Influence of Filler Type on Surface Topography and Printability in Supercalendered Paper, 1999 International Paper Physics Conference Proceedings

Marielle Lorusso, William W. Sampson, Christopher T. J. Dodson

Modern grades of supercalendered paper are produced using blends of filler. This study concerns the influence of filler types and blend ratios on the optical properties and printing characteristics with a view to ptimising the use of fillers. Papers containing standard kaolin, calcium carbonates and blends of both pigments were produced on a pilot paper machine. The sheets were calendered and printed. Surface roughness was measured by profilometry; surface compressibility was determined through the change in PPS roughness with clamp pressure. The results show that roughness or compressibility alone are not good predictor of print quality. However, our experiments confirm the findings of Bristow that the pressure requirement, which combines these surface characteristics, correlates well with the percentage of missing dots. We note however that the correlation does not persist for papers containing only calcium carbonate filler. A measure of bulk compressibility, related to void volume, was found to correlate well with missing dots for any filler considered. The results demonstrate that the amount and type of kaolin in a blend are predominantly responsible for the amount of missing dots, and that the internal paper structure has a more significant effect on ink transfer than surface properties.