Coating Structure
Ultra thin protective film applied in liquid form to paper or board has a thickness of less than one micrometer to block the passage of external substances. This sub micron barrier coating is typically formulated from aqueous polymer dispersions that form a continuous layer upon drying. By keeping the layer extremely thin, the substrate retains its paper like feel and remains easier to recycle than thicker laminated boards.
Barrier Efficiency
Resistance to grease and moisture transmission is achieved by the high density and cross linking of the polymer molecules in the dried film. Because the sub micron barrier coating occupies so little volume, it does not add significant weight or stiffness to the paperboard. This feature allows manufacturers to produce lightweight packaging with excellent protection.
Converting Utility
Application of the thin coating directly on the paper machine or offline coater requires careful monitoring of the surface tension of the base sheet. When a sub micron barrier coating is applied, it must dry rapidly without forming pinholes or causing the paperboard to curl. This uniform coverage allows subsequent printing and gluing steps to proceed without adhesion failures.
Converting plants value these coatings because they do not interfere with standard water based glues used in carton assembly.
