Pneumatic tire

Abstract

A pneumatic tire is provided in which uneven wear of the tread portion during high-speed driving is effectively suppressed, and it exhibits good durability. This pneumatic tire has a sidewall and a bead portion, wherein: in a radial section, the distance Ha from the bead baseline to the outer side of the bead portion in the width direction is greater than the distance Hb to the inner side in the width direction; the composite modulus E* of the sidewall is measured under conditions of 70°C, a frequency of 10Hz, an initial strain of 5%, and a dynamic strain rate of 1%. S The composite modulus E* is less than that at the edge. C Furthermore, the following equations (1) and (2) must be satisfied, where Wt is the cross-sectional width of the tire when it is mounted on a standardized rim and filled with air to an internal pressure of 250 kPa, Dt is the outer diameter, and the hypothetical volume V is the volume of space occupied by the tire. 1600 ≤ (Dt) 2 ×π / 4) / Wt≦2827.4···Equation 1[(V+1.5×10 7 ) / Wt]≦2.88×10 5 Equation 2

Description

Technical Field

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

[0002] In recent years, from the perspective of increasing concerns about environmental issues and economic benefits, there has been an increasing demand for fuel efficiency in automobiles, and there has also been a strong demand for improved fuel efficiency in pneumatic tires (hereinafter referred to as "tires") mounted on automobiles.

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

[0004] Therefore, conventionally, it has been proposed to reduce rolling resistance by designing the formulation of a rubber composition constituting a tire tread portion (for example, Patent Documents 1 to 4).

[0005] [Prior art literature]

[0006] [Patent Document]

[0007] [Patent Document 1] JP2018-178034A

[0008] [Patent Document 2] JP2019-089911A

[0009] [Patent Document 3] WO2018 / 186367A

[0010] [Patent Document 4] JP2019-206643A Summary of the Invention

[0011] [Problems to be solved by the present invention]

[0012] However, although the tire manufactured by the above-mentioned conventional technology can reduce rolling resistance, the tread portion tends to suffer uneven wear during high-speed running, and it cannot be said that the durability performance is sufficient.

[0013] Therefore, an object of the present invention is to provide a pneumatic tire in which uneven wear of a tread portion during high-speed running is sufficiently suppressed and which has excellent durability performance.

[0014] [Methods of solving the problem]

[0015] The present inventors have diligently studied solutions to the above problems and have found that the above problems can be solved by the following configuration.

[0016] The present invention is:

[0017] A pneumatic tire having side portions and bead portions, wherein:

[0018] Ha>Hb, where, in a meridian cross section, the distance from the bead base line to the outer side of the bead portion at the interface between the side portion and the bead portion in the width direction is Ha (mm), and the distance to the inner side in the width direction is Hb (mm);

[0019] E* S <E* C , where the composite elastic modulus of the side measured at 70°C, a frequency of 10 Hz, an initial strain of 5% and a dynamic strain rate of 1% is E* S (MPa), the composite elastic modulus of the edge is E* C (MPa); and

[0020] The tire satisfies the following equations 1 and 2:

[0021] 1600≤(Dt 2 ×π / 4) / Wt≦2827.4···Equation 1

[0022] [(V+1.5×10 7 ) / Wt]≦2.88×10 5 Formula 2,

[0023] Wherein, when the tire is mounted on a standardized rim and the internal pressure is 250 kPa, the cross-sectional width of the tire is Wt (mm), the outer diameter is Dt (mm), and the volume of the space occupied by the tire is the imaginary volume V (mm 3 ).

[0024] [Effects of the Invention]

[0025] According to the present invention, it is possible to provide a pneumatic tire in which uneven wear of a tread portion during high-speed running is sufficiently suppressed and which has excellent durability performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] [ Figure 1 ] is a partial meridian cross-sectional view of a pneumatic tire according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] [1] Features of the tire of the present invention

[0028] First, the features of the tire of the present invention will be described.

[0029] 1. Overview

[0030] The tire of the present invention is a pneumatic tire having side portions provided on side surfaces and bead portions provided in a bead portion region contacting a rim flange, and has the following features.

[0031] First, the tire of the present invention is characterized in that Ha>Hb, wherein, in the meridian section, the distance from the bead baseline to the widthwise outer side of the edge portion at the joint surface between the side portion and the edge portion is Ha (mm), and the distance to the widthwise inner side is Hb (mm).

[0032] Next, the tire of the present invention is characterized by E* S <E* C , where the composite elastic modulus of the side measured at 70°C, a frequency of 10 Hz, an initial strain of 5% and a dynamic strain rate of 1% is E* S (MPa), the composite elastic modulus of the edge is E* C (MPa) Here, each E* is a value measured using a viscoelasticity measuring device such as "Eplexor (registered trademark)" manufactured by GABO.

[0033] Furthermore, the tire of the present invention is characterized by satisfying the following equations 1 and 2:

[0034] 1600≤(Dt 2 ×π / 4) / Wt≦2827.4···Equation 1

[0035] [(V+1.5×10 7 ) / Wt]≦2.88×10 5 Formula 2

[0036] Wherein, when the tire is mounted on a standardized rim and the internal pressure is 250 kPa (the normal internal pressure of a pneumatic tire for a passenger car), the cross-sectional width of the tire is Wt (mm), the outer diameter is Dt (mm), and the volume of the space occupied by the tire is the virtual volume V (mm). 3 ).

[0037] With these features, it is possible to provide a pneumatic tire in which not only rolling resistance is reduced but also uneven wear of the tread portion during high-speed running is sufficiently suppressed and durability performance is excellent.

[0038] In the above description, a "standardized rim" refers to a rim defined for each tire in a standard system, including the standards to which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Association), it is a standardized rim of applicable size described in the "JATMA Year Book," in the case of ERTO (European Tire and Rim Technical Organization), it is a "Measuring Rim" described in the "Standards Manual," and in the case of TRA (Tire and Rim Association Inc.), it is a "Design Rim" described in the "Year Book." For tires not specified in the standard, it refers to a rim that can be assembled and maintain internal pressure, that is, a rim that does not cause air leakage between the rim and the tire, and has the smallest rim diameter, followed by the narrowest rim width.

[0039] Furthermore, the tire's outer diameter Dt refers to the outer diameter of the tire when mounted on a standardized rim, at an internal pressure of 250 kPa, and in an unloaded state. The tire's cross-sectional width Wt (mm) refers to the width of the tire when mounted on a standardized rim, at an internal pressure of 250 kPa, and in an unloaded state. It is the straight-line distance between the sidewalls (total tire width), excluding any sidewall patterns, text, and the like. Ha and Hb are values ​​measured for tires mounted on standardized rims, at an internal pressure of 250 kPa and with no load.

[0040] Specifically, the tire's virtual volume V (mm) can be calculated using the following formula based on the tire's outer diameter Dt (mm), tire cross-section height Ht (mm) (the distance from the bead bottom to the outermost surface of the tread, which is 1 / 2 of the difference between the tire's outer diameter and the nominal rim diameter), and tire cross-section width Wt (mm) when the tire is mounted on a standardized rim with an internal pressure of 250 kPa and no load applied. 3 ):

[0041] V=[(Dt / 2) 2 -{(Dt / 2)-Ht} 2 ]×π×Wt.

[0042] In the above description, "normalized internal pressure" refers to the air pressure specified for each tire by the above standards. For JATMA, this is the maximum air pressure; for TRA, it is the maximum value described in the "Tire Load Limits at Various Cold Inflation Pressures" table; and for ETRTO, it indicates "Inflation Pressure." For example, for pneumatic tires for passenger cars, this is "250 kPa."

[0043] 2. Mechanism of Effect Expression in the Tire of the Present Invention

[0044] The mechanism by which the tire of the present invention exhibits its effects is presumed to be a mechanism that not only reduces rolling resistance but also sufficiently suppresses uneven wear of the tread portion during high-speed running and further exhibits excellent durability performance.

[0045] As described above, in the tire of the present invention, the cross-sectional width Wt (mm) and the outer diameter Dt (mm) of the tire are preferably such that 1600≦(Dt 2 ×π / 4) / Wt≦2827.4Equation 1.

[0046] By increasing the area of ​​the tire when viewed from the side relative to the tire's cross-sectional width Wt [(Dt / 2) 2 ×π)=(Dt 2 ×π / 4)] and satisfies the numerical range specified in Formula 1, it is considered that the repeatability of deformation per unit time is reduced, and therefore, the time available for heat exchange is increased, thereby improving the heat release performance of the side portion, and since the friction between the tread portion and the road surface can be reduced, low rolling resistance and improvement in durability can be achieved.

[0047] In Formula 1, it is more preferably 1700 or more, further preferably 1704 or more, further preferably 1731 or more, further preferably 1733 or more, further preferably 1737 or more, further preferably 1755 or more, further preferably 1758 or more, further preferably 1772 or more, further preferably 1781 or more, further preferably 1789 or more, further preferably 1805 or more, further preferably 1816 or more, further preferably 1822 or more, further preferably 1865 or more, further preferably 1870 or more, further preferably 1963.4 or more, further preferably 2014 or more, further preferably 2018 or more, further preferably 2021 or more, further preferably 2032 or more, further preferably 2045 or more, and further preferably 2107 or more.

[0048] However, such tires have a larger area when viewed from the side. In other words, as the outer diameter Dt increases, the centrifugal force acting on the entire tread increases during high-speed driving, promoting partial unevenness in the tire and often causing uneven wear. In particular, as driving speed increases, the centrifugal force also increases, making uneven wear more likely to occur.

[0049] Therefore, in the tire of the present invention, the virtual volume V (mm 3 ) and the cross-section width Wt (mm) should satisfy [(V+1.5×10 7 ) / Wt]≦2.88×10 5 Formula 2.

[0050] In this way, it is believed that by reducing the imaginary volume V of the tire according to the reduction of the tire cross-sectional width Wt and reducing the volume of the tire itself, the increase in outer diameter with the increase of centrifugal force can be suppressed, and the deformation of the tread part can be reduced, while the rolling resistance is reduced. As a result, not only heat generation can be reduced, but also the occurrence of uneven wear can be suppressed.

