The Development of Pigment Ink for Plain Paper

Abstract

Pigments that exist as particles are inferior to dyes in terms of color expression and transparency but exhibit excellent water-fastness, lightfastness, gas-fastness and other properties of stability and longevity. In addition, the penetration of pigments in the recording medium can be controlled. In 2000, Epson unveiled the StylusPhoto 2000P, our first inkjet printer equipped with μ-CRYSTA pigment ink. By shrinking the size of pigment particles and micro-capsulating them, we achieved high image quality on specialty media that turned the image of pigment upside down. The main target of this printer was specialty media, but the reason was that we had not yet developed ink that could support plain paper. The following year, in 2001, we released the EPSON Stylus C80, a four-color printer, equipped with ink that contained high density of pigment to improve performance on plain paper. The printing speed, print quality, and durability of the printed matter earned the printer high marks as a multipurpose model. However, the quality on plain paper was still not entirely satisfactory.Further investigations into the realization of high print quality on plain paper confirmed that print density on plain paper is largely dependent on the state of pigment dispersion. This finding led us to optimize the dispersion of pigment and match it with the ink formulation, thereby developing a new pigment ink that exhibits dramatic improvement in print density on plain paper and that is compatible with many different types of paper. This paper discusses print head and pigment ink technology with which new Epson printers are being equipped in 2002.