Surface oxidized carbon black pigments for improved inkjet ink performance

Abstract

This technical study focuses on two production processes - namely the widely used furnace black process and the gas black process. These pigment blacks types were then subjected to three different gas phase, post oxidation processes to alter the surface chemistry. The influence of these changes was evaluated in dispersion and inkjet ink form to gain a better understanding of their impact on a range of physical properties related to inkjet print performance. Besides the general physico-chemical analysis of these samples, advanced techniques like X-ray photoelectronic spectrometry (XPS) and titration methods are used to characterize the surface chemistry. Pigment dispersibility and particle size were determined. Finally, optical densities and inter-color bleeding properties of two formulated inkjet inks, based on these surface oxidized carbon black pigments, are evaluated. The test studies show distinct advantages of a surface oxidized carbon black pigment for improving dispersibility of aqueous systems as well as the influence of the oxidation process on critical print qualities such as optical density and inter-color bleeding.