Pneumatic tire

Abstract

Provided is a pneumatic tire that balances ride comfort at low temperatures and handling stability at high speeds, and that has a tread portion having: two or more circumferential grooves that extend continuously in the tire circumferential direction; a pair of shoulder land portions separated by the circumferential grooves and a center land portion located between the pair of shoulder land portions; and a transverse groove; and optionally has a sipe. When the tire cross-sectional width is Wt (mm) and the tire outer diameter is Dt (mm), Wt and Dt satisfy the following formula (1); when the tire circumferential length is La, and the sum of the total length of the edge components in the transverse direction of the transverse groove, Lb1, and the total length of the edge components in the transverse direction of the sipe, Lb2, is Lb, La and Lb satisfy the following formula (2); and the tread portion has at least one rubber layer composed of a rubber composition containing a rubber component, the rubber composition having a 5°C tan δ, a 20°C tan δ, and a 50°C tan δ, measured under the conditions of a frequency of 10 Hz and an elongation strain of 2.5%, satisfying the following formula (3) and formula (4): formula (1) 1963.4 ≤ (π / 4) × (Dt^2 / Wt) ≤ 2827.4 formula (2) 0.10 ≤ La / Lb ≤ 0.50 formula (3) 0.01 ≤ |20°C tan δ + 50°C tan δ| / 2 ≤ 0.17 formula (4) 0.30 ≤ |5°C tan δ + 20°C tan δ| / 2 ≤ 0.60.

Description

TECHNICAL FIELD

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

[0002] In recent years, in addition to the equipment of automobiles, performance has been significantly improved, and the road network has also expanded, so the number of high-speed driving situations has increased, and in particular, in high-speed driving, a tire having a base tread that always improves the stability of the steering stability and the ride comfort is required.

[0003] For example, Patent Document 1 discloses a pneumatic tire having a base tread in which collagen particles are incorporated. However, the steering stability and the ride comfort at high speed are not sufficiently satisfied.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT DOCUMENTS

[0006] Patent Document 1: Japanese Patent Application Publication No. 2004-269684 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] An object of the present application is to provide a tire that balances the ride comfort at low speed and the steering stability at high speed.

[0009] MEANS FOR SOLVING THE PROBLEMS

[0010] The present inventors conducted intensive studies, and as a result, found that in a tire in which the cross-sectional width of the tire and the outer diameter of the tire satisfy prescribed requirements, by setting the viscoelasticity of the tread rubber and the tread pattern to specific conditions, a tire that balances the ride comfort at low speed and the steering stability at high speed can be obtained, thereby completing the present application.

[0011] That is, the present application relates to:

[0012] [1] : A pneumatic tire having a tread portion, the tread portion having: two or more circumferential grooves continuously extending in a circumferential direction of the tire; a pair of shoulder land portions separated by the circumferential grooves and a center land portion located between the pair of shoulder land portions; and a transverse groove; can arbitrarily have or not have a sipe; when a tire cross-sectional width is set as Wt (mm) and an outer diameter of the tire is set as Dt (mm), Wt and Dt satisfy the following formula (1); when a circumferential length of the tire is set as La, and a sum of a length of a side component in the transverse direction of the transverse groove Lbl and a length of a side component in the transverse direction of the sipe Lb2 is set as Lb, La and Lb satisfy the following formula (2); the tread portion has at least one rubber layer composed of a rubber composition containing a rubber component, tan δ at 5°C (5°C tan δ), tan δ at 20°C (20°C tan δ), and tan δ at 50°C (50°C tan δ) of the rubber composition measured under conditions of a frequency of 10 Hz and a tensile strain of 2.5% satisfy the following formula (3) and the following formula (4):

[0013] Formula (1) 1963.4 ≤ (π / 4) x (Dt^2 / Wt) ≤ 2827.4

[0014] Formula (2) 0.10 ≤ La / Lb ≤ 0.50

[0015] Formula (3) 0.01 ≤ |20°C tan δ + 50°C tan δ| / 2 ≤ 0.17

[0016] Formula (4) 0.30 ≤ |5°C tan δ + 20°C tan δ| / 2 ≤ 0.60.

[0017] [2] : The pneumatic tire according to [1], wherein the value of the formula (3) is less than 0.15.

[0018] [3] : The pneumatic tire according to [1] or [2], wherein the value of the formula (4) is 0.35 to 0.55.

[0019] [4] : The pneumatic tire according to any one of [1] to [3], wherein the value of the formula (3) is less than 0.14.

[0020] [5] : The pneumatic tire according to any one of [1] to [4], wherein the value of the formula (4) is 0.40 to 0.55.

[0021] [6] : The pneumatic tire according to any one of [1] to [5], wherein the 5°C tan δ of the rubber composition is 0.65 or more.

[0022] [7]: The pneumatic tire as described in any one of [1] to [6], wherein the 5°C tanδ of the rubber composition is 0.70 or more.

[0023] [8]: The pneumatic tire as described in any one of [1] to [7], wherein the tanδ of the rubber composition at 20°C is 0.25 or less.

[0024] [9]: The pneumatic tire as described in any one of [1] to [8], wherein the tanδ of the rubber composition at 20°C is 0.20 or less.

[0025]

[10] : The pneumatic tire as described in any one of [1] to [9], wherein the tanδ of the rubber composition at 20°C is 0.15 or less.

[0026]

[11] : The pneumatic tire as described in any one of [1] to

[10] , wherein the total length of the lateral side component of the lateral groove in the shoulder contact portion is Lb. sh The total length Lb of the lateral side component of the sipes in the tire shoulder contact area mentioned above. sh The sum of 2 Lb sh The total length Lb of the transverse side component of the transverse trench in the central grounding part. ce The total length Lb of the transverse side component of the knife groove in the central grounding portion mentioned above. ce The sum of 2 Lb ce The ratio Lb sh / Lb ce For Lb sh / Lb ce <1.

[0027]

[12] : The pneumatic tire as described in any one of [1] to

[11] , wherein the width of at least one of the above-mentioned central contact portions is more than 1.4 times the depth of the circumferential groove adjacent to the tire in the lateral direction.

[0028]

[13] : The pneumatic tire as described in any one of [1] to

[12] , wherein when the ground contact area of ​​the tread surface is set to St, and the sum of the total area of ​​the circumferential groove Sg1 and the total area of ​​the lateral groove and the sipe Sg2 is set to Sg, St and Sg satisfy the following formula (6).

[0029] Equation (6) 0.15≤Sg / St≤0.35

[0030]

[14] : The pneumatic tire as described in

[13] , wherein Sg1 / St is 0.09 to 0.16 and Sg2 / St is 0.08 to 0.14.

[0031]

[15] : The pneumatic tire as described in any one of [1] to

[14] , wherein the ratio of the value of the above formula (3) to the value of the above formula (2) is 0.30 to 1.05.

[0032]

[16] : The pneumatic tire as described in any one of [1] to

[15] , wherein the ratio of the value of the above formula (4) to the value of the above formula (2) is 2.1 to 3.8.

[0033]

[17] : The pneumatic tire as described in any one of

[13] to

[16] , wherein the ratio of the value of the above formula (4) to the value of the above formula (6) is 1.7 to 2.7.

[0034]

[18] : A pneumatic tire as described in any one of [1] to

[17] , wherein the tire is a passenger car tire.

[0035] Invention Effects

[0036] The pneumatic tire of the present invention, by setting specific conditions for the tire's cross-sectional width and outer diameter, the viscoelasticity of the tread rubber, and the tread pattern, can balance ride comfort at low temperatures and handling stability at high speeds. Attached Figure Description

[0037] Figure 1 This is a partially unfolded view showing the tread pattern of the pneumatic tire of the present invention. Detailed Implementation

[0038] Hereinafter, an embodiment of the pneumatic tire of the present invention will be described with reference to the accompanying drawings. It should be noted that the embodiment shown below is only an example, and the pneumatic tire of the present invention is not limited to the following embodiment.

[0039] Figure 1 This is a unfolded view of the tread portion 1. Tread patterns are formed on the tread portion 1, specifying the direction of installation onto the vehicle. The tread patterns of the tread portion 1 are formed in an asymmetrical shape relative to the tire equator C.

[0040] The tread portion 1 has an outer tread end To and an inner tread end Ti. The outer tread end To is located on the outer side of the vehicle when mounted on it. Figure 1 (The middle is the right side). The inner tread end Ti is located inside the vehicle when installed. Figure 1 (The middle is the left side).

