Abstract: The invention relates to thermoplastic moulded masses containing, a) at least one block copolymer (A), comprising, with relation to (A), a1) 50 to 90 wt. % of at least one styrol monomer, a2) 10 to 50 wt. % of at least one diene monomer, with the following as stabilisers, relative to the moulded mass, b) 0.001 to 0.18 wt. % of at least one benzofuranone derivative (B), c) 0.05 to 1 wt. % of at least one organic phosphite (C), and d) 0.1 to 0.3 wt. % of at least one stabiliser compound (D), selected from sterically hindered phenols and aromatic amines.