[0051] [(V+1.5×107) / Wt] is more preferably 2.87×10 5 Below, more preferably 2.85×10 5 Below, more preferably 2.77×10 5 Below, more preferably 2.61×10 5 Below, more preferably 2.55×10 5 Below, more preferably 2.50×10 5 Below, more preferably 2.49×10 5 Below, more preferably 2.42×10 5 Below, more preferably 2.27×10 5 Below, more preferably 2.24×10 5 Below, more preferably 2.21×10 5 Below, more preferably 2.19×10 5 Below, more preferably 2.18×10 5 Below, more preferably 2.17×10 5 Below, and further preferably 2.16×10 5 the following.

[0052] In this case, it is more preferable that [(V+2.0×10 7 ) / Wt]≦2.88×10 5 Formula 3. The above [(V+2.0×107) / Wt] is more preferably 2.83×10 5 Below, more preferably 2.80×10 5Below, more preferably 2.77×10 5 Below, more preferably 2.76×10 5 Below, more preferably 2.64×10 5 Below, more preferably 2.50×10 5 Below, more preferably 2.49×10 5 Below, more preferably 2.47×10 5 Below, more preferably 2.46×10 5 Below, more preferably 2.44×10 5 Below, and further preferably 2.41×10 5 the following.

[0053] Furthermore, it is more preferred that [(V+2.5×10 7 ) / Wt]≦2.88×10 5 Formula 4. The above [(V+2.5×10 7 ) / Wt] is more preferably 2.85×10 5 Below, more preferably 2.78×10 5 Below, more preferably 2.75×10 5 Below, more preferably 2.71×10 5 Below, more preferably 2.69×10 5 Below, more preferably 2.68×10 5 Below, and further preferably 2.66×10 5 the following.

[0054] Furthermore, in the tire of the present invention, the bead portion and the side portion are joined so that Ha>Hb and E* S <E* C , making the edge portion stiffer than the side portion. Therefore, it is believed that the load applied to the interface between the edge portion and the side portion during high-speed driving can be reduced, further suppressing uneven wear during high-speed driving. In this case, if the end of the side portion is covered by the end of the edge portion, the effect of further suppressing uneven wear during high-speed driving is more pronounced, which is preferred.

[0055] In the above case, the specific difference between Ha and Hb (Ha-Hb) is preferably 12 mm or more, more preferably 22 mm or more, further preferably 23 mm or more, and further preferably 35 mm or more. Furthermore, the specific difference between E*C and E*S (E*CE*S) is preferably 2.1 MPa or more, more preferably 2.7 MPa or more, further preferably 3.7 MPa or more, and further preferably 4.3 MPa or more.

[0056] [2] More preferred embodiments of the tire of the present invention

[0057] The tire of the present invention can achieve greater effects by adopting the following embodiments.

[0058] 1. Flatness

[0059] The tire of the present invention preferably has an aspect ratio of 40% or greater. This allows for increased side height and area, and further improves heat dissipation throughout the tire by reducing the contribution of heat generated by the tread. Consequently, a decrease in rigidity in the tread and sidewalls can be minimized, further suppressing the occurrence of uneven wear during high-speed driving.

[0060] When the internal pressure is 250 kPa, the above-mentioned aspect ratio (%) can be obtained by the following formula using the cross-sectional height Ht (mm) and the cross-sectional width Wt (mm) of the tire.

[0061] (Ht / Wt)×100(%)

[0062] The flatness is more preferably 41% or more, more preferably 45% or more, further preferably 47.5% or more, further preferably 49% or more, further preferably 50% or more, further preferably 52.5% or more, further preferably 53% or more, further preferably 55% or more, and further preferably 58% or more. There is no specific upper limit, but for example, it is 100% or less.

[0063] 2.E* S (MPa), E* C Relationship between (MPa) and Wt (mm)

[0064] Assuming that as the cross-sectional width Wt increases, the difference between the contact pressure of the tread center portion and the contact pressure of the tread shoulder portion tends to increase, and uneven wear is likely to occur. On the other hand, when the composite elastic modulus E* of the edge portion is C Greater than the composite elastic modulus E* of the side S When the edge portion with high rigidity can press the side portion with low rigidity, it is considered to be beneficial for suppressing the occurrence of uneven wear.

[0065] Considering that as the cross-sectional width Wt increases, the difference in the composite elastic modulus between the edge and the side can be increased, that is, E* C -E* S , to suppress uneven wear, so the study of E* C -E* S The relationship between (MPa) and Wt (mm). It was found that if (E* C -E* S) / Wt>0.04×10 -1 According to Formula 5, uneven wear can be effectively suppressed, which is preferable.

[0066] The above (E* C -E* S ) / Wt is more preferably 0.08×10 -1 More preferably, 0.09×10 -1 More than 0.10×10 -1 Preferably, more preferably 0.11×10 -1 More preferably, 0.12×10 -1 More preferably, 0.13×10 -1 More preferably, 0.14×10 -1 More than 0.15×10 -1 , more preferably 0.16×10 -1 More preferably, 0.18×10 -1 More preferably, 0.21×10 -1 More than 0.24×10 -1 above.

[0067] 3. Relationship between Ha (mm), Hb (mm), and Wt (mm)

[0068] As described above, as the cross-sectional width Wt increases, the difference between the contact pressure at the center of the tread and the contact pressure at the shoulder of the tread tends to increase, and it is presumed that uneven wear is more likely to occur. On the other hand, when Hb is greater than Ha, as described above, it is presumed that the load applied to the interface between the bead portion and the side portion during high-speed driving is reduced, thereby further suppressing uneven wear during high-speed driving. When the end of the side portion is covered by the end of the bead portion, the side portion can be pressed by the bead portion over a large area, and therefore, it is presumed that the effect of suppressing uneven wear during high-speed driving can be more significantly exhibited.

[0069] Therefore, the present inventors believed that uneven wear could be suppressed by increasing Ha-Hb as the cross-sectional width Wt increased, and studied the relationship between Ha, Hb, and Wt. It was found that if (Ha-Hb) / Wt>0.04 (Equation 7) was satisfied, uneven wear could be effectively suppressed, which is preferred.

[0070] The results show that the above (Ha-Hb) / Wt is more preferably 0.05 or more, further preferably 0.06 or more, further preferably 0.09 or more, further preferably greater than 0.10, further preferably 0.11 or more, further preferably 0.12 or more, further preferably greater than 0.15, further preferably 0.17 or more, and further preferably 0.20 or more.

[0071] Furthermore, in the tire of the present invention, the ratio of Ha and Hb to Ht is preferably 5% or more and 80% or less. And, from the comprehensive perspective of uneven wear performance and durability performance, E*C is preferably 6.1 MPa or more and 8.3 MPa or less. E* S It is preferably 2 MPa or more and 5 MPa or less, more preferably 4 MPa or less, and further preferably 3.5 MPa or less.

[0072] 4. Loss tangent of the side (tanδ)

[0073] In the tire of the present invention, the loss tangent (tan δ) of the side portion, measured under the conditions of 70°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%, is preferably 0.095 or less, more preferably 0.090 or less, further preferably 0.085 or less, further preferably 0.080 or less, further preferably 0.075 or less, further preferably 0.070 or less, and most preferably 0.065 or less. Therefore, it is believed that the heat release performance of the side portion can be further improved while the heat release performance of the side portion can be reduced.

[0074] Tan δ is measured on a piece of rubber cut from at least the radially outer side of the tire groove bottom, preferably from the radially outer side at half the depth of the deepest circumferential groove. Specifically, for example, the viscoelasticity measuring device "Eplexor (registered trademark)" manufactured by GABO can be used. Tan δ can also be measured simultaneously with the aforementioned E* measurement.

[0075] Then, when the thickness of the side portion measured at the maximum width position is Ts (mm), (tan δ × Ts) is preferably 0.40 or greater, more preferably 0.45 or greater, and further preferably 0.50 or greater. By controlling tan δ and Ts in this manner, it is believed that heat generation in the side portion can be appropriately controlled. A specific Ts is, for example, 1 to 20 mm.

[0076] 5. Tread grooves

[0077] The tire of the present invention has a circumferential groove extending continuously in the tire circumferential direction in the tread portion. The groove width L at a depth of 80% of the maximum depth of the circumferential groove is 80 The ratio of the circumferential groove width L0 on the ground contact surface of the tread portion (L 80The ratio (L / L) is preferably 0.3 to 0.7. This suppresses movement of the entire ground contact portion of the tread on its bottom surface, effectively suppressing uneven wear of the tread and improving durability during high-speed driving. This ratio is more preferably 0.35 to 0.65, further preferably 0.40 to 0.60, and particularly preferably 0.45 to 0.55.

[0078] The above L0 and L 80 The straight-line distance between the groove edges on the tread surface of the circumferential grooves of the tire tread (L0) and the minimum distance between the groove walls at the position where the groove depth is 80% (L0) are respectively referred to when the tire is mounted on a standardized rim, the internal pressure is 250kPa and no load is applied. 80 ). In short, they can be obtained by pressing the bead portion of a section with a width of 2-4 cm cut out in the radial direction according to the rim width.

[0079] It is preferred that multiple circumferential grooves be formed in the tread portion, with the total cross-sectional area of ​​the grooves being 10% to 30% of the cross-sectional area of ​​the tread portion. This is known to suppress movement of the tread portion, reduce uneven wear of the tread portion during high-speed driving, and improve durability. More preferred is 15 to 27%, further preferred is 18 to 25%, and particularly preferred is 21 to 23%.

[0080] The cross-sectional area of ​​a circumferential groove is the sum of the areas defined by the straight line connecting the ends of the circumferential groove and the groove wall, when the tire is mounted on a standardized rim and under an internal pressure of 250 kPa and in an unloaded state. Simply put, this area is achieved by compacting the bead section, which is cut radially into sections with a width of 2-4 cm, according to the rim width. Circumferential grooves can extend continuously in the tire's circumferential direction, and they also include nonlinear grooves such as herringbone grooves and wavy grooves.

[0081] Furthermore, it is preferred that a plurality of axially extending lateral grooves be formed in the tread portion, with the total volume of the plurality of lateral grooves being 2.0-5.0% of the tread portion volume. This is known to suppress tread movement, prevent uneven wear, and improve durability. A more preferred ratio is 2.2-4.0%, further preferred is 2.5-3.5%, and particularly preferred is 2.7-3.0%.

