Stable liquid formulations of anionic dyes

1. A concentrated aqueous solution, comprising the salt or the free acid or mixtures thereof, of at least one anionic dye of the formula

wherein

D is a radical of the formula (a)

wherein

R 1 , R 2 , R 3 , are independently H; C 1-4 alkyl; C 1-4 alkoxy, —SO 3 H; —OH or —CN; or independently —SO 2 —Y or —O—Y, wherein Y is an unsubstituted C 1-4 -alkenyl group or an unsubstituted C 1-4 alkyl group or wherein Y is an NC—, HO—, HOSO 3 —, halogen-substituted C 1-4 -alkenyl group or an NC—, HO—, HOSO 3 —, halogen-substituted C 1-4 alkyl group or Y is —NR 11 R 12 wherein R 11 and R 12 are independently H, C 1-4 alkyl or substituted C 1-4 alkyl or combine with the interjacent nitrogen to form a five- or six-membered ring optionally comprising one or two or three heteroatoms, in which case the heterocyclic ring is unsubstituted or the heterocyclic ring is substituted by one or two C 1-4 alkyl groups,

or D is a bicyclic ring system unsubstituted or substituted with C 1-4 alkoxy, —SO 3 H; —OH or —CN; or independently —SO 2 —Y or —O—Y, wherein Y is an unsubstituted C 1-4 -alkenyl group or an unsubstituted C 1-4 alkyl group or wherein Y is an NC—, HO—, HOSO 3 —, halogen-substituted C 1-4 -alkenyl group or an NC—, HO—, HOSO 3 —, halogen-substituted C 1-4 alkyl group or Y is —NR 11 R 12 where R 11 and R 12 are each as defined above, wherein each of the rings are, optionally, and independently a five-membered or six-membered ring, wherein the five- or six-membered rings, optionally include one or two or three heteroatoms and this bicyclic ring system is not further substituted by substituents attached via azo groups, and

M is a bridging phenyl group unsubstituted or substituted by C 1-4 alkyl, C 1-4 alkoxy, hydroxyl, carboxyl, sulpho, cyano or halogen,

and

when n=1, B is hydrogen, an unsubstituted aryl radical, a substituted aryl radical, or a substituted triazine derivative of the formula

wherein X 1 and X 2 are independently unsubstituted amine —NH 2 or substituted amine —NR 21 R 22 wherein R 21 and R 22 are independently: H, C 1-4 alkyl or substituted C 1-4 alkyl, or combine with the interjacent nitrogen to form a five- or six-membered ring optionally comprising one or two or three heteroatoms, in which case the heterocyclic ring is unsubstituted or the heterocyclic ring is substituted by one or two C 1-4 alkyl groups

or when n=2, B is a bridge of the formula

or a bridge of the formula

where X 1 is defined above

and 2-(2-butoxyethoxy) ethanol.

2. A concentrated aqueous solution according to claim 1 , wherein the at least one dye of the formula I is a dye of the formula I′

3. A concentrated aqueous solution according to claim 1 , wherein

D is a radical of the formula (a′)

wherein

R 1 , R 2 , R 3 , are independently H; C 1-4 alkyl C 1-4 alkoxy; —SO 3 H; —OH or —CN;

M is a bridging phenyl group unsubstituted or substituted by C 1-4 alkyl, C 1-4 alkoxy; sulpho, carboxyl, or hydroxyl and

B is H, an unsubstituted phenyl group or substituted phenyl group or a substituted triazine derivative of the formula

where X 1 and X 2 are independently as defined above and n=1.

4. A concentrated aqueous solution according to claim 1 , wherein the concentrated aqueous solution comprises 5% to 40% by weight of the at least one dye of the formula I, 5-40% by weight of 2-(2-butoxyethoxy) ethanol and 20% to 90% by weight of water.

5. A concentrated aqueous solution according to claim 1 , wherein the concentrated aqueous solution comprises 5% to 40% by weight of the at least one dye of the formula I, 5% to 40% by weight of 2-(2-butoxyethoxy) ethanol, 3-10% by weight of a water-soluble organic solubilizer and 10% to 88% by weight of water.

6. A concentrated aqueous solution according to claim 1 , wherein the concentrated aqueous solution comprises 10% to 30% by weight of the at least one dye of the formula I, 10% to 30% by weight of 2-(2-butoxyethoxy) ethanol, 3-6% by weight of a water-soluble organic solubilizer and 34% to 77% by weight of water.

7. An inkjet ink comprising at least one concentrated aqueous solution according to claim 1 .

8. A method for dyeing and/or printing a hydroxyl-containing substrate comprising the step of contacting at least one concentrated aqueous solution according to claim 1 with the hydroxyl-containing substrate.

9. A hydroxyl-containing substrate dyed and/or printed by the process according to claim 8 .

10. A hydroxyl-containing substrate according to claim 9 wherein the hydroxyl-containing substrate is paper.

11. A method for producing an inkjet ink, comprising the step of combining a concentrated aqueous solution according to claim 1 , with at least one additional chemical and/or water.