Hewlett-packard Company

David J Halko

Barbara Tomlonovic Halko

Norman E Pawlowski

Bruce Cowger

Raymond J Adamic

Robert M Amici

Palitha Wickramanayake

Joseph W Tsang

Marc A Baldwin

John M Altendorf

Suraj L Hindagolla

Garold Eugene Radke

Ronald J Gambale

Patricia A Wang

Kimberly L Dahm

Oxo anions (both singly and multiply charged), such as phosphates, polyphosphates, and phosphate esters, serve as additives, and in the case of cationic dyes, may serve as replacement counter-ions, for use in thermal ink-jet inks to reduce kogation significantly. The addition of such additive essentially eliminates kogation for the life of ink pens. Further, such additives will prevent kogation for inks containing dyes with negatively-charged water-solubilizing groups, such as sulfonate and carboxylate.

Ink additives for improved ink-jet performance

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

Treatment of the inner and outer surfaces of an orifice plate for ink-jet pens with self-assembled monolayers is disclosed. The outer surface of a gold-plated orifice plate is treated with self-assembled monolayers to control wettability of the surface in order to reduce the accumulation of residual ink. The inner surface is treated with self-assembled monolayers to improve and control drop ejection. Various monolayers can also be used on the inner surface allowing for greater flexibility in controlling the steady state firing rate and uniformity of drops from a pen. In addition, treatment of orifice plate surfaces with self-assembled monolayers inhibits corrosion and contamination of the plate while presenting a uniform surface for the ink. The self-assembled monolayers for use in the present invention include thiols, disulfides, and sulfinates, having terminal functional groups which determine the wettability of the surface. A chemical bond is formed between the gold on the orifice plate and the thiol, disulfide, or sulfinate group of the monolayer compounds. The terminal functional group of the monolayer compound is therefore oriented away from the surface of the orifice plate and renders the surface either wetting or nonwetting depending on whether the term group has hydrophobic or hydrophilic characteristics.

Treatment of an orifice plate with self-assembled monolayers

An ink-jet ink for ink-jet printers is provided, comprising: (a) an aqueous-based vehicle; and (b) an anionic dye complexed with a polyamine in an amount sufficient to form a pH-insensitive, water-soluble, dye:polyamine complex that acts like a cationic dye. Further, a method of converting the anionic dye to the cationic dye for formulating the ink-jet ink having a desired pH is provided. The method comprises adding a sufficient amount of the polyamine to form the dye:polyamine complex. The dye:polyamine complex is a complex of the dye and the polyamine polymer, which is cationic. Consequently, this complex behaves as a cationic dye. These ink-jet inks show remarkable waterfastness on a variety of common office papers and are pH-insensitive and even in some cases, completely pH-independent. These inks are thus stable over a wide pH range. In addition, the ink-jet inks exhibit superior ink-to-ink bleed when printed next to a drop of another color ink which contains an anionic polymer or carboxylated colorant and resist crusting or drying in ink-jet nozzles.

Polyamines complexed to anionic dyes, thereby forming water-soluble

Treatment of the inner and outer surfaces of an orifice plate for ink-jet pens with self-assembled monolayers is disclosed. The outer surface of a gold-plated orifice plate is treated with self-assembled monolayers to control the wettability of the surface in order to reduce the accumulation of residual ink. The inner surface is treated with self-assembled monolayers to improve and control drop ejection. Various monolayers can also be used on the inner surface allowing for greater flexibility in controlling the steady state firing rate and uniformity of drops from a pen. In addition, treatment of orifice plate surfaces with self-assembled monolayers inhibits corrosion and contamination of the plate while presenting a uniform surface for the ink. The self-assembled monolayers for use in the present invention include thiols, disulfides, and sulfinates, having terminal functional groups which determine the wettability of the surface. A chemical bond is formed between the gold on the orifice plate and the thiol, disulfide, or sulfinate group of the monolayer compounds. The terminal functional group of the monolayer compound is therefore oriented away from the surface of the orifice plate and renders the surface either wetting or nonwetting depending on whether the terminal group has hydrophobic or hydrophilic characteristics.

The valve is operable with a bubble generator that provides a restricted flow of air bubbles into a reservoir of an ink-jet pen to relieve excessive back pressure in the pen. The valve includes housed operating liquid that closes the valve in the event that the pen is tipped out of an upright orientation. A hydrophobic air-porous vent is provided for permitting passage of air bubbles through the valve into the reservoir while prohibiting the flow of the operating liquid through the vent.

Method of valving and orientation sensitive valve including a liquid for

Inks are provided comprising (a) at least two dyes corresponding to the formula ##STR1## wherein W is COOH,

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Corvallis, OR, United States of America

David J Halko