[0082] The volume of the lateral grooves mentioned above refers to the total volume consisting of the surface area connecting the ends of the lateral grooves and the groove wall, when the tire is mounted on a standardized rim, at an internal pressure of 250 kPa and in an unloaded state. Simply put, this volume can be calculated by calculating the volume of each lateral groove, multiplying it by the number of grooves, by cutting out radially 2-4 cm sections of the bead according to the rim width and compressing them. Furthermore, the area of ​​this section excluding the lateral grooves is calculated, multiplied by the outer diameter, and the difference between this calculated area and the volume of the lateral grooves is used to calculate the tread volume.

[0083] In order to suppress uneven wear of the tread portion and further improve durability, it is preferred that these lateral grooves have a (Gw / Gd) ratio (i.e., the ratio of groove width Gw to groove depth Gd) of 0.50 to 0.80. This ratio is more preferably 0.53 to 0.77, further preferably 0.55 to 0.75, and particularly preferably 0.60 to 0.70.

[0084] The groove width and groove depth of the lateral grooves are the maximum length of a straight line (perpendicular to the groove direction) connecting the two ends of the tread of the lateral groove and the maximum depth of the lateral groove, respectively, when the tire internal pressure is 250 kPa and no load is applied. In short, these can be calculated by compacting the bead portion of a radially cut section with a width of 2-4 cm according to the rim width.

[0085] 6. Tire shape

[0086] In the tire of the present invention, when the tire is mounted on a standardized rim and the internal pressure is 250 kPa, the specific outer diameter Dt (mm) is preferably, for example, 515 mm or more, more preferably 558 mm or more, further preferably 585 mm or more, further preferably 648 mm or more, further preferably 658 mm or more, further preferably 662 mm or more, further preferably 664 mm or more, further preferably 671 mm or more, and most preferably 673 mm or more.

[0087] On the other hand, it is preferably less than 843 mm, more preferably less than 735 mm, further preferably less than 725 mm, further preferably less than 719 mm, further preferably less than 717 mm, further preferably less than 716 mm, further preferably less than 714 mm, further preferably less than 711 mm, further preferably less than 707 mm, further preferably less than 691 mm, further preferably less than 690 mm, further preferably less than 685 mm, further preferably less than 685 mm, further preferably less than 680 mm, and further preferably less than 675 mm.

[0088] The specific cross-sectional width Wt (mm) is preferably 115 mm or more, more preferably 130 mm or more, further preferably 150 mm or more, further preferably 170 mm or more, further preferably 174 mm or more, further preferably 175 mm or more, further preferably 176 mm or more, further preferably 178 mm or more, further preferably 181 mm or more, further preferably 183 mm or more, and particularly preferably 185 mm, and most preferably 193 mm or more.

[0089] On the other hand, it is preferably less than 305 mm, more preferably less than 245 mm, further preferably 235 mm or less, further preferably 231 mm or less, further preferably 230 mm or less, further preferably 229 mm or less, further preferably 228 mm or less, further preferably 224 mm or less, further preferably less than 210 mm, further preferably less than 205 mm, further preferably 203 mm or less, further preferably 202 mm or less, further preferably 200 mm or less, and further preferably less than 200 mm.

[0090] The specific cross-sectional height Ht (mm) is, for example, preferably 37 mm or more, more preferably 69 mm or more, further preferably 70 mm or more, further preferably 71 mm or more, further preferably 77 mm or more, further preferably 78 mm or more, further preferably 79 mm or more, further preferably 80 mm or more, further preferably 87 mm or more, further preferably 89 mm or more, further preferably 90 mm or more, further preferably 95 mm or more, further preferably 96 mm or more, further preferably 98 mm or more, and further preferably 99 mm or more.

[0091] On the other hand, it is preferably less than 180 mm, more preferably 116 mm or less, further preferably 114 mm or less, further preferably less than 112 mm, further preferably 104 mm or less, further preferably 101 mm or less, and further preferably less than 101 mm.

[0092] The specific virtual volume V is preferably 13,000,000 mm 3 Above, more preferably 22,647,919 mm 3 Above, more preferably 23,279,803mm 3 Above, more preferably 23,518,082 mm 3 Above, more preferably 28,585,634mm 3 Above, more preferably 28,719,183mm 3 More than, more preferably 29,000,000 mm 3 Above, more preferably 29,087,378mm 3Above, more preferably 30, 132, 749 mm 3 Above, more preferably 30, 349, 719 mm 3 Above, more preferably 34, 192, 251 mm 3 Above, more preferably 35,836,776mm 3 More than 36,000,000 mm is more preferred 3 Above, more preferably 36, 203, 610mm 3 Above, more preferably 36,418,787mm 3 Above, more preferably 36, 616, 393 mm 3 Above, and further preferably 36,682,357mm 3 above.

[0093] On the other hand, it is preferably less than 66,000,000 mm 3 , more preferably 52, 265, 389 mm 3 Below, more preferably less than 44,000,000 mm 3 , further preferably 43,355,989mm 3 Below, more preferably 41,835,961mm 3 Below, more preferably 40, 755, 756 mm 3 Less than, and more preferably less than 38,800,000 mm 3 .

[0094] Furthermore, in the tire of the present invention, considering the stability of ride comfort during driving, (Dt-2×Ht) is preferably 450 mm or more, more preferably 456 mm or more, further preferably 458 mm or more, further preferably 470 mm or more, further preferably 480 mm or more, further preferably 482 mm or more, further preferably 483 mm or more, and further preferably 484 mm or more.

[0095] On the other hand, considering the deformation of the tread portion, it is preferably less than 560 mm, more preferably 559 mm or less, further preferably 558 mm or less, further preferably 534 mm or less, further preferably 533 mm or less, further preferably less than 530 mm, further preferably less than 510 mm, further preferably 509 mm or less, further preferably 508 mm or less, and further preferably 507 mm or less.

[0096] [3] Specific embodiments of the present invention

[0097] Hereinafter, the present invention will be described in detail based on embodiments.

[0098] 1. Tire shape

[0099] Figure 1 : is a partial meridian cross-sectional view of a tire according to an embodiment of the present invention. Figure 1 In the figure, 1 is the tire, 2 is the side, 3 is the bead, 4 is the bead core, 5 is the carcass ply, 6 is the bead apex, and 7 is the inner liner. Ha is the distance (mm) from the bead base line to the widthwise outer side of the bead 3 at the interface between the side 2 and the bead 3, and Hb is the distance (mm) to the widthwise inner side of the bead 3. The side 2 is joined to the tread portion (not shown).

[0100] like Figure 1 As shown, in the tire of this embodiment, the end of the bead portion 3 overlaps with the end of the side portion 2, and the bead portion 3 is joined to the side portion 2, thereby satisfying Ha>Hb. Figure 1 In the figure, the end of the side portion is covered by the end of the edge portion, but the content of the present invention is not limited to the form shown in the figure.

[0101] In this embodiment, the complex elastic modulus E* of the side portion 2 measured under the conditions of temperature of 70°C, frequency of 10 Hz, initial strain of 5% and dynamic strain rate of 1% is S (MPa) less than the composite elastic modulus E* of the edge portion 3 C (MPa).

[0102] In this embodiment, when the cross-sectional width is Wt (mm), the outer diameter is Dt (mm) and the volume of the space occupied by the tire is the virtual volume V (mm 3 ), and when the tire is mounted on a standardized rim and the internal pressure is 250 kPa, the following equations 1 and 2 are satisfied.

[0103] 1600≦(Dt 2 ×π / 4) / Wt≦2827.4Equation 1

[0104] [(V+1.5×10 7 ) / Wt]≦2.88×10 5 Formula 2

[0105] By configuring the tire of the present embodiment in this manner, it is possible to sufficiently suppress uneven wear of the tread portion during high-speed running and provide a pneumatic tire having excellent durability performance.

[0106] 2. Rubber composition

[0107] The side portions, bead portions, and tread portion are main components constituting the tire of this embodiment, and are each made of a rubber composition (a rubber composition for the side portions, a rubber composition for the bead portions, and a rubber composition for the tread portion).

[0108] (1) Rubber composition of the side portion and the rubber composition of the edge portion

[0109] In this embodiment, the rubber composition of the side portion and the rubber composition of the edge portion are prepared by mixing various compounding materials such as the following rubber components, fillers, softeners, vulcanizers and vulcanization accelerators, and they can be easily obtained by appropriately adjusting the compounding materials, especially the types and amounts of fillers and softeners (to obtain corresponding physical properties).

[0110] (a) Rubber component

[0111] As the rubber component of each rubber composition, the rubber (polymer) commonly used for producing tires can be used, such as butadiene rubber (BR), styrene-butadiene rubber (SBR), isoprene rubber and acrylonitrile-butadiene rubber (NBR). Among them, butadiene rubber (BR) and isoprene rubber are preferably used.

[0112] (a-1)BR

[0113] In each rubber composition, the BR content per 100 parts by mass of the rubber component is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 55 parts by mass or more. On the other hand, the BR content is preferably 75 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 65 parts by mass or less.

[0114] The weight average molecular weight of BR is, for example, greater than 100,000 and less than 2,000,000. The vinyl bond 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. The cis content can be measured by infrared absorption spectroscopy.

[0115] There are no particular limitations on BR, and BR with a high cis content (90% or more cis content), BR with a low cis content, and BR containing syndiotactic polybutadiene crystals can be used. Among these, high cis BR is preferred. High cis BR is butadiene rubber with a cis content of 90% or more.

[0116] BR may be unmodified BR or modified BR. As the modified BR, for example, BR modified with a compound (modifying agent) represented by the following formula can be used.

[0117] [Chemical Formula 1]

[0118]

[0119] Where R 1 、R 2 and R 3 represents the same or different alkyl groups, alkoxy groups, silyl groups, acetal groups, carboxyl groups (-COOH), mercapto groups (-SH) or their derivatives. 4 and R 5 R represents the same or different hydrogen atoms or alkyl groups. 4 and R 5 They can be combined to form a ring structure with a nitrogen atom. n represents an integer.

[0120] As the BR modified with the compound (modifying agent) represented by the above formula, there can be mentioned BR whose polymerization terminal (active terminal) is modified with the compound represented by the above formula.

