Pneumatic tires

Abstract

To provide a pneumatic tire excellent in riding comfort performance and steering stability during high-speed traveling.SOLUTION: A pneumatic tire includes a tread part and a belt layer. The belt layer is formed such that reinforcement cords each made of a steel monofilament are covered with a rubber composition. In the pneumatic tire, the number e (cords) of the reinforcement cords arranged per 5 cm in a tire width direction, a thickness G (mm) of the tread part, and a complex elastic modulus E*(MPa) measured for the rubber composition under the conditions of a temperature of 70°C, an initial strain of 5%, a dynamic strain of ±1%, a frequency of 10 Hz, and a deformation mode of stretch, satisfy the following (formula 1): e÷G×E*≥70...(formula 1).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a pneumatic tire, and more particularly, to a pneumatic tire having a tread portion and a belt layer. [Background technology]

[0002] In recent years, there has been a growing demand for automobiles to have lower fuel consumption due to growing concerns about environmental issues and economic reasons, and there is also a strong demand for improved fuel efficiency in pneumatic tires (hereinafter simply referred to as "tires") that are fitted to automobiles.

[0003] The fuel efficiency of a tire can be evaluated by its rolling resistance, and it is known that the smaller the rolling resistance, the more fuel efficient the tire.

[0004] Therefore, it has been proposed to reduce the rolling resistance by modifying the compounding of the rubber composition constituting the tread portion of the tire (for example, Patent Documents 1 to 4). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-178034 A [Patent Document 2] JP 2019-089911 A [Patent Document 3] WO2018 / 186367 publication [Patent Document 4] JP 2019-206643 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the construction of expressways in recent years, it is not uncommon for people to travel long distances on expressways, and so there is a strong demand for improved ride comfort and handling stability when traveling at high speeds. However, the above-mentioned conventional technologies cannot be said to fully meet these demands.

[0007] Therefore, an object of the present disclosure is to provide a pneumatic tire that is excellent in ride comfort and handling stability during high-speed driving. [Means for solving the problem]

[0008] The present inventors have conducted intensive research into solving the above problems, and have found that the above problems can be solved by the disclosure described below, thereby completing the present disclosure.

[0009] The present disclosure relates to A pneumatic tire having a tread portion and a belt layer, The belt layer is configured by covering a reinforcing cord made of a steel monofilament with a rubber composition, The number of reinforcing cords arranged per 5 cm in the tire width direction e (pieces), the thickness G (mm) of the tread portion, and the complex modulus E of the rubber composition measured under the conditions of temperature: 70° C., initial strain: 5%, dynamic strain: ±1%, frequency: 10 Hz, and deformation mode: extension * (MPa) satisfies the following (Formula 1): e÷G×E * ≧70··············(Formula 1) Effect of the Invention

[0010] According to the present disclosure, it is possible to provide a pneumatic tire that is excellent in ride comfort and handling stability during high-speed driving. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] [1] Characteristics of the tire according to the present disclosure First, the features of the tire according to the present disclosure will be described.

[0012] 1. Overview The tire according to the present disclosure is a pneumatic tire having a tread portion and a belt layer, and the belt layer is configured by coating a reinforcing cord made of a steel monofilament (steel monofilament cord: hereinafter also simply referred to as a "monofilament cord") with a rubber composition.

[0013] The number of reinforcing cords arranged per 5 cm in the tire width direction (hereinafter also referred to as "ends") e (pieces / 5 cm), the thickness of the tread portion (hereinafter also referred to as "tread rubber gauge") G (mm), and the complex modulus of elasticity E of the rubber composition measured under the conditions of temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10 Hz, and deformation mode: extension. * (MPa) satisfies the following (Equation 1). e÷G×E * ≧70··············(Formula 1)

[0014] By having these characteristics, it is possible to provide a pneumatic tire that is excellent in ride comfort and handling stability during high-speed driving, as will be described later.

[0015] In the above description, ends e refers to the average number of monofilament cords arranged per 5 cm in the width direction of the tire when the tire is mounted on a regular rim, the internal pressure is 250 kPa, and there is no load. Simply put, ends e can be determined by measuring the number of monofilament cords arranged in an area of ​​5 to 10 cm wide centered on the tire equatorial plane on a cross-sectional section cut out in the radial direction of the tire with a thickness of 2 to 4 cm, and calculating the average number per 5 cm.

[0016] In the above, the tread rubber gauge G is the linear distance from the tread surface on the tire equatorial plane to the surface of the monofilament cord of the outermost belt layer in the radial cross section of the tire when the tire is mounted on a regular rim, the internal pressure is 250 kPa, and there is no load. When a groove is formed on the tread equatorial plane, the linear distance from the intersection point of the line obtained by connecting the tire ground contact surface ends of the groove and the tire equatorial plane to the outermost belt layer is taken as the distance G. When no monofilament cord of the outermost belt layer layer is present on the tire equatorial plane, the intersection point of the line connecting two points on the tire radial outermost side of a pair of monofilament cords closest to the equatorial plane and the equatorial plane is regarded as the position of the outermost belt layer, and the linear distance to the tread surface is taken as the distance G. For simplicity, the measurement can be performed in a state where the bead portion of a section cut out in the tire width direction with a thickness of 2 to 4 mm is pressed down to match the corresponding rim width.

[0017] Here, "genuine rim" refers to a rim that is specified for each tire by a standard system that includes the standard on which the tire is based, such as the standard rim for the applicable size listed in the "JATMA YEAR BOOK" for JATMA (Japan Automobile Tire Manufacturers Association), the "Measuring Rim" listed in the "STANDARDS MANUAL" for ETRTO (The European Tire and Rim Technical Organisation), and the "Design Rim" listed in the "YEAR BOOK" for TRA (The Tire and Rim Association, Inc.). In the case of a tire not specified by a standard, it refers to a rim that can be assembled to a rim and can hold internal pressure, that is, a rim that does not leak air from between the rim and tire, and has the smallest rim diameter and the next narrowest rim width.

[0018] In addition, the complex modulus E * can be measured using a viscoelasticity measuring device such as "IPLEXER (registered trademark)" manufactured by GABO.

[0019] 2. Mechanism of effect manifestation in the tire according to the present disclosure The mechanism by which the effects of the tire according to the present disclosure are manifested, that is, the mechanism by which a pneumatic tire excellent in ride comfort and handling stability during high-speed driving can be provided, is presumed to be as follows.

[0020] One method for improving ride comfort during high-speed driving is to thicken the tread rubber gauge to make it harder for vibrations from the road surface to be transmitted, but if the tread rubber gauge is made thicker, the centrifugal force acting on the tread increases even for tires with the same outer diameter, making it easier for the outer diameter to grow during high-speed driving. As a result, the contact shape, i.e., the shape of the tire surface in the tire width direction, becomes rounded, which raises concerns about reduced steering stability during high-speed driving.

[0021] Therefore, in the present disclosure, a belt layer in which cords (monofilament cords) made of monofilaments (single wires) are arranged is used as a belt layer reinforcing the tread, instead of cords (twisted wire cords) made of twisted wires. Since monofilament cords are not twisted and can be made into rigid cords, it is believed that the belt layer has high restraint, and deformation and vibration are less likely to occur in the tread portion.

[0022] However, in the case of a tire using a belt layer using a monofilament cord, the high restraint of the belt layer reduces the damping property in the tread portion, and even slight vibrations in the tread portion are easily transmitted, which may lead to a deterioration in ride comfort. In particular, when traveling at high speeds, the belt layer comes into contact with the ground repeatedly more frequently, which is thought to result in a significant deterioration in ride comfort.

[0023] Therefore, in the present disclosure, in addition to increasing the restraining ability of the belt layer by using a belt layer using a monofilament cord, as the tread rubber gauge G becomes thicker, the product of the number of monofilament cords arranged e (pieces / 5 cm) and the complex modulus of the rubber composition coated on the monofilament cord is increased.

[0024] This makes it possible to increase the reaction force generated in the belt layer while improving the restraint performance, thereby making it possible to increase the force generated in the tread portion while suppressing changes in the contact shape. It is believed that this makes it possible to maintain ride comfort during high-speed driving while also improving handling stability.

[0025] That is, the complex modulus E * is a parameter related to rigidity, and the larger the value, the higher the rigidity, which can suppress the occurrence of rounding of the tread portion during high-speed driving, and at the same time, it is thought that it is easier to obtain a large reaction force on the tread surface. In addition, since the rigidity of the entire tread surface can be increased, it is thought that it is easier to suppress large deformation of the tread portion when an impact is transmitted.

[0026] On the other hand, the tread rubber gauge can be considered as a parameter indicating the centrifugal force acting on the tread and the ride comfort, and it is considered that the larger the value, the better the ride comfort performance, but the greater the centrifugal force acting on the tread. Therefore, it is considered that by increasing the product of the complex modulus of the ends of the monofilament cord and the rubber composition covering the monofilament cord in response to an increase in the tread rubber gauge, the restraining force against the deformation of the tread can be sufficiently secured.

[0027] As a result of various experiments and studies, the complex modulus of elasticity E measured in the deformation mode: extension, for the end length (5 cm), tread rubber gauge G (mm), and rubber composition, under the conditions of temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10Hz. * It has been found that when the tire pressure (MPa) and tire fatigue strength (T / S) satisfy the following (Formula 1), it is possible to maintain ride comfort during high-speed driving while also improving steering stability. e÷G×E * ≧70··············(Formula 1)

[0028] In addition, the above [e÷G×E * It was found that 75 or more is more preferable, and 80 or more is even more preferable.

