| 摘要 |
Perylene-3,4,9,10-dicarboximide pigments of the formula I <IMAGE> in which both X represent a radical of the formula <IMAGE> or <IMAGE> are prepared. The pigments have a specific surface area according to BET of 5 to 35 m<2>/g, a maximum in the particle size distribution between 0.1 and 1 mu m in length and 0.1 to 0.4 mu m in breadth, the ratio of length to breadth on average being 4 : 1 to 1 : 1 and the amount of the particle sizes in the total distribution being at least 50%. Crude diimide of the formula I, whose primary particles have a size between 0.05 and 0.1 mu m to at least 60 to 70% and which form agglomerates of 0.1 to 100 mu m, is recrystallised here in organic liquids, in the presence or absence of water, at temperatures between 50 and 200 DEG C, until at least 50% of the particles have a size of 0.1 to 1 mu m. |
