Tire

Abstract

Provided is a tire having improved overall performance of chipping resistance and wet grip performance. A tire having a tread portion, the tread portion being provided with at least a first layer constituting a tread surface, a second layer adjacent to the first layer on the inside in the tire radial direction, and a third layer present on the inside in the tire radial direction of the second layer, the first layer and the second layer are each configured from a rubber composition containing a styrene butadiene rubber and / or an isoprene rubber and silica, and at least one of the rubber compositions constituting the first layer and the second layer contains a copolymer resin containing styrene and cyclopentadiene as monomer components. When S1 (mass%) is the total styrene content in the rubber composition when the mass of the rubber component is 100 mass% in the rubber composition constituting the first layer, and S2 (mass%) is the total styrene content in the rubber composition when the mass of the rubber component is 100 mass% in the rubber composition constituting the second layer, S2-S1 is greater than 0.

Description

Technical Field

[0001] The present invention relates to a tire. Background Art

[0002] In Patent Document 1, there is described a rubber composition for a tire that improves handling stability and cut and chunk resistance by containing a mixture of natural rubber and / or butadiene rubber, a norbornene polymer, and a mixture of a zinc salt of an aliphatic carboxylic acid and a zinc salt of an aromatic carboxylic acid. [Prior Art Documents [Patent Documents

[0003] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2015-117310 Summary of the Invention [Problems to be Solved by the Invention

[0004] However, in Patent Document 1, there is still room for improvement in the comprehensive performance of chipping resistance and wet grip performance.

[0005] An object of the present invention is to provide a tire with improved comprehensive performance of chipping resistance and wet grip performance. [Means for Solving the Problems

[0006] The present invention relates to a tire, characterized in that it is a tire having a tread portion, the tread portion includes at least a first layer constituting the tread surface, a second layer adjacent to the first layer on the inner side in the tire radial direction, and a third layer existing on the inner side in the tire radial direction of the second layer, the first layer and the second layer are composed of a rubber composition containing a rubber component including styrene-butadiene rubber and / or isoprene-based rubber and silica, at least any one of the rubber compositions constituting the first layer and the second layer contains a copolymer resin including styrene and cyclopentadiene as monomer components, in the rubber composition constituting the first layer, when the mass of the rubber component is set to 100% by mass, the total styrene amount in the rubber composition is set to S1 (% by mass), in the rubber composition constituting the second layer, when the mass of the rubber component is set to 100% by mass, the total styrene amount in the rubber composition is set to S2 (% by mass), S2 - S1 > 0. [Advantages of the Invention

[0007] According to the present invention, a tire with improved comprehensive performance of chipping resistance and wet grip performance can be provided. Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Description of Reference Numerals

[0009] A tire according to an embodiment of the present invention is characterized in that it is a tire having a tread surface, and the tread surface at least includes a first layer constituting the tread surface, a second layer adjacent to the first layer on the inner side in the tire radial direction, and a third layer existing on the inner side in the tire radial direction of the second layer. The first layer and the second layer are composed of a rubber composition containing a rubber component including styrene-butadiene rubber and / or isoprene-based rubber and silica. At least any one of the rubber compositions constituting the first layer and the second layer contains a copolymer resin including styrene and cyclopentadiene as monomer components. In the rubber composition constituting the first layer, when the mass of the rubber component is set to 100% by mass, the total styrene amount in the rubber composition is set to S1 (% by mass). In the rubber composition constituting the second layer, when the mass of the rubber component is set to 100% by mass, the total styrene amount in the rubber composition is set to S2 (% by mass), and S2 - S1 is greater than 0.

[0010] Although it is not intended to be limited theoretically, in the tire of the present invention, as the principle of improving the comprehensive performance of the anti-blocking performance and the wet grip performance, for example, the following speculation can be made.

[0011] First, (1) by making the tread surface composed of three or more rubber compositions, multiple rubber layer interfaces are formed on the tread surface. It can be considered that, thus, when shear deformation occurs on the tread surface, energy loss can be generated based on the friction brought about by the fine molecular movement of each rubber phase constituting the interface, so it helps to improve the wet grip performance. At the same time, it can be considered that (2) by making the rubber compositions constituting the first layer and the second layer contain a rubber component including styrene-butadiene rubber and / or isoprene-based rubber and silica, the followability to the road surface is improved based on the interaction between the silanol groups of the silica and the moisture on the road surface, which helps to improve the wet grip performance. Further, it can be considered that the reinforcing property brought about by the silica also helps to improve the anti-blocking performance.

[0012] In addition, it can be considered that (3) by making at least any one of the rubber compositions constituting the first layer and the second layer contain a copolymer resin including styrene and cyclopentadiene as monomer components, since the resin has a large volume, softness can be imparted to the rubber composition without impairing the reinforcing effect, which helps to improve the wet grip performance.

[0013] Moreover, (4) by making S2 - S1 greater than 0, the amount of styrene in the first layer is relatively small, so the 30°C tanδ of the rubber composition constituting the first layer decreases, and heat generation at the tire contact surface during vehicle travel can be suppressed. It is considered that, thereby, an effect can be expected that the fracture characteristics of the entire rubber composition constituting the tread portion are less likely to deteriorate, thus contributing to an improvement in chunking resistance. On the other hand, the amount of styrene in the second layer is relatively large, and the 30°C tanδ of the rubber composition constituting the second layer increases. Therefore, in a situation where the tread portion is subjected to a large strain, such as when a vehicle travels on a rough road, good wet grip performance can be obtained. That is, it is considered that by setting S2 - S1 to be greater than 0, the heat generation due to deformation in the entire tread portion can be increased, and heat generation at the tread surface can be suppressed.

[0014] It is considered that through the synergistic effect of the above (1) to (4), a particularly remarkable effect of improving the comprehensive performance of chunking resistance and wet grip performance can be achieved.

[0015] When the thickness of the above first layer is set to t1 (mm), S1 × t1 is preferably less than 100.0.

[0016] It is considered that when S1 is large, by reducing the thickness of the first layer, the 30°C tanδ of the rubber composition constituting the first layer can be reduced, and the wet grip performance can be further improved.

[0017] Preferably, the rubber composition constituting the above second layer contains a copolymer resin containing styrene and cyclopentadiene as monomer components.

[0018] It is considered that by making the second layer contain this resin, the heat generation in the tread portion is increased based on the styrene component, and the wet grip performance is further improved.

[0019] The tanδ (30°C tanδ1) of the rubber composition constituting the above first layer at 30°C is preferably 0.30 or less.

[0020] It is considered that by setting 30°C tanδ1 within the above range, heat generation at the tread surface can be suppressed, and the chunking resistance can be further improved.

[0021] The complex elastic modulus (30°C E*2) of the rubber composition constituting the above second layer at 30°C is preferably 3.5 MPa or less.

[0022] It is considered that by setting 30°C E*2 within the above range, the fracture characteristics of the rubber composition in the tread portion can be reduced, and the chunking resistance can be further improved.

[0023] The rubber composition constituting the above first layer is preferably: containing 70 parts by mass or more of silica relative to 100 parts by mass of the above rubber component.

[0024] It can be considered that the reinforcement effect brought by silica can be obtained, and the chipping resistance performance is further improved.

[0025] S1 is preferably greater than 0 and less than 20.

[0026] It can be considered that by setting S1 within the above range, due to the interaction between styrene groups and silica, the followability to the road surface is improved. In addition, since the heat generation of the tire contact surface can be suppressed, the chipping resistance performance and wet grip performance are further improved.

[0027] The rubber composition constituting the second layer is preferably: containing 70 parts by mass or more of silica based on 100 parts by mass of the above rubber component.

[0028] It can be considered that the reinforcement effect brought by silica can be obtained, and the chipping resistance performance is further improved.

[0029] The modulus M2 of the rubber composition constituting the second layer at 200% elongation is preferably 7.0 MPa or less.

[0030] It can be considered that by setting the modulus of the rubber composition constituting the second layer at 200% elongation within the above range, when there is a deformation from the road surface that is not completely absorbed by the first layer, the second layer can deform softly, and good wet grip performance can be obtained.

[0031] The ratio (30°C tanδ2 / 30°C tanδ3) of the tanδ (30°C tanδ2) of the rubber composition constituting the second layer at 30°C to the tanδ (30°C tanδ3) of the rubber composition constituting the third layer at 30°C is preferably greater than 1.0.

[0032] It can be considered that by increasing the heat generation of the second layer relative to the heat generation of the rubber composition constituting the third layer, good wet grip performance can be further obtained in a situation where the tread surface strain is large, such as when a vehicle is traveling on a rough road.

[0033] The above tread surface preferably has a plurality of circumferential grooves continuously extending in the tire circumferential direction. When the thickness of the first layer is set as t1 (mm) and the groove depth of the deepest part of the circumferential groove is set as H (mm), t1 / H is 0.90 or less.

[0034] It can be considered that by making the deepest part of the circumferential groove exist on the inner side in the tire radial direction compared to the first layer, voids are generated in the second layer and its inner layer, and good wet grip performance can be further obtained in a situation where the tread surface strain is large, such as when a vehicle is traveling on a rough road.

[0035] Preferably, on at least one groove wall of the above circumferential groove, there is a recessed portion that is recessed outward in the groove width direction compared to the groove edge of the tread surface appearing on the above tread surface.

[0036] It can be considered that by providing the recessed portion on the groove wall of the circumferential groove, a void is formed inside the tread, and the impact can be absorbed in this void portion and the propagation can be suppressed.

[0037] [Definition] The "tread portion" is a component including the portion forming the ground contact surface of the tire. When there are components such as a belt layer or a belt reinforcing layer and a carcass layer formed of steel or textile material in the radial cross-section of the tire, it is disposed outside these components in the tire radial direction.

[0038] The "rubber component of the rubber composition" refers to the component participating in crosslinking in the rubber composition, and is usually a component having a weight average molecular weight (Mw) of 10,000 or more.

[0039] The "total styrene amount S in the rubber composition" refers to the total styrene amount (mass%) in the rubber composition when the mass of the rubber component is set to 100 mass%, and is the total amount of the styrene portion contained in the rubber component and the styrene portion contained in the compounding agent other than the rubber component. As the styrene portion, there is no particular limitation as long as it is a group having a styrene structure. For example, styrene, α-methylstyrene, vinyltoluene, chlorostyrene, etc. can be cited.

[0040] That is, first, for each rubber component, the value obtained by multiplying the content (mass%) of the styrene portion by the mass fraction in the rubber component is calculated, and the total value (mass%) obtained by summing these values is obtained. Then, for the compounding agent containing the styrene portion other than the rubber component contained in the rubber composition, the value obtained by multiplying the content (mass%) of the styrene portion in each compounding agent containing the styrene portion by the mass fraction relative to 100 mass parts of the rubber component is calculated, and the total value (mass%) obtained by summing them is obtained. The sum of these two total values is taken as the total styrene amount S (mass%). Therefore, it is calculated by {Σ (content (mass%) of the styrene portion of each rubber containing the styrene portion × content (mass%) of each rubber containing the styrene portion in the rubber component / 100) + Σ (content (mass%) of the styrene portion of each compounding agent containing the styrene portion other than the rubber component × compounding amount (mass parts) of each compounding agent containing the styrene portion relative to 100 mass parts of the rubber component / 100)}.

