| abstract |
Alunite type compound particles represented by the following general formula (I) and having a specific value of D 75 /D 25 when D 25 is the particle diameter of particles which account for 25% of the total and D 75 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: n M a [Al 1-x M′ x ] 3 (SO 4 2− ) y (OH) z .m H 2 O (I) n wherein M is at least one cation selected from the group consisting of Na + , K + , NH 4 + and H 3 O + , M′ is at least one cation selected from the group consisting of Cu 2+ , Zn 2+ , Ni 2+ , Sn 4+ , Zr 4+ and Ti 4+ , 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. n 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. |