tire

Abstract

To provide a tire which can be improved in overall performance, namely wet grip performance, dry grip performance and low fuel consumption performance.SOLUTION: A rubber composition contains filler of 45 pts.mass with respect to rubber component of 100 pts.mass, and when the maximum load capacity of a tire is denoted as WL(kg), weight of the tire is denoted as G(kg), land ratio of ground contact surface of a tread portion is denoted as R, complex elastic modulus at 30°C in drying time of the rubber composition is denoted as 30°CE*D(MPa), complex elastic modulus at 30°C in water wet time of the rubber composition is denoted as 30°CE*W(MPa), tanδ at 30°C in drying time of the rubber composition is denoted as 30°CtanδD and tanδ at 30°C in wet time of the rubber composition is denoted as 30°CtanδW, the WL, G, R, 30°CE*D, 30°CE*W, 30°CtanδD and 30°CtanδW satisfy a specific equation.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] Due to the technical improvement of the tread rubber composition using silica, the wet grip performance of tires has been greatly improved (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] On the other hand, regarding the change in grip performance when a road surface change occurs, such as from a dry road surface to a wet road surface or from a wet road surface to a dry road surface, it remains an important technical issue and there is room for improvement.

[0005] As another method for improving wet grip performance, there is a method of blending a plasticizer into the tread rubber composition to soften the rubber. However, when the tread rubber is softened, there is a problem that the low fuel consumption performance on a dry road surface deteriorates.

[0006] An object of the present invention is to provide a tire capable of improving the overall performance of wet grip performance, dry grip performance, and low fuel consumption performance.

Means for Solving the Problems

[0007] The present invention relates to a tire having a tread portion with at least one rubber layer, wherein a first layer constituting a tread surface is composed of a rubber composition containing a rubber component and a filler, the rubber composition contains 45 parts by mass or more of the filler with respect to 100 parts by mass of the rubber component, and a maximum load capacity of the tire is W L (kg), a weight of the tire is G (kg), a land ratio at a ground contact surface of the tread portion is R, a complex elastic modulus at 30°C when the rubber composition is dry is 30°C E* D (MPa), a complex elastic modulus at 30°C when the rubber composition is wet with water is 30°C E* W (MPa), a tanδ at 30°C when the rubber composition is dry is 30°C tanδ D , a tanδ at 30°C when the rubber composition is wet with water is 30°C tanδ W , in the case where W L , G, R, 30°C E* D , 30°C E* W , 30°C tanδ D , and 30°C tanδ W satisfy the following formulas (1) to (6). R ≧ 0.50 ···(1) G / W L ≦ 0.025 ···(2) |30°C E* D - 30°C E* W | ≧ 1.3 ···(3) |30°C tanδ D - 30°C tanδ W | ≧ 0.03 ···(4) |30°C E* D - 30°C E* W | × R ≧ 0.70 ···(5) |30°C tanδ D - 30°C tanδ W | / (G / W L ) ≧ 1.3 ···(6)

Advantages of the Invention

[0008] According to the present invention, there is provided a tire capable of improving the overall performance of wet grip performance, dry grip performance, and low fuel consumption performance.

[0009] In the tire according to the present invention, although not intending to be bound by theory, the reasons for the improvement in the overall performance of wet grip performance, dry grip performance, and low fuel consumption performance are considered as follows.

[0010] The tire according to the present invention contributes to improving the grip force by ensuring drainage by setting the land ratio R to 0.50 or more. Further, (2) by setting G / W L to 0.025 or less and reducing the weight of the tire, it contributes to improving the low fuel consumption performance.

[0011] Further, by using, as the rubber composition constituting the first layer constituting the tread surface, a rubber composition in which the complex elastic modulus and tanδ change reversibly with water, the wet grip performance and the dry grip performance can be improved synergistically. Specifically, (3) by making the difference between 30°C E* D and 30°C E* W a certain value or more, it is considered that it can be made soft in a wet environment and the contact area with the road surface during wet can be improved while maintaining dry grip and handling stability. Further, (4) by making the difference between 30°C tanδ D and 30°C tanδ W a certain value or more, it is considered that the grip force can be improved while maintaining the normal low fuel consumption performance.

[0012] Furthermore, (5) by making the product of |30°C E* D -30°C E* W | and R a certain value or more, when the difference between 30°C E* D and 30°C E* W is small, it is considered that by increasing R, the contact area with the road surface can be increased and the influence of the change in rubber can be increased. Also, (6) by making the ratio of |30°C tanδ L to G / W D -30°C tanδ W | a certain value or more, when the difference between 30°C tanδ D and 30°C tanδ W is small, G / WL It is considered that by reducing [it], the grip force can be improved while maintaining low fuel consumption performance.

[0013] And, it is considered that the above (1) to (6) cooperate to achieve a remarkable effect that the overall performance of wet grip performance, dry grip performance, and low fuel consumption performance is improved.

Embodiments for Carrying Out the Invention

[0014] A tire according to an embodiment of the present invention is a tire provided with a tread portion having at least one rubber layer, wherein a first layer constituting the tread surface is composed of a rubber composition containing a rubber component and a filler, the rubber composition contains 45 parts by mass or more of the filler with respect to 100 parts by mass of the rubber component, the maximum load capacity of the tire is W L (kg), the weight of the tire is G (kg), the land ratio at the ground contact surface of the tread portion is R, the complex elastic modulus of the rubber composition at 30°C when dry is 30°C E* D (MPa), the complex elastic modulus of the rubber composition at 30°C when water-wetted is 30°C E* W (MPa), the tanδ of the rubber composition at 30°C when dry is 30°C tanδ D , the tanδ of the rubber composition at 30°C when water-wetted is 30°C tanδ W In the case where it is, W L , G, R, 30°C E* D , 30°C E* W , 30°C tanδ D , and 30°C tanδ W is a tire that satisfies the following formulas (1) to (6). R≧0.50 ···(1) G / W L ≦0.025 ···(2) |30°C E* D -30°C E* W |≧1.3 ···(3) |30°C tanδ D -30°C tanδ W |≧0.03 ···(4) |30°C E*D -30 °C E* W |×R ≥ 0.70 ···(5) |30 °C tanδ D -30 °C tanδ W | / (G / W L ) ≥ 1.3 ···(6)

[0015] From the perspective of improving grip performance, it is preferable that the rubber composition contains 40 parts by mass or more of silica with respect to 100 parts by mass of the rubber component.

[0016] From the perspective of increasing the specific surface area of the silica, increasing the interaction with the rubber component, suppressing the movement of molecular chains, and suppressing heat generation, the average primary particle diameter of the silica is preferably 20 nm or less.

[0017] From the perspective of softening the rubber and improving the followability to the road surface, it is preferable that the rubber composition contains 5 parts by mass or more of a plasticizer with respect to 100 parts by mass of the rubber component.

[0018] From the perspective of improving grip performance, the plasticizer preferably contains at least one selected from the group consisting of a resin component and a liquid polymer.

[0019] From the perspective of improving wear resistance performance, it is preferable that the rubber component contains 10 mass% or more of butadiene rubber.

[0020] From the perspective of ensuring reinforcement, the sulfur content in the rubber composition is preferably 0.1 mass% or more.

[0021] From the perspective of low-temperature embrittlement, the glass transition temperature of the rubber composition is preferably -10 °C or lower.

[0022] The 30 °C E* of the rubber composition D is preferably 3.0 MPa or more from the perspective of ensuring handling stability performance.

[0023] The 30 °C tanδ of the rubber composition DFrom the perspective of dry grip performance, it is preferably 0.10 or more.

[0024] <Definition> The "tread portion" is the part that forms the contact surface of the tire. In the radial cross-section of the tire, when the tire skeleton is formed by members such as steel and textile materials like the belt layer, belt reinforcing layer, and carcass layer, it is the member outside these in the radial direction of the tire.

[0025] The "belt layer" is a layer provided outside the carcass layer in the radial direction of the tire. It corresponds to a plurality of working layers in which the internal reinforcing material is inclined about 18 - 30° with respect to the circumferential direction of the tire and overlaps in the reverse direction, or a circumferential belt layer in which the internal reinforcing material is oriented at an angle of ±10° with respect to the circumferential direction of the tire.

[0026] The "normal state" means a no-load state in which the tire is mounted on a normal rim and filled with air at normal internal pressure.

[0027] 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 values specified in a state where the cut tire piece is held at the rim width of the normal rim, for example, by cutting the tire with a plane including the tire rotation axis.

[0028] "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 minimum-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).

[0029] "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, it must be 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.

