TIRES

Abstract

A tire is provided which comprises a tread portion, the tread portion comprising at least a first layer forming a tread surface, a second layer adjacent to an inner side in a tire radial direction of the first layer, and a third layer provided on the inner side in the tire radial direction of the second layer, wherein the first layer and the second layer are each composed of a rubber composition comprising a rubber component comprising a styrene-butadiene rubber and / or an isoprene-based rubber and silica, wherein at least one of the rubber composition forming the first layer and the rubber composition forming the second layer comprises a copolymer resin comprising styrene and cyclopentadiene as monomer components, and wherein, when S1 in mass% is a total amount of styrene of the rubber composition,which forms the first layer, wherein a mass of the rubber component is 100 mass%, and when S2 in mass% represents a total styrene amount of the rubber composition forming the second layer, wherein a mass of the rubber component is 100 mass%, S1 - S2 is greater than 0.,

Description

TECHNICAL FIELD

[0001] The present invention relates to a tire. STATE OF THE ART

[0002] JP 2023-88085 A describes that uneven wear resistance is improved by a tire having a plurality of intersecting belt layers and one or more circumferential belt layers, wherein an intersecting belt cord forms an angle of 20° to 45° with respect to a tire width direction, wherein a plurality of main grooves and sub-grooves are provided on a tread surface, and wherein an outer groove wall surface at the sub-groove is located at a position in the tire width direction of one or more circumferential belt layers or is located on an inner side in the tire width direction with respect to the outermost end in the tire width direction of the circumferential belt layer. SUMMARY OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION

[0003] However, JP 2023-88085 A does not consider tire performance other than uneven wear resistance.

[0004] An object of the present invention is to provide a tire having improved overall performance of abrasion resistance, wet grip performance and fuel efficiency. MEANS TO SOLVE THE PROBLEM

[0005] The present invention relates to: a tire comprising a tread portion, wherein the tread portion comprises at least a first layer forming a tread surface, a second layer adjacent to an inner side in a tire radial direction of the first layer, and a third layer present on the inner side in the tire radial direction of the second layer, wherein the first layer and the second layer are each composed of a rubber composition comprising a rubber component comprising a styrene-butadiene rubber and / or an isoprene-based rubber, and silicon dioxide, wherein at least one of the rubber composition forming the first layer and the rubber composition forming the second layer comprises a copolymer resin comprising styrene and cyclopentadiene as monomer components, and where, where S1 represents in mass% a total amount of styrene of the rubber composition constituting the first layer, wherein a mass of the rubber component is 100 mass%, and where S2 represents in mass% a total amount of styrene of the rubber composition constituting the second layer, wherein a mass of the rubber component is 100 mass%, S1 - S2 is greater than 0. EFFECT OF THE INVENTION

[0006] There is provided according to the present invention a tire having improved overall performance of uneven wear resistance, wet grip performance and fuel efficiency. SHORT DESCRIPTION OF THE CHARACTERS Fig. 1 is a cross-sectional view schematically showing a part of a tread of a tire. Fig. 2 is an enlarged plan view of a circumferential groove according to an embodiment of the present invention. Fig. 3 is a cross-sectional view along the line AA in Fig. 2. EMBODIMENTS FOR CARRYING OUT THE INVENTION

[0007] The tire which is an embodiment of the present invention is a tire comprising a tread portion, wherein the tread portion comprises at least a first layer forming a tread surface, a second layer adjacent to an inner side in a tire radial direction of the first layer, and a third layer provided on the inner side in the tire radial direction of the second layer, wherein the first layer and the second layer are each composed of a rubber composition comprising a rubber component comprising a styrene-butadiene rubber and / or an isoprene-based rubber and silica, wherein at least one of the rubber composition forming the first layer and the rubber composition forming the second layer comprises a copolymer resin comprising styrene and cyclopentadiene as monomer components, and wherein,when S1 in mass% represents a total styrene amount of the rubber composition constituting the first layer, wherein a mass of the rubber component is 100 mass%, and when S2 in mass% represents a total styrene amount of the rubber composition constituting the second layer, wherein a mass of the rubber component is 100 mass%, S1 - S2 is greater than 0.,

[0008] For example, while not intended to be bound by any theory, the following may be assumed as a mechanism for improving overall performance of uneven wear resistance, wet grip performance, and fuel efficiency in the tire of the present invention.

[0009] First, (1) by configuring the tread portion with three or more layers of rubber composition, multiple rubber layer interfaces are formed in the tread portion. This can reduce energy loss due to friction caused by fine molecular movement of each rubber phase constituting the interface when shear deformation occurs in the tread portion, and is therefore expected to contribute to improving wet grip performance and fuel efficiency.Then, (2) silica is considered to contribute to improving fuel efficiency, but it is chemically bonded to a styrene-butadiene rubber or an isoprene-based rubber via a silane coupling agent to reinforce the rubber composition, so that the first layer and the second layer each comprise a rubber component comprising a styrene-butadiene rubber and / or an isoprene-based rubber and silica to reinforce the tread portion, and therefore, it is considered to contribute to improving uneven wear resistance.Furthermore, (3) since a copolymer resin comprising styrene and cyclopentadiene as monomer components is bulky, flexibility can be imparted to the rubber composition without impairing a reinforcing effect if at least one of the rubber composition constituting the first layer and the rubber composition constituting the second layer comprises the copolymer resin, and therefore, it is considered to contribute to improving wet grip performance.

[0010] As described above, when the rubber composition has reinforcing property and flexibility, the entire tread portion becomes hard and flexible, so that uneven wear of the tread portion can be suppressed.

[0011] Moreover, even if uneven wear occurs, if (4) S1 - S2 is greater than 0, as wear progresses, the first layer having a large amount of styrene becomes thinner, and a proportion of the second layer having a smaller amount of styrene than the first layer and less likely to generate heat in the entire tread portion increases, therefore, it is considered to slow down the progress of wear in the portion where uneven wear has occurred.

[0012] Furthermore, (5) when the first layer comprises a large amount of styrene groups, 0 °C-tanδ of the first layer can be increased due to heat generation by the styrene groups, and therefore, it is considered to contribute to the improvement of wet grip performance.

[0013] With the cooperation of (1) to (5) described above, it is expected that a remarkable effect of improving the overall performance of abrasion resistance, wet grip performance and fuel efficiency is achieved.

[0014] When t1 in mm represents a thickness of the first layer, S1 × t1 is preferably less than 100.0, more preferably less than 50.0, and even more preferably less than 25.0.

[0015] When S1 is large, 30 °C-tanδ can be reduced by reducing the thickness of the first layer while keeping 0 °C-tanδ high, so that both fuel efficiency and wet grip performance can be achieved.

[0016] S2 is preferably greater than 0 and less than 20.

[0017] By setting S2 within the range described above, it is assumed that fine styrene domains are formed in the second layer and external deformation can be easily absorbed by interfaces between the styrene domains and the surrounding rubber molecular chains.

[0018] The rubber composition forming the first layer preferably comprises a copolymer resin comprising styrene and cyclopentadiene as monomer components.

[0019] When the first layer includes the resin, the rubber composition itself becomes hard and flexible at the tread surface, thus, it is expected to further improve uneven wear resistance. Furthermore, heat generation at the tread surface increases, so it is expected to further improve wet grip performance.

[0020] A ratio (70 °C-tanδ1 / R) of a loss tangent at 70 °C of the rubber composition constituting the first layer (tanδ1) to a rise ratio R is preferably less than 0.29.

[0021] By setting 70 °C-tanδ1 / R within the range described above and increasing the elevation ratio R as 70 °C-tanδ of the first layer increases, deformation of the first layer is reduced, so it is assumed that heat generation is suppressed. As a result, softening of the first layer is reduced, so it is assumed that uneven abrasion resistance is improved.

[0022] A ratio (70 °C-tanδ2 / R) of a loss tangent at 70 °C of the rubber composition constituting the second layer (tanδ2) to the elevation ratio R is preferably greater than 0.20.

[0023] By setting 70 °C-tanδ2 / R within the above-described range and increasing 70 °C-tanδ of the second layer relative to the elevation ratio R, energy absorption efficiency in the second layer is increased, so that uneven abrasion resistance is expected to be improved.

[0024] A modulus M2 at 200% elongation of the rubber composition constituting the second layer is preferably 9.5 MPa or less.

[0025] By setting the modulus at elongation of 200% of the rubber composition constituting the second layer within the range described above, it is assumed that when deformation occurs from a road surface that could not be completely absorbed by the first layer, the second layer deforms flexibly and can easily absorb the deformation.

[0026] The rubber composition constituting the second layer preferably comprises 80 parts by mass or more of silica based on 100 parts by mass of the rubber component.

[0027] A reinforcing property with silica can be obtained, so that uneven abrasion resistance is expected to be further improved.

[0028] A ratio (70 °C-tanδ2 / 70 °C-tanδ3) of 70 °C-tanδ2 to a loss tangent at 70 °C of the rubber composition constituting the third layer (70 °C-tanδ3) is preferably greater than 1.0.

[0029] It is believed that by increasing heat generation of the second layer relative to heat generation of the rubber composition constituting the third layer, the second layer can easily absorb the deformation even when deformation occurs which cannot be completely absorbed by the first layer.

[0030] It is preferable that the tread portion has a plurality of circumferential grooves continuously extending in a tire circumferential direction, and that at least one groove wall of the circumferential groove is provided with a depressed portion depressed outward in a groove width direction with respect to a groove edge appearing on a tread surface of the tread portion.

[0031] When the groove wall of the circumferential groove is provided with such a depressed portion, a gap is formed inside the tread, so that it is believed that the gap can absorb impact and suppress propagation of the impact. [Definitions]

[0032] A "tread portion" is a member including a portion constituting a ground contact surface of a tire, and in a case where the tire includes a member constituting a tire skeleton made of steel or a textile material, such as a belt layer, a belt reinforcing layer, a carcass layer, and the like, in a cross section in a tire radial direction, a member disposed on an outer side thereof in the tire radial direction.

[0033] A “rubber component of a rubber composition” is a component that contributes to crosslinking in the rubber composition and generally has a weight average molecular weight (Mw) of 10,000 or more.

[0034] A "total styrene amount S in a rubber composition" is a total styrene amount in mass % in the rubber composition, where a mass of a rubber component is 100 mass %, which is a total amount of contents of styrene parts contained in rubber components and contents of styrene parts contained in coupling agents other than the rubber components. The styrene part is not particularly limited as long as it is a group having a styrene structure, and examples thereof include, for example, styrene, α-methylstyrene, vinyltoluene, chlorostyrene, and the like.

[0035] That is, first, for each rubber component, a value obtained by multiplying a mass % content of each styrene part by a mass fraction in the rubber component is calculated, and these values are added together to obtain a total mass % value. Next, for styrene part-containing coupling agents other than the rubber components included in the rubber composition, a value obtained by multiplying a mass % content of each styrene part of each styrene part-containing coupling agent by a mass fraction relative to 100 parts by mass of the rubber component is calculated, and these values are added together to obtain a total mass % value. A value obtained by adding both total values is defined as a total styrene amount S in mass %.Thus, it is calculated by {Σ(content (mass %) of styrene part of each styrene part-containing rubber × content (mass %) of each styrene part-containing rubber in rubber component / 100) + Σ(content (mass %) of styrene part of each styrene part-containing coupling agent other than rubber component × compound amount (mass parts) of each styrene part-containing coupling agent based on 100 mass parts of rubber component / 100)}.

[0036] For example, when the rubber component consists of 30 mass % of a first SBR (styrene content: 25 mass %), 60 mass % of a second SBR (content of styrene part: 27.5 mass %), and 10 mass % of BR, and the rubber composition further comprises, in addition to the rubber component, 20 mass parts of a first resin having a styrene part (content of styrene part: 5 mass %) based on 100 mass parts of the rubber component and 10 mass parts of a second resin having a styrene part (content of styrene part: 1 mass %) based on 100 mass parts of the rubber component, a total styrene amount S in the rubber composition based on 100 mass % of the rubber component is 25.1 mass % = {(25 × 30 / 100 + 27.5 × 60 / 100 + 0 × 10 / 100) + (5 × 20 / 100 + 1 × 10 / 100)}.

[0037] A "standardized condition" is a condition in which a tire is mounted on a standardized rim, filled with air at a standardized internal pressure, and no load is applied. Unless otherwise specified, a tire is used in the standardized condition.

[0038] A "standardized rim" is a rim in a standards system containing a standard on which the tire is based, which is defined by the standard for each tire. For example, a "standardized rim" refers to a standard rim of an applicable size described in the JATMA (The Japan Automobile Tire Manufacturers Association, Inc.) "JATMA YEAR BOOK," the "Measuring Rim" described in the ETRTO (The European Tire and Rim Technical Organization) "STANDARDS MANUAL," or the "Design Rim" described in the TRA (The Tire and Rim Association, Inc.) "YEAR BOOK," which are referred to in that order. If there is an applicable size at the time of reference, the rim conforms to its standard.In addition, in a case of tires not defined by the standard, the standardized rim shall refer to a rim that can be mounted on the tire and whose width is the narrowest among rims that have the smallest diameter that can maintain internal pressure (ie, does not cause air leakage between the rim and the tire).

[0039] A "standardized internal pressure" is an air pressure in a standard system containing a standard on which the tire is based, which is defined by the standard for each tire. It refers, for example, to a "MAXIMUM AIR PRESSURE" at JATMA, "INFLATION PRESSURE" at ETRTO or a maximum value described in table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" at TRA, referred to in that order, as in the case of the standardized rim, and if there is an applicable size at the time of reference, the standardized internal pressure conforms to its standard.In addition, in the case of tires not defined by the standard, the standardized internal pressure shall refer to a standardized internal pressure (250 kPa or more) of another tire size (specified in the standard) for which the standardized rim is described as a standard rim, and if multiple standardized internal pressures of 250 kPa or more are described, it shall refer to a minimum value among them.

