Tire

Abstract

Provided is a tire that achieves an improvement in the overall performance of low fuel consumption performance and wear resistance performance. The tire is provided with a tread portion having at least one rubber layer, the ratio (G / WL) of the tire weight G (kg) to the maximum load capacity WL (kg) of the tire is 0.0140 or less, and the first layer constituting the tread surface is configured from a rubber composition containing a rubber component, a plasticizer, and a filler. The plasticizer contains at least one selected from the group consisting of hydrogenated resin components and vegetable oils, and the product (R * P) of R and P is greater than 10.0, where R is the ground contact area ratio of the tread portion in the ground contact surface, and P is the total content of the plasticizer per 100 parts by mass of the rubber component in the rubber composition.

Description

Technical Field

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

[0002] In the tread of a tire, in addition to low fuel consumption performance (rolling resistance characteristics), performance such as wear resistance and wet skid resistance is also required. The performance can be improved by studying methods such as rubber components and fillers for the tread portion (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

Problems to be Solved by the Invention

[0004] In recent years, tires are being lightened in order to reduce the rolling resistance of the tires. In order to lighten the tire, it is considered necessary to reduce the thickness of the tread portion, but there is a concern that the life of the tire may be shortened due to wear. In addition, since the rubber for low fuel consumption generates little heat, it is difficult to buffer the impact from the road surface, and the breaking strength of the rubber tends to decrease.

[0005] An object of the present invention is to provide a tire that achieves an improvement in the comprehensive performance of low fuel consumption performance and wear resistance.

Means for Solving the Problems

[0006] The present invention relates to a tire, characterized in that it is a tire having a tread portion with at least one rubber layer, and the ratio (G / W L (kg)) of the tire weight G (kg) to the maximum load capacity W of the tire L ) 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 contains at least one selected from a hydrogenated resin component and a vegetable oil, and when the grounding area ratio of the tread portion in the grounding surface is set to R and the total content of the plasticizer relative to 100 parts by mass of the rubber component in the rubber composition is set to P (parts by mass), the product (R × P) of R and P is greater than 10.0.

Advantages of the Invention

[0007] According to the present invention, a tire that achieves an improvement in the comprehensive performance of low fuel consumption performance and wear resistance can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0008]

【 Figure 1A diagram showing the tire cross-sectional width Wt, the tire cross-sectional height Ht, and the tire outer diameter Dt in the cross-section of the tire. Detailed Description

[0009] A tire according to an embodiment of the present invention is a tire having a tread portion with at least one rubber layer, and the ratio (G / W L (kg)) of the tire weight G (kg) to the maximum load capacity W of the tire L ) 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 contains at least one selected from a hydrogenated resin component and a vegetable oil. When the grounding area ratio of the tread portion in the ground contact surface is R and the total content of the plasticizer relative 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 greater than 10.0.

[0010] Regarding the reason for the comprehensive improvement of the low fuel consumption performance and the wear resistance performance of the tire of the present invention, although it is not intended to be limited theoretically, the following speculation can be made.

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

[0012] It is considered that by compounding a hydrogenated resin and a vegetable oil, it becomes easy to increase the viscosity of the rubber composition. Therefore, the shear force necessary for the dispersion of the filler increases, and the dispersibility of the filler improves.

[0013] In addition, it is considered that by increasing the grounding area ratio, the force loaded per unit area of the rubber decreases, and the deformation amount of the rubber is suppressed. On the other hand, by increasing the content of the plasticizer, the followability of the rubber surface increases, and the amount of slip during driving decreases. However, since the viscous component in the rubber component increases, the low fuel consumption performance deteriorates slightly. Therefore, it is considered that by setting the product of them to a certain value or more, slipping on the rubber surface and deformation of the rubber can be suppressed.

[0014] At the same time, it is considered that based on these synergistic effects, the low fuel consumption performance, the breaking strength, and the elongation at break can be improved synergistically, and the comprehensive performance of improving the low fuel consumption performance and the wear resistance performance of the tire can be achieved.

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

[0016] It is considered that by setting the tanδ at 30°C within the above range, the low fuel consumption performance can be improved.

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

[0018] It can be considered that by setting the tanδ / R at 30°C within the above range, both the low fuel consumption performance and the improvement in wear resistance due to the suppression of rubber deformation can be achieved.

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

[0020] It can be considered that by setting (R×P) / (G / W L ) within the above range, both the weight reduction of the tire and the improvement in lifespan can be achieved.

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

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

[0023] It can be considered that by setting S / R within the above range, the balance between rubber deformation and road surface followability can be improved.

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

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

[0026] When the modulus of the above rubber composition at 200% elongation is set as M 200 (MPa) and the complex elastic modulus of the above rubber composition at 30°C is set as 30°C E*(MPa), preferably, M 200 , 30°C E* and 30°C tanδ of the above rubber composition satisfy the relational expression M 200 ×30°C E* / 30°C tanδ ≧ 200.

[0027] It can be considered that by setting M 200 ×30°C E* / 30°C tanδ within the above range, the low fuel consumption performance and wear resistance can be improved with good balance.

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

[0029] <Definition> The "tread area" is the part that forms the ground contact surface of the tire. When the tire radial cross-section has components such as a belt layer or a belt reinforcing layer, and a carcass layer that form the tire skeleton with steel or textile materials, it refers to the components located more radially outside these components.

[0030] The "normal state" means: a state without load, assembled on a normal rim and filled with air at normal internal pressure.

[0031] The "dimensions of each part of the tire": Unless otherwise specified, the "dimensions of each part of the tire" shown on the outer side of the tire are the values specified in the normal state. On the other hand, for the "dimensions of each part of the tire" inside the tire and in the tire cross-section, for example, it is the value specified in the state where the cut tire piece is held at the rim width of the normal rim after cutting with a plane containing the tire rotation axis.

[0032] The "normal rim" means: in the standard system including the standard on which the tire is based, the rim specified for each tire by its standard. For example, it refers to the standard rim in the applicable dimensions recorded in the "JATMA YEAR BOOK" of JATMA (Japan Automobile Tire Manufacturers Association), the "Measuring Rim" recorded in the "STANDARDS MANUAL" of ETRTO (The European Tyre and Rim Technical Organisation), and the "Design Rim" recorded in the "YEAR BOOK" of TRA (The Tire and Rim Association, Inc.). Refer to them in the order of JATMA, ETRTO, and TRA, and follow the standard if there is an applicable dimension. In addition, for a tire not specified in the above standards, it refers to the rim with the smallest rim width among the rims with the smallest diameter that can be assembled and maintain internal pressure (that is, there is no air leakage between the rim and the tire).

[0033] "Normal internal pressure" means: in the standard system that includes the standard on which the tire is based, the air pressure specified by the standard for each tire. For example, it refers to the maximum value recorded in the "Maximum Air Pressure" of JATMA, the "INFLATION PRESSURE" of ETRTO, and the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" of TRA. Similar to the case of the normal rim, it is referenced in the order of JATMA, ETRTO, and TRA, and when there are applicable dimensions during the reference, the standards thereof shall be followed. In addition, for a tire not specified in the above standards, it means the normal internal pressure (where it is 250 kPa or more) of other tire sizes (where the tire is specified in the standard) recorded with the above normal rim as the standard rim. When there are multiple normal internal pressures of 250 kPa or more recorded, it refers to the minimum value among them.

[0034] "Normal load" is the load specified by the standard for each tire in the standard system that includes the standard on which the tire is based. For example, it refers to the maximum value recorded in the "Maximum Load Capacity" of JATMA, the "LOAD CAPACITY" of ETRTO, and the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" of TRA. Similar to the cases of the normal rim and the normal internal pressure, it is referenced in the order of JATMA, ETRTO, and TRA, and when there are applicable dimensions during the reference, the standards thereof shall be followed. At the same time, for a tire not specified in the above standards, the maximum load capacity W L calculated separately shall be set as the normal load.

[0035] "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 sectional height of the tire in the radial direction of the cross-section of the tire based on the plane including the tire rotation axis (mm), and "Wt" is the sectional width of the tire in the normal state (mm). When the rim diameter of the tire is set as R, Ht can be obtained by (Dt - R) / 2. When there are patterns or characters on the tire sidewall, Wt is the value obtained after removing these. In addition, the maximum load capacity has the same meaning as the above normal load.

[0036]

Mathematical formula 1

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

[0038] The "groove" including circumferential grooves and transverse grooves means: a recessed part with a width of at least more than 2.0 mm.

