Ink jet printing process

Details Ink jet printing process Ink jet printing process

2002-03-08

2003-12-30

Klemanski, Helene (Department: 1755)

Compositions: coating or plastic

Coating or plastic compositions

Marking

C106S031780, C347S100000

Reexamination Certificate

active

06669767

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to an ink jet printing method employing inks that provide images with high print density 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 that 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. In addition to the light absorption characteristics of the dyes, the maximum print density achieved from the ink is another important factor to provide a high color gamut. The higher the print density the greater the color gamut.
It is well known that ink components of the ink composition other than the dye can affect print density. The non-dye components can control the depth of dye penetration into the receiving media and or the lateral spread of the dye on the receiving media thus influencing the print density.
There are many ink components or additives that are used commercially or have been described in patents. In particular, pylTolidin-2-one and specific derivatives of pyrrolidin-2-one have been frequently used to influence printed ink performance.
U.S. Pat. No. 5,302,197 describes an ink composition that comprises a polyol/alkylene oxide condensate in combination with specific cyclic amide derivatives. Examples of the cyclic amide derivative include pyrrolidin-2-one and 1-(2-hydroxyethyl)-2-pyrrolidinone. U.S. Pat. No. 5.876,491 describes an ink composition comprising at least one specific cyclic ester or amide in combination with at least one polyhydroxy compound with at least four hydroxyl groups. An example of the cyclic amide is pyrrolidin-2-one. U.S. Pat. No. 5,300,143 describes an ink composition which comprises certain sulfone compounds in combination with specific cyclic amines an example of which is pyrrolidin-2-one. Japanese Patent Application JP 75-59680 describes ink compositions which comprise specific derivatives of 2-pyrrolidinone which includes 1-(2-hydroxyethyl)-2-pyrrolidinone.
However the print density that can be achieved in ink compositions comprising pyrrolidin-2-one, or common derivatives thereof such as 1-methyl-pyrrolidin-2-one or 1-(2-hydroxyethyl)-pyrrolidin-2-one and the like are not as high as one would desire.
It is an object of this invention to provide an ink printing method using inks that are capable of producing high print densities via ink jet printing than the inks of the prior art.
SUMMARY OF THE INVENTION
This and other objects are achieved in accordance with the present invention which relates to an ink jet printing method comprising the steps of
A) providing an ink jet printer that is responsive to digital data signals,
B) loading said printer with an ink jet recording element comprising a support having thereon an image-receiving layer;
C) loading said printer with an ink jet ink comprising water, a colorant and a water-soluble ester or amide of a pyrrolidin-2-one carboxylic acid; which may be de scribed by the following Structure I:
wherein R
1
represents a branched or unbranched alkyl group of 1 to about 8 carbon atoms;
R
2
represents H, an optionally substituted branched or unbranched alkyl group of 1 to about 4 carbon atoms or a poly(oxyalkylene) group of 3 to about 12 atoms; ieach R
3
independently represents H or an optionally substituted branched or unbranched alkyl group of 1 to about 8 carbon atoms, hydroxy, amino, halogen, cyano, alkoxy, alkoxycarbonyl, carboxy, ureido, carbamoyl, alkylamido or alkylsulfonamido;
X represents O or NR
4
where R
4
represents H or a branched or unbranched alkyl group of 1 to about 8 carbon atoms;
with the proviso that the water solubility of said ester or amide of a pyrrolidin-2-one carboxylic acid is greater than about 0.05% and
D) printing on said image-receiving layer using said ink jet ink composition in response to said digital data signals.
The ink jet printing method of the invention provides high print densities than methods of the prior art.
DETAILED DESCRIPTION OF THE INVENTION
Both dyes and pigments may be used as the colorant described in the summary of the invention.
Any cyan dye or cyan pigment or mixture thereof may be used in the cyan ink. In a preferred embodiment the cyan dye may be a water-soluble copper or nickel phthalocyanine dye such as Direct Blue 86, Direct Blue 199, or Direct Blue 307. In another preferred embodiment, the pigment is Pigment Blue 15:3 or a derivative of aluminum phthalocyanine.
Any magenta dye or magenta pigment or mixtures thereof may be used in the magenta ink. In a preferred embodiment the magenta dye is a water-soluble azo dye such as Direct Violet 107 or Reactive Red 31, a water soluble transition metal complex of an 8-heterocyclylazo-5-hydroxy quinoline such as are described in U.S. Pat. No. 6,001,161, or an anthrapyridone dye such as those described in World Patent Application 01-18123. In another preferred embodiment, the magenta pigment is Pigment Red 122.
Any yellow dye or yellow pigment or mixtures thereof may be used in the yellow ink. In a preferred embodiment the yellow dye is a water-soluble azo dye such as Direct Yellow 86, Direct Yellow 107 or Direct Yellow 132. In another preferred embodiment, the yellow pigment is Pigment Yellow 155 or Pigment Yellow 74.
Any black dye

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