Tire

Abstract

The present invention addresses the problem of providing a tire capable of improving the overall performance of low fuel consumption performance and wear resistance performance. [Solution] A tire provided with a tread portion having at least one rubber layer, in which the ratio (G / WL) of the tire weight G (kg) to the maximum load capacity WL (kg) of the tire is 0.0160 or less, the cross-sectional width Wt of the tire is 200 mm or more, a first layer constituting the tread is composed of a rubber composition containing a rubber component and a filler, the thickness t1 of the first layer is greater than 3.0 mm, and the thickness t2 of the first layer is greater than 3.0 mm. When the complex elastic modulus of the rubber composition at 30 DEG C is 30 DEG C E * (MPa) and the ground contact ratio on the ground contact surface of the tread portion is R, 30 DEG C E * is greater than 8.0 MPa, and the product of R and 30 DEG C E * (R * 30 DEG C E *) is greater than 5.0.

Description

Technical Field

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

[0002] On the tread surface of a tire, in addition to low fuel consumption performance (rolling resistance characteristics), performances such as abrasion resistance performance and wet skid resistance performance are also required. Performance improvement is carried out by methods such as designing the rubber composition, filler, etc. for the tread portion (for example, Patent Documents 1 and 2). There is still room for improvement in improving the balance of these performances well. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2008 - 31244 [Patent Document 2] International Publication No. 2013 / 125614 Summary of the Invention [Problems to be Solved by the Invention]

[0004] An object of the present invention is to provide a tire capable of improving the comprehensive performance of low fuel consumption performance and abrasion resistance performance. [Means for Solving the Problems]

[0005] In recent years, in order to reduce the rolling resistance of a tire, the tire has been made lighter. In order to make the tire lighter, reducing the thickness of the tread portion is considered, but there is a concern that the tire life may become shorter due to friction. In addition, since the low - fuel - consumption rubber generates less heat, it has a tendency to immediately deform when receiving an impact and is easily subjected to rubber damage.

[0006] The present invention relates to a tire having a tread portion with at least one rubber layer. The ratio (G / W L (kg)) of the tire weight G (kg) to the maximum load - carrying capacity W L ) of the tire is 0.0160 or less. The sectional width Wt of the tire is 200 mm or more. The first layer constituting the tread is composed of a rubber composition containing a rubber component and a filler. The thickness t1 of the first layer is greater than 3.0 mm. When the complex elastic modulus at 30°C of the rubber composition is 30°C E* (MPa) and the ground contact ratio of the ground contact surface of the tread portion is R, 30°C E* is greater than 8.0 MPa, and the product (R × 30°C E*) of R and 30°C E* is greater than 5.0. [Effects of the Invention]

[0007] According to the present invention, a tire is provided which can improve the comprehensive performance of low fuel consumption performance and abrasion resistance performance. Brief Description of the Drawings

[0008] Figure 1 ​】is a diagram showing the tire cross-sectional width Wt, the tire cross-sectional height Ht, and the tire outer diameter Dt in the tire cross-section. Detailed implementation mode

[0009] The tire according to an embodiment of the present invention is a tire having a tread portion with at least one rubber layer, and the ratio (G / W L (kg)) of the tire weight G (kg) to the maximum load capacity W L ) of the tire is 0.0160 or less, the cross-sectional width Wt of the tire is 200 mm or more, the first layer constituting the tread is composed of a rubber composition containing a rubber component and a filler, the thickness t1 of the first layer is greater than 3.0 mm, when the complex elastic modulus at 30 °C of the rubber composition is 30 °C E* (MPa) and the ground contact ratio of the ground contact surface of the tread portion is R, 30 °C E* is greater than 8.0 MPa, and the product (R × 30 °C E*) of R and 30 °C E* is greater than 5.0.

[0010] Regarding the reason for the comprehensive performance improvement of the low fuel consumption performance and wear resistance performance of the tire of the present invention, although not theoretically restricted purposefully, there are the following considerations.

[0011] It is considered that if the tire cross-sectional width Wt is increased, the maximum load capacity W L increases. Therefore, when G / W L is 0.0160 or less, the low fuel consumption effect brought by the weight reduction of the tire is improved.

[0012] In addition, by making 30 °C E* of the first layer greater than 8.0 MPa, the rubber becomes hard, and the deformation amount of the rubber can be suppressed. It is further considered that by increasing the ground contact ratio, the force applied to the rubber per unit area becomes smaller, and the deformation amount of the rubber is suppressed. Thus, it is considered that by making their product above a certain value, the deformation of the rubber can be suppressed.

[0013] And it is considered that by applying the above requirements to a tire with a tire cross-sectional width Wt of 200 mm or more and a first layer thickness t1 greater than 3.0 mm, through their synergy, it contributes to the improvement of the comprehensive performance of the low fuel consumption performance and wear resistance performance of the tire.

[0014] The tanδ (30 °C tanδ) of the rubber composition at 30 °C is preferably less than 0.25.

[0015] It is considered that by making 30 °C tanδ within the above range, the low fuel consumption performance can be improved.

[0016] The product (30 °C tanδ × 30 °C E* × t1) of 30 °C tanδ, 30 °C E*, and t1 is preferably less than 8.25.

[0017] It is considered that by making 30°C tanδ × 30°C E* × t1 within the said range, both low fuel consumption performance and the hardness of the rubber can be taken into account.

[0018] From the viewpoints of abrasion resistance performance and wet grip performance, the rubber composition preferably contains silica with an average primary particle size of 16 nm or less.

[0019] From the viewpoints of abrasion resistance performance and low fuel consumption performance, the rubber composition preferably contains a mercapto-based silane coupling agent.

[0020] The acetone extraction amount of the rubber composition is preferably 20% by mass or less.

[0021] It is considered that by making the acetone extraction amount within the said range, the hardness of the rubber can be ensured and the abrasion resistance performance can be improved.

[0022] From the viewpoint of the effects of the present invention, the rubber component preferably contains an isoprene-based rubber.

[0023] From the viewpoint of the effects of the present invention, the rubber component preferably contains a styrene-butadiene rubber with a styrene content of 30% by mass or less.

[0024] S / 30°C E* is preferably 2.5 or less.

[0025] If the 30°C E* is small, the deformation of the tread rubber becomes large. On the other hand, by reducing the total styrene amount S in the rubber component, the heat generation during the deformation of the tread rubber can be suppressed. It is considered that thus, by reducing the total styrene amount S as the 30°C E* decreases, the low fuel consumption performance and the breaking strength of the tread rubber are further improved. In addition, from the viewpoint of the effects of the present invention, the total styrene amount S in the rubber component is preferably 25% by mass or less.

[0026] The product of R and S (R × S) is preferably 15.0 or less.

[0027] It is considered that by making R × S within the said range, both low fuel consumption performance and abrasion resistance performance can be taken into account.

[0028] Taking the modulus at 200% elongation of the rubber composition as M 200 (MPa), the M of the rubber composition 200 、30°C E* and 30°C tanδ preferably satisfy the relational expression M 200 × 30°C E* / 30°C tanδ ≥ 200.

[0029] It is considered that by making M 200 × 30°C E* / 30°C tan within the said range, the low fuel consumption performance and the abrasion resistance performance can be improved with good balance.

[0030] From the perspective of the difficulty of oil migration, the rubber composition preferably contains vegetable oil.

[0031] From the perspective of building a sustainable society, the filler preferably contains silica made from biomass materials.

[0032] <Definition> The "tread face" is the part that forms the ground contact surface of the tire. When there are components such as steel and fabric materials that form the tire skeleton through the belt layer, belt reinforcement layer, and carcass layer in the tire radial cross-section, it is the component that is further outside in the tire radial direction than them.

[0033] The "normal state" means a no-load state in which the tire is mounted on the normal rim and filled with air at the normal internal pressure.

[0034] Unless otherwise specified, the "dimensions of each part of the tire" are the values specified in the normal state for the components that appear on the outer surface of the tire. On the other hand, for the components that exist inside the tire or in the tire cross-section, for example, the tire is cut with a plane containing the tire rotation axis, and the cut tire piece is held in the state of the rim width of the normal rim and the values are specified.

[0035] The "normal rim" means, in the specification system that includes the specifications on which the tire is based, the rim specified for each tire by this specification. For example, if it is JATMA (Japan Automobile Tire Association), it is the standard rim under the applicable dimensions recorded in the "JATMA YEAR BOOK". If it is ETRTO (The European Tyre and Rim Technical Organisation), it is the "Measuring Rim" recorded in the "STANDARDS MANUAL". If it is TRA (The Tire and Rim Association, Inc.), it is the "Design Rim" recorded in the "YEAR BOOK". Refer to the order of JATMA, ETRTO, and TRA. When referring, if there are applicable dimensions, follow their specifications. In addition, for a tire not specified by the above specifications, it means the rim with the smallest rim width among the rims that can be mounted on the tire and can maintain the internal pressure (that is, no air leakage occurs between the rim / tire).

[0036] "Normal internal pressure" means the air pressure specified for each tire in the specification system that includes the specifications on which the tire is based. For example, in the case of JATMA, it is the "maximum air pressure"; in the case of ETRTO, it is the "Inflation Pressure"; in the case of TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". The same applies to the case of a normal rim. Refer to JATMA, ETRTO, and TRA in this order. When there is an applicable size during the reference, follow its specifications. It should be noted that for a tire not specified by the said specifications, it means the normal internal pressure (where it is 250 kPa or more) of other tire sizes (wherein, those specified in the specifications) recorded with the said normal rim as the standard rim. When there are multiple recorded normal internal pressures of 250 kPa or more, it means the minimum value among them.

[0037] "Normal load" means the load specified for each tire in the specification system that includes the specifications on which the tire is based. For example, in the case of JATMA, it is the "maximum load capacity"; in the case of ETRTO, it is the "Load Capacity"; in the case of TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". The same applies to the cases of a normal rim and normal internal pressure. Refer to JATMA, ETRTO, and TRA in this order. When there is an applicable size during the reference, follow its specifications. And when the said specifications do not specify a tire, the maximum load capacity W L calculated separately is the normal load.

[0038] "Maximum load capacity W L " is calculated by the following calculation formula. "V" is the hypothetical volume of the tire (mm 3 ), "Dt" is the outer diameter of the tire in the normal state (mm), "Ht" is the tire cross-sectional height in the radial direction of the tire on the tire cross-section obtained by the plane including the tire rotation axis (mm), and "Wt" is the tire cross-sectional width in the normal state (mm). When the rim diameter of the tire is R, Ht can be obtained by (Dt - R) / 2. Wt is the value obtained by removing patterns, characters, etc. on the tire sidewall. In addition, the maximum load capacity is synonymous with the said normal load.

[0039]

Equation 1

[0040] "The tire weight G (kg)" means the weight of the tire monomer without the weight of the rim. On the other hand, when the tire inner cavity part is equipped with a sound-absorbing material, a sealant, a sensor, etc., G is the weight including these.

[0041] Including circumferential grooves and transverse grooves, a "groove" means a depression with a width of at least more than 2.0 mm.

