| abstract |
A process for the preparation of mixed crystals of 1,4-diketopyrrolo[3,4-c]pyrroles, consisting of 1 mol each of two different compounds of formula in solid form to the temperature range from 220 DEG to 380 DEG C. A and B are, for example, each a group of formula <IMAGE> <IMAGE> wherein R1 and R2 are each independently hydrogen, chloro, bromo, C1-C4alkyl, C1-C6alkoxy, C1-C6alkylamino, phenyl or -CN, G is -O-, -NR7-, -N=N- or -SO2-, R3 and R4 are hydrogen, and R7 is hydrogen, methyl or ethyl. The mixed crystals and solid solutions obtained are excellently suited for pigmenting high molecular weight material. |