tire

Abstract

To provide a tire which can improve total performance of low fuel consumption performance and abrasion resistance performance.SOLUTION: A tire includes a tread part having at least one rubber layer, wherein a ratio (G / WL) of tire weight G (kg) to maximum load capacity WL(kg) of the tire is 0.0170 or less, a first layer constituting the tread surface is composed of a rubber composition containing a rubber component and a filler, the filler contains a sustainable filler, and when a land ratio on the ground surface of the tread part is represented by R, and the total content of the filler with respect to 100 pts.mass of the rubber component in the rubber composition is represented by F (pts.mass), a product (R×F) of R and F exceeds 42.0.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] In addition to low fuel consumption performance (rolling resistance characteristics), the tread of a tire is required to have performance such as wear resistance and wet skid resistance. Performance improvement has been carried out by devising the rubber component, filler, etc. used in the tread part (for example, Patent Documents 1 and 2), but there is still room for improvement in the point of improving these performances in a well-balanced manner.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

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 overall performance of low fuel consumption performance and wear resistance.

Means for Solving the Problems

[0005] In recent years, tires have been made lighter in order to reduce the rolling resistance of the tires. In order to make the tire lighter, it is conceivable to reduce the thickness of the tread part, but there is a concern that the life of the tire will be shortened due to wear. In addition, since low-fuel-consumption rubber generates little heat, it easily deforms when it receives an impact, and the destruction of the rubber tends to progress easily.

[0006] The present invention is a tire provided with a tread part having at least one rubber layer, and the maximum load capacity W of the tire LThe ratio (G / W L ) of the tire weight G (kg) to the maximum load capacity W (kg) of the tire is 0.0170 or less, the first layer constituting the tread surface is composed of a rubber composition containing a rubber component and a filler, the filler includes a sustainable filler, when the land ratio at the grounding surface of the tread portion is R and the total content of the filler with respect to 100 parts by mass of the rubber component in the rubber composition is F (parts by mass), the present invention relates to a tire in which the product (R×F) of R and F exceeds 42.0.

Advantages of the Invention

[0007] According to the present invention, there is provided a tire capable of improving the overall performance of low fuel consumption performance and wear resistance performance.

Brief Description of the Drawings

[0008]

Figure 1

Embodiments for Carrying Out the Invention

[0009] A tire according to an embodiment of the present invention is a tire provided with a tread portion having at least one rubber layer, the ratio (G / W L ) of the tire weight G (kg) to the maximum load capacity W (kg) of the tire is 0.0170 or less, the first layer constituting the tread surface is composed of a rubber composition containing a rubber component and a filler, the filler includes a sustainable filler, when the land ratio at the grounding surface of the tread portion is R and the total content of the filler with respect to 100 parts by mass of the rubber component in the rubber composition is F (parts by mass), the product (R×F) of R and F exceeds 42.0. L ) is a tire.

[0010] Regarding the reason why the overall performance of the low fuel consumption performance and wear resistance performance of the tire of the present invention is improved, although not intended to be restricted by theory, it is considered as follows.

[0011] Increasing the tire cross-sectional width Wt increases the maximum load capacity W L so that G / W L is 0.0160 or less, and it is considered that the low fuel consumption effect due to reducing the weight of the tire becomes larger.

[0012] Sustainable fillers are characterized by a wide particle size distribution. Since an increase in viscosity occurs due to the influence of the portion with a small particle diameter of such a filler, the shear force required for the dispersion of the filler increases, and it is considered that the dispersibility of the filler is improved.

[0013] Also, by increasing the total filler content F, the breaking strength of the rubber can be ensured. Furthermore, by increasing the land ratio R, it is considered that the pattern rigidity increases and the wear energy improves. From this, it is considered that the wear resistance performance can be improved by making the product of R and F equal to or greater than a certain value.

[0014] And it is considered that by these cooperating, the overall performance of the low fuel consumption performance and the wear resistance performance of the tire can be improved.

[0015] From the viewpoint of constructing a sustainable society, the filler preferably contains silica made from biomass materials.

[0016] From the viewpoint of constructing a recycling-oriented society, the filler preferably contains recycled carbon black.

[0017] The tanδ (tanδ at 30°C) of the rubber composition at 30°C is preferably 0.20 or less.

[0018] By setting tanδ at 30°C within the above range, it is considered that the low fuel consumption performance can be improved.

[0019] (R×F) / (G / W L ) is preferably more than 3000.

[0020] (R×F) / (G / W LBy setting [[ID=]] to the above range, it is considered that the wear resistance performance can be improved.

[0021] When the complex elastic modulus of the rubber composition at 30 °C is 30 °C E* (MPa), the product of R and 30 °C E* (R×30 °C E*) is preferably greater than 2.5.

[0022] By setting R×30 °C E* to the above range, it is considered that the wear resistance performance can be improved.

[0023] 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.

[0024] The product of R and S (R×S) is preferably 15.0 or less.

[0025] By setting R×S to the above range, it is considered that the low fuel consumption performance can be improved.

[0026] S / 30 °C E* is preferably 6.0 or less.

[0027] When 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. From this, it is considered that by reducing the total styrene amount S as 30 °C E* decreases, the low fuel consumption performance and the breaking strength of the tread rubber are further improved.

[0028] From the viewpoint of the effects of the present invention, the rubber component preferably contains an isoprene-based rubber.

[0029] From the viewpoint of the effects of the present invention, the rubber component preferably contains a styrene-butadiene rubber having a styrene content of 30% by mass or less.

[0030] When the modulus at 200% elongation of the rubber composition is M 200 (MPa), 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 ≥ 100.

[0031] M 200 × 30°C E* / 30°C tan within the above range is considered to be able to improve the low fuel consumption performance and wear resistance performance in a well-balanced manner.

[0032] From the perspective of building a sustainable society, the rubber composition preferably contains vegetable oil.

[0033] <Definition> The "tread part" is the part that forms the ground contact surface of the tire. In the radial cross-section of the tire radius, when it is provided with members that form the tire skeleton by steel or textile materials such as the belt layer, belt reinforcing layer, and carcass layer, it is a member outside these in the tire radius direction.

[0034] The "normal state" is a no-load state in which it is assembled to a normal rim and filled with air at normal internal pressure.

[0035] The "dimensions of each part of the tire" are, unless otherwise specified, values specified in the normal state for those appearing on the outer surface of the tire, while those existing inside the tire or on the tire cut surface are, for example, values specified in a state where the tire is cut by a plane including the tire rotation axis and the cut tire piece is held at the rim width of the normal rim.

[0036] "Normal Rim" refers to the rim defined for each tire in the standard system that includes the standards on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Association), it refers to the standard rim in the applicable sizes described in the "JATMA YEAR BOOK"; in the case of ETRTO (The European Tyre and Rim Technical Organisation), it refers to the "Measuring Rim" described in the "STANDARDS MANUAL"; and in the case of TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" described in the "YEAR BOOK". Refer to JATMA, ETRTO, and TRA in that order, and follow the relevant standards if there are applicable sizes during the reference. In the case of a tire not defined in the above standards, it refers to the rim with the narrowest width among the smallest-diameter rims that can be assembled with the tire and can maintain the internal pressure (i.e., does not cause air leakage between the rim and the tire).

[0037] "Normal Inflation Pressure" refers to the air pressure defined for each tire in the standard system that includes the standards on which the tire is based. For example, in the case of JATMA, it refers to the "Maximum Air Pressure"; in the case of ETRTO, it refers to the "INFLATION PRESSURE"; and in the case of TRA, it refers to the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". Similar to the case of the normal rim, refer to JATMA, ETRTO, and TRA in that order, and follow the relevant standards if there are applicable sizes during the reference. In the case of a tire not defined in the above standards, it refers to the normal inflation pressure (but not less than 250 kPa) of another tire size described with the normal rim as the standard rim (however, as defined in the standards). If there are multiple normal inflation pressures not less than 250 kPa described, it refers to the minimum value among them.

[0038] The "normal load" refers to the load specified for each tire in a standard system that includes the standards 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 "LOAD CAPACITY"; and in the case of TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". Refer to JATMA, ETRTO, and TRA in this order, as in the case of the normal rim and normal internal pressure, and follow the relevant standard if there is an applicable size when referring. For tires not specified in the above standards, the maximum load capacity W L calculated separately is taken as the normal load.

[0039] The "maximum load capacity W L " is calculated by the following formula. "V" is the virtual volume of the tire (mm 3 ), "Dt" is the outer diameter of the tire in the normal state (mm), "Ht" is the cross-sectional height of the tire in the radial direction of the tire in the cross-section of the tire by a plane including the tire rotation axis (mm), and "Wt" is the cross-sectional width of the tire in the normal state (mm). When R is the rim diameter of the tire, Ht can be obtained by (Dt - R) / 2. Wt is the value obtained excluding patterns, letters, etc. on the tire sidewall. Note that the maximum load capacity is synonymous with the above normal load.

[0040]

Equation

[0041] The "tire weight G (kg)" refers to the weight of the tire alone without including the weight of the rim. On the other hand, when the tire inner cavity is equipped with a sound insulation material, a sealant, a sensor, etc., G includes the weight of these components.

[0042] The "groove", including the circumferential groove and the transverse groove, refers to a recess with a width greater than at least 2.0 mm.

