tire

Abstract

To provide a tire improved in abrasion resistance.SOLUTION: A tire comprises a tread. Rubber compositions constituting the tread include rubber components including isoprene rubber and styrene-butadiene rubber, silica as well as coupling agents. A tread surface of the tread has circumferential grooves continuously extending in a circumferential direction. When a content (parts by mass) of isoprene rubber with respect to 100 parts by mass of the rubber components is defined as AIR, a content (parts by mass) of styrene- butadiene rubber is defined as ASBR, a content (parts by mass) of silica is defined as ASIL and a groove depth (mm) of the deepest circumferential groove of the circumferential grooves is defined as D, AIR. ASBR, ASIL and D satisfy the following relations: (1) ASIL / ASBR>1.00 and (2) AIR / D>3.0.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] One of the important performances required for a tire is wear resistance. For example, Patent Document 1 describes a rubber composition for a tire in which wear resistance and the like are improved by blending a predetermined silica and a liquid resin.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, regarding the wear resistance of the rubber composition for a tire, further improvement is required from various aspects.

[0005] An object of the present invention is to provide a tire that improves wear resistance, particularly wear resistance on rough roads, when using a rubber composition containing an isoprene rubber and a styrene-butadiene rubber, silica, and a coupling agent.

Means for Solving the Problems

[0006] The present invention relates to the following tire. A tire including a tread, wherein the rubber composition constituting the tread contains a rubber component including an isoprene rubber and a styrene-butadiene rubber, silica, and a coupling agent, the tread surface of the tread has a circumferential groove continuously extending in the circumferential direction, the content (parts by mass) of the isoprene rubber with respect to 100 parts by mass of the rubber component is AIR wherein the content (parts by mass) of styrene-butadiene rubber is A SBR wherein the content (parts by mass) of silica is A SIL wherein when the groove depth (mm) of the deepest circumferential groove among the circumferential grooves is D, A IR 、A SBR 、A SIL and a tire in which D satisfies the following relationship. (1) A SIL / A SBR >1.00 (2) A IR / D>3.0

Advantages of the Invention

[0007] According to the present invention, it is possible to provide a tire that improves wear resistance, particularly wear resistance on rough roads.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0009] The tire of the present invention is the following tire. A tire provided with a tread, wherein the rubber composition constituting the tread contains a rubber component containing isoprene rubber and styrene-butadiene rubber, silica, and a coupling agent, wherein the tread surface of the tread has circumferential grooves continuously extending in the circumferential direction, Let the content (parts by mass) of the isoprene rubber with respect to 100 parts by mass of the rubber component be A IR Let the content (parts by mass) of the styrene-butadiene rubber be B SBR Let the content (parts by mass) of the silica be C SIL When the groove depth (mm) of the deepest circumferential groove among the circumferential grooves is D, a tire in which A IR , A SBR , A SIL and D satisfy the following relationship. (1) A SIL / A SBR > 1.00 (2) A IR / D> 3.0

[0010] Although not intended to be bound by theory, in the present invention, the following can be considered as mechanisms for improving wear resistance, particularly wear resistance on rough roads.

[0011] That is, (1) By using a rubber component containing an isoprene rubber (IR rubber) and a styrene-butadiene rubber (SBR) in the rubber composition used for the tread, these form a phase-separated structure, and it becomes easier to relax external forces at the interface. (2) By blending an amount of silica greater than the amount of SBR, a silica network is formed across each phase related to phase separation, enhancing the reinforcing effect. (3) In addition to these, increasing the IR rubber to improve the dispersion of silica or reducing the groove depth of the circumferential grooves on the tread surface to suppress the deformation of the tread rubber is considered to enhance wear resistance. And it is considered that these (1) to (3) cooperate to improve wear resistance, particularly wear resistance on rough roads, synergistically.

[0012] The content (parts by mass) C of the silica SIL is preferably more than 50 parts by mass and less than 200 parts by mass.

[0013] This is because it is considered that a silica network is easily formed. Also, it is considered that silica can contribute to low fuel consumption.

[0014] The rubber composition contains carbon black, and the content (parts by mass) of carbon black with respect to 100 parts by mass of the rubber component is A CB When this is the case, A CB is preferably more than 2 parts by mass and less than 20 parts by mass.

[0015] This is because it is considered that by suppressing the amount of carbon black and increasing the amount of silica as the filler, a network of silica is likely to be formed. This is also because silica is considered to be able to contribute to low fuel consumption.

[0016] The rubber composition contains carbon black, and the content (parts by mass) of carbon black with respect to 100 parts by mass of the rubber component is A CB When this is the case, the content (parts by mass) A of the silica SIL and A CB preferably satisfy the following relationship. (3) A CB / A SIL <0.80

[0017] This is because it is considered that by suppressing the amount of carbon black and increasing the amount of silica as the filler, a network of silica is likely to be formed. This is also because silica is considered to be able to contribute to low fuel consumption.

[0018] The average primary particle diameter of the silica is preferably less than 19 nm.

[0019] This is because it is considered that a stronger network of silica is formed.

[0020] When the land ratio (%) of the tread contact surface of the tread is L, the content (parts by mass) A of the silica SIL and L preferably satisfy the following relationship. (4) A SIL ×L>2500

[0021] Since the force per unit area of the rubber is suppressed as the land ratio increases, the amount of deformation of the rubber is also suppressed, so it is considered that a smaller amount of silica can be tolerated.

[0022] When the thickness (mm) of the rubber layer composed of the rubber composition constituting the tread is H and the total styrene amount (% by mass) in the rubber component is S, it is preferable that H and S satisfy the following relationship. (5) H×S<230

[0023] Since the amount of deformation of the rubber is suppressed as the thickness of the rubber layer constituting the dredge decreases, it is considered that a smaller total styrene amount can be tolerated.

[0024] The coupling agent preferably includes a coupling agent containing a nitrogen atom-containing associative group.

[0025] The coupling agent containing a nitrogen atom-containing associative group interacts with acidic silica through acid-base interaction. For this reason, even when the tread rubber is greatly deformed, the reinforcing effect by the coupling agent is less likely to be lost, and it is considered that the abrasion resistance on rough roads is further improved.

[0026] The content of the coupling agent containing a nitrogen atom-containing associative group is preferably more than 6 parts by mass and less than 12 parts by mass with respect to 100 parts by mass of silica.

[0027] In the present invention, it is considered that the effect of the coupling agent containing a nitrogen atom-containing associative group is easily exerted.

[0028] When the tire is incorporated into a rim and the internal pressure is 250 kPa or more, when the tire cross-sectional width is Wt (mm) and the tire outer diameter is Dt (mm), it is preferable that Wt and Dt satisfy any one of the following formulas (A), (B), or (C). Wt<225 and Dt≧59.078×Wt^0.460 ···(A) 225 ≤ Wt < 235 and Dt ≥ 59.078 × Wt^0.620 - 967.673 ···(B) 235 ≤ Wt and Dt ≥ Wt^0.6 + 750 ···(C)

[0029] The tires that satisfy the requirements of formula (A) to formula (C) have a relatively large tire outer diameter with respect to the tire cross-sectional width, so they can suppress air resistance and rolling resistance and contribute to the improvement of fuel consumption performance.

[0030] Preferably, the tire includes at least one lateral groove that extends from the circumferential groove in the tire width direction and remains within the land portion.

[0031] This is because it can contribute to the improvement of fuel consumption performance.

[0032] <Definition> "Dimensions, etc. of each part of the tire" shall be values specified in the unloaded normal state where the tire is mounted on the standard rim and filled with the standard internal pressure, unless otherwise specified.

[0033] "Standard rim" is the rim defined for each tire in the standard system including the standard on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Association), it refers to the standard rim in the applicable sizes described in the "JATMA YEAR BOOK"; in the case of ETRTO (The European Tyre and Rim Technical Organisation), it refers to the "Measuring Rim" described in the "STANDARDS MANUAL"; in the case of TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" described in the "YEAR BOOK". Refer to JATMA, ETRTO, and TRA in that order, and follow the relevant standards if there are applicable sizes. For tires not defined by the standards, it refers to the rim that can be mounted on the tire and can hold the internal pressure, that is, among the rims that do not cause air leakage between the rim / tire, the one with the smallest rim diameter and then the narrowest rim width.

[0034] "Normal internal pressure" refers to the air pressure determined for each tire in the standard system including the standards on which the tire is based. For JATMA, it is the "maximum air pressure"; for ETRTO, it is "INFLATION PRESSURE"; for TRA, it is the "maximum value" described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". Refer to JATMA, ETRTO, and TRA in this order, similar to the normal rim. When there is an applicable size during the reference, follow the relevant standard. For tires not specified in the standard, it refers to the normal internal pressure (provided it is 250 KPa or more) of another tire size (specified in the standard) with the said normal rim described as the standard rim. In the case where multiple normal internal pressures of 250 KPa or more are described, it refers to the minimum value among them.

[0035] "Maximum load capacity W L " is calculated by the following formula. "V" is the virtual volume of the tire (mm 3 ), "Dt" is the outer diameter of the tire in the normal state (mm), "Ht" is the cross-sectional height of the tire in the tire cross-section by the plane including the tire rotation axis in the tire radial direction (mm), and "Wt" is the cross-sectional width of the tire in the normal state (mm). When the rim diameter of the tire is R, Ht can be obtained by (Dt - R) / 2. Wt is the value obtained after excluding patterns or characters on the tire sidewall. Note that the maximum load capacity is synonymous with the said normal load.

[0036]

Number

[0037] "Circumferential groove" refers to a groove continuously extending in the tire circumferential direction, where the groove width in the tire width direction on the tread surface is 4 mm or more. The circumferential groove may extend linearly along the circumferential direction, or may extend in a wave shape, sine shape, or zigzag shape along the circumferential direction.

