Pneumatic tire

Abstract

Provided is a pneumatic tire having excellent handling stability and durability during high-speed running. A pneumatic tire is a tire having a belt layer and a tread portion, the tread portion being disposed on the tire radial direction outer side of the belt layer, in a cross section of the tire radial direction of the belt layer, the reinforcing cords in the belt layer being constituted by cords composed of monofilaments in the tire width direction at an arrangement of 50 or more per 5 cm, the maximum load capacity WL (kg) of the tire and the weight WT (kg) of the tire satisfying the following (Formula 1). (WT / WL) ≤ 0.0140 ··· (Formula 1).

Description

Technical Field

[0001] This invention relates to a pneumatic tire, and more specifically to a pneumatic tire having a belt layer. Background Technology

[0002] In recent years, driven by growing concern for environmental issues and economic considerations, there has been a growing demand for lower fuel consumption in automobiles, and a strong requirement for improved fuel efficiency in pneumatic tires (hereinafter referred to as "tires") installed on automobiles.

[0003] The fuel efficiency of a tire can be evaluated by its rolling resistance; the lower the rolling resistance, the better the fuel efficiency of the tire.

[0004] Therefore, compared to the past, it has been proposed to reduce rolling resistance by adjusting the rubber composition that constitutes the tread of the tire (for example, Patent Documents 1-4).

[0005] In addition to the above, the development of technologies that make tires lighter, such as those that make the tire carcass, belt layer, and bead lightweight, is becoming increasingly active.

[0006] Existing technical documents

[0007] Patent documents

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2018-178034

[0009] [Patent Document 2] Japanese Patent Application Publication No. 2019-089911

[0010] [Patent Document 3] WO 2018 / 186367

[0011] [Patent Document 4] Japanese Patent Application Publication No. 2019-206643 Summary of the Invention

[0012] The problem the invention aims to solve

[0013] However, with the widespread development of highways, it is not uncommon to use highways for long-distance travel nowadays. Considering that the maximum load capacity of the tire WL (kg) and the weight of the tire WT (kg) satisfy the following relationship (Equation 1), can the handling stability and durability at high speeds be guaranteed?

[0014] (WT / WL)≤0.0140·····(Formula 1)

[0015] Therefore, the present invention aims to provide a pneumatic tire that, even with a certain degree of weight reduction, can still exhibit excellent handling stability and durability at high speeds.

[0016] Technical means to solve the problem

[0017] In order to solve the above-mentioned problems, the inventors conducted in-depth research and found that the above-mentioned problems could be solved by the invention described below, and thus completed the present invention.

[0018] 1) The invention described is a pneumatic tire, characterized in that,

[0019] It has a belt layer and a tread.

[0020] The tread portion is positioned radially outward of the belt layer of the tire.

[0021] The reinforcing cords in the belt layer, in the radial section of the belt layer, are composed of monofilament cords arranged at a rate of 50 cords per 5cm or more in the width direction of the tire.

[0022] The maximum load capacity WL (kg) and the weight WT (kg) of the tire satisfy the following (Equation 1).

[0023] (WT / WL)≤0.0140·····(Formula 1)

[0024] 2) The invention described is the pneumatic tire described in 1), characterized in that,

[0025] The outer diameter of the cord composed of monofilaments is 0.1 to 0.5 mm.

[0026] 3) The invention described is the pneumatic tire described in 1) or 2), characterized in that,

[0027] The complex elastic modulus E of the tread rubber composition forming the outermost contact surface in the tread portion is measured under the following conditions: temperature: 30°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10Hz, and deformation mode: tension. ＊ The distance T (mm) from the outermost surface of the tread to the outermost surface of the belt layer satisfies the following (Equation 2).

[0028] (E ＊ ×T)≥30·····(Equation 2)

[0029] 4) The invention described is a pneumatic tire as described in any one of 1) to 3), characterized in that,

[0030] The tread section has multiple circumferential grooves that extend continuously along the tire circumference.

[0031] The total cross-sectional area of ​​the multiple circumferential grooves is 10% to 30% of the cross-sectional area of ​​the tread.

[0032] 5) The invention described is a pneumatic tire as described in any one of 1) to 4), characterized in that,

[0033] The tread section has multiple transverse grooves extending along the tire axial direction.

[0034] The total volume of the multiple transverse grooves is 2.0 to 5.0% of the volume of the tread area.

[0035] 6) The invention described is the pneumatic tire described in any one of 1) to 5), characterized in that,

[0036] The belt layer has at least two layers.

[0037] In at least one of the groups of belt layers that are adjacent in the radial direction of the tire,

[0038] The average distance D (mm) between each belt layer in the tread area is less than 0.6 mm.

[0039] 7) The invention described is a pneumatic tire as described in any one of 1) to 6), characterized in that,

[0040] The belt layer has at least two layers.

[0041] In at least one of the groups of belt layers that are adjacent in the radial direction of the tire,

[0042] The angle between each belt layer in the tread portion and the tire circumferential direction is less than 65°.

[0043] 8) The invention described is a pneumatic tire as described in any one of 1) to 7), characterized in that,

[0044] The tread has circumferential grooves that extend continuously along the tire's circumference.

[0045] The groove width L at 80% of the maximum depth of the circumferential groove 80 The ratio (L0) of the circumferential groove width L0 on the contact surface of the tread surface to the groove width L0 of the circumferential groove. 80 / L0) is 0.3 to 0.7.

[0046] 9) The invention described is a pneumatic tire as described in any one of 1) to 8), characterized in that,

[0047] The cross-sectional width Wt (mm) of the tire is less than 200mm.

[0048] The effects of the invention

[0049] According to the present invention, a pneumatic tire can be provided that, even with a certain degree of weight reduction, can still exhibit excellent handling stability and durability at high speeds. Detailed Implementation

[0050] [1] Features of the tire involved in this invention

[0051] First, the features of the pneumatic tire involved in this invention will be described.

[0052] 1. Summary

[0053] The tire involved in this invention is a tire with a belt layer and a tread, and the maximum load capacity WL (kg) of the tire and the weight WT (kg) of the tire satisfy the following relationship (Equation 1).

[0054] (WT / WL)≤0.0140·····(Formula 1)

[0055] Then, the tread portion is positioned on the radial outer side of the belt layer of the tire. The reinforcing cords in the belt layer are composed of monofilament cords (hereinafter also referred to as "monofilament cords") arranged in a tire width direction of 50 cords / 5cm or more on the radial section of the belt layer.

[0056] With the above-described configuration, even if the tire is made lighter to a certain extent, specifically, even if the maximum load capacity WL (kg) and the tire weight WT (kg) satisfy the relationship described above (Equation 1), it is still possible to provide a pneumatic tire with excellent handling stability and durability at high speeds.

[0057] Furthermore, in the above description, "maximum load capacity WL" refers to 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) under no-load conditions, with the tire mounted on a standard rim and the internal pressure set to 250 kPa. This value is approximately 50-100 kg less than the maximum load capacity specified by the JATMA (Japan Automobile Tire Association) standard for load index (LI). Additionally, V represents the volume of space occupied by the tire (imaginary volume), and (Dt / 2 - Ht) is the rim diameter.

[0058] V(mm 3 )={(Dt / 2) 2 -(Dt / 2-Ht) 2}×π×Wt

[0059] WL (kg) = 0.000011 × V + 100

[0060] Here, "standard rim" refers to the rim specified for each tire within a specification system, including tire specifications. For example, for JATMA, it refers to the standard rim in the applicable size listed in the "JATMA YEAR BOOK"; for ETRTO (The European Tyre and Rim Technical Organization), it refers to the "Measuring Rim" listed in the "STANDARDS MANUAL"; and for TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" listed in the "YEAR BOOK". Then, in cases where the specification does not specify a tire, it refers to a rim that can be assembled and maintains internal pressure; that is, among rims that prevent air leakage between the rim and tire, the one with the smallest rim diameter and the next narrowest rim width.

[0061] Then, the tire section width Wt can be obtained by subtracting the width of the tire sidewall patterns, text, etc., from the straight-line distance between all tire sidewall portions (the total tire width). Additionally, the tire section height Ht can be obtained by taking half the difference between the tire's outer diameter and the rim's nominal diameter.

[0062] 2. The mechanism by which the effect in the tire involved in this invention is generated.

[0063] The mechanism by which the effect in the tire involved in this invention is generated, namely, the mechanism by which the tire can be fully reduced in weight to a certain extent while still achieving both high-speed handling stability and durability, is speculated as follows.

[0064] One way to improve tire fuel efficiency is to reduce the amount (thickness) of tire components, thereby reducing tire weight. However, reducing the number of tire components can decrease tire rigidity and moment of inertia, potentially leading to reduced handling stability.

[0065] In particular, at high speeds, the tire tread is prone to rounding due to centrifugal force, which significantly reduces handling stability. Furthermore, the amount of tire deformation during driving is also considered to increase, greatly reducing durability.

