| 摘要 |
PURPOSE:To obtain the titled pigment economically on an industrial scale, preventing the decomposition of the pigment and the corrosion of the apparatus caused by the generated acid, by treating a raw material composed mainly of brominated anthanthrone with a nonionic solvent to effect the crystallization, and washing and filtering the crystal. CONSTITUTION:Anthanthrone of formula I is brominated in sulfuric acid and the reaction product is poured into water to obtain fine powder of brominated anthanthrone of formula II. The powder is crystallized by using a nonionic solvent (preferably having a dipole moment of 1.0-5.0 and high boiling point, e.g. nitrobenzene), and the crystal is washed and separated by filtration to obtain the objective pigment. The crystal is preferably the one satisfying the formula 1.1<=b/a<=20 (a is length of minor axis; b is length of major axis) and having an average particle diameter (average of b) of 0.01-2mum. EFFECT:The photosensitive material produced therefrom has improved electrification rank, sensitivity and stability to repeated use. |