[0042] The "contact area" is the tread area obtained from the contour when the tire is pressed against the ground. After installing the tire on a regular rim, loading the regular internal pressure, and standing for 24 hours at 25°C, ink is applied to the tire tread surface. Then, a regular load (maximum load capacity) is applied to the tire and it is vertically pressed against thick paper (camber angle is 0°), and it is obtained by printing the ink. The area of the contact area is called the total contact area. The total contact area can be calculated as follows: rotate the tire by 72° each time, and perform the above printing operation at a total of 5 locations, and take the average of the 5 areas obtained.

[0043] The "effective contact area" is the tread area where the tire is in contact with the ground when the tire is pressed against the ground. After installing it on a regular rim, loading the regular internal pressure, and standing for 24 hours at 25°C, ink is applied to the tire tread surface. Then, a regular load (maximum load capacity) is applied to the tire and it is vertically pressed against thick paper (camber angle 0°), and it is obtained by printing the ink. The area of the effective contact area is the effective contact area. The effective contact area can be calculated as follows: rotate the tire by 72° each time, and perform the above printing operation at a total of 5 locations, and take the average of the 5 areas obtained.

[0044] The "contact ratio R" is calculated from the total contact area of the contact area and the effective contact area of the effective contact area by the following formula. (Contact ratio) = (Effective contact area / Total contact area)

[0045] The "overall thickness of the tread part" means the overall thickness of the tread part on the tire equatorial plane in the cross-section obtained by cutting the tire with a plane including the tire rotation axis. In addition, the inner end in the tire radius direction of the overall thickness of the tread part is the inner interface of the rubber composition constituting the tread part in the tire radius direction. When the tire has a belt reinforcing layer, a belt layer, and a carcass layer, it is the overall thickness of the rubber layer that is more on the outer side in the tire radius direction than the outermost layer in the tire radius direction among them. In addition, when there is a circumferential groove on the tire equatorial plane, measure the overall thickness of the tread part as the tire with the groove filled.

[0046] "The thickness of each rubber layer constituting the tread portion" is the thickness of each rubber layer on the equatorial plane of the tire in a cross section obtained by cutting the tire with a plane containing the rotation axis of the tire, and is the average thickness of the tread portion obtained at 5 positions by rotating the tire 72° each time in the circumferential direction. For example, the thickness of the first layer refers to the straight-line distance in the radial direction of the tire from the outermost surface of the tread to the inner radial interface of the first layer on the equatorial plane of the tire. In addition, when there is a circumferential groove on the equatorial plane of the tire, the thickness of each rubber layer constituting the tread portion is the thickness of each rubber layer on the central part in the tire width direction of the land portion closest to the equatorial plane of the tire. "The land portion closest to the equatorial plane of the tire" refers to the land portion of the circumferential groove existing on the equatorial plane of the tire and having the groove edge closest to the equatorial plane of the tire. When such a land portion exists on both sides in the tire width direction, the thickness of each rubber layer constituting the tread portion is the average thickness of each rubber layer on the central part in the tire width direction of the two land portions. Furthermore, when a conducting component or the like exists on the land portion on the tire equatorial plane and the interface is unclear, the interface blocked by the conducting component or the like is virtually connected and measured.

[0047] "Plasticizer" refers to a material that gives plasticity to the rubber component and is extracted from the rubber composition with acetone. Plasticizers include plasticizers that are liquid at 25°C and plasticizers that are solid at 25°C. Among them, wax and stearic acid commonly used in the tire industry are not included.

[0048] The "content of plasticizer" includes the amount of plasticizer contained in the extended rubber component that has been extended in advance by a plasticizer such as oil, resin component, liquid rubber component, etc. In addition, the same applies to the content of oil, the content of resin component, and the content of liquid rubber. For example, when the extended component is oil, the extended oil is included in the content of the oil.

[0049] <Measurement method> The “thickness of each rubber layer constituting the tread portion” is measured in a state where the tire is cut along a plane including the tire rotation axis so that the width of the bead portion matches the normal rim width.

[0050] "30°C tanδ" is the loss tangent measured using a dynamic viscoelasticity measuring device (e.g., EPLEXOR series manufactured by GABO) at a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of ±1%, and a tensile mode. The sample for the loss tangent measurement is a vulcanized rubber composition of 20 mm in length, 4 mm in width, and 1 mm in thickness. When cutting out from a tire for production, the sample is cut out from the tread portion of the tire with the tire circumferential direction as the long side and the tire radial direction as the thickness direction.

[0051] "30℃ E*" is the complex elastic modulus measured under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of ±1%, and a tensile mode using a dynamic viscoelasticity measuring device (e.g., EPLEXOR series manufactured by GABO). The sample for this measurement is produced in the same manner as in the case of 30°C tanδ.

[0052] "Modulus at 200% elongation (M 200 )" is the tensile stress (MPa) at 200% elongation in the grain direction (the calendering direction when forming a rubber sheet by extrusion or shearing) measured at 23°C in an atmosphere based on JIS K 6251:2017 under the condition of a tensile speed of 3.3 mm / sec. M 200 The sample for measurement is a dumbbell-shaped No. 7 vulcanized rubber test piece with a thickness of 1 mm. When cutting and producing from a tire, it is cut from the tread of the tire in such a way that the circumferential direction of the tire is the tensile direction and the radial direction of the tire is the thickness direction.

[0053] "Acetone extraction amount" can be obtained by immersing each vulcanized rubber test piece in acetone for 72 hours based on JIS K 6229:2015, extracting the soluble components, measuring the mass of each test piece before and after extraction, and calculating using the following formula. When cutting and producing from a tire, it is cut from the tread of the tire in such a way that the circumferential direction of the tire is the long side and the radial direction of the tire is the thickness direction. (Acetone extraction amount (mass%)) = {((mass of rubber test piece before extraction - mass of rubber test piece after extraction) / (mass of rubber test piece before extraction))} × 100

[0054] "Styrene content" is a value calculated by pyrolysis gas chromatography and is applicable, for example, to rubber components having repeating units of styrene from SBR, etc. In addition, in this specification, "pyrolysis gas chromatography" refers to a method of heating a sample through a pyrolysis device, separating each component contained in the gas phase components generated by this heating through a separation column, and analyzing each separately separated component.

[0055] "Vinyl content (1,2-bond butadiene unit amount)" is a value calculated by infrared absorption spectrometry in accordance with JIS K 6239-2:2017 and is applicable, for example, to rubber components having repeating units of butadiene from SBR, BR, etc.

[0056] "Cis content (cis-1,4-bond butadiene unit amount)" is a value calculated by infrared absorption spectrometry in accordance with JIS K 6239-2:2017 and is applicable, for example, to rubber components having repeating units of butadiene from BR, etc.

[0057] "Total styrene content in the rubber component" means the total content (mass %) of styrene units contained in 100% by mass of the rubber component. For each rubber component, the value obtained by multiplying the styrene content (mass %) by the mass fraction in the rubber component is calculated, and these values are added up. Specifically, it is calculated by Σ (styrene content (mass %) of each rubber containing styrene units × content (mass %) of each rubber containing styrene units in the rubber component / 100).

[0058] "Weight-average molecular weight (Mw)" can be determined based on the measured values of gel permeation chromatography (GPC) (for example, GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKgel SuperMultipore HZ-M manufactured by Tosoh Corporation) and converted by standard polystyrene conversion. For example, it is applicable to SBR, BR, plasticizers, etc.

[0059] "Nitrogen adsorption specific surface area (N2SA) of carbon black" is measured based on JIS K 6217-2:2017. "Nitrogen adsorption specific surface area (N2SA) of silica" is measured by the BET method based on ASTM D3037-93.

[0060] "Average primary particle size" is obtained by photographing the particles with a transmission or scanning electron microscope and calculating the arithmetic average of 400 particle sizes. When the shape of the particle is almost circular, the diameter of the circle is used as the particle size; when it is needle-shaped or rod-shaped, the minor axis is used as the particle size; in other cases, the circular equivalent diameter calculated from the electron microscope image is used as the particle size. The circular equivalent diameter is obtained as the positive square root of [4 × (particle area) / π]. The average primary particle size is applicable to silica, carbon black, etc.

[0061] "Softening point of the resin component" is measured with a ring and ball softening point apparatus for the softening point specified in JIS K 6220-1:2015 7.7, the temperature at which the ball drops.

[0062] The manufacturing sequence of the tire according to an embodiment of the present invention will be described in detail below. Herein, the following description is an example for explaining the present invention, and the main purpose is not to limit the scope of the technology of the present invention to this description scope.

[0063] [Tire] In the tire according to this embodiment, from the viewpoint of the effects of the present invention, the ratio of the tire weight G (kg) to the maximum load capacity W L (kg) (G / W L ) is 0.0160 or less, preferably 0.0155 or less, more preferably 0.0150 or less, further preferably 0.0145 or less, and particularly preferably 0.0140 or less. From the viewpoint of the effects of the present invention, this G / WL There is no particular limitation on the lower limit value. For example, it can be 0.0120 or more, 0.0125 or more, 0.0130 or more. In addition, the tire weight G can be changed by a usual method, that is, the tire weight G can be increased by increasing the tire specific gravity or increasing the thickness of each tire component, or the tire weight G can be decreased in the opposite way.

[0064] From the viewpoint of better exerting the effects of the present invention, the maximum load capacity W L (kg) is preferably 300 or more, more preferably 400 or more, further preferably 450 or more, and particularly preferably 500 or more. In addition, from the viewpoint of better exerting the effects of the present invention, the maximum load capacity W L (kg) can be, for example, 1300 or less, 1200 or less, 1100 or less, 1000 or less, 900 or less, 800 or less, 700 or less. In addition, the maximum load capacity W can be increased by increasing the imaginary volume V of the space occupied by the tire, L or decreased in the opposite way.

[0065] In the tire according to the present embodiment, from the viewpoint of the effects of the present invention, the tire section width Wt (mm) is 200 or more, preferably 205 or more, more preferably 210 or more. In addition, there is no particular limitation from the viewpoint of the effects of the present invention, but Wt is preferably 270 or less, more preferably 260 or less, further preferably 250 or less.

[0066] The ground contact ratio R on the ground contact surface of the tread portion is preferably 0.50 or more, more preferably 0.55 or more, further preferably 0.60 or more. In addition, the ground contact ratio R is preferably 0.85 or less, more preferably 0.80 or less, further preferably 0.75 or less.

[0067] The tread portion according to the present embodiment has at least one rubber layer. The tread portion according to the present embodiment may be a tread portion composed of a single rubber layer, or may be a tread portion having a first layer forming the tread surface and one or more rubber layers (inner rubber layers) existing between the first layer and the belt layer.

[0068] The thickness of the first layer forming the tread surface may be, for example, 30% or more, 50% or more, 70% or more, 90% or more with respect to the overall thickness of the tread portion, or the tread portion may be composed only of the first layer forming the tread surface.