[0043] The "contact area" is the area of the tread obtained from the contour when the tire is pressed against the ground. After assembling the tire on the standard rim, applying the standard internal pressure, and leaving it standing for 24 hours at 25°C, ink is applied to the tire tread surface. Then, the tire is loaded with the standard load (maximum load capacity) and pressed vertically against thick paper (the camber angle is 0°), and the ink is transferred to obtain it. The area of the contact area is called the total contact area. The total contact area can be calculated as the average value of the five areas obtained by performing the above transfer operation while rotating the tire by 72° each time for a total of five locations.

[0044] The "effective contact area" is the area of the tread where the tire contacts the ground when the tire is pressed against the ground. After assembling the tire on the standard rim, applying the standard internal pressure, and leaving it standing for 24 hours at 25°C, ink is applied to the tire tread surface. Then, the tire is loaded with the standard load (maximum load capacity) and pressed vertically against thick paper (the camber angle is 0°), and the ink is transferred to obtain it. The area of the effective contact area is called the effective contact area. The effective contact area can be calculated as the average value of the five areas obtained by performing the above transfer operation while rotating the tire by 72° each time for a total of five locations.

[0045] The "land ratio R" is calculated by the following formula from the total contact area of the contact area and the effective contact area of the effective contact area. (Land ratio) = (Effective contact area / Total contact area)

[0046] The "overall thickness of the tread part" refers to 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. Note that the inner end in the tire radius direction of the overall thickness of the tread part is the inner interface in the tire radius direction of the rubber composition constituting the tread part. When the tire includes a belt reinforcement layer, a belt layer, and a carcass layer, among these, it is the total thickness of the rubber layer outside the outermost layer in the tire radius direction in the tire radius direction. When there are circumferential grooves on the tire equatorial plane, the overall thickness of the tread part is measured with the grooves filled.

[0047] The "thickness of each rubber layer constituting the tread portion" is the thickness of each rubber layer on the tire equatorial plane in a cross-section obtained by cutting the tire with a plane including the tire rotation axis, and is the average value of the thicknesses of the tread portion obtained at five positions by rotating the tire by 72° in the circumferential direction. For example, the thickness of the first layer refers to the linear distance in the tire radial direction from the outermost surface of the tread to the inner interface of the first layer in the tire radial direction on the tire equatorial plane. When there are circumferential grooves on the tire equatorial plane, the thickness of each rubber layer constituting the tread portion shall be the thickness of each rubber layer at the center in the tire width direction of the land portion closest to the tire equatorial plane. The "land portion closest to the tire equatorial plane" refers to the land portion having the groove edge closest to the tire equatorial plane among the circumferential grooves existing on the tire equatorial plane. When such land portions exist on both sides in the tire width direction, the thickness of each rubber layer constituting the tread portion shall be the average value of the thicknesses of each rubber layer at the center in the tire width direction of the two land portions. Also, when there are current-carrying members or the like on the land portion on the tire equatorial plane and the interface is unclear, it shall be measured by virtually connecting the interfaces blocked by the current-carrying members or the like.

[0048] The "sustainable filler" refers to a filler made from a biomass material as a raw material or a filler obtained from a used article containing a filler.

[0049] The "plasticizer" is a material that imparts plasticity to the rubber component and is a component extracted from the rubber composition using acetone. The plasticizer includes plasticizers that are liquid (liquid state) at 25°C and plasticizers that are solid at 25°C. However, waxes and stearic acid commonly used in the tire industry are not included.

[0050] The "content of plasticizer" also includes the amount of plasticizer contained in the stretched rubber component previously stretched by a plasticizer such as oil, resin component, liquid rubber component, etc. The same applies to the content of oil, the content of resin component, and the content of liquid rubber. For example, when the stretching component is oil, the stretched oil is included in the content of oil.

[0051] <Measurement method> The "thickness of each rubber layer constituting the tread portion" is measured with the tire cut along a plane including the tire rotation axis and with the width of the bead portion adjusted to match the width of the standard rim.

[0052] "tanδ at 30°C" is the loss tangent 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 an elongation mode using a dynamic viscoelasticity measuring device (for example, the Implex series manufactured by GABO). The sample for loss tangent measurement is a vulcanized rubber composition with a length of 20 mm × a width of 4 mm × a thickness of 1 mm. When it is prepared by cutting from a tire, it is cut from the tread portion of the tire such that the tire circumferential direction is the long side and the tire radial direction is the thickness direction.

[0053] "E* at 30°C" 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 an elongation mode using a dynamic viscoelasticity measuring device (for example, the Implex series manufactured by GABO). The sample for this measurement is prepared in the same manner as in the case of 30°C tanδ.

[0054] "Modulus at 200% elongation (M 200 )" is the tensile stress (MPa) at 200% elongation in the columnar direction (the rolling direction when forming a rubber sheet by extrusion or shearing treatment) measured in accordance with JIS K 6251:2017 under the condition of a tensile speed of 3.3 mm / second in an atmosphere of 23°C. The sample for M 200 measurement is a dumbbell-shaped No. 7 vulcanized rubber test piece with a thickness of 1 mm. When it is prepared by cutting from a tire, it is cut from the tread portion of the tire such that the tire circumferential direction is the tensile direction and the tire radial direction is the thickness direction.

[0055] "Styrene content" is a value calculated by pyrolysis gas chromatography and is applied, for example, to rubber components having repeating units derived from styrene such as SBR. In this specification, "pyrolysis gas chromatography" refers to a method in which a sample is heated by a pyrolysis device, the individual components contained in the gas-phase components generated by this heating are separated by a separation column, and each isolated component is analyzed.

[0056] "Vinyl content (1,2-bonded butadiene unit amount)" is a value calculated by infrared absorption spectrum analysis in accordance with JIS K 6239-2:2017, and is applicable to rubber components having repeating units derived from butadiene such as SBR and BR, for example.

[0057] "Cis content (cis-1,4-bonded butadiene unit amount)" is a value calculated by infrared absorption spectrum analysis in accordance with JIS K 6239-2:2017, and is applicable to rubber components having repeating units derived from butadiene such as BR, for example.

[0058] "Total styrene amount in the rubber component" is the total content (% by mass) of styrene units contained in 100% by mass of the rubber component. For each rubber component, a value obtained by multiplying the styrene content (% by mass) by the mass fraction in the rubber component is calculated, and the sum of these values is the total value. Specifically, it is calculated by Σ (styrene content (% by mass) of each rubber containing styrene units × content (% by mass) of each rubber containing styrene units in the rubber component / 100).

[0059] "Weight average molecular weight (Mw)" can be determined by standard polystyrene conversion based on the measured value by gel permeation chromatography (GPC) (for example, GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKgel SuperMultipore HZ-M manufactured by Tosoh Corporation). For example, it is applicable to SBR, BR, plasticizers, etc.

[0060] "Nitrogen adsorption specific surface area (N2SA) of carbon black" is measured in accordance with JIS K 6217-2:2017. "Nitrogen adsorption specific surface area (N2SA) of silica" is measured by the BET method in accordance with ASTM D3037-93.

[0061] "Particle size distribution" is measured by a laser diffraction particle size distribution measuring device (for example, SALD-2300 manufactured by Shimadzu Corporation), and is applicable to silica, carbon black, etc., for example.

[0062] The "average primary particle diameter" is obtained by photographing particles with a transmission or scanning electron microscope and calculating the arithmetic mean of 400 particle diameters. When the shape of the particle is approximately circular, the diameter of the circle is taken as the particle diameter; when the particle is needle-shaped or rod-shaped, the minor axis is taken as the particle diameter; and in other cases, the equivalent circle diameter is calculated from the electron microscope image and taken as the particle diameter. The equivalent circle diameter is obtained as the positive square root of [4 × (particle area) / π]. The average primary particle diameter is applicable to silica, carbon black, etc.

[0063] The "softening point of the resin component" is measured with a ring and ball softening point measuring device according to the softening point defined in JIS K 6220-1:2015 7.7, and is the temperature at which the ball drops.

[0064] The production procedure of the tire which is one embodiment of the present invention will be described in detail below. However, the following description is an exemplification for explaining the present invention, and is not intended to limit the technical scope of the present invention only to this description scope.

[0065] [Tire] In the tire according to this embodiment, the ratio (G / W L (kg)) of the tire weight G (kg) to the maximum load capacity W L ) is 0.0170 or less, preferably 0.0165 or less, more preferably 0.0155 or less, further preferably 0.0145 or less, further preferably 0.0140 or less, and particularly preferably 0.0135 or less from the viewpoint of the effects of the present invention. On the other hand, the lower limit value of the G / W L is not particularly limited from the viewpoint of the effects of the present invention, but can be, for example, 0.0110 or more, 0.0115 or more, 0.0120, 0.0125 or more. Note that the tire weight G can be varied by a conventional method, that is, it can be increased by increasing the specific gravity of the tire or increasing the thickness of each member of the tire, and can be decreased conversely.

[0066] The maximum load capacity W L(kg) is preferably 300 or more, more preferably 400 or more, still more preferably 450 or more, and particularly preferably 500 or more from the viewpoint of more favorably exhibiting the effects of the present invention. Further, the maximum load capacity W L (kg) can be, for example, 1300 or less, 1250 or less, 1200 or less, 1000 or less, 900 or less, 800 or less, 700 or less from the viewpoint of more favorably exhibiting the effects of the present invention. Note that the maximum load capacity W L can be increased by increasing the virtual volume V of the space occupied by the tire, and conversely can also be decreased.

