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US 7,101,592 B2Granted
Method and apparatus for curtain coating
AssigneeDow Global Technologies LLC
InventorsMarkus Gueggi, Sedat Varli
Life of this patent
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AssigneeDow Global Technologies LLC
InventorsMarkus Gueggi, Sedat Varli
Estimating the term…
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.
A method for curtain coating of a moved substrate wherein said substrate is moved below a liquid coating 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, wherein the dynamic wetting line of the coating curtain on the substrate is oriented generally perpendicular to the moving direction of the substrate, providing substantially the same air pressure over the coating curtain on its front and back side with respect to the moving direction of the substrate, providing a first supply air flow upstream to the wetting line wherein the supply air flows over a substantial length along the free-falling curtain, and evacuating 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 and a boundary air layer entrained to the substrate, characterised in that a second supply air flow is provided in proximity to and upstream of the wetting line, so that the first and second supply air flows are provided between the curtain and any blade or air shield.
A method for curtain coating of a moved paper web substrate wherein said substrate is moved below a liquid coating 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, wherein the dynamic wetting line of the coating curtain on the substrate is oriented generally perpendicular to the moving direction of the substrate, providing substantially the same air pressure over the coating curtain on its front and back side with respect to the moving direction of the substrate, providing a first supply air flow upstream to the wetting line wherein the supply air flows over a substantial length along the free-falling curtain, and evacuating 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 and a boundary air layer entrained to the substrate, characterised in that a second supply air flow is provided in proximity to and upstream of the wetting line, so that the first and second supply air flows are provided between the curtain and any blade or air shield, and that the speed of air supplied in a gap between the substrate and said blade or air shield is at least about twice the speed of the substrate.
An apparatus with means for moving of a substrate to be coated wherein said substrate is moved through a curtain coater, comprising an arrangement with liquid coating supply means for providing a free-falling curtain of coating liquid, with a blade or air shield means provided upstream of said curtain to provide a small gap between the substrate and said blade or air shield, with a first air supply opening extending generally over the width of the substrate providing a first air flow in the region of the dynamic wetting line where the liquid coating curtain impinges on the substrate, and with a suction or vacuum providing means connected to said blade or air shield arranged to remove air from said gap between the substrate and said blade or air shield characterised in that the arrangement comprises a second air supply flow with an air supply outlet in proximity to, and upstream of, the wetting line, so that the first and second supply air flows are provided between the curtain and any blade or air shield.
Dependencies are inferred from the claim text.