 2.0 parts by mass or more, per 100 parts by mass of the rubber component, and also preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and even more preferably 3.0 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0174] 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.

[0175] The above rubber composition may contain a vulcanization accelerator. In the above rubber composition, the content of the vulcanization accelerator is preferably 1.5 parts by mass or more, more preferably 3.0 parts by mass or more, even more preferably 4.5 parts by mass or more, and preferably 16 parts by mass or less, and more preferably 8 parts by mass or less, per 100 parts by mass of the rubber component. When the content is within the above range, a better effect tends to be obtained.

[0176] There are no particular restrictions on the type of vulcanization accelerator; commonly used ones can be used. Examples of vulcanization accelerators include benzothiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiadylsulfenamide; thiram-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-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, and N,N'-diisopropyl-2-benzothiazolesulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, diortotrilguanidine, and orthotrilbiguanidine. Commercially available products from companies such as Sumitomo Chemical Co., Ltd. and Ouchi Shinko Chemical Co., Ltd. can be used. These may be used individually or in combination of two or more. Among these, sulfenamide, guanidine, and benzothiazole vulcanization accelerators are preferred.

[0177] In addition to the above components, the above rubber composition may also contain other compounding agents commonly used in the tire industry, such as mold release agents.

[0178] In this specification, various materials containing carbon atoms (e.g., rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from atmospheric carbon dioxide. As a method for obtaining the above formulations from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process in which methane is synthesized from carbon dioxide may be converted.

[0179] The above rubber composition can be manufactured, for example, by kneading each of the above components using a rubber kneading device such as an open roll or Banbury mixer, and then vulcanizing them.

[0180] Regarding the mixing conditions, in the base mixing step in which additives other than the crosslinking agent (vulcanizing agent) and vulcanization accelerator are mixed, the mixing temperature is preferably 100°C or higher, more preferably 120°C or higher, and also preferably 180°C or lower, more preferably 170°C or lower. In the finish mixing step in which the vulcanizing agent and vulcanization accelerator are mixed, the mixing temperature is preferably 80°C or higher, also preferably 120°C or lower, more preferably 110°C or lower. 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 preferably 140°C or higher, more preferably 150°C or higher, also preferably 190°C or lower, more preferably 185°C or lower.

[0181] A tire having a tread made of the above-mentioned rubber composition is manufactured by conventional methods using the above-mentioned rubber composition. That is, a rubber composition, which may contain various additives as needed, can be extruded to match the shape of the tread at the unvulcanized stage, molded in conventional methods on a tire molding machine, bonded together with other tire components to form an unvulcanized tire, and then heated and pressurized in a vulcanizing machine to manufacture the tire. The above tread may be a single layer or a multi-layer structure. If the above tread has a multi-layer structure, it is sufficient that at least one of the layers is made of the above rubber composition, and it is preferable that at least the outermost layer in the radial direction of the tire is made of the above rubber composition.

[0182] The above-mentioned tires are not particularly limited and include, for example, pneumatic tires, solid tires, and airless tires. Among these, pneumatic tires are preferred.

[0183] The above-mentioned tires can be used for passenger cars, large passenger cars, large SUVs, heavy-duty trucks and buses, light trucks, motorcycles, racing tires, winter tires (studless tires, snow tires, studded tires), all-season tires, run-flat tires, aircraft tires, mining tires, etc. Among these, passenger car tires are preferred.

[0184] In the above-mentioned tire, the maximum depth D of the circumferential grooves formed in the tread is preferably 6 mm or more, more preferably 10 mm or more, and even more preferably 15 mm or more. The upper limit is preferably 30 mm or less, more preferably 25 mm or less, and even more preferably 20 mm or less. Within the above range, a better effect tends to be obtained.

[0185] In this specification, the maximum depth D of the circumferential groove is measured along the normal to the plane extended from the surface forming the contact surface of the outermost tread surface, and is the distance from the extended surface to the deepest groove bottom, representing the maximum groove depth among all the circumferential grooves provided.

[0186] In the above tire, when the maximum depth of the circumferential groove is D (mm) and the silica content per 100 parts by mass of the rubber component is S (parts by mass), the condition D × S > 300 is satisfied. The D×S value is preferably 330 or higher, more preferably 600 or higher, even more preferably 900 or higher, even more preferably 1200 or higher, even more preferably 1500 or higher, and even more preferably 1800 or higher. It is also preferably 5000 or lower, more preferably 4000 or lower, and even more preferably 3000 or lower. When the value is within the above range, a better effect tends to be obtained. On the other hand, from the viewpoint of wear resistance, the value is preferably 1800 or less, more preferably 900 or less, and even more preferably 330 or less.