[0066] Specifically, this refers to whether the handling stability and durability at high speeds can be guaranteed when the tire's maximum load capacity WL (kg) and tire weight WT (kg) satisfy the following relationship (Equation 1).

[0067] (WT / WL)≤0.0140·····(Formula 1)

[0068] In this invention, the belt layer used to reinforce the tread is not a cord composed of twisted yarn (twisted cord), but rather a cord composed of monofilament (single thread) (monofilament cord). Unlike twisted cord, monofilament cords are less prone to elongation, thus suppressing the elongation of the belt layer. Furthermore, by arranging these monofilament cords at a density of 50 or more strands per 5 cm (i.e., at a spacing of less than 1 mm between each strand), the belt layer provides sufficient restraint on the tread. Therefore, even with the lightweight tire, the tread is less likely to become rounded at high speeds, ensuring handling stability and durability at high speeds.

[0069] Then, with the above configuration, even if (WT / WL) ≤ 0.0140 (Equation 1), sufficient handling stability and durability can be obtained at high speeds. Furthermore, setting (WT / WL) to 0.0135 or less allows for sufficiently low rolling resistance, achieving low fuel consumption while maintaining sufficient handling stability and durability at high speeds. Further weight reduction, resulting in (WT / WL) below 0.0133, yields even better results.

[0070] In addition, the aforementioned number of monofilaments refers to the average number of cords arranged in the width direction of the tire when installed on a standard rim, with an internal pressure of 250 kPa and no load. Simply put, it can be obtained by measuring the number of cords arranged in a 2-4 cm thick section along the radius of the tire, with a width of 5-10 cm centered on the equator of the tire, and calculating the average number of cords per 5 cm.

[0071] The outer diameter of the monofilament cord is preferably between 0.1 mm and 0.5 mm. If it is less than 0.1 mm, the force generated by each monofilament is too weak and may not provide sufficient restraint. Furthermore, considering that the cord is prone to breakage due to impact during driving, this may reduce the improvement in high-speed handling stability and durability.

[0072] On the other hand, if the outer diameter of the cord is greater than 0.5 mm, it is difficult to cover the rubber on the monofilament cords without gaps to form a belt layer when arranging the monofilament cords. At the same time, because the distance between the monofilament cords is too narrow, the monofilament cord layer is difficult to deform in the width direction when turning, and cannot generate sufficient stress, which may reduce the effect of improving handling stability.

[0073] Based on 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, as an upper limit, it is more preferably 0.40 mm or less, and even more preferably 0.35 mm or less. Furthermore, the outer diameter of the monofilament cord refers to the outer diameter of the monofilament cord in the tire width direction. When the cord cross-section is a perfect circle, it is equivalent to the conventional outer diameter. When the cord has an aspect ratio, and the major diameter of the cord is Φ (mm), and the angle between the line parallel to the tire width direction and the major diameter Φ is θ, it refers to the distance occupied in the tire width direction calculated by Φ × cosθ.

[0074] [2] A more preferred method in the tires involved in this invention

[0075] The tires involved in this invention can achieve greater effects by adopting the following methods.

[0076] 1. The complex elastic modulus of the tread rubber and the distance from the tread to the belt layer.

[0077] In the tires of the present invention, the tread rubber composition forming the outermost contact surface of the tread layer is preferably characterized by a complex elastic modulus E measured under the following conditions: temperature: 30°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10Hz, and deformation mode: tension. ＊ (MPa) and the distance T (mm) from the outermost surface of the tread to the outermost surface of the belt layer satisfy (E ＊ ×T)≥30.

[0078] Complex elastic modulus E ＊ This is a parameter related to rigidity; the higher the value, the stronger the rigidity, which can suppress the rounding of the tread surface during high-speed driving and also facilitate the generation of greater reaction forces on the tread surface. Furthermore, because it improves the overall rigidity of the tread, it can more easily suppress large deformations of the tread surface upon impact.

[0079] On the other hand, the distance from the outermost surface of the tread layer to the outermost surface of the belt layer can also be considered a parameter representing the effect of the rigidity of the tread layer on the belt layer. The larger this value, the more adequately the restraint of the belt layer can be ensured. At the same time, the larger the value, the better the distance from the tread surface to the belt layer is maintained, and the more the belt layer can be deformed in the radial direction of the tire.

[0080] Under this idea, for the complex elastic modulus E ＊ The preferred relationship between (MPa) and the distance T (mm) from the outermost surface of the tread layer to the outermost surface of the belt layer was found through experiments to be that if the above (E) can be satisfied... ＊The relationship of ×T)≥30 can ensure the constraint from the belt layer, while the deformation of the belt layer in the tire radial direction is also small, thus improving the handling stability and durability at high speeds.

[0081] In addition, in the above record, the complex elastic modulus E ＊ For example, it is possible to perform the measurement using a viscoelasticity measuring device such as the "EPLEXOR (registered trademark)" manufactured by GABO Corporation. Then, (E ＊ The value of ×T) is more preferably 35 or more, and even more preferably 40 or more.

[0082] Then, in the above description, the distance T (mm) from the outermost surface of the tread to the outermost surface of the belt layer refers to the straight-line distance from the tread surface on the equatorial surface of the tire to the surface of the monofilament cord of the outermost layer of the belt layer on the radial section of the tire when it is mounted on a regular rim, with an internal pressure of 250 kPa and no load.

[0083] Furthermore, when grooves are formed on the equatorial surface of the tire tread, the distance T is the distance from the intersection of the line obtained from the end of the tire contact surface connecting the grooves and the tire equatorial surface to the outermost layer of the belt layer. Conversely, when there are no monofilament cords on the tire equatorial surface for the outermost layer of the belt layer, the distance T is calculated by taking the intersection of the line connecting the two points on the outermost radial side of the tire closest to the equatorial surface and the equatorial surface as the location of the outermost layer of the belt layer.

[0084] In simple terms, the distance T (mm) mentioned above can be measured by cutting a portion of the tire bead with a thickness of 2 to 4 cm along the width of the tire, while pressing and aligning it with the corresponding rim width.

[0085] In addition, the complex elastic modulus E of the above-mentioned rubber composition ＊ While there is no particular upper limit, it is preferably 15.0 MPa or less, more preferably 12.0 MPa or less, and even more preferably 9.0 MPa or less.

[0086] If the pressure exceeds 15.0 MPa, the tread becomes difficult to deform, making it difficult to improve handling stability at high speeds. On the other hand, there is no particular lower limit, but it is preferably 3.0 MPa or higher, more preferably 3.7 MPa or higher, and even more preferably 5.0 MPa or higher. If the pressure is less than 3.0 MPa, the rigidity of the tread will decrease, and the amount of deformation will become too large, making it difficult to improve durability.

[0087] In addition, the distance T (mm) from the outermost surface of the tread to the outermost surface of the belt layer is preferably 12.0 mm or less, more preferably 10.0 mm or less, and even more preferably 7.5 mm or less.

[0088] If the distance is greater than 12.0 mm, the shear deformation generated on the tread surface is difficult to transmit to the belt layer due to the excessive distance from the tread surface to the belt layer, resulting in insufficient reaction force and hindering the improvement in handling stability at high speeds. Furthermore, a lower limit is preferably 6.0 mm or more, and more preferably 7.0 mm or more. If the distance is less than 6.0 mm, impacts from the tread surface are easily transmitted to the belt layer, making it difficult to achieve improved durability.

[0089] 2. Grooves on the tire tread

[0090] The tire of this invention has a tread portion with multiple circumferential grooves, the total cross-sectional area of ​​which is preferably 10% to 30% of the tread portion's cross-sectional area. This suppresses tread portion movement, thereby significantly improving handling stability and durability at high speeds. More preferably, it is 15% to 27%, even more preferably 18% to 25%, and particularly preferably 21% to 23%.

[0091] The aforementioned tread cross-sectional area refers to the area from the belt layer to the radial outer side of the tire on the radial cross-section of a tire mounted on a standard rim with an internal pressure of 250 kPa and under no load, including the straight line connecting the ends of the circumferential grooves of the tread, the tread surface profile formed by the tread surface, and the area divided by two straight lines parallel to the equatorial plane passing through the two ends of the widest part of the belt layer.

[0092] Additionally, when the belt reinforcement layer, made of organic fibers and / or steel cords, extends from the belt reinforcement layer to the radially outer side of the tire, it refers to the area extending from the belt reinforcement layer to the radially outer side. On the other hand, the cross-sectional area of ​​the circumferential groove refers to the total area formed by the straight line connecting the ends of the circumferential grooves on the tire cross-section under a standard rim, internal pressure of 250 kPa, and no-load connection, along with the groove walls. Simply put, these can be calculated by cutting a 2-4 cm thick portion of the tire bead in the radial direction and pressing it to align with the rim width.

[0093] Furthermore, the tread has multiple lateral grooves extending along the tire axial direction, and the total volume of these grooves is preferably 2.0% or more and 5.0% or less of the tread volume. This suppresses tread movement, thereby significantly improving handling stability and durability at high speeds. More preferably, it is 2.2% or more and 4.0% or less; even more preferably, it is 2.5% or more and 3.5% or less; and particularly preferably, it is 2.7% or more and 3.0% or less.

