| 摘要 |
PURPOSE:To obtain a magnetic fluid composition having a stable dispersity by dispersing ferromagnetic fine particles into a dispersant consisting of at least a kind of alkylpolyphenylether oil and alkylnaphthalene oil through a surface active agent having the same structure as the dispersant in the hydrophobic group thereof. CONSTITUTION:A dispersant uses any one of alkylpolyphenylether oil and alkylnaphthalene oil or a mixture of them depending on the condition of using a magnetic fluid. Moreover a surface active agent includes in the structure thereof a non-poralized hydrophobic group and polarized hydrophinic group and the hydrophobic group has the same structure as the dispersant. Namely, in cae the dispersant is alkylpolyphenylether oil, those having the alkylpolyphenyl structure are used, for example, as the dispersant and in case the dispersant is alkylnaphthalene oil, those having the alkylnaphthalene structure are used, for example, as the dispersant. Thereby, a magnetic fluid composition, which prevents a phenomenon such as drop of sealing function due to temperature rise by friction heat during the use and assures excellent dispersity and high thermal stability, can be obtained. |