[0187] In the above-mentioned tire, the maximum tread thickness T is preferably 3.0 mm or more, more preferably 5.0 mm or more, even more preferably 7.0 mm or more, and particularly preferably 9.0 mm or more. The upper limit is preferably 20.0 mm or less, more preferably 18.0 mm or less, even more preferably 16.0 mm or less, and particularly preferably 14.0 mm or less. Within the above range, a better effect tends to be obtained.

[0188] In this specification, the maximum tread thickness T refers to the maximum distance in the radial direction of the tire, measured along the normal to the extended surface that forms the contact surface of the outermost tread surface, from the extended surface that forms the contact surface to the top surface of the carcass.

[0189] Figure 1 is a meridian-oriented cross-sectional view showing a portion of a pneumatic tire 1 according to one embodiment of the present disclosure. Note that the tire of the present disclosure is not limited to the following embodiments.

[0190] In Figure 1, the vertical direction is the tire radial direction (hereinafter also simply referred to as the radial direction), the horizontal direction is the tire axial direction (hereinafter also simply referred to as the axial direction), and the direction perpendicular to the plane of the paper is the tire circumferential direction (hereinafter also simply referred to as the circumferential direction). This tire 1 has a shape that is almost symmetrical with respect to the center line CL in Figure 1. This center line CL is also called the tread center line and represents the equatorial plane EQ of tire 1.

[0191] This tire 1 has a tread 2, sidewall 3, bead 4, carcass 5, and belt 6. This tire 1 is a tubeless type.

[0192] The tread 2 has a tread surface 7. The tread surface 7 has a shape that is convex radially outward in a cross-section of the tire 1 cut along the meridian. This tread surface 7 is in contact with the road surface. Multiple grooves 8 extending in the circumferential direction are engraved on the tread surface 7. These grooves 8 form the tread pattern. The outer portion of the tread 2 in the tire axial direction (tire width direction) is called the shoulder portion 15. The sidewall 3 extends radially inward from the end of the tread 2. This sidewall 3 is made of cross-linked rubber or the like.

[0193] As shown in Figure 1, the bead 4 is located approximately radially inward from the sidewall 3. The bead 4 comprises a core 10 and an apex 11 extending radially outward from the core 10. The core 10 is ring-shaped along the circumferential direction of the tire. The core 10 is made of a wound non-stretchable wire. Typically, steel wire is used for the core 10. The apex 11 tapers radially outward. The apex 11 is made of a high-hardness cross-linked rubber or the like.

[0194] In this embodiment, the carcass 5 consists of carcass plies 12. The carcass plies 12 are stretched between the two beads 4 and run along the inside of the tread 2 and sidewall 3. The carcass plies 12 are folded around the core 10 from the inside to the outside in the tire axial direction. Although not shown, the carcass plies 12 consist of a number of parallel cords and topping rubber. The absolute value of the angle that each cord makes with respect to the equatorial plane EQ(CL) is typically between 70° and 90°. In other words, this carcass 5 has a radial structure.

[0195] In this embodiment, the belt 6 is located radially outside the carcass 5. The belt 6 is laminated on the carcass 5. The belt 6 reinforces the carcass 5. The belt 6 may consist of an inner layer belt 13 and an outer layer belt 14. In this embodiment, the widths of the two belts 13 and 14 are different.

[0196] Although not shown in the diagram, the inner belt 13 and the outer belt 14 each typically consist of a number of parallel cords and topping rubber. It is desirable that each cord be inclined with respect to the equatorial plane EQ. It is desirable that the inclination direction of the cords in the inner belt 13 is opposite to the inclination direction of the cords in the outer belt.

[0197] Although not shown in the diagram, a band may be laminated on the radially outer side of the belt 6. The width of this band is greater than the width of the belt 6. This band may consist of a cord and a topping rubber. The cord is wound in a spiral shape. The belt is restrained by this cord, so that the lifting of the belt 6 is suppressed. The cord is preferably made of organic fibers. Examples of preferred organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

[0198] Although not shown in the figures, an edge band may be provided on the radially outer side of the belt 6 and near the widthwise end (edge ​​portion) of the belt 6. This edge band, like the band described above, may consist of a cord and a topping rubber. An example of such an edge band is one that is laminated on the upper surface of the step 20 portion of the wide inner layer belt 13. The cord of this edge band is inclined in the same direction as the cord of the narrow outer layer belt 14, and is biased against the cord of the wide inner layer belt 13.

