Color Capability of Inkjet Coating

For inkjet printing, the print substrate plays a vital role in color reproduction. The simplest way to enhance color reproduction capability and print quality of inkjet paper is to add an ink-receptive coating to the paper. A typical inkjet coating formulation includes silica or alumina pigments as the key components, together with a binder and performance enhancing additives. The basic requirement for glossy inkjet paper coating is to fix the anionic inkjet colorants to the coating rapidly and efficiently. Since pigment is the primary determinant of print quality, it is important to understand the benefits and detriments to print quality, when using fumed alumina or fumed silica as coating pigments. The objective of this study is to evaluate the performance of the coatings in terms of roughness, paper gloss, optical density and color gamut. The results confirmed that fumed alumina coatings form smoother and glossier surfaces, while cationic silica has a rougher coating layer. The tested coatings were more attracted to the negatively charged dye-based inkjet ink. For fumed alumina coatings, the addition of polyvinyl pyrrolidone did not expand attainable color gamut. Optical density and color gamut improve with increases in the coat weight, with the exception of some colors printed on the dye-based printer. Additional passes through the calendering nip did not result in a significant improvement in color gamut.