[0041] For example, the rubber component consists of 30% by mass of a first SBR (styrene content: 25%), 60% by mass of a second SBR (styrene content: 27.5%), and 10% by mass of BR. In the rubber composition, in addition to this rubber component, 20 parts by mass of a first resin having a styrene portion (styrene content: 5%) is further contained per 100 parts by mass of the rubber component, and 10 parts by mass of a second resin having a styrene portion (styrene content: 1%) is contained per 100 parts by mass of the rubber component. At this time, the total styrene amount S in the rubber composition relative to 100% by mass of the rubber component is 25.1% by mass = { (25×30 / 100 + 27.5×60 / 100 + 0×10 / 100) + (5×20 / 100 + 1×10 / 100)}.

[0042] The "normal state" means a non-loaded state in which it is assembled on a normal rim and filled with air at a normal internal pressure.

[0043] The "normal rim" means a rim whose standard is specified for each tire in a standard system including the standard on which the tire is based. For example, it refers to the standard rim in the applicable sizes described in the "JATMA YEAR BOOK" of JATMA (Japan Automobile Tire Manufacturers Association), the "Measuring Rim" described in the "STANDARDS MANUAL" of ETRTO (The European Tyre and Rim Technical Organisation), and the "Design Rim" described in the "YEAR BOOK" of TRA (The Tire and Rim Association, Inc.). Refer to them in the order of JATMA, ETRTO, and TRA, and follow the standard if there is an applicable size. In addition, for a tire not specified in the above standards, it means the rim with the smallest rim width among the rims with the smallest diameter that can be assembled and maintain the internal pressure (i.e., no air leakage occurs between the rim and the tire).

[0044] "Normal internal pressure" means: in the standard system that includes the standard on which the tire is based, the air pressure specified for each tire by this standard. For example, it refers to the "maximum air pressure" of JATMA, the "INFLATION PRESSURE" of ETRTO, and the maximum value recorded in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" of TRA. Similar to the case of the normal rim, it is referenced in the order of JATMA, ETRTO, and TRA, and when there are applicable dimensions during the reference, the standards thereof shall be followed. In addition, for a tire not specified in the above standards, it refers to the normal internal pressure (where it is 250 kPa or more) of other tire sizes (where the tire is specified in the standard) with the above normal rim as the standard rim. When there are multiple normal internal pressures of 250 kPa or more recorded, it refers to the minimum value among them.

[0045] "Normal load" is the load specified for each tire by the standard in the standard system that includes the standard on which the tire is based. For example, it refers to the "maximum load capacity" of JATMA, the "LOAD CAPACITY" of ETRTO, and the maximum value recorded in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" of TRA. Similar to the cases of the normal rim and normal internal pressure, it is referenced in the order of JATMA, ETRTO, and TRA, and when there are applicable dimensions during the reference, the standards thereof shall be followed. At the same time, for a tire not specified in the above standards, the maximum load capacity W L calculated separately shall be set as the normal load.

[0046] "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 radial direction of the cross-section of the tire based on the plane including the tire rotation axis (mm), and "Wt" is the cross-sectional width of the tire in the normal state (mm). When the rim diameter of the tire is set as R, Ht can be obtained by (Dt - R) / 2. When there are patterns or words on the tire sidewall, Wt is the value obtained after removing these. In addition, the maximum load capacity has the same meaning as the above normal load.

[0047]

Mathematical formula 1

[0048] "The dimensions of each part of the tire": Unless otherwise specified, the "dimensions of each part of the tire" appearing on the outer side of the tire are the values specified in the normal state. On the other hand, for the "dimensions of each part of the tire" existing inside the tire and in the tire cross-section, for example, it is the value specified in the state where the tire piece obtained by cutting with a plane containing the tire rotation axis is held with the rim width of the regular rim.

[0049] "The loss tangent (tanδ) and complex elastic modulus E* of the rubber composition" are the tanδ and complex elastic modulus E* (MPa) under each condition measured in the tensile mode using a dynamic viscoelasticity measuring device (for example, the EPLEXOR series manufactured by GABO). The sample used in the dynamic viscoelasticity measurement is a vulcanized rubber composition with a length of 20 mm × width of 4 mm × thickness of 1 mm. When cutting out and making a sample from the tire, when the part for making the sample is the tread portion, the length direction of the sample is made to coincide with the tire circumferential direction, and the thickness direction of the sample is made to coincide with the tire radial direction. In addition, the sample is made as close as possible to the state of the specified dimensions. The strain applied to the sample is normalized with respect to the length, and the measured tanδ is normalized with the width and thickness of the sample, so it can be considered that there is no influence based on the sample size.

[0050] "30°C tanδ" and "30°C E*" are the loss tangent (tanδ) and complex elastic modulus E* (MPa) measured under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of ±1%, and a tensile mode, respectively.

[0051] "The modulus at 200% elongation" is the stress (MPa) at 200% elongation when a No. 7 dumbbell-shaped test piece with a thickness of 1 mm is made and a tensile test is carried out in an atmosphere of 23°C at a tensile speed of 3.3 mm / second according to JIS K 6251:2017.

[0052] "Groove" means: A recessed part (extending radially inward of the tire) formed on the tread surface of the tire, and a recessed part with an opening width of 2.0 mm or more on the tread surface. A recessed part that is the same but less than 2.0 mm is called a "sipe".

[0053] "Circumferential groove" means: A groove that continuously extends in the tire circumferential direction. The circumferential groove can extend linearly in the circumferential direction, or can extend in a wave shape, sine shape, or zigzag shape in the circumferential direction.

[0054] The "content of the styrene portion" is calculated by pyrolysis gas chromatography. In addition, "pyrolysis gas chromatography" in this specification means a method of heating a sample with a pyrolysis device, separating each component contained in the gas components generated by this heating through a separation column, and analyzing the separated components.

[0055] The "vinyl content (amount of 1,2-bonded butadiene units)" is also calculated by pyrolysis gas chromatography.

[0056] The "cis content (amount of cis-1,4-bonded butadiene units)" is a value calculated by infrared absorption spectrometry according to JIS K 6239-2:2017, and is applicable to rubber components having repeating units derived from butadiene such as BR, for example.

[0057] The "weight-average molecular weight (Mw)" can be obtained by conversion with standard polystyrene based on the measured values according to gel permeation chromatography (GPC) (for example, GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKgel SuperMultipore HZ-M manufactured by Tosoh Corporation). For example, it is applicable to SBR, BR, plasticizers, etc.

[0058] The "nitrogen adsorption specific surface area of carbon black (N2SA)" is measured according to JIS K 6217-2:2017.

[0059] The "nitrogen adsorption specific surface area of silica (N2SA)" is measured by the BET method according to ASTM D3037-93.

[0060] The "average primary particle size" is a value obtained by taking a photograph of the particles with a transmission or scanning electron microscope and calculating the arithmetic average of the particle sizes of 400 particles. When the shape of the particles is spherical, the diameter of the sphere is defined as the particle size, and when it is other than spherical, the equivalent circle diameter calculated from the microscope image (the positive square root of {4 × (particle area) / π}) is defined as the particle size.

[0061] "Plasticizer" means a material that imparts plasticity to the rubber component and is a component that can be extracted from the rubber composition with acetone. In addition, plasticizers include plasticizers that are liquid (liquid state) at 25°C and plasticizers that are solid at 25°C. Among them, waxes and stearic acid commonly used in the tire industry are not included.

[0062] The "softening point of the resin" is the temperature at which the ball drops when measuring the softening point specified in JIS K 6220-1:2015 7.7 with a ring and ball softening point measuring device.

[0063] For the manufacturing sequence of a tire according to an embodiment of the present invention, the following description is an example for explaining the present invention, and the gist of the present invention is not limited to the scope of this description. In addition, in this specification, when a numerical range is represented by "~", it is assumed to include the numerical values at both ends.

[0064] <Tread surface> Figure 1 It is a cross-sectional view schematically showing a part of the tread of a tire according to an embodiment of the present invention. Figure 1 In this figure, the up-down direction is the tire radial direction, the left-right direction is the tire width direction, and the direction perpendicular to the paper surface is the tire circumferential direction.

[0065] The tread surface according to this embodiment has three or more rubber layers. The composition of the rubber layer is: the first layer constituting the tread surface, the second layer adjacent to the first layer on the inner side in the radial direction, and the third layer existing on the inner side in the radial direction of the second layer. Between the second layer and the third layer, or between the third layer and the belt layer, one or two or more rubber layers may be further provided.

[0066] From the viewpoint of the effects of the present invention, in the rubber composition constituting the first layer, when the mass of the rubber component is set to 100% by mass, the total styrene amount S1 in the rubber composition is preferably greater than 0, more preferably 5.0% by mass or more, further preferably 8.0% by mass or more, further preferably 10.0% by mass or more, further preferably 11.0% by mass or more, further preferably 12.0% by mass or more, and particularly preferably 15.0% by mass or more. In addition, from the viewpoint of the anti-blocking performance, S1 is preferably 40.0% by mass or less, more preferably 35.0% by mass or less, further preferably 30.0% by mass or less, and particularly preferably less than 20.0% by mass.

[0067] From the viewpoint of wet grip performance, in the rubber composition constituting the second layer, when the mass of the rubber component is set to 100% by mass, the total styrene amount S2 in the rubber composition is preferably 10.0% by mass or more, more preferably 12.0% by mass or more, further preferably 15.0% by mass or more, and particularly preferably 20.0% by mass or more. In addition, from the viewpoint of low fuel consumption performance, S2 is preferably 40.0% by mass or less, more preferably 35.0% by mass or less, further preferably 30.0% by mass or less.

[0068] From the viewpoint of the effects of the present invention, S2 - S1 is greater than 0% by mass, preferably greater than 3.0% by mass, more preferably greater than 5.0% by mass, further preferably greater than 7.0% by mass, further preferably greater than 10.0% by mass, further preferably greater than 11.0% by mass, and particularly preferably greater than 12.5% by mass. In addition, from the viewpoint of low fuel consumption performance, S2 - S1 is preferably less than 25.0% by mass, more preferably less than 22.0% by mass, further preferably less than 20.0% by mass, and particularly preferably less than 18.0% by mass.

[0069] In the rubber composition constituting the third layer, the total styrene amount S3 in the rubber composition when the mass of the rubber component is set to 100% by mass is not particularly limited. For example, it may also be 0% by mass.

[0070] In addition, the total styrene amount of the rubber composition can be appropriately adjusted by the types and compounding amounts of the following rubber components. For example, by compounding styrene - butadiene rubber with a high styrene content, resin containing styrene as a monomer component, etc., the total styrene amount S can be increased. Conversely, by reducing the compounding amount of styrene - butadiene rubber, etc., the total styrene amount S can be decreased.

[0071] From the viewpoint of anti - chunking performance, the 30°C tanδ (30°C tanδ1) of the rubber composition constituting the first layer is preferably 0.40 or less, more preferably 0.35 or less, and further preferably 0.30 or less. In addition, from the viewpoint of wet grip performance, 30°C tanδ1 is preferably 0.15 or more, more preferably 0.18 or more, and further preferably 0.20 or more.

[0072] From the viewpoint of low fuel consumption performance, the 30°C tanδ (30°C tanδ2) of the rubber composition constituting the second layer is preferably 0.50 or less, more preferably 0.40 or less, and further preferably 0.35 or less. In addition, from the viewpoint of wet grip performance, 30°C tanδ2 is preferably 0.10 or more, more preferably 0.15 or more, and further preferably 0.18 or more.

[0073] From the viewpoint of low fuel consumption performance, the 30°C tanδ (30°C tanδ3) of the rubber composition constituting the third layer is preferably 0.25 or less, more preferably 0.20 or less, and further preferably 0.15 or less. In addition, from the viewpoint of wet grip performance, 30°C tanδ2 is preferably 0.08 or more, more preferably 0.10 or more, and further preferably 0.12 or more.

