Key Attributes and Opportunities of Multilayer Curtain Coating for Paper, 2005 TAPPI Coating Conference

Curtain coating is an emerging low-impact premetered application method for coated paper and paper board. Most of the work to date has focused on single layer curtain coating using slot die curtain applicators. Multilayer curtain coating offers several advantages over single layer curtain coating. These advantages include low capital costs, flexibility in coating design, wide operational latitude in terms of coating rheology, and avoidance of issues such as heel formation and air entrainment that are particularly important at high application speeds. The photographic industry has used multilayer curtain coating for many years, but the operating conditions used in the photographic industry are substantially different from those used in the paper industry. This paper reviews the fundamentals of multilayer curtain coating using slide die curtain applicators and provides several working examples of multilayer curtain coating under conditions relevant to the paper industry. These examples demonstrate the utility of using a thin interface layer to improve runnability at high speeds, the use of a very thin functional topcoat over a lower cost basecoat to achieve good coating properties, and the combination of these concepts into a three layer light weight coating (LWC) that cannot be applied by any other coating method.