Previously, we have shown that coatings formulated with fumed silica pigments are capable of producing glossy inkjet media, despite the presence of these coating cracks, caused by shrinkage of the coating layer. However, their high cost and the inability to run them at high solids (>30% solids) limits their commercial application. Raising the coating solids with the addition of conventional pigments reduces the amount of shrinkage that occurs during drying, and thereby reduces the coating cracks, improving the final gloss of the coating layer.In this research, the solids of fumed silica coating systems were increased by adding co-pigments of different particle sizes. Fumed silica was used as the main pigment and precipitated calcium carbonate (PCC) and ultra fine ground calcium carbonate (UFGCC) were used as co-pigments. The ratio of fumed silica to co-pigments were 100:0, 90:10, 80:20, 70:30, 60:40, 50:50, 0:100. These blends of pigments were previously shown to produce high gloss and good printability. The coatings were applied using Meyer rods to obtain a coat weight of 10g/m2 on one side. The optical brightness, printability, ink density, and ink gloss were compared. Based on the findings, it is concluded that the co-pigment systems had optical properties and printing qualities as good as the mono pigment coatings.
Hyun-Kook Lee, Margaret K. Joyce, Paul D. Fleming, "Influence of Pigment Particles on Gloss and Printability for Inkjet Paper Coatings" in Proc. IS&T Int'l Conf. on Digital Printing Technologies (NIP20), 2004, pp 934 - 939, https://doi.org/10.2352/ISSN.2169-4451.2004.20.1.art00089_2