[0094] The volume of the tread portion mentioned above refers to the volume obtained by extending the area of ​​the tread portion along the tire circumference. Simply put, it can be obtained by multiplying the area of ​​the tread portion by the length of the tire's outer rim (Dt×π). Furthermore, the volume of the lateral grooves refers to the total volume formed by the surface connecting the ends of the lateral grooves and the groove walls on a tire mounted on a standard rim with an internal pressure of 250 kPa and under no load. This can be calculated by determining the volume of each individual lateral groove.

[0095] Furthermore, the groove width L at a depth of 80% of the maximum depth of the circumferential groove. 80 The ratio of the width L0 of the circumferential grooves relative to the contact surface of the tread (L) 80 The value of L0 is preferably 0.3 or higher and 0.7 or lower. This allows for the suppression of overall land movement by utilizing the bottom surface of the land portion of the tread, thus significantly improving handling stability and durability at high speeds. More preferably, it is 0.35 or higher and 0.65 or lower; even more preferably, it is 0.40 or higher and 0.60 or lower; and particularly preferably, it is 0.45 or higher and 0.55 or lower.

[0096] The above L0 and L 80 This refers to the straight-line distance (L0) between the ends of the grooves on the surface of the tread grooves of a tire mounted on a standard rim with an internal pressure of 250 kPa and in an unloaded state, and the minimum distance (L) between the groove ends and the groove walls located at 80% of the groove depth. 80 In simple terms, the width of the tire bead is cut out in the radial direction, and the width is determined by pressing it to align with the rim width.

[0097] 3. Multilayering of the belt layer

[0098] In this invention, the belt layer is multi-layered to have at least two layers. In at least one group of belt layers that are adjacent to each other in the radial direction of the tire, the average distance D (mm) between the belt layers in the tread area is preferably less than 0.6 mm.

[0099] Thus, the one set of belt layers cooperate with each other to properly constrain the tread, which can suppress the deformation of the tread during rolling, and further improve the handling stability and durability at high speeds.

[0100] In addition, the average distance D between the belt layers mentioned here refers to the average distance between the monofilaments (cords) of the belt layers, which is the distance between the inner surface of the monofilament of the outer belt layer and the outer surface of the monofilament of the inner belt layer on the equatorial plane of two overlapping belt layers.

[0101] Furthermore, in the case of multi-layered belt layers, in at least one group of belt layers that are adjacent to each other in the radial direction of the tire, the angle between the belt layers in the tread portion and each other in the circumferential direction of the tire is preferably 65° or less, more preferably 60° or less, and even more preferably 58° or less.

[0102] By configuring the belt layers at an appropriate angle to each other, a clamping effect is achieved, which strongly constrains almost the entire width of the tread, suppressing the amount of tread deformation during rolling, thus maintaining low rolling resistance and handling stability.

[0103] Furthermore, the aforementioned angle is formed by the angle of a single filament in the tire when it is not filled with air relative to the tire's circumference, and can be confirmed by peeling off the tread from the radial side of the tire.

[0104] By configuring the belt layers at an appropriate angle to each other, the deformation of the tread during rolling can be suppressed due to the strong constraint on almost the entire width of the tread, thereby further improving handling stability and durability at high speeds.

[0105] 4. Tire shape

[0106] For the tire involved in this invention, when installed on a standard rim with an internal pressure of 250 kPa, the specific tire outer diameter Dt (mm) is preferably 515 mm or more, more preferably 558 mm or more, further 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 further preferably less than 707 mm.

[0107] Then, regarding the specific tire cross-section width Wt (mm), it is preferably 115mm or more, more preferably 130mm or more, even more preferably 150mm or more, even more preferably 170mm or more, particularly preferably 185mm or more, and most preferably 193mm or more. On the other hand, it is preferably less than 305mm, more preferably less than 245mm, even more preferably less than 210mm, particularly preferably less than 205mm, and most preferably less than 200mm.

[0108] Then, regarding the specific tire section height Ht (mm), it is preferably 37mm or more, more preferably 87mm or more, and even more preferably 95mm or more. On the other hand, it is preferably less than 180mm, more preferably less than 112mm, and even more preferably less than 101mm.

[0109] Then, as a specific value for the aforementioned V (imaginary volume), for example, it is preferably 13,000,000 mm. 3The above, more preferably 29,000,000 mm 3 The above is further preferred to be 36,000,000 mm. 3 That's all. On the other hand, it is preferable to have a diameter of less than 66,000,000 mm. 3 More preferably less than 44,000,000 mm 3 More preferably, less than 38,800,000 mm 3 .

[0110] Furthermore, in this invention, considering stability during driving, (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, considering tread deformation, it is preferably less than 560 (mm), more preferably less than 530 (mm), and even more preferably less than 510 (mm).

[0111] [3] Implementation

[0112] The present invention will now be described in detail based on its embodiments.

[0113] 1. The rubber composition constituting the outermost layer of the tread.

[0114] (1) Proportioning materials

[0115] The rubber composition (tread rubber composition) forming the outermost layer of the tread of the tire according to the present invention can be prepared by the rubber components described below, as well as other proportioned materials.

[0116] (a) Rubber composition

[0117] In this embodiment, there are no particular limitations on the rubber component. Diene-based rubbers such as isoprene rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), and nitrile rubber (NBR), butyl rubber, and other rubbers (polymers) commonly used in tire manufacturing can be used. These can be used alone or in combination. Preferably, it contains any one of isoprene rubber, BR, and SBR. It can also contain isoprene rubber and BR, BR and SBR, isoprene rubber and SBR, or isoprene rubber and BR and SBR.

[0118] ①SBR

[0119] The SBR content in 100 parts by weight of the rubber component is preferably greater than 50 parts by weight, more preferably greater than 75 parts by weight, more preferably greater than 80 parts by weight, and even more preferably greater than 85 parts by weight, from the viewpoint of handling stability at high speeds. On the other hand, from the viewpoint of heat dissipation at high speeds, it is preferably less than 100 parts by weight, more preferably less than 95 parts by weight.

[0120] The weight-average molecular weight of the SBR is, for example, greater than 100,000 and less than 2,000,000. The styrene content of the SBR, from the viewpoint of handling stability at high speeds, is preferably greater than 5% by mass, more preferably greater than 10% by mass, and even more preferably greater than 20% by mass. On the other hand, from the viewpoint of heat release and durability at high speeds, 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 content of the SBR (1,2-bonded butadiene unit content) is, for example, greater than 5% by mass and less than 70% by mass. Furthermore, structural analysis of the SBR (determination of styrene content and vinyl bond content) can be performed, for example, using a JNM-ECA series device manufactured by Nippon Electronics Co., Ltd.

[0121] There are no particular limitations on SBR; for example, emulsion-polymerized styrene-butadiene rubber (E-SBR) and solution-polymerized styrene-butadiene rubber (S-SBR) can be used. SBR can be unmodified or modified.

[0122] As a modified SBR, any SBR having a functional group that interacts with fillers such as silica is acceptable. For example, examples include end-modified SBRs (end-modified SBRs with the aforementioned functional groups at the end) which are modified with a compound (modifier) ​​having the aforementioned functional groups at at least one end of the SBR; main-chain modified SBRs with the aforementioned functional groups in the main chain; main-chain end-modified SBRs with the aforementioned functional groups in both the main chain and the end (e.g., main-chain end-modified SBRs with the aforementioned functional groups in the main chain and at least one end modified with the aforementioned modifier at the end); and end-modified SBRs that have been modified (coupled) by a polyfunctional compound having two or more epoxy groups in the molecule, thereby introducing hydroxyl or epoxy groups.

[0123] Examples of the aforementioned functional groups include, for instance, amino, amide, silyl, alkoxysilyl, isocyanate, imino, imidazo, urea, ether, carbonyl, oxycarbonyl, mercapto, thioether, dithio, sulfonyl, sulfinyl, thiocarbonyl, ammonium, imide, hydrazine, azo, diazo, carboxyl, nitrile, pyridyl, alkoxy, hydroxyl, oxygen, and epoxy groups. Furthermore, these functional groups may also have substituents.

[0124] Alternatively, as a modified SBR, for example, an SBR modified by a compound (modifier) ​​represented by the following formula can be used.

[0125]

Chemistry 1

[0126]

[0127] Additionally, in the formula, R 1 R 2 and R 3 They can be the same or different, representing alkyl, alkoxy, silyloxy, acetal, carboxyl (-COOH), mercapto (-SH), or derivatives thereof. R 4 and R 5 They can be the same or different, representing hydrogen atoms or alkyl groups. R 4 and R 5 It can also form a ring structure together with nitrogen atoms through bonding. n represents an integer.

[0128] As a modified SBR modified by the compound (modifier) ​​represented by the above formula, the SBR modified by the compound represented by the above formula can be obtained by using the polymerization end (active end) of solution-polymerized styrene-butadiene rubber (S-SBR). (The modified SBR described in Japanese Patent Application Publication No. 2010-111753, etc.)

