Pneumatic tires

Abstract

To provide a pneumatic tire excellent in steering stability during high-speed travelling and durability.SOLUTION: A pneumatic tire comprises a belt layer and a tread part. The tread part is arranged outside the belt layer in a tire radial direction. Reinforcement cords in the belt layer are configured so that 50 / 5 cm or more cords made of mono-filaments are arranged in a tire width direction, on a cross section in the tire radial direction of the belt layer. A maximum load capacity WL (Kg) of the tire and weight WT (Kg) of the tire satisfy a following formula (1): (WT / WL)≤0.0140.....(formula 1).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire having 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).

[0005] In addition to the above, there has been active development of technologies for reducing the weight of tires, for example, technologies for reducing the weight of carcasses, belts, beads, etc. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2018-178034 A [Patent Document 2] JP 2018-178034 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]

[0007] However, nowadays, with the development of well-developed expressways and the fact that it is no longer uncommon to travel long distances using expressways, it has become clear that when the maximum load capacity of a tire, WL (kg), and the tire weight, WT (kg), meet the relationship shown below (Equation 1), there are concerns about ensuring handling stability and durability when driving at high speeds. (WT / WL)≦ 0.0135 ...(Formula 1)

[0008] Therefore, an object of the present invention is to provide a pneumatic tire that has excellent driving stability and durability during high-speed driving even if the tire is made lighter than a certain amount. [Means for solving the problem]

[0009] The present inventors have conducted extensive research into solving the above problems, and have found that the above problems can be solved by the invention described below, thereby completing the present invention.

[0010] The invention described in claim 1 is A pneumatic tire having a belt layer and a tread portion, The tread portion is disposed on the outer side of the belt layer in the tire radial direction, The reinforcing cords in the belt layer are configured such that cords made of monofilaments are arranged in a tire width direction at 50 cords / 5 cm or more in a tire radial cross section of the belt layer, The pneumatic tire is characterized in that the maximum load capacity WL (kg) and the tire weight WT (kg) of the tire satisfy the following (Equation 1). (WT / WL)≦ 0.0135 ...(Formula 1) The "maximum load capacity WL of the tire" is a value 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, the internal pressure is set to 250 kPa, and there is no load. V(mm 3 )={(Dt / 2) 2 -(Dt / 2-Ht) 2 }×π×Wt WL(kg)=0.000011×V+100

[0011] The invention described in claim 2 is 2. The pneumatic tire according to claim 1, wherein the cord made of the monofilament has an outer diameter of 0.1 to 0.5 mm.

[0012] The invention described in claim 3 is The tread rubber composition forming the ground contact surface in the outermost layer of the tread portion was measured under the conditions of temperature: 30°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10Hz, and deformation mode: extension. * (MPa) and The distance T (mm) from the outermost surface of the tread portion to the outermost surface of the belt layer, The pneumatic tire according to claim 1 or 2, characterized in that the following (Formula 2) is satisfied: (E * ×T)≧30 (Formula 2)

[0013] The invention described in claim 4 is The tread portion has a plurality of circumferential grooves extending continuously in a circumferential direction of the tire, 4. The pneumatic tire according to claim 1, wherein a total cross-sectional area of ​​the plurality of circumferential grooves is 10 to 30% of a cross-sectional area of ​​the tread portion.

[0014] The invention described in claim 5 is The tread portion has a plurality of lateral grooves extending in an axial direction of the tire, 5. The pneumatic tire according to claim 1, wherein a total volume of the plurality of lateral grooves is 2.0 to 5.0% of a volume of the tread portion.

[0015] The invention described in claim 6 is At least two belt layers are provided, In at least one pair of belt layers adjacent in the tire radial direction, 6. The pneumatic tire according to claim 1, wherein an average distance D (mm) between the belt layers in the tread portion is 0.6 mm or less.

[0016] The invention described in claim 7 is At least two belt layers are provided, In at least one pair of belt layers adjacent in the tire radial direction, 7. The pneumatic tire according to claim 1, wherein an angle formed between the belt layers in the tread portion in the tire circumferential direction is 65° or less.

[0017] The invention described in claim 8 is The tire has a circumferential groove in the tread portion that extends continuously in the 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 8. The pneumatic tire according to claim 1, wherein the ratio of the surface roughness to the surface roughness of the tire is 0.3 to 0.7.

[0018] The invention described in claim 9 is Ta 9. The pneumatic tire according to claim 1, wherein a tire cross-sectional width Wt (mm) is less than 200 mm. Effect of the Invention

[0019] According to the present invention, it is possible to provide a pneumatic tire that is excellent in handling stability and durability during high-speed driving, even if the tire is made lighter than a certain amount. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] [1] Characteristics of the tire according to the present invention First, the features of the pneumatic tire according to the present invention will be described.

[0021] 1. Overview The tire according to the present invention is a tire including a belt layer and a tread portion, and the maximum load capacity WL (kg) and the tire weight WT (kg) of the tire satisfy the relationship represented by the following formula 1. (WT / WL)≦ 0.0135 ...(Formula 1)

[0022] The tread portion is disposed on the radially outer side of the belt layer, and the reinforcing cords in the belt layer are configured by arranging 50 cords / 5 cm or more in the tire width direction in the radial cross section of the belt layer, the cords being made of monofilament (hereinafter also referred to as "monofilament cords").

[0023] By configuring as described above, even if the tire is made lighter than a certain amount, specifically, even if the tire's maximum load capacity WL (kg) and tire weight WT (kg) satisfy the relationship represented by the above (Equation 1), a pneumatic tire with excellent handling stability and durability during high-speed driving can be provided.

[0024] In the above description, the "maximum load capacity WL" is a value 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, the internal pressure is set to 250 kPa, and there is no load. be . Note that V is the volume of the space occupied by the tire (virtual volume), and (Dt / 2-Ht) is the rim diameter. V(mm 3 )={(Dt / 2) 2 -(Dt / 2-Ht) 2}×π×Wt WL(kg)=0.000011×V+100

[0025] Here, "genuine rim" refers to a rim that is determined 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 described in the "JATMA YEAR BOOK" for the above-mentioned JATMA, the "Measuring Rim" described in the "STANDARDS MANUAL" for the ETRTO (The European Tire and Rim Technical Organisation), and the "Design Rim" described in the "YEAR BOOK" for the 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, with the smallest rim diameter and the next narrowest rim width.