[0069] From the viewpoints of durability and the effects of the present invention, the thickness t1 of the first layer is greater than 3.0 mm, preferably 3.5 mm or more, more preferably 4.0 mm or more, further preferably 4.5 mm or more. In addition, the thickness t1 of the first layer is preferably 12.0 mm or less, more preferably 11.0 mm or less, further preferably 10.0 mm or less.

[0070] From the perspective of the effects of the present invention, the specific gravity of the rubber composition constituting the first layer is preferably 1.270 or less, more preferably 1.260 or less, further preferably 1.250 or less, still further preferably 1.240 or less, and particularly preferably 1.230 or less. On the other hand, in addition, from the perspective of the effects of the present invention, the lower limit value of this specific gravity is not particularly limited, but is preferably 1.150 or more, more preferably 1.160 or more, and further preferably 1.170 or more. The specific gravity can be increased, for example, by increasing the silica content, and conversely, can be decreased by reducing the silica content. In addition, in this specification, the specific gravity of the rubber composition refers to the specific gravity of the vulcanized rubber composition measured based on JIS K 2249-4:2011.

[0071] From the perspective of the effects of the present invention, the 30°C E* of the rubber composition constituting the first layer is greater than 8.0 MPa, preferably greater than 8.2 MPa, more preferably greater than 8.4 MPa, still further preferably greater than 8.6 MPa, and particularly preferably greater than 8.8 MPa. In addition, the 30°C E* of this rubber composition is preferably less than 15.0 M, more preferably less than 14.0 MPa, further preferably less than 13.0 MPa, and particularly preferably less than 12.0 MPa. In addition, the 30°C E* of the rubber composition can be appropriately adjusted by the types and mixing amounts of the rubber components, vulcanized rubber particles, resin components, oils, etc. described later.

[0072] From the perspective of the effects of the present invention, the 30°C tanδ of the rubber composition constituting the first layer is preferably less than 0.25, more preferably less than 0.24, further preferably less than 0.23, still further preferably less than 0.22, and particularly preferably less than 0.21. In addition, the 30°C tanδ of this rubber composition is preferably greater than 0.06, more preferably greater than 0.08, and further preferably greater than 0.10. In addition, the 30°C tanδ of the rubber composition can be appropriately adjusted by the types and mixing amounts of the rubber components, vulcanized rubber particles, resin components, oils, etc. described later.

[0073] From the perspective of the effects of the present invention, the M of the rubber composition constituting the first layer 200 is preferably 4.0 MPa or more, more preferably 5.0 MPa or more, further preferably 6.0 MPa or more, and particularly preferably 7.0 MPa or more. In addition, the M of this rubber composition 200 is preferably 15.0 MPa or less, more preferably 13.0 MPa or less, and further preferably 11.0 MPa or less. In addition, the M of the rubber composition 200 can be appropriately adjusted by the types and mixing amounts of the rubber components, vulcanized rubber particles, resin components, oils, etc. described later.

[0074] The product (R × E* at 30°C) of the ground contact ratio R and the E* (MPa) at 30°C of the rubber composition constituting the first layer is greater than 5.0, preferably 5.2 or more, more preferably greater than 5.4, further preferably greater than 5.6, and particularly preferably greater than 5.8. On the other hand, the upper limit value of R × E* at 30°C is not particularly limited, preferably less than 12.0, more preferably less than 10.0, further preferably less than 9.0 or more, and particularly preferably less than 8.0.

[0075] The ratio (S / E* at 30°C) of the total styrene amount S (mass%) in the rubber component to the E* at 30°C of the rubber composition constituting the first layer is preferably 3.0 or less, more preferably 2.7 or less, further preferably 2.5 or less, and particularly preferably 2.3 or less. In addition, from the viewpoint of the effects of the present invention, the lower limit value of S / E* at 30°C is not particularly limited, but preferably greater than 0, more preferably 0.4 or more, further preferably 0.8 or more, and particularly preferably 1.2 or more.

[0076] The acetone extraction amount of the rubber composition constituting the first layer is preferably 22 mass% or less, more preferably 20 mass% or less, further preferably 18 mass% or less, and particularly preferably 16 mass% or less. In addition, the acetone extraction amount of the rubber composition constituting the first layer is preferably 3 mass% or more, more preferably 4 mass% or more, further preferably 5 mass% or more, and particularly preferably 6 mass% or more.

[0077] The product (R × S) of the ground contact ratio R and the total styrene amount S (mass%) in the rubber component is preferably 20.0 or less, more preferably 18.0 or less, further preferably 15.0 or less, and particularly preferably 14.0 or less. On the other hand, the lower limit value of R × S is not particularly limited, but preferably greater than 0, more preferably 1.0 or more, further preferably 3.0 or more, and particularly preferably 5.0 or more.

[0078] The product (tan δ at 30°C × E* at 30°C × t1) of tan δ at 30°C, E* at 30°C and t1 is preferably less than 12.0, more preferably less than 11.0, further preferably less than 10.0. On the other hand, tan δ at 30°C × E* at 30°C × t1 is preferably greater than 5.0, more preferably greater than 6.0.

[0079] M 200 × E* at 30°C / tan δ at 30°C is preferably 200 or more, more preferably 250 or more, further preferably 300 or more. On the other hand, M 200 × E* at 30°C / tan δ at 30°C has no particular upper limit, but is preferably 800 or less, more preferably 750 or less, further preferably 700 or less.

[0080] [Rubber composition] The tire according to this embodiment can more effectively improve the comprehensive performance of low fuel consumption performance and abrasion resistance performance through the structures of the aforementioned tire and tread portion and the physical properties of the rubber composition constituting the tread portion. Hereinafter, the rubber composition constituting the first layer will be described.

[0081] <Rubber component> For the rubber composition according to this embodiment, as the rubber component, a diene rubber is preferably used. Examples of the diene rubber include isoprene rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene rubber (SIR), styrene-isoprene-butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), etc. These diene rubbers may be modified rubbers obtained by treating with a modifying group capable of interacting with fillers such as carbon black and silica, or may be hydrogenated rubbers obtained by hydrogenating a part of the unsaturated bonds. The diene rubber may be used alone or in combination of two or more. In addition, as the diene rubber, an extended rubber preliminarily extended with a plasticizer described later may also be used.

[0082] The content of the diene rubber in the rubber component is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, and particularly preferably 95% by mass or more. In addition, the rubber component may be composed only of the diene rubber.

[0083] As the diene rubber component, at least one selected from the group consisting of isoprene rubber, styrene-butadiene rubber (SBR), and butadiene rubber (BR) is preferably used. The rubber component preferably contains SBR, more preferably contains SBR and isoprene rubber and / or BR, further preferably contains isoprene rubber, BR, and SBR, and may also be a rubber component composed only of isoprene rubber, SBR, and BR.

[0084] (Isoprene rubber) The isoprene rubber is not particularly limited, and examples thereof include natural rubber (NR), isoprene rubber (IR), and modified natural rubber. Examples of NR include SIR20, RSS#3, TSR20, etc. Examples of IR include IR2200, etc. Examples of the modified natural rubber include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), high-purity natural rubber, grafted natural rubber, etc. These isoprene rubbers may be used alone or in combination of two or more.

[0085] From the perspective of the effects of the present invention, the content of isoprene rubber in the rubber component is preferably 60% by mass or less, more preferably 50% by mass or less, still more preferably 40% by mass or less, and particularly preferably 30% by mass or less. In addition, the lower limit of this content is not particularly limited and can be, for example, 1% by mass or more, 3% by mass or more, 5% by mass or more, 7% by mass or more, 10% by mass or more.

[0086] (BR) There is no particular limitation on the BR, and for example, BR with a cis content of less than 50 mol% (low-cis BR), BR with a cis content of 90 mol% or more (high-cis BR), rare-earth series butadiene rubber synthesized with rare-earth element-based catalysts (rare-earth series BR), BR containing syndiotactic polybutadiene crystals (BR containing SPB), modified BR (high-cis modified BR, low-cis modified BR), etc., which are general products in the tire industry can be used. These BRs can be used alone or in combination of two or more.

[0087] For high-cis BR, for example, products commercially available from Zeon Corporation, Ube Industries, Ltd., JSR Corporation, etc. in Japan can be used. The wear resistance performance can be improved by containing high-cis BR. The cis content of high-cis BR is preferably 95 mol% or more, more preferably 96 mol% or more, still more preferably 97 mol% or more. In addition, the cis content of BR is measured by the said measurement method.

[0088] As the modified BR, a modified butadiene rubber (modified BR) in which the terminal and / or the main chain is modified with a functional group containing at least one element selected from the group consisting of silicon, nitrogen, and oxygen is preferably used.

[0089] As other modified BRs, those obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and further, the terminal of the modified BR molecule is bonded by a tin-carbon bond (tin-modified BR) can be mentioned. In addition, the modified BR can be either an unhydrogenated modified BR or a hydrogenated modified BR.

[0090] From the perspective of wear resistance performance, the weight-average molecular weight (Mw) of BR is preferably 300,000 or more, more preferably 350,000 or more, still more preferably 400,000 or more. In addition, from the perspective of crosslinking uniformity, etc., it is preferably 2,000,000 or less, more preferably 1,000,000 or less. In addition, the Mw of BR is measured by the said measurement method.

[0091] From the perspective of the effects of the present invention, the content of BR in the rubber component is preferably 50% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less, and particularly preferably 25% by mass or less. In addition, the lower limit of this content is not particularly limited. For example, it can be 1% by mass or more, 3% by mass or more, 5% by mass or more, 7% by mass or more, 10% by mass or more.

[0092] (SBR) There is no particular limitation on the SBR. Examples thereof include unmodified solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), and their modified SBR (modified S-SBR, modified E-SBR), etc. As the modified SBR, examples include SBR modified at the terminal and / or main chain, and modified SBR coupled with tin, silicon compounds, etc. (condensates, those having a branched structure, etc.). Further, hydrides of these SBRs (hydrogenated SBR) can also be used. These SBRs can be used alone or in combination of two or more.

[0093] As the SBR involved in this embodiment, extended SBR can be used, or non-extended SBR can also be used. When using extended SBR, the amount of extender for SBR, that is, the content of the extender plasticizer contained in SBR, is preferably 10 to 50 parts by mass relative to 100 parts by mass of the rubber solid component of SBR.

[0094] The listed SBRs can be used alone or in combination of two or more. As the listed SBRs, commercially available products such as those of Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., and ZS Elastomer Co., Ltd. can be used.

[0095] The styrene content of SBR can be appropriately selected so that the total styrene amount S in the rubber component satisfies the range described later, but it is preferably 40% by mass or less, more preferably 37% by mass or less, still more preferably 34% by mass or less, and particularly preferably 30% by mass or less. In addition, the styrene content of SBR is preferably 5% by mass or more, more preferably 7% by mass or more, still more preferably 10% by mass or more, and particularly preferably 12% by mass or more. In addition, the styrene content of SBR is measured by the above-mentioned measurement method.

