Process for producing ultrafine powders based on polyamides, ultrafine polyamide powders and their use

A process for preparing an ultrafine powder based on a polyamide comprising preparing a suspension by suspending inorganic particles in an alcoholic medium with introduction of an energy input of greater than 1000 kJ/m3, contacting the polyamide having a relative solution viscosity ηrel in a range from 1.5 to 2.0, measured in a 0.5% m-cresol solution at 25° C., with the suspension under the action of pressure and/or temperature to generate an at least partial solution, and then precipitating the polyamide from the at least partial solution, wherein

• the suspension is prepared by, prior to introduction of an energy input of greater than 1000 kJ/m3, forming a presuspension of the inorganic particles in the alcoholic medium with introduction of an energy input of less than 1000 kJ/m3, dividing the presuspension into at least two substreams, these substreams are placed under a pressure of at least 500 bar in a high-energy mill, decompressed through a nozzle and allowed to meet one another in a gas-or liquid-filled reaction chamber, and high-energy grinding is optionally repeated at least once.