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US-12617238-B2 - Pneumatic tire

US12617238B2US 12617238 B2US12617238 B2US 12617238B2US-12617238-B2

Abstract

Provided is a pneumatic tire that has substantially improved crack resistance performance and durability performance; and the pneumatic tire has a tread portion with grooves formed on the surface, the tread portion is formed of a first rubber composition constituting a groove bottom portion, and a second rubber composition adjacent to the first rubber composition on the inner side of the groove bottom portion in the tire radial direction; and the acetone extractable content of the first rubber composition: E1 (% by mass) and the acetone extractable content of the second rubber composition: E2 (% by mass) satisfy (E1−E2)<20, and, when the tire is assembled to a standardized rim and the internal pressure is 250 kPa, the cross-sectional width of the tire Wt (mm), the outer diameter Dt (mm), and the volume of the space occupied by the tire: virtual volume V (mm 3 ) satisfy following (formula 1) and (formula 2). 1700 ≦ ( Dt 2 × π / 4 ) / W ⁢ t ≦ 2827.4 ( formula ⁢ 1 ) [ ( V + 1.5 × 10 7 ) / W ⁢ t ] ≦ 2.88 × 10 5 ( formula ⁢ 2 )

Inventors

  • Kenji HAMAMURA
  • Hiroki Kawai
  • Subaru TOYA

Assignees

  • SUMITOMO RUBBER INDUSTRIES, LTD.

Dates

Publication Date
20260505
Application Date
20210901

Claims (13)

  1. 1 . A pneumatic tire having a tread portion with grooves formed on an outer surface and a cord layer below the outer surface, wherein the tread portion includes a groove bottom portion Gd that is formed of a first rubber composition and a second rubber composition adjacent to the first rubber composition on an inner side of the groove bottom portion Gd in the tire radial direction, wherein the groove bottom portion Gd has a thickness which is a distance in the tire radial direction from the groove bottom surface to the cord layer; the first rubber composition has a loss tangent (0° C. tan δ) of 0.72 or more, measured under the conditions of 0° C., a frequency of 10 Hz, an initial strain of 10%, and a dynamic strain rate of 2.5%; a ratio of the loss tangent (0° C. tan δ) of the first rubber composition to the thickness of the groove bottom portion Gd (mm) (0° C. tan δ/Gd) is 0.16 or less; an acetone extractable content of the first rubber composition: E1 (% by mass) and an acetone extractable content of the second rubber composition: E2 (% by mass) satisfy (E1−E2) is 7 or less, wherein E1 and E2 are not equal; the first rubber composition has the acetone extractable content E1 (% by mass) of 26% by mass or more; the second rubber composition has the acetone extractable content E2 (% by mass) of 37% by mass or more; when the tire is assembled to a standardized rim and has an internal pressure of 250 kPa, a cross-sectional width of the tire Wt (mm), an outer diameter Dt (mm), and a volume of the space occupied by the tire: virtual volume V (mm 3 ) satisfy (formula 1) and formula 2), 1 ⁢ 7 ⁢ 0 ⁢ 0 ≤ { D ⁢ t 2 × π / 4 ) / Wt ≤ 2827.4 ( formula ⁢ 1 ) [ { V + 1.5 × 10 7 ) / Wt ] ≤ 2.88 × 10 5 ; ( formula ⁢ 2 ) and Wt is 199 mm or more and Dt is 665 mm or less, or Wt is 229 mm or more and Dt is 718 mm or less; and (E1−E2)×Wt is 1603 or less.
  2. 2 . The pneumatic tire according to claim 1 , wherein, when the tire is assembled to the standardized rim and the internal pressure is 250 kPa, the outer diameter of the tire: Dt (mm), and a cross-sectional height of the tire: Ht (mm) satisfy 470≤(Dt−2×Ht).
  3. 3 . The pneumatic tire according to claim 1 , wherein the 0° C. tan δ is 0.75 or more.
  4. 4 . The pneumatic tire according to claim 1 , wherein the tread has multiple circumferential grooves that extend continuously in the tire circumferential direction, and a total cross-sectional area of the plurality of circumferential grooves is 10 to 30% of a cross-sectional area of the tread portion.
  5. 5 . The pneumatic tire according to claim 1 , wherein the tread has multiple lateral grooves extending in the axial direction of the tire, and a total volume of the plurality of lateral grooves is 2.0 to 5.0% of a volume of the tread portion.
  6. 6 . The pneumatic tire according to claim 1 , wherein the 0° C. tan δ/Gd is 0.14 or less.
  7. 7 . The pneumatic tire according to claim 1 , wherein the pneumatic tire has an aspect ratio of 34% to 44%.
  8. 8 . The pneumatic tire according to claim 1 , wherein the following (formula 3) is satisfied, [ ( V + 2. × 10 7 ) / Wt ] ≦ 2.88 × 10 5 . ( formula ⁢ 3 )
  9. 9 . The pneumatic tire according to claim 8 , wherein the following (formula 4) is satisfied, [ ( V + 2.5 × 10 7 ) / Wt ] ≦ 2.88 × 10 5 . ( formula ⁢ 4 )
  10. 10 . The pneumatic tire according to claim 1 , wherein the pneumatic tire has an aspect ratio of 40% or more.
  11. 11 . The pneumatic tire according to claim 10 , wherein the pneumatic tire has the aspect ratio of 45% or more.
  12. 12 . The pneumatic tire according to claim 11 , wherein the pneumatic tire has the aspect ratio of 47.5% or more.
  13. 13 . A pneumatic tire having a tread portion with grooves formed on the surface, wherein the tread portion includes a groove bottom portion that is formed of a first rubber composition and a second rubber composition adjacent to the first rubber composition on the inner side of the groove bottom portion in the tire radial direction; the first rubber composition has an acetone extractable content E1 (% by mass) of 26% by mass or more; the second rubber composition has an acetone extractable content E2 (% by mass) of 37% by mass or more; and the acetone extractable content E1 (% by mass) and the acetone extractable content E2 (% by mass) satisfy (E1−E2) is 7 or less, wherein E1 and E2 are not equal; and when the tire is assembled to a standardized rim and has an internal pressure of 250 kPa, then a cross-sectional width of the tire Wt (mm), an outer diameter Dt (mm), and a volume of the space occupied by the tire: virtual volume V (mm 3 ) satisfy (formula 1) and (formula 2), 1 ⁢ 7 ⁢ 0 ⁢ 0 ≤ { D ⁢ t 2 × π / 4 ) / Wt ≤ 2827.4 ( formula ⁢ 1 ) [ { V + 1.5 × 10 7 ) / Wt ] ≤ 2.88 × 10 5 ; ( formula ⁢ 2 ) and Wt is 199 mm or more and Dt is 665 mm or less, or Wt is 229 mm or more and Dt is 718 mm or less; and (E1−E2)×Wt is 1603 or less.