[0096] From the perspective of ensuring the reactivity with silica and the abrasion resistance performance, the vinyl content of SBR is preferably 5 mol% or more, more preferably 10 mol% or more, still more preferably 15 mol% or more. In addition, from the perspective of the tensile strength at break and the abrasion resistance performance, the vinyl content of SBR is preferably 50 mol% or less, more preferably 40 mol% or less, still more preferably 35 mol% or less. In addition, in this specification, the vinyl content of SBR is measured by the above-mentioned measurement method.

[0097] From the viewpoint of the effects of the present invention, the weight average molecular weight (Mw) of SBR is preferably 100,000 or more, more preferably 200,000 or more, and further preferably 300,000 or more. In addition, from the viewpoint of crosslinking uniformity, the weight average molecular weight is preferably 2,000,000 or less, more preferably 1,800,000 or less, and further preferably 1,500,000 or less. In addition, the weight average molecular weight of SBR is measured by the above-mentioned measurement method.

[0098] The content of SBR in the rubber component can be appropriately selected so that the total styrene amount S in the rubber component satisfies the range described below. Among them, it is preferably 20% by mass or more, more preferably 30% by mass or more, further preferably 40% by mass or more, further preferably 50% by mass or more, and particularly preferably 60% by mass or more. On the other hand, the content of SBR in the rubber component is preferably 99% by mass or less, more preferably 95% by mass or less, further preferably 90% by mass or less, and particularly preferably 85% by mass or less.

[0099] From the viewpoint of the effects of the present invention, the total styrene amount S in the rubber component is preferably 30% by mass or less, more preferably 27% by mass or less, further preferably 25% by mass or less, and particularly preferably 22% by mass or less. In addition, the lower limit value of the total styrene amount S in the rubber component is not particularly limited, and is preferably 1% by mass or more, more preferably 3% by mass or more, further preferably 5% by mass or more, and particularly preferably 7% by mass or more.

[0100] (Other rubber components) Within the range that does not affect the effects of the present invention, the rubber component may contain rubber components other than diene-based rubbers (non-diene-based rubbers). As the non-diene-based rubber, rubber components generally used in the tire industry can be used, and examples thereof include butyl-based rubbers, ethylene propylene rubbers, polynorbornene rubbers, silicone rubbers, chlorinated polyethylene rubbers, fluororubbers (FKM), acrylic rubbers (ACM), and alcohol (Hydrin) rubbers. These other rubber components can be used alone or in combination of two or more. In addition, in addition to the above-mentioned rubber components, known thermoplastic elastomers may or may not be contained.

[0101] (Rubber components synthesized from recycled and biomass-derived raw materials) Monomers that are structural units of synthetic rubbers such as IR, BR, and SBR can be derived from underground resources such as petroleum and natural gas, or can be recovered from rubber products such as tires and non-rubber products such as polystyrene. As monomers obtained by recovery (recovered monomers), there are no particular limitations, and examples include recovered polyisoprene, recovered butadiene, and recovered aromatic vinyl compounds. As the butadiene, 1,2-butadiene and 1,3-butadiene can be mentioned. As the aromatic vinyl compound, there are no particular limitations, and styrene etc. can be mentioned. Among them, it is preferable to use recovered polyisoprene (recovered isoprene), recovered butadiene (recovered butadiene), and recovered styrene (recovered styrene) as raw materials.

[0102] As a method for manufacturing the recovered monomer, there are no particular limitations, and examples include synthesis from recovered naphtha obtained by decomposing rubber products such as tires. In addition, as a method for manufacturing the recovered naphtha, there are no particular limitations. For example, rubber products such as tires can be decomposed under high temperature and high pressure, or decomposed by microwave, or mechanically pulverized and then extracted.

[0103] Furthermore, monomers that are structural units of synthetic rubbers such as IR, BR, and SBR can be monomers derived from biomass. In this specification, biomass refers to substances from natural resources such as plants. There are no particular limitations for biomass, and examples include agricultural, forestry, and fishery products, sugars, wood chips, plant residues after obtaining useful components, ethanol from plants, biomass naphtha, etc.

[0104] As monomers derived from biomass (biomass monomers), there are no particular limitations, and examples include butadiene derived from biomass and aromatic vinyl compounds derived from biomass. As the butadiene, 1,2-butadiene and 1,3-butadiene can be mentioned. As the aromatic vinyl compound, there are no particular limitations, and styrene etc. can be mentioned. In addition, there are no particular limitations for the method for manufacturing biomass monomers, and examples include products based on biological and / or chemical and / or physical transformations of animals and plants. As biological transformation, fermentation by microorganisms is representative, and as chemical and / or physical transformation, products based on catalysts, products based on high heat, products based on high pressure, products based on electromagnetic waves, products based on supercritical fluids, and combinations thereof can be mentioned.

[0105] The polymer synthesized from the biomass monomer component (biomass polymer) is not particularly limited, and examples thereof include polybutadiene rubber synthesized from butadiene from biomass, aromatic vinyl / butadiene copolymers synthesized from butadiene from biomass and / or aromatic vinyl compounds from biomass, etc. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from butadiene from biomass and / or styrene from biomass, etc.

[0106] Whether the raw material of a polymer is derived from biomass can be determined by pMC (percent Modern Carbon) measured in accordance with ASTM D6866-10.

[0107] pMC refers to the 14 C concentration and modern standard reference 14 The ratio of C concentration is a value used as an index to indicate the biomass ratio of a compound. The meaning of this value is as follows.

[0108] 1 mole of carbon atoms (6.02×10 23 There are about one trillionth of the usual carbon atoms, or about 6.02×10 11 indivual 14 C. 14 The half-life of C is 5730 years. 14 C will decrease regularly. It takes 226,000 years for all of them to disintegrate. Therefore, it is believed that after more than 226,000 years, the carbon dioxide in the atmosphere is taken in and fixed by plants, etc., and the carbon dioxide contained in them is fixed in fossil fuels such as coal, oil, and natural gas. 14 The C element is completely disintegrated. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas do not contain any 14 Therefore, the chemicals produced from these fossil fuels do not contain any 14 C element.

[0109] on the other hand, 14 C is continuously generated by nuclear reactions in the atmosphere through cosmic rays. 14 The reduction caused by the radioactive decay of C and the generation caused by nuclear reactions are balanced. In the Earth's atmosphere, 14 Therefore, in the current environment, the amount of substances from biomass resources in the material cycle is 14 As mentioned above, the C concentration is about 1×10 -12 Therefore, the biomass ratio in a certain compound can be calculated by using the difference between these values.

[0110] Should 14 C is generally determined as follows. Using tandem accelerator-based accelerator mass spectrometry, 13 C concentration ( 13 C / 12 C), 14 C concentration ( 14 C / 12 C) determination. In the determination, as 14 The modern standard reference for the concentration of C is based on the concentration of circulating carbon in nature at the time of 1950. 14 C concentration. As a specific standard substance, an oxalic acid standard provided by NIST (National Institute of Standards and Technology) was used. The specific radioactivity of carbon in the oxalic acid (the radioactivity of carbon per gram) was calculated. 14 C radioactivity intensity), for each carbon isotope, 13 C is corrected to a certain value, which is based on the value of attenuation correction implemented from 1950 to the measurement date. 14 The value of C concentration (100%) is used. The ratio of this value to the value of the sample actually measured is the pMC value.

[0111] Therefore, if rubber is made of 100% biomass-derived materials, although there are regional differences, under normal conditions, many are not 100, and show a value of about 110 pMC. On the other hand, for chemical substances derived from fossil fuels such as petroleum, the measurement of this 14 When the concentration of C is 0 pMC, it shows a value of about 0 pMC (for example, 0.3 pMC). As described above, this value corresponds to a biomass ratio of 0%.

[0112] As described above, it is suitable from the perspective of environmental protection to use a material such as rubber having a high pMC value, that is, a material such as rubber having a high biomass ratio, for a rubber composition.

[0113] <Packing> The rubber composition according to the present embodiment contains a filler. The filler according to the present embodiment preferably contains silica, more preferably contains carbon black and silica, and may be a filler consisting only of carbon black and silica.

[0114] (Silicon Dioxide) As the silica, there is no particular limitation, and for example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrous silica), etc., which are generally used in the tire industry, can be used. As the raw material of silica, there is no particular limitation. For example, it can be a raw material from minerals such as quartz, a raw material from organisms such as rice husks (for example, silica based on biomass materials such as rice husks, etc.), or silica recovered from products containing silica. Among them, due to the reason of having many silanol groups, hydrous silica prepared by a wet method is preferred. These silicas can be used alone or in combination of two or more.

[0115] Silica based on biomass materials can be obtained, for example, as follows. From rice husk ash obtained by burning rice husks, silicate is extracted with sodium hydroxide solution, and this silicate is reacted with sulfuric acid in the same way as conventional wet silica, and the resulting silica precipitate is filtered, washed with water, dried, and pulverized.

[0116] As the silica recovered from products containing silica, for example, silica recovered from electronic components such as semiconductors, tires, desiccants, filter materials such as diatomaceous earth, etc., can be used. In addition, as the recovery method, there is no particular limitation, and thermal decomposition, decomposition based on electromagnetic waves, etc. can be cited. Among them, silica recovered from electronic components such as semiconductors or tires is preferred.

[0117] If silica crystallizes, it is insoluble in water and the silicic acid as its component cannot be utilized. By controlling the combustion temperature and combustion time, the crystallization of silica in rice husk ash can be suppressed (refer to JP-A-2009-2594, Akita Prefectural University Internet Journal B / 2019, vol.6, p.216 - 222, etc.).

[0118] Amorphous silica extracted from rice husks can be commercially available products from companies such as Wilmar.

[0119] From the viewpoint of ensuring reinforcement and attenuation of the tread portion, the nitrogen adsorption specific surface area (N2SA) of silica is preferably 110 m 2 / g or more, more preferably 140 m 2 / g or more, further preferably 170 m 2 / g or more, particularly preferably 200 m 2 / g or more. In addition, from the viewpoints of heat generation and processability, it is preferably 350 m 2 / g or less, more preferably 300 m 2 / g or less, further preferably 250 m 2 / g or less. In addition, the N2SA of silica is measured by the above-mentioned measurement method.

[0120] From the viewpoints of increasing the specific surface area of silica, enhancing the interaction with rubber components, suppressing the movement of molecular chains, and suppressing heat generation, the average primary particle size of silica is preferably 20 nm or less, more preferably 18 nm or less, and still more preferably 16 nm or less. The lower limit value of this average primary particle size is not particularly limited, but from the viewpoint of the dispersibility of silica, it is preferably 1 nm or more, more preferably 3 nm or more, and still more preferably 5 nm or more. In addition, the average primary particle size of silica is measured by the above-mentioned measurement method.

[0121] From the viewpoints of ensuring reinforcement and attenuation properties of the tread portion, the content of silica relative to 100 parts by mass of the rubber component is preferably 40 parts by mass or more, more preferably 55 parts by mass or more, still more preferably 70 parts by mass or more, and particularly preferably 80 parts by mass or more. In addition, from the viewpoints of reducing the rubber specific gravity and achieving weight reduction, it is preferably 140 parts by mass or less, more preferably 120 parts by mass or less, still more preferably 100 parts by mass or less, and particularly preferably 95 parts by mass or less.

