Hewlett-packard Company

Roger A Brown

Hiang P Lauw

William H Wilson

Loren E Johnson

Robert P Rhodes

James W Baker

Thomas E Price

George P Walsh

Michael D Glaser

Ellen F Mason

Thomas M Przybylski

Chromatograph

A method and ink-jet ink composition are provided for reducing crystallization of Acid Yellow 23 anionic dye in ink-jet ink compositions printed on transparencies and glossy media, both film- and paper-based. The method comprises formulating the yellow ink-jet ink composition in accordance with at least one of the following three conditions: (a) a first condition, wherein the yellow ink-jet ink composition includes about 6 to 9 wt % ethylhydroxypropanediol, about 3 to 9 wt % 2-pyrrolidone, and about 3 to 9 wt % diethylene glycol; (b) a second condition, wherein the vehicle of the yellow ink-jet ink includes a buffer in amount sufficient to maintain the pH of the ink-jet ink within the range of about 5 to 7; and (c) a third condition, wherein the cation of the inorganic salt component of the ink-jet ink comprises calcium ions to the substantial exclusion of magnesium ions. While any or all of the foregoing conditions may be implemented to reduce crystallization in the yellow ink, a combination of the three is particularly efficacious. A narrower embodiment also incorporates two alternative techniques, namely reducing the dye load of the yellow ink to no more than about 3.5 wt % and increasing the thickness of the clear polymeric surface coating of the transparency or glossy media to at least about 12 .mu.m from its typical 10 .mu.m. The solution offered by the present method and ink-jet ink composition is easily and inexpensively implemented and does not sacrifice overall print quality.

Mitigation of dye crystallization in images on transparencies and glossy

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Carlsbad, CA, United States of America

Roger A Brown