Development of new aqueous resin ink for sign graphics

Abstract

An aqueous resin ink was developed which can offer excellent image qualities on non-permeating media such as plastic media with an inkjet printer. The print speed with this aqueous resin ink reaches the level of solvent-inks diffused as inks for non-permeating media for sign graphic, i.e., at least 30m2/h. In order to increase the print speed, it is important that the ink has good compatibility to the coating layer of non-permeating media. It was found that kinds of solvents added to the ink were highly related to the compatibility. Furthermore, such solvents have a particular feature in common. Solvents with specific range of fractional parameter have high coating layer-solving ability. To show validity of this mechanism, a new method for evaluation of ink fixation was developed. With this new method, it was proved that higher concentration of coating-layer-solving solvent gave ink faster fixation onto the non-permeating media. Furthermore, we also discovered that the characteristics of the pigment dispersion element in an ink formula greatly affected the discharging reliability.