tire

Abstract

To provide a tire which can improve total performance of low fuel consumption performance and abrasion resistance performance.SOLUTION: A tire includes a tread part having at least one rubber layer, wherein a ratio (G / WL) of tire weight G (kg) to maximum load capacity WL(kg) of the tire is 0.0140 or less, a first layer constituting the tread surface is composed of a rubber composition containing a rubber component, a plasticizer and a filler, the plasticizer contains at least one selected from the group consisting of a hydrogenated resin component and vegetable oil, and when a land ratio on the ground surface of the tread part is represented by R, the total content of the plasticizer to 100 pts.mass of the rubber component in the rubber composition is represented by P (pts.mass), a product (R×P) of R and P exceeds 10.0.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

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

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, tires have been made lighter in order to reduce the rolling resistance of the tires. To make the tire lighter, it is conceivable to reduce the thickness of the tread part, but there is a concern that the life of the tire will be shortened due to wear. In addition, since low-fuel-consumption rubber generates less heat, it is difficult to relieve the impact from the road surface, and the fracture strength of the rubber tends to decrease.

[0005] An object of the present invention is to provide a tire capable of improving the overall performance of low fuel consumption performance and wear resistance.

Means for Solving the Problems

[0006] The present invention is a tire provided with a tread portion having at least one rubber layer, and the maximum load capacity W of the tire LRatio of tire weight G (kg) to tire weight (G / W L the land ratio at the contact surface of the tread portion is R, and the total content of the plasticizer per 100 parts by mass of the rubber component in the rubber composition is P (parts by mass), the product of R and P (R×P) exceeds 10.0. Effect of the Invention

[0007] According to the present invention, a tire is provided that can improve the overall performance of fuel economy and wear resistance. [Brief description of the drawings]

[0008]

Figure 1

[0009] A tire according to one embodiment of the present invention is a tire having a tread portion having at least one rubber layer, and the tire has a maximum load capacity W L Ratio of tire weight G (kg) to tire weight (G / W L ) is 0.0140 or less, a first layer constituting the tread surface is constituted by a rubber composition containing a rubber component, a plasticizer, and a filler, the plasticizer includes at least one selected from the group consisting of a hydrogenated resin component and a vegetable oil, and when a land ratio at the contact surface of the tread portion is R and a total content of the plasticizer per 100 parts by mass of the rubber component in the rubber composition is P (parts by mass), the product of R and P (R x P) exceeds 10.0.

[0010] Although not intending to be bound by theory, the reasons for the improvement in the overall performance of the fuel efficiency and wear resistance of the tire of the present invention are considered as follows.

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

[0012] By blending a hydrogenated resin or vegetable oil, it becomes easier to improve the viscosity of the rubber composition. Therefore, the shearing force required for filler dispersion increases, and it is considered that the dispersibility of the filler is improved.

[0013] Also, by increasing the land ratio, the force applied per unit area of the rubber decreases, and it is considered that the amount of rubber deformation is suppressed. On the other hand, by increasing the content of the plasticizer, the followability of the rubber surface increases and the skid amount during running decreases, but since the viscous component in the rubber component increases, the fuel efficiency performance deteriorates slightly. From this, it is considered that by making the product of these above a certain value or more, it is possible to suppress the skid on the rubber surface and the deformation of the rubber.

[0014] And by these acting in cooperation, it is considered that the fuel efficiency performance, breaking strength, and elongation at break can be improved synergistically, and the overall performance of the fuel efficiency and wear resistance of the tire can be improved.

[0015] The tanδ (30°C tanδ) of the rubber composition at 30°C is preferably 0.15 or less.

[0016] By setting 30°C tanδ within the above range, it is considered that the fuel efficiency performance can be improved.

[0017] 30°C tanδ / R is preferably less than 0.60.

[0018] By setting 30°C tan δ / R within the above range, it is considered possible to achieve both low fuel consumption performance and improved wear resistance by suppressing the amount of rubber deformation.

[0019] (R×P) / (G / W L ) is preferably greater than 1000 and less than 2000.

[0020] (R×P) / (G / W L ) By setting it within the above range, it is considered possible to achieve both weight reduction of the tire and improved lifespan.

[0021] From the perspective of the effects of the present invention, the total styrene amount S in the rubber component is preferably 25% by mass or less.

[0022] S / R is preferably less than 45.

[0023] By setting S / R within the above range, it is considered possible to improve the balance between rubber deformation and road surface followability.

[0024] From the perspective of the balance between processability and low fuel consumption performance, the rubber composition preferably contains silica with an average primary particle diameter of 16 nm or less.

[0025] From the perspective of the balance between low fuel consumption performance and wear resistance, the rubber composition preferably contains a mercapto-based silane coupling agent.

[0026] Let the modulus at 200% elongation of the rubber composition be M 200 (MPa), and when the complex elastic modulus of the rubber composition at 30°C is 30°C E* (MPa), M 200 , 30°C E*, and 30°C tan δ preferably satisfy the relational expression M 200 ×30°C E* / 30°C tan δ ≧ 200.

[0027] M 200By setting ×30℃E* / 30℃tan within the above range, it is considered that the low fuel consumption performance and the wear resistance performance can be improved well in balance.

[0028] From the viewpoint of the effects of the present invention, the rubber component preferably contains a hydrogenated styrene-butadiene rubber.

[0029] <Definition> The "tread portion" is a portion that forms the ground contact surface of the tire. In the radial cross-section of the tire, when the tire skeleton is formed by members such as a belt layer, a belt reinforcing layer, and a carcass layer made of steel or textile materials, it is a member located outside these in the radial direction of the tire.

[0030] The "normal state" is a no-load state in which the tire is mounted on a normal rim and filled with air at a normal internal pressure.

[0031] 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. On the other hand, those existing inside the tire or on the tire cut surface are, for example, values specified in a state where the cut tire piece is held in the rim width of the normal rim by cutting the tire with a plane including the tire rotation axis.

[0032] "Regular rim" refers to the rim defined for each tire in a 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 when making 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).

[0033] "Regular internal pressure" refers to the air pressure defined for each tire in a standard system that includes the standards on which the tire is based. For example, in the case of JATMA, it 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 regular rim, refer to JATMA, ETRTO, and TRA in that order, and follow the relevant standards if there are applicable sizes when making the reference. In the case of a tire not defined in the above standards, it refers to the regular internal pressure (not less than 250 kPa) of another tire size described with the regular rim as the standard rim (provided that it is defined in the standards). When there are multiple regular internal pressures not less than 250 kPa described, it refers to the minimum value among them.

[0034] The "normal load" refers to 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"; and in the case of TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". Refer to JATMA, ETRTO, and TRA in this order as in the case of the normal rim and normal internal pressure, and follow the relevant standard if there is an applicable size during the reference. For tires not defined in the above standards, the maximum load capacity W L calculated separately is taken as the normal load.

[0035] The "maximum load capacity W L " is calculated by the following formula. "V" is the virtual volume of the tire (mm 3 ), "Dt" is the outer diameter of the tire in the normal state (mm), "Ht" is the cross-sectional height of the tire in the radial direction of the tire in the cross-section of the tire by the plane including the tire rotation axis (mm), and "Wt" is the cross-sectional width of the tire in the normal state (mm). When R is the rim diameter of the tire, Ht can be obtained by (Dt - R) / 2. Wt is the value obtained after excluding patterns, characters, etc. on the tire sidewall. Note that the maximum load capacity is synonymous with the above normal load.

[0036]

Equation

[0037] The "tire weight G (kg)" refers to the weight of the tire alone without including the weight of the rim. On the other hand, when the tire inner cavity is equipped with sound insulation materials, sealants, sensors, etc., G is the weight including these.

[0038] The "groove", including the circumferential groove and transverse groove, refers to a recess with a width of more than at least 2.0 mm.

[0039] The "contact area" is the area of the tread obtained from the contour when the tire is pressed against the ground. After assembling the tire on the standard rim, applying the standard internal pressure, and leaving it standing for 24 hours at 25°C, ink is applied to the tire tread surface. Then, the tire is loaded with the standard load (maximum load capacity) and pressed vertically against thick paper (the camber angle is 0°), and the ink is transferred to obtain it. The area of the contact area is called the total contact area. The total contact area can be calculated as the average value of the five areas obtained by performing the above transfer operation while rotating the tire by 72° each time for a total of five locations.

