| 摘要 |
PURPOSE:To obtain a magnetic fluid which has much higher saturation magnetization than that of the conventional magnetic fluid and which is practical, by employing a surface-active agent including either a nonionic or oil-soluble anion surface-active agent, and a low-volatile solution as a medium. CONSTITUTION:Cobalt fine particles of 70-120Angstrom are employed. It is preferable to employ a low-volatile solvent whose boiling temperature is, for example, 150 deg.C or lower at 1mmHg. Dispersibility is particularly improved by employing as a medium at least one selected from among diester media and saturated aliphatic hydrocarbon media. Among diester media, dicarboxylic diesters, particularly at least one selected from among diesters of saturated aliphatic dicarboxylic acids having 6-10 carbon atoms is preferably employed, the diester being represented by the formula I: ROOC(CH2)nCOOR (n=4-8) preferable saturated aliphatic dicarboxylic acids include adipic acid (n=4), azelaic acid (n=7) and sebacic acid (n=8), R is a saturated aliphatic hydrocarbon residue preferably having 3-10 carbon atoms, particularly preferably, an octyl group such as 2-ethylhexyl group having 8 carbon atoms. |
