# US 8,785,541 B2 · Rubber composition and run-flat tire using same

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- Number: US 8,785,541 B2
- Document ID: US8785541B2
- Status: Granted
- Kind: B2
- Application number: 12/223,609
- Filed: 2007-03-27
- Published: 2009-02-05
- Granted: 2014-07-22
- Earliest claimed: 2006-04-06
- Assignees: Sumitomo Rubber Industries, Ltd.
- Applicants: Kazuo Hochi
- Inventors: Kazuo Hochi
- Web page: https://patentgrep.com/patent/US8785541B2

## CPC

- B60C 17/00: Tyres characterised by means enabling restricted operation in damaged or deflated condition; Accessories therefor
- B60C 1/00: Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
- C08K 7/00: Use of ingredients characterised by shape
- C08K 7/06: Elements
- B60C 2001/0033: {Compositions of the sidewall inserts, e.g. for runflat}
- C08K 3/04: Carbon
- C08K 2201/016: Additives defined by their aspect ratio
- B60C: VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)

## Abstract

The present invention can provide a rubber composition, in which all of strength at break, low heat-build up property, run-flat durability and low fuel consumption can be improved since the rubber composition comprises 5 to 120 parts by weight of flake-like graphite having an average aspect ratio of 3 to 80 and an average particle diameter of 2 to 80 μm on the basis of 100 parts by weight of a diene rubber component, and a run-flat tire using the rubber composition.

## Claims

### Claim 1

A rubber composition, comprising 5 to 120 parts by weight of a flake-like graphite having an average aspect ratio of 3 to 80 and an average particle diameter of 2 to 80 μm on the basis of 100 parts by weight of a diene rubber component;
wherein said diene rubber component comprises 20 to 80% by weight of a butadiene rubber; and
wherein the graphite is layered graphite having a crystal structure of hexagonal, plate-like form.

### Claim 2 (depends on 1)

The rubber composition of claim 1, wherein said butadiene rubber is a butadiene rubber comprising syndiotactic-1,2-polybutadiene crystal.

### Claim 3 (depends on 1)

The rubber composition of claim 1, wherein a strength at break is not less than 10 MPa, and a loss modulus E″ and a complex modulus E* satisfy the following equation (1):
E″/(E*)2≦7.0×10−9 Pa−1.

### Claim 4 (depends on 1)

The rubber composition of claim 1, which is used for a reinforcing rubber layer of a sidewall part.

### Claim 5 (depends on 1)

A run-flat tire, which has a reinforcing rubber layer of a sidewall part prepared by using the rubber composition of claim 1.

### Claim 6 (depends on 1)

The rubber composition of claim 1, wherein the graphite is substantially free of carbon black.

### Claim 7

A reinforcing rubber layer of a sidewall part of a tire which comprises a rubber composition, comprising 5 to 120 parts by weight of a flake-like graphite having an average aspect ratio of 3 to 80 and an average particle diameter of 2 to 80 μm on the basis of 100 parts by weight of a diene rubber component, wherein said graphite is layered graphite having a crystal structure of hexagonal, plate-like form; and
wherein said diene rubber component comprises 20 to 80% by weight of a butadiene rubber.

### Claim 8

A run-flat tire having an improved strength at break, a low heat build-up property, improved run-flat durability and a low fuel consumption, which comprises a rubber composition, comprising 5 to 120 parts by weight of a flake-like graphite having an average aspect ratio of 3 to 80 and an average particle diameter of 2 to 80 μm on the basis of 100 parts by weight of a diene rubber component, wherein the graphite is layered graphite having a crystal structure of hexagonal, plate-like form; and
wherein said diene rubber component comprises 20 to 80% by weight of a butadiene rubber.

### Claim 9 (depends on 8)

The run-flat tire of claim 8, wherein said butadiene rubber is a butadiene rubber comprising syndiotactic-1,2-polybutadiene crystal and the graphite is substantially free of carbon black.