Thin coatings for paper by foam coating

Abstract

The future of paper products is predicted to lie in intelligent and functional paper properties. These properties are achieved by using coating materials, which are usually very expensive, but the amount needed is also very small. The application of these small amounts requires a new type of coating method; conventional coating methods used in the industry today are not capable of providing ultrathin layers. In this study we introduce foam coating, a technology widely used in the textile and nonwovens industries. Foam coating technology offers a unique opportunity to apply coating on the web surface thinly enough to be economically viable. Our pilot-scale studies show that a thin coating of nanomaterial at a thickness of 1 μm or less and coat weight of 0.3-2.0 g/m2 is enough to change paper surface properties and enable the functionalization of the paper surface. This report describes the applicability of the curtain-like foam coating technology in unmodified cellulose nanofiber (CNF) applications.