[0026] The tire cross-sectional width Wt can be calculated as the width obtained by excluding the patterns, letters, etc. on the tire side from the linear distance between the sidewalls (total tire width), including all patterns, letters, etc. on the tire side. The tire cross-sectional height Ht can be calculated as half the difference between the tire outer diameter and the nominal rim diameter.

[0027] 2. Mechanism of effect manifestation in the tire according to the present invention The mechanism by which the effect of the tire according to the present invention is manifested, i.e., the mechanism by which both steering stability during high-speed driving and durability performance are sufficiently achieved even when the tire is made lighter than a certain level, is presumed to be as follows.

[0028] One method to improve the fuel efficiency of tires is to reduce the amount (thickness) of tire components that make up the tire, thereby reducing the tire weight. However, reducing the amount of tire components reduces the tire's rigidity and moment of inertia, which may lead to a decrease in steering stability.

[0029] In particular, when traveling at high speeds, centrifugal force is likely to cause the tread portion to round, resulting in a significant decrease in steering stability. At the same time, the amount of deformation of the tire during rolling increases, and it is thought that durability is also significantly reduced.

[0030] Specifically, it was found that when the maximum load capacity of a tire, WL (kg), and the tire weight, WT (kg), have the relationship shown in Equation 1 below, there are concerns about ensuring steering stability and durability during high-speed driving. (WT / WL)≦0.0140 (Formula 1)

[0031] Therefore, in the present invention, the belt layer reinforcing the tread is configured using a cord (monofilament cord) made of a monofilament (single wire) rather than a cord (twisted wire cord) made of twisted wire. By using a monofilament cord as the reinforcing cord, unlike a twisted cord, it is difficult to elongate, so that the elongation of the belt layer can be suppressed. Furthermore, by arranging the monofilament cords at 50 or more per 5 cm, that is, in a dense state with an interval of 1 mm or less per cord, the belt layer can exert a sufficient restraining effect on the tread portion, so that even when a lightweight tire is driven at high speed, the tread portion is unlikely to become rounded, and it is considered that the steering stability and durability during high-speed driving can be ensured.

[0032] And by using the above configuration, (WT / WL)≦ 0.0135 It was found that even with (Formula 1), sufficient steering stability and durability during high-speed driving can be obtained. ,difference It was found that even greater effects could be obtained by further reducing the weight and making (WT / WL) 0.0133 or less.

[0033] The number of arranged monofilaments refers to the average number of arranged cords per 5 cm arranged in the width direction of the tire when the tire is assembled to a regular rim, with an internal pressure of 250 kPa and no load. Simply put, it can be determined by measuring the number of arranged cords in an area of ​​5 to 10 cm wide centered on the tire equatorial plane on a 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.

[0034] The 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 is weak, and there is a risk that sufficient binding force cannot be exerted. At the same time, it is thought that it will be easily broken by impact during driving, and there is a concern that the effect of improving high-speed steering stability and durability performance will be reduced.

[0035] On the other hand, if the cord outer diameter exceeds 0.5 mm, it may be difficult to form a belt layer by covering the monofilament cords with rubber without gaps when the monofilament cords are arranged. At the same time, the distance between the monofilament cords becomes narrow, making it difficult for the monofilament cord layer to deform in the width direction when turning, and sufficient stress cannot be generated, which may reduce the effect of improving steering stability.

[0036] For the above reasons, the outer diameter of the 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. The outer diameter of the monofilament cord refers to the outer diameter of the monofilament cord in the tire in the tire width direction, and is equal to the normal outer diameter when the cord cross section is a perfect circle. When the cord has an aspect ratio, the outer diameter refers to the distance in the tire width direction calculated by Φ×cosθ, where Φ (mm) is the major axis of the cord and θ is the angle between the major axis Φ and a line parallel to the tire width direction.

[0037] [2] More preferred embodiments of the tire according to the present invention The tire according to the present invention can achieve even greater effects by adopting the following features.

[0038] 1. Complex modulus of tread rubber and distance from tread to belt layer In the tire according to the present invention, the tread rubber composition forming the contact surface in the outermost layer of the tread portion is measured under the conditions of temperature: 30°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10Hz, and deformation mode: extension. * (MPa) and the distance T (mm) from the outermost surface of the tread portion to the outermost surface of the belt layer are * ×T)≧30 (Equation 2) is preferably satisfied.

[0039] 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.

[0040] On the other hand, the distance from the outermost surface of the tread portion to the outermost surface of the belt layer can be considered as a parameter indicating the effect of tightening the belt layer due to the rigidity of the tread portion, and it is considered that the larger the value, the more the restraint by the belt layer can be secured. At the same time, it is considered that the larger the value, the more the distance from the tread surface to the belt layer can be maintained, and therefore the smaller the deformation of the belt layer in the tire radial direction can be.

[0041] Based on this idea, the complex modulus E * Experiments were carried out to determine the preferable relationship between the tire pressure (MPa) and the distance T (mm) from the outermost surface of the tread portion to the outermost surface of the belt layer. *× T) ≥ 30, the belt layer can provide sufficient restraint and at the same time the amount of deformation of the belt layer in the tire radial direction can be reduced, thereby improving the handling stability and durability during high-speed driving.

[0042] In the above description, the complex elastic modulus E * can be measured using a viscoelasticity measuring device such as "Iplexer (registered trademark)" manufactured by GABO. * ×T) is more preferably 35 or more, and even more preferably 40 or more.

[0043] In the above description, the distance T (mm) from the outermost surface of the tread portion to the outermost surface of the belt layer is the straight-line distance from the tread surface on the tire equatorial plane to the surface of the monofilament cord of the outermost layer of the belt layer in a radial cross section of the tire mounted on a regular rim, with an internal pressure of 250 kPa and no load.

[0044] In addition, when a groove is formed on the tread equatorial plane, the distance T is the point where a line obtained by connecting the tire contact surface ends of the groove intersects with the tire equatorial plane to the outermost belt layer. In addition, when no monofilament cord of the outermost belt layer is present on the tire equatorial plane, the distance T is calculated by taking the intersection point of a line connecting two points on the outermost side in the tire radial direction of a pair of monofilament cords closest to the equatorial plane and the equatorial plane as the position of the outermost belt layer.

[0045] The above distance T (mm) can be simply measured 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.