[0122] (Carbon black) There is no particular limitation on the carbon black, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The carbon black raw material can be a biomass material such as lignin or vegetable oil, or can be a pyrolysis oil obtained by thermally decomposing waste tires. In addition, the manufacturing method of carbon black can be a manufacturing method based on combustion such as the furnace method, or can be a manufacturing method based on hydrothermal carbonization (HTC), or can be a manufacturing method based on the thermal decomposition of methane generated by the thermal black method, etc. As commercially available products, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., Columbian Carbon Company, etc. can be used. These carbon blacks can be used alone or in combination of two or more.

[0123] In addition, as carbon black, in addition to the above, from the viewpoints such as life cycle assessment, carbon black using biomass materials such as lignin and vegetable oil as raw materials, and recycled carbon black obtained by thermally decomposing and purifying products containing carbon black such as tires can be used.

[0124] In this specification, "recycled carbon black" refers to carbon black obtained by pulverizing used products such as tires containing carbon black and firing the pulverized product. According to the thermogravimetric measurement method based on JIS K 6226-2:2003, when oxidized and burned in air, the proportion of the non-combustible component, that is, the mass of ash (ash content), is 13% by mass or more. That is, the proportion of the mass (carbon content) of the reduced amount caused by the oxidation combustion of the recycled carbon black is 87% by mass or less. Recycled carbon black can also be represented by rCB.

[0125] Recycled carbon black can be obtained from the thermal decomposition process of used pneumatic tires. For example, as mentioned in the specification of European Patent Application Publication No. 3427975, in "Rubber Chemistry and Technology", Vol. 85, No. 3, pages 408 - 449 (2012), especially pages 438, 440, 442, it is described that carbon black is obtained by thermal decomposition of organic materials at 550 - 800 °C with oxygen excluded, or vacuum thermal decomposition at a lower temperature (

[0027] ). The carbon black obtained by such a thermal decomposition process, as mentioned in

[0004] of Patent No. 6856781, generally lacks functional groups on its surface (Comparison of the surface morphology and chemistry of thermal decomposition carbon black and commercially available carbon black, Powder Technology 160 (2005) 190 - 193).

[0126] The surface of recycled carbon black may lack functional groups, or it can also be treated so that its surface contains functional groups. The treatment in such a way that the surface of recycled carbon black contains functional groups can be carried out by ordinary methods. For example, in the specification of European Patent Application Publication No. 3173251, carbon black obtained from the thermal decomposition process is treated with potassium permanganate under acidic conditions to obtain carbon black with hydroxyl and / or carboxyl groups on its surface. In addition, in the publication of Patent No. 6856781, carbon black obtained from the thermal decomposition process is treated with an amino acid compound containing at least one mercapto group or disulfide group to obtain surface-activated carbon black. The recycled carbon black involved in this embodiment includes carbon black treated so that its surface contains functional groups.

[0127] Commercially available carbon black such as that from Strable Green Carbon Company and LDCarbon Company can be used as recycled carbon black.

[0128] From the viewpoints of weather resistance and reinforcement, the nitrogen adsorption specific surface area (N2SA) of carbon black is preferably 50 m 2 / g or more, more preferably 80 m 2 / g or more, and further preferably 100 m 2 / g or more. In addition, from the viewpoints of dispersibility, low fuel consumption performance, fracture characteristics, and durability performance, it is preferably 250 m 2 / g or less, more preferably 220 m 2 / g or less. In addition, the N2SA of carbon black is measured by the said measurement method.

[0129] From the viewpoints of weather resistance and reinforcement, the content based on 100 parts by mass of the rubber component when carbon black is included is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more. In addition, from the viewpoint of low fuel consumption performance, it is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, further preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less.

[0130] (Other fillers) Fillers other than silica and carbon black are not particularly limited. For example, aluminum hydroxide, alumina (aluminum oxide), calcium carbonate, magnesium sulfate, talc, clay, biochar, etc. can be mixed with products generally used in the conventional tire industry. These other fillers can be used alone or in combination of two or more.

[0131] The ratio of the carbon black content to the silica content is preferably 0.40 or less, more preferably 0.30 or less, further preferably 0.21 or less, further preferably 0.17 or less, further preferably 0.13 or less, and particularly preferably 0.10 or less. By making the ratio of the carbon black content to the silica content within the above range, the low fuel consumption performance can be further improved. On the other hand, the lower limit value of the ratio of the carbon black content to the silica content is not particularly limited. For example, it can be 0.01 or more, 0.02 or more, 0.05 or more, or it can be a filler without carbon black.

[0132] From the viewpoints of ensuring reinforcement and attenuation of the tread portion, the total content of the fillers based on 100 parts by mass of the rubber component is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, further preferably 70 parts by mass or more, and particularly preferably 80 parts by mass or more. From the viewpoint of the effects of the present invention, it is preferably 140 parts by mass or less, more preferably 120 parts by mass or less, further preferably 100 parts by mass or less, and particularly preferably 95 parts by mass or less.

[0133] (Silane coupling agent) Silica is preferably used in combination with a silane coupling agent. There is no particular limitation on the silane coupling agent. In the tire industry, any silane coupling agent used in combination with silica in the past can be used. From the point of better obtaining the desired effects, it is preferably one or more silane coupling agents selected from the group consisting of sulfide-based silane coupling agents and mercapto-based silane coupling agents, and more preferably mercapto-based silane coupling agents.

[0134] Examples of the sulfide-based silane coupling agent include bis(3-triethoxysilylpropyl) disulfide, bis(3-triethoxysilylpropyl) tetrasulfide, etc. These sulfide-based silane coupling agents can be used alone or in combination of two or more.

[0135] In this specification, the mercapto-based silane coupling agent refers to a silane coupling agent having a mercapto group and a silane coupling agent having a structure in which the mercapto group is protected by a protecting group. There is no particular limitation on the mercapto-based silane coupling agent, and examples thereof include a compound having a mercapto group represented by the following formula (2), a compound in which the mercapto group is protected by an ester represented by the following formula (3), and a compound containing a bonding unit A represented by the following formula (4) and / or a bonding unit B represented by the following formula (5). Among them, for the reason that the effects of the present invention can be better exerted, the compound represented by the following formula (3) or a compound containing a bonding unit A represented by the following formula (4) and / or a bonding unit B represented by the following formula (5) is preferred, and the compound represented by the following formula (3) is more preferred. These mercapto-based silane coupling agents can be used alone or in combination of two or more.

Chemical 1

Chemical 2

Chemical 3

Chemical 4

[0136] Examples of the compound represented by the formula (2) include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, a compound represented by the following formula (6) (Si363 manufactured by Evonik Degussa GmbH), etc., and the compound represented by the following formula (6) can be appropriately used. They can be used alone or in combination of two or more.

Chemical 5

[0137] Examples of the compound represented by the formula (3) include 3-octanoylthio-1-propyltriethoxysilane, 3-hexanoylthio-1-propyltriethoxysilane, 3-octanoylthio-1-propyltrimethoxysilane, etc.

[0138] It is considered that a compound containing the bonding unit A represented by formula (4) and / or the bonding unit B represented by formula (5) inhibits the increase in viscosity during processing as compared with a sulfur-based silane coupling agent such as bis-(3-triethoxysilylpropyl)tetrasulfide. Therefore, the dispersibility of silica is better, and the low fuel consumption performance, wet grip performance, and tensile strength at break are further improved. It is considered that this is because the sulfur part of the bonding unit A is a C-S-C bond, which is thermally stable compared with tetrasulfide and disulfide, and thus the increase in Mooney viscosity is small.

[0139] From the viewpoint of suppressing the increase in viscosity during processing, the content of the bonding unit A is preferably 30 to 99 mol%, more preferably 50 to 90 mol%. In addition, the content of the bonding unit B is preferably 1 to 70 mol%, more preferably 5 to 65 mol%, and further preferably 10 to 55 mol%. In addition, the total content of the bonding units A and B is preferably 95 mol% or more, more preferably 98 mol% or more, and particularly preferably 100 mol%. In addition, the contents of the bonding units A and B also include the amounts when the bonding units A and B are located at the ends of the silane coupling agent. The form when the bonding units A and B are located at the ends of the silane coupling agent is not particularly limited, and units corresponding to formulas (4) and (5) representing the bonding units A and B may be formed.

[0140] In the compound containing the bonding unit A represented by formula (4) and the bonding unit B represented by formula (5), the total number of repetitions (x + y) of the repetition number (x) of the bonding unit A and the repetition number (y) of the bonding unit B is preferably in the range of 3 to 300. If it is within this range, due to the -C7H of the bonding unit A 15 The mercapto silane covering the bonding unit B can inhibit the shortening of the coking time and ensure good reactivity with silica and the rubber component.

[0141] Examples of the compound containing the bonding unit A represented by formula (4) and / or the bonding unit B represented by formula (5) include NXT-Z30, NXT-Z45, NXT-Z60, NXT-Z100, etc. manufactured by Momentive. These can be used alone or in combination of two or more.

[0142] As the silane coupling agent other than the sulfide-based silane coupling agent and the mercapto-based silane coupling agent, there is no particular limitation, and examples thereof include vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silane coupling agents such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-(2-aminoethyl)aminopropyltriethoxysilane; glycidoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane; and the like. These other silane coupling agents may be used alone or in combination of two or more. As the silane coupling agents listed above, for example, silane coupling agents manufactured and sold by Momentive Performance Materials Inc., Evonik Degussa GmbH, etc. may be used.

[0143] From the viewpoint of improving the dispersibility of silica, the content of the silane coupling agent relative to 100 parts by mass of silica is preferably 1.0 part by mass or more, more preferably 3.0 part by mass or more, and still more preferably 5.0 part by mass or more. In addition, from the viewpoints of cost and processability, it is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and still more preferably 12 parts by mass or less.

[0144] <Other Blending Agents> The rubber composition according to the present embodiment may appropriately contain blending agents generally used in the tire industry in the past, such as plasticizers, vulcanized rubber particles, processing aids, waxes, anti-aging agents, stearic acid, zinc oxide, vulcanizing agents, vulcanization accelerators, etc., in addition to the above components.

[0145] The plasticizer refers to a material that imparts plasticity to the rubber component, and is a concept including both plasticizers that are liquid at 25°C and plasticizers that are solid at room temperature (25°C). Examples of the plasticizer include resin components, oils, liquid rubbers, ester-based plasticizers, etc. These plasticizers may be derived from mineral resources such as petroleum and natural gas, may be derived from biomass, or may be derived from naphtha recovered from rubber products and non-rubber products. In addition, low-molecular-weight hydrocarbon components obtained by thermally decomposing and extracting products containing used tires and various components may also be used as plasticizers. These plasticizers may be used alone or in combination of two or more.

[0146] (Resin Component) As the resin component, there is no particular limitation as long as it is a resin component commonly used in the tire industry. Examples thereof include tackifying resins such as dicyclopentadiene-based resins, aromatic vinyl resins, C9-based resins, C5-based resins, C5C9-based resins, terpene-based resins, rosin-based resins, and phenol-based resins. These resin components can be used alone or in combination of two or more.