[0039] The "contact area" is the area of the tread obtained from the contour when the tire is pressed on the ground. It can be obtained by assembling the tire on a regular rim, loading the regular internal pressure, standing for 24 hours at 25°C, coating the surface of the tire tread with ink, loading the tire with the regular load (maximum load capacity) and pressing it vertically on cardboard (camber angle is 0°), and transferring the ink. The area of the contact area refers to the total contact area. The total contact area can be calculated by rotating the tire 72 degrees in sequence, performing the above transfer operation at a total of 5 places, and taking the average of the 5 obtained areas.

[0040] The "effective contact area" is the area of the tire tread in contact with the ground when the tire is pressed on the ground. It can be obtained by assembling the tire on a regular rim, loading the regular internal pressure, standing for 24 hours at 25°C, coating the surface of the tire tread with ink, loading the tire with the regular load (maximum load capacity) and pressing it vertically on cardboard (camber angle is 0°), and transferring the ink. The area of the effective contact area refers to the effective contact area. The effective contact area can be calculated by rotating the tire 72 degrees in sequence, performing the above transfer operation at a total of 5 places, and taking the average of the 5 obtained areas.

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

[0042] The "thickness of the entire tread part" means: in the cross-section obtained by cutting the tire with a plane including the tire rotation axis, the thickness of the entire tread part in the tire equatorial plane. In addition, in the thickness of the entire tread part, the inner end in the tire radial direction is the inner interface of the rubber composition constituting the tread part. When the tire has a belt reinforcing layer, a belt layer, and a carcass layer, it is the thickness of the entire rubber layer located on the outer side in the tire radial direction compared to the outermost layer in the tire radial direction among these. In addition, when there is a circumferential groove in the tire equatorial plane, the groove is regarded as a filled groove when measuring the thickness of the entire tread part.

[0043] "The thickness of each rubber layer constituting the tread surface" is: in the cross-section obtained by cutting the tire with a plane including the tire rotation axis, the thickness of each rubber layer on the tire equatorial plane, and the average value of the thicknesses of the rubber layers constituting the tread surface obtained by rotating the tire 72° sequentially in the circumferential direction and measuring at 5 positions. For example, the thickness of the first layer refers to the straight-line distance in the tire radial direction from the outermost surface of the tread to the inner interface of the first layer on the tire equatorial plane. In addition, when there are circumferential grooves on the tire equatorial plane, the thickness of each rubber layer constituting the tread surface is taken as the thickness of each rubber layer at the center in the tire width direction of the grounding portion closest to the tire equatorial plane. "The grounding portion closest to the tire equatorial plane" means: having a grounding portion at the groove edge closest to the tire equatorial plane in the circumferential groove existing on the tire equatorial plane. When such grounding portions exist on both sides in the tire width direction, the thickness of each rubber layer constituting the tread surface is taken as the average value of the thicknesses of each rubber layer at the center in the tire width direction of these 2 grounding portions. In addition, when the grounding portion on the tire equatorial plane exists in an energized component or the like and the interface is not clear, the value measured by virtually connecting the interfaces blocked by the energized component or the like is taken.

[0044] "Plasticizer" refers to a material that imparts plasticity to the rubber component and is a component that can be extracted from the rubber composition with acetone. Plasticizers include plasticizers that are liquid (in a liquid state) at 25°C and plasticizers that are solid at 25°C. Among them, 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 rubber component with increased plasticizer content in advance through plasticizers such as oil, resin component, and liquid rubber component. In addition, the same applies to the content of oil, the content of resin component, and the content of liquid rubber. For example, when the increased component is oil, the increased oil is included in the content of oil.

[0046] <Measurement method> "The thickness of each rubber layer constituting the tread surface" is measured in a state where the width of the bead portion is the same as the width of the regular rim in the cross-section obtained by cutting the tire with a plane including the tire rotation axis.

[0047] "tanδ at 30°C" is the loss tangent measured using a dynamic viscoelasticity measuring device (for example, the EPLEXOR series manufactured by GABO) under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of ±1%, and a tensile mode. The sample for measuring the loss tangent is a vulcanized rubber composition with a length of 20 mm × a width of 4 mm × a thickness of 1 mm. When cutting out and manufacturing from the tire, it is cut out from the tread surface of the tire with the tire circumferential direction as the long side and the tire radial direction as the thickness direction.

[0048] "30℃E*" is the complex elastic modulus measured under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of ±1%, and a tensile mode using a dynamic viscoelasticity measuring device (for example, the EPLEXOR series manufactured by GABO). 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 )" is the tensile stress (MPa) at an elongation of 200% in the grain direction (the rolling direction when forming a rubber sheet by extrusion or shearing treatment) measured according to JIS K 6251:2017 in an atmosphere of 23°C under the condition of a tensile speed of 3.3 mm / second. M 200 The sample for measurement is a No. 7 dumbbell-shaped vulcanized rubber test piece with a thickness of 1 mm. When cutting out and producing from a tire, it is cut out from the tread surface of the tire with the circumferential direction of the tire as the tensile direction and the radial direction of the tire as 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, for example. In addition, "pyrolysis gas chromatography" in this specification means a method of heating a sample with a pyrolysis device, separating each component contained in the gas phase components generated by this heating through a separation column, and analyzing the separated components.

[0051] "Vinyl content (1,2-bonded butadiene unit amount)" is a value calculated by infrared absorption spectroscopic analysis according to 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] "Cis content (cis-1,4-bonded butadiene unit amount)" is a value calculated by infrared absorption spectroscopic analysis according to JIS K 6239-2:2017 and is applicable to rubber components having repeating units derived from butadiene such as BR, for example.

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

[0054] "Weight-average molecular weight (Mw)" can be determined by standard polystyrene conversion based on the measured values obtained by gel permeation chromatography (GPC) (for example, GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKgel SuperMultipore HZ-M manufactured by Tosoh Corporation). For example, it is applicable to SBR, BR, plasticizers, etc.

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

[0056] "Average primary particle size" is obtained by taking pictures of particles with a transmission or scanning electron microscope and calculating the arithmetic average of the particle sizes of 400 particles. For the particle size, when the shape of the particle is approximately circular, the diameter of the circle is set as the particle size; when it is needle-shaped or rod-shaped, the short diameter is set as the particle size; in other cases, the equivalent circle diameter calculated from the electron microscope image is set as the particle size. The equivalent circle diameter can be obtained by setting it as "the positive square root of [4×(the area of the particle) / π]". The average primary particle size is applicable to silica, carbon black, etc.

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

[0058] The manufacturing sequence of the tire according to an embodiment of the present invention will be described in detail below. Here, the following description is an example for explaining the present invention, and the gist of the present invention is not limited to the scope of this description.

[0059] [Tire] In the tire according to this embodiment, from the viewpoint of the effects of the present invention, the ratio of the tire weight G (kg) to the maximum load capacity W L (kg) (G / W L ) is 0.0140 or less, preferably 0.0137 or less, more preferably 0.0135 or less, and further preferably 0.0133 or less. On the other hand, from the viewpoint of the effects of the present invention, the lower limit value of this G / W L is not particularly limited. For example, it can be set to 0.0110 or more, 0.0115 or more, 0.0120 or more, 0.0125 or more. In addition, the tire weight G can be changed by conventional methods, that is, by increasing the specific gravity of the tire or increasing the thickness of each component of the tire, or it can be decreased by the opposite operation.

[0060] From the viewpoint of better exerting the effects of the present invention, the maximum load capacity W L (kg) is preferably 300 or more, more preferably 400 or more, still more preferably 450 or more, and particularly preferably 500 or more. In addition, from the viewpoint of better exerting the effects of the present invention, the maximum load capacity W L (kg) can be set to, for example, 1300 or less, 1200 or less, 1100 or less, 1000 or less, 900 or less, 800 or less, 700 or less. In addition, the maximum load capacity W L can be increased by increasing the virtual volume V of the space occupied by the above-mentioned tire, or can be decreased by the reverse operation.

[0061] The ground contact area ratio R in the ground contact surface of the tread portion is preferably 0.50 or more, more preferably 0.55 or more, still more preferably 0.60 or more. In addition, the ground contact area ratio R is preferably 0.85 or less, more preferably 0.80 or less, still 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 forming the tread surface and one or more rubber layers (inner rubber layers) present between the first layer and the belt layer.

[0063] The thickness of the first layer forming the tread surface can be set to, for example, 30% or more, 50% or more, 70% or more, 90% or more with respect to the thickness of the entire tread portion, or it can also be a tread portion composed only of the first layer forming 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, still more preferably 3.5 mm or more. In addition, the thickness t1 of the first layer is preferably 12.0 mm or less, more preferably 11.0 mm or less, still more preferably 10.0 mm or less.

