Solvent-Based and Water-Based Knife Coating
topic
Solvent-based coating systems use organic solvent solutions of polyurethane, neoprene, or nitrocellulose at 20 to 40 percent solid content that dry by solvent evaporation in heated tunnels with solvent recovery systems capturing and recycling organic vapours before exhaust air treatment, while water-based systems use aqueous dispersions at 40 to 60 percent solid content that dry by water evaporation at higher energy cost from water's higher latent heat of vaporisation than organic solvents.
Role
Determines the coating compound solid content, drying system requirements, and environmental compliance obligations of the coating operation through the choice of solvent carrier system, with increasing regulatory pressure on VOC emissions driving conversion from solvent-based to water-based coating systems that eliminate organic solvent handling and recovery requirements while typically requiring higher drying energy and longer drying zones for equivalent solid coating weight application.