| 摘要 |
PURPOSE:To obtain an extremely stable magnetic fluid free from solid/liquid separation for a long period of time, by dispersing a specially treated fine ferromagnetic powder in a solvent consisting of polymerized olefin oils to which a specified nonionic surfactant is added. CONSTITUTION:A ferromagnetic powder with a hydrophobic surface is prepd. by coating the surface of each particle of a ferromagnetic powder such as magnetite with a monomolecular adsorption film of an unsaturated fatty acid ion. Then said ferromagnetic powder with the hydrophobic surface is added to a solvent consisting of polymerized olefin oils having different degrees of polymn., e.g., those having average MW of 370, 570, 730 or 820. A magnetic fluid contg. said synthetic oil as a dispersion medium is obtd. by adding a surfactant soluble in said solvent and having an HLB small than the solubility limit for said solvent. |
