Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
1999-08-17
2001-07-17
Klemanski, Helene (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031530, C106S031560, C106S031590, C106S031430, C106S031580
Reexamination Certificate
active
06261350
ABSTRACT:
TECHNICAL FIELD
The present invention is directed to ink-jet inks, and, more particularly, to ink-jet ink compositions for increasing chroma and edge acuity, as well as improving color-to-color bleed, waterfastness, optical density of composite black, and decreasing strikethrough.
BACKGROUND ART
There is a considerable demand in a better image quality of ink-jet. The poor edge acuity, color-to-color bleed, and low chroma, as well as low waterfastness and smudge seem to be the main drawbacks of ink-jet, and this invention addresses these issues.
It is well-known that inks can be dye- or pigment-based. In dye-based inks, the colorant is present in a molecular-dispersed state. In pigment-based inks, the solid colorant is suspended in the ink vehicle. Both dye- and pigment-based inks have their advantages and drawbacks. Thus, dye-based inks provide vivid saturated colors. Because vivid colors can be achieved with a relatively low ink volume, the drying is relatively short, and the printouts show a low smudge, cockle and curl. On the other hand, pigmented inks are characterized by duller colors, but have a better edge acuity, strikethrough, and waterfastness.
Several techniques has been tried in order to improve the color vividness, edge acuity, waterfastness and bleed. One such technique is underprinting, which helps to stratify the colorant to the surface of the paper, reduces wicking, and improves color performance. Underprinting is defined as applying a transparent fluid on substrate prior the ink deposition. There are several patents addressing the technique of underprinting for better waterfastness and bleed control; see, e.g., U.S. Pat. No. 5,624,484, “Liquid Composition and Ink Set, and Image-Forming Process and Apparatus Using the Same”, issued to K. Takahashi et al on Apr. 29, 1997, and U.S. Pat. No. 5,640,187, “Ink Jet Recording Method and Ink Jet Recording Apparatus Therefor”, issued to A. Kashiwazaki et al on Jun. 17, 1997, both assigned to Canon; U.S. Pat. No. 5,723,179, “Method and Composition for Obtaining Waterfast Images From Ink Jet Inks”, issued to R. W. Wong et al on Mar. 3, 1998, and assigned to Xerox Corp.; and U.S. Pat. No. 5,746,818, “Pigment Ink Composition Capable of Forming Image Having No Significant Bleeding or Feathering”, issued to M. Yatake on May 5, 1998, and assigned to Seiko Epson. The underlying idea in underprinting is to bind the dyes with oppositely charged species. For example, anionic dyes can be bound by a cationic polymer, and cationic dyes can be bound by an anionic polymer. The clear underprinting fluid will be referred below as a fixing fluid, or fixer.
It is known that underprinting can increase the chroma (or, for black, optical density) of pigmented dispersions, such as carbon black-based inks. For example, black inks in Hewlett-Packard's DeskJet 890C printer are underprinted with a composite black, resulting in a considerable boost in the optical density. Also, the edge acuity of underprinted pigmented inks is normally improved.
However, for dye-based inks, the underprinting techniques known in art only marginally increase, or, most often, decrease chroma. Thus, as can be judged from the above-mentioned U.S. Pat. No. 5,723,179, underprinting decreased the optical density of the images (although underprinting made them waterfast). Similarly, in the commercial Canon BJC-700 printer, underprinting improves the edge acuity and bleed, but decreases the color vividness (see Examples, below). The decrease in chroma comes, among other things, from the plain increase in the volume of liquid poured on the paper. As a result of the higher liquid volume, the complex of the dye with the underprinting fixer penetrates deeper into the paper and the chroma is somewhat lost. As for the edge acuity of dye-based systems, it often improves, but at the expense of a poorer area fill uniformity. Underprinted dye images often show “mottle” and “muddy color”, supposedly because of the low dot gain and dye aggregation.
