Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2001-10-30
2003-11-25
Meier, Stephen D. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S096000, C106S031130
Reexamination Certificate
active
06652085
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to ink-jet inks, systems, and methods for improving the waterfastness of printed images.
BACKGROUND OF THE INVENTION
Thermal ink jet printers, provide an effective means of propelling ink jet inks onto various media including paper. These printers can accomplish this by using resistive heater elements for heating the ink to a boil, and propelling the ink through an overlying orifice plate. Such printers, as typified by the Hewlett-Packard DeskJet™ and DesignJet™ printers, are desirable for use for several reasons. For example, thermal ink jet printers have a relatively fast throughput while being relatively inexpensive to run. Additionally, these printers are relatively easy to use, and the ink is easily replaced.
There are several reasons that ink-jet printing has become a popular way of recording images on various media surfaces, particularly paper. Some of these reasons include low printer noise, capability of high speed recording, and multi-color recording. Additionally, these advantages can be obtained at a relatively low price to consumers. However, though there has been great improvement in ink-jet printing, accompanying this improvement are increased demands by consumers in this area, e.g., higher speeds, higher resolution, full color image formation, increased stability, new applications, etc. As new ink-jet inks are developed, there are several traditional characteristics to consider when evaluating the ink in conjunction with a printing surface or substrate. Such characteristics include edge acuity and optical density of the image on the surface, dry time of the ink on the substrate, adhesion to the substrate, lack of deviation of ink droplets, presence of all dots, resistance of the ink after drying to water and other solvents, long term storage stability, and long term reliability without corrosion or nozzle clogging. Though the above list of characteristics provides a worthy goal to achieve, there are difficulties associated with satisfying all of the above characteristics. Often, the inclusion of an ink component meant to satisfy one of the above characteristics can prevent another characteristic from being met. Thus, most commercial inks for use in ink-jet printers represent a compromise in an attempt to achieve at least an adequate response in meeting all of the above listed requirements.
Dye-based ink-jet inks have been a dominant technology in the ink-jet ink arena. However, as many dyes are water-soluble, images printed using many of such dye-based ink jet inks are not as waterfast as may be desirable. In the prior art, the waterfastness of an anionic dye-based ink-jet ink printed on media has been shown to be enhanced by overprinting or underprinting the printed image with a cationic polymer, such as from a separate pen. Thus, when the cationic polymer and the anionic dye contact one another on a substrate, a reaction between the dye and the polymer creates an image with improved waterfastness. However, despite this improvement, there is still a need in this area to provide additional ink-jet inks, systems, and methods for improving the waterfastness of ink-jet ink images.
SUMMARY OF THE INVENTION
It has now been discovered that the use of three key components can provide the means for improving waterfastness of printed images. Essentially, by printing images using an anionic dye, a polyamine compound, and an acidic fixer, images that exhibit desired waterfastness can be obtained. More particularly, in one embodiment, the anionic dye and the polyamine compound can be part of a single ink-jet ink formulation, as ink-jet inks having both of these components can remain stable at relatively high pH levels and have acceptable viscosity. For example, in some embodiments, a pH from about 9 to 11 and a viscosity from about 1 to 5 cp can be achieved with acceptable stability. Thus, a first pen formulation can comprise an anionic dye, a polyamine compound, and an ink vehicle. As part of a second pen formulation, an acidic fixer composition can comprise an ink vehicle and an acid. Thus, when the composition of the first pen and the composition of the second pen are both printed onto a substrate such that the first pen composition contacts the second pen composition, protonation of the polyamine can occur resulting in ink precipitation or fixation. This system results in improved waterfastness.
In a first aspect of the present invention, a system for printing images with improved waterfastness is disclosed. The system can comprise a first pen containing an ink composition and a second pen containing an acidic fixer composition. The ink composition preferably comprises effective amounts of an anionic dye, a polyamine, and an ink vehicle. The acidic fixer composition comprises an effective amount of an acid and an ink-vehicle. With this system, the first pen and the second pen are configured to print the ink composition and the acidic fixer composition, respectively, onto a substrate such that the ink composition and the acidic fixer composition are in contact on the substrate. The acid of the acidic fixer composition acts to protonate the polyamine of the ink composition on the substrate. In one embodiment, the acid concentration and volume of the acidic fixer composition utilized can be sufficient to preferentially protonate the polyamine molecules on the substrate, and not protonate the anionic dye molecules.
In an alternative aspect of the present invention, a method of printing a waterfast image using an ink-jet printer is disclosed. This method comprises the steps of jetting an ink composition onto a substrate, wherein the ink composition comprises effective amounts of an ink vehicle, an anionic dye, and a polyamine; and jetting an acidic fixer composition onto the substrate, wherein the acidic fixer composition comprises an effective amount of an acid and an ink-vehicle. Thus, the acidic fixer composition can contact the ink composition on the substrate, providing the image having improved waterfastness.
In yet another aspect of the present invention, an ink-jet ink created image is disclosed comprising a substrate, having printed thereon, effective amounts of ink vehicle, an anionic dye, a polyamine, and an acid. The anionic dye provides color to the image, and the acid protonates the polyamine resulting in increased waterfastness.
DETAILED DESCRIPTION OF THE INVENTION
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the exemplary embodiments, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications of the inventive features illustrated herein, and any additional applications of the principles of the invention as illustrated herein, which would occur to one skilled in the relevant art and having possession of this disclosure, are to be considered within the scope of the invention.
The singular forms “a,” “an,” and, “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “an ink” includes reference to one or more of such inks.
As used herein, “effective amount” refers to the minimal amount of a substance or agent, which is sufficient to achieve a desire effect. For example, an effective amount of an “ink vehicle” is the minimum amount required in order to create an ink composition or acidic fixer composition, while maintaining properties necessary for effective ink-jetting.
As used herein, “ink vehicle,” refers to the vehicle in which the anionic dyes, polyamines, and/or acids are placed to form an ink. Ink vehicles are well known in the art, and a wide variety of ink vehicles may be used with the systems, methods, and ink composition of the present invention. Such ink vehicles may include a mixture of a variety of different agents, including without limitation, surfactants, solvents, co-solvents, buffers, biocides, viscosity modifiers, sur
Hewlett--Packard Development Company, L.P.
Meier Stephen D.
Shah Manish
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