Process for drying polymeric beads and associating shading pigments therewith

摘要

A process for drying a water-wet paste containing polymeric beads without agglomeration is disclosed in which there is added to the wet paste a proportion of an organic solvent which forms an azeotrope with water, such as methyl isobutyl ketone, in an amount providing a stirrable mixture, and the solvent-containing aqueous paste is heated to remove the water as an azeotrope with the solvent and to produce a water free suspension of the beads in organic solvent. The proportion of azeotropic solvent can be minimized by adding a resinous vehicle in organic solvent solution to the solvent-containing aqueous paste after substantially all the water has been removed, and continuing the application of heat to remove undesired organic solvent and thereby increase the solids content. As a feature of the invention, a pigment which is incompatible with the azeotropic solvent, such as an aqueous dispersion of lamp black, is added to the aqueous paste either before or after the addition of azeotropic organic solvent to be present while the water is azeotropically removed to avoid flooding.