[0046] The complex elastic modulus E of the rubber composition * The upper limit is not particularly limited, but is preferably 15.0 MPa. It is preferable that the pressure is 1.0 MPa or less, more preferable that the pressure is 12.0 MPa or less, and further preferable that the pressure is 9.0 MPa or less.

[0047] If it exceeds 15.0 MPa, it is considered that the tread portion is difficult to deform, and the effect of improving steering stability during high-speed driving is difficult to obtain. On the other hand, the lower limit is not particularly limited, but it is preferably 3.0 MPa or more, more preferably 3.7 MPa or more, and even more preferably 5.0 MPa or more. If it is less than 3.0 MPa, the rigidity of the tread portion is low and the deformation amount becomes too large, so it is considered that the effect of improving durability is difficult to obtain.

[0048] Further, the distance T (mm) from the outermost surface of the tread portion to the outermost surface of the belt layer is preferably 12.0 mm or less, more preferably 10.0 mm or less, and further preferably 7.5 mm or less.

[0049] If it exceeds 12.0 mm, the distance from the tread surface to the belt layer becomes too long, making it difficult to transmit the shear deformation generated on the tread surface to the belt layer, and it is difficult to obtain sufficient reaction force, which is considered to make it difficult to obtain the effect of improving steering stability during high-speed driving. The lower limit is preferably 6.0 mm or more, and more preferably 7.0 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, making it difficult to obtain the effect of improving durability performance.

[0050] 2. Tread grooves In the tire according to the present invention, the tread portion has a plurality of circumferential grooves, and the total cross-sectional area of ​​the plurality of circumferential grooves is preferably 10% to 30% of the cross-sectional area of ​​the tread portion. This makes it possible to suppress the movement of the tread portion and sufficiently improve the steering stability and durability during high-speed driving. It is more preferable that the total cross-sectional area is 15% to 27%, even more preferable that the total cross-sectional area is 18% to 25%, and particularly preferable that the total cross-sectional area is 21% to 23%.

[0051] The above-mentioned cross-sectional area of ​​the tread portion refers to the area of ​​the tire radially outboard of the belt layer in a region bounded by a straight line connecting the ends of the circumferential grooves of the tread portion and the tread surface profile formed by the tread surface and two straight lines passing through both ends of the widest one of the belt layers and parallel to the equatorial plane in a radial cross section of the tire mounted on a regular rim, with an internal pressure of 250 kPa and no load.

[0052] In addition, when a belt reinforcing layer using organic fibers and / or steel cords is provided radially outward of the belt layer, the area is the area radially outward of the belt reinforcing layer. Meanwhile, the cross-sectional area of ​​the circumferential groove refers to the total area formed by the straight line connecting the ends of the tread circumferential groove and the groove wall in the tire cross section when the tire is mounted on a regular rim, the internal pressure is 250 kPa, and the tire is in an unloaded state. These areas can be simply obtained by pressing the bead portions of a section cut out of the tire in the radial direction with a thickness of 2 to 4 cm to match the rim width.

[0053] In addition, it is preferable that the tread portion has a plurality of lateral grooves extending in the tire axial direction, and 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. This makes it possible to suppress the movement of the tread portion and sufficiently improve the steering stability and durability during high-speed driving. It is more preferable that the total volume is 2.2% or more and 4.0% or less, even more preferable that the total volume is 2.5% or more and 3.5% or less, and particularly preferable that the total volume is 2.7% or more and 3.0% or less.

[0054] 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. In a simplified manner, it can be obtained by multiplying the area of ​​the tread portion by the tire outer periphery length (Dt x 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.

[0055] Furthermore, the groove width L at a depth of 80% of the maximum depth of the circumferential groove with respect to the groove width L0 of the circumferential groove on the contact surface of the tread portion 80 Ratio (L 80 / L0) is preferably 0.3 or more and 0.7 or less. This makes it possible to suppress the movement of the entire land portion at the bottom surface of the land portion of the tread portion, thereby sufficiently improving the steering stability and durability during high-speed driving. It is more preferably 0.35 or more and 0.65 or less, even more preferably 0.40 or more and 0.60 or less, and particularly preferably 0.45 or more and 0.55 or less.

[0056] 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.

[0057] 3.Multi-layered belt In the present invention, the belt layer is multi-layered by providing at least two layers, and it is preferable that in at least one pair of belt layers adjacent in the radial direction of the tire, the average distance D (mm) between the belt layers in the tread portion is 0.6 mm or less.

[0058] As a result, a pair of belt layers work together to appropriately restrain the tread portion and reduce the amount of deformation of the tread portion during rolling, thereby enabling further improvement in handling stability and durability during high-speed driving.

[0059] The average distance D between the belt layers referred to here is the average distance between the monofilaments (cords) of the belt layers, and is the distance between the inner surface of the monofilament of the belt layer on the surface side and the outer surface of the monofilament of the inner belt layer on the equator plane of two overlapping belt layers.

[0060] In the case of a multi-layered belt layer, in at least one pair of belt layers adjacent in the radial direction of the tire, the angle formed by the belt layers in the tread portion in the tire circumferential direction is preferably 65° or less, more preferably 60° or less, and even more preferably 58° or less.

[0061] By arranging the belt layers inclined to each other at an appropriate angle, a hoop effect can be obtained, which firmly restrains almost the entire width of the tread and suppresses the amount of deformation of the tread during rolling, thereby maintaining low rolling resistance and handling stability.

[0062] The angle is the angle of the monofilament 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.

[0063] By arranging the belt layers inclined to each other at an appropriate angle, it is possible to firmly restrain almost the entire width of the tread portion and suppress the amount of deformation of the tread portion during rolling, thereby further improving the handling stability and durability during high-speed driving.

[0064] 4. Tire shape In the tire according to the present invention, when the tire is mounted on a regular rim and the internal pressure is set to 250 kPa, the specific tire outer diameter Dt (mm) is, for example, preferably 515 mm or more, more preferably 558 mm or more, even more preferably 585 mm or more, particularly preferably 658 mm or more, and most preferably 673 mm or more. On the other hand, it is preferably less than 843 mm, more preferably less than 725 mm, and even more preferably less than 707 mm.

[0065] A specific tire 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, even more preferably 170 mm or more, particularly preferably 185 mm or more, and most preferably 193 mm or more. On the other hand, it 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.

