The invention relates to a method for producing a thermoplastic polymer material that is filled with at least one filler, preferably calcium carbonate CaCO3, sensitive to hydrolytic degradation and optionally hygroscopic, and produced by way of polycondensation, particularly PET, wherein under vacuum conditions, constant stirring or mixing and an increased temperature, a mixture of not yet melted, optionally softened, polymer material comprising the filler is produced, wherein for this purpose a filler, which at the time of addition has not been pre-dried and has a residual moisture (H2O) of more than 500 ppm, particularly more than 1000 ppm, is used.