[0065] From the viewpoint 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. In addition, the 30°C E* of this rubber composition is preferably 15.0 MPa or less, more preferably 12.0 MPa or less, still more preferably 11.0 MPa or less. In addition, the 30°C E* of the rubber composition can be appropriately adjusted by the types and compounding amounts of the following rubber components, resin components, oils, etc.

[0066] From the viewpoint 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. In addition, 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. Further, the 0°C tanδ of the rubber composition can be appropriately adjusted by the types and compounding amounts of the following rubber components, resin components, oils, etc.

[0067] From the viewpoint of the effects of the present invention, the M of the rubber composition constituting the first layer 200 is preferably 4.0 MPa or more, more preferably 5.0 MPa or more, still more preferably 6.0 MPa or more, and particularly preferably 7.0 MPa or more. In addition, the M of the rubber composition 200 is preferably 15.0 MPa or less, more preferably 13.0 MPa or less, still more preferably 11.0 MPa or less. Further, the M of the rubber composition 200 can be appropriately adjusted by the types and compounding amounts of the following rubber components, vulcanized rubber particles, resin components, oils, etc.

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

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

[0070] The ratio (30°C tanδ / R) of the 30°C tanδ of the rubber composition constituting the first layer to the ground contact area 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. In addition, the lower limit value of 30°C tanδ / R is not particularly limited, preferably greater than 0.10, more preferably greater than 0.15, still more preferably greater than 0.20, and particularly preferably greater than 0.25.

[0071] The ratio (S / R) of the total styrene content S (mass %) in the rubber component to the contact area 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 value of S / R is not particularly limited, but is preferably greater than 3, more preferably greater than 5, and still more preferably greater than 7.

[0072] M 200 M × E* at 30°C / tan δ at 30°C is preferably 200 or more, more preferably 220 or more, and still more preferably 240 or more. On the other hand, 200 the upper limit value of M × E* at 30°C / tan δ at 30°C is not particularly limited and 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 through the synergistic effects of the above-described configurations of the tire and the tread portion and the above-described 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 the present embodiment, a diene rubber can be 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 in which a part of the unsaturated bonds are hydrogenated. The diene rubber may be used alone or in combination of two or more. In addition, as the diene rubber, an oil-extended rubber obtained by previously adding the following plasticizer can also 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. In addition, the rubber component may be composed only of the diene rubber.

[0076] As the diene rubber component, at least one selected from isoprene rubber, styrene-butadiene rubber (SBR), and butadiene rubber (BR) can be preferably used. The rubber component preferably contains SBR, more preferably contains SBR and contains isoprene rubber and / or BR, still more preferably contains isoprene rubber, BR, and SBR, and may be composed only of isoprene rubber, SBR, and BR.

[0077] (Isoprene rubber) The isoprene rubber is not particularly limited. For example, natural rubber (NR), isoprene rubber (IR), modified natural rubber, etc. can be cited. As NR, for example, SIR20, RSS#3, TSR20, etc. can be cited. As IR, for example, IR2200, etc. can be cited. As modified natural rubber, for example, epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), high-purity natural rubber, grafted natural rubber, etc. can be cited. These isoprene rubbers can 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, further preferably 40% by mass or less, and particularly preferably 30% by mass or less. In addition, the lower limit value of this content is not particularly limited. For example, it can be set to 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) As BR, there is no particular limitation. 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 with a rare-earth element-based catalyst (rare-earth-based BR), BR containing syndiotactic polybutadiene crystals (BR containing SPB), modified BR (high-cis modified BR, low-cis modified BR), etc., which are commonly used in the tire industry, can be used. These BRs can be used alone or in combination of two or more.

[0080] As high-cis BR, for example, commercially available substances from companies such as Zeon Corporation, UBE Corporation, and JSR Corporation in Japan can be used. By containing high-cis BR, the abrasion resistance can be improved. The cis content of high-cis BR is preferably 95 mol% or more, more preferably 96 mol% or more, and further preferably 97 mol% or more. In addition, the cis content of BR is measured by the above-mentioned measurement method.

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

[0082] As other modified BRs, modified BRs obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and further, modified BRs in which a tin-carbon bond is bonded to the terminal of the modified BR molecule (tin-modified BR), etc. can be cited. In addition, the modified BR can be either an unhydrogenated modified BR or a hydrogenated modified BR.

[0083] From the viewpoint of abrasion resistance, the weight-average molecular weight (Mw) of BR is preferably 300,000 or more, more preferably 350,000 or more, and further preferably 400,000 or more. In addition, from the viewpoints of crosslinking uniformity and the like, it is preferably 2,000,000 or less, more preferably 1,000,000 or less. In addition, the Mw of BR is measured by the above-described 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, further preferably 30% by mass or less, and particularly preferably 25% by mass or less. In addition, the lower limit value of this content is not particularly limited. For example, it may be set to 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) There is no particular limitation on SBR. For example, unmodified solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), modified SBRs of these (modified S-SBR, modified E-SBR), etc. can be cited. As the modified SBR, SBR modified at the terminal and / or main chain; modified SBR coupled with tin, silicon compounds, etc. (condensates, substances having a branched structure, etc.) can be cited. Further, hydrides of these SBRs (hydrogenated SBR) etc. can also be used. These SBRs can 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 to a hydrogenation treatment by a known method (for example, the method described in JP-A-2020-79340). The copolymerization order is not particularly limited and can be random copolymerization or block copolymerization. In addition, the hydrogenated SBR can also be synthesized by copolymerizing a monomer having a hydrogenated structure.

[0087] As the conjugated diene compound, for example, 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, 1,3-hexadiene, etc. can be cited. 1,3-Butadiene and isoprene are preferred, and 1,3-butadiene is more preferred. These can 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. In addition, the hydrogenation rate of the hydrogenated copolymer is preferably 99 mol% or less, more preferably 98 mol% or less. When within the above ranges, it tends to be more preferable to obtain the effects of the present invention. The hydrogenation rate can be adjusted by adjusting reaction conditions such as hydrogen supply pressure and reaction temperature in the hydrogenation reaction described in Production Example 1 below. In addition, the hydrogenation rate refers to the proportion of double bonds in the conjugated diene moiety of the copolymer of styrene and conjugated diene compound that are hydrogenated, and can be calculated from the reduction rate of the spectrum of the unsaturated bond part of the spectrum obtained by measuring 1 1H-NMR.

[0089] As the SBR according to the present embodiment, oil-extended SBR or non-oil-extended SBR can be used. When using oil-extended SBR, the oil content of the SBR, that is, the content of the extender plasticizer contained in the SBR is preferably 10 to 50 parts by mass relative to 100 parts by mass of the rubber solid component of the SBR.

[0090] The SBRs listed above can be used alone or in combination of two or more. As the SBRs listed above, for example, commercially available substances from Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Co., Ltd., ZSELASTOMERS Co., Ltd., etc. can be used.

[0091] The styrene content of the SBR can be appropriately selected on the premise that the total styrene amount S in the rubber component satisfies the following range, and is preferably 40% by mass or less, more preferably 37% by mass or less, still more preferably 34% by mass or less, and particularly preferably 30% by mass or less. In addition, the styrene content of 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. In addition, the styrene content of the SBR is measured by the above-mentioned measurement method.

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

[0093] From the viewpoint of the effects of the present invention, the weight-average molecular weight (Mw) of SBR is preferably 100,000 or more, more preferably 200,000 or more, and still more preferably 300,000 or more. In addition, from the viewpoint of crosslinking uniformity, the weight-average molecular weight is preferably 2,000,000 or less, more preferably 1,800,000 or less, and still more preferably 1,500,000 or less. In addition, the weight-average molecular weight of SBR is measured by the above-described measurement method.

[0094] The content of SBR in the rubber component can be appropriately selected on the premise that the total styrene amount S in the rubber component satisfies the following range, and is preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 40% by mass or more, still more 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, still more 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, still more preferably 25% by mass or less, and particularly preferably 22% by mass or less. In addition, the lower limit value of the total styrene amount S in the rubber component is not particularly limited, and is preferably 3% by mass or more, more preferably 5% by mass or more, still more preferably 7% by mass or more, and particularly preferably 13% by mass or more.

[0096] (Other rubber components) Within a range that does not affect the effects of the present invention, the rubber component may also contain a rubber component other than the diene-based rubber (non-diene-based rubber). As the non-diene-based rubber, rubber components commonly used in the tire industry can be used. For example, butyl-based rubber, ethylene-propylene rubber, polynorbornene rubber, silicone rubber, chlorinated polyethylene rubber, fluororubber (FKM), acrylic rubber (ACM), epichlorohydrin rubber, etc. can be cited. These other rubber components can be used alone or in combination of two or more. In addition, in addition to the above rubber components, a known thermoplastic elastomer may or may not be contained.