[0147] The "dicyclopentadiene-based resin" means a resin containing cyclopentadiene (CPD) or dicyclopentadiene (DCPD) as a monomer component, and may also be a hydride or modified product thereof. Examples of the dicyclopentadiene-based resin include DCPD / C9 resins containing dicyclopentadiene and the C9 fraction described below as monomer components (this DCPD / C9 resin may also be a resin obtained by hydrogenating it or a resin obtained by modifying it), and preferably a DCPD / C9 resin containing dicyclopentadiene and styrene as monomer components. As the dicyclopentadiene-based resin, for example, resins commercially available from ExxonMobil Corporation, ENEOS Corporation, Zeon Corporation, Maruzen Petrochemical Co., Ltd., etc. can be used. These dicyclopentadiene-based resins can be used alone or in combination of two or more.

[0148] The "aromatic vinyl-based resin" means a resin containing an aromatic vinyl compound such as styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene, etc. as the monomer component with the largest content, and may also be a resin obtained by hydrogenating it or a resin obtained by modifying it. As the aromatic vinyl-based resin, for reasons of economy, ease of processing, and excellent heat generation properties, a homopolymer of α-methylstyrene or styrene or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred. As the aromatic vinyl-based resin, for example, those commercially available from CLAYTON Company, Eastman Chemical Company, Mitsui Chemicals, Inc., etc. can be used. These aromatic vinyl-based resins can be used alone or in combination of two or more.

[0149] The "C9-based resin" means a resin obtained by polymerizing the C9 fraction, and may be a resin obtained by homopolymerizing the C9 fraction or a polymer obtained by copolymerizing the C9 fraction and other components. For example, a resin obtained by copolymerizing dicyclopentadiene (DCPD) and the C9 fraction is called a DCPD / C9 resin. In addition, it may also be a resin obtained by hydrogenating it or a resin obtained by modifying it. Examples of the C9 fraction include petroleum fractions having 8 to 10 carbon atoms such as vinyltoluene, alkylstyrene, coumarone, indene, methylindene, and dicyclopentadiene. These C9-based resins can be used alone or in combination of two or more.

[0150] "C5 resin" refers to a resin obtained by polymerizing C5 fractions, or a resin obtained by hydrogenating it or modifying it. Examples of C5 fractions include petroleum fractions with 4 to 5 carbon atoms such as cyclopentadiene, isoprene, pentane, isopentane, neopentane, pentene, and pentadiene. These C5 resins can be used alone or in combination of two or more.

[0151] "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, or a resin obtained by hydrogenating it or modifying it. As C5C9 petroleum resins, commercially available resins such as those from Tosoh Corporation and LUHUA Company can be used. These C5C9 resins can be used alone or in combination of two or more.

[0152] "Terpene resin" refers to a resin containing terpene compounds such as α-pinene, β-pinene, limonene, and dipentene as the monomer component with the highest content, or a hydride obtained by hydrogenating it or a modified product obtained by modifying it. Specific examples of terpene resins include polyterpene resins containing only one or more of the above terpene compounds as monomer components; aromatic modified terpene resins containing the terpene compounds and aromatic compounds as monomer components; terpene phenol resins containing the terpene compounds and phenolic compounds as monomer components, etc. Examples of aromatic compounds as monomer components of aromatic modified terpene resins include styrene, α-methylstyrene, vinyltoluene, divinyltoluene, etc. Examples of phenolic compounds as monomer components of terpene phenol resins include phenol, bisphenol A, cresol, xylenol, etc. These terpene resins can be used alone or in combination of two or more.

[0153] "Rosin resin" refers to a resin containing rosin acid compounds such as rosin acid, neoabietic acid, palustric acid, and isopimaric acid, or a hydride obtained by hydrogenating it or a modified product obtained by modifying it. There is no particular limitation on rosin resins, and examples include natural resin rosin, rosin modified resins obtained by modifying it such as hydrogenation, disproportionation, dimerization, and esterification. These rosin resins can be used alone or in combination of two or more.

[0154] "Phenolic resin" refers to a resin containing phenolic compounds such as phenol and cresol as the monomer component with the highest content. There is no particular limitation on phenolic resins, and examples include phenol formaldehyde resin, alkylphenol formaldehyde resin, alkylphenol acetylene resin, oil-modified phenol formaldehyde resin, etc. These phenolic resins can be used alone or in combination of two or more.

[0155] From the perspective of grip performance, the softening point of the resin component is preferably 60 °C or higher, more preferably 70 °C or higher, and still more preferably 80 °C or higher. Further, from the perspective of improving processability and the dispersibility of the rubber component and filler, it is preferably 150 °C or lower, more preferably 140 °C or lower, and still more preferably 130 °C or lower. In addition, the softening point of the resin component is measured by the above-mentioned measurement method.

[0156] When a resin component is included, the content of the resin component relative to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more. Further, from the perspective of suppressing heat generation, it is preferably 60 parts by mass or lower, more preferably 50 parts by mass or lower, still more preferably 40 parts by mass or lower, and particularly preferably 30 parts by mass or lower.

[0157] (Oil) Examples of the oil include mineral oil, vegetable oil, animal oil, etc. Further, from the perspective of life cycle assessment, waste oil used in a rubber mixer or an engine and waste cooking oil used in a restaurant can be purified and used.

[0158] In this specification, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of the mineral oil include paraffin-based oil (mineral oil), naphthenic oil, aromatic oil, etc. Specific examples of the mineral oil include, for example, MES (mild extraction solvate), DAE (distilled aromatic extract), TDAE (treated distilled aromatic extract), TRAE (treated residual aromatic extract), RAE (residual aromatic extract), etc. Further, under environmental measures, oil with a low content of polycyclic aromatic compounds (PCA) can be used. Examples of the low-PCA-content oil include MES, TDAE, and heavy naphthenic oil.

[0159] In this specification, "vegetable oil" refers to, 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, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grape seed oil, wood wax, etc. Further, examples of the vegetable oil include refined oil (such as salad oil) obtained by refining the above-mentioned oil, transesterified oil obtained by transesterifying the above-mentioned oil, hydrogenated oil obtained by hydrogenating the above-mentioned oil, thermally polymerized oil obtained by thermally polymerizing the above-mentioned oil, oxidatively polymerized oil obtained by oxidizing the above-mentioned oil, and waste cooking oil obtained by recovering oil used as cooking oil, etc. In addition, the vegetable oil can be liquid or solid at normal temperature (25 °C). These vegetable oils can be used alone or in combination of two or more.

[0160] The vegetable oil involved in this embodiment preferably contains acylglycerol, and more preferably contains triacylglycerol. In addition, in this specification, acylglycerol refers to a compound in which the hydroxyl group carried by glycerol and a fatty acid are ester-bonded. As the acylglycerol, there is no particular limitation, and it can be any one of 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, and triacylglycerol. Further, the acylglycerol can be a monomer, a dimer, or a polymer of three or more monomers. In addition, acylglycerols of two or more monomers can be obtained by thermal polymerization, oxidative polymerization, etc. In addition, acylglycerol can be a liquid or a solid at normal temperature (25 °C).

[0161] As a method for confirming the presence of the acylglycerol in the rubber composition, there is no particular limitation. For example, it can be confirmed by the following 1 1H-NMR measurement. Specifically, the rubber composition mixed with triacylglycerol is immersed in deuterated chloroform at normal temperature (25 °C) for 24 hours. After removing the rubber composition, 1H-NMR measurement is carried out at room temperature. 1 When the signal of tetramethylsilane (TMS) is 0.00 ppm in the 1H-NMR measurement, signals around 5.26 ppm, around 4.28 ppm, and around 4.15 ppm are observed, and it is presumed that these signals are from the hydrogen atoms bonded to the carbon atoms adjacent to the oxygen atom of the ester group. In addition, "around" in this paragraph means a range of ±0.10 ppm.

[0162] The fatty acid is not particularly limited and can be an unsaturated fatty acid or a saturated fatty acid. As the unsaturated fatty acid, examples include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. In addition, as the saturated fatty acid, examples include butyric acid and lauric acid.

[0163] Among them, as the fatty acid, it is desirable to contain fatty acids with fewer double bonds, that is, saturated fatty acids or monounsaturated fatty acids, and preferably oleic acid. As the vegetable oil containing such fatty acids, for example, vegetable oils containing saturated fatty acids or monounsaturated fatty acids can be used, or modified vegetable oils such as those obtained by transesterification can also be used. In addition, in order to produce vegetable oils containing such fatty acids, plants can be improved by variety improvement, genetic recombination, etc.

[0164] As the vegetable oil, for example, those commercially available from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Olisoy Co., H&R Co., Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0165] As the animal oil, fish oil, beef tallow, or oil alcohols derived from them can be cited.

[0166] The content of unsaturated fatty acids in the constituent fatty acids of vegetable oil is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, still more preferably 75% by mass or more, still more preferably 80% by mass or more, and particularly preferably 85% by mass or more.

[0167] When vegetable oil is contained, from the viewpoint of processability, the content of vegetable oil relative to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more. Further, from the viewpoint of rubber hardness, it is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, still more preferably 30 parts by mass or less.

[0168] From the viewpoint of processability, the content of oil relative to 100 parts by mass of the rubber component (the total amount when multiple oils are used in combination) is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more. Further, from the viewpoint of rubber hardness, it is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, still more preferably 30 parts by mass or less.

[0169] The liquid rubber is not particularly limited as long as it is a polymer in a liquid state at normal temperature (25°C). Examples thereof include liquid butadiene rubber (liquid BR), liquid styrene-butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene-isoprene rubber (liquid SIR), and liquid farnesene rubber. These liquid rubbers can be used alone or in combination of two or more.

[0170] Examples of the ester plasticizer include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di(2-ethylhexyl) azelate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), di(undecyl) 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), and tris(xylene) phosphate (TXP). These ester plasticizers can be used alone or in combination of two or more.

[0171] The content of the plasticizer relative to 100 parts by mass of the rubber component (the total combined amount when multiple plasticizers are used) is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, further preferably 30 parts by mass or more, and particularly preferably 35 parts by mass or more. In addition, the content is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, further preferably 60 parts by mass or less, and particularly preferably 50 parts by mass or less.

[0172] The vulcanized rubber particles are particles made of vulcanized rubber. Specifically, rubber powder specified in JIS K 6316:2017 can be used, etc. From the viewpoints of environmental consideration and cost, recycled rubber powder made from crushed waste tires, etc. is preferred. These can be used alone or in combination of two or more.

[0173] There is no particular limitation on the vulcanized rubber particles, which can be unmodified vulcanized rubber particles or modified vulcanized rubber particles. As commercially available products of vulcanized rubber, products of, for example, Lehigh Company, Murakami Rubber Industry Co., Ltd. can be used.

[0174] When the vulcanized rubber particles are contained, the content of the vulcanized rubber particles relative to 100 parts by mass of the rubber component can be appropriately adjusted, for example, in the range greater than 1 part by mass and less than 80 parts by mass.

