Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1996-06-06
1998-02-03
Cain, Edward J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
524141, 524247, 524249, C08K 552
Patent
active
057145334
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a rubber composition improved in a charging property, and a pneumatic tire produced by making use of the same.
BACKGROUND ART
In recent years, it has become important to investigate a reduction in a rolling resistance (RR) of a tire in order to save a fuel consumption of automobiles based on social requirements to energy saving and resource saving.
It is generally known that a decrease in a rolling resistance of a tire leads to a reduction in a fuel consumption, which turns a tire into a so-called low fuel consumption tire. In general, materials having a low hysteresis loss are used as tread rubber in order to reduce a rolling resistance of a tire. On the other hand, a requirement to running stability has resulted in strongly demanding rubber materials having a large frictional resistance on a wet road (wet skid resistance).
However, a relation of antinomy exists between these low rolling resistance and wet skid resistance, and therefore it has been very difficult to satisfy both characteristics at the same time.
With respect to the requirement described above, it is known that a rubber composition for a tire into which a white filler, particularly silica or aluminum hydroxide is blended causes a wet skid performance to be highly compatible with an RR.
However, because of a non-conductivity of white fillers used for rubber, pneumatic tires using the white fillers have much higher electric resistance as compared with tires comprising rubber compositions containing mainly carbon black as the filler.
As tires roll on a road, electrostatic charge is produced by friction between a road surface and tire treads. This charge readily disappears by conduction in the case of tires which are produced from rubber compositions having a higher proportion of carbon black and have a relatively low electric resistance on the tread surface. On the other hand, in the case of tires which are produced from rubber compositions having a higher proportion of white fillers and therefore have a high electric resistance on the tread surface, a pretty large amount of charge is accumulated on the tread surface thereof. Involved therein is a problem that not only an unpleasant feeling is brought about to passengers of an automobile equipped with such tires, for example, in getting off the automobile, but also electrostatic charge accumulated during driving causes producing an electromagnetic field on the tires and emitting radio waves capable of interfering with electronic equipments loaded in the car as tires roll, which indispose or disturb radio wave reception.
On the other hand, also known as a pneumatic tire improved in a charging property are tires obtained by applying conductive materials such as copper and aluminum alloys on the surface of pneumatic tires(Japanese Patent Application Laid-Open No. Sho 48-7403). However, also involved is a problem that since the tires always rub a road surface and are abraded therewith, the coating peels off soon, and therefore the antistatic effect is lost in an early stage.
Further, also known as a pneumatic tire using a rubber composition improved in a charging property are radial tires for passenger cars, in which at least surface parts of side treads are composed of rubber compositions blended with conductive carbon black (Japanese Patent Application Laid-Open No. Sho 60-90235 and Japanese Patent Application Laid-Open No. Hei 2-202936). However, also involved is a problem that while this technique provides a large effect of improving the conductivity, it markedly deteriorates the RR and therefore cancels an effect of using a white filler.
Further, known are antistatic tires in which metal wires are put into lines connecting beads with treads, and the ends of the respective metal wires are exposed (Japanese Patent Application Laid-Open No. Sho 53-147302). However, a problem exists in that producing electrostatic charge on treads themselves can not be prevented.
Further, also known is a conductive chloroprene rubber composition for a sheath m
REFERENCES:
"Surfactants" pp. 379 to 383, written by F. Kitahara et al., published by Kodansha on Apr. 20, 1979*.
"Developments of New Additives for Plastic and Rubber" pp. 167 to 176, published by K.K. C.M.C. on Feb. 25, 1983*.
"Practical Handbook for Plastic and Rubber Additives" pp. 333 to 457, published by Kagaku Kogyo sha on Jul. 20, 1989*.
*An English abstract as a concise explanation of the relevance of each thereof.
Database WPI Section Ch, Week 9335, Derwent Publications Ltd., An 93-278388 corresponding to JP-A-05 194 790.
Cataldo Franco
Hatakeyama Kazuya
Hojo Masahiro
Nohara Daisuke
Bridgestone Corporation
Cain Edward J.
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