PROCESS FOR PRODUCING FINE MAGNETIC-SUBSTANCE PARTICLE, FINE MAGNETIC-SUBSTANCE PARTICLE OBTAINED BY THE SAME, AND PROCESS FOR PRODUCING MAGNETIC FLUID OR MAGNETIC-SUBSTANCE PRODUCT

摘要

A process for producing fine magnetic-substance particles. By the process, monodisperse fine magnetic-substance particles can be produced. The product is self-dischargeable and causes no clogging. The process does not necessitate a high pressure and attains high productivity. At least two fluids are used in the process. At least one of the fluids is a fluid containing at least one raw material for a magnetic substance. At least one of the fluids other than that fluid is a fluid containing at least one precipitant for fine magnetic-substance particles. These fluids are caused to meet each other in a thin-film fluid formed between treatment planes which are disposed face to face so as to be capable of being brought near to or apart from each other and at least one of which rotates with respect to the other. Thus, fine magnetic-substance particles are precipitated in that thin-film fluid to obtain fine magnetic-substance particles.