A process for producing at least one monofilament from a thermoplastic polymer material comprising at least one polyester and also nanoparticles and optionally further additives as components, comprises adding the components to an extruder as partial or complete mixtures or separately and the thermoplastic polymer material being initially strand extruded, cooled and stretched and finally heat-conditioned at a temperature in the range from 40 to 120° C. for 0.01 to 10 min. The invention further relates to using a monofilament obtained by the process in the manufacture of artificial turf, wigs and also as bristles for soft or stiff brushes.