[0041] To and Ti at each tread end represent the tire's lateral W when it is in normal load condition and grounded at a camber angle of 0 degrees. Figure 1The outermost ground contact position in the lateral direction of the tire in the normal state. The normal state refers to a state in which the tire is assembled on a normal rim and filled with a normal internal pressure, and is not under load. In this specification, unless otherwise specified, the dimensions of each part of the tire (tire cross-sectional width Wt, tire outer diameter Dt, etc.) are values measured in the above normal state. In the normal state, the distance in the lateral direction W between the outer side tread end To and the inner side tread end Ti is defined as the tread width TW.

[0042] "Normal rim" refers to a rim prescribed in each standard in the standard system including the standard to which the tire conforms, and refers to "Standard Rim" if JATMA, "Design Rim" if TRA, or "Measuring Rim" if ETRTO.

[0043] "Normal internal pressure" refers to the air pressure prescribed in each standard in the standard system including the standard to which the tire conforms, and refers to "Maximum Air Pressure" if JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" if TRA, or "INFLATION PRESSURE" if ETRTO.

[0044] "Normal load" refers to the load prescribed in each standard in the standard system including the standard to which the tire conforms, and refers to "Maximum Load Capacity" if JATMA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" if TRA, or "LOAD CAPACITY" if ETRTO.

[0045] The tread portion 1 has two or more circumferential grooves 11, 12, 13 that extend continuously in the circumferential direction C. Figure 1 In the present embodiment, three circumferential grooves 11, 12, 13 are provided. However, the number of circumferential grooves is not particularly limited, and may be, for example, two to five. In addition, the circumferential grooves 11, 12, 13 extend linearly in the circumferential direction C in the present embodiment, but are not limited to this manner, and may extend in a wavy, sinusoidal, zigzag, or the like manner in the circumferential direction C.

[0046] The groove width of each of the circumferential grooves 11, 12, 13 can be arbitrarily determined as appropriate. In order to provide sufficient drainage performance while maintaining the pattern rigidity of the tread portion 1, the groove width of each of the circumferential grooves 11, 12, 13 is preferably, for example, about 2.5% to 5% of the tread width TW. The groove depth of each of the circumferential grooves 11, 12, 13 is not particularly limited, and is preferably 5.0 to 12.0 mm, more preferably 6.0 to 11.0 mm, and further preferably 7.0 to 10.0 mm.

[0047] The "shoulder land portion" in the present application refers to a pair of land portions formed between the circumferential groove located at the outermost side in the lateral direction W from the tire equator C and each of the tread ends To, Ti. Figure 1 The outer side shoulder land portion 16 formed between the circumferential groove 12 located at the outermost side when mounted on a vehicle and the outer side tread end To, and the inner side shoulder land portion 17 formed between the circumferential groove 11 located at the innermost side when mounted on a vehicle and the inner side tread end Ti are respectively provided.

[0048] Two or more shoulder lateral grooves 21, 22 and two or more shoulder sipes 23, 24 extending in a direction transverse to the shoulder land portions 16, 17 are provided in each of the shoulder land portions 16, 17. Two or more shoulder lateral grooves 21, 22 and two or more shoulder sipes 23, 24 are respectively provided in each of the pair of shoulder land portions 16, 17. Note that, in the present specification, the shoulder lateral grooves and shoulder sipes provided in the outer side shoulder land portion 16 are referred to as the outer side shoulder lateral grooves 21 and the outer side shoulder sipes 23, respectively. In addition, the shoulder lateral grooves and shoulder sipes provided in the inner side shoulder land portion 17 are referred to as the inner side shoulder lateral grooves 22 and the inner side shoulder sipes 24, respectively.

[0049] The "center land portion" in the present application refers to the entire land portion sandwiched between the pair of shoulder land portions described above. Figure 1 The outer side center land portion 18 formed between the circumferential groove 13 provided along the tire equator C and the circumferential groove 12 located at the outermost side when mounted on a vehicle, and the inner side center land portion 19 formed between the circumferential groove 13 provided along the tire equator C and the circumferential groove 11 located at the innermost side when mounted on a vehicle are respectively provided, but the number of center land portions is not particularly limited, and can be, for example, one to five.

[0050] Two or more central lateral grooves 25, 26 and two or more central sipes 27, 28 are provided in the central ground contacting portion 18, 19 so as to extend in a direction transverse to the central ground contacting portion 18, 19. Two or more central lateral grooves 25, 26 and two or more central sipes 27, 28 are provided in the central ground contacting portion 18, 19, respectively. Note that, in the present specification, the central lateral grooves and the central sipes provided in the outer central ground contacting portion 18 are referred to as the outer central lateral grooves 25 and the outer central sipes 27, respectively. In addition, the central lateral grooves and the central sipes provided in the inner central ground contacting portion 19 are referred to as the inner central lateral grooves 26 and the inner central sipes 28, respectively.

[0051] The groove width of each of the lateral grooves 21, 22, 25, 26 is preferably, for example, about 2.5% to 5% of the tread width TW. The groove depth of each of the lateral grooves 21, 22, 25, 26 is not particularly limited, and is preferably 5.0 to 12.0 mm, more preferably 6.0 to 11.0 mm, and further preferably 7.0 to 10.0 mm. Note that, in the present specification, the "sipe" refers to a fine cut having a width of 2.0 mm or less, and preferably 0.5 to 1.5 mm.

[0052] The shoulder ground contacting portions 16, 17 can also be provided with shoulder fine grooves 29, 30 extending in the tire circumferential direction. Thereby, the shoulder ground contacting portions 16, 17 can be divided into an outer piece 16A, 17A disposed between the shoulder fine grooves 29, 30 and the tread end To, Ti and an inner piece 16B, 17B disposed on the tire equator C side of the outer piece 16A, 17A.

[0053] By providing the above-described shoulder fine grooves 29, 30, the edge component in the tire circumferential direction can be increased, and the cornering performance can be improved. In addition, since the rigidity of the tire in the circumferential direction of the outer piece 16A, 17A and the inner piece 16B, 17B is significantly ensured, the running performance on a dry road surface is improved. Note that, in the present application, the shoulder fine grooves 29, 30 extend in a straight line in the circumferential direction C, but are not limited to such a manner, and can be, for example, wavy, sinusoidal, or zigzag. The groove width W2 of the shoulder fine grooves 29, 30 is preferably, for example, 1.0% to 2.0% of the tread width TW. The groove depth of the shoulder fine grooves 29, 30 is preferably, for example, 0.40 to 0.60 times the groove depth of the deepest portion of the circumferential grooves 11, 12, 13.

[0054] In addition, in the present application, as Figure 1As shown, the sipes 27, 28 of the center ground portions 18, 19 extend in a manner connecting both ends of the lateral direction W of the center ground portions 18, 19. The straight line connecting both ends of the lateral direction W of the sipes 27, 28 of the center ground portions 18, 19 and the angle θ formed by the circumferential groove 12 are preferably within a range of 60 to 80 degrees. In this case, a water film can be scraped out in the center ground portions 18, 19, and the braking performance on a wet road surface can be improved.

[0055] The tire of the present application is characterized in that, when a tire cross-sectional width is set as Wt (mm) and a tire outer diameter is set as Dt (mm), Wt and Dt satisfy the following formula (1). Note that, in the present specification, the "tire cross-sectional width" refers to the maximum width between the outer surfaces of the tire sides in a normal state, excluding patterns or characters or the like on the tire sides.

[0056] Formula (1) 1963.4 ≤ (π / 4) x (Dt2 / Wt) ≤ 2827.4

[0057] Further, the tire of the present application is characterized in that, when the length of the circumferential direction C of the tire 1 is set as La, and the sum of the length of the lateral direction W of the lateral groove 21, 22, 25, 26 is set as Lbl and the length of the lateral direction W of the sipe 23, 24, 27, 28 is set as Lb2, the total of Lbl and Lb2 is set as Lb, La and Lb satisfy the following formula (2).

[0058] Formula (2) 0.10 ≤ La / Lb ≤ 0.50

[0059] The value (La / Lb) of formula (2) is 0.10 or more, preferably 0.11 or more, more preferably 0.12 or more, further preferably 0.13 or more, and particularly preferably 0.14 or more. Further, the value (La / Lb) of formula (2) is 0.50 or less, preferably 0.45 or less, more preferably 0.40 or less, further preferably 0.30 or less, and particularly preferably 0.25 or less. By setting the relationship between the length of the lateral direction W of the lateral groove 21, 22, 25, 26 and the sipe 23, 24, 27, 28 and the length La of the circumferential direction C of the tire 1 within the above range, the deformation of the tread portion 1 can be ensured to be within a predetermined range, the area of the ground portion 16, 17, 18, 19 of the tread portion 1 can be ensured to be a predetermined area or more, and the handling stability at high speed can be improved when the rubber composition described later is used for the tread.

