Dow Global Technolgoies LLC

Ilford Ag

Markus Gueggi

Sedat Varli

Peter Schweizer

A method and apparatus for curtain coating of a moved substrate, particularly for high-speed curtain coating of a continous paper web substrate, wherein a substrate () is moved below a hopper means (), provides one or more liquid coating materials in the form of a free-falling curtain () impinging the substrate at a dynamic wetting line. () Edge guide elements () are used for stabilizing the width and equalizing the flow speed of the coating curtain and allowing disturbance free provision