The present invention relates to thermoplastic polyamide moulding compositions which contain at least one copolyamide with at least 20% by weight polyamide 12 components and at least one aprotic compound selected from the group of N-alkylated, cyclic carboxylic acid amides with 5 to 7 ring elements and/or of urea derivatives, the alkyl rests of which are linear at the nitrogen or which form a linking of the two N-atoms, and a process for production of the moulding compositions. The thermoplastic polyamide moulding compositions are distinguished by the fact that no solid deposits are formed during thermoplastic conversion.