[0060] Note that, the "length of the lateral direction W of the lateral groove 21, 22, 25, 26 and the sipe 23, 24, 27, 28" refers to the projected length (lateral component among the lateral component and the circumferential component) of the lateral groove 21, 22, 25, 26 and the sipe 23, 24, 27, 28 in the lateral direction W.

[0061] Furthermore, the ratio La / Lb1 of the length La of the tire's circumferential C and the total length Lb1 of the side components of the lateral W of the lateral grooves 21, 22, 25, 26 is preferably 0.18 to 0.70, more preferably 0.21 to 0.60, and even more preferably 0.24 to 0.50. By ensuring that the relationship between the total length Lb1 of the side components of the lateral W of the lateral grooves 21, 22, 25, 26 and the length La of the tire's circumferential C falls within the above range, the effect of the rubber composition described later can be further improved.

[0062] In addition, the total length Lb of the side components of the lateral W in the lateral grooves 21 and 22 in the tire shoulder contact portions 16 and 17 is... sh The total length Lb of the lateral W side components of the sipes 23 and 24 in the shoulder contact portions 16 and 17 is as follows: sh The sum of 2 Lb sh The total length Lb of the side components of the transverse W of the transverse trenches 25 and 26 in the central grounding parts 18 and 19. ce The total length Lb of the transverse W side components of the knife grooves 27 and 28 in the central grounding parts 18 and 19 is 1. ce The sum of 2 Lb ce The ratio Lb sh / Lb ce Preferably Lb sh / Lb ce <1. In this case, the edge components in the tire shoulder contact portions 16 and 17 become smaller, and the rigidity of the tire shoulder contact portions 16 and 17 increases. As a result, wear on the tire shoulder contact portions 16 and 17 can be suppressed, and handling stability at high speeds can be improved.

[0063] Regarding the tire of the present invention, the area of ​​the entire contact patch when the tread is pressed against a flat surface under normal conditions and a normal load is applied is defined as Sr, and the total area of ​​the aforementioned central contact patch is defined as S. ce When Sr and S are preferred ce It satisfies the following equation (5).

[0064] Equation (5) 0.35≤Sce / Sr≤0.80

[0065] The value of equation (5) (S) ce The value of / Sr) is preferably 0.35 or more, more preferably 0.38 or more, even more preferably 0.40 or more, and particularly preferably 0.42 or more. Furthermore, the value of formula (5) (S) ce The ratio of Sr is preferably 0.80 or less, more preferably 0.70 or less, even more preferably 0.60 or less, and particularly preferably 0.55 or less. By making the ratio of the total area of ​​the central contact patch to the total area of ​​the tire contact patch within the above range, the volume of the central contact patch can be increased, the rigidity of the contact patch can be increased, and thus better handling stability can be obtained.

[0066] In addition, from the viewpoint of obtaining the same effects, the ground contact width of the at least one central ground portion is preferably 1.4 times or more, more preferably 1.5 times or more, and further preferably 1.6 times or more of the groove depth of the circumferential groove adjacent on the lateral outer side.

[0067] With respect to the tire of the present application, when the ground contact area of the tread portion is set as St, and the sum of the total area Sgl of the circumferential grooves and the total area Sg2 of the lateral grooves and the sipes is set as Sg, St and Sg preferably satisfy the following formula (6). Note that the "ground contact area of the tread portion" in this specification refers to the ground contact area of the tread portion 1 in a state in which all of the grooves of the tread portion 1 are filled.

[0068] Formula (6) 0.15 ≤ Sg / St ≤ 0.35

[0069] The value (Sg / St) of formula (6) is preferably 0.15 or more, more preferably 0.18 or more, and further preferably 0.21 or more. In addition, the value (Sg / St) of formula (6) is preferably 0.35 or less, more preferably 0.30 or less, and further preferably 0.25 or less.

[0070] Sgl / St is preferably 0.09 or more, more preferably 0.10 or more, and further preferably 0.11 or more. In addition, Sgl / St is preferably 0.16 or less, more preferably 0.14 or less, and further preferably 0.13 or less.

[0071] Sg2 / St is preferably 0.08 or more, more preferably 0.09 or more, and further preferably 0.10 or more. In addition, Sg2 / St is preferably 0.14 or less, more preferably 0.13 or less, and further preferably 0.12 or less.

[0072] By setting the proportions of the total groove area, the total area of the circumferential grooves, and the total area of the lateral grooves and the sipes to the ground contact area to the above ranges, the rigidity of the ground portion of the tread can be increased, and based on the synergistic effect with the softness of the rubber possessed by the tread rubber composition of the present application, high handling stability at high speed can be exhibited while improving ride comfort at low temperature. In the case where the proportions of the total groove area, the total area of the circumferential grooves, and the total area of the lateral grooves and the sipes to the ground contact area are less than the above ranges, because the proportion of the ground portion is increased too much, there is a tendency for the water drainage and the grip to decrease. On the other hand, in the case where the proportions of the total groove area, the total area of the circumferential grooves, and the total area of the lateral grooves and the sipes to the ground contact area are greater than the above ranges, because sufficient rigidity of the ground portion of the tread cannot be obtained, there is a tendency for the handling stability to decrease.

[0073] It should be noted that in this specification, the area Sr of the entire grounding part and the total area S of the central grounding part are... ce The total area Sg1 of the circumferential grooves and the total area Sg2 of the lateral grooves and sipes are calculated from the contact patch shape when the tread is pressed against a flat surface under normal load. The contact patch shape is obtained by mounting the tire to a normal rim, maintaining normal internal pressure, applying ink to the tread portion 1, and pressing it perpendicularly onto thick paper or the like under normal load (camber angle 0°), thus transferring the ink applied to the tread portion 1. Furthermore, the area obtained based on the outer contour of the obtained contact patch shape is set as the contact patch area St of the tread portion when all grooves are filled.

[0074] In this invention, "5℃tanδ", "20℃tanδ" and "50℃tanδ" refer to the tanδ at 5℃, 20℃ and 50℃ measured under conditions of 10Hz frequency and 2.5% tensile strain, respectively. The rubber composition of this invention is characterized in that the 5℃tanδ, 20℃tanδ and 50℃tanδ satisfy the following formulas (3) and (4).

[0075] Formula (3) 0.01≤|20℃tanδ+50℃tanδ| / 2≤0.17

[0076] Formula (4) 0.30≤|5℃tanδ+20℃tanδ| / 2≤0.60

[0077] Considering the effects of the present invention, the value of formula (3) (|20℃tanδ+50℃tanδ| / 2) is 0.01 or more, preferably 0.03 or more, more preferably 0.05 or more, even more preferably 0.07 or more, and particularly preferably 0.09 or more. Furthermore, the value of formula (3) (|20℃tanδ+50℃tanδ| / 2) is 0.17 or less, preferably 0.16 or less, more preferably 0.15 or less, even more preferably 0.14 or less, and particularly preferably 0.13 or less.

[0078] Considering the effects of the present invention, the value of formula (4) (|5℃tanδ+20℃tanδ| / 2) is 0.30 or more, preferably 0.32 or more, more preferably 0.34 or more, even more preferably 0.36 or more, and particularly preferably 0.38 or more. Furthermore, the value of formula (4) (|5℃tanδ+20℃tanδ| / 2) is 0.60 or less, preferably 0.58 or less, more preferably 0.56 or less, even more preferably 0.54 or less, and particularly preferably 0.52 or less.

[0079] From the viewpoint of the effects of the present application, the value of formula (3) is preferably 0.05 or more, more preferably 0.10 or more, further preferably 0.15 or more. In addition, the value of formula (3) is preferably 0.40 or less, more preferably 0.35 or less, further preferably 0.30 or less.

[0080] From the viewpoint of the effects of the present application, the value of formula (4) is preferably 0.70 or more, more preferably 0.75 or more, further preferably 0.80 or more. In addition, the value of formula (4) is preferably 1.50 or less, more preferably 1.30 or less, further preferably 1.10 or less.

[0081] From the viewpoint of the effects of the present application, the ratio of the value of formula (3) to the value of formula (2) is preferably 0.15 or more, more preferably 0.30 or more, further preferably 0.45 or more. In addition, the ratio of the value of formula (3) to the value of formula (2) is preferably 1.05 or less, more preferably 0.95 or less, further preferably 0.85 or less.

[0082] From the viewpoint of the effects of the present application, the ratio of the value of formula (4) to the value of formula (2) is preferably 1.8 or more, more preferably 2.1 or more, further preferably 2.4 or more. In addition, the ratio of the value of formula (4) to the value of formula (2) is preferably 3.8 or less, more preferably 3.6 or less, further preferably 3.4 or less.

