METHOD FOR PRODUCING A LIQUID FORMULATION OF SALTS OF SULPHONIC-ACID AZO DYES

摘要

The invention relates to a method for producing a liquid formulation of salts of sulphonic-acid azo dyes by the coupling of one at least equimolar quantity of diazotized amino aryl sulphonic acids of formula (I), H2N - Ar - SO3H, to the coupling product of a self-coupled phenylenediamine, which can be optionally substituted by methyl. In said formula, Ar represents phenylene, which can be monosubstituted by sulpho, or naphthylene, which can be monosubstituted or disubstituted by sulpho and/or monosubstituted by hydroxy. According to the method, the azo dye is dissolved in a basic solution and the mixture is then subjected to a nanofiltration.