[0030] The "normal load" is the load defined for each tire in a standard system including 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"; 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, similar to the case of the normal rim and normal internal pressure. When there is an applicable size during the reference, follow the corresponding standard. For tires not defined in the above standards, the maximum load capacity W L calculated separately is taken as the normal load.

[0031] 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 cross-section of the tire by the plane including the tire rotation axis in the tire radial direction (mm), and "Wt" is the cross-sectional width of the tire in the normal state (mm). When R is the rim diameter of the tire, Ht can be obtained by (Dt - R) / 2. Wt is the value obtained after removing patterns, characters, etc. on the tire sidewall. Note that the maximum load capacity is synonymous with the above normal load.

[0032]

Equation

[0033] 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 normal rim, loading the normal internal pressure, and leaving it static at 25°C for 24 hours, apply ink to the tire tread surface, load the normal load (maximum load capacity) on the tire, and press it vertically against thick paper (the camber angle is 0°) to transfer the ink. 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.

[0034] 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 a 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, and the tire is loaded with the standard load (maximum load capacity) and pressed vertically against thick paper (the camber angle is 0°) to transfer the ink, thereby obtaining it. The area of the effective contact area is referred to as 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.

[0035] 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)

[0036] "Reversibly changed by water" means that the physical properties of the vulcanized rubber composition change reversibly due to the presence of water. For example, when it changes as dry → water-wet → dry, it is sufficient if the physical properties change reversibly, and it is not necessarily required to have the same physical properties at the previous dry time and the subsequent dry time.

[0037] 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 a plasticizer that is liquid (liquid state) at 25°C and a plasticizer that is solid at 25°C. However, it is assumed that waxes and stearic acid commonly used in the tire industry are not included.

[0038] The "content of plasticizer" also includes the amount of plasticizer contained in the extended rubber component previously extended 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 extended component is oil, the extended oil is included in the content of oil.

[0039] <Measurement method> "30°C E*" is the complex elastic modulus measured under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of ±1%, and an elongation mode using a dynamic viscoelasticity measuring device (for example, the Implex series manufactured by GABO). The sample for 30°C E* measurement is a vulcanized rubber composition with a length of 20 mm × width of 4 mm × thickness of 1 mm. When it is produced by cutting from a tire, it is cut from the tread part of the tire such that the tire circumferential direction is the long side and the tire radial direction is the thickness direction. 30°C E* W The sample for measurement is obtained by immersing the vulcanized rubber test piece in water at 25°C for 12 hours. Also, 30°C E* D The sample for measurement is obtained by subjecting the water-moistened vulcanized rubber composition to vacuum drying under the conditions of 80°C and 1 kPa or less until a constant weight is achieved.

[0040] "30°C tanδ" 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). 30°C tanδ W and 30°C tanδ D The sample for measurement is the same as that for 30°C E* W and 30°C E* D is produced in the same manner.

[0041] "The glass transition temperature (Tg) of the rubber composition" is the temperature (tanδ peak temperature) corresponding to the maximum value within the range of -60°C or higher and 40°C or lower of the temperature distribution curve of tanδ measured under the conditions of a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±0.5%, and a heating rate of 2°C / min using a dynamic viscoelasticity measuring device (for example, the Implex series manufactured by GABO). In the measurement within the range of -60 to 40°C, when the tanδ value continuously increases or decreases with the increase in temperature, the glass transition temperature of the rubber composition is 40°C or -60°C, respectively. Also, when there are two or more points showing a maximum value within the range of -60°C or higher and 40°C or lower, the point with the lowest temperature is taken as the glass transition temperature.

[0042] The "sulfur content" is the sulfur content (mass %) measured by the oxygen combustion flask method in accordance with JIS K 6233:2016. The sample for sulfur content measurement is a vulcanized rubber composition with a length of 20 mm, a width of 4 mm, and a thickness of 1 mm. When 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.

[0043] The "styrene content" is 1 a value calculated by 1H-NMR measurement and is applicable to rubber components having repeating units derived from styrene such as SBR, for example.

[0044] The "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.

[0045] The "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.

[0046] The "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). It is applicable to, for example, SBR, BR, plasticizers, etc.

[0047] The "nitrogen adsorption specific surface area (N2SA) of carbon black" is measured in accordance with JIS K 6217-2:2017.

[0048] The "nitrogen adsorption specific surface area (N2SA) of silica" is measured by the BET method in accordance with ASTM D3037-93.

[0049] 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 × (area of the particle) / π]. The average primary particle diameter is applicable to silica, carbon black, etc.

[0050] The "softening point of the resin component" is the temperature at which the ball drops when measured with a ring and ball softening point measuring device according to the softening point specified in JIS K 6220-1:2015 7.7.

[0051] The manufacturing 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.

[0052] [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 0.025 or less from the viewpoint of the effects of the present invention, preferably 0.024 or less, more preferably 0.023 or less, further preferably 0.022 or less, and particularly preferably 0.021 or less. On the other hand, the lower limit of G / W L is not particularly limited from the viewpoint of the effects of the present invention, but can be, for example, 0.012 or more, 0.013 or more, 0.014 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 conversely, it can also be decreased.

[0053] The maximum load capacity W L (kg) is preferably 300 or more, more preferably 400 or more, further preferably 450 or more, and particularly preferably 500 or more from the viewpoint of better exhibiting the effects of the present invention. Also, the maximum load capacity WL (kg) can be, for example, 1300 or less, 1200 or less, 1100 or less, 1000 or less, 900 or less, 800 or less, 700 or less from the viewpoint of better exhibiting the effects of the present invention. The maximum load capacity W L can be increased by increasing the virtual volume V of the space occupied by the tire, and can also be decreased conversely.

[0054] The tire weight G is preferably 8.0 kg or more, more preferably 8.5 kg or more, still more preferably 9.0 kg or more, and particularly preferably 9.5 kg or more. The upper limit value of the tire weight G is not particularly limited, but is usually 100 kg or less, and can be, for example, 80 kg or less, 60 kg or less, 40 kg, 20 kg, 15 kg or less, etc.

[0055] The land ratio R on the ground contact surface of the tread portion is 0.50 or more from the viewpoint of ensuring drainage and improving grip force, preferably 0.53 or more, more preferably 0.56 or more, and still more preferably 0.59 or more. Also, the land ratio R is preferably 0.85 or less, more preferably 0.80 or less, and still more preferably 0.75 or less from the viewpoint of ensuring drainage and suppressing the occurrence of the hydroplaning phenomenon. The land ratio R can be varied by a conventional method, that is, it can be increased by reducing the groove area of the tread surface, and can also be decreased conversely.

[0056] The tread according to the present embodiment has at least one rubber layer. The tread according to the present embodiment may be a tread composed of a single rubber layer, or may be a tread 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.

[0057] The thickness of the first layer 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 may be a tread composed only of the first layer.

[0058] 30°C E*D From the perspective of following performance with the road surface, it is preferably 50 MPa or less, more preferably 30 MPa or less, and even more preferably 15 MPa or less. On the other hand, 30°C E* D From the perspective of ensuring handling stability performance, it is preferably 3.0 MPa or more, more preferably 4.0 MPa or more, even more preferably 5.0 MPa or more, and particularly preferably 6.0 MPa or more.

[0059] 30°C E* W From the perspective of following performance with the road surface, it is preferably 50 MPa or less, more preferably 30 MPa or less, and even more preferably 15 MPa or less. On the other hand, 30°C E* W From the perspective of ensuring handling stability performance, it is preferably 2.0 MPa or more, more preferably 3.0 MPa or more, even more preferably 4.0 MPa or more, and particularly preferably 5.0 MPa or more.

[0060] 30°C tanδ D From the perspective of dry grip performance, it is preferably 0.10 or more, more preferably 0.15 or more, and even more preferably 0.18 or more. Also, 30°C tanδ D From the perspective of low fuel consumption performance, it is preferably 0.50 or less, more preferably 0.45 or less, even more preferably 0.40 or less, and particularly preferably 0.35 or less.

[0061] 30°C tanδ W From the perspective of wet grip performance, it is preferably 0.10 or more, more preferably 0.15 or more, and even more preferably 0.18 or more. Also, 30°C tanδ D From the perspective of low fuel consumption performance, it is preferably 0.50 or less, more preferably 0.45 or less, even more preferably 0.40 or less, and particularly preferably 0.35 or less.

[0062] In addition, 30°C E* D 、30°C E* W 、30°C tanδ D 、30°C tanδ W can be appropriately adjusted according to the types and blending amounts of the following rubber components, resin components, oils, etc.