[0040] A "standardized load in kg" is a load in a standard system containing a standard on which the tire is based, which is defined by the standard for each tire, for example, a "MAXIMUM LOAD CAPACITY" in JATMA, a "LOAD CAPACITY" in ETRTO, or a maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in TRA, referred to in that order, as in the case of a standardized rim and a standardized internal pressure, and if there is an applicable size at the time of reference, the load conforms to its standard. Then, in the case of a tire not specified in the standard described above, the separately calculated maximum load capacity WL is defined as a standardized load.

[0041] The "maximum load capacity WL" is calculated by the following equations. Where "V" is a virtual volume of the tire in mm3 of a tire, "Dt" is a tire outer diameter in mm in a standardized state, "Ht" is a tire section height in mm in a tire radial direction in a cross-section of the tire in a plane containing a tire rotation axis, and "Wt" is a tire section width in mm in a standardized state. Where R represents a rim diameter of the tire, Ht can be calculated by (Dt-R) / 2. Wt is a value obtained by excluding patterns or characters on the side surface of the tire, if any. In addition, the "maximum load capacity" has the same meaning as the standardized load described above. WL=0.000011×V+175 V={(Dt / 2)2−(Dt / 2−Ht)2}×π×Wt

[0042] A "ground contact area" is a tread area obtained from a contour when a tire is pressed against the ground. It is obtained by mounting the tire on a standardized rim, filling it with a standardized internal pressure, and allowing the tire to stand at 25°C for 24 hours. This is followed by painting a tire tread surface of the tire with ink, applying a standardized load (load equal to the maximum load capacity) to the tire to press the tire vertically against a cardboard (a camber angle of 0°), and transferring the ink. A ground contact area area refers to a total ground contact area. The total ground contact area can be determined as an average value of five areas obtained by performing the above-described transfer process at a total of five locations by rotating a tire by 72°.

[0043] An "effective ground contact area" is a tread area where a tire contacts the ground when the tire is pressed against the ground. It is obtained by mounting the tire on a standardized rim, filling it with a standardized internal pressure, and allowing the tire to stand at 25°C for 24 hours. This is followed by painting a tire tread surface of the tire with ink, applying a standardized load (load equal to the maximum load capacity) to the tire to press the tire vertically against a cardboard (a camber angle at 0°), and transferring the ink. An area of the effective ground contact area refers to an effective ground contact area. The effective ground contact area can be determined as an average value of five areas obtained by performing the above-described transfer process at a total of five locations by rotating a tire by 72°.

[0044] A “lift ratio R at a ground contact surface of a tread portion” is calculated from a total ground contact area of the ground contact area and an effective ground contact area of the effective ground contact area by the following equation. Elevation ratio R = (effective ground contact area / total ground contact area)

[0045] A "dimension of any part of the tire" is, unless otherwise specified, a value specified in a standardized condition for one appearing on the outer surface of the tire, while for one existing inside the tire or for one on a tire cut surface, it is a value specified in a condition in which, for example, the tire is cut along a plane containing a tire axis of rotation and the cut tire piece is held to a rim width of a standardized rim.

[0046] A "loss tangent (tanδ) of a rubber composition" is a tanδ under each condition as measured in a stretching mode using a dynamic viscoelasticity measuring device (e.g., EPLEXOR series, manufactured by gabo Systemtechnik GmbH). A sample for measuring dynamic viscoelasticity is a vulcanized rubber composition measuring 20 mm in length × 4 mm in width × 1 mm in thickness. In a case where the sample is prepared by cutting from a tire, when a member from which the sample is prepared is a tread portion, a longitudinal direction of the sample is configured to coincide with a tire circumferential direction, and a thickness direction of the sample is configured to coincide with a tire radial direction. In addition, the sample is prepared so that its dimensions are as close as possible to predetermined dimensions.This is because a strain applied to the sample is normalized with respect to the length and normalized to a tanδ to be measured with the width and thickness of the sample, so it is assumed that there is no influence due to the size of the sample.

[0047] "70 °C-tanδ" is a loss tangent (tanδ) measured under a condition of a temperature of 70 °C, a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±1%, and a strain mode.

[0048] The “0 °C tanδ” is a loss tangent (tanδ) measured under a condition of a temperature of 0 °C, a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±2.5% and a strain mode.

[0049] “30 °C-tanδ” is a loss tangent (tanδ) measured under a condition of a temperature of 30 °C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of ±1%, and a strain mode.

[0050] A “modulus at 200% strain” is a stress at 200% strain (MPa) obtained by preparing a test piece in the shape of dumbbell No. 7 with a thickness of 1 mm and conducting a tensile test under a condition of a tensile speed of 3.3 mm / sec in an atmosphere at 23 °C according to JIS K 6251:2017.

[0051] A "groove" refers to a depressed portion formed on a tire tread surface (extending toward an inner side in a tire radial direction) that has an opening width of 2.0 mm or more on the tread surface. A groove with a groove width of less than 2.0 mm refers to a "sipe."

[0052] A "circumferential groove" refers to a groove that extends continuously in a tire circumferential direction. The circumferential groove may extend linearly along a circumferential direction or may extend in a wave-like, sinusoidal, or zigzag pattern along the circumferential direction.

[0053] A "content of a styrene moiety" is calculated by pyrolysis gas chromatography. Furthermore, in the present specification, "pyrolysis gas chromatography" refers to a method of heating a sample in a pyrolysis device, separating individual components contained in gas-phase components generated by this heating using a separation column, and analyzing each separated component.

[0054] A “vinyl content (1,2-bound butadiene unit amount)” is also calculated by pyrolysis gas chromatography.

[0055] A “cis content (cis-1,4-bonded butadiene unit amount)” is a value calculated by infrared absorption spectrometry according to JIS K 6239-2:2017, and is applied to a rubber component having a repeating unit derived from butadiene, such as a BR and the like.

[0056] A "weight-average molecular weight (Mw)" can be calculated with respect to a standard polystyrene based on measured values obtained by gel permeation chromatography (GPC) (e.g., GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKgel (registered trademark) SuperMultiporeHZ-M manufactured by Tosoh Corporation). For example, it is applied to an SBR, a BR, a plasticizer, and the like.

[0057] A “specific nitrogen adsorption surface area (N2SA) of carbon black” is measured according to JIS K 6217-2:2017.

[0058] A “nitrogen adsorption specific surface area (N2SA) of silica” is measured by the BET method according to ASTM D3037-93.

[0059] An "average primary particle size" is a value obtained by photographing particles using a transmission or scanning electron microscope and calculating an arithmetic mean of particle sizes of 400 particles. When a particle shape is spherical, a diameter of the sphere is defined as a particle size; and when the shape is non-spherical, a circle-equivalent diameter (positive square root of {4 × (area of particle) n}) is calculated from the microscope image, thus defining it as a particle size.

[0060] A "plasticizer" is a material that imparts plasticity to a rubber component and is a component extracted from a rubber composition using acetone. Furthermore, the plasticizer includes a plasticizer that is liquid (in a fluid state) at 25°C and a plasticizer that is solid at 25°C. However, it shall not include wax and stearic acid, which are commonly used in the tire industry.

[0061] A “softening point of resin” is specified as a temperature at which a ball falls when the softening point defined in JIS K 6220-1:2015 7.7 is measured with a ring-and-ball softening point measuring device.

[0062] A process for producing a tire that is an embodiment of the present invention will be described in detail below. However, the following descriptions are illustrative for explaining the present invention and are not intended to limit the technical scope of the present invention to this description range only. Furthermore, in the present description, a numerical range identified as "to" means that it includes the numerical values from both ends. <Laufflächenabschnitt>

[0063] Fig. 1 is a cross-sectional view schematically showing a part of a tread of a tire according to an embodiment of the present invention. Fig. 1, a vertical direction is a tire radial direction, a horizontal direction is a tire width direction, and a direction perpendicular to a paper surface is a tire circumferential direction.

[0064] The tread portion according to the present embodiment includes three or more rubber layers. A configuration of the rubber layer includes a first layer whose outer surface forms a tread surface, a second layer adjacent to an inner side in a radial direction of the first layer, and a third layer provided on an inner side in a radial direction of the second layer. One or more rubber layers may be further provided between the second layer and the third layer or between the third layer and the belt layer.

[0065] A total styrene amount S1 in the rubber composition constituting the first layer based on 100 mass % of the rubber component of the rubber composition is, from the viewpoint of the effects of the present invention, preferably 20.0 mass % or more, more preferably 21.0 mass % or more, even more preferably 22.0 mass % or more, even more preferably 23.0 mass % or more, even more preferably 24.0 mass % or more, even more preferably 25.0 mass % or more, particularly preferably 26.0 mass % or more. Furthermore, from the viewpoint of fuel efficiency, S1 is preferably 40.0 mass % or less, more preferably 38.0 mass % or less, and even more preferably 35.0 mass % or less.

[0066] A total styrene amount S2 in the rubber composition constituting the second layer, based on 100 mass % of the rubber component of the rubber composition, is preferably 10.0 mass % or more, more preferably 12.0 mass % or more, even more preferably 14.0 mass % or more, and particularly preferably 15.0 mass % or more from the viewpoint of the effects of the present invention. Furthermore, from the viewpoint of fuel efficiency, S2 is preferably 25.0 mass % or less, more preferably 20.0 mass % or less, and even more preferably 18.0 mass % or less.

[0067] From the viewpoint of the effects of the present invention, S1-S2 is more than 0 mass%, preferably more than 3.0 mass%, more preferably more than 5.0 mass%, even more preferably more than 7.0 mass%, and particularly preferably more than 10.0 mass%. Moreover, from the viewpoint of forming fine styrene domains in the second layer to facilitate absorption of external deformation through the interfaces between the styrene domains and the surrounding rubber molecular chains, S1-S2 is preferably less than 25.0 mass%, more preferably less than 22.0 mass%, even more preferably less than 20.0 mass%, and particularly preferably less than 18.0 mass%.

[0068] A total amount of styrene S3 in the rubber composition constituting the third layer based on 100 mass% of the rubber component of the rubber composition is not particularly limited, and it may be, for example, 0 mass%.

[0069] In addition, a total styrene amount of a rubber composition can be appropriately adjusted depending on the types and compounding amounts of rubber components described later. For example, a total styrene amount S can be increased by compounding a styrene-butadiene rubber with a high content of a styrene moiety, by compounding a resin comprising styrene as a monomer component, or the like. Conversely, the total styrene content S can be reduced by decreasing a compounding amount of a styrene-butadiene rubber or the like.

[0070] From the viewpoint of the effects of the present invention, 70°C-tan δ of the rubber composition constituting the first layer (70°C-tan δ1) is preferably 0.12 or more, more preferably 0.15 or more, and even more preferably 0.17 or more. Furthermore, from the viewpoint of uneven abrasion resistance, 70°C-tan δ1 is preferably 0.25 or less, more preferably 0.23 or less, and even more preferably 0.20 or less.

[0071] 70°C tan δ of the rubber composition constituting the second layer (70°C tan δ2) is preferably 0.10 or more, more preferably 0.11 or more, and even more preferably 0.12 or more, from the viewpoint of the effects of the present invention. Furthermore, 70°C tan δ2 is preferably 0.20 or less, more preferably 0.18 or less, and even more preferably 0.15 or less, from the viewpoint of uneven abrasion resistance.

[0072] 70°C-tan δ of the rubber composition constituting the third layer (70°C-tan δ3) is preferably 0.02 or more, more preferably 0.04 or more, and even more preferably 0.05 or more from the viewpoint of the effects of the present invention. Furthermore, 70°C-tan δ3 is preferably 0.12 or less, more preferably 0.10 or less, and even more preferably 0.08 or less from the viewpoint of uneven abrasion resistance.

[0073] 70 °C-tanδ2 / 70 °C-tanδ3 is preferably greater than 1.0, more preferably greater than 1.5, even more preferably greater than 2.0 and most preferably greater than 2.3.

[0074] In addition, the 70°C tan δ of the rubber composition can be appropriately adjusted depending on the types and compounding amounts of a rubber component, a filler, a plasticizer, and the like, which will be described later. For example, the 70°C tan δ can be increased by increasing the total amount of styrene in a rubber composition.

[0075] The modulus (M2) at 200% elongation of the rubber composition constituting the second layer is preferably 5.0 MPa or more, more preferably 6.0 MPa or more, and even more preferably 8.0 MPa or more, from the viewpoint of the effects of the present invention. Furthermore, from the viewpoint of uneven abrasion resistance, M2 is preferably 12.0 MPa or less, more preferably 11.0 MPa or less, even more preferably 10.0 MPa or less, and particularly preferably 9.5 MPa or less.

[0076] A modulus (M1) at 200% elongation of the rubber composition constituting the first layer is preferably 4.5 MPa or more, more preferably 5.0 MPa or more, and even more preferably 6.0 MPa or more from the viewpoint of the effects of the present invention. Furthermore, from the viewpoint of uneven abrasion resistance, M1 is preferably 12.0 MPa or less, more preferably 10.0 MPa or less, and even more preferably 8.0 MPa or less. In addition, a modulus (M3) at 200% elongation of the rubber composition constituting the third layer is not particularly limited.

[0077] In Fig. 1, a double arrow t1 is a thickness of the first layer 6, a double arrow t2 is a thickness of the second layer 7, and a double arrow t3 is a thickness of the third layer 8. In Fig.1, a center point in a tire width direction of the land portion 2 is represented as a symbol P. A straight line represented by a symbol N is a straight line (a normal) passing through the point P and perpendicular to a tangential plane at this point P. In the present description, in the cross section of Fig. 1 the thicknesses t1, t2 and t3 are measured along the normal N drawn from the point P on the tread surface at a position where no grooves exist.

[0078] For a “thickness of each rubber layer constituting a tread” when the tire has a groove on a tire equator plane, a thickness of a rubber layer at a center portion in a tire width direction of a land portion closest to the tire equator plane is a thickness of each rubber layer constituting the tread.