[0040] The "effective contact area" is the area of the tread where the tire contacts the ground when the tire is pressed against the ground. After assembling the tire on the standard rim, applying the standard internal pressure, and leaving it standing for 24 hours at 25°C, ink is applied to the tire tread surface. Then, the tire is loaded with the standard load (maximum load capacity) and pressed vertically against thick paper (the camber angle is 0°), and the ink is transferred to obtain it. The area of the effective contact area is called the effective contact area. The effective contact area can be calculated as the average value of the five areas obtained by performing the above transfer operation while rotating the tire by 72° each time for a total of five locations.

[0041] The "land ratio R" is calculated by the following formula from the total contact area for the contact area and the effective contact area for the effective contact area. (Land ratio) = (Effective contact area / Total contact area)

[0042] The "total thickness of the tread portion" refers to the total thickness of the tread portion on the tire equatorial plane in the cross-section obtained by cutting the tire with a plane including the tire rotation axis. Note that the inner end in the tire radius direction of the total thickness of the tread portion is the inner interface of the rubber composition constituting the tread portion. When the tire is provided with a belt reinforcing layer, a belt layer, and a carcass layer, among these, it is the total thickness of the rubber layer outside the outermost layer in the tire radius direction in the tire radius direction. When there are circumferential grooves on the tire equatorial plane, the total thickness of the tread portion is measured with the grooves filled.

[0043] "The thickness of each rubber layer constituting the tread portion" is the thickness of each rubber layer on the tire equatorial plane in a cross-section obtained by cutting the tire with a plane including the tire rotation axis, and is the average value of the thicknesses of the tread portion obtained at five positions by rotating the tire by 72° in the circumferential direction. For example, the thickness of the first layer refers to the linear distance in the tire radial direction from the outermost surface of the tread to the inner interface of the first layer in the tire radial direction on the tire equatorial plane. When there are circumferential grooves on the tire equatorial plane, the thickness of each rubber layer constituting the tread portion shall be the thickness of each rubber layer at the center in the tire width direction of the land portion closest to the tire equatorial plane. The "land portion closest to the tire equatorial plane" refers to the land portion having the groove edge closest to the tire equatorial plane among the circumferential grooves existing on the tire equatorial plane. When such land portions exist on both sides in the tire width direction, the thickness of each rubber layer constituting the tread portion shall be the average value of the thicknesses of each rubber layer at the center in the tire width direction of the two land portions. Also, when there are current-carrying members etc. on the land portion on the tire equatorial plane and the interface is unclear, it shall be measured by virtually connecting the interfaces blocked by the current-carrying members etc.

[0044] The "plasticizer" is a material that imparts plasticity to the rubber component and is a component extracted from the rubber composition using acetone. The plasticizer includes plasticizers that are liquid (in liquid state) at 25°C and plasticizers that are solid at 25°C. However, waxes and stearic acid commonly used in the tire industry are not included.

[0045] The "total content P of plasticizer" also includes the amount of plasticizer contained in the extended rubber component previously extended by plasticizers 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.

[0046] <Measurement method> The "thickness of each rubber layer constituting the tread portion" is measured with the tire cut by a plane including the tire rotation axis and the width of the bead portion adjusted to match the width of the regular rim.

[0047] "30°C tanδ" is the loss tangent measured using a dynamic viscoelasticity measuring device (for example, the Implex series manufactured by GABO) under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of ±1%, and an elongation mode. The sample for loss tangent measurement is a vulcanized rubber composition with a length of 20 mm × width of 4 mm × thickness of 1 mm. When produced 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.

[0048] "30°C E*" is the complex elastic modulus measured using a dynamic viscoelasticity measuring device (for example, the Implex series manufactured by GABO) under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of ±1%, and an elongation mode. The sample for this measurement is produced in the same manner as in the case of 30°C tanδ.

[0049] "Modulus at 200% elongation (M 200 )" conforms to JIS K 6251:2017 and is the tensile stress (MPa) at 200% elongation in the machine direction (the rolling direction when forming a rubber sheet by extrusion or shearing treatment) measured under the conditions of an atmosphere of 23°C and a tensile speed of 3.3 mm / second. M 200 The sample for measurement is a dumbbell-shaped No. 7 vulcanized rubber test piece with a thickness of 1 mm. When produced by cutting from a tire, it is cut from the tread portion of the tire such that the tire circumferential direction is the tensile direction and the tire radial direction is the thickness direction.

[0050] "Styrene content" is a value calculated by pyrolysis gas chromatography and is applicable to rubber components having repeating units derived from styrene such as SBR. In this specification, "pyrolysis gas chromatography" refers to a method in which a sample is heated by a pyrolysis device, the individual components contained in the gas-phase components generated by this heating are separated by a separation column, and each isolated component is analyzed.

[0051] The "vinyl content (amount of 1,2 - bonded butadiene units)" 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.

[0052] The "cis content (amount of cis - 1,4 - bonded butadiene units)" 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.

[0053] The "total styrene amount in the rubber component" is the total content (% by mass) of styrene units contained in 100% by mass of the rubber component. For each rubber component, a value obtained by multiplying the styrene content (% by mass) by the mass fraction in the rubber component is calculated, and the sum of these values is the result. Specifically, it is calculated by Σ (styrene content (% by mass) of each rubber containing styrene units × content (% by mass) of each rubber containing styrene units in the rubber component / 100).

[0054] The "weight - average molecular weight (Mw)" can be determined by standard polystyrene conversion based on the measured values 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 SBR, BR, plasticizers, etc., for example.

[0055] The "nitrogen adsorption specific surface area (N2SA) of carbon black" is measured in accordance with JIS K 6217 - 2:2017. The "nitrogen adsorption specific surface area (N2SA) of silica" is measured by the BET method in accordance with ASTM D3037 - 93.

[0056] The "average primary particle diameter" is obtained by photographing particles with a transmission or scanning electron microscope and calculating the arithmetic mean of 400 particle diameters. When the shape of the particle is approximately circular, the diameter of the circle is taken as the particle diameter; when the particle is needle-shaped or rod-shaped, the minor axis is taken as the particle diameter; and in other cases, the equivalent circle diameter is calculated from the electron microscope image and taken as the particle diameter. The equivalent circle diameter is obtained as the positive square root of [4×(particle area) / π]. The average primary particle diameter is applicable to silica, carbon black, etc.

[0057] The "softening point of the resin component" is measured with a ring and ball softening point measuring device as the softening point defined in JIS K 6220-1:2015 7.7, which is the temperature at which the ball drops.

[0058] The manufacturing procedure of the tire, which is an embodiment of the present invention, will be described in detail below. However, the following description is for illustrative purposes to explain the present invention and is not intended to limit the technical scope of the present invention only to this description range.

[0059] [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 0.0140 or less from the viewpoint of the effect of the present invention, preferably 0.0137 or less, more preferably 0.0135 or less, and even more preferably 0.0133 or less. On the other hand, the lower limit value of the G / W L is not particularly limited from the viewpoint of the effect of the present invention, but can be, for example, 0.0110 or more, 0.0115 or more, 0.0120, 0.0125 or more. Note that the tire weight G can be varied by conventional methods, that is, it can be increased by increasing the specific gravity of the tire or increasing the thickness of each member of the tire, and can also be decreased conversely.

[0060] The maximum load capacity W L (kg) is preferably 300 or more, more preferably 400 or more, even more preferably 450 or more, and particularly preferably 500 or more from the viewpoint of better exerting the effect 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. Note that the maximum load capacity W L can be increased by increasing the virtual volume V of the space occupied by the tire, and can also be decreased conversely.

[0061] The land ratio R on the ground contact surface of the tread portion is preferably 0.50 or more, more preferably 0.55 or more, and even more preferably 0.60 or more. Also, the land ratio R is preferably 0.85 or less, more preferably 0.80 or less, and even more preferably 0.75 or less.

