Details:
Summary:
Print gloss is one of the most important attributes of a printed product. � While is it well known that gloss mainly depends on the surface smoothness, it is less well understood how paper, inks and varnishes interact to generate a specific gloss. � Ink films are known to start from a highly textured structure after the splitting of the ink film, but need to level to a smooth surface before the ink solidifies.
A model is developed that predicts the surface tension driven leveling of an ink film. � The model inputs are the ink rheology, the surface tension of the ink, and the solids of the ink. � In addition, the pore structure of the paper is taken into account to predict the setting of the ink on the paper. � The model includes the formation of a filtercake that grows during setting, but then limits the leveling of the ink film. � Other predictions, based on other ink setting models are compared. �
The model results are compared to experimental results. � The low gloss that can be obtained with certain inks and ink film thicknesses is linked to the ability of the ink films to level. � As ink oil are absorbed into the coating layers, the filtercake thickness increases decreasing the ability of the ink film to completely level.