Wettability of Model Fountain Solutions and Their Influence on Offset Paper Properties

A surface chemical and physical characterization of offset paper was determined before and after application of isopropyl alcohol -based and isopropyl alcohol - free surfactant based fountain solutions, respectively. The paper surface features were characterized with Atomic Force Microscopy and the surface energies were determined from contact angle measurements. Changes in the surface chemical properties induced by the fountain solutions were investigated with Time-of-Flight Secondary Ion Mass Spectroscopy. Wetting of the coated papers with different model fountain solutions revealed a slight increase in Root Mean Square roughness with the surfactant based fountain solution. This change in sub- microroughness is not only ascribed to substrate swelling or migration of coating constituents but rather to the presence of surfactants on the surface. A change in the surface energy and particularly the polar contribution could be observed after application of the surfactant based fountain solution. Time-of-Flight Secondary Ion Mass Spectroscopy analysis showed further that the isopropyl alcohol based fountain solution does not change the elemental composition of the surface, while the surfactant based fountain solution clearly changed the chemical composition of the surface which thus is associated with the characteristic composition used.