method for the extraction of metalliseerbare black azo dyes, under which the formula of the number 16.505 16500 number and colour index, 2nd edition is presented.

摘要

Metallizable black monoazo dyestuffs are obtained by spray-drying an aqueous dyestuff solution or suspension obtained in the preparation of Diamantschwarz PV or PBB (C.I. Nos. 16500 and 16505) or mixtures of these dyes without previous isolation of the dyestuffs. The solutions or suspensions are rendered acidic prior to spray-drying and preferably have a pH of 4-6. Shading dyestuffs and/or standardizing agents may be added to the aqueous solutions or suspensions or to the product obtained after spray-drying.