[0079] The thickness t1 of the first layer is preferably 0.3 mm or more from the viewpoint of fuel efficiency, more preferably 0.4 mm or more, and even more preferably 0.5 mm or more. Furthermore, from the viewpoint of uneven abrasion resistance, t1 is preferably 5.0 mm or less, more preferably 4.5 mm or less, even more preferably 4.0 mm or less, even more preferably 3.5 mm or less, and particularly preferably 3.0 mm or less.

[0080] A thickness t2 of the second layer is preferably 2.0 mm or more, more preferably 3.0 mm or more, and even more preferably 3.5 mm or more. Furthermore, t2 is preferably 10.0 mm or less, more preferably 8.0 mm or less, and even more preferably 7.0 mm or less.

[0081] A thickness t3 of the third layer is preferably 0.5 mm or more, more preferably 1.0 mm or more, and even more preferably 1.5 mm or more. Furthermore, t3 is preferably 5.0 mm or less, more preferably 4.5 mm or less, and even more preferably 4.0 mm or less.

[0082] From the viewpoint of the effects of the present invention, S1 × t1 is preferably less than 100.0, more preferably less than 70.0, even more preferably less than 50.0, and particularly preferably less than 25.0. Moreover, from the viewpoint of ensuring S1 and t1 at a certain level or higher, S1 × t1 is preferably greater than 8.0, more preferably greater than 10.0, and even more preferably greater than 15.0.

[0083] The tread portion according to the present embodiment preferably includes a plurality of circumferential grooves 1 extending continuously in a tire circumferential direction. The circumferential groove 1 may extend linearly along the circumferential direction or may extend in a zigzag shape along the circumferential direction. Furthermore, the tread portion according to the present embodiment preferably includes land portions 2 separated by the circumferential grooves 1 in a tire width direction.

[0084] A groove depth H of the deepest portion of the circumferential groove 1 is calculated by a distance between an extension line 4 of a tread surface 3 and an extension line 5 of the deepest portion of the groove bottom of the circumferential groove 1. In addition, when there are a plurality of circumferential grooves 1, the groove depth H may be, for example, a distance between the extension line 4 of the tread surface 3 and the extension line 5 of the deepest portion of the groove bottom of the circumferential groove 1 (a circumferential groove 1 on the left side in Fig. 1) with the deepest groove depth among the plurality of circumferential grooves 1.

[0085] The elevation ratio R of the tire according to the present embodiment is preferably 0.60 or more, more preferably 0.65 or more, even more preferably 0.68 or more, and particularly preferably 0.70 or more from the viewpoint of the effects of the present invention. Furthermore, from the viewpoint of grip performance, the elevation ratio R is preferably 0.90 or less, more preferably 0.88 or less, and even more preferably 0.85 or less.

[0086] The ratio (70°C-tanδ1 / R) of 70°C-tanδ1 to the elevation ratio R at the ground contact surface of the tread portion is preferably less than 0.40, more preferably less than 0.35, and even more preferably less than 0.29 from the viewpoint of uneven wear resistance. Furthermore, from the viewpoint of fuel efficiency, 70°C-tanδ1 / R is preferably greater than 0.18, more preferably greater than 0.20, and even more preferably greater than 0.22.

[0087] The ratio (70°C-tanδ2 / R) of 70°C-tanδ2 to the elevation ratio R at the ground contact surface of the tread portion is preferably greater than 0.17, more preferably greater than 0.20, and even more preferably greater than 0.22 from the viewpoint of uneven wear resistance. Furthermore, from the viewpoint of fuel efficiency, it is preferably less than 0.35, more preferably less than 0.31, and even more preferably less than 0.29. <umfangsrille>

[0088] Fig. 2 shows an enlarged plan view of a circumferential groove 1 according to an embodiment of the present invention. In Fig. 2, groove edges 10 of the circumferential groove 1 are indicated by solid lines, and contours 12 of a groove wall when a tread portion is viewed in plan view are indicated by dashed lines. Furthermore, depressed areas (depressed portions 11) between the groove edge 10 of the circumferential groove 1 and the contour 12 of the groove wall are indicated by dots.

[0089] Fig. 3 shows a cross-sectional view of the Fig. 2 along the line AA. As shown in Fig. 3, the circumferential groove 1 is provided on groove walls on both sides, with recessed portions 11 each having a constant recess amount in a tire circumferential direction. The recessed portion 11 has, for example, a flat surface 44 formed between the deepest portion of the recessed portion and the groove edge 10, but is not limited to such an aspect.

[0090] A total depression amount of the circumferential groove 1 is preferably 0.10 to 0.90 times, more preferably 0.15 to 0.80 times, even more preferably 0.20 to 0.70 times a groove width W1 of the circumferential groove 1. Furthermore, in the present specification, a "total depression amount of a circumferential groove" refers to c1 + c2 when the circumferential groove 1 has the Fig. 3 shown aspect. [Rubber composition]

[0091] The rubber composition constituting the first or second layer of the tread portion according to the present embodiment (which may hereinafter be referred to as the rubber composition according to the present embodiment) comprises a rubber component comprising a styrene-butadiene rubber (SBR) and / or an isoprene-based rubber, and silica, and at least one of the rubber composition constituting the first layer and the rubber composition constituting the second layer comprises a copolymer resin comprising styrene and cyclopentadiene as monomer components, each of which can be produced using raw materials described below. The rubber composition according to the present embodiment is described below.

[0092] The rubber composition constituting the first layer preferably comprises two or more diene-based rubbers selected from the group consisting of an SBR, an isoprene-based rubber, and a butadiene rubber (BR), more preferably comprises an SBR and an isoprene-based rubber, and still more preferably comprises an SBR, an isoprene-based rubber, and a BR.

[0093] The rubber composition constituting the second layer preferably comprises one or more diene-based rubbers selected from the group consisting of an SBR rubber, an isoprene-based rubber, and a BR, more preferably comprises two or more diene-based rubbers selected from the group consisting of an SBR rubber, an isoprene-based rubber, and a BR, and still more preferably comprises an SBR rubber and an isoprene-based rubber. <kautschukkomponente>

[0094] The rubber component preferably comprises a diene-based rubber. As the diene-based rubber, any of those commonly used in the tire industry can be suitably used. Specific examples of the diene-based rubbers include, for example, an isoprene-based rubber, a BR, an SBR, a styrene-isoprene rubber (SIR), a styrene-isoprene-butadiene rubber (SIBR), a chloroprene rubber (CR), an acrylonitrile-butadiene rubber (NBR), and the like. These diene-based rubbers can be used alone, or two or more of them can be used in combination.

[0095] A content of a diene-based rubber in the rubber component of the rubber composition according to the present embodiment is preferably 90 mass% or more, more preferably 95 mass% or more, and even more preferably 99 mass% or more. The rubber component may be one consisting of a diene-based rubber. (SBR)

[0096] An SBR is not particularly limited; examples thereof include a solution-polymerized SBR (S-SBR), an emulsion-polymerized SBR (E-SBR), modified SBRs (a modified S-SBR, a modified E-SBR) thereof, and the like. Examples of the modified SBR include an SBR modified at its terminal and / or main chain, a modified SBR coupled with tin, a silicon compound, etc. (a modified SBR of condensate or having a branched structure, etc.), and the like. These SBRs can be used alone, or two or more of them can be used in combination.

[0097] A content of a styrene moiety in an SBR is preferably greater than 18 mass %, more preferably greater than 20 mass %, and even more preferably greater than 25 mass % from the viewpoint of the effects of the present invention. On the other hand, the content of the styrene moiety in the SBR is preferably less than 60 mass %, more preferably less than 50 mass %, and even more preferably less than 45 mass %. When the content of the styrene moiety in the SBR is greater than 60 mass %, styrene groups will abut each other, a polymer becomes too hard, and crosslinking is likely to become non-uniform, which may deteriorate blowing performance during high-temperature driving, and temperature dependence increases, and a change in performance with respect to a temperature change becomes large, resulting in a tendency that stable adhesion performance cannot be satisfactorily obtained during driving and in the later stage thereof.Furthermore, in the present specification, the content of the styrene part in the SBR is measured by the measuring method described above.

[0098] A vinyl content of an SBR is preferably more than 10 mol%, more preferably more than 15 mol%, and even more preferably more than 20 mol%. Furthermore, the vinyl content of the SBR is preferably less than 70 mol%, more preferably less than 65 mol%, and even more preferably less than 60 mol%. Furthermore, in the present specification, the vinyl content of the SBR is measured by the measurement method described above.

[0099] A glass transition point (Tg) of an SBR is preferably -80°C or higher, more preferably -70°C or higher, and even more preferably -65°C or higher from the viewpoint of wet grip performance. Furthermore, the Tg of the SBR is preferably -40°C or lower, more preferably -45°C or lower, even more preferably -50°C or lower, and even more preferably -55°C or lower from the viewpoint of fuel efficiency. In addition, the Tg of the SBR in the present specification is calculated by subjecting a pure SBR content to differential scanning calorimetry (DSC) in accordance with JIS K 7121 after removing an extender oil by using acetone in accordance with JIS K 6229.

[0100] A weight-average molecular weight (Mw) of an SBR is preferably greater than 200,000, more preferably greater than 300,000, even more preferably greater than 400,000, and particularly preferably greater than 500,000. Furthermore, from the viewpoints of crosslinking uniformity, etc., the Mw is preferably less than 2,000,000, more preferably less than 1,500,000, and even more preferably less than 1,000,000. In addition, the Mw of the SBR is measured by the measurement method described above.

[0101] As an SBR, an oil-extended SBR or a non-oil-extended SBR can be used. As SBRs that can be used in the present embodiment, those commercially available from JSR Corporation, Sumitomo Chemical Co., Ltd., UBE Corporation, Asahi Kasei Corporation, ZS Elastomer Co., Ltd., ARLANXEO, etc. can be used.

[0102] A content of an SBR in the rubber component constituting the first layer can be appropriately adjusted so that S1-S2 and S1 × t1 are within the above-described ranges, but it is preferably 30 mass% or more, more preferably 40 mass% or more, even more preferably 50 mass% or more, even more preferably 60 mass% or more, even more preferably 70 mass% or more, and particularly preferably 80 mass% or more. Furthermore, the content of the SBR in the rubber component is preferably 95 mass% or less, and further preferably 90 mass% or less.

[0103] A content of an SBR in the rubber component constituting the second layer can be appropriately adjusted so that S1-S2 falls within the above-mentioned ranges, but it is preferably 20 mass% or more, more preferably 30 mass% or more, even more preferably 40 mass% or more, even more preferably 50 mass% or more, even more preferably 60 mass% or more, and particularly preferably 70 mass% or more. Moreover, the content of the SBR in the rubber component is preferably 95 mass% or less, more preferably 90 mass% or less, even more preferably 85 mass% or less. (Isoprene-based rubber)

[0104] As an isoprene-based rubber, for example, those commonly used in the tire industry can be used, such as isoprene rubber (IR), natural rubber, and the like. Examples of natural rubber include unrefined natural rubber (NR) and refined natural rubber, such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), ultrapure natural rubber, grafted natural rubber, and the like. These isoprene-based rubbers can be used alone, or two or more of them can be used in combination.

[0105] An NR is not particularly restricted, and those commonly used in the tire industry may be used, examples of which include SIR20, RSS#3, TSR20, and the like.

[0106] A content of an isoprene-based rubber in each of the rubber component constituting the first layer and the rubber component constituting the second layer is preferably 10 mass% or more, more preferably 15 mass% or more, and even more preferably 20 mass% or more. Furthermore, the content is preferably 70 mass% or less, more preferably 60 mass% or less, and even more preferably 50 mass% or less. (BR)

[0107] A BR is not particularly limited, and those commonly used in the tire industry can be used, such as a BR with a cis content of less than 50 mol% (a low-cis BR), a BR with a cis content of 90 mol% or more (a high-cis BR), a rare earth-based butadiene rubber synthesized using a rare earth element-based catalyst (a rare earth-based BR), a BR containing a syndiotactic polybutadiene crystal (a SPB-containing BR), a modified BR (a high-cis modified BR, a low-cis modified BR), and the like. These BRs can be used alone, or two or more of them can be used in combination.

[0108] As the cis-rich BR, for example, those commercially available from Zeon Corporation, UBE Corporation, JSR Corporation, etc. can be used. When the cis-rich BR is bonded, low-temperature properties and abrasion resistance can be improved. A cis content of the cis-rich BR is preferably more than 95 mol%, more preferably more than 96 mol%, and even more preferably more than 97 mol%. In addition, the cis content of the BR is measured by the measurement method described above.

[0109] The rare earth-based BR includes those synthesized using a rare earth element-based catalyst and having a vinyl content of preferably less than 1.8 mol%, more preferably less than 1.6 mol%, and even more preferably 1.5 mol% or less, and a cis content of preferably more than 95 mol%, more preferably more than 96 mol%, and even more preferably 97 mol% or more. As the rare earth-based BR, for example, those commercially available from LANXESS, etc., can be used.

[0110] Examples of the SPB-containing BR include those in which a 1,2-syndiotactic polybutadiene crystal is chemically bonded and dispersed with BR, but not those in which the crystal is simply dispersed in the BR. As such SPB-containing BR, those commercially available from UBE Corporation, etc., can be used.

[0111] Examples of the modified BR include a BR modified with a functional group or the like similar to those described for the SBR, and a modified butadiene rubber (a modified BR) modified at its terminal and / or main chain with a functional group containing at least one element selected from the group consisting of silicon, nitrogen, and oxygen can be suitably used.

[0112] Examples of other modified BRs include those obtained by adding a tin compound after polymerizing 1,3-butadiene by a lithium initiator, the end of which is further bonded by a tin-carbon bond (tin-modified BR), and the like. Furthermore, the modified BR may be either non-hydrogenated or hydrogenated.