[0063] From the viewpoint of ensuring reinforcement, the sulfur content in the rubber composition constituting the first layer is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and still more preferably 0.5% by mass or more. On the other hand, the upper limit value of the sulfur content in the rubber composition is not particularly limited, but is usually 2.5% by mass or less. When the sulfur content is within the above range, sufficient crosslinking points between polymers can be obtained, so that the polymer is less likely to deform. The sulfur content of the rubber composition can be appropriately adjusted according to the compounding amounts of sulfur and vulcanization accelerator described below.

[0064] From the viewpoint of the effects of the present invention, the glass transition temperature (Tg) of the rubber composition constituting the first layer is preferably -100°C or higher, more preferably -80°C or higher, still more preferably -60°C or higher, and particularly preferably -50°C or higher. From the viewpoint of ensuring low-temperature brittleness, it is preferably 0°C or lower, more preferably -10°C or lower, and still more preferably -15°C or lower. The Tg of the rubber composition can be appropriately adjusted according to the types and compounding amounts of the rubber component, filler, and plasticizer described below.

[0065] The rubber composition constituting the first layer according to the present embodiment is characterized by satisfying the following formulas (3) and (4). |30°C E* D -30°C E* W |≥1.3 ···(3) |30°C tanδ D -30°C tanδ W |≥0.03 ···(4)

[0066] |30°C E* D -30°C E* W | is preferably 1.4 or more, and more preferably 1.5 or more. |30°C E* D -30°C E* W | By setting |30°C E* D -30°C E* W | within the above range, it is considered that an increase in the contact area of the tread portion due to softening by water can be expected. On the other hand, the upper limit value of |30°C E*

[0067] |tanδ at 30°C D |tanδ at -30°C W |is preferably 0.04 or more, more preferably 0.05 or more. |tanδ at 30°C D |tanδ at -30°C W |By setting it within the above range, it is considered that an improvement in grip performance can be expected. On the other hand, |tanδ at 30°C D |tanδ at -30°C W |The upper limit value is not particularly limited, but is usually 0.20 or less, preferably 0.15 or less, and more preferably 0.10 or less.

[0068] The tire according to this embodiment is characterized by satisfying the following formulas (5) and (6). |E* at 30°C D |E* at -30°C W |×R ≧ 0.70 ···(5) |tanδ at 30°C D |tanδ at -30°C W | / (G / W L ) ≧ 1.3 ···(6)

[0069] |E* at 30°C D |E* at -30°C W |×R is more preferably 0.75 or more, and more preferably 0.80 or more. |E* at 30°C D |E* at -30°C W |By setting E*×R within the above range, it is considered that a change in rubber physical properties and an optimal synergistic effect of the tire structure can be produced. On the other hand, |E* at 30°C D |E* at -30°C W |The upper limit value of ×R is not particularly limited, but is usually 1.50 or less, preferably 1.30 or less.

[0070] |tanδ at 30°C D |tanδ at -30°C W | / (G / W L ) is preferably 1.4 or more, more preferably 1.6 or more, further preferably 1.8 or more, further preferably 2.0 or more, and particularly preferably 2.1 or more. |tanδ at 30°C D |tanδ at -30°C W| / (G / W L ) By setting it within the above range, it is considered that both grip performance and low fuel consumption performance can be achieved. On the other hand, |30℃tanδ D -30℃tanδ W | / (G / W L ) The upper limit value is not particularly limited, but is usually 5.0 or less, preferably 4.0 or less, and more preferably 3.5 or less.

[0071] [Rubber composition] The tire according to this embodiment can more effectively improve the overall performance of wet grip performance, dry grip performance, and low fuel consumption performance by the cooperation of the configuration of the tire and the tread described above and the physical properties of the rubber composition constituting the tread portion. Hereinafter, the rubber composition constituting the first layer will be described.

[0072] In this embodiment, in order to reversibly change the complex elastic modulus and tanδ of the rubber composition by water, it is useful to form a part of the crosslinking formed by the rubber composition by a bond based on an electrostatic interaction such as an ionic bond. When the rubber composition contains a bond based on an electrostatic interaction, when water is taken into the rubber composition, the bond can be reversibly broken. Therefore, the complex elastic modulus of the rubber composition can be decreased when wet with water, and tanδ increases due to the improvement of the hysteresis loss caused by the dissociation of the crosslinking points. In addition, since the ionic bond is the strongest bond among non-covalent bonds, the bonding force can be maintained when dry. In addition, in order to form a bond based on an electrostatic interaction in the rubber composition, the following rubber component, resin component, silica, silane coupling agent, etc. can be modified with a hydrophilic functional group (for example, a functional group containing at least one element selected from the group consisting of nitrogen, oxygen, silicon, and sulfur; preferably, at least one selected from the group consisting of a carboxyl group, an amino group, and a hydroxyl group).

[0073] Among the bonds formed by electrostatic interaction, regarding ionic bonds, these can be introduced into the crosslinked structure in the rubber composition. In this specification, such materials are referred to as "ionic bond materials". Examples of ionic bond materials include, for example, ionically bonded modified rubbers modified so as to be able to form ionic bonds, ionically bonded modified silica, ionically bonded modified silane coupling agents, ionically bonded modified plasticizers, and the like. Further, examples of ionically bonded modified plasticizers include ionically bonded modified resins, ionically bonded modified liquid polymers, and the like. Specific examples of these ionic bond materials will be described in the columns of rubber components, silica, silane coupling agents, and plasticizers, respectively.

[0074] [Rubber composition] The rubber composition (hereinafter referred to as the rubber composition according to the present embodiment) constituting the tread portion of the tire according to the present embodiment contains a rubber component and a filler, and both can be manufactured using the raw materials described below. Hereinafter, the rubber composition according to the present embodiment will be described.

[0075] <Rubber component> In the rubber composition according to the present embodiment, a diene rubber is preferably used as the rubber component. Examples of diene rubbers include, for example, isoprene rubbers, butadiene rubbers (BR), styrene-butadiene rubbers (SBR), styrene-isoprene rubbers (SIR), styrene-isoprene-butadiene rubbers (SIBR), chloroprene rubbers (CR), acrylonitrile-butadiene rubbers (NBR), and the like. These diene rubbers may be modified rubbers treated with a modifying group capable of interacting with fillers such as carbon black and silica, or may be hydrogenated rubbers in which a part of the unsaturated bonds has been hydrogenated. Among the modified rubbers, the modified rubber into which the hydrophilic functional group has been introduced can be preferably used as an ionically bonded modified rubber. As the diene rubber, an extended rubber preliminarily extended using a plasticizer described later may be used. The diene rubber may be used alone or in combination of two or more.

[0076] 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.

[0077] 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.

[0078] (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.

[0079] From the viewpoint of the effects of the present invention, the content of the isoprene rubber 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 20% 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.

[0080] (SBR) The SBR is not particularly limited, and examples thereof include unmodified solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), and modified SBRs thereof (modified S-SBR, modified E-SBR), etc. Examples of the modified SBR include SBRs modified at the terminal and / or main chain, modified SBRs coupled with tin, silicon compounds, etc. (condensates, those having a branched structure, etc.). Among them, S-SBR and modified SBR are preferred. 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.

[0081] Among the modified SBRs, SBRs modified with a functional group containing at least one element selected from the group consisting of nitrogen, oxygen, silicon, and sulfur at the terminal and / or main chain can be preferably used as ionically bonded modified SBRs. Examples of the above functional group include, for example, amino group (preferably an amino group in which a hydrogen atom of the amino group is substituted with an alkyl group having 1 to 6 carbon atoms), amide group, silyl group, alkoxysilyl group (preferably an alkoxysilyl group having 1 to 6 carbon atoms), isocyanate group, imino group, imidazole group, urea group, ether group, carbonyl group, oxycarbonyl group, mercapto group, sulfide group, disulfide group, sulfonyl group, sulfinyl group, thiocarbonyl group, ammonium group, imide group, hydrazo group, azo group, diazo group, carboxyl group, nitrile group, pyridyl group, alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), hydroxyl group, oxy group, epoxy group, etc. One or more functional groups selected from the group consisting of amino group, carboxyl group, and alkoxysilyl group are preferred. In addition, these functional groups may have substituents. Examples of the substituent include functional groups such as amino group, amide group, alkoxysilyl group, carboxyl group, and hydroxyl group. Examples of the modified SBR include hydrogenated ones, epoxidized ones, tin-modified ones, etc.

[0082] As the SBR according to this embodiment, extended SBR can be used, or non-extended SBR can also be used. When using extended SBR, the amount of extension of the SBR, that is, the content of the extendable plasticizer contained in the SBR, is preferably 10 to 50 parts by mass with respect to 100 parts by mass of the rubber solid content of the SBR.

