A dye which is a mono-azo carboxylate dye of Formula: wherein R 3 each independently is alkyl, oxyalkyl, oxyaryl, sulfonamidoalkyl, sulfonamidoaryl, amidoalkyl, amidodialkyl, amidoaryl, amidodiaryl, halogen, thioalkyl or thioaryl; a is an integer of 0-4; D is an aromatic or heteroaromatic group, with thiophene being excluded; R 1 is selected from (a) unsubstituted or substituted C 1-12 -alkyl optionally comprising ether (C-O-C), ester and/or amide links, and optionally being substituted with Cl, Br, -CN, -NO 2, -SO 2 CH 3,or -OH; and (b) (CH 2 CH 2 O)y((CH 2) w NH) z Q; R 2 is (CH 2 CH 2 O) y' ((CH 2) w' NH) z' Q'; wherein y and y' each independently are an integer of 0-39, and ( y + y') is in the range of 3-35; w and w' each independently are 2 or 3; z and z' each independently are 0 or 1; and z = 1 when y = 0; and wherein z' = 1 when y' = 0; Q and Q' each independently is H or Y, and at least one Q or Q' is Y; wherein Y is an organic radical of Formula: wherein independently for each Y, M is H or a charge balancing cation; m, n each independently is 0-5; and the sum of ( m + n) is 1-10; R 4 each independently is H, linear or branched C 3-18 -alkyl or linear or branched C 3-18 -alkenyl, and at least one R 4 is not H; and the sum of carbon atoms in all R 4 groups is 0.4 ( y + y') to 3.0 ( y + y'). R 3 each independently is alkyl, oxyalkyl, oxyaryl, sulfonamidoalkyl, sulfonamidoaryl, amidoalkyl, amidodialkyl, amidoaryl, amidodiaryl, halogen, thioalkyl or thioaryl; a is an integer of 0-4; D is an aromatic or heteroaromatic group, with thiophene being excluded; R 1 is selected from (a) unsubstituted or substituted C 1-12 -alkyl optionally comprising ether (C-O-C), ester and/or amide links, and optionally being substituted with Cl, Br, -CN, -NO 2, -SO 2 CH 3,or -OH; and (b) (CH 2 CH 2 O)y((CH 2) w NH) z Q; (a) unsubstituted or substituted C 1-12 -alkyl optionally comprising ether (C-O-C), ester and/or amide links, and optionally being substituted with Cl, Br, -CN, -NO 2, -SO 2 CH 3,or -OH; and (b) (CH 2 CH 2 O)y((CH 2) w NH) z Q; R 2 is (CH 2 CH 2 O) y' ((CH 2) w' NH) z' Q'; wherein y and y' each independently are an integer of 0-39, and ( y + y') is in the range of 3-35; w and w' each independently are 2 or 3; z and z' each independently are 0 or 1; and z = 1 when y = 0; and wherein z' = 1 when y' = 0; Q and Q' each independently is H or Y, and at least one Q or Q' is Y; wherein Y is an organic radical of Formula: wherein independently for each Y, M is H or a charge balancing cation; m, n each independently is 0-5; and the sum of ( m + n) is 1-10; R 4 each independently is H, linear or branched C 3-18 -alkyl or linear or branched C 3-18 -alkenyl, and at least one R 4 is not H; and y and y' each independently are an integer of 0-39, and ( y + y') is in the range of 3-35; w and w' each independently are 2 or 3; z and z' each independently are 0 or 1; and z = 1 when y = 0; and wherein z' = 1 when y' = 0; Q and Q' each independently is H or Y, and at least one Q or Q' is Y; wherein Y is an organic radical of Formula: wherein independently for each Y, M is H or a charge balancing cation; m, n each independently is 0-5; and the sum of ( m + n) is 1-10; R 4 each independently is H, linear or branched C 3-18 -alkyl or linear or branched C 3-18 -alkenyl, and at least one R 4 is not H; and M is H or a charge balancing cation; m, n each independently is 0-5; and the sum of ( m + n) is 1-10; R 4 each independently is H, linear or branched C 3-18 -alkyl or linear or branched C 3-18 -alkenyl, and at least one R 4 is not H; and