[0113] A weight-average molecular weight (Mw) of a BR is preferably greater than 300,000, more preferably greater than 350,000, and even more preferably greater than 400,000 from the viewpoint of abrasion resistance. Furthermore, it is preferably less than 2,000,000, more preferably less than 1,000,000, and even more preferably less than 500,000 from the viewpoint of crosslinking uniformity, etc. In addition, the Mw can be calculated by the method described above.

[0114] A content of a BR in each of the rubber component constituting the first layer and the rubber component constituting the second layer is preferably 1 mass% or more, more preferably 5 mass% or more, and even more preferably 10 mass% or more, but is not particularly limited. Furthermore, the content of the BR in the rubber component is preferably 50 mass% or less, more preferably 30 mass% or less, even more preferably 25 mass% or less. (Other rubber components)

[0115] The rubber component may include rubber components other than diene-based rubbers (non-diene-based rubbers) as long as they do not impair the effects of the present invention. As the non-diene-based rubbers, rubber components commonly used in the tire industry can be used, examples of which include, for example, a butyl-based rubber, an ethylene-propylene rubber, a polynorbornene rubber, a silicone rubber, a polyethylene chloride rubber, a fluororubber (FKM), an acrylic rubber (ACM), a hydrin rubber, and the like. These other rubber components may be used alone, or two or more of them may be used in combination. Furthermore, the rubber component may or may not include a known thermoplastic elastomer in addition to the rubber components described above. (Rubber component synthesized from recycled / biomass-derived raw material)

[0116] A monomer that is a structural unit of a synthetic rubber such as an SBR, a BR, and the like may be one derived from petroleum or recycled from a rubber product such as a tire and the like, or a non-rubber product such as polystyrene and the like. The monomer obtained by recycling (recycled monomer) is not particularly limited, and examples thereof include a recycled butadiene, a recycled aromatic vinyl compound, and the like. Examples of the butadiene include 1,2-butadiene, 1,3-butadiene, and the like. The above-described aromatic vinyl compound is not particularly limited, and examples thereof include styrene and the like. Among them, a recycled butadiene (recycled butadiene) and / or a recycled styrene (recycled styrene) are preferably used as a raw material.

[0117] A method of producing a recycled monomer is not particularly limited, examples thereof include, for example, a method of synthesizing a monomer from a recycled naphtha obtained by decomposing a rubber product such as a tire and the like. Moreover, a method of producing a recycled naphtha is not particularly limited, and a recycled naphtha can be obtained, for example, by decomposing a rubber product such as a tire and the like under high temperature and high pressure, by decomposing it by microwaves, or by extruding it after mechanically pulverizing it.

[0118] Furthermore, a monomer that is a structural unit of a polymer such as an SBR, a BR, and the like may be a biomass-derived monomer. The biomass-derived monomer (biomass monomer) is not particularly limited, and examples thereof include a biomass-derived butadiene, a biomass-derived aromatic vinyl compound, and the like. Examples of the butadiene include 1,2-butadiene, 1,3-butadiene, and the like. The above-described aromatic vinyl compound is not particularly limited, and examples thereof include styrene and the like. Furthermore, a method of producing a biomass monomer is not particularly limited, and examples thereof include, for example, one by a biological and / or a chemical and / or a physical conversion of animals and plants, and the like.Microbial fermentation is representative of biological conversion, and examples of chemical and / or physical conversion include catalyst conversion, high heat conversion, high pressure conversion, electromagnetic wave conversion, critical fluid conversion, and combinations thereof. Examples of biomass sources for these monomers include sugar, wood, a plant residue after recovery of a useful component, a plant-derived ethanol, a biomass naphtha, and the like.

[0119] A polymer synthesized from a biomass monomer component (biomass polymer) is not particularly limited; examples thereof include a polybutadiene rubber synthesized from biomass-derived butadiene, an aromatic-vinyl-butadiene copolymer synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl, and the like. Examples of the aromatic-vinyl-butadiene copolymer include, for example, a styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene, and the like.

[0120] Whether a polymer raw material is derived from biomass can be determined by pMC (percent modern carbon), measured according to ASTM D6866-10. Here, pMC is a ratio of 14 C concentration of a sample to 14 C concentration of a modern standard reference agent, and this value is used as an index indicating the biomass ratio of a compound (rubber). The meaning of this value is mentioned below.

[0121] In 1 mole of carbon atoms (6.02 × 10 23 pieces) are about 6.02 × 10 11 14 C, which are about one trillionth the number of normal carbon atoms. A half-life of 14 C is 5730 years, and 14 C decreases regularly. Thus, for fossil fuels such as coal, petroleum, natural gas and the like, where it is assumed that 226,000 years or more have passed since carbon dioxide in the atmosphere was absorbed by plants to fix it, all 14 C elements that were present in it at the beginning of fixation. Therefore, fossil fuels such as coal, petroleum, natural gas, and the like, do not contain any 14 C element. Therefore, the chemical substances produced using these fossil fuels as raw materials also do not contain 14 C element.

[0122] on the other hand 14 C is constantly generated by cosmic rays, which cause nuclear reactions in the atmosphere. Thus, decreases in 14 C due to radioactive decay and production of 14 C due to nuclear reactions and the amount of 14 C in the Earth’s atmospheric environment. Thus, the 14 C concentration of substances derived from biomass resources circulating in the current environment, a value of about 1 × 10 -12 Mole% based on total carbon atoms, as described above. Accordingly, by using a difference between these values, a ratio (biomass ratio) of compounds derived from natural resources (compounds derived from biomass resources) in a particular compound (rubber) can be calculated.

[0123] This 14 C is generally measured as follows. Using accelerator mass spectrometry based on a tandem accelerator, a 13 C concentration ( 13 C / 12 C) and a 14 C concentration ( 14 C / 12 C) is measured. During the measurements, a 14 C concentration in a circulating carbon in nature from 1950 as the modern standard reference for the 14 C concentration is used. An oxalic acid standard body provided by the National Institute of Standards and Technology (NIST) is used as a specific reference material. A specific radioactivity of carbon in this oxalic acid (radioactivity intensity of 14 C per gram of carbon) is sorted for each carbon isotope, 13 C is corrected to a constant value, and a value corrected for attenuation from 1950 to the measurement date is used as a standard 14 C concentration value (100%) is used. The ratio of this value to an actually measured value for a sample is called a pMC value.

[0124] Thus, if a rubber is produced from a material derived 100% from biomass (natural), it will show a value of approximately 110 pMC (currently, under normal conditions, it is often not equal to 100), although there are regional variations, etc. On the other hand, if these 14 C concentration measured for a chemical substance derived from a fossil fuel, such as petroleum and the like, has a value of approximately 0 pMC (e.g., 0.3 pMC). This value corresponds to a biomass ratio of 0%, as mentioned above.

[0125] Due to the above, it is suitable in terms of environmental protection to use a material such as a rubber having a high pMC value and the like, that is, a material such as a rubber having a high biomass ratio and the like for a rubber composition. [Filler]

[0126] The rubber composition according to the present embodiment preferably comprises a filler. A filler of each of the rubber composition constituting the first layer and the rubber composition constituting the second layer comprises silica, and preferably comprises silica and carbon black. Furthermore, the filler may be a filler consisting of carbon black and silica. <siliciumdioxid>

[0127] Silica is not particularly limited, and those commonly used in the tire industry can be used, such as silica produced by a dry process (anhydrous silica), silica produced by a wet process (hydrous silica), and the like. A raw material of silica is not particularly limited and can be, for example, a raw material derived from minerals such as quartz and the like, a raw material derived from biomaterials such as rice husks and the like (e.g., silica made from a biomass material such as rice husks and the like), or silica recycled from a silica-containing product. Among them, hydrous silica produced by a wet process is preferable because it has many silanol groups.This silica can be used alone, or two or more of them can be used in combination.

[0128] Silica made from a biomass material can be obtained, for example, by extracting silicate from rice husk ash obtained by burning rice husks using a sodium hydroxide solution and, in the same manner as a conventional wet silica, filtering, washing with water, drying, and pulverizing precipitates of silica produced by reacting with sulfuric acid using the silicate.

[0129] As the silica recycled from a product containing silica, for example, silica recovered from an electronic component such as a semiconductor, a tire, a product containing silica such as a desiccant, a filter material such as diatomaceous earth, and the like can be used. Furthermore, a recovery method is not particularly limited; examples include pyrolysis, decomposition by electromagnetic waves, and the like. Among them, silica recovered from an electronic component such as a semiconductor, etc., or from a tire is preferable.

[0130] When silica crystallizes, it is insoluble in water, and silicic acid, a component of silica, cannot be used. By controlling the firing temperature and firing time, crystallization of silica in rice husk ash can be suppressed (JP 2009-2594 A, Akita Prefectural University Web Journal B / 2019, vol. 6, pp. 216-222, etc.). As an amorphous silica extracted from rice husk, those commercially available from Wilmar, etc., can be used.

[0131] A nitrogen adsorption specific surface area (N2SA) of silica is preferably 100 m from the viewpoint of ensuring reinforcement property and adhesion performance 2 / g or more, more preferably 120 m 2 / g or more, more preferably 140 m 2 / g or more, more preferably 160 m 2 / g or more and particularly preferably 170 m 2 / g or more. In addition, from the point of view of heat generation and processability, it is preferably 350 m 2 / g or less, more preferably 300 m 2 / g or less and more preferably 250 m 2 / g or less. In addition, the N2SA of silicon dioxide is measured by the measurement method described above.

[0132] An average primary particle size of the silica is preferably 10 nm or more, more preferably 12 nm or more, even more preferably 14 nm or more, and particularly preferably 16 nm or more. Furthermore, the average primary particle size is preferably 24 nm or smaller, more preferably 22 nm or smaller, and even more preferably 20 nm or smaller. In addition, the average primary particle size of silica is measured by the measurement method described above.

[0133] A silica content based on 100 parts by mass of the rubber component in the rubber composition constituting the first layer is preferably greater than 50 parts by mass, more preferably greater than 60 parts by mass, and even more preferably more than 70 parts by mass. Furthermore, from the viewpoint of reducing heat generation, the silica content based on 100 parts by mass of the rubber component is preferably less than 110 parts by mass, more preferably less than 100 parts by mass, and even more preferably less than 90 parts by mass.

[0134] A silica content based on 100 parts by mass of the rubber component in the rubber composition constituting the second layer is preferably greater than 50 parts by mass, more preferably greater than 60 parts by mass, and even more preferably 80 parts by mass or more. Furthermore, from the viewpoint of reducing heat generation, the silica content based on 100 parts by mass of the rubber component is preferably less than 110 parts by mass, more preferably less than 100 parts by mass, and even more preferably less than 90 parts by mass. <silankupplungsmittel>

[0135] Silica is preferably used in combination with a silane coupling agent. Examples of the silane coupling agent include, for example, sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl)disulfide, bis(3-triethoxysilylpropyl)tetrasulfide, and the like; mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and the like; vinyl-based silane coupling agents such as vinyltriethoxysilane, vinyltrimethoxysilane, and the like; amino-based silane coupling agents such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, and the like. Glycidoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane and the like;Nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane, and the like; chlorine-based silane coupling agents such as 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, and the like, but are not particularly limited thereto. Among them, sulfide-based silane coupling agents and / or mercapto-based silane coupling agents are preferably used. As the silane coupling agent, for example, those commercially available from Evonik Industries AG, Momentive Performance Materials, etc. can be used. These silane coupling agents can be used alone, or two or more of them can be used in combination.

[0136] A content of a silane coupling agent based on 100 parts by mass of the rubber component (a total amount of plural silane coupling agents when used in combination) is preferably more than 3.0 parts by mass, more preferably more than 5.0 parts by mass, and even more preferably more than 6.0 parts by mass from the viewpoint of enhancing silica dispersibility. Furthermore, from the viewpoint of preventing deterioration of abrasion resistance, it is preferably less than 15 parts by mass, more preferably less than 10 parts by mass, and even more preferably less than 9.0 parts by mass. <Ruß>

[0137] Examples of carbon black are not particularly limited and include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, and the like. A raw material of carbon black may be a biomass material such as lignin, a vegetable oil, and the like, or may be a pyrolysis oil obtained by pyrolyzing a scrap tire. Furthermore, a method of producing carbon black may be one by combustion, such as a furnace method, and the like, one by hydrothermal carbonization (HTC), or one by pyrolysis of methane, such as a thermal carbon black method, and the like. As commercially available products, products of Asahi Carbon Co., Ltd., Cabot Japan KK, Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, NIPPON STEEL Carbon Co. Ltd., Columbia Chemical Corporation, etc. can be used. They can be used alone, or two or more of them can be used in combination.

[0138] Furthermore, besides the carbon black described above, from the viewpoint of environmental performance, carbon black from a biomass material such as lignin and the like, or a reclaimed carbon black obtained by pyrolyzing and refining a product containing carbon black such as a tire and the like can be used as the carbon black.

[0139] A "recovered carbon black" in the present specification refers to a carbon black obtained by pulverizing a product such as a used tire comprising carbon black and the like and burning the pulverized product, in which, when the product is subjected to oxidative combustion by heating in the air using a thermal gravity measurement method according to JIS K 6226-2:2003, a mass ratio of ash (ash content), which is a component that does not burn, is 13 mass% or more. That is, a mass ratio (carbon amount) of a weight loss content due to oxidative combustion of the recovered carbon black is 87 mass% or less. The recovered carbon black can be expressed by rCB.

[0140] The recovered carbon black can be obtained from a pyrolysis process of a used pneumatic tire. For example, EP3427975 A, with reference to "Rubber Chemistry and Technology", Vol. 85, No. 3, pages 408 to 449 (2012), particularly pages 438, 440, and 442, describes that the recovered carbon black can be obtained by pyrolysis of an organic material at 550 to 800°C in the absence of oxygen or by vacuum pyrolysis at a relatively low temperature (

[0027] ). As mentioned in

[0004] of JP 6856781 B (A comparison of surface morphology and chemistry of pyrolytic carbon blacks with commercial carbon blacks, Powder Technology 160 (2005) 190-193), such carbon black obtained by the pyrolysis process usually lacks a functional group on its surface.

