Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Inks are provided comprising (a) at least two dyes corresponding to the formula ##STR1## wherein W is COOH,X is H, or COOH,Y is H, COOH, or SO.sub.3 H,Z is H, COOH, or SO.sub.3 H, andR is H, CH.sub.2 COOH, or CH.sub.2 CH.sub.2 COOH;with the proviso that there are at least two COOH groups and that the number of COOH groups is equal to or greater than the number of SO.sub.3 H groups, and (b) a solvent which may be water or a mixture of water and a water-soluble organic solvent provide excellent waterfast prints on paper. The inks preferably have a pH from about 7 to about 9.5. Also preferably, a phosphate is added to reduce kogation and a metal chelating agent is added to further reduce nozzle clogging.

Abstract: 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.

Abstract: 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.