Forward Deformable Roll Coating at High Speed with Newtonian Fluids

Abstract

The flow of Newtonian fluids through the deformable nip of a high speed roll coater was experimentally studied. A digital video system was used for the observation of the formation, elongation and break-up of fluid filaments at the exit of the nip and to investigate how misting droplets are ejected to the surroundings. The pressure profile in the nip was obtained by a miniaturized piezoelectric transducer mounted on one of the coater rolls. Experimental results show that both film splitting and air entrainment into the nip can be responsible for misting occurrence when a low load is applied between the rolls. When a high load is applied, misting can be eliminated and a periodic flow is generated in the nip gap.