[0067] The land ratio R on the ground contact surface of the tread portion is preferably 0.50 or more, more preferably 0.55 or more, still more preferably 0.60 or more, and particularly preferably 0.63 or more. Further, the land ratio R is preferably 0.85 or less, more preferably 0.80 or less, and still more preferably 0.75 or less.

[0068] 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 whose outer surface constitutes the tread surface and one or more rubber layers (inner rubber layers) existing between the first layer and the belt layer.

[0069] The thickness of the first layer constituting the tread surface with respect to the thickness of the entire tread portion can be, for example, 30% or more, 50% or more, 70% or more, 90% or more, and the tread portion may be composed only of the first layer constituting the tread surface.

[0070] From the perspective of the effects of the present invention, the 30°C E* of the rubber composition constituting the first layer is preferably 3.0 MPa or more, more preferably 3.5 MPa or more, still more preferably 4.0 MPa or more, and particularly preferably 4.5 MPa or more. Also, the 30°C E* of the rubber composition is preferably 15.0 MPa or less, more preferably 13.0 MPa or less, still more preferably 11.0 MPa or less, and particularly preferably 10.0 MPa or less. Note that the 30°C E* of the rubber composition can be appropriately adjusted according to the types and compounding amounts of the rubber component, vulcanized rubber particles, resin component, oil, etc. described later.

[0071] From the perspective of the effects of the present invention, the 30°C tanδ of the rubber composition constituting the first layer is preferably 0.30 or less, more preferably 0.27 or less, still more preferably 0.25 or less, even more preferably 0.22 or less, even more preferably 0.20 or less, and particularly preferably 0.18 or less. Also, the 0°C tanδ of the rubber composition is preferably 0.06 or more, more preferably 0.08 or more, and still more preferably 0.10 or more. Note that the 30°C tanδ of the rubber composition can be appropriately adjusted according to the types and compounding amounts of the rubber component, vulcanized rubber particles, resin component, oil, etc. described later.

[0072] The M of the rubber composition constituting the first layer 200 is preferably 3.0 MPa or more, more preferably 3.5 MPa or more, still more preferably 4.0 MPa or more, and particularly preferably 4.5 MPa or more from the perspective of the effects of the present invention. On the other hand, the upper limit value of the M of the rubber composition 200 is not particularly limited, but is preferably 15.0 MPa or less, more preferably 13.0 MPa or less, and still more preferably 11.0 MPa or less. Note that the M of the rubber composition 200 can be appropriately adjusted according to the types and compounding amounts of the rubber component, vulcanized rubber particles, resin component, oil, etc. described later.

[0073] The product (R×F) of the land ratio R and the total filler content F (parts by mass) per 100 parts by mass of the rubber component in the rubber composition is more than 42.0, preferably more than 44.0, more preferably more than 46.0, and even more preferably more than 48.0 from the viewpoint of abrasion resistance performance. On the other hand, the upper limit value of R×F is not particularly limited, but preferably less than 75.0, more preferably less than 70.0.

[0074] The product (R×30°C E*) of the land ratio R and the 30°C E* (MPa) of the rubber composition constituting the first layer is preferably more than 2.0, more preferably more than 2.5, even more preferably more than 3.0, and particularly preferably more than 3.5. On the other hand, the upper limit value of R×30°C E* is not particularly limited, but preferably less than 14.0, more preferably less than 12.0, even more preferably less than 10.0, and particularly preferably less than 8.0.

[0075] The ratio (S / 30°C E*) of the total styrene amount S (mass%) in the rubber component to the 30°C E* of the rubber composition constituting the first layer is preferably 6.0 or less, more preferably 5.5 or less, even more preferably 5.0 or less, and particularly preferably 4.5 or less. Also, the lower limit value of S / 30°C E* is not particularly limited from the viewpoint of the effects of the present invention, but preferably more than 0, more preferably 0.3 or more, even more preferably 0.6 or more, and particularly preferably 0.9 or more.

[0076] The product (R×S) of the land ratio R and the total styrene amount S (mass%) in the rubber component is preferably 24.0 or less, more preferably 21.0 or less, even more preferably 18.0 or less, and particularly preferably 15.0 or less. On the other hand, the lower limit value of R×S is not particularly limited, but preferably 1.0 or more, more preferably 2.0 or more, even more preferably 3.0 or more, and particularly preferably 4.0 or more.

[0077] The product (30°C tanδ×30°C E*×t1) of 30°C tanδ, 30°C E*, and the thickness t1 of the first layer of the tread portion is preferably less than 8.25, more preferably less than 8.00, and even more preferably less than 7.75. On the other hand, 30°C tanδ×30°C E*×t1 is preferably more than 2.00, more preferably more than 2.50, and even more preferably more than 3.00.

[0078] (R×F) / (G / W L ) is preferably more than 3000, and more preferably more than 3500. On the other hand, (R×F) / (G / W L ) is not particularly limited in its upper limit value, but is preferably less than 5000, and more preferably less than 4500.

[0079] M 200 ×30°C E* / 30°C tanδ is preferably 100 or more, more preferably 120 or more, still more preferably 140 or more, and particularly preferably 160 or more. On the other hand, M 200 ×30°C E* / 30°C tanδ is not particularly limited in its upper limit value, but is preferably 800 or less, more preferably 700 or less, still more preferably 600 or less, and particularly preferably 500 or less.

[0080] [Rubber composition] The tire according to this embodiment can more effectively improve the comprehensive performance of low fuel consumption performance and wear resistance performance by the cooperation of the configurations of the tire and the tread part described above and the physical properties of the rubber composition constituting the tread part. Hereinafter, the rubber composition constituting the first layer will be described.

[0081] [Rubber component] In the rubber composition according to this embodiment, a diene rubber is preferably used as the rubber component. 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), and the like. These diene rubbers may be modified rubbers treated with a modifying group capable of interacting with a filler such as carbon black or 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. Further, as the diene rubber, an extended rubber preliminarily extended using a plasticizer described later may 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, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Further, the rubber component may be composed of only 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, still more preferably contains isoprene rubber, BR, and SBR, and may also be a rubber component composed of only 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), modified natural rubber, etc. Examples of NR include SIR20, RSS#3, TSR20, etc. Examples of IR include IR2200, etc. Examples of 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 viewpoint of the effects of the present invention, the content of the isoprene rubber in the rubber component is preferably 90% by mass or less, more preferably 80% by mass or less, still more preferably 70% by mass or less, and particularly preferably 60% by mass or less. Further, the lower limit value of the content is not particularly limited, and 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.

[0086] (BR) BR is not particularly limited. 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 butadiene rubber synthesized using a rare-earth element-based catalyst (rare-earth-based BR), BR containing syndiotactic polybutadiene crystals (SPB-containing BR), modified BR (high-cis modified BR, low-cis modified BR), etc., which are common in the tire industry, can be used. These BRs may be used alone or in combination of two or more.

[0087] As the high-cis BR, for example, those commercially available from Nippon Zeon Co., Ltd., UBE Industries, Ltd., JSR Corporation, etc. can be used. By containing high-cis BR, the abrasion resistance performance can be improved. The cis content of the high-cis BR is preferably 95 mol% or more, more preferably 96 mol% or more, and still more preferably 97 mol% or more. The cis content of BR is measured by the above-mentioned measurement method.

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

[0089] Other modified BRs include those obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and further having the terminal of the modified BR molecule bonded by a tin-carbon bond (tin-modified BR), etc. Also, the modified BR may be either unhydrogenated or hydrogenated.

[0090] From the viewpoint of abrasion resistance performance, the weight average molecular weight (Mw) of BR is preferably 300,000 or more, more preferably 350,000 or more, and still more preferably 400,000 or more. From the viewpoints such as crosslinking uniformity, etc., it is preferably 2,000,000 or less, more preferably 1,000,000 or less. The Mw of BR is measured by the above-mentioned 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. The lower limit of the content is not particularly limited, but 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) SBR is not particularly limited, and examples include unmodified solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), and modified SBR (modified S-SBR, modified E-SBR) thereof. Examples of modified SBR include SBR with modified terminals and / or main chains, and modified SBR coupled with tin, silicon compounds, etc. (condensates, those having a branched structure, etc.). Furthermore, hydrogenated products (hydrogenated SBR) of these SBRs can also be used. These SBRs can be used alone or in combination of two or more.

[0093] In the SBR according to this embodiment, stretched SBR or non-stretched SBR can be used. When using stretched SBR, the stretching amount of SBR, that is, the content of the stretching plasticizer contained in SBR, is preferably 10 to 50 parts by mass with respect to 100 parts by mass of the rubber solid content of SBR.

[0094] The SBR listed above can be used alone or in combination of two or more. As the SBR listed above, for example, those commercially available from Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., ZS Elastomer Co., Ltd., etc. can be used.

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

[0096] From the viewpoints of ensuring reactivity with silica and abrasion resistance performance, the vinyl content of the SBR is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more. Also, from the viewpoints of elongation at break and abrasion resistance performance, the vinyl content of the SBR is preferably 50 mol% or less, more preferably 40 mol% or less, and even more preferably 35 mol% or less. Note that in this specification, the vinyl content of the 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 the SBR is preferably 100,000 or more, more preferably 200,000 or more, and even more preferably 300,000 or more. Also, 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 even more preferably 1,500,000 or less. Note that the weight average molecular weight of the 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 following range. However, it is preferably 20% by mass or more, more preferably 30% by mass or more, even more 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, even more preferably 90% by mass or less, and particularly preferably 85% by mass or less.

