Top layer coatability on barrier coatings

The influence on top layer coatability by different surface characteristics of dispersion coated barrier layers was studied. The barrier layer consisted of platy pigments such as talc and kaolin combined with different amounts and types of latexes. Coating of the top coat was carried out using reverse gravure technique where the dispersion consisting of mineral pigments and latex is applied under slight pressure onto the barrier coated substrate. Wettability and coatability were measured as a function of surface energy and surface roughness of barrier layer and surface tension of the top coat dispersion. Plasma and corona surface treatments were used for increasing surface energy and wettability without affecting surface topography. The most important aspect to predict coatability was the wettability and especially the water contact angle since the top coat is an aqueous solution. Decreasing the surface tension of top coat dispersion also improved coatability whereas roughness had only a minor effect.