Rheological Properties of Highly Pigmented Inks: Consequence on the Color Printing Quality.

In order to optimize color reproduction, especially in the context of four-, six- or seven-color processes, ink makers formulate inks with unusually high pigment contents. The aim of this study is to examine the rheological characteristics of these pigment-rich inks, in order to get a better understanding of the ink transfer, and thus of the color printing quality. These formulations give rise to peculiar rheological characteristics, such as shear-thinning behavior, yield behavior, thixotropy and viscoelasticity. Continuous flow and dynamic viscoelasticity results are analysed, with particular emphasis on the effect of temperature. The dependence of the rheological and viscoelastic properties with respect to frequency and temperature displayed interesting features which will be discussed together with the corresponding color reproduction results.