[0062] The tread portion according to the present embodiment has at least one rubber layer. The tread portion according to the present embodiment may be a tread portion composed of a single rubber layer, or may be a tread portion having a first layer whose outer surface constitutes a tread surface and one or more rubber layers (inner rubber layers) existing between the first layer and the belt layer.

[0063] The thickness of the first layer constituting the tread surface with respect to the thickness of the entire tread portion can be, for example, 30% or more, 50% or more, 70% or more, 90% or more, and the tread portion may be composed only of the first layer constituting the tread surface.

[0064] The thickness t1 of the first layer is preferably 2.5 mm or more, more preferably 3.0 mm or more, and even more preferably 3.5 mm or more. Also, the thickness t1 of the first layer is preferably 12.0 mm or less, more preferably 11.0 mm or less, and even more preferably 10.0 mm or less.

[0065] From the perspective of the effects of the present invention, the 30°C E* of the rubber composition constituting the first layer is preferably 4.0 MPa or more, more preferably 4.5 MPa or more, still more preferably 5.0 MPa or more, and particularly preferably 5.5 MPa or more. Also, the 30°C E* of the rubber composition is preferably 15.0 MPa or less, more preferably 12.0 MPa or less, and still more preferably 11.0 MPa or less. The 30°C E* of the rubber composition can be appropriately adjusted according to the types and blending amounts of the rubber component, resin component, oil, etc. described below.

[0066] From the perspective of the effects of the present invention, the 30°C tanδ of the rubber composition constituting the first layer is preferably 0.25 or less, more preferably 0.22 or less, still more preferably 0.20 or less, and particularly preferably 0.18 or less. Also, the 0°C tanδ of the rubber composition is preferably 0.06 or more, more preferably 0.08 or more, still more preferably 0.10 or more, and particularly preferably 0.12 or more. The 0°C tanδ of the rubber composition can be appropriately adjusted according to the types and blending amounts of the rubber component, resin component, oil, etc. described below.

[0067] The M 200 of the rubber composition constituting the first layer is preferably 4.0 MPa or more, more preferably 5.0 MPa or more, still more preferably 6.0 MPa or more, and particularly preferably 7.0 MPa or more from the perspective of the effects of the present invention. Also, the M 200 of the rubber composition is preferably 15.0 MPa or less, more preferably 13.0 MPa or less, and still more preferably 11.0 MPa or less. The M 200 of the rubber composition can be appropriately adjusted according to the types and blending amounts of the rubber component, vulcanized rubber particles, resin component, oil, etc. described below.

[0068] The product (R×P) of the land ratio R and the total content P (parts by mass) of the plasticizer with respect to 100 parts by mass of the rubber component in the rubber composition is greater than 10.0, preferably 11.0 or more, and more preferably 12.0 or more. On the other hand, the upper limit value of R×P is not particularly limited, but is preferably less than 35.0, more preferably less than 30.0, and still more preferably less than 28.0.

[0069] (R×P) / (G / W L ) is preferably more than 800, more preferably more than 1000, still more preferably more than 1200, and particularly preferably more than 1400. On the other hand, (R×P) / (G / W L ) is preferably less than 2200, more preferably less than 2000, and still more preferably less than 1900.

[0070] The ratio (30°C tan δ / R) of the 30°C tan δ of the rubber composition constituting the first layer to the land ratio R is preferably less than 0.60, more preferably less than 0.50, still more preferably less than 0.45, and particularly preferably less than 0.40. Also, the lower limit of 30°C tan δ / R is not particularly limited, but is preferably more than 0.10, more preferably more than 0.15, still more preferably more than 0.20, and particularly preferably more than 0.25.

[0071] The ratio (S / R) of the total styrene amount S (mass%) in the rubber component to the land ratio R is preferably less than 45, more preferably less than 40, and still more preferably less than 38. On the other hand, the lower limit of S / R is not particularly limited, but is preferably more than 3, more preferably more than 5, and still more preferably more than 7.

[0072] M 200 ×30°C E* / 30°C tan δ is preferably 200 or more, more preferably 220 or more, and still more preferably 240 or more. On the other hand, M 200 ×30°C E* / 30°C tan δ is not particularly limited in its upper limit, but is preferably 800 or less, more preferably 700 or less.

[0073] [Rubber composition] The tire according to the present embodiment can more effectively improve the comprehensive performance of low fuel consumption performance and wear resistance performance by the cooperation of the configuration of the tire and the tread portion 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.

[0074] <Rubber component> In the rubber composition according to this embodiment, a diene rubber is preferably used as the rubber component. Examples of the diene rubber include isoprene rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene rubber (SIR), styrene-isoprene-butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), and the like. These diene rubbers may be modified rubbers treated with a modifying group capable of interacting with fillers such as carbon black and silica, or may be hydrogenated rubbers obtained by hydrogenating a part of the unsaturated bonds. The diene rubber may be used alone or in combination of two or more. Further, as the diene rubber, an extended rubber preliminarily extended using a plasticizer described below may be used.

[0075] 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 consist only of the diene rubber.

[0076] 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 consist only of isoprene rubber, SBR, and BR.

[0077] (Isoprene rubber) The isoprene rubber is not particularly limited, and examples thereof include natural rubber (NR), isoprene rubber (IR), modified natural rubber, and the like. Examples of NR include SIR20, RSS#3, TSR20, and the like. Examples of IR include IR2200 and the like. 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, and the like. These isoprene rubbers may be used alone or in combination of two or more.

[0078] From the viewpoint of the effects of the present invention, the content of the isoprene rubber in the rubber component is preferably 60% by mass or less, more preferably 50% by mass or less, still more preferably 40% by mass or less, and particularly preferably 30% by mass or less. The lower limit 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.

[0079] (BR) BR is not particularly limited, and for example, BR with a cis content of less than 50 mol% (low-cis BR), BR with a cis content of 90 mol% or more (high-cis BR), rare-earth-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), and the like, which are common in the tire industry, can be used. These BRs may be used alone or in combination of two or more.

[0080] 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 wear 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.

[0081] As the modified BR, modified butadiene rubber (modified BR) modified with a functional group containing at least one element selected from the group consisting of silicon, nitrogen, and oxygen at the terminal and / or main chain is preferably used.

[0082] As other modified BRs, those obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and further having the terminals of the modified BR molecules bonded by tin-carbon bonds (tin-modified BR) etc. may be mentioned. Further, the modified BR may be either an unhydrogenated one or a hydrogenated one.

[0083] From the viewpoint of abrasion resistance performance, the weight average molecular weight (Mw) of BR is preferably 300,000 or more, more preferably 350,000 or more, and still more preferably 400,000 or more. Also, 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.

[0084] From the viewpoint of the effects of the present invention, the content of BR in the rubber component is preferably 50% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less, and particularly preferably 25% by mass or less. Also, the lower limit value of the content is not particularly limited, but for example, it can be 1% by mass or more, 3% by mass or more, 5% by mass or more, 7% by mass or more, 10% by mass or more.

[0085] (SBR) 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. As the modified SBR, SBR modified at the terminal and / or main chain, modified SBR coupled with tin, silicon compounds, etc. (condensates, those having a branched structure, etc.) may be mentioned. Further, hydrogenated products of these SBRs (hydrogenated SBR) etc. can also be used. These SBRs may be used alone or in combination of two or more.

[0086] The hydrogenated SBR can be synthesized by subjecting a polymer obtained by polymerizing styrene and a conjugated diene compound by a known method (for example, the method described in JP-A-2020-79340) to a hydrogenation treatment. There is no particular limitation on the copolymerization order, and it may be a random copolymerization or a block copolymerization. Further, the hydrogenated SBR may be synthesized by copolymerizing a monomer having a structure after hydrogenation.

[0087] Examples of the conjugated diene compound include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, 1,3-hexadiene and the like, with 1,3-butadiene and isoprene being preferred, and 1,3-butadiene being more preferred. These may be used alone or in combination of two or more.

