METHOD AND APPARATUS FOR CURTAIN COATING

摘要

In a method and an apparatus for curtain coating of a moved substrate like a paper web substrate is moved below a liquid supply means providing a single or multilayer liquid coating in the form of a free-falling curtain impinging the substrate at a dynamic wetting line and a blade or air shield located upstream of the dynamic wetting line with respect to the moving direction of the substrate. The dynamic wetting line of the coating curtain on the substrate or web is oriented generally perpendicular to the moving direction of the substrate or web, providing substantially the same air pressure over an essential part of the coating curtain on its front and back side with respect to the moving direction of the substrate and providing a first supply air flow upstream to the wetting line. The supply air flows over a substantial length along the free-falling curtain and evacuates air from a location upstream of the supply air flow so that the air near the dynamic wetting line is moved against the moving direction of the substrate web and the boundary air layer entrained to the substrate. A second supply air is provided in proximity to the wetting line.