[0083] From the viewpoint of the effects of the present application, the ratio of the value of formula (3) to the value of formula (5) is preferably 0.05 or more, more preferably 0.10 or more, further preferably 0.15 or more. In addition, the ratio of the value of formula (3) to the value of formula (5) is preferably 0.40 or less, more preferably 0.35 or less, further preferably 0.30 or less.

[0084] From the viewpoint of the effects of the present application, the ratio of the value of formula (4) to the value of formula (5) is preferably 0.70 or more, more preferably 0.75 or more, further preferably 0.80 or more. In addition, the ratio of the value of formula (4) to the value of formula (5) is preferably 1.50 or less, more preferably 1.30 or less, further preferably 1.10 or less.

[0085] From the viewpoint of the effects of the present application, the ratio of the value of formula (4) to the value of formula (6) is preferably 1.5 or more, more preferably 1.6 or more, further preferably 1.7 or more. In addition, the ratio of the value of formula (4) to the value of formula (6) is preferably 3.0 or less, more preferably 2.7 or less, further preferably 2.4 or less.

[0086] The tread portion of the present application has at least one rubber layer. The rubber layer can be formed of a single rubber layer, or can further have one or more rubber layers inside the tire radial direction of the rubber layer (tread rubber layer) constituting the outer surface of the tread. In the case where the rubber layer is formed of two or more layers, at least one of the two or more rubber layers can be formed of the above-mentioned specified rubber composition, and preferably the tread rubber layer is formed of the above-mentioned specified rubber composition.

[0087] The above-mentioned specified rubber composition is preferably used for a rubber layer present in a portion or all of the tire radial direction outside the deepest portion of the groove bottom of the deepest groove among the circumferential grooves 11, 12, 13 and the transverse grooves 21, 22, 25, 26, and more preferably for a rubber layer present in all of the tire radial direction outside the deepest portion of the groove bottom of the deepest groove. In the case where the above-mentioned specified rubber composition is used for a tread rubber layer, the tread rubber layer is preferably present in all of the tire radial direction outside the deepest portion of the groove bottom of the deepest groove among the circumferential grooves 11, 12, 13 and the transverse grooves 21, 22, 25, 26.

[0088] [Rubber composition]

[0089] As for the tire of the present application, by the above-mentioned tire structure, particularly the shape of the tread, in cooperation with the above-mentioned properties of the rubber composition, the ride comfort at low temperatures and the steering stability at high speeds can be more effectively improved.

[0090] [Rubber component]

[0091] As for the rubber composition of the present application, it is preferable to contain at least one selected from the group consisting of isoprene-based rubber, styrene butadiene rubber (SBR) and butadiene rubber (BR) as a rubber component, more preferable to contain SBR, further preferable to contain SBR and BR, and can be a rubber component formed of only SBR and BR.

[0092] (SBR)

[0093] The SBR is not particularly limited, and examples include solution polymerized SBR (S-SBR), emulsion polymerized SBR (E-SBR), modified SBRs of these (modified S-SBR, modified E-SBR), and the like. As the modified SBR, examples include SBRs modified at the terminal and / or main chain, modified SBRs coupled with tin, silicon compounds, and the like (polycondensates, substances having a branched structure, and the like), and the like. Among these, S-SBR and modified SBRs are preferable. Further, hydrogenated products of these SBRs (hydrogenated SBR) and the like can be used. These SBRs can be used singly or in combination of two or more.

[0094] As the S-SBR which can be used in the present application, S-SBR manufactured and sold by JSR Corporation, Sumitomo Chemical Co., Ltd., Ube Industries, Ltd., Asahi Kasei Corporation, ZS Elastomers, Inc., and the like can be mentioned.

[0095] The styrene content of the SBR is preferably 10% by mass or more, more preferably 15% by mass or more, and further preferably 20% by mass or more from the viewpoint of wet grip performance and wear resistance. In addition, it is preferably 60% by mass or less, more preferably 55% by mass or less, and further preferably 50% by mass or less from the viewpoint of temperature dependence of the wet grip performance and the burst resistance. Note that the styrene content of the SBR in the present specification is calculated from the H-NMR measurement. 1

[0096] The vinyl content of the SBR is preferably 10 mol% or more, more preferably 15 mol% or more, and further preferably 20 mol% or more from the viewpoint of ensuring reactivity with silica, wet grip performance, rubber strength, and wear resistance. In addition, it is preferably 70 mol% or less, more preferably 65 mol% or less, and further preferably 60 mol% or less from the viewpoint of preventing an increase in temperature dependence, elongation at break, and wear resistance. Note that the vinyl content (amount of 1,2-bonded butadiene units) of the SBR in the present specification is measured by infrared absorption spectroscopy.

[0097] The weight average molecular weight (Mw) of the SBR is preferably 200,000 or more, more preferably 250,000 or more, and further preferably 300,000 or more from the viewpoint of wet grip performance. In addition, it is preferably 2,000,000 or less, more preferably 1,800,000 or less, and further preferably 1,500,000 or less from the viewpoint of uniformity of crosslinking. Note that the weight average molecular weight of the SBR in the present specification can be calculated by converting the value measured by gel permeation chromatography (GPC) (for example, GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer; column: TSKGEL SUPERMALTIPORE HZ-M manufactured by Tosoh Corporation) to standard polystyrene.

[0098] In the case where the SBR is contained, the content thereof in the rubber component 100% by mass is preferably 40% by mass or more, more preferably 50% by mass or more, further preferably 60% by mass or more, and particularly preferably 70% by mass or more from the viewpoint of wet grip performance. In addition, the upper limit of the content of the SBR in the rubber component is not particularly limited and can be 100% by mass.

[0099] (BR)

[0100] ​The BR is not particularly limited, and, for example, BR having a content of cis-1,4 bonds (cis content) of less than 50% (low-cis BR), BR having a content of cis-1,4 bonds of 90% or more (high-cis BR), rare-earth-based butadiene rubber (rare-earth-based BR) synthesized using a rare-earth element-based catalyst, BR containing syndiotactic polybutadiene crystals (BR containing SPB), modified BR (high-cis modified BR, low-cis modified BR), and the like, which are commonly used in the tire industry, can be used. These BRs can be used alone or in combination of two or more.

[0101] As the modified BR, there are, for example, tin-modified BR obtained by adding a tin compound after polymerization of 1,3-butadiene using a lithium initiator and further modifying the terminal of the BR molecule with a tin-carbon bond, butadiene rubber having a condensation alkoxy silane compound at the active terminal of the butadiene rubber (silicon-modified BR), and the like. As such modified BR, there are, for example, tin-modified BR and silicon-modified BR manufactured and sold by ZS Elastomers Co., Ltd., and the like.

[0102] From the viewpoint of abrasion resistance, the weight average molecular weight (Mw) of the BR is preferably 300,000 or more, more preferably 350,000 or more, and further preferably 400,000 or more. In addition, from the viewpoint of uniformity of crosslinking, it is preferably 2,000,000 or less, and more preferably 10,000,000 or less. Note that the weight average molecular weight of the BR can be calculated by converting the value measured by gel permeation chromatography (GPC) (for example, GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer; column: TSKGEL SUPERMALTIPORE HZ-M manufactured by Tosoh Corporation) to standard polystyrene.

[0103] In the case where the BR is contained, the content thereof in the rubber component is preferably 50% by mass or less, more preferably 40% by mass or less, further preferably 30% by mass or less, and particularly preferably 20% by mass or less, from the viewpoint of wet grip performance. In addition, the lower limit of the content in the case where the BR is contained is not particularly limited, and can be, for example, 1% by mass or more, 3% by mass or more, 5% by mass or more, 10% by mass or more, or 15% by mass or more.

[0104] (Isoprene-based rubber)

[0105] As the isoprene-based rubber, for example, isoprene rubber (IR) and natural rubber, which are commonly used in the tire industry, can be used. In addition to unmodified natural rubber (NR), modified natural rubber such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), high purity natural rubber, grafted natural rubber, and the like can be contained in the natural rubber. These isoprene-based rubbers can be used singly or in combination of two or more kinds.

[0106] As the NR, a material commonly used in the tire industry can be used, and for example, SIR20, RSS#3, TSR20, and the like can be mentioned.

[0107] In the case where the isoprene-based rubber is contained, the content thereof in the rubber component 100% by mass is preferably 50% by mass or less, more preferably 40% by mass or less, further preferably 30% by mass or less, and particularly preferably 20% by mass or less from the viewpoint of wet grip performance. In addition, in the case where the isoprene-based rubber is contained, the lower limit of the content thereof is not particularly limited, and can be set to, for example, 1% by mass or more, 3% by mass or more, 5% by mass or more, 10% by mass or more, or 15% by mass or more.

