US Patent 7547741 Preparation of polymer powders

A process for preparing a polymer powder by evaporating the volatile constituents from an aqueous dispersion of a film-forming polymer P, wherein prior to the evaporation of the volatile constituents the aqueous polymer dispersion still comprises drying assistants T, present in an amount of from 0.1 to 80% by weight, based on the polymer P of the dispersion, and there being used as drying assistant T polyvinylformamide. The polyvinylformamide used preferably has a K value (KW), determined by the method of Fikentscher in accordance with DIN 53726, of from 5 to 50.