[0099] From the perspective of the effects of the present invention, the total styrene content S in the rubber component is preferably 30% by mass or less, more preferably 27% by mass or less, still more preferably 25% by mass or less, and particularly preferably 22% by mass or less. The lower limit of the total styrene content S in the rubber component is not particularly limited, but is preferably 1% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more, and particularly preferably 7% by mass or more.

[0100] (Other rubber components) The rubber component may contain a rubber component other than a diene rubber (non-diene rubber) as long as it does not affect the effects of the present invention. As the non-diene rubber, rubber components generally used in the tire industry can be used. For example, butyl rubber, ethylene propylene rubber, polynorbornene rubber, silicone rubber, chlorinated polyethylene rubber, fluororubber (FKM), acrylic rubber (ACM), hydrin rubber, etc. can be mentioned. These other rubber components may be used alone or in combination of two or more. In addition, a known thermoplastic elastomer may or may not be contained in addition to the above rubber components.

[0101] (Rubber components synthesized from recycled and biomass-derived raw materials) The monomers that are the constituent units of synthetic rubbers such as IR, BR, and SBR may be derived from underground resources such as petroleum and natural gas, or may be recycled from rubber products such as tires and non-rubber products such as polystyrene. The monomers obtained by recycling (recycled monomers) are not particularly limited, and examples include recycled polyisoprene, recycled butadiene, recycled aromatic vinyl compounds, etc. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl compound is not particularly limited, and examples include styrene. Among them, it is preferable to use recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and recycled styrene (recycled styrene) as raw materials.

[0102] The method for producing the recycled monomer is not particularly limited. For example, it can be synthesized from naphtha derived from recycling obtained by decomposing rubber products such as tires. Also, the method for producing naphtha derived from recycling is not particularly limited. For example, rubber products such as tires may be decomposed under high temperature and high pressure, decomposed by microwaves, or extracted after mechanical pulverization.

[0103] Furthermore, the monomers that are the constituent units of synthetic rubbers such as IR, BR, and SBR may be derived from biomass. In this specification, biomass refers to substances derived from natural resources such as plants. Biomass is not particularly limited, but examples include agricultural and forestry products, sugars, wood chips, plant residues after obtaining useful components, ethanol derived from plants, biomass naphtha, and the like.

[0104] The biomass-derived monomers (biomass monomers) are not particularly limited, and examples include biomass-derived butadiene and biomass-derived aromatic vinyl compounds. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl compound is not particularly limited, and examples include styrene. Also, the method for producing biomass monomers is not particularly limited, and examples include those by biological and / or chemical and / or physical conversion of animals and plants. Fermentation by microorganisms is typical of biological conversion, and examples of chemical and / or physical conversion include those by catalysts, high heat, high pressure, electromagnetic waves, supercritical fluids, and combinations thereof.

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

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

[0107] pMC is the ratio of the 14 C concentration of the sample to the 14 C concentration of the standard modern carbon (modern standard reference), and is a value used as an index indicating the biomass ratio of a compound. The significance of this value is described below.

[0108] In one mole (6.02×10 23 individuals) of carbon atoms, there are approximately 6.02×10 11 individuals of 14 C, which is about one trillionth of the normal carbon atom. 14 The half-life of 14 C is 5730 years, and 14 C decreases regularly. It takes 226,000 years for all of these to decay. Therefore, in fossil fuels such as coal, oil, and natural gas, which are considered to have passed more than 226,000 years after carbon dioxide in the atmosphere was taken up and fixed by plants, etc., all of the 14 C elements that were originally contained in these have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas do not contain any 14 C elements. Therefore, chemical substances produced from these fossil fuels as raw materials also do not contain any

[0109] On the one hand, 14 C is constantly generated by cosmic rays undergoing nuclear reactions in the atmosphere. From this, 14 C is in equilibrium between the decrease due to radioactive decay and the generation due to nuclear reactions. In the earth's atmospheric environment, 14 the amount of C is a constant amount. Therefore, for substances derived from biomass resources that are cycling in the current environment, 14 the C concentration is about 1×10 -12 mol% with respect to the total number of carbon atoms as described above. Therefore, by utilizing the difference between these values, the biomass ratio in a certain compound can be calculated.

[0110] This 14 C is generally measured as follows. Using accelerator mass spectrometry based on a tandem accelerator, 13 C concentration ( 13 C / 12 C), 14 C concentration ( 14 C / 12 C) is measured. In the measurement, 14 as the modern standard reference for the concentration of C, the 14 C concentration in the circulating carbon in nature as of 1950 is adopted. As a specific standard substance, the oxalic acid standard provided by NIST (National Institute of Standards and Technology) is used. The specific activity of carbon in this oxalic acid (the radioactivity intensity of 14 C per 1 g of carbon) is separated for each carbon isotope, 13 and for 14 C, it is corrected to a constant value and the value after applying the decay correction from 1950 AD to the measurement date is used as the standard 14 C concentration value (100%). The ratio of this value to the value of the sample actually measured is the pMC value.

[0111] Therefore, if the rubber is made of 100% biomass-derived substances, although there are regional differences, etc., it usually does not reach 100 under normal conditions at present, so it will show a value of about 110 pMC. On the other hand, for chemical substances derived from fossil fuels such as petroleum, when measuring this 14 C concentration, it will show a value of about 0 pMC (for example, 0.3 pMC). This value corresponds to the biomass ratio of 0% mentioned above.

[0112] From the above, using materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in the rubber composition is suitable from the perspective of environmental protection.

[0113] <Filler> The rubber composition according to this embodiment contains a sustainable filler as a filler, and may also contain fillers other than the sustainable filler. The sustainable filler is not particularly limited as long as it is a filler made from a biomass material as a raw material or a filler obtained from used articles containing a filler, but sustainable silica and sustainable carbon black are preferred.

[0114] (Silica) Examples of sustainable silica include silica made from a biomass material as a raw material, and specifically, amorphous silica refined from rice husks, etc.

[0115] Silica made from a biomass material as a raw material can be obtained, for example, by extracting silicate from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and reacting the silicate with sulfuric acid in the same manner as conventional wet silica to obtain a precipitate of silicon dioxide, which is then filtered, washed with water, dried, and pulverized (see, for example, Japanese Patent Laid-Open No. 2019-38728).

[0116] When silica crystallizes, it becomes insoluble in water and the silicic acid that is its component cannot be utilized. By controlling the combustion temperature and combustion time, crystallization of silica in rice husk ash can be suppressed (see, for example, Japanese Patent Application Laid-Open No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol. 6, p. 216-222, etc.).

[0117] As the amorphous silica extracted from rice husks, those commercially available from Wilmar Co., Ltd. and others can be used.

[0118] From the viewpoint of ensuring the reinforcing property and the damping property in the tread portion, the nitrogen adsorption specific surface area (N2SA) of sustainable silica is preferably 110 m 2 / g or more, more preferably 140 m 2 / g or more, still more preferably 170 m 2 / g or more, particularly preferably 200 m 2 / g or more. Also, from the viewpoints of exothermic property and processability, it is preferably 350 m 2 / g or less, more preferably 300 m 2 / g or less, still more preferably 250 m 2 / g or less. The N2SA of silica is measured by the above-described measurement method.

[0119] From the viewpoint of increasing the specific surface area of silica, increasing the interaction with the rubber component, suppressing the movement of molecular chains, and suppressing heat generation, the average primary particle diameter of sustainable silica is preferably 20 nm or less, more preferably 18 nm or less, still more preferably 16 nm or less. The lower limit value of the average primary particle diameter 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, still more preferably 5 nm or more. The average primary particle diameter of silica is measured by the above-described measurement method.

[0120] The silica using the biomass material according to this embodiment as a raw material preferably contains silica with a primary particle diameter of 23 nm or more. By containing silica with a primary particle diameter of 23 nm or more, it is considered that the low fuel consumption performance can be improved. In this specification, "containing silica with a primary particle diameter of 23 nm or more" means that the integrated particle size (D99) at 99% in the volume integrated particle size distribution of silica is 23 nm or more.

[0121] The silica other than sustainable silica is not particularly limited, and for example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrous silica), etc., which are common in the tire industry, can be used. Among them, hydrous silica prepared by a wet method is preferred because it has many silanol groups.

[0122] The nitrogen adsorption specific surface area (N2SA) of the silica other than sustainable silica is preferably 110 m 2 / g or more, more preferably 140 m 2 / g or more, even more preferably 170 m 2 / g or more, and particularly preferably 200 m 2 / g or more, from the viewpoints of reinforcement and ensuring attenuation in the tread part. Also, 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, even more preferably 250 m 2 / g or less.

[0123] The average primary particle diameter of the silica other than sustainable silica is preferably 20 nm or less, more preferably 18 nm or less, and even more preferably 16 nm or less, from the viewpoint of increasing the specific surface area of silica, increasing the interaction with the rubber component, suppressing the movement of molecular chains, and suppressing heat generation. The lower limit value of the average primary particle diameter 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 even more preferably 5 nm or more.

[0124] From the viewpoint of the effects of the present invention, the content of sustainable silica relative to 100 parts by mass of the rubber component is preferably 20 parts by mass or more, more preferably 35 parts by mass or more, still more preferably 50 parts by mass or more, and particularly preferably 60 parts by mass or more. Also, the content 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.

[0125] From the viewpoint of ensuring reinforcement and attenuation in the tread portion, the content of silica relative to 100 parts by mass of the rubber component is preferably 20 parts by mass or more, more preferably 35 parts by mass or more, still more preferably 50 parts by mass or more, and particularly preferably 60 parts by mass or more. Also, from the viewpoint of reducing the specific gravity of the rubber 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.