[0029] In the present disclosure, the specific tread rubber gauge G (mm) is preferably 12.0 mm or less, and more preferably 10.0 mm or less. If it exceeds 12.0 mm, the distance from the tread surface to the belt layer becomes too long, and the contribution of the rigidity of the belt layer is insufficient, which is considered to result in insufficient improvement in steering stability during high-speed driving. On the other hand, the lower limit is preferably 6.0 mm or more, and more preferably 8.0 mm or more. If it is less than 6.0 mm, it is considered that the impact from the tread portion is easily transmitted to the belt layer, thereby reducing the effect of improving the ride comfort performance of the tire.

[0030] [2] More preferred aspects of the tire according to the present disclosure The tire according to the present disclosure can achieve even greater effects by adopting the following aspects.

[0031] 1.Improvement of adhesion of rubber composition In the tire according to the present disclosure, it is preferable to improve the adhesion of the rubber composition.

[0032] As described above, in the present disclosure, a steel monofilament cord is used as the reinforcing cord of the belt layer. By forming the reinforcing cord into a monofilament in this way, the cord can be made less stretchable and more rigid, and at the same time, the wire diameter of the cord can be made smaller. Therefore, when the cord is covered with the same amount of rubber composition, the rubber thickness of the entire belt layer can be made thinner, but when traveling at high speeds, the shear strain per rubber thickness increases and the contact area between the rubber and each steel cord becomes smaller, increasing the risk of separation between the cord and the rubber composition.

[0033] Therefore, it is preferable to reduce the risk of separation by improving the adhesion between the cord and the rubber composition. At the same time, it is believed that by improving the adhesion, the rubber composition and the cord are more firmly bound, which makes it easier to generate force in the belt layer and improves the steering stability during high-speed driving.

[0034] As a specific means, it is preferable to use a rubber composition containing 80 parts by mass or more and 100 parts by mass or less of isoprene-based rubber (IR) per 100 parts by mass of the rubber component, as well as 5 parts by mass or more and 80 parts by mass or less of carbon black and 0.1 parts by mass or more and 5 parts by mass or less of organic acid cobalt, relative to 100 parts by mass of the rubber component, as the rubber for covering the cord.

[0035] By using IR, which has excellent strength, as the main rubber component and by incorporating an appropriate amount of carbon black, which has excellent reinforcing properties, it is possible to ensure that the rubber covering the cord exhibits sufficient strength, and by incorporating an appropriate amount of organic acid cobalt, it is believed that the adhesion to the steel monofilament cord can be improved.

[0036] In this case, if an aliphatic (thiosulfate) sodium salt derivative such as sodium hexamethylene-1,6-bis(thiosulfate) dihydrate is contained in an amount of 0.1 part by mass or more and 5 parts by mass or less per 100 parts by mass of the rubber component together with the organic acid cobalt, the initial adhesion / heat-resistant adhesion / water-resistant adhesion of the rubber composition to the steel monofilament cord can be balanced, and the adhesion to the steel monofilament cord can be further improved.

[0037] Also, it is preferable to provide an adhesive layer between the rubber composition and the steel monofilament cord as a means for improving adhesion. Specifically, an adhesive composition containing a polybenzoxazine compound including units represented by the following (Chemical Formula 1) to (Chemical Formula 4) is applied to the surface of the steel monofilament cord to form a coating layer, whereby the rubber composition and the steel monofilament cord can be sufficiently bonded via this adhesive layer, thereby further reducing the risk of separation.

[0038] [ka]

[0039] [ka]

[0040] [ka]

[0041] [ka]

[0042] In the above (Chemical formula 1) and (Chemical formula 2), X1 is a hydrocarbon selected from aliphatic, alicyclic, and aromatic groups, or a combination thereof, and may have any of S, O, N, and P heteroatoms, or a structure in which these heteroatoms are continuously linked. X2 has an (S)n structure in which n (1 to 8) S atoms are linked, and may have a hydrocarbon selected from aliphatic, alicyclic, and aromatic groups, and any of S, O, N, and P, and / or a combination thereof. In the above (Chemical formula 3) and (Chemical formula 4), X1 is a hydrocarbon selected from aliphatic, alicyclic, and aromatic groups, or a combination thereof, and may have an (S)n structure in which n (1 to 8) S atoms are linked.

[0043] 2. Monofilament cord ( Reinforcement Ends and outer diameter of cord In this disclosure, the ends e (pieces / 5 cm) of the monofilament cord and the cross-sectional area A (mm 2 ) preferably satisfies e×A>4.0 (equation 4), and more preferably satisfies e×A>5.0.

[0044] The product of the cross-sectional area A per monofilament cord and the ends e is the total area occupied by the entire monofilament cord in the cross section of the belt layer. In this way, by increasing the area occupied by the monofilament cord in the cross section of the belt layer, the rigidity of the tread portion can be increased and large input can be prevented from being applied to the belt layer, which is considered to result in a better ride comfort performance during high-speed driving.

[0045] The cross-sectional shape of the monofilament cord is preferably circular, but may be elliptical or track-shaped.

[0046] The specific outer diameter of the monofilament cord is preferably 0.1 mm or more and 0.5 mm or less. If it is less than 0.1 mm, the force that can be generated by each monofilament cord is weak, and there is a possibility that sufficient rigidity cannot be exhibited, and sufficient ride comfort performance cannot be exhibited during high-speed driving. On the other hand, if the outer diameter exceeds 0.5 mm, when the monofilament cords are arranged, it may be difficult to form a belt layer by covering the monofilament cords with rubber without gaps, and at the same time, there is a concern that vibrations may be easily transmitted between the cords, causing resonance. The outer diameter of the monofilament cord is more preferably 0.15 mm or more, and even more preferably 0.2 mm or more. On the other hand, the upper limit is more preferably 0.40 mm or less, and even more preferably 0.35 mm or less.

[0047] The outer diameter of the monofilament cord can be measured in accordance with JIS G 3510 for the cord removed from the tire. In cases where the cross-sectional shape is flat or track-shaped and a minor axis / major axis occurs, the outer diameter is determined by the distance occupied by the monofilament cord in the tire width direction, calculated by Φ×cosθ, where θ is the angle between the major axis Φ (mm) of the monofilament cord and a line parallel to the tire width direction, for the monofilament cord closest to the tire equatorial plane.

[0048] 3. Angle of monofilament cord In the present disclosure, the monofilament cord is preferably arranged so as to form an angle of 10° or more and 35° or less with a straight line parallel to the tire circumferential direction.

[0049] By arranging the belt layers so that the monofilament cords are inclined at an appropriate angle, it is possible to firmly restrain almost the entire width of the tread and reduce the amount of deformation of the tread during rolling, which is believed to result in better ride comfort performance when driving at high speeds.

[0050] 4.Multi-layered belt In the present disclosure, the belt layer is multi-layered with at least two layers, and at least one pair of adjacent belt layers in the tire radial direction is preferably arranged at a distance of 0.1 mm or more and 0.8 mm or less, more preferably 0.2 mm or more, and even more preferably 0.3 mm or more, while being more preferably 0.7 mm or less, and even more preferably 0.6 mm or less.

[0051] This allows a pair of belt layers to work together to appropriately restrain the tread, reducing the amount of deformation of the tread during rolling. It also enables the reaction force from the monofilament cord toward the road surface to be transmitted in a balanced manner at all angles relative to the axial direction of the tire, which is believed to result in better handling stability during high-speed driving.

[0052] The distance between the belt layers can be expressed as an average distance in the width direction, and can be obtained by measuring the distance from the innermost layer on the surface side to the surface of the inner layer on the equatorial plane.

[0053] In this case, if at least one pair of adjacent belt layers is arranged so that the cords cross each other, a hoop effect can be obtained, firmly binding almost the entire width of the tread and reducing the amount of deformation of the tread during rolling. This is thought to result in even better handling stability and ride comfort when driving at high speeds.

[0054] 5. Tire shape The tire according to the present disclosure preferably has the following shape.

[0055] (1) Sectional width and outer diameter In the present disclosure, when the tire is mounted on a regular rim and the internal pressure is 250 kPa, the tire preferably satisfies the following formula 5, where Wt (mm) and Dt (mm) are the cross-sectional width and outer diameter of the tire. 1650≦(Dt 2 ×π / 4) / Wt (Formula 5)

[0056] The area of ​​the tire when viewed from the side with respect to the cross-sectional width Wt is [(Dt / 2) 2 ×π)=(Dt 2 ×π / 4) is large, specifically, by making it 1650 or more, the moment of inertia of the tire can be increased and the rolling resistance in a steady state can be reduced, which is believed to provide a tire with excellent fuel efficiency. Note that 1600 or more is more preferable, 1700 or more is even more preferable, 1800 or more is even more preferable, and 1963.4 or more is particularly preferable.

[0057] However, such a tire has a cross-sectional area [(Dt / 2) 2 ×π)=(Dt 2 ×π / 4) is large, so that the centrifugal force is generally large, and the tread portion is deformed into a round shape during high-speed driving, which may lead to a deterioration in rolling resistance. Also, during high-speed driving, the outer diameter tends to grow large due to the increase in centrifugal force, which may lead to a deterioration in steering stability.

