Nissan Chemical Industries Limited

Yoshito Yuri

Makoto Tsugeno

Masao Kubo

Tokumi Mochiyama

Yasushi Takako

Silica particles having an average particle size of 5 to 100 .mu.m, a BET specific surface area of not more than 20 m.sup.2 /g and a pore volume of not more than 0.1 ml/g, each of which has on its surface a plurality of protuberances with a smooth configuration , a diameter at half the protuberance height of the said protuberance being 0.2 to 5.0 .mu.m and a height of the said protuberance being 0.2 to 4.0 .mu.m, and a process for producing the silica particles, which comprises (A) reacting hydrosilicofluoric acid, ammonium silicofluoride or a mixture thereof with ammonia in an aqueous medium to form a silica slurry, (B) separating a silica from the silica slurry, and (C) calcining, after optionally drying, the separated silica at a temperature of not less than 500.degree. C.

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Ube, Japan

Yoshito Yuri