[0066] A specific tire section 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, more preferably less than 112 mm, and even more preferably less than 101 mm.

[0067] A specific value of the above-mentioned V (virtual volume) is, for example, 13,000,000 mm 3 It is preferable that the length is 29,000,000 mm or more. 3 More preferably, it is 36,000,000 mm or more. 3 More preferably, the thickness is 66,000,000 mm or more. 3 Preferably less than 44,000,000 mm 3 Preferably less than 38,800,000 mm 3 It is even more preferable that it is less than 1000 μm.

[0068] In the present invention, in consideration of stability during running, (Dt-2×Ht) is preferably 450 (mm) or more, more preferably 470 (mm) or more, and even more preferably 480 (mm) or more. On the other hand, in consideration of deformation of the tread portion, it is preferably less than 560 (mm), more preferably less than 530 (mm), and even more preferably less than 510 (mm).

[0069] [3] Implementation form Hereinafter, the present invention will be described in detail based on the embodiments.

[0070] 1. Rubber composition constituting the outermost layer of the tread (1) Compounding materials The rubber composition forming the outermost layer of the tread portion of the tire according to the present invention (rubber composition for tread) can be obtained from the rubber components and other compounding materials described below.

[0071] (a) Rubber component In the present embodiment, the rubber component is not particularly limited, and rubbers (polymers) generally used in tire production can be used, such as diene rubbers such as isoprene-based rubber, butadiene rubber (BR), styrene butadiene rubber (SBR), and nitrile rubber (NBR), and butyl-based rubbers such as butyl rubber. These may be used alone or in combination, but it is preferable to include any one of isoprene-based rubber, BR, and SBR, and it may include isoprene-based rubber and BR, BR and SBR, isoprene-based rubber and SBR, or it may include isoprene-based rubber, BR, and SBR.

[0072] (a) SBR The content of SBR in 100 parts by mass of the rubber component is, for example, preferably more than 50 parts by mass, more preferably more than 75 parts by mass, more preferably more than 80 parts by mass, and even more preferably more than 85 parts by mass from the viewpoint of handling stability during high-speed driving, while it is preferably less than 100 parts by mass, more preferably less than 95 parts by mass from the viewpoint of heat build-up during high-speed driving.

[0073] The weight average molecular weight of SBR is, for example, more than 100,000 and less than 2,000,000. The styrene content of SBR is, for example, preferably more than 5% by mass, more preferably more than 10% by mass, and even more preferably more than 20% by mass, from the viewpoint of handling stability during high-speed driving. On the other hand, from the viewpoint of heat generation and durability during high-speed driving, it is preferably less than 50% by mass, more preferably less than 40% by mass, and even more preferably less than 35% by mass. The vinyl bond amount (1,2-bonded butadiene unit amount) of SBR is, for example, more than 5% by mass and less than 70% by mass. The structure identification of SBR (measurement of styrene content and vinyl bond amount) can be performed, for example, using a JNM-ECA series device manufactured by JEOL Ltd.

[0074] There are no particular limitations on the SBR, and for example, emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc. may be used. The SBR may be either unmodified SBR or modified SBR.

[0075] The modified SBR may be any SBR having a functional group that interacts with a filler such as silica, and examples thereof include terminal-modified SBR in which at least one end of SBR has been modified with a compound (modifying agent) having the above-mentioned functional group (terminal-modified SBR having the above-mentioned functional group at the end), main-chain-modified SBR in which the main chain has the above-mentioned functional group, main-chain-terminal-modified SBR in which the main chain and at least one end are modified with the above-mentioned modifier, and terminal-modified SBR modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and having a hydroxyl group or epoxy group introduced therein.

[0076] Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imide group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, an epoxy group, etc. These functional groups may have a substituent.

[0077] Furthermore, as the modified SBR, for example, SBR modified with a compound (modifying agent) represented by the following formula can be used.

[0078] [ka]

[0079] In the formula, R 1 , R 2 and R 3 R may be the same or different and represents an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group (-COOH), a mercapto group (-SH), or a derivative thereof. 4 and R 5 R may be the same or different and represents a hydrogen atom or an alkyl group. 4 and R 5 may bond to form a ring structure together with the nitrogen atom, and n represents an integer.

[0080] As the modified SBR modified with a compound (modifier) ​​represented by the above formula, SBR in which the polymerization terminals (active terminals) of solution-polymerized styrene-butadiene rubber (S-SBR) have been modified with a compound represented by the above formula (such as the modified SBR described in JP 2010-111753 A).

[0081] R 1 , R 2 and R 3R is preferably an alkoxy group (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms). 4 and R 5 is preferably an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms). n is preferably 1 to 5, more preferably 2 to 4, and further preferably 3. In addition, R 4 and R 5 When the nitrogen atom and the nitrogen atom are bonded to each other to form a ring structure, the ring is preferably a 4- to 8-membered ring. The alkoxy group also includes a cycloalkoxy group (such as a cyclohexyloxy group) and an aryloxy group (such as a phenoxy group and a benzyloxy group).

[0082] Specific examples of the modifying agent include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane, etc. These may be used alone or in combination of two or more.

[0083] In addition, modified SBR modified with the following compounds (modifiers) can also be used as the modified SBR. Examples of the modifiers include polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; polyglycidyl ethers of aromatic compounds having two or more phenol groups such as diglycidylated bisphenol A; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxidized liquid polybutadiene; epoxy group-containing tertiary amines such as 4,4'-diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, Diglycidyl amino compounds such as diglycidyl orthotoluidine, tetraglycidyl meta-xylylenediamine, tetraglycidyl aminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidyl aminomethylcyclohexane, and tetraglycidyl-1,3-bisaminomethylcyclohexane; amino group-containing acid chlorides such as bis-(1-methylpropyl)carbamic acid chloride, 4-morpholinecarbonyl chloride, 1-pyrrolidinecarbonyl chloride, N,N-dimethylcarbamic acid chloride, and N,N-diethylcarbamic acid chloride; epoxy group-containing silane compounds such as 1,3-bis-(glycidyloxypropyl)-tetramethyldisiloxane and (3-glycidyloxypropyl)-pentamethyldisiloxane;(Trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(triethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(trippropoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(tributoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldipropoxy sulfide group-containing silane compounds such as (trimethylsilyl)[3-(methyldibutoxysilyl)propyl]sulfide and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl]sulfide; N-substituted aziridine compounds such as ethyleneimine and propyleneimine; methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, Alkoxysilanes such as thyltriethoxysilane; (thio)benzophenone compounds having amino groups and / or substituted amino groups, such as 4-N,N-dimethylaminobenzophenone, 4-N,N-di-t-butylaminobenzophenone, 4-N,N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(diphenylamino)benzophenone, and N,N,N',N'-bis-(tetraethylamino)benzophenone; Benzaldehyde compounds having an amino group and / or a substituted amino group, such as dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, 4-N,N-divinylaminobenzaldehyde, etc.; N-substituted pyrrolidones, such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, Nt-butyl-2-pyrrolidone, N-methyl-5-methyl-2-pyrrolidone, etc.; N-substituted piperidones, such as N-methyl-2-piperidone, N-vinyl-2-piperidone, N-phenyl-2-piperidone, etc.;N-substituted lactams such as N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurylolactam, N-vinyl-ω-laurylolactam, N-methyl-β-propiolactam, and N-phenyl-β-propiolactam, as well as N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), and tris-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-trione , N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3-diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N,N-dimethylaminoacetophene, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, 1,7-bis(methylethylamino)-4-heptanone, etc. Modification with the above compounds (modifiers) can be carried out by known methods.

