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AssigneeBASF SE
InventorsMichael Schmitt, Jurgen Decker, Helmut Reichelt, Gerd Rollar, Armin Diefenbacher, Hartwig Voss
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A process for producing a liquid formulation of a basic azo dye from a phenylenediamine I, which may be alkyl or alkoxy substituted, by diazotizing and coupling in acidic solution comprises diazotizing the phenylenediamine with sodium nitrite in the presence of at least two organic acids comprising at least one first acid (A) having a pkA value of ≦40 and at least a second acid (B) having a pKA value ≧4.1 and performing a nanofiltration after the coupling has ended.
A process for producing a liquid formulation of a basic azo dye from a phenylenediamine I, which may be alkyl or alkoxy substituted, by diazotizing and coupling in acidic solution, which comprises diazotizing the phenylenediamine with sodium nitrite in the presence of at least two organic acids comprising at least one first acid (A) having a pkA value of ≦4.0 and at least a second acid (B) having a pKA value ≧4.1 and performing a nanofiltration after the coupling has ended.
Dependencies are inferred from the claim text.