Pneumatic tire

Abstract

Provided is a pneumatic tire having sufficiently reduced rolling resistance during high-speed running and having sufficiently improved durability. The pneumatic tire has a tread portion, at least one layer of the rubber layers forming the tread portion is formed of a rubber composition having a rubber component containing styrene-butadiene rubber and isoprene-based rubber and having a loss tangent (30°C tan δ) of 0.14 or less, measured at 30°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%; and when Wt (mm) defined as the cross-sectional width, Dt (mm) defined as the outer diameter, and a virtual volume V (mm 3 ) defined as the volume of the space occupied by the tire are defined in a state where the tire is mounted on a standard rim and the internal pressure of the tire is 250 kPa, the pneumatic tire satisfies the following (Formula 1) and (Formula 2).1600 ≦ (Dt 2 × π / 4) / Wt ≦ 2827.4 ··· (Formula 1)[(V + 1.5 × 10 7 ) / Wt] ≦ 2.88 × 10 5 ··· (Formula 2).

Description

TECHNICAL FIELD

[0001] The present application relates to a pneumatic tire. BACKGROUND

[0002] In recent years, the demand for fuel efficiency of a motor vehicle has been increasing from the viewpoint of growing concern for environmental problems and economic efficiency, and there is a strong demand for improvement in fuel efficiency of a pneumatic tire (hereinafter, simply referred to as "tire") installed in a motor vehicle.

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

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

[0005] [Patent Documents]

[0006] [Patent Documents]

[0007] [Patent Document 1] JP 2018-178034 A

[0008] [Patent Document 2] JP 2019-089911 A

[0009] [Patent Document 3] WO 2018 / 186367 A

[0010] [Patent Document 4] JP 2019-206643 A SUMMARY

[0011] [Problems to be Solved by the Invention]

[0012] However, it cannot be said that the rolling resistance during high-speed running of a tire manufactured by the above-described conventional technology is sufficiently reduced, and it is desired to further reduce it. Also, it cannot be said that these tires have sufficient durability.

[0013] Therefore, an object of the present application is to provide a pneumatic tire in which the rolling resistance during high-speed running is sufficiently reduced, and in which the durability is sufficiently improved.

[0014] [Means for Solving the Problems]

[0015] The present inventors have intensively studied a solution to the above-described problems, and as a result, have found that the above-described problems can be solved by the disclosure described below, and have completed the present application.

[0016] The present application is:

[0017] A pneumatic tire having a tread portion, wherein

[0018] at least one layer of the rubber layer forming the tread portion is formed of a rubber composition having a rubber component containing styrene-butadiene rubber and isoprene-based rubber and a loss tangent (30°C tan δ) of 0.14 or less measured at 30°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%; and

[0019] When a cross-sectional width of the tire in a state where the tire is mounted on a standard rim and an internal pressure is 250 kPa is Wt (mm), an outer diameter is Dt (mm), and a volume of a space occupied by the tire is a virtual volume V (mm 3 ), the tire satisfies the following (Formula 1) and (Formula 2) :

[0020] 1600 ≦ (Dt 2 x π / 4) / Wt ≦ 2827.4 ··· (Formula 1)

[0021] [(V + 1.5 x 10 7 ) / Wt] ≦ 2.88 x 10 5 ··· (Formula 2)

[0022] [Effects of the Invention]

[0023] According to the present application, it is possible to provide a pneumatic tire in which the rolling resistance during high-speed running is sufficiently reduced and the durability is sufficiently improved. DETAILED DESCRIPTION

[0024] [1] Features of the Tire of the Invention

[0025] First, the features of the tire of the present application will be described.

[0026] 1. SUMMARY

[0027] The tire of the present application is characterized in that at least one layer of the rubber layer forming the tread portion is formed of a rubber composition having a rubber component containing styrene-butadiene rubber and isoprene-based rubber and a loss tangent (30°C tan δ) of 0.14 or less measured at 30°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%.

[0028] The tire of the present application is further characterized in that when a cross-sectional width of the tire in a state where the tire is mounted on a standard rim and an internal pressure is 250 kPa is Wt (mm), an outer diameter is Dt (mm), and a volume of a space occupied by the tire is a virtual volume V (mm 3 ), the tire satisfies the following (Formula 1) and (Formula 2) :

[0029] 1600 ≦ (Dt 2 x π / 4) / Wt ≦ 2827.4 ··· (Formula 1)

[0030] [(V+1.5×10 7 ) / Wt]≦2.88×10 5 ...(Equation 2)

[0031] The physical properties of the rubber composition forming the tread and the shape of the tire have the above-mentioned characteristics, thereby providing a tire with sufficiently reduced rolling resistance and sufficiently improved durability during high-speed driving.

[0032] In the above description, "standard rim" refers to the rim defined for each tire within the standard system upon which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Association), it is the standard rim of applicable size described in the "JATMA YEAR BOOK"; in the case of ETRTO (European Tire and Rim Technical Organization), it is the "Measuring Rim" described in the "Standards Manual"; and in the case of TRA (The Tire and Rim Association, Inc.), it is the "Design Rim" described in the "YEARBOOK". In the case of 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 leak air between the rim and the tire, has the smallest rim diameter, and then the narrowest rim width.

[0033] Furthermore, the tire's outer diameter Dt is the outer diameter of the tire when mounted on a standard rim, with an internal pressure of 250 kPa, and under no-load conditions. The tire's cross-sectional width Wt (mm) is the width of the tire when mounted on a standard rim, with an internal pressure of 250 kPa, and under no-load conditions, and is calculated by excluding the distance of patterns, text, etc., on the tire sidewalls from the straight-line distance between all patterns, text, etc., on the tire sidewalls (the total width of the tire).

[0034] In addition, the virtual volume V (mm) of the tire 3 Specifically, the following formulas can be used to calculate the tire's outer diameter Dt (mm), tire section height (distance from the bottom of the bead to the outermost surface of the tread; half the difference between the tire's outer diameter and the rim's nominal diameter) Ht (mm), and tire section width Wt (mm), when the tire is mounted on a standard rim with an internal pressure of 250 kPa and no load applied:

[0035] V = [(Dt / 2) 2 - {(Dt / 2) - Ht} 2 ] x π x Wt.

[0036] 2. Mechanism of effectuation in the tire of the present invention

[0037] The mechanism of effectuation in the tire of the present invention, i.e., the mechanism by which the rolling resistance at high speed is sufficiently reduced and the durability is sufficiently improved, is presumed as follows.

[0038] (1) Tire shape

[0039] As described above, in the present invention, the cross-sectional width Wt (mm) and the outer diameter Dt (mm) of the tire are set to satisfy 1600 ≦ (Dt 2 x π / 4) / Wt ≦ 2827.4 (Formula 1).

[0040] By increasing the area [(Dt 2 x π) = (Dt 2 x π / 4)] from the lateral observation of the tire with respect to the cross-sectional width Wt of the tire, and satisfying the numerical range prescribed in Formula 1, the number of repetitions of deformation per unit time is reduced, as a result, the friction between the tread portion and the road surface is reduced, and this is believed to enable low rolling resistance. In Formula 1, (Dt 2 x π / 4) / Wt is more preferably 1700 or greater, further preferably 1735 or greater, further preferably 1737 or greater, further preferably 1749 or greater, further preferably 1751 or greater, further preferably 1753 or greater, further preferably 1758 or greater, further preferably 1760 or greater, further preferably 1787 or greater, further preferably 1801 or greater, further preferably 1818 or greater, further preferably 1853 or greater, further preferably 1856 or greater, further preferably 1864 or greater, further preferably 1865 or greater, further preferably 1963.5 or greater, further preferably 2008 or greater, further preferably 2010 or greater, further preferably 2015 or greater, further preferably 2016 or greater, further preferably 2018 or greater, further preferably 2031 or greater.

[0041] However, in such a narrow tire, the centrifugal force during high speed running increases, and there is a risk that the tire radius will significantly increase during rolling, or there is a risk that the tread portion will be rounded and the amount of deformation will increase.

[0042] Furthermore, as the outer diameter increases, the tread portion is stretched and weakened, and as the outer diameter increases, the increase in the amount of deformation of the tread portion can damage the tread portion.

[0043] Therefore, in the present application, the virtual volume V (mm 3 ) and the cross-sectional width Wt (mm) of the tire are set to satisfy [(V + 1.5 x 10 7 ) / Wt] ≦ 2.88 x 10 5 (Formula 2).

[0044] Thus, it is considered that by reducing the virtual volume V of the tire according to the reduction of the cross-sectional width Wt of the tire, and reducing the volume of the tire itself, the increase in the outer diameter due to the expansion of the internal air can be suppressed, and the deformation of the tread portion can be reduced, and the heat generation property can be reduced. Furthermore, since the increase in the outer diameter can be suppressed, the tread is less likely to be weakened, and it is considered that the damage resistance is improved.

[0045] [(V + 1.5 x 10 7 ) / Wt] is more preferably 2.87 x 10 5 Further preferably, [(V + 1.5 x 10 5 ) / Wt] is 2.86 x 10 5 Further preferably, [(V + 1.5 x 10 5 ) / Wt] is 2.60 x 10 5 Further preferably, [(V + 1.5 x 10 5 ) / Wt] is 2.54 x 10 5 Further preferably, [(V + 1.5 x 10 5 ) / Wt] is 2.47 x 10 5 Further preferably, [(V + 1.5 x 10 5 ) / Wt] is 2.42 x 10 5 Further preferably, [(V + 1.5 x 10 5 ) / Wt] is 2.26 x 10 5 Further preferably, [(V + 1.5 x 10 5 ) / Wt] is 2.20 x 10 5 Further preferably, [(V + 1.5 x 10 5 ) / Wt] is 2.16 x 10 5 .

