Aqueous solutions of direct dyes
The invention relates to an aqueous dye solution comprising a) 5 to 30% by weight of an anionic or cationic direct dye, b) 0.01 to 5% by weight of the compound of formula (1), in which M represents hydrogen, an alkali metal or alkaline earth metal, ammonium or ammonium, that is mono-, di-, tri- or tetra-substituted by C 1 -C 4 alkyl or C 2 -C 4 hydroxyalkyl or mixtures thereof, c) 0 to 10% by weight of an inorganic or an organic acid, d) 0 to 20% by weight of further additives and e) water to complete to 100%, with the proviso that direct dyes of the formula (2) in which K is a residue of a coupling component of the acetoacetanilide, pyridone, pyrazolone or pyrimidine series and M is as defined above, are excluded, a process for their preparation and the use thereof for dyeing paper.
1. A storage stable aqueous dye solution consisting of:
a) 5 to 30% by weight of an anionic or cationic direct dye;
b) 0.01 to 5% by weight of a compound of formula (1)
wherein
M is hydrogen, an alkali metal or alkaline earth metal, ammonium or ammonium that is mono-, di-, tri- or tetra-substituted by C 1 -C 4 alkyl or C 2 -C 4 hydroxyalkyl or mixtures thereof;
c) 0 to 10% by weight of an inorganic or an organic acid;
d) 0 to 20% by weight of further additives, said further additives selected from the group consisting of water-soluble organic solubilizers, hydrotropic agents, viscosity regulators, dispersing agents, microbiocides, and pH adjusting agents; and
e) water to complete to 100%;
with the proviso that direct dyes of formula (2)
wherein
K is a residue of a coupling component of an acetoacetanilide, a pyridone, a pyrazolone, or a pyrimidine; and
M is as defined above,
are excluded.
2. The storage stable aqueous dye solution according to claim 1 , wherein the anionic direct dye contains at least one sulfonic acid and/or carboxylic acid group and is derived from a metal-free or metallic monoazo, disazo, or -polyazo dye, a pyrazolone dye, a thioxanthone dye, an oxazine dye, a stilbene dye, a formazan dye, an anthraquinone dye, a nitro dye, a methane dye, a triphenylmethane dye, a xanthone dye, a naphthazarine dye, a styryl dye, an azastyryl dye, a naphthoperinone dye, a quinophthalone dye, or a phthalocyanine dye.
3. The storage stable aqueous dye solution according to claim 1 , wherein the cationic direct dye is a basic dye selected from the group consisting of an acridine basic dye, an anthraquinone basic dye, an azine basic dye, an azomethine basic dye, an azostyryl basic dye, a mono-, bis- or polyazo basic dye, a benzimidazole basic dye, a benzothiazole basic dye, a cyanine basic dye, a di- or triarylmethane basic dye, a ketone imine basic dye, a methane or polymethine basic dye, a naphthostyryl basic dye, a nitro basic dye, an oxazine or dioxazine basic dye, a phthalocyanine basic dye, a quinoline basic dye, a quinophthalone basic dye, a thiazine basic dye, a thiazole basic dye, and a xanthene derived basic dye.
4. The storage stable aqueous dye solution of claim 1 , wherein the direct dye is anionic.