[0121] As R 1 、R 2 and R 3 , an alkoxy group is preferred (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms). As R 4 and R 5 , an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) is preferred. n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. In addition, when R 4 and R 5 When combined with a nitrogen atom to form a ring structure, it is preferably a 4- to 8-membered ring. Alkoxy groups also include cycloalkoxy groups (eg, cyclohexyloxy groups) and aryloxy groups (eg, phenoxy groups, benzyloxy groups).

[0122] Specific examples of the above-mentioned 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.

[0123] In addition, as the modified BR, modified BR modified with the following compounds (modifiers) can also be used. Examples of the modifying agent include:

[0124] Polyglycidyl ethers of polyols, such as ethylene glycol diglycidyl ether, glycerol triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether;

[0125] Polyglycidyl ethers of aromatic compounds having two or more phenolic groups, such as bisphenol A diglycidyl ether;

[0126] Polyepoxides, such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxidized liquid polybutadiene;

[0127] Tertiary amines containing epoxy groups, such as 4,4'-diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine;

[0128] Diglycidylamino compounds, such as diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidyl-n-toluene, tetraglycidyl-m-xylenemethylamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-bisaminomethylcyclohexane;

[0129] Acidic chlorides containing amino groups, such as bis(1-methylpropyl)carbamic acid chloride, 4-morpholinecarbonyl chloride, 1-pyrrolidinecarbonyl chloride, N,N-dimethylcarbonyl chloride and N,N-diethylcarbonyl chloride;

[0130] Silane compounds containing epoxy groups, such as 1,3-bis(glycidylpropyl)-tetramethyldisiloxane and (3-glycidylpropyl)-pentamethyldisiloxane;

[0131] Silane compounds containing a thioether group, such as (trimethylsilyl)[3-(trimethoxysilyl)propyl] sulfide, (trimethylsilyl)[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, and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl] sulfide;

[0132] N-substituted aziridine compounds, such as ethyleneimine and propyleneimine;

[0133] Alkoxysilanes, such as methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane and N,N-bis(trimethylsilyl)aminoethyltriethoxysilane;

[0134] (Thio)benzophenone compounds having an amino group and / or a substituted amino group, such as 4-N,N-dimethylaminobenzophenone, 4-N,N-di-tert-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;

[0135] Benzaldehyde compounds having an amino group and / or a substituted amino group, such as 4-N,N-dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, and 4-N,N-divinylaminobenzaldehyde;

[0136] N-substituted pyrrolidones, such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, N-tert-butyl-2-pyrrolidone and N-methyl-5-methyl-2-pyrrolidone;

[0137] N-substituted piperidones, such as N-methyl-2-piperidone, N-vinyl-2-piperidone and N-phenyl-2-piperidone;

[0138] N-substituted lactams, such as N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurolactam, N-vinyl-ω-laurolactam, N-methyl-β-propiolactam and N-phenyl-β-propiolactam; and

[0139] N,N-bis(2,3-epoxypropyl)-aniline, 4,4-methylenebis(N,N-glycidylaniline), 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-dimethylaminoacetophenone, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, and 1,7-bis(methylethylamino)-4-heptanone. Modification with the above compounds (modifiers) can be performed by known methods. These modified BRs can be used alone or in combination of two or more.

[0140] As BR, for example, products of Ube Industries, Ltd., JSR Corporation, Asahi Kasei Co., Ltd., Nippon Zeon Co., Ltd., etc. can be used.

[0141] (a-2) Isoprene rubber

[0142] In each rubber composition, the content (total content) of the isoprene-based rubber per 100 parts by mass of the rubber component is preferably 25 parts by mass or more, more preferably 30 parts by mass or more, and further preferably 35 parts by mass or more. On the other hand, it is preferably 55 parts by mass or less, more preferably 50 parts by mass or less, and further preferably 45 parts by mass or less.

[0143] Examples of the isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), recombinant NR, modified NR, and modified IR. Among them, NR is preferable from the viewpoint of excellent strength.

[0144] As NR, for example, SIR20, RSS#3, TSR20, etc. commonly used in the tire industry can be used. There is no particular limitation on IR, for example, IR2200 manufactured by Nippon Zeon Co., Ltd., which is common in the tire industry, can be used. Modified NR includes deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), etc. Modified NR includes epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, etc. Modified IR includes epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, etc. These can be used alone or in combination of two or more.

[0145] (a-3) Other rubber components

[0146] Furthermore, the rubber composition may contain, as another rubber component, a rubber (polymer) generally used for producing tires, such as styrene-butadiene rubber (SBR) and nitrile rubber (NBR).

[0147] (b) Compounding materials other than rubber components

[0148] (b-1) Carbon black

[0149] Each rubber composition preferably contains carbon black as a reinforcing agent. For example, the content of carbon black is preferably greater than 1 part by mass and less than 200 parts by mass per 100 parts by mass of the rubber component.

[0150] Carbon black is not particularly limited, and examples thereof include furnace blacks such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF; acetylene black; thermal blacks such as FT and MT; channel blacks such as EPC, MPC, and CC; and graphite. Commercially available products include, for example, those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin Nikka Carbon Co., Ltd., and Columbia Carbon Co., Ltd. These can be used alone or in combination of two or more.

[0151] The nitrogen adsorption specific surface area (N2SA) of carbon black is, for example, greater than 30 m 2 / g and less than 250m 2 / g. The amount of dibutyl phthalate (DBP) absorbed by carbon black is, for example, greater than 50 ml / 100 g and less than 250 ml / 100 g. The nitrogen adsorption specific surface area of ​​carbon black is measured according to ASTM D4820-93, and the amount of DBP absorbed is measured according to ASTM D2414-93.

[0152] In addition to the carbon black described above, each rubber composition may further contain fillers commonly used in the tire industry, such as silica, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica. For example, the content of these fillers is greater than 0.1 part by mass and less than 200 parts by mass per 100 parts by mass of the rubber component.

[0153] (b) Softener

[0154] The rubber composition may contain oil (including extending oil) or liquid rubber as a softener. The total content of these, relative to 100 parts by mass of the rubber component, is preferably greater than 1.0 parts by mass, and more preferably greater than 8.0 parts by mass. On the other hand, less than 100 parts by mass is preferred, less than 40 parts by mass is more preferred, and less than 30 parts by mass is even more preferred. The oil content also includes the amount of oil contained in the rubber (oil-dispersed rubber).

[0155] The example of oil includes mineral oil (generally referred to as process oil), vegetable oil and fat, or its mixture. As mineral oil (process oil), for example, paraffin process oil, aromatic process oil, naphthenic process oil etc. can be used. The example of vegetable oil and fat includes 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, Beni flower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil and tung oil. These can be used alone or in combination of two or more.

[0156] Specific examples of the process oil (mineral oil) include products of Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Olisoy Co., Ltd., H&R Co., Ltd., Toyokuni Seiyu Co., Ltd., Showa Shell Sekiyu Co., Ltd., and Fuji Kosan Co., Ltd.

[0157] Liquid rubber mentioned as a softener is a polymer that is in a liquid state at room temperature (25°C) and has monomers similar to those of solid rubber as constituent elements. Examples of liquid rubber include farnesene polymers, liquid diene polymers, and hydrogenated additives thereof.

[0158] Farnesene polymers are obtained by polymerizing farnesene and have farnesene-based structural units. Farnesene includes 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).

[0159] 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).

[0160] Examples of the liquid diene polymer include liquid styrene-butadiene copolymers (liquid SBR), liquid butadiene polymers (liquid BR), liquid isoprene polymers (liquid IR), and liquid styrene isoprene copolymers (liquid SIR).

[0161] The polystyrene equivalent weight average molecular weight (Mw) of the liquid diene polymer measured by gel permeation chromatography (GPC) is, for example, greater than 1.0×10 3 and less than 2.0×10 5In this specification, the Mw of the liquid diene polymer is a polystyrene-converted value measured by gel permeation chromatography (GPC).

[0162] As the liquid rubber, for example, products of Kuraray Co., Ltd. and Clay Valley Co., Ltd. can be used.

[0163] (b-3) Anti-aging agent

[0164] Each rubber composition preferably contains an antioxidant. For example, the content of the antioxidant is greater than 1 part by mass and less than 10 parts by mass per 100 parts by mass of the rubber component.

[0165] Examples of anti-aging agents include naphthylamine anti-aging agents such as phenyl-α-naphthylamine; diphenylamine anti-aging agents such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine 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 anti-aging agents such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol anti-aging agents such as 2,6-di-tert-butyl-4-methylphenol and styrenated phenol; bis-, tris-, and polyphenol anti-aging agents such as tetrakis[3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane. These can be used alone or in combination of two or more.

[0166] As the anti-aging agent, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexsys Co., Ltd., etc. can be used.

[0167] (b-4) stearic acid

[0168] Each rubber composition may contain stearic acid. For example, the content of stearic acid may be greater than 0.5 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component. Conventional stearic acid can be used, for example, products from NOF Corporation, Kao Corporation, Fuji Film Wako Pure Chemical Industries, Ltd., and Chiba Fatty Acid Co., Ltd.

[0169] (b-5) Zinc oxide

[0170] Each rubber composition may contain zinc oxide. For example, the content of zinc oxide is greater than 0.5 parts by mass and less than 10 parts by mass per 100 parts by mass of the rubber component. Conventional zinc oxide can be used, for example, products from Mitsui Metal Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Shodo Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., and the like.

[0171] (b-6) wax

[0172] Each rubber composition preferably contains wax. For example, the wax content is 0.5 to 20 parts by mass, preferably 1.5 to 15 parts by mass, and more preferably 3.0 to 10.0 parts by mass per 100 parts by mass of the rubber component.

[0173] The wax is not particularly limited, and examples thereof include petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as plant wax and animal wax; and synthetic waxes such as polymers of ethylene or propylene. These can be used alone or in combination of two or more.

[0174] As the wax, for example, products of Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Seiko Kagaku Co., Ltd. can be used.

[0175] (b-7) Crosslinking agent and vulcanization accelerator

[0176] Each rubber composition preferably contains a crosslinking agent such as sulfur. For example, the content of the crosslinking agent is greater than 0.1 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component.

[0177] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur commonly used in the rubber industry. These can be used alone or in combination of two or more.