[0083] The SBR listed above may 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.

[0084] The styrene content of the SBR is preferably 40% by mass or less, more preferably 37% by mass or less, still more preferably 34% by mass or less, and particularly preferably 30% by mass or less. Also, the styrene content of the SBR is preferably 5% by mass or more, more preferably 7% by mass or more, still more preferably 10% by mass or more, and particularly preferably 12% by mass or more. Note that the styrene content of the SBR is measured by the above measurement method.

[0085] From the viewpoints of ensuring reactivity with silica and wear resistance performance, the vinyl content of the SBR is preferably 5 mol% or more, more preferably 10 mol% or more, and still more preferably 15 mol% or more. Also, from the viewpoints of elongation at break and wear resistance performance, the vinyl content of the SBR is preferably 65 mol% or less, more preferably 60 mol% or less. Note that in this specification, the vinyl content of the SBR is measured by the above measurement method.

[0086] 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 still 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 still more preferably 1,500,000 or less. Note that the weight average molecular weight of the SBR is measured by the above measurement method.

[0087] From the perspective of the effects of the present invention, the content of SBR in the rubber component is preferably 30% by mass or more, more preferably 40% by mass or more, still more preferably 50% by mass or more, and particularly preferably 60% by mass or more. The upper limit of the content is not particularly limited, but for example, it can be 99% by mass or less, 95% by mass or less, 90% by mass or less, 85% by mass or less.

[0088] (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-based 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 can be used alone or in combination of two or more.

[0089] 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 measurement method.

[0090] Among the modified BRs, BR modified with a functional group containing at least one element selected from the group consisting of nitrogen, oxygen, silicon, and sulfur at the terminal and / or main chain can be preferably used as the ion-bond modified BR. Examples of the above functional groups include those exemplified in the above modified SBR.

[0091] 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 ends of the modified BR molecules bonded by tin-carbon bonds (tin-modified BR), etc. The modified BR may be either non-hydrogenated or hydrogenated.

[0092] From the viewpoint of wear resistance performance, the weight average molecular weight (Mw) of BR is preferably 300,000 or more, more preferably 350,000 or more, and even more preferably 400,000 or more. From the viewpoints such as crosslinking uniformity, etc., it is preferably 2,000,000 or less, and more preferably 1,000,000 or less. The Mw of BR is measured by the above measurement method.

[0093] From the viewpoint of ensuring wear resistance performance, the content of BR in the rubber component is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, still more preferably 7% by mass or more, and particularly preferably 10% by mass or more. Also, from the viewpoint of the effects of the present invention, the content is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, and particularly preferably 20% by mass or less.

[0094] (Other rubber components) The rubber component may contain a rubber component other than the 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. Also, in addition to the above rubber components, a known thermoplastic elastomer may or may not be contained.

[0095] (Rubber components synthesized from recycled and biomass-derived raw materials) Monomers that are 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, and recycled aromatic vinyl compounds. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl compound is not particularly limited, and examples include styrene. Among them, it is preferable to use recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and recycled styrene (recycled styrene) as raw materials.

[0096] The method for producing recycled monomers is not particularly limited, and examples include being synthesized from recycled naphtha obtained by decomposing rubber products such as tires. Also, the method for producing recycled naphtha is not particularly limited, and for example, rubber products such as tires may be decomposed under high temperature and high pressure, decomposed by microwaves, or extracted after mechanical pulverization.

[0097] Furthermore, monomers that are 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. The biomass is not particularly limited, and examples include agricultural and forestry products, sugar, wood chips, plant residues after obtaining useful components, plant-derived ethanol, biomass naphtha, and the like.

[0098] The biomass-derived monomers (biomass monomers) are not particularly limited, and examples thereof 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 thereof include styrene. Further, the method for producing the biomass monomer is not particularly limited, and examples thereof include those by biological and / or chemical and / or physical conversion of animals and plants. Fermentation by microorganisms is typical as the biological conversion, and examples of the chemical and / or physical conversion include those by a catalyst, high heat, high pressure, electromagnetic waves, a supercritical fluid, and combinations thereof.

[0099] The polymers synthesized from the biomass monomer components (biomass polymers) are 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.

[0100] 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.

[0101] 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 the compound. The significance of this value will be described below.

[0102] In one mole (6.02 × 10 23 pieces) of carbon atoms, there are about 6.02 × 10, which is about one trillionth of ordinary carbon atoms.11 There is 14 carbon C. 14 The half-life of C is 5730 years, and 14 C decreases regularly. It takes 226,000 years for all of them 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., at the beginning of fixation, 14 all of the C element has decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas do not contain 14 any C element. Therefore, chemical substances produced from these fossil fuels also do not contain 14 any C element.

[0103] On the other 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, and in the atmospheric environment of the earth, 14 the amount of C is constant. Therefore, the 14 C concentration of substances derived from biomass resources circulating in the current environment is about 1×10 -12 mol% with respect to the entire carbon atoms as described above. Therefore, by utilizing the difference between these values, the biomass ratio in a certain compound can be calculated.

[0104] This 14 C is generally measured as follows. Using accelerator mass spectrometry based on a tandem accelerator, 13 the C concentration ( 13 C / 12 C), 14 the C concentration ( 14 C / 12 C) is measured. In the measurement, 14 as a modern standard reference for the concentration of C, the 14The C concentration is adopted. As a specific reference 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 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 value of the standard

[0105] C concentration (100%). The ratio of this value to the value of the actually measured sample is the pMC value. 14 Therefore, if the rubber is made of 100% biomass-derived substances, although there are regional differences and the like, it often 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 the

[0106] C concentration is measured, it will show a value of about 0 pMC (for example, 0.3 pMC). This value corresponds to a biomass ratio of 0% mentioned above.

[0107] <Filler> The rubber composition according to this embodiment contains a filler. The filler according to this embodiment preferably contains silica, more preferably contains carbon black and silica, and may also be a filler consisting only of carbon black and silica.

[0108] (Silica) The silica is not particularly limited, and for example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrous silica), etc., which are common in the tire industry, can be used. The raw material of the silica is not particularly limited, and for example, it may be a raw material derived from a mineral such as quartz, or it may be a raw material derived from a living organism such as rice husk (for example, silica using a biomass material such as rice husk as a raw material), or silica recycled from a product containing silica may also be used. Among them, hydrous silica prepared by a wet method is preferred because it has many silanol groups. These silicas may be used alone or in combination of two or more.

[0109] Silica using a biomass material as a raw material can be obtained, for example, by extracting silicate from rice husk ash obtained by burning rice husk using a sodium hydroxide solution, and reacting the silicate with sulfuric acid in the same manner as conventional wet silica to precipitate silicon dioxide, followed by filtration, washing with water, drying, and pulverization.

[0110] As the silica recycled from a product containing silica, for example, silica recovered from products containing silica such as electronic components such as semiconductors, tires, desiccants, and filter materials such as diatomaceous earth can be used. The recovery method is not particularly limited, and examples include thermal decomposition and decomposition by electromagnetic waves. Among them, silica recovered from electronic components such as semiconductors or tires is preferred.

[0111] When silica crystallizes, it is insoluble in water and the silicic acid that is its component cannot be utilized. By controlling the combustion temperature and combustion time, the crystallization of silica in rice husk ash can be suppressed (see, for example, Japanese Patent Application Laid-Open No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol. 6, p. 216-222, etc.).

[0112] Amorphous silica extracted from rice husk can be those commercially available from Wilmar Co., Ltd. and the like.

[0113] The nitrogen adsorption specific surface area (N2SA) of the silica is 110 m2 Preferably more than / g, 130 m 2 More preferably more than / g, 150 m 2 Even more preferably more than / g, 170 m 2 Particularly preferably more than / g. Also, from the viewpoints of heat generation property and processability, 350 m 2 Preferably below / g, 300 m 2 More preferably below / g, 250 m 2 Even more preferably below / g. The N2SA of silica is measured by the above measurement method.

[0114] 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 silica is preferably 20 nm or less, more preferably 19 nm or less, even more preferably 18 nm or less, and particularly preferably 17 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, and even more preferably 5 nm or more. The average primary particle diameter of silica is measured by the above measurement method.

[0115] From the viewpoint of reinforcement, the content of silica relative to 100 parts by mass of the rubber component is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 40 parts by mass or more, and particularly preferably 60 parts by mass or more. Also, from the viewpoints of processability and weight reduction of the rubber, it is preferably 200 parts by mass or less, more preferably 160 parts by mass or less, even more preferably 120 parts by mass or less, and particularly preferably 100 parts by mass or less.