[0097] (Rubber component synthesized from recycled / biomass-derived raw materials) The monomers that are the constituent units of synthetic rubbers such as IR, SBR, and BR can be substances derived from underground resources such as petroleum and natural gas, or substances recovered from rubber products such as tires or non-rubber products such as polystyrene. As the monomers obtained by recovery (recovered monomers), there is no particular limitation, and examples include recovered polyisoprene, recovered butadiene, recovered aromatic vinyl compounds, etc. As the above-mentioned butadiene, 1,2-butadiene and 1,3-butadiene can be mentioned. As the above-mentioned aromatic vinyl compound, there is no particular limitation, and styrene, etc. can be mentioned. Among them, it is preferable to use recovered polyisoprene (recovered isoprene), recovered butadiene, and recovered styrene as raw materials.

[0098] As the method for producing the recovered monomer, there is no particular limitation. For example, it can be synthesized from recovered naphtha obtained by cracking rubber products such as tires. In addition, as the method for producing recovered naphtha, there is no particular limitation. For example, rubber products such as tires can be cracked under high temperature and high pressure, or cracked by microwave, or extracted after mechanical pulverization.

[0099] Furthermore, the monomers that are the constituent units of polymers such as IR, SBR, and BR can also be substances derived from biomass. In this specification, biomass refers to substances derived from natural resources such as plants. As biomass, there is no particular limitation, and examples include substances derived from agricultural, forestry, and fishery products or sugars, wood chips, plant residues after obtaining useful components, ethanol of plants, biomass naphtha, etc.

[0100] As the monomers derived from biomass (biomass monomers), there is no particular limitation, and examples include butadiene derived from biomass, aromatic vinyl compounds derived from biomass, etc. As the above-mentioned butadiene, 1,2-butadiene and 1,3-butadiene can be mentioned. As the above-mentioned aromatic vinyl compound, there is no particular limitation, and styrene, etc. can be mentioned. In addition, the method for producing the monomers of biomass is not particularly limited. For example, substances obtained by biological and / or chemical and / or physical conversion of animals and plants can be mentioned. As biological conversion, fermentation based on microorganisms is representative. As chemical and / or physical conversion, conversion based on a catalyst, conversion based on high heat, conversion based on high pressure, conversion based on electromagnetic waves, conversion based on supercritical fluids, and combinations thereof can be mentioned.

[0101] As the polymer synthesized from biomass monomer components (biomass polymer), there is no particular limitation, and examples thereof include polybutadiene rubber synthesized from biomass-derived butadiene, aromatic vinyl / butadiene copolymer synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl compound, and the like. As the above-mentioned aromatic vinyl / butadiene copolymer, for example, styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene can be mentioned.

[0102] Whether the raw material of the polymer is derived from biomass can be judged by pMC (percent Modern Carbon) measured according to ASTM D6866-10.

[0103] pMC refers to: the 14 C concentration of the sample relative to that of the 14 modern standard reference of C, which is a value used as an index representing the biomass ratio of the compound. The meaning of this value will be described below.

[0104] In 1 mole (6.02×10 23 pieces) of carbon atoms, there is about one trillionth of the ordinary carbon atoms, that is, about 6.02×10 11 pieces 14 of 14 C. 14 The half-life of 14 C is 5730 years, and 14 C decreases regularly. It takes 226,000 years for all these decays to occur. Therefore, it can be considered that after carbon dioxide in the atmosphere and the like are absorbed and immobilized by plants and the like, in fossil fuels such as coal, oil, and natural gas that have experienced more than 226,000 years, all the 14 C elements contained therein at the time of initial immobilization have decayed. Therefore, in the 21st century today, fossil fuels such as coal, oil, and natural gas do not contain any

[0105] On the other hand, 14 C is continuously generated by nuclear reactions in the atmosphere through cosmic rays. Therefore, 14 the decrease of 14 C due to radioactive decay and the generation due to nuclear reactions reach an equilibrium. In the atmospheric environment of the earth, 14 the amount of -12Values of about mole %. Therefore, using the difference between these values, the biomass ratio in a certain compound can be calculated.

[0106] Generally, the 14 C is measured as described below. Using accelerator mass spectrometry based on a tandem accelerator, 13 C concentration ( 13 C / 12 C), 14 C concentration ( 14 C / 12 C) are measured. During the measurement, as the standard modern carbon for the concentration reference of 14 C, the 14 C concentration in the circulating carbon in nature in 1950 is adopted. As a specific reference material, the oxalic acid standard provided by NIST (National Institute of Standards and Technology) is used. The specific radioactivity of carbon in this oxalic acid (the radioactivity intensity of 14 C per 1 g of carbon) is classified according to each carbon isotope, 13 C 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 standard 14 C concentration value (100%). The ratio of the value of the actually measured sample to this value is the pMC value.

[0107] Therefore, if the rubber is made of 100% substances derived from biomass, although there are regional differences, etc., since it is mostly not 100 under normal conditions now, it is expected to show a value of about 110 pMC. On the other hand, for chemical substances derived from fossil fuels such as petroleum, when measuring the 14 C concentration, a value of about 0 pMC (for example, 0.3 pMC) is shown. This value corresponds to the above-mentioned biomass ratio of 0%.

[0108] In summary, it is preferable in terms of environmental protection to use materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in the rubber composition.

[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 composed only of carbon black and silica.

[0110] (Silica) As silicon dioxide, there is no particular limitation, for example, silicon dioxide (anhydrous silicon dioxide) prepared by a dry method, silicon dioxide (hydrous silicon dioxide) prepared by a wet method, and other silicon dioxide commonly used in the tire industry can be used. As the raw material of silicon dioxide, there is no particular limitation, for example, it can be a raw material derived from minerals such as quartz, it can also be a raw material derived from organisms such as rice husks (for example, silicon dioxide using biomass materials such as rice husks as raw materials, etc.), and silicon dioxide recovered from products containing silicon dioxide can also be used. Among them, due to the large number of silanol groups, hydrous silicon dioxide prepared by a wet method is preferred. These silicon dioxides can be used alone or in combination of two or more.

[0111] Silica made from biomass materials can be obtained, for example, by extracting silicate from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and reacting the silicate with sulfuric acid in the same manner as conventional wet silica to produce silica precipitate, which is then filtered, washed with water, dried, and pulverized.

[0112] Silica recovered from products containing silica, for example, silica recovered from products containing silica such as electronic components such as semiconductors, tires, desiccants, diatomaceous earth and other filter materials can be used. In addition, the recovery method is not particularly limited, and thermal cracking, electromagnetic wave cracking and the like can be cited. Among them, silica recovered from electronic components such as semiconductors or tires is preferred.

[0113] If silicon dioxide is crystallized, it will not dissolve in water, and the silicic acid as a component cannot be used. By controlling the combustion temperature and combustion time, the crystallization of silicon dioxide in rice husk ash can be suppressed (see Japanese Patent Publication No. 2009-2594, Akita Prefectural University Online Journal B (Akita Prefectural University ウェブジャーナルB) / 2019, vol. 6, p. 216-222, etc.).

[0114] Amorphous silica extracted from rice husks and commercially available products such as Wilmar can be used.

[0115] From the viewpoint of reinforcement and ensuring damping performance in the tread portion, the nitrogen adsorption specific surface area (N2SA) of silica is preferably 110 m 2 / g or more, more preferably 140m 2 / g or more, more preferably 170m 2 / g or more, particularly preferably 200m 2 / g or more. In addition, from the viewpoint of heat generation and processability, 350 m 2 / g or less, more preferably 300m 2 / g or less, more preferably 250m 2 / g or less. In addition, the N2SA of silica is measured by the above-mentioned measurement method.

[0116] From the viewpoint of increasing the specific surface area of silica, increasing the interaction with the rubber component, suppressing the activity 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 further preferably 16 nm or less. The lower limit value of the average primary particle diameter is not particularly limited, and from the viewpoint of the dispersibility of silica, it is preferably 1 nm or more, more preferably 3 nm or more, and further preferably 5 nm or more. In addition, the average primary particle diameter of silica is measured by the above-described measurement method.

[0117] From the viewpoint of ensuring reinforcement and damping properties at the tread portion, the content of silica relative to 100 parts by mass of the rubber component is preferably 40 parts by mass or more, more preferably 55 parts by mass or more, further preferably 70 parts by mass or more, and particularly preferably 80 parts by mass or more. In addition, 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, further preferably 100 parts by mass or less, and particularly preferably 95 parts by mass or less.