[0178] As sulfur, for example, products of Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemicals Corporation, Flexsys Co., Ltd., Nippon Kanryu Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., and the like can be used.

[0179] Examples of cross-linking agents other than sulfur include vulcanizing agents containing sulfur atoms, such as Tackirol V200 manufactured by Taoka Chemical Industry Co., Ltd., DURALINK HTS (1,6-hexamethylene-sodium dithiosulfate dihydrate) manufactured by Flexsys, and KA9188 (1,6-bis(N,N′-dibenzylthiocarbamoyldisulfide)hexane) manufactured by Lanxess; and organic peroxides such as dicumyl peroxide.

[0180] Each rubber composition preferably contains a vulcanization accelerator. For example, the content of the vulcanization accelerator is greater than 0.3 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component.

[0181] Examples of vulcanization accelerators include:

[0182] Thiazole vulcanization accelerators, such as 2-mercaptobenzothiazole, di-2-benzothiazole disulfide, and N-cyclohexyl-2-benzothiazylsulfenamide;

[0183] Thiuram vulcanization accelerators, such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N);

[0184] Sulfenamide vulcanization accelerators, such as N-cyclohexyl-2-benzothiazolesulfenamide, N-tert-butyl-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide and N,N'-diisopropyl-2-benzothiazolesulfenamide;

[0185] and guanidine vulcanization accelerators such as diphenylguanidine, di-o-tolylguanidine and o-tolylguanidine.

[0186] These can be used alone or in combination of two or more.

[0187] (b-8) Other

[0188] In addition to the above ingredients, each rubber composition may also contain additives commonly used in the tire industry, such as fatty acid metal salts, carboxylic acid metal salts, organic peroxides, and graphite. For example, the content of these additives is greater than 0.1 parts by mass and less than 200 parts by mass per 100 parts by mass of the rubber component.

[0189] (2) Rubber composition of tread

[0190] In the present embodiment, the rubber composition of the tread portion contains a predetermined rubber component and other compounding materials.

[0191] (a) Rubber component

[0192] The rubber composition of the tread portion can use rubber (polymer) such as butadiene rubber (BR), styrene-butadiene rubber (SBR), isoprene rubber and acrylonitrile-butadiene rubber (NBR) that are commonly used to make tires as rubber components. Among them, styrene-butadiene rubber (SBR) and isoprene rubber are preferably used. In these rubbers, the rubber phase can be phase separated and entangled with each other, so that the strain in the rubber can be reduced.

[0193] (a-1)SBR

[0194] The SBR content in 100 parts by mass of the rubber component is 1 part by mass or more and less than 100 parts by mass. It is more preferably greater than 5 parts by mass, further preferably greater than 15 parts by mass, and particularly preferably greater than 25 parts by mass. On the other hand, it is preferably less than 65 parts by mass, more preferably less than 55 parts by mass, further preferably less than 45 parts by mass, and particularly preferably less than 35 parts by mass.

[0195] The weight average molecular weight of SBR is, for example, greater than 100,000 and less than 2,000,000. The styrene content of SBR is more than 5% by mass, particularly more than 8% by mass. It is preferably less than 35% by mass, more preferably less than 25% by mass, and further preferably less than 15% by mass. The vinyl bond amount (butadiene unit amount of 1,2-bonding) of SBR is, for example, greater than 5% by mass and less than 70% by mass. The structural evaluation (styrene content and measurement of vinyl bond amount) of SBR can be carried out using the JNM-ECA series equipment manufactured by, for example, JEOL Ltd.

[0196] There are no particular limitations on SBR, and examples thereof include emulsion-polymerized styrene-butadiene rubber (E-SBR) and solution-polymerized styrene-butadiene rubber (S-SBR). SBR may be unmodified SBR or modified SBR, and these may be used alone or in combination of two or more.

[0197] Modified SBR can be any SBR having functional groups that interact with fillers such as silica. Examples include:

[0198] Terminal-modified SBR (terminal-modified SBR having the above-mentioned functional groups at the ends), wherein at least one end of the SBR is modified with a compound (modifier) ​​having the above-mentioned functional groups;

[0199] Main chain modified SBR, whose functional groups are on the main chain;

[0200] Main chain terminal modified SBR having functional groups in the main chain and at the terminals (e.g., main chain terminal modified SBR in which the main chain has the above functional groups and at least one terminal is modified with the above modifier); and

[0201] Terminal-modified SBR is modified (coupled) with a multifunctional compound having two or more epoxy groups in the molecule, and epoxy groups or hydroxyl groups are introduced therein.

[0202] Examples of the functional group include an amino group, an acylamino 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 thioether group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imido 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, and an epoxy group. These functional groups may also have a substituent.

[0203] Furthermore, as the modified SBR, one into which the above-mentioned functional groups are introduced can be used.

[0204] As SBR, for example, SBR produced and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Co., Ltd., Nippon Zeon Co., Ltd., etc. can be used. The SBR can be used alone or in combination of two or more.

[0205] (a-2) Isoprene rubber

[0206] As isoprene rubber, the aforementioned natural rubber (NR), isoprene rubber (IR), recombinant NR, modified NR, and modified IR can be used. The isoprene rubber content (total content) is preferably greater than 5 parts by mass, more preferably greater than 25 parts by mass, even more preferably greater than 35 parts by mass, and particularly preferably greater than 50 parts by mass. Meanwhile, the upper limit of the isoprene rubber content is not particularly limited, but is preferably less than 100 parts by mass, and more preferably less than 80 parts by mass.

[0207] (a-3)BR

[0208] The rubber composition of the tread portion may further include the aforementioned BR. In this case, the BR content is preferably greater than 5 parts by mass per 100 parts by mass of the rubber component. Furthermore, it is preferably less than 100 parts by mass, more preferably less than 30 parts by mass, and even more preferably less than 20 parts by mass.

[0209] (a-4) Other rubber components

[0210] Furthermore, the rubber composition of the tread portion may contain, as another rubber component, a rubber (polymer) generally used for producing tires, such as acrylonitrile-butadiene rubber (NBR).

[0211] (b) Compounding materials other than rubber components

[0212] (b-1) Silicon dioxide

[0213] If necessary, the rubber composition may contain silica. From the viewpoint of obtaining good durability, the BET specific surface area of ​​silica is preferably greater than 140 m 2 / g, more preferably greater than 160m 2 / g. On the other hand, from the perspective of obtaining good rolling resistance during high-speed running, it is preferably less than 250m 2 / g, more preferably less than 220m 2 / g. Furthermore, the silica content is preferably greater than 60 parts by mass, more preferably greater than 70 parts by mass, per 100 parts by mass of the rubber component. On the other hand, it is preferably less than 150 parts by mass, more preferably less than 140 parts by mass, and even more preferably less than 130 parts by mass. The above-mentioned BET specific surface area is the N2SA value measured using the BET method according to ASTM D3037-93.

[0214] Examples of silica include dry-process silica (anhydrous silica) and wet-process silica (hydrous silica). Among them, wet-process silica is preferred because it has a large number of silanol groups.

[0215] As silica, for example, products of Evonik, Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Corporation, etc. can be used.

[0216] (b-2) Silane coupling agent

[0217] In addition, the rubber composition of the tread portion preferably contains a silane coupling agent and silica. The silane coupling agent is not particularly limited. Examples of silane coupling agents include:

[0218] Sulfide silane coupling agents, such as 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)tetrasulfide bis(trimethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-trimethoxysilylpropyl methacrylate monosulfide;

[0219] Mercapto-based silane coupling agents, such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and NXT and NXT-Z manufactured by Momentive;

[0220] Vinyl silane coupling agents, such as vinyltriethoxysilane and vinyltrimethoxysilane;

[0221] Amino silane coupling agents, such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane;

[0222] Glycidyloxy silane coupling agents, such as γ-glycidyloxypropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane;

[0223] Nitro-based silane coupling agents, such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and

[0224] Chlorosilane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane can be used alone or in combination of two or more.

[0225] As the silane coupling agent, for example, products of Degussa, Momentive, Shinetsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., Toray Dow Corning Co., Ltd., etc. can be used.

[0226] For example, the content of the silane coupling agent is greater than 3 parts by mass and less than 25 parts by mass relative to 100 parts by mass of silica.

[0227] (b-3) Carbon black

[0228] The rubber composition of the tread portion preferably contains the carbon black described in the "(1) rubber composition of the side portion and the rubber composition of the bead portion." For example, the carbon black content is greater than 1 part by mass and less than 200 parts by mass per 100 parts by mass of the rubber component.

[0229] In addition to the aforementioned silica and carbon black, fillers commonly used in the tire industry, such as calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica, may also be contained, for example, in an amount greater than 0.1 parts by mass and less than 200 parts by mass per 100 parts by mass of the rubber component.

[0230] (b-4) Softener

[0231] Similarly, the rubber composition of the tread portion preferably contains the oil (including the extension oil) and liquid rubber described in the above "(1) Rubber composition of the side portion and the rubber composition of the bead portion" as a softener. The total content of these is preferably greater than 5 parts by mass, more preferably greater 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.

[0232] (b-5) Resin component

[0233] The rubber composition of the tread portion preferably contains a resin component. The resin component can be solid or liquid at room temperature. Specific examples of the resin component include styrene resins, coumarone resins, terpene resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins. Two or more types of resin components may be used in combination. The content of the resin component per 100 parts by mass of the rubber component is preferably greater than 2 parts by mass and less than 45 parts by mass, and more preferably less than 30 parts by mass.

[0234] (Styrene resin)

[0235] Styrene resins are polymers using styrene monomers as constituent monomers, and examples thereof include polymers obtained by polymerizing styrene monomers as a main component (50% by mass or more). Specifically, they include homopolymers obtained by polymerizing 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 obtained by copolymerizing two or more styrene monomers, and copolymers obtained by copolymerizing styrene monomers and other monomers copolymerizable with styrene monomers.

[0236] Examples of other monomers include acrylonitriles such as acrylonitrile and methacrylate; unsaturated carboxylic acids such as acrylic acid and methacrylic acid; 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; α,β-unsaturated carboxylic acids (such as maleic anhydride) and anhydrides thereof.

