Stock material or miscellaneous articles – Ink jet stock for printing – Particles present in ink receptive layer
Reexamination Certificate
2002-04-10
2004-08-31
Shewareged, B. (Department: 1774)
Stock material or miscellaneous articles
Ink jet stock for printing
Particles present in ink receptive layer
C428S032210
Reexamination Certificate
active
06783819
ABSTRACT:
FIELD OF THE INVENTION
The present invention is drawn to crown compound modified silica coatings for ink-jet media. The present invention is also drawn to ink-jet ink and coated media systems that provide good image permanence over time.
BACKGROUND OF THE INVENTION
In recent years, computer printer technology has evolved to a point where high resolution images can be transferred on to various types of media, including paper. One particular type of printing involves the placement of small drops of a fluid ink onto media surfaces in response to a digital signal. Typically, the fluid ink is placed or jetted onto the surface without physical contact between the printing device and the surface. Within this general technique, the specific method that the ink-jet ink is deposited onto the printing surface varies from system to system, and can include continuous ink deposit or drop-on-demand ink deposit.
With regard to continuous printing systems, inks used are typically based on solvents such as methyl ethyl ketone and ethanol. Essentially, continuous printing systems function as a stream of ink droplets that are ejected and directed by a printer nozzle. The ink droplets are directed additionally with the assistance of an electrostatic charging device in close proximity to the nozzle. If the ink is not used on the desired printing surface, the ink is recycled for later use. With regard to drop-on-demand printing systems, the ink-jet inks are typically based upon water and glycols. Essentially, with these systems, ink droplets are propelled from a nozzle by heat or by a pressure wave such that all of the ink droplets ejected are used to form the printed image.
There are several reasons that make ink-jet printing 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 cost to consumers. However, though there have been great improvements in ink-jet printing, accompanying these improvements are increased consumer demands such as higher speeds, higher resolution, full color image formation, increased image durability, etc. As new ink-jet inks are developed, there have been several traditional characteristics to consider when evaluating the ink in conjunction with printing media. 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 to address one of the above attributes prevents another being met. Thus, most commercial inks for use in ink-jet printers represent a compromise, in an attempt to achieve adequate performance in all of the above listed attributes.
Ink-jet inks are either dye- or pigment-based. Dye-based ink-jet inks generally, but not always, use water-soluble colorants. As a result, such dye-based inks are usually not always water fast. Prints made from these inks tend to undergo color change over time, or fading, when exposed to ambient light and air. The media surface can play a key role in the fade properties and wet fastness of an image in that for a given ink, the degree of fade and wet fastness can be highly dependent on the chemistry of the media surface. Therefore, for optimum performance, many ink-jet inks often require that an appropriate media be selected in accordance with the application, thus, reducing the choice of media. In the case of pigmented inks, it is the dispersed colorant particles that produce color. Often the line quality of prints produced by pigment-based inks is superior to that of dye-based inks. When a printed image is made with pigmented inks, solid colorant particles adhere to the surface of the substrate. Once the ink vehicle evaporates, the particles will generally not go back into solution, and are therefore more water fast. In addition, pigmented inks are often much more fade resistant than dye-based inks. Though pigmented inks, in some areas, exhibit superior performance, dyes in general produce inherently more color saturated and more reliable inks. Thus, dye-based inks have been more often used in applications where fade resistance is not primarily important.
In order for the ink-jet industry to effectively compete with silver halide photography, it is important that ink-jet prints must improve their image fade resistance. In other words, enhanced permanence of images has become important to the long-term success of photo-quality ink-jet ink technologies. According to accelerated tests and “industry standard” failure criteria, photographs have typically been known to last about 13 to 22 years under fluorescent light exposure. There are now even systems with published values of 19 to 30 years. The best dye based ink-jet printers produce prints that last for much less time under similar conditions.
Two broad categories of photographic ink-jet media are currently available: polymer and porous coating based media. It is the polymer based type that produce the best known images, e.g. longest lasting, mentioned above. However, this category of media is generally inferior in dry time and wet fastness relative to porous coating-based media. On the other hand, image fade resistance and humid fastness of the porous coating-based media is generally lower than that of its polymer-based media counterpart. Therefore, there is a great desire to improve the image permanence of ink jet ink images on porous coating based media.
SUMMARY OF THE INVENTION
In accordance with the compositions and coated substrates of the present invention, the use of a chemically modified silica coating can provide certain advantages related to image permanence over the prior art. For example, the use of a crown compound chemically attached to silica as a coating on paper or other substrate can provide altered image permanence characteristics. More specifically, as crown compounds are known to interact with certain ions, the presence of the crown compounds can alter the way ion-containing dyes interact with media coated as described herein.
With this in mind, a coated substrate for ink-jet ink printing can comprise a substrate having a porous coating coated thereon. In one embodiment, the porous coating can be silica covalently modified by a crown compound through a reactive group (and optionally, a spacer group). The crown compound can further be substantially homogenously distributed on the silica. In one embodiment, the crown compound can be a crown ether.
In another embodiment, a system for producing permanent ink-jet ink images can comprise a substrate, having coated thereon a porous coating, said porous coating comprising silica covalently attached to a crown compound through a reactive group; and an ink-jet ink comprising a composition configured for chemically interacting with the crown compound upon printing the ink-jet ink onto the porous coating.
Crown compound modified silica gel can be used to bind cationic dyes directly, or to bind anionic dyes indirectly, such as by interacting with the counter ion associated with the dye. An advantage that can be realized by an embodiment of the present invention is that the orientation of a dye relative to crown compound modified silica media can be different than that obtained with standard silica modified media. This change in the surface orientation can improve the stability of the dye, and improve water fastness and humid fastness properties. For example, the use of crown ether modified silica media can enhance the specificity of the surface absorption of dyes and other charged species due to the presence of a crown
Deardurff Larrie A.
Shields James P.
Hewlett--Packard Development Company, L.P.
Shewareged B.
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