Hewlett-packard Company

Patricia A Wang

Robert M Amici

David J Halko

Ronald J Gambale

The ink of the invention comprises a vehicle and a colorant. The colorant is a water-insoluble pigment that has been chemically modified to be water dispersable by addition of functional groups to the surface of the pigment resulting in water soluble colorant particles. The performance of these pigments is improved by the addition of specific functional groups which provide improved black to color bleed control and high waterfastness.

Superior waterfastness and bleed control with specifically treated pigments for ink-jet printing

In accordance with the invention inks suitable for use in ink-jet printers and method for formulating the same are provided. The present dye set exhibits excellent color quality and lightfastness across a range of media. Furthermore, the dye set preserves its performance over a wide pH range, particularly low pH. This functionality across a wide pH range, enables the use of pH- sensitive bleed control mechanisms. More specifically, a specific dye set for formulating the yellow, magenta, and cyan inks is disclosed, comprising Direct Yellow 132 and Acid Yellow 23; Magenta 377 and Acid Red 52; and Direct Blue 199 and Acid Blue 9; respectively.

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Corvallis, OR, United States of America

Patricia A Wang