| 摘要 |
Alunite type compound particles represented by the following general formula (I) and having a specific value of D75/D25 when D25 is the particle diameter of particles which account for 25% of the total and D75 is the particle diameter of particles which account for 75% of the total in the cumulative particle size distribution curve measured by a laser diffraction method: Ma[Al1-xM′x]3(SO42−)y(OH)z.mH2O  (I) wherein M is at least one cation selected from the group consisting of Na+, K+, NH4+ and H3O+, M′ is at least one cation selected from the group consisting of Cu2+, Zn2+, Ni2+, Sn4+, Zr4+ and Ti4+, and a, m, x, y and z satisfy 0.8≦̸a≦̸1.35, 0≦̸m≦̸5, 0≦̸x≦̸0.4, 1.7≦̸y≦̸2.5, and 4≦̸z≦̸7, respectively. The above particles of the present invention have a small average particle diameter, are spherical, disk-like or hexagonal and have an extremely narrow particle size distribution.
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