[0038] The "groove depth D" is the groove depth (mm) of the deepest circumferential groove provided on the tread surface. Here, the groove depth means the maximum value of the depth in the groove.

[0039] The "land ratio L" is the ratio of the surface area of the actually contacting tread ground surface to the surface area of the tread ground surface in a state where all grooves are assumed to be filled on the tread ground surface when the maximum load capacity is loaded on the tire in the normal state and the tire contacts the plane at a camber angle of 0 degrees. Each surface area of the tread ground surface is obtained by assembling the tire on a standard rim, applying a normal internal pressure, standing still at 25°C for 24 hours, then applying ink to the tire tread surface, loading the maximum load capacity and pressing it against thick paper (the camber angle is 0°), and transferring it to the paper. It is the average value when the tire is rotated 72° in the circumferential direction and transferred at 5 locations. Note that FIG. 2 is a diagram schematically showing the shape of the tread ground surface of the tire. The enclosed area in the figure represents the shape of the tread ground surface.

[0040] The "thickness H of the rubber layer composed of the rubber composition constituting the tread part" is the thickness of the rubber layer constituting the tread part measured along the normal line drawn from the tire center line (tire equator). When there is a circumferential groove on the tire center line, it is measured along the normal line drawn from the land center line of the land closest to the tire center line among the lands. The "land center line" is a straight line passing through the center in the tire width direction of the land and continuously extending in the tire circumferential direction. The "tread part" is the part that forms the ground contact surface of the tire. In the tire radial cross-section, when there are members such as a belt layer, a belt reinforcing layer, and a carcass layer that form the tire skeleton with steel or textile materials, it is the member outside these in the tire radial direction. When the tread part consists of multiple rubber layers, H is the combined thickness of all the rubber layers. FIG. 1 shows the thickness H of the rubber layer constituting the tread part measured along the normal line drawn from the tire center line (tire equator).

[0041] The "transverse groove" is a groove that extends from the circumferential groove in the tire width direction and remains within the tread portion, and its groove width is not particularly limited. Therefore, in addition to those with a groove width of 2 mm or more, fine grooves with a groove width of less than 2 mm, sometimes called sipes, are also included.

[0042] The "plasticizer content" includes the amount of plasticizer in the rubber component extended by the plasticizer. Similarly, the "oil content" includes the amount of oil contained in the oil-extended rubber.

[0043] "Rough road" generally refers to an unpaved road, which is generally called an off-road road.

[0044] <Measurement method> The "styrene content" 1 is calculated by 1H-NMR measurement.

[0045] The "vinyl content (amount of 1,2-bonded butadiene units)" is measured by infrared absorption spectroscopy.

[0046] The "cis content (amount of cis-1,4-bonded butadiene units)" is measured by infrared absorption spectroscopy.

[0047] The "weight average molecular weight (Mw)" can be determined by standard polystyrene conversion based on the measured value by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMALTPORE HZ-M manufactured by Tosoh Corporation).

[0048] The "N2SA of carbon black" is a value determined according to JIS K 6217-2:2017.

[0049] The "N2SA of silica" is a value measured by the BET method in accordance with ASTM D3037-93.

[0050] The "average primary particle diameter" is a value obtained by the arithmetic mean of 400 primary particles observed with a transmission or scanning electron microscope. When the shape of the particle is spherical, the diameter of the sphere is taken as the particle diameter. When the shape is other than spherical, the equivalent circle diameter ({the positive square root of 4 × (the area of the particle) / π}) is calculated from the electron microscope image and taken as the particle diameter. It is applicable to silica, carbon black, etc.

[0051] The "total styrene amount (mass%) of the rubber component" is a value obtained by calculating the product of the styrene content and the content rate in the whole rubber component for each rubber constituting the whole rubber component (100 mass%), and then summing them all up.

[0052] The "softening point of resin, etc." is, unless otherwise specified, the softening point defined in JIS K 6220-1:2015, measured with a ring and ball type softening point measuring device, and is the temperature at which the ball drops. The softening point measured by other methods shall be described to that effect.

[0053] <Rubber composition constituting the tread> The rubber composition constituting the tread of the present invention will be described. The rubber composition contains a rubber component including an isoprene-based rubber and a styrene-butadiene rubber, silica, and a coupling agent.

[0054] (Rubber component) The rubber component of the present invention includes an isoprene-based rubber and a styrene-butadiene rubber.

[0055] ≪Isoprene-based rubber≫ Examples of isoprene rubbers (IR rubbers) include natural rubber (NR), isoprene rubber (IR), modified NR, denatured NR, denatured IR, etc. As NR, for example, those commonly used in the tire industry such as SIR20, RSS#3, TSR20, etc. can be used. IR is not particularly limited, and for example, those commonly used in the tire industry such as IR2200, etc. can be used. Examples of modified NR include deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc. Examples of denatured NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Examples of denatured IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, etc. These may be used alone or in combination of two or more.

[0056] The content of isoprene rubber in 100% by mass of the rubber component is preferably more than 35% by mass, more preferably 40% by mass or more, and still more preferably more than 45% by mass. The upper limit is preferably less than 65% by mass, more preferably 60% by mass or less, and still more preferably 55% by mass or less. By setting it within the above range, the IR rubber is likely to form a phase-separated structure with styrene-butadiene rubber, which is preferable.

[0057] ≪SBR≫ SBR is not particularly limited, and for example, emulsion polymerization styrene-butadiene rubber (E-SBR), solution polymerization styrene-butadiene rubber (S-SBR), etc. can be used. Also, SBR may be unmodified SBR or modified SBR. Further, as SBR, hydrogenated styrene-butadiene copolymer (hydrogenated SBR) can also be used. These may be used alone or in combination of two or more.

[0058] The styrene content of SBR is preferably more than 5.0% by mass, more preferably more than 10.0% by mass, and still more preferably more than 20.0% by mass. The styrene content is preferably less than 40.0% by mass, more preferably less than 35.0% by mass, and still more preferably less than 30.0% by mass. By setting it within the above range, there is a tendency for low fuel consumption and wet grip performance to be improved. In this specification, the styrene content is1 It can be measured by 1H-NMR measurement.

[0059] The vinyl content of SBR is preferably more than 30% by mass, more preferably more than 40% by mass, still more preferably more than 50% by mass. The vinyl content is preferably less than 80% by mass, more preferably less than 70% by mass, still more preferably less than 65% by mass. By setting it within the above range, there is a tendency for low fuel consumption and wet grip performance to be improved. The vinyl content can be measured by the above method.

[0060] As SBR, SBR extended with a plasticizer (extended SBR) can be used, or non-extended SBR can also be used. When using extended SBR, the amount of extension of SBR, that is, the content of the extending plasticizer contained in SBR, is preferably 10 to 50 parts by mass with respect to 100 parts by mass of the rubber solid content of SBR. As the plasticizer used for extension, for example, oil is preferably used.

[0061] As SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., etc. can be used.

[0062] The content of SBR in 100% by mass of the rubber component is preferably more than 35% by mass, more preferably 40% by mass or more, still more preferably 45% by mass or more. The upper limit is preferably less than 65% by mass, more preferably 60% by mass or less, still more preferably 55% by mass or less. By setting it within the above range, it is preferable because SBR easily forms a phase-separated structure with IR-based rubber.

[0063] ≪BR≫ BR is not particularly limited, and for example, high cis-content high cis BR, BR containing syndiotactic polybutadiene crystals, BR synthesized using a rare earth-based catalyst (rare earth BR), etc. can be used. These may be used alone or in combination of two or more.

[0064] Among them, the BR preferably contains high-cis BR with a cis content of more than 90% by mass. The cis content is more preferably more than 95% by mass, and even more preferably 98% by mass or more. The cis content can be measured by the above method.

[0065] Also, the BR may be unmodified BR or modified BR. Examples of the modified BR include modified BR into which a functional group similar to that of the modified diene rubber is introduced. Further, hydrogenated butadiene polymer (hydrogenated BR) can also be used as the BR.

[0066] As the BR, for example, products of UBE Corporation, JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used.

[0067] The content of BR in 100% by mass of the rubber component is preferably less than 20% by mass, more preferably less than 15% by mass, and even more preferably 10% by mass or less. By setting it within the above range, the IR-based rubber and SBR are likely to form a phase-separated structure, which is preferable. BR may not be included, and an embodiment in which BR is not included can be cited as one preferable embodiment. Also, BR may be included, and in that case, the lower limit value of the content of BR is, for example, more than 1% by mass, or more than 3% by mass, or more than 5% by mass.

[0068] ≪Other Rubber Components≫ As the rubber component, rubbers other than the above diene rubbers can be used. Such rubbers include diene rubbers such as styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), and non-diene rubbers such as ethylene propylene diene rubber (EPDM), butyl rubber (IIR), and halogenated butyl rubber (X-IIR). These may be used alone or in combination of two or more.

[0069] The content of the diene rubber in 100% by mass of the rubber component is preferably more than 80% by mass, more preferably more than 90% by mass, and most preferably 100% by mass.

[0070] ≪Total styrene content (S) of rubber component (mass%)≫ From the viewpoint of the effects of the present invention, the total styrene content (S) of the rubber component is preferably more than 5% by mass, more preferably more than 7% by mass, and still more preferably 10% by mass or more. From the viewpoint of the effects of the present invention, the total styrene content (S) of the rubber component is preferably less than 25% by mass, more preferably less than 22% by mass, and still more preferably less than 20% by mass.

[0071] (Rubber component synthesized from recycled and biomass-derived raw materials) The monomers that are the constituent units of synthetic rubbers such as SBR and BR may be derived from petroleum or recycled from rubber products such as tires and non-rubber products such as polystyrene. The monomers obtained by recycling (recycled monomers) are not particularly limited, and examples include recycled butadiene and recycled aromatic vinyl compounds. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl compound is not particularly limited, and examples include styrene. Among them, it is preferable to use recycled butadiene (recycled butadiene) and / or recycled styrene (recycled styrene) as raw materials.