Description

TECHNICAL FIELD The present invention relates to pneumatic tires. BACKGROUND ART In recent years, there has been a growing demand for automobiles to be more fuel-efficient due to growing interest in environmental issues and economic efficiency; and there is also a strong demand for improved fuel efficiency. The fuel efficiency of a tire can be evaluated by its rolling resistance, and it is known that the lower the rolling resistance, the better the fuel efficiency of tire. Therefore, it has been proposed to reduce the rolling resistance by modifying the shape of the tire and the composition of the rubber composition constituting the tread portion of the tire (for example, Patent documents 1 to 4). PRIOR ART DOCUMENTS Patent Document [Patent document 1] JP 2018-178034 A[Patent document 2] JP 2019-089911 A[Patent document 3] WO 2018/186367 A[Patent document 4] JP 2019-206643 A SUMMARY OF INVENTION Problem to be Solved by the Invention However, in tires manufactured using the above-mentioned conventional technology, cracks may occur at the bottom of the grooves (circumferential grooves and lateral grooves) formed in the tread (at the groove bottom), and their durability is not sufficient. Therefore, an object of the present invention is to provide a pneumatic tire having sufficiently improved crack resistance and durability. Means for Solving the Problem The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and have found that the above-mentioned problems can be solved by the invention described below, and have completed the present invention. The invention according to a first embodiment is a pneumatic tire having a tread portion with grooves formed on the surface, whereinthe tread portion is formed of a first rubber composition constituting a groove bottom portion, and a second rubber composition adjacent to the first rubber composition on the inner side of the groove bottom portion in the tire radial direction; andthe acetone extractable content of the first rubber composition: E1 (% by mass) and the acetone extractable content of the second rubber composition: E2 (% by mass) satisfy (E1−E2)<20, and when the tire is assembled to a standardized rim and the internal pressure is 250 kPa, the cross-sectional width of the tire Wt (mm), the outer diameter Dt (mm), and the volume of the space occupied by the tire: virtual volume V (mm3) satisfy following (formula 1) and (formula 2). 1700≦(Dt2×π/4)/W⁢t≦2827.4(formula⁢ 1)[(V+1.5×107)/W⁢t]≦2.88×105(formula⁢ 2) The invention according to a second embodiment is the pneumatic tire according to a first embodiment, wherein following (formula 3) is satisfied. [(V+2.×107)/W⁢t]≦2.88×105(formula⁢ 3) The invention according to a third embodiment is the pneumatic tire according to a second embodiment, wherein following (formula 4) is satisfied. [(V+2.5×107)/W⁢t]≦2.88×105(formula⁢ 4) The invention according to a fourth embodiment is the pneumatic tire according to any one of embodiments one to three, wherein, when the tire is assembled to a standardized rim and the internal pressure is 250 kPa, the outer diameter of the tire: Dt (mm), and the cross-sectional height of the tire: Ht (mm) satisfy 470≤(Dt−2×Ht). The invention according to a fifth embodiment is the pneumatic tire according to any one of embodiments one to four, wherein the loss tangent (0° C. tan δ) of the first rubber composition, measured under the conditions of a temperature of 0° C., a frequency of 10 Hz, an initial strain of 10%, and a dynamic strain rate of 2.5% is 0.72 or more. The invention according to a sixth embodiment is the pneumatic tire according to a fifth embodiment, wherein the 0° C. tan δ is 0.75 or more. The invention according to a seventh embodiment is the pneumatic tire according to any one of embodiments one to six, wherein the pneumatic tire has an aspect ratio of 40% or more. The invention according to an eighth embodiment is the pneumatic tire according to a seventh embodiment, wherein the pneumatic tire has an aspect ratio of 45% or more. The invention according to a ninth embodiment is the pneumatic tire according to an eighth embodiment, wherein the pneumatic tire has an aspect ratio of 47.5% or more. The invention according to a tenth embodiment is the pneumatic tire according to any one of embodiments one to nine, wherein the E1, E2, and Wt satisfy the following (formula 5). (E⁢1-E⁢2)×Wt<5×103(formula⁢ 5) The invention according to an eleventh embodiment is the pneumatic tire according to a tenth embodiment, wherein the following (formula 6) is satisfied. (E⁢1-E⁢2)×Wt<4×103(formula⁢ 6) The invention according to a twelfth embodiment is the pneumatic tire according to an eleventh embodiment, wherein the following (formula 7) is satisfied. (E⁢1-E⁢2)×Wt<3×103(formula⁢ 7) The invention according to a thirteenth embodiment is the pneumatic tire according to any one of embodiments one to twelve, whereinthe tread has mult