Compositions – Inorganic luminescent compositions with organic...
Reexamination Certificate
2001-04-03
2004-06-15
Koslow, C. Melissa (Department: 1755)
Compositions
Inorganic luminescent compositions with organic...
C106S031320, C106S031640
Reexamination Certificate
active
06749773
ABSTRACT:
THE FIELD OF THE INVENTION
The present invention relates to phosphorescent ink compositions for use in ink-jet printers. More particularly, the present invention relates to an ink-jet ink composition which includes a phosphorescent material while retaining acceptable print performance in an ink-jet pen.
BACKGROUND OF THE INVENTION
Essentially all ink-jet inks are of two types: dye-based and pigment-based. Dye-based inks utilize a dye as a colorant that is dissolved in the ink vehicle. Therefore, most dye-based inks are non-particulate. Pigment-based inks, on the other hand, utilize a particulate colorant that is dispersed or suspended in an ink vehicle. Although there have been a number of advances made in dye-based inks, these inks still suffer from printing performance deficiencies with respect to various characteristics such as, water fastness, smear resistance, edge acuity, and lightfastness when used on various of print media. In contrast, because of their physical properties, pigment-based inks generally provide better images on many print media, because of their ability to achieve high optical density and sharp edge acuity with good water fastness, smear resistance and lightfastness. Additionally, pigment inks generally offer greater optical density, which provides richer, deeper color.
Glow-in-the-dark, or phosphorescent, articles are popular items in many consumer and industrial markets. Generally, when a phosphorescent material is exposed to a source of energy (e.g. light), it absorbs that energy, placing its atoms in an excited state. Over time, the energy level of the material drops back to its normal state. During this process, the atoms emit photons which can be seen as visible light, thereby creating a luminescence, or glow, that is still visible after the source of energy has been removed.
Many phosphorescent materials are unsuitable for use in an ink-jet ink composition because of the stringent ink-jet performance requirements. Problems may particularly arise with kogation, particulate size, print velocity, and interaction with other ink vehicle components.
SUMMARY OF THE INVENTION
It has been recognized that a phosphorescent ink composition which is suitable for use in ink-jet printers would be advantageous. Accordingly, the present invention provides an ink composition for use in an ink-jet printer comprising a mixture of an effective amount of a phosphorescent powder and a liquid ink vehicle.
The composition may optionally include a dispersing agent for maintaining disbursement of the phosphorescent material in the ink vehicle. In one embodiment, the phosphorescent powder may have average particle size of less than about 5 micrometers. In another embodiment, the phosphorescent powder may have an average particle size of less than about 1 micrometer.
One or more colorants may also be dispersed within the ink vehicle, in addition to the phosphorescent powder, such that the ink composition has the appearance of a conventional ink. The colorant may be, but is not limited to, a pigment or dye.
The ink vehicle used in the present composition is an aqueous or solvent based liquid that may additionally include one or more of the following ingredients: surfactants, defoamers, biocides, cosolvents, conductivity enhancing agents, anti-kogation agents, and drying agents. The ink vehicle can be present in amounts of between 60%-99.899% by weight of the composition.
The amount of phosphorescent powder may be from about 0.1% to about 20% by weight of the ink composition. Similarly, the amount of colorant may be from about 0.1% to about 20% by weight of the ink composition.
The present invention also provides a method of producing a phosphorescent ink-jet ink composition. In one aspect, such a method may include the step of mixing an effective amount of a phosphorescent powder with an ink vehicle.
The method of producing the phosphorescent ink composition may also include the step of adding a dispersing agent. In one embodiment, the average particle size of the phosphorescent powder may be less than about 5 micrometers. In another embodiment, the average particle size of the phosphorescent powder may be less than about 1 micrometer.
A colorant may be dispersed within the ink vehicle, such that the ink composition has the appearance of a conventional ink. This colorant may be, but is not limited to, a dye or a pigment.
The mixing of an effective amount of a phosphorescent powder with an ink vehicle may be accomplished by various processes known to those ordinarily skilled in the art. In one aspect, the mixing process may be milling.
There has thus been outlined, rather broadly, the more important features of the invention so that the detailed description thereof that follows may be better understood, and so that the present contribution to the art may be better appreciated. Other features of the present invention will become clearer from the following detailed description of the invention or may be learned by the practice of the invention.
DETAILED DESCRIPTION OF THE INVENTION
Before the present ink-jet ink composition and associated method of making an ink-jet ink composition are disclosed and described, it is to be understood that this invention is not limited to the particular process steps and materials disclosed herein, but is extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.
A. Definitions
In describing and claiming the present invention, the following terminology will be used.
The singular forms “a,”“an,” and, “the ” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a pigment” includes reference to one or more of such pigments, reference to “an ink” includes reference to one or more of such inks, and reference to “the color” includes reference to a mixture of one or more of such colors.
As used herein, “ink” refers to a composition for application to a print medium, which meets the accepted performance requirements known to those skilled in the art as being suitable for use in an ink-jet printer.
As used herein, “phosphorescent” refers to any substance containing electrons which temporarily enter an excited state upon exposure to a source of energy, such as light or electricity, and emit photons of visible light as they return to a normal state thereby creating a luminescence, or glow, that is still visible after the source of energy has been removed.
As used herein, “powder” refers to a substance in particulate form which has an average particle size that is suitable for use with ink-jet nozzle, according to well established parameters known to those skilled in the art.
As used herein, “colorant” refers to a dye or pigment for use with an ink vehicle to create an ink-jet ink.
As used herein, “conventional ink” refers to any ink that is not phosphorescent.
As used herein, “milling” refers to the process whereby ingredients of the ink composition, including phosphorescent material and an ink vehicle, are blended together such that the phosphorescent powder is dispersed and deaggregated to an average particle size that is suitable for use with ink-jet nozzle.
As used herein, “disbursement” refers to distributing or placing pigment particles, or a colorant, such as phosphorescent particles, within an ink vehicle.
As used herein, “dispersing agent” refers to any substance that prevents pigment particles or phosphorescent particles, from agglomerating or otherwise settling out of the ink vehicle.
As used herein, “effective amount” refers to the minimal amount of a substance or agent, which is sufficient to achieve a desired effect. For example, an effective amount of an “ink vehicle” is the minimum amount required in order to create ink, which will meet specified performance and characteristic standards. Additionally, the effective amount of a “phosphorescent powder” would be the minimum amount that pr
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