Patent ID: 6923836

Claim:
A process for preparing dyed plastics characterized in that it comprises mixing a high molecular weight organic material with a coloristically effective amount of at least one dye of the formula where R 1 is hydrogen, hydroxyl or a radical —NHCO—R 6 , where R 6 is C 1 -C 6 alkyl or unsubstituted or C 1 -C 4 alkyl- or halogen-substituted phenyl, R 2 is hydrogen, hydroxyl or a radical W—R 7 , where W is —NHCO— or —S— and R 7 is C 1 -C 6 alkyl or unsubstituted or C 1 -C 4 alkyl- or halogen-substituted phenyl, R 3 is hydrogen, R 4 is hydrogen or hydroxyl, R 5 is hydrogen, or R 3 and R 4 combine to form the radical of the formula where the ring may bear further substituents, with the proviso, that at least one of the substituents R 1 to R 4 is not hydrogen.