[0116] (Carbon black) The carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The raw material of the carbon black may be a biomass material such as lignin or vegetable oil, or may be a pyrolysis oil obtained by pyrolyzing waste tires. Further, the manufacturing method of the carbon black may be by combustion such as the furnace method, may be by hydrothermal carbonization (HTC), or may be by thermal decomposition of methane such as the thermal black method. As commercial products, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., Columbian Carbon Company, etc. can be used. These carbon blacks may be used alone or in combination of two or more.

[0117] In addition to the above, from the perspective of life cycle assessment, etc., carbon black made from biomass materials such as lignin as a raw material, or recycled carbon black obtained by pyrolyzing and purifying products containing carbon black such as tires may also be used as the carbon black.

[0118] In this specification, "recycled carbon black" refers to carbon black obtained by pulverizing used products such as tires containing carbon black and firing the pulverized product, and when oxidized and burned by heating in air by a thermogravimetric method conforming to JIS K 6226-2:2003, it refers to carbon black in which the ratio of the mass of the ash content (ash amount), which is the component that does not burn, is 13% by mass or more. That is, the ratio of the mass of the weight loss amount (carbon amount) due to the oxidative combustion of the recycled carbon black is 87% by mass or less. Recycled carbon black may also be represented by rCB.

[0119] 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), especially 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).

[0120] Recycled carbon black may lack functional groups on its surface, or may be treated to contain functional groups on its surface. The treatment to make the recycled carbon black contain functional groups on its surface can be carried out by conventional methods. For example, in European Patent Application Publication No. 3173251, carbon black obtained from a pyrolysis process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl and / or carboxyl groups on its surface. Also, in Patent No. 6856781, carbon black obtained from a pyrolysis process is treated with an amino acid compound containing at least one thiol group or disulfide group to obtain carbon black with an activated surface. The recycled carbon black according to this embodiment also includes carbon black treated to contain functional groups on its surface.

[0121] Commercially available recycled carbon black from companies such as Strable Green Carbon and LDCarbon can be used.

[0122] The nitrogen adsorption specific surface area (N2SA) of carbon black is 50 m 2Preferably 80 m / g or more, more preferably 100 m / g or more, and even more preferably 250 m / g or more. Also, from the viewpoints of dispersibility, low fuel consumption performance, fracture characteristics, and durability performance, preferably 250 m / g or less, more preferably 220 m / g or less, and even more preferably 190 m / g or less. The N2SA of the carbon black is measured by the above measurement method. 2 Preferably 80 m / g or more, more preferably 100 m / g or more, and even more preferably 250 m / g or more. Also, from the viewpoints of dispersibility, low fuel consumption performance, fracture characteristics, and durability performance, preferably 250 m / g or less, more preferably 220 m / g or less, and even more preferably 190 m / g or less. The N2SA of the carbon black is measured by the above measurement method. 2 Preferably 80 m / g or more, more preferably 100 m / g or more, and even more preferably 250 m / g or more. Also, from the viewpoints of dispersibility, low fuel consumption performance, fracture characteristics, and durability performance, preferably 250 m / g or less, more preferably 220 m / g or less, and even more preferably 190 m / g or less. The N2SA of the carbon black is measured by the above measurement method. 2 Preferably 80 m / g or more, more preferably 100 m / g or more, and even more preferably 250 m / g or more. Also, from the viewpoints of dispersibility, low fuel consumption performance, fracture characteristics, and durability performance, preferably 250 m / g or less, more preferably 220 m / g or less, and even more preferably 190 m / g or less. The N2SA of the carbon black is measured by the above measurement method. 2 Preferably 80 m / g or more, more preferably 100 m / g or more, and even more preferably 250 m / g or more. Also, from the viewpoints of dispersibility, low fuel consumption performance, fracture characteristics, and durability performance, preferably 250 m / g or less, more preferably 220 m / g or less, and even more preferably 190 m / g or less. The N2SA of the carbon black is measured by the above measurement method. 2 Preferably 80 m / g or more, more preferably 100 m / g or more, and even more preferably 250 m / g or more. Also, from the viewpoints of dispersibility, low fuel consumption performance, fracture characteristics, and durability performance, preferably 250 m / g or less, more preferably 220 m / g or less, and even more preferably 190 m / g or less. The N2SA of the carbon black is measured by the above measurement method.

[0123] The average primary particle diameter of the carbon black is preferably 32 nm or less, more preferably 28 nm or less, even more preferably 26 nm or less, and particularly preferably 22 nm or less. Also, from the viewpoint of the average primary particle diameter, preferably 8 nm or more, more preferably 10 nm or more, even more preferably 12 nm or more, and particularly preferably 14 nm or more. The average primary particle diameter of the carbon black is measured by the above measurement method.

[0124] The content of the carbon black with respect to 100 parts by mass of the rubber component, from the viewpoints of weather resistance and reinforcing property, 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. Also, from the viewpoint of low fuel consumption performance, preferably 30 parts by mass or less, more preferably 25 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less.

[0125] (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 commonly used in the tire industry, can be blended. These other fillers may be used alone or in combination of two or more.

[0126] The ratio of the content of carbon black to the content of silica is preferably 0.40 or less, more preferably 0.33 or less, still more preferably 0.25 or less, still 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 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.

[0127] From the viewpoint of ensuring the reinforcing property during drying, the total content of the filler with respect to 100 parts by mass of the rubber component is 45 parts by mass or more, preferably 55 parts by mass or more, more preferably 65 parts by mass or more, and still more preferably 70 parts by mass or more. Also, from the viewpoints of low fuel consumption performance and processability, the content is preferably 200 parts by mass or less, more preferably 160 parts by mass or less, still more preferably 120 parts by mass or less, and particularly preferably 100 parts by mass or less.

[0128] (Silane coupling agent) When using silica, it is preferable to use a silane coupling agent in combination. The silane coupling agent is not particularly limited. For example, sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl) disulfide and bis(3-triethoxysilylpropyl) tetrasulfide; mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane; vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silane coupling agents such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane; glycidoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane, and in addition, quaternary ammonium salt-based silane coupling agents such as aqueous silane coupling agents having a quaternary ammonium salt in the organic functional group, etc. Among these, amino-based silane coupling agents, glycidoxy-based silane coupling agents, and quaternary ammonium salt-based silane coupling agents can be preferably used as ionic bond-modified silane coupling agents. As the silane coupling agent, for example, those commercially available from Evonik Degussa, Momentive, Shin-Etsu Chemical Co., Ltd., Topco Technologies Corporation, etc. can be used. These silane coupling agents may be used alone or in combination of two or more.

[0129] From the perspective 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 parts by mass or more, still more preferably 5.0 parts by mass or more, and particularly preferably 7.0 parts by mass or more. From the perspectives of cost and processability, it is preferably 20 parts by mass or less, and more preferably 15 parts by mass or less.

[0130] <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.

[0131] A plasticizer is a material that imparts plasticity to the 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 polymers, 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 thermally decomposing and extracting used tires and products containing various components may be used as plasticizers. Among these plasticizers, those modified by a functional group containing at least one element selected from the group consisting of nitrogen, oxygen, silicon, and sulfur can be preferably used as ion-bonding modified plasticizers. These plasticizers may be used alone or in combination of two or more.

[0132] (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 rosin-based resins, terpene-based resins, dicyclopentadiene-based resins, aromatic vinyl resins, C9-based resins, C5-based resins, C5C9-based resins, and phenolic resins can be mentioned. Among them, since rosin-based resins have carboxyl groups, they can be preferably used as ion-bonding modified resins. These resin components may be used alone or in combination of two or more.

[0133] The "rosin-based resin" refers to a resin containing rosin acid compounds such as abietic acid, neoabietic acid, palustric acid, and isopimaric acid, and those obtained by hydrogenating or modifying them may also be used. The rosin-based resin is not particularly limited, and examples include natural resin rosin, rosin-modified resins obtained by hydrogenating, disproportionating, dimerizing, esterifying, etc. of the rosin. These rosin-based resins may be used alone or in combination of two or more.

[0134] The "terpene-based resin" refers to a resin containing terpene compounds such as α-pinene, β-pinene, limonene, and dipentene as the monomer component with the highest content, and those obtained by hydrogenating or modifying them may also be used. Specific examples of terpene-based 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 that are monomer components of aromatic-modified terpene resins include styrene, α-methylstyrene, vinyltoluene, divinyltoluene, etc. Examples of phenolic compounds that are monomer components of terpene-phenol resins include phenol, bisphenol A, cresol, xylenol, etc. These terpene-based resins may be used alone or in combination of two or more.

