Patent ID: 7678360

Claim:
Alunite type compound particles which are represented by the following general formula (I) and have a particle size distribution sharpness Ds (=D 75 /D 25 ) of 1 to 1.4 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 and a spherical particle shape: M a [Al 1-x M′ x ] 3 (SO 4 2− ) y (OH) z .m H 2 O (I) 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.