[0072] The method for producing recycled monomers is not particularly limited, and examples include being synthesized from recycled naphtha obtained by decomposing rubber products such as tires. Also, 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 high pressure, decomposed by microwaves, or extracted after mechanical pulverization.

[0073] Furthermore, monomers that are constituent units of polymers such as SBR and BR may be derived from biomass. The monomers derived from biomass (biomass monomers) are not particularly limited, and examples include butadiene derived from biomass and aromatic vinyl compounds derived from biomass. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl compound is not particularly limited, and examples include styrene. Also, the method for producing biomass monomers is not particularly limited, and examples include those by biological and / or chemical and / or physical conversion of animals and plants. Fermentation by microorganisms is typical of biological conversion, and examples of chemical and / or physical conversion include those by catalysts, high heat, high pressure, electromagnetic waves, supercritical fluids, and combinations thereof. Examples of biomass sources for these monomers include sugars, wood, plant residues after obtaining useful components, ethanol derived from plants, biomass naphtha, and the like.

[0074] Polymers synthesized from biomass monomer components (biomass polymers) are not particularly limited, and examples include polybutadiene rubber synthesized from butadiene derived from biomass and aromatic vinyl / butadiene copolymers synthesized from butadiene derived from biomass and / or aromatic vinyl compounds derived from biomass. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from butadiene derived from biomass and / or styrene derived from biomass.

[0075] Whether the raw material of the polymer is derived from biomass can be determined by pMC (percent Modern Carbon) measured in accordance with ASTM D 6866-10. pMC is the ratio of the 14 C concentration of the sample to the 14 C concentration of the standard modern carbon (modern standard reference), and this value is used as an index indicating the biomass ratio of the compound (rubber). The significance of this value is described below.

[0076] One mole (6.02×10 23 atoms) of carbon atoms contains approximately 6.02×10 11 atoms of 14 C, which is about one trillionth of ordinary carbon atoms. 14 The half-life of 14 C is 5730 years, and 14 C decreases regularly. 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, which are thought to have been around for over 226,000 years, all of the 14 C element initially contained in them has decayed. Thus, in the 21st century, fossil fuels such as coal, oil, and natural gas contain 14 no 14 C element at all. Therefore, chemical substances produced from these fossil fuels also 14 contain no 14 C element.

[0077] On the other hand, 14 C is constantly produced by nuclear reactions of cosmic rays in the atmosphere. Therefore, 14 C is in equilibrium between decrease due to radioactive decay and production by nuclear reactions, and in the Earth's atmospheric environment, 14 the amount of 14 C is constant. Therefore, the 14 C concentration of substances derived from biomass resources that are cycling in the current environment is about 1×10 -12 mol% with respect to the total number of 14 C atoms as described above. Therefore, by utilizing the difference between these values, the ratio (biomass ratio) of compounds derived from natural resources (compounds derived from biomass resources) in a certain compound (rubber) can be calculated.

[0078] This 14 C is generally measured as follows. Using accelerator mass spectrometry based on a tandem accelerator, 13 the 13 C concentration ( 13 13 C / 12 C), 14 the 14 C concentration ( 14 14 C / 12 C) is measured. In the measurement, 14As a modern standard reference for the concentration of C, the 14 C concentration in the circulating carbon in nature in 1950 is adopted. As a specific reference material, the oxalic acid standard provided by NIST (National Institute of Standards and Technology) is used. The specific radioactivity of carbon in this oxalic acid (the 14 radioactivity intensity of 13 C per gram of carbon) is fractionated for each carbon isotope, and the value corrected to a constant value for 14 C and subjected to decay correction from 1950 AD to the measurement date is used as the standard

[0079] C concentration value (100%). The ratio of this value to the value of the actually measured sample is the pMC value. 14 Therefore, if the rubber is made of a 100% biomass (natural system) - derived material, although there are regional differences, it will show a value of approximately 110 pMC (currently, in the normal state, it often does not reach 100). On the other hand, for chemical substances derived from fossil fuels such as petroleum, when the

[0080] C concentration is measured, it will show approximately 0 pMC (for example, 0.3 pMC). This value corresponds to a biomass ratio of 0% mentioned above.

[0081] (Filler) The rubber composition for tires of the present invention contains silica, preferably contains silica and carbon black, and more preferably consists only of silica and carbon black.

[0082] ≪Silica≫ The silica is not particularly limited, and for example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrous silica), etc., which are common in the tire industry, can be used. The raw material of the silica is not particularly limited, and for example, it may be a raw material derived from a mineral such as quartz, or it may be a raw material derived from a living organism such as rice husk (for example, silica using a biomass material such as rice husk as a raw material), or silica recycled from a product containing silica may also be used. Among them, hydrous silica prepared by a wet method is preferred because of its large number of silanol groups. The silica may be used alone or in combination of two or more.

[0083] Silica using a biomass material as a raw material can be obtained, for example, by extracting silicate from rice husk ash obtained by burning rice husk using a sodium hydroxide solution, and reacting the silicate with sulfuric acid in the same manner as conventional wet silica to obtain a precipitate of silicon dioxide, followed by filtration, washing with water, drying, and pulverization.

[0084] As the silica recycled from a product containing silica, for example, silica recovered from products containing silica such as electronic components such as semiconductors, tires, desiccants, and filter materials such as diatomaceous earth can be used. The recovery method is not particularly limited, and examples include thermal decomposition and decomposition by electromagnetic waves. Among them, silica recovered from electronic components such as semiconductors or tires is preferred.

[0085] When silica crystallizes, it does not dissolve in water and the silicic acid that is its component cannot be utilized. By controlling the combustion temperature and combustion time, the crystallization of silica in rice husk ash can be suppressed (see, for example, JP-A-2009-2594, Akita Prefectural University Web Journal B / 2019, vol. 6, p. 216-222, etc.). Commercially available amorphous silica extracted from rice husk can be used, such as those sold by Wilmar Co., Ltd.

[0086] As commercially available products of silica, products of Evonik Degussa, Rhodia, Tosoh Silica Corporation, Solvay Japan K.K., Tokuyama Corporation, etc. can be used.

[0087] The nitrogen adsorption specific surface area (N2SA) of silica is preferably more than 50 m 2 / g, more preferably more than 150 m 2 / g, even more preferably more than 170 m 2 / g, even more preferably more than 175 m 2 / g or more. The upper limit of the N2SA of silica is not particularly limited, but is preferably less than 600 m 2 / g, more preferably less than 350 m 2 / g, even more preferably less than 260 m 2 / g. By setting it within the above range, the wet grip performance tends to improve. The N2SA of silica is a value measured by the above method.

[0088] The average primary particle diameter of silica is preferably less than 25 nm, more preferably less than 22 nm, even more preferably less than 19 nm, from the viewpoints of reinforcement, low fuel consumption, etc. The lower limit of the average primary particle diameter is not particularly limited, but is preferably more than 5 nm, more preferably more than 10 nm, even more preferably more than 13 nm, even more preferably more than 15 nm. The average primary particle diameter of silica can be determined by the above method.

[0089] The content of silica (total amount of silica) is preferably more than 50 parts by mass, more preferably more than 60 parts by mass, even more preferably more than 70 parts by mass, even more preferably more than 75 parts by mass, even more preferably 80 parts by mass or more with respect to 100 parts by mass of the rubber component. On the other hand, the content is preferably less than 200 parts by mass, more preferably less than 180 parts by mass, even more preferably less than 150 parts by mass, even more preferably less than 120 parts by mass.

[0090] ≪Carbon black≫ The carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The raw material of the carbon black may be a biomass material such as lignin or vegetable oil, or may be a pyrolysis oil obtained by pyrolyzing waste tires. Further, the manufacturing method of the carbon black may be by combustion such as the furnace method, may be by hydrothermal carbonization (HTC), or may be by thermal decomposition of methane such as the thermal black method. As commercially available products, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., Columbian Carbon Company, etc. can be used. These may be used alone or in combination of two or more.

[0091] In addition to the above, from the perspective of life cycle assessment and the like, carbon black made from biomass materials such as lignin as a raw material, or recycled carbon black obtained by pyrolyzing and purifying products containing carbon black such as tires may also be used as the carbon black.

[0092] In this specification, "recycled carbon black" refers to carbon black obtained by pulverizing used products such as tires containing carbon black and firing the pulverized product, and when oxidized and burned by heating in air by a thermogravimetric method conforming to JIS K 6226-2:2003, it refers to carbon black in which the ratio of the mass of the component that does not burn (ash content) is 13% by mass or more. That is, the ratio of the mass (carbon amount) of the weight loss due to the oxidative combustion of the recycled carbon black is 87% by mass or less. Recycled carbon black may also be represented by rCB.

[0093] Recycled carbon black can be obtained from the pyrolysis process of used pneumatic tires. For example, European Patent Application Publication No. 3427975 refers to "Rubber Chemistry and Technology", Vol. 85, No. 3, pages 408-449 (2012), particularly pages 438, 440, and 442, and describes that it can be obtained by pyrolysis of organic materials at 550-800 °C with oxygen excluded or vacuum pyrolysis at relatively low temperatures (

[0027] ). The carbon black obtained from such a pyrolysis process usually lacks functional groups on its surface, as mentioned in

[0004] of Patent No. 6856781 (Comparison of the surface morphology and chemistry of pyrolytic carbon black and commercially available carbon black, Powder Technology 160 (2005) 190-193).

