PURPOSE: To easily obtain the subject composition capable of realizing significant viscosity change by electric field application, excellent in dispersion stability and fluidity under no electric field application, useful for clutches etc., comprising an electrical insulating oil as dispersion medium and specific dielectric particles as disperse phase.
CONSTITUTION: This composition comprises (A) dispersion medium consisting of an electrical insulating oil A1 such as a silicone oil [e.g. (partially octyl- or partially phenyl-substituted) polydimethylsiloxane, fluorosilicone oil] and (B) disperse phase consisting of dielectric particles (B1) 0.001-0.5μm in average diameter. The dielectric particles (B1) can be obtained by grafting a polymer [e.g. made up of structural, unit of the formula (A is COO or phenylene; R1 is H or CH3; R2 is a 1-6C alkylene; R3-R13 are each an aryl, a 1-6C alkyl, etc.; (a) ≥1; (b) and (c) are each 0-10; (d) is 0-200)] to carbon black in the electrical insulating oil A1.
MORI YOSHIKUNI
ONO SATORU
NAGASHIMA TERUHISA
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