# Patent

## Title
Cyan inkjet ink having improved print quality with porous photo media

## Abstract

The present invention relates to cyan dye-based inkjet inks having improved permanence when jetted onto porous photo media. The inkjet ink includes a copper phthalocyanine dye having sulfonylamine groups, at least three co-solvents having about 18% to about 24% of the composition of the ink by weight, a polymeric dye dispersant having about 0.5% to about 2.0% of the composition of the ink by weight, a penetrant, at least one wetting agent, and water.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
Not applicable.
MICROFICHE APPENDIX
Not applicable.
GOVERNMENT RIGHTS IN PATENT
Not applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to inkjet inks, and, more particularly, to cyan inkjet inks having improved print quality with porous media.
2. Description of the Related Art
Thermal inkjet printing, to which this invention relates, is a commonly practiced form of printing. Thermal inkjet printing involves intense heating of an aqueous ink in a small amount in contact with a heating element so the ink is vaporized. The vaporized ink, including solids in the ink, is then expelled through a nozzle and subsequently jetted to an intended substrate, such as, for example, paper.
The composition of an inkjet ink is traditionally comprised of deionized water, a water-soluble organic solvent, and a colorant. The colorant may be a soluble dye or insoluble pigment. Traditionally, pigment based inks may have some disadvantages as compared to dye based inks as traditional pigment based inks tend to have slightly higher solids and viscosity which may pose to be more difficult for jetting through relatively smaller nozzle printhead designs. For example, due to the insolubility of pigments in water, polymeric dispersants and/or surfactants are typically added to improve the dispersibility of the pigment. The addition of a polymeric dispersant can increase the viscosity of an ink, and a viscous ink may be more difficult to jet in a printhead.
Inkjet printers may use dye-based color inks or pigment-based color inks. Dye-based color inks tend to be more saturated and more robust to inkjet pens. In contrast, pigment-based color inks tend to be more permanent and of the quality typically recognized with laser-like printers.
There is a very limited choice of pigments for use with pigment-based color inks, whereas the number of dyes to be used with dye-based color inks continuously grows.
A current challenge in the industry is to develop faster drying dye-based inks for use with porous photo media, rather than for use with traditional swellable polymer photo media. However, porous photo media are comprised of inorganic materials that, in conjunction with ozone gasses and light, interact with dyes such that the dyes fade and degrade.
What is needed in the art is a cyan dye-based inkjet ink that may be used with porous photo media with substantially minimal fading and degradation of the cyan dye.
SUMMARY OF THE INVENTION
Exemplary embodiments of the present invention provide an inkjet ink comprised of a copper phthalocyanine dye having sulfonylamine groups, at least three co-solvents comprising about 18% to about 24% of the composition of the ink by weight, a penetrant, at least one wetting agent, and water.
Various other exemplary embodiments of the present invention include a method of printing using an inkjet ink. The method is comprised of the steps of positioning a porous photo medium substantially adjacent to a printer having a print head retaining an inkjet ink, wherein the inkjet ink is comprised of a copper phthalocyanine dye having sulfonylamine groups, at least three co-solvents comprising about 18% to about 24% of the composition of the ink by weight, a penetrant, at least one wetting agent, and water. The inkjet ink is then jetting from the print head onto the porous photo medium.