[0108] <Other Rubber Component>

[0109] As the rubber component of the present application, a rubber component other than the above-described isoprene-based rubber, SBR, and BR can also be contained. As the other rubber component, a rubber component that can be crosslinked, which is commonly used in the tire industry, can be used, and for example, styrene-isoprene-butadiene copolymer rubber (SIBR), styrene-isobutylene-styrene block copolymer (SIBS), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), hydrogenated nitrile rubber (HNBR), butyl rubber (IIR), ethylene-propylene rubber, polynorbornene rubber, silicone rubber, chlorinated polyethylene rubber, fluororubber (FKM), acrylate rubber (ACM), chlorohydrin rubber, and the like can be mentioned. These other rubber components can be used singly or in combination of two or more kinds.

[0110] <Filler>

[0111] As the filler, the rubber composition of the present application preferably contains silica, and more preferably contains carbon black and silica.

[0112] (Carbon Black)

[0113] As the carbon black, a carbon black commonly used in the tire industry can be appropriately used, and for example, GPF, FEF, HAF, ISAF, SAF, and the like can be mentioned. These carbon blacks can be used singly or in combination of two or more kinds.

[0114] From the viewpoint of reinforcement, the nitrogen adsorption specific surface area (N2SA) of the carbon black is preferably 10 m 2 / g or more, more preferably 20 m 2 / g or more. In addition, from the viewpoint of low fuel consumption performance and processability, it is preferable that the N2SA be 200 m 2 / g or less, more preferably 150 m 2 / g or less, further preferably 100 m 2 / g or less, further preferably 80 m 2 / g or less, particularly preferably 50 m 2 / g or less. Note that the N2SA of the carbon black is a value measured in accordance with JIS K 6217-2 "Carbon Black for Rubber - Basic Properties - Part 2: Calculation Method for Specific Surface Area - Nitrogen Adsorption Method - Single Point Method".

[0115] In the case of containing carbon black, from the viewpoint of wear resistance and wet grip performance, the content of the carbon black is preferably 1 part by mass or more, more preferably 3 parts by mass or more, further preferably 5 parts by mass or more, with respect to 100 parts by mass of the rubber component. In addition, from the viewpoint of low fuel consumption performance, it is preferable that the content be 50 parts by mass or less, more preferably 35 parts by mass or less, further preferably 20 parts by mass or less, particularly preferably 10 parts by mass or less.

[0116] (Silica)

[0117] As the silica, there is no particular limitation, and substances commonly used in the tire industry, such as silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrous silica), and the like can be used. Among them, from the viewpoint of having many silanol groups, hydrous silica prepared by a wet method is preferable. These silicas can be used singly or in combination with two or more kinds.

[0118] From the viewpoint of low fuel consumption performance and wear resistance, the nitrogen adsorption specific surface area (N2SA) of the silica is preferably 140 m 2 / g or more, more preferably 170 m 2 / g or more, further preferably 200 m 2 / g or more. In addition, from the viewpoint of low fuel consumption performance and processability, it is preferable that the N2SA be 350 m 2 / g or less, more preferably 300 m 2 / g or less, further preferably 250 m 2 / g or less. Note that the N2SA of the silica in the present specification is a value measured in accordance with ASTM D3037-93 using the BET method.

[0119] In the case of containing silica, the content of silica is preferably 20 parts by mass or more, more preferably 40 parts by mass or more, further preferably 50 parts by mass or more, and particularly preferably 60 parts by mass or more, relative to 100 parts by mass of the rubber component, from the viewpoint of wet grip performance. In addition, the content is preferably 130 parts by mass or less, more preferably 120 parts by mass or less, and further preferably 110 parts by mass or less, from the viewpoint of wear resistance.

[0120] The total content of silica and carbon black is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, and further preferably 60 parts by mass or more, relative to 100 parts by mass of the rubber component, from the viewpoint of wear resistance. In addition, the total content is preferably 160 parts by mass or less, more preferably 140 parts by mass or less, and further preferably 120 parts by mass or less, from the viewpoint of low fuel consumption and elongation at break.

[0121] The proportion of silica is preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, and particularly preferably 85% by mass or more, relative to the total content of silica and carbon black.

[0122] (Other fillers)

[0123] As the fillers other than silica and carbon black, it is possible to incorporate substances that have been conventionally used in the tire industry, such as aluminum hydroxide, calcium carbonate, alumina, clay, talc, and the like.

[0124] (Silane coupling agent)

[0125] Silica is preferably used in combination with a silane coupling agent. As the silane coupling agent, there is no particular limitation, and any silane coupling agent that has been conventionally used in combination with silica in the tire industry can be used. Examples of the silane coupling agent include, for example, the following mercapto-based silane coupling agent; sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl) disulfide and bis(3-triethoxysilylpropyl) tetrasulfide; vinyl-based silane coupling agents such as vinyl triethoxysilane and vinyl trimethoxysilane; amino-based silane coupling agents such as 3-aminopropyl triethoxysilane, 3-aminopropyl trimethoxysilane, and 3-(2-aminoethyl) aminopropyl triethoxysilane; glycidoxy-based silane coupling agents such as γ-glycidoxypropyl triethoxysilane and γ-glycidoxypropyl trimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyl trimethoxysilane and 3-nitropropyl triethoxysilane; and chloro-based silane coupling agents such as 3-chloropropyl trimethoxysilane and 3-chloropropyl triethoxysilane. Among these, sulfide-based silane coupling agents and / or mercapto-based silane coupling agents are preferred, and mercapto-based silane coupling agents are more preferred. These silane coupling agents can be used alone or in combination with two or more kinds.

[0126] The mercapto-based silane coupling agent is preferably a compound represented by the following formula (7), and / or a compound containing a bonding unit A represented by the following formula (8) and a bonding unit B represented by the following formula (9).

[0127] [Chemical Formula 1]

[0128]

[0129] (In the formula, R 101 , R 102 , and R 103 each independently represent an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or -0-(R 111 -O) z -R 112 (z number of R 111 each independently represent a divalent hydrocarbon group having 1 to 30 carbon atoms; R 112 represent an alkyl group having 1 to 30 carbon atoms, an alkenyl group having 2 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an aralkyl group having 7 to 30 carbon atoms; and z represents an integer of 1 to 30.) ; R 104 represents an alkylene group having 1 to 6 carbon atoms.)

[0130] [Chemical Formula 2]

[0131]

[0132] [Chemical Formula 3]

[0133]

[0134] (In the formula, x represents an integer of 0 or more; y represents an integer of 1 or more; R 201 represents a hydrogen atom, an alkyl group having 1 to 30 carbon atoms which can be substituted with a halogen atom, a hydroxyl group, or a carboxyl group, an alkenyl group having 2 to 30 carbon atoms, or an alkynyl group having 2 to 30 carbon atoms; R 202 represents an alkylene group having 1 to 30 carbon atoms, an alkenylene group having 2 to 30 carbon atoms, or an alkynylene group having 2 to 30 carbon atoms; here, R 201 and R 202 may form a ring structure.)

[0135] As the compound represented by formula (7), for example, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, a compound represented by the following formula (10) (Si363 manufactured by Evonik Degussa), and the like can be given, and the compound represented by the following formula (10) can be preferably used. These can be used singly or in combination of two or more.

[0136] [Chemical 4]

[0137]

[0138] As the compound containing the bonding unit A represented by formula (8) and the bonding unit B represented by formula (9), for example, a compound manufactured and sold by Momentive Co., Ltd. can be given. These can be used alone or in combination with two or more.

[0139] In the case of containing the silane coupling agent, the total content of the silane coupling agent is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, further preferably 2.0 parts by mass or more, and particularly preferably 4.0 parts by mass or more, with respect to 100 parts by mass of the rubber component, from the viewpoint of improving the dispersibility of the silica. In addition, it is preferably 20 parts by mass or less, more preferably 12 parts by mass or less, further preferably 10 parts by mass or less, and particularly preferably 9.0 parts by mass or less, from the viewpoint of preventing a decrease in wear resistance.

[0140] The content of the silane coupling agent (total amount in the case of using two or more kinds of silane coupling agents) is preferably 1.0 parts by mass or more, more preferably 3.0 parts by mass or more, and particularly preferably 5.0 parts by mass or more, with respect to 100 parts by mass of the silica, from the viewpoint of improving the dispersibility of the silica. In addition, it is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and further preferably 12 parts by mass or less, from the viewpoint of cost and processability.

