| 摘要 |
Water-insoluble violet benzimidazolone monoazo pigments of the formula: <IMG> wherein R1, R2 and R3 each represent hydrogen, chlorine, bromine, methyl, methoxy, ethoxy, vitro or a group of the formula -COOR with R being hydrogen, methyl or ethyl, and R4 represents hydrogen, chlorine, bromine, methyl, methoxy, ethoxy or vitro group. Due to the presence of two 5-membered heterocyclic rings in the molecule, these pigments display veryhi gh thermoresistance and excellent fastness to migration.
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