| 摘要 |
PURPOSE:To efficiently obtain a magnetic fluid comprising a stable and highly concentrated dispersion in a base oil having a low vapor pressure by adding a solution of a specified surface active agent in an organic solvent to an aqueous suspension of a ferrite to allow the fine ferrite particles to adsorb the surface active agent. CONSTITUTION:A solution of an alkenylsuccinimide substituted by an N- polyalkylene polyamine [e.g. a compound of formula I or II (wherein R is 12-24C hydrocarbyl or polybutenyl having a molecular weight of about 300 to 2,000; R' is 1-6C alkylene; (n) is 1 to 5; (m) is 0 to 4)] in an organic solvent insoluble or hardly soluble in water (e.g. n-hexane) is added to an aqueous suspension of fine ferrite particles to allow the ferrite particle to adsorb the substituted alkenylsuccinimide. Then, water and the organic solvent are distilled off, and the remaining fine ferrite particles containing the adsorbed substituted alkenylsuccinimide are dispersed in a base oil having a vapor pressure as low as at most 0.1mmHg at 25 deg.C, thus producing a magnetic fluid. |