[0046] At this time, more preferably [(V + 2.0 x 10 7 ) / Wt] ≦ 2.88 x 10 5 (Formula 3), further preferably [(V + 2.5 x 10 7 ) / Wt] ≦ 2.88 x 10 5 (Formula 4).

[0047] The above [(V + 2.0 x 10 7) / Wt] is further preferably 2.83 x 10 5 ) / Wt] is further preferably 2.79 x 10 5 ) / Wt] is further preferably 2.77 x 10 5 ) / Wt] is further preferably 2.75 x 10 5 ) / Wt] is further preferably 2.64 x 10 5 ) / Wt] is further preferably 2.47 x 10 5 ) / Wt] is further preferably 2.46 x 10 5 ) / Wt] is further preferably 2.45 x 10 5 ) / Wt] is further preferably 2.44 x 10 5 ) / Wt] is further preferably 2.43 x 10

[0048] Further, [(V + 2.5 x 10 7 ) / Wt] is further preferably 2.86 x 10 5 ) / Wt] is further preferably 2.75 x 10 5 ) / Wt] is further preferably 2.74 x 10 5 ) / Wt] is further preferably 2.73 x 10 5 ) / Wt] is further preferably 2.71 x 10 5 ) / Wt] is further preferably 2.70 x 10 5 ) / Wt] is further preferably 2.69 x 10 5 ) / Wt] is further preferably 2.68 x 10 5 ) / Wt] is further preferably 2.43 x 10

[0049] (2) Rubber composition forming the tread portion

[0050] In the present application, at least one layer of the rubber layer forming the tread portion is made of a rubber composition having a rubber component containing styrene-butadiene rubber and isoprene-based rubber. As a result, the styrene-butadiene rubber phase and the isoprene-based rubber phase can be phase-separated and entangled with each other, thereby reducing distortion inside the rubber.

[0051] Further, by setting the loss tangent (30°C tan δ) of the rubber composition measured at 30°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1% to be 0.14 or less, the heat generation at the tread portion can be reduced; and in combination with the fact that distortion inside the rubber can be reduced, temperature rise of the tire can be suppressed, durability of the rubber composition itself can be suppressed from decreasing, and increase in diameter with temperature rise can be suppressed, damage to the tire can be prevented and durability can be improved.

[0052] The 30°C tan δ is more preferably 0.12 or less, and further preferably 0.10 or less.

[0053] The measurement of the 30°C tan δ described above is performed on rubber cut out from the radially outer side of at least the bottom of the tire groove (preferably from the radially outer side of half the depth of the deepest circumferential groove). Specifically, the measurement is performed using a viscoelasticity measuring device such as "Eplexor (registered trademark)" manufactured by GABO.

[0054] When the tread portion is formed of a plurality of rubber layers and the innermost layer is a base rubber layer and the other layers are cap rubber layers, the rubber composition is preferably used for the cap rubber layer. Among the cap rubber layers, it is particularly preferable to use it for the outermost layer.

[0055] [2] More preferable embodiments of the tire of the present application.

[0056] The tire of the present application can achieve greater effects by adopting the following embodiments.

[0057] 1. Aspect ratio

[0058] The tire of the present application is preferably a tire having an aspect ratio of 40% or more, whereby the height of the side portion of the tire can be increased to reduce the contribution of heat generation in the tread portion and the deformation of the tire can be made uniform throughout the tire, and the total heat generation of the tire can be sufficiently reduced. As a result, the rolling resistance during high-speed running can be further reduced, and the durability of the tire can be further improved.

[0059] The aspect ratio (%) described above can be obtained using the cross-sectional height Ht (mm) and the cross-sectional width Wt (mm) of the tire at an internal pressure of 250 kPa by the following formula:

[0060] (Ht / Wt) x 100 (%).

[0061] The aspect ratio described above is more preferably 44% or more, further preferably 45% or more, further preferably 47.5% or more, further preferably 48% or more, further preferably 49% or more, further preferably 50% or more, further preferably 52.5% or more, further preferably 55% or more, further preferably 57% or more, further preferably 59% or more. The upper limit is not particularly limited, and is, for example, 100% or less.

[0062] 2. Relationship between loss tangent (30°C tan δ) and cross-sectional width Wt (mm)

[0063] As the cross-sectional width Wt increases, the contribution of heat generation from the tread increases, and heat generation becomes more difficult to control. Therefore, the inventors studied the relationship between the loss tangent (30°C tanδ) and the cross-sectional width Wt (mm) and found that if 30°C tanδ × Wt ≤ 30.0, heat generation can be controlled according to the width, further reducing rolling resistance during high-speed driving and further improving tire durability. More preferably, 30°C tanδ × Wt is 28.3 or less, more preferably 28.0 or less, more preferably 27.8 or less, more preferably 27.5 or less, more preferably 27.0 or less, and more preferably 25.7 or less.

[0064] Furthermore, it was found that it is even more preferable to satisfy tanδ×Wt≦25.0 at 30℃. tanδ×Wt at 30℃ is further preferably 24.8 or less, further preferably 24.7 or less, further preferably 24.2 or less, further preferably 23.9 or less, further preferably 22.6 or less, further preferably 21.9 or less, further preferably 21.3 or less, further preferably 19.8 or less, and further preferably 17.7 or less.

[0065] 3. Tire tread grooves

[0066] The tire of the present invention has circumferential grooves extending continuously in the tire circumferential direction on the tread. The groove width L is located at 80% of the maximum depth of the circumferential groove. 80 The ratio of the groove width L0 of the circumferential groove at the contact surface of the tread (L) 80 The ratio (L0) is preferably 0.3-0.7. As a result, movement of the entire contact patch on the bottom surface of the tread portion can be suppressed, thereby effectively suppressing uneven wear of the tread portion during high-speed driving and improving durability. This ratio is more preferably 0.35-0.65, further preferably 0.40-0.60, and particularly preferably 0.45-0.55. The circumferential groove can be a groove extending continuously in the tire circumferential direction, and non-linear grooves such as serrated grooves and wavy grooves are also included in the circumferential groove.

[0067] The above L0 and L 80 These refer to the straight-line distance (L0) between the ends of the grooves on the tread surface of the tire's circumferential grooves when the tire is mounted on a standard rim, with an internal pressure of 250 kPa and no load applied, and the minimum distance (L) between the groove walls at a location where the groove depth is 80%. 80 In simple terms, they can be obtained by placing the bead portion, with a radially cut cross-section of 2-4 cm in width, in a pressed state according to the rim width.

[0068] Preferably, the tread portion has a plurality of circumferential grooves, and the total sectional area of the plurality of circumferential grooves is 10 to 30% of the sectional area of the tread portion. It is considered that this makes it possible to suppress movement of the tread portion, and to suppress eccentric wear of the tread portion during high-speed running and to improve durability. It is more preferably 15 to 27%, further preferably 18 to 25%, and particularly preferably 21 to 23%.

[0069] The sectional area of the above circumferential groove refers to the total value of the areas formed by the straight lines connecting the end portions of the circumferential grooves of the tread portion and the groove walls in a tire mounted on a regular rim, having an internal pressure of 250 kPa, and in an unloaded state. In other words, they can be obtained by placing the bead portion of a sectional area of 2 to 4 cm in width cut in the radial direction in a pressed state according to the rim width.

[0070] In addition, preferably, the tread portion has a plurality of lateral grooves extending in the tire axial direction, and the total volume of the plurality of lateral grooves is 2.0 to 5.0% of the volume of the tread portion. It is considered that this makes it possible to suppress movement of the tread portion, to suppress eccentric wear of the tread portion, and to improve durability. It is more preferably 2.2 to 4.0%, further preferably 2.5 to 3.5%, and particularly preferably 2.7 to 3.0%.

[0071] The volume of the above lateral groove refers to the total volume formed by the surfaces connecting the end portions of the lateral grooves and the groove walls in a tire mounted on a regular rim, having an internal pressure of 250 kPa, and in an unloaded state. In other words, it can be obtained by calculating the volume of each lateral groove in a state in which the bead portion of a sectional area of 2 to 4 cm in width cut in the radial direction is pressed downward according to the rim width, and multiplying the volume by the number of grooves. In addition, the volume of the tread portion can be calculated by calculating the area excluding the portion of the lateral grooves from the above sectional area and multiplying the area by the outer diameter, and then finding the difference between the calculation result and the volume of the lateral grooves.

[0072] In order to suppress eccentric wear of the tread portion and further improve durability, preferably, the groove width ratio (Gw / Gd) of at least one of the lateral grooves, that is, the ratio of the groove width Gw to the groove depth Gd, is 0.50 to 0.80. The ratio is more preferably 0.53 to 0.77, further preferably 0.55 to 0.75, and particularly preferably 0.60 to 0.70.

[0073] The groove width and the groove depth of the above-mentioned lateral grooves are the maximum length in a straight line (perpendicular to the groove direction) connecting the tread surface end portions of the lateral grooves, and the maximum depth of the lateral grooves, respectively, in a tire in a state where the internal pressure is 250 kPa and no load is applied. In other words, they can be calculated in a state where a bead portion of a cross section having a width of 2 to 4 cm cut out in the radial direction is placed in a pressed state according to the rim width.

[0074] 4. Tire shape

[0075] In the tire of the present application, when the tire is mounted on a standard 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 649 mm or more, further preferably 658 mm or more, further preferably 663 mm or more, further preferably 664 mm or more, further preferably 665 mm or more, further preferably 672 mm or more, most preferably 673 mm or more.

[0076] On the other hand, it is preferably less than 843 mm, more preferably 734 mm or less, further preferably less than 725 mm, further preferably 718 mm or less, further preferably 717 mm or less, further preferably 716 mm or less, further preferably 713 mm or less, further preferably 710 mm or less, further preferably less than 707 mm, further preferably 693 mm or less, further preferably 691 mm or less, further preferably less than 685 mm, further preferably 684 mm or less, further preferably 680 mm or less, further preferably 679 mm or less, further preferably 674 mm or less.

