PURPOSE: To prevent precipitation of solid components by contg. a non- electroconductive liq. and specified silicon-contg. material particles.

CONSTITUTION: Silicon-contg. material particles, having 0.5-10% water content, 0.5-50 μm mean particle diameter, except philosilicate, are dispersed in a nonconductive liq., reacted with a compd. forming a group of formula I [where R is a group of formula II-IV {W is Si or Ti; R1 is a straight or branched 1-4C alkyl; R2 is a group of formula V ((x) is 1-9; R' and R" are each H, a 5-20C alkyl, a 5-20C alkenyl or -(C2H4O)x-C6H5-(7-11C)alkyl; Y' and Y" are each O, NH or NR"; R" is a group of formula VI; (y) and (z) are each 1-9; (n) is 10-30; R3 is a group of CnH2n+1-COO; R4 is a group of formula VII; R5 is a 7-20C alkyl or a 7-20C alkenyl)}] at 60-300°C for 5-24 hours to reform the group of formula VIII on surfaces of silicon-contg. particles.