[0141] The recovered carbon black may lack a functional group on its surface, or it may be treated so that its surface includes a functional group. The treatment performed so that the surface of the recovered carbon black includes a functional group can be implemented by a conventional method. For example, in EP3173251A, carbon black including a hydroxyl and / or carboxyl group on its surface is obtained by treating carbon black obtained from a pyrolysis process with potassium permanganate under an acidic condition. Furthermore, in JP6856781B, carbon black whose surface is activated is obtained by treating carbon black obtained from a pyrolysis process with an amino acid compound including at least one thiol group or disulfide group. The recovered carbon black according to the present embodiment also includes carbon black whose surface has been treated to include a functional group.

[0142] As the recovered carbon black, those commercially available from Strebl Green Carbon Pte Ltd., LDC Co., Ltd. etc. can be used.

[0143] An average primary particle size of carbon black is preferably 15 nm or more, more preferably 18 nm or more, even more preferably 20 nm or more, and particularly preferably 22 nm or more. On the other hand, from the viewpoint of obtaining reinforcing properties, the average primary particle size is preferably 100 nm or smaller, more preferably 80 nm or smaller, and even more preferably 50 nm or smaller. In addition, the average primary particle size of carbon black is measured by the measurement method described above.

[0144] A nitrogen adsorption specific surface area (N2SA) of carbon black is preferably 200 m from the viewpoint of the effects of the present invention 2 / g or less, more preferably 180 m 2 / g or less and more preferably 150 m 2 / g or less. In addition, N2SA is preferably 30 m 2 / g or greater, more preferably 40 m 2 / g or greater and even more preferably 45 m 2 / g or greater. In addition, the N2SA of soot is measured using the measurement method described above.

[0145] A content of carbon black when incorporated in the rubber composition constituting the first layer or the second layer, based on 100 parts by mass of the rubber component, is preferably greater than 3 parts by mass, more preferably greater than 5 parts by mass, and even more preferably greater than 9 parts by mass from the viewpoint of reinforcing properties. Furthermore, from the viewpoint of maintaining flexibility for mitigating elongation, it is preferably less than 50 parts by mass, more preferably less than 40 parts by mass, even more preferably less than 30 parts by mass, and particularly preferably less than 20 parts by mass. <Andere Füllstoffe>

[0146] The filler may contain other fillers besides silica and carbon black. Other fillers are not particularly limited, and those conventionally and commonly used in the tire industry, such as aluminum hydroxide, calcium carbonate, alumina, clay, talc, and the like, may be incorporated. [Other connecting devices]

[0147] The rubber composition according to the present embodiment may suitably comprise, in addition to the rubber components and fillers, coupling agents conventionally and usually used in the tire industry, for example, a plasticizer, a processing aid, a vulcanized rubber particle, wax, stearic acid, zinc oxide, an antioxidant, a vulcanizing agent, a vulcanization accelerator, etc., and it is preferable that at least one of the rubber composition constituting the first layer and the rubber composition constituting the second layer comprises a copolymer resin comprising styrene and cyclopentadiene as monomer components, and that the rubber composition constituting the first layer comprises a copolymer resin comprising styrene and cyclopentadiene as monomer components. <plastifizierungsmittel>

[0148] The plasticizer is a material that imparts plasticity to the rubber component and has a concept that includes both a plasticizer that is liquid (in a liquid state) at 25°C and a plasticizer that is solid at 25°C. Examples of the plasticizer include resin, oil, a liquid polymer, an ester-based plasticizer, and the like. These plasticizers may be those derived from petroleum, those derived from biomass, or those derived from naphtha recycled from a rubber product or a non-rubber product. In addition, a low-molecular-weight hydrocarbon component obtained by pyrolyzing and extracting a waste tire or a product comprising various components may be used as a plasticizer.The plasticizers may be used alone, or two or more of them may be used in combination. <<Copolymerharz, das Styrol und Cyclopentadien als Monomerkomponenten umfasst> >

[0149] The copolymer resin comprising styrene and cyclopentadiene as monomer components is not particularly limited as long as it is a resin comprising styrene and cyclopentadiene as monomer components, and may further comprise other monomer components described below. Furthermore, it may be one obtained by hydrogenation or modification thereof.

[0150] The monomer components other than styrene and cyclopentadiene are, but not particularly limited, preferably monomer components commonly used in petroleum resins, more preferably a C9 fraction described below, etc., still more preferably indene.

[0151] As the copolymer resin comprising styrene and cyclopentadiene as monomer components, a copolymer resin comprising styrene, cyclopentadiene and / or dicyclopentadiene and indene as monomer components is preferable, and it may be one obtained by hydrogenating or modifying the copolymer resin.

[0152] As the copolymer resin comprising styrene and cyclopentadiene as monomer components, for example, those commercially available from Exxon Mobil Corporation, ENEOS Corporation, Zeon Corporation, Maruzen Petrochemical Co., Ltd., etc. can be used. The resin can be used alone, or two or more of them can be used in combination.

[0153] A content of a styrene moiety in a copolymer resin comprising styrene and cyclopentadiene as monomer components is preferably 0.5 mass% or more, more preferably 0.8 mass% or more, and still more preferably 1.0 mass% or more from the viewpoint of the effects of the present invention. Furthermore, an upper limit of the content of the styrene moiety is not particularly limited, but may be, for example, less than 50 mass%, less than 40 mass%, less than 30 mass%, 10 mass% or less, 5 mass% or less, 3 mass% or less, or the like.

[0154] A softening point of a copolymer resin comprising styrene and cyclopentadiene as monomer components is preferably higher than 70°C, more preferably higher than 80°C, even more preferably higher than 90°C, and particularly preferably higher than 100°C from the viewpoint of the effects of the present invention. Moreover, it is preferably lower than 150°C, more preferably lower than 140°C, and even more preferably lower than 130°C from the viewpoints of processability and improvement of dispersibility of a rubber component with a filler. The softening point of resin is measured by the measurement method described above.

[0155] A content of a copolymer resin comprising styrene and cyclopentadiene as monomer components based on 100 parts by mass of the rubber component is preferably more than 5 parts by mass, more preferably more than 10 parts by mass, even more preferably more than 15 parts by mass, even more preferably more than 19 parts by mass, and particularly preferably more than 22 parts by mass. Furthermore, from the viewpoint of processability, the content is preferably less than 100 parts by mass, more preferably less than 80 parts by mass, even more preferably less than 60 parts by mass, and particularly preferably less than 40 parts by mass. (Other resins)

[0156] The rubber composition according to the present embodiment may comprise other resins besides the copolymer resin comprising styrene and cyclopentadiene as monomer components. The other resins are not particularly limited, and any resin commonly used in the tire industry can be used. Examples thereof include, for example, a C9-based resin, a C5-based resin, a C5 / C9-based resin, a dicyclopentadiene-based resin, an aromatic vinyl-based resin, a coumarone-based resin, an indene-based resin, a terpene-based resin, a rosin-based resin, a phenol-based resin, and the like. These resin components may be used alone, or two or more of them may be used in combination. Each resin component may also be used alone, or two or more of them may be used in combination. <<Harz auf C9-Basis> >

[0157] A "C9-based resin" refers to a resin obtained by polymerizing C9 fractions, and may be a polymer obtained by polymerizing a C9 fraction alone or a copolymer obtained by copolymerizing a C9 fraction with other components. For example, a resin obtained by copolymerizing dicyclopentadiene (DCPD) with a C9 fraction is called a DCPD / C9 resin. In addition, the C9-based resin may be one obtained by hydrogenating or modifying it.

[0158] Examples of the C9 fraction include, for example, a petroleum fraction having 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, coumarone, indene, methylindene, dicyclopentadiene, and the like. As the C9-based resin, for example, those commercially available from BASF, Zeon Corporation, ENEOS Corporation, etc. <<Harz auf C5-Basis> >

[0159] A "C5-based resin" refers to a resin obtained by polymerizing C5 fractions, and may be one obtained by hydrogenating or modifying them. Examples of C5 fractions other than dicyclopentadiene include, for example, a petroleum fraction having 4 to 5 carbon atoms, such as cyclopentadiene, isoprene, piperylene, 2-methyl-1-butene, 2-methyl-2-butene, 1-pentene, and the like. As the C5-based resin, for example, those commercially available from STRUKTOL, Zeon Corporation, ENEOS Corporation, etc. can be used. <<Harz auf C5 / C9-Basis> >

[0160] A "C5 / C9-based resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be one obtained by hydrogenating or modifying them. As the C5 / C9-based petroleum resin, for example, those commercially available from Tosoh Corporation, Zibo Luhua Hongjin New Material Group Co., Ltd., etc., can be suitably used. <<Harz auf Dicyclopentadien-Basis> >

[0161] A "dicyclopentadiene-based resin" refers to a resin comprising cyclopentadiene (CPD) and / or dicyclopentadiene (DCPD) as a monomer component with the largest content, and may be one obtained by hydrogenating or modifying them. As the dicyclopentadiene-based resin, for example, a polymer obtained by polymerizing only dicyclopentadiene as a monomer, a copolymer obtained by copolymerizing dicyclopentadiene with the C9 fraction (DCPD / C9 resin), and the like are preferable. As the dicyclopentadiene-based resin, for example, those commercially available from Exxon Mobil Corporation, ENEOS Corporation, Zeon Corporation, Maruzen Petrochemical Co., Ltd., etc. can be used. <<Harz auf aromatischer Vinyl-Basis> >

[0162] An "aromatic vinyl-based resin" refers to a resin comprising an aromatic vinyl compound such as styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene, and the like as a monomer component having the largest content, and may be one obtained by hydrogenating or modifying them. As the aromatic vinyl-based resin, 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 because it is economical, easy to process, and excellent in heat generation. As the aromatic vinyl-based resin, for example, those commercially available from Kraton Corporation, Eastman Chemical Company, Mitsui Chemicals, Inc., etc. can be used. <<Harz auf Cumaron-Basis> >

[0163] A "coumarone-based resin" refers to a resin comprising coumarone as a monomer component and may be one obtained by hydrogenating or modifying it. As the coumarone-based resin, for example, a coumarone resin which is a polymer comprising only coumarone as a monomer component, a coumarone-indene resin which is a copolymer comprising coumarone and indene as monomer components, a coumarone-indene-styrene resin which is a copolymer comprising coumarone, indene, and styrene as monomer components, and the like are preferable. As the coumarone-based resin, for example, those commercially available from Rutgers Chemicals, Nitto Chemical Co., Ltd., Mitsui Chemicals, Inc., etc. can be used. <<Harz auf Inden-Basis> >

[0164] An "indene-based resin" refers to a resin comprising indene as a monomer component and may be one obtained by hydrogenating or modifying it. As the indene-based resin, for example, a coumarone-indene resin, which is a copolymer comprising coumarone and indene as monomer components, a coumarone-indene-styrene resin, which is a copolymer comprising coumarone, indene, and styrene as monomer components, and the like are preferable. As the indene-based resin, for example, those commercially available from Rutgers Chemicals, Nitto Chemical Co., Ltd., Mitsui Chemicals, Inc., etc. can be used. <<Harz auf Terpen-Basis> >

[0165] A "terpene-based resin" refers to a resin comprising a terpene compound such as α-pinene, β-pinene, limonene, dipentene, and the like as a monomer component, and may be one obtained by hydrogenating or modifying it. As the terpene-based resin, for example, a polyterpene resin that is a polymer comprising only one or more of the terpene compounds as monomer components, an aromatic-modified terpene resin that is a copolymer comprising the terpene compound and an aromatic compound as monomer components, a terpene-phenolic resin that is a copolymer comprising the terpene compound and a phenol compound as monomer components, and the like are preferable. Examples of the aromatic compound used as a monomer component for the aromatic-modified terpene resin include, for example, styrene, α-methylstyrene, vinyltoluene, divinyltoluene, and the like.Examples of the phenol compound used as a monomer component for the terpene phenolic resin include, for example, phenol, bisphenol A, cresol, xylenol, and the like. As the terpene-based resin, for example, those commercially available from Yasuhara Chemical Co., Ltd., Arakawa Chemical Industries, Ltd., Nippon Terpene Chemicals, Inc., etc., can be used. <<Harz auf Kolophonium-Basis> >

[0166] A "rosin-based resin" refers to a resin comprising a rosin acid compound such as abietic acid, neoabietic acid, palustric acid, isopimaric acid, and the like, and may be one obtained by hydrogenating or modifying it. Examples of the rosin-based resin include, for example, a natural resin rosin and a rosin-modified resin obtained by modifying the natural resin rosin through hydrogenation, disproportionation, dimerization, esterification, etc., but are not particularly limited. As the rosin-based resin, for example, those commercially available from Harima Chemicals Group, Inc., Arakawa Chemical Industries, Ltd., IREC Co., Ltd., etc. can be used. <<Harz auf Phenol-Basis> >

[0167] A "phenol-based resin" refers to a resin comprising a phenolic compound such as phenol, cresol, and the like as a monomer component, and may be one obtained by hydrogenating or modifying it. Examples of the phenol-based resin include, but are not particularly limited to, a phenol-formaldehyde resin, an alkylphenol-formaldehyde resin, an alkylphenol-acetylene resin, an oil-modified phenol-formaldehyde resin, a terpene-phenol resin, and the like. As the phenol-based resin, for example, those commercially available from Sumitomo Bakelite Co., Ltd., DIC Corporation, ASAHI YUKIZAI CORPORATION, etc. can be used. < <erweichungspunkt>>

[0168] A softening point of resin is preferably higher than 80°C, more preferably higher than 90°C, and even more preferably higher than 100°C from the viewpoint of wet grip performance. Moreover, it is preferably lower than 150°C, more preferably lower than 140°C, and even more preferably lower than 130°C from the viewpoints of processability and improvement of dispersibility of a rubber component with a filler. The softening point of resin is measured by the measurement method described above. < <gehalt>>

[0169] A resin content based on 100 parts by mass of the rubber component constituting the first layer or the second layer (a total content when two or more resins are bonded) is preferably more than 10 parts by mass, more preferably more than 15 parts by mass, and even more preferably 20 parts by mass or more. On the other hand, from the viewpoint of suppressing heat generation, the content is preferably less than 80 parts by mass, more preferably less than 60 parts by mass, and even more preferably less than 40 parts by mass. (Plasticizer other than resin)

[0170] Oil, a liquid rubber, and an ester-based plasticizer, which are plasticizers other than resin, are described. <<Ö1>>

[0171] Examples of oil include, for example, mineral oil, vegetable oil, animal oil, and the like. Furthermore, from the perspective of environmental performance, those obtained by purifying waste oil from a rubber mixer or engine, or waste cooking oil used in a restaurant, can be used. This oil can be used alone, or two or more of them can be used in combination.