[0126] (Carbon black) Examples of sustainable carbon black include carbon black made from biomass materials such as lignin and vegetable oil as raw materials, and recycled carbon black obtained by pyrolyzing and purifying products containing carbon black such as tires.

[0127] 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 material. When oxidized and burned by heating in air using a thermogravimetric measurement method conforming to JIS K 6226-2:2003, it refers to carbon black in which the proportion of the mass of the component that does not burn (ash content) is 13% by mass or more. That is, the proportion of the mass of the weight loss (carbon amount) due to the oxidation combustion of the recycled carbon black is 87% by mass or less. Recycled carbon black may also be represented by rCB.

[0128] Recycled carbon black can be obtained from the pyrolysis process of used pneumatic tires. For example, European Patent Application Publication No. 3427975 refers to "Rubber Chemistry and Technology", Vol. 85, No. 3, pages 408-449 (2012), particularly pages 438, 440, and 442, and describes that it can be obtained by pyrolysis of organic materials at 550-800 °C with oxygen excluded, or by vacuum pyrolysis at relatively low temperatures (

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

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

[0129] Recycled carbon black may lack functional groups on its surface, or may be treated to contain functional groups on its surface. The treatment to make the surface of recycled carbon black contain functional groups can be carried out by conventional methods. For example, in European Patent Application Publication No. 3173251, carbon black obtained from a pyrolysis process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl and / or carboxyl groups on its surface. Also, in Patent No. 6856781, carbon black obtained from a pyrolysis process is treated with an amino acid compound containing at least one thiol group or disulfide group to obtain carbon black with an activated surface. The recycled carbon black according to this embodiment also includes carbon black treated to contain functional groups on its surface.

[0130] Recycled carbon black commercially available from companies such as Strable Green Carbon and LDCarbon can be used.

[0131] The regenerated carbon black according to this embodiment preferably contains carbon black having a primary particle diameter of 25 nm or more. By containing carbon black having a primary particle diameter of 25 nm or more, it is considered that the low fuel consumption performance can be improved. In this specification, "containing carbon black having a primary particle diameter of 25 nm or more" means that the integrated particle size (D99) at 99% in the volume integrated particle size distribution of the carbon black is 25 nm or more.

[0132] The carbon black other than the sustainable carbon black is not particularly limited, and for example, those commonly used in the tire industry such as GPF, FEF, HAF, ISAF, and SAF can be used.

[0133] The nitrogen adsorption specific surface area (N2SA) of the carbon black other than the sustainable carbon black is preferably 50 m 2 / g or more, more preferably 80 m 2 / g or more, and even more preferably 100 m 2 / g or more, from the viewpoints of weather resistance and reinforcing properties. Also, 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. The N2SA of the carbon black is measured by the above measurement method.

[0134] The content of the sustainable carbon black with respect to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, from the viewpoint of the effects of the present invention. Also, the content is preferably 50 parts by mass or less, more preferably 35 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less.

[0135] The content of carbon black with respect to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more from the viewpoints of weather resistance and reinforcing property. Further, from the viewpoint of low fuel consumption performance, it is preferably 50 parts by mass or less, more preferably 35 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less.

[0136] (Other fillers) Fillers other than silica and carbon black are not particularly limited, and for example, aluminum hydroxide, alumina (aluminum oxide), calcium carbonate, magnesium sulfate, talc, clay, biochar, etc., which have been conventionally generally used in the tire industry, can be blended. These other fillers may be used alone or in combination of two or more.

[0137] The ratio of the total content of sustainable fillers to the total content of fillers is preferably 0.40 or more, more preferably 0.50 or more, even more preferably 0.60 or more, and particularly preferably 0.70 or more from the viewpoint of environmental load. On the other hand, the upper limit value of the ratio of the total content of sustainable fillers to the total content of fillers is not particularly limited.

[0138] The ratio of the content of carbon black to the content of silica is preferably 0.50 or less, more preferably 0.40 or less, even more preferably 0.30 or less, further more preferably 0.20 or less, and particularly preferably 0.15 or less. By setting the ratio of the content of carbon black to the content of silica 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 content of carbon black to the content of silica is not particularly limited, and for example, it can be 0.01 or more, 0.02 or more, 0.05 or more, and it may also be a filler that does not contain carbon black.

[0139] The total content F of the filler relative to 100 parts by mass of the rubber component is preferably 50 parts by mass or more, more preferably 55 parts by mass or more, further preferably 60 parts by mass or more, still further preferably 65 parts by mass or more, still further preferably 70 parts by mass or more, and particularly preferably 75 parts by mass or more from the viewpoints of ensuring reinforcing properties and damping properties in the tread portion. 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.

[0140] (Silane coupling agent) Silica is preferably used in combination with a silane coupling agent. The silane coupling agent is not particularly limited, and any silane coupling agent conventionally used in combination with silica in the tire industry can be used. However, from the viewpoint of more suitably obtaining the desired effects, one or more silane coupling agents selected from the group consisting of sulfide-based silane coupling agents and mercapto-based silane coupling agents are preferred, and mercapto-based silane coupling agents are more preferred.

[0141] Examples of the sulfide-based silane coupling agent include bis(3-triethoxysilylpropyl)disulfide, bis(3-triethoxysilylpropyl)tetrasulfide, and the like. These sulfide-based silane coupling agents may be used alone or in combination of two or more.

[0142] 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. The mercapto-based silane coupling agent is not particularly limited. For example, it includes 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 more favorably exhibited, a 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 preferable, and a compound represented by the following formula (3) is more preferable. These mercapto-based silane coupling agents may be used alone or in combination of two or more kinds.

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0143] Examples of the compound represented by the formula (2) include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and a compound represented by the following formula (6) (Si363 manufactured by Evonik Degussa), etc. Among them, the compound represented by the following formula (6) can be preferably used. These may be used alone or in combination of two or more.

Chemical formula

[0144] Examples of the compound represented by the formula (3) include 3-octanoylthio-1-propyltriethoxysilane, 3-hexanoylthio-1-propyltriethoxysilane, 3-octanoylthio-1-propyltrimethoxysilane, etc.

[0145] The compound containing the bonding unit A represented by the formula (4) and / or the bonding unit B represented by the formula (5) suppresses the increase in viscosity during processing compared with sulfide-based silane coupling agents such as bis-(3-triethoxysilylpropyl)tetrasulfide. Therefore, it is considered that the dispersibility of silica becomes better, and the low fuel consumption performance, wet grip performance, and elongation at break are further improved. This is probably because the sulfide part of the bonding unit A is a C-S-C bond, which is thermally more stable than tetrasulfide or disulfide, resulting in less increase in Mooney viscosity.

[0146] From the perspective of suppressing the increase in viscosity during processing, the content of the linking unit A is preferably 30 to 99 mol%, more preferably 50 to 90 mol%. Further, the content of the linking unit B is preferably 1 to 70 mol%, more preferably 5 to 65 mol%, and even more preferably 10 to 55 mol%. Also, the total content of the linking units A and B is preferably 95 mol% or more, more preferably 98 mol% or more, and particularly preferably 100 mol%. Note that the contents of the linking units A and B are amounts including the case where the linking units A and B are located at the terminals of the silane coupling agent. The form in the case where the linking units A and B are located at the terminals of the silane coupling agent is not particularly limited as long as it forms units corresponding to the formulas (4) and (5) representing the linking units A and B.

[0147] In a compound containing the linking unit A represented by the formula (4) and the linking unit B represented by the formula (5), the total number of repetitions (x + y) of the number of repetitions (x) of the linking unit A and the number of repetitions (y) of the linking unit B is preferably in the range of 3 to 300. When within this range, the mercaptosilane of the linking unit B can cover -C7H of the linking unit A, so that it is possible to suppress the shortening of the scorch time and ensure good reactivity with silica and rubber components. 15

[0148] Examples of the compound containing the linking unit A represented by the formula (4) and / or the linking unit B represented by the formula (5) include NXT-Z30, NXT-Z45, NXT-Z60, NXT-Z100, etc. manufactured by Momentive. These may be used alone or in combination of two or more.

[0149] ​Silane coupling agents other than sulfide-based silane coupling agents and mercapto-based silane coupling agents are not particularly limited. For example, vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silane coupling agents such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-(2-aminoethyl)aminopropyltriethoxysilane; glycidoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane; etc. 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, Evonik Degussa, etc. can be used.

[0150] From the viewpoint of enhancing 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 even more preferably 5.0 part by mass or more. Also, 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 even more preferably 12 parts by mass or less.

[0151] <Other compounding agents> In addition to the above components, the rubber composition according to this embodiment may appropriately contain compounding agents generally used in the conventional tire industry, such as plasticizers, vulcanized rubber particles, processing aids, waxes, anti-aging agents, stearic acid, zinc oxide, vulcanizing agents, vulcanization accelerators, etc.

[0152] A plasticizer is a material that imparts plasticity to a rubber component, and is a concept that includes both plasticizers that are liquid at 25°C and plasticizers that are solid at normal temperature (25°C). Examples of plasticizers 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 recycled from rubber products or non-rubber products. Also, low-molecular-weight hydrocarbon components obtained by pyrolyzing and extracting used tires or products containing various components may be used as plasticizers. These plasticizers may be used alone or in combination of two or more.