[0129] As R 1 R 2 and R 3 Preferably, it is an alkoxy group (preferably containing 1 to 8 carbon atoms, more preferably alkoxy groups containing 1 to 4 carbon atoms). As R 4 and R 5 Preferably, it is an alkyl group (preferably an alkyl group containing 1 to 3 carbon atoms). n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. Additionally, when R... 4 and R 5 When bonding forms a ring structure together with the nitrogen atom, a 4- to 8-membered ring is preferred. In addition, alkoxy groups also include cycloalkoxy groups (such as cyclohexyloxy groups) and aryloxy groups (such as phenoxy and benzyloxy groups).

[0130] Specific examples of the aforementioned modifiers include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane. These can be used alone or in combination of two or more.

[0131] Additionally, modified SBRs can also be made from the following compounds (modifiers). Examples of modifiers include, for instance, polyglycidyl ethers of polyols such as ethylene glycol diglycidyl ether, glycerol triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; polyglycidyl ethers of aromatic compounds having two or more phenolic groups such as bisphenol A diglycidyl ether; polyepoxide compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxide liquid polybutadiene; tertiary amines with epoxy groups such as 4,4'-diglycidyl diphenylmethylamine and 4,4'-diglycidyl dibenzylmethylamine; diglycidyl aniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidyl o-toluidine, and tetraglycidyl aniline. Diglycidylamino compounds such as oleo-based m-phenylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-diaminomethylcyclohexane; amino-containing acyl chlorides such as bis-(1-methylpropyl)carbamoyl chloride, 4-morpholinocarbamoyl chloride, 1-pyrrolidinecarbamoyl chloride, N,N-dimethylcarbamoyl chloride, and N,N-diethylcarbamoyl chloride; epoxy-containing silane compounds such as 1,3-bis-(glycidyloxypropyl)-tetramethyldisiloxane and (3-glycidyloxypropyl)-pentamethyldisiloxane; (trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (trimethylsilyl)[ Silane compounds containing thioether groups, such as 3-(triethoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(tripropoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(tributoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(methyldimethoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(methyldiethoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(methyldipropoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(methyldibutoxysilyl)propyl] sulfide, etc.; N-substituted aziridine compounds of ethyleneimine, acrylimine, etc.; methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethylsilane, etc. Alkoxysilanes such as oxysilanes, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, and N,N-bis(trimethylsilyl)aminoethyltriethoxysilane; (thio)benzophenone compounds having an amino group 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, and N,N,N',N'-bis-(tetraethylamino)benzophenone;Benzaldehyde compounds containing amino groups and / or substituted amino groups, such as 4-N,N-dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, and 4-N,N-divinylaminobenzaldehyde; N-substituted pyrrolidones, such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, Nt-butyl-2-pyrrolidone, and N-methyl-5-methyl-2-pyrrolidone; N-substituted piperidinones, such as N-methyl-2-piperidinone, N-vinyl-2-piperidinone, and N-phenyl-2-piperidinone; N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurolactam, N-vinyl-ω-laurolactam, N-methyl-β-propiolactam, and N-phenyl- Besides N-substituted lactams such as β-propiolactam, other examples include N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), tris-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-triones, N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethylurea, 1,3-divinylethylurea, 1,3-diethyl-2-imidazolinone, 1-methyl-3-ethyl-2-imidazolinone, 4-N,N-dimethylaminoacetophenone, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, and 1,7-bis(methylethylamino)-4-heptanone. Furthermore, modification using the above compounds (modifiers) can be carried out using known methods.

[0132] As an SBR (Self-Borne Blender), for example, SBR manufactured and sold by companies such as Sumitomo Chemical Co., Ltd., JSR Co., Ltd., Asahi Kasei Co., Ltd., Nippon ZEON Co., Ltd., and Versalis Co., Ltd. can be used. Furthermore, SBR can be used alone or in combination with two or more types.

[0133] ②BR

[0134] The above-described rubber composition may further contain BR if necessary. In this case, the BR content in 100 parts by weight of the rubber component is preferably greater than 2 parts by weight, more preferably greater than 4 parts by weight. On the other hand, it is preferably less than 20 parts by weight, more preferably less than 10 parts by weight, and even more preferably less than 6 parts by weight.

[0135] The weight-average molecular weight of BR is, for example, greater than 100,000 and less than 2,000,000. The vinyl content of BR is, for example, greater than 1% by mass and less than 30% by mass. The cis content of BR is, for example, greater than 1% by mass and less than 98% by mass. The trans content of BR is, for example, greater than 1% by mass and less than 60% by mass.

[0136] There are no particular limitations on BR (brane synthesizer). BRs with high cis content (cis content above 90%), low cis content, and syndiotactic polybutadiene crystals can be used. BRs can be unmodified or modified. Examples of modified BRs include those incorporating the aforementioned functional groups. These can be used individually or in combination. Furthermore, the cis content can be determined by infrared absorption spectroscopy.

[0137] As a modified BR, for example, tin-modified BR can also be used. As a tin-modified BR, it can be obtained by adding a tin compound after polymerization of 1,3-butadiene with a lithium initiator, and the ends of the tin-modified BR molecule are preferably bonded by tin-carbon bonds.

[0138] Examples of lithium initiators include lithium-based compounds such as alkyl lithium, aryl lithium, vinyl lithium, organotin lithium, and organonitrogen lithium compounds, as well as lithium metal. By using the above-mentioned lithium initiators as initiators for tin-modified BR, tin-modified BR with high vinyl content and low cis content can be produced.

[0139] Examples of tin compounds include tin tetrachloride, butyltin trichloride, dibutyltin dichloride, dioctyltin dichloride, tributyltin chloride, triphenyltin chloride, diphenyl dibutyltin, triphenyl ethoxytin, diphenyl dimethyltin, xylyltin chloride, diphenyltin dioctanoate, divinyl diethyltin, tetrabenzyltin, dibutyltin distearate, tetraallyltin, and styrene-p-tributyltin.

[0140] Then, the tin atom content in the tin-modified BR is preferably 50 ppm or more, more preferably 60 ppm or more. On the other hand, it is preferably 3000 ppm or less, more preferably 2500 ppm or less, and even more preferably 250 ppm or less.

[0141] In addition, the molecular weight distribution (Mw / Mn) of the tin-modified BR is preferably 2 or less, and more preferably 1.5 or less.

[0142] Furthermore, the vinyl content in the tin-modified BR is preferably 5% by mass or more, more preferably 7% by mass or more. On the other hand, the vinyl content in the tin-modified BR is preferably 50% by mass or less, more preferably 20% by mass or less.

[0143] In addition, the S-modified BR and tin-modified BR mentioned above can be used alone or in combination with more than one type.

[0144] As a BR (Brandinger), products from companies such as Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Japan Zeon Corporation can be used.

[0145] ③Isoprene-based rubber

[0146] Furthermore, the above-mentioned rubber composition may, if necessary, further contain isoprene-based rubber. In this case, the content of isoprene-based rubber in 100 parts by mass of the rubber component is preferably greater than 2 parts by mass, more preferably greater than 4 parts by mass. On the other hand, 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.

[0147] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR, with NR being the preferred choice due to its superior strength.

[0148] As a natural rubber (NR), substances commonly used in the tire industry, such as SIR20, RSS#3, and TSR20, can be used. As an inductively coupled rubber (IR), there are no particular limitations, and substances commonly used in the tire industry, such as IR2200, can be used. Examples of modified NRs include deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR). Examples of modified NRs include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of modified IRs include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These can be used individually or in combination of two or more.

[0149] ④ Other rubber components

[0150] In addition, as other rubber components, if necessary, it may also contain rubbers (polymers) commonly used in tire manufacturing, such as nitrile rubber (NBR).

[0151] (b) Materials other than rubber components

[0152] ① Filler

[0153] In this embodiment, the rubber composition preferably contains a filler. Specific fillers include, for example, carbon black, silica, graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, etc. Among these, silica is preferably used as a reinforcing agent, and in this case, it is preferable to use it in combination with a silane coupling agent. Additionally, if necessary, carbon black is preferably used as a reinforcing agent.

[0154] (i) Silicon dioxide

[0155] The rubber composition preferably contains silica. From the viewpoint of obtaining good durability, the BET specific surface area of ​​silica is preferably greater than 140 m². 2 / g, more preferably greater than 160m 2 / g. On the other hand, from the viewpoint of obtaining good low rolling resistance, it is preferable to have less than 250m.2 / g, more preferably less than 220m 2 / g. Furthermore, the above BET specific surface area is based on the N2SA value determined by the BET method according to ASTM D3037-93.

[0156] Relative to 100 parts by weight of rubber component, the silica content is preferably 30 parts by weight or more, more preferably 40 parts by weight or more, and even more preferably 45 parts by weight or more. On the other hand, it is preferably 200 parts by weight or less, preferably 150 parts by weight or less, preferably 100 parts by weight or less, more preferably 80 parts by weight or less, 60 parts by weight or less, and even more preferably 55 parts by weight or less.

