| 摘要 |
PURPOSE:To obtain a magnetic fluid with a high saturation magnetization by causing fine ferrite particles to adsorb halogenated hydroacid salts of N- polyalkylenepolyamine-substd. alkenylsuccinimides contained in a specific soln. and dispersing the ferrite particles with the salts absorbed in a low-vapor- pressure base oil. CONSTITUTION:This magnetic fluid is produced by adding a soln. of halogenated hydroacid salts of N-polyalkylenepolyamine-substd. alkylsuccinimides in a hydrocarbon having a b.p. higher than that of water to an aq. suspension of fine ferrite particles to cause the particles to absorb the salts, removing water from the suspension, adding a flocculant soln. to the remaining hydrocarbon soln. to recover the particles with the salts absorbed thereby, and dispersing the recovered particles in a base oil with a vapor pressure at 25 deg.C of 0.1mmHg or lower. The salts are hydrochlorides, etc., of the compds. of the formula (wherein R is a 12-24C hydrocarbon group, etc.; R' is a 1-6C alkylene; (n) is 1-5; and (m) is 0-4). Pref. ferrite particles are obtd. by coprecipitation. Thus is obtd., at a high yield, a magnetic fluid which is a dispersion in a base oil (e.g. a lubricating oil) with a dispersion concn. of about 10-50wt.% and has a high saturation magnetization. |
