Analysis of Liquid Absorptivity of Paper by Dynamic Scanning Absorptometry Part II. Correlation with Smoothness and Two-Sidedness of Paper

Abstract

Influence of surface roughness of paper on its liquid absorption behavior was studied by dynamic scanning absorptometry (DSA). Commercial wood-free and newsprint papers showed small but definite differences in water absorptivity between top side and bottom side, apparently due to the difference in surface roughness. Laboratory handsheets with surface roughness modified by combinations of various wet press conditions and drying methods showed significant variations in roughness index and absorption coefficient. Handssheets with widely differing roughness prepared by wet-pressing against sand papers of various grades gave roughness index values corresponding to the sand paper grade used. There is positive correlations between the roughness index and the absorption coefficient for water, showing that surface roughness itself is a controlling factor for absorptivity; the relation, however, depends on the level of sizing. Roughness index with linseed oil as test liquid showed more direct dependence on surface roughness than with water. Absorptivity of linseed oil, on the other hand, did not depend on surface roughness. Rouhgness index values from DSA measurement showed a universal correlation with the air-leak type smoothness (Oken Smoothness) for a wide range of roughness.