DETAILED DESCRIPTION OF THE INVENTION
Porous photo media, as opposed to traditional swellable polymer photo media, tends to allow for faster drying. As such, it is desired to develop dye-based inks that allow greater permanence with the porous photo media. However, as noted above, porous photo media are comprised of inorganic materials that, in conjunction with ozone gasses and light, interact with dyes such that the dyes fade and degrade.
Permanence, as used herein, refers in part to the ability of a dye to resist the interactions with light, ozone, temperature, and humidity that cause fading and degradation of the dye associated with the media.
It has been found that a color inkjet ink comprised of a copper phthalocyanine dye having sulfonylamine groups, three co-solvents, a penetrant, and a wetting agent has an increased permanence when used with porous photo media.
In exemplary embodiments, the inkjet ink may further be comprised of a biocide, such as, for example, PROXEL® GXL (available from Arch Chemicals, Inc. of Norwalk, Conn.).
In the various exemplary embodiments of the present invention, a copper phthalocyanine dye having sulfonylamine groups comprises about 3.0% to about 6.0% of the composition of the ink by weight. The sulfonylamine groups assist in enabling the cyan dye to be more stable to interactions with ozone.
The a copper phthalocyanine dye having sulfonylamine groups may be selected from, for example, Fuji PROJET® Cyan GLF (available from Fujifilm Imaging Colorants Limited) or Nippon Cyan JPD LM-1 Liquid (available from Nippon Kayaku Co, Ltd. of Tokyo, Japan).
The at least three co-solvents are selected from the group consisting of 1,3-propanediol; 1,2-alkanediol; 1,5-pentanediol; triethylene glycol; and dipropylene glycol.
In exemplary embodiments, at least two of the three co-solvents are alkanediols and the third co-solvent is a glycol.
The penetrant is preferably about 1.0% to about 3.5% of the composition of the ink by weight. A exemplary penetrant is 1,2-hexanediol.
It is preferred that the wetting agent be of about 0.5% to about 1.5% by weight of the inkjet ink. In a more preferred embodiment, the non-ionic silicone surfactant is about 0.75% by weight of the inkjet ink.
Exemplary wetting agents include polyoxyethylene dimethyl siloxanes, ZONYL® fluorosurfactants, and combinations thereof. A commercially available wetting agent is, for example, SILWET® L-7600 (polyalkylene oxide grafted polydimethylsiloxane from Momentive Performance).
The polymeric dispersant is preferably about 0.5% to about 2.0% by weight of the inkjet ink, and assists in stabilizing the carbon black pigment and buffering the pH of the inkjet ink.
An optional polymeric dispersant can be added to assist in stabilizing the compatibility with a carbon black pigment ink in a Cyan-Magenta-Yellow-Black (CMYK) inset. When CMYK inks are printed in substantially close proximity to each other, each ink needs to be compatible and not destabilize adjacent inks. In the present exemplary embodiments, the CMY dye inks may be printed along with a black pigmented ink without destabilizing any of the CMY dye inks or the black pigmented ink due to the presence of the polymeric dispersant in the CMY dye inks.
In exemplary embodiments of the present invention, the polymeric dispersant may be selected from dispersants set forth in, for example, any of U.S. Pat. Nos. 5,719,204; 5,994,427; 6,063,834; 6,267,807; 6,896,724; and 6,984,701, all incorporated by reference.
One or more buffers may also be included in the inkjet ink composition. Exemplary embodiments of the one or more buffers include triethanolamine (TEA), N,N-bis(2-hydroxyethyl)tuarine or N,N-bis(2-hydroxyethyl)-2-aminoethane sulfonic acid (BES), or combinations thereof.
Several exemplary inkjet inks according to the present invention were formulated and evaluated using a standard printhead and porous photo paper in the form of Perfectfinish Glossy Photo Paper (available from Lexmark International, Inc. of Lexington, Ky.). The same printing was conducted using a commercially available cyan dye-based inkjet ink. Each ink was evaluated for its permanence against the effects of ozone and xenon light.
In Table 1, the permanence of each dye-based ink on porous photo media is compared. The numbers shown represents the number of years of permanence according to the criteria of 40% density loss and assuming the exposure level of 78 ppm-hr/yr for ozone and 1.1 Mlux-hr/yr for light fade.