[0074] From the viewpoint of wet grip performance, 30°C tanδ2 / 30°C tanδ3 is preferably greater than 1.0, more preferably greater than 1.5, and further preferably greater than 1.8. In addition, from the viewpoint of anti-blocking performance, 30°C tanδ2 / 30°C tanδ3 is preferably less than 2.5, more preferably less than 2.2, and further preferably less than 2.0.

[0075] In addition, the 30 tanδ of the rubber composition can be appropriately adjusted by the types and compounding amounts of the following rubber components, fillers, plasticizers, etc. For example, 30°C tan can be increased by increasing the total styrene amount of the rubber composition.

[0076] From the viewpoint of anti-blocking performance, the complex elastic modulus (30°C E*2) of the rubber composition constituting the second layer at 30°C is preferably 5.0 MPa or less, more preferably 4.0 MPa or less, and further preferably 3.5 MPa or less. In addition, from the viewpoint of wet grip performance, 30°C E*2 is preferably 2.0 MPa or more, more preferably 2.3 MPa or more, and further preferably 2.5 MPa or more.

[0077] From the viewpoint of anti-blocking performance, the complex elastic modulus (30°C E*1) of the rubber composition constituting the first layer at 30°C is preferably 6.0 MPa or less, more preferably 5.5 MPa or less, and further preferably 5.2 MPa or less. In addition, from the viewpoint of wet grip performance, 30°C E*1 is preferably 2.5 MPa or more, more preferably 2.8 MPa or more, and further preferably 3.0 MPa or more.

[0078] From the viewpoint of low fuel consumption performance, the complex elastic modulus (30°C E*3) of the rubber composition constituting the third layer is preferably 2.0 MPa or less, more preferably 1.8 MPa or less, and further preferably 1.6 MPa or less. In addition, from the viewpoint of wet grip performance, 30°C E* is preferably 1.0 MPa or more, more preferably 1.2 MPa or more, and further preferably 1.4 MPa or more.

[0079] From the viewpoint of the effects of the present invention, the modulus (M2) of the rubber composition constituting the second layer at 200% elongation is preferably 7.5 MPa or less, more preferably 7.0 MPa or less, and further preferably 6.8 MPa or less. In addition, from the viewpoint of anti-blocking performance, M2 is preferably 4.5 MPa or more, more preferably 5.0 MPa or more, and further preferably 6.0 MPa or more.

[0080] From the perspective of the effects of the present invention, the modulus (M1) of the rubber composition constituting the first layer at 200% elongation is preferably 10.0 MPa or less, more preferably 9.0 MPa or less, and further preferably 8.8 MPa or less. In addition, from the perspective of the chip resistance performance, M1 is preferably 6.5 MPa or more, more preferably 7.0 MPa or more, and further preferably 7.5 MPa or more. In addition, the modulus (M3) of the rubber composition constituting the third layer at 200% elongation is not particularly limited.

[0081] Figure 1 Among them, the double arrow t1 is the thickness of the first layer 6, the double arrow t2 is the thickness of the second layer 7, and the double arrow t3 is the thickness of the third layer 8. Figure 1 Among them, the grounding portion 2 is represented by the symbol P at the midpoint in the tire width direction. The straight line represented by the symbol N is a straight line (normal line) passing through the point P and perpendicular to the tangent plane at that point P. In this specification, the thicknesses t1, t2, and t3 are Figure 1 measured along the normal line N drawn from the point P on the tread surface at a position without grooves in the cross-section.

[0082] From the perspective of the chip resistance performance, the thickness t1 of the first layer is preferably 1.5 mm or more, more preferably 1.8 mm or more, and further preferably 2.0 mm or more. In addition, from the perspective of the wet grip performance, t1 is preferably 6.0 mm or less, further preferably 5.5 mm or less, further preferably 5.0 mm or less, and particularly preferably 4.0 mm or less.

[0083] The thickness t2 of the second layer is preferably 2.0 mm or more, more preferably 3.0 mm or more, and further preferably 3.5 mm or more. In addition, t2 is preferably 10.0 mm or less, more preferably 8.0 mm or less, and further preferably 7.0 mm or less.

[0084] The thickness t3 of the third layer is preferably 0.5 mm or more, more preferably 1.0 mm or more, and further preferably 1.5 mm or more. In addition, t3 is preferably 5.0 mm or less, more preferably 4.5 mm or less, and further preferably 4.0 mm or less.

[0085] From the perspective of the effects of the present invention, S1×t1 is preferably less than 110.0, more preferably less than 100.0, more preferably less than 95.0, and further preferably less than 90.0. In addition, from the perspective of ensuring that S1 and t1 are above a certain value, S1×t1 is preferably greater than 20.0, more preferably greater than 30.0, and further preferably greater than 40.0.

[0086] The tread surface portion involved in this embodiment preferably has a plurality of circumferential grooves 1 that continuously extend in the tire circumferential direction. The circumferential grooves 1 may extend linearly in the circumferential direction or may extend in a serrated shape in the circumferential direction. In addition, the tread surface portion involved in this embodiment preferably has a grounding portion 2 divided by the circumferential grooves 1 in the tire width direction.

[0087] The groove depth H of the deepest part of the circumferential groove 1 can be obtained by the distance between the extension line 4 of the tread surface 3 and the extension line 5 of the deepest part of the groove bottom of the circumferential groove 1. In addition, for example, when there are a plurality of circumferential grooves 1, the groove depth H can be set as the distance between the extension line 4 of the tread surface 3 and the extension line 5 of the deepest part of the groove bottom of the circumferential groove 1 with the deepest groove depth among the plurality of circumferential grooves 1 ( Figure 1 in this case, it is the left circumferential groove 1).

[0088] <Circumferential groove> Figure 2 shows an enlarged plan view of the circumferential groove 1 involved in one embodiment of the present invention. Figure 2 In, the groove edge 10 of the circumferential groove 1 is represented by a solid line, and the contour 12 of the groove wall when looking down at the tread surface portion is represented by a dotted line. In addition, the recessed area (recess portion 11) between the groove edge 10 and the contour 12 of the groove wall of the circumferential groove 1 is represented by small dots.

[0089] Figure 3 shows Figure 2 the cross-sectional view taken along the line A-A of the circumferential groove 1 shown. As Figure 3 shown, in the circumferential groove 1, recessed portions 11 with a constant recess amount in the tire circumferential direction are provided on both side groove walls. The recessed portions 11 form a plane 44, for example, between the deepest part of the recessed portion and the groove edge 10, but are not limited to such a form.

[0090] The total recess amount of the circumferential groove 1 is preferably 0.10 to 0.90 times, more preferably 0.15 to 0.80 times, and further preferably 0.20 to 0.70 times the groove width W1 of the circumferential groove 1. In addition, in this specification, when the circumferential groove 1 is in the Figure 3 form, the "total recess amount of the circumferential groove" refers to c1 + c2.

[0091] [Rubber composition] The rubber composition (hereinafter, sometimes referred to as the rubber composition involved in this embodiment) constituting the first layer or the second layer of the tread surface portion involved in this embodiment contains a rubber component including styrene-butadiene rubber (SBR) and / or isoprene-based rubber and silica. At least any one of the rubber compositions constituting the first layer and the second layer is a composition containing a copolymer resin including styrene and cyclopentadiene as monomer components, and any one of them can be manufactured using the raw materials described below. Hereinafter, the rubber composition involved in this embodiment will be described.

[0092] <Rubber component> As the rubber component, a diene rubber is preferably contained. As the diene rubber, a rubber component commonly used in the tire industry can be optionally preferably used. Specifically, for example, isoprene rubber, butadiene rubber (BR), SBR, styrene-isoprene rubber (SIR), styrene-isoprene-butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), etc. can be cited. These diene rubbers can be used alone or in combination of two or more.

[0093] The content of the diene rubber in the rubber component of the rubber composition according to the present embodiment is preferably 90% by mass or more, more preferably 95% by mass or more, and further preferably 99% by mass or more. The rubber component can also be only a diene rubber component.

[0094] (SBR) There is no particular limitation on SBR, and solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), modified SBRs (modified S-SBR, modified E-SBR) thereof, etc. can be cited. As the modified SBR, SB modified at the terminal and / or main chain; modified SBR coupled with tin, silicon compounds, etc. (condensates, substances having a branched structure, etc.) can be cited. These SBRs can be used alone or in combination of two or more.

[0095] From the viewpoint of the effects of the present invention, the content of the styrene portion of SBR is preferably greater than 18% by mass, more preferably greater than 20% by mass, and further preferably greater than 25% by mass. On the other hand, the content of the styrene portion of SBR is preferably less than 60% by mass, more preferably less than 50% by mass, and further preferably less than 45% by mass. When the content of the styrene portion of SBR is greater than 60% by mass, styrene groups are adjacent to each other, the polymer does not become too hard, crosslinking easily becomes uneven, the blowability during high-temperature driving may deteriorate, the temperature correlation increases, the performance change with respect to temperature change increases, and it tends to be impossible to obtain stable grip performance during driving and in the later stage. In addition, in the present specification, the content of the styrene portion of SBR is measured by the above-mentioned measurement method.

[0096] The vinyl content of SBR is preferably greater than 10 mol%, more preferably greater than 15 mol%, and further preferably greater than 20 mol%. In addition, the vinyl content of SBR is preferably less than 70 mol%, more preferably less than 65 mol%, and further preferably less than 60 mol%. In addition, in the present specification, the vinyl content of SBR is measured by the above-mentioned measurement method.

[0097] From the viewpoint of wet grip performance, the glass transition temperature (Tg) of SBR is preferably -80°C or higher, more preferably -70°C or higher, and further preferably -65°C or higher. In addition, from the viewpoint of low fuel consumption performance, the Tg of SBR is preferably -40°C or lower, more preferably -45°C or lower, further preferably -50°C or lower, and further preferably -55°C or lower. In addition, the Tg of SBR in this specification can be determined by differential scanning calorimetry (DSC) according to JIS K7121 for the pure SBR component after removing extender oil with acetone according to JIS K 6229.

[0098] The weight average molecular weight (Mw) of SBR is preferably greater than 200,000, more preferably greater than 300,000, further preferably greater than 400,000, and particularly preferably greater than 500,000. In addition, from the viewpoints of crosslinking uniformity, etc., Mw is preferably less than 2,000,000, more preferably less than 1,500,000, and further preferably less than 1,000,000. In addition, the Mw of SBR is measured by the above-mentioned measurement method.

[0099] As SBR, oil-extended SBR or non-oil-extended SBR can be used. In this specification, as SBR, commercially available substances from companies such as JSR Corporation, Sumitomo Chemical Co., Ltd., UBE Industries, Ltd., Asahi Kasei Corporation, ZS ELASTOMERS Co., Ltd., and ARLANXEO can be used.

[0100] The content of SBR in the rubber component constituting the first layer can be appropriately set such that S2 - S1 and S1×t1 are within the above ranges, but is preferably 20% by mass or more, more preferably 30% by mass or more, further preferably 40% by mass or more, further preferably 50% by mass or more, and particularly preferably 60% by mass or more. In addition, the content of this SBR in the rubber component is preferably 90% by mass or less, and more preferably 80% by mass or less.

[0101] The content of SBR in the rubber component constituting the second layer can be appropriately set such that S2 - S1 is within the above range, but is preferably 25% by mass or more, more preferably 35% by mass or more, further preferably 45% by mass or more, further preferably 55% by mass or more, further preferably 65% by mass or more, and particularly preferably 70% by mass or more. In addition, the content of this SBR in the rubber component is preferably 95% by mass or less, and more preferably 90% by mass or less.