[0175] Examples of the processing aid include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, fatty acid esters, mixtures of fatty acid metal salts and amide esters, mixtures of fatty acid metal salts and fatty acid amides, etc. As the processing aid, products commercially available from companies such as Schill+Seilacher Company, Performance Additives can be used. These processing aids can be used alone or in combination of two or more.

[0176] When the processing aid is contained, the content relative to 100 parts by mass of the rubber component, from the viewpoint of exerting the improvement effect of processability, is preferably greater than 0.5 part by mass, more preferably greater than 1 part by mass, and further preferably greater than 1.5 parts by mass. In addition, from the viewpoints of abrasion resistance and breaking strength, it is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and further preferably less than 5.0 parts by mass.

[0177] As for the wax, there is no particular limitation, and any one commonly used in the tire industry can be appropriately used. Examples include mineral waxes and waxes derived from plants. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Waxes derived from plants refer to waxes derived from natural resources such as plants. Among them, mineral waxes are preferred. Examples of waxes derived from plants include rice wax, carnauba wax, candelilla wax, etc. Examples of mineral waxes include paraffin wax, microcrystalline wax, and their selected special waxes, with paraffin wax being preferred. In addition, the wax involved in this embodiment does not contain stearic acid. The wax can be a commercially available wax from, for example, Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., PARAMELT Corporation, etc. These waxes can be used alone or in combination of two or more.

[0178] From the perspective of the weather resistance of the rubber, the content of the wax relative to 100 parts by mass of the rubber component when containing wax is preferably 0.5 part by mass or more, more preferably 1.0 part by mass or more, and further preferably 1.5 part by mass or more. In addition, from the perspective of preventing the whitening of the tire caused by blooming, it is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less.

[0179] There is no particular limitation on the antioxidant, and examples include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine-based antioxidants 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'-dimethylxyl-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), N,N'-di-2-naphthyl-p-phenylenediamine (DNPD), etc.; quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; bisphenol, triphenol, polyphenol-based antioxidants such as tetrakis[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, etc. Among them, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline polymer are more preferred. As commercially available products, products from, for example, Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis Co., Ltd., etc. can be used. These antioxidants can be used alone or in combination of two or more.

[0180] From the perspective of ozone crack resistance of rubber, the content of the anti-aging agent relative to 100 parts by mass of the rubber component when containing the anti-aging agent is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and further preferably 1.5 parts by mass or more. In addition, from the perspectives of abrasion resistance and wet grip performance, it is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less.

[0181] From the perspective of processability, the content of stearic acid relative to 100 parts by mass of the rubber component when containing stearic acid is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and further preferably 1.5 parts by mass or more. In addition, from the perspective of vulcanization rate, it is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less.

[0182] From the perspective of processability, the content of zinc oxide relative to 100 parts by mass of the rubber component when containing zinc oxide is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and further preferably 1.5 parts by mass or more. In addition, from the perspective of abrasion resistance, it is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less.

[0183] As the vulcanizing agent, sulfur is preferably used. As sulfur, powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, etc. can be used.

[0184] From the perspective of ensuring sufficient vulcanization reaction, the content of sulfur relative to 100 parts by mass of the rubber component when containing sulfur as the vulcanizing agent is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and further preferably 1.0 parts by mass or more. In addition, from the perspective of deterioration prevention, it is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and further preferably 3.5 parts by mass or less. In addition, when using oil-containing sulfur as the vulcanizing agent, the content of the vulcanizing agent is the total content of the pure sulfur component contained in the oil-containing sulfur.

[0185] Examples of vulcanizing agents other than sulfur include alkylphenol / sulfur chloride condensate, 1,6-hexamethylene-dithiocarbamate disodium salt dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyl disulfide) hexane, etc. These vulcanizing agents other than sulfur can be commercially available vulcanizing agents from companies such as Tago Chemical Industry Co., Ltd., Lanxess Co., Ltd., and Flexis Co., Ltd.

[0186] Examples of the vulcanization accelerator include sulfenamide vulcanization accelerators, thiazole vulcanization accelerators, guanidine vulcanization accelerators, thiuram vulcanization accelerators, dithiocarbamate vulcanization accelerators, caprolactam disulfide, and the like. These vulcanization accelerators can be used alone or in combination of two or more. Among them, based on the point of better obtaining the desired effect, one or more vulcanization accelerators selected from the group consisting of sulfenamide vulcanization accelerators, thiazole vulcanization accelerators, and guanidine vulcanization accelerators are preferred, and it is more preferred to use a combination of sulfenamide vulcanization accelerators and guanidine vulcanization accelerators.

[0187] Examples of the sulfenamide vulcanization accelerator include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N,N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS), and the like. Among them, TBBS and CBS are preferred.

[0188] Examples of the thiazole vulcanization accelerator include 2-mercaptobenzothiazole (MBT) or its salt, bis-2-benzothiazolyl disulfide (MBTS), 2-(2,4-dinitrophenyl)mercaptobenzothiazole, 2-(2,6-diethyl-4-morpholinothio)benzothiazole, and the like. Among them, MBTS and MBT are preferred, and MBTS is more preferred.

[0189] Examples of the guanidine vulcanization accelerator include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of di-catechol borate, 1,3-di-o-isopropylphenylguanidine, 1,3-di-o-phenylguanidine, 1,3-di-o-isopropylphenyl-2-propionylguanidine, and the like. Among them, DPG is preferred.

[0190] When the vulcanization accelerator is contained, the content of the vulcanization accelerator relative to 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1.0 part by mass or more, and further preferably 1.5 part by mass or more. In addition, the content of the vulcanization accelerator relative to 100 parts by mass of the rubber component is preferably 8.0 parts by mass or less, more preferably 6.0 parts by mass or less, and further preferably 4.0 parts by mass or less. By making the content of the vulcanization accelerator within the above range, it tends to ensure the breaking strength and elongation.

[0191] [Rubber Composition and Tire Manufacturing] The rubber composition according to the present embodiment can be produced by a known method. For example, it can be produced by kneading the respective components using a rubber kneading device such as an open extruder, a closed kneader (Banbury mixer, extruder, etc.).

[0192] The kneading process includes, for example: a basic kneading process of kneading a mixture and additives other than vulcanizing agents and vulcanization accelerators; a final kneading (F-kneading) process of adding vulcanizing agents and vulcanization accelerators to the kneaded product obtained in the basic kneading process and kneading. Further, the basic kneading process can be divided into multiple processes according to requirements.

[0193] There are no particular restrictions on the kneading conditions. For example, in the basic kneading process, kneading is carried out at a discharge temperature of 150 to 170 °C for 3 to 10 minutes, and in the final kneading process, kneading is carried out at 70 to 110 °C for 1 to 5 minutes. There are no particular restrictions on the vulcanization conditions. For example, a method of vulcanizing at 150 to 200 °C for 10 to 30 minutes can be cited.

[0194] A tire having a tread portion composed of the rubber composition can be manufactured by a conventional method. That is, an unvulcanized rubber composition in which the above components are mixed with the rubber component as needed is extruded according to the shape of the first layer of the tread portion, and is adhered to the inner rubber layer of the tread portion and other tire components on a tire molding machine, and is molded by a conventional method to form an unvulcanized tire. By heating and pressurizing this unvulcanized tire in a vulcanizer, a tire can be manufactured. There are no particular restrictions on the vulcanization conditions. For example, a method of vulcanizing at 150 to 200 °C for 10 to 30 minutes can be cited.

[0195] [Use of the tire] The tire according to this embodiment can be suitably used for passenger car tires, truck / bus tires, two-wheeler tires, and racing tires, and is preferably used for passenger car tires. In addition, a passenger car tire refers to a tire premised on being installed on a four-wheeled vehicle, and its maximum load capacity is 1000 kg or less.

Examples

[0196] The following shows examples (examples) considered to be preferable when implementing, and the scope of the present invention is not limited by the examples. Using the various drugs shown below, tires having the first layer of the tread portion obtained by mixing according to Tables 1 to 4 are investigated, and the results calculated based on the following evaluation methods are shown in Tables 1 to 4.

[0197] The following summarizes the various drugs used in the examples and comparative examples. NR: TSR20 SBR: EUROPRENE (registered trademark) SOL R C2525 manufactured by Versalis (styrene content: 26% by mass, vinyl content: 24% by mass, Mw: 600,000, non-oil extended product) BR: CB24 manufactured by Lanxess AG (BR synthesized with an Nd-based catalyst, cis content: 96 mol%, Mw: 500,000) Carbon black: Show Black N220 manufactured by Cabot Japan Co., Ltd. (N2SA: 111 m 2 / g) Silica 1: ULTRASIL (registered trademark) VN3 manufactured by Evonik Degussa GmbH (N2SA: 175 m 2 / g, average primary particle size: 17 nm) Silica 2: ULTRASIL (registered trademark) 9100GR manufactured by Evonik Degussa GmbH (N2SA: 230 m 2 / g, average primary particle size: 15 nm) Silica 3: Silica derived from rice husk obtained through the following production example (N2SA: 175 m 2 / g, average primary particle size: 18 nm) Silane coupling agent 1: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa GmbH Silane coupling agent 2: NXT-Z45 manufactured by Momentive Performance Materials Inc. (mercapto-based silane coupling agent, copolymer of binding unit A and binding unit B (binding unit A: 55 mol%, binding unit B: 45 mol%)) Oil 1: VivaTec 500 (TDAE oil) manufactured by H&R Oil 2: Sunflower oil manufactured by Nisshin OilliO Group, Ltd. (content of oleic acid contained in constituent fatty acids: 55% by mass, total content of polyunsaturated fatty acids contained in constituent fatty acids: 8% by mass) Resin component: Oppera PR395 (hydrogenated DCPD / C9 resin, softening point: 118°C) manufactured by ExxonMobil Wax: OzoAce 0355 (paraffin wax) of Nippon Seiro Co., Ltd. Antioxidant: Nocrack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. Zinc oxide: Zinc white No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Stearic acid "Tsubaki" manufactured by Yushu Co., Ltd. Sulfur: HK-200-5 (5% oil-containing powdered sulfur) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator: Noxeller CZ (N-cyclohexyl-2-benzothiazolylsulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.

[0198] (Production example of silica 3) Rice husk ash was added to an aqueous sodium hydroxide solution, and the mixture was heated and stirred with a stirring rod. Then, the mixture was allowed to return to room temperature and centrifuged to precipitate the carbon component. The supernatant was filtered through a Kiriyama funnel. Further, after adding water to the precipitate and stirring, it was centrifuged again, and the supernatant was filtered through a Kiriyama funnel. The filtrate was mixed with the previous filtrate. Then, the mixed filtrate was diluted with water to obtain an aqueous sodium silicate solution.

[0199] A portion of the aqueous sodium silicate solution was taken out, diluted with pure water, and then 1 mol / L sulfuric acid was added to adjust the pH to 2 - 4, followed by heating. Then, a portion of the remaining aqueous sodium silicate solution was added thereto to adjust the pH to 8 - 10, and further heated. It was diluted with pure water to obtain a seed solution.