[0058] In the present disclosure, as described above, the belt layer is configured by covering the steel monofilament cord with the rubber composition, so that the tread portion is sufficiently restrained during high-speed running, and deformation of the tread portion caused by centrifugal force can be sufficiently suppressed.

[0059] In addition, when such a belt layer is adopted, deformation of the profile shape of the tread portion is reduced and the responsiveness of the belt layer to shear deformation is increased, so that it is possible to improve the steering stability during high-speed driving and to suppress deterioration of the steering stability during high-speed driving.

[0060] In the above description, when the tire is mounted on a regular rim and the internal pressure is set to 250 kPa, the specific outer diameter Dt (mm) is, for example, preferably 515 mm or more, more preferably 558 mm or more, and even more preferably 600 mm or more.

[0061] On the other hand, although the upper limit is not particularly limited, it is preferably less than 843 mm, more preferably less than 725 mm, even more preferably less than 707 mm, particularly preferably less than 685 mm, and most preferably less than 655 mm. By setting the outer diameter Dt within the above range, it is considered that a good moment of inertia during rolling can be obtained, and a reaction force can be easily generated when a steering angle is applied.

[0062] A specific cross-sectional width Wt (mm) is, for example, preferably 115 mm or more, more preferably 130 mm or more, even more preferably 150 mm or more, and even more preferably 170 mm or more.

[0063] On the other hand, the upper limit is not particularly limited, but is preferably less than 305 mm, more preferably less than 245 mm, even more preferably less than 210 mm, particularly preferably less than 205 mm, and most preferably less than 200 mm.

[0064] Specifically, the cross-sectional height Ht (mm) is, for example, preferably 37 mm or more, more preferably 87 mm or more, and even more preferably 95 mm or more, while it is preferably less than 180 mm, and more preferably less than 120 mm.

[0065] (2) Circumferential grooves in the tread In the tire according to the present disclosure, the tread portion has a plurality of circumferential grooves, and the total cross-sectional area of ​​the plurality of circumferential grooves is preferably 10% or more and 30% or less of the cross-sectional area of ​​the tread portion. This is believed to suppress the movement of the tread portion and provide better ride comfort performance during high-speed driving. It is more preferable that it is 15% or more, even more preferable that it is 18% or more, and particularly preferable that it is 21% or more. On the other hand, it is more preferable that it is 27% or less, even more preferable that it is 25% or less, and particularly preferable that it is 23% or less.

[0066] The cross-sectional area of ​​the circumferential grooves mentioned above refers to the total area defined by the straight line connecting the ends of the tread circumferential grooves and the groove walls in a tire mounted on a regular rim, with an internal pressure of 250 kPa and no load applied. In simple terms, this area can be determined by cutting the tire in a radial direction with a width of 2 to 4 cm and pressing the space between the bead portions to match the width of the rim.

[0067] The cross-sectional area of ​​the tread portion refers to the area radially outward of the belt layer in a region bounded by a straight line connecting the ends of the circumferential grooves of the tread portion and two straight lines parallel to the equatorial plane, passing through both ends of the widest one of the tread surface profile and belt layers formed by the tread surface, in a radial cross section of a tire mounted on a regular rim, with an internal pressure of 250 kPa and no load. Note that, in the case where a belt reinforcing layer using organic fibers and / or steel cords is present radially outward of the belt layer, the cross-sectional area refers to the area radially outward of the belt reinforcing layer.

[0068] In addition, the groove width L at a depth of 80% of the maximum depth of the circumferential groove with respect to the groove width L0 at the contact surface of the tread portion 80 Ratio (L 80 / L0) is preferably 0.3 or more and 0.7 or less, more preferably 0.35 or more, even more preferably 0.40 or more, and particularly preferably 0.45 or more, while it is more preferably 0.65 or less, even more preferably 0.60 or less, and particularly preferably 0.55 or less.

[0069] This suppresses the movement of the entire land portion at the bottom of the tread, resulting in better ride comfort when driving at high speeds.

[0070] In addition, the above L0 and L 80 The straight-line distance (L0) between the ends of the circumferential grooves on the tread surface of a tire mounted on a standard rim, with an internal pressure of 250 kPa and no load, and the minimum distance (L) between the groove walls at a position of 80% of the groove depth 80 ) and can be calculated simply by cutting a section of the tire 2 to 4 cm wide in the radial direction and pressing the space between the beads to match the width of the rim.

[0071] (3) Yokomizo In the present disclosure, the tread portion further has a plurality of lateral grooves extending in the tire axial direction, and the total volume of the plurality of lateral grooves is preferably 2.0% or more and 5.0% or less of the volume of the tread portion, more preferably 2.2% or more, even more preferably 2.5% or more, and particularly preferably 2.7% or more, while being more preferably 4.0% or less, even more preferably 3.5% or less, and particularly preferably 3.0% or less.

[0072] This suppresses tread movement and provides better ride comfort when driving at high speeds.

[0073] The volume of the tread portion mentioned above refers to the volume obtained by extending the area of ​​the tread portion in the tire circumferential direction. Simply put, it can be obtained by multiplying the area of ​​the tread portion by the length of the tire circumference (outer diameter Dt × π). The volume of the lateral groove refers to the total volume formed by the surface connecting the ends of the lateral grooves and the groove walls in a tire mounted on a regular rim, with an internal pressure of 250 kPa and no load, and can be calculated by determining the volume of each lateral groove.

[0074] The volume of the lateral grooves refers to the total volume formed by the surfaces connecting the ends of the lateral grooves and the groove walls when the tire is mounted on a standard rim, with an internal pressure of 250 kPa and no load applied. In simple terms, it can be found by calculating the volume of each lateral groove while pressing down the space between the beads of a section 2 to 4 cm wide cut out of the tire in the radial direction to fit the rim width.

[0075] [3] Implementation form Hereinafter, the present disclosure will be specifically described based on embodiments.

[0076] 1. Rubber composition (1) Compounding materials The rubber composition constituting the belt layer of the tire according to the present disclosure can be obtained from the rubber component and other compounding materials described below.

[0077] (a) Rubber component In the present embodiment, the rubber component is not particularly limited, and rubbers (polymers) generally used in tire manufacturing, such as diene rubbers such as isoprene rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), and nitrile rubber (NBR), and butyl rubber such as butyl rubber, can be used. Among these, isoprene rubber is preferred, and it is preferable to use NR, since the cis structure of polyisoprene is close to 100% and the tensile strength is superior to other rubber components. Note that BR and SBR may be used in combination, if necessary.

[0078] (a) Isoprene rubber The amount (total amount) of the isoprene-based rubber in 100 parts by mass of the rubber component is preferably not less than 80 parts by mass, and more preferably not less than 90 parts by mass.

[0079] Examples of isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR, with NR being preferred from the standpoint of excellent strength.

[0080] As the NR, for example, SIR20, RSS♯3, TSR20, etc., which are common in the tire industry, can be used. As the IR, there is no particular limitation, and for example, IR2200, etc., which are common in the tire industry can be used. As the modified NR, deproteinized natural rubber (DPNR), highly purified natural rubber (UPNR), etc. can be used. As the modified NR, epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. can be used. As the modified IR, epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, etc. can be used. These may be used alone or in combination of two or more kinds.

[0081] (b) Other rubber components Other rubber components may include rubbers (polymers) that are generally used in tire production, such as butadiene rubber (BR), styrene butadiene rubber (SBR), nitrile rubber (NBR), etc. The content (total content) of these rubber components in 100 parts by mass of the rubber component is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less.

[0082] (b) Compounding materials other than rubber components (a) Filler In the present embodiment, the rubber composition preferably contains a filler. Specific examples of the filler include carbon black, silica, graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica. Among these, carbon black is preferably used as a reinforcing agent.

[0083] (i) Carbon black The rubber composition preferably contains carbon black. The amount of carbon black per 100 parts by mass of the rubber component is, for example, preferably 5 parts by mass or more and 80 parts by mass or less, more preferably 40 parts by mass or more and 70 parts by mass or less, and even more preferably 50 parts by mass or more and 60 parts by mass or less.

[0084] The carbon black is not particularly limited, and examples thereof include furnace blacks (furnace carbon blacks) such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF; acetylene blacks (acetylene carbon blacks); thermal blacks (thermal carbon blacks) such as FT and MT; channel blacks (channel carbon blacks) such as EPC, MPC, and CC. These may be used alone or in combination of two or more.

[0085] From the viewpoint of appropriate reinforcement, the BET specific surface area of ​​carbon black is, for example, 30 m 2 / g over 250m 2 / g or less. The BET specific surface area is the nitrogen adsorption specific surface area (N2SA) measured by the BET method in accordance with ASTM D3037-93.

[0086] The BET specific surface area of ​​the above carbon black is 45m 2 / g or less is more preferable. BET specific surface area: 45 m 2 By using large particle size carbon black of less than 1 / g, heat generation of the rubber during high speed driving is appropriately reduced and the stiffness of the rubber, i.e., the complex modulus E * As a result, softening of the rubber and a decrease in the restraint property during high-speed driving can be suppressed, and sufficient reaction force can be generated with sufficient restraint property. In this case, the content of the rubber component is preferably 5 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the rubber component.