[0172] In the present specification, a mineral oil refers to oil derived from mineral resources such as petroleum, a natural gas, and the like. Examples of the mineral oil include paraffinic oils (mineral oils), naphthenic oils, aromatic oils, and the like. Specific examples of the mineral oil include, for example, mild extract solvate (MES), distillate aromatic extract (DAE), treated distillate aromatic extract (TDAE), treated residual aromatic extract (TRAE), residual aromatic extract (RAE), and the like. In addition, as an environmental measure, an oil having a low content of a polycyclic aromatic compound (PCA) may also be used. Examples of the oil having a low content of a PCA include MES, TDAE, a heavy naphthenic oil, and the like. The mineral oil may be used alone, or two or more of them may be used in combination.

[0173] In the present specification, examples of the vegetable oil include, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grape seed oil, Japan wax, and the like. Furthermore, examples of the vegetable oil also include a refined oil obtained by refining the above-described oil (an edible oil, etc.).), a transesterified oil obtained by transesterifying the above-described oil, a hydrogenated oil obtained by hydrogenating the above-described oil, a thermally polymerized oil obtained by thermally polymerizing the above-described oil, an oxidized polymerized oil obtained by oxidizing the above-described oil, a used cooking oil obtained by reclaiming what was used as an edible oil, etc., and the like. In addition, the vegetable oil may be liquid or solid at 25°C.

[0174] The vegetable oil preferably comprises acylglycerol, and more preferably comprises triacylglycerol. In the present specification, acylglycerol also refers to a compound in which a hydroxy group of glycerol and a fatty acid are ester-bonded. Acylglycerol is not particularly limited and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Furthermore, acylglycerol may be a monomer, a dimer, or a multimer that is a trimer or higher. Furthermore, acylglycerol that is a dimer or higher may be obtained by thermal polymerization, oxidative polymerization, or the like. Furthermore, acylglycerol may be liquid or solid at 25°C.

[0175] Whether the rubber composition comprises the acylglycerol described above can be determined by 1 H-NMR measurement, but is not particularly limited. For example, a heavy chloroform in which a rubber composition containing triacylglycerol is immersed at room temperature (25 °C) for 24 hours and then removed is subjected to a 1 H NMR was subjected to measurement at room temperature, and signals near 5.26 ppm, near 4.28 ppm, and near 4.15 ppm were observed under a condition that a signal from tetramethylsilane (TMS) was set to 0.00 ppm. These signals are suspected to be derived from hydrogen atoms bonded to carbon atoms adjacent to oxygen atoms of the ester group. Furthermore, "near" in this paragraph is a range of ±0.10 ppm.

[0176] The fatty acid described above is not particularly limited and may be an unsaturated fatty acid or a saturated fatty acid. Examples of the unsaturated fatty acid include a monounsaturated fatty acid such as oleic acid and the like, and a polyunsaturated fatty acid such as linoleic acid, linolenic acid, and the like. Furthermore, examples of the saturated fatty acid include butyric acid, lauric acid, and the like.

[0177] Among them, a fatty acid with few double bonds, that is, a saturated fatty acid or a monounsaturated fatty acid, is desirable as the fatty acid, and oleic acid is preferred. As a vegetable oil comprising such a fatty acid, for example, a vegetable oil comprising a saturated fatty acid or a monounsaturated fatty acid can be used, or a vegetable oil modified by interesterification or the like can be used. Furthermore, to produce a vegetable oil comprising such a fatty acid, a plant can be improved by selective breeding, gene recombination, genome editing, or the like.

[0178] As the vegetable oil, for example, those commercially available from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo KK, ENEOS Corporation, Olisoy, H&R Group, Hokoku Corporation, Fuji Kosan Co., Ltd., The Nisshin OilliO Group, Ltd., etc. can be used.

[0179] Examples of the animal oil include a fish oil, a beef tallow, an oleyl alcohol derived therefrom, or the like.

[0180] The oil content when combined based on 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 even more preferably 20 parts by mass or more from the viewpoint of processability. Furthermore, from the viewpoint of abrasion resistance, it is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 40 parts by mass or less. An oil content also includes an amount of oil contained in an oil-extended rubber. <<Flüssigkautschuk> >

[0181] A liquid rubber is not particularly limited as long as it is a polymer in a liquid state at 25°C. Examples include, for example, a liquid butadiene rubber (a liquid BR), a liquid styrene-butadiene rubber (a liquid SBR), a liquid isoprene rubber (a liquid IR), a liquid styrene-isoprene rubber (a liquid SIR), a liquid farnesene rubber, and the like. The liquid rubber can be used alone, or two or more of them can be used in combination.

[0182] A content of a liquid rubber when combined based on 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 even more preferably 5 parts by mass or more. Furthermore, the content of the liquid rubber is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 10 parts by mass or less. The content of the liquid rubber includes an amount of an extended liquid rubber used to extend the rubber component. <<Plastifizierungsmittel auf Ester-Basis> >

[0183] Examples of the ester-based plasticizer include, for example, dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), bis(2-ethylhexyl)azelate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), trixylenyl phosphate (TXP), and the like. The ester-based plasticizer can be used alone, or two or more of them can be used in combination.

[0184] A content of an ester-based plasticizer when combined based on 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 even more preferably 5 parts by mass or more. Furthermore, the content of the liquid rubber is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 10 parts by mass or less. The content of the ester-based plasticizer includes an amount of an extended ester-based plasticizer used to extend the rubber component.

[0185] A content of a plasticizer (a total content when two or more plasticizers are combined) based on 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 even more preferably more than 34 parts by mass. On the other hand, from the viewpoint of fuel efficiency, the content is preferably less than 120 parts by mass, more preferably less than 100 parts by mass, and even more preferably less than 80 parts by mass. (Vulcanized rubber particle)

[0186] A vulcanized rubber particle is a particle made of vulcanized rubber. Specifically, rubber powder and the like specified in JIS K 6316:2017 can be used. From environmental and cost considerations, recycled rubber powder produced from a pulverized product of a scrap tire or the like is preferred. The vulcanized rubber particle can be used alone, or two or more of them can be used in combination.

[0187] The vulcanized rubber particle is not particularly limited and can be an unmodified vulcanized rubber particle or a modified vulcanized rubber particle. Commercially available vulcanized rubber products include products from Lehigh Technologies, Muraoka Rubber Reclaiming Co., Ltd., etc.

[0188] A content of a vulcanized rubber particle when bonded based on 100 parts by mass of the rubber component can be appropriately adjusted, for example, within a range of more than 1 part by mass and less than 80 parts by mass. (Stearic acid)

[0189] A content of stearic acid when combined based on 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more from the viewpoint of processability, more preferably 1 part by mass or more. Furthermore, from the viewpoint of vulcanization rate, it is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less. (Zinc oxide)

[0190] A content of zinc oxide when combined based on 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 1.5 parts by mass or more from the viewpoint of processability. Furthermore, 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 even more preferably 4.0 parts by mass or less. (Wax)

[0191] Wax is not particularly limited, and any of those commonly used in the tire industry can be suitably used. Examples thereof include, for example, a mineral-based wax, a plant-derived wax, and the like. The mineral-based wax refers to wax derived from mineral resources such as oil, a natural gas, and the like. The plant-derived wax refers to wax derived from natural resources such as a plant, and the like. Among them, the mineral-based wax is preferable. Examples of the plant-derived wax include, for example, a rice wax, a carnauba wax, a candelilla wax, and the like. Examples of the mineral-based wax include, for example, a paraffin wax, a microcrystalline wax, specially selected waxes thereof, and the like. Among them, a paraffin wax is preferable.Furthermore, wax according to the present embodiment should not contain stearic acid. For example, waxes commercially available from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt BV, etc. can be used. Waxes can be used alone, or two or more of them can be used in combination.

[0192] A wax content when combined based on 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, from the viewpoint of weather resistance of a rubber. Furthermore, from the viewpoint of preventing whitening of a tire due to blooming, it is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less. (antioxidant)

[0193] Examples of the antioxidant include, but are not particularly limited to, a naphthylamine-based antioxidant such as phenyl-α-naphthylamine and the like; a diphenylamine-based antioxidant such as octylated diphenylamine, 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine and the like; A p-phenylenediamine-based antioxidant 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'-ditolyl-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), N,N'-di-2-naphthyl-p-phenylenediamine (DNPD), and the like; a quinoline-based antioxidant such as a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline, and the like;a monophenol-based antioxidant such as 2,6-di-t-butyl-4-methylphenol, a styrenated phenol, and the like; bis-, tris-, and polyphenol-based antioxidants such as tetrakis[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane and the like. Among them, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, and polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. As commercially available products, for example, products manufactured by Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexsys, etc. can be used. The antioxidant can be used alone, or two or more of them can be used in combination.;

[0194] A content of an antioxidant when combined based on 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, from the viewpoint of ozone cracking resistance of a rubber. Furthermore, from the viewpoint of abrasion resistance and wet grip performance, it is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less. (processing aids)

[0195] Examples of processing aids include, for example, a fatty acid metal salt, a fatty acid amide, an amide ester, a silica surface activator, a fatty acid ester, a mixture of a fatty acid metal salt and an amide ester, a mixture of a fatty acid metal salt and a fatty acid amide, and the like. As processing aids, for example, those commercially available from Schill+Seilacher GmbH, Performance Additives, etc. can be used. The processing aid can be used alone, or two or more of them can be used in combination.

[0196] A content of the processing aid when combined based on 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, from the viewpoint of exhibiting an effect of improving processability. Furthermore, from the viewpoint of abrasion resistance and fracture strength, it is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and still more preferably 5 parts by mass or less. (vulcanizing agent)

[0197] Sulfur is suitably used as a vulcanizing agent. Powdered sulfur, oil-processing sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and the like can be used as the sulfur. The vulcanizing agent can be used alone, or two or more of them can be used in combination.

[0198] A content of sulfur when combined as a vulcanizing agent based on 100 parts by mass of the rubber component is preferably 0.1 part by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more from the viewpoint of ensuring a sufficient vulcanization reaction. Furthermore, 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 even more preferably 3.0 parts by mass or less. In addition, a content of a vulcanizing agent, when an oily sulfur is used as the vulcanizing agent, should be a total content of pure sulfur contained in the oily sulfur.

[0199] Examples of vulcanizing agents other than sulfur include, for example, an alkylphenol sulfur chloride condensate, sodium hexamethylene 1,6-bisthiosulfate dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, and the like. As these vulcanizing agents other than sulfur, those commercially available from Taoka Chemical Co., Ltd., LANXESS, Flexsys, etc. can be used. The vulcanizing agent can be used alone, or two or more of them can be used in combination. (vulcanization accelerator)

[0200] Examples of the vulcanization accelerator include, for example, sulfenamide-based, thiazole-based, thiuram-based, thiourea-based, guanidine-based, dithiocarbamic acid-based, aldehyde-amine-based, aldehyde-ammonia-based, imidazoline-based, and xanthate-based vulcanization accelerators, and the like. Among them, sulfenamide-based, thiazole-based, and guanidine-based vulcanization accelerators are preferred. The vulcanization accelerator can be used alone, or two or more of them can be used in combination.

[0201] Examples of the sulfenamide-based vulcanization accelerator include, for example, N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N,N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS), and the like. Among them, N-cyclohexyl-2-benzothiazolylsulfenamide (CBS) is preferred.

[0202] Examples of the thiazole-based vulcanization accelerator include, for example, 2-mercaptobenzothiazole, a cyclohexylamine salt of 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and the like. Among them, 2-mercaptobenzothiazole is preferred.

[0203] Examples of the guanidine-based vulcanization accelerator include, for example, 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of dicachol borate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, 1,3-di-o-cumenyl-2-propionylguanidine, and the like. Among them, 1,3-diphenylguanidine (DPG) is preferred.

[0204] A content of a vulcanization accelerator when compounded based on 100 parts by mass of the rubber component is preferably 1 part by mass or more, and more preferably 1.5 parts by mass or more. Moreover, the content of the vulcanization accelerator based on 100 parts by mass of the rubber component is preferably 8 parts by mass or less, more preferably 7 parts by mass or less, even more preferably 6 parts by mass or less. When the content of the vulcanization accelerator is within the above-described ranges, fracture strength and elongation tend to be ensured. <Verschiedene Materialien, die Kohlenstoffatome umfassen>

[0205] In the present specification, various materials comprising carbon atoms (e.g., a rubber, oil, resin, a vulcanization accelerator, an antioxidant, a surfactant, etc.) may be derived from carbon dioxide in the atmosphere. These various materials may be obtained from carbon dioxide by directly converting carbon dioxide or by converting methane obtained via a methanation process by which methane is synthesized from carbon dioxide.

