Process for preparing aqueous dispersions of magnetic polymer particles with sharp grain size distribution.

摘要

Process for preparing aqueous dispersions of particles of magnetisable polymer, having a narrow grain size distribution, from aqueous dispersions having a wide grain size distribution, characterised in that: a) the quantity of water of the aqueous dispersion having a wide distribution is adjusted so that the content by weight in particles of magnetisable polymer lies between approximately 1 and 40 % of the said dispersion; b) the concentration in surfactant of the dispersion obtained at stage a) is increased in order to obtain two phases, a so called liquid phase and a so called solid phase; c) the two phases are separated; d) stages a), b) and c) are optionally repeated on the solid phase as many times as necessary; e) the aqueous dispersion having a narrow grain size distribution is recovered.