[0088] The hydrogenation rate of the hydrogenated SBR is preferably 40 mol% or more, more preferably 50 mol% or more, still more preferably 60 mol% or more, and particularly preferably 70 mol% or more. Further, the hydrogenation rate of the hydrogenated copolymer is preferably 99 mol% or less, more preferably 98 mol% or less. When within the above range, the effects of the present invention tend to be more preferably obtained. The hydrogenation rate can be adjusted by adjusting reaction conditions such as the hydrogen gas supply pressure and reaction temperature in the hydrogenation reaction as described in Production Example 1 below. The hydrogenation rate refers to the ratio of the double bonds in the conjugated diene portion of the copolymer of styrene and the conjugated diene compound that have been hydrogenated, 1 and can be calculated from the spectral reduction rate of the unsaturated bond portion of the spectrum obtained by measuring 1H-NMR.

[0089] In the SBR according to this embodiment, extended SBR or non-extended SBR can be used. When extended SBR is used, the amount of extension of the SBR, that is, the content of the extending 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.

[0090] The SBRs listed above may be used alone or in combination of two or more. As the SBRs 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.

[0091] The styrene content of the SBR can be appropriately selected so that the total styrene amount S in the rubber component satisfies the following range. Preferably it is 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.

[0092] From the viewpoints of ensuring reactivity with silica and abrasion resistance performance, the vinyl content of the SBR is preferably 5 mol% or more, more preferably 10 mol% or more, and still more preferably 15 mol% or more. Also, from the viewpoints of elongation at break and abrasion resistance performance, the vinyl content of the SBR is preferably 45 mol% or less, more preferably 40 mol% or less, and still more preferably 35 mol% or less. Note that in this specification, the vinyl content of the SBR is measured by the above measurement method.

[0093] 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.

[0094] The content of SBR in the rubber component can be appropriately selected so that the total styrene amount S in the rubber component satisfies the following range. However, it is preferably 20% by mass or more, more preferably 30% by mass or more, further preferably 40% by mass or more, still further preferably 50% by mass or more, and particularly preferably 60% by mass or more. On the other hand, the content of SBR in the rubber component is preferably 99% by mass or less, more preferably 95% by mass or less, further preferably 90% by mass or less, and particularly preferably 85% by mass or less.

[0095] From the viewpoint of the effects of the present invention, the total styrene amount S in the rubber component is preferably 30% by mass or less, more preferably 27% by mass or less, further preferably 25% by mass or less, and particularly preferably 22% by mass or less. Also, the lower limit value of the total styrene amount S in the rubber component is not particularly limited, but is preferably 13% by mass or more, more preferably 3% by mass or more, further preferably 5% by mass or more, and particularly preferably 7% by mass or more.

[0096] (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.

[0097] (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.

[0098] 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.

[0099] 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. Biomass is not particularly limited, and examples include agricultural and forestry products, sugars, wood chips, plant residues after obtaining useful components, plant-derived ethanol, biomass naphtha, and the like.

[0100] The biomass-derived monomers (biomass monomers) are not particularly limited, and examples include biomass-derived butadiene and biomass-derived aromatic vinyl compounds. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl compound is not particularly limited, and examples include styrene. Further, the method for producing the biomass monomer is not particularly limited, and examples include those by biological and / or chemical and / or physical conversion of animals and plants. Fermentation by microorganisms is typical 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 critical liquid, and combinations thereof.

[0101] The polymers synthesized from the biomass monomer components (biomass polymers) are not particularly limited, and examples 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.

[0102] 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.

[0103] pMC is the ratio of the 14 C concentration of the sample to the 14 C concentration of the standard modern carbon (modern standard reference), and is a value used as an index indicating the biomass ratio of a compound. The significance of this value will be described below.

[0104] 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 pcs 14 C exists. 14 The half-life of C is 5730 years, 14 C is decreasing regularly. It will take 226,000 years for all of these to decay. Therefore, in the case of fossil fuels such as coal, oil, and natural gas, which are thought to have been absorbed and fixed by plants and other organisms more than 226,000 years ago, the carbon dioxide contained in these fuels at the time of fixation was also included in the carbon dioxide. 14 All C elements have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas are 14 There is no C element at all. Therefore, chemical substances produced using these fossil fuels as raw materials also 14 It does not contain any C elements.

[0105] on the other hand, 14 C is constantly produced by cosmic rays undergoing nuclear reactions in the atmosphere. 14 C is balanced between its loss by radioactive decay and its generation by nuclear reactions, and in the Earth's atmospheric environment, 14 The amount of C is constant. Therefore, the amount of biomass-derived materials circulating in the current environment is 14 As mentioned above, the C concentration is about 1×10 -12 The value is on the order of mole percent. Therefore, the biomass ratio in a compound can be calculated by using the difference between these values.

[0106] this 14 C is typically measured as follows: using accelerator mass spectrometry based on a tandem accelerator, 13 C concentration ( 13 C / 12 C). 14 C concentration ( 14 C / 12 C) is measured. 14 The modern standard reference for the C concentration is the carbon circulating in nature in 1950. 14The C concentration is adopted. As a specific standard substance, the oxalic acid standard provided by NIST (National Institute of Standards and Technology) is used. The specific activity of carbon in this oxalic acid (the radioactivity intensity of 14 C per gram of carbon) is separated for each carbon isotope, 13 and for 14 C, it is corrected to a fixed value, and the value after applying the decay correction from 1950 AD to the measurement date is used as the value of the standard

[0107] 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 current conditions, 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

[0108] 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.

[0109] <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.

[0110] (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 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 be used. Among them, hydrous silica prepared by a wet method is preferred because of its large number of silanol groups. These silicas may be used alone or in combination of two or more.

[0111] 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 obtain a precipitate of silicon dioxide, followed by filtration, washing with water, drying, and pulverization.

[0112] As the silica recycled from a product containing silica, for example, silica recovered from products containing silica such as electronic parts 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 pyrolysis and decomposition by electromagnetic waves. Among them, silica recovered from electronic parts such as semiconductors or tires is preferred.

[0113] 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, crystallization of silica in rice husk ash can be suppressed (see, for example, JP-A-2009-2594, Akita Prefectural University Web Journal B / 2019, vol. 6, p. 216-222, etc.).

[0114] Amorphous silica extracted from rice husk can be a commercially available product from Wilmar Co., Ltd. or the like.

[0115] The nitrogen adsorption specific surface area (N2SA) of the silica is 110 m2 Above / g is preferable, 140m 2 Above / g is more preferable, 170m 2 Above / g is even more preferable, 200m 2 Above / g is particularly preferable. Also, from the viewpoints of heat generation property and processability, 350m 2 Below / g is preferable, 300m 2 Below / g is more preferable, 250m 2 Below / g is even more preferable. Note that the N2SA of silica is measured by the above measurement method.

[0116] 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 18 nm or less, and even more preferably 16 nm or less. The lower limit value of the average primary particle diameter is not particularly limited, but from the viewpoint of the dispersibility of silica, it is preferably 1 nm or more, more preferably 3 nm or more, and even more preferably 5 nm or more. Note that the average primary particle diameter of silica is measured by the above measurement method.

[0117] From the viewpoints of ensuring reinforcement and attenuation in the tread part, the content of silica relative to 100 parts by mass of the rubber component is preferably 40 parts by mass or more, more preferably 55 parts by mass or more, even more preferably 70 parts by mass or more, and particularly preferably 80 parts by mass or more. Also, from the viewpoint of reducing the specific gravity of the rubber and achieving weight reduction, it is preferably 140 parts by mass or less, more preferably 120 parts by mass or less, even more preferably 100 parts by mass or less, and particularly preferably 95 parts by mass or less.

[0118] (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 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.

[0119] In addition to the above, from the viewpoint of life cycle assessment and the like, carbon black made from biomass materials such as lignin and vegetable oil as raw materials, or recycled carbon black obtained by pyrolyzing and purifying products containing carbon black such as tires may also be used as the carbon black.

[0120] 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 in the thermogravimetric measurement method conforming to JIS K 6226-2:2003, when oxidized and burned by heating in air, 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 (carbon amount) of the weight loss 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.

[0121] 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, 442, and describes that it can be obtained by pyrolysis of organic materials at 550 - 800 °C with oxygen excluded or vacuum pyrolysis at a relatively low temperature (

[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).

