# US 11,993,709 B2 · Tread rubber composition and pneumatic tire

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- Number: US 11,993,709 B2
- Document ID: US11993709B2
- Status: Granted
- Kind: B2
- Application number: 17/273,128
- Filed: 2019-07-26
- Published: 2021-10-28
- Granted: 2024-05-28
- Earliest claimed: 2018-09-20
- Assignees: Sumitomo Rubber Industries, Ltd.
- Applicants: Sumitomo Rubber Industries, Ltd.
- Inventors: Kentaro Nakamura
- Web page: https://patentgrep.com/patent/US11993709B2

## CPC

- C08L 7/00: Compositions of natural rubber
- B60C 1/0016: {Compositions of the tread}
- C08L 2205/025: containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure
- C08L 2205/035: containing four or more polymers in a blend
- C08L 2312/00: Crosslinking
- Y02T 10/86: Optimisation of rolling resistance, e.g. weight reduction
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- B60C: VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

Provided are tread rubber compositions and pneumatic tires which are excellent in abrasion resistance. Included is a tread rubber composition containing, based on 100% by mass of a rubber component therein, 10% by mass or more of styrene-butadiene rubber and 10% by mass or more of polybutadiene rubber, and having an absolute value of change in hardness before and after heat aging, |ΔHs|, satisfying the following relationship (1) and an absolute value of change in Swell before and after heat aging, |ΔSwell|, satisfying the following relationship (2) |ΔHs|≤3.0 (1); |ΔSwell|≤20% (2).

## Claims

### Claim 1

A pneumatic tire, comprising a tread rubber composition,
comprising, based on 100% by mass of a rubber component therein, 10% by mass or more of styrene-butadiene rubber and 10% by mass or more of polybutadiene rubber, and
having an absolute value of change in hardness before and after heat aging, |ΔHs|, satisfying the following relationship (1) and an absolute value of change in Swell before and after heat aging, |ΔSwell|, satisfying the following relationship (2):
|ΔHs|≤3.0 (1);
|ΔSwell|≤20% (2),
wherein the heat aging is performed in accordance with JIS K6257:2010 under heat aging conditions at 100*C for 96 hours, wherein the hardness is measured using a type A durometer in accordance with JIS K6253 and wherein the tread rubber composition does not include a zinc dithiophosphate.

### Claim 2 (depends on 1)

The tread rubber composition according to claim 1,
wherein the rubber composition comprises sulfur and a crosslinking agent other than sulfur.

### Claim 3 (depends on 1)

The tread rubber composition according to claim 1,
wherein the rubber composition comprises a crosslinking agent other than sulfur alone as a crosslinking agent.

### Claim 4 (depends on 1)

The tread rubber composition according to claim 1,
wherein the rubber composition comprises 25% by mass or more of an isoprene-based rubber based on 100% by mass of the rubber component.