[0118] (Carbon black) As the carbon black, there is no particular limitation, and examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The raw material of the carbon black can be biomass materials such as lignin and vegetable oil, or pyrolysis oil obtained by thermally cracking waste tires. In addition, the manufacturing method of the carbon black can be a combustion-based method such as a furnace method, a method based on hydrothermal carbonization (HTC), or a method based on the thermal cracking of methane derived from a thermal cracking carbon black method. As commercially available products, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., Columbia Carbon Company, etc. can be used. These carbon blacks can be used alone or in combination of two or more.

[0119] In addition, as the carbon black, in addition to the above, from the viewpoint of life cycle assessment, etc., carbon black using biomass materials such as lignin and vegetable oil as raw materials, and recycled carbon black obtained by thermally cracking and refining products containing carbon black such as tires can also be used.

[0120] In this specification, "regenerated carbon black" refers to carbon black obtained by crushing used tires and other products containing carbon black and burning the crushed product, and the mass ratio of the non-combustible component, that is, the ash content (ash content) is 13% by mass or more when it is heated in air for oxidative combustion by thermogravimetric measurement based on JIS K 6226-2:2003. That is, the mass ratio (carbon content) of the reduced part of the regenerated carbon black based on the above-mentioned oxidative combustion is 87% by mass or less. Regenerated carbon black is sometimes also represented by rCB.

[0121] Regenerated carbon black can be obtained by the thermal cracking process of used pneumatic tires. For example, European Patent Application Publication No. 3427975 states that Rubber Chemistry and Technology, Vol. 85, No. 3, pp. 408-449 (2012), especially pp. 438, 440, 442, mentions that it can be obtained by thermal cracking of organic materials at 550-800° C. after removing oxygen, or by vacuum thermal cracking at relatively low temperatures (

[0027] ). The carbon black obtained by such a thermal cracking process is generally a regenerated carbon black lacking functional groups on its surface, as mentioned in

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

[0122] Regenerated carbon black may be carbon black lacking functional groups on its surface, or may be carbon black treated so that its surface contains functional groups. The treatment to make the surface of the regenerated carbon black contain functional groups can be implemented by conventional methods. For example, in European Patent Application Publication No. 3173251, carbon black containing hydroxyl and / or carboxyl groups on its surface is obtained by treating the carbon black obtained by the thermal cracking process with potassium permanganate under acidic conditions. In addition, in Patent No. 6856781, the carbon black obtained by the thermal cracking process is treated with an amino acid compound containing at least one thiol group or disulfide group to obtain a carbon black with its surface activated. The regenerated carbon black involved in this embodiment includes these carbon blacks treated so that the surface contains functional groups.

[0123] As the regenerated carbon black, commercially available products such as Strable Green Carbon and LD Carbon can be used.

[0124] From the viewpoint of weather resistance and reinforcement, the nitrogen adsorption specific surface area (N2SA) of carbon black is preferably 50 m 2 / g or more, more preferably 80m 2 / g or more, more preferably 100m 2 / g or more. In addition, from the viewpoints of dispersibility, low fuel consumption performance, fracture characteristics, and durability performance, it is preferably 250 m 2 / g or less, more preferably 220 m 2 / g or less. In addition, the N2SA of carbon black is measured by the above-mentioned measurement method.

[0125] When carbon black is contained, from the viewpoints of weather resistance and reinforcement, its content 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 further preferably 5 parts by mass or more. In addition, from the viewpoint of low fuel consumption performance, it is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, further preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less.

[0126] (Other fillers) There is no particular limitation on the fillers other than silica and carbon black. For example, aluminum hydroxide, alumina, calcium carbonate, magnesium sulfate, talc, clay, biochar, etc., which are commonly used in the tire industry, can be compounded. These other fillers can 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, further preferably 0.21 or less, further preferably 0.17 or less, further preferably 0.13 or less, and particularly preferably 0.10 or less. By 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. For example, it can be set to 0.01 or more, 0.02 or more, 0.05 or more, or it can be a filler without carbon black.

[0128] From the viewpoints of ensuring reinforcement and damping at the tread portion, the total content of the fillers 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, further preferably 70 parts by mass or more, and particularly preferably 80 parts by mass or more. From the viewpoint of the effects of the present invention, it is preferably 140 parts by mass or less, more preferably 120 parts by mass or less, further preferably 100 parts by mass or less, and particularly preferably 95 parts by mass or less.

[0129] (Silane coupling agent) Silica is preferably used in combination with a silane coupling agent. There is no particular limitation on the silane coupling agent, and any silane coupling agent that has been used in combination with silica in the tire industry can be used. However, from the viewpoint of more preferably obtaining the desired effects, it is preferably one or more silane coupling agents selected from sulfide-based silane coupling agents and mercapto-based silane coupling agents, and more preferably mercapto-based silane coupling agents.

[0130] As the sulfide-based silane coupling agent, for example, bis(3-triethoxysilylpropyl) disulfide, bis(3-triethoxysilylpropyl) tetrasulfide, etc. can be cited. These sulfide-based silane coupling agents can 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. For example, a compound having a mercapto group represented by the following formula (2), a compound in which the mercapto group is protected by an ester group 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) can be cited. Among them, for the reason that the effects of the present invention can be exerted more preferably, 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 preferred, and a compound represented by the following formula (3) is more preferred. These mercapto-based silane coupling agents can be used alone or in combination of two or more.

Chemical formula 1

Chemical formula 2

Chemical formula 3

Chemical formula 4

[0132] As the compound represented by the formula (2), for example, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, or a compound represented by the following formula (6) (Si363 manufactured by Evonik Degussa GmbH), etc. can be cited, and a compound represented by the following formula (6) can be preferably used. These can be used alone or in combination of two or more.

Chemical Formula 5

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

[0134] Compared with a sulfur-containing silane coupling agent such as bis(3-triethoxysilylpropyl)tetrasulfide, a compound containing the bonding unit A represented by the formula (4) and / or the bonding unit B represented by the formula (5) can suppress an increase in viscosity during processing. 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 considered because the sulfur-containing part of the bonding unit A is a C-S-C bond, so it is more thermally stable than tetrasulfide and disulfide, and the increase in Mooney viscosity is less.

[0135] From the viewpoint of suppressing an increase in viscosity during processing, the content of the bonding unit A is preferably 30 to 99 mol%, more preferably 50 to 90 mol%. In addition, the content of the bonding unit B is preferably 1 to 70 mol%, more preferably 5 to 65 mol%, and further preferably 10 to 55 mol%. In addition, the total content of the bonding units A and B is preferably 95 mol% or more, more preferably 98 mol% or more, and particularly preferably 100 mol%. In addition, the contents of the bonding units A and B also include the amounts in the case where the bonding units A and B are located at the ends of the silane coupling agent. The form when the bonding units A and B are located at the ends of the silane coupling agent is not particularly limited as long as units corresponding to the formulas (4) and (5) representing 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 -C7H of the bonding unit A 15 covers the mercapto group of the bonding unit B, the scorch time can be suppressed from becoming short while ensuring good reactivity with silica and 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 can be used alone or in combination of two or more.

[0138] The 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 can be cited; 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; chlorine-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane, etc. These other silane coupling agents can be used alone or in combination of two or more. As the silane coupling agents listed above, for example, silane coupling agents manufactured and sold by Momentive Performance Materials Inc., Evonik Degussa GmbH, etc. can be used.

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

[0140] <Plasticizer> The rubber composition according to the present embodiment contains a plasticizer. The plasticizer according to the present embodiment contains at least one selected from a hydrogenated resin component and vegetable oil, and further may contain other plasticizers. As the hydrogenated resin component, a hydrogenated dicyclopentadiene-based resin can be preferably used. As other plasticizers, for example, unhydrogenated resin components, oils, liquid rubbers, ester-based plasticizers, etc. can be cited. These plasticizers can be substances derived from mineral resources such as petroleum and natural gas, substances derived from biomass, or substances derived from naphtha recovered from rubber products and non-rubber products. In addition, low-molecular-weight hydrocarbon components obtained by thermally cracking and extracting used tires and products containing various components can also be used as plasticizers. These plasticizers can be used alone or in combination of two or more.

[0141] (Resin component) As the resin component, there is no particular limitation as long as it is a resin component commonly used in the tire industry. For example, adhesive resins such as dicyclopentadiene-based resins, aromatic vinyl resins, C9-based resins, C5-based resins, C5C9-based resins, terpene-based resins, rosin-based resins, and phenolic resins can be cited. These resin components can be used alone or in combination of two or more.