[0094] Recycled carbon black may lack functional groups on its surface, or may be treated to contain functional groups on its surface. The treatment to make the recycled carbon black contain functional groups on its surface can be carried out by conventional methods. For example, in European Patent Application Publication No. 3173251, carbon black obtained from a pyrolysis process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl and / or carboxyl groups on its surface. Also, in Patent No. 6856781, carbon black obtained from a pyrolysis process is treated with an amino acid compound containing at least one thiol group or disulfide group to obtain carbon black with an activated surface. The recycled carbon black according to this embodiment also includes carbon black treated to contain functional groups on its surface.

[0095] Commercially available recycled carbon black from companies such as Strable Green Carbon and LDCarbon can be used.

[0096] The nitrogen adsorption specific surface area (N2SA) of the carbon black is preferably more than 50 m 2 / g, and more preferably 70 m 2 / g or more is more preferable, 90 m 2 / g or more is even more preferable. Further, the above N2SA is 200 m 2 / g or less is preferable, 150 m 2 / g or less is more preferable, 130 m 2 / g or less is even more preferable. By setting within the above range, there is a tendency for improvement in low fuel consumption property and wet grip performance. The nitrogen adsorption specific surface area of carbon black is determined by the above method.

[0097] From the viewpoint of reinforcing property, the average primary particle diameter of carbon black is preferably less than 30 nm, more preferably less than 28 nm, and even more preferably less than 25 nm. The lower limit of the average primary particle diameter is not particularly limited, but is preferably more than 10 nm, more preferably more than 15 nm, and even more preferably more than 20 nm. The average primary particle diameter of carbon black can be determined by the above method.

[0098] The content of carbon black is preferably more than 1 part by mass, more preferably more than 2 parts by mass, even more preferably more than 3 parts by mass, and even more preferably 5 parts by mass or more with respect to 100 parts by mass of the rubber component. The upper limit of the content is preferably less than 40 parts by mass, more preferably 35 parts by mass or less, even more preferably less than 20 parts by mass, even more preferably less than 15 parts by mass, and even more preferably less than 10 parts by mass. By setting within the above range, there is a tendency for improvement in low fuel consumption property and wet grip performance.

[0099] ≪Formula (3) (A CB / A SIL )≫ When the rubber composition contains silica and carbon black, the content (parts by mass) of silica with respect to 100 parts by mass of the rubber component is A SIL Let, and the content (parts by mass) of carbon black be A CB When, A SIL And A CB It is preferable to satisfy the following formula (3). A CB / A SIL <0.80 (3)

[0100] The right side of the above formula (3) is preferably 0.70, more preferably 0.65, still more preferably 0.50, still more preferably 0.30, and still more preferably 0.15. On the other hand, A CB / A SIL The lower limit of the value of is not particularly limited, and for example, it may be about 0.01.

[0101] ≪Other fillers≫ The rubber composition for tires of the present invention may contain other fillers other than silica and carbon black. Such other fillers are not particularly limited, and materials known in the rubber field can be used. For example, inorganic fillers such as calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, mica, etc. can be mentioned.

[0102] ≪Content of filler≫ From the viewpoint of the effects of the present invention, the content of the filler (total content of the fillers) is preferably more than 70 parts by mass, more preferably more than 80 parts by mass, still more preferably 85 parts by mass or more, and still more preferably 90 parts by mass or more with respect to 100 parts by mass of the rubber component. The upper limit of the content is preferably less than 200 parts by mass, more preferably less than 150 parts by mass, and still more preferably less than 130 parts by mass.

[0103] (Coupling agent) The rubber composition of the present invention contains a coupling agent. The coupling agent preferably contains a coupling agent containing a nitrogen atom-containing associative group, and may consist only of a coupling agent containing a nitrogen atom-containing associative group. The coupling agent may be used alone or in combination of two or more.

[0104] Examples of the coupling agent containing a nitrogen atom-containing associative group include amino-based silane coupling agents such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, and the following nitrogen atom-containing polysulfide compounds (hereinafter also referred to as "N-containing polysulfide"). Among these, N-containing polysulfide is preferred.

[0105] ≪N-containing polysulfide≫ The N-containing polysulfide is a compound represented by the following chemical formula (I). R A -Y A -(S)x-Y B -R B (I) (Here, R A and R B are the same or different and each represents an associative organic group containing at least one nitrogen atom, Y A and Y B are the same or different and each represents a divalent linking group, S represents a sulfur atom, and x represents an integer of 2 or more.)

[0106] Here, "associative" particularly means the property of being able to associate with each other by at least one bond selected from the group consisting of hydrogen bonds, ionic bonds, and hydrophobic bonds. Among these, it is preferable to associate by hydrogen bonds.

[0107] When the associative organic group can associate by hydrogen bonds, R A and R B preferably each contain a donor site and an acceptor site for hydrogen bonds. Preferred examples of the associative organic group represented by R A and R B include imidazolidinoyl, ureyl, bisureyl, ureido-pyrimidyl, and triazolyl, etc. More preferably, groups represented by the following chemical formulas (II) to (VI) are included.

[0108]

Chemical formula

[0109] Here, the symbols have the following meanings. -R represents a linear, branched or cyclic hydrocarbon group, preferably having 1 to C carbon atoms 10 , more preferably 1 to 6 carbon atoms. The hydrocarbon group may optionally contain a heteroatom. -Y represents an oxygen atom or a sulfur atom, preferably an oxygen atom. -R’ represents a linear, branched or cyclic hydrocarbon-based group, preferably having 1 to C carbon atoms 10 , more preferably 1 to 6 carbon atoms. The hydrocarbon group may optionally contain a heteroatom. -The symbol * indicates the moiety bonded to Y A or Y B (the same applies in the following chemical formula).

[0110] R’ may be a hydrocarbylene group such as alkylene, substituted alkylene, cycloalkylene, substituted cycloalkylene, arylene or substituted arylene. The number of carbon atoms of this hydrocarbylene group is preferably 1 to C 10 . This hydrocarbylene group may contain a heteroatom such as nitrogen, oxygen or sulfur. These heteroatoms may be contained in the hydrocarbylene chain. The ring of formula (II) is preferably a 5-membered ring or a 6-membered ring. More preferably, R’ is -CH2-CH2- or -CH2-CH2-CH2-.

[0111] R A and R B are each independently a nitrogen-containing (di- or tri-) nitrogen heterocyclic ring having 5 or 6 atoms and containing at least one carbonyl functional group. According to a preferred embodiment, at least one of R A and R B is an imidazolidinone group of formula (VII). The other of R A and R B corresponds to any of the above formulas (II) to (VI), preferably an imidazolidinone group of formula (VII).

[0112]

Chemical formula

[0113] Y in the above chemical formula (I) A and Y B are groups that do not interfere with R A and R B or groups that, even if there is interference, can be suppressed to a slight extent. Y A and Y B are preferably, independently of each other, divalent, linear, branched or cyclic hydrocarbon radicals. These may independently contain one or more aromatic radicals and / or one or more heteroatoms such as nitrogen atoms, sulfur atoms, oxygen atoms. This divalent hydrocarbon radical may be optionally substituted, and the substituent is preferably inert to R A and R B According to a preferred embodiment, Y A and Y B are the same or different and represent a linear alkylene group, preferably having 1 to 6 carbon atoms. Y A and Y B are preferably the same.

[0114] x in the above chemical formula (I) is preferably an integer from 2 to 8, more preferably an integer from 2 to 6, and even more preferably an integer from 2 to 4. According to other specific embodiments, x is 2, or 3, or 4, or 5, or 6.

[0115] Preferred examples of the N-containing polysulfide include, in chemical formula (I), where R A and R B are both imidazolidinone groups of chemical formula (VII), and Y A and Y B are both C1-C 13、 preferably a linear alkylene group of C1-C6, and x is an integer of 2 or more, preferably an integer from 2 to 8, more preferably an integer from 2 to 6, and even more preferably an integer from 2 to 4.

[0116] More preferred examples of the N-containing polysulfide are compounds of the following chemical formula (VIII) or (IX).

[0117] [Chemical formula]

[0118] [Chemical formula]

[0119] Here, x is an integer of 2 or more, preferably an integer of 2 to 8, more preferably an integer of 2 to 6, still more preferably an integer of 2 to 4, and still more preferably x = 4.

[0120] More preferred examples of the N-containing polysulfide are compounds of the following chemical formula (X) or (XI).

[0121] [Chemical formula]

[0122] Note that the N-containing polysulfide can be a mixture of compounds with different values of x, and as a result, the value of x can be a number (average value) different from an integer value. In such a case, the preferred range of the average value of x in the mixture of the N-containing polysulfide is a positive number in the range of 2 to 8, preferably a positive number in the range of 2 to 6, more preferably a positive number in the range of 3 to 5, still more preferably a positive number in the range of 3 to 4, or a positive number in the range of 4 to 5.

[0123] The N-containing polysulfide can be produced, for example, by the method described in International Publication No. 2019 / 193286.

[0124] <<Other coupling agents>> As the coupling agent other than the above-mentioned "coupling agent containing a nitrogen atom-containing associative group", a coupling agent commonly used in the tire industry can be used. Examples of such coupling agents include sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl)disulfide and bis(3-triethoxysilylpropyl)tetrasulfide; mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, NXT-Z100, NXT-Z45 manufactured by Momentive, and NXT (3-octanoylthiopropyltriethoxysilane); vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; glycidoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Among these, sulfide-based silane coupling agents are preferred. These silane coupling agents may be used alone or in combination of two or more.

[0125] ≪Content of Coupling Agent≫ The content of the coupling agent with respect to 100 parts by mass of silica (the total amount of all when using a plurality of coupling agents in combination) is preferably more than 1 part by mass, more preferably more than 3 parts by mass, still more preferably more than 5 parts by mass, and still more preferably more than 7 parts by mass from the viewpoint of enhancing the dispersibility of silica. Also, from the viewpoint of preventing a decrease in wear resistance performance, the content is preferably less than 20 parts by mass, more preferably less than 18 parts by mass, and still more preferably less than 15 parts by mass.

