| abstract |
The present invention relates to methine dyes of the formula (I) and to a process for their preparation, characterized in that in formula (I). R 1 is fluorine, chlorine, CF 3 or COOR 9 , R 2 is oxygen or sulfur, R 3 is hydrogen, R 4 , R 5 and R 6 are each methyl, R 7 and R 8 are each independently hydrogen, each unsubstituted methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl or tert-butyl or 1-methyl-2-methoxyethyl, and R 9 is methyl. With the dyes of the formula (I) according to the invention, yellow to orange colorations of plastics, in particular of polyamides, can be achieved, which are distinguished by improved light fastnesses and improved thermal stability compared to the known yellow dyes used for these purposes. |