[0142] "Dicyclopentadiene-based resin" refers to: a resin containing cyclopentadiene (CPD) or dicyclopentadiene (DCPD), which may also be their hydrogenated products or modified products. As a dicyclopentadiene-based resin, for example, a DCPD / C9 resin containing dicyclopentadiene and the following C9 fraction as monomer components can be cited (this DCPD / C9 resin may also be their hydrogenated products or modified products), and a DCPD / C9 resin containing dicyclopentadiene and styrene as monomer components is preferred. As a dicyclopentadiene-based resin, for example, commercially available substances from ExxonMobil Corporation, ENEOS Corporation, Nippon Zeon Co., Ltd., Maruzen Petrochemical Co., Ltd., etc. can be used. These dicyclopentadiene-based resins can be used alone or in combination of two or more.

[0143] "Aromatic vinyl-based resin" refers to: a resin containing an aromatic vinyl compound such as styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene, etc. as the monomer component with the largest content, which may also be their hydrogenated products or modified products. As an aromatic vinyl-based resin, due to economic efficiency, 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 an aromatic vinyl-based resin, for example, commercially available substances from Kraton Corporation, Eastman Chemical Company, Mitsui Chemicals, Inc., etc. can be used. These aromatic vinyl-based resins can be used alone or in combination of two or more.

[0144] "C9-based resin" refers to: a resin obtained by polymerizing a C9 fraction, which may be a resin obtained by polymerizing 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. In addition, it may also be their hydrogenated products or modified products. As a C9 fraction, for example, petroleum fractions equivalent to 8 to 10 carbon atoms such as vinyltoluene, alkylstyrene, coumarone, indene, methylindene, dicyclopentadiene, etc. can be cited. These C9-based resins can be used alone or in combination of two or more.

[0145] "C5-based resin" refers to: a resin obtained by polymerizing a C5 fraction, which may also be their hydrogenated products or modified products. As a C5 fraction, for example, petroleum fractions equivalent to 4 to 5 carbon atoms such as cyclopentadiene, isoprene, pentane, isopentane, neopentane, pentene, pentadiene, etc. can be cited. These C5-based resins can be used alone or in combination of two or more.

[0146] "C5C9 resin" refers to: a resin obtained by copolymerizing the above-mentioned C5 fraction and the above-mentioned C9 fraction, or it may be a hydrogenated product or a modified product thereof. As the C5C9 petroleum resin, for example, commercially available substances from Tosoh Corporation, LUHUA Company, etc. can be used. These C5C9 resins can be used alone or in combination of two or more.

[0147] "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, or it may be a hydrogenated product or a modified product thereof. As a specific example of the terpene resin, for example, polyterpene resin containing only one or more of the above-mentioned terpene compounds as monomer components; aromatic modified terpene resin containing the above-mentioned terpene compounds and aromatic compounds as monomer components; terpene phenol resin containing the above-mentioned terpene compounds and phenolic compounds as monomer components, etc. As the aromatic compound which is the monomer component constituting the aromatic modified terpene resin, for example, styrene, α-methylstyrene, vinyltoluene, divinyltoluene, etc. can be cited. As the phenolic compound which is the monomer component constituting the terpene phenol resin, for example, phenol, bisphenol A, cresol, xylenol, etc. can be cited. These terpene resins can be used alone or in combination of two or more.

[0148] "Rosin resin" refers to: a resin containing rosin acid compounds such as abietic acid, neoabietic acid, palustric acid, isopimaric acid, etc. as the monomer component with the highest content, or it may be a hydrogenated product or a modified product thereof. As the rosin resin, there is no particular limitation. For example, natural resin rosin, rosin modified resin obtained by hydrogenating, disproportionating, dimerizing, esterifying, etc. of it can be cited. These rosin resins can be used alone or in combination of two or more.

[0149] "Phenolic resin" refers to: a resin containing phenolic compounds such as phenol, cresol, etc. as the monomer component with the highest content. As the phenolic resin, there is no particular limitation. Phenol formaldehyde resin, alkylphenol formaldehyde resin, alkylphenol acetylene resin, oil-modified phenol formaldehyde resin, etc. can be cited. These phenolic resins can be used alone or in combination of two or more.

[0150] From the viewpoint of grip performance, the softening point of the resin component is preferably 60 °C or higher, more preferably 70 °C or higher, and further preferably 80 °C or higher. In addition, from the viewpoints 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 further preferably 130 °C or lower. In addition, the softening point of the resin component is measured by the above-mentioned measurement method.

[0151] When a hydrogenated resin component is contained, from the viewpoint of the effects of the present invention, its content 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 further preferably 5 parts by mass or more. In addition, the content is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, and further preferably 30 parts by mass or less.

[0152] From the viewpoint of the effects of the present invention, the content of the resin component relative to 100 parts by mass of the rubber component (when a plurality of resin components are used in combination, it is the total amount of all) is preferably 1 part by mass or more, more preferably 3 parts by mass or more, further preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more. In addition, the content is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and further 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, further preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more. In addition, from the viewpoint of suppressing heat generation, it is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and further preferably 40 parts by mass or less.

[0154] (Oil) As the oil, for example, mineral oil, vegetable oil, animal oil, etc. can be cited. In addition, from the viewpoint of life cycle assessment, oil refined from waste oil after being used in a rubber mixer or an engine, or waste cooking oil used in a restaurant can also be used.

[0155] In this specification, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. As the mineral oil, paraffin-based oil (mineral oil), naphthenic oil, aromatic oil, etc. can be cited. As a specific example of the mineral oil, for example, MES (Mild Extract Solvate), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), RAE (Residual Aromatic Extract), etc. can be cited. In addition, due to environmental countermeasures, oil with a lower content of polycyclic aromatic (polycyclic aromatic compound: PCA) compounds can also be used. As the oil with a low PCA content, MES, TDAE, heavy naphthenic oil, etc. can be cited.

[0156] In this specification, "vegetable oil" refers to, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice bran oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grape seed oil, wood wax, etc. Further, as vegetable oils, 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 cooking oils obtained by recycling oils used as edible oils, etc. can also be cited. In addition, vegetable oils can be liquid or solid at normal temperature (25°C). These vegetable oils can be used alone or in combination of two or more.

[0157] The vegetable oil involved in this embodiment preferably contains acylglycerol, and more preferably contains triacylglycerol. In addition, in this specification, acylglycerol refers to a compound in which the hydroxyl group of glycerol forms an ester bond with a fatty acid. As acylglycerol, there is no particular limitation, and it can be any one of 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, and triacylglycerol. Further, acylglycerol can be a monomer, a dimer, or a polymer of trimer or higher. In addition, acylglycerols of dimer or higher can be obtained by thermal polymerization, oxidative polymerization, etc. In addition, acylglycerol can be liquid or solid at normal temperature (25°C).

[0158] As a method for confirming whether acylglycerol is contained in the rubber composition, there is no particular limitation. For example, it can be confirmed by the following 1 1H-NMR measurement. Specifically, the rubber composition compounded with triacylglycerol is immersed in deuterated chloroform at normal temperature (25°C) for 24 hours. After removing the rubber composition, 1H-NMR is measured at room temperature. 1 When the signal of tetramethylsilane (TMS) is set to 0.00 ppm, signals around 5.26 ppm, around 4.28 ppm, and around 4.15 ppm can be observed. It is speculated that these signals are signals from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In addition, "around" in this paragraph refers to the range of ±0.10 ppm.

[0159] As the above fatty acid, there is no particular limitation, and it can be an unsaturated fatty acid or a saturated fatty acid. As unsaturated fatty acids, monounsaturated fatty acids such as oleic acid or polyunsaturated fatty acids such as linoleic acid and linolenic acid can be cited. In addition, as saturated fatty acids, butyric acid, lauric acid, etc. can be cited.

[0160] Among them, as the above fatty acid, it is preferable to contain a fatty acid with fewer double bonds, that is, a saturated fatty acid or a monounsaturated fatty acid, preferably oleic acid. As such a vegetable oil containing a fatty acid, for example, a vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid can be used, or a modified vegetable oil such as a transesterified vegetable oil can also be used. In addition, in order to produce a vegetable oil containing such a fatty acid, plants can also be improved through variety improvement, genetic modification, etc.

[0161] As the vegetable oil, for example, commercially available substances from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoy Co., Ltd., H&R Co., Ltd., 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 an oil alcohol 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, further preferably 75% by mass or more, further preferably 80% by mass or more, and particularly preferably 85% by mass or more.

[0164] When a vegetable oil is contained, from the viewpoint of the effects of the present invention, its content 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 further preferably 5 parts by mass or more. In addition, the content is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and further preferably 20 parts by mass or less.

[0165] From the viewpoint of the effects of the present invention, the content of the oil relative to 100 parts by mass of the rubber component (when multiple oils are used in combination, it is the total amount of all) is preferably 1 part by mass or more, more preferably 3 parts by mass or more, further preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more. In addition, the content is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and 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 normal 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 cited. These liquid rubbers can be used alone or in combination of two or more.