[0157] Examples of silica include dry silica (anhydrous silica) and wet silica (hydrated silica). Among these, wet silica is preferred because it contains more silanol groups.

[0158] As commodities, for example, products from Degussa Corporation, RHODIA Corporation, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., and Tokuyama Co., Ltd. can be used.

[0159] (ii) Silane coupling agents

[0160] As mentioned above, when using silica, it is preferable to use it in conjunction with a silane coupling agent. There are no particular limitations on the silane coupling agent; examples 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, and 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-trimethoxysilane Sulfide systems including propyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; thiol-based compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and NXT and NXT-Z manufactured by Momentive; and vinyltriethoxysilane. Vinyl derivatives such as alkanes and vinyltrimethoxysilanes; amino derivatives such as 3-aminopropyltriethoxysilanes and 3-aminopropyltrimethoxysilanes; epoxypropoxy derivatives such as γ-epoxypropoxypropyltriethoxysilanes and γ-epoxypropoxypropyltrimethoxysilanes; nitro derivatives such as 3-nitropropyltrimethoxysilanes and 3-nitropropyltriethoxysilanes; and chlorine derivatives such as 3-chloropropyltrimethoxysilanes and 3-chloropropyltriethoxysilanes. These can be used alone or in combination of two or more.

[0161] As silane coupling agents, products from companies such as Degussa, Momentive, Shin-Etsu Silicon Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azmax Co., Ltd., and Toray Dow Corning Co., Ltd. can be used.

[0162] The content of the silane coupling agent, relative to 100 parts by weight of silicon dioxide, is preferably greater than 3 parts by weight, more preferably greater than 5 parts by weight, even more preferably greater than 7 parts by weight, and even more preferably greater than 9 parts by weight. On the other hand, it is preferably less than 15 parts by weight, more preferably less than 13 parts by weight, and even more preferably less than 11 parts by weight.

[0163] (iii) Carbon black

[0164] The rubber composition preferably contains carbon black, if necessary. The carbon black content, relative to 100 parts by weight of the rubber component, is preferably 2 parts by weight or more, more preferably 3 parts by weight or more. On the other hand, it is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, and even more preferably 5 parts by weight or less.

[0165] As for carbon black, there are no particular limitations. Examples include furnace blacks (furnace blacks) such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF; acetylene black; thermal cracking blacks such as FT and MT; and channel blacks such as EPC, MPC, and CC. These can be used individually or in combination with two or more.

[0166] The nitrogen adsorption specific surface area (N2SA) of carbon black, for example, is greater than 30 m². 2 / g, less than 250m 2 / g. Dibutyl phthalate (DBP) absorption of carbon black, for example, greater than 50 ml / 100g and less than 250 ml / 100g. Additionally, the nitrogen adsorption specific surface area of ​​carbon black was determined based on ASTM D4820-93, and the DBP absorption was determined based on ASTM D2414-93.

[0167] Specifically, as carbon black, there are no particular limitations; N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc., can be used. As commercial products, for example, products from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Corporation, Shin-Nippon Chemical Carbon Co., Ltd., Columbia Carbon Black Co., Ltd., etc., can be used. These can be used individually or in combination of two or more.

[0168] (iv) Other fillers

[0169] In addition to 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, and mica. The content of these fillers relative to 100 parts by weight of the rubber component is, for example, greater than 0.1 parts by weight and less than 200 parts by weight.

[0170] ② Curing resin components

[0171] The rubber composition may, if necessary, contain curable resin components such as modified resorcinol resin or modified phenolic resin. This improves the rigidity of the rubber composition, resulting in good handling stability at high speeds.

[0172] Specifically, as a modified resorcinol resin, for example, SUMIKANOL620 (modified resorcinol resin) manufactured by Taoka Chemical Industry Co., Ltd. can be cited as an example, and as a modified phenolic resin, PR12686 (cashew oil modified phenolic resin) manufactured by Sumitomo Bakelite Co., Ltd. can be cited as an example.

[0173] The content of the curable resin component relative to 100 parts by weight of the rubber component is preferably 1 part by weight or more, more preferably 2 parts by weight or more, from the viewpoint of sufficiently improving the complex modulus of elasticity. On the other hand, from the viewpoint of maintaining the breaking strength, it is preferably 10 parts by weight or less, more preferably 8 parts by weight or less.

[0174] When using modified resorcinol resin, it is preferable to use a methylene donor as a curing agent. Examples of methylene donors include hexamethylenetetramine (HMT), hexamethoxyhydroxymethyl melamine (HMMM), and hexamethylol melamine pentamethyl ether (HMMPME), etc., preferably containing, for example, 5 parts by weight or more, up to about 15 parts by weight, relative to 100 parts by weight of the curable resin component. If the amount is too small, sufficient complex modulus of elasticity may not be obtained. On the other hand, if the amount is too large, the viscosity of the rubber increases, and processability deteriorates.

[0175] Specifically, as a methylene donor, for example, SUMIKANOL 507 manufactured by Taoka Chemical Industry Co., Ltd. can be used.

[0176] ③ Plasticizer components

[0177] The rubber composition, as a component that softens the rubber, may also contain oil (containing filling oil), liquid rubber, and resin as a plasticizer. Furthermore, the plasticizer component can be a component extracted from vulcanized rubber using acetone. The total content of the plasticizer component, relative to 100 parts by weight of the rubber component, is preferably greater than 5 parts by weight, more preferably greater than 10 parts by weight. On the other hand, it is preferably less than 70 parts by weight, more preferably less than 50 parts by weight, and even more preferably 30 parts by weight. In addition, the oil content also includes the amount of oil contained in the rubber (oil-extended rubber).

[0178] (i)Oil

[0179] Examples of oils include, for example, mineral oils (commonly referred to as processing oils), vegetable oils, or mixtures thereof. Mineral oils (processing oils) can include, for example, paraffin-based processing oils, aromatic processing oils, naphthenic processing oils, etc. Vegetable oils include, for example, castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, peanut oil, rosin, pine resin, pine oil, pine nuts, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, olive oil, sunflower seed oil, palm kernel oil, tea oil, jojoba oil, macadamia nut oil, tung oil, etc. These can be used alone or in combination of two or more.

[0180] Specifically, as a processing oil (mineral oil), products from companies such as Idemitsu Kosan Co., Ltd., Sankyo Oil & Chemical Co., Ltd., Nippon Energy Co., Ltd., Olisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Showa Shell Oil Co., Ltd., and Fuji Kosan Co., Ltd. can be used.

[0181] (ii) Liquid rubber

[0182] Liquid rubber, as an example of a plasticizer, refers to a polymer that is liquid at room temperature (25°C) and can be extracted from vulcanized tires using acetone. Examples of liquid rubber include farnesene polymers (LFR), liquid diene polymers, and their respective hydrides.

[0183] Farnese polymers refer to polymers obtained by polymerizing farnese, possessing structural units based on farnese. Farnese contains isomers such as α-farnese ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecanetraene) and β-farnese (7,11-dimethyl-3-methylene-1,6,10-dodecanetriene).

[0184] Farnese polymers can be either homopolymers of farnese (farnese homopolymers) or copolymers of farnese and vinyl monomers (farnese-vinyl monomer copolymers).

[0185] 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).

[0186] The weight-average molecular weight (Mw) of polystyrene-based liquid diene polymers, determined by gel permeation chromatography (GPC), for example, greater than 1.0 × 10⁻⁶. 3 Less than 2.0×10 5 Additionally, in this specification, the Mw of the liquid diene polymer is a polystyrene equivalent determined by gel permeation chromatography (GPC).

[0187] The content of liquid rubber (total content of liquid farnesene polymers, liquid diene polymers, etc.) relative to 100 parts by mass of the rubber component is, for example, greater than 1 part by mass and less than 100 parts by mass.

[0188] As a liquid rubber, products such as those from Kuraray Co., Ltd. and Clayville Corporation can be used.

[0189] (iii) Resin composition

[0190] The resin component functions as an adhesive agent and can be solid or liquid at room temperature. Specific resin components include, for example, rosin-based resins, styrene-based resins, coumarone-based resins, terpene-based resins, C5 resins, C9 resins, C5C9 resins, acrylic resins, etc., and two or more types can be used in combination. The content of the resin component is greater than 2 parts by weight relative to 100 parts by weight of the rubber component, preferably less than 45 parts by weight, and more preferably less than 30 parts by weight.

[0191] Rosin-based resins are resins whose main component is rosin acid, obtained through the processing of rosin. These rosin-based resins (rosin derivatives) can be classified according to whether they are modified or not, into unmodified rosin and modified rosin derivatives. Examples of unmodified rosin include tall oil rosin, resin rosin, wood rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, and rosin modified by other chemical methods. Modified rosin derivatives are modified forms of unmodified rosin, and examples include rosin esters, unsaturated carboxylic acid-modified rosin derivatives, unsaturated carboxylic acid-modified rosin esters, rosin amide compounds, and rosin amine salts.

