Waterfast ink formulations with a novel series of anionic dyes containing two or more carboxyl groups
AssigneeHewlett-Packard Company
InventorSuraj L. Hindagolla
Life of this patent
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Abstract
Inks are provided comprising (a) a dye corresponding to the formula ##STR1## wherein W is COOH, X is H, or COOH, Y is H, COOH, or SO.sub.3 H, Z is H, COOH, or SO.sub.3 H, and R is H, CH.sub.2 COOH, or CH.sub.2 CH.sub.2 COOH; with the proviso that there are at least two COOH groups and that the number of COOH groups is equal to or greater than the number of SO.sub.3 groups, and (b) a solvent which may be water or a mixture of water and a water-soluble organic solvent provide excellent waterfast prints on paper. The inks preferably have a pH from about 7 to about 9.5.
Claims17
An ink comprising, by wt%:
- (a) from about 0.5% to about 20% dye which, in the free acid state, corresponds to the formula ##STR3## wherein W is COOH,
- X is H or COOH,
- Y is H, COOH, or SO.sub.3 H,
- Z is H, COOH, or SO.sub.3 H, and
- R is H, CH.sub.2 COOH, or CH.sub.2 CH.sub.2 COOH;
- provided that there are at least two COOH groups and that the number of COOH groups is equal to or greater than the number of SO.sub.3 groups,
- (b) up to about 30% of a water soluble organic solvent for said dye, and
- (c) water.
An ink of cliam 2 wherein there are at least two COOH groups attached directly to aromatic carbon atoms.
An ink of cliam 2 wherein W is in the para position with respect to the azo group when X is H.
An ink of cliam 2 wherein X is COOH and X and W are in the 3,5-, 3,4-, or 2,5- position with respect to the azo group.
An ink of cliam 11 wherein the salt is ammonium acetate.
An ink comprising, by wt%:
- (a) from about 1% to about 10% dye corresponding to the formula ##STR4## wherein W is COOH,
- X is H, or COOH,
- Y is H, COOH, or SO.sub.3 H,
- Z is H, COOH, or SO.sub.3 H, and
- R is H, CH.sub.2 COOH, or CH.sub.2 CH.sub.2 COOH;
- provided that there are at least two COOH groups and that the number of COOH groups is equal to or greater than the number of SO.sub.3 groups,
- (b) water, and
- (c) and sufficient buffer to maintain the ink at a pH from about 7 to about 9.5.
An ink comprising, by wt%:
- (a) from about 1% to about 10% dye corresponding to the following formula ##STR5## wherein W is COOH,
- X is H, or COOH,
- Y is H, COOH, or SO.sub.3 H,
- Z is H, COOH, or SO.sub.3 H, and
- R is H, CH.sub.2 COOH, or CH.sub.2 CH.sub.2 COOH;
- provided that there are at least two COOH groups and that the number of COOH groups is equal to or greater than the number of SO.sub.3 groups,
- (b) about 2% to about 30% water-soluble organic solvent,
- (c) water, and
- (d) and sufficient buffer to maintain the ink at a pH from about 7 to about 9.5.
An ink of cliam 14 wherein the water-soluble organic solvent is an alkanol having from 1 to 4 carbon atoms, an amide, a ketone, a ketone alcohol, an ether, a nitrogen containing heterocyclic ketone, a polyalkylene glycol, an alkylene glycol, an alkylene thioglycol, thiodiglycol, hexylene glycol, diethylene glycol, a polyol, and a lower alkyl ether of a polyhydric alcohol.
Dependencies are inferred from the claim text.