Single-phase mixed crystals of laked monoazo dyes

摘要

Novel improved single-phase mixed crystals of monoazo dyes laked with alkaline earth metal cations and ammonium cations in a molar ratio of about 1:2 having a fine particle size and substantially better fastness properties than similar known products are excellently suitable as tinctorially strong pigments. Also claimed is a process for the preparation of a single-phase mixed crystal pigment of formula wherein E is Mg, Ca or Sr, by crystallisation from an inert hydrophilic liquid in the presence of solvated catiens E⁺⁺, NR₅R₆R₇R₈⁺, x is a number from 0.33 to 0.62 and y is a number from 0.76 to 1.34, and the concentration of solvated catiens E⁺⁺ at the beginning of the crystallisation is higher than the concentration of solvated cations NR₅R₈R₇R₈⁺.