Thin Film Coating Laboratory
We investigate the phenomena relevant to the coating and drying of liquid films. The applications are in the large scale manufacturing of numerous sheet goods from printing papers to flat panel displays. Sometimes several layers are coated and dried simultaneously for increased efficiency at the cost of increased complexity. The relevant phenomena include capillary hydrodynamics and associated instabilities, complex rheology, and surface-tension-driven flow. Hardware design is important for forming uniform layers and applying them to a substrate, often a wide, thin and continuous sheet of paper or plastic moving at one meter per second or faster. The many coating methods in use developed largely as art, and the goal of research is to replace or augment coating art with engineering science. One device in the lab is an empirically developed instrument for measuring the dynamic action of surfactants in a flowing liquid with an air-liquid interface. Although the apparatus and its utility are long known, the linkage between the measurements and coating methods is still an area of active research. Current work is directed toward improving the design of the apparatus and developing a mathematical model to enhance its application to coating methods.