MAGNETITE PARTICLE POWDER AND METHOD FOR PRODUCING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide magnetite particle powder having excellent dispersibility and excellent hydrophobicity, and also having low flocculation properties. SOLUTION: The magnetite particle powder has a mean particle diameter of 0.05 to 1μm, and each surface of the particles of magnetite particle powder is coated with a coupling agent comprising one or more kinds selected from silicon, aluminum and titanium. The pH change value in a mixture between the magnetite particle powder and an ethanol aqueous solution is 0.1 to 1.5 by a value shown by the formula (1): the pH change value=¾A¾+¾B¾(wherein, A is the pH change value at the time when the ethanol aqueous solution having a pH 5 and the magnetite particle powder are mixed; and B is the pH change value at the time when the ethanol aqueous solution having a pH 12 and the magnetite particle powder are mixed). COPYRIGHT: (C)2006,JPO&NCIPI