Patent ID: 7828887

Claim:
A dye-based ink formulation, comprising: a dye and a solvent, wherein the solvent is selected from the group consisting of: 1,2,4-butanetriol; 1,3-butylene glycol; N-(2-hydroxyethyl)propanamide; 1,2-butyleneglycol; 2,3-butanediol; 3-methyl-1,5-pentanediol; 1,6-hexanediol; 2-methyl-2,4-pentandiol; urea; betaine sulfolane; 1,2-hydroxyethyl-2-pyrrolidinone; sulfolane; 1,5-pentanediol; 2-pyridylcarbinol; 1,4-piperazinedicarboxaldehyde; N,N-1 dimethylpropionamide; 1,4-butanediol; dipropylene glycol; N-actyl-L-cysteine; and combinations thereof, wherein the solvent is in an amount from about 5 to 30 weight percent of the dye-based ink formulation; and wherein the ink includes a black dye selected from the group consisting of 1H-Pyrazole-3-carboxylic acid, 4-[[6-[[4-[(1,5-disulfo-2-naphthalenyl)azo]-2-methoxy-5-methylphenyl]azo]-5-hydroxy-7-sulfo-2-naphthalenyl]azo]-4,5-dihydro-5-oxo-1-(4-sulfophenyl)-, lithium sodium salt; 2,7-Naphthalenedisulfonic acid, 3-[[4-[[4-[[5-(aminocarbonyl)-1-ethyl-1,6-dihydro-2-hydroxy-4-methyl-6-oxo-3-pyridinyl]azo]-2-sulfophenyl]azo]-2,5-bis(2-hydroxyethoxy)phenyl]azo]-4,5-dihydroxy-, potassium sodium salt; Cuprate(4-), [2-(amino-κN)ethanol][7-[[3-(hydroxy-κO)-4-[[1-(hydroxyl κO)-3-sulfo-7-[(2-sulfoethyl)amino]-2-naphthalenyl]azo-κN1]phenyl]azo]-1,3-naphthalenedisulfonato(6-)]-, tetrasodium (9Cl); 2,7-Naphthalenedisulfonic acid, 6-amino-4-hydroxy-3-[[7-sulfo-4-[(4-sulfophenyl)azo]-1-naphthalenyl]azo]-, tetrasodium salt (7Cl); 1,3-Benzenedicarboxylic acid, 5-[[4-(7-amino-1-hydroxy-3-sulfo-2-naphthalenyl)azo]-6-sulfo-1-naphthalenyl]azo]-, tetraammonium salt (9Cl); a black dye of formula 1: wherein X is SO 3 Q, where Q is a sodium ion, lithium ion, or a combination thereof, and where n is 1, 2 or 3; a black dye of formula 2: wherein R 1 and R 2 each independently represents a hydrogen, halogen a cyano group, a carboxy group, a sulfo group, a sulfamoyl group, a N-alkylaminosulfonyl group, and a N-phenylaminosulfonyl group; R 3 , R 4 , R 5 , R 6 , R 7 , and R 8 each independently represents a hydrogen, a halogen group, a hydroxy group, a cyano group, a carboxy group, a sulfo group, a sulfamoyl group, a N-alkylaminosulfonyl group, a N-phenylaminosulfonyl group; and n is 0 or 1; and combinations thereof.