[0153] (Resin component) The resin component is not particularly limited as long as it is a resin component commonly used in the tire industry. For example, tacky 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 can be mentioned. These resin components may be used alone or in combination of two or more.

[0154] The "dicyclopentadiene-based resin" refers to a resin containing cyclopentadiene (CPD) or dicyclopentadiene (DCPD) as a monomer component, and those obtained by hydrogenating or modifying them may also be used. Examples of dicyclopentadiene-based resins include DCPD / C9 resins containing dicyclopentadiene and the C9 fraction described below as monomer components (the DCPD / C9 resins may be those obtained by hydrogenating or modifying them), and DCPD / C9 resins containing dicyclopentadiene and styrene as monomer components are preferred. As dicyclopentadiene-based resins, for example, those commercially available from ExxonMobil, ENEOS Corporation, Nippon Zeon Co., Ltd., Maruzen Petrochemical Co., Ltd., etc. can be used. These dicyclopentadiene-based resins may be used alone or in combination of two or more.

[0155] "Aromatic vinyl resin" refers to a resin containing an aromatic vinyl compound such as styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene, etc. as the monomer component with the highest content, and those that are hydrogenated or modified may also be included. As the aromatic vinyl resin, due to economic reasons, 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 resin, for example, those commercially available from companies such as Kraton, Eastman Chemical, and Mitsui Chemicals can be used. These aromatic vinyl resins may be used alone or in combination of two or more.

[0156] "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, which may be a polymer of the C9 fraction alone or a copolymer obtained by copolymerizing the C9 fraction with other components. For example, a resin obtained by copolymerizing dicyclopentadiene (DCPD) and a C9 fraction is called a DCPD / C9 resin. Also, those that are hydrogenated or modified may be used. Examples of the C9 fraction include petroleum fractions corresponding to 8 to 10 carbon atoms such as vinyltoluene, alkylstyrene, coumarone, indene, methylindene, and dicyclopentadiene. These C9 resins may be used alone or in combination of two or more.

[0157] "C5 resin" refers to a resin obtained by polymerizing a C5 fraction, and those that are hydrogenated or modified may also be used. Examples of the C5 fraction include petroleum fractions corresponding to 4 to 5 carbon atoms such as cyclopentadiene, isoprene, pentane, isopentane, neopentane, pentene, and pentadiene. These C5 resins may be used alone or in combination of two or more.

[0158] The term "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and it may be hydrogenated or modified. As the C5C9 petroleum resin, for example, those commercially available from Tosoh Corporation, LUHUA, etc. can be used. These C5C9 resins may be used alone or in combination of two or more.

[0159] The term "terpene resin" refers to a resin containing terpene compounds such as α-pinene, β-pinene, limonene, dipentene, etc. as the monomer component with the highest content, and it may be hydrogenated or modified. Specific examples of terpene resins include, for example, 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 serving as monomer components of aromatic modified terpene resins include styrene, α-methylstyrene, vinyltoluene, divinyltoluene, etc. Examples of phenolic compounds serving as monomer components of terpene phenol resins include phenol, bisphenol A, cresol, xylenol, etc. These terpene resins may be used alone or in combination of two or more.

[0160] The term "rosin resin" refers to a resin containing rosin acid compounds such as abietic acid, neoabietic acid, palustric acid, isopimaric acid, etc., and it may be hydrogenated or modified. The rosin resin is not particularly limited, and examples include natural resin rosin, rosin modified resins modified by hydrogenation, disproportionation, dimerization, esterification, etc. These rosin resins may be used alone or in combination of two or more.

[0161] The term "phenolic resin" refers to a resin containing a phenolic compound such as phenol or cresol as the monomer component with the highest content. The phenolic resin is not particularly limited, and examples thereof include phenol formaldehyde resin, alkylphenol formaldehyde resin, alkylphenol acetylene resin, oil-modified phenol formaldehyde resin, and the like. These phenolic resins may be used alone or in combination of two or more.

[0162] From the viewpoint 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 viewpoints of processability and improvement of the dispersibility of the rubber component and the filler, it is preferably 150°C or lower, more preferably 140°C or lower, and still more preferably 130°C or lower. The softening point of the resin component is measured by the above measurement method.

[0163] When the resin component is contained, the content thereof with respect to 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and still more preferably 15 parts by mass or more. Further, from the viewpoint of suppressing heat generation, it is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 40 parts by mass or less, and particularly preferably 30 parts by mass or less.

[0164] (Oil) Examples of the oil include mineral oil, vegetable oil, animal oil, and the like. Further, from the viewpoint of life cycle assessment, waste oil after use in a rubber mixer or an engine, or refined waste cooking oil used in a cooking shop may be used.

[0165] In this specification, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oil (mineral oil), naphthenic oil, aromatic oil, etc. Specific examples of mineral oil include, for example, MES (Mild Extracted Solvate), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), RAE (Residual Aromatic Extract), etc. Also, oils with a low content of polycyclic aromatic (polycyclic aromatic compound: PCA) compounds can be used for environmental protection. Examples of the low-PCA-content oil include MES, TDAE, heavy naphthenic oil, etc.

[0166] In this specification, "vegetable oil" refers to, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice bran oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grape seed oil, wood rosin, etc. Furthermore, vegetable oils include refined oils (such as salad oil) obtained by refining the above oils, transesterified oils obtained by transesterifying the above oils, hydrogenated oils obtained by hydrogenating the above oils, thermally polymerized oils obtained by thermally polymerizing the above oils, oxidation-polymerized oils obtained by oxidizing the above oils, waste cooking oils recovered from those used as edible oils, etc. Note that vegetable oil may be liquid or solid at room temperature (25°C). These vegetable oils may be used alone or in combination of two or more.

[0167] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably contains triacylglycerol. In this specification, acylglycerol refers to a compound in which the hydroxy group of glycerin and a fatty acid are ester-bonded. The acylglycerol is not particularly limited, and may be any of 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, and triacylglycerol. Furthermore, the acylglycerol may be a monomer, a dimer, or a multimer of trimer or higher. Note that acylglycerols of dimer or higher can be obtained by thermal polymerization, oxidative polymerization, or the like. Also, the acylglycerol may be liquid or solid at normal temperature (25°C).

[0168] As a method for confirming whether the acylglycerol is contained in the rubber composition, it is not particularly limited, but for example, the following 1 can be confirmed by 1H-NMR measurement. Specifically, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at normal temperature (25°C) for 24 hours. After removing the rubber composition, 1 1H-NMR is measured. When the signal of tetramethylsilane (TMS) is set to 0.00 ppm, signals around 5.26 ppm, around 4.28 ppm, and around 4.15 ppm are observed, and these signals are presumed to be signals derived from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In this paragraph, "around" means a range of ±0.10 ppm.

[0169] The fatty acid is not particularly limited and may be an unsaturated fatty acid or a saturated fatty acid. Examples of the unsaturated fatty acid include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of the saturated fatty acid include butyric acid and lauric acid.

[0170] Among them, as the fatty acid, it is desirable to contain a fatty acid with few double bonds, that is, a saturated fatty acid or a monounsaturated fatty acid, and oleic acid is preferred. As the vegetable oil containing such a fatty acid, for example, a vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid may be used, or a vegetable oil subjected to modification such as transesterification may be used. Further, in order to produce a vegetable oil containing such a fatty acid, plants may be improved by variety improvement, genetic recombination, or the like.

[0171] As the vegetable oil, for example, those commercially available from Idemitsu Kosan Co., Ltd., Sankyo Oil Chemical Co., Ltd., ENEOS Co., Ltd., Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0172] Examples of the animal oil include fish oil, beef tallow, or oleyl alcohol that can be derived therefrom.

[0173] The content of the oil with respect to 100 parts by mass of the rubber component (the total amount of all when using a plurality of oils in combination) is preferably 1 part by mass or more, more preferably 3 parts by mass or more, further preferably 5 parts by mass or more, still further preferably 10 parts by mass or more, and particularly preferably 15 parts by mass or more from the viewpoint of processability. Further, from the viewpoint of improving the wear resistance performance, it is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, further preferably 30 parts by mass or less, and particularly preferably 25 parts by mass or less.

[0174] The liquid rubber is not particularly limited as long as it is a polymer in a liquid state at room temperature (25 ° C). Examples thereof include liquid butadiene rubber (liquid BR), liquid styrene-butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene-isoprene rubber (liquid SIR), liquid farnesene rubber, and the like. These liquid rubbers may be used alone or in combination of two or more.

[0175] Examples of ester plasticizers include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), bis(2-ethylhexyl) azelate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), trixylenyl phosphate (TXP), and the like. These ester plasticizers may be used alone or in combination of two or more.

[0176] The content of the plasticizer relative to 100 parts by mass of the rubber component (when a plurality of plasticizers are used in combination, the total amount of all) is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, still more preferably 30 parts by mass or more, and particularly preferably 35 parts by mass or more. Also, the content is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, still more preferably 60 parts by mass or less, and particularly preferably 50 parts by mass or less.

[0177] Vulcanized rubber particles are particles made of vulcanized rubber. Specifically, rubber powder etc. specified in JIS K 6316:2017 can be used. From the viewpoints of environmental consideration and cost, recycled rubber powder produced from crushed waste tires etc. is preferable. These may be used alone or in combination of two or more.

[0178] The vulcanized rubber particles are not particularly limited, and may be non-modified vulcanized rubber particles or modified vulcanized rubber particles. As commercially available products of vulcanized rubber, for example, products of Lehigh, Murakami Rubber Industry Co., Ltd. etc. can be used.