[0135] The term "dicyclopentadiene-based resin" refers to a resin containing cyclopentadiene (CPD) or dicyclopentadiene (DCPD) as a monomer component, which may be hydrogenated or modified. 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 hydrogenated or modified versions thereof), and DCPD / C9 resins containing dicyclopentadiene and styrene as monomer components are preferred, and DCPD / C9 resins containing dicyclopentadiene, styrene, and indene as monomer components are more 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.

[0136] The term "aromatic vinyl-based 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, which may be hydrogenated or modified. As aromatic vinyl-based resins, due to economic reasons, ease of processing, and excellent heat generation properties, homopolymers of α-methylstyrene or styrene or copolymers of α-methylstyrene and styrene are preferred, and copolymers of α-methylstyrene and styrene are more preferred. As aromatic vinyl-based resins, for example, those commercially available from Creighton, Eastman Chemical, Mitsui Chemicals, etc. can be used. These aromatic vinyl-based resins may be used alone or in combination of two or more.

[0137] "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 of the C9 fraction and other components. For example, a resin obtained by copolymerizing dicyclopentadiene (DCPD) and a C9 fraction is called a DCPD / C9 resin. Further, it may be hydrogenated or modified. 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.

[0138] "C5 resin" refers to a resin obtained by polymerizing a C5 fraction, which may be hydrogenated or modified. 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.

[0139] "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, which may be hydrogenated or modified. As the C5C9 petroleum resin, for example, those commercially available from Tosoh Corporation, LUHUA Co., Ltd., etc. can be used. These C5C9 resins may be used alone or in combination of two or more.

[0140] "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, and oil-modified phenol formaldehyde resin. These phenolic resins may be used alone or in combination of two or more.

[0141] From the perspective of grip performance, the softening point of the resin component is preferably 60°C or higher, more preferably 70°C or higher, and even more preferably 80°C or higher. Further, from the perspectives of processability and improving the dispersibility of the rubber component and the filler, it is preferably 150°C or lower, more preferably 140°C or lower, and even more preferably 130°C or lower. The softening point of the resin component is measured by the above measurement method.

[0142] When containing the resin component, the content thereof with respect to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and particularly preferably 12 parts by mass or more. Further, from the perspective of suppressing heat generation, it is preferably 50 parts by mass or lower, more preferably 40 parts by mass or lower, and even more preferably 30 parts by mass or lower.

[0143] (Oil) Examples of the oil include mineral oil, vegetable oil, animal oil, etc. Further, from the perspective of life cycle assessment, it is also possible to use waste oil after being used in a rubber mixer or an engine, or refined waste cooking oil used in a cooking shop.

[0144] In this specification, the mineral oil refers to an oil derived from mineral resources such as petroleum and natural gas. Examples of the mineral oil include paraffinic oil (mineral oil), naphthenic oil, aromatic oil, etc. Specific examples of the 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. Further, it is also possible to use an oil with a low content of polycyclic aromatic (PCA) compounds for environmental measures. Examples of the low PCA content oil include MES, TDAE, heavy naphthenic oil, etc.

[0145] In this specification, the "vegetable oil" includes, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grape seed oil, wood wax, etc. Further, as the vegetable oil, there may be mentioned 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, oxidative polymerized oils obtained by oxidizing the above oils, waste cooking oils recovered from those used as edible oils, etc. Note that the vegetable oil may be liquid or solid at normal temperature (25°C). These vegetable oils may be used alone or in combination of two or more.

[0146] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably contains triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxy group of glycerin and a fatty acid are ester-bonded. The acylglycerol is not particularly limited, and may be any of 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, and triacylglycerol. Further, the acylglycerol may be a monomer, a dimer, or a multimer of trimer or more. Note that acylglycerols of dimer or more can be obtained by thermal polymerization, oxidative polymerization, etc. Also, the acylglycerol may be liquid or solid at normal temperature (25°C).

[0147] The method for confirming whether the acylglycerol is contained in the rubber composition 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, at room temperature 1When measuring 1H-NMR and setting the signal of tetramethylsilane (TMS) to 0.00 ppm, signals around 5.26 ppm, around 4.28 ppm, and around 4.15 ppm were 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.

[0148] The fatty acid is not particularly limited and may be an unsaturated fatty acid or a saturated fatty acid. Examples of unsaturated fatty acids include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of saturated fatty acids include butyric acid and lauric acid.

[0149] Among them, it is desirable that the fatty acid contains 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. In addition, in order to produce a vegetable oil containing such a fatty acid, plants may be improved by variety improvement, genetic recombination, or the like.

[0150] As the vegetable oil, for example, those commercially available from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo 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.

[0151] Examples of animal oils include fish oil, beef tallow, or oleyl alcohol that can be derived therefrom.

[0152] The content of oil with respect to 100 parts by mass of the rubber component (when using a plurality of oils in combination, the total amount of all) is preferably 1 part by mass or more, more preferably 5 parts by mass or more, still more preferably 10 parts by mass or more, and particularly preferably 12 parts by mass or more from the viewpoint of processability. Also, from the viewpoint of the hardness of the rubber, it is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and still more preferably 30 parts by mass or less.

[0153] (Liquid polymer) The liquid polymer is not particularly limited as long as it is in a liquid state at normal temperature (25°C). For example, liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), liquid styrene-butadiene copolymer (liquid SBR), liquid styrene-isoprene copolymer (liquid SIR), polymers containing myrcene and farnesene, etc. can be mentioned. Among these liquid polymers, those modified with a functional group containing at least one element selected from the group consisting of nitrogen, oxygen, silicon, and sulfur at the terminal and / or in the main chain can be preferably used as the ion-bonding modified liquid polymer. Examples of the above functional group include those exemplified in the above modified SBR. As the liquid polymer, those manufactured by Kuraray Co., Ltd. etc. can be used. These liquid polymers may be used alone or in combination of two or more.

[0154] When containing a liquid polymer, the content with respect to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 5 parts by mass or more, still more preferably 10 parts by mass or more, and particularly preferably 12 parts by mass or more. Also, the content of the liquid polymer is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and still more preferably 30 parts by mass or less.

[0155] (Ester plasticizer) Examples of ester plasticizers include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), bis(2-ethylhexyl) azelate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), trixylenyl phosphate (TXP), and the like. These ester plasticizers may be used alone or in combination of two or more.

[0156] The content of the plasticizer relative to 100 parts by mass of the rubber component (the total amount of all plasticizers when using a plurality of plasticizers in combination) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 15 parts by mass or more, still more preferably 20 parts by mass or more, and particularly preferably 25 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.

[0157] In addition, when any one or more of the above rubber component, silica, resin component, and liquid polymer are modified with a carboxyl group, various metal salts may be blended in order to form an ionic bond in the rubber composition. Examples of these metal salts include metal carbonates such as lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, beryllium carbonate, magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate, and lithium acetate; metal acetates such as sodium acetate, potassium acetate, rubidium acetate, cesium acetate, beryllium acetate, magnesium acetate, calcium acetate, strontium acetate, and barium acetate; fatty acid metal salts other than metal acetates such as sodium stearate, magnesium stearate, calcium stearate, barium stearate, sodium oleate, magnesium oleate, calcium oleate, and barium oleate; and metal phenoxides such as lithium phenoxide, sodium phenoxide, potassium phenoxide, rubidium phenoxide, cesium phenoxide, beryllium diphenoxide, magnesium diphenoxide, calcium diphenoxide, strontium diphenoxide, and barium diphenoxide.

[0158] The content of the metal salt relative to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more. Also, the content is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, and particularly preferably 12 parts by mass or less.

[0159] (Vulcanized rubber particles) 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.

[0160] The vulcanized rubber particles are not particularly limited and may be either 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.

[0161] 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.

[0162] (Processing aid) Examples of the processing aid include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, fatty acid esters, mixtures of fatty acid metal salts and amide esters, mixtures of fatty acid metal salts and fatty acid amides, etc. As the processing aid, for example, those commercially available from Schill+Seilacher, Performance Additives, etc. can be used. These processing aids may be used alone or in combination of two or more.

[0163] When containing the processing aid, from the viewpoint of exerting the effect of improving processability, the content relative to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 1 part by mass, and even more preferably more than 1.5 parts by mass. 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 even more preferably less than 5.0 parts by mass.

[0164] (Wax) The wax is not particularly limited, and any wax commonly used in the tire industry can be preferably used. Examples 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 their selected special waxes, etc., and paraffin wax is preferred. Note that the wax according to this embodiment does not contain stearic acid. As the wax, for example, those commercially available from Ouchi Shinsei Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., etc. can be used. These waxes may be used alone or in combination of two or more.

