| 摘要 |
PURPOSE:To make it possible to contain high density magnetic fine particles, to maintain a high degree of magnetization, and also to make it possible to obtain low viscosity magnetic fluid by a method wherein a solvent, magnetic fine particles and a specific dispersant which is soluble in the solvent are mixed, and excessive moisture is removed. CONSTITUTION:A solvent, magnetic fine particles, fatty acid vinyl ester polymer, which is a dispersant soluble in the solvent, and a dispersant, containing at least a kind selected from alkyl and alkenyl imide succinate, are mixed and excessive moisture is removed. For example, the electrolyte in the magnetite colloid, which is compounded with the aqueous solution of ferrous sulfide and ferric sulfide, and the aqueous solution of caustic soda, is washed and removed by water, it is filtrated, and hydrous magnetite is prepared. Then, a mixture is formed as a solvent by mixing dioctyl adipate and fatty acid vinyl ester polymer, the above-mentioned hydrous magnetite is added to the mixture, completely stirred up using a homomixer, and surplus moisture is removed completely by heating up to 12 deg.C. Lastly, a centrifugal separation is conducted to remove non-dispersion solid matter. |