[0237] (Coumarone resin)

[0238] As the coumarone resin, coumarone-indene resin is preferably used. Coumarone-indene resin is a resin containing coumarone and indene as monomer components constituting the resin skeleton (main chain). Examples of monomer components contained in the skeleton, in addition to coumarone and indene, include styrene, α-methylstyrene, methylindene, and vinyltoluene.

[0239] For example, the content of the coumarone-indene resin is greater than 1.0 part by mass and less than 50.0 parts by mass relative to 100 parts by mass of the rubber component.

[0240] The hydroxyl value (OH value) of the coumarone-indene resin is, for example, greater than 15 mgKOH / g and less than 150 mgKOH / g. The OH value refers to the amount of potassium hydroxide (in milligrams) required to neutralize acetic acid bound to hydroxyl groups when 1 g of the resin is acetylated. This value is measured by potentiometric titration (JIS K 0070:1992).

[0241] The softening point of the coumarone-indene resin is, for example, higher than 30° C. and lower than 160° C. The softening point is a temperature at which a ball falls when measuring the softening point defined in JIS K 6220-1:2001 using a ring-and-ball softening point measuring device.

[0242] (Terpene resin)

[0243] Examples of terpene resins include polyterpenes, terpene phenols, and aromatic modified terpene resins. Polyterpenes are resins obtained by polymerizing terpene compounds and their hydrogenation products. Terpene compounds are a type of compound having (C5H8) nHydrocarbons or their oxygenated derivatives, which are classified as monoterpenes (C 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 ) as a basic skeleton. Examples include α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, osimene, α-phellandrene, α-terpinene, γ-terpinene, terpinene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0244] Examples of polyterpenes include terpene resins made from the above-mentioned terpene compounds, such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin and β-pinene / limonene resin, and hydrogenated terpene resins obtained by hydrogenating terpene resins. Examples of terpene phenols include resins obtained by copolymerizing the above-mentioned terpene compounds and phenolic compounds, and resins obtained by hydrogenating the above-mentioned resins. Specifically, resins obtained by condensing the above-mentioned terpene compounds, phenolic compounds and formalin are mentioned. Examples of phenolic compounds include 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 phenol compounds such as phenol, alkylphenol, alkoxyphenol and phenol containing an unsaturated hydrocarbon group; naphthol compounds such as naphthol, alkylnaphthol, alkoxynaphthol and naphthol containing an unsaturated hydrocarbon group; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, styrene containing an unsaturated hydrocarbon group; coumarone and indene.

[0245] (C5 resin, C9 resin, C5C9 resin)

[0246] 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.

[0247] C9 resin refers to a resin obtained by polymerizing a C9 fraction, and it can be hydrogenated or modified. Examples of C9 fractions include petroleum fractions with 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene and methylindene. As specific examples, coumarone-indene resin, coumarone resin, indene resin and aromatic vinyl resin are preferably used. As aromatic vinyl resin, a homopolymer of α-methylstyrene or styrene or a copolymer of α-methylstyrene and styrene is preferred because it is economical, easy to process, and excellent in terms of heat generation. Copolymers of α-methylstyrene and styrene are more preferred. As aromatic vinyl resins, for example, commercially available resins such as Clayton and Eastman Chemical can be used.

[0248] C5C9 resin refers to a resin obtained by copolymerizing a C5 fraction and a C9 fraction, and it may be hydrogenated or modified. Examples of C5 fraction and C9 fraction include the above-mentioned petroleum fractions. As C5C9 resin, for example, those commercially available from Tosoh Corporation, LUHUA, etc. can be used.

[0249] (Acrylic resin)

[0250] The acrylic resin is not particularly limited, and for example, a solvent-free acrylic resin can be used.

[0251] As solvent-free acrylic resins, there can be mentioned (meth)acrylic resins (polymers) synthesized by a high-temperature continuous polymerization method (high-temperature continuous bulk polymerization method: methods described in US Pat. No. 4,414,370B, JP 84-6207A, JP 93-58805B, JP 89-313522A, US Pat. No. 5,010,166B, Toa Synthetic Research Annual Report TREND 2000 No. 3, p. 42-45, etc.), without using polymerization initiators, chain transfer agents, organic solvents, etc. as auxiliary raw materials as much as possible. In the present invention, (meth)acrylic acid refers to methacrylic acid and acrylic acid.

[0252] Examples of monomer components constituting the acrylic resin include (meth)acrylic acid, and (meth)acrylic acid derivatives such as (meth)acrylates (alkyl esters, aryl esters, aralkyl esters, etc.), (meth)acrylamide, and (meth)acrylamide derivatives.

[0253] Furthermore, as monomer components constituting the acrylic resin, aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, divinylnaphthalene, etc. may be used together with (meth)acrylic acid or a (meth)acrylic acid derivative.

[0254] The acrylic resin may be a resin composed only of a (meth)acrylic acid component or a resin containing components other than the (meth)acrylic acid component. In addition, the acrylic resin may have a hydroxyl group, a carboxyl group, a silanol group, or the like.

[0255] As the resin component, for example, products of Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Toso Co., Ltd., Rutgers Chemicals Co., Ltd., BASF Co., Ltd., Arizona Chemical Co., Ltd., Nitto Chemical Co., Ltd., Nippon Catalyst Co., Ltd., JX Energy Co., Ltd., Arakawa Chemical Industry Co., Ltd., and Taoka Chemical Industry Co., Ltd. can be used.

[0256] (b-6) Anti-aging agent

[0257] The rubber composition of the tread portion preferably contains an antioxidant as described in "(1) Rubber composition of the side portion and rubber composition of the bead portion" above. For example, the amount of the antioxidant is greater than 1 part by mass and less than 10 parts by mass per 100 parts by mass of the rubber component.

[0258] (b-7) stearic acid

[0259] The rubber composition of the tread portion may also contain the above-mentioned stearic acid. For example, the content of stearic acid is greater than 0.5 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component.

[0260] (b-8) Zinc oxide

[0261] The rubber composition of the tread portion may also contain the above-mentioned zinc oxide. For example, the content of zinc oxide is greater than 0.5 parts by mass and less than 10 parts by mass per 100 parts by mass of the rubber component.

[0262] (b-9) Crosslinking agent and vulcanization accelerator

[0263] The rubber composition of the tread portion preferably contains the crosslinking agent and vulcanization accelerator described above. For example, the crosslinking agent content is greater than 0.1 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component. For example, the vulcanization accelerator content is greater than 0.3 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component.

[0264] (b-10) Other

[0265] In addition to the above-mentioned components, the rubber composition of the tread portion may further contain additives commonly used in the tire industry, such as fatty acid metal salts, carboxylic acid metal salts, organic peroxides, etc. For example, the content of these additives may be greater than 0.1 parts by mass and less than 200 parts by mass per 100 parts by mass of the rubber component.

[0266] (3) Mixing of rubber compositions

[0267] The mixing of each rubber composition will be described in detail below.

[0268] As described above, kneading can be performed using, for example, a Banbury mixer, a kneader, or an open roll.

[0269] The mixing temperature in the basic mixing step is, for example, higher than 50° C. and lower than 200° C., and the mixing time is, for example, greater than 30 seconds and less than 30 minutes. In the basic mixing process, in addition to the above ingredients, compounding agents commonly used in the rubber industry, such as softeners (e.g., oil, stearic acid, zinc oxide), anti-aging agents, waxes, and vulcanization accelerators, may be appropriately added and mixed as needed.

[0270] In the fine mixing step, the mixed product obtained in the basic mixing step is mixed with a crosslinking agent. The mixing temperature in the fine mixing step is, for example, above room temperature and below 80°C, and the mixing time is, for example, greater than 1 minute and less than 15 minutes. In addition to the aforementioned ingredients, a vulcanization accelerator, zinc oxide, etc. may be added and mixed as needed in the fine mixing step.

[0271] 3. Tire manufacturing

[0272] The tire of the present invention is manufactured by a conventional method using the unvulcanized rubber composition obtained through the fine mixing step. In other words, the unvulcanized rubber composition is extruded according to the shape of each of the side portions, bead portions, and tread portion, and molded together with other tire components on a tire molding machine by a conventional method to produce an unvulcanized tire.

[0273] Specifically, the inner liner, which ensures the tire's airtightness, the carcass, which withstands the load, impact, and inflation pressure of the tire, and the belt, which strongly tightens the carcass to increase tread rigidity, are wound around the forming drum. The carcass' ends are secured to the sides, and the beads, which secure the tire to the rim, are arranged and formed into a toroidal shape. The tread is then attached to the center of the outer circumference, and the sidewalls, which protect the carcass and prevent bending, are attached radially outward, resulting in an unvulcanized tire.

[0274] In this embodiment, it is preferable to provide an inclined belt layer extending at an angle greater than 55° and less than 75° relative to the tire circumferential direction as the belt. Therefore, the tire durability can be ensured while the rigidity of the tread is sufficiently maintained.

[0275] The unvulcanized tire is then heated and pressed in a vulcanizer to obtain a tire. The vulcanization step can be performed by applying known vulcanization methods. The vulcanization temperature is, for example, higher than 120°C and lower than 200°C, and the vulcanization time is, for example, greater than 5 minutes and less than 15 minutes.

[0276] At this time, when the tire is mounted on a standardized rim and the internal pressure is set to 250 kPa, the tire is formed into a shape that satisfies the above-mentioned Formulas 1 and 2.

[0277] Specific tires that can meet the above formulas 1 and 2 include tires with size markings of 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, 195 / 55R20, etc.

[0278] In this embodiment, a tire that can satisfy Formulas 1 and 2 is preferably used in pneumatic tires for passenger cars, and satisfying the above formulas can more advantageously solve the problem in the present invention, namely, providing a pneumatic tire in which uneven wear of the tread portion is sufficiently suppressed during high-speed driving, and which has excellent durability performance in addition to sufficiently reducing rolling resistance.

[0279] Here, the passenger car tire refers to a tire installed on a four-wheel vehicle, and its maximum load capacity is 1000 kg or less. Here, the maximum load capacity refers to the maximum load capacity defined for each tire in the standard system to which the tire is based. For example, in the case of the JATTA standard (Japan Automobile Tire Association standard), it is the maximum load capacity based on the load index (LI); in the case of the TRA (The Tire and Rim Association, Inc.), it is the maximum value described in "TIRE LOAD LIMITS AT VARIOUS COLD INFRATION PRESSURES"; and in the case of ETRTO, it is "INFRATION PRESSUR".