[0179] When containing vulcanized rubber particles, the content relative to 100 parts by mass of the rubber component can be appropriately adjusted, for example, in the range of more than 1 part by mass and less than 80 parts by mass.

[0180] Examples of processing aids 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, and the like. As the processing aids, those commercially available from, for example, Schill+Seilacher, Performance Additives, etc. can be used. These processing aids may be used alone or in combination of two or more.

[0181] When containing a processing aid, the content thereof with respect to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 1 part by mass, and still more preferably more than 1.5 parts by mass from the viewpoint of exerting the effect of improving processability. Also, from the viewpoints of abrasion resistance and fracture strength, it is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and still more preferably less than 5.0 parts by mass.

[0182] The wax is not particularly limited, and any of those usually used in the tire industry can be preferably used. Examples thereof include mineral waxes and plant-derived waxes. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Plant-derived waxes refer to waxes derived from natural resources such as plants. Among them, mineral waxes are preferred. Examples of plant-derived waxes include rice wax, carnauba wax, candelilla wax, etc. Examples of mineral waxes include paraffin wax, microcrystalline wax, and these selected special waxes, and paraffin wax is preferred. Note that the wax according to this embodiment does not contain stearic acid. As the wax, those commercially available from, for example, Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelto Co., Ltd., etc. can be used. These waxes may be used alone or in combination of two or more.

[0183] When contained, the content relative to 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1.0 part by mass or more, and still more preferably 1.5 part by mass or more from the viewpoint of the weather resistance of the rubber. Also, from the viewpoint of preventing whitening of the tire due to blooming, it is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less.

[0184] The antioxidant is not particularly limited, but naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-ditoly-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), N,N'-di-2-naphthyl-p-phenylenediamine (DNPD) and other p-phenylenediamine-based antioxidants; 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; bis, tris, polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane and the like. Among them, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and polymers of 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. As commercial products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexsys Co., Ltd. and the like can be used. These antioxidants may be used alone or in combination of two or more.

[0185] When contained, the content relative to 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1.0 part by mass or more, and still more preferably 1.5 part by mass or more from the viewpoint of ozone crack resistance of the rubber. Also, from the viewpoints of abrasion resistance performance and wet grip performance, it is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0186] When contained, the content relative to 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1.0 part by mass or more, and still more preferably 1.5 part by mass or more from the viewpoint of processability. Also, from the viewpoint of vulcanization rate, it is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0187] When contained, the content relative to 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1.0 part by mass or more, and still more preferably 1.5 part by mass or more from the viewpoint of processability. Also, from the viewpoint of abrasion resistance performance, it is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0188] Sulfur is preferably used as the vulcanizing agent. As the sulfur, powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, etc. can be used.

[0189] When the vulcanizing agent contains sulfur, the content relative to 100 parts by mass of the rubber component is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and still more preferably 1.0 part by mass or more from the viewpoint of ensuring a sufficient vulcanization reaction. Also, from the viewpoint of deterioration prevention, it is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and still more preferably 3.5 parts by mass or less. Note that 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.

[0190] Examples of vulcanizing agents other than sulfur include alkylphenol sulfur chloride condensates, sodium 1,6 - hexamethylene - dithiolsulfate dihydrate, 1,6 - bis(N,N’ - dibenzylthiocarbamoyldithio)hexane, and the like. As these vulcanizing agents other than sulfur, those commercially available from companies such as Tago Chemical Industry Co., Ltd., Rancess Co., Ltd., and Flexis Co., Ltd. can be used.

[0191] Examples of vulcanization accelerators include sulfenamide - type vulcanization accelerators, thiazole - type vulcanization accelerators, guanidine - type vulcanization accelerators, thiuram - type vulcanization accelerators, dithiocarbamate - type vulcanization accelerators, caprolactam disulfide, and the like. These vulcanization accelerators may be used alone or in combination of two or more. Among them, from the viewpoint of more preferably obtaining the desired effect, one or more vulcanization accelerators selected from the group consisting of sulfenamide - type vulcanization accelerators, thiazole - type vulcanization accelerators, and guanidine - type vulcanization accelerators are preferred, and it is more preferred to use sulfenamide - type vulcanization accelerators and guanidine - type vulcanization accelerators in combination.

[0192] Examples of sulfenamide - type vulcanization accelerators 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.

[0193] Examples of thiazole - type vulcanization accelerators include 2 - mercaptobenzothiazole (MBT) or its salts, di - 2 - benzothiazolyldisulfide (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.

[0194] Examples of guanidine-based vulcanization accelerators include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of dicatecholborate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, 1,3-di-o-cumenyl-2-propionylguanidine, and the like. Among them, DPG is preferred.

[0195] When containing a vulcanization accelerator, the content relative to 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1.0 part by mass or more, and still more preferably 1.5 part by mass or more. Also, 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 still more preferably 4.0 parts by mass or less. By setting the content of the vulcanization accelerator within the above range, the breaking strength and elongation tend to be ensured.

[0196] In this specification, various materials containing carbon atoms (such as rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from carbon dioxide in the atmosphere. As a method for obtaining the various materials from carbon dioxide, the carbon dioxide may be directly converted, or the methane obtained through the methanation process of synthesizing methane from carbon dioxide may be converted.

[0197] [Manufacture of Rubber Composition and Tire] The rubber composition according to this embodiment can be manufactured by a known method. For example, it can be manufactured by kneading the above-mentioned respective components using a rubber kneading device such as an open roll, a closed kneader (Banbury mixer, kneader, etc.).

[0198] The kneading process includes, for example, a base kneading process of kneading compounding agents and additives other than the vulcanizing agent and the vulcanization accelerator, and a final kneading (F kneading) process of adding the vulcanizing agent and the vulcanization accelerator to the kneaded product obtained in the base kneading process and kneading them. Further, the base kneading process can be divided into a plurality of processes if desired.

[0199] Although the kneading conditions are not particularly limited, for example, in the base kneading step, kneading is performed at a discharge temperature of 150 to 170°C for 3 to 10 minutes, and in the final kneading step, kneading is performed at 70 to 110°C for 1 to 5 minutes. The vulcanization conditions are not particularly limited, and for example, a method of vulcanizing at 150 to 200°C for 10 to 30 minutes can be mentioned.

[0200] A tire provided with a tread portion composed of the rubber composition can be manufactured by a usual method. That is, an unvulcanized rubber composition in which each of the above components is blended as necessary with respect to the rubber component is extruded according to the shape of the first layer of the tread portion, and is bonded together with the inner rubber layer of the tread portion and other tire members on a tire molding machine, and molded by a usual method to form an unvulcanized tire. The tire can be manufactured by heating and pressurizing this unvulcanized tire in a vulcanizer. The vulcanization conditions are not particularly limited, and for example, a method of vulcanizing at 150 to 200°C for 10 to 30 minutes can be mentioned.

[0201] [Use of the tire] The tire according to the present embodiment can be suitably used for passenger car tires, truck / bus tires, motorcycle tires, and racing tires, and among them, it is preferably used for passenger car tires. Note that a passenger car tire is a tire assumed to be mounted on an automobile that runs on four wheels, and refers to a tire having a maximum load capacity of 1000 kg or less.

Examples

[0202] Hereinafter, examples (Examples) considered to be preferable in carrying out the invention are shown, but the scope of the present invention is not limited to the examples. Using the various chemicals shown below, tires having the first layer of the tread portion obtained according to the formulations in Tables 1 and 2 were examined, and the results calculated based on the following evaluation methods are shown in Tables 1 and 2.

[0203] Hereinafter, the various chemicals used in the examples and comparative examples are collectively shown. NR:TSR20 SBR1: EUROPRENE® SOL R C2525 manufactured by Versalis (styrene content: 26% by mass, vinyl content: 24% by mass, Mw: 600,000, non-oil product) SBR2: T3830 manufactured by Asahi Kasei Corporation (styrene content: 33% by mass, vinyl content: 34% by mass, Mw: 950,000, non-oil product) BR: CB24 manufactured by Lanxess Corporation (BR synthesized using Nd-based catalyst, cis content: 96 mol%, Mw: 500,000) Carbon black: SHOW BLACK N220 manufactured by Cabot Japan Ltd. (N2SA: 111 m 2 / g) Silica: ULTRASIL® VN3 manufactured by Evonik Degussa GmbH (N2SA: 175 m 2 / g, average primary particle size: 17 nm) Sustainable filler 1: SS550 manufactured by Streble Green Carbon (carbon black obtained from the thermal decomposition process of tires) Sustainable filler 2: Rice husk-derived silica obtained by the following production example (N2SA: 175 m 2 / g, average primary particle size: 18 nm) Sustainable filler 3: Rice husk-derived silica obtained by the following production example (N2SA: 235 m 2 / g, average primary particle size: 15 nm) Silane coupling agent 1: Si266 manufactured by Evonik Degussa GmbH (bis(3-triethoxysilylpropyl) disulfide) Silane coupling agent 2: NXT-Z45 manufactured by Momentive (mercapto group-based silane coupling agent, copolymer of bonding unit A and bonding unit B (bonding unit A: 55 mol%, bonding unit B: 45 mol%)) Oil: VivaTec500 manufactured by H&R (TDAE oil) Resin component: Oppera PR395 manufactured by ExxonMobil (hydrogenated DCPD / C9 resin, softening point: 118 °C) Wax: Oz Ace 0355 of Nippon Seiro Co., Ltd. (paraffin wax) Anti-aging agent: Nocrack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Zinc oxide: Zinc white No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Bead stearic acid camellia manufactured by NOF Corporation Sulfur: HK-200-5 (powder sulfur containing 5% oil) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator: Noxeller CZ (N-cyclohexyl-2-benzothiazolylsulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0204] (Production examples of sustainable fillers 2 and 3) Add rice husk ash to an aqueous sodium hydroxide solution and heat and stir with a stirring rod. Then, let it return to room temperature, centrifuge to precipitate carbon components, and filter the supernatant through a Kiriyama funnel. Further, add water to the precipitate, stir, centrifuge again, filter the supernatant with a Kiriyama funnel, and mix this filtrate with the previous filtrate. Then, dilute this mixed filtrate with water to obtain an aqueous sodium silicate solution.

