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
1997-11-13
2000-05-02
Cain, Edward J.
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...
524493, 52531842, 525320, 5253291, C08K 300
Patent
active
06057397&
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a rubber composition comprising a diene rubber and silica as reinforcing agent. More particularly, the present invention relates to a silica-containing diene rubber composition superior in resilience, tensile properties, abrasion property, hardness property and processability and also to a process for production of the rubber composition.
BACKGROUND ART
In recent years, as energy saving, environmental protection, etc. have come to be considered more important, the requirement for lower fuel consumption of automobiles has become increasingly severe. In this connection, tires for automobiles are required to have a smaller rolling resistance so as to be able to contribute to lower fuel consumption. In order to allow a tire to have a smaller rolling resistance, there is generally used a rubber material for tire which can give a vulcanized rubber of higher resilience.
It has heretofore been proposed to obtain a high resilience by using, as a rubber material for tire, a rubber composition comprising a diene rubber and, as a reinforcing agent, silica in place of carbon black. This silica-containing diene rubber composition, however, has had a problem in that the composition is unable to give sufficient abrasion resistance and tensile strength as compared with carbon black-containing diene rubber compositions. One reason therefor is thought to be that the affinity of silica to diene rubber is smaller than the affinity of carbon black to diene rubber, making it impossible to obtain sufficient reinforcing effects.
In order to enhance the affinity of silica to diene rubber, it has been studied to use a diene rubber into which a group having affinity to silica is introduced. For example, in the case of diene rubber produced by emulsion polymerization, there was proposed a diene rubber into which a tertiary amino group is introduced (JP-A-1-101344); and in the case of diene rubber produced by anionic polymerization, there was proposed a diene rubber into which an alkylsilyl group (JP-A-1-188501), a halogenated silyl group (JP-A-5-230286) or a substituted amino group (JP-A-64-22940) is introduced.
Many of these diene rubbers into which one of the above-mentioned groups is introduced, however, strongly adhere to silica in blending with silica, causing insufficient dispersion; therefore, the resulting blends are inferior in processability and hardness property and are not sufficiently improved in properties such as resilience, tensile strength, abrasion resistance and the like.
DISCLOSURE OF THE INVENTION
The object of the present invention lies in providing a silica-containing diene rubber composition superior in resiliene (which is an indication of rolling resistance), at least equal, in tensile strength and abrasion resistance, to carbon black-containing diene rubber compositions, and good in processability and hardness property.
The present inventors made an intensive study in order to overcome the above-mentioned problems of the prior art. As a result, the present inventors found out that a rubber composition good in processability and hardness property, high in resilience and sufficient in tensile strength and abrasion resistance is obtainable by using, as a diene rubber component to be reinforced with silica, at least one kind of hydroxyl group-containing diene rubber having a weight-average molecular weight of 50,000 or more, or a combination of at least one kind of the hydroxyl group-containing diene rubber and other diene rubber.
The present inventors found out also that a rubber composition further improved in procesability and giving a vulcanized rubber of improved properties is obtainable by, in producing a rubber composition by mixing various components, mixing a diene rubber with the total or part of a required amount of silica and, when the remainder of silica is present, mixing the resulting mixture with the remainder of silica, a reinforcing agent (e.g. carbon black, clay or talc), a vulcanizing agent, an antioxidant, a plasticizer and other compoun
REFERENCES:
patent: 3175997 (1965-03-01), Hsieh
patent: 4150014 (1979-04-01), Edwards
patent: 4357432 (1982-11-01), Edwards
"Handbook of Fillers for Plastics", ed Katz and Milewski (1987).
Abstract of Jap. Laid-Open Pat. Appln. Publ. No. 58-29812 (Feb. 22, 1983).
I. Franta: "Elastomers and Rubber Compounding Materials", Elseviers, Amsterdam (1989) pp. 410-411.
Nakamura Masao
Takagishi Yukio
Cain Edward J.
Nippon Zeon Co. Ltd.
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