Cationic modified self-dispersing pigment dispersions and inkjet inks thereof
AssigneeE. I. Du Pont de Nemours and Company
InventorsMichael Stephen Wolfe, Michael J. Eiseman, Loretta L. Tam, Cullen Kirkpatrick
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Abstract
This invention pertains to aqueous inkjet inks containing self-dispersing pigments. The self-dispersing pigments are modified with multivalent cations.
Claims18
An aqueous pigment dispersion comprising:
- a self-dispersing pigment having at least one type of hydrophilic functional group bonded onto a surface of the self-dispersing pigment, said at least one type of hydrophilic functional group comprising a carboxyl group;
- and
- a multivalent cation selected from the group consisting of Mg2+, Ca2+, Cu2+, Al3+, Fe3+, and mixtures thereof, wherein said multivalent cation is adsorbed onto said self-dispersing pigment via ionic bonds between the multivalent cation and surface acid group on the self-dispersing pigment displacing monovalent cation(s) associating with the carboxyl group on the surface of the self-dispersing pigment, the displaced monovalent cation(s) are removed from the pigment dispersion.
A process for making an aqueous inkjet ink comprising the step of:
- (a) preparing an aqueous vehicle;
- (b) adding the aqueous vehicle to an aqueous pigment dispersion, wherein said pigment dispersion comprising a self-dispersing pigment having at least one type of hydrophilic functional group bonded onto a surface of said self-dispersing pigment, said at least one type of hydrophilic functional group comprising a carboxyl group;
- and a multivalent cation selected from the group consisting of Mg2+, Ca2+, Cu2+, Al3+, Fe3+, and mixtures thereof, wherein said cation is adsorbed onto said self-dispersing pigment via ionic bonds between the cation and surface acid group on said self-dispersing pigment displacing monovalent cation(s) associating with the carboxyl group on the surface of the self-dispersing pigment;
- and
- (c) removing the monovalent cation(s) displaced by the multivalent cation.
An inkjet ink comprising an aqueous vehicle and an aqueous pigment dispersion, wherein said pigment dispersion comprising a self-dispersing pigment having at least one type of hydrophilic functional group bonded onto a surface of said self-dispersing pigment, said at least one type of hydrophilic functional group comprising a carboxyl group;
- and a multivalent cation selected from the group consisting of Mg2+, Ca2+, Cu2+, Al3+, Fe3+, and mixtures thereof, wherein said multivalent cation is adsorbed onto said self-dispersing pigment via ionic bonds between the multivalent cation and surface acid group on said self-dispersing pigment displacing monovalent cation(s) associating with the carboxyl group on the surface of the self-dispersing pigment, the displaced monovalent cation(s) are removed from the pigment dispersion.
Dependencies are inferred from the claim text.