[0167] As ester plasticizers, for example, dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di-2-ethylhexyl azelate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), dilauryl 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. can be cited. These ester plasticizers can be used alone or in combination of two or more.

[0168] From the viewpoint of followability to the road surface, the total content P of the plasticizer relative to 100 parts by mass of the rubber component (when multiple plasticizers are used in combination, it is the total amount of all) is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, further preferably 25 parts by mass or more, and particularly preferably 30 parts by mass or more. In addition, 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, further preferably 60 parts by mass or less, and particularly preferably 50 parts by mass or less.

[0169] <Other compounding agents> In the rubber composition according to this embodiment, in addition to the above components, compounding agents commonly used in the tire industry in the past can be appropriately contained, for example, vulcanized rubber particles, processing aids, waxes, anti-aging agents, stearic acid, zinc oxide, vulcanizing agents, vulcanization accelerators, etc.

[0170] Vulcanized rubber particles are particles made of vulcanized rubber. Specifically, rubber powder specified in JIS K 6316:2017 can be used. From the viewpoints of environmental concerns and cost, recycled rubber powder made from crushed waste tires, etc. is preferred. These can be used alone or in combination of two or more.

[0171] As the vulcanized rubber particles, there is no particular limitation, and they can be non-modified vulcanized rubber particles or modified vulcanized rubber particles. As commercially available products of vulcanized rubber, for example, products of Lehigh Company, Murakami Rubber Industry Co., Ltd., etc. can be used.

[0172] When vulcanized rubber particles are contained, their content relative to 100 parts by mass of the rubber component can be appropriately adjusted, for example, in the range of more than 1 part by mass and less than 80 parts by mass.

[0173] As processing aids, for example, 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. can be cited. As processing aids, for example, substances commercially available from companies such as Schill + Seilacher and Performance-Additives can be used. These processing aids can be used alone or in combination of two or more.

[0174] When a processing aid is contained, from the viewpoint of exerting the effect of improving processability, its content relative to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 1 part by mass, and still more preferably more than 1.5 parts by mass. In addition, from the viewpoints of abrasion resistance and breaking strength, it is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and still more preferably less than 5.0 parts by mass.

[0175] The wax is not particularly limited, and any one of the substances commonly used in the tire industry can be preferably used. For example, mineral waxes, waxes derived from plants, etc. can be cited. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Waxes derived from plants refer to waxes derived from natural resources such as plants. Among them, mineral waxes are preferred. As waxes derived from plants, for example, rice bran wax, carnauba wax, candelilla wax, etc. can be cited. As mineral waxes, for example, paraffin wax, microcrystalline wax, selected special waxes thereof, etc. can be cited, and paraffin wax is preferred. In addition, the wax according to this embodiment does not contain stearic acid. The wax, for example, substances commercially available from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., etc. can be used. These waxes can be used alone or in combination of two or more.

[0176] When wax is contained, from the viewpoint of the weather resistance of the rubber, its 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. In addition, from the viewpoint of preventing the whitening of the tire caused by blooming, it is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less.

[0177] As the anti-aging agent, there is no particular limitation, and examples thereof include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine, 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'-dimethylxyl-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), 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-tert-butyl-4-methylphenol, styrenated phenol; bis-, tris-, and polyphenol-based anti-aging agents such as tetrakis[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane, etc. Among them, p-phenylenediamine-based anti-aging agents and quinoline-based anti-aging agents are preferred, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and polymers of 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. As commercially available products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis Co., etc. can be used. These anti-aging agents can be used alone in one kind or in combination of two or more kinds.

[0178] When containing the anti-aging agent, from the viewpoint of ozone crack resistance of the rubber, its 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. In addition, from the viewpoints of abrasion resistance and wet grip performance, it is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less.

[0179] When containing stearic acid, from the viewpoint of processability, its 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. In addition, 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, from the viewpoint of processability, its 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. In addition, from the viewpoint of abrasion resistance, it is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less.

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

[0182] When sulfur is contained, from the viewpoint of ensuring a sufficient vulcanization reaction, its 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. In addition, from the viewpoint of preventing deterioration, it is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and further preferably 3.5 parts by mass or less. In addition, when using sulfur containing oil as the vulcanizing agent, the content of the vulcanizing agent is the total content of the pure sulfur component contained in the sulfur containing oil.

[0183] As vulcanizing agents other than sulfur, for example, alkylphenol / sulfur chloride condensates, 1,6-hexamethylene disodium dithiocarbamate dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, etc. can be cited. These vulcanizing agents other than sulfur can use commercially available substances from companies such as Tago Chemical Industry Co., Ltd., Lanxess AG, and Flexis.

[0184] As vulcanization accelerators, for example, sulfenamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, guanidine-based vulcanization accelerators, thiuram-based vulcanization accelerators, dithiocarbamate-based vulcanization accelerators, caprolactam disulfide, etc. can be cited. These vulcanization accelerators can be used alone or in combination of two or more. Among them, from the viewpoint of being able to better obtain the desired effect, it is preferable to select one or more vulcanization accelerators from sulfenamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, and guanidine-based vulcanization accelerators, and more preferably to use a combination of sulfenamide-based vulcanization accelerators and guanidine-based vulcanization accelerators.

[0185] As sulfenamide-based vulcanization accelerators, for example, N-tert-butyl-2-benzothiazole sulfenamide (TBBS), N-cyclohexyl-2-benzothiazole sulfenamide (CBS), N,N-dicyclohexyl-2-benzothiazole sulfenamide (DCBS), etc. can be cited. Among them, TBBS and CBS are preferred.

[0186] As thiazole-based vulcanization accelerators, for example, 2-mercaptobenzothiazole (MBT) or its salts, di-2-benzothiazole disulfide (MBTS), 2-(2,4-dinitrophenyl)mercaptobenzothiazole, 2-(2,6-diethyl-4-morpholinothio)benzothiazole, etc. can be cited. Among them, MBTS and MBT are preferred, and MBTS is more preferred.

[0187] As guanidine-based vulcanization accelerators, for example, 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of dicatecholborate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenyl guanidine, 1,3-di-o-cumenyl-2-propionylguanidine, etc. may be mentioned. Among them, DPG is preferred.

[0188] When the vulcanization accelerator is contained, its 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. In addition, the content of the vulcanization accelerator relative to 100 parts by mass of the rubber component is preferably 8.0 parts by mass or less, more preferably 6.0 parts by mass or less, and further preferably 4.0 parts by mass or less. By setting the content of the vulcanization accelerator within the above range, it tends to ensure the breaking strength and elongation at break.

[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 the above-mentioned respective components using a rubber kneading device such as an open roll mill, a closed kneader (Banbury mixer, kneader, etc.).

[0190] The kneading process, for example, includes the following basic kneading process: kneading compounding agents and additives other than the vulcanizing agent and the vulcanization accelerator, and a final kneading process (F kneading): adding the vulcanizing agent and the vulcanization accelerator to the kneaded product obtained in the basic kneading process and kneading. Further, the above basic kneading process can also be decomposed into a plurality of processes as needed.

[0191] As the kneading conditions, there are no particular limitations. For example, a method of kneading for 3 to 10 minutes at a discharge temperature of 150 to 170°C in the basic kneading process and kneading for 1 to 5 minutes at 70 to 110°C in the final kneading process may be mentioned. As the vulcanization conditions, there are no particular limitations. For example, a method of vulcanizing for 10 to 30 minutes at 150 to 200°C may be mentioned.

[0192] A tire having a tread portion composed of the above rubber composition can be manufactured by a conventional method. That is, the tire can be manufactured by: compounding the above components as required with respect to the rubber component, extruding the prepared unvulcanized rubber composition in the shape of the first layer of the tread portion, laminating the obtained tread portion together with the inner rubber layer of the tread portion and other tire components on a tire building machine, forming an unvulcanized tire by a conventional method, and heating and pressurizing the obtained unvulcanized tire in a vulcanizer. As the vulcanization conditions, there are no particular limitations, and for example, a method of vulcanizing at 150 to 200 °C for 10 to 30 minutes can be cited.

[0193] [Use of the tire] The tire according to the present embodiment can be preferably used for passenger car tires, truck / bus tires, two-wheel vehicle tires, and racing tires, and among them, it is preferably used for passenger car tires. In addition, a passenger car tire means a tire premised on being mounted on an automobile that travels on four wheels and has a maximum load capacity of 1000 kg or less.

Examples

[0194] Examples (Examples) considered to be preferable at the time of implementation are shown below, but the scope of the present invention is not limited to the examples. A tire having a first layer of the tread portion obtained by compounding using various reagents shown below according to the compounding ratios in Tables 1 and 2 was studied, and the results calculated based on the following evaluation methods are shown in Tables 1 and 2.