[0165] When containing wax, 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 even 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 the whitening of the tire due to blooming, it is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0166] (Antioxidant) The anti-aging agent is not particularly limited, but examples include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine-based anti-aging agents such as N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-ditoly-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based anti-aging agents such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based anti-aging agents such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; bis, tris, polyphenol-based anti-aging agents such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, etc. Among them, p-phenylenediamine-based anti-aging agents and quinoline-based anti-aging agents are preferred, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and polymers of 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. As commercially available products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Industry Co., Ltd., Flexsys Co., etc. can be used. These anti-aging agents may be used alone or in combination of two or more kinds.

[0167] When containing an anti-aging agent, the content based on 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 even more preferably 1.5 part by mass or more from the viewpoint of ozone crack resistance of the rubber. Also, from the viewpoint of wear resistance performance, it is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less.

[0168] When contained, the content of stearic acid 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.

[0169] When contained, the content of zinc oxide 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.

[0170] (Vulcanizing agent) Sulfur is preferably used as the vulcanizing agent. As sulfur, powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, etc. can be used.

[0171] When the vulcanizing agent contains sulfur, the content relative to 100 parts by mass of the rubber component is preferably more than 0.1 part by mass, more preferably more than 0.5 part by mass, and still more preferably more than 1.0 part by mass from the viewpoint of ensuring a sufficient vulcanization reaction. Also, from the viewpoint of deterioration prevention, it is preferably less than 5.0 parts by mass, more preferably less than 4.0 parts by mass, and still more preferably less than 3.5 parts by mass. Further, from the viewpoint of the effects of the present invention, the content of the vulcanizing agent is preferably 3.0 parts by mass or less, more preferably less than 2.5 parts by mass, still more preferably less than 2.0 parts by mass, and particularly preferably 1.5 parts by mass or less in order to reduce the density of sulfur crosslinking. Note that when oil-containing sulfur is used as the vulcanizing agent, the content of the vulcanizing agent is the total content of pure sulfur contained in the oil-containing sulfur.

[0172] 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 Taoka Chemical Industry Co., Ltd., Rancess Co., Ltd., Flexsys Co., etc. can be used. The vulcanizing agents other than sulfur may be used alone or in combination of two or more.

[0173] (Vulcanization accelerator) 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 suitably 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.

[0174] 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.

[0175] 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.

[0176] Examples of guanidine-based vulcanization accelerators include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, the 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.

[0177] 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.

[0178] In this specification, various materials containing carbon atoms (such as rubber, oil, resin components, vulcanization accelerators, antioxidants, etc.) may be derived from carbon dioxide in the atmosphere. As a method for obtaining the various materials from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process of synthesizing methane from carbon dioxide may be converted.

[0179] [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.).

[0180] 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.

[0181] 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.

[0182] The tire of the present invention provided with a tread composed of the rubber composition can be manufactured by a normal 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, and is bonded together with the inner rubber layer of the tread and other tire members on a tire molding machine, and molded by a normal 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.

[0183] [Use of tire] The tire according to this 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 1400 kg or less. [Examples]

[0184] 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, a tire having the first layer of the tread portion obtained according to the formulation in Table 1 was examined, and the results calculated based on the following evaluation method are shown in Table 1.

[0185] Hereinafter, the various chemicals used in the examples and comparative examples are summarized and shown. NR:TSR20 SBR1: Nipol NS616 manufactured by ZS Elastomer Co., Ltd. (S-SBR, styrene content: 21% by mass, vinyl content: 61 mol%, Mw: 510,000, non-oil extended) SBR2: SBR manufactured according to the following Production Example 1 (carboxylic acid-modified SBR, carboxylic acid group content: 5% by mass, styrene content: 23% by mass, butadiene content: 72% by mass) BR1: Nipol BR1220 manufactured by Zeon Corporation (BR synthesized using a cobalt-based catalyst, cis content: 96 mol%, Mw: 460,000) Carbon black: Seast 6 manufactured by Tokai Carbon Co., Ltd. (N2SA: 119 m 2 / g, average primary particle diameter: 22 nm) Silica 1: ULTRASIL® VN3 manufactured by Evonik Degussa GmbH (N2SA: 175 m 2 / g, average primary particle diameter: 17 nm) Silica 2: ULTRASIL® 9100GR manufactured by Evonik Degussa GmbH (N2SA: 235 m 2 / g, average primary particle diameter: 15 nm) Silane coupling agent 1: Si266 (bis(3-triethoxysilylpropyl)disulfide) manufactured by Evonik Degussa GmbH Silane coupling agent 2 (ionically bonded modified silane coupling agent): KBE603 of Topco Technologies Corporation (N-2-(aminoethyl)-3-aminopropyltriethoxysilane) Liquid polymer (ionically bonded modified liquid polymer): Kuraprene LIR410 of Kuraray Co., Ltd. (modified liquid polyisoprene having about 10 carboxyl groups per molecule and a number average molecular weight of 25,000) Oil: Process X-140 manufactured by ENEOS Corporation Resin component 1: SYLVATRAXX 4150 manufactured by Crayton Corporation (polyt terpene resin, softening point: 115°C) Resin component 2: Gum rosin manufactured by Sigma-Aldrich Metal salt: Potassium acetate Zinc oxide: Zinc white No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Bead stearic acid Camellia manufactured by NOF Corporation Wax: Sunoc N (paraffin wax) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Antioxidant: No Crack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Sulfur: Powder sulfur manufactured by Karuizawa Sulfur Co., Ltd. Vulcanization accelerator 1: Nocceler D (1,3-diphenylguanidine (DPG)) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Vulcanization accelerator 1: Nocceler NS-G (N-tert-butyl-2-benzothiazolylsulfenamide (TBBS)) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

[0186] (Production Example 1: Production of SBR2) Distilled water, Emulsifier (1), Emulsifier (2), Electrolyte, Styrene, Methacrylic acid, Butadiene, and a molecular weight regulator are charged into a pressure reactor equipped with a stirrer. An aqueous solution in which a radical initiator and SFS are dissolved and an aqueous solution in which EDTA and a catalyst are dissolved are added to the reactor to initiate polymerization. Then, a polymerization terminator is added to stop the reaction, and latex is obtained. Unreacted monomers are removed by steam distillation. The residue is added to alcohol and coagulated while adjusting the pH to 3 - 5 with a saturated sodium chloride aqueous solution or formic acid to obtain a crumb-like polymer, which is then dried in a vacuum dryer to obtain SBR2.

[0187] The materials used in Production Example 1 are as follows. Emulsifier (1): Rosin soap manufactured by Harima Kasei Co., Ltd. Emulsifier (2): Fatty acid soap manufactured by Fujifilm Wako Pure Chemical Corporation Electrolyte: Sodium phosphate manufactured by Fujifilm Wako Pure Chemical Corporation Styrene: Styrene manufactured by Fujifilm Wako Pure Chemical Corporation Methacrylic acid: Methacrylic acid manufactured by Fujifilm Wako Pure Chemical Corporation Butadiene: 1,3-Butadiene manufactured by Takachiho Chemical Industry Co., Ltd. Molecular weight regulator: tert-Dodecyl mercaptan manufactured by Fujifilm Wako Pure Chemical Corporation Radical initiator: para-menthane hydroperoxide manufactured by NOF Corporation SFS: Sodium formaldehyde sulfoxylate manufactured by FUJIFILM Wako Pure Chemical Corporation EDTA: Sodium ethylenediaminetetraacetate manufactured by FUJIFILM Wako Pure Chemical Corporation Catalyst: Ferric sulfate manufactured by FUJIFILM Wako Pure Chemical Corporation Polymerization terminator: N,N'-dimethyldithiocarbamate manufactured by FUJIFILM Wako Pure Chemical Corporation Alcohol: Methanol and ethanol manufactured by Kanto Chemical Co., Inc. Formic acid: Formic acid manufactured by Kanto Chemical Co., Inc. Sodium chloride: Sodium chloride manufactured by FUJIFILM Wako Pure Chemical Corporation

[0188] (Examples and Comparative Examples) According to the formulation shown in Table 1, 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 into the shape of the first layer (thickness: 10 mm) of the tread part using an extruder equipped with a die of a predetermined shape, and laminated together with the second layer (thickness: 4 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 (size: 195 / 65R15, rim: 15×6JJ, internal pressure: 230 kPa) described in Table 1.

