PURPOSE: To manufacture finely powdered aluminosilicate contg. little impurities and having superior whiteness and a particle size distribution controlled to a small and narrow range by reacting glassy polyvalent metal aluminosilicate and a monobasic acid under specified conditions.
CONSTITUTION: Glassy polyvalent metal aluminosilicate formed by melting and represented by the formula (where M is a II, IV or VIII group metal in the periodic table or Mn; k is the valence of metal M; n=0.3W5; and m≤3) is pulverized to ≤80μ maximum particle size and mixed with water to prepare an aqueous slurry of ≤50% concn. To this slurry is added a monobasic acid such as nitric acid or formic acid by 0.3W1.5 equiv. to the amount of the polyvalent metal so that the pH is adjusted to 1.3W5 for most of the time from the start of the mixing of them to the end, and they are reacted. The resulting soln. contg. water soluble polyvalent metal salt and the resulting insoluble finely powdered aluminosilicate are then subjected to solid-liq. separation.
NAITOU HIROYUKI
TAKAI KIYOSHI
SATOU TOSHIO
OBANA MICHIAKI
