Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2001-08-01
2002-11-19
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S101000
Reexamination Certificate
active
06481841
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an ink jet printing method using inks for ink jet printing that provide images with good lightfastness and improved color gamut.
BACKGROUND OF THE INVENTION
Ink jet printing is a non-impact method for producing images by the deposition of ink droplets in a pixel-by-pixel manner to an image-recording element in response to digital signals. There are various methods which may be utilized to control the deposition of ink droplets on the image-recording element to yield the desired image. In one process, known as continuous ink jet, a continuous stream of droplets is charged and deflected in an imagewise manner onto the surface of the image-recording element, while unimaged droplets are caught and returned to an ink sump. In another process, known as drop-on-demand ink jet, individual ink droplets are projected as needed onto the image-recording element to form the desired image. Common methods of controlling the projection of ink droplets in drop-on-demand printing include piezoelectric transducers and thermal bubble formation. Ink jet printers have found broad applications across markets ranging from industrial labeling to short run printing to desktop document and pictorial imaging.
The inks used in the various ink jet printers can be classified as either dye-based or pigment-based. A dye is a colorant which is dissolved in the carrier medium. A pigment is a colorant that is insoluble in the carrier medium, but is dispersed or suspended in the form of small particles, often stabilized against flocculation and settling by the use of dispersing agents. The carrier medium can be a liquid or a solid at room temperature in both cases. Commonly used carrier media include water, mixtures of water and organic co-solvents and high boiling organic solvents, such as hydrocarbons, esters, ketones, etc. For aqueous dye-based inks, the dyes needs to be sufficiently soluble in water to prepare a solution that is capable of producing adequate density on the receiving element and stable for extended periods of storage without precipitation. High quality ink jet printing with dye-based inks requires dyes which will provide both bright hue and good light fastness.
To generate full color prints via ink jet printing, ink sets comprising at least cyan, magenta and yellow inks are normally utilized. In addition a black ink is often added to enhance the printing of text and darker colors. The range of colors that can be produced with a given set of inks defines the color gamut of that ink set. For the production of high quality photorealistic images via ink jet printing, ink sets with a large color gamut are preferred. In addition, it is important that the ink sets produce images with good fastness, especially to light.
The choice of the colorants in ink jet systems is critical for both light fastness and color gamut. The color gamut of an ink set is controlled primarily by the spectral absorption characteristics of the component dyes. The primary dyes (e.g., cyan, magenta and yellow) should only absorb light of the required wavelengths (i.e., have relatively narrow absorption bands) and not overlap excessively with the dyes in the complementary inks. While there are many dyes with bright hues that are useful in ink jet printing, many have poor light fastness. Conversely many light stable dyes suitable for ink jet printing have broad absorption bands but give dull colors and limited color gamut.
WO 01/18123 relates to the use of magenta anthrapyridone dyes for ink jet inks. While there is a disclosure of other color ink jet inks used with this magenta dye, the color gamut of these combinations is not as large as one would like.
It is an object of this invention to provide an inkjet printing method using a set of inks capable of producing images via ink jet printing which have better color gamut than the ink sets of the prior art.
SUMMARY OF THE INVENTION
This and other objects are achieved in accordance with the present invention comprising an ink jet printing method, comprising the steps of:
A) providing an ink jet printer that is responsive to digital data signals;
B) loading the printer with an ink-receiving element comprising a support having thereon an ink-receiving layer;
C) loading the printer with an ink jet ink set for color printing comprising:
(a) a yellow ink comprising a carrier and a yellow azoaniline dye;
(b) a magenta ink comprising a carrier and a magenta anthrapyridone dye, and
(c) a cyan ink comprising a carrier and Direct Blue 307; and
D) printing on the ink-receiving layer using the ink jet ink in response to the digital data signals.
DETAILED DESCRIPTION OF THE INVENTION
Dyes referred to by dye numbers are numbers assigned by The Color Index.
Any yellow azoaniline dye may be used in the invention. In a preferred embodiment, the yellow azoaniline dye is Direct Yellow 132, Direct Yellow 107, Direct Yellow 86 or mixtures thereof.
Any magenta anthrapyridone dye may be used in the invention, as disclosed, for example, in U.S. Pat. No. 6,152,969; EP 1,063,268, EP 1,067,155; WO 00/23440; WO 01/18123; JP 2000-256587 and JP 2001-072884, the disclosures of which are hereby incorporated by reference. In a preferred embodiment, the magenta anthrapyridone dye is a sulfonic acid or sulfonate derivative of a compound represented by the general formula:
wherein:
R
1
represents hydrogen, or a substituted or unsubstituted alkoxycarbonyl, carboxyl, benzoyl, alkyl, aryl, hetaryl, alkoxy or phenoxy group,
R
2
represents hydrogen or a substituted or unsubstituted alkyl, alicyclic, aryl or hetaryl group;
R
3
represents hydrogen, carboxyl, or a substituted or unsubstituted alkyl, alicyclic, aryl, hetaryl, alkoxy or phenoxy group;
each X independently represents hydrogen, halogen, nitro, hydroxyl, carboxyl, or a substituted or unsubstituted alkyl, alicyclic, aryl, hetaryl, alkoxy, phenoxy, amino, amido or sulfonamido group; and
n represents 0, 1, 2 or 3.
In a preferred embodiment of the invention, R
1
in the above formula is benzoyl. In another preferred embodiment, R
2
is hydrogen. In yet another preferred embodiment, R
3
is a sulfonated phenoxy group. In yet still another preferred embodiment, n is 1 and X is a sulfonate group.
A preferred magenta dye which can be used in the invention is sold commercially as JPD Magenta EK-1 Liquid, from Nippon Kayaku Kabusbiki Kaisha as an approximately 10% solution in water.
As noted above, the cyan dye employed in the invention is Direct Blue 307. This dye is sold commercially as ProJet® Fast Cyan 2 Liquid from Avecia Corp.
In yet another preferred embodiment of the invention, a black ink can be added to the ink jet ink set to further increase the available color gamut. Black inks which can be used include a carrier and a black colorant such as Reactive Black 31, Direct Black 19, Direct Black 168, Solubilized Sulfur Black 1 (Duasyn® Black SU-SF) or a black pigment.
In general, the inks employed in this invention comprise the above dyes at concentration of from about 0.1 to about 10%, preferably from about 0.4 to about 5% by weight of the inkjet ink composition.
In yet still another preferred embodiment of the invention, additional inks of a “light” cyan ink or “light” magenta ink, which is the same cyan and magenta dyes in (c) and (b), except that they are employed at a concentration of about 5% to about 50% of the amount of the cyan and magenta dyes.
For the purpose of this invention, color gamut is specified in the CIELAB metric. Color gamut is defined as the sum of the a*-b* areas of 9 L* slices (L*=10, 20, 30, 40, 50, 60, 70, 80 and 90) obtained when a given ink set is used. Color gamut may be obtained through measurement and estimation from a large sample of color patches which is very tedious and time-consuming, or calculated from the measured absorption characteristics of the individual dyes using the techniques described in J. Photographic Science, 38, 163 (1990).
The absorption characteristics of a given image dye will vary to some extent with a change in ink laydown or printed density. This i
Blease James W.
Evans Steven
Klingman Karen J.
Barlow John
Cole Harold E.
Shah Manish
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