[0102] (Isoprene rubber) As the isoprene rubber, for example, substances commonly used in the tire industry such as isoprene rubber (IR) and natural rubber can be used. In natural rubber, in addition to unmodified natural rubber (NR), modified natural rubbers such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), high-purity natural rubber, and grafted natural rubber can also be contained. These isoprene rubbers can be used alone or in combination of two or more.

[0103] As NR, there is no particular limitation, and substances commonly used in the tire industry can be used. For example, SIR20, RSS#3, TSR20, etc. can be cited.

[0104] The content of the isoprene rubber in the rubber components constituting the first layer and the second layer is preferably 1% by mass or more, more preferably 5% by mass or more, and further preferably 10% by mass or more. In addition, the content is preferably 60% by mass or less, more preferably 50% by mass or less, and further preferably 40% by mass or less.

[0105] (BR) As BR, there is no particular limitation. For example, BR with a cis content of less than 50 mol% (low-cis BR), BR with a cis content of 90 mol% or more (high-cis BR), rare-earth series butadiene rubber synthesized with a rare-earth element series catalyst (rare-earth series BR), BR containing syndiotactic polybutadiene crystals (BR containing SPB), modified BR (high-cis modified BR, low-cis modified BR), etc., which are commonly used in the tire industry, can be used. These BRs can be used alone or in combination of two or more.

[0106] As high-cis BR, for example, substances commercially available from Zeon Corporation, UBE Corporation, JSR Corporation, etc. in Japan can be used. By containing high-cis BR, the low-temperature characteristics and abrasion resistance can be improved. The cis content of high-cis BR is preferably greater than 95 mol%, more preferably greater than 96 mol%, and further preferably greater than 97 mol%. In addition, the cis content of BR is measured by the above-mentioned measurement method.

[0107] As the rare-earth series BR, it is synthesized with a rare-earth element series catalyst, the vinyl content is preferably less than 1.8 mol%, more preferably less than 1.6 mol%, and further preferably 1.5 mol% or less, and the cis content is preferably greater than 95 mol%, more preferably greater than 96 mol%, and further preferably 97 mol% or more. As the rare-earth series BR, for example, substances commercially available from Lanxess Corporation, etc. can be used.

[0108] The BR containing SPB, such as syndiotactic 1,2-polybutadiene crystals, is not simply dispersed in BR, but a substance that disperses crystals by bonding chemically with BR. As such BR containing SPB, commercially available substances from companies such as UBE Industries, Ltd. can be used.

[0109] As modified BR, in addition to BR modified with the same functional groups as those described in the above SBR, etc., modified butadiene rubber (modified BR) modified at the terminal and / or main chain with functional groups containing at least one element selected from silicon, nitrogen, and oxygen is also preferably used.

[0110] As other modified BR, there can be mentioned modified BR obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and further, modified BR in which a tin-carbon bond is bonded to the terminal of the modified BR molecule (tin-modified BR), etc. In addition, the modified BR can be either unhydrogenated modified BR or hydrogenated modified BR.

[0111] From the viewpoint of abrasion resistance, the weight-average molecular weight (Mw) of BR is preferably greater than 300,000, more preferably greater than 350,000, and further preferably greater than 400,000. In addition, from the viewpoints of crosslinking uniformity, etc., it is preferably less than 2,000,000, more preferably less than 1,000,000, and further preferably less than 500,000. In addition, Mw can be determined by the above method.

[0112] The content of BR in the rubber components constituting the first layer and the second layer is not particularly limited, and is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 20% by mass or more. In addition, the content of this BR in the rubber components is preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 30% by mass or less.

[0113] (Other rubber components) Within the range that does not affect the effects of the present invention, the rubber components can further contain rubber components other than diene rubbers (non-diene rubbers). As non-diene rubbers, rubber components commonly used in the tire industry can be used. For example, there can be mentioned butyl rubbers, ethylene-propylene rubbers, polynorbornene rubbers, silicone rubbers, chlorinated polyethylene rubbers, fluororubbers (FKM), acrylic rubbers (ACM), epichlorohydrin rubbers, etc. These other rubber components can be used alone or in combination of two or more. In addition, in addition to the above rubber components, known thermoplastic elastomers can be contained or not contained.

[0114] (Rubber components synthesized from recycled / biomass-derived raw materials) The monomers that are the constituent units of synthetic rubbers such as SBR and BR can be substances derived from petroleum, or substances recovered from rubber products such as tires or non-rubber products such as polystyrene. As the monomers obtained by recycling (recycled monomers), there is no particular limitation, and examples include recycled butadiene, recycled aromatic vinyl compounds, etc. As the above-mentioned butadiene, 1,2-butadiene and 1,3-butadiene can be cited. As the above-mentioned aromatic vinyl compound, there is no particular limitation, and examples include styrene, etc. Among them, it is preferable to use recycled butadiene (recycled butadiene) and / or recycled styrene (recycled styrene) as raw materials.

[0115] As the method for manufacturing recycled monomers, there is no particular limitation. For example, it can be cited as synthesized from recycled naphtha obtained by pyrolyzing rubber products such as tires. In addition, as the method for manufacturing recycled naphtha, there is no particular limitation. For example, rubber products such as tires can be pyrolyzed under high temperature and high pressure, or pyrolyzed with microwaves, or extracted after mechanical pulverization.

[0116] Furthermore, the monomers that are the constituent units of polymers such as SBR and BR can also be substances derived from biomass. As the monomers derived from biomass (biomass monomers), there is no particular limitation, and examples include biomass-derived butadiene, biomass-derived aromatic vinyl compounds, etc. As the above-mentioned butadiene, 1,2-butadiene and 1,3-butadiene can be cited. As the above-mentioned aromatic vinyl compound, there is no particular limitation, and examples include styrene, etc. In addition, the method for manufacturing biomass monomers is not particularly limited. For example, substances obtained by biological and / or chemical and / or physical conversion of animals and plants can be cited. As biological conversion, fermentation based on microorganisms is representative. As chemical and / or physical conversion, conversion based on catalysts, conversion based on high heat, conversion based on high pressure, conversion based on electromagnetic waves, conversion based on supercritical fluids, and combinations thereof can be cited. As the biomass sources of these monomers, substances derived from sugar, wood, plant residues after obtaining useful components, ethanol of plants, biomass naphtha, etc. can be cited.

[0117] As the polymers synthesized from biomass monomer components (biomass polymers), there is no particular limitation, and examples include polybutadiene rubber synthesized from biomass-derived butadiene, aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl compounds, etc. As the above-mentioned aromatic vinyl / butadiene copolymer, for example, styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene can be cited.

[0118] Whether the raw materials of the polymer are derived from biomass can be judged by pMC (percent Modern Carbon) determined according to ASTM D6866-10. pMC means: the 14 C concentration relative to that of the standard modern carbon 14 is the ratio of the C concentration, and is a value used as an index representing the biomass ratio of the compound. The meaning of this value is described below.

[0119] In 1 mole (6.02×10 23 ), there is about one trillionth of the normal carbon atoms, that is, about 6.02×10 11 14 C. 14 The half-life of 14 C is 5730 years, and 14 C decreases regularly. Therefore, it can be considered that after carbon dioxide in the atmosphere is absorbed and immobilized by plants, etc., in fossil fuels such as coal, oil, and natural gas that have experienced more than 226,000 years, all of the 14 C elements contained at the initial immobilization have decayed. Therefore, in the 21st century today, fossil fuels such as coal, oil, and natural gas do not contain 14 C elements at all. Therefore, chemical substances produced from these fossil fuels also do not contain

[0120] On the other hand, 14 C is continuously generated by nuclear reactions in the atmosphere through cosmic rays. Therefore, 14 the decrease of 14 C due to radioactive decay and the generation due to nuclear reactions reach an equilibrium, and in the atmospheric environment of the earth, 14 the -12 C concentration of substances from biomass resources in the material cycle is about 1×10

[0121] mol% relative to all carbon atoms as described above. Therefore, using the difference between these values, the proportion (biomass ratio) of the compound (rubber) derived from natural resources (compound derived from biomass resources) in a certain compound can be calculated. 14 C is usually measured as follows. Using accelerator mass spectrometry based on a tandem accelerator, the 13 C concentration ( 13 C / 12 C), 14 C concentration ( 14 C / 12 C) are measured. When measuring, as 14 ​As the reference standard of the concentration of C, modern carbon is used, which is the 14 C concentration in the cyclic carbon in nature in 1950. As a specific reference material, the oxalic acid reference material provided by NIST (National Institute of Standards and Technology) is used. The specific radioactivity of carbon in this oxalic acid (the radioactivity intensity of 14 C per 1 g of carbon) is classified according to each carbon isotope, and 13 C is corrected to a fixed value, and the value after applying the decay correction from 1950 AD to the measurement date is used as the standard 14 C concentration value (100%). The ratio of the value of the actually measured sample to this value is the pMC value.

[0122] Therefore, if the rubber is made of materials derived from 100% biomass (natural type), although there are regional differences, etc., since it is mostly not 100 under normal conditions now, it is expected to show a value of about 110 pMC (under normal conditions now, it is generally not 100). On the other hand, for chemical substances derived from fossil fuels such as petroleum, when measuring the 14 C concentration, a value of about 0 pMC (for example, 0.3 pMC) is shown. This value corresponds to a biomass ratio of 0%.

[0123] In summary, it is environmentally preferable to use rubber and other materials with a high pMC value, that is, rubber and other materials with a high biomass ratio, in the rubber composition.

[0124] [Filler] The rubber composition according to this embodiment preferably contains a filler. The rubber compositions constituting the first layer and the second layer contain silica, and preferably contain silica and carbon black. In addition, the filler can also be a filler composed only of carbon black and silica.

[0125] [Silica] There is no particular limitation on the silica. For example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrous silica), etc., which are commonly used in the tire industry, can be used. There is no particular limitation on the raw material of the silica. For example, it can be a raw material derived from minerals such as quartz, or a raw material derived from organisms such as rice husks (for example, silica using biomass materials such as rice husks as raw materials), and silica recovered from products containing silica can also be used. Among them, due to the large number of silanol groups, hydrous silica prepared by a wet method is preferred. These silicas can be used alone or in combination of two or more.

[0126] Silica made from biomass materials can be obtained, for example, by extracting silicate from rice husk ash obtained by burning rice husks with a sodium hydroxide solution, and reacting the silicate with sulfuric acid in the same manner as conventional wet silica to produce a silica precipitate, which is then filtered, washed with water, dried, and pulverized.

[0127] Silica recovered from products containing silica, for example, silica recovered from products containing silica such as electronic components such as semiconductors, tires, desiccants, diatomaceous earth and other filter materials can be used. In addition, the recovery method is not particularly limited, and thermal cracking, electromagnetic wave cracking and the like can be cited. Among them, silica recovered from electronic components such as semiconductors or tires is preferred.

[0128] If silicon dioxide is crystallized, it is insoluble in water and silicic acid, which is its component, cannot be used. By managing the combustion temperature and combustion time, the crystallization of silicon dioxide in rice husk ash can be suppressed (see Japanese Patent Publication No. 2009-2594, Akita Prefectural University Online Journal B (Akita Prefectural University ウェブジャーナルB) / 2019, vol.6, p.216-222, etc.). Amorphous silicon dioxide extracted from rice husks can use commercially available substances such as Wilmar.

[0129] From the viewpoint of reinforcement and ensuring grip performance, the nitrogen adsorption specific surface area (N2SA) of silica is preferably 100 m 2 / g or more, more preferably 120m 2 / g or more, more preferably 140m 2 / g or more, more preferably 160m 2 / g or more, particularly preferably 170m 2 / g or more. In addition, from the viewpoint of processability, 350 m 2 / g or less, more preferably 300m 2 / g or less, more preferably 250m 2 / g or less. In addition, the N2SA of silica is measured by the above-mentioned measurement method.

