| 摘要 |
PURPOSE:To attempt the elevation of dispersibility in an organic solvent and of compatibility in a paint film of the granular powder of an acicular magnetic iron oxide by a method wherein after the acerular hydrous ferric oxide is made to be dispersed and suspended in water, the mixture of a specified quantity of phenol resin and higher fatty acid is made to be dissolved in the aqueous suspension and the pH of the liquid is regulated. CONSTITUTION:The acicular iron oxide grain or the acicular iron oxide grain containing cobalt is made to be dispersed and suspended in water and the mixture of phenol resin like phenol, cresol, etc., having 0.5-5.0wt% against the iron oxide mentioned above and the higher fatty acid of apliphatic monocarboxylic acid, etc., having the carbon number of 8-24 are made to be dissolved in the aqueous suspension to obtain an aqueous suspension having pH of 8 or more [provided that it is made to be, (phenol resin):(higher fatty acid)=(90:5)-(5-95)]. Then after the pH of this liquid is regulated and the surface of the grains are covered with the deposit of the resin and the fatty acid, it is heated and reduced in a reducing gas at the temperature within the range of 300-550 deg.C. By this way, the dispersibility in the solvent and the compatibility in the paint film can be elevated. |
