concentrated solutions lagerstabile waessrige yellow stilbenazo (xy) dyes.

摘要

The process for preparing concentrated stable aqueous solutions of yellow stilbeneazo(xy) dyes which are obtained by self-condensation of 4-nitrotoluene-2-sulphonic acid in alkali metal hydroxide solution by conversion of the sparingly soluble alkali metal dye salt by double cation exchange via a lipophilic ammonium salt into a water-soluble alkanolammonium salt is characterised in that the double ion exchange is carried out in a 2-phase system of nitrobenzene/water and in that the first ion exchange is effected with a di- or trialkylamine of 12 to 40 carbon atoms in total and the second with a C2-C4-mono-, -di- or -trialkanolamine. …??The dye solutions thus obtained are suitable in particular for dyeing paper.