[0087] The average primary particle size of the carbon black is preferably 25 nm or more, more preferably 40 nm or more, from the viewpoint of obtaining appropriate flexibility. On the other hand, from the viewpoint of reinforcing the rubber composition and obtaining good repulsion, it is preferably 75 nm or less, more preferably 70 nm or less. In this case, the content per 100 parts by mass of the rubber component is preferably 5 parts by mass or more and 60 parts by mass or less.

[0088] The average primary particle diameter of the carbon black can be calculated by directly observing the carbon black extracted from the rubber composition extracted from the tire using a transmission electron microscope (TEM) or the like, calculating the equivalent cross-sectional area diameter from the area of ​​each carbon black particle obtained, and calculating the average value.

[0089] The carbon black has a dibutyl phthalate (DBP) absorption of, for example, more than 50 ml / 100 g and less than 250 ml / 100 g, as measured according to ASTM D2414-93.

[0090] Specific carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Co., Ltd., Shin-Nichika Carbon Co., Ltd., Columbia Carbon Co., Ltd., and the like. These may be used alone or in combination of two or more kinds.

[0091] (ii-1) Silica The rubber composition may contain silica as necessary. When silica is used, it is preferable to use it in combination with a silane coupling agent.

[0092] The BET specific surface area of ​​silica is set to 140 m from the viewpoint of obtaining good durability. 2 / g or more is preferable, and 160m 2On the other hand, from the viewpoint of obtaining good rolling resistance during high-speed driving, a tire having a rolling resistance of 250 m 2 / g or less is preferable, and 220m 2 / g or less. The BET specific surface area is the N2SA value measured by the BET method in accordance with ASTM D3037-93.

[0093] When silica is used as a reinforcing filler, the content of silica per 100 parts by mass of the rubber component is preferably more than 35 parts by mass, more preferably more than 40 parts by mass, from the viewpoint of obtaining good durability performance, while being preferably less than 150 parts by mass, more preferably less than 70 parts by mass, even more preferably less than 65 parts by mass, and particularly preferably less than 60 parts by mass, from the viewpoint of obtaining good rolling resistance during high-speed running.

[0094] Examples of silica include dry process silica (anhydrous silica), wet process silica (hydrated silica), etc. Among these, wet process silica is preferred because it has a large number of silanol groups.

[0095] Examples of silica include: Evonik Industries Products from companies such as Rhodia, Tosoh Silica, Solvay Japan, and Tokuyama can be used.

[0096] (ii-2) Silane coupling agents When silica is used as the reinforcing filler, the rubber composition preferably contains a silane coupling agent together with silica. The silane coupling agent is not particularly limited, and examples thereof include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl silane, and the like. Examples of the silane include sulfide-based silanes such as rubamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide, mercapto-based silanes such as 3-mercaptopropyl trimethoxysilane, 2-mercaptoethyl triethoxysilane, and NXT and NXT-Z manufactured by Momentive, vinyl-based silanes such as vinyl triethoxysilane and vinyl trimethoxysilane, amino-based silanes such as 3-aminopropyl triethoxysilane and 3-aminopropyl trimethoxysilane, glycidoxy-based silanes such as γ-glycidoxypropyl triethoxysilane and γ-glycidoxypropyl trimethoxysilane, nitro-based silanes such as 3-nitropropyl trimethoxysilane and 3-nitropropyl triethoxysilane, and chloro-based silanes such as 3-chloropropyl trimethoxysilane and 3-chloropropyl triethoxysilane. These may be used alone or in combination of two or more.

[0097] Examples of the silane coupling agent include: Evonik IndustriesProducts from companies such as Dow Corning Toray, Momentive, Shin-Etsu Silicones, Tokyo Chemical Industry, Azumax, and others can be used.

[0098] The content of the silane coupling agent is, for example, more than 3 parts by mass and less than 25 parts by mass relative to 100 parts by mass of silica.

[0099] (iii) Other fillers In addition to the carbon black, the rubber composition may further contain, as necessary, fillers commonly used in the tire industry, such as graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica. The content of these is, for example, more than 0.1 parts by mass and less than 200 parts by mass per 100 parts by mass of the rubber component. When silica is used, it is preferably used in combination with a silane coupling agent.

[0100] (b) Hardening resin component The rubber composition preferably contains a phenolic resin and / or a melamine resin as a curable resin component, which improves adhesion to the steel cord without significantly deteriorating heat buildup and elongation at break, making it easier for the rubber and steel cord to generate a large reaction force.

[0101] Specific examples of phenolic resins include PR12686 (cashew oil modified phenolic resin) manufactured by Sumitomo Bakelite Co., Ltd., and examples of melamine resins include Sumikanol 507AP (modified etherified methylol melamine resin) manufactured by Taoka Chemical Co., Ltd.

[0102] The content of the curable resin component is, for example, preferably 1 part by mass or more, more preferably 2 parts by mass or more, relative to 100 parts by mass of the rubber component, from the viewpoint of sufficiently improving the complex elastic modulus and obtaining a large reaction force during deformation, while the content is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 5 parts by mass or less, from the viewpoint of maintaining the breaking strength.

[0103] When using a melamine resin, it is preferable to also contain a methylene donor as a curing agent. Examples of methylene donors include hexamethylenetetramine (HMT), hexamethoxymethylolmelamine (HMMM), and hexamethylolmelamine pentamethylether (HMMPME), and the like can be mentioned. The methylene donor is preferably contained in an amount of, for example, 5 parts by mass or more, and about 15 parts by mass, per 100 parts by mass of the curable resin component. If the amount is too small, there is a risk that a sufficient complex modulus cannot be obtained. On the other hand, if the amount is too large, there is a risk that the viscosity of the rubber increases and the processability deteriorates.

[0104] As a specific example of the methylene donor, Sumikanol 507 manufactured by Taoka Chemical Co., Ltd. can be used.

[0105] (C) Plasticizer components The rubber composition may contain oil (including extending oil), liquid rubber, and resin as plasticizers that soften rubber. The plasticizer component is a component that can be extracted from vulcanized rubber with acetone. The total content of the plasticizer components is preferably more than 1 part by mass, more preferably 2 parts by mass or more, per 100 parts by mass of the rubber component. On the other hand, it is preferably less than 20 parts by mass, more preferably less than 10 parts by mass. The oil content includes the amount of oil contained in the rubber (oil-extended rubber).

[0106] (i) Oil Examples of oils include mineral oils (generally called process oils), vegetable oils, and mixtures thereof. Examples of mineral oils (process oils) that can be used include paraffin-based process oils, aromatic process oils, and naphthenic process oils. Examples of vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. These may be used alone or in combination of two or more.

[0107] Specific examples of process oils (mineral oils) include those manufactured by Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation Products from companies such as Orisoi, H&R, Toyokuni Oil Mills, Showa Shell Sekiyu, and Fuji Kosan can be used.

[0108] (ii) Liquid rubber The liquid rubber mentioned as a plasticizer is a polymer that is in a liquid state at room temperature (25°C) and is a rubber component that can be extracted by acetone extraction from a vulcanized tire. Examples of liquid rubber include farnesene-based polymers, liquid diene-based polymers, and hydrogenated products thereof.

[0109] Farnesene polymers are polymers obtained by polymerizing farnesene and contain structural units based on farnesene. Farnesene has isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene).

[0110] The farnesene-based polymer may be a homopolymer of farnesene (farnesene homopolymer) or a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer).

[0111] Examples of liquid diene polymers include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), and liquid styrene-isoprene copolymer (liquid SIR).

[0112] The liquid diene polymer has a weight average molecular weight (Mw) of, for example, 1.0×10 3 Super, 2.0×10 5 In this specification, the Mw of the liquid diene polymer is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0113] The amount of the liquid rubber (total amount of the liquid farnesene polymer, the liquid diene polymer, etc.) is, for example, more than 1 part by mass and less than 100 parts by mass per 100 parts by mass of the rubber component.

[0114] As the liquid rubber, for example, products of Kuraray Co., Ltd., Cray Valley Co., Ltd., etc. can be used.

[0115] (iii) Resin component The resin component also functions as a tackifier and may be solid or liquid at room temperature, and specific examples of the resin component include rosin resin, styrene resin, coumarone resin, terpene resin, C5 resin, C9 resin, C5C9 resin, acrylic resin, etc., and two or more of them may be used in combination. The content of the resin component is preferably more than 2 parts by mass and less than 45 parts by mass, more preferably less than 30 parts by mass, based on 100 parts by mass of the rubber component.

[0116] Rosin-based resins are resins whose main component is rosin acid obtained by processing rosin. These rosin-based resins (rosins) can be classified according to whether they have been modified or not, and can be classified into unmodified rosin (unmodified rosin) and modified rosin (rosin derivatives). Examples of unmodified rosins include tall rosin (also known as tall oil rosin), gum rosin, wood rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, and other chemically modified rosins. Modified rosin is a modification of unmodified rosin, and examples of such modified rosin include rosin esters, unsaturated carboxylic acid modified rosin esters, unsaturated carboxylic acid modified rosin esters, rosin amide compounds, and rosin amine salts.