[0126] The content of the coupling agent containing a nitrogen atom-containing associative group with respect to 100 parts by mass of silica is the same as above. In a preferred embodiment, it is preferably more than 6 parts by mass, more preferably more than 7 parts by mass, and even more preferably 8 parts by mass or more. On the other hand, the content is preferably less than 12 parts by mass, more preferably less than 11 parts by mass, and even more preferably less than 10 parts by mass.

[0127] (Resin) The rubber composition can contain a resin. The resin is not particularly limited, but resins commonly used in the tire industry can be used. For example, aromatic vinyl resins, dicyclopentadiene resins, C9 resins, C5 resins, C5C9 resins, terpene resins, rosin resins, phenolic resins, etc. can be mentioned. Among these, petroleum resins, aromatic vinyl resins, dicyclopentadiene resins, C9 resins, and terpene resins are preferred. The resin may be used alone or in combination of two or more.

[0128] ≪Aromatic vinyl resin≫ The "aromatic vinyl resin" refers to a resin containing at least one aromatic vinyl compound selected from the group consisting of styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene, etc. as the monomer component with the highest content, preferably containing 50 mol% or more, and those obtained by hydrogenating or modifying them may also be used. As the aromatic vinyl resin, due to economic reasons, easy processing, and excellent heat generation properties, a homopolymer of α-methylstyrene or styrene or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred. As the aromatic vinyl resin, for example, those commercially available from companies such as Kreton, Eastman Chemical, and Mitsui Chemicals can be used. The resin may be used alone or in combination of two or more.

[0129] ≪Dicyclopentadiene resin≫ The term "dicyclopentadiene-based resin" refers to a resin containing dicyclopentadiene (DCPD) as the monomer component with the highest content, and it may be hydrogenated or modified. Examples of dicyclopentadiene-based resins include, for example, DCPD / C9 resins obtained by copolymerizing dicyclopentadiene and the C9 fraction, etc., and DCPD / C9 resins are preferred. As DCPD resins, for example, those commercially available from ExxonMobil, ENEOS Corporation, Nippon Zeon Co., Ltd., Maruzen Petrochemical Co., Ltd., etc. can be used. The resin may be used alone or in combination of two or more.

[0130] ≪C9-based resin≫ The term "C9-based resin" refers to a resin obtained by polymerizing the C9 fraction, and it may be a polymer of the C9 fraction alone or a copolymer obtained by copolymerizing the C9 fraction and other components. For example, a resin obtained by copolymerizing dicyclopentadiene (DCPD) and the C9 fraction is called a DCPD / C9 resin. Also, it may be hydrogenated or modified. Examples of the C9 fraction include at least one petroleum fraction corresponding to 8 to 10 carbon atoms selected from the group consisting of vinyltoluene, alkylstyrene, coumarone, indene, methylindene, dicyclopentadiene, etc. Specific examples of C9-based resins include, for example, coumarone-indene resins, coumarone resins, indene resins, etc. The resin may be used alone or in combination of two or more.

[0131] ≪C5-based resin≫ The term "C5-based resin" refers to a resin obtained by polymerizing a C5 fraction other than dicyclopentadiene, and it may be hydrogenated or modified. Examples of the C5 fraction other than dicyclopentadiene include at least one petroleum fraction corresponding to 4 to 5 carbon atoms selected from the group consisting of cyclopentadiene, isoprene, pentane, isopentane, neopentane, pentene, pentadiene, etc. The resin may be used alone or in combination of two or more.

[0132] ≪C5C9-based resin≫ The "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be a hydrogenated or modified one thereof. As the C5C9 petroleum resin, for example, those commercially available from Tosoh Corporation, LUHUA Co., Ltd., etc. can be used. The resin may be used alone or in combination of two or more kinds.

[0133] ≪Terpene resin≫ The terpene resin refers to a resin containing at least one terpene compound selected from the group consisting of α-pinene, β-pinene, limonene, dipentene, etc. as the monomer component with the highest content, preferably containing 50 mol% or more, and may be a hydrogenated or modified one thereof. Specific examples of the terpene resin include, for example, polyterpene resin containing only one or more of the above terpene compounds as monomer components; aromatic modified terpene resin containing the terpene compound and an aromatic compound as monomer components; terpene phenol resin containing the terpene compound and a phenolic compound as monomer components, etc. Examples of the aromatic compound serving as a monomer component of the aromatic modified terpene resin include at least one selected from the group consisting of styrene, α-methylstyrene, vinyltoluene, divinyltoluene, etc. Examples of the phenolic compound serving as a monomer component of the terpene phenol resin include at least one selected from the group consisting of phenol, bisphenol A, cresol, xylenol, etc. The resin may be used alone or in combination of two or more kinds.

[0134] ≪Rosin resin≫ The rosin-based resin refers to a resin containing at least one rosin acid compound selected from the group consisting of abietic acid, neoabietic acid, palustric acid, isopimaric acid, etc., preferably containing as the monomer component with the highest content, more preferably containing 50 mol% or more. It may be a hydrogenated or modified product thereof. The rosin-based resin is not particularly limited, and examples thereof include natural resin rosin, rosin-modified resins obtained by modifying it by hydrogenation, disproportionation, dimerization, esterification, etc. The resin may be used alone or in combination of two or more.

[0135] ≪Phenolic resin≫ The phenolic resin refers to a resin containing a phenolic compound such as phenol or cresol as the monomer component with the highest content, preferably containing 50 mol% or more. The phenolic resin is not particularly limited, and examples thereof include phenol formaldehyde resin, alkylphenol formaldehyde resin, alkylphenol acetylene resin, oil-modified phenol formaldehyde resin, etc. The resin may be used alone or in combination of two or more.

[0136] ≪Content≫ The content of the resin component relative to 100 parts by mass of the rubber component is preferably more than 1 part by mass, more preferably more than 3 parts by mass, still more preferably more than 4 parts by mass, and still more preferably 5 parts by mass or more. Also, the content of the resin component is preferably less than 30 parts by mass, more preferably less than 25 parts by mass, and still more preferably less than 20 parts by mass.

[0137] (Plasticizer) The rubber composition for tires of the present invention can contain a plasticizer other than the above resin. A plasticizer is a material that imparts plasticity to the rubber component, and is a concept including both a plasticizer that is liquid (liquid state) at normal temperature (25 °C) and a plasticizer that is solid at normal temperature (25 °C). Specific examples of the plasticizer other than the above resin include, for example, oil, liquid polymer, ester plasticizer, etc. The plasticizer other than the resin may be used alone or in combination of two or more.

[0138] ≪Oil≫ Examples of oils include process oils, vegetable oils, animal oils, etc. Examples of process oils include paraffinic process oils (mineral oils), naphthenic process oils, aromatic process oils, etc. Specific examples of process oils include, for example, MES (Mild Extract Solvated), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), RAE (Residual Aromatic Extract), etc. Also, a process oil with a low content of polycyclic aromatic (PCA) compounds can be used for environmental measures. Examples of the low-PCA-content process oils include MES, TDAE, heavy naphthenic oils, etc. Further, from the perspective of life cycle assessment, it is also possible to use waste oil after being used in a rubber mixer or an engine, or refined waste cooking oil used in a restaurant.

[0139] 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, grape seed oil, wood wax, etc. Further, vegetable oils include refined oils (such as salad oil) obtained by refining the above oils, 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, oxidation polymerized oils obtained by oxidizing the above oils, waste cooking oils recovered from those used as edible oils, etc. Note that vegetable oils may be liquid or solid at normal temperature (25°C). These vegetable oils may be used alone or in combination of two or more.

[0140] 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 hydroxy 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. Further, the acylglycerol may be a monomer, a dimer, or a multimer of trimer or higher. Note that acylglycerols of dimer or higher can be obtained by thermal polymerization, oxidative polymerization, or the like. Also, the acylglycerol may be liquid or solid at normal temperature (25°C).

[0141] As a method for confirming whether the acylglycerol is contained in the rubber composition, it is not particularly limited, but 1 it can be confirmed by 1H-NMR measurement. For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at normal temperature (25°C) for 24 hours. After removing the rubber composition, 1 1H-NMR is measured. When the signal of tetramethylsilane (TMS) is set to 0.00 ppm, signals are observed around 5.26 ppm, around 4.28 ppm, and around 4.15 ppm. These signals are presumed to be signals derived from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In this paragraph, "around" means a range of ±0.10 ppm.

[0142] The fatty acid is not particularly limited and may be an unsaturated fatty acid or a saturated fatty acid. Examples of the unsaturated fatty acid include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of the saturated fatty acid include butyric acid and lauric acid.

[0143] Among them, as the fatty acid, it is desirable to contain a fatty acid with few double bonds, that is, a saturated fatty acid or a monounsaturated fatty acid, and oleic acid is preferred. As the vegetable oil containing such a fatty acid, for example, a vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid may be used, or a vegetable oil subjected to modification such as transesterification may be used. Further, in order to produce a vegetable oil containing such a fatty acid, plants may be improved by variety improvement, gene recombination, genome editing, etc.

[0144] As the vegetable oil, for example, those commercially available from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Co., Ltd., Oryzoi Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0145] Examples of the animal oil include fish oil, beef tallow, or oleyl alcohol that can be derived therefrom.

[0146] ≪Liquid polymer≫ The liquid polymer is not particularly limited as long as it is in a liquid state at normal temperature (25°C). Examples thereof include liquid butadiene rubber (liquid BR), liquid styrene-butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene-isoprene rubber (liquid SIR), liquid farnesene rubber, etc. The liquid polymer may be used alone or in combination of two or more.

