Improving the inkjet codability of folding boxboard

Good inkjet printability requires a coating layer with good water absorption properties. A properly designed open coating structure helps to efficiently remove the water phase of the printing ink while controlling the penetration of the ink. The absorptivity of the coating is primarily dependent on the pigment type, as well as the binder type and amount. The pore volume of the coating layer can in principle be increased by introducing a structured pigment or a pigment with narrow particle size distribution. It is also important to optimize the binder type and level, with the aim to create a coating with higher void volume. The objective of this study was to achieve the best possible combination of sheet-fed offset and inkjet printability (i.e., one-color codability) by modifying the top coating formulation with respect to the calcium carbonate pigment type and the ratio of styrene acrylate/polyvinyl alcohol.