Another approach to improving the color performance, waterfastness, and edge acuity is the incorporation of the color dyes into surfactant aggregates in solution. Thus, in U.S. Pat. No. 5,226,957 entitled “Solubilization of Water-Insoluble Dyes via Microemulsions for Bleedless, Non-Threading, High Print Quality Inks for Thermal Inkjet Printers”, issued to P. Wickramanayake on Jul. 13, 1993, and assigned to the same assignee as the present application, it is suggested to incorporate an oil-soluble dye into a microemulsion, which contains solvents, surfactants, co-surfactants, and water. In another patent issued to P. Wickramanayake, U.S. Pat. No. 5,565,022, “Fast-Drying, Bleed-Free Ink-Jet Ink Compositions”, issued on Oct. 15, 1996, and assigned to the same assignee as the present application, it is suggested to incorporate a dye into a mixture of an organic solvent, surfactant, and water, so that the dye and water-insoluble solvent are solubilized by the surfactant. In U.S. Pat. No. 5,643,357, “Liquid Crystalline Ink Compositions”, issued to M. P. Brenton et al on Jul. 1, 1997, and assigned to Xerox Corp., an ink composition is suggested that contains a surfactant, and oil- or alcohol-soluble dye, and water. The formulation undergoes a phase transition upon heating from a microemulsion phase to a lamellar phase, which helps to stratify the inks to the surface of the paper, when the printing substrate is heated. U.S. Pat. No. 5,492,559, “Liquid Crystalline Microemulsion Ink Compositions”, issued to J. F. Oliver et al on Feb. 20, 1996, and assigned to Xerox Corp., describes an ink formulation containing an aqueous phase, oil phase, and surfactant, and an oil-soluble dye, such that the system undergoes a microemulsion—liquid crystalline state transition with decreasing temperature. The use of another type of surfactant aggregates, vesicles, in ink-jet was first suggested in U.S. Pat. No. 4,783,220, “Vesicle Ink Compositions”, issued to R. C. Gamble et al on Nov. 8, 1988, and co-assigned to Xerox and Vestar. The patentees disclose vesicle ink compositions, where the dyes are dissolved in the surfactant bilayer. This is deemed to improve waterfastness of the images. The patentees disclose different types of vesicle-forming surfactants, including phospholipids, dioctadecylammonium bromide, diacylglycerides and their ethoxylated derivatives.
In the U.S. Pat. No. 5,626,654, “Ink Compositions Containing Liposomes”, issued to M. P. Breton et al on May 6, 1997, and assigned to Xerox, the patentees disclose vesicles in ink, wherein the vesicles are at least partially polymerized. Further, the patentees disclose the use of oppositely charged vesicles and dyes, or covalently bound vesicle-forming lipids and dyes. The benefit of this is claimed to be “the excellent edge quality and optical density”.
U.S. Pat. No. 5,633,109, “Ink Compositions with Liposomes Containing Photochromic Compounds”, issued to C. A. Jennings on May 27, 1997, and assigned to Xerox Corporation, discloses an ink composition which comprises an aqueous liquid vehicle, a photochromic material, and a vesicle-forming lipid. The ink compositions are photochromic; that is, the inks have two different states, each having a different absorption spectrum, and can be switched from one state to the other by suitable exposure of the printed ink to radiation of the appropriate wavelength.
U.S. Pat. No. 5,788,749, “Pigmented Ink Compositions Containing Liposomes”, issued to M. P. Breton et al on Aug. 4, 1998, and assigned to Xerox, addresses the use of liposomes for pigmented inks. The advantages claimed are “excellent edge raggedness and excellent optical densities”.
In U.S. Pat. No. 5,772,743, “Ink Compositions for Thermal Ink-jet Printing”, issued to K. P. Gundlach et al on Jun. 30, 1998, and assigned to Xerox, the patentees disclose the use of specific fluorinated vesicle-forming surfactants.
A recent patent issued to M. Gore, U.S. Patent 5,911,816, “Liposomal Ink Compositions with Water-Insoluble Dyes and Pigments”, issued on Jun. 15, 1999, and assigned to the same assignee as the present
Faison Veronica F.
Hewlett--Packard Company
Klemanski Helene
LandOfFree
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