[0199] Although not shown in the diagram, the cushion rubber layer may be laminated with the carcass 5 near the widthwise end of the belt 6. The cushion layer may be made of soft cross-linked rubber. The cushion layer absorbs stress at the end of the belt.

[0200] FIG. 2 shows a cross-section cut in a plane including the tire axis of the tread 2 of the tire 1. The tread 2 of the tire 1 is provided with circumferential groove portions 8. In the tire 1, the maximum depth D of the circumferential groove portions 8 is the normal direction distance from the plane extending the plane forming the ground contact surface of the tread surface 7 to the deepest groove bottom, and among the plurality of circumferential groove portions 8, it indicates the depth of the deepest formed groove. Also, in the tire 1, the maximum thickness T of the tread 2 indicates the maximum distance among the dimensions in the tire radial direction from the plane extending the plane forming the ground contact surface of the tread surface 7 to the upper surface of the carcass 5.

Example

[0201] Hereinafter, the present invention will be described by way of examples, but the scope of the present invention is not limited to these examples.

[0202] Hereinafter, various chemicals used in the examples and comparative examples will be described.

[0203] (Rubber component) NR: TSR20 Amino group-modified SBR: HPR850 manufactured by ENEOS MATERIALS Co., Ltd. (styrene content: 27.5% by mass, vinyl content: 59% by mass, Tg: -24°C) BR: Nipol BR1220 manufactured by Nippon Zeon Co., Ltd. (vinyl content: 1% by mass, cis content 97% by mass or more)

[0204] (Chemicals other than rubber components) Carbon black: Diablack I manufactured by Mitsubishi Chemical Corporation (N220, N2SA 114 m 2 / g, DBP 114 ml / 100 g) Silica: Ultrasil VN3 manufactured by Evonik Degussa GmbH (average particle diameter 17 nm) Ionic bonding coupling agent: X-12-1126 manufactured by Shin-Etsu Chemical Co., Ltd. (quaternary ammonium salt) Silane coupling agent: Si266 manufactured by Evonik Corporation (bis(3-triethoxysilylpropyl)disulfide) Oil: Process X-140 manufactured by ENEOS Corporation Liquid Rubber: LIR-410 manufactured by Kuraray (Liquid IR, Mw 30000) Wax: Sunoc N manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Antioxidant 1: No Crack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Antioxidant 2: No Crack RD (Poly(2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Stearic Acid: Tsubaki manufactured by NOF Corporation Zinc Oxide: Zinc White No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powdered sulfur manufactured by Karuizawa Refinery Co., Ltd. Vulcanization Accelerator 1: Noxeller CZ (N-cyclohexyl-2-benzothiazolylsulfenamide) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Vulcanization Accelerator 2: Noxeller D (N,N'-diphenylguanidine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

[0205] (Examples and Comparative Examples) According to the formulation shown in Table 1, using a 16L Banbury mixer manufactured by Kobe Steel, Ltd., chemicals other than sulfur and vulcanization accelerators were kneaded at 160 °C for 4 minutes to obtain a kneaded product. Next, sulfur and vulcanization accelerators were added to the kneaded product, and it was kneaded at 80 °C for 4 minutes using an open roll to obtain an unvulcanized polymer composition. The unvulcanized polymer composition was formed into the shape of a tread, and laminated together with other tire members on a tire molding machine to form an unvulcanized tire. Then, it was vulcanized at 170 °C for 12 minutes to manufacture a test tire (specification: Table 1, size: 195 / 65R15). The test tires manufactured in this way were examined, and the results calculated based on the following evaluation method are shown in Table 1.

[0206] Also, in the following evaluation method, the evaluation criteria when calculating the index are as follows. Table 1: Comparative Example 1

[0207] <Wet grip performance> The test tires are fitted to all wheels of the vehicle, and the vehicle is driven 10 laps on a wet surface course. Twenty test drivers evaluate the braking performance in the wet surface area on a 5-point scale from 1 to 5. A higher score indicates better performance. The total score from 20 people's evaluations is calculated and indexed with a baseline of 100. A higher index indicates better wet grip performance.

[0208] [Table 1]

[0209] The present invention (1) comprises a tread made of a rubber composition, The tread has circumferential grooves, The rubber composition contains a rubber component having an amino group, a filler containing silica, and an ionic coupling agent. When the maximum depth of the circumferential groove is D (mm) and the silica content per 100 parts by mass of the rubber component is S (parts by mass), This tire satisfies the requirement D×S > 300.