[0147] ≪Ester plasticizer≫ Examples of ester plasticizers include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), bis(2-ethylhexyl) azelate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), trixylenyl phosphate (TXP), and the like. The ester plasticizers may be used alone or in combination of two or more.

[0148] ≪Content≫ The content of the plasticizer other than the resin with respect to 100 parts by mass of the rubber component (the total amount of all when using a plurality in combination) is preferably more than 1 part by mass, more preferably more than 2 parts by mass, and still more preferably more than 3 parts by mass. Also, the content of the plasticizer is preferably less than 50 parts by mass, more preferably less than 40 parts by mass, and still more preferably less than 30 parts by mass.

[0149] (Other compounding agents) As other compounding agents, the rubber composition for tires of the present invention can use vulcanized rubber particles, wax, anti-aging agent, stearic acid, zinc oxide, vulcanizing agent, vulcanization accelerator, and the like.

[0150] ≪Vulcanized rubber particles≫ Vulcanized rubber particles are particles made of vulcanized rubber. Specifically, rubber powder defined in JIS K 6316:2017 can be used. From the viewpoints of environmental consideration and cost, recycled rubber powder produced from crushed waste tires and the like is preferable. These may be used alone or in combination of two or more. The vulcanized rubber particles are not particularly limited, and may be non-modified vulcanized rubber particles or modified vulcanized rubber particles. As commercially available products of vulcanized rubber, for example, products of Lehigh, Murakami Rubber Industry Co., Ltd., and the like can be used.

[0151] <<Wax>> The wax is not particularly limited, and any wax commonly used in the tire industry can be preferably used. Examples include petroleum waxes, mineral waxes, synthetic waxes, etc. Among them, petroleum waxes are preferred. Examples of petroleum waxes include paraffin wax, microcrystalline wax, and their selected special waxes, etc. Among them, paraffin wax is preferred. As the wax, those manufactured and sold by, for example, Ouchi Shinsei Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., etc. can be used. The wax can be used alone or in combination of two or more.

[0152] When the wax is contained, the content relative to 100 parts by mass of the rubber component is preferably more than 0.3 part by mass, more preferably more than 0.5 part by mass, and still more preferably 1.0 part by mass or more. On the other hand, the content is preferably less than 4.0 parts by mass, more preferably less than 3.0 parts by mass, and still more preferably less than 2.0 parts by mass.

[0153] <<Antioxidant>> The antioxidant is not particularly limited, and any antioxidant commonly used in the tire industry can be preferably used. Examples of antioxidants include quinoline-based antioxidants, quinone-based antioxidants, phenol-based antioxidants, phenylenediamine-based antioxidants, and metal carbamates, etc. Among them, phenylenediamine-based antioxidants are preferred because they can better exhibit the effect of improving ozone resistance. The antioxidant can be used alone or in combination of two or more.

[0154] When the antioxidant is contained, the content relative to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 0.8 part by mass, and still more preferably more than 1.0 part by mass. On the other hand, the content is preferably less than 7.0 parts by mass, more preferably less than 5.0 parts by mass, and still more preferably less than 3.0 parts by mass.

[0155] <<Stearic Acid>> When containing stearic acid, the content with respect to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 0.7 part by mass, and even more preferably more than 1.0 part by mass from the viewpoint of processability. On the other hand, from the viewpoint of vulcanization rate, the content is preferably less than 10 parts by mass, more preferably less than 5 parts by mass, and even more preferably less than 3 parts by mass.

[0156] ≪Zinc Oxide≫ When containing zinc oxide, the content with respect to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 0.7 part by mass, and even more preferably more than 1 part by mass from the viewpoint of processability. On the other hand, from the viewpoint of abrasion resistance, the content is preferably less than 10 parts by mass, more preferably less than 7 parts by mass, and even more preferably less than 5 parts by mass.

[0157] ≪Vulcanizing Agent≫ The vulcanizing agent is not particularly limited, and known vulcanizing agents can be used. For example, organic peroxides, sulfur-based vulcanizing agents, resin vulcanizing agents, metal oxides such as magnesium oxide, etc. can be mentioned. Among them, sulfur-based vulcanizing agents are preferred. As the sulfur-based vulcanizing agent, for example, sulfur, sulfur donors such as morpholine disulfide, etc. can be used. Among these, it is preferable to use sulfur. The vulcanizing agent can be used alone or in combination of two or more.

[0158] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur (oil-treated sulfur, special sulfur treated with a dispersant, masterbatch type sulfur, etc.), insoluble sulfur (oil-treated insoluble sulfur, etc.), and any of them can be preferably used. Among them, powdered sulfur is preferred. Sulfur can be used, for example, those manufactured and sold by Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Kasei Kogyo Co., Ltd., Flexsys, Nippon Dry Distillation Industry Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc.

[0159] When contained, the content with respect to 100 parts by mass of the rubber component is preferably more than 0.4 part by mass, more preferably more than 0.7 part by mass, and still more preferably 1.0 part by mass or more. On the other hand, the content is preferably less than 6.0 parts by mass, more preferably less than 5.0 parts by mass, and still more preferably less than 3.0 parts by mass. When the content of the vulcanizing agent is within the above range, an appropriate reinforcing effect tends to be obtained, and the effects of the present invention tend to be exhibited more favorably. When the vulcanizing agent contains components other than sulfur such as oil-treated sulfur, the content of the vulcanizing agent means the content of the sulfur component itself.

[0160] ≪Vulcanization accelerator≫ The vulcanization accelerator is not particularly limited, and known vulcanization accelerators can be used. For example, sulfenamide-based, thiazole-based, thiuram-based, thiourea-based, guanidine-based, dithiocarbamic acid-based, aldehyde-amine-based or aldehyde-ammonia-based, imidazoline-based, or xanthate-based vulcanization accelerators can be mentioned. Among them, sulfenamide-based, thiuram-based, and guanidine-based are preferable, and sulfenamide-based is more preferable. As the vulcanization accelerator, for example, those manufactured and sold by Ouchi Shinko Chemical Industry Co., Ltd., Sanshin Chemical Industry Co., Ltd., etc. can be used. These vulcanization accelerators can be used alone or in combination of two or more.

[0161] Examples of the sulfenamide-based vulcanization accelerator include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N,N'-dicyclohexyl-2-benzothiazolylsulfenamide (DZ), etc. Examples of the thiuram-based vulcanization accelerator include tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetrabenzylthiuram disulfide (TBzTD), etc. Examples of the guanidine-based vulcanization accelerator include 1,3-diphenylguanidine (DPG), diorthotolylguanidine, orthotolylbiguanidine, etc.

[0162] The content of the vulcanization accelerator with respect to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 1.0 part by mass, and even more preferably more than 2.0 parts by mass. On the other hand, the content is preferably less than 8.0 parts by mass, more preferably less than 6.0 parts by mass, and even more preferably less than 5.0 parts by mass. When the content of the vulcanization accelerator is within the above range, the breaking strength and elongation tend to be ensured, and the effects of the present invention tend to be more favorably exhibited.

[0163] In this specification, various materials containing carbon atoms (for example, rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from carbon dioxide in the atmosphere. As a method for obtaining the formulation of the various materials from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process of synthesizing methane from carbon dioxide may be converted.

[0164] <Tire> Hereinafter, the tire of the present invention will be described as appropriate with reference to the drawings. However, the drawings are merely examples for explanation.

[0165] The tire of the present invention is a tire provided with a tread made of the rubber composition, and the tread surface of the tread has a circumferential groove that continuously extends in the circumferential direction.

[0166] (Circumferential groove) The circumferential groove may extend linearly along the circumferential direction, or may extend in a wave shape, a sine shape, or a zigzag shape along the circumferential direction. Here, the zigzag shape means that the center in the width direction of the circumferential groove extends in the tire circumferential direction while swinging in the tire width direction. Therefore, in addition to the form in which a linear groove repeatedly bends, a form in which a curved groove repeatedly curves in a wave shape is also included.

[0167] The number of circumferential grooves is not particularly limited, and may be 1, 2, 3, 4, or 5 or more. The groove depth of the circumferential groove is the distance in the tire radial direction to the deepest part of the groove, which is the maximum value of the depth in the groove. The groove depth is correlated with the tread thickness and is usually around 70% of the tread thickness.

[0168] (Equation (1), Equation (2)) In the tire of the present invention, the content (parts by mass) of isoprene rubber with respect to 100 parts by mass of the rubber component is A IR Let it be, and the content (parts by mass) of styrene-butadiene rubber is A SBR Let it be, and the content (parts by mass) of silica is A SIL Let it be. When the groove depth (mm) of the deepest circumferential groove among the circumferential grooves is D, A IR , A SBR , A SIL And D satisfy the following relationship. (1) A SIL / A SBR > 1.00 (2) A IR / D> 3.0

[0169] ≪A SIL / A SBR ≫ The right side of Equation (1) is preferably 1.09, more preferably 1.50, still more preferably 1.59, still more preferably 1.69, still more preferably 1.79, still more preferably 1.88, still more preferably 2.00. On the other hand, regarding the upper limit of the value of A SIL / A SBR , there is no particular limitation from the viewpoint of the effects of the present invention, but as a reference value, it is, for example, about 5.00.

[0170] ≪A IR / D≫ The right side of Equation (2) is preferably 3.2, more preferably 4.0, still more preferably 5.0, still more preferably 6.0, still more preferably 7.0, still more preferably 8.0. On the other hand, regarding the upper limit of the value of A IR / D, there is no particular limitation from the viewpoint of the effects of the present invention, but as a reference value, it is, for example, about 12.0.

[0171] D is the groove depth of the deepest circumferential groove among the circumferential grooves. D is as shown in FIG. 1, for example. The value of D is correlated with the thickness of the tread and is usually about 70% of the thickness of the tread.

