Process for preparing a magnetic fluid

摘要

A magnetic fluid containing fine particles of ferrite stably dispersed in a low vapor pressure base oil is prepared by adding N-polyalkylenepolyamine-substituted alkenylsuccinimide (and a low vapor pressure base oil) to a suspension of fine particles of surfactant-adsorbed ferrite dispersed in a low boiling point hydrocarbon solvent, heating the resulting mixture, separating the hydrocarbon solvent therefrom, adding a low vapor pressure base oil and a specific dispersing agent to the fine particles of N-polyalkylenepolyamine-substituted alkenylsuccinimide-coated ferrite as the residues and subjecting the resulting mixture to a dispersion treatment.