New Eco-friendly Coating Formulations for Recycled Paperboards: Effect on Print Quality and Ink Volume Consumption

The coatings are commonly applied on paperboards in packaging to improve their strength and printability. This study focuses on the effect of new eco-friendly coating formulations on the colorimetric performance of recycled paperboards for packaging applications. China clay (F1) and montmorillonite clay (F2) based eco-friendly formulations were prepared and applied on selected recycled paperboards using a K-bar coater for three different coating thicknesses (4, 10, and 15 µm). The coated recycled paperboards were printed using an IGT printability tester, and the colorimetric performance was evaluated by comparing the color difference (ΔE) of the printed image with the ISO 12647-2 (2013) standard. The preliminary studies on coated recycled paperboards printed with black offset ink revealed that recycled paperboards coated with formulation F1 for 4 µm thickness showed better colorimetric performance compared to those coated with formulation F2. The China clay-based coating (F1) improved the surface structure by reducing the surface pores and roughness of the coated recycled paperboards. The improved surface structure, higher surface energy, and zeta potential of China-based formulation (F1) have resulted in better printability. Printing solid images using four-color offset ink with 1 and 2 mL ink volumes was used to test the colorimetric printability of coated recycled paperboards. Colorimetric printability was significantly improved using 1 mL of ink supply due to decreased ink absorption on coated recycled boards. The hypothesis test was carried out by performing paired t-test using IBM SPSS 20 software to verify the experimental results.