[0117] The styrene resin is a polymer using a styrene monomer as a constituent monomer, and examples thereof include polymers polymerized with a styrene monomer as the main component (50% by mass or more).Specific examples thereof include homopolymers obtained by polymerizing each of the styrene monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.) alone, copolymers obtained by copolymerizing two or more kinds of styrene monomers, and copolymers of a styrene monomer and another monomer that can be copolymerized therewith.

[0118] Examples of the other monomer include acrylonitriles such as acrylonitrile and methacrylonitrile, unsaturated carboxylic acids such as acrylics and methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, dienes such as chloroprene and butadiene-isoprene, olefins such as 1-butene and 1-pentene, α,β-unsaturated carboxylic acids such as maleic anhydride or acid anhydrides thereof, and the like.

[0119] Among the coumarone resins, coumarone-indene resins are preferred. Coumarone-indene resins are resins that contain coumarone and indene as monomer components that constitute the resin skeleton (main chain). Other monomer components contained in the skeleton besides coumarone and indene include styrene, α-methylstyrene, methylindene, vinyltoluene, etc.

[0120] The amount of the coumarone-indene resin per 100 parts by mass of the rubber component is, for example, more than 1.0 part by mass and less than 50.0 parts by mass.

[0121] The hydroxyl value (OH value) of the coumarone-indene resin is, for example, more than 15 mgKOH / g and less than 150 mgKOH / g. The OH value is the amount of potassium hydroxide required to neutralize acetic acid bonded to hydroxyl groups when acetylating 1 g of the resin, expressed in milligrams, and is a value measured by potentiometric titration (JIS K 0070:1992).

[0122] The softening point of the coumarone-indene resin is, for example, more than 30° C. and less than 160° C. The softening point is the temperature at which the ball drops when the softening point specified in JIS K 6220-1:2001 is measured using a ring and ball softening point tester.

[0123] Terpene resins include polyterpene, terpene phenol, and aromatic modified terpene resins. Polyterpenes are resins obtained by polymerizing terpene compounds and their hydrogenated products. Terpene compounds are (C5H8) n The hydrocarbons and their oxygen-containing derivatives are represented by the following composition: Monoterpenes (C 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 ), and examples thereof include α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0124] Examples of polyterpenes include terpene resins such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, and β-pinene / limonene resin, which are made from the above-mentioned terpene compounds, as well as hydrogenated terpene resins obtained by hydrogenating the terpene resins. Examples of terpene phenols include resins obtained by copolymerizing the above-mentioned terpene compounds with phenolic compounds, and resins obtained by hydrogenating the above-mentioned resins, and specifically include resins obtained by condensing the above-mentioned terpene compounds, phenolic compounds, and formalin. Examples of phenolic compounds include, for example, phenol, bisphenol A, cresol, and xylenol. Examples of aromatic modified terpene resins include resins obtained by modifying terpene resins with aromatic compounds, and resins obtained by hydrogenating the above-mentioned resins. The aromatic compound is not particularly limited as long as it is a compound having an aromatic ring, and examples thereof include phenolic compounds such as phenol, alkylphenols, alkoxyphenols, and phenols containing an unsaturated hydrocarbon group; naphthol compounds such as naphthol, alkylnaphthols, alkoxynaphthols, and naphthols containing an unsaturated hydrocarbon group; styrene derivatives such as styrene, alkylstyrenes, alkoxystyrenes, and styrenes containing an unsaturated hydrocarbon group; coumarone, indene, and the like.

[0125] "C5 resin" refers to a resin obtained by polymerizing a C5 fraction. Examples of C5 fractions include petroleum fractions having 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, and isoprene. As a C5 petroleum resin, dicyclopentadiene resin (DCPD resin) is preferably used.

[0126] The term "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, and may be a resin obtained by hydrogenating or modifying the resin. Examples of C9 fractions include petroleum fractions having 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specific examples of suitable resins include coumarone-indene resins, coumarone resins, indene resins, and aromatic vinyl resins. As aromatic vinyl resins, homopolymers of α-methylstyrene or styrene or copolymers of α-methylstyrene and styrene are preferred, and copolymers of α-methylstyrene and styrene are more preferred, because they are economical, easy to process, and have excellent heat generation properties. As aromatic vinyl resins, for example, those commercially available from Kraton, Eastman Chemical, etc. can be used.

[0127] The term "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be a hydrogenated or modified resin. Examples of the C5 fraction and the C9 fraction include the petroleum fractions. As the C5C9 resin, for example, those commercially available from Tosoh Corporation, LUHUA, etc. can be used.

[0128] The acrylic resin is not particularly limited, but for example, a solventless acrylic resin can be used.

[0129] Examples of the solvent-free acrylic resin include (meth)acrylic resins (polymers) synthesized by high-temperature continuous polymerization (high-temperature continuous bulk polymerization) (methods described in U.S. Pat. No. 4,414,370, JP-A-59-6207, JP-B-5-58005, JP-A-1-313522, U.S. Pat. No. 5,010,166, and Toa Gosei Kenkyuu Nenpo TREND 2000 Vol. 3, p. 42-45, etc.) using as little secondary raw material as possible, such as polymerization initiators, chain transfer agents, and organic solvents. In the present invention, (meth)acrylic means methacryl and acrylic.

[0130] Examples of monomer components constituting the acrylic resin include (meth)acrylic acid, (meth)acrylic acid esters (alkyl esters, aryl esters, aralkyl esters, etc.), (meth)acrylamide, and (meth)acrylic acid derivatives such as (meth)acrylamide derivatives.

[0131] In addition, aromatic vinyls such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene may be used together with (meth)acrylic acid or a (meth)acrylic acid derivative as a monomer component constituting the acrylic resin.

[0132] The acrylic resin may be a resin composed only of a (meth)acrylic component, or a resin containing components other than the (meth)acrylic component as constituent elements. The acrylic resin may have a hydroxyl group, a carboxyl group, a silanol group, or the like.

[0133] Examples of the resin component that can be used include products from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nippon Paint Chemical Co., Ltd., Nippon Shokubai Co., Ltd., JX Energy Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Co., Ltd.

[0134] (D) Metal salts of organic acids The rubber composition preferably contains an organic acid cobalt salt as the organic acid metal salt. Since the organic acid cobalt salt serves to improve the adhesion between the cord and the rubber, the incorporation of this component can improve the adhesion between the cord and the rubber.

[0135] Specific examples of the cobalt organic acid that can be preferably used include cobalt salts of acetylacetonate, fumaric acid, pentanoic acid, acetic acid, benzoic acid, and derivatives thereof, and more preferably cobalt salts of boron-containing organic acids. Among these, boron neodecanoate is particularly preferably used.

[0136] The content of the organic acid cobalt is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, based on 100 parts by mass of the rubber component. On the other hand, the upper limit is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and even more preferably 2 parts by mass or less. If the content is too small, there is a risk that the adhesion between the plating layer of the steel cord and the rubber cannot be sufficiently ensured. On the other hand, if the content is too large, there is a risk that the oxidative deterioration of the rubber becomes significant, and the breaking properties deteriorate.

[0137] In addition, as a chemical other than the organic cobalt acid, a chemical in which the cobalt element is appropriately replaced with an element having an ionization tendency between that of zinc and copper may be used. Examples of such metal elements include iron, nickel, tin, antimony, and bismuth.

[0138] In the present disclosure, it is preferable to contain 0.1 parts by mass or more and 5 parts by mass or less of an aliphatic (thiosulfate) sodium salt derivative such as sodium hexamethylene-1,6-bis(thiosulfate) dihydrate together with the organic acid cobalt, based on 100 parts by mass of the rubber component.

[0139] Since the aliphatic (thiosulfate) sodium salt derivative contains a sulfur atom, it also functions as a crosslinking agent, and can balance the initial adhesion / heat-resistant adhesion / water-resistant adhesion of the rubber composition to the steel monofilament cord, thereby improving the adhesion to the steel monofilament cord.

[0140] Specific examples of aliphatic sodium (thiosulfate) salt derivatives include Duralink HTS (sodium hexamethylene-1,6-bis(thiosulfate) dihydrate) manufactured by Flexis.

[0141] (e) Anti-aging agents The rubber composition preferably contains an antioxidant. The content of the antioxidant is, for example, more than 0.5 parts by mass and less than 10 parts by mass, and more preferably 1 part by mass or more, per 100 parts by mass of the rubber component.

[0142] Examples of the antioxidant include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, and N,N'-di-2-naphthyl-p-phenylenediamine. p-phenylenediamine-based antioxidants such as quinolinone, quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline, monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol, and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. These may be used alone or in combination of two or more.

[0143] As the antioxidant, for example, products available from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis, etc. can be used.

[0144] (F) Zinc oxide The rubber composition may contain zinc oxide. The content of zinc oxide is preferably 15 parts by mass or less based on 100 parts by mass of the rubber component.

[0145] As the zinc oxide, any known zinc oxide can be used, for example, products available from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc.

[0146] (G) Crosslinking agents and vulcanization accelerators The rubber composition preferably contains a crosslinking agent such as sulfur. Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, and the like, which are commonly used in the rubber industry. These may be used alone or in combination of two or more.

[0147] The amount of sulfur is preferably 8 parts by mass or less based on 100 parts by mass of the rubber component.