[0280] There are no particular restrictions on the maximum load capacity, as long as it is 1000 kg or less. However, generally speaking, as the maximum load capacity increases, the tire weight tends to increase, and due to inertia, the braking distance also increases accordingly. Therefore, the maximum load capacity is preferably 900 kg or less, more preferably 800 kg or less, and even more preferably 700 kg or less.

[0281] From the perspective of the braking distance due to inertia, 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, and 8 kg or less. The tire of the present invention may be equipped with electronic components. In this case, the tire weight referred to herein includes the weight of the electronic components and the components on which the electronic components are mounted. If sealant, sponge, etc. are provided in the cavity, the tire weight also includes these components.

[0282] Example

[0283] Hereinafter, the present invention will be described in more detail with reference to Examples.

[0284] [Experiment 1]

[0285] In this experiment, a 175 size tire was prepared and evaluated.

[0286] 1. Production of each rubber composition

[0287] First, each rubber composition (a rubber composition for the side portion, a rubber composition for the bead portion, and a rubber composition for the tread) was prepared.

[0288] (1) Rubber composition of the side portion

[0289] First, BR and NR were used as the rubber components in the above-mentioned compounding materials, and they were placed in a Banbury mixer together with carbon black, oil, stearic acid, zinc oxide, wax and an anti-aging agent as other compounding materials, and kneaded at 150° C. for 5 minutes to obtain a compounded product.

[0290] Next, sulfur and a vulcanization accelerator were added to the kneaded product obtained above, and the obtained mixture was kneaded at 80°C for 5 minutes using an open roll to obtain a rubber composition for the side portion. At this time, the mixing amounts of carbon black and oil in the compounded materials were adjusted so that the E* (E*) of the tire side portion was S ) is 4.0 MPa, and tanδ of the tire side is 0.090.

[0291] (2) Rubber component of the edge

[0292] The rubber composition of the side portion was obtained in the same manner as the rubber composition of the side portion. Here, in the compounding material, the mixing amount of carbon black and oil was adjusted to obtain five types, among which E* (E* C ) are 6.1MPa (Formula 1), 7.7MPa (Formula 2), 8.3MPa (Formula 3), 2.8MPa (Formula 4) or 6.7MPa (Formula 5) respectively.

[0293] (3) Rubber composition of the tread

[0294] NR and SBR were used as the rubber components of the above-mentioned compounding materials, and they were put into a Banbury mixer together with carbon black, silica, a silane coupling agent, oil, a resin (polymer), stearic acid and zinc oxide as other compounding materials, and kneaded at 150° C. for 5 minutes to obtain a kneaded product.

[0295] Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and the mixture was kneaded with an open roll at 80° C. for 5 minutes to obtain a rubber composition for the tread portion.

[0296] 2. Tire manufacturing

[0297] Using each of the obtained rubber compositions, side portions (thickness Ts: 5 mm), bead portions, and tread portions were molded into predetermined shapes and bonded together with other tire components to form unvulcanized tires. The unvulcanized tires were then press-vulcanized at 170° C. for 10 minutes to produce test tires (Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-5) having a size of 175.

[0298] 3. Parameter calculation

[0299] Thereafter, the outer diameter Dt (mm), cross-sectional width Wt (mm), aspect ratio (%), and (Ha-Hb) of each test tire were obtained, and the virtual volume V (mm 3 ). The results are shown in Tables 1 and 2.

[0300] At the same time, rubber test pieces measuring 20 mm in length, 4 mm in width, and 2 mm in thickness were cut from the rubber layer of the bead and side of each test tire, with the longer side oriented in the tire's circumferential direction. These rubber test pieces were then used to measure the viscoelasticity of each rubber test piece. The complex elastic modulus (E*) of each rubber test piece was measured using an Eplexor series manufactured by GABO Co., Ltd. at 70°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain of 1%. C ,E* S The results are shown in Tables 1 and 2. At the same time, tan δ of the side portion was measured to obtain tan δ×Ts (0.090×5=0.45).

[0301] Then, we calculated (Dt 2× π / 4) / Wt、(V+1.5×10 7 ) / Wt、(V+2.0×10 7 ) / Wt、(V+2.5×10 7 ) / Wt、30℃tanδ×Wt、(E* C -E* S The results are shown in Tables 1 and 2.

[0302] 4. Performance evaluation test

[0303] (1) Evaluation of uneven wear

[0304] Each test tire was mounted on all wheels of a domestic FF car (2000cc displacement). After filling with air to an internal pressure of 250 kPa, the tire was driven on a dry road test course at a speed of 120 km / h. After 30 laps, the wear of the center and shoulder treads was measured, and the ratio between the two was calculated. The closer this ratio is to 1, the less uneven wear there is.

[0305] Next, the calculation results in Comparative Examples 1-5 were set to 100, and the results were indexed based on the following formula to relatively evaluate the uneven wear resistance during high-speed running. A larger value indicates less uneven wear and better uneven wear resistance.

[0306] Uneven wear resistance = [(calculated results of Comparative Examples 1-5) / (calculated results of the test tire)] × 100

[0307] (2) Evaluation of durability

[0308] Each test tire was mounted on all wheels of a vehicle (a domestically produced FF car with a displacement of 2000cc) and inflated to an internal pressure of 250kPa. The vehicle was then driven for 10 laps at 50km / h. The vehicle was then driven over uneven surfaces at 80km / h. This process was repeated on a dry road surface while overloaded. Afterwards, the vehicle was driven once more at 50km / h for one lap, and then the speed was gradually increased to measure the speed at which the driver felt something was wrong.

[0309] Next, the results of Comparative Examples 1 to 5 were set to 100, and the durability performance was relatively evaluated by indexation based on the following formula: The larger the value, the better the durability.

[0310] Durability = [(results of the test tire) / (results of Comparative Examples 1-5)] × 100

[0311] (3) Comprehensive evaluation

[0312] The evaluation results of (1) and (2) above are combined to obtain a comprehensive evaluation.

[0313] (4) Evaluation results

[0314] The results of each evaluation are shown in Tables 1 and 2.

[0315] [Table 1]

[0316]

[0317] [Table 2]

[0318]

[0319] [Experiment 2]

[0320] In this experiment, a 195 size tire was prepared and evaluated.

[0321] After producing the test tires of Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-5 shown in Tables 3 and 4 in the same manner as Experiment 1, the various parameters were calculated by following the same procedure. Performance evaluation tests were then conducted and evaluated in the same manner. In this experiment, the results of Comparative Examples 2-5 were set to 100 for the purpose of evaluation. The results of each evaluation are shown in Tables 3 and 4.

[0322] [Table 3]

[0323]

[0324] [Table 4]

[0325]

[0326] [Experiment 3]

[0327] In this experiment, a 225 size tire was prepared and evaluated.

[0328] After producing the test tires of Examples 3-1 to 3-5 and Comparative Examples 3-1 to 3-5 shown in Tables 5 and 6 in the same manner as Experiment 1, the various parameters were calculated using the same procedure. Performance evaluation tests were then conducted and evaluated in the same manner. In this experiment, the results of Comparative Examples 3-5 were set as 100 for evaluation purposes. The results of each evaluation are shown in Tables 5 and 6.

[0329] [Table 5]

[0330]

[0331] [Table 6]

[0332]

[0333] [Summary of Experiments 1 to 3]

[0334] From the results of Experiments 1 to 3 (Tables 1 to 6), it can be seen that for any tire size of 175, 195, or 225, when Ha>Hb, E* C >E* S When the above-mentioned Formula 1 and Formula 2 are satisfied, it is possible to provide a pneumatic tire in which uneven wear of the tread portion during high-speed running is sufficiently suppressed and which has excellent durability performance.

[0335] Then, it is shown that by satisfying the requirements specified in claim 2 and thereafter, it is possible to provide a tire in which the uneven wear resistance and durability of the tread portion during high-speed running are further improved.

[0336] On the other hand, it is shown that when the above Ha>Hb, E* C >E* S When any one of Formula 1 and Formula 2 is not satisfied, uneven wear during high-speed running cannot be sufficiently suppressed, and excellent durability performance cannot be sufficiently achieved.

[0337] [Experiment 4]

[0338] Next, three tires (Examples 4-1 to 4-3) were produced using the same formulation, with no significant difference in the relationship between the virtual volume V and the cross-sectional width Wt, and were evaluated in the same manner. Here, in addition to the aforementioned evaluations of uneven wear resistance and durability, rolling resistance was also evaluated.

[0339] Specifically, each test tire was mounted on all wheels of a vehicle (a domestically produced FF car with a displacement of 2000cc), filled with air to an internal pressure of 250kPa, and then driven on a dry road test course. After completing a 10km run at 100km / h, the accelerator was released, and the distance from the time the accelerator was released until the vehicle came to a stop was measured as rolling resistance during high-speed driving. A larger value indicates a longer distance from the time the accelerator was released until the vehicle came to a stop, and a lower steady-state rolling resistance.

[0340] The results from Example 4-3 were then set to 100 and indexed using the following formula to relatively evaluate rolling resistance during high-speed driving. A larger value indicates a longer distance from accelerator release to vehicle stop, lower rolling resistance in steady state, and higher fuel efficiency. Table 7 shows the evaluation results.

[0341] Rolling resistance = [(measurement result of test tire) / (measurement result of Example 4-3)] × 100

[0342] Then, the evaluation results were totaled to obtain a comprehensive evaluation, similar to Experiments 1 to 3. Table 7 shows the results of each evaluation.

[0343] [Table 7]

[0344]

[0345]

[0346] Table 7 shows that when there is no big difference in the relationship between the imaginary volume V and the cross-sectional width Wt, as the cross-sectional width Wt becomes smaller, such as from less than 205 mm to less than 200 mm, and as the flatness rate increases, the uneven wear resistance and durability during high-speed driving are further improved, and significant effects are shown.

[0347] 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 scope of the same or equivalent to the present invention.