[0210] The present invention (2) is the tire according to the present invention (1), wherein the rubber having the amino group is styrene-butadiene rubber.

[0211] The present invention (3) is a tire according to the present invention (1) or (2) in which the rubber component comprises butadiene rubber.

[0212] The present invention (4) is a tire in any combination of the rubber component of the present invention (1) to (3) and any of the rubber components of the present invention (1) to (3).

[0213] The present invention (5) is a tire in any combination of the present invention (1) to (4), wherein the silica content per 100 parts by mass of the rubber component is 90 parts by mass or more and 150 parts by mass or less.

[0214] The tire of the present invention (6) is a tire in any combination of the present inventions (1) to (5) in which the rubber composition contains a silane coupling agent.

[0215] The tire of the present invention (7) is the tire according to the present invention (6), in which the content of the silane coupling agent with respect to 100 parts by mass of the rubber having an amino group is 4 parts by mass or more and 10 parts by mass or less.

[0216] The tire of the present invention (8) is a tire in any combination of the present inventions (1) to (7) in which the filler contains carbon black.

[0217] The tire of the present invention (9) is the tire according to the present invention (8), in which the content of the carbon black with respect to 100 parts by mass of the rubber component is 6 parts by mass or more and 15 parts by mass or less.

[0218] The tire of the present invention (10) is the tire according to the present invention (8) or (9), in which the value of the content of the carbon black / the content of the silica is 0.06 or more and 0.15 or less.

[0219] The tire of the present invention (11) is a tire in any combination of the present inventions (1) to (10) in which the rubber composition contains a softening agent.

[0220] The tire of the present invention (12) is the tire according to the present invention (11), in which the value of the content of the softening agent / the content of the filler is 0.20 or more and 0.70 or less.

[0221] The tire of the present invention (13) is the tire according to the present invention (11) or (12), in which the softening agent contains a liquid polymer.

[0222] The tire of the present invention (14) is a tire in any combination of the present inventions (1) to (13), in which the maximum depth of the circumferential groove is 6 mm or more and 20 mm or less.

[0223] The present invention (15) is a tire in any combination with any of the present inventions (1) to (14) wherein the D×S value is 900 or more and 3000 or less. [Explanation of Symbols]

[0224] 1 tire 2 tread 3 Sidewall 4 Beads 5 Carcass 6 belts 7. Tread surface 8 grooves 10 cores 11 Apex 12 Carcass ply 13 Inner belt 14. Outer belt 15 Shoulder section 17. Crown Center (Tread Center Line CL, Tire 1 Equatorial Surface EQ) 20 steps D Maximum groove depth of the circumferential groove section T tread maximum thickness

Claims

1. Equipped with a tread made of a rubber composition, The tread has circumferential grooves, The rubber composition contains a rubber component having an amino group, a filler containing silica, and an ionic coupling agent. When the maximum depth of the circumferential groove is D (mm) and the silica content relative to 100 parts by mass of the rubber component is S (parts by mass), Tires that satisfy D×S > 300.

2. The tire according to claim 1, wherein the rubber having the amino group is styrene-butadiene rubber.

3. The tire according to claim 1 or 2, wherein the rubber component comprises butadiene rubber.

4. The tire according to claim 1 or 2, wherein the rubber component comprises isoprene-based rubber.

5. The tire according to claim 1 or 2, wherein the silica content per 100 parts by mass of the rubber component is 90 parts by mass or more and 150 parts by mass or less.

6. The tire according to claim 1 or 2, wherein the rubber composition contains a silane coupling agent.

7. The tire according to claim 6, wherein the content of the silane coupling agent per 100 parts by mass of the rubber having the amino group is 4 parts by mass or more and 10 parts by mass or less.

8. The tire according to claim 1 or 2, wherein the filler comprises carbon black.

9. The tire according to claim 8, wherein the carbon black content per 100 parts by mass of the rubber component is 6 parts by mass or more and 15 parts by mass or less.

10. The tire according to claim 8, wherein the value of the carbon black content / silica content is 0.06 or more and 0.15 or less.

11. The tire according to claim 1 or 2, wherein the rubber composition contains a softening agent.

12. The tire according to claim 11, wherein the value of the content of the softener / the content of the filler is 0.20 or more and 0.70 or less.

13. The tire according to claim 11, wherein the softening agent comprises a liquid polymer.

14. The tire according to claim 1 or 2, wherein the maximum depth of the circumferential groove is 6 mm or more and 20 mm or less.

15. The tire according to claim 1 or 2, wherein the value of D×S is 900 or more and 3000 or less.

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