[0122] Recycled carbon black may lack functional groups on its surface, or may be treated to contain functional groups on its surface. The treatment to make the surface of recycled carbon black contain functional groups can be carried out by conventional methods. For example, in European Patent Application Publication No. 3173251, carbon black obtained from a pyrolysis process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl and / or carboxyl groups on its surface. Also, in Patent No. 6856781, carbon black obtained from a pyrolysis process is treated with an amino acid compound containing at least one thiol group or disulfide group to obtain carbon black with an activated surface. The recycled carbon black according to this embodiment also includes such carbon black treated to contain functional groups on its surface.

[0123] Recycled carbon black commercially available from companies such as Strable Green Carbon and LDCarbon can be used.

[0124] From the perspective of weather resistance and reinforcing properties, the nitrogen adsorption specific surface area (N2SA) of carbon black is preferably 50 m 2 / g or more, and 80 m2 More preferably 100 m 2 / g or more, and even more preferably. Further, from the viewpoints of dispersibility, low fuel consumption performance, fracture characteristics, and durability performance, 250 m 2 / g or less is preferable, and 220 m 2 / g or less is more preferable. The N2SA of carbon black is measured by the above measurement method.

[0125] When containing carbon black, the content with respect to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more from the viewpoints of weather resistance and reinforcement. Further, from the viewpoint of low fuel consumption performance, 30 parts by mass or less is preferable, 25 parts by mass or less is more preferable, 20 parts by mass or less is even more preferable, and 15 parts by mass or less is particularly preferable.

[0126] (Other fillers) Fillers other than silica and carbon black are not particularly limited. For example, aluminum hydroxide, alumina (aluminum oxide), calcium carbonate, magnesium sulfate, talc, clay, biochar, etc., 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.

[0127] The ratio of the content of carbon black to the content of silica is preferably 0.40 or less, more preferably 0.30 or less, even more preferably 0.21 or less, even more preferably 0.17 or less, even more preferably 0.13 or less, and particularly preferably 0.10 or less. By setting the ratio of the content of carbon black to the content of silica within the above range, the low fuel consumption performance can be further improved. On the other hand, the lower limit value of the ratio of the content of carbon black to the content of silica is not particularly limited, and for example, it can be 0.01 or more, 0.02 or more, 0.05 or more, and it may also be a filler that does not contain carbon black.

[0128] From the viewpoint of ensuring reinforcement and damping properties in the tread portion, the total filler content relative to 100 parts by mass of the rubber component is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, still more preferably 70 parts by mass or more, and particularly preferably 80 parts by mass or more. From the viewpoint of the effects of the present invention, it is preferably 140 parts by mass or less, more preferably 120 parts by mass or less, still more preferably 100 parts by mass or less, and particularly preferably 95 parts by mass or less.

[0129] (Silane coupling agent) Silica is preferably used in combination with a silane coupling agent. The silane coupling agent is not particularly limited, and in the tire industry, any silane coupling agent conventionally used in combination with silica can be used. However, from the viewpoint of more suitably obtaining the desired effects, one or more silane coupling agents selected from the group consisting of sulfide-based silane coupling agents and mercapto-based silane coupling agents are preferred, and mercapto-based silane coupling agents are more preferred.

[0130] Examples of the sulfide-based silane coupling agent include bis(3-triethoxysilylpropyl)disulfide, bis(3-triethoxysilylpropyl)tetrasulfide, and the like. These sulfide-based silane coupling agents may be used alone or in combination of two or more.

[0131] In this specification, the mercapto-based silane coupling agent refers to a silane coupling agent having a mercapto group and a silane coupling agent having a structure in which the mercapto group is protected by a protecting group. The mercapto-based silane coupling agent is not particularly limited, and examples thereof include a compound having a mercapto group represented by the following formula (2), a compound in which the mercapto group is protected by an ester represented by the following formula (3), and a compound containing a bonding unit A represented by the following formula (4) and / or a bonding unit B represented by the following formula (5). Among them, a compound represented by the following formula (3), or a compound containing a bonding unit A represented by the following formula (4) and / or a bonding unit B represented by the following formula (5) is preferable, and a compound represented by the following formula (3) is more preferable because the effects of the present invention can be exhibited more favorably. These mercapto-based silane coupling agents may be used alone or in combination of two or more.

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0132] Examples of the compound represented by the formula (2) include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and the compound represented by the following formula (6) (Si363 manufactured by Evonik Degussa), etc. Among them, the compound represented by the following formula (6) can be preferably used. These may be used alone or in combination of two or more. [Chemical formula]

[0133] Examples of the compound represented by the formula (3) include 3-octanoylthio-1-propyltriethoxysilane, 3-hexanoylthio-1-propyltriethoxysilane, 3-octanoylthio-1-propyltrimethoxysilane, etc.

[0134] The compound containing the bonding unit A represented by the formula (4) and / or the bonding unit B represented by the formula (5) suppresses the increase in viscosity during processing compared to sulfide-based silane coupling agents such as bis-(3-triethoxysilylpropyl)tetrasulfide. Therefore, it is considered that the dispersibility of silica becomes better, and the low fuel consumption performance, wet grip performance, and elongation at break are further improved. This is presumably because the sulfide moiety of the bonding unit A is a C-S-C bond, which is thermally more stable than tetrasulfide or disulfide, resulting in less increase in Mooney viscosity.

[0135] From the perspective of suppressing the increase in viscosity during processing, the content of the bonding unit A is preferably 30 to 99 mol%, more preferably 50 to 90 mol%. Further, the content of the bonding unit B is preferably 1 to 70 mol%, more preferably 5 to 65 mol%, and even more preferably 10 to 55 mol%. Moreover, the total content of the bonding units A and B is preferably 95 mol% or more, more preferably 98 mol% or more, and particularly preferably 100 mol%. Note that the contents of the bonding units A and B are amounts including the case where the bonding units A and B are located at the terminals of the silane coupling agent. The form when the bonding units A and B are located at the terminals of the silane coupling agent is not particularly limited as long as the units corresponding to the formulas (4) and (5) indicating the bonding units A and B are formed.

[0136] In the compound containing the bonding unit A represented by the formula (4) and the bonding unit B represented by the formula (5), the total number of repetitions (x + y) of the number of repetitions (x) of the bonding unit A and the number of repetitions (y) of the bonding unit B is preferably in the range of 3 to 300. When within this range, since the mercaptosilane of the bonding unit B covers -C7H of the bonding unit A, it is possible to suppress the shortening of the scorch time and ensure good reactivity with silica or the rubber component. 15 Since it covers, it is possible to suppress the shortening of the scorch time and ensure good reactivity with silica or the rubber component.

[0137] Examples of the compound containing the bonding unit A represented by the formula (4) and / or the bonding unit B represented by the formula (5) include NXT-Z30, NXT-Z45, NXT-Z60, NXT-Z100, etc. manufactured by Momentive. These may be used alone or in combination of two or more.

[0138] Silane coupling agents other than sulfide-based silane coupling agents and mercapto-based silane coupling agents are not particularly limited. For example, vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silane coupling agents such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-(2-aminoethyl)aminopropyltriethoxysilane; glycidoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane; and the like. These other silane coupling agents may be used alone or in combination of two or more. As the silane coupling agents listed above, for example, silane coupling agents manufactured and sold by Momentive, Evonik Degussa, etc. can be used.

[0139] From the viewpoint of enhancing the dispersibility of silica, the content of the silane coupling agent relative to 100 parts by mass of silica is preferably 1.0 part by mass or more, more preferably 3.0 parts by mass or more, and still more preferably 5.0 parts by mass or more. From the viewpoints of cost and processability, it is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and still more preferably 12 parts by mass or less.

[0140] <Plasticizer> The rubber composition according to this embodiment contains a plasticizer. The plasticizer according to this embodiment includes at least one selected from the group consisting of a hydrogenated resin component and a vegetable oil, and may further contain other plasticizers. As the hydrogenated resin component, a hydrogenated dicyclopentadiene-based resin is preferably used. Examples of other plasticizers include a non-hydrogenated resin component, an oil, a liquid rubber, an ester-based plasticizer, 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. Further, a low-molecular-weight hydrocarbon component obtained by thermally decomposing and extracting a used tire or a product containing various components may be used as a plasticizer. These plasticizers may be used alone or in combination of two or more.