[0148] As sulfur, for example, products from Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanritsu Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

[0149] Examples of crosslinking agents other than sulfur include vulcanizing agents containing sulfur atoms, such as Tackirol V200 manufactured by Taoka Chemical Co., Ltd. and KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane) manufactured by LANXESS, and organic peroxides, such as dicumyl peroxide.

[0150] The rubber composition preferably contains a vulcanization accelerator. The content of the vulcanization accelerator is, for example, more than 0.3 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component.

[0151] Examples of vulcanization accelerators include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, and N-oxyethylene-2-benzothiazole sulfenamide. 、N , N'-diisopropyl-2-benzothiazolesulfenamide and other sulfenamide-based vulcanization accelerators; and diphenylguanidine, di-orthotolylguanidine, orthotolylbiguanidine and other guanidine-based vulcanization accelerators. These may be used alone or in combination of two or more.

[0152] (H) Others In addition to the above components, the rubber composition may further contain additives commonly used in the tire industry, such as fatty acid metal salts, carboxylate metal salts, organic peroxides, reversion (reversion) inhibitors, etc., as necessary. The content of these additives is, for example, more than 0.1 parts by mass and less than 200 parts by mass per 100 parts by mass of the rubber component.

[0153] (2) Preparation of rubber composition The rubber composition is produced by a general method, for example, a production method including a base kneading step of kneading a rubber component with a filler such as carbon black, and a finish kneading step of kneading the kneaded product obtained in the base kneading step with a crosslinking agent.

[0154] The kneading can be carried out using a known (internal) kneading machine such as a Banbury mixer, a kneader, or an open roll.

[0155] The kneading temperature in the base kneading step is, for example, more than 50° C. and less than 200° C., and the kneading time is, for example, more than 30 seconds and less than 30 minutes. In the base kneading step, in addition to the above-mentioned components, compounding agents conventionally used in the rubber industry, for example, softeners such as oil, zinc oxide, antioxidants, waxes, vulcanization accelerators, etc., may be appropriately added and kneaded as necessary.

[0156] In the final kneading step, the kneaded product obtained in the base kneading step is kneaded with a crosslinking agent. The kneading temperature in the final kneading step is, for example, higher than room temperature and lower than 80° C., and the kneading time is, for example, longer than 1 minute and shorter than 15 minutes. In the final kneading step, in addition to the above components, a vulcanization accelerator, zinc oxide, etc. may be appropriately added and kneaded as necessary.

[0157] 2. Manufacturing of belt components The belt member can be produced by topping the rubber composition obtained above on both sides of reinforcing cords (steel monofilament cords) arranged in parallel at predetermined intervals (ends).

[0158] In the present disclosure, it is preferable to form a coating layer by applying an adhesive composition to the surface of the reinforcing cord prior to topping with the rubber composition. It is believed that this coating layer functions as an adhesive layer to sufficiently bond the rubber composition and the steel monofilament cord, thereby enabling the rubber composition and the steel monofilament cord to be firmly bonded to each other.

[0159] As the adhesive composition, an adhesive composition containing a polybenzoxazine compound including units represented by the following (Chemical Formula 1) to (Chemical Formula 4) is preferred because it exhibits excellent adhesion to both the rubber composition and the steel monofilament cord.

[0160] [ka]

[0161] [ka]

[0162] [ka]

[0163] [ka]

[0164] In the above (Chemical formula 1) and (Chemical formula 2), X1 is a hydrocarbon selected from aliphatic, alicyclic, and aromatic groups, or a combination thereof, and may have any of S, O, N, and P heteroatoms, or a structure in which these heteroatoms are continuously linked. X2 has an (S)n structure in which n (1 to 8) S atoms are linked, and may have a hydrocarbon selected from aliphatic, alicyclic, and aromatic groups, and any of S, O, N, and P, and / or a combination thereof. In the above (Chemical formula 3) and (Chemical formula 4), X1 is a hydrocarbon selected from aliphatic, alicyclic, and aromatic groups, or a combination thereof, and may have an (S)n structure in which n (1 to 8) S atoms are linked.

[0165] The adhesive composition described above can be prepared using a known method, for example, as described in US2020 / 0290402 (JP2019-507805A). A coating liquid of the obtained adhesive composition is applied to the surface of a steel monofilament cord, dried, and then thermally crosslinked to form an adhesive layer on the surface of the steel monofilament cord.

[0166] 3. Tire manufacturing The tire according to the present disclosure can be produced as an unvulcanized tire by molding the belt member obtained above together with other tire components on a tire building machine in a normal manner.

[0167] Specifically, an inner liner as a member for ensuring the airtightness of the tire, a carcass as a member for enduring the load, impact, and filled air pressure received by the tire, and a belt member as a member for tightly tightening the carcass and increasing the rigidity of the tread are wound around a molding drum, and both ends of the carcass are fixed to both side edges, and bead portions as members for fixing the tire to the rim are arranged. After molding into a toroidal shape, a tread is attached to the center of the outer periphery, and a sidewall is attached to the radially outside to form the side portion, thereby producing an unvulcanized tire.

[0168] In this embodiment, as described above, the belt layer may be provided in a plurality of layers in order to increase the binding force on the tread during running and to easily suppress the growth of the outer diameter. In this case, it is preferable that the average distance D (mm) between the cords of each belt layer in the tread portion of the vulcanized tire is 0.6 mm or less. It is also preferable that the angle between each cord in the tread portion and a straight line parallel to the tire circumferential direction is 10° or more and 35° or less, and that the cords of adjacent belt layers are arranged so as to cross each other.

[0169] The angle of the steel cord is the angle of the steel cord with respect to the circumferential direction of the tire when the tire is not filled with air, and can be confirmed by peeling off the tread portion from the radially outer side of the tire.

[0170] The unvulcanized tire thus produced is then heated and pressurized in a vulcanizer to obtain a tire. The vulcanization step can be carried out by applying a known vulcanization method. The vulcanization temperature is, for example, more than 120°C and less than 200°C, and the vulcanization time is, for example, more than 5 minutes and less than 15 minutes.

[0171] At this time, the tire is molded into a shape that satisfies the above-mentioned (Equation 1) when mounted on a regular rim and the internal pressure is set to 250 kPa.

[0172] Specific examples of tires to which the present disclosure is preferably applied include tires with size notations such as 145 / 60R18, 145 / 60R19, 155 / 55R18, 155 / 55R19, 155 / 70R17, 155 / 70R19, 165 / 55R20, 165 / 55R21, 165 / 60R19, 165 / 65R19, 165 / 70R18, 175 / 55R19, 175 / 55R20, 175 / 55R22, 175 / 60R18, 185 / 55R19, 185 / 60R20, 195 / 50R20, and 195 / 55R20.

[0173] In the present embodiment, the present invention can be used for various tires classified into passenger car tires, truck and bus tires, motorcycle tires, etc., and among tires that can satisfy (Formula 1), it is preferable to apply the present invention to passenger car tires, i.e., tires that are mounted on automobiles that run on four wheels and have a maximum load capacity of 1000 kg or less. By satisfying (Formula 1), the present invention can more suitably contribute to solving the problem in the present disclosure, which is to provide a pneumatic tire that has excellent ride comfort performance and handling stability during high-speed driving.

[0174] The above-mentioned maximum load capacity is the maximum load capacity determined for each tire by the standard system including the standard on which the tire is based. For example, the maximum load capacity based on the load index (LI) in the case of the JATMA standard (Japan Automobile Tire Manufacturers Association standard), the maximum value stated in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the case of the TRA (The Tire and Rim Association, Inc.), and the " LOAD CAPACITY " refers to

[0175] For tires not specified by these standards, the maximum load capacity WL (kg) is calculated using the following two formulas based on the tire section width Wt (mm), tire section height Ht (mm), and tire outer diameter Dt (mm) when the tire is mounted on a regular rim, with the internal pressure set to 250 kPa and no load: V is the volume of the space occupied by the tire (virtual volume), and (Dt / 2-Ht) is the rim diameter (mm). V(mm 3 )={(Dt / 2) 2 -(Dt / 2-Ht) 2}×π×Wt WL(kg)=0.000011×V+175

[0176] The above-mentioned maximum load capacity is not particularly limited as long as it is 1000 kg or less, but since generally, as the maximum load capacity increases, the tire weight tends to increase and the impact transmitted to the tire tends to become larger, it is preferable that the maximum load capacity be 900 kg or less, more preferably 800 kg or less, and even more preferably 700 kg or less.

[0177] Here, from the viewpoint of reducing the impact transmitted to the tire, the tire weight is preferably 20 kg or less, more preferably 15 kg or less, and even more preferably 12 kg or less, 10 kg or less, or 8 kg or less. The tire weight here refers to the weight of the entire tire, and includes sealant, sponge, three-dimensional mesh structure, electronic parts, etc., if they are provided on the tire inner cavity surface. The tire weight can be appropriately adjusted depending on the thickness and width of each member constituting the tire, the specific gravity of the rubber composition, the number of steel cords arranged in the belt reinforcing layer, the configuration of the bead wire, etc. EXAMPLES

[0178] The present invention will be described in more detail below with reference to examples. In these examples, tires having a tire size of 185 / 60R16 were produced and evaluated (outer diameter Dt: 633.2 mm, section width Wt: 189 mm, (Dt 2 ×π / 4) / Wt:1666.1).

[0179] 1. Production of rubber composition for belts First, a rubber composition for a belt was produced.