[0200] The seed solution was heated and stirred. Here, while simultaneously dropping the remaining aqueous sodium silicate solution and 1 mol / L sulfuric acid, the pH was adjusted to the range of 8 - 11 while stirring. After the dropping of the aqueous sodium silicate solution was completed, only 1 mol / L sulfuric acid was continuously dropped at the same rate until the dropping was completed at the specified pH (1.5 - 6). The white precipitate formed after the dropping was completed was filtered through a Kiriyama funnel, and the filter cake was washed with water. These steps were repeated once, and the filter cake was dried to obtain silicon dioxide 3.

[0201] (Examples and Comparative Examples) According to the mixing formulas shown in Tables 1 - 4, using a 1.7L closed Banbury mixer, the chemicals other than sulfur and vulcanization accelerators were mixed for 1 - 10 minutes until the discharge temperature reached 150 - 160°C to obtain a mixture. Next, using a two - roll open - type extruder, sulfur and vulcanization accelerators were added to the mixture and mixed for 4 minutes until it reached 105°C to obtain an unvulcanized rubber composition. Using this unvulcanized rubber composition, it was extruded and formed according to the shape of the first layer of the tread surface (thickness: 5.0 mm) using an extruder equipped with a nozzle of a specified shape, and laminated together with the second layer of the tread surface (thickness: 1.0 mm) and other tire components to produce an unvulcanized tire, which was press - vulcanized at 170°C for 12 minutes. Thus, each test tire described in Tables 1 - 4 was obtained.

[0202] <Measurement of 30°C tanδ and 30°C E*> Regarding each vulcanized rubber test piece prepared by cutting out a piece with a length of 20 mm × width of 4 mm × thickness of 1 mm from the inside of the first layer of the tread surface of each test tire, with the tire circumferential direction as the long side and the tire radius direction as the thickness direction, the loss tangent tanδ and the complex elastic modulus E* were measured using a dynamic viscoelasticity measuring device (EPLEXOR series manufactured by GABO) under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of ±1%, and a tensile mode.

[0203] <Tensile Test> Regarding the test pieces of dumbbell No. 7 shape cut with a thickness of 1 mm from the inside of the first layer and the second layer of the tread surface of each test tire, with the circumferential direction of the tire as the tensile direction and the radial direction of the tire as the thickness direction, a tensile test was carried out under the conditions of a temperature of 23 °C and a tensile speed of 3.3 mm / second based on JIS K 6251:2017, and the modulus (M 200 )(MPa) at 200% elongation was measured.

[0204] <Measurement of Acetone Extraction Amount (AE Amount)> Regarding the vulcanized rubber test pieces cut and made from each rubber layer of the tread surface of each test tire, the AE amount was measured respectively. The AE amount is obtained by immersing each vulcanized rubber test piece in acetone for 24 hours, extracting the soluble components, measuring the mass of each test piece before and after extraction, and calculating through the following formula. Acetone extraction amount (mass %) = { (mass of vulcanized rubber test piece before extraction - mass of vulcanized rubber test piece after extraction) / (mass of rubber test piece before extraction)} × 100

[0205] <Low Fuel Consumption Performance> Using a rolling resistance test machine, the rolling resistance when each test tire was running at an internal pressure of (230 kPa), a load of (3.43 kN), and a speed of (80 km / h) was measured, and it was expressed as an index with the reference comparison examples (Comparative Example 2 in Table 1, Comparative Example 10 in Table 2, Comparative Example 19 in Table 3, Comparative Example 29 in Table 4) being 100. The larger the index, the smaller the rolling resistance and the more excellent the low fuel consumption performance.

[0206] <Abrasion Resistance Performance> Each test tire was installed on a domestic FF vehicle, the groove depth of the tread surface after driving 8000 km was measured, and the driving distance when the tire groove depth decreased by 1 mm was calculated, and it was expressed as an index with the reference comparison examples (Comparative Example 2 in Table 1, Comparative Example 10 in Table 2, Comparative Example 19 in Table 3, Comparative Example 29 in Table 4) being 100. The larger the index, the more excellent the abrasion resistance performance.

[0207] <Comprehensive Performance> The sum of the above low fuel consumption index and abrasion resistance performance index was expressed as the comprehensive performance index.

[0208]

Table 1

[0209]

Table 2

[0210]

Table 3

Table 4

[0212] <Embodiment> Examples of the embodiments of the present invention are shown below.

[0213] 〔1〕A tire having a tread portion with at least one rubber layer, wherein the ratio (G / W) of the tire weight G (kg) to the maximum load capacity W (kg) of the tire is 0.0160 or less, the cross-sectional width Wt of the tire is 200 mm or more, the first layer constituting the tread is composed of a rubber composition containing a rubber component and a filler, the thickness t1 of the first layer is greater than 3.0 mm, when the complex elastic modulus at 30 °C of the rubber composition is 30 °C E* (MPa) and the ground contact ratio on the ground contact surface of the tread portion is R, 30 °C E* is greater than 8.0 MPa, and the product (R × 30 °C E*) of R and 30 °C E* is greater than 5.0. L (kg) is 0.0160 or less, the cross-sectional width Wt of the tire is 200 mm or more, the first layer constituting the tread is composed of a rubber composition containing a rubber component and a filler, the thickness t1 of the first layer is greater than 3.0 mm, when the complex elastic modulus at 30 °C of the rubber composition is 30 °C E* (MPa) and the ground contact ratio on the ground contact surface of the tread portion is R, 30 °C E* is greater than 8.0 MPa, and the product (R × 30 °C E*) of R and 30 °C E* is greater than 5.0. L ) is 0.0160 or less, the cross-sectional width Wt of the tire is 200 mm or more, the first layer constituting the tread is composed of a rubber composition containing a rubber component and a filler, the thickness t1 of the first layer is greater than 3.0 mm, when the complex elastic modulus at 30 °C of the rubber composition is 30 °C E* (MPa) and the ground contact ratio on the ground contact surface of the tread portion is R, 30 °C E* is greater than 8.0 MPa, and the product (R × 30 °C E*) of R and 30 °C E* is greater than 5.0. 〔2〕The tire according to the above 〔1〕, wherein R × 30 °C E* is greater than 6.0 (preferably greater than 6.0 and less than 12.0). 〔3〕The tire according to the above 〔1〕 or 〔2〕, wherein the tanδ at 30 °C (30 °C tanδ) of the rubber composition is less than 0.25. 〔4〕The tire according to any one of the above 〔1〕 to 〔3〕, wherein the product (30 °C tanδ × 30 °C E* × t1) of 30 °C tanδ, 30 °C E*, and t1 is less than 12.0 (preferably greater than 5.0 and less than 11.0). 〔5〕The tire according to any one of the above 〔1〕 to 〔4〕, wherein the rubber composition contains silica having an average primary particle diameter of 16 nm or less. 〔6〕The tire according to any one of the above 〔1〕 to 〔5〕, wherein the rubber composition contains a mercapto-based silane coupling agent. 〔7〕The tire according to any one of the above 〔1〕 to 〔6〕, wherein the acetone extraction amount of the rubber composition is 20% by mass or less. 〔8〕The tire according to any one of the above 〔1〕 to 〔7〕, wherein the rubber component contains an isoprene-based rubber. 〔9〕The tire according to any one of the above 〔1〕 to 〔8〕, wherein the rubber component contains a styrene-butadiene rubber having a styrene content of 30% by mass or less. 〔10〕The tire according to any one of the above 〔1〕 to 〔9〕, wherein the total styrene amount S in the rubber component is 25% by mass or less. 〔11〕For the tire described in the above 〔10〕, S / 30℃E* is 2.5 or less. 〔12〕For the tire described in the above 〔10〕 or 〔11〕, the product of R and S (R×S) is 15.0 or less. 〔13〕For the tire according to any one of the above 〔1〕 to 〔12〕, when the modulus at 200% elongation of the rubber composition is M 200 (MPa), M of the rubber composition 200 , 30℃E* and 30℃tanδ satisfy the following formula (1). M 200 ×30℃E* / 30℃tanδ≥200 ···(1) 〔14〕For the tire according to any one of the above 〔1〕 to 〔13〕, the rubber composition contains vegetable oil. 〔15〕For the tire according to any one of the above 〔1〕 to 〔14〕, the filler contains silica made from biomass materials.

Claims

1. A tire, characterized in that: A tire having a tread portion having at least one rubber layer, Tire weight G and tire maximum load capacity W L Ratio G / W L is below 0.0160, The tire's cross-sectional width Wt is 200 mm or more. The first layer constituting the tread is composed of a rubber composition containing a rubber component and a filler. The thickness t1 of the first layer is greater than 3.0 mm, When the complex elastic modulus of the rubber composition at 30°C is 30°C E* and the ground contact ratio of the ground contact surface of the tread portion is R, 30°C E* is greater than 8.0 MPa, and the product of R and 30°C E* (R×30°C E*) is greater than 5.0, Tire weight G and maximum load capacity W L The unit of is kg, and the unit of 30℃E* is MPa.

2. The tire according to claim 1, wherein R×30°C E* is greater than 6.

0.

3. The tire according to claim 1, wherein 30°C E* is less than 15.0 MPa. 4 . The tire according to claim 1 , wherein R×30° C. E* is less than 12.

0. The tire according to claim 1 , wherein the rubber composition has a tan δ at 30° C. (tan δ at 30° C.) of less than 0.

25. 6 . The tire according to claim 5 , wherein the product of 30° C. tan δ, 30° C. E* and t1 (30° C. tan δ×30° C. E*×t1) is less than 12.

0. 7 . The tire according to claim 1 , wherein the rubber composition contains silica having an average primary particle size of 16 nm or less. 8 . The tire according to claim 1 , wherein the rubber composition contains a mercapto-based silane coupling agent. 9 . The tire according to claim 1 , wherein an acetone extractable amount of the rubber composition is 22% by mass or less. 10 . The tire according to claim 1 , wherein an acetone extractable amount of the rubber composition is 20% by mass or less. 11 . The tire according to claim 1 , wherein the rubber component contains isoprene-based rubber. 12 . The tire according to claim 1 , wherein the rubber component contains styrene-butadiene rubber having a styrene content of 30% by mass or less. 13 . The tire according to claim 1 , wherein a total styrene amount S in the rubber component is 25% by mass or less. 14 . The tire according to claim 13 , wherein S / 30° C. E* is 2.5 or less. 15 . The tire according to claim 13 , wherein the product of R and S (R×S) is 15.0 or less.

16. The tire according to any one of claims 1 to 6, wherein the modulus of the rubber composition when stretched 200% is M 200 When the rubber composition M 200 , 30℃E* and 30℃tanδ satisfy the following formula (1), M 200 The unit is MPa, M 200 ×30℃E* / 30℃tanδ≥200· · · (1)。 17 . The tire according to claim 1 , wherein the rubber composition contains vegetable oil. 18 . The tire according to claim 1 , wherein the filler contains silica made from a biomass material.

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