Technology Newsline

"In order to understand the advantages of Claria, it’s helpful to briefly review the differences between the two types of ink available for printers pigment-based inks and dye-based inks," says Hiroko Hayashi, general manager of R&D inkjet printing engineering in Epson’s Imaging Products Operations Division. Pigment-based ink, she explains, is composed of microscopically small particles that cannot easily be dissolved in water. Pigment ink is characterized by its longevity and durability under adverse environmental conditions, such as exposure to light, gases, and water. Though pigment ink renders text clearly on plain paper, it does not easily produce a glossy finish on photo paper, because of its particulate composition.

Epson has developed pigment ink that achieves excellent performance in both photo and text printing by improving the composition of the pigment and pigment-coating resin. Two types of this ink have been launched. One is DURABrite, an all-around ink that can be used to print ordinary photos and documents, and the other is UltraChrome (K3 and Hi-Gloss), which produces a wide color gamut and a glossy finish on photo paper to meet the needs of professional photo users.

Dye-based inks, meanwhile, says Hayashi, are easily dissolved in water, which enables them to produce sharp images and bright colors on many types of photo paper. They fare worse than pigment inks under adverse environmental conditions, however, and are less resistant to light and oxidization. "Dye inks produce high-gloss results on photo paper and enable users to enjoy photo printing. So a dye ink that is also resistant to light and oxidant gas represents a breakthrough," says Hayashi. "Claria has raised the bar for what a dye ink can achieve."

Epson began research and development of Claria more than three years ago under the leadership of Kazuhiko Kitamura, an R&D inkjet engineering manager in the Imaging Products Operations Division. "After numerous trials and tests, we succeeded in not only significantly strengthening the permanence of the dye but also in improving the ink’s quality, so that today it delivers unequaled high-definition printing," says Kitamura.

The researchers actually found it relatively easy to improve on the ink’s light fastness (its ability to maintain its chemical composition and color under lighted conditions). Similarly, it was not difficult to improve on the ink’s gas fastness (its durability when exposed to naturally occurring gases like ozone, which cause ink to deteriorate over time).

"The real challenge came in maintaining or improving the ink’s quality when modifying it to improve its overall durability," says Kitamura. "This was very difficult." Success was only achieved after the researchers significantly altered the ink’s chemical structure at the atomic level, a process that resulted in the creation of new chemical compositions.

Kitamura explains that light and gases cause ink to deteriorate by leaching away electrons that form the bonds between the atoms of the ink’s molecular structure. Over time, this leads to a breakdown of the chemical structure, resulting in fading colors.

To counter this, the researchers created new chemical formations by adding additional atoms to the dye’s basic molecular structure, and then engineered the molecules into tight clusters. This not only strengthened the ink’s atomic bonding, better protecting it from the effects of light and gases, but also improved the quality of the ink.

"In non technical terms, we have created a more durable ink in which the color black is now even blacker and yellow is a more vivid yellow," says Kitamura. "The difference between Claria and our previous dye inks–or, for that matter, the inks produced by our competitors–is significant." In fact, he adds, "the quality is now better than lab printing." In addition to improved durability, Kitamura says that Claria is more resistant to water spills and humidity and that, thanks to its quick-drying formula, prints can be handled immediately after printing without fear of smudging.