Printing or dyeing with water-insoluble dye - which is recovered by pptn. using acid treatment to separate precipitant and/or flocculant

摘要

Printing or dyeing of fibrous materials with water-insol. dyes involves applying an aq. liquor or paste, then rinsing and/or washing. The dye in the dye and/or after-treatment liquor is pptd. using precipitant (I) and/or flocculant (II) and sepd. with (I) and/or (II) by filtering or centrifuging. The novelty comprises sepg. (I) and/or (II) from the dye by acid treatment before filtering or centrifuging and isolating the dye. The dye, (I) and (II) and the rinsing and/or washing liquors can be re-used. Pref. a vat dye, leuco vat ester dye, sulphur dye or disperse dye is used. Acid treatment is carried out with HCl.