[0195] The following summarizes the various reagents used in the examples and comparative examples. 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-extended oil product) SBR2: T3830 manufactured by Asahi Kasei Corporation (styrene content: 33% by mass, vinyl content: 34% by mass, Mw: 950,000, non-extended oil product) SBR3: Hydrogenated SBR manufactured in Production Example 1 below (hydrogenation rate: 80 mol%, styrene content: 30% by mass, Mw: 480,000) BR: CB24 manufactured by Lanxess Corporation (BR synthesized using an Nd-based catalyst, cis content: 96 mol%, Mw: 500,000) Carbon black: SHOBLACK N220 manufactured by Cabot Japan Limited (N2SA: 111m 2 / g) Silica 1: ULTRASIL (registered trademark) VN3 manufactured by Evonik Degussa GmbH (N2SA: 175m2 / g, average primary particle size: 17 nm) Silica 2: ULTRASIL (registered trademark) 9100GR manufactured by Evonik Degussa AG (N2SA: 230 m 2 / g, average primary particle size: 15 nm) Silane coupling agent 1: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa AG Silane coupling agent 2: NXT-Z45 (mercapto-based silane coupling agent, copolymer of bonding unit A and bonding unit B (bonding unit A: 55 mol%, bonding unit B: 45 mol%)) manufactured by Momentive Performance Materials Inc. Oil 1: VivaTec500 (TDAE oil) manufactured by H&R Oil 2: Sunflower oil manufactured by Nisshin Oillio Group, Ltd. (content of oleic acid contained in constituent fatty acids: 55% by mass, total content of polyunsaturated fatty acids contained in constituent fatty acids: 8% by mass) Resin component: Oppera PR395 (hydrogenated DCPD / C9 resin, softening point: 118°C) manufactured by ExxonMobil Wax: OZOACE 0355 (paraffin wax) of Nippon Seiro Co., Ltd. Antioxidant: NOCRAC 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. Zinc oxide: Zinc Oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Stearic acid beads "TSUBAKI" manufactured by NOF Corporation Sulfur: HK-200-5 (powdered sulfur containing 5% oil) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator: NOCCELLER CZ (N-cyclohexyl-2-benzothiazole sulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.

[0196] Production Example 1: Production of hydrogenated SBR 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 were added to a heat - resistant reaction vessel fully replaced with nitrogen, and stirred at 50 °C for 5 hours to carry out a polymerization reaction. Then, while supplying hydrogen at a gauge pressure of 0.4 MPa, it was stirred for 20 minutes to react with the lithium at the unreacted polymer end to obtain lithium hydride. The hydrogen supply pressure was set to 0.7 MPa absolute pressure, the reaction temperature was set to 90 °C, and hydrogenation was carried out using a catalyst mainly composed of titanocene dichloride. When the cumulative amount of hydrogen absorption reached the target hydrogenation rate, the reaction temperature was set to room temperature, the hydrogen pressure was restored to atmospheric pressure and withdrawn from the reaction vessel. The reaction solution was added to water and stirred, and the solvent was removed by steam stripping to obtain hydrogenated SBR.

[0197] (Examples and Comparative Examples) According to the compounding recipe shown in Table 1, using a 1.7 L closed - type Banbury mixer, the reagents other than sulfur and vulcanization accelerators were kneaded for 1 - 10 minutes until the discharge temperature reached 150 - 160 °C to obtain a kneaded product. Then, using a twin - screw open - type rolling mill, sulfur and vulcanization accelerators were added to this kneaded product and kneaded for 4 minutes until it reached 105 °C to obtain an unvulcanized rubber composition. By using this unvulcanized rubber composition, it was extruded and formed according to the shape of the first layer (thickness: 5.0 mm) of the tread on an extruder equipped with a die of a specified shape, and laminated together with the second layer (thickness: 2.0 mm) of the tread and other tire components to produce an unvulcanized tire, which was press - vulcanized at 170 °C for 12 minutes to obtain each test tire (size: 215 / 55R18) described in Tables 1 and 2.

[0198] (Measurement of tanδ at 30 °C and E* at 30 °C) For each vulcanized rubber test piece with a length of 20 mm × width of 4 mm × thickness of 1 mm cut out from the inside of the first layer of the tread of each test tire, with the tire circumferential direction as the long side and the tire radial direction as the thickness direction, the loss tangent tanδ and the complex elastic modulus E* were measured using a dynamic viscoelasticity measuring device (EPLEXOR series manufactured by GABO) under the conditions of a temperature of 30 °C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of ±1%, and a tensile mode.

[0199] (Tensile Test) For a No. 7 dumbbell - shaped test piece with a thickness of 1 mm cut out from the inside of the first layer of the tread of each test tire, with the tire circumferential direction as the tensile direction and the tire radial direction as the thickness direction, according to JIS K 6251:2017, a tensile test was carried out in an atmosphere of 23 °C and at a tensile speed of 3.3 mm / s, and the modulus at 200% elongation (M200 )(MPa).

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

[0201] <Wear resistance performance> Install each test tire on a domestic FF vehicle, measure the groove depth of the tread surface after traveling 8000 km, calculate the traveling distance when the tire groove depth decreases by 1 mm, and express it as an index when Comparative Example 2 is set to 100. The larger the index, the more excellent the wear resistance performance.

[0202] <Comprehensive performance> Express 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 the embodiments of the present invention are as follows.

[0206] 〔1〕A tire, characterized in that it is a tire having a tread portion with at least one rubber layer, and the ratio of the tire weight G (kg) to the maximum load capacity W L (kg) (G / W L ) 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 contains at least one selected from a hydrogenated resin component and a vegetable oil, when the grounding area ratio of the tread portion in the contact surface is set to R and the total content of the plasticizer relative to 100 parts by mass of the rubber component in the rubber composition is set to P (parts by mass), the product of R and P (R×P) is greater 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-mentioned 〔1〕 or 〔2〕, wherein the tanδ (tanδ at 30 °C) of the rubber composition is 0.15 or less at 30 °C. 〔4〕The tire according to the above-mentioned 〔3〕, wherein tanδ at 30 °C / R is less than 0.60 (preferably less than 0.50, more preferably greater than 0.10 and less than 0.45). 〔5〕The tire according to any one of the above-mentioned 〔1〕 to 〔4〕, wherein (R × P) / (G / W L ) is greater than 1000 and less than 2000. 〔6〕The tire according to any one of the above-mentioned 〔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-mentioned 〔6〕, wherein S / R is less than 45 (preferably greater than 3 and less than 40). 〔8〕The tire according to any one of the above-mentioned 〔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 the above-mentioned 〔1〕 to 〔8〕, wherein the rubber composition contains a mercapto-based silane coupling agent. 〔10〕The tire according to any one of the above-mentioned 〔1〕 to 〔9〕, wherein when the modulus of the rubber composition at 200% elongation is set as M 200 (MPa) and the complex elastic modulus of the rubber composition at 30 °C is set as 30 °C E* (MPa), M 200 of the rubber composition, 30 °C E* and 30 °C tanδ satisfy the following formula (1). M 200 × 30 °C E* / 30 °C tanδ ≧ 200......(1) 〔11〕The tire according to any one of the above-mentioned 〔1〕 to 〔10〕, wherein the rubber component contains a hydrogenated styrene-butadiene rubber.

Claims

1. A tire, characterized in that: The tire has a tread portion having at least one rubber layer. Tire weight G relative to the tire's maximum load capacity W L Ratio G / W L Below 0.0140, G and W L The unit is kg. The 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 hydrogenated resin components and vegetable oils, When the contact area ratio of the tread portion in the contact surface is defined as R and the total content of the plasticizer in the rubber composition relative to 100 parts by mass of the rubber component is defined as P, the product of R and P (R×P) is greater than 10.0, The unit of P is parts by mass.

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

3. The tire according to claim 1, wherein: The rubber composition has a tan δ at 30° C., that is, tan δ at 30° C. of 0.15 or less.

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

60.

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

6. The tire according to any one of claims 1 to 4, wherein: The total styrene amount S in the rubber component is 25 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 size 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. The tire according to any one of claims 1 to 4, wherein The modulus of the rubber composition at 200% stretching is defined as M 200 , when the complex elastic modulus of the rubber composition at 30°C is set to 30°C E*, the M of the rubber composition 200 , 30℃E* and 30℃tanδ satisfy the following formula (1), M 200 ×30℃E* / 30℃tanδ≧200……(1), M 200 The unit of and 30℃E* is MPa.

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

12. The tire according to any one of claims 1 to 4, wherein G / W L It is above 0.0110.

13. The tire according to any one of claims 1 to 4, wherein: R×P is less than 35.0.

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