[0077] 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, still more preferably 176 mm or more, still more preferably 177 mm or more, still more preferably 182 mm or more, still more preferably 183 mm or more, even more preferably 185 mm or more, most preferably 193 mm or more.

[0078] In another aspect, it is preferably less than 305 mm, more preferably less than 245 mm, further preferably 231 mm or less, further preferably 229 mm or less, further preferably 228 mm or less, further preferably 227 mm or less, further preferably 226 mm or less, further preferably 225 mm or less, further preferably less than 210 mm, further preferably less than 205 mm, further preferably 202 mm or less, further preferably 201 mm or less, further preferably 200 mm or less, further preferably less than 200 mm, further preferably 199 mm or less, further preferably 198 mm or less, further preferably 196 mm or less.

[0079] A 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 78 mm or more, further preferably 79 mm or more, further preferably 80 mm or more, further preferably 87 mm or more, further preferably 88 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, further preferably 99 mm or more.

[0080] In another aspect, it is preferably less than 180 mm, more preferably 117 mm or less, further preferably 113 mm or less, further preferably less than 112 mm, further preferably 105 mm or less, further preferably 101 mm or less, further preferably less than 101 mm.

[0081] A specific virtual volume V is preferably 13,000,000 mm 3 mm or more, more preferably 23,093,883 mm or more, further preferably 23,412,074 mm or more, further preferably 23,599,328 mm or more, further preferably 28,431,992 mm or more, further preferably 28,526,824 mm or more, further preferably 29,000,000 mm or more, further preferably 29,087,378 mm or more, further preferably 30,152,956 mm or more, further preferably 30,354,118 mm or more, further preferably 34,384,955 mm or more, further preferably 35,417,448 mm or more. 3 mm or more, more preferably 23,093,883 mm or more, further preferably 23,412,074 mm or more, further preferably 23,599,328 mm or more, further preferably 28,431,992 mm or more, further preferably 28,526,824 mm or more, further preferably 29,000,000 mm or more, further preferably 29,087,378 mm or more, further preferably 30,152,956 mm or more, further preferably 30,354,118 mm or more, further preferably 34,384,955 mm or more, further preferably 35,417,448 mm or more. 3 mm or more, more preferably 23,093,883 mm or more, further preferably 23,412,074 mm or more, further preferably 23,599,328 mm or more, further preferably 28,431,992 mm or more, further preferably 28,526,824 mm or more, further preferably 29,000,000 mm or more, further preferably 29,087,378 mm or more, further preferably 30,152,956 mm or more, further preferably 30,354,118 mm or more, further preferably 34,384,955 mm or more, further preferably 35,417,448 mm or more. 3 mm or more, more preferably 23,093,883 mm or more, further preferably 23,412,074 mm or more, further preferably 23,599,328 mm or more, further preferably 28,431,992 mm or more, further preferably 28,526,824 mm or more, further preferably 29,000,000 mm or more, further preferably 29,087,378 mm or more, further preferably 30,152,956 mm or more, further preferably 30,354,118 mm or more, further preferably 34,384,955 mm or more, further preferably 35,417,448 mm or more. 3 mm or more, more preferably 23,093,883 mm or more, further preferably 23,412,074 mm or more, further preferably 23,599,328 mm or more, further preferably 28,431,992 mm or more, further preferably 28,526,824 mm or more, further preferably 29,000,000 mm or more, further preferably 29,087,378 mm or more, further preferably 30,152,956 mm or more, further preferably 30,354,118 mm or more, further preferably 34,384,955 mm or more, further preferably 35,417,448 mm or more. 3 mm or more, more preferably 23,093,883 mm or more, further preferably 23,412,074 mm or more, further preferably 23,599,328 mm or more, further preferably 28,431,992 mm or more, further preferably 28,526,824 mm or more, further preferably 29,000,000 mm or more, further preferably 29,087,378 mm or more, further preferably 30,152,956 mm or more, further preferably 30,354,118 mm or more, further preferably 34,384,955 mm or more, further preferably 35,417,448 mm or more. 3 mm or more, more preferably 23,093,883 mm or more, further preferably 23,412,074 mm or more, further preferably 23,599,328 mm or more, further preferably 28,431,992 mm or more, further preferably 28,526,824 mm or more, further preferably 29,000,000 mm or more, further preferably 29,087,378 mm or more, further preferably 30,152,956 mm or more, further preferably 30,354,118 mm or more, further preferably 34,384,955 mm or more, further preferably 35,417,448 mm or more. 3 mm or more, more preferably 23,093,883 mm or more, further preferably 23,412,074 mm or more, further preferably 23,599,328 mm or more, further preferably 28,431,992 mm or more, further preferably 28,526,824 mm or more, further preferably 29,000,000 mm or more, further preferably 29,087,378 mm or more, further preferably 30,152,956 mm or more, further preferably 30,354,118 mm or more, further preferably 34,384,955 mm or more, further preferably 35,417,448 mm or more. 3 mm or more, more preferably 23,093,883 mm or more, further preferably 23,412,074 mm or more, further preferably 23,599,328 mm or more, further preferably 28,431,992 mm or more, further preferably 28,526,824 mm or more, further preferably 29,000,000 mm or more, further preferably 29,087,378 mm or more, further preferably 30,152,956 mm or more, further preferably 30,354,118 mm or more, further preferably 34,384,955 mm or more, further preferably 35,417,448 mm or more. 3 mm or more, more preferably 23,093,883 mm or more, further preferably 23,412,074 mm or more, further preferably 23,599,328 mm or more, further preferably 28,431,992 mm or more, further preferably 28,526,824 mm or more, further preferably 29,000,000 mm or more, further preferably 29,087,378 mm or more, further preferably 30,152,956 mm or more, further preferably 30,354,118 mm or more, further preferably 34,384,955 mm or more, further preferably 35,417,448 mm or more. 3 mm or more, more preferably 23,093,883 mm or more, further preferably 23,412,074 mm or more, further preferably 23,599,328 mm or more, further preferably 28,431,992 mm or more, further preferably 28,526,824 mm or more, further preferably 29,000,000 mm or more, further preferably 29,087,378 mm or more, further preferably 30,152,956 mm or more, further preferably 30,354,118 mm or more, further preferably 34,384,955 mm or more, further preferably 35,417,448 mm or more. 3Further preferably, the above is 35,785,417 mm 3 Further preferably, the above is 35,954,077 mm 3 Further preferably, the above is 36,000,000 mm 3 Further preferably, the above is 36,203,610 mm 3 Further preferably, the above is 37,040,131 mm 3 Further preferably, the above is 37,040,131 mm

[0082] Further preferably, the above is 37,040,131 mm 3 Further preferably, the above is 37,040,131 mm 3 Further preferably, the above is 37,040,131 mm 3 Further preferably, the above is 37,040,131 mm 3 Further preferably, the above is 37,040,131 mm 3 Further preferably, the above is 37,040,131 mm 3 Further preferably, the above is 37,040,131 mm 3 .

[0083] Further preferably, the above is 37,040,131 mm

[0084] Further preferably, the above is 37,040,131 mm

[0085] [3] Embodiment

[0086] Hereinafter, the present application will be specifically described based on an embodiment.

[0087] 1. Rubber composition forming the tread portion

[0088] The rubber composition forming the tread portion of the tire of the present application can be obtained by appropriately adjusting the kinds and amounts of various compounding materials such as the rubber component, the filler, the softener, the vulcanizing agent, and the vulcanization accelerator as described below.

[0089] (1) Rubber component

[0090] In the present embodiment, as the rubber component, a rubber (polymer) generally used for manufacturing tires, such as styrene-butadiene rubber (SBR), isoprene rubber, butadiene rubber (BR), nitrile rubber (NBR), can be used. Among them, use of styrene-butadiene rubber (SBR) and isoprene rubber is preferred. Since these rubbers can be entangled with each other by phase separation of respective rubber phases, it is possible to reduce the twist inside the rubber.

[0091] (a) SBR

[0092] From the viewpoint of wet grip performance, the content of SBR in the rubber component 100 parts by mass is, for example, preferably more than 5 parts by mass, more preferably more than 10 parts by mass, and further preferably 20 parts by mass or more, 50 parts by mass or more. On the other hand, from the viewpoint of heat generation during high-speed running, it is preferably less than 100 parts by mass, and more preferably 70 parts by mass or less. The weight average molecular weight of SBR is, for example, more than 100,000 and less than 2 million. For example, from the viewpoint of obtaining good wet grip performance, the styrene content of SBR is preferably more than 5% by mass, more preferably more than 10% by mass, and even more preferably more than 20% by mass. On the other hand, from the viewpoint of heat generation during high-speed running and durability, it is preferably less than 50% by mass, more preferably less than 40% by mass, and further preferably less than 35% by mass. The vinyl bond content (amount of 1,2-bonded butadiene units) of SBR is, for example, more than 5% by mass and less than 70% by mass. The structure identification of SBR (determination of the styrene content and the vinyl bond content) can be performed using, for example, a device of the JNM-ECA series manufactured by JEOL Ltd.

[0093] SBR is not particularly limited, and, for example, emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), or the like can be used. SBR can be unmodified SBR or modified SBR.

[0094] The modified SBR can be any SBR having a functional group that interacts with a filler such as silica. Examples thereof include:

[0095] a terminal-modified SBR (a terminal-modified SBR having the above-described functional group on a terminal) in which at least one terminal of SBR is modified with a compound (a modifier) having the above-described functional group,

[0096] a main chain-modified SBR having the above-described functional group in a main chain,

[0097] a main chain-terminal-modified SBR (for example, a main chain-terminal-modified SBR in which a main chain has the above-described functional group and at least one terminal is modified with the above-described modifier), and

[0098] modified at the terminal end with a multifunctional compound having two or more epoxy groups and to which an epoxy group or a hydroxyl group has been introduced.