[0172] (Equation (4) (A SIL × L)) When the land ratio (%) of the tread contact surface of the tire of the present invention is L, the silica content (parts by mass) A SIL and L preferably satisfy the following relationship. (4) A SIL × L > 2500

[0173] The right side of Equation (4) is preferably 3000, more preferably 3500, still more preferably 4000, and even more preferably 5000. On the other hand, there is no particular limitation on the upper limit of the value of A SIL × L from the viewpoint of the effects of the present invention, but as a reference value, it is about 14000, for example.

[0174] From the viewpoints of grip performance and wear resistance, the land ratio L is preferably 50% or more, more preferably more than 55%, and still more preferably more than 60%. On the other hand, from the viewpoint of grip performance, the land ratio L is preferably less than 80%, more preferably 75% or less, and still more preferably less than 70%.

[0175] (Equation (5) (H × S)) When the thickness (mm) of the rubber layer composed of the rubber composition constituting the tread of the tire of the present invention is H and the total styrene amount (mass%) in the rubber component is S, H and S preferably satisfy the following relationship. (5) H × S < 230

[0176] In the above Equation (5), the value of the right side is preferably 220, more preferably 200, still more preferably 180, and even more preferably 170. On the other hand, there is no particular limitation on the lower limit of the value of H × S from the viewpoint of the effects of the present invention, but as a reference value, it is about 50, for example.

[0177] The thickness H of the rubber layer may be more than 4 mm, preferably 6 mm or more, more preferably more than 8 mm, and still more preferably 9 mm or more. The upper limit is not particularly limited, but is preferably less than 35 mm, more preferably less than 25 mm. H is as shown in FIG. 1, for example.

[0178] (Formulas (A) to (C)) When the tire of the present invention is incorporated into a rim and the internal pressure is 250 kPa or more, when the tire cross-sectional width is Wt (mm) and the tire outer diameter is Dt (mm), it is preferable that Wt and Dt satisfy any one of the following formulas (A), (B), or (C). Wt < 225 and Dt ≧ 59.078 × Wt^0.460 ···(A) 225 ≦ Wt < 235 and Dt ≧ 59.078 × Wt^0.620 - 967.673 ···(B) 235 ≦ Wt and Dt ≧ Wt^0.6 + 750 ···(C)

[0179] Formulas (A) to (C) are applied according to the size of the tire cross-sectional width Wt (mm). That is, formula (A) is applied when Wt < 225, formula (B) is applied when 225 ≦ Wt < 235, and formula (C) is applied when 235 ≦ Wt. Since a tire that satisfies the requirements of formulas (A) to (C) has a relatively large tire outer diameter with respect to the tire cross-sectional width, it can contribute to the improvement of fuel consumption performance by suppressing air resistance and rolling resistance. Note that FIG. 3 shows the tire cross-sectional width (Wt), the tire cross-sectional height (Ht), and the tire outer diameter (Dt).

[0180] (Lateral groove) The tire of the present invention preferably includes at least one lateral groove that extends from the circumferential groove in the tire width direction and remains within the land portion. This is because it can contribute to improving fuel consumption performance. The lateral groove is not particularly limited as long as it extends from the circumferential groove in the tire width direction and remains within the land portion. Therefore, the extending direction of the lateral groove can take an arbitrary angle with respect to the extending direction of the circumferential groove. Also, the groove width of the lateral groove is not particularly limited, and in addition to those with a groove width of 2 mm or more, it may be a fine groove with a groove width of less than 2 mm, which is sometimes called a sipe. Further, the groove depth of the lateral groove is not particularly limited either.

[0181] FIG. 4 is a diagram schematically showing a tread pattern of a tire according to an embodiment of the present invention. In FIG. 4, TW indicates the tread contact width, and as the lateral groove 4, a lateral groove that extends from the circumferential groove in the tire width direction and remains within the land portion is shown.

[0182] <Manufacture> The rubber composition according to the present invention can be manufactured by a known method. For example, it can be manufactured by kneading each of the above components using a rubber kneading device such as an open roll or a closed kneader (Banbury mixer, kneader, etc.).

[0183] The kneading process includes, for example, a base kneading process of kneading compounding agents and additives other than the vulcanizing agent and the vulcanization accelerator, and a final kneading (F kneading) process of adding the vulcanizing agent and the vulcanization accelerator to the kneaded product obtained in the base kneading process and kneading them. Further, the base kneading process can be divided into a plurality of processes if desired. For example, the base kneading process may be divided into a plurality of masterbatch processes, or the base kneading process may be further subjected to a remilling process of repeating kneading one or more times.

[0184] As for the division into masterbatch steps, for example, it can be divided into a masterbatch containing isoprene rubber and the amount of silica to be distributed thereto, and a masterbatch containing a rubber component other than isoprene rubber and the amount of silica to be distributed thereto, and each masterbatch is kneaded in advance. Since silica has the property of being easily distributed to isoprene rubber among rubber components, by making masterbatches as described above, it is possible to correct the unbalanced distribution of silica to the rubber components. Each of the above masterbatches may consist only of each rubber component and silica, or may further contain other chemicals excluding vulcanizing agents and vulcanization accelerators such as coupling agents and oils. When dividing and kneading in the masterbatch step, after kneading each masterbatch step, if there are other chemicals excluding unkneaded vulcanizing agents and vulcanization accelerators in the combined masterbatches, the other chemicals are added and further kneaded. The content of each chemical compounded into the masterbatch is basically the same as the content of each of the above chemicals when the amount of the rubber component of the masterbatch is 100 parts by mass.

[0185] The kneading conditions are not particularly limited. For example, in the base kneading step, kneading is performed at a discharge temperature of 150 to 170°C for 3 to 10 minutes, and in the final kneading step, kneading is performed at 70 to 110°C for 1 to 5 minutes. The vulcanization conditions are not particularly limited. For example, a method of vulcanizing at 150 to 200°C for 10 to 30 minutes can be mentioned. Here, the base kneading step includes the masterbatch step and the remill step.

[0186] The tire of the present invention can be manufactured by a conventional method using the above rubber composition. That is, an unvulcanized rubber composition in which each of the above components is blended with the rubber component as necessary is extruded by an extruder equipped with a mandrel of a predetermined shape to conform to the shape of the rubber layer constituting the tread surface of the tread portion, and is laminated together with other tire members on a tire molding machine and molded by a conventional method to form an unvulcanized tire. The tire can be manufactured by heating and pressurizing this unvulcanized tire in a vulcanizer. The vulcanization conditions are not particularly limited, and examples include a method of vulcanizing at 150 to 200 ° C for 10 to 30 minutes.

[0187] <Use> Examples of the tire include pneumatic tires and non-pneumatic tires. Among them, pneumatic tires are preferred. The tire can be used for passenger car tires, large passenger car tires, large SUV tires, heavy load tires such as trucks and buses, light truck tires, two-wheeled vehicle tires, and race tires (high-performance tires). Among them, it can be preferably used for passenger car tires.

[0188] A passenger car tire is a tire assumed to be mounted on a four-wheel drive automobile, and refers to a tire having a maximum load capacity (normal load) of 1000 kg or less.

Examples

[0189] Hereinafter, examples (Examples) considered to be preferable in carrying out the invention will be shown, but the scope of the present invention is not limited to the examples. Using the various chemicals shown below, the tires obtained according to each table were examined, and the results calculated based on the following evaluation methods are shown at the bottom of each table.

[0190] <Various chemicals> The chemicals used in the examples and comparative examples will be collectively described below.

[0191] IR-based rubber: natural rubber (TSR20) SBR: SE-0212 manufactured by Sumitomo Chemical Co., Ltd. (amine-terminated modified S-SBR, styrene content: 25% by mass, vinyl content: 61.0 mol%) BR: Ube Pol BR150B manufactured by UBE Industries, Ltd. (cis content: 98% by mass, vinyl content: 1% by mass) Carbon black: Seast N220 (N2SA 114 m 2 / g, average primary particle size 23 nm) manufactured by Mitsubishi Chemical Corporation Silica: Ultrasil VN3 (N2SA 175 m 2 / g, average primary particle size: 17 nm) manufactured by Evonik Degussa Coupling agent 1: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa Coupling agent 2: bis{2-(imidazolidin-2-one-1-yl)ethyl}tetrasulfide Coupling agent 3: bis[10-{2-(imidazolidin-2-one-1-yl)ethylaminocarbonyl}decyl]tetrasulfide Oil: Diana Process NH-70S (aromatic process oil) manufactured by Idemitsu Kosan Co., Ltd. Wax: Oz Ace (registered trademark) 0355 manufactured by Nippon Seiro Co., Ltd. Antioxidant: No Crack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. Stearic acid: Tsubaki Bead Stearic Acid manufactured by NOF Corporation Zinc oxide: Zinc White No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Co., Ltd. Vulcanization accelerator 1: Noxeller NS (N-tert-butyl-2-benzothiazolylsulfenamide (TBBS)) manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. Vulcanization accelerator 2: Noxeller D (N,N'-diphenylguanidine (DPG)) manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.

[0192] <Manufacture of unvulcanized rubber composition> (Manufactured by normal kneading) According to the formulation in Table 1, using a 1.7L Banbury mixer, chemicals other than sulfur and vulcanization accelerators are kneaded for 5 minutes under the condition of a discharge temperature of 150°C to obtain a kneaded product. Sulfur and vulcanization accelerators are added to the kneaded product, and it is kneaded using an open roll until it reaches 105°C for 4 minutes to obtain an unvulcanized rubber composition.

[0193] (Manufacture by masterbatch) According to the formulation in Table 2, an unvulcanized rubber composition is manufactured by the masterbatch method.

[0194] That is, using a 1.0L pressure kneader, the chemicals related to Masterbatch 1 in Table 2 are kneaded for 4 minutes under the condition of a discharge temperature of 150°C to prepare Masterbatch 1.

