Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
2001-10-30
2004-11-16
Bell, Mark L. (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
Reexamination Certificate
active
06818048
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to ink-jet inks having improved image quality and reliability.
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. Specifically, a typical ink-jet printhead has an array of precisely formed nozzles located on a nozzle plate and attached to an ink-jet printhead substrate. The substrate incorporates an array of firing chambers that receive liquid ink (colorants dissolved or dispersed in a solvent) through fluid communication with one or more ink reservoirs. Each chamber has a thin-film resistor located opposite the nozzle so ink can collect between the firing resistor and the nozzle. Upon energizing a particular resistor element, a droplet of ink is expelled through the nozzle toward a print medium. 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, good dot size and dot gain, color-to-color bleed alleviation, less chia, acceptable coalescence, 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.
Ink-jet ink compositions have tended to become more and more complicated as demands for print quality have increased. In U.S. Pat. No. 5,788,754, an ink-jet ink composition is described that exhibits some desired properties of good ink-jet inks. For example, when printed on gelatin-coated media, excellent color-to-color bleed alleviation, good dot gain, good dot size, etc., are observed. However, the formulation is somewhat complicated having a large number of components. Thus, it is recognized that it would be desirable to formulate ink-jet inks that provide some of the same advantages of the inks of the prior art, while at the same time providing ink-jet ink formulations that are simpler to manufacture and less aggressive toward materials used in typical printheads.
SUMMARY OF THE INVENTION
The present invention provides an ink-jet ink for ink-jet printing, consisting of from 0.1% to 5% by weight of at least one dye; from 8% to 20% by weight of an organic solvent selected from the group consisting of 1,2-pentanediol, 1,2-hexanediol, and combinations thereof; from 0.1% to 5% by weight of an aliphatic alcohol or aliphatic alcohol mixture; from 0.1% to 1.5% by weight of at least one component independently selected from the group consisting of buffers, biocides, and metal chelators; and from 68.5% to 91.7% of water.
Alternatively, the present invention provides an ink-jet ink for ink-jet printing, comprising from 0.1% to 5% by weight of at least one dye; from 8% to 20% by weight of an organic solvent selected from the group consisting of 1,2-pentanediol, 1,2-hexanediol, and combinations thereof; from 0.1% to 5% by weight of an aliphatic alcohol or aliphatic alcohol mixture; and from 0.1% to 1.5% by weight of at least one component independently selected from the group consisting of buffers, biocides, and metal chelators, with the proviso that no surfactant is present in the ink-jet ink composition.
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 “a dye” includes reference to one or more of such dyes.
As used herein, “effective amount” refers to the minimal amount of a substance or agent, which is sufficient to achieve a desired result. For example, an effective amount of an “ink vehicle” is the minimum amount required in order to create an ink composition, while maintaining properties necessary for effective ink-jetting.
As used herein, “ink vehicle,” refers to the composition in which dyes are added to provide ink-jet ink compositions. 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. However, with the present invention, the ink-vehicle is defined by specific components in specific amounts, and excludes common additives such as surfactants.
An “ink-jet ink” or “ink composition” comprises an ink vehicle, a dye, and water.
In one embodiment, the present invention provides an ink-jet ink for ink-jet printing, consisting of from 0.1% to 5% by weight of at least one dye; from 8% to 20% by weight of an organic solvent selected from the group consisting of 1,2-pentanediol, 1,2-hexanediol, and combinations thereof; from 0.1% to 5% by weight of an aliphatic alcohol or aliphatic alcohol mixture; from 0.1% to 1.5% by weight of at least one component independently selected from the group consisting of buffers, biocides, and metal chelators; and from 68.5% to 91.7% of water. In another embodiment, the present invention provides an ink-jet ink for ink-jet printing, comprising from 0.1% to 5% by weight of at least one dye; from 8% to 20% by weight of an organic solvent selected from the group consisting of 1,2-pentanediol, 1,2-hexanediol, and combinations thereof; from 0.1% to 5% by weight of an aliphatic alcohol or aliphatic alcohol mixture; and from 0.1% to 1.5% by weight of at least one component independently selected from the group consisting of buffers, biocides, and metal chelators, with the proviso that no surfactant is present in the ink-jet ink composition. Notably absent from these ink-jet ink compositions is the presence of any traditional surface active agents such as anionic or nonionic surfactants.
Turning to a discussion of each component of the ink-jet ink compositions of the present invention, one comp
Chatterjee Amiya K.
Gardner John M.
Kelly-Rowley Anne M.
Prasad Keshava A.
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