Process for the production of pigments of the dioxazine series

摘要

Dioxazine pigments are made by heating to at least 100 DEG C. a stirrable mixture consisting substantially of one or several water-soluble non-oxidizing inorganic salts, the aqueous solution of which is not alkaline, and of optionally further substituted 2 : 5 - bis - (21 - alkoxy - phenylamino)-, 2 : 5 - bis - (21 - cycloalkoxy - phenylamino)-, 2 : 5 - bis - (21 - benzyloxy - phenylamino)- or 2 : 5 - bis - (21 - phenoxy - phenylamino) - 1 : 4 - benzoquinone, the weight ratio of salts to benzoquinone being about 10 : 1 to 1 : 2. Organic solvents and an acid condensing agent may also be present. Examples are given.