[0084] As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Zeon Corporation, Versalis Inc., etc. may be used. The SBR may be used alone or in combination of two or more kinds.

[0085] (b) BR The rubber composition may further contain BR as necessary. In this case, the content of BR in 100 parts by mass of the rubber component is, for example, preferably more than 2 parts by mass, more preferably more than 4 parts by mass, while it is preferably less than 20 parts by mass, more preferably less than 10 parts by mass, and even more preferably less than 6 parts by mass.

[0086] The weight average molecular weight of the BR is, for example, more than 100,000 and less than 2,000,000. The vinyl bond amount of the BR is, for example, more than 1 mass% and less than 30 mass%. The cis amount of the BR is, for example, more than 1 mass% and less than 98 mass%. The trans amount of the BR is, for example, more than 1 mass% and less than 60 mass%.

[0087] The BR is not particularly limited, and BR with a high cis content (cis content of 90% or more), BR with a low cis content, BR containing syndiotactic polybutadiene crystals, etc. can be used. The BR may be either unmodified BR or modified BR, and the modified BR may be modified BR into which the above-mentioned functional groups have been introduced. These may be used alone or in combination of two or more. The cis content can be measured by infrared absorption spectroscopy.

[0088] As the modified BR, for example, tin-modified BR can be used. The tin-modified BR is preferably obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and the terminals of the tin-modified BR molecule are preferably bonded with a tin-carbon bond.

[0089] Examples of the lithium initiator include lithium-based compounds such as alkyl lithium, aryl lithium, vinyl lithium, organotin lithium, and organonitrogen lithium compounds, as well as lithium metal, etc. By using the lithium initiator as the initiator of the tin-modified BR, it is possible to prepare a tin-modified BR having a high vinyl and low cis content.

[0090] Examples of tin compounds include tin tetrachloride, butyltin trichloride, dibutyltin dichloride, dioctyltin dichloride, tributyltin chloride, triphenyltin chloride, diphenyldibutyltin, triphenyltin ethoxide, diphenyldimethyltin, ditolyltin chloride, diphenyltin dioctanoate, divinyldiethyltin, tetrabenzyltin, dibutyltin distearate, tetraallyltin, and p-tributyltin styrene.

[0091] The content of tin atoms in the tin-modified BR is preferably 50 ppm or more, more preferably 60 ppm or more, while it is preferably 3000 ppm or less, more preferably 2500 ppm or less, and even more preferably 250 ppm or less.

[0092] The molecular weight distribution (Mw / Mn) of the tin-modified BR is preferably 2 or less, and more preferably 1.5 or less.

[0093] The vinyl bond content in the tin-modified BR is preferably 5% by mass or more, more preferably 7% by mass or more, while the vinyl bond content in the tin-modified BR is preferably 50% by mass or less, more preferably 20% by mass or less.

[0094] The above-mentioned S-modified BR and tin-modified BR may be used alone or in combination of two or more kinds.

[0095] As the BR, for example, products from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Zeon Corporation, etc. can be used.

[0096] (c) Isoprene rubber The rubber composition may further contain an isoprene-based rubber as necessary. In this case, the content of the isoprene-based rubber in 100 parts by mass of the rubber component is, for example, preferably more than 2 parts by mass, more preferably more than 4 parts by mass, while it is preferably less than 40 parts by mass, more preferably less than 20 parts by mass, and even more preferably less than 8 parts by mass.

[0097] 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.

[0098] 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.

[0099] (D) Other rubber components Furthermore, as other rubber components, rubber (polymer) that is generally used in the manufacture of tires, such as nitrile rubber (NBR), may be included as necessary.

[0100] (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, silica is preferably used as a reinforcing agent, and in this case, it is preferable to use silica in combination with a silane coupling agent. It is also preferable to use carbon black as a reinforcing agent as necessary.

[0101] (i) Silica The rubber composition preferably contains silica. From the viewpoint of obtaining good durability, the BET specific surface area of ​​the silica is 140 m 2 / g or more is preferable, and 160m 2 On the other hand, from the viewpoint of obtaining a good low rolling resistance, it is more preferable that the rolling resistance is more than 250 m 2 / g or less is preferable, and 220m 2 It is more preferable that the BET specific surface area is less than N2SA / g. The BET specific surface area is the value of N2SA measured by the BET method in accordance with ASTM D3037-93.

[0102] The amount of silica per 100 parts by mass of the rubber component is preferably 30 parts by mass or more, more preferably 40 parts by mass or more, and even more preferably 45 parts by mass or more, while it is preferably 200 parts by mass or less, preferably 150 parts by mass or less, preferably 100 parts by mass or less, more preferably 80 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 55 parts by mass or less.

[0103] 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.

[0104] Commercially available products that can be used include those manufactured by Degussa, Rhodia, Tosoh Silica, Solvay Japan, and Tokuyama.

[0105] (ii) Silane coupling agent As described above, when using silica, it is preferable to use a silane coupling agent in combination. 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.

[0106] As the silane coupling agent, for example, products available from Degussa, Momentive, Shin-Etsu Silicones, Tokyo Chemical Industry, Azumax, Dow Corning Toray, etc. can be used.

