Treatment of water-soluble dye or optical brightener, used for dyeing or optical brightening of natural or synthetic material, especially paper, uses superheated or saturated steam in pressure filtration of aqueous synthesis suspension

摘要

In the production of water-soluble dye and/or optical brightener compound(s) (A), an aqueous suspension containing (A), with a water solubility of over 0.1, preferably over 1, especially over 5 g/l at 20 degrees C, is subjected to steam pressure filtration with superheated or saturated steam at the end of chemical synthesis.