Process for the production of concentrated solutions of cationic azo dyes
AssigneeSandoz Ltd.
InventorsUlrich Blass, Roland Entschel
Life of this patent
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Abstract
Concentrated solutions of cationic azo dyes are prepared directly from sparingly soluble salts of the dye in a one-step reaction by reacting the sparingly soluble dye with a non-chromophoric carboxylate salt, the cation of which forms an insoluble or sparingly soluble salt with the anion of the starting cationic azo dye in the solvent system employed.
Claims25
A process for the production of a concentrated liquid dye preparation of a cationic azo dye, said concentrated liquid dye preparation being suitable for direct application to textiles, comprising
- a. reacting in a solvent system an insoluble or sparingly soluble cationic azo dye of the formula
- F.sup.+ A.sub.1.sup.-
- with a non-chromophoric carboxylate salt of the formula
- M.sup.+ A.sup.-
- to obtain a concentrated solution of a soluble cationic azo dye of the formula
- F.sup.+ A.sup.-
- wherein
- F.sup.+ is the cation of an insoluble or sparingly soluble cationic azo dye,
- A.sub.1 .sup.- is the anion of an insoluble or sparingly soluble cationic azo dye,
- M.sup.+ is a non-chromophoric cation, and
- A.sup.- is a non-chromophoric carboxylate anion,
- with the provisos that
- 1. the reactants and solvent system are chosen such that F.sup.+ A.sup.- is more soluble in the solvent system than is F.sup.+ A.sub.1 .sup.- ,
- 2. f.sup.+ a.sup.- is soluble enough to form a concentrated solution in the solvent system,
- 3. M.sup.+ A.sup.- and F.sup.+ A.sub.1 .sup.- are present in amounts sufficient for the preparation of a concentrated solution, and
- 4. M.sup.+ A.sup.- is soluble or partially soluble in the solvent system, and
- b. removing any precipitated salts, whereby a concentrated liquid dye preparation is obtained.
A process for the preparation of a concentrated solution of a cationic azo dye comprising (a) reacting in a solvent system an insoluble or sparingly soluble cationic azo dye of the formula
- F.sup.+ A.sub.1 .sup.-
- with a non-chromophoric carboxylate salt of the formula
- M.sup.+ A.sup.-
- to obtain a concentrated solution of a soluble cationic dye of the formula
- F.sup.+ A.sup.-
- wherein
- F.sup.+ is the cation of an insoluble or sparingly soluble cationic azo dye,
- A.sub.1 .sup.- is the anion of an insoluble or sparingly soluble cationic azo dye,
- M.sup.+ is a non-chromophoric cation, and
- A.sup.- is a non-chromophoric carboxylate anion,
- with the provisos that
- 1. the reactants and solvent system are chosen such that F.sup.+ A.sup.- is more soluble in the solvent system than is F.sup.+ A.sub.1 .sup.-,
- 2. f.sup.+ a.sup.- is soluble enough to form a concentrated solution in the solvent system,
- 3 M.sup.+ A.sup.- and F.sup.+ A.sub.1 .sup.- are present in amounts sufficient for the preparation of a concentrated solution, and
- 4. M.sup.+ A.sup.- is soluble or partially soluble in the solvent system, and
- b. removing any precipitated salts.
Dependencies are inferred from the claim text.