Print speed, print quality, bleed, and waterfastness with cationic black pigments and underprinting with anionic dyes

Abstract

A method of printing an ink onto a print medium is provided. In the method, two inks are employed, a first ink that includes at least one water-soluble color dye that has a first charge, e.g., anionic, and a second ink that includes at least one black pigment that has a second and opposite charge, e.g., cationic. The method comprises: (a) providing the first ink, which contains at least one water-soluble, anionic color dye and at least one surfactant; (b) providing the second ink, which contains at least one cationic black pigment; (c) printing in a first pass across the print medium the first ink; (d) printing the second ink over the first ink, totally covering and overlapping the first ink, whereby the cationic black pigment(s) reacts with the anionic color dye(s) to form an insoluble complex on the print medium, and the surfactant draws the vehicle into the print medium, thereby improving print speed, print quality, bleed, and waterfastness of the ink. A printed ink set is also provided. The printed ink set comprises the cationic black pigment-based ink printed over the anionic color dye-based ink.

Dependencies are inferred from the claim text.