Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1997-09-17
2000-01-18
Marquis, Melvyn I.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
524265, 524267, 524493, C08K 554
Patent
active
060158506
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 rebound resilience and moreover superb in tensile property, abrasion property 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 high rebound resilience is 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 into a diene rubber in place of carbon black so as to enhance rebound resilience. However, the silica-compounded rubber composition has involved a problem that it cannot bring about 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.
It has recently been proposed to use silica surface-treated with a silicone oil having a repeating unit of --Si(CH.sub.3).sub.2 --O-- and/or --SiHCH.sub.3 --O-- (Japanese Patent Application Laid-Open No. 248116/1994). However, this method requires to conduct a heat treatment at 250.degree. C. for about 1 hour for the surface treatment of the silica, so that a sufficient effect cannot be achieved by simply kneading a diene rubber, silica and such a silicone oil in a lot in a common roll or Banbury.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a rubber composition which comprises a diene rubber component and silica, is excellent in rebound resilience which is taken as an index to rolling resistance, exhibits tensile strength and abrasion resistance equal to or higher than those of a carbon black-compounded rubber composition and is also good in processability.
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 a silicone oil having a polar group such as an epoxy group, hydroxyalkyl group or alkoxy group is used for the purpose of enhancing the affinity of silica for a diene rubber, a rubber composition having good processability and exhibiting high rebound resilience and sufficient tensile strength and abrasion resistance can be provided even by charging the diene rubber, silica and the silicone oil having a polar group in a lot into a kneader such as a Banbury and kneading them without surface-treating silica with the silicone oil in advance, thus leading to completion of the present invention.
According to the present invention, there is thus provided a rubber composition comprising a diene rubber and silica, wherein (i) silica having a specific surface area ranging from 50 to 400 m.sup.2 /g as determined by nitrogen absorption (BET method) is compounded in a proportion of 10-150 parts by weight per 100 parts by weight of the diene rubber, and (ii) a silicone oil having a polar group at its side chain or terminal is compounded in a proportion of 0.1-50 parts by weight per 100 parts by weight of the silica.
BEST MODE FOR CARRYING OUT THE INVENTION
REFERENCES:
patent: 4753976 (1988-06-01), Yoshioka et al.
patent: 5059648 (1991-10-01), Fukushima et al.
patent: 5089554 (1992-02-01), Bomo et al.
patent: 5409969 (1995-04-01), Hamada
Nakamura Masao
Takagishi Yukio
Marquis Melvyn I.
Nippon Zeon Co. Ltd.
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