[0107] The content of the silane coupling agent is, for example, preferably more than 3 parts by mass, more preferably more than 5 parts by mass, more preferably more than 7 parts by mass, and even more preferably more than 9 parts by mass, relative to 100 parts by mass of silica. On the other hand, it is preferably less than 15 parts by mass, more preferably less than 13 parts by mass, and even more preferably less than 11 parts by mass.

[0108] (iii) Carbon black The rubber composition preferably contains carbon black as necessary. The amount of carbon black is, for example, preferably 2 parts by mass or more, more preferably 3 parts by mass or more, based on 100 parts by mass of the rubber component. On the other hand, the amount is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 5 parts by mass or less.

[0109] 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.

[0110] The nitrogen adsorption specific surface area (N2SA) of carbon black is, for example, 30m 2 / g, 250m 2 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. The nitrogen adsorption specific surface area of ​​the carbon black is measured according to ASTM D4820-93, and the DBP absorption is measured according to ASTM D2414-93.

[0111] 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.

[0112] (iv) Other fillers In addition to the above-mentioned silica and carbon black, the rubber composition may further contain fillers commonly used in the tire industry, such as graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, etc. The content of these fillers is, for example, more than 0.1 part by mass and less than 200 parts by mass per 100 parts by mass of the rubber component.

[0113] (b) Hardening resin component The rubber composition may contain a curable resin component such as a modified resorcinol resin or a modified phenolic resin, as necessary. This is believed to increase the rigidity of the rubber composition and provide good steering stability during high-speed driving.

[0114] Specific examples of modified resorcinol resins include Sumikanol 620 (modified resorcinol resin) manufactured by Taoka Chemical Co., Ltd., and examples of modified phenolic resins include PR12686 (cashew oil modified phenolic resin) manufactured by Sumitomo Bakelite Co., Ltd.

[0115] 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, based on 100 parts by mass of the rubber component, from the viewpoint of sufficiently improving the complex modulus of elasticity, while it is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, based on the viewpoint of maintaining the breaking strength.

[0116] When using the modified resorcinol resin, it is preferable to contain a methylene donor as a curing agent. Examples of methylene donors include hexamethylenetetramine (HMT), hexamethoxymethylolmelamine (HMMM), and hexamethylolmelamine pentamethylether (HMMPME), and the like are 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.

[0117] As a specific example of the methylene donor, Sumikanol 507 manufactured by Taoka Chemical Co., Ltd. can be used.

[0118] (C) Plasticizer components The rubber composition may contain oil (including extender 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 5 parts by mass, and more preferably more than 10 parts by mass, per 100 parts by mass of the rubber component. On the other hand, it is preferably less than 70 parts by mass, more preferably less than 50 parts by mass, and even more preferably less than 30 parts by mass. The oil content includes the amount of oil contained in the rubber (oil-extended rubber).

[0119] (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.

[0120] Specific examples of process oils (mineral oils) that can be used include products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H&R Co., Ltd., Toyokuni Oil Mills Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., and the like.

[0121] (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.

[0122] 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).

[0123] 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).

[0124] 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).

[0125] 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).

[0126] 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.

[0127] As the liquid rubber, for example, products of Kuraray Co., Ltd., Cray Valley Co., Ltd., etc. can be used.

[0128] (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.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] 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).

[0135] 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.

[0136] 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.

[0137] 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.

[0138] "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.

[0139] 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.

[0140] 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.

[0141] The acrylic resin is not particularly limited, but for example, a solventless acrylic resin can be used.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] (D) Anti-aging agents The rubber composition preferably contains an antioxidant. The content of the antioxidant is, for example, more than 1 part by mass and less than 10 parts by mass per 100 parts by mass of the rubber component.

[0148] 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.

[0149] 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.

[0150] (e) Stearic acid The rubber composition may contain stearic acid. The content of stearic acid is, for example, more than 0.5 parts by mass and less than 10.0 parts by mass with respect to 100 parts by mass of the rubber component. As the stearic acid, a conventionally known product can be used, for example, a product from NOF Corporation, NOF Corporation, Kao Corporation, FUJIFILM Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc. can be used.

[0151] (F) Zinc oxide The rubber composition may contain zinc oxide. The content of zinc oxide is, for example, more than 0.5 parts by mass and less than 15 parts by mass with respect to 100 parts by mass of the rubber component. As the zinc oxide, a conventionally known product can be used, for example, a product of Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc. can be used.

[0152] (G) Crosslinking agents and vulcanization accelerators The rubber composition preferably contains a crosslinking agent such as sulfur, etc. The content of the crosslinking agent is, for example, more than 0.1 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component.

[0153] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. These may be used alone or in combination of two or more kinds.

[0154] 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.

[0155] Examples of crosslinking agents other than sulfur include vulcanizing agents containing sulfur atoms, such as Tackirol V200 manufactured by Taoka Chemical Co., Ltd., Duralink HTS (sodium 1,6-hexamethylenedithiosulfate dihydrate) manufactured by Flexsys, and KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane) manufactured by LANXESS, as well as organic peroxides such as dicumyl peroxide.

[0156] 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.

[0157] Examples of the vulcanization accelerator 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); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenyl guanidine, di-orthotolyl guanidine, and orthotolyl biguanidine. These may be used alone or in combination of two or more kinds.

[0158] (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. 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.

[0159] (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 silica or carbon black, and a finish kneading step of kneading the kneaded product obtained in the base kneading step with a crosslinking agent.

[0160] The kneading can be carried out using a known (internal) kneading machine such as a Banbury mixer, a kneader, or an open roll.

[0161] 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, stearic acid, zinc oxide, antioxidants, waxes, vulcanization accelerators, etc., may be appropriately added and kneaded as necessary.

[0162] 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.

[0163] (3) Manufacturing of tread The tread portion can be manufactured by molding the rubber composition obtained above into a predetermined shape. In the case of a multi-layer tread having a cap layer, a base layer, etc., the rubber composition is made to be the outermost layer.

[0164] 2. Manufacturing of belt components The belt member can be produced by topping both sides of reinforcing cords (monofilament cords such as steel cords) arranged in parallel at a predetermined interval (50 cords / 5 cm or more) with a known coating rubber composition.

[0165] 3. Tire manufacturing The tire according to the present embodiment can be produced as an unvulcanized tire by molding the tread portion and belt member obtained above together with other tire components in a tire building machine by a normal method.