[0189] <Viscoelasticity measurement> From inside the first layer of the tread portion of each test tire, each vulcanized rubber test piece produced by cutting out a piece with a length of 20 mm × width of 4 mm × thickness of 1 mm such that the tire circumferential direction is the long side and the tire radial direction is the thickness direction is immersed in water at 25°C for 12 hours to obtain a water-wetted vulcanized rubber composition. Regarding this water-wetted vulcanized rubber composition, using a dynamic viscoelasticity measuring device (Iplexer 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, 30°C E* W and 30°C tan δ W are measured. Next, the water-wetted vulcanized rubber composition is dried under reduced pressure at 80°C and 1 kPa or less until a constant weight is obtained to obtain a dried vulcanized rubber composition. Regarding this dried vulcanized rubber composition, using a dynamic viscoelasticity measuring device (Iplexer 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, 30°C E* D and 30°C tan δ D are measured.

[0190] <Measurement of glass transition temperature (Tg) of rubber composition> Regarding each rubber test piece produced by cutting out a piece with a length of 20 mm × width of 4 mm × thickness of 1 mm from the tread portion of each test tire such that the tire circumferential direction is the long side and the tire radial direction is the thickness direction, using a dynamic viscoelasticity measuring device (Iplexer series manufactured by GABO), under the conditions of a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±0.5%, and a heating rate of 2°C / min, the temperature distribution curve of tan δ in the range from -60°C to 40°C is measured, and the temperature (tan δ peak temperature) corresponding to the largest tan δ value in the obtained temperature distribution curve is determined as the Tg of the rubber composition.

[0191] <Measurement of sulfur content> Regarding each vulcanized rubber test piece produced by cutting out a piece with a length of 20 mm × width of 4 mm × thickness of 1 mm from inside the first layer of the tread portion of each test tire such that the tire circumferential direction is the long side and the tire radial direction is the thickness direction, in accordance with JIS K 6233:2016, the sulfur content (mass%) is measured by the oxygen combustion flask method.

[0192] <Wet Grip Performance> Mount each test tire on all four wheels of a vehicle (domestic FF 2000 cc), and measure the braking distance from the point where the brakes are applied at a speed of 100 km / h on a wet asphalt road surface. Convert the braking distance of the control tire (Comparative Example 1) to 100, and express the reciprocal of the braking distance of each test tire as an index using the following formula. The higher the index, the better the wet grip performance. (Wet Grip Performance Index) = (Braking Distance of Control Tire) / (Braking Distance of Each Test Tire)

[0193] <Dry Grip Performance> Mount each test tire on all four wheels of a vehicle (domestic FF 2000 cc), and measure the braking distance from the point where the brakes are applied at a speed of 100 km / h on a dry asphalt road surface. Convert the braking distance of the control tire (Comparative Example 1) to 100, and express the reciprocal of the braking distance of each test tire as an index using the following formula. The higher the index, the better the dry grip performance. (Dry Grip Performance Index) = (Braking Distance of Control Tire) / (Braking Distance of Each Test Tire)

[0194] <Low Fuel Consumption Performance> Using a rolling resistance tester, measure the rolling resistance when each test tire is run at a rim of 15×6JJ, an internal pressure of 230 kPa, a load of 3.43 kN, and a speed of 80 km / h, and express the reciprocal as an index when the reference comparative example is 100. The larger the index, the smaller the rolling resistance and the better the low fuel consumption performance.

[0195] <Comprehensive Performance> Express the sum of the wet grip performance index, dry grip performance index, and low fuel consumption performance index as the comprehensive performance index.

[0196]

Table 1

[0197] <Embodiment> Examples of embodiments of the present invention are shown below.

[0198] 〔1〕A tire comprising a tread portion having at least one rubber layer, wherein a first layer constituting the tread surface is composed of a rubber composition containing a rubber component and a filler, the rubber composition contains 45 parts by mass or more of the filler with respect to 100 parts by mass of the rubber component, the maximum load capacity of the tire is W L (kg), the weight of the tire is G (kg), the land ratio at the ground contact surface of the tread portion is R, the complex elastic modulus of the rubber composition at 30 ° C when dry is 30 ° C E* D (MPa), the complex elastic modulus of the rubber composition at 30 ° C when water-wetted is 30 ° C E* W (MPa), the tan δ of the rubber composition at 30 ° C when dry is 30 ° C tan δ D , the tan δ of the rubber composition at 30 ° C when water-wetted is 30 ° C tan δ W is, when W L , G, R, 30 ° C E* D , 30 ° C E* W , 30 ° C tan δ D , and 30 ° C tan δ W satisfy the following formulas (1) to (6). R ≧ 0.50 ···(1) G / W L ≦ 0.025 ···(2) |30 ° C E* D -30 ° C E* W |≧ 1.3 ···(3) |30 ° C tan δ D -30 ° C tan δ W |≧ 0.03 ···(4) |30 ° C E* D -30 ° C E* W |× R ≧ 0.70 ···(5) |30 ° C tan δ D -30 ° C tan δ W | / (G / W L )≧ 1.3 ···(6) 〔2〕The tire according to the above 〔1〕, wherein the rubber composition contains 40 parts by mass or more of silica with respect to 100 parts by mass of the rubber component. 〔3〕The average primary particle diameter of the silica is 20 nm or less, and the tire according to the above 〔1〕 or 〔2〕. 〔4〕The rubber composition contains 5 parts by mass or more of a plasticizer with respect to 100 parts by mass of the rubber component, and the tire according to any one of the above 〔1〕 to 〔3〕. 〔5〕The plasticizer contains at least one selected from the group consisting of a resin component and a liquid polymer, and the tire according to the above 〔4〕. 〔6〕The rubber component contains 10% by mass or more of butadiene rubber, and the tire according to any one of the above 〔1〕 to 〔5〕. 〔7〕The amount of sulfur in the rubber composition is 0.1% by mass or more, and the tire according to any one of the above 〔1〕 to 〔6〕. 〔8〕The glass transition temperature of the rubber composition is -10°C or higher, and the tire according to any one of the above 〔1〕 to 〔7〕. 〔9〕30°C E* D is 3.0 MPa or more, and the tire according to any one of the above 〔1〕 to 〔8〕. 〔10〕30°C tanδ D is 0.10 or more, and the tire according to any one of the above 〔1〕 to 〔9〕.

Claims

1. A tire having a tread portion with at least one rubber layer, wherein the first layer constituting the tread surface is composed of a rubber composition containing a rubber component and a filler, the rubber composition contains 45 parts by mass or more of the filler with respect to 100 parts by mass of the rubber component, The maximum load capacity of the tire is W L (kg), the weight of the tire is G (kg), the land ratio on the ground contact surface of the tread portion is R, the complex elastic modulus of the rubber composition at 30°C when dry is 30°C E* D (MPa), the complex elastic modulus of the rubber composition at 30°C when water-wetted is 30°C E* W (MPa), the tanδ of the rubber composition at 30°C when dry is 30°C tanδ D and the tanδ of the rubber composition at 30°C when water-wetted is 30°C tanδ W When it is the case, W L , G, R, 30°C E* D , 30°C E* W , 30°C tanδ D , and 30°C tanδ W A tire in which satisfy the following formulas (1) to (6). R≧0.50 ··· (1) G / W L ≤0.025 ··· (2) | 30°C E* D -30°C E* W | ≥1.3 ··· (3) |tanδ at 30°C D tanδ at -30°C W |≥ 0.03 ··· (4) | 30 °C E* D -30 °C E* W | × R ≥ 0.70 ··· (5) |tanδ at 30°C D -tanδ at -30°C W | / (G / W L ) ≥ 1.3 ··· (6)

2. The tire according to claim 1, wherein the rubber composition contains 40 parts by mass or more of silica with respect to 100 parts by mass of the rubber component.

3. The tire according to claim 1 or 2, wherein the average primary particle diameter of the silica is 20 nm or less.

4. The tire according to claim 1 or 2, wherein the rubber composition contains 5 parts by mass or more of a plasticizer with respect to 100 parts by mass of the rubber component.

5. The tire according to claim 4, wherein the plasticizer contains at least one selected from the group consisting of a resin component and a liquid polymer.

6. The tire according to claim 1 or 2, wherein the rubber component contains 10% by mass or more of butadiene rubber.

7. The tire according to claim 1 or 2, wherein the sulfur content in the rubber composition is 0.1% by mass or more.

8. The tire according to claim 1 or 2, wherein the glass transition temperature of the rubber composition is -10°C or higher.

9. 30 °C E* D The tire according to claim 1 or 2, wherein D is 3.0 MPa or more.

10. tanδ at 30°C D The tire according to claim 1 or 2, wherein D is 0.10 or more.

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