Enhancing color space of reactive ink using heat

#Inkjet printing is a popular alternative for home and office printing due to the low cost of inkjet printers, advances in quality of the printed images, and relative noise-free operation. Recent developments in inkjet technology allow consumers to use inkjet printing for creating traditional documents on “plain paper” or non-glossy media as well as creating high quality images or brochures on glossy media. Research and development of inkjet printing continues in order to improve inkjet print quality while maintaining a reasonable cost for the inkjet printer and the printing process.

#To print color images, inkjet printing uses a combination of cyan, magenta, yellow, and, optionally, black, light cyan, and light magenta inkjet inks to produce the colors of a color spectrum. Color inkjet inks are typically aqueous-based and are formulated by dissolving or dispersing a colorant, such as a dye or pigment, in an aqueous ink vehicle. The ink vehicle comprises additional components depending on the application and desired properties of the color inkjet ink, as known in the art. Water based inks are generally preferred in the inkjet printing industry because water is readily available at low cost, chemically unreactive, non-toxic and environmentally friendly.

#However, water-based inks are potentially limited in waterfastness of the printed image. The colorant is not immobilized so that when the printed image encounters water the image is degraded. Thus, there is a desire to develop methods that will increase the waterfastness of the aqueous based inks.

#While the specification concludes with claims particularly pointing out and distinctly claiming that which is regarded as the present invention, the present invention can be more readily ascertained from the following description of the invention when read in conjunction with the accompanying drawings in which:

#FIG. 1 is a flow chart depicting an embodiment of a method of the present invention;

#FIG. 2 is a flow chart depicting an optional post-printing heating step that may be included in the present invention;

#The present invention provides a color system for inkjet printing that exhibits enhanced color space. Fixer may be used with a dye-based color ink system to provide durability. However, fixer tends to precipitate the dye quickly, reducing dot gain resulting in lower chroma. The present invention provides enhanced color space by applying heat during printing.

#As used herein, “dot gain” refers to the net percent increase in halftone dot size over the initial, spherical drop diameter. “Chroma” refers to the attribute of color used to indicate the degree of departure of the color from a gray of the same lightness (ASTM E 284). “Print mode” refers to the number of passes printing. An n-pass print mode corresponds to putting down 1/n of a fixed amount of ink and fixer in the same pass. The process is repeated “n” times during printing. Fixer may be printed before or after the inks are printed.

#Ink and Fixer Compositions