[0192] Styrene-based resins are polymers that use styrene monomers as structural monomers. Examples include polymers polymerized with styrene monomers as the main component (50% by mass or more). Specifically, this refers to homopolymers polymerized individually from 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.), copolymers copolymerized from two or more styrene monomers, and copolymers of styrene monomers and other monomers that can be copolymerized with them.

[0193] Other monomers mentioned above include acrylonitrile derivatives such as acrylonitrile and methacrylonitrile; unsaturated carboxylic acids such as acrylic acids and methacrylic acids; unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate; dienes such as chloroprene, butadiene, and isoprene; olefins such as 1-butene and 1-pentene; and α,β-unsaturated carboxylic acids or their anhydrides such as maleic anhydride.

[0194] Among coumarone-based resins, coumarone-indene resin is preferred. Coumarin-indene resin is a resin in which coumarone and indene are contained as monomeric components constituting the resin skeleton (main chain). Examples of monomeric components other than coumarone and indene contained in the skeleton include styrene, α-methylstyrene, methylindene, and vinyltoluene.

[0195] The content of coumarin indole resin relative to 100 parts by weight of rubber component is, for example, greater than 1.0 parts by weight and less than 50.0 parts by weight.

[0196] The hydroxyl value (OH value) of coumarin indene resin is, for example, greater than 15 mg KOH / g and less than 150 mg KOH / g. Additionally, the OH value refers to the amount of potassium hydroxide required, expressed in milligrams, to neutralize the acetic acid bonded to the hydroxyl groups when 1 g of resin is acetylated, determined by potentiometric titration (JIS K 0070:1992).

[0197] The softening point of coumarin indene resin is, for example, greater than 30°C and less than 160°C. Furthermore, the softening point is determined using a ring-and-ball softening point measuring device, based on the temperature at which the ball falls. This is in accordance with JIS K 6220-1:2001.

[0198] Examples of terpene-based resins include polyterpenes, terpene phenols, and aromatic modified terpene resins. Polyterpenes are resins obtained by polymerizing terpene compounds and their hydrides. Terpene compounds are those with the structure (C5H8). n Hydrocarbons and their oxygen-containing derivatives, represented by their composition, are classified as monoterpenes (C6N). 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 Compounds with terpenes as their basic skeleton include, for example, α-pinene, β-pinene, dipentene, limonene, geraniol, allocirrhene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol, etc.

[0199] As polyterpenes, in addition to terpene resins such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, and β-pinene / limonene resin, which are derived from the aforementioned terpene compounds, examples can also include hydrogenated terpene resins obtained by hydrogenation treatment of these terpene resins. As terpene phenols, examples can include resins copolymerized from the aforementioned terpene compounds and phenolic compounds, as well as resins that have undergone hydrogenation treatment; specifically, examples can include resins condensed from the aforementioned terpene compounds, phenolic compounds, and formalin. Furthermore, examples of phenolic compounds include, for example, phenol, bisphenol A, cresol, and xylenol. As aromatic-modified terpene resins, examples can include resins obtained by modifying terpene resins with aromatic compounds, as well as resins that have undergone hydrogenation treatment. Furthermore, as aromatic compounds, there are no particular limitations as long as they have an aromatic ring. For example, examples include phenolic compounds such as phenol, alkylphenol, alkoxyphenol, and phenol with an unsaturated hydrocarbon group; naphthol compounds such as naphthol, alkylnaphthol, alkoxynaphthol, and naphthol with an unsaturated hydrocarbon group; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and styrene with an unsaturated hydrocarbon group; coumarone, indene, etc.

[0200] "C5 resin" refers to resin obtained by polymerizing C5 fractions. Examples of C5 fractions include petroleum fractions with 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, and isoprene. Dicyclopentadiene resin (DCPD resin) is suitable as a C5-based petroleum resin.

[0201] "C9 resin" refers to resin obtained by polymerizing C9 fractions, or hydrogenated or modified versions of these fractions. Examples of C9 fractions include petroleum fractions with 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specific examples include coumarone-indene resin, coumarone resin, indene resin, and aromatic vinyl resins. As aromatic vinyl resins, homopolymers of α-methylstyrene or styrene, or copolymers of α-methylstyrene and styrene, are preferred for economic, easy-to-process, and exothermic reasons; copolymers of α-methylstyrene and styrene are more preferred. For example, products sold by Kraton Corporation, Eastman Chemical Company, etc., can be used as aromatic vinyl resins.

[0202] "C5C9 resin" refers to a resin obtained by copolymerizing the aforementioned C5 fraction and the aforementioned C9 fraction, or it may be a hydrogenated or modified version of these. Examples of C5 and C9 fractions include the aforementioned petroleum fractions. For example, products sold by companies such as Tosoh Corporation and Luhua Corporation can be used as C5C9 resin.

[0203] There are no particular limitations on acrylic resins; for example, solvent-free acrylic resins can be used.

[0204] Solvent-free acrylic resins include (meth)acrylic resins (polymers) synthesized via high-temperature continuous polymerization (high-temperature continuous bulk polymerization) without using polymerization initiators, chain transfer agents, organic solvents, etc., as byproducts (as described in US Patent No. 4,414,370, Japanese Patent Application Publication No. 59-6207, Japanese Patent Application Publication No. 5-58005, Japanese Patent Application Publication No. 1-313522, US Patent No. 5,010,166, and the Toa Synthetic Research Annual Report TREND2000 No. 3, pp. 42-45). In this invention, (meth)acrylic acid refers to both methacrylic acid and acrylic acid.

[0205] Examples of monomeric components constituting the above-mentioned acrylic resins include (meth)acrylic acid, (meth)acrylates (alkyl esters, aryl esters, aralkyl esters, etc.), (meth)acrylamide, and (meth)acrylamide derivatives.

[0206] In addition, aromatic ethylene compounds such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene can also be used as monomer components constituting the above-mentioned acrylic resins, together with (meth)acrylic acid and (meth)acrylic acid derivatives.

[0207] The aforementioned acrylic resin can be a resin composed solely of (meth)acrylic acid, or a resin that also contains components other than (meth)acrylic acid as constituent elements. Furthermore, the aforementioned acrylic resin may also contain hydroxyl, carboxyl, or silanol groups, etc.

[0208] As a resin component, products from companies such as Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Co., Ltd., Rutgers Chemicals Co., Ltd., BASF Co., Ltd., Arizona Chemical Company, Nippon Paint Co., Ltd., Nippon Shokubai Co., Ltd., JX Energy Co., Ltd., Arakawa Chemical Industry Co., Ltd., Taoka Chemical Industry Co., Ltd., etc. can be used.

[0209] ④ Anti-aging agents

[0210] The rubber composition preferably contains an anti-aging agent. The content of the anti-aging agent relative to 100 parts by weight of the rubber component is, for example, greater than 1 part by weight and less than 10 parts by weight.

[0211] Examples of anti-aging agents include, for instance, naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octyl diphenylamine and 4,4′-bis(α,α′-dimethylbenzyl)diphenylamine; p-phenylenediamine-based anti-aging agents such as N-isopropyl-N′-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, and N,N′-di-2-naphthyl-p-phenylenediamine; quinoline-based anti-aging agents such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based anti-aging agents such as 2,6-di-t-butyl-4-methylphenol and styrylated phenol; and bis, tri, and polyphenol-based anti-aging agents such as tetra-[methylene-3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate]methane. These can be used alone or in combination of two or more.

[0212] In addition, as anti-aging agents, products from companies such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi New Chemical Industry Co., Ltd., and Flexis Co., Ltd. can be used.

[0213] ⑤ Stearic acid

[0214] The rubber composition may also contain stearic acid. The stearic acid content, relative to 100 parts by weight of the rubber component, is, for example, greater than 0.5 parts by weight and less than 10.0 parts by weight. As stearic acid, existing known products can be used, such as products from Nippon Oil Co., Ltd., NOF Co., Ltd., Kao Corporation, Fujifilm, Kojun Pharmaceutical Co., Ltd., Chiba Fatty Acid Co., Ltd., etc.

[0215] ⑥ Zinc oxide

[0216] The rubber composition may also contain zinc oxide. The zinc oxide content, relative to 100 parts by weight of the rubber component, is, for example, greater than 0.5 parts by weight and less than 15 parts by weight. As zinc oxide, existing known substances can be used, for example, products from Mitsui Metal Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Technology Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc.

[0217] ⑦ Crosslinking agents and vulcanization accelerators

[0218] The rubber composition preferably contains a crosslinking agent such as sulfur. The content of the crosslinking agent relative to 100 parts by weight of the rubber component is, for example, greater than 0.1 parts by weight and less than 10.0 parts by weight.

[0219] Examples of sulfur used in the rubber industry include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, and soluble sulfur. These can be used alone or in combination of two or more.

[0220] In addition, as sulfur, products from companies such as Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Co., Ltd., Nippon Dry Distillation Co., Ltd., and Hosoi Chemical Industry Co., Ltd. can be used.