[0141] (Resin component) The resin component is not particularly limited as long as it is a resin component commonly used in the tire industry. Examples thereof include tacky resins such as dicyclopentadiene-based resins, aromatic vinyl resins, C9 resins, C5 resins, C5C9 resins, terpene resins, rosin resins, and phenolic resins. These resin components may be used alone or in combination of two or more.

[0142] The term "dicyclopentadiene-based resin" refers to a resin containing cyclopentadiene (CPD) or dicyclopentadiene (DCPD) as monomer components, which may be hydrogenated or modified ones. Examples of the dicyclopentadiene-based resin include DCPD / C9 resins containing dicyclopentadiene and the C9 fraction described below as monomer components (the DCPD / C9 resins may be hydrogenated or modified ones), and DCPD / C9 resins containing dicyclopentadiene and styrene as monomer components are preferred. As the dicyclopentadiene-based resin, 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.

[0143] The term "aromatic vinyl-based resin" refers to a resin containing aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene, etc. as the monomer component with the highest content, which may be hydrogenated or modified ones. As the aromatic vinyl-based resin, due to economic reasons, easy processing, and excellent heat generation properties, a homopolymer of α-methylstyrene or styrene or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred. As the aromatic vinyl-based resin, for example, 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.

[0144] "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, which may be a polymer of the C9 fraction alone or a copolymer obtained by copolymerizing the C9 fraction with other components. For example, a resin obtained by copolymerizing dicyclopentadiene (DCPD) and a C9 fraction is called a DCPD / C9 resin. Also, those obtained by hydrogenating or modifying them may be used. Examples of the C9 fraction include petroleum fractions corresponding to 8 to 10 carbon atoms such as vinyltoluene, alkylstyrene, coumarone, indene, methylindene, and dicyclopentadiene. These C9 resins may be used alone or in combination of two or more.

[0145] "C5 resin" refers to a resin obtained by polymerizing a C5 fraction, which may be obtained by hydrogenating or modifying them. 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.

[0146] "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, which may be obtained by hydrogenating or modifying them. 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.

[0147] The "terpene resin" refers to a resin containing terpene compounds such as α-pinene, β-pinene, limonene, dipentene, etc. as the monomer component with the highest content, and those obtained by hydrogenating or modifying them may also be used. Specific examples of terpene resins include, for example, polyterpene resins containing only one or more of the above terpene compounds as monomer components; aromatic-modified terpene resins containing the terpene compounds and aromatic compounds as monomer components; terpene-phenol resins containing the terpene compounds and phenolic compounds as monomer components, etc. Examples of aromatic compounds 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 resins may be used alone or in combination of two or more.

[0148] The "rosin resin" refers to a resin containing rosin acid compounds such as abietic acid, neoabietic acid, palustric acid, isopimaric acid, etc., and those obtained by hydrogenating or modifying them may also be used. The rosin resin is not particularly limited, and examples include natural resin rosin, rosin-modified resins obtained by modifying it by hydrogenation, disproportionation, dimerization, esterification, etc. These rosin resins may be used alone or in combination of two or more.

[0149] The "phenolic resin" refers to a resin containing phenolic compounds such as phenol, cresol, etc. as the monomer component with the highest content. The phenolic resin is not particularly limited, and examples include phenol-formaldehyde resins, alkylphenol-formaldehyde resins, alkylphenol-acetylene resins, oil-modified phenol-formaldehyde resins, etc. These phenolic resins may be used alone or in combination of two or more.

[0150] 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-described measurement method.

[0151] When containing a hydrogenated resin component, the content thereof 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 from the perspective of the effects of the present invention. Further, the content is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, and even more preferably 30 parts by mass or less.

[0152] The content of the resin component relative to 100 parts by mass of the rubber component (when using a plurality of resin components in combination, the total amount of all) is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more from the perspective of the effects of the present invention. Further, the content is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less.

[0153] The content of the resin component relative to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more. Further, from the perspective of suppressing heat generation, it is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less.

[0154] (Oil) Examples of the oil include mineral oil, vegetable oil, animal oil, etc. Further, from the perspective of life cycle assessment, waste oil after being used in a rubber mixer or an engine, or refined waste cooking oil used in a restaurant may be used.

[0155] As used herein, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oil (mineral oil), naphthenic oil, aromatic oil, etc. Specific examples of mineral oil include, for example, MES (Mild Extracted Solvate), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), RAE (Residual Aromatic Extract), etc. Also, oils with a low content of polycyclic aromatic (PCA) compounds can be used for environmental protection. Examples of the low-PCA-content oils include MES, TDAE, and heavy naphthenic oil, etc.

[0156] As used herein, "vegetable oil" refers to, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar 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. Furthermore, vegetable oils include refined oils (such as salad oil) obtained by refining the above oils, transesterified oils obtained by transesterifying the above oils, hydrogenated oils obtained by hydrogenating the above oils, thermally polymerized oils obtained by thermally polymerizing the above oils, oxidatively polymerized oils obtained by oxidizing the above oils, waste edible oils recovered from those used as edible oils, etc. Note that vegetable oil may be liquid or solid at room temperature (25°C). These vegetable oils may be used alone or in combination of two or more.

[0157] 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. Furthermore, the acylglycerol may be a monomer, a dimer, or a multimer of trimer or higher. Note that acylglycerols of dimer or higher can be obtained by thermal polymerization, oxidative polymerization, or the like. Also, the acylglycerol may be liquid or solid at normal temperature (25°C).

[0158] As a method for confirming whether the acylglycerol is contained in the rubber composition, it is not particularly limited. For example, the following 1 can be confirmed by 1H-NMR measurement. Specifically, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at normal temperature (25°C) for 24 hours. After removing the rubber composition, 1 1H-NMR is measured. When the signal of tetramethylsilane (TMS) is set to 0.00 ppm, signals are observed around 5.26 ppm, around 4.28 ppm, and around 4.15 ppm. 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.

[0159] The fatty acid is not particularly limited, and may be an unsaturated fatty acid or a saturated fatty acid. Examples of the unsaturated fatty acid include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of the saturated fatty acid include butyric acid and lauric acid.

[0160] Among them, as the fatty acid, it is desirable to contain a fatty acid with few double bonds, that is, a saturated fatty acid or a monounsaturated fatty acid, and oleic acid is preferred. As the vegetable oil containing such a fatty acid, for example, a vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid may be used, or a vegetable oil subjected to modification such as transesterification may be used. Further, in order to produce such a vegetable oil containing a fatty acid, plants may be improved by variety improvement, genetic recombination, etc.

[0161] As the vegetable oil, for example, those commercially available from Idemitsu Kosan Co., Ltd., Sankyo Oil Chemical Industry Co., Ltd., ENEOS Co., Ltd., Oryz Oy, H&R, Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0162] Examples of the animal oil include fish oil, beef tallow, or oleyl alcohol that can be derived therefrom.

[0163] The content of the unsaturated fatty acid contained in the constituent fatty acids of the vegetable oil is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, still further preferably 75% by mass or more, still further preferably 80% by mass or more, and particularly preferably 85% by mass or more.

[0164] From the viewpoint of the effects of the present invention, the content of the vegetable oil with respect to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and still further preferably 5 parts by mass or more. Also, the content is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and still further preferably 20 parts by mass or less.

[0165] From the viewpoint of the effects of the present invention, the content of the oil with respect to 100 parts by mass of the rubber component (the total amount of all when a plurality of oils are used in combination) is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still further preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more. Also, the content is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and still further preferably 30 parts by mass or less.

[0166] The liquid rubber is not particularly limited as long as it is a polymer in a liquid state at room temperature (25°C). For example, liquid butadiene rubber (liquid BR), liquid styrene-butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene-isoprene rubber (liquid SIR), liquid farnesene rubber, etc. can be mentioned. These liquid rubbers may be used alone or in combination of two or more.