[0166] 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 filling air pressure received by the tire, and a belt member prepared as described above as a member for tightly fastening 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 outer side to form the side portion, thereby producing an unvulcanized tire.

[0167] In this embodiment, as described above, from the viewpoint of increasing the binding force on the tread during running and making it easier to suppress the growth of the outer diameter, it is preferable that at least two belt layers are provided and formed on the belt member. In this case, it is preferable that the average distance D (mm) between each belt layer in the tread portion of the vulcanized tire is 0.6 mm or less. It is also preferable that the angle formed by each belt layer in the tread portion in the tire circumferential direction is 65° or less.

[0168] 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.

[0169] 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.

[0170] A tire is preferable because it has excellent low rolling resistance when mounted on a regular rim and the tire cross-sectional width Wt (mm) and tire outer diameter Dt (mm) satisfy the following formula when the internal pressure is set to 250 kPa. 1600≦(Dt 2 ×π / 4) / Wt≦2827.4

[0171] Specific examples of tires to which the present invention 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.

[0172] In this embodiment, among tires classified into passenger car tires, truck and bus tires, motorcycle tires, etc., 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, and by satisfying (Equation 1), it can more appropriately contribute to solving the problem in the present invention of providing a pneumatic tire that has excellent handling stability and durability during high-speed driving.

[0173] The above-mentioned maximum load capacity is not particularly limited as long as it is 1000 kg or less. However, since an increase in the maximum load capacity generally leads to an increase in tire weight and a larger impact transmitted to the tire, 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.

[0174] Here, from the viewpoint of mitigating the impact transmitted to the tire, the tire weight is preferably 20 kg or less, more preferably 15 kg or less, further preferably 12 kg or less, 10 kg or less, or even more preferably 8 kg or less. EXAMPLES

[0175] The present invention will now be described more specifically with reference to examples.

[0176] [Experiment 1] In this experiment, tires having a tire size of 185 / 65R16 were manufactured and evaluated.

[0177] 1. Production of rubber composition for tread First, a rubber composition for a tread was produced.

[0178] (1) Compounding materials First, the following blended materials were prepared.

[0179] (a) Rubber component (a) NR:TSR20 (b) SBR: Versalis C2525 (solution polymerization SBR) (styrene content: 26% by mass, vinyl bond content: 24% by mass) (c) BR: UBEPOL BR150B manufactured by Ube Industries, Ltd. (Cis content: 97% by mass, Trans content: 2% by mass)

[0180] (b) Compounding materials other than rubber components (a) Carbon black: Show Black N220 manufactured by Cabot Japan Co., Ltd. (N2SA:111m 2 / g) (b) Silica: Ultrasil VN3 manufactured by Evonik (BET specific surface area: 165m 2 / g) (c) Silane coupling agent: Degussa Si69 (Bis(3-triethoxysilylpropyl)tetrasulfide) (d) Oil: H&R VIVATEC NC500 (aromatic process oil) (E) Resin: Terpene styrene resin TO125 manufactured by Yasuhara Chemical Co., Ltd. (Aromatic modified terpene resin) (f) Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. (G) Anti-aging agent-1: Nocrac 6C manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine) (H) Anti-aging agent-2: Antage RD manufactured by Kawaguchi Chemical Industry Co., Ltd. (2,2,4-trimethyl-1,2-dihydroquinoline) (R) Wax: Ozoace 0355 manufactured by Nippon Seiro Co., Ltd. (J) Stearic acid: NOF Corp.'s "Tsubaki" stearic acid (K) Crosslinking agents and vulcanization accelerators Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator-1: Noccela CZ-G (CZ) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N-cyclohexyl-2-benzothiazolyl sulfenamide) Vulcanization accelerator-2: Noccela D (DPG) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (1,3-Diphenylguanidine)

[0181] (2) Production of Rubber Composition According to the composition shown in Tables 1 and 2, materials other than sulfur and vulcanization accelerator were kneaded for 5 minutes at 150°C using a Banbury mixer to obtain a kneaded mixture. Each compounding amount is in parts by mass.

[0182] Next, sulfur and a vulcanization accelerator were added to the obtained kneaded mixture, and the mixture was kneaded for 5 minutes at 80° C. using an open roll to obtain a rubber composition for tread.

[0183] 2. Tire manufacturing First, steel cords having the configuration and outer diameter shown in Tables 1 and 2 were arranged in the ends (pieces / 5 cm) shown in Tables 1 and 2, and then the previously obtained rubber composition for belts was coated on both sides of the arrangement to produce a belt member with a total thickness of "cord diameter (mm) + cord distance × 2 (mm)".

[0184] Thereafter, two layers of the belt members were laminated together so as to cross each other at the distance and angle shown in Tables 1 and 2 to form a belt layer, which was then laminated together with a tread member prepared using the above-mentioned rubber composition for a tread and other tire components to form an unvulcanized tire. The tire was press-vulcanized for 10 minutes under a condition of 170°C to produce each test tire shown in Tables 1 and 2 (outer diameter Dt: 646 mm, cross-sectional width Wt: 189 mm, virtual volume V: 37429958 mm 3 ) was manufactured.

[0185] In addition, 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 portion, and the total volume of the lateral grooves, including those with a groove width / groove depth ratio of 0.65, was 3.5% of the volume of the tread portion.

[0186] 3. Calculation of parameters Thereafter, the distance T (mm) from the outermost surface of the tread portion of each test tire to the outermost surface of the belt layer was measured, and the tire weight WT (kg) was measured to determine the ratio of WT to the maximum load capacity WL (kg) calculated from the above V (WT / WL). In addition, rubber was cut out from between the belt layers of each test tire to prepare a rubber test piece for viscoelasticity measurement with a length of 40 mm and a width of 4 mm, and the complex modulus of elasticity E was measured using a GABO Iplexer series under the conditions of temperature: 30°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10 Hz, and deformation mode: extension. * (MPa) was measured, and (E * × T) was calculated. The results are shown in Tables 1 and 2.

[0187] 4.Performance evaluation test (1) Evaluation of driving stability Each test tire was fitted to all wheels of a vehicle (a domestically produced FF vehicle with an engine displacement of 2000cc) and filled with air to an internal pressure of 250kPa. The vehicle was then driven at 120km / h on a test course with a dry road surface, and the drivers evaluated the handling characteristics sensorily on a 5-point scale from 1 to 5. The total score of the evaluations by the 20 drivers was then calculated.