[0206] The rubber composition constituting the third layer of the tread portion can be produced by a conventional method using the above-mentioned raw materials in the same manner as for the rubber composition constituting the first layer and the rubber composition constituting the second layer. However, it preferably comprises an isoprene-based rubber, and more preferably comprises an isoprene-based rubber and a BR as rubber components.

[0207] A content of an isoprene-based rubber in the rubber component constituting the third layer of the tread portion is preferably 50 mass% or more, more preferably 60 mass% or more, and even more preferably 70 mass% or more. Furthermore, a content of a BR in the rubber component constituting the third layer is preferably 10 mass% or more, and more preferably 20 mass% or more.

[0208] The BR in the rubber component constituting the third layer of the tread portion is preferably a low-cis BR having a cis content of less than 50 mol%, more preferably a modified low-cis BR.

[0209] In the rubber composition constituting the third layer of the tread portion, an N2SA of carbon black is preferably 80 m 2 / g or less, more preferably 70 m 2 / g or less. In addition, N2SA is preferably 30 m 2 / g or greater, more preferably 50 m 2 / g or greater and even more preferably 60 m 2 / g or larger.

[0210] A content of carbon black when combined in the rubber composition constituting the third layer, based on 100 parts by mass of the rubber component (a total content when two or more carbon blacks are combined), is preferably more than 20 parts by mass from the viewpoint of the effects of the present invention, more preferably more than 25 parts by mass, even more preferably more than 30 parts by mass, and even more preferably more than 40 parts by mass. Moreover, from the viewpoint of fuel efficiency, it is preferably less than 100 parts by mass, more preferably less than 80 parts by mass, even more preferably less than 60 parts by mass, and particularly preferably less than 50 parts by mass.

[0211] The rubber composition constituting the third layer of the tread portion may or may not include resin as a plasticizer, but preferably contains oil.

[0212] A content of resin based on 100 parts by mass of the rubber component constituting the third layer (a total content when two or more resins are bonded) is not particularly limited, and a lower limit may be, for example, 1 part by mass or more, 3 parts by mass or more, 5 parts by mass or more, or the like, and an upper limit may be 15 parts by mass or less, 10 parts by mass or less, 8 parts by mass or less, or the like. [Production process]

[0213] The rubber composition can be produced by a known method. For example, it can be produced by kneading each of the above-described components using a rubber kneading device such as an open roll, a closed-type kneader (Bunbury mixer, kneader, etc.), and the like.

[0214] For example, the kneading step includes a basic kneading step of kneading coupling agents and additives other than vulcanizing agents and vulcanization accelerators, and a final kneading step (F-kneading) of adding vulcanizing agents and vulcanization accelerators to the kneaded product obtained by the basic kneading step and kneading them. Furthermore, the basic kneading step can be divided into multiple steps if desired.

[0215] A kneading condition is not particularly limited. Examples of kneading include, for example, a method of kneading at a discharge temperature of 150 to 170 °C for 3 to 10 minutes in the initial kneading step and a method of kneading at 70 to 110 °C for 1 to 5 minutes in the final kneading step.

[0216] The tire according to the present embodiment can be produced by a conventional method using the above-described rubber composition. That is, the tire can be produced by extruding the above-described rubber composition in an unvulcanized state into a shape of a first layer, a second layer, or a third layer of a tread portion with an extruder equipped with a die having a predetermined shape, mounting them together with other tire elements on a tire molding machine while adjusting them to have a predetermined tire structure, and molding them by a conventional method to form an unvulcanized tire, followed by heating and pressurizing this unvulcanized tire in a vulcanizing machine. A vulcanization condition is not particularly limited.Examples of vulcanization include, for example, a process of vulcanizing at 140 to 170 °C for 10 to 40 minutes. [Applications]

[0217] In the present specification, the tire can be used for any application, regardless of whether it is a pneumatic tire or a pneumatic tire, 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 heavy-duty tire, or a run-flat tire. In addition, the passenger car tire is a tire under the premise that it is mounted on a car that runs on four wheels and refers to one with a maximum load capacity of less than 1400 kg. Furthermore, the heavy-duty tire refers to a tire with a maximum load capacity of 1400 kg or more. In addition, in the present specification, the tire can be used as an all-season tire, a summer tire, or a winter tire, such as a studless tire and the like. EXAMPLES

[0218] Examples considered preferable in implementing the present invention (Examples) will be described below, although the scope of the present invention is not limited to these Examples only.

[0219] Considering tires having tread portions produced using rubber compositions obtained by varying the compound according to Table 1 using various chemicals shown below, results calculated based on the evaluation methods described below are shown in Tables 2 and 3. No.: TSR20 SBR1: HPR830E, manufactured by JSR Corporation (S-SBR, Tg: -23 °C, styrene content: 39.5 mass%, vinyl content: 38.5 mol%, containing 10.0 mass parts of extender oil based on 100 mass parts of rubber solid content) SBR2: SBR, produced according to Production Example 1 below (S-SBR, Tg: -50 °C, styrene content: 30 mass%, vinyl content: 22 mol%, non-oil-extended) SBR3: SBR, produced according to Production Example 2 below (S-SBR, Tg: -66 °C, styrene content: 19 mass%, vinyl content: 19 mol%, non-oil-extended) BR1: UBEPOL BR (registered trademark) 150B, manufactured by UBE Corporation (cis content: 98 mol%, vinyl content: 1 mol%) BR2: BR1250H, manufactured by Zeon Corporation (tin-modified BR, polymerized using lithium as an initiator, vinyl content: 10 to 13 mol%, cis content: 39.7 mol%) CB1: DIABLACK I, manufactured by Mitsubishi Chemical Corporation (N220, N2SA: 114 m 2 / g, average primary particle size: 22 nm) CB2: Show Black N351H, manufactured by Cabot Japan KK (N2SA: 69 m 2 / g, average primary particle size: 29 nm) CB3: DIABLACK E, manufactured by Mitsubishi Chemical Corporation (N550, N2SA: 41 m 2 / g, average primary particle size: 81 nm) Silicon dioxide: ULTRASIL VN3, manufactured by Evonik Industries AG (N2SA: 175 m 2 / g, average primary particle size: 18 nm) Silane coupling agent: Si266, manufactured by Evonik Industries AG (bis(3-triethoxysilylpropyl) disulfide) Oil: VivaTec 500, manufactured by H&R Group (TDAE oil) Copolymer resin: Oppera PR383, manufactured by Exxon Mobil Corporation (hydrogenated DCPD-C9 resin comprising styrene and cyclopentadiene as monomer components, Mw: 770, softening point: 103 °C, styrene moiety content: 1.78 mass%) Terpene-based resin: YS resin PX1150N, manufactured by Yasuhara Chemical Co., Ltd. (polyterpene resin, softening point: 115 ± 5 °C) Stearic acid: Stearic acid "CAMELLIA", manufactured by NOF CORPORATION Zinc oxide: Zinc oxide No. 1, manufactured by Mitsui Mining & Smelting Co., Ltd. Wax: OZOACE 0355, manufactured by Nippon Seiro Co., Ltd. Antioxidant 1: Nocrac 6C, manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine) Antioxidant 2: Nocrac RD, manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (Poly(2, 2, 4-Trimethyl-1,2-dihydroquinoline)) Sulfur 1: M95, manufactured by Nippon Kanryu Industry Co., Ltd. (insoluble sulfur) Sulfur 2: Powdered sulfur manufactured by Karuizawa Sulfur Co., Ltd. Vulcanization accelerator 1: Nocceler CZ-G, manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N-cyclohexyl-2-benzothiazolylsulfenamide) Vulcanization accelerator 2: Nocceler D, manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (1,3-Diphenylguanidine (DPG)) (Production example 1: Production of SBR2)

[0220] Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene are charged into a nitrogen-purged autoclave reactor. The ratio of styrene to 1,3-butadiene is adjusted so that the styrene content is 30 mass%. After adjusting the temperature of the contents in the reactor, n-butyllithium is added to initiate polymerization. Polymerization is carried out under adiabatic conditions, and the polymerization solution is poured into ethanol to collect a precipitate. The precipitate is blow-dried and then dried under reduced pressure until the loss on drying is 0.1% to obtain SBR2. (Production example 2: Production of SBR3)

[0221] Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene are charged into a nitrogen-purged autoclave reactor. The ratio of styrene to 1,3-butadiene is adjusted so that the styrene content is 19 mass%. After adjusting the temperature of the contents in the reactor, n-butyllithium is added to initiate polymerization. Polymerization is carried out under adiabatic conditions, and the polymerization solution is poured into ethanol to collect a precipitate. The precipitate is blow-dried and dried under reduced pressure until the loss on drying becomes 0.1% to obtain SBR3. (Examples and comparison examples)

[0222] According to the compound recipes shown in Table 1, using a 1.7-liter closed-type Banbury mixer, all chemicals other than sulfur and vulcanization accelerator were kneaded for 1 to 10 minutes until a discharge temperature of 150°C to 160°C was reached to obtain a kneaded product. Next, using a twin-screw open-roll mixer, sulfur and vulcanization accelerator were added to the resulting kneaded product, and the mixture was kneaded for 4 minutes until the temperature reached 105°C to obtain an unvulcanized rubber composition.The obtained unvulcanized rubber composition is molded into a shape of each of a first layer, a second layer (thickness: 4.0 mm), and a third layer (thickness: 1.0 mm) of a tread, and is joined with other tire elements to prepare an unvulcanized tire, followed by press vulcanization for 35 minutes under a condition of 150 °C to obtain each test tire (195 / 65R15) described in Tables 2 and 3. In addition, a groove width W1 of a circumferential groove (groove width on a tread surface) is 5 mm, and a total depression amount of circumferential grooves is 2 mm. <Messung von Modul bei Dehnung von 200 %>

[0223] For a test piece No. 7 in the shape of a dumbbell with a thickness of 1 mm cut out from a second layer of a tread portion of each test tire from the inside so that a tire circumferential direction becomes a tensile direction and a tire radial direction becomes a thickness direction, a tensile test is carried out in accordance with JIS K 6251:2017 under a condition of a tensile speed of 3.3 mm / sec in an atmosphere of 23 °C to measure a modulus (MPa) at elongation of 200%. <Messung von tanδ bei 70 °C>

[0224] A rubber test piece is produced by cutting a tread portion of each test tire, measuring 20 mm in length, 4 mm in width, and 1 mm in thickness, in such a way that a tire circumferential direction becomes a long side and a tire radial direction becomes a thickness direction. For each rubber test piece, a tanδ (70 °C-tanδ) is measured using an EPLEXOR series manufactured by gabo Systemtechnik GmbH under conditions of a temperature of 70 °C, a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±1.0%, and a strain mode. <Ungleichmäßiger Abriebfestigkeit>

[0225] Each test tire is mounted on all wheels of a vehicle (domestic FF, 2000 cc). After the vehicle is driven for 10,000 km on a test track with a dry asphalt road surface at an average speed of 80 km / h, a difference in wear amount on both sides in a tire circumferential direction of a center block, a middle block, and a shoulder block of the rear wheels is measured. For each block, eight blocks with a substantially equal pitch in the tire circumferential direction are used to calculate an average value of all measured values. Then, measurement results are expressed as indexes by the following equation. The results show that the larger the index, the better the uneven wear resistance. For the uneven wear resistance index, Comparative Example 6 is defined as the reference comparative example. (Index of uneven abrasion resistance) = (Difference in abrasion amount from reference comparison example) / (Difference in abrasion amount from each test tire) × 100 <nasshaftungsleistung>

[0226] Each test tire is mounted on all wheels of a vehicle (domestic FF, 2000 cc). The braking distance from an initial speed of 100 km / h on a wet asphalt road surface is calculated. The measurement results are expressed as indices by the following equation. The larger the index, the shorter the braking distance and the more excellent the wet grip performance. For the wet grip performance index, Comparative Example 1 is defined as the reference comparative example. (Wet Grip Performance Index) = (Braking Distance of Reference Comparison Example) / (Braking Distance of Each Test Tire) × 100 <brennstoffeffizienz>

[0227] For each test tire, a rolling resistance coefficient (RRC) is measured in accordance with JIS D 4234:2009 (ISO 28580). For the inverse of the rolling resistance coefficient, the measurement results are expressed as indices using the following equation. The larger the index, the lower the rolling resistance and the better the fuel efficiency. For the fuel efficiency index, Comparative Example 6 is defined as the reference comparative example. (Fuel Efficiency Index) = (Rolling resistance coefficient of reference comparison example) / (Rolling resistance coefficient of each test tire) × 100 <gesamtleistung>

