Physical Properties of LWC Papers and Gravure Ink Mileage, 2005 Coating Conference

Paper properties, such as roughness, air permeability, pore size and their relationships to the ink mileage were studied. Ink mileage was measured using commercial toluene based gravure coated inks marked with trace metal carboxylates, which can be detected after printing by means of Inductively Coupled Argon Plasma (ICAP/ICP) Atomic Emission Spectroscopy (AES). Magenta ink was doped one metal carboxylate, while cyan and black inks were doped with another metal carboxylate. The amount of ink transferred was calculated from the ICP analysis of both wet ink and printed samples. Commercial LWC coated papers for rotogravure were used as testing substrates. Paper surface properties studied were air permeability (Parker Print-Surf (PPS) porosity), mercury intrusion porosimetry, and surface roughness, measured by PPS, Emveco stylus profilometer and Atomic Force Microscopy (AFM). It was found that compressed cells transferred more ink than elongated and normal cells. Paper porosity, permeability and pore size have more profound effects than surface roughness on amount of ink transferred to paper. However, the correlations between surface properties and ink transfer are not as clear as expected. Possible reasons could be the interaction between surface roughness and pore properties, or other unknown factors such as coating formulation and structure.