[0180] (1) Compounding materials First, the following blended materials were prepared.

[0181] (a) Rubber component NR:RSS3

[0182] (b) Compounding materials other than rubber components (a) Carbon black-1: Show Black N660 manufactured by Cabot Japan Co., Ltd. (BET specific surface area: 35m 2 / g, average particle size: 40nm) (b) Carbon black-2: Show Black N326 manufactured by Cabot Japan Co., Ltd. (BET specific surface area: 78m 2 / g, average particle size: 30nm) (c) Oil: Diana Process AH-24 (aroma oil) manufactured by Idemitsu Kosan Co., Ltd. (d) Curable resin-1: PR12686 manufactured by Sumitomo Bakelite Co., Ltd. (Cashew oil modified phenolic resin) (e) Curable resin-2: Sumikanol 507AP manufactured by Taoka Chemical Co., Ltd. (Modified etherified methylol melamine resin) (F) Organic acid cobalt-1: COST-F manufactured by DIC Corporation (Cobalt stearate, cobalt content: 9.5% by mass) (G) Organic acid cobalt-2: DICNATE NBC-II manufactured by DIC Corporation (Cobalt boron neodecanoate, cobalt content 22.5% by mass) (H) Organic acid cobalt-3: Cobalt acetylacetonate manufactured by Tokyo Chemical Industry Co., Ltd. (Cobalt acetylacetonate, cobalt content 16.5% by mass) (i) Anti-aging agent: Antage RD manufactured by Kawaguchi Chemical Industry Co., Ltd. (2,2,4-trimethyl-1,2-dihydroquinoline) (J) HTS: Duralink HTS manufactured by Flexis (Sodium hexamethylene-1,6-bis(thiosulfate) dihydrate) (k) Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. (L) Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. (W) Vulcanization accelerator: Noccela DZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N,N-dicyclohexyl-2-benzothiazolylsulfenamide)

[0183] (2) Production of Rubber Composition According to the composition shown in Table 1, materials other than sulfur and the vulcanization accelerator were kneaded for 5 minutes under the condition of 150° C. using a Banbury mixer to obtain a kneaded product. The amounts of each compound are in parts by mass.

[0184] Next, sulfur and a vulcanization accelerator were added to the obtained kneaded mixture, and the mixture was kneaded for 5 minutes under the condition of 80° C. using an open roll to obtain a rubber composition for belts.

[0185] 2. Tire manufacturing First, steel cords (surface brass-plated) having the configuration and outer diameter shown in Table 1 were arranged in the ends (pieces / 5 cm) shown in Table 1, and then the previously obtained rubber composition for belts was coated on both sides to prepare a belt member. At this time, the same amount of rubber was topped on the top and bottom so that the steel cords were arranged in the center of the thickness direction of the belt member, and the thickness was appropriately adjusted so that the average distance between the steel cords in one belt layer in the vulcanized tire was 0.45 mm. In Example 7, prior to topping, an adhesive composition containing a polybenzoxazine compound was applied to the surface of the steel cords to form a coating layer.

[0186] Thereafter, two layers were laminated together with other tire components so that the steel cords in the belt member formed an angle of 28° with a straight line parallel to the tire circumferential direction to form an unvulcanized tire, which was press-vulcanized for 10 minutes under a condition of 170°C to produce each test tire (Examples 1 to 7 and Comparative Examples 1 to 3) shown in Table 1. The tread rubber gauge G of each test tire was set to the thickness (mm) shown in Table 1.

[0187] Then, for each test tire, the above-mentioned (L 80 / L0) was 0.5, the total cross-sectional area of ​​the circumferential grooves was 22% of the cross-sectional area of ​​the tread, and the total volume of the lateral grooves was 3.5% of the volume of the tread.

[0188] 3. Calculation of parameters Thereafter, a rubber composition was cut out from between the belt layers of each test tire to prepare a rubber test piece for viscoelasticity measurement having a length of 40 mm and a width of 4 mm. The complex modulus of elasticity E was measured using an Iplexer series manufactured by GABO under the following conditions: temperature: 70°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10 Hz, deformation mode: extension. * The results are shown in Table 1.

[0189] And, "e÷G×E * " and "e × A" were calculated. The results are shown in Table 1.

[0190] 4.Performance evaluation test (1) Evaluation of driving stability Each test tire was fitted to all wheels of a vehicle (domestic FF vehicle, 2000cc displacement) and filled with air to an internal pressure of 250kPa. The vehicle was then driven zigzag at 100km / h on a test course with a dry road surface, and 20 drivers each performed a sensory evaluation of the handling stability on a 5-point scale (the higher the number, the more stable the handling). The total score of the evaluations by the 20 drivers was then calculated.

[0191] Next, the result of Comparative Example 1 was set as 100, and the steering stability was evaluated by indexing it according to the following formula. A larger value indicates better steering stability during high-speed driving. Steering stability = [(Test tire results) / (Comparative example 1 (Results) × 100

[0192] (2) Evaluation of ride comfort Each test tire was fitted to all wheels of a vehicle (domestic FF vehicle, 2000cc displacement) and filled with air to an internal pressure of 250kPa. The vehicle was then driven on a test course with a dry road surface at a speed of 100km / h, and sudden starts and stops were repeated on a straight line, during which 20 drivers each performed a sensory evaluation of the ride comfort on a 5-point scale (the higher the number, the better the ride comfort). The total score of the evaluations by the 20 drivers was then calculated.

[0193] Next, the result of Comparative Example 1 was set as 100, and the ride comfort was evaluated by indexing it according to the following formula. A larger value indicates a better ride comfort during high-speed driving. Ride comfort = [(Test tire results) / (Comparative example 1 (Results) × 100

[0194] (3) Evaluation results The results of each evaluation are shown in Table 1. In Table 1, "1x1" in the cord configuration indicates a monofilament cord, and "1x2" indicates a twisted cord in which two filaments are twisted together.

[0195] [Table 1]

[0196] From the results shown in Table 1, the steel monofilament cord is covered with the rubber composition to form a belt layer, and e÷G×E * It can be seen that if the tread width is ≧70, a pneumatic tire excellent in ride comfort and handling stability during high-speed driving can be provided.

[0197] It can be seen that when each of the formulas (2) to (5) described below is satisfied, or when the angle and outer diameter of the cord, the average distance D between the steel cords, etc. are appropriately controlled, a pneumatic tire with excellent ride comfort performance and handling stability during high-speed driving can be provided.

[0198] Although the present disclosure has been described based on the embodiments, the present disclosure is not limited to the above-mentioned embodiments. Various modifications can be made to the above-mentioned embodiments within the same and equivalent scope as the present disclosure.

[0199] The present disclosure (1) is A pneumatic tire having a tread portion and a belt layer, The belt layer is configured by covering a reinforcing cord made of a steel monofilament with a rubber composition, The number of reinforcing cords arranged per 5 cm in the tire width direction e (pieces), the thickness G (mm) of the tread portion, and the complex modulus E of the rubber composition measured under the conditions of temperature: 70° C., initial strain: 5%, dynamic strain: ±1%, frequency: 10 Hz, and deformation mode: extension * (MPa) satisfies the following (Formula 1): e÷G×E * ≧70··············(Formula 1)

[0200] This disclosure (2) is The pneumatic tire according to the present disclosure (1) is characterized in that it satisfies the following (Formula 2): e÷G×E * ≧75··············(Formula 2)

[0201] This disclosure (3) is The pneumatic tire according to the present disclosure (2) is characterized in that it satisfies the following (Formula 3). e÷G×E * ≧80··············(Formula 3)

[0202] This disclosure (4) is The rubber composition contains 80 parts by mass or more and 100 parts by mass or less of isoprene-based rubber (IR) per 100 parts by mass of the rubber component, and also contains 5 parts by mass or more and 80 parts by mass or less of carbon black and 0.1 parts by mass or more and 5 parts by mass or less of organic acid cobalt, relative to 100 parts by mass of the rubber component, and is a pneumatic tire in any combination with any of the present disclosures (1) to (3).

[0203] This disclosure (5) is The carbon black has a BET specific surface area of ​​45 m 2 / g or less, and is contained in an amount of 5 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the rubber component.

[0204] This disclosure (6) is The pneumatic tire according to the present disclosure (4) or (5) is characterized in that the organic acid cobalt is a cobalt salt of acetylacetonate, fumaric acid, pentanoic acid, acetic acid, benzoic acid, or a derivative thereof.

[0205] This disclosure (7) is The pneumatic tire is characterized in that the organic acid cobalt is a cobalt salt of a boron-containing organic acid, and is any combination with any of the present disclosures (4) to (6).

[0206] This disclosure (8) is The pneumatic tire is characterized in that the rubber composition contains a phenol resin and / or a melamine resin, and is any combination with any of the present disclosures (4) to (7).

[0207] This disclosure (9) is The rubber composition contains 0.1 parts by mass or more and 5 parts by mass or less of an aliphatic (thiosulfate) sodium salt derivative per 100 parts by mass of the rubber component, and is a pneumatic tire in any combination with any of the present disclosures (4) to (8).

[0208] The present disclosure (10) relates to The pneumatic tire is characterized in that an adhesive layer is provided between the reinforcing cord and the rubber composition, and is any combination with any of the present disclosures (1) to (9).