[0228] A sum of an index of uneven wear resistance, a wet grip performance index and a fuel efficiency index is given as an overall performance index. Table 1 Composite quantity A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 Composite quantity (mass parts) NR 20 20 - 20 100 10 90 - - 20 SBR1 88 77 - - - - - - - 88 (oil content) (8) (7) - - - - - - - (8) SBR2 - - 80 80 - 80 - 80 - - SBR3 - - - - - - - - - - BR1 - 10 20 - - 10 10 20 100 - BR2 - - - - - - - - - - CB1 10 10 10 10 10 10 10 10 10 20 CB2 - - - - - - - - - - CB3 - - - - - - - - - - Silicon dioxide 80 80 80 80 80 80 80 80 80 100 Silane coupling agent 6, 4 6, 4 6, 4 6, 4 6, 4 6, 4 6, 4 6, 4 6, 4 8,0 Öl 22 20,5 10 10 10 10 10 10 10 22 copolymer resin 20 20 20 - 20 - 20 - 20 20 Terpene-based resin - - - 20 - 20 - 20 - - Stearic acid 3,0 3,0 3,0 3,0 3,0 3,0 3,0 3,0 3,0 3,0 zinc oxide 3,0 3,0 3,0 3,0 3,0 3,0 3,0 3,0 3,0 3,0 wax 2,0 - - - - - - - - 2,0 Antioxidant 1 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 Antioxidant 2 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 Sulfur 1 - - - - - - - - - - Sulfur 2 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 (Continued on the next page) Composite quantity A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 Vulcanization accelerator 1 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 Vulcanization accelerator 2 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 Total styrene amount (mass%) 32,0 28,0 24,4 24,0 0,4 24,0 0,4 24,0 0,4 32,0 Modulus (MPa) of 200% 6,4 6,6 9,0 9,5 8,1 9,7 8,0 9,7 7,6 7,9 70 °C-tanδ 0,17 0,18 0,15 0,17 0,17 0,17 0,17 0,17 0,16 0,22 (Continued on the next page) Composite quantity B1 B2 B3 B4 B5 B6 B7 B8 B9 C1 Composite quantity (mass parts) NR 20 10 - 20 10 30 - 20 20 75 SBR1 - - - 88 88 66 88 66 - - (oil content) - - - (8) (8) (6) (8) (6) - - SBR2 - - - - - - - - - - SBR3 80 80 80 - - - - - 80 - BR1 - 10 20 - 10 10 20 20 - - BR2 - - - - - - - - - 25 CB1 10 10 10 10 10 10 10 10 10 - CB2 - - - - - - - - - 36 CB3 - - - - - - - - - 6 Silicon dioxide 80 80 80 80 80 80 80 80 80 - Silane coupling agent 6, 4 6, 4 6, 4 6, 4 6, 4 6, 4 6, 4 6, 4 6, 4 - Öl 10 10 10 22 22 19 22 19 10 10 copolymer resin - - - 20 20 20 20 - 20 - Terpene-based resin 20 20 20 - - - - 20 - - Stearic acid 3,0 3,0 3,0 3,0 3,0 3,0 3,0 3,0 3,0 2,0 zinc oxide 3,0 3,0 3,0 3,0 3,0 3,0 3,0 3,0 3,0 3,0 wax 2,0 - - - - - - - - 1,25 Antioxidant 1 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,5 Antioxidant 2 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 0,5 Sulfur 1 - - - - - - - - - 1,25 Sulfur 2 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 1,0 Vulcanization accelerator 1 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 1,6 Vulcanization accelerator 2 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 - Total styrene amount (mass%) 15,2 15,2 15,2 32,0 32,0 24,1 32,0 23,7 15, 6 0,0 (Continued on the next page) B1 B2 B3 B4 B5 B6 B7 B8 B9 C1 Modulus (MPa) of 200% 8,8 9, 3 9, 3 6, 4 6, 4 6, 7 6, 6 6, 8 8, 6 5,2 70 °C-tanδ 0,14 0,14 0,14 0,18 0,18 0,18 0,18 0,19 0,11 0,06 Table 2 Example 1 2 3 4 5 6 7 8 9 First layer A1 A2 A3 A10 A4 A1 A3 A1 A3 Second layer B1 B2 B3 B1 B9 B1 B3 B1 B3 Third layer C1 C1 C1 C1 C1 C1 C1 C1 C1 S1 (mass %) 32,0 28,0 24,4 32,0 24,0 32,0 24,4 32,0 24,4 S2 (mass %) 15,2 15,2 15,2 15,2 15,6 15,2 15,2 15,2 15,2 S1 - S2 16,8 12,8 9,2 16,8 8,4 16,8 9,2 16,8 9,2 t1 (mm) 2,8 1,6 0,7 0,7 0,7 0,7 2,8 0,7 0,7 S1 × t1 89,6 44,8 17,1 22,4 16,8 22,4 68,3 22,4 17,1 Survey ratio R 0,60 0,60 0,60 0,60 0,60 0,60 0,60 0,65 0,55 70 °C-tanδ1 0,17 0,18 0,15 0,22 0,17 0,17 0,15 0,17 0,15 70 °C-tanδ2 0,14 0,14 0,14 0,14 0,11 0,14 0,14 0,14 0,14 70 °C-tanδ3 0,06 0,06 0,06 0,06 0,06 0,06 0,06 0,06 0,06 70 °C-tanδ1 / R 0,28 0,30 0,25 0,37 0,28 0,28 0,25 0,26 0,27 70 °C-tanδ2 / R 0,23 0,23 0,23 0,23 0,18 0,23 0,23 0,22 0,25 70 °C-tanδ2 / 70 °C-tanδ3 2,33 2,33 2,33 2,33 1,83 2,33 2,33 2,33 2,33 (Continued on the next page) 1 2 3 4 5 6 7 8 9 M2 (MPa) 8,8 9,3 9,3 8,8 8,6 8,8 9,3 8,8 9,3 Uneven abrasion resistance 95 115 128 114 134 95 135 92 130 Wet grip performance 126 134 117 105 100 112 103 130 110 Fuel efficiency 100 112 114 100 109 108 108 97 114 Total performance 321 361 359 319 343 315 346 319 354 Table 3 Comparison example 1 2 3 4 5 6 First layer A4 A5 A6 A7 A8 A9 Second layer B4 B4 B5 B6 B7 B8 Third layer C1 C1 C1 C1 C1 C1 S1 (mass %) 24,0 0, 4 24,0 0,4 24,0 0,4 S2 (mass %) 32,0 32,0 32,0 24,1 32,0 23,7 S1 - S2 -8,0 -31,6 -8,0 -23,7 -8,0 -23,3 t1 (mm) 2,8 2,8 1, 6 1, 6 0, 7 0, 7 S1 × t1 67,2 1,12 38,4 0, 64 16, 8 0,28 Survey ratio R 0, 60 0, 60 0, 60 0, 60 0, 60 0, 60 70 °C-tanδ1 0,17 0,17 0,17 0,17 0,17 0,16 70 °C-tanδ2 0,18 0,18 0,18 0,18 0,18 0,19 70 °C-tanδ3 0,06 0,06 0,06 0,06 0,06 0,06 70 °C-tanδ1 / R 0,28 0,28 0,28 0,28 0,28 0,27 70 °C-tanδ2 / R 0,30 0,30 0,30 0,30 0,30 0,32 70 °C-tanδ2 / 70 °C-tanδ3 3,00 3,00 3,00 3,00 3,00 3,17 M2 (MPa) 6, 4 6, 4 6, 4 6, 7 6, 6 6, 8 Uneven abrasion resistance 86 89 86 92 86 100 Wet grip performance 100 83 100 81 100 92 Fuel efficiency 95 97 95 97 95 100 Total performance 281 269 281 270 281 292 <Ausführungsformen>

[0229] Examples of embodiments of the present invention are shown below. [1] A tire comprising a tread portion wherein the tread portion comprises at least a first layer forming a tread surface, a second layer adjacent to an inner side in a tire radial direction of the first layer, and a third layer present on the inner side in the tire radial direction of the second layer, wherein the first layer and the second layer are each composed of a rubber composition comprising a rubber component comprising a styrene-butadiene rubber and / or an isoprene-based rubber, and silicon dioxide, wherein at least one of the rubber composition forming the first layer and the rubber composition forming the second layer comprises a copolymer resin comprising styrene and cyclopentadiene as monomer components, and where, where S1 represents in mass% a total amount of styrene of the rubber composition constituting the first layer, wherein a mass of the rubber component is 100 mass%, and where S2 represents in mass% a total amount of styrene of the rubber composition constituting the second layer, wherein a mass of the rubber component is 100 mass%, S1 - S2 is greater than 0. [2] The tire of [1] above, where, when t1 in mm represents a thickness of the first layer, S1 × t1 is less than 100.0. [3] The tire of [2] above, where S1 × t1 is less than 50.0. [4] The tire of [2] above, where S1 × t1 is less than 25.0. [5] The tire of any one of [1] to [4] above, wherein S1 - S2 is greater than 7.0, preferably greater than 10.0. [6] The tire of any one of [1] to [5] above, wherein S2 is greater than 0 and less than 20.0, preferably greater than 10.0 and less than 20.0, more preferably greater than 10.0 and less than 18.0. [7] The tire of any one of [1] to [6] above, wherein the rubber composition constituting the first layer comprises a copolymer resin comprising styrene and cyclopentadiene as monomer components. [8] The tire of any one of [1] to [7] above, wherein a ratio (70 °C-tanδ1 / R) of a loss tangent at 70 °C of the rubber composition constituting the first layer (tanδ1) to a bump ratio R is less than 0.29. [9] The tire of any one of [1] to [8] above, wherein a ratio (70 °C-tanδ2 / R) of a loss tangent at 70 °C of the rubber composition constituting the second layer (tanδ2) to a bump ratio R is more than 0.20, preferably more than 0.22.

[10] The tire of any one of [1] to [9] above, wherein a modulus M2 at elongation of 200% of the rubber composition constituting the second layer is 9.5 MPa or less.

[11] The tire of any one of [1] to

[10] above, wherein the rubber composition constituting the second layer comprises 80 parts by mass or more of silica based on 100 parts by mass of the rubber component.

[12] The tire of any one of [1] to

[11] above, wherein a ratio (70 °C-tan δ2 / 70 °C-tan δ3) of 70 °C-tan δ2 to a loss tangent at 70 °C of the rubber composition constituting the third layer (70 °C-tan δ3) is more than 1.0, preferably more than 1.5, more preferably more than 2.0, even more preferably more than 2.3.

[13] The tire of any one of the above [1] to

[12] , wherein the tread portion has a plurality of circumferential grooves continuously extending in a tire circumferential direction, and wherein at least one groove wall of the circumferential groove is provided with a depressed portion depressed outward in a groove width direction with respect to a groove edge appearing on a tread surface of the tread portion. LIST OF REFERENCE SYMBOLS 1 circumferential groove 2 bridge section 3 Tread surface 4 Extension line of tread surface 5 Extension line from deepest section of groove bottom of circumferential groove 6 First layer 7 Second layer 8 Third layer 9 Extension of outer surface of second layer N Normal to tread surface on tire equator P Center of web section in tire width direction H Groove depth of deepest section of circumferential groove t1 thickness of first layer t2 thickness of second layer t3 thickness of third layer 10 grooved edge 11 in-depth section 12 Contour 43 deepest section 44 Level W1 Opening width (groove width on tread surface) c1 Amount of depression from groove edge to groove bottom c2 Amount of depression from groove edge to groove bottom QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2023-88085 A [0002, 0003] JP 2009-2594 A

[0130] EP 3427975 A

[0140] JP 6856781 B [0140, 0141] EP 3173251 A

[0141] Cited non-patent literature

[0000] JIS K 6239-2:2017

[0055] JIS K 6220-1:2015 7.7

[0061] JIS K 6226-2:2003

[0139] Rubber Chemistry and Technology", Vol. 85, No. 3, pages 408 to 449 (2012)

[0140] A comparison of surface morphology and chemistry of pyrolytic carbon blacks with commercial carbon blacks, Powder Technology 160 (2005) 190-193

[0140] JIS K 6316:2017

[0186] ISO 28580

[0227] < / gesamtleistung> < / brennstoffeffizienz> < / nasshaftungsleistung> < / gehalt> < / erweichungspunkt> < / plastifizierungsmittel> < / silankupplungsmittel> < / siliciumdioxid> < / kautschukkomponente> < / umfangsrille>

Claims

[1] Tire comprising a tread portion, wherein the tread portion comprises at least a first layer forming a tread surface, a second layer adjacent to an inner side in a tire radial direction of the first layer, and a third layer present on the inner side in the tire radial direction of the second layer, wherein the first layer and the second layer are each composed of a rubber composition comprising a rubber component comprising a styrene-butadiene rubber and / or an isoprene-based rubber, and silicon dioxide, wherein at least one of the rubber composition forming the first layer and the rubber composition forming the second layer comprises a copolymer resin comprising styrene and cyclopentadiene as monomer components, and where, where S1 represents in mass% a total amount of styrene of the rubber composition constituting the first layer, wherein a mass of the rubber component is 100 mass%, and where S2 represents in mass% a total amount of styrene of the rubber composition constituting the second layer, wherein a mass of the rubber component is 100 mass%, S1 - S2 is greater than 0. [2] A tire according to claim 1, wherein when t1 in mm represents a thickness of the first layer, S1 × t1 is less than 100.

0. [3] A tire according to claim 2, wherein S1 × t1 is less than 50.

0. [4] A tire according to claim 2, wherein S1 × t1 is less than 25.

0. [5] A tire according to any one of claims 1 to 4, wherein S1 - S2 is greater than 7.

0. [6] A tire according to any one of claims 1 to 5, wherein S2 is greater than 0 and less than 20.

0. [7] A tire according to any one of claims 1 to 6, wherein the rubber composition constituting the first layer comprises a copolymer resin comprising styrene and cyclopentadiene as monomer components. [8] A tire according to any one of claims 1 to 7, wherein a ratio (70°C-tanδ1 / R) of a loss tangent at 70°C of the rubber composition constituting the first layer (tanδ1) to a bump ratio R is less than 0.

29. [9] The tire according to any one of claims 1 to 8, wherein a ratio (70°C-tanδ2 / R) of a loss tangent at 70°C of the rubber composition constituting the second layer (tanδ2) to a bump ratio R is more than 0.

20. [10] A tire according to any one of claims 1 to 9, wherein a modulus M2 at 200% elongation of the rubber composition constituting the second layer is 9.5 MPa or less. [11] The tire according to any one of claims 1 to 10, wherein the rubber composition constituting the second layer comprises 80 parts by mass or more of silica based on 100 parts by mass of the rubber component. [12] A tire according to any one of claims 1 to 11, wherein a ratio (70°C-tanδ2 / 70°C-tanδ3) of 70°C-tanδ2 to a loss tangent at 70°C of the rubber composition constituting the third layer (70°C-tanδ3) is more than 1.

0. [13] Tire according to one of claims 1 to 12, wherein the tread portion has a plurality of circumferential grooves extending continuously in a tire circumferential direction, and wherein at least one groove wall of the circumferential groove is provided with a depressed portion depressed outward in a groove width direction with respect to a groove edge appearing on a tread surface of the tread portion.

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