[0221] Examples of crosslinking agents other than sulfur include sulfur-containing vulcanizing agents such as Tackirol V200 manufactured by Taoka Chemical Industry Co., Ltd., DURA Link HTS (sodium 1,6-hexamethylene-dithiosulfate dihydrate) manufactured by Flexis Corporation, KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyl dithio)hexane) manufactured by Lanxess Corporation, and organic peroxides such as dicumyl peroxide.

[0222] The rubber composition preferably contains a vulcanization accelerator. The content of the vulcanization accelerator relative to 100 parts by weight of the rubber component is, for example, greater than 0.3 parts by weight and less than 10.0 parts by weight.

[0223] Examples of vulcanization accelerators include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazole disulfide, and N-cyclohexyl-2-benzothiazole sulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetra(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazole sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, di-o-toluidine, and o-toluylbiguanidine. These can be used alone or in combination of two or more.

[0224] ⑧ Other

[0225] In addition to the components mentioned above, the rubber composition may further contain additives commonly used in the tire industry, such as fatty acid metal salts, carboxylic acid metal salts, organic peroxides, and reversion (vulcanization reversion) inhibitors. The content of these additives relative to 100 parts by weight of the rubber component is, for example, greater than 0.1 parts by weight and less than 200 parts by weight.

[0226] (2) Preparation of rubber composition

[0227] The rubber composition described above can be manufactured by a conventional method, for example, including: a basic mixing step of mixing rubber components with fillers such as silica and carbon black, and a final mixing step of mixing the mixture obtained from the basic mixing step with a crosslinking agent.

[0228] Mixing can be done using known (closed) mixing machines such as Banbury internal mixers, kneaders, and open mills.

[0229] The mixing temperature in the basic mixing process is, for example, greater than 50°C and less than 200°C, and the mixing time is, for example, greater than 30 seconds and less than 30 minutes. In addition to the above-mentioned components, if necessary, appropriate additives used in the existing rubber industry may be added during the basic mixing process, such as softeners such as oils, stearic acid, zinc oxide, anti-aging agents, waxes, vulcanization accelerators, etc.

[0230] The final mixing process involves mixing the compound obtained from the basic mixing process with a crosslinking agent. The mixing temperature in the final mixing process is, for example, above room temperature and below 80°C, and the mixing time is, for example, above 1 minute and below 15 minutes. In addition to the above-mentioned components, vulcanization accelerators, zinc oxide, etc., may be added appropriately if necessary during the final mixing process.

[0231] (3) Manufacturing of the tread

[0232] The tread can be manufactured by molding the rubber composition obtained above into a predetermined shape. Furthermore, in the case of multi-layered treads such as the crown and base layers, the above-mentioned rubber composition is used as the outermost layer.

[0233] 2. Manufacturing of belt layer components

[0234] The belt layer component can be manufactured by attaching a known coating rubber composition to both sides of reinforcing cords (monofilament cords such as steel wire cords) arranged side by side at specified intervals (50 cords / 5cm or more).

[0235] 3. Tire manufacturing

[0236] The tire involved in this embodiment can be manufactured as an uncured tire by molding the tread and belt layer components obtained above together with other tire components on a tire forming machine using conventional methods.

[0237] Specifically, an uncured tire is manufactured by winding the inner liner (which ensures the tire's airtightness), the carcass (which can withstand the load, impact, and inflation pressure of the tire), and the belt layer (which strengthens the carcass and improves the tread rigidity) onto a forming drum. The two ends of the carcass are fixed to the two side edges, and a bead portion (which serves to fix the tire to the rim) is arranged. After being formed into a ring shape, the tread is attached to the center of the outer periphery, and the sidewall is attached to the radially outer side to form the sidewall portion.

[0238] Furthermore, as described above, from the viewpoint of improving the restraining force relative to the tread during driving and easily suppressing the growth of the outer diameter, it is preferable that at least two belt layers are provided in this embodiment to form a belt layer component. In this case, the average distance D (mm) between the belt layers in the tread of the vulcanized tire is preferably 0.6 mm or less. In addition, the angle formed by each belt layer in the tread in the tire circumferential direction is preferably 65° or less.

[0239] Furthermore, the angle of the steel cord mentioned above is the angle of the steel cord relative to the tire circumference when the tire is not filled with air. This can be confirmed by peeling off the tread from the outside of the tire in the radial direction.

[0240] The uncured tires are then heated and pressurized in a vulcanizing machine to obtain tires. The vulcanization process can be carried out using known vulcanization methods. For example, the vulcanization temperature is greater than 120°C and less than 200°C, and the vulcanization time is greater than 5 minutes and less than 15 minutes.

[0241] When a tire is mounted on a standard rim and its cross-sectional width Wt (mm) and outer diameter Dt (mm) satisfy the following formula at an internal pressure of 250 kPa, it exhibits excellent low rolling resistance and is therefore preferred.

[0242] 1600≤(Dt 2 (×π / 4) / Wt≤2827.4

[0243] Furthermore, as specific tires preferably applicable to this invention, examples include tires with sizes 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.

[0244] In this embodiment, among tires classified as automobile tires, truck / bus tires, motorcycle tires, etc., automobile tires are preferred, that is, tires with a maximum load capacity of 1000 kg or less that are installed on four-wheeled vehicles. By satisfying (Equation 1), this can make a better contribution to solving the problem of providing a pneumatic tire with excellent handling stability and durability at high speeds in this invention.

[0245] There is no particular limitation on the maximum load capacity as long as it is below 1000 kg. However, since the tire weight tends to increase with the increase of the maximum load capacity, the impact transmitted to the tire tends to increase as well. Therefore, it is preferable to be below 900 kg, more preferably below 800 kg, and even more preferably below 700 kg.

[0246] 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, and even more preferably 12 kg or less, 10 kg or less, or 8 kg or less.

[0247]

Example

[0248] The present invention will be further described in detail below through examples.

[0249] [Experiment 1]

[0250] In this experiment, tires with a size of 185 / 65R16 were manufactured and evaluated.

[0251] 1. Manufacturing of rubber compositions for tire treads

[0252] Initially, the manufacturing of rubber compositions for tire treads was carried out.

[0253] (1) Proportioning materials

[0254] First, prepare the ingredients in the proportions shown below.

[0255] (a) Rubber composition

[0256] ①NR: TSR20

[0257] ②SBR: Versalis' C2525 (solution polymerization SBR)

[0258] (Styrene content: 26% by mass, Vinyl content: 24% by mass)

[0259] ③BR: UBEPOL BR150B manufactured by Ube Industries, Ltd.

[0260] (cis: 97% by mass, trans: 2% by mass)

[0261] (b) Materials other than rubber components

[0262] ① Carbon black: Show black N220 manufactured by Cabot Corporation

[0263] (N2SA: 111m) 2 / g)

[0264] ②Silica: Ultra silica VN3 manufactured by Evonik Industries

[0265] (BET specific surface area: 165m²) 2 / g)

[0266] ③Silane coupling agent: Si69 manufactured by Degussa

[0267] (bis(3-triethoxysilylpropyl)tetrasulfide)

[0268] ④ Oil: H&R's VIVATEC NC500 (aromatic processing oil)

[0269] ⑤ Resin: Terpene styrene resin TO125 manufactured by Anhara Chemical Co., Ltd.

[0270] (Aromatic modified terpene resin)

[0271] ⑥ Zinc oxide: Zinc Hua No. 1 manufactured by Mitsui Metals Mining Co., Ltd.

[0272] ⑦ Anti-aging agent-1: Nocrack 6C manufactured by Ouchi Shinsei Chemical Co., Ltd.

[0273] (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine)

[0274] ⑧ Anti-aging agent-2: ANTAGE RD manufactured by Kawaguchi Chemical Industry Co., Ltd.

[0275] (2,2,4-Trimethyl-1,2-dihydroquinoline)

[0276] ⑨ Wax: Ozoace 0355 manufactured by Nippon Fine Wax Co., Ltd.

[0277] ⑩ Stearic acid: Stearic acid "Tsubaki" produced by Nippon Oil Co., Ltd.

[0278] Crosslinking agents and vulcanization accelerators

[0279] Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd.

[0280] Vulcanization accelerator-1: Noxeller CZ-G (CZ) manufactured by Ouchi Shinsei Chemical Co., Ltd.

[0281] (N-Cyclohexyl-2-benzothiazole sulfenamide)

[0282] Vulcanization accelerator-2: Noxeller D (DPG) manufactured by Ouchi Shinshin Chemical Industry Co., Ltd.

[0283] (1,3-Diphenylguanidine)

[0284] (2) Manufacturing of rubber compositions

[0285] According to the proportions shown in Tables 1 and 2, sulfur and materials other than vulcanization accelerators were mixed at 150°C for 5 minutes using a Banbury internal mixer to obtain the compound. Furthermore, all proportions are parts by weight.