[0130] The average primary particle size of silicon dioxide is preferably more than 10nm, more preferably more than 12nm, further preferably more than 14nm, and particularly preferably more than 16nm. In addition, the average primary particle size is preferably less than 24nm, more preferably less than 22nm, and further preferably less than 20nm. In addition, the average primary particle size of silicon dioxide is measured by the above-mentioned determination method.

[0131] In the rubber composition constituting the first layer, the content of silica relative to 100 parts by mass of the rubber component is preferably more than 50 parts by mass, more preferably more than 60 parts by mass, still more preferably 70 parts by mass or more, and still more preferably more than 70 parts by mass. Further, from the viewpoint of wet grip performance, the content of silica relative to 100 parts by mass of the rubber component is preferably less than 110 parts by mass, more preferably less than 100 parts by mass, still more preferably less than 90 parts by mass.

[0132] In the rubber composition constituting the second layer, the content of silica relative to 100 parts by mass of the rubber component is preferably more than 50 parts by mass, more preferably more than 60 parts by mass, still more preferably 70 parts by mass or more. Further, the content of silica relative to 100 parts by mass of the rubber component is preferably less than 110 parts by mass, more preferably less than 100 parts by mass, still more preferably less than 90 parts by mass.

[0133] <Silane coupling agent> Silica is preferably used in combination with a silane coupling agent. There is no particular limitation on the silane coupling agent. For example, sulfur-containing silane coupling agents such as bis(3-triethoxysilylpropyl) disulfide and bis(3-triethoxysilylpropyl) tetrasulfide can be cited; mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane; vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silane coupling agents such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-(2-aminoethyl)aminopropyltriethoxysilane; 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, etc. Among them, it is preferable to contain a sulfur-containing silane coupling agent and / or a mercapto-based silane coupling agent. As the silane coupling agent, for example, commercially available substances from Evonik Degussa AG, Momentive Performance Materials Inc., etc. can be used. These silane coupling agents can be used alone or in combination of two or more.

[0134] From the viewpoint of improving the dispersibility of silica, the content of the silane coupling agent relative to 100 parts by mass of the rubber component (when multiple silane coupling agents are used in combination, it is the total amount of all) is preferably more than 3.0 parts by mass, more preferably more than 5.0 parts by mass, still more preferably 6.0 parts by mass or more. Further, from the viewpoint of preventing a decrease in abrasion resistance, it is preferably less than 15 parts by mass, more preferably less than 10 parts by mass, still more preferably less than 9.0 parts by mass.

[0135] <Carbon Black> As carbon black, there is no particular limitation, and N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. can be cited. The raw material of carbon black can be a biomass material such as lignin and vegetable oil, or a pyrolysis oil obtained by pyrolysis of waste tires. In addition, the manufacturing method of carbon black can be a combustion-based method such as a furnace method, a method based on hydrothermal carbonization (HTC), or a method based on thermal cracking of methane derived from a thermal cracking carbon black method. As a commercial product, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Black Co., Ltd., Columbia Carbon Co., Ltd., etc. can be used. These can be used alone or in combination of two or more.

[0136] In addition to the above, from the viewpoint of life cycle assessment, carbon black made from biomass materials such as lignin, or recycled carbon black obtained by pyrolysis and purification of products containing carbon black such as tires can also be used as carbon black.

[0137] In this specification, "regenerated carbon black" refers to carbon black obtained by crushing used tires and other products containing carbon black and burning the crushed product, and the mass ratio of the non-combustible component, that is, the ash content (ash content) is 13% by mass or more when it is heated in air for oxidative combustion by thermogravimetric measurement based on JIS K 6226-2:2003. That is, the mass ratio (carbon content) of the reduced part of the regenerated carbon black based on the above-mentioned oxidative combustion is 87% by mass or less. Regenerated carbon black is sometimes also represented by rCB.

[0138] Regenerated carbon black can be obtained by the thermal cracking process of used pneumatic tires. For example, European Patent Application Publication No. 3427975 states that Rubber Chemistry and Technology, Vol. 85, No. 3, pp. 408-449 (2012), especially pp. 438, 440, 442, mentions that it can be obtained by thermal cracking of organic materials at 550-800° C. after removing oxygen, or by vacuum thermal cracking at relatively low temperatures (

[0027] ). The carbon black obtained by such a thermal cracking process is generally a regenerated carbon black lacking functional groups on its surface, as mentioned in

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

[0139] The recycled carbon black may be carbon black lacking functional groups on its surface, or may be carbon black that has been treated to have functional groups on its surface. The treatment for making the surface of the recycled carbon black contain functional groups can be carried out by conventional methods. For example, in European Patent Application Publication No. 3173251, carbon black obtained by a thermal cracking process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl groups and / or carboxyl groups on its surface. In addition, in Patent No. 6856781, carbon black obtained by a thermal cracking process is treated with an amino acid compound containing at least one mercapto group or disulfide group to obtain carbon black with an activated surface. The recycled carbon black involved in this embodiment includes such carbon black treated to have functional groups on its surface.

[0140] Commercially available substances such as those from Strable Green Carbon and LD Carbon can be used as the recycled carbon black.

[0141] The average primary particle diameter of the carbon black is preferably 15 nm or more, more preferably 18 nm or more, further preferably 20 nm or more, and particularly preferably 22 nm or more. On the other hand, from the viewpoint of obtaining reinforcement, the average primary particle diameter is preferably 100 nm or less, more preferably 80 nm or less, further preferably 50 nm or less. In addition, the average primary particle diameter of the carbon black is measured by the above-mentioned measurement method.

[0142] From the viewpoint of the effects of the present invention, the nitrogen adsorption specific surface area (N2SA) of the carbon black is preferably 200 m 2 / g or less, more preferably 180 m 2 / g or less, further preferably 150 m 2 / g or less. In addition, the N2SA is preferably 30 m 2 / g or more, more preferably 40 m 2 / g or more, further preferably 45 m 2 / g or more. In addition, the N2SA of the carbon black is measured by the above-mentioned measurement method.

[0143] When the rubber composition constituting the first layer or the second layer contains carbon black, from the viewpoint of reinforcement, its content relative to 100 parts by mass of the rubber component is preferably more than 3 parts by mass, more preferably more than 5 parts by mass, further preferably more than 9 parts by mass. In addition, from the viewpoint of obtaining softness and stress relaxation, it is preferably less than 50 parts by mass, more preferably less than 40 parts by mass, further preferably less than 30 parts by mass, and particularly preferably less than 20 parts by mass.

[0144] <Other fillers> The filler may also contain other fillers other than silica and carbon black. There is no particular limitation on the other fillers. For example, substances commonly used in the tire industry in the past, such as aluminum hydroxide, calcium carbonate, bauxite, clay, talc, etc., can be compounded.

[0145] [Other compounding agents] In the rubber composition according to this embodiment, in addition to the rubber component and the filler, compounding agents commonly used in the tire industry in the past can be appropriately contained. For example, plasticizers, processing aids, vulcanized rubber particles, waxes, stearic acid, zinc oxide, anti-aging agents, vulcanizing agents, vulcanization accelerators, etc. At least any one of the rubber compositions constituting the first layer and the second layer contains a copolymer resin containing styrene and cyclopentadiene as monomer components. Preferably, the rubber composition constituting the first layer contains a copolymer resin containing styrene and cyclopentadiene as monomer components.

[0146] [Plasticizer] A plasticizer refers to a material that imparts plasticity to the rubber component, and is a concept including both plasticizers that are liquid (liquid state) at 25°C and plasticizers that are solid at 25°C. Examples of plasticizers include resins, oils, liquid polymers, ester-based plasticizers, etc. These plasticizers can be substances derived from petroleum, substances derived from biomass, or substances derived from naphtha recovered from rubber products and non-rubber products. In addition, low-molecular-weight hydrocarbon components obtained by thermally cracking and extracting used tires and products containing various components can also be used as plasticizers. These plasticizers can be used alone or in combination of two or more.

[0147] [Copolymer resin containing styrene and cyclopentadiene as monomer components] As the copolymer resin containing styrene and cyclopentadiene as monomer components, there is no particular limitation as long as it is a resin containing styrene and cyclopentadiene as monomer components, and it can also be a resin further containing other monomer components described below. In addition, it can also be a hydrogenated product or a modified product thereof.

[0148] There is no particular limitation on the other monomer components other than styrene and cyclopentadiene. Monomer components commonly used in petroleum resins are preferred, C9 fractions etc. described below are more preferred, and indene is further preferred.

[0149] As the copolymer resin containing styrene and cyclopentadiene as monomer components, a copolymer resin containing styrene, cyclopentadiene and / or dicyclopentadiene, indene as monomer components is preferred, and it can also be a hydrogenated or modified product of this copolymer resin.

[0150] As a copolymer resin containing styrene and cyclopentadiene as monomer components, for example, commercially available substances from ExxonMobil Corporation, ENEOS Corporation, Nippon Zeon Co., Ltd., Maruzen Petrochemical Co., Ltd., etc. can be used. This resin can be used alone or in combination of two or more kinds.

[0151] From the viewpoint of the effects of the present invention, the content of the styrene portion in the copolymer resin containing styrene and cyclopentadiene as monomer components is preferably 0.5% by mass or more, more preferably 0.8% by mass or more, and further preferably 1.0% by mass or more. In addition, the upper limit value of the content of this styrene portion is not particularly limited. For example, it can be set to less than 50% by mass, less than 40% by mass, less than 30% by mass, 10% by mass or less, 5% by mass or less, 3% by mass or less, etc.

[0152] From the viewpoint of the effects of the present invention, the softening point of the copolymer resin containing styrene and cyclopentadiene as monomer components is preferably greater than 70 °C, more preferably greater than 80 °C, further preferably greater than 90 °C, and particularly preferably greater than 100 °C. In addition, from the viewpoints of processability and improving the dispersibility of the rubber component and the filler, it is preferably less than 150 °C, more preferably less than 140 °C, and further preferably less than 130 °C. The softening point of the resin is measured by the above-mentioned measurement method.

[0153] The content of the copolymer resin containing styrene and cyclopentadiene as monomer components relative to 100 parts by mass of the rubber component is preferably greater than 5 parts by mass, more preferably greater than 10 parts by mass, further preferably greater than 15 parts by mass, further preferably greater than 19 parts by mass, and particularly preferably greater than 22 parts by mass. In addition, from the viewpoint of processability, this content is preferably less than 100 parts by mass, more preferably less than 80 parts by mass, further preferably less than 60 parts by mass, and particularly preferably less than 40 parts by mass.

[0154] (Other resins) The rubber composition according to the present embodiment may also contain other resins other than the copolymer resin containing styrene and cyclopentadiene as monomer components. As other resins, there is no particular limitation, and 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 cited. The resins can be used alone or in combination of two or more kinds.

[0155] 《Aromatic vinyl resins》 In this specification, the "aromatic vinyl-based resin" refers to a resin containing at least one aromatic vinyl compound selected from styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene, etc. as a monomer component (wherein, a copolymer resin containing styrene and cyclopentadiene as monomer components is excluded). As the aromatic vinyl-based resin, due to economic efficiency, 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-based resin, for example, commercially available substances from companies such as Kraton Corporation, Eastman Chemical Company, and Mitsui Chemicals, Inc. can be used. This resin can be used alone as one kind, or two or more kinds can be used in combination.

