Method of curtain coating a moving support wherein the maximum practical coating speed is increased

摘要

Curtain coating processes arc well known wherein a composition is coated on to a moving support. However, the maximum coating speeds in such processes are severely limited at high curtain flow rates by the formation of a region metastable to air-entrainment. Described herein is a method which enhances the maximum coating speed at high flow tales by the application of small levels of voltages, typically below 400 V, to the moving support. Progressive suppression of the metastable region is obtained as the, voltage level is increased. All levels of voltage up to 400 V give a degree of removal of the metastable region, and therefore will enhance the maximum practical coating speed. Lower levels of voltage may also be used in conjunction with forward application angles to selectively enhance the maximum practical coating speed for a given laydown.