| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a coating magnetite particle in which the hydrophobicity is high, and which excels in dispersibility in an organic solvent, and can maintain high hydrophobicity even after distributing processing in an organic solvent. <P>SOLUTION: The coating magnetite particle includes: a core particle of a magnetite; a silica layer which covers the surface; and a silane compound layer which covers a surface of the silica layer, wherein the content of a sum total of an alkali metal and an alkaline earth metal in the silica layer is at most 50 ppm based on the weight of the coating magnetite particle. The coating magnetite particle is suitably obtained by: that a core particle of a magnetite and an alkali metal salt of a silicic acid are mixed, and a core particle on the surface of which a silica layer is formed is obtained; that the core particle in which the silica layer is formed is contacted to a cation exchange resin, and an alkali metal ion contained in the silica layer is reduced; and that the surface of the core particle in which the silica layer is formed is covered with an alkoxysilane compound, heat treatment is performed succeedingly, and the silane compound layer is formed. <P>COPYRIGHT: (C)2012,JPO&INPIT</p> |