[0099] Examples of the above functional groups include amino, amido, silyl, alkoxysilyl, isocyanate, imino, imidazole, ureido, ether, carbonyl, oxycarbonyl, mercapto, sulfide, disulfide, sulfonyl, sulfinyl, thiocarbonyl, ammonium, imide, hydrazo, azo, diazo, carboxyl, nitrile, pyridyl, alkoxy, hydroxyl, oxyl, and epoxy. In addition, these functional groups can have substituents.

[0100] In addition, as the modified SBR, for example, an SBR modified with a compound (modifier) represented by the following formula can be used.

[0101] [Chemical Formula 1]

[0102]

[0103] In the formula, R 1 , R 2 , and R 3 are the same or different and represent an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group (-COOH), a mercapto group (-SH), or a derivative thereof. R 4 , R 5 , and R 4 are the same or different and represent a hydrogen atom or an alkyl group. R 5 , and R 5 may combine together with the nitrogen atom to form a ring structure. n represents an integer.

[0104] As the modified SBR modified with the compound (modifier) represented by the above formula, a solution polymerized styrene-butadiene rubber (S-SBR) in which the polymer terminal end (active terminal end) is modified with a compound represented by the above formula (such as the modified SBR described in JP-A-2010-111753) can be used.

[0105] As R 1 , R 2 , and R 3 , an alkoxy group (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms) is preferred. 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 further preferably 3. In addition, when R 4 , and R 5When combined with a nitrogen atom to form a ring structure, a 4- to 8-membered ring is preferred. Alkoxy also includes cycloalkoxy (e.g., cyclohexyloxy) and aryloxy (e.g., phenoxy, benzyloxy).

[0106] 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 with two or more.

[0107] Further, as the modified SBR, a modified SBR modified with the following compound (modifier) can also be used. Examples of the modifier include:

[0108] Polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerol triglycidyl ether, trimethylol ethane triglycidyl ether, trimethylol propane triglycidyl ether;

[0109] Polyglycidyl ethers of aromatic compounds having two or more phenolic groups such as diglycidylated bisphenol A;

[0110] Polyepoxy compounds such as 1,4-diglycidyl benzene, 1,3,5-triglycidyl benzene, polyepoxy liquid polybutadiene;

[0111] Epoxy group-containing tertiary amines such as 4,4'-diglycidyl-diphenylmethylamine, 4,4'-diglycidyl-dibenzylmethylamine;

[0112] Diglycidyl amino compounds such as diglycidyl aniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidyl o-toluidine, tetraglycidyl-m-xylylenediamine, tetraglycidyl-aminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidyl aminomethylcyclohexane, tetraglycidyl-1,3-bisaminomethylcyclohexane;

[0113] Amino-containing acid chlorides such as bis(1-methylpropyl)carbamoyl chloride, 4-morpholinocarbonyl chloride, 1-pyrrolidinocarbonyl chloride, N,N-dimethylcarbamoyl chloride, N,N-diethylcarbamoyl chloride;

[0114] Epoxy group-containing silane compounds such as 1,3-bis-(glycidyloxypropyl)-tetramethyldisiloxane, (3-glycidyloxypropyl)-pentamethyldisiloxane;

[0115] Silane compounds containing a sulfide 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;

[0116] N-substituted aziridine compounds such as ethyleneimine, propyleneimine;

[0117] Alkoxy silanes such as methyltriethoxysilane, N,N-bis(trimethylsilyl)-3- aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethyltriethoxysilane;

[0118] (Thio)benzophenone compounds having an amino group and / or a substituted amino group such as 4-N,N-dimethylaminobenzophenone, 4-N,N-di-t-butylaminobenzophenone, 4-N,N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(diphenylamino)benzophenone, and N,N,N',N'-bis-(tetraethylamino)benzophenone;

[0119] Benzaldehyde compounds having an amino group and / or a substituted amino group such as 4-N,N-dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, 4-N,N-diethylaminobenzaldehyde;

[0120] N-substituted pyrrolidones such as N-methyl-2-pyrrolidone, N-vinyl-2- pyrrolidone, N-phenyl-2-pyrrolidone, N-t-butyl-2-pyrrolidone, and N-methyl-5- methyl-2-pyrrolidone;

[0121] N-substituted piperidones such as N-methyl-2-piperidone, N-vinyl-2- piperidone, N-phenyl-2-piperidone;

[0122] N-substituted lactams such as N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-lauryllactam, N-vinyl-ω-lauryllactam, N-methyl-β-propiolactam, and N-phenyl-β-propiolactam; and

[0123] N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), tris-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-trione, N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3-diethyl-2-imidazolinone, 1-methyl-3-ethyl-2-imidazolinone, 4-N,N-dimethylaminophenylacetone, 4-N,N-diethylaminophenylacetone, 1,3-bis(diphenylamino)-2-propanone, 1,7-bis(methylethylamino)-4-heptanone. The modification with the above compounds (modifiers) can be carried out by known methods.

[0124] As the SBR, for example, SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Co., Ltd., Asahi Kasei Co., Ltd., Japan Seiko Co., Ltd., and the like can be used. The SBR can be used alone or in combination with two or more kinds.

[0125] (b) isoprene-based rubber

[0126] From the viewpoint of obtaining good low heat generation and durability during high-speed running, the content (total content) of the isoprene-based rubber in the rubber component 100 parts by mass is preferably more than 5 parts by mass, and more preferably more than 25 parts by mass. More preferably, it is 30 parts by mass or more, and even more preferably 40 parts by mass or more.

[0127] On the other hand, the upper limit of the content of the isoprene-based rubber is not particularly limited, but from the viewpoint of wet grip performance, it is preferably less than 100 parts by mass, and more preferably 70 parts by mass or less. Examples of the isoprene-based rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR.

[0128] As the NR, for example, SIR 20, RSS #3, TSR 20, and the like commonly used in the tire industry can be used. The IR is not particularly limited, and for example, IR 2200 and the like commonly used in the tire industry can be used. The modified NR includes deproteinized natural rubber (DPNR), high-purity natural rubber (UPNR), and the like. The modified NR includes epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), grafted natural rubber, and the like. The modified IR includes epoxidized isoprene rubber, hydrogenated isoprene rubber, grafted isoprene rubber, and the like. These can be used alone or in combination with two or more kinds.

[0129] (c) BR

[0130] The rubber composition can further contain BR as needed. In this case, the content of BR in 100 parts by mass of the rubber component is preferably greater than 5 parts by mass, more preferably 10 parts by mass or greater, from the viewpoint of abrasion resistance. On the other hand, the amount is preferably less than 100 parts by mass, more preferably less than 30 parts by mass, further preferably less than 20 parts by mass, from the viewpoint of rolling resistance during high-speed running. 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 mass% and less than 30 mass%. The cis content of BR is, for example, greater than 1 mass% and less than 98 mass%. The trans amount of BR is, for example, greater than 1 mass% and less than 60 mass%.

[0131] BR is not particularly limited, and BR having a high cis content (cis content of 90% or greater), BR having a low cis content, BR containing syndiotactic polybutadiene crystals, or the like can be used. BR can be unmodified BR or modified BR, and the modified BR includes modified BR into which the above-mentioned functional group is introduced. These can be used alone or in combination with two or more. The cis content can be measured by infrared absorption spectroscopy.

[0132] As BR, for example, the products of Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Japan Carbon Co., Ltd. can be used.

[0133] (d) Other rubber component

[0134] Further, as the other rubber component, the rubber composition can contain rubber (polymer) that is generally used in tire production, such as nitrile rubber (NBR).

[0135] (2) Extending material other than the rubber component

[0136] (a) Filler

[0137] In the present embodiment, the rubber composition preferably contains a filler. Specific examples of the filler include silica, carbon black, graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica. Among these, silica and carbon black can be preferably used as a reinforcing agent. In the case of using silica, it is preferable to use it in combination with a silane coupling agent.

[0138] (a-1) Silica

[0139] The rubber composition preferably contains silica. From the viewpoint of obtaining good durability, the BET specific surface area of the silica is preferably greater than 140 m 2 / g, more preferably greater than 160 m 2 / g. On the other hand, from the viewpoint of obtaining good rolling resistance during high-speed running, it is preferably less than 250 m 2 / g, more preferably less than 220 m 2 / g. The above BET specific surface area is a value of N2SA measured by the BET method according to ASTM D3037-93.

[0140] In the case of using silica as a filling reinforcing agent, from the viewpoint of obtaining good durability, the content of silica is preferably more than 35 parts by mass, more preferably more than 40 parts by mass, with respect to 100 parts by mass of the rubber component. On the other hand, from the viewpoint of obtaining good rolling resistance during high-speed running, it is preferably less than 70 parts by mass, more preferably less than 65 parts by mass, even more preferably less than 60 parts by mass, and less than 50 parts by mass.

[0141] 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.

[0142] As the silica, products of, for example, Degussa Corporation, Rhodia Corporation, Tosoh Silica Co., Ltd., Solvay Japan K.K., Tokuyama Corporation, and the like can be used.

[0143] (a-2) Silane Coupling Agent

[0144] The rubber composition preferably contains a silane coupling agent together with the silica. The silane coupling agent is not particularly limited. Examples of the silane coupling agent include:

[0145] Sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilyl ethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilyl ethyl)tetrasulfide, bis(2-triethoxysilyl ethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilyl ethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilyl ethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilyl ethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide;

[0146] Mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 2- mercaptoethyltriethoxysilane, NXT, NXT-Z manufactured by Momentive;

[0147] Vinyl-based silane coupling agents such as vinyltriethoxysilane, vinyltrimethoxysilane;

[0148] Amino-based silane coupling agents such as 3-aminopropyltriethoxysilane, 3- aminopropyltrimethoxysilane;

[0149] Glycidoxypropoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane;

[0150] Nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane, 3- nitropropyltriethoxysilane; and

[0151] Chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3- chloropropyltriethoxysilane. These can be used alone or in combination with two or more kinds.