[0209] The present disclosure (11) relates to The adhesive layer is formed containing a polybenzoxazine compound including a unit represented by the following (Chemical Formula 1) or (Chemical Formula 2), and is a pneumatic tire according to the present disclosure (10).

[0210] [ka]

[0211] [ka]

[0212] (X1 is a hydrocarbon selected from aliphatic, alicyclic, and aromatic groups, or a combination thereof, and may have a heteroatom of any of S, O, N, and P, or a structure in which these heteroatoms are linked in succession. X2 has an (S)n structure in which n (1 to 8) S atoms are linked together, and may have a hydrocarbon selected from aliphatic, alicyclic, and aromatic groups, and any one or combination of S, O, N, and P.

[0213] The present disclosure (12) relates to The adhesive layer is formed containing a polybenzoxazine compound including a unit represented by the following (Chemical Formula 3) or (Chemical Formula 4), and is a pneumatic tire according to the present disclosure (10).

[0214] [ka]

[0215] [ka]

[0216] (X1 is a hydrocarbon selected from aliphatic, alicyclic, and aromatic groups, or a combination thereof, and has an (S)n structure in which n (1 to 8) S atoms are linked together.)

[0217] This disclosure (13) is The number of reinforcing cords arranged e (pieces / 5 cm) and the cross-sectional area A (mm 2 ) satisfies the following (Formula 4), and is a pneumatic tire in any combination with any of the present disclosures (1) to (12). e×A>4.0 (Formula 4)

[0218] This disclosure (14) is The pneumatic tire is characterized in that an angle between the reinforcing cord and a straight line parallel to the tire circumferential direction is 10° or more and 35° or less, and is any combination with any of the present disclosures (1) to (13).

[0219] The present disclosure (15) relates to The pneumatic tire is characterized in that the outer diameter r (mm) of the reinforcing cord is 0.1 mm or more and 0.5 mm or less, and is any combination with any of the present disclosures (1) to (14).

[0220] This disclosure (16) relates to At least two belt layers are provided, A pneumatic tire characterized in that at least one pair of belt layers adjacent in the tire radial direction is disposed at a distance of 0.1 mm or more and 0.8 mm or less, and in any combination with any of the present disclosures (1) to (15).

[0221] This disclosure (17) is This pneumatic tire is characterized by satisfying the following formula 5 when the tire's cross-sectional width is Wt (mm) and its outer diameter is Dt (mm) when mounted on a regular rim and the internal pressure is 250 kPa, and can be arbitrarily combined with any of the present disclosures (1) to (16). 1650≦(Dt 2 ×π / 4) / Wt (Formula 5)

[0222] This disclosure (18) is The tread portion has a plurality of circumferential grooves extending continuously in a circumferential direction of the tire, The total cross-sectional area of ​​the plurality of circumferential grooves is 10% or more and 30% or less of the cross-sectional area of ​​the tread portion, and the pneumatic tire is any combination with any of the present disclosures (1) to (17).

[0223] This disclosure (19) is The tread portion has a plurality of circumferential grooves extending continuously in a circumferential direction of the tire, A groove width L at a depth that is 80% of the maximum depth of the circumferential groove with respect to a groove width L0 of the circumferential groove in the ground contact surface of the tread portion 80 Ratio (L 80 / L0) is 0.3 or more and 0.7 or less, and is a pneumatic tire in any combination with any of the present disclosures (1) to (18).

[0224] The present disclosure (20) relates to The tread portion further has a plurality of lateral grooves extending in the tire axial direction, The pneumatic tire is characterized in that the total volume of the plurality of lateral grooves is 2.0% or more and 5.0% or less of the volume of the tread portion, and is any combination with any of the present disclosures (1) to (19).

Claims

1. A pneumatic tire having a tread portion and a belt layer, The belt layer is configured by covering a reinforcing cord made of a steel monofilament with a rubber composition, The number of reinforcing cords arranged per 5 cm in the tire width direction e (pieces), the thickness G (mm) of the tread portion, and the complex modulus E of the rubber composition measured under the conditions of temperature: 70° C., initial strain: 5%, dynamic strain: ±1%, frequency: 10 Hz, and deformation mode: extension ＊ (MPa) satisfies the following (Formula 1): e÷G×E ＊ ≧70・・・・・・・・・・・・・・(Formula 1)

2. 2. The pneumatic tire according to claim 1, wherein the following formula 2 is satisfied: e÷G×E ＊ ≧75・・・・・・・・・・・・・・(Formula 2)

3. 3. The pneumatic tire according to claim 2, wherein the following formula 3 is satisfied: e÷G×E ＊ ≧80・・・・・・・・・・・・・・(Formula 3)

4. 4. The pneumatic tire according to claim 1, wherein the rubber composition contains 80 parts by mass or more and 100 parts by mass or less of an isoprene-based rubber (IR) per 100 parts by mass of a rubber component, and contains 5 parts by mass or more and 80 parts by mass or less of carbon black and 0.1 parts by mass or more and 5 parts by mass or less of an organic acid cobalt, relative to 100 parts by mass of the rubber component.

5. The carbon black has a BET specific surface area of ​​45 m ２ 5. The pneumatic tire according to claim 4, wherein the carbon black is 5 parts by mass or more and 60 parts by mass or less per 100 parts by mass of the rubber component.

6. 6. The pneumatic tire according to claim 4, wherein the organic acid cobalt is a cobalt salt of acetylacetonate, fumaric acid, pentanoic acid, acetic acid, benzoic acid, or a derivative thereof.

7. 7. The pneumatic tire according to claim 4, wherein the organic acid cobalt is a cobalt salt of a boron-containing organic acid.

8. 8. The pneumatic tire according to claim 4, wherein the rubber composition contains a phenolic resin and / or a melamine resin.

9. 9. The pneumatic tire according to claim 4, wherein the rubber composition contains 0.1 parts by mass or more and 5 parts by mass or less of an aliphatic (thiosulfate) sodium salt derivative per 100 parts by mass of the rubber component.

10. 10. The pneumatic tire according to claim 1, wherein an adhesive layer is provided between the reinforcing cord and the rubber composition.

11. The pneumatic tire according to claim 10, characterized in that the adhesive layer is formed by containing a polybenzoxazine compound containing a unit represented by the following (Chemical Formula 1) or (Chemical Formula 2). 【Chemistry 1】 【Chemistry 2】 (X １ is a hydrocarbon selected from aliphatic, alicyclic, and aromatic hydrocarbons, or a combination thereof, and may have a heteroatom of any one of S, O, N, and P, or a structure in which these heteroatoms are linked in succession. X ２ has an (S)n structure in which n (1 to 8) S atoms are linked together, and may contain a hydrocarbon selected from aliphatic, alicyclic, and aromatic groups, and any one or combination of S, O, N, and P.

12. The pneumatic tire according to claim 10, characterized in that the adhesive layer is formed by containing a polybenzoxazine compound containing a unit represented by the following (Chemical Formula 3) or (Chemical Formula 4). 【Chemistry 3】 【Chemistry 4】 (X １ is a hydrocarbon selected from aliphatic, alicyclic, and aromatic hydrocarbons, or a combination thereof, and has an (S)n structure in which n (1 to 8) S atoms are linked together.

13. The number of the reinforcing cords arranged e (cords / 5 cm) and the cross-sectional area A (mm ２ 13. The pneumatic tire according to claim 1, wherein the following formula 4 is satisfied: e×A>4.0 (Formula 4)

14. 14. The pneumatic tire according to claim 1, wherein an angle between the reinforcing cord and a straight line parallel to the tire circumferential direction is equal to or greater than 10 degrees and equal to or less than 35 degrees.

15. 15. The pneumatic tire according to claim 1, wherein an outer diameter r (mm) of the reinforcing cord is equal to or greater than 0.1 mm and equal to or less than 0.5 mm.

16. At least two belt layers are provided, 16. The pneumatic tire according to claim 1, wherein at least one pair of belt layers adjacent to each other in a radial direction of the tire are disposed at a distance of 0.1 mm or more and 0.8 mm or less.

17. 17. The pneumatic tire according to claim 1, wherein the tire has a cross-sectional width Wt (mm) and an outer diameter Dt (mm) when mounted on a regular rim and subjected to an internal pressure of 250 kPa, and satisfies the following formula (5): 1650≦(Dt ２ ×π / 4) / Wt………………………………(Formula 5)

18. The tread portion has a plurality of circumferential grooves extending continuously in a circumferential direction of the tire, 18. The pneumatic tire according to claim 1, wherein a total cross-sectional area of ​​the plurality of circumferential grooves is 10% or more and 30% or less of a cross-sectional area of ​​the tread portion.

19. The tread portion has a plurality of circumferential grooves extending continuously in a circumferential direction of the tire, A groove width L of the circumferential groove at the ground contact surface of the tread portion ０ The groove width L at a depth of 80% of the maximum depth of the circumferential groove ８０ The ratio (L ８０ / L ０ 19. The pneumatic tire according to claim 1, wherein the ratio of the axial length of the tyre to the axial length of the tire is 0.3 or more and 0.7 or less.

20. The tread portion further has a plurality of lateral grooves extending in the tire axial direction, 20. The pneumatic tire according to claim 1, wherein a total volume of the plurality of lateral grooves is 2.0% or more and 5.0% or less of a volume of the tread portion.

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