[0167] Examples of the ester plasticizer 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), etc. These ester plasticizers may be used alone or in combination of two or more.

[0168] The total content P of the plasticizer (the total amount of all when a plurality of plasticizers are used in combination) with respect to 100 parts by mass of the rubber component is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, still more preferably 25 parts by mass or more, and particularly preferably 30 parts by mass or more from the viewpoint of followability to the road surface. Also, from the viewpoint of low fuel consumption performance, it 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.

[0169] <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 vulcanized rubber particles, processing aids, waxes, anti-aging agents, stearic acid, zinc oxide, vulcanizing agents, vulcanization accelerators, etc.

[0170] The vulcanized rubber particles are particles made of vulcanized rubber. Specifically, rubber powder etc. defined in JIS K 6316:2017 can be used. From the viewpoints of environmental consideration and cost, recycled rubber powder produced from pulverized waste tires etc. is preferable. These may be used alone or in combination of two or more.

[0171] The vulcanized rubber particles are not particularly limited, and may be non-modified vulcanized rubber particles or modified vulcanized rubber particles. As commercially available products of vulcanized rubber, for example, products of Lehigh, Murakami Rubber Industry Co., Ltd. etc. can be used.

[0172] When containing vulcanized rubber particles, the content with respect 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.

[0173] 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.

[0174] When containing the processing aid, from the viewpoint of exerting the effect of improving processability, the content with respect to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 1 part by mass, and further preferably more than 1.5 parts by mass. Also, from the viewpoints of abrasion resistance and breaking strength, it is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and further preferably less than 5.0 parts by mass.

[0175] 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.

[0176] When containing wax, 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 further 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.

[0177] 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 from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Industry Co., Ltd., Flexsys, etc. can be used. These anti-aging agents may be used alone or in combination of two or more.

[0178] When containing an anti-aging agent, from the perspective of the ozone crack resistance of the rubber, the content per 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. Also, from the perspectives of abrasion resistance performance and wet grip performance, it is preferably 10 parts by mass or less, and more preferably 5.0 parts by mass or less.

[0179] When containing stearic acid, 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 further 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, more preferably 5.0 parts by mass or less.

[0180] When containing zinc oxide, 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 further preferably 1.5 part by mass or more from the viewpoint of processability. 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.

[0181] As the vulcanizing agent, sulfur is preferably used. As sulfur, powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, etc. can be used.

[0182] When containing sulfur as the vulcanizing agent, the content relative to 100 parts by mass of the rubber component is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and further preferably 1.0 part by mass or more from the viewpoint of ensuring a sufficient vulcanization reaction. Also, from the viewpoint of deterioration prevention, it is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and further preferably 3.5 parts by mass or less. In addition, when using oil-containing sulfur as the vulcanizing agent, the content of the vulcanizing agent is the total content of pure sulfur contained in the oil-containing sulfur.

[0183] As vulcanizing agents other than sulfur, for example, alkylphenol sulfur chloride condensates, sodium 1,6 - hexamethylene - dithiolsulfate dihydrate, 1,6 - bis(N,N'-dibenzylthiocarbamoyldithio)hexane, etc. can be mentioned. These vulcanizing agents other than sulfur can be those commercially available from companies such as Taoka Chemical Industry Co., Ltd., Rancess Co., Ltd., and Flexsys.

[0184] Examples of the vulcanization accelerator include sulfenamide - type vulcanization accelerators, thiazole - type vulcanization accelerators, guanidine - type vulcanization accelerators, thiuram - type vulcanization accelerators, dithiocarbamate - type vulcanization accelerators, caprolactam disulfide, and the like. These vulcanization accelerators may be used alone or in combination of two or more. Among them, from the viewpoint of more preferably obtaining the desired effect, one or more vulcanization accelerators selected from the group consisting of sulfenamide - type vulcanization accelerators, thiazole - type vulcanization accelerators, and guanidine - type vulcanization accelerators are preferred, and it is more preferred to use a combination of sulfenamide - type vulcanization accelerators and guanidine - type vulcanization accelerators.

[0185] Examples of the sulfenamide - type vulcanization accelerator include N - tert - butyl - 2 - benzothiazolylsulfenamide (TBBS), N - cyclohexyl - 2 - benzothiazolylsulfenamide (CBS), N,N - dicyclohexyl - 2 - benzothiazolylsulfenamide (DCBS), and the like. Among them, TBBS and CBS are preferred.

[0186] Examples of the thiazole - type vulcanization accelerator include 2 - mercaptobenzothiazole (MBT) or its salt, 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.

[0187] Examples of the guanidine - type vulcanization accelerator include 1,3 - diphenylguanidine (DPG), 1,3 - di - o - tolguanidine, 1 - o - tolbiguanide, di - o - tolguanidine 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.

[0188] 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. Further, 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.

[0189] [Manufacture of Rubber Composition and Tire] The rubber composition according to the present embodiment can be manufactured by a known method. For example, it can be manufactured by kneading each of the above components using a rubber kneading device such as an open roll, a closed kneader (Banbury mixer, kneader, etc.).

[0190] 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.

[0191] The kneading conditions are not particularly limited. For example, in the base kneading process, kneading is performed at a discharge temperature of 150 to 170 °C for 3 to 10 minutes, and in the final kneading process, kneading is performed at 70 to 110 °C for 1 to 5 minutes. The vulcanization conditions are not particularly limited. For example, a method of vulcanizing at 150 to 200 °C for 10 to 30 minutes can be mentioned.

[0192] A tire having a tread portion composed of the rubber composition can be manufactured by a conventional method. That is, an unvulcanized rubber composition in which each of the above components is blended with the rubber component as required is extruded according to the shape of the first layer of the tread portion, and is bonded together with the inner rubber layer of the tread portion and other tire members on a tire molding machine, and molded by a conventional 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.

[0193] [Use of the 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 running on four wheels, and refers to a tire having a maximum load capacity of 1000 kg or less.

Examples

[0194] Hereinafter, examples (Examples) considered to be preferable in practice are shown, but the scope of the present invention is not limited to the examples. Using the various chemicals shown below, tires having the first layer of the tread portion obtained according to the formulations in Tables 1 and 2 were examined, and the results calculated based on the following evaluation methods are shown in Tables 1 and 2.

[0195] Hereinafter, various chemicals used in Examples and Comparative Examples are collectively shown. NR: TSR20 SBR1: EUROPRENE (registered trademark) SOL R C2525 manufactured by Versalis (styrene content: 26% by mass, vinyl content: 24% by mass, Mw: 600,000, non-oil product) SBR2: T3830 manufactured by Asahi Kasei Corporation (styrene content: 33% by mass, vinyl content: 34% by mass, Mw: 950,000, non-oil product) SBR3: Hydrogenated SBR produced in Production Example 1 described below (hydrogenation rate: 80 mol%, styrene content: 30% by mass, Mw: 480,000) BR: CB24 manufactured by Lanxess Co., Ltd. (BR synthesized using an Nd-based catalyst, cis content: 96 mol%, Mw: 500,000) Carbon black: Show Black N220 manufactured by Cabot Japan Co., Ltd. (N2SA: 111 m 2 / g) Silica 1: ULTRASIL® 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: 230 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: NXT-Z45 manufactured by Momentive Performance Materials Inc. (mercapto group-based silane coupling agent, copolymer of bonding unit A and bonding unit B (bonding unit A: 55 mol%, bonding unit B: 45 mol%)) Oil 1: VivaTec 500 manufactured by H&R (TDAE oil) Oil 2: Sunflower oil manufactured by Nisshin Oillio Group, Ltd. (oleic acid content in constituent fatty acids: 55% by mass, total content of polyunsaturated fatty acids in constituent fatty acids: 8% by mass) Resin component: Oppera PR395 manufactured by ExxonMobil Chemical Company (hydrogenated DCPD / C9 resin, softening point: 118°C) Wax: Oz Ace 0355 (paraffin wax) manufactured by Nippon Seiro Co., Ltd. Antioxidant: No Crack 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Zinc oxide: Zinc white No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Camellia Bead Stearic Acid manufactured by NOF Corporation Sulfur: HK-200-5 (5% oil-containing powdered sulfur) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator: Nocceler CZ (N-cyclohexyl-2-benzothiazolylsulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0196] Production Example 1: Production of hydrogenated SBR Add 2000 ml of n-hexane, 60 g of styrene, 140 g of 1,3-butadiene, 0.93 g of TMEDA, and 0.45 mmol of n-butyllithium to a heat-resistant reaction vessel that has been sufficiently purged with nitrogen, and stir at 50 °C for 5 hours to conduct a polymerization reaction. Next, while supplying hydrogen gas at a pressure of 0.4 MPa-Gauge, stir for 20 minutes to react with the unreacted polymer terminal lithium to form lithium hydride. Set the hydrogen gas supply pressure to 0.7 MPa-Gauge and the reaction temperature to 90 °C, and perform hydrogenation using a catalyst mainly composed of titanocene dichloride. When the absorption of hydrogen reaches the integrated amount corresponding to the target hydrogenation rate, bring the reaction temperature to room temperature, return the hydrogen pressure to normal pressure, withdraw from the reaction vessel, and stir and pour the reaction solution into water to remove the solvent by steam stripping to obtain hydrogenated SBR.

