| 摘要 |
PROBLEM TO BE SOLVED: To obtain excellent dispersion stability by blending fine silica particles having the surfaces modified through esterification with an alcohol-modified silicone oil having at least a specified number of hydroxyl groups as substituents. SOLUTION: At least one of silicone oils modified with a polyhydric alcohol, represented by formulas II to V (wherein R<1> is a 1-6C alkyl, an aromatic group, etc.; R<2> is a 1-18C alkyl, an aromatic group, etc.; R<3> is a 1-18C alkyl, polyoxyalkenyl, etc.; m is 0 to 1,000; and n is 1 to 1,000), for example, that of formula I (wherein n is 16 to 20) is dissolved in, e.g. toluene solvent. This solution is mixed under stirring with fine silica particles having a primary particle diameter of about 0.01-50μm, the mixture is heated under reflux to effect esterification, and the product is separated to give fine silica particles having modified surfaces with the number of bonding groups of about 0.1-6.0/mm<2> . A silicone oil is blended with about 0.1-50wt.% of the fine silica particles having modified surfaces and a polarization accelerator comprising a polyhydric alcohol, such as triethylene glycol, in an amount of about 1-100wt.% based on the fine silica particles to give an electroviscous fluid. |