[0152] As the silane coupling agent, for example, products of Degussa, Momentive, Shin-Etsu Silicone, Tokyo Chemical Industry, Azmax, and Dow Corning Toray can be used.

[0153] The content of the silane coupling agent is, for example, greater than 3 parts by mass and less than 25 parts by mass, and more preferably 10 parts by mass or more, with respect to 100 parts by mass of the silica.

[0154] (a-3) Carbon black

[0155] The rubber composition preferably contains carbon black. The content of the carbon black is, for example, greater than 1 part by mass and less than 200 parts by mass, and more preferably 15 parts by mass or more, with respect to 100 parts by mass of the rubber component.

[0156] The carbon black is not particularly limited, and examples thereof include furnace black (furnace process carbon black) such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF; acetylene black (acetylene carbon black); thermal black (thermal cracking process carbon black) such as FT and MT; channel black (channel process carbon black) such as EPC, MPC, and CC. These can be used alone or in combination with two or more kinds.

[0157] The nitrogen adsorption specific surface area (N2SA) of the carbon black is, for example, greater than 30 m 2 / g and less than 250 m 2The dibutyl phthalate (DBP) absorption of the 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 the carbon black is determined according to ASTM D4820-93, and the DBP absorption is determined according to ASTM D2414-93.

[0158] The specific carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercial products include, for example, products of Asahi Carbon Co., Cabot Japan K.K., Tokai Carbon Co., Mitsubishi Chemical Corporation, Lion Corporation, Shin Nikka Carbon Co., Columbia Carbon Co., and the like. These can be used alone or in combination with two or more.

[0159] (a-4) Other fillers

[0160] In addition to the above-described carbon black and silica, the rubber composition can contain fillers commonly used in the tire industry, such as graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica. The content of these is, for example, greater than 0.1 parts by mass and less than 200 parts by mass with respect to 100 parts by mass of the rubber component.

[0161] (b) Softening agent

[0162] The rubber composition can contain an oil (including an extender oil), a liquid rubber, or the like as a softening agent. The total content of these is preferably greater than 5 parts by mass, more preferably 10 parts by mass or more, with respect to 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 further preferably less than 30 parts by mass. The oil content also includes the amount of oil contained in the rubber (extender rubber).

[0163] Examples of the oil include mineral oil (commonly referred to as process oil), vegetable fat, or a mixture thereof. As the mineral oil (process oil), for example, paraffin-based process oil, aromatic process oil, naphthenic process oil, and the like can be used. Examples of the vegetable fat include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice oil, safflower oil, sesame oil, olive oil, sunflower seed oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. These can be used alone or in combination with two or more.

[0164] Specific examples of the operating oil (mineral oil) include products of Shodex Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Nippon Enerdy Co., Ltd., Olisoy Co., Ltd., H&R Co., Ltd., Toyokuni Seiyu Co., Ltd., Showa Shell Sekiyu Co., Ltd., Fuji Osako Co., Ltd., and the like.

[0165] The liquid rubber mentioned as the softening agent is a polymer that is in a liquid state at room temperature (25°C), and is a polymer having a monomer similar to a solid rubber as a constituent element. Examples of the liquid rubber include a farnesene-based polymer, a liquid diene-based polymer, and a hydrogenated additive thereof.

[0166] The farnesene-based polymer is a polymer obtained by polymerizing farnesene, and has a structural unit based on farnesene. Farnesene includes isomers such as a-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodec tetraene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene).

[0167] The farnesene-based polymer can be a homopolymer of farnesene (farnesene homopolymer) or a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer).

[0168] Examples of the liquid diene-based polymer include a liquid styrene-butadiene copolymer (liquid SBR), a liquid butadiene polymer (liquid BR), a liquid isoprene polymer (liquid IR), and a liquid styrene-isoprene copolymer (liquid SIR).

[0169] The liquid diene-based polymer has a weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) of, for example, greater than 1.0 x 10 3 and less than 2.0 x 10 5 In the present specification, the Mw of the liquid diene-based polymer is a value in terms of polystyrene measured by gel permeation chromatography (GPC).

[0170] The content of the liquid rubber (total content of the liquid farnesene-based polymer, the liquid diene-based polymer, and the like) is, for example, greater than 1 part by mass and less than 100 parts by mass with respect to 100 parts by mass of the rubber component.

[0171] As the liquid rubber, products of Kuraray Co., Ltd. and Cray Valley Co., Ltd. can be used, for example.

[0172] (c) Resin Component

[0173] Further, the rubber composition preferably contains a resin component as needed. The resin component can be solid or liquid at ordinary temperature, and specific examples of the resin component include styrene-based resins, benzofuran-based resins, terpene-based resins, C5 resins, C9 resins, C5C9 resins, acrylic-based resins, and the like. Two or more kinds of resin components can be used in combination. The content of the resin component is preferably more than 2 parts by mass and more preferably 3 parts by mass or more, and on the other hand, is preferably less than 45 parts by mass and more preferably less than 30 parts by mass, relative to 100 parts by mass of the rubber component.

[0174] The styrene-based resin is a polymer using a styrene-based monomer as a constituent monomer, and examples thereof include a polymer obtained by polymerizing a styrene-based monomer as a main component (50% by mass or more). Specifically, it includes a homopolymer obtained by polymerizing a styrene-based monomer (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, a-methylstyrene, p-methoxystyrene, p-t-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, and the like) individually, a copolymer obtained by copolymerizing two or more kinds of styrene-based monomers, and further includes a copolymer obtained by copolymerizing a styrene-based monomer and another monomer copolymerizable with the styrene-based monomer.

[0175] Examples of the above-mentioned other monomer include acrylonitriles such as acrylonitrile and methacrylonitrile; 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, isoprene), olefins (such as 1-butene, 1-pentene); a, b-unsaturated carboxylic acids and their anhydrides such as maleic anhydride.

[0176] As the benzofuran-based resin, a benzofuran-indene resin is preferably used. The benzofuran-indene resin is a resin containing benzofuran and indene as monomer components constituting the resin skeleton (main chain). Examples of monomer components contained in the skeleton other than benzofuran and indene include styrene, a-methylstyrene, methylindene, and vinyltoluene.

[0177] The content of the benzofuran-indene resin is, for example, more than 1.0 parts by mass and less than 50.0 parts by mass, relative to 100 parts by mass of the rubber component.

[0178] The benzofuran-indene resin has a hydroxyl value (OH value) of, for example, more than 15 mgKOH / g and less than 150 mgKOH / g. The OH value is the amount of potassium hydroxide required to neutralize the acetic acid combined with the hydroxyl group when 1 g of the resin is acetylated, and is expressed in milligrams. It is a value determined by potentiometric titration (JIS K 0070:1992).

[0179] The softening point of the benzofuran-indene resin is, for example, greater than 30°C and less than 160°C. The softening point is the temperature at which the ball falls when the softening point defined in JIS K 6220-1:2001 is measured with a ring-and-ball softening point measuring device.

[0180] Examples of the terpene-based resin include polyterpene, terpene phenol, and aromatic-modified terpene resin. The polyterpene is a resin obtained by polymerizing a terpene compound and its hydrogenate. The terpene compound is a hydrocarbon or its oxygen-containing derivative having a composition of (C5H8) n 10 16 15 24 20 32 Examples thereof include α-pinene, β-pinene, dipentene, limonene, myrcene, allo-ocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0181] Examples of the polyterpene include: terpene resins such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, and β-pinene / limonene resin made from the above-described terpene compounds; and hydrogenated terpene resins obtained by hydrogenating the terpene resins. Examples of the terpene phenol include: resins obtained by copolymerizing the above-described terpene compounds and phenol-based compounds, and resins obtained by hydrogenating the above-described resins. Specifically, a resin obtained by condensing the above-described terpene compounds, phenol-based compounds, and formalin can be exemplified. Examples of the phenol-based compounds include phenol, bisphenol A, cresol, and xylenol. Examples of the aromatic-modified terpene resin include resins obtained by modifying terpene resins with aromatic compounds, and resins obtained by hydrogenating the above-described 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 having an unsaturated hydrocarbon group; naphthol compounds such as naphthol, alkyl naphthol, alkoxy naphthol, and naphthol having an unsaturated hydrocarbon group; styrene derivatives such as styrene, alkyl styrene, alkoxy styrene, and styrene having an unsaturated hydrocarbon group; benzofuran; and indene.

[0182] The C5 resin refers to a resin obtained by polymerizing a C5 fraction. Examples of the C5 fraction include petroleum fractions having 4 to 5 carbon atoms such as cyclopentadiene, pentene, pentadiene, and isoprene. As the C5 petroleum resin, a dicyclopentadiene resin (DCPD resin) is preferably used.

[0183] ​​​​​​The C9 resin refers to a resin obtained by polymerizing a C9 fraction, and can be hydrogenated or modified. Examples of the C9 fraction include petroleum fractions having 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. As specific examples, a benzofuran-indene resin, a benzofuran resin, an indene resin, and an aromatic vinyl-based resin are preferably used. As the aromatic vinyl-based resin, for economic, easy processability, and excellent heat generation reasons, a homopolymer of a-methylstyrene or styrene, or a copolymer of a-methylstyrene and styrene is preferable, and a copolymer of a-methylstyrene and styrene is more preferable. As the aromatic vinyl-based resin, for example, those available from Kraton Corporation, Eastman Chemical, and the like can be used.

