| 摘要 |
PURPOSE:To provide the subject composition producing a large shear stress, having good electric characteristics and age stability and useful for clutches, etc., by sulfonating an aromatic vinyl compound-polyvinyl compound copolymer in the presence of a pentavalent P compound and subsequently dispersing the reaction product in an insulating liquid. CONSTITUTION:A monomer mixture comprising (A) an aromatic vinyl compound (e.g. styrene) and (B) a polyvinyl compound (e.g. divinylbenzene) as main components and, if necessary, (C) other vinyl compounds (e.g. vinyl acetate) is suspension-polymerized in the presence of a dispersing agent such as polyvinyl alcohol and a radical polymerization initiator such as azobisisobutyronitrile in an aqueous medium, and the prepared crosslinked polymer particles are sulfonated with concentrated sulfuric acid in the presence of a pentavalent phosphorus compound such as phosphorus tentaoxide to produce the spherical particles of the sulfonated polymer in the dispersion, which are mixed with and dispersed in an insulative dispersing medium (e.g. dimethyl silicone oil) to provide the objective electrically viscous fluid composition. |
