Curtain coating - Technology and application

Curtain coating is a contact-free application process and only functions at a minimum flow-through rate of ca. 6000 g/min and in working widths with adequately low surface tension. The viscosity should be in a certain range from 50-300 mPas at a shear speed of 1000 1/s. The precise limit depends on the use and the flow curve. In addition to the viscosity and surface tension, the air boundary layer and the behavior at the side leads play a role. The basic dispersion of the coating medium is made by the die, which is adapted to the particular Theological properties of the mass. The application weight is defined only via the pump (mass flowthrough) and the coating speed. The feed pump must be pulsation-free, The coating mass may not include any air bubbles. A high-value product, with all the advantages of the process, can only be created in curtain coating when all the conditions are fulfilled.