Method for producing a liquid formulation of salts of sulphonic-acid azo dyes
AssigneeBASF SE
InventorsGunter-Rudolf Schroeder, Juergen Decker, Helmut Reichelt, Ingo Klopp, Armin Diefenbacher, Hartwig Voss
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Abstract
A process for producing a liquid formulation of salts of sulfonated azo dyes by coupling an at least equimolar amount of diazotized aminoarylsulfonic acids I H2N—Ar—SO3H (I), where Ar is phenylene (which may be monosubstituted by sulfo) or naphthylene (which may be mono- or disubstituted by sulfo and/or monosubstituted by hydroxyl) onto the coupling product of an unsubstituted or methyl-substituted phenylenediamine with itself comprises dissolving the azo dye in a basic medium and then subjecting the solution to a nanofiltration.
Claims18
A process for producing a liquid formulation of salts of sulfonated azo dyes, which process comprises:
- (a) forming an azo dye by coupling at least an equimolar amount of diazotized aminoarylsulfonic acids of the formula I
- H2N—Ar—SO3H (I),
- wherein Ar is phenylene, which may be monosubstituted by sulfo, or naphthylene, which may be mono- or disubstituted by sulfo and/or monosubstituted by hydroxyl, onto the coupling product of an unsubstituted or methyl-substituted phenylenediamine coupled with itself;
- (b) dissolving the azo dye in a basic medium;
- and then
- (c) subjecting the solution to a nanofiltration;
- wherein the process for producing the liquid formulation avoids isolation of the dye as a solid and the liquid formulation produced has an inorganic salt content of less than 2% by weight based on 100% pure dye.
A process for producing a liquid formulation of salts of sulfonated azo dyes comprising:
- a) preparing a coupling product of an unsubstituted or methyl-substituted phenylenediamine coupled with itself;
- b) without intervening isolation of this coupling product, coupling at least an equimolar amount of diazotized aminoarylsulfonic acids of the formula I
- H2N—Ar—SO3H (I),
- wherein Ar is phenylene, which may be monosubstituted by sulfo, or naphthylene, which may be mono- or disubstituted by sulfo and/or monosubstituted by hydroxyl, onto the coupling product obtained according to a), to form a dye;
- c) dissolving the dye in a basic medium;
- and
- d) subjecting the solution obtained according to c) to nanofiltration;
- wherein the process for producing the liquid formulation avoids isolation of the dye as a solid and the liquid formulation produced has an inorganic salt content of less than 2% by weight based on 100% pure dye.
Dependencies are inferred from the claim text.