[0184] The C5C9 resin refers to a resin obtained by copolymerizing the above-described C5 fraction and the above-described C9 fraction, and can be hydrogenated or modified. Examples of the C5 fraction and the C9 fraction include the above-described petroleum fractions. As the C5C9 resin, for example, those available from Tosoh Corporation, LUHUA Corporation, and the like can be used.

[0185] The acrylic resin is not particularly limited, but for example, a solvent-free acrylic resin can be used.

[0186] As the solvent-free acrylic resin, a (meth)acrylic resin (polymer) synthesized by a high-temperature continuous polymerization method (high-temperature continuous bulk polymerization method: a method described in US4414370B, JP 84-6207A, JP 93-58805A, JP 89-313522A, US5010166B, TREND 2000 No. 3, pp. 42-45, Research Annual Report of Toagosei, and the like) in a case where a polymerization initiator, a chain transfer agent, an organic solvent, and the like are used as little as possible as auxiliary materials can be exemplified. In the present application, (meth)acrylic acid refers to methacrylic acid and acrylic acid.

[0187] Examples of the monomer component constituting the above-described acrylic resin include (meth)acrylic acid, and (meth)acrylic acid derivatives such as (meth)acrylate (alkyl ester, aryl ester, aralkyl ester, and the like), (meth)acrylamide, and (meth)acrylamide derivatives.

[0188] Further, as the monomer component constituting the above-described acrylic resin, an aromatic vinyl compound (such as styrene, a-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, divinyl naphthalene, and the like) can be used together with (meth)acrylic acid or (meth)acrylic acid derivatives.

[0189] The above-mentioned acrylic resin can be a resin composed only of a (meth) acrylic component, or a resin having a component other than the (meth) acrylic component. In addition, the above-mentioned acrylic resin can have a hydroxyl group, a carboxyl group, a silanol group, or the like.

[0190] As the resin component, for example, products of Maruzen Petrochemical Co., Ltd., Sumitomo Durez Co., Ltd., Yasuhara Chemical Co., Ltd., DKS Co., Ltd., Rutgers Chemicals Co., Ltd., BASF Co., Ltd., Arizona Chemical Co., Ltd., Nippon Paint Co., Ltd., Nippon Shokubai Co., Ltd., JX Energy Co., Ltd., Arakawa Chemical Industries, Ltd., and Takagi Chemical Industrial Co., Ltd. can be used.

[0191] (d) Anti-aging agent

[0192] The rubber composition preferably contains an anti-aging agent. The content of the anti-aging agent is, for example, greater than 1 part by mass and less than 10 parts by mass, and more preferably 3 parts by mass or more, with respect to 100 parts by mass of the rubber component.

[0193] Examples of the anti-aging agent include: a naphthylamine-based anti-aging agent such as phenyl-a-naphthylamine; a diphenylamine-based anti-aging agent such as octylated diphenylamine, 4,4'-bis(a,a'-dimethylbenzyl)diphenylamine; a p-phenylenediamine-based anti-aging agent such as N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine; a quinoline-based anti-aging agent such as a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline; a monophenol-based anti-aging agent such as 2,6-di-tert-butyl-4-methylphenol, styrenated phenol; a bisphenol, a triphenol, a polyphenol-based anti-aging agent such as tetra-[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane. These can be used alone or in combination of two or more.

[0194] As the anti-aging agent, for example, products of Seiko Chemicals Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industrial Co., Ltd., Flexsys Co., Ltd., and the like can be used.

[0195] (e) Stearic acid

[0196] The rubber composition can contain stearic acid. The content of the stearic acid is, for example, greater than 0.5 parts by mass and less than 10.0 parts by mass, and more preferably 3 parts by mass or more, with respect to 100 parts by mass of the rubber component. As the stearic acid, conventionally known stearic acids, for example, products of Nippon Oil Mills Co., Ltd., NOF Corporation, Kao Corporation, Fuji Photo Film and Mitsunaga & Co., Ltd., Chiba Fatty Acid Co., Ltd., and the like can be used.

[0197] (f) zinc oxide

[0198] The rubber composition can contain zinc oxide. The content of zinc oxide is, for example, greater than 0.5 parts by mass and less than 10 parts by mass, more preferably 3 parts by mass or greater, with respect to 100 parts by mass of the rubber component. As the zinc oxide, conventionally known zinc oxides can be used, and, for example, products of Mitsui Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Shōwa Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., and the like can be used.

[0199] (g) wax

[0200] The rubber composition preferably contains a wax. The content of the wax is, for example, 0.5 to 20 parts by mass, preferably 1.0 to 15 parts by mass, more preferably 1.5 to 10.0 parts by mass, with respect to 100 parts by mass of the rubber component.

[0201] The wax is not particularly limited, and examples thereof include petroleum-based waxes such as paraffin wax and microcrystalline wax; natural-based waxes such as plant-based waxes and animal-based waxes; and synthetic waxes such as polymers of ethylene or propylene. These can be used alone or in combination with two or more kinds.

[0202] As the wax, for example, products of Ouchi Shinko Chemical Industrial Co., Ltd., Japan Wax Co., Ltd., Seiko Chemical Co., Ltd. can be used.

[0203] (h) crosslinking agent and vulcanization accelerator

[0204] The rubber composition preferably contains a crosslinking agent such as sulfur. The content of the crosslinking agent is, for example, greater than 0.1 parts by mass and less than 10.0 parts by mass, more preferably 1.5 parts by mass or greater, with respect to 100 parts by mass of the rubber component.

[0205] Examples of the sulfur include powder sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, high-dispersibility sulfur, and soluble sulfur that are commonly used in the rubber industry. These can be used alone or in combination with two or more kinds.

[0206] As the sulfur, for example, products of Tsurumi Chemical Industry Co., Ltd., Kagosaka Sulfur Co., Ltd., Shikoku Chemicals Corporation, Flexsys, Japan Dry Cell Co., Ltd., Hosoi Chemical Industry Co., Ltd., and the like can be used.

[0207] Examples of the crosslinking agent other than sulfur include sulfurating agents containing sulfur atoms such as Tackirol V200 manufactured by TAKENATEC CO., LTD., DURALINK HTS (1,6-hexamethylene-bis-sodium thiosulfate dihydrate) manufactured by Flexsys Corporation, and KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyl disulfide)hexane) manufactured by Lanxess Corporation, and organic peroxides such as dicumyl peroxide.

[0208] The rubber composition preferably contains a vulcanization accelerator. The content of the vulcanization accelerator is, for example, greater than 0.3 parts by mass and less than 10.0 parts by mass, and more preferably 3 parts by mass or more, with respect to 100 parts by mass of the rubber component.

[0209] Examples of the vulcanization accelerator include:

[0210] Thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazyl disulfide, and N-cyclohexyl-2-benzothiazole sulfenamide;

[0211] Thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetra(2-ethylhexyl)thiuram disulfide (TOT-N);

[0212] Sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, N-tert-butyl-2-benzothiazyl sulfenamide, N-oxalyl-2-benzothiazole sulfenamide, N,N'-diisopropyl-2-benzothiazole sulfenamide, and guanidine-based vulcanization accelerators such as diphenyl guanidine, di-o-tolyl guanidine, and o-tolyl biguanide. These can be used alone or in combination with two or more.

[0213] (i) Other

[0214] In addition to the above-mentioned components, the rubber composition can contain additives generally used in the tire industry such as fatty acid metal salts, carboxylic acid metal salts, and organic peroxides. The content of these additives is, for example, greater than 0.1 parts by mass and less than 200 parts by mass with respect to 100 parts by mass of the rubber component.

[0215] 2. Production of the Tread Rubber Composition

[0216] The rubber composition is produced by a general method, for example, by a production method including a base mixing step of mixing the rubber component with a filler such as silica or carbon black, and a final mixing step of mixing the mixture obtained in the base mixing step with a crosslinking agent.

[0217] The mixing can be performed using a publicly known (enclosed) mixer such as a Banbury mixer, a kneader, or an open mill.

[0218] The mixing temperature of the base mixing step is, for example, greater than 50°C and less than 200°C, and the mixing time is, for example, greater than 30 seconds and less than 30 minutes. In the base mixing step, in addition to the above-mentioned components, a compounding agent commonly used in the rubber industry, such as a softening agent (such as oil), stearic acid, zinc oxide, an anti-aging agent, a wax, a vulcanization accelerator, can be added and mixed as necessary.

[0219] In the final mixing step, the mixture obtained in the above-mentioned base mixing step is mixed with a cross-linking agent. The mixing temperature of the final mixing step is, for example, greater than room temperature and less than 80°C, and the mixing time is, for example, greater than 1 minute and less than 15 minutes. In the final mixing step, in addition to the above-mentioned components, a vulcanization accelerator, zinc oxide, and the like can be added and mixed as necessary.

[0220] 3. Tire production

[0221] The tire of the present application uses the unvulcanized rubber composition obtained by the final mixing step, and is produced by a usual method. That is, the unvulcanized rubber composition is extruded according to the shape of the tread, and is shaped together with other tire components on a tire building machine by a conventional method, to produce an unvulcanized tire.

[0222] Specifically, on a building drum, the inner liner layer which is a component for ensuring the air tightness of the tire, the carcass which is a component for bearing the load, impact, and inflation pressure received by the tire, the belt which is a component for tightly tightening the carcass to increase the rigidity of the tread, and the like are wound, both ends of the carcass are fixed to both side edge portions, the bead portion which is a component for fixing the tire to the rim is arranged, and they are shaped into a toroidal shape. Then, the tread is attached to the central portion of the outer circumference, and the sidewall portion which is a component for protecting the carcass and resisting bending is attached to the radially outer side, to produce an unvulcanized tire.