[0195] Similarly, using a 1.0L pressure kneader, the chemicals related to Masterbatch 2 in Table 2 are kneaded for 4 minutes under the condition of a discharge temperature of 150°C to prepare Masterbatch 2.

[0196] The above Masterbatch 1 and Masterbatch 2, and the remaining chemicals other than sulfur and vulcanization accelerators are kneaded for 5 minutes using a 1.7L Banbury mixer under the condition of a discharge temperature of 150°C to obtain a kneaded product. Sulfur and vulcanization accelerators are added to the kneaded product, and it is kneaded using an open roll until it reaches 105°C for 4 minutes to obtain an unvulcanized rubber composition.

[0197]

Table 1

[0198]

Table 2

[0199] (Manufacture of test tires) (Tires to be manufactured) The tires to be manufactured are passenger car tires P and S described in the following table.

[0200] [Table 3]

[0201] (Manufacture of Tires) According to Tables 4 to 5, each of the above unvulcanized rubber compositions is molded into the shape of a tread and bonded together with other tire members, and vulcanized at 170 ° C for 15 minutes to obtain test tires for passenger cars (Tire P, Tire S).

[0202] [Abrasion Resistance Performance on Rough Roads] Each test tire was mounted on a domestic FF2000cc vehicle, and the groove depth of the tread portion of the tire was measured after driving on a rough road surface at a speed of 100 to 150 km / h for a driving distance of 5000 km. The driving distance when the tire groove depth decreased by 1 mm was calculated and indexed by the following formula. The larger the index, the better the abrasion resistance. Abrasion Resistance Index = (Driving Distance When Groove Depth Decreases by 1 mm) / (Driving Distance When Tire Groove of Reference Comparative Example Decreases by 1 mm) × 100

[0203] [Table 4]

[0204] [Table 5]

[0205] [Embodiment] Preferred embodiments are shown below.

[0206] [1] A tire comprising a tread, The rubber composition constituting the tread contains a rubber component containing isoprene rubber and styrene-butadiene rubber, silica, and a coupling agent, The tread surface of the tread has circumferential grooves continuously extending in the circumferential direction, The content (parts by mass) of isoprene rubber with respect to 100 parts by mass of the rubber component is AIR The content of styrene butadiene rubber (parts by mass) is A SBR The silica content (parts by mass) is A SIL and the groove depth (mm) of the deepest circumferential groove among the circumferential grooves is D, A IR , A SBR , A SIL and D satisfies the following relationship, preferably the right side of formula (1) is 1.09, and preferably the right side of formula (2) is 3.2, more preferably 4.0, and even more preferably 5.0. (1) A SIL / A SBR >1.00 (2) A IR / D>3.0 [2] The tire according to the above [1], wherein the right side of formula (1) is 1.50, preferably 1.59, more preferably 1.69, even more preferably 1.79, still more preferably 1.88, and even more preferably 2.00. [3] The tire according to the above [1] or [2], wherein the right side of formula (2) is 6.0, preferably 7.0, and more preferably 8.0. [4] The content (parts by mass) of the silica A SIL is more than 50 parts by mass and less than 200 parts by mass, preferably more than 60 parts by mass and less than 200 parts by mass, more preferably more than 70 parts by mass and less than 180 parts by mass, even more preferably more than 75 parts by mass and less than 150 parts by mass, and even more preferably more than 80 parts by mass and less than 120 parts by mass. [5] The rubber composition contains carbon black, and the content (parts by mass) of the carbon black per 100 parts by mass of the rubber component is A CB Then, A CB The tire according to any one of the above [1] to [4], wherein the amount of the carboxylic acid is more than 1 part by mass and less than 40 parts by mass, preferably more than 2 parts by mass and less than 35 parts by mass, more preferably more than 3 parts by mass and less than 20 parts by mass, even more preferably 5 parts by mass or more and less than 15 parts by mass, and even more preferably 5 parts by mass or more and less than 10 parts by mass. [6] The rubber composition contains carbon black, and the content (parts by mass) of the carbon black per 100 parts by mass of the rubber component is A CBWhen setting it as such, the content (parts by mass) A of the silica SIL and A CB satisfy the following relationship, preferably the right side of the above formula (3) is 0.70, more preferably 0.65, still more preferably 0.50, still more preferably 0.30, still more preferably 0.15. The tire according to any one of [1] to [5] above. (3) A CB / A SIL <0.80 [7] The average primary particle diameter of the silica is less than 25 nm, preferably less than 22 nm, more preferably less than 19 nm. The tire according to any one of [1] to [6] above. [8] When the land ratio (%) of the tread contact surface of the tread is L, the content (parts by mass) A of the silica SIL and L satisfy the following relationship, preferably the right side of the formula (4) is 3000, more preferably 3500, still more preferably 4000, still more preferably 5000. The tire according to any one of [1] to [7] above. (4) A SIL ×L>2500 [9] When the thickness (mm) of the rubber layer composed of the rubber composition constituting the tread is H and the total styrene amount (mass%) in the rubber component is S, H and S satisfy the following relationship, preferably the right side of the formula (5) is 220, more preferably 200, still more preferably 180, still more preferably 170. The tire according to any one of [1] to [8] above. (5) H×S<230

[10] The coupling agent includes a coupling agent containing a nitrogen atom-containing associative group. The tire according to any one of [1] to [9] above.

[11] The content of the coupling agent containing a nitrogen atom-containing associative group is more than 6 parts by mass and less than 12 parts by mass, preferably more than 7 parts by mass and less than 11 parts by mass, more preferably 8 parts by mass or more and less than 10 parts by mass with respect to 100 parts by mass of silica. The tire according to

[10] above.

[12] When the tire is incorporated into a rim and the internal pressure is 250 kPa or more, when the tire cross-sectional width is Wt (mm) and the tire outer diameter is Dt (mm), the tire according to any one of [1] to

[11] above, wherein Wt and Dt satisfy any one of the following formulas (A), (B), or (C). Wt < 225 and Dt ≥ 59.078 × Wt^0.460 ···(A) 225 ≤ Wt < 235 and Dt ≥ 59.078 × Wt^0.620 - 967.673 ···(B) 235 ≤ Wt and Dt ≥ Wt^0.6 + 750 ···(C)

[13] The tire according to any one of [1] to

[12] above, comprising at least one lateral groove extending in the tire width direction from the circumferential groove and remaining within the land portion.

Explanation of symbols

[0207] 1 Tire 2 Tread 3 Circumferential groove 4 Lateral groove D Groove depth H Thickness of rubber layer EP Tire equatorial plane Wt Tire cross-sectional width Dt Tire outer diameter Ht Tire cross-sectional height TW Tread contact width

Claims

1. A tire having a tread, wherein the rubber composition constituting the tread contains a rubber component including isoprene rubber and styrene-butadiene rubber, silica, and a coupling agent, the tread surface of the tread has circumferential grooves continuously extending in the circumferential direction, when the content (parts by mass) of isoprene rubber relative to 100 parts by mass of the rubber component is A IR and the content (parts by mass) of styrene-butadiene rubber is A SBR and the content (parts by mass) of silica is A SIL and the groove depth (mm) of the deepest circumferential groove among the circumferential grooves is D, a tire in which A IR , A SBR , A SIL and D satisfy the following relationship. (1) A SIL / A SBR > 1.00 (2) A IR / D > 3.0

2. The tire according to claim 1, wherein the right side of formula (1) is 1.

50.

3. The tire according to claim 1 or 2, wherein the right side of formula (2) is 6.

0.

4. The tire according to claim 1 or 2, wherein the content (parts by mass) A SIL of the silica is more than 50 parts by mass and less than 200 parts by mass.

5. The rubber composition contains carbon black, and when the content (parts by mass) of carbon black relative to 100 parts by mass of the rubber component is A CB , A CB is more than 1 part by mass and less than 40 parts by mass, the tire according to claim 1 or 2.

6. The rubber composition contains carbon black, and when the content (parts by mass) of carbon black relative to 100 parts by mass of the rubber component is A CB , the content (parts by mass) A SIL of the silica and A CB The tire according to claim 1 or 2, wherein the following relationship is satisfied. (3) A CB / A SIL < 0.80

7. The tire according to claim 1 or 2, wherein the average primary particle diameter of the silica is less than 19 nm.

8. When the land ratio (%) of the tread contact surface of the tread is L, the content (parts by mass) A of the silica SIL and L satisfy the following relationship. The tire according to claim 1 or 2. (4) A SIL ×L > 2500

9. When the thickness (mm) of the rubber layer composed of the rubber composition constituting the tread is H and the total styrene amount (mass%) in the rubber component is S, H and S satisfy the following relationship. The tire according to claim 1 or 2. (5) H×S < 230

10. The tire according to claim 1 or 2, wherein the coupling agent includes a coupling agent containing a nitrogen atom-containing associative group.

11. The tire according to claim 10, wherein the content of the coupling agent containing a nitrogen atom-containing associative group is more than 6 parts by mass and less than 12 parts by mass with respect to 100 parts by mass of silica.

12. When the tire is incorporated into a rim and the internal pressure is 250 kPa or more, when the tire cross-sectional width is Wt (mm) and the tire outer diameter is Dt (mm), Wt and Dt satisfy any one of the following formulas (A), (B), or (C). The tire according to claim 1 or 2. Wt < 225 and Dt ≧ 59.078×Wt^0.460... (A) 225 ≦ Wt < 235 and Dt ≧ 59.078×Wt^0.620 - 967.673... (B) 235 ≦ Wt and Dt ≧ Wt^0.6 + 750... (C)

13. The tire according to claim 1 or 2, comprising at least one lateral groove extending in the tire width direction from the circumferential groove and remaining within the land portion.

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