US 11,807,042 B2
Pneumatic tire for heavy load
Suguru Izumo, Kobe (JP)
Assigned to SUMITOMO RUBBER INDUSTRIES, LTD., Kobe (JP)
Filed by Sumitomo Rubber Industries, Ltd., Kobe (JP)
Filed on Jan. 26, 2022, as Appl. No. 17/584,530.
Claims priority of application No. 2021-011029 (JP), filed on Jan. 27, 2021.
Prior Publication US 2022/0234388 A1, Jul. 28, 2022
Int. Cl. B60C 11/00 (2006.01); B60C 1/00 (2006.01); C08K 3/36 (2006.01); C08K 5/103 (2006.01); C08L 9/06 (2006.01); B82Y 40/00 (2011.01); C08K 3/04 (2006.01)
CPC B60C 1/0016 (2013.01) [B60C 11/0075 (2013.01); C08K 3/36 (2013.01); C08K 5/103 (2013.01); C08L 9/06 (2013.01); B60C 2200/06 (2013.01); B82Y 40/00 (2013.01); C08K 3/04 (2013.01); C08K 2201/011 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A pneumatic tire for heavy load comprising,
a tread having a cap rubber layer of a tread surface and a base rubber layer adjacent to inside in a tire radial direction of the cap rubber layer, the cap rubber layer and the base rubber layer being composed of a rubber composition comprising a filler component that includes carbon black and a rubber component that comprises an isoprene-based rubber, and
four or more belt layers inside in a tire radial direction of the base rubber layer, wherein at least one surface of an outer surface in a tire radial direction of the belt layer on the outermost side in the tire radial direction and an outer surface in the tire radial direction of the belt layer having the widest width is covered with a reinforcing rubber layer that terminates without reaching a tire equatorial plane,
wherein
the rubber component of the base rubber layer rubber composition comprises 85% by mass or more of the isoprene-based rubber,
the filler component of the base rubber layer rubber composition comprises silica and 20 to 60 parts by mass of carbon black based on 100 parts by mass of the rubber component,
the base layer has a thickness that is 1 to 70% of the tread total thickness,
the rubber composition of the base rubber layer exhibits an acetone extraction amount that is less than 4.0% by mass, wherein the acetone extraction amount is measured in accordance with JIS K 6229-3: 2015,
the rubber composition of the base rubber layer has a tan δ at 70° C. (70° C. tan δ) of less than 0.040, wherein the value of tan δ at 70° C. (70° C. tan δ) is measured in accordance with JIS K 6394: 2007,
if a modulus at 200% elongation at 23° C. of the rubber composition of the base rubber layer is defined as M200b (MPa) and a modulus at 200% elongation at 23° C. of the rubber composition of the cap rubber layer is defined as M200c (MPa), wherein the modulus at 200% elongation is measured in accordance with JIS K 6251: 2017, then M200b and M200c satisfy the following inequality (1): 0≤M200c−M200b≤5 (1), and
when the rubber composition of the base rubber layer has a strength at break at 23° C. defined as TB (MPa), wherein the strength at break is measured in accordance with JIS K 6251: 2017, and has an elongation at break at 23° C. defined as EB (%), the tan δ at 70° C. (70° C. tan δ) of the rubber composition of the base rubber layer, TB and EB satisfy the following inequality (2): TB×EB/70° C. tan δ≥4.5×105 (2).