PROCESS FOR THE PREPARATION OF DYES WHICH CONTAIN SULFONIC ACID GROUPS AND HAVE A LOW ELECTROLYTE CONTENT

摘要

The present invention relates to a process for the preparation of dyes having a sulfo group and a low electrolyte content comprising (a) mixing at elevated temperature an aqueous solution or suspension of a dye having a sulfo group and a non-emulsifying waterinsoluble amine having 12 to 40 carbon atoms, such that approximately one equivalent of amino group of the amine is used per equivalent of sulfo group in the dye and such that the pH of the mixture is adjusted to <5 with an acid; (b) isolating the water-insoluble amine salt of the sulfo group containing dye; (c) adding a water-soluble base to said amine salt to form a water-soluble sulfonate salt; and (d) separating the water-soluble sulfonate salt from the water-insoluble amine.