# US 4,398,582 A · Pneumatic tire

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- Number: US 4,398,582 A
- Document ID: US4398582A
- Status: Granted
- Kind: A
- Application number: 06/260,552
- Filed: 1981-05-05
- Granted: 1983-08-16
- Earliest claimed: 1980-05-23
- Assignees: Bridgestone Tire Company Limited
- Inventors: Kazuaki Yuto; Toru Oniki; Nobumasa Ikeda; Itsuo Miyake
- Web page: https://patentgrep.com/patent/US4398582A

## CPC

- C08L 7/00: Compositions of natural rubber
- B60C 1/0016: {Compositions of the tread}
- C08K 3/04: Carbon
- C08L 9/06: Copolymers with styrene
- C08L 9/08: Latex
- C08L 9/00: Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
- 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
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

A pneumatic tire having remarkably low rolling resistance and high wet skid resistance without deteriorating the wear resistance is obtained by using in at least the ground-contact area of its tread, a rubber composition consisting essentially of 100 parts by weight of a mixed elastomer and 40-80 parts by weight of carbon black, the mixed elastomer consisting of 10-60 parts by weight of a solution-polymerized styrene-butadiene copolymer rubber having a bonded styrene content of 5-30% by weight and a trans-1,4 content in butadiene unit of not more than 45% by weight; 10-50 parts by weight of an emulsion-polymerized styrene-butadiene copolymer rubber having a bonded styrene content of 30-50% by weight; and 0-80 parts by weight of at least one rubber having a glass transition temperature of not higher than -50.degree. C., which is selected from the group consisting of natural rubber, synthetic polyisoprene rubber, polybutadiene rubber and an emulsion polymerized styrene-butadiene copolymer rubber having a bonded styrene content of 18-28% by weight. The use of carbon black having a specific surface area of 85-95 m.sup.2 /g, a dibutyl phthalate absorption value of 100-110 ml/100 g, a tinting strength of 95-105 and a half value width of at least 180 m.mu. in the size distribution curve of the aggregates is particularly effective for lowering the rolling resistance.

## Claims

### Claim 1

A pneumatic tire having a tread, at least the ground-contact area of which is formed of a rubber composition consisting essentially of 100 parts by weight of a mixed elastomer and 40-80 parts by weight of furnace carbon black,
said mixed elastomer consisting of
10-60 parts by weight of a solution-polymerized styrene-butadiene copolymer rubber having a bonded styrene content of 5-30% by weight and a trans-1,4 bond content in the butadiene unit of not more than 45% by weight,
10-50 parts by weight of an emulsion-polymerized styrene-butadiene copolymer rubber having a bonded styrene content of 30-50% by weight, and
0-80 parts by weight of at least one rubber having a glass transition temperature Tg of not higher than -50.degree. C., which is selected from the group consisting of natural rubber, synthetic polyisoprene rubber, polybutadiene rubber and an emulsion-polymerized styrene-butadiene copolymer rubber having a bonded styrene content of 18-28% by weight; and
said furnace carbon black having a specific surface area (N.sub.2 SA) of 85-95 m.sup.2 /g measured by the nitrogen adsorption method, a dibutyl phthalate absorption value (24M4 DBP) of 100-110 ml/100 g, a tinting strength (TINT) of 95-105 and a half value width (.DELTA.D.sub.50 (ST)) of at least 180 m.mu. in the size distribution curve of the aggregates.

### Claim 2 (depends on 1)

A pneumatic tire according to claim 1, wherein the mixed elastomer contains 10-60 parts by weight of the rubber having a glass transition temperature Tg of not higher than -50.degree. C.

### Claim 3 (depends on 1)

A pneumatic tire according to claim 1, wherein the carbon black is furnace carbon black having a specific surface area (N.sub.2 SA) of 85-92 m.sup.2 /g measured by the nitrogen adsorption method, a dibutyl phthalate absorption value (24M4 DBP) of 103-110 ml/100 g and a tinting strength (TINT) of 98-105.