Patent ID: 8282991

Claim:
A process for producing hydrophobized silicon oxide-coated metal oxide particles, which comprises: (a) adding a silicon oxide precursor to a dispersion of metal oxide particles to form a silicon oxide film on the surface of metal oxide particles thereby to obtain a dispersion of silicon oxide-coated metal oxide particles, (b) adding a compound represented by the following formula (1) or (2) and a silicon oxide precursor to the above dispersion of silicon oxide-coated metal oxide particles thereby to obtain a dispersion of primarily hydrophobized silicon oxide-coated metal oxide particles, R 1 4-n Si(OR 2 ) n (1) R 3 3 Si—NH—SiR 3 3 (2) in the above formulae (1) and (2), R 1 is a C 1-9 alkyl group, each of R 2 and R 3 which are independent of each other, is an alkyl group, and n is an integer of from 1to 3, (c) adding a silanol-protective agent to the above dispersion of primarily hydrophobized silicon oxide-coated metal oxide particles thereby to obtain a dispersion of secondarily hydrophobized silicon oxide-coated metal oxide particles, and (d) drying the above secondarily hydrophobized silicon oxide-coated metal oxide particles thereby to obtain the hydrophobized silicon oxide-coated metal oxide particles.