[0156] 《Dicyclopentadiene-based Resin》 In this specification, the "dicyclopentadiene-based resin" refers to a resin containing dicyclopentadiene as a monomer component (wherein, a copolymer resin containing styrene and cyclopentadiene as monomer components is excluded). As the dicyclopentadiene-based resin, for example, commercially available substances from companies such as ExxonMobil Corporation, ENEOS Corporation, Nippon Zeon Co., Ltd., and Maruzen Petrochemical Co., Ltd. can be used. This resin can be used alone as one kind, or two or more kinds can be used in combination.

[0157] 《C9-based Resin》 In this specification, the "C9-based resin" refers to a resin obtained by polymerizing a C9 fraction (wherein, a copolymer resin containing styrene and cyclopentadiene as monomer components is excluded), which can be a resin obtained by homopolymerizing the C9 fraction or a copolymer obtained by copolymerizing the C9 fraction with other components. As the C9 fraction, for example, at least one petroleum fraction having 8 to 10 carbon atoms selected from alkylstyrenes such as vinyltoluene, coumarone, indene, methylindene, etc. can be cited. As specific examples of the C9-based resin, for example, coumarone / indene resin, coumarone resin, indene resin, etc. can be cited. This resin can be used alone as one kind, or two or more kinds can be used in combination.

[0158] 《C5-based Resin》 In this specification, the "C5-based resin" refers to a resin obtained by polymerizing a C5 fraction other than cyclopentadiene, and can also be a hydrogenated product or a modified product thereof. As the C5 fraction other than cyclopentadiene, for example, at least one petroleum fraction having 4 to 5 carbon atoms selected from dicyclopentadiene, isoprene, pentane, isopentane, neopentane, pentene, pentadiene, etc. can be cited. This resin can be used alone as one kind, or two or more kinds can be used in combination.

[0159] 《C5C9-based Resin》 "C5C9 resin" refers to: a resin obtained by copolymerizing the above-mentioned C5 fraction and the above-mentioned C9 fraction, or it can also be their hydrogenated products or modified products. As C5C9 petroleum resins, for example, substances commercially available from Tosoh Corporation, LUHUA Corporation, etc. This resin can be used alone or in combination of two or more kinds.

[0160] 《Terpene Resin》 "Terpene resin" refers to: a resin containing at least one terpene compound selected from α-pinene, β-pinene, limonene, dipentene, etc. as the monomer component with the highest content, preferably a resin containing 50 mol% or more, or it can also be their hydrogenated products or modified products. As specific examples of terpene resins, for example, polyterpene resins containing only one or more of the above-mentioned terpene compounds as monomer components; aromatic modified terpene resins containing the above-mentioned terpene compounds and aromatic compounds as monomer components; terpene phenol resins containing the above-mentioned terpene compounds and phenolic compounds as monomer components, etc. As the monomer component of the aromatic modified terpene resin, that is, the aromatic compound, for example, at least one selected from styrene, α-methylstyrene, vinyltoluene, divinyltoluene, etc. can be cited. As the monomer component of the terpene phenol resin, that is, the phenolic compound, for example, at least one selected from phenol, bisphenol A, cresol, xylenol, etc. can be cited. This resin can be used alone or in combination of two or more kinds.

[0161] 《Rosin Resin》 As rosin resin, it refers to a resin containing at least one rosin acid compound selected from abietic acid, neoabietic acid, palustric acid, isopimaric acid, etc., or it can also be their hydrogenated products or modified products. As rosin resin, there is no particular limitation, for example, natural resin rosin, rosin modified resins obtained by hydrogenating, disproportionating, dimerizing, esterifying, etc. of it can be cited. This resin can be used alone or in combination of two or more kinds.

[0162] 《Phenolic Resin》 As phenolic resin, it refers to a resin containing phenolic compounds such as phenol, cresol, etc. as the monomer component with the highest content, preferably a resin containing 50 mol% or more. As phenolic resin, there is no particular limitation, and phenol formaldehyde resin, alkylphenol formaldehyde resin, alkylphenol acetylene resin, oil-modified phenol formaldehyde resin, etc. can be cited. This resin can be used alone or in combination of two or more kinds.

[0163] 《Softening Point》 From the viewpoint of wet grip performance, the softening point of the resin is preferably greater than 80 °C, more preferably greater than 90 °C, and still more preferably greater than 100 °C. Further, from the viewpoints of processability and improving the dispersibility of the rubber component and the filler, it is preferably less than 150 °C, more preferably less than 140 °C, and still more preferably less than 130 °C. The softening point of the resin is measured by the above-described measuring method.

[0164] 《Content》 The content of the resin relative to 100 parts by mass of the rubber component constituting the first layer or the second layer (total content when two or more are contained) is preferably greater than 10 parts by mass, more preferably greater than 15 parts by mass, and still more preferably 20 parts by mass or more. On the other hand, from the viewpoint of low fuel consumption performance, the content is preferably less than 80 parts by mass, more preferably less than 60 parts by mass, and still more preferably less than 40 parts by mass.

[0165] (Plasticizer other than resin) Plasticizers other than the resin, namely oils, liquid rubbers, and ester-based plasticizers, will be described.

[0166] 《Oil》 Examples of the oil include processing oils, vegetable oils, and animal oils. Examples of the processing oil include paraffin-based processing oils (mineral oils), naphthenic-based processing oils, and aromatic-based processing oils. Specific examples of the processing oil include MES (Mild Extract Solvate), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), and RAE (Residual Aromatic Extract). Further, due to environmental measures, processing oils with a low content of polycyclic aromatic (polycyclic aromatic compound: PCA) compounds can also be used. Examples of the oil with a low PCA content include MES, TDAE, and heavy naphthenic oils. Further, from the viewpoint of life cycle assessment, oils refined from waste oils used in rubber mixers or engines and waste cooking oils used in restaurants can also be used. The oil can be used alone or in combination of two or more.

[0167] Vegetable oils refer to, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice bran oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar, 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, as vegetable oils, 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, heat-polymerized oils obtained by heat-polymerizing the above oils, oxidation-polymerized oils obtained by oxidizing the above oils, waste cooking oils obtained by recycling the oils used as edible oils, etc. can also be cited. In addition, vegetable oils can be liquid or solid at normal temperature (25°C).

[0168] Vegetable oils preferably contain acylglycerols, and more preferably contain triacylglycerols. In addition, in this specification, acylglycerols refer to compounds in which the hydroxyl groups of glycerol form ester bonds with fatty acids. As acylglycerols, there is no particular limitation, and any one of 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, and triacylglycerol can be used. Further, acylglycerols can be monomers, dimers, or polymers of trimers or higher. In addition, acylglycerols of dimers or higher can be obtained by heat polymerization, oxidation polymerization, etc. In addition, acylglycerols can be liquid or solid at normal temperature (25°C).

[0169] As a method for confirming whether an acylglycerol is contained in the rubber composition, there is no particular limitation, and it can be confirmed by 1 1H-NMR measurement. For example, the rubber composition compounded with triacylglycerol is immersed in deuterated chloroform at normal temperature (25°C) for 24 hours, and after removing the rubber composition, 1H-NMR is measured at room temperature. 1 When the signal of tetramethylsilane (TMS) is set to 0.00 ppm in 1H-NMR, signals around 5.26 ppm, around 4.28 ppm, and around 4.15 ppm can be observed, and it is speculated that these signals are signals from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In addition, "around" in this paragraph refers to a range of ±0.10 ppm.

[0170] As the above fatty acids, there is no particular limitation, and they can be unsaturated fatty acids or saturated fatty acids. As unsaturated fatty acids, monounsaturated fatty acids such as oleic acid or polyunsaturated fatty acids such as linoleic acid and linolenic acid can be cited. In addition, as saturated fatty acids, butyric acid, lauric acid, etc. can be cited.

[0171] Among them, as the above fatty acid, it is preferably a fatty acid with fewer double bonds, that is, a saturated fatty acid or a monounsaturated fatty acid, preferably oleic acid. As such a vegetable oil containing fatty acids, for example, a vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid can be used, or a modified vegetable oil such as a transesterified vegetable oil can also be used. In addition, in order to produce such a vegetable oil containing fatty acids, plants can also be improved through variety improvement, genetic modification, etc.

[0172] As the vegetable oil, for example, commercially available substances from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0173] Examples of animal oils include fish oil, beef tallow, whale oil, or oil alcohols derived therefrom.

[0174] When oil is contained, from the viewpoint of processability, its content relative to 100 parts by mass of the rubber component is preferably 8 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 20 parts by mass or more. In addition, from the viewpoint of abrasion resistance, it is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, and further preferably 40 parts by mass or less. The content of the oil also includes the amount of oil contained in the oil-extended rubber.

[0175] "Liquid Rubber" The liquid rubber is not particularly limited as long as it is a polymer in a liquid state at normal temperature (25 °C). For example, 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. can be cited. The liquid rubber can be used alone or in combination of two or more.

[0176] When liquid rubber is contained, its content relative to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more. In addition, the content of the liquid rubber is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and further preferably 10 parts by mass or less. The content of the liquid rubber also includes the amount of the extender liquid rubber used in the increment of the rubber component.

[0177] "Ester Plasticizer" As ester plasticizers, for example, dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di-2-ethylhexyl azelate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), dilauryl 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), etc. can be cited. The ester plasticizers can be used alone or in combination of two or more.

[0178] When containing an ester plasticizer, its content relative to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more. In addition, the content of the liquid rubber is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and further preferably 10 parts by mass or less. The content of the ester plasticizer also includes the amount of the incremental ester plasticizer used in the increment of the rubber component.

[0179] The content of the plasticizer (total content when containing two or more) relative to 100 parts by mass of the rubber component constituting the first layer or the second layer is preferably more than 20 parts by mass, more preferably more than 30 parts by mass, and further preferably more than 34 parts by mass. On the other hand, from the viewpoint of low fuel consumption performance, this content is preferably less than 120 parts by mass, more preferably less than 100 parts by mass, and further preferably less than 80 parts by mass.

[0180] (Vulcanized rubber particles) Vulcanized rubber particles are particles made of vulcanized rubber. Specifically, rubber powder specified in JIS K 6316:2017, etc. can be used. From the viewpoints of environmental concerns and cost, recycled rubber powder made from crushed waste tires, etc. is preferred. The vulcanized rubber particles can be used alone or in combination of two or more.

[0181] As the vulcanized rubber particles, there is no particular limitation, and they can be non-modified vulcanized rubber particles or modified vulcanized rubber particles. As commercially available products of vulcanized rubber, for example, products of Lehigh Company, Murakami Rubber Industry Co., Ltd., etc. can be used.

[0182] When containing vulcanized rubber particles, its content relative to 100 parts by mass of the rubber component can be appropriately adjusted, for example, in the range of more than 1 part by mass and less than 80 parts by mass.

[0183] (Stearic acid) When stearic acid is contained, from the viewpoint of processability, its content relative to 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1 part by mass or more. Further, from the viewpoint of vulcanization rate, it is preferably 10 parts by mass or less, more preferably 5 parts by mass or less.

[0184] (Zinc oxide) When zinc oxide is contained, from the viewpoint of processability, its content relative to 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1.0 part by mass or more, and still more preferably 1.5 parts by mass or more. Further, from the viewpoint of abrasion resistance, it is preferably 5.0 parts by mass or less, more preferably 4.5 parts by mass or less, and still more preferably 4.0 parts by mass or less.