[0141] As the filler, in addition to carbon black and silica, other fillers can be used. As such a filler, there is no particular limitation, and any of the fillers commonly used in the field, such as aluminum hydroxide, aluminum oxide, calcium carbonate, magnesium sulfate, talc, clay, and the like, can be used, and calcium carbonate is preferably used. These fillers can be used alone or in combination with two or more kinds.

[0142] <Other additives>

[0143] In the rubber composition of the present application, in addition to the above-mentioned components, an additive commonly used in the past tire industry, such as a softening agent, a wax, a processing aid, stearic acid, zinc oxide, an anti-aging agent, a vulcanizing agent, a vulcanization accelerator, and the like, can be appropriately contained.

[0144] (Softening agent)

[0145] The rubber composition of the present application preferably contains a softening agent. As the plasticizer, for example, a resin component, an oil, a liquid rubber, an ester-based plasticizer, and the like, can be given.

[0146] As the resin component, there is no particular limitation, and petroleum resins, terpene-based resins, rosin-based resins, phenol-based resins, and the like that are conventionally used in the tire industry can be given. These resin components can be used singly or in combination of two or more.

[0147] In the present specification, "C5-based petroleum resin" refers to a resin obtained by polymerizing a C5 fraction. As the C5 fraction, petroleum fractions having 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, isoprene, and the like, can be given. As the C5-based petroleum resin, a dicyclopentadiene resin (DCPD resin) is preferably used.

[0148] In the present specification, "aromatic-based petroleum resin" refers to a resin obtained by polymerizing a C9 fraction, and can also be a resin in which these are hydrogenated or modified. As the C9 fraction, petroleum fractions having 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, methylindene, and the like, can be given. As specific examples of the aromatic-based petroleum resin, a coumarone-indene resin, a coumarone resin, an indene resin, and an aromatic vinyl-based resin are preferably used. As the aromatic vinyl-based resin, because of the excellent economy, ease of processing, and exothermicity, a homopolymer of α-methylstyrene, styrene, or a copolymer of α-methylstyrene and styrene is preferably used, and a copolymer of α-methylstyrene and styrene is more preferably used. As the aromatic vinyl-based resin, commercially available resins from, for example, Kraton Corporation, Eastman Chemical, and the like can be used.

[0149] In the present specification, "C5C9-based petroleum resin" refers to a resin obtained by copolymerizing the above-described C5 fraction and the above-described C9 fraction, and can also be a resin in which these are hydrogenated or modified. As the C5 fraction and the C9 fraction, the above-described petroleum fractions can be given. As the C5C9-based petroleum resin, commercially available resins from, for example, Toagosei Co., Ltd., LUHUA, and the like can be used.

[0150] As the terpene-based resin, a polyterpene resin composed of at least one selected from terpene compounds such as α-pinene, β-pinene, limonene, dipentene, and the like; an aromatic-modified terpene resin using the above-described terpene compound and an aromatic compound as a raw material; a terpene-phenol resin using a terpene compound and a phenol-based compound as a raw material; and a resin in which these terpene-based resins are subjected to hydrogenation treatment (hydrogenated terpene-based resin) can be given. As the aromatic compound as a raw material of the aromatic-modified terpene resin, styrene, α-methylstyrene, vinyltoluene, divinyltoluene, and the like can be given. As the phenol-based compound as a raw material of the terpene-phenol resin, phenol, bisphenol A, cresol, dimethylphenol, and the like can be given.

[0151] As the rosin-based resin, there is no particular limitation, and examples that can be given include natural resin rosin, rosin modified resins in which rosin is modified by hydrogenation, disproportionation, dimerization, esterification, and the like.

[0152] As the phenol-based resin, there is no particular limitation, and examples that can be given include phenol resins, alkyl phenol resins, alkyl phenol acetylene resins, oil-modified phenol resins, and the like.

[0153] From the viewpoint of wet grip performance, the softening point of the resin component is preferably 60°C or higher, more preferably 65°C or higher. In addition, from the viewpoint of processability and improvement of dispersibility of the rubber component and the filler, it is preferably 150°C or lower, more preferably 140°C or lower, and further preferably 130°C or lower. Note that, in the present specification, the softening point can be defined as follows: the softening point prescribed in JIS K 6220-1:2001 is measured using a ring-and-ball softening point measuring device, and the temperature at which the ball is lowered is the softening point.

[0154] In the case where the resin component is contained, the content of the resin component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more, with respect to 100 parts by mass of the rubber component, from the viewpoint of wet grip performance. In addition, it is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and further preferably 40 parts by mass or less, and particularly preferably 30 parts by mass or less, from the viewpoint of suppressing exothermicity.

[0155] As the oil, examples that can be given include process oil, vegetable fat, animal fat, and the like. As the process oil, examples that can be given include paraffin-based process oil, naphthenic-based process oil, aromatic-based process oil, and the like. In addition, as an environmental countermeasure, a process oil having a low content of polycyclic aromatic compound (PCA) can also be used. As the low-PCA-content process oil, examples that can be given include mild extract solvate (MES), treated distillate aromatic extract (TDAE), heavy naphthenic-based oil, and the like.

[0156] In the case where the oil is contained, the content of the oil is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 15 parts by mass or more, with respect to 100 parts by mass of the rubber component, from the viewpoint of processability. In addition, it is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, and further preferably 90 parts by mass or less, from the viewpoint of wear resistance. Note that, in the present specification, the content of the oil also includes the amount of oil contained in oil-extended rubber.

[0157] The liquid rubber is not particularly limited as long as it is a polymer that is in a liquid state at ordinary temperature (25°C), and examples thereof include liquid butadiene rubber (liquid BR), liquid styrene butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene isoprene rubber (liquid SIR), liquid farnesene rubber, and the like. These liquid rubbers can be used alone or in combination of two or more.

[0158] In the case where the liquid rubber is contained, the content of the liquid rubber is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and further preferably 3 parts by mass or more, and particularly preferably 5 parts by mass or more, with respect to 100 parts by mass of the rubber component. In addition, the content of the liquid rubber is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and further preferably 20 parts by mass or less.

[0159] As the ester-based plasticizer, examples thereof include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di(2-ethylhexyl) azelate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), tris(2,6-xylyl) phosphate (TXP), and the like. These ester-based plasticizers can be used alone or in combination of two or more.

[0160] In the case where the ester-based plasticizer is contained, the content of the ester-based plasticizer is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and further preferably 3 parts by mass or more, and particularly preferably 5 parts by mass or more, with respect to 100 parts by mass of the rubber component. In addition, the content of the ester-based plasticizer is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and further preferably 20 parts by mass or less.

[0161] With respect to 100 parts by mass of the rubber component, the content of the softening agent (the total amount of all of the softening agents in the case where two or more kinds of softening agents are used in combination) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 15 parts by mass or more, from the viewpoint of wet grip performance. In addition, the content is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, further preferably 90 parts by mass or less, and particularly preferably 80 parts by mass or less, from the viewpoint of processability.

[0162] In the case of containing the wax, the content of the wax is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, relative to 100 parts by mass of the rubber component, from the viewpoint of the weather resistance of the rubber. In addition, from the viewpoint of preventing the whitening of the tire due to the bloom, it is preferably 10 parts by mass or less, more preferably 5 parts by mass or less.

[0163] As the processing aid, for example, a fatty acid metal salt, a fatty acid amide, an amide ester, a silica surfactant, a fatty acid ester, a mixture of a fatty acid metal salt and an amide ester, a mixture of a fatty acid metal salt and a fatty acid amide, and the like can be given. These processing aids can be used alone or in combination of two or more. As the processing aid, commercially available products of Schill + Seilacher Co., Performance Additives Co., and the like can be used.

[0164] In the case of containing the processing aid, the content of the processing aid is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, relative to 100 parts by mass of the rubber component, from the viewpoint of the improvement effect of the processability. In addition, from the viewpoint of the wear resistance and the breaking strength, it is preferably 10 parts by mass or less, more preferably 8 parts by mass or less.

[0165] As the anti-aging agent, there is no particular limitation, and for example, various compounds of amine-based, quinoline-based, quinone-based, phenol-based, imidazole-based, metal salt of carbamic acid, and the like can be given, and a phenylene diamine-based anti-aging agent such as N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N-isopropyl-N'-phenyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N,N'-di-2-naphthyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, and a quinoline-based anti-aging agent such as 2,2,4-trimethyl-1,2-dihydroquinoline polymer, 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline are preferable. These anti-aging agents can be used alone or in combination of two or more.