[0205] Take out a part of the aqueous sodium silicate solution, dilute it with pure water, then adjust the pH to 2 - 4 by adding 1 mol / L sulfuric acid, and then heat. Next, add the remaining part of the aqueous sodium silicate solution to adjust the pH to 8 - 10, heat further, and dilute this with pure water to obtain a seed solution.

[0206] Heat and stir the seed solution, and simultaneously dropwise add the remaining aqueous sodium silicate solution and 1 mol / L sulfuric acid thereto, and stir while adjusting the pH to the range of 8 - 11. After the dropping of the aqueous sodium silicate solution is completed, continue dropping only 1 mol / L sulfuric acid at the same rate and finish dropping at a predetermined pH (1.5 - 6). Filter the white precipitate formed after the dropping is completed through a Kiriyama funnel, and wash the filtrate with water. Repeat this once again, dry the filtrate, and obtain sustainable filler 2.

[0207] Further, by adjusting the amount of 1 mol / L sulfuric acid dropped into the seed solution and changing the pH value after the dropping is completed, a sustainable filler 3 is obtained.

[0208] (Examples and Comparative Examples) According to the compounding formulations shown in Tables 1 and 2, using a 1.7 L sealed Banbury mixer, chemicals other than sulfur and vulcanization accelerators are kneaded for 1 to 10 minutes until the discharge temperature reaches 150 to 160 °C to obtain a kneaded product. Next, using a twin-screw open roll, sulfur and vulcanization accelerators are added to the kneaded product and kneaded for 4 minutes until it reaches 105 °C to obtain an unvulcanized rubber composition. Using the unvulcanized rubber composition, it is extruded and molded into the shape of the first layer (thickness: 5 mm) of the tread part using an extruder equipped with a die of a predetermined shape, and bonded together with the second layer (thickness: 2 mm) of the tread part and other tire members to produce an unvulcanized tire, which is press-vulcanized at 170 °C for 12 minutes to obtain each test tire described in Tables 1 and 2.

[0209] <Measurement of tanδ at 30 °C and E* at 30 °C> For each vulcanized rubber test piece produced by cutting out from the inside of the first layer of the tread part of each test tire, with the tire circumferential direction as the long side and the tire radial direction as the thickness direction, having a length of 20 mm × width of 4 mm × thickness of 1 mm, using a dynamic viscoelasticity measuring device (Epsilon 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 an elongation mode, the loss tangent tanδ and the complex elastic modulus E* are measured.

[0210] <Tensile Test> For a dumbbell-shaped No. 7 test piece cut out with a thickness of 1 mm from the inside of the first and second layers of the tread part of each test tire, with the tire circumferential direction as the tensile direction and the tire radial direction as the thickness direction, in accordance with JIS K 6251:2017, in an atmosphere of 23 °C, a tensile test is carried out under the condition of a tensile speed of 3.3 mm / second, and the modulus (M 200 )(MPa) at 200% elongation is measured.

[0211] <Low Fuel Consumption Performance> Using a rolling resistance tester, the rolling resistance was measured when each test tire was run at an internal pressure of (230 kPa), a load of (3.43 kN), and a speed of (80 km / h), and is expressed as an index with the reference comparative example (Comparative Example 1 in Table 1, Comparative Example 5 in Table 2) set to 100. The larger the index, the smaller the rolling resistance, indicating excellent low fuel consumption performance.

[0212] <Wear resistance performance> Each test tire was mounted on a domestic FF vehicle, the groove depth of the tread part was measured after a driving distance of 8000 km, the driving distance when the tire groove depth decreased by 1 mm was calculated, and it is expressed as an index with the reference comparative example (Comparative Example 1 in Table 1, Comparative Example 5 in Table 2) set to 100. The larger the index, the better the wear resistance performance.

[0213] <Comprehensive performance> The total value of the above low fuel consumption index and wear resistance performance index is shown as the comprehensive performance index.

[0214]

Table 1

[0215]

Table 2

[0216] <Embodiment> Examples of embodiments of the present invention are shown below.

[0217] 〔1〕A tire having a tread portion with at least one rubber layer, wherein the ratio of the tire weight G (kg) to the maximum load capacity W L (kg) of the tire (G / W L) is 0.0170 or less, the first layer constituting the tread surface is composed of a rubber composition containing a rubber component and a filler, the filler includes a sustainable filler, when the land ratio at the grounding surface of the tread portion is R, and the total content of the filler with respect to 100 parts by mass of the rubber component in the rubber composition is F (parts by mass), a tire in which the product (R×F) of R and F exceeds 42.0 (preferably exceeds 44.0, more preferably exceeds 46.0 and is less than 75.0). 〔2〕The tire according to 〔1〕 above, wherein the sustainable filler includes silica made from a biomass material. 〔3〕The tire according to 〔1〕 or 〔2〕 above, wherein the sustainable filler includes recycled carbon black. 〔4〕G / W L is 0.0135 or less, the tire according to any one of 〔1〕 to 〔3〕 above. 〔5〕The tire according to any one of 〔1〕 to 〔4〕 above, wherein the 30 °C tanδ of the rubber composition is 0.20 or less. 〔6〕(R×F) / (G / W L ) exceeds 3000, the tire according to any one of 〔1〕 to 〔5〕 above. 〔7〕When the complex elastic modulus of the rubber composition at 30 °C is 30 °C E* (MPa), the product (R×30 °C E*) of R and 30 °C E* exceeds 2.5, the tire according to any one of 〔1〕 to 〔6〕 above. 〔8〕The tire according to any one of 〔1〕 to 〔7〕 above, wherein the total styrene amount S in the rubber component is 25% by mass or less. 〔9〕The tire according to 〔8〕 above, wherein R×S is 15.0 or less. 〔10〕When the complex elastic modulus of the rubber composition at 30 °C is 30 °C E* (MPa), S / 30 °C E* is 6.0 or less (preferably 5.5 or less, more preferably 0.3 or more and 5.0 or less), the tire according to 〔8〕 or 〔9〕 above. 〔11〕The tire according to any one of 〔1〕 to 〔10〕 above, wherein the rubber component includes an isoprene-based rubber. 〔12〕The tire according to any one of 〔1〕 to 〔11〕 above, wherein the rubber component includes a styrene-butadiene rubber having a styrene content of 30% by mass or less. Let M be the modulus at 200% elongation of the rubber composition 200 (MPa). When the M of the rubber composition 200 , 30°C E*, and 30°C tan δ satisfy the following formula (1), the tire according to any one of the above [1] to

[12] . M 200 × 30°C E* / 30°C tan δ ≥ 100 ··· (1)

Claims

1. A tire having a tread portion with at least one rubber layer, Ratio (G / W) of tire weight G (kg) to maximum load capacity W of tire L (kg) is 0.0170 or less, L and wherein a first layer constituting a tread surface is composed of a rubber composition containing a rubber component and a filler, the filler includes a sustainable filler, when a land ratio at a grounding surface of the tread portion is R and a total content of the filler relative to 100 parts by mass of the rubber component in the rubber composition is F (parts by mass), a product (R×F) of R and F is more than 42.

0.

2. The tire according to claim 1, wherein the sustainable filler includes silica made from a biomass material.

3. The tire according to claim 1, wherein the sustainable filler includes recycled carbon black.

4. G / W L The tire according to any one of claims 1 to 3, wherein L is 0.0135 or less.

5. The tire according to any one of claims 1 to 3, wherein a 30°C tanδ of the rubber composition is 0.20 or less.

6. (R × F) / (G / W L ) is more than 3000, the tire according to any one of claims 1 to 3.

7. The tire according to any one of claims 1 to 3, when a complex elastic modulus at 30°C of the rubber composition is 30°C E* (MPa), a product (R×30°C E*) of R and 30°C E* is more than 2.

5.

8. The tire according to any one of claims 1 to 3, wherein a total styrene amount S in the rubber component is 25% by mass or less.

9. The tire according to claim 8, wherein R×S is 15.0 or less.

10. The tire according to claim 8, when a complex elastic modulus at 30°C of the rubber composition is 30°C E* (MPa), S / 30°C E* is 6.0 or less.

11. The tire according to any one of claims 1 to 3, wherein the rubber component includes an isoprene-based rubber.

12. The tire according to any one of claims 1 to 3, wherein the rubber component includes a styrene-butadiene rubber having a styrene content of 30% by mass or less.

13. Let the modulus at 200% elongation of the rubber composition be M 200 (MPa), then the M of the rubber composition 200 , the 30°C E*, and the 30°C tanδ satisfy the following formula (1). The tire according to any one of claims 1 to 3 M 200 M×30°C E* / 30°C tan δ ≥ 100...(1)

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