[0286] Then, sulfur and vulcanization accelerator are added to the obtained compound, and the mixture is mixed for 5 minutes at 80°C using a two-roll mill to obtain a rubber composition for tire tread.

[0287] 2. Tire manufacturing

[0288] First, the steel wire cords with the composition and outer diameter shown in Tables 1 and 2 are arranged in a cord density of 5cm as shown in Tables 1 and 2. Then, the previously obtained belt layer is covered on both sides with a rubber composition to make a belt layer component with a total thickness of "cord diameter (mm) + cord spacing × 2 (mm)".

[0289] Then, by interlacing the distances and angles shown in Tables 1 and 2, a belt layer with two belt layer components is formed. The tread component made using the above-mentioned tread rubber composition and other tire components are then bonded together to form an uncured tire. The tire is then vulcanized under pressure at 170°C for 10 minutes to produce the test tires shown in Tables 1 and 2 (outer diameter Dt: 646 mm, section width Wt: 189 mm, hypothetical volume V: 37429958 mm). 3 ).

[0290] In addition, among the test tires, the above (L) 80 The cross-sectional area of ​​the circumferential grooves is 0.5, and the total cross-sectional area of ​​the circumferential grooves is 22% of the cross-sectional area of ​​the tread. The total volume of the transverse grooves, including the lateral grooves with a width / depth of 0.65, is 3.5% of the tread volume.

[0291] 3. Parameter Calculation

[0292] Then, while measuring the distance T (mm) from the outermost surface of the tread layer to the outermost surface of the belt layer of each test tire, the tire weight WT (kg) was measured, and the ratio (WT / WL) of the maximum load capacity WL (kg) calculated based on V was determined relative to WT. Simultaneously, rubber was cut from between the belt layers of each test tire to prepare viscoelasticity test pieces with a length of 40 mm and a width of 4 mm. Using the EPLEXOR series from GABO, the complex elastic modulus E was measured under the following conditions: temperature: 30°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10 Hz, deformation mode: tensile. ＊ (MPa), calculate (E) ＊The results are shown in Table 1 and Table 2.

[0293] 4. Performance evaluation test

[0294] (1) Evaluation of handling stability

[0295] All test tires were installed on all wheels of the vehicle (a domestically produced FF car with a 2000cc engine). After inflating the tires to an internal pressure of 250 kPa, the vehicle was driven at 120 km / h on a dry test track. The handling performance was evaluated by the drivers on a 5-stage scale (1 to 5). The total score from the evaluations of 20 drivers was then calculated.

[0296] Then, the results from Comparative Examples 1-10 are taken as 100 and exponentialized according to the following formula to evaluate handling stability at high speeds. The larger the value, the better the handling stability at high speeds.

[0297] Handling stability = [(Results of the test tires) / (Results of Comparative Examples 1-10)] × 100

[0298] (2) Evaluation of durability performance

[0299] All test tires were installed on all wheels of the vehicle (a domestically produced FF car with a 2000cc engine). After inflating the tires to an internal pressure of 250 kPa, the vehicle was driven 10 times at 50 km / h on a dry test track under overload conditions. Then, it was driven repeatedly over uneven surfaces at 80 km / h. The vehicle was then driven around the track again at 50 km / h, and the speed was gradually increased to measure the speed at which the driver felt any abnormality.

[0300] Then, the results from Comparative Examples 1-10 are taken as 100 and exponentialized according to the following formula to evaluate durability performance relatively. The larger the value, the better the durability.

[0301] Durability = [(Results of the test tires) / (Results of Comparative Examples 1-10)] × 100

[0302] (3) Comprehensive evaluation

[0303] The sum of the evaluation results of (1) and (2) above shall be used as the comprehensive evaluation.

[0304] (4) Evaluation Results

[0305] The evaluation results are shown in Table 1 and Table 2. In addition, in the tables, "1×1" indicates a single filament and "1×2" indicates a twisted yarn made of two single filaments twisted together.

[0306] Table 1

[0307]

[0308] Table 2

[0309]

[0310] [Experiment 2]

[0311] In this experiment, a tire with a size of 205 / 55R16 was manufactured (outer diameter Dt: 632mm, cross-sectional width Wt: 214mm, hypothetical volume V: 39373809mm²). 3 ), and conduct an evaluation.

[0312] The test tires shown in Tables 3 and 4 were manufactured in the same manner as in Experiment 1, and the parameters were calculated in the same way. Then, performance evaluation tests were conducted and evaluated in the same manner. Furthermore, for handling stability, the results from Comparative Examples 2-10 were set to 100, and for durability performance, the results from Comparative Examples 2-10 were also set to 100 for evaluation. The evaluation results are shown in Tables 3 and 4.

[0313] Table 3

[0314]

[0315] Table 4

[0316]

[0317] [Experiment 3]

[0318] In this experiment, a tire with a size of 215 / 55R17 was manufactured (outer diameter Dt: 668mm, cross-sectional width Wt: 226mm, hypothetical volume V: 46109661mm). 3 ), and conduct an evaluation.

[0319] After manufacturing the test tires shown in Tables 5 and 6 in the same manner as in Experiment 1, the parameters were obtained in the same way. Then, the performance evaluation tests were conducted and evaluated in the same manner. In addition, for handling stability, the results in Comparative Examples 3-10 were set to 100, and for durability performance, the results in Comparative Examples 3-10 were also set to 100 for evaluation. The evaluation results are shown in Tables 5 and 6.

[0320] Table 5

[0321]

[0322] Table 6

[0323]

[0324] Based on the results of experiments 1 to 3 (Tables 1 to 6), for tires of any size, when the reinforcing cords in the belt layer are composed of cords made of monofilaments arranged in a pattern of 50 cords / 5cm or more, and when the above (Equation 1) is satisfied, a pneumatic tire with excellent handling stability and durability at high speeds can be obtained.

[0325] Then, by controlling the above (Equation 2) and appropriately controlling the outer diameter of the cord, a pneumatic tire with even better handling stability and durability at high speeds can be obtained.

[0326] The present invention has been described above based on the embodiments, but the present invention is not limited to the above embodiments. Various modifications can be made to the above embodiments within the same and equivalent scope as the present invention.

Claims

1. A pneumatic tire, characterized in that, It has a belt layer and a tread. The tread portion is positioned radially outward of the belt layer of the tire. The reinforcing cords in the belt layer are composed of monofilament cords arranged at a rate of 50 cords per 5cm or more in the width direction of the tire, on the radial cross-section of the belt layer. The maximum load capacity WL and the weight WT of the tire, both in kg, satisfy the following formula: (WT / WL)≤0.0140… Formula 1 The maximum load capacity WL is: a value calculated using the following two formulas, with the tire mounted on a standard rim and the tire section width Wt, tire section height Ht, and tire outer diameter Dt under no-load conditions and with the internal pressure set to 250 kPa. The units for Wt, Ht, and Dt are mm. V(mm 3 )={(Dt / 2) 2 -(Dt / 2-Ht) 2 }×π×Wt WL(kg)=0.000011×V+100 The complex elastic modulus E, measured in MPa, of the tread rubber composition forming the outermost contact surface of the tread portion, under the following conditions: temperature: 30°C, initial strain: 5%, dynamic strain: ±1%, frequency: 10Hz, and deformation mode: tensile. ＊ The distance T, in mm, from the outermost surface of the tread portion to the outermost surface of the belt layer satisfies the following equation 2: (E) ＊ ×T)≥30 …… Equation 2.

2. The pneumatic tire according to claim 1, characterized in that, The outer diameter of the cord composed of monofilaments is 0.1 to 0.5 mm.

3. The pneumatic tire according to claim 1 or 2, characterized in that, The tread section has multiple circumferential grooves that extend continuously along the tire circumference. The total cross-sectional area of ​​the multiple circumferential grooves is 10% to 30% of the cross-sectional area of ​​the tread.

4. The pneumatic tire according to claim 1 or 2, characterized in that, The tread section has multiple transverse grooves extending along the tire axial direction. The total volume of the multiple transverse grooves is 2.0 to 5.0% of the volume of the tread area.

5. The pneumatic tire according to claim 1 or 2, characterized in that, The belt layer has at least two layers. In at least one of the groups of belt layers that are adjacent in the radial direction of the tire, The average distance D (mm) between each belt layer in the tread area is less than 0.6 mm.

6. The pneumatic tire according to claim 1 or 2, characterized in that, The belt layer has at least two layers. In at least one of the groups of belt layers that are adjacent in the radial direction of the tire, The angle between each belt layer in the tread portion and the tire circumferential direction is less than 65°.

7. The pneumatic tire according to claim 1 or 2, characterized in that, The tread has circumferential grooves that extend continuously along the tire's circumference. The groove width L at 80% of the maximum depth of the circumferential groove 80 The ratio of L0 to the width L0 of the circumferential groove on the contact surface of the tread surface, L 80 / L0 is 0.3 to 0.

7.

8. The pneumatic tire according to claim 1 or 2, characterized in that, The cross-sectional width Wt (mm) of the tire is less than 200mm.

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