[0185] (Wax) The wax is not particularly limited, and any one of the substances commonly used in the tire industry can be preferably used. For example, petroleum wax, mineral wax, synthetic wax, plant-derived wax, etc. can be cited. Among them, petroleum wax and plant-derived wax are preferred, and petroleum wax is more preferred. As the plant-derived wax, for example, rice bran wax, carnauba wax, candelilla wax, etc. can be cited. As the petroleum wax, for example, paraffin wax, microcrystalline wax, selected special waxes thereof, etc. can be cited, and paraffin wax is preferred. In addition, the wax involved in this embodiment does not include stearic acid. The wax can be, for example, a commercially available substance from Ouchi Shinsei Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., etc. The wax can be used alone or in combination of two or more.

[0186] When wax is contained, from the viewpoint of the weather resistance of the rubber, its content relative to 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1 part by mass or more. Further, from the viewpoint of preventing tire whitening caused by blooming, it is preferably 10 parts by mass or less, more preferably 5 parts by mass or less.

[0187] (Antioxidant) As the anti-aging agent, there is no particular limitation, and examples thereof include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine, 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine-based anti-aging agents such as N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-dimethylxylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based anti-aging agents such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based anti-aging agents such as 2,6-di-tert-butyl-4-methylphenol, styrenated phenol; bis-, tris-, polyphenol-based anti-aging agents such as tetrakis[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane, etc. Among them, p-phenylenediamine-based anti-aging agents and quinoline-based anti-aging agents are preferred, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and polymers of 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. As commercially available products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industrial Co., Ltd., Flexis Co., etc. can be used. The anti-aging agent can be used alone or in combination of two or more kinds.

[0188] When containing the anti-aging agent, from the viewpoint of ozone crack resistance of the rubber, its content relative to 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1 part by mass or more. In addition, from the viewpoints of abrasion resistance and wet grip performance, it is preferably 10 parts by mass or less, more preferably 5 parts by mass or less.

[0189] (Processing aid) As the processing aid, for example, fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, fatty acid esters, mixtures of fatty acid metal salts and amide esters, mixtures of fatty acid metal salts and fatty acid amides, etc. can be cited. As the processing aid, for example, substances commercially available from companies such as Schill+Seilacher and Performance-Additives can be used. The processing aid can be used alone or in combination of two or more kinds.

[0190] When containing the processing aid, from the viewpoint of exerting the improvement effect of processability, its content relative to 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1 part by mass or more. In addition, from the viewpoints of abrasion resistance and breaking strength, it is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and further preferably 5 parts by mass or less.

[0191] (Vulcanizing agent) As the vulcanizing agent, sulfur is preferably used. As sulfur, powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, etc. can be used. The vulcanizing agent can be used alone as one kind, or two or more kinds can be used in combination.

[0192] When sulfur is contained as the vulcanizing agent, from the viewpoint of ensuring sufficient vulcanization reaction, its content relative to 100 parts by mass of the rubber component is preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, and further preferably 0.5 part by mass or more. In addition, from the viewpoint of preventing deterioration, it is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and further preferably 3.0 parts by mass or less. In addition, when using sulfur containing oil as the vulcanizing agent, the content of the vulcanizing agent is set as the total content of pure sulfur contained in the sulfur containing oil.

[0193] As vulcanizing agents other than sulfur, for example, alkylphenol / sulfur chloride condensates, sodium 1,6-hexamethylenedithiocarbamate dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, etc. can be cited. These vulcanizing agents other than sulfur can use commercially available substances from companies such as Taoka Chemical Industry Co., Ltd., Lanxess AG, and Flexis. The vulcanizing agent can be used alone as one kind, or two or more kinds can be used in combination.

[0194] (Vulcanization accelerator) As the vulcanization accelerator, for example, sulfenamide-based, thiazole-based, thiuram-based, thiourea-based, guanidine-based, dithiocarbamate-based, aldehyde-amine-based or aldehyde-ammonia-based, imidazoline-based, or xanthate-based vulcanization accelerators, etc. can be cited. Among them, sulfenamide-based, thiazole-based, and guanidine-based vulcanization accelerators are preferred. The vulcanization accelerator can be used alone as one kind, or two or more kinds can be used in combination.

[0195] As sulfenamide-based vulcanization accelerators, for example, N-tert-butyl-2-benzothiazolesulfenamide (TBBS), N-cyclohexyl-2-benzothiazolesulfenamide (CBS), N,N-dicyclohexyl-2-benzothiazolesulfenamide (DCBS), etc. can be cited. Among them, N-cyclohexyl-2-benzothiazolesulfenamide (CBS) is preferred.

[0196] As thiazole-based vulcanization accelerators, for example, 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, di-2-benzothiazole disulfide, etc. can be cited. Among them, 2-mercaptobenzothiazole is preferred.

[0197] As a guanidine-based vulcanization accelerator, for example, 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of dicatecholborate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenyl guanidine, 1,3-di-o-cumenyl-2-propionylguanidine, etc. may be mentioned. Among them, 1,3-diphenylguanidine (DPG) is preferred.

[0198] When a vulcanization accelerator is contained, its content relative to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more. In addition, the content of the vulcanization accelerator relative to 100 parts by mass of the rubber component is preferably 8 parts by mass or less, more preferably 7 parts by mass or less, and further preferably 6 parts by mass or less. By setting the content of the vulcanization accelerator within the above range, it tends to ensure the breaking strength and elongation at break.

[0199] <Various materials containing carbon atoms> In this specification, various materials containing carbon atoms (for example, rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may also be derived from carbon dioxide in the atmosphere. As a method for obtaining the blend according to the embodiment of the present invention from carbon dioxide, carbon dioxide can be directly converted, or methane obtained through a methanation process of synthesizing methane from carbon dioxide can be converted.

[0200] The rubber composition constituting the third layer of the tread surface can be produced by a conventional method using the above-mentioned raw materials in the same manner as the rubber composition constituting the first layer or the second layer. However, as the rubber component, it is preferably an isoprene rubber, more preferably an isoprene rubber and BR.

[0201] The content of the isoprene rubber in the rubber component constituting the third layer of the tread surface is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 80% by mass or more. In addition, the content of BR in the rubber component constituting the third layer is preferably 10% by mass or more.

[0202] The BR contained in the rubber component constituting the third layer of the tread surface is preferably a low-cis BR having a cis content of less than 50 mol%, more preferably a low-cis modified BR.

[0203] In the rubber composition constituting the third layer of the tread surface, the N2SA of the carbon black is preferably 80 m 2 / g or less, more preferably 70 m 2 / g or less. In addition, this N2SA is preferably 30 m2 above / g, more preferably 50 m 2 above / g, further preferably 60 m 2 above / g.

[0204] When the rubber composition constituting the third layer contains carbon black, from the viewpoint of the effects of the present invention, its content relative to 100 parts by mass of the rubber component is preferably more than 20 parts by mass, more preferably more than 25 parts by mass, and further preferably more than 30 parts by mass. In addition, from the viewpoint of low fuel consumption performance, it is preferably less than 100 parts by mass, more preferably less than 80 parts by mass, and further preferably less than 60 parts by mass.

[0205] As a plasticizer, the rubber composition constituting the third layer of the tread portion may contain a resin or may not contain a resin, but preferably contains an oil.

[0206] There is no particular limitation on the content of the resin (total content when two or more kinds are contained) relative to 100 parts by mass of the rubber component constituting the third layer. For example, the lower limit value can be set to 1 part by mass or more, 3 parts by mass or more, 5 parts by mass or more, etc., and the upper limit value can be set to 15 parts by mass or less, 10 parts by mass or less, 8 parts by mass or less, etc.

[0207] [Manufacturing method] The rubber composition can be manufactured by a known method. For example, it can be manufactured by kneading the above-mentioned respective components using a rubber kneading device such as an open roll mill, a closed kneader (Banbury mixer, kneader, etc.).

[0208] The kneading process includes, for example, the following basic kneading process: kneading compounding agents and additives other than the vulcanizing agent and the vulcanization accelerator, and a final kneading process (F kneading): adding the vulcanizing agent and the vulcanization accelerator to the kneaded product obtained in the basic kneading process and kneading. Further, the above basic kneading process can also be decomposed into multiple processes as needed.

[0209] As the kneading conditions, there is no particular limitation. For example, in the basic kneading process, kneading is carried out at a discharge temperature of 150 to 170 °C for 3 to 10 minutes, and in the final kneading process, kneading is carried out at 70 to 110 °C for 1 to 5 minutes.

[0210] The tire according to this embodiment can be manufactured by a conventional method using the above rubber composition. That is, the tire can be manufactured by extruding the above rubber composition in an unvulcanized state through an extruder equipped with a die having a specified shape in accordance with the shape of the first, second, or third layer of the tread surface, adjusting it to a specified tire structure on a tire molding machine while being adhered together with other tire components, and forming an unvulcanized tire by molding through a conventional method, and then manufacturing the unvulcanized tire by heating and pressurizing it in a vulcanizer. As the vulcanization conditions, there are no particular limitations. For example, a method of vulcanizing at 140 to 170 °C for 10 to 40 minutes can be cited.

[0211] [Use] In this specification, the tire, whether it is a pneumatic tire or a non-pneumatic tire, can be used for any purpose and can be used as a passenger car tire, a large passenger car tire, a large SUV tire, a racing tire, a motorcycle tire, a load-carrying tire, a run-flat tire. In addition, a passenger car tire means a tire with a maximum load capacity of less than 1400 kg on the premise of being installed on a four-wheel-driving vehicle. In addition, a load-carrying tire means a tire with a maximum load capacity of 1400 kg or more. In addition, in this specification, the tire can be used for winter tires such as studless tires in addition to all-season tires and summer tires.

Examples

[0212] The following shows examples (examples) considered to be preferred during implementation, but the scope of the present invention is not limited to the examples.

[0213] Using various drugs shown below, tires having a tread surface made of a rubber composition obtained by changing the formulation according to Table 1 were studied, and the results calculated based on the following evaluation methods are shown in Tables 2 and 3. NR: TSR20 SBR1: SBR (S-SBR, Tg: -66 °C, styrene content: 19% by mass, vinyl content: 19 mol%, non-oil-extended) manufactured according to the following Production Example 1 SBR2: SBR (S-SBR, Tg: -50 °C, styrene content: 30% by mass, vinyl content: 22 mol%, non-oil-extended) manufactured according to the following Production Example 2 SBR3: HPR830E manufactured by JSR Corporation (S-SBR, Tg: -23 °C, styrene content: 39.5% by mass, vinyl content: 38.5 mol%, containing 10.0 parts by mass of oil extender relative to 100 parts by mass of rubber solid content) BR1: UBEPOL BR (registered trademark) 150B manufactured by UBE Industries, Ltd. (cis content: 98 mol%, vinyl content: 1 mol%) BR2: BR1250H manufactured by Zeon Corporation, Japan (tin-modified BR, polymerized using lithium as an initiator, vinyl content: 10 - 13 mol%, cis content: 39.7 mol%) CB1: DIABLACK I manufactured by Mitsubishi Chemical Corporation (N220, N2SA: 114m 2 / g, average primary particle size: 22nm) CB2: SHOBLACK N351H manufactured by Cabot Japan Limited (N2SA: 69m 2 / g, average primary particle size: 29nm) Silica: ULTRASIL VN3 manufactured by Evonik Degussa GmbH (N2SA: 175m 2 / g, average primary particle size: 18nm) Silane coupling agent: Si266 manufactured by Evonik Degussa GmbH (bis(3-triethoxysilylpropyl) disulfide) Oil: VivaTec500 manufactured by H&R Co., Ltd. (TDAE oil) Wax: OZOACE 0355 of Nippon Seiro Co., Ltd. Copolymer resin: Opera PR383 manufactured by ExxonMobil Corporation (hydrogenated DCPD-C9 resin, containing styrene and cyclopentadiene as monomer components, Mw: 770, softening point: 103°C, content of styrene part: 1.78 mass%) Terpene resin: YS Resin PX1150N manufactured by Yasuhara Chemical Co., Ltd. (polyterpene resin, softening point: 115 ± 5°C) Stearic acid: Stearic acid beads "TSUBAKI" manufactured by NOF Corporation Zinc oxide: Zinc oxide No. 1 of Mitsui Mining & Smelting Co., Ltd. Antioxidant 1: NOCRAC 6 manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) Antioxidant 2: NOCRAC RD manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) Sulfur 1: M95 manufactured by Nippon Karyukai Industry Co., Ltd. (insoluble sulfur) Sulfur 2: HK-200-5 manufactured by Hosoi Chemical Industry Co., Ltd. (powder sulfur containing 5% oil) Vulcanization accelerator 1: NOCCELLER CZ-G manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. (N-cyclohexyl-2-benzothiazole sulfenamide) Vulcanization accelerator 2: NOCCELLER D (1,3-diphenylguanidine (DPG)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 3: NOCCELLER NS-G (N-tert-butyl-2-benzothiazolesulfenamide (TBBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0214] (Production Example 1: Production of SBR1) Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were added to an autoclave reactor purged with nitrogen. The ratio of styrene and 1,3-butadiene was adjusted so that the content of the styrene portion was 19% by mass. After adjusting the temperature of the contents of the reactor, tert-butyllithium was added to start polymerization. Polymerization was carried out under adiabatic conditions, and the polymerization solution was poured into ethanol to recover the precipitate. The precipitate was air-dried and then dried under reduced pressure until the loss on drying reached 0.1% to obtain SBR1.