[0166] In the case of containing the anti-aging agent, the content of the anti-aging agent is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, relative to 100 parts by mass of the rubber component, from the viewpoint of the ozone cracking resistance of the rubber. In addition, from the viewpoint of the wear resistance and the wet grip performance, it is preferably 10 parts by mass or less, more preferably 5 parts by mass or less.

[0167] In the case of containing the stearic acid, the content of the stearic acid is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, relative to 100 parts by mass of the rubber component, from the viewpoint of the processability. In addition, from the viewpoint of the vulcanization speed, it is preferably 10 parts by mass or less, more preferably 5 parts by mass or less.

[0168] In the case of containing zinc oxide, the content of zinc oxide is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, relative to 100 parts by mass of the rubber component, from the viewpoint of processability. In addition, it is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, from the viewpoint of wear resistance.

[0169] As the vulcanizing agent, sulfur is preferably used. As the sulfur, powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and the like can be used.

[0170] In the case of containing sulfur as the vulcanizing agent, the content of sulfur is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, further preferably 0.5 parts by mass or more, relative to 100 parts by mass of the rubber component, from the viewpoint of ensuring sufficient vulcanization reaction. In addition, it is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, further preferably 3.0 parts by mass or less, from the viewpoint of preventing deterioration. Note that, in the case of using oil-containing sulfur as the vulcanizing agent, the content of the vulcanizing agent is set to the total content of the pure sulfur component contained in the oil-containing sulfur.

[0171] As the vulcanizing agent other than sulfur, for example, alkylphenol-sulfur chloride condensate, 1,6-hexamethylene-bis(thiocarbodithioaminoformyl) sodium dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyl disulfide) hexane, and the like can be given. These vulcanizing agents other than sulfur can use commercially available products of TAKACHIMICA CO., LTD., LANXESS KK, Flexsys Corporation, and the like.

[0172] As the vulcanization accelerator, for example, a sulfenamide-based, thiazole-based, thiuram-based, guanidine-based, dithiocarbamic acid-based, aldehyde-amine-based or aldehyde-ammonia-based, imidazoline-based, or xanthate-based vulcanization accelerator, and the like can be given. These vulcanization accelerators can be used alone or in combination with two or more. Among them, one or more vulcanization accelerators selected from the group consisting of a sulfenamide-based, guanidine-based, and thiazole-based vulcanization accelerator is preferred.

[0173] As the sulfenamide-based vulcanization accelerator, for example, N-tert-butyl-2-benzothiazyl sulfenamide (TBBS), N-cyclohexyl-2-benzothiazyl sulfenamide (CBS), N,N-dicyclohexyl-2-benzothiazyl sulfenamide (DCBS), and the like can be given. Among them, N-tert-butyl-2-benzothiazyl sulfenamide (TBBS) is preferred.

[0174] As the guanidine-based vulcanization accelerator, for example, 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of bispyrocatechol borate, 1,3-di-o-cumylguanidine, 1,3-di-o-biphenylguanidine, 1,3-di-o-cumyl-2-propionylguanidine, and the like can be given. Among them, 1,3-diphenylguanidine (DPG) is preferred.

[0175] As the thiazole-based vulcanization accelerator, for example, 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, bisbenzothiazyl disulfide, and the like can be given. Among them, 2-mercaptobenzothiazole is preferred.

[0176] In the case where the vulcanization accelerator is contained, the content of the vulcanization accelerator is preferably 1 part by mass or more, more preferably 2 parts by mass or more, with respect to 100 parts by mass of the rubber component. In addition, the content of the vulcanization accelerator is preferably 8 parts by mass or less, more preferably 7 parts by mass or less, further preferably 6 parts by mass or less, with respect to 100 parts by mass of the rubber component. By making the content of the vulcanization accelerator within the above range, there is a tendency that the breaking strength and the elongation can be ensured.

[0177] The rubber composition of the present application can be manufactured by a publicly known method. For example, it can be manufactured by mixing the above components using an open roll, a closed mixing machine (Banbury mixer, kneader, or the like), or the like rubber mixing device.

[0178] The mixing step includes, for example, a base mixing step of mixing the compounding agents and additives other than the vulcanizing agent and the vulcanization accelerator, and a finishing (F mixing) step of adding the vulcanizing agent and the vulcanization accelerator to the mixture obtained in the base mixing step and mixing. Further, the above base mixing step can be divided into two or more steps as desired.

[0179] The mixing conditions are not particularly limited, and for example, a method in which, in the base mixing step, mixing is performed at a discharge temperature of 150 to 170°C for 3 to 10 minutes, and in the finishing step, mixing is performed at 70 to 110°C for 1 to 5 minutes can be given. The vulcanization conditions are not particularly limited, and for example, a method in which vulcanization is performed at 150 to 200°C for 10 to 30 minutes can be given.

[0180] As for the tire provided with a tread composed of the above rubber composition, it can be manufactured in a usual manner using the above rubber composition. That is, an unvulcanized rubber composition in which the above components are compounded in the rubber component as needed is extrusion-processed in accordance with the shape of the tread, is attached to other tire components on a tire building machine, is molded in a usual manner, thereby forming an unvulcanized tire, and the unvulcanized tire is heated and pressurized in a vulcanizer, whereby the tire can be manufactured.

[0181] The above rubber composition can be used for a tread of various tires, for example, a tire for a passenger car; a tire for a truck or a bus; a tire for a two-wheeled vehicle; a high performance tire; a studless tire for winter use; and the like. These tires can also be: a zero pressure tire provided with a side reinforcement layer; a tire provided with a sound absorbing member such as a sponge in the inner cavity of the tire; a tire provided with a sealant member capable of sealing when a tire bursts in the inner portion of the tire or the inner cavity of the tire; a tire provided with an electronic member such as a sensor, a wireless tag, or the like in the inner portion of the tire or the inner cavity of the tire; and the like.

[0182] Examples

[0183] The present application is specifically described according to the examples, but the present application is not limited to these examples.

[0184] Hereinafter, various agents used in the examples and comparative examples are shown in summary.

[0185] SBR1: S-SBR (styrene content: 30 mass%, vinyl group content: 52 mol%, Mw: 250,000, non-extended product) manufactured in Production Example 1 described later

[0186] SBR2: HP755 (S-SBR; styrene content: 40 mass%, vinyl group content: 38 mol%, extended product containing 37.5 parts by weight of oil with respect to 100 parts by weight of rubber component) manufactured by JSR Corporation

[0187] BR1: UBEPOL BR (registered trademark) 150B (cis content: 97%, Mw: 440,000) manufactured by Ube Industries, Ltd.

[0188] BR2: BR500 (cis content: 32%) manufactured by JSR Corporation

[0189] Carbon black: Diablack N220 (N2SA: 115 m 2 / g) manufactured by Mitsubishi Chemical Corporation

[0190] Silica 1: Zeosil 1115MP (N2SA: 115 m 2 / g) manufactured by Solvay Japan KK

[0191] Silica 2: ULTRASIL (registered trademark) VN3 (N2SA: 175 m 2 / g) manufactured by Evonik Degussa

[0192] Calcium carbonate: FP-300 manufactured by CALFINE

[0193] Silane coupling agent 1: Si266 (bis(3-triethoxysilylpropyl)disulfide) manufactured by Evonik Degussa

[0194] Silane coupling agent 2: NXT-Z45 (mercapto-based silane coupling agent) manufactured by Momentive

[0195] Ester-based plasticizer: TOP (tris(2-ethylhexyl)phosphate) manufactured by Daiecl Chemical Industries, Ltd.

[0196] Resin component: Sylvatraxx 4401 (copolymer of α-methylstyrene and styrene, softening point: 85°C) manufactured by Kraton Corporation

[0197] Anti-aging agent: Antigen 3C (N-isopropyl-N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd.

[0198] Stearic acid: Bead stearic acid "Tsubaki" manufactured by Nisshin Oil Mills, Ltd.

[0199] Zinc oxide: Zinc white No. 1 manufactured by Mitsui Mining Co., Ltd.

[0200] Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Co., Ltd.

[0201] Vulcanization accelerator 1: Soxinol CZ (N-cyclohexyl-2-benzothiazole sulfenamide) manufactured by Sumitomo Chemical Co., Ltd.

[0202] Vulcanization accelerator 2: Soxinol D-G (N,N'-diphenylguanidine) manufactured by Sumitomo Chemical Co., Ltd.

[0203] Production Example 1: Synthesis of SBR1

[0204] A high-pressure autoclave reactor after replacement with nitrogen was charged with cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene. After adjusting the temperature of the contents of the reactor to 20°C, n-butyllithium was added, and polymerization was started. The polymerization was carried out under adiabatic conditions, with a maximum temperature of 85°C. At the time when the polymerization conversion reached 99%, 1,3-butadiene was added, and after re-polymerization for 5 minutes, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane was added as a modifier and reacted. After the polymerization reaction was completed, 2,6-di-tert-butyl-p-cresol was added. Next, desolventization was carried out by stripping, and drying was performed using a hot roller adjusted to 110°C, to obtain SBR1.

