Process for the preparation of concentrated aqueous dye formulations of water-soluble organic dyes by membrane separation and with cross-flow micro-filtration to remove suspended or colloidal solids

摘要

Concentrated aqueous dye formulations of water-soluble organic dyes are prepared by desalination and concentration of corresponding crude dye solutions by means of membrane separation processes. The effectiveness of the membrane separation process on the one hand and the stability of the dye formulations on the other hand is improved if dye solutions are subjected to cross-flow microfiltration before and/or after the membrane separation process and insoluble constituents are thus removed.