[0215] (Production Example 2: Production of SBR2) Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were added to an autoclave reactor purged with nitrogen. The ratio of styrene and 1,3-butadiene was adjusted so that the content of the styrene portion was 30% by mass. After adjusting the temperature of the contents of the reactor, tert-butyllithium was added to start polymerization. Polymerization was carried out under adiabatic conditions, and the polymerization solution was poured into ethanol to recover the precipitate. The precipitate was air-dried and then dried under reduced pressure until the loss on drying reached 0.1% to obtain SBR2.

[0216] (Examples and Comparative Examples) According to the compounding recipe shown in Table 1, using a 1.7 L closed Banbury mixer, the reagents other than sulfur and vulcanization accelerators were kneaded for 1 to 10 minutes until the discharge temperature reached 150 to 160 °C to obtain a kneaded product. Then, using a twin-screw open mill, sulfur and vulcanization accelerators were added to the kneaded product and kneaded for 4 minutes until it reached 105 °C to obtain an unvulcanized rubber composition. By shaping the obtained unvulcanized rubber composition into the shape of the first layer, second layer (thickness: 4.0 mm), and third layer (thickness: 1.0 mm) of the tread and bonding it together with other tire components, an unvulcanized tire was produced. By press-vulcanizing at 150 °C for 35 minutes, each test tire (195 / 65R15) described in Tables 2 and 3 was obtained.

[0217] (Measurement of tanδ at 30 °C and E* at 30 °C) From the tread surface of each test tire, a rubber test piece with a length of 20 mm × width of 4 mm × thickness of 1 mm was cut out with the tire circumferential direction as the long side and the tire radial direction as the thickness direction. For each rubber test piece, using the EPLEXOR series manufactured by GABO, tanδ and complex elastic modulus (E*) were measured under the conditions of a temperature of 30 °C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain of ±1.0%.

[0218] <Measurement of modulus at 200% elongation> For the No. 7 dumbbell-shaped test pieces cut out from the inner part of the second layer of the tread surface of each test tire with a thickness of 1 mm in the tire circumferential direction as the stretching direction and the tire radial direction as the thickness direction, a tensile test was carried out according to JIS K 6251:2017 under the conditions of an atmosphere of 23 °C and a stretching speed of 3.3 mm / second, and the modulus (MPa) at 200% elongation was measured.

[0219] <Chunking resistance performance> Each test tire was respectively assembled on a regular rim, and after being inflated to the regular internal pressure, it was installed on a vehicle and driven on an uneven ground at a speed of 50 km / h for 4 hours. After driving, for all cracks generated on the tire surface, the circumferential length was measured, and the maximum value of the circumferential length was obtained for each tire. The results were expressed as an index with Comparative Example 1 set to 100 according to the following formula. The larger the index, the smaller the crack and the better the chunking resistance performance. (Chunking resistance performance index) = (Circumferential length of cracks of the tire in Comparative Example 1) / (Circumferential length of cracks of each test tire) × 100

[0220] <Wet grip performance> All tires of each test tire were installed on a vehicle (domestic FF 2000 cc), and the braking distance starting from an initial speed of 100 km / h on an uneven ground was obtained. The measurement results were expressed as an index according to the following calculation formula. The larger the index, the shorter the braking distance and the more excellent the wet grip performance. In the wet grip performance index, Comparative Example 1 was set as the reference comparative example. (Wet grip performance index) = (Braking distance of Comparative Example 1) / (Braking distance of each test tire) × 100

[0221] <Comprehensive performance> The sum of the chunking resistance performance index and the wet grip performance index was expressed as the comprehensive performance index.

[0222]

Table 1

[0223]

Table 2

[0224]

Table 3

[0225] <Embodiment> Examples of the embodiments of the present invention are shown below. 〔1〕A tire, characterized in that it is a tire having a tread surface, the tread surface includes at least a first layer forming the tread surface, a second layer adjacent to the first layer on the inner side in the tire radial direction, and a third layer existing on the inner side in the tire radial direction of the second layer, the first layer and the second layer are made of a rubber composition containing a rubber component including styrene-butadiene rubber and / or isoprene-based rubber and silica, at least any one of the rubber compositions forming the first layer and the second layer contains a copolymer resin including styrene and cyclopentadiene as monomer components, in the rubber composition forming the first layer, when the mass of the rubber component is set to 100% by mass, the total styrene amount in the rubber composition is set to S1 (% by mass), in the rubber composition forming the second layer, when the mass of the rubber component is set to 100% by mass, the total styrene amount in the rubber composition is set to S2 (% by mass), S2 - S1 is greater than 0. 〔2〕The tire according to the above 〔1〕, wherein when the thickness of the first layer is set to t1 (mm), S1 × t1 is less than 100.0, preferably less than 95.0, more preferably less than 90.0. 〔3〕The tire according to the above 〔1〕 or 〔2〕, wherein S2 - S1 is greater than 10.0, preferably greater than 11.0, more preferably greater than 12.5. 〔4〕The tire according to any one of the above 〔1〕 to 〔3〕, wherein the rubber composition forming the second layer contains a copolymer resin including styrene and cyclopentadiene as monomer components. 〔5〕The tire according to any one of the above 〔1〕 to 〔4〕, wherein the tanδ (30 °C tanδ1) of the rubber composition forming the first layer at 30 °C is 0.30 or less. 〔6〕The tire according to any one of the above 〔1〕 to 〔5〕, wherein the complex elastic modulus (30 °C E*2) of the rubber composition forming the second layer at 30 °C is 3.5 MPa or less. 〔7〕The tire according to any one of the above-mentioned 〔1〕 to 〔6〕, wherein, based on 100 parts by mass of the rubber component, the rubber composition constituting the first layer contains 70 parts by mass or more of silica. 〔8〕The tire according to any one of the above-mentioned 〔1〕 to 〔7〕, wherein S1 is greater than 0 and less than 20.0, preferably 5.0 or more and less than 20.0, more preferably 8.0 or more and less than 20.0, and further preferably 11.0 or more and less than 20.0. 〔9〕The tire according to any one of the above-mentioned 〔1〕 to 〔8〕, wherein, based on 100 parts by mass of the rubber component, the rubber composition constituting the second layer contains 70 parts by mass or more of silica. 〔10〕The tire according to any one of the above-mentioned 〔1〕 to 〔9〕, wherein the modulus M2 at 200% elongation of the rubber composition constituting the second layer is 7.0 MPa or less, preferably 6.8 MPa or less. 〔11〕The tire according to any one of the above-mentioned 〔1〕 to 〔10〕, wherein the ratio (30 °C tanδ2 / 30 °C tanδ3) of tanδ (30 °C tanδ2) of the rubber composition constituting the second layer at 30 °C to tanδ (30 °C tanδ3) of the rubber composition constituting the third layer at 30 °C is greater than 1.0, preferably greater than 1.5, and more preferably greater than 1.8. 〔12〕The tire according to any one of the above-mentioned 〔1〕 to 〔11〕, wherein the tread portion has a plurality of circumferential grooves continuously extending in the tire circumferential direction, and at least one of the plurality of circumferential grooves is provided with a recessed portion that is recessed outward in the groove width direction compared with the groove edge of the tread surface appearing on the tread portion.

Claims

1. A tire, characterized in that: It is a tire having a tread portion. The tread portion includes at least a first layer constituting a tread surface, a second layer adjacent to the first layer inwardly in the tire radial direction, and a third layer present inwardly in the tire radial direction of the second layer. The first layer and the second layer are composed of a rubber composition containing a rubber component including styrene-butadiene rubber and / or isoprene-based rubber and silica. At least one of the rubber compositions constituting the first layer and the second layer contains a copolymer resin containing styrene and cyclopentadiene as monomer components, In the rubber composition constituting the first layer, the total amount of styrene in the rubber composition when the mass of the rubber component is 100 mass % is referred to as S1, In the rubber composition constituting the second layer, when the mass of the rubber component is 100 mass %, the total amount of styrene in the rubber composition is denoted as S2. S2-S1 is greater than 0, The unit of S1 and S2 is mass %.

2. The tire according to claim 1, wherein: When the thickness of the first layer is set to t1, S1×t1 is less than 100.0, and the unit of t1 is mm.

3. The tire according to claim 1 or 2, wherein: S2-S1 is greater than 10.

0.

4. The tire according to claim 1 or 2, wherein: The rubber composition constituting the second layer contains a copolymer resin including styrene and cyclopentadiene as monomer components.

5. The tire according to claim 1 or 2, wherein: The rubber composition constituting the first layer has a tan δ at 30° C., that is, tan δ1 at 30° C. of 0.30 or less.

6. The tire according to claim 1 or 2, wherein: The rubber composition constituting the second layer has a complex elastic modulus 30°C E*2 at 30°C of 3.5 MPa or less.

7. The tire according to claim 1 or 2, wherein: The rubber composition constituting the first layer contains 70 parts by mass or more of silica based on 100 parts by mass of the rubber component.

8. The tire according to claim 1 or 2, wherein: S1 is greater than 0 and less than 20.

0.

9. The tire according to claim 1 or 2, wherein: The rubber composition constituting the second layer contains 70 parts by mass or more of silica based on 100 parts by mass of the rubber component.

10. The tire according to claim 1 or 2, wherein: The modulus M2 of the rubber composition constituting the second layer at 200% elongation is 7.0 MPa or less.

11. The tire according to claim 1 or 2, wherein: The ratio (30°C tanδ2 / 30°C tanδ3) of tanδ at 30°C of the rubber composition constituting the second layer to tanδ at 30°C of the rubber composition constituting the third layer is greater than 1.

0.

12. The tire according to claim 1 or 2, wherein: The tread portion has a plurality of circumferential grooves extending continuously in the tire circumferential direction, and a groove wall of at least one of the plurality of circumferential grooves is provided with a recessed portion recessed outward in the groove width direction relative to a groove edge appearing on a tread surface of the tread portion.

13. The tire according to claim 1 or 2, wherein: S2-S1 is less than 25.0.

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