Process for the preparation of water-soluble dyestuffs with a low salt content
AssigneeBayer Aktiengesellschaft
InventorsKonrad Nonn, Joachim Laser, Karlheinz Wolf, Reinhold Hornle, Erich Istel
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Abstract
Process for the preparation of water-soluble dyestuffs with a low salt content, characterized in that the water-soluble dyestuffs are salted out from their aqueous solutions and/or dispersions by adding salts which are volatile at temperatures of about 40.degree. C. to about 250.degree. C. under a pressure of about 10 mm Hg to about 760 mm Hg, the dyestuffs are isolated and the volatile salts are volatilized during the drying process.
Claims7
Process for the preparation of water-soluble dyestuffs with a low salt content, characterised in that the water-soluble dyestuffs are salted out from their aqueous solutions and/or dispersions by adding ammonium salts which are volatile at temperatures of about 40.degree. C. to about 250.degree. C. and under a pressure of about 10 mm Hg to about 760 mm Hg, the dyestuffs are isolated and the volatile salts are volatilised during the drying process.
Process according to any one of claims 5, 6 or 7, characterised in that anionic dyestuffs which contain a NH.sub.4.sup..sym. cation are converted, by adding stronger bases, into the salt of the stronger base, with volatilisation of NH.sub.3.
Dependencies are inferred from the claim text.