[0197] (Examples and Comparative Examples) According to the compounding formulations shown in Table 1 and Table 2, using a 1.7 L closed Banbury mixer, knead the chemicals other than sulfur and the vulcanization accelerator 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, add sulfur and the vulcanization accelerator to the kneaded product, knead for 4 minutes until the temperature reaches 105 °C to obtain an unvulcanized rubber composition. Using the unvulcanized rubber composition, extrude and mold it according to the shape of the first layer (thickness: 5.0 mm) of the tread part using an extruder equipped with a die of a predetermined shape, and laminate it together with the second layer (thickness: 2.0 mm) of the tread part and other tire members to produce an unvulcanized tire, and press-vulcanize it at 170 °C for 12 minutes to obtain each test tire (size: 215 / 55R18) described in Table 1 and Table 2.

[0198] <Measurement of tan δ at 30 °C and E* at 30 °C> For each vulcanized rubber test piece prepared by cutting out from the inside of the first layer of the tread portion of each test tire 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, using a dynamic viscoelasticity measuring device (Implex series manufactured by GABO), measure the loss tangent tanδ and the complex elastic modulus E* 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.

[0199] <Tensile test> For the dumbbell-shaped No. 7 test piece cut out with a thickness of 1 mm from the inside of the first layer of the tread portion of each test tire such that the tire circumferential direction is the tensile direction and the tire radial direction is the thickness direction, in accordance with JIS K 6251:2017, conduct a tensile test at a tensile speed of 3.3 mm / second under an atmosphere of 23°C, and measure the modulus (M 200 )(MPa) at 200% elongation.

[0200] <Low fuel consumption performance> Using a rolling resistance tester, measure the rolling resistance when each test tire is run at an internal pressure of (230 kPa), a load of (3.43 kN), and a speed of (80 km / h), and display it as an index when Comparative Example 2 is taken as 100. The larger the index, the smaller the rolling resistance, indicating excellent low fuel consumption performance.

[0201] <Wear resistance performance> Mount each test tire on a domestic FF vehicle, measure the groove depth of the tread portion after a running distance of 8000 km, calculate the running distance when the tire groove depth decreases by 1 mm, and display it as an index when Comparative Example 2 is taken as 100. The larger the index, the better the wear resistance performance.

[0202] <Comprehensive performance> Show the total value of the above low fuel consumption index and wear resistance performance index as the comprehensive performance index.

[0203]

Table 1

[0204]

Table 2

[0205] <Embodiment> Examples of embodiments of the present invention are shown below.

[0206] 〔1〕A tire comprising a tread portion having at least one rubber layer, wherein the ratio (G / W L ) of the tire weight G (kg) to the maximum load capacity W L (kg) of the tire is 0.0140 or less, the first layer constituting the tread surface is composed of a rubber composition containing a rubber component, a plasticizer, and a filler, the plasticizer includes at least one selected from the group consisting of a hydrogenated resin component and a vegetable oil, when the land ratio at the ground contact surface of the tread portion is R and the total content of the plasticizer with respect to 100 parts by mass of the rubber component in the rubber composition is P (parts by mass), the product (R × P) of R and P is more than 10.0 (preferably 11.0 or more, more preferably 12.0 or more and less than 35.0). 〔2〕The tire according to the above 〔1〕, wherein G / W L is 0.0135 or less. 〔3〕The tire according to the above 〔1〕 or 〔2〕, wherein tanδ (30 °C tanδ) of the rubber composition at 30 °C is 0.15 or less. 〔4〕The tire according to the above 〔3〕, wherein 30 °C tanδ / R is less than 0.60 (preferably less than 0.50, more preferably more than 0.10 and less than 0.45). 〔5〕The tire according to any one of the above 〔1〕 to 〔4〕, wherein (R × P) / (G / W L ) is more than 1000 and less than 2000. 〔6〕The tire according to any one of the above 〔1〕 to 〔5〕, wherein the total styrene amount S in the rubber component is 25% by mass or less. 〔7〕The tire according to the above 〔6〕, wherein S / R is less than 45 (preferably more than 3 and less than 40). 〔8〕The tire according to any one of the above 〔1〕 to 〔7〕, wherein the rubber composition contains silica having an average primary particle diameter of 16 nm or less. 〔9〕The tire according to any one of 〔1〕 to 〔8〕 above, wherein the rubber composition contains a mercapto-based silane coupling agent. 〔10〕Let the modulus at 200% elongation of the rubber composition be M 200 (MPa), and when the complex elastic modulus of the rubber composition at 30 °C is 30 °C E*(MPa), M 200 of the rubber composition, 30 °C E*, and 30 °C tan δ satisfy the following formula (1). The tire according to any one of 〔1〕 to 〔9〕 above. M 200 × 30 °C E* / 30 °C tan δ ≧ 200 ··· (1) 〔11〕The tire according to any one of 〔1〕 to 〔10〕 above, wherein the rubber component contains a hydrogenated styrene-butadiene rubber.

Claims

1. A tire having a tread portion with at least one rubber layer, Ratio (G / W) of tire weight G (kg) to maximum load capacity W of tire L (kg) is 0.0140 or less, L and wherein a first layer constituting a tread surface is composed of a rubber composition containing a rubber component, a plasticizer, and a filler, the plasticizer includes at least one selected from the group consisting of a hydrogenated resin component and a vegetable oil, when a land ratio at a ground contact surface of the tread portion is R and a total content of the plasticizer per 100 parts by mass of the rubber component in the rubber composition is P (parts by mass), a product (R×P) of R and P is more than 10.

0.

2. G / W L The tire according to claim 1, wherein G / W is 0.0135 or less.

3. The tire according to claim 1, wherein tanδ (30°C tanδ) of the rubber composition at 30°C is 0.15 or less.

4. The tire according to claim 3, wherein 30°C tanδ / R is less than 0.

60.

5. (R × P) / (G / W L ) is more than 1000 and less than 2000, the tire according to any one of claims 1 to 4.

6. The tire according to any one of claims 1 to 4, wherein a total styrene amount S in the rubber component is 25% by mass or less.

7. The tire according to claim 6, wherein S / R is less than 45.

8. The tire according to any one of claims 1 to 4, wherein the rubber composition contains silica having an average primary particle diameter of 16 nm or less.

9. The tire according to any one of claims 1 to 4, wherein the rubber composition contains a mercapto-based silane coupling agent.

10. Let the modulus at 200% elongation of the rubber composition be M 200 (MPa), and when the complex elastic modulus of the rubber composition at 30°C is 30°C E* (MPa), the M of the rubber composition 200 , 30°C E*, and 30°C tan δ satisfy the following formula (1), the tire according to any one of claims 1 to 4. M 200 M×tanδ at 30°C / tanδ at 30°C ≥ 200...(1)

11. The tire according to any one of claims 1 to 4, wherein the rubber component contains a hydrogenated styrene-butadiene rubber.

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