Process for the production of a spherical-particle shape of toners for electrophotography

摘要

The invention relates to a process for producing a spherical grain shape in fine grain toners. The toners are of the type used in electrophotography for developing latent charge images. The treatment of the toner takes place in a material bed which is fluidized by gas streams which are directed against one another. In this manner the grains are subjected to a multitude of reciprocal collisions and friction stress. The intensity of the collisions and frictional stress are adjusted through selection of the operating pressure, velocity, direction and temperature of the gas streams. Thus the grains undergo permanent deformation. A classifier to separate out the super-fine portion resulting from abrasion.