[0223] In the present embodiment, as the belt, an inclined belt layer which extends at an angle of 15° to 30° with respect to the tire circumferential direction is preferably provided. As a result, the durability of the tire is ensured, while the rigidity of the tread can be sufficiently maintained. Furthermore, since it can be constrained in the circumferential direction, it becomes easy to suppress the growth of the outer diameter.

[0224] Then, the manufactured unvulcanized tire is heated and pressurized in a vulcanizer, to obtain a tire. The vulcanization step can be performed by adopting a publicly known vulcanization means. The vulcanization temperature is, for example, greater than 120°C and less than 200°C, and the vulcanization time is, for example, greater than 5 minutes and less than 15 minutes.

[0225] At this time, the tire is formed so as to satisfy the above (Formula 1) and (Formula 2) when the tire is mounted on a standard rim and the internal pressure is set to 250 kPa.

[0226] Specific tires that can satisfy the above (Formula 1) and (Formula 2) include tires having a size designation 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, or the like.

[0227] In the present embodiment, the tire that can satisfy (Formula 1) and (Formula 2) is preferably applied to a passenger car pneumatic tire, and the satisfaction of the above formulas can more favorably contribute to solving the problem of the present application, that is, to provide a pneumatic tire in which the rolling resistance during high-speed running is sufficiently reduced and the durability is sufficiently improved.

[0228] [Examples]

[0229] Hereinafter, the present application will be more specifically described with reference to examples.

[0230] [Experiment 1]

[0231] In the present experiment, a tire of 175 size was prepared and evaluated.

[0232] 1. Manufacture of Rubber Composition for Tread

[0233] First, a rubber composition for tread was manufactured.

[0234] (1) Compounding Materials

[0235] First, each of the compounding materials shown below was prepared.

[0236] (a) Rubber Component

[0237] (a-1) NR: TSR20

[0238] (a-2) SBR: Modified solution polymerized SBR manufactured according to the method described in the following paragraph. (Styrene content: 30 mass%, vinyl bond content: 52 mass%, Mw: 250,000)

[0239] (a-3) BR: UBEPOL-BR150 manufactured by Ube Industries, Ltd.

[0240] The SBR was manufactured according to the process described below. First, cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were charged into a nitrogen-purged autoclave reactor. After adjusting the temperature of the reactor contents to 20°C, n-butyllithium was added to initiate polymerization. Polymerization was carried out under adiabatic conditions, with a maximum temperature of 85°C. When the polymerization conversion reached 99%, 1,3-butadiene was added, and polymerization was further carried out for 5 minutes. Then, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane was added as a modifier to initiate the reaction. After the polymerization reaction was complete, 2,6-di-tert-butyl-p-cresol was added. The solvent was then removed by stripping and dried by hot roller drying at 110°C to obtain the SBR.

[0241] (b) Compounds other than rubber components

[0242] (b-1) Carbon black: Diablack N220 manufactured by Mitsubishi Chemical Corporation

[0243] (b-2) Silica: Ultrasil VN3 (BET specific surface area: 165m²) manufactured by Evonik. 2 / g)

[0244] (b-3) Silane coupling agent: Si266 manufactured by Degussa.

[0245] (bis(3-triethoxysilylpropyl)disulfide)

[0246] (b-4) Oil: Process X-140 manufactured by Nippon Energy Corporation.

[0247] (b-5) Resin (polymer component): SA85 manufactured by Arizona Chemical Company

[0248] (α-Methylstyrene resin)

[0249] (b-6) Wax: Ozoace 0355 manufactured by Nippon Seiwa Co., Ltd.

[0250] (b-7) Anti-aging agent-1: Nocrac 6C (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine) manufactured by Ouchi Shinsei Chemical Co., Ltd.

[0251] (b-8) Anti-aging agent-2: Nocrac 224 (2,2,4-trimethyl-1,2-dihydroquinoline polymer) manufactured by Ouchi Shinsei Chemical Co., Ltd.

[0252] (b-9) Zinc oxide: Zinc White No. 1 manufactured by Mitsui Metals Mining Co., Ltd.

[0253] (b-10) Stearic acid: Stearic acid "TSUBAKI" manufactured by NOF Corporation

[0254] (b-11) Crosslinking agent and vulcanization accelerator

[0255] Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd.

[0256] Vulcanization accelerator-1: Nocceler CZ-G (CBS) (N-cyclohexyl-2-benzothiazylsulfenamide) manufactured by Ono Pharmaceutical Co., Ltd.

[0257] Vulcanization accelerator-2: Nocceler D (DPG) (1,3-diphenylguanidine) manufactured by Ono Pharmaceutical Co., Ltd.

[0258] (2) Production of rubber composition

[0259] The materials except for sulfur and vulcanization accelerator were mixed for 5 minutes at 150°C using a Banbury mixer to obtain a mixture in accordance with the formulations shown in Tables 1 and 2. Each compounding amount is in parts by mass.

[0260] 2. Tire production

[0261] Next, sulfur and vulcanization accelerator were added to the obtained mixture, and the mixture was mixed for 5 minutes at 80°C using an open mill to obtain a tread rubber composition. Using the obtained tread rubber composition, a shaped tread was formed, and other tire components were attached thereto to form an unvulcanized tire, and then the unvulcanized tire was press-vulcanized at 170°C for 10 minutes to produce each test tire (Example 1-1 to Example 1-5 and Comparative Example 1-1 to Comparative Example 1-7) having a size of 175.

[0262] In each test tire, the above (L 80 / L0) was 0.5, the total cross-sectional area of the circumferential grooves was 22% of the cross-sectional area of the tread portion, and the total volume of the transverse grooves including the transverse grooves having a groove width / groove depth of 0.65 was set to 3.5% of the volume of the tread portion.

[0263] 3. Parameter calculation

[0264] Subsequently, the outer diameter Dt (mm), the cross-sectional width Wt (mm), the cross-sectional height Ht (mm), and the flatness (%) of each test tire were obtained, and the virtual volume V (mm 3). Meanwhile, by cutting out a rubber layer from the tread portion of each test tire in a size of 20 mm in length, 4 mm in width, and 2 mm in thickness with the tire circumferential direction being the long side, a rubber test piece for viscoelasticity measurement was produced. For each rubber test piece, tan δ (30°C tan δ) was measured at 30°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain of 1% using an Eplexor series manufactured by GABO Co., Ltd. The results are shown in Tables 1 and 2.

[0265] Then, (Dt - 2 x Ht), (Dt 2 x π / 4) / Wt, (V + 1.5 x 10 7 ) / Wt, (V + 2.0 x 10 7 ) / Wt, (V + 2.5 x 10 7 ) / Wt, and 30°C tan δ x Wt were determined. The results are shown in Tables 1 and 2.

[0266] 4. Performance Evaluation Test

[0267] (1) Evaluation of Rolling Resistance during High-Speed Travel

[0268] Each test tire was mounted on all wheels of a vehicle (a Japanese-made FF car, displacement 2000 cc), and air was filled into the tires to make the internal pressure 250 kPa, and then travel was performed at a speed of 100 km / h on a test course of a dry road surface. After 10 km of travel was completed, the accelerator was turned off, and the distance from the turning off of the accelerator to the stop of the vehicle was measured as the rolling resistance during high-speed travel.

[0269] Next, the results in Comparative Examples 1 to 7 were set to 100, and the results were exponentiated based on the following equation to relatively evaluate the rolling resistance during high-speed travel. The larger the value, the longer the distance from the turning off of the accelerator to the stop of the vehicle, the smaller the rolling resistance in a steady state, and the better the fuel efficiency.

[0270] Rolling Resistance = [(Result of Test Tire) / (Result of Comparative Example 1-7)] x 100

[0271] (2) Evaluation of Durability

[0272] After each test tire was mounted on all wheels of a vehicle (a Japanese-made FF car, displacement 2000 cc) and the tires were filled with air to make the internal pressure 250 kPa, travel was repeated at a speed of 50 km / h for 10 laps and then the action of climbing over irregularities provided on a road surface at a speed of 80 km / h was repeated under an overload state on a test course of a dry road surface. Thereafter, travel was performed at a speed of 50 km / h again, and then the speed at which the driver felt an abnormality was measured while the speed was gradually increased.

[0273] Next, the results in Comparative Examples 1-7 were set to 100, and durability was relatively evaluated by exponentiation based on the following formula. The larger the value, the better the durability.

[0274] Durability = [(result of test tire) / (result of Comparative Examples 1-7)] x 100

[0275] (3) Comprehensive Evaluation

[0276] The evaluation results of (1) and (2) above were added to obtain a comprehensive evaluation.

[0277] (4) Evaluation Results

[0278] Each evaluation result is shown in Tables 1 and 2.

[0279] [Table 1]

[0280]

[0281] [Table 2]

[0282]

[0283] [Experiment 2]

[0284] In this experiment, tires of 195 size were manufactured and evaluated.

[0285] After each test tire of Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-7 shown in Tables 3 and 4 was manufactured in the same manner as in Experiment 1, each parameter was calculated by performing the same procedure. Then, performance evaluation tests were performed and evaluated in the same manner. In this experiment, the results in Comparative Example 2-7 were set to 100 to perform evaluation. Each evaluation result is shown in Tables 3 and 4.

[0286] [Table 3]

[0287]

[0288] [Table 4]

[0289]

[0290] [Experiment 3]

[0291] In this experiment, tires of 225 size were manufactured and evaluated.

[0292] After the tires for each test shown in Tables 5 and 6 of Examples 3-1 to 3-5 and Comparative Examples 3-1 to 3-7 were manufactured in the same manner as in Experiment 1, each parameter was calculated by performing the same procedure. Then, the performance evaluation test was performed and evaluated in the same manner. In this experiment, the results in Comparative Example 3-7 were set to 100 for evaluation. Each evaluation result is shown in Tables 5 and 6.

