Factors Influencing Surface Strength of Coated Papers

Abstract

This paper focuses on the influence of different coating color parameters on the surface strength of pilot coated paper as determined in full-scale sheet-fed offset printing. A tailor-made printing method using a special printing plate and high-tack inks was developed with the objective to evaluate the impact of different coating parameters on surface strength, mainly in terms of edge picking. Evaluated parameters included the solids content of the coating color, the type, fineness and particle size distribution of the pigment, the binder level, and calendering. The developed printing test method provided clear differentiation relative to the investigated parameters and it was possible to correlate these results with lab test data on ink-coating interaction and mercury intrusion porosimetry. It was shown that by maximizing the solids content of the formulation, the binder level could be optimized for cost savings while maintaining sufficient pick resistance. In addition, clear differences related to the type of pigment were detected. Other lab tests showed poor correlation with the observed degree of edge picking.