[0188] Next, the results of Comparative Examples 1-10 were set as 100 and indexed according to the following formula to evaluate the handling stability during high-speed driving. A larger value indicates better handling stability during high-speed driving. Steering stability = [(Test tire results) / (Comparative example 1-10 results)] x 100

[0189] (2) Evaluation of durability 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, then the vehicle was overloaded and driven around a test course on a dry road surface at a speed of 50km / h for 10 laps, and then repeatedly driven over uneven surfaces at a speed of 80km / h.Then, the vehicle was driven around again at a speed of 50km / h, and the speed was gradually increased, and the speed at which the driver felt something was wrong was measured.

[0190] Next, the results of Comparative Examples 1-10 were set as 100, and the durability performance was relatively evaluated by indexing it according to the following formula. A larger value indicates better durability. Durability performance=[(Test tire results) / (Comparative example 1-10 results)]×100

[0191] (3) Overall evaluation The results of the evaluations (1) and (2) above were summed up to determine the overall evaluation.

[0192] (4) Evaluation results The results of each evaluation are shown in Tables 1 and 2. In the tables, "1x1" indicates that the cord is a monofilament, and "1x2" indicates that it is a twisted wire made of two filaments twisted together.

[0193] [Table 1]

[0194] [Table 2]

[0195] [Experiment 2] In this experiment, a tire with a tire size of 205 / 55R16 (outer diameter Dt: 632 mm, cross-sectional width Wt: 214 mm, virtual volume V: 39373809 mm 3 ) was prepared and evaluated.

[0196] In the same manner as in Experiment 1, each test tire shown in Tables 3 and 4 was manufactured, and each parameter was determined in the same manner. Then, a performance evaluation test was conducted and evaluated in the same manner. The low rolling resistance was evaluated by setting the result of Comparative Example 2-10 to 100, and the noise performance was also evaluated by setting the result of Comparative Example 2-10 to 100. The results of each evaluation are shown in Tables 3 and 4.

[0197] [Table 3]

[0198] [Table 4]

[0199] [Experiment 3] In this experiment, a tire with a tire size of 215 / 55R17 (outer diameter Dt: 668 mm, cross-sectional width Wt: 226 mm, virtual volume V: 46109661 mm 3 ) was prepared and evaluated.

[0200] In the same manner as in Experiment 1, each test tire shown in Tables 5 and 6 was manufactured, and each parameter was determined in the same manner. Then, a performance evaluation test was conducted and evaluated in the same manner. The low rolling resistance was evaluated by setting the result of Comparative Example 3-10 to 100, and the noise performance was also evaluated by setting the result of Comparative Example 3-10 to 100. The results of each evaluation are shown in Tables 5 and 6.

[0201] [Table 5]

[0202] [Table 6]

[0203] The results of Experiments 1 to 3 (Tables 1 to 6) show that, for any size tire, when the reinforcing cords in the belt layer are configured with monofilament cords arranged at 50 cords / 5 cm or more and the above-mentioned (Equation 1) is satisfied, a pneumatic tire with excellent handling stability and durability at high speeds can be obtained.

[0204] It can also be seen that by controlling according to the above-mentioned (Equation 2) and by appropriately controlling the outer diameter of the cord, a pneumatic tire having even more excellent driving stability and durability during high-speed driving can be obtained.

[0205] Although the present invention has been described above based on the embodiment, the present invention is not limited to the above embodiment. Various modifications can be made to the above embodiment within the same and equivalent scope of the present invention.

Claims

1. A pneumatic tire having a belt layer and a tread portion, The tread portion is disposed on the outer side of the belt layer in the tire radial direction, The reinforcing cords in the belt layer are configured such that cords made of monofilaments are arranged in a tire width direction at 50 cords / 5 cm or more in a tire radial cross section of the belt layer, A pneumatic tire characterized in that the maximum load capacity WL (kg) and the weight WT (kg) of the tire satisfy the following (Equation 1). (WT / WL)≦0.0135 (Formula 1) The "maximum load capacity WL of the tire" is a value 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, the internal pressure is set to 250 kPa, and there is no load. V (mm 3 ) = {(Dt / 2) 2 - (Dt / 2-Ht) 2}×π×Wt WL (kg) = 0.000011 x V + 100

2. 2. The pneumatic tire according to claim 1, wherein the cord made of the monofilament has an outer diameter of 0.1 to 0.5 mm.

3. The tread rubber composition forming the ground contact surface in the outermost layer of the tread portion was measured under the conditions of temperature: 30° C., initial strain: 5%, dynamic strain: ±1%, frequency: 10 Hz, and deformation mode: extension. ＊ (MPa) and A distance T (mm) from the outermost surface of the tread portion to the outermost surface of the belt layer; 3. The pneumatic tire according to claim 1, wherein the following formula 2 is satisfied: (E ＊ ×T)≧30……………………(Formula 2)

4. The tread portion has a plurality of circumferential grooves extending continuously in a circumferential direction of the tire, 4. The pneumatic tire according to claim 1, wherein a total cross-sectional area of ​​the plurality of circumferential grooves is 10 to 30% of a cross-sectional area of ​​the tread portion.

5. The tread portion has a plurality of lateral grooves extending in an axial direction of the tire, 5. The pneumatic tire according to claim 1, wherein a total volume of the plurality of lateral grooves is 2.0 to 5.0% of a volume of the tread portion.

6. At least two belt layers are provided, In at least one pair of belt layers adjacent in the tire radial direction, 6. The pneumatic tire according to claim 1, wherein an average distance D (mm) between the belt layers in the tread portion is 0.6 mm or less.

7. At least two belt layers are provided, In at least one pair of belt layers adjacent in the tire radial direction, 7. The pneumatic tire according to claim 1, wherein an angle between the belt layers in the tread portion in the tire circumferential direction is 65 degrees or less.

8. The tire has a circumferential groove in the tread portion that extends continuously in the 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 8. The pneumatic tire according to claim 1, wherein the ratio of the surface roughness to the surface roughness of the tire is 0.3 to 0.

7.

9. A pneumatic tire as described in any one of claims 1 to 8, characterized in that the tire cross-sectional width Wt (mm) is less than 200 mm.

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