[0205] According to the compounding contents shown in Table 1, using a 1.7L closed-type Banbury mixer, the agents except sulfur and vulcanization accelerator were kneaded at a discharge temperature of 160°C for 4 minutes to obtain a kneaded product. Next, to the obtained kneaded product, sulfur and vulcanization accelerator were added, and using an open roll, kneading was performed for 4 minutes to obtain an unvulcanized rubber composition. Further, the obtained unvulcanized rubber composition was flat-plate vulcanized at 170°C for 12 minutes to obtain a test vulcanized rubber sheet.

[0206] In addition, each rubber sheet was made into the shape of a tread using the obtained unvulcanized rubber composition, and was attached to other components to produce a green tire. Next, in a vulcanization step, press molding was performed at 170°C for 20 minutes to produce a test tire of 195 / 65R15 size.

[0207] <Measurement of tan δ>

[0208] From the sheet-shaped vulcanized rubber composition, a long strip-shaped test piece having a width of 4 mm, a length of 20 mm, and a thickness of 2 mm was punched out for use in the test. Using a dynamic viscoelasticity measuring device EPLEXOR (registered trademark) series manufactured by GABO Co., Ltd., tan δ at 5°C (5°C tan δ), tan δ at 20°C (20°C tan δ), and tan δ at 50°C (50°C tan δ) were measured under conditions of a frequency of 10 Hz and a tensile strain of 2.5%.

[0209] <Handling stability at high speed running>

[0210] Each test tire was installed on all wheels of a domestic FF car having a displacement of 660 cc, and real vehicle running was performed on a test course of dry asphalt at an air temperature of 20°C to 30°C. The handling characteristics were evaluated based on the feeling of each of a test driver at the time of straight running, lane changing, and acceleration and deceleration at a running speed of 120 km / h. The evaluation was performed in integer values of 1 to 5, and under the evaluation criteria that the higher the score, the more excellent the handling characteristics, the total scores of 10 test drivers were calculated. The total score of the reference comparative example (Comparative Example 1 in Tables 3 and 4, Comparative Example 5 in Tables 5 and 6) was converted into a reference value (100), and the evaluation results of each test tire were expressed by being exponentially proportional to the total score.

[0211] <Riding comfort at low temperature>

[0212] Each of the test tires was mounted on all wheels of a domestic FF vehicle with a displacement of 660 cc, and real vehicle running was performed on a test course of dry asphalt at an air temperature of -1°C to -6°C, and a sensory evaluation of ride comfort was performed by test drivers. The evaluation was performed with an integer value of 1 to 5, and under the evaluation criteria that the higher the score, the more excellent the ride comfort, the total scores of 10 test drivers were calculated. The total scores of the reference comparative examples (Comparative Example 1 in Tables 3 and 4, Comparative Example 5 in Tables 5 and 6) were converted into a reference value (100), and the evaluation results of each of the test tires were expressed by being index-converted in proportion to the total scores.

[0213] [Table 1]

[0214]

[0215] [Table 2]

[0216]

[0217]

[0218] [Table 4]

[0219]

[0220]

[0221] [Table 6]

[0222]

[0223] From the results of Tables 1 to 6, it was found that the pneumatic tire of the present application, which is provided with the specific conditions of the cross-sectional width and the outer diameter of the tire, the viscoelasticity of the tread rubber, and the tread pattern, is improved in both ride comfort at low temperature and steering stability at high speed running.

[0224] Explanation of symbols

[0225] 1 tread portion

[0226] 11, 12, 13 circumferential grooves

[0227] 16 outer shoulder land portion

[0228] 17 inner shoulder land portion

[0229] 18 outer center land portion

[0230] 19 inner center land portion

[0231] 21 outer shoulder transverse groove

[0232] 22 inner shoulder transverse groove

[0233] 23 outer shoulder sipe

[0234] 24 inner shoulder sipe

[0235] 25 outer center transverse groove

[0236] 26 inner center transverse groove

[0237] 27 outer center sipe

[0238] 28 inner center sipe

[0239] 29 outer shoulder fine sipe

[0240] 30 inner shoulder fine sipe

[0241] To outer tread end

[0242] Ti inner tread end

[0243] W tire transverse direction

Claims

1. A pneumatic tire having a tread portion, wherein, The tread portion has: Two or more circumferential grooves that extend continuously along the circumference of the tire; A pair of tire shoulder grounding portions separated by the circumferential groove and a central grounding portion located between the pair of tire shoulder grounding portions; and Horizontal trench; The tread surface may or may not have sipes; When the tire cross-sectional width is set to Wt (mm) and the tire outer diameter is set to Dt (mm), Wt and Dt satisfy the following equation (1); When the circumferential length of the tire is set to La, and the sum of the lengths of the lateral side components of the lateral groove to Lb1 and the lengths of the lateral side components of the sipe to Lb2 is set to Lb, La and Lb satisfy the following equation (2). The tread portion has at least one rubber layer composed of a rubber composition containing rubber components. The tanδ values ​​of the rubber composition at 5°C (5°C tanδ), 20°C (20°C tanδ), and 50°C (50°C tanδ), measured at a frequency of 10 Hz and a tensile strain of 2.5%, satisfy the following equations (3) and (4): Formula (1) 1963.4≤(π / 4)×(Dt^2 / Wt)≤2827.4 Equation (2) 0.10≤La / Lb≤0.50 Formula (3) 0.01≤|20℃ tanδ + 50℃ tanδ| / 2≤0.17 Formula (4) 0.30≤|5℃ tanδ + 20℃ tanδ| / 2≤0.60, The tanδ of the rubber composition at 5°C is 0.65 or higher.

2. The pneumatic tire according to claim 1, wherein, The value of equation (3) is less than 0.

15.

3. The pneumatic tire according to claim 1 or 2, wherein, The value of equation (4) is 0.35 to 0.

55.

4. The pneumatic tire according to claim 1 or 2, wherein, The value of equation (3) is less than 0.

14.

5. The pneumatic tire according to claim 1 or 2, wherein, The value of equation (4) is 0.40 to 0.

55.

6. The pneumatic tire according to claim 1 or 2, wherein, The tanδ of the rubber composition at 5°C is 0.70 or higher.

7. The pneumatic tire according to claim 1 or 2, wherein, The tanδ of the rubber composition at 20°C is less than 0.

25.

8. The pneumatic tire according to claim 1 or 2, wherein, The tanδ of the rubber composition at 20°C is below 0.

20.

9. The pneumatic tire according to claim 1 or 2, wherein, The tanδ of the rubber composition at 20°C is less than 0.

15.

10. The pneumatic tire according to claim 1 or 2, wherein, The total length Lb of the lateral side components of the lateral groove in the tire shoulder ground contact portion sh The total length Lb of the lateral side component of the sipe in the tire shoulder ground contact portion and 1. sh The sum of 2 Lb sh The total length Lb of the transverse side component of the transverse trench in the central grounding portion ce The total length Lb of the transverse side component of the knife groove in the central grounding portion and 1. ce The sum of 2 Lb ce The ratio Lb sh / Lb ce For Lb sh / Lb ce <1.

11. The pneumatic tire according to claim 1 or 2, wherein, The width of at least one of the central grounding portions is more than 1.4 times the depth of the circumferential groove adjacent to it in the lateral direction of the tire.

12. The pneumatic tire according to claim 1 or 2, wherein, When the ground contact area of ​​the tread is set to St, and the sum of the total area of ​​the circumferential grooves Sg1 and the total area of ​​the lateral grooves and the sipes Sg2 is set to Sg, St and Sg satisfy the following equation (6). Equation (6) 0.15≤Sg / St≤0.

35.

13. The pneumatic tire according to claim 12, wherein, Sg1 / St is 0.09–0.16, and Sg2 / St is 0.08–0.

14.

14. The pneumatic tire according to claim 1 or 2, wherein, The ratio of the value of equation (3) to the value of equation (2) is 0.30 to 1.

05.

15. The pneumatic tire according to claim 1 or 2, wherein, The ratio of the value of equation (4) to the value of equation (2) is 2.1 to 3.

8.

16. The pneumatic tire according to claim 12, wherein, The ratio of the value of equation (4) to the value of equation (6) is 1.7 to 2.

7.

17. The pneumatic tire according to claim 1 or 2, wherein, The tires mentioned are passenger car tires.

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