Process for the Preparation of Concentrated Solutions of Dyestuffs and of Brighteners

摘要

Process for the preparation of concentrated aqueous solutions of dyestuffs and of brighteners, the inorganic salts being separated off and the sodium salts, potassium salts and alkaline earth metal salts of the dyestuffs in the case of anionic dyestuffs and the chlorides, sulphates and methosulphates in the case of cationic dyestuffs being converted into salts which are more readily soluble, without the free acids or bases being intermediately isolated, characterised in that the inorganic salts are separated off by means of a membrane separation process and, before, during or after separating off the inorganic salts originally present, 10-500 mol%, relative to the dyestuff, of ammonium salts of the formula I wherein R<1>, R<2>, R<3> and R<4> denote hydrogen, alkyl, hydroxyalkyl, aminoalkyl, alkoxyalkyl, -(C2H4O)n-H, -(C3H6O)n-H, -[CH2- CH(CH2OH)O]n-H or -[CH2- CH(CH2OH)-CH2O]n-H, or two of the radicals R1, R2, R3 and R4, together with the N atom and optionally further hetero-atoms, denote a saturated heterocyclic ring, alkyl or alkoxy containing 1 to 20 C atoms, n denotes a number from 2 to 20 and X denotes the anion of an inorganic acid or OH, or lithium salts are added in the case of anionic dyestuffs and brighteners, and 10- 500 mol%, relative to the dyestuff, of salts of cyclic or acyclic organic acids containing, as the cation, the cation of an inorganic base are added in the case of cationic dyestuffs and brighteners, and concentrated solutions obtained by this process and their use for dyeing natural or synthetic fibre materials.