Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1997-09-24
2000-09-05
Michl, Paul R.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
523213, C08K 340
Patent
active
061144320
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to rubber compositions obtained by compounding silica as a reinforcing agent into a diene rubber, and more particularly to rubber compositions, which are excellent in heat build-up resistance and moreover superb in tensile properties, abrasion properties and processability.
BACKGROUND ART
As much importance has been attached to saving in resources and countermeasures to environment in recent years, requirements to reduce fuel consumption of automobiles have been increasingly severe. Automobile tires have also been required to low their rolling resistance so as to contribute to reduction in the fuel consumption. In order to low the rolling resistance of tires, a rubber material capable of providing vulcanized rubber having low heat build-up is generally used as a rubber material for the tires.
It has heretofore been proposed to use a rubber composition obtained by compounding silica as a reinforcing agent with a diene rubber in place of carbon black so as to reduce heat build-up. However, the silica-compounded rubber composition has involved a problem that it cannot exhibit sufficient abrasion resistance and tensile strength compared with the carbon black-compounded rubber composition. A cause for this problem is considered to be attributed to the fact that the affinity of the silica for the diene rubber is lower than that of the carbon black, so that a reinforcing effect cannot be sufficiently developed.
In order to enhance the affinity of the silica for the diene rubber, it has heretofore been proposed to use a silane coupling agent (Japanese Patent Application Laid-Open Nos. 252431/1991 and 252433/1991, etc.). However, this method requires to use an expensive silane coupling agent in a large amount for bringing about a sufficient effect.
The use of a diene rubber with a substituent having high affinity for silica introduced therein has been investigated as another improving method. For example, a diene rubber with a tertiary amino group (Japanese Patent Application Laid-Open No. 101344/1989) introduced therein has been proposed for a diene rubber obtained by an emulsion polymerization process. Besides, a diene rubber with an alkylsilyl group (Japanese Patent Application Laid-Open No. 188501/1989), a halogenated silyl group (Japanese Patent Application Laid-Open No. 230286/1993) or a substituted amino group (Japanese Patent Application Laid-Open No. 22940/1989) introduced therein has been proposed for a diene rubber obtained by an anionic polymerization process.
However, many of the diene rubbers with these substituents introduced therein have demerits that when silica is blended with these diene rubbers, they strongly aggregate with silica to form compounds having a high Mooney viscosity, so that the resulting diene rubber compositions become poor in processability because a failure in dispersion occurs, and that the various properties of the diene rubber, such as heat build-up resistance, tensile strength and abrasion resistance, are not sufficiently improved.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a diene rubber composition which comprises a diene rubber component and silica, has good processability and is excellent in various properties such as heat build-up resistance, tensile strength and abrasion resistance.
The present inventors have carried out an extensive investigation with a view toward overcoming the above-described problems involved in the prior art. As a result, it has been found that when silica having a specified specific surface area as determined by nitrogen absorption is compounded with a specified diene copolymer rubber having an amino group, a diene rubber composition in which the Mooney viscosity of the resultant compound does not become too high, and so the resulting diene rubber composition has good processability can be provided. This diene rubber composition exhibits low heat build-up and is hence excellent in heat build-up resistance which is taken as an index to rolling resistance. Th
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Nakamura Masao
Takagishi Yukio
Michl Paul R.
Nippon Zeon Co. Ltd.
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