TABLE 1







Permanence of Dye with Porous Photo Media









Years of Permanence after Exposure to:










Ozone
Xenon LF


Ink
(1 ppm or 5 ppm)
(80 klux)





Cyan Inkjet Ink
4
40


Commercially Available Cyan-
1
26


dye Based Inkjet Ink









As clearly illustrated above, the present cyan-dye based inkjet ink shows an improvement in permanence when exposed to ozone four times greater than that of commercially available cyan-dye inkjet inks undergoing the same exposure. When exposed to xenon light, the cyan inkjet ink of the present invention showed a permanence one and a half times greater than that of a commercially available cyan-dye inkjet ink.
While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

## Claims

1. An inkjet ink comprising:
a copper phthalocyanine dye having sulfonylamine groups;
at least three co-solvents comprising about 18% to about 24% of the composition of the ink by weight, the at least three co-solvents including 1,3-propanediol, 1,2-alkanediol, and triethylene glycol;
a polymeric dye dispersant comprising about 0.5% to about 2.0% of the composition of the ink by weight;
a penetrant;
at least one wetting agent; and
water.

2. The inkjet ink according to claim 1, wherein the copper phthalocyanine dye having sulfonylamine groups comprise about 3.0% to about 6.0% of the composition of the ink by weight.

3. The inkjet ink according to claim 1, wherein the penetrant comprises about 1.0% to about 3.5% of the composition of the ink by weight.

4. The inkjet ink according to claim 1, wherein the at least three co-solvents further includes 1,5-pentanediol; and dipropylene glycol.

5. The inkjet ink according to claim 1, wherein the wetting agent is about 0.5% to about 1.5% of the composition of the ink by weight.

6. The inkjet ink according to claim 1, wherein the wetting agent is selected from the group consisting of polyoxyethylene dimethyl siloxanes, fluorosurfactants, and combinations thereof.

7. The inkjet ink according to claim 1, further comprising one or more buffers selected from the group consisting of triethanolamine (TEA), N,N-bis(2-hydroxyethyl)tuarine or N,N-bis(2-hydroxyethyl)-2-aminoethane sulfonic acid (BES), or combinations thereof.

8. The inkjet ink according to claim 1, further comprising a biocide.

9. The inkjet ink according to claim 1, wherein the penetrant is a 1,2-alkanediol.

10. A method of printing using an inkjet ink, the method being comprised of the steps of:
positioning a porous photo medium substantially adjacent to a printer having a print head retaining an inkjet ink, wherein the inkjet ink is comprised of copper phthalocyanine dye having sulfonylamine groups;
at least three co-solvents comprising about 18% to about 24% of the composition of the ink by weight, the at least three co-solvents including 1,3-propanediol, 1,2-alkanediol, and triethylene glycol;
a polymeric dye dispersant comprising about 0.5% to about 2.0% of the composition of the ink by weight;
a penetrant;
at least one wetting agent; and
water; and

jetting the inkjet ink from the print head onto the porous photo medium.

11. The method of printing using an inkjet ink according to claim 10, wherein the copper phthalocyanine dye having sulfonylamine groups comprise about 3.0% to about 6.0% of the composition of the ink by weight.

12. The method of printing using an inkjet ink according to claim 10, wherein the penetrant comprises about 1.0% to about 3.5% of the composition of the ink by weight.

13. The method of printing using an inkjet ink according to claim 10, wherein the at least three co-solvents further includes 1,5-pentanediol; and dipropylene glycol.

14. The method of printing using an inkjet ink according to claim 10, wherein the wetting agent is about 0.5% to about 1.5% of the composition of the ink by weight.

15. The method of printing using an inkjet ink according to claim 11, wherein the wetting agent is selected from the group consisting of polyoxyethylene dimethyl siloxanes, fluorosurfactants, and combinations thereof.

16. The method of printing using an inkjet ink according to claim 10, further comprising one or more buffers selected from the group consisting of triethanolamine (TEA), N,N-bis(2-hydroxyethyl)tuarine or N,N-bis(2-hydroxyethyl)-2-aminoethane sulfonic acid (BES), or combinations thereof.

17. The method of printing using an inkjet ink according to claim 10, further comprising a biocide.