[0293] [Table 5]

[0294]

[0295] [Table 6]

[0296]

[0297] [Summary of Experiment 1-3]

[0298] According to the results of Experiment 1-3 (Tables 1 to 6), it was confirmed that, for tires of any size (175 size, 195 size, 225 size), when the above (Formula 1) and (Formula 2) were satisfied, a pneumatic tire in which the rolling resistance at high speed was sufficiently reduced and the durability was sufficiently improved could be provided.

[0299] Then, it was confirmed that, by satisfying each requirement specified in the following application (2) and thereafter, a tire in which the rolling resistance at high speed and the durability were further improved could be provided.

[0300] On the other hand, when (Formula 1) or (Formula 2) was not satisfied, the rolling resistance at high speed could not be sufficiently reduced, and the durability could not be sufficiently improved.

[0301] [Experiment 4]

[0302] Next, three tires in which there was no significant difference in the relationship between the virtual volume V and the cross-sectional width Wt were manufactured with the same formulation (Examples 4-1 to 4-3), and were evaluated in the same manner. Here, the results of the tire of Example 4-3 were set to 100. Each evaluation result is shown in Table 7.

[0303] [Table 7]

[0304]

[0305] Table 7 shows that, in the case where there was no large difference in the relationship between the virtual volume V and the cross-sectional width Wt, as the cross-sectional width Wt became smaller from less than 205 mm to less than 200 mm, and as the flatness increased, both the rolling resistance at high speed and the durability were improved. That is, it can be seen that a significant effect was exhibited.

[0306] Although the present application has been described above based on the embodiments, the present application is not limited to the above embodiments. Various modifications can be made to the above embodiments within the scope of the present application disclosed.

[0307] The present application (1) is;

[0308] A pneumatic tire having a tread portion, wherein

[0309] At least one layer of the rubber layers forming the tread portion is formed of a rubber composition having a rubber component containing styrene-butadiene rubber and isoprene-based rubber and a loss tangent (30°C tan δ) of 0.14 or less, measured at 30°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1%;

[0310] When the tire is mounted on a standard rim and the cross-sectional width of the tire in a state where the internal pressure is 250 kPa is Wt (mm), the outer diameter is Dt (mm), and the volume of the space occupied by the tire is a virtual volume V (mm 3 ), the tire satisfies the following (Formula 1) and (Formula 2):

[0311] 1600 ≦ (Dt 2 × π / 4) / Wt ≦ 2827.4... (Formula 1)

[0312] [(V + 1.5 x 10 7 ) / Wt] ≦ 2.88 x 10 5 ... (Formula 2)

[0313] The present application (2) is the pneumatic tire according to the present application (1), wherein the tire satisfies the following (Formula 3).

[0314] [(V + 2.0 x 10 7 ) / Wt] ≦ 2.88 x 10 5 ... (Formula 3)

[0315] The present application (3) is the pneumatic tire according to the present application (2), wherein the tire satisfies the following (Formula 4).

[0316] [(V + 2.5 x 10 7 ) / Wt] ≦ 2.88 x 10 5 ... (Formula 4)

[0317] The present application (4) is the pneumatic tire according to any combination of the present applications (1) to (3), wherein when the tire is mounted on a standard rim and the outer diameter of the tire in a state where the internal pressure is 250 kPa is Dt (mm) and the cross-sectional height of the tire is Ht (mm), (Dt - 2 x Ht) is 470 (mm) or more.

[0318] The present application (5) is the pneumatic tire according to any combination of the present application (1) to (4), wherein the flat ratio of the tire is 40% or more.

[0319] The present application (6) is the pneumatic tire according to the present application (5), wherein the flat ratio of the tire is 45% or more.

[0320] The present application (7) is the pneumatic tire according to the present application (6), wherein the flat ratio of the tire is 47.5% or more.

[0321] The present application (8) is the pneumatic tire according to the present application (7), wherein the flat ratio of the tire is 50% or more.

[0322] The present application (9) is the pneumatic tire according to any combination of the present application (1) to (8), wherein the tan δ at 30°C is 0.12 or less.

[0323] The present application (10) is the pneumatic tire according to the present application (9), wherein the tan δ at 30°C is 0.10 or less.

[0324] The present application (11) is the pneumatic tire according to any combination of the present application (1) to (10), wherein tan δ at 30°C x Wt ≦ 30.0.

[0325] The present application (12) is the pneumatic tire according to the present application (11), wherein tan δ at 30°C x Wt ≦ 25.0.

[0326] The present application (13) is the pneumatic tire according to any combination of the present application (1) to (12), wherein,

[0327] The tread portion has a plurality of circumferential grooves continuously extending in the tire circumferential direction,

[0328] The groove width L at a depth of 80% of the maximum depth of the circumferential groove 80 The ratio (L 80 / L0) of the groove width L0 of the circumferential groove on the ground surface of the tread portion is 0.3 to 0.7.

[0329] The present application (14) is the pneumatic tire according to any combination of the present application (1) to (13), wherein,

[0330] The tread portion has a plurality of circumferential grooves continuously extending in the tire circumferential direction,

[0331] The total cross-sectional area of the plurality of circumferential grooves is 10 to 30% of the cross-sectional area of the tread portion.

[0332] The present application (15) is the pneumatic tire according to any combination of the present application (1) to (14), wherein,

[0333] the tread portion has a plurality of lateral grooves extending in the tire axial direction,

[0334] the total volume of the plurality of lateral grooves is 2.0-5.0% of the volume of the tread portion.

[0335] The invention (16) is the pneumatic tire according to the invention (15), wherein at least 1 of the lateral grooves is a lateral groove having a groove width / groove depth of 0.50-0.80.

[0336] The invention (17) is the pneumatic tire according to any combination of the inventions (1)-(16), wherein when the outer diameter of the tire in a state where the tire is mounted on a standard rim and the internal pressure is 250 kPa is Dt (mm), Dt is less than 685 (mm).

[0337] The invention (18) is the pneumatic tire according to any combination of the inventions (1)-(17), wherein the cross-sectional width Wt (mm) is less than 205 mm.

[0338] The invention (19) is the pneumatic tire according to the invention (18), wherein the cross-sectional width Wt (mm) is less than 200 mm.

[0339] The invention (20) is the pneumatic tire according to any combination of the inventions (1)-(19), wherein,

[0340] the tread portion is formed of a plurality of rubber layers,

[0341] the rubber composition is used in a running surface rubber layer of the tread.

[0342] The invention (21) is the pneumatic tire according to any combination of the inventions (1)-(20), wherein the tire is a pneumatic tire for a passenger vehicle.

Claims

1. A pneumatic tire having a tread portion, characterized in that, at least one of the rubber layers forming the tread portion is formed of a rubber composition having a rubber component containing styrene-butadiene rubber and isoprene-based rubber and a loss tangent tan δ at 30°C measured under conditions of a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain rate of 1% of 0.12 or less; and when the tire is mounted on a standard rim and the cross-sectional width of the tire in a state where the internal pressure is 250 kPa is Wt, the outer diameter is Dt, and the volume of the space occupied by the tire is a virtual volume V, the tire satisfies the following (Formula 1) and (Formula 4): 1600 ≦ (Dt 2 x π / 4) / Wt ≦ 2827.4... (Equation 1) [(V + 2.5 x 10 7 ) / Wt] < 2.75 x 10 5 · · · (Equation 4), Wt and Dt are in mm, V is in mm 3 ; when the tire is mounted on a standard rim and the outer diameter of the tire in a state where the internal pressure is 250 kPa is Dt and the cross-sectional height of the tire is Ht, (Dt - 2 x Ht) is 470 or more and 507 or less, the units of Dt and Ht are mm.

2. The pneumatic tire of claim 1, wherein, the flatness is 40% or more.

3. The pneumatic tire of claim 2, wherein, the flatness is 45% or more.

4. The pneumatic tire of claim 3, wherein, the flatness is 47.5% or more.

5. The pneumatic tire of claim 4, wherein, the flatness is 50% or more.

6. The pneumatic tire of claim 5, wherein, the tan δ at 30°C is 0.10 or less.

7. The pneumatic tire of claim 1, wherein, 30°C tan δ x Wt ≦ 30.

0.

8. The pneumatic tire of claim 7, wherein, 30°C tan δ x Wt ≦ 25.

0.

9. The pneumatic tire according to claim 1, characterized in that, the tread portion has a plurality of circumferential grooves extending continuously in the tire circumferential direction, A groove width L at a depth of 80% of a maximum depth of the circumferential groove 80 A ratio L of the groove width L0 of the circumferential groove on the ground surface of the tread portion 80 L / L0 is 0.3-0.

7.

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

11. The pneumatic tire according to claim 1, characterized in that, the tread portion has a plurality of transverse grooves extending in the tire axial direction, the total volume of the plurality of transverse grooves is 2.0-5.0% of the volume of the tread portion.

12. The pneumatic tire of claim 11, wherein, at least one of the transverse grooves is a transverse groove having a groove width / groove depth of 0.50-0.

80.

13. The pneumatic tire according to claim 1, characterized in that, when the outer diameter of the tire in a state where the tire is mounted on a standard rim and the internal pressure is 250 kPa is Dt, Dt is less than 685 mm.

14. The pneumatic tire of claim 1, wherein, the cross-sectional width Wt is less than 205 mm.

15. The pneumatic tire of claim 14, wherein, the cross-sectional width Wt is less than 200 mm.

16. The pneumatic tire according to any one of claims 1-15, characterized in that, the tread portion is formed of a plurality of rubber layers, the rubber composition is used in a running surface rubber layer of the tread portion.

17. The pneumatic tire of any of claims 1-15, wherein, the pneumatic tire is a pneumatic tire for a passenger vehicle. the pneumatic tire is a pneumatic tire for a passenger vehicle.

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