[0348] The present invention (1) is:

[0349] A pneumatic tire having side portions and bead portions, wherein:

[0350] Ha>Hb, wherein, in a meridian cross section, the distance from the bead base line to the widthwise outer side of the bead portion at the joint surface between the side portion and the bead portion is Ha (mm), and the distance to the widthwise inner side is Hb (mm);

[0351] E*S <E* C , wherein the composite elastic modulus of the side portion measured at 70°C, a frequency of 10 Hz, an initial strain of 5% and a dynamic strain rate of 1% is E* S (MPa), the composite elastic modulus of the edge portion is E* C (MPa); and

[0352] The tire satisfies the following equations 1 and 2:

[0353] 1600≤(Dt 2 ×π / 4) / Wt≦2827.4···Equation 1

[0354] [(V+1.5×10 7 ) / Wt]≦2.88×10 5 Formula 2,

[0355] Wherein, when the tire is mounted on a standardized rim and the internal pressure is 250 kPa, the cross-sectional width of the tire is Wt (mm), the outer diameter is Dt (mm), and the volume of the space occupied by the tire is the imaginary volume V (mm 3 ).

[0356] The present invention (2) is the pneumatic tire according to the present invention (1), wherein the following formula 3 is satisfied:

[0357] [(V+2.0×10 7 ) / Wt]≦2.88×10 5 ···Formula 3.

[0358] The present invention (3) is the pneumatic tire according to the present invention (2), wherein the following formula 4 is satisfied:

[0359] [(V+2.5×10 7 ) / Wt]≦2.88×10 5 ···Formula 4.

[0360] The present invention (4) is a pneumatic tire as any combination of the present inventions (1) to (3), wherein, when the outer diameter of the tire is Dt (mm) and the cross-sectional height of the tire is Ht (mm), and when the tire is mounted on a standardized rim and the internal pressure is 250 kPa, (Dt-2×Ht) is 470 (mm) or more.

[0361] The present invention (5) is a pneumatic tire as any combination of the present inventions (1) to (4), wherein the loss tangent (tanδ) of the side portion measured under the conditions of 70°C, a frequency of 10 Hz, an initial strain of 5% and a dynamic strain rate of 1% is less than 0.095.

[0362] The present invention (6) is the pneumatic tire according to the present invention (5), wherein tan δ is 0.090 or less.

[0363] The present invention (7) is a pneumatic tire according to any combination of the present inventions (1) to (6), wherein the aspect ratio is 40% or more.

[0364] The present invention (8) is a pneumatic tire as described in the present invention (1) to (7), wherein the aspect ratio is 45% or more.

[0365] The present invention (9) is a pneumatic tire as described in the present invention (1) to (8), wherein the aspect ratio is 47.5% or more.

[0366] The present invention (10) is a pneumatic tire according to the present invention (9), wherein the aspect ratio is 50% or more.

[0367] The present invention (11) is a pneumatic tire according to any combination of the present inventions (1) to (10), wherein the following formula 5 is satisfied:

[0368] (E* C -E* S ) / Wt>0.04×10 -1 ···Formula 5.

[0369] The present invention (12) is the pneumatic tire according to the present invention (11), wherein the following formula 6 is satisfied:

[0370] (E* C -E* S ) / Wt>0.10×10 -1 ···Formula 6.

[0371] The present invention (13) is a pneumatic tire according to any combination of the present inventions (1) to (12), wherein E* C It is 6.1 MPa or more and 8.3 MPa or less.

[0372] The present invention (14) is a pneumatic tire according to any combination of the present inventions (1) to (13), wherein the following formula 7 is satisfied:

[0373] (Ha-Hb) / Wt>0.04···Formula 7.

[0374] The present invention (15) is the pneumatic tire according to the present invention (14), wherein the following formula 8 is satisfied:

[0375] (Ha-Hb) / Wt>0.10···Formula 8.

[0376] The present invention (16) is a pneumatic tire as any combination of the present inventions (1) to (15), wherein a plurality of circumferential grooves are formed in the tread portion, and the total cross-sectional area of ​​the plurality of circumferential grooves is 10% to 30% of the cross-sectional area of ​​the tread portion.

[0377] The present invention (17) is a pneumatic tire as any combination of the present inventions (1) to (16), wherein a plurality of lateral grooves extending in the axial direction of the tire are formed in the tread portion, and the total volume of the plurality of lateral grooves is 2.0% to 5.0% of the volume of the tread portion.

[0378] The present invention (18) is a pneumatic tire according to any combination of the present inventions (1) to (17), wherein the loss tangent (tan δ) of the side portion measured under the conditions of 70° C., a frequency of 10 Hz, an initial strain of 5% and a dynamic strain rate of 1% and the thickness Ts (mm) of the side portion measured at the maximum width position satisfy the following formula 9:

[0379] tanδ×Ts>0.40···Equation 9.

[0380] The present invention (19) is the pneumatic tire according to the present invention (18), wherein the following formula 10 is satisfied:

[0381] tanδ×Ts>0.45···Equation 10.

[0382] The present invention (20) is a pneumatic tire as any combination of the present inventions (1) to (19), wherein Dt is less than 685 (mm), where Dt (mm) is the outer diameter of the tire when the tire is mounted on a standardized rim and the internal pressure is 250 kPa.

[0383] The present invention (21) is a pneumatic tire according to any combination of the present inventions (1) to (20), wherein the cross-sectional width Wt (mm) is less than 205 mm.

[0384] The present invention (22) is the pneumatic tire according to the present invention (21), wherein the cross-sectional width Wt (mm) is less than 200 mm.

[0385] The present invention (23) is a pneumatic tire according to any combination of the present inventions (1) to (22), which is a pneumatic tire for passenger vehicles.

[0386] [Description of Reference Signs]

[0387] 1 tire

[0388] 2 Side

[0389] 3. Edge

[0390] 4 Bead core

[0391] 5 Carcass ply

[0392] 6 Bead Apex

[0393] 7 Lining

Claims

1. A pneumatic tire having side portions and bead portions, wherein: Ha>Hb, wherein, in a meridian cross section, the distance from the bead base line to the widthwise outer side of the bead portion at the joint surface between the side portion and the bead portion is Ha (mm), and the distance to the widthwise inner side is Hb (mm); E* S <E* C , wherein the composite elastic modulus of the side portion measured at 70°C, a frequency of 10 Hz, an initial strain of 5% and a dynamic strain rate of 1% is E* S (MPa), the composite elastic modulus of the edge portion is E* C (MPa); and The tire satisfies the following equations 1 and 2: 1600≤(Dt 2 ×π / 4) / Wt≦2827.4···Equation 1 [(V+1.5×10 7 ) / Wt]≦2.88×10 5 Formula 2, Wherein, when the tire is mounted on a standardized rim and the internal pressure is 250 kPa, the cross-sectional width of the tire is Wt (mm), the outer diameter is Dt (mm), and the volume of the space occupied by the tire is the imaginary volume V (mm 3 ).

2. The pneumatic tire according to claim 1, wherein: Satisfies the following formula 3: [(V+2.0×10 7 ) / Wt]≦2.88×10 5 ···Formula 3.

3. The pneumatic tire according to claim 2, wherein: Satisfies the following formula 4: [(V+2.5×10 7 ) / Wt]≦2.88×10 5 ···Formula 4.

4. The pneumatic tire according to any one of claims 1 to 3, wherein When the outer diameter of the tire is Dt (mm) and the cross-sectional height of the tire is Ht (mm), and when the tire is mounted on a standardized rim and the internal pressure is 250 kPa, (Dt-2×Ht) is 470 (mm) or more. The pneumatic tire according to any one of claims 1 to 4, wherein the loss tangent (tan δ) of the side portion measured under the conditions of 70°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1% is 0.095 or less.

6. The pneumatic tire according to claim 5, wherein: The tan δ is 0.090 or less. 7 . The pneumatic tire according to claim 1 , wherein the pneumatic tire has an aspect ratio of 40% or more.

8. The pneumatic tire according to claim 7, wherein the aspect ratio is 45% or more.

9. The pneumatic tire according to claim 8, wherein the aspect ratio is 47.5% or more.

10. The pneumatic tire according to claim 9, wherein the aspect ratio is 50% or more.

11. The pneumatic tire according to any one of claims 1 to 10, wherein: The following formula 5 is satisfied: (E* C -E* S ) / Wt>0.04×10 -1 ...Equation 5.

12. The pneumatic tire according to claim 11, wherein The following formula 6 is satisfied: (E* C -E* S ) / Wt>0.10×10 -1 ...Equation 6.

13. The pneumatic tire according to any one of claims 1 to 12, wherein: E* C It is 6.1 MPa or more and 8.3 MPa or less.

14. The pneumatic tire according to any one of claims 1 to 13, wherein The following formula 7 is satisfied: (Ha-Hb) / Wt>0.04···Formula 7.

15. The pneumatic tire according to claim 14, wherein: The following formula 8 is satisfied: (Ha-Hb) / Wt>0.10···Formula 8.

16. The pneumatic tire according to any one of claims 1 to 15, wherein A plurality of circumferential grooves are formed in a tread portion, and a total cross-sectional area of ​​the plurality of circumferential grooves is 10% to 30% of a cross-sectional area of ​​the tread portion.

17. The pneumatic tire according to any one of claims 1 to 16, wherein: A plurality of lateral grooves extending in the tire axial direction are formed in the tread portion, and a total volume of the plurality of lateral grooves is 2.0% to 5.0% of the volume of the tread portion.

18. The pneumatic tire according to any one of claims 1 to 17, wherein The loss tangent (tan δ) of the side portion measured under the conditions of 70° C., a frequency of 10 Hz, an initial strain of 5% and a dynamic strain rate of 1% and the thickness Ts (mm) of the side portion measured at the maximum width position satisfy the following formula 9: tanδ×Ts>0.40···Equation 9.

19. The pneumatic tire according to claim 18, wherein: The following formula 10 is satisfied: tanδ×Ts>0.45···Equation 10.

20. The pneumatic tire according to any one of claims 1 to 19, wherein Dt is less than 685 (mm), where Dt (mm) is the outer diameter of the tire when the tire is mounted on a standardized rim and the internal pressure is 250 kPa.

21. The pneumatic tire according to any one of claims 1 to 20, wherein The cross-sectional width Wt (mm) is less than 205 mm.

22. The pneumatic tire according to claim 21, wherein: The cross-sectional width Wt (mm) is less than 200 mm.

23. The pneumatic tire according to any one of claims 1 to 22, which is a pneumatic tire for a passenger vehicle.

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