Water-soluble dyestuff preparations - made by mechanical - comminution in aqs dispersion esp of metal complex azo dyes

摘要

Aqs. suspensions contg. a dispersing agent and dyes of low solubility in cold water are subjected to mechanical comminution until the particle size of the dye is =20 mu and subsequently dried to a solid preparation. The suspension pref. contains 2-20% dispersing agent which is pref. an anionic type, esp. condensation products of formaldehyde and naphthalene sulphonic acid or their salts, or lignin sulphonate. The dyes are pref. nickel, cobalt, copper or chronium complexes of azo dyes which contain a complex-bound gp. derived from an amino-carboxy0 or hydroxy-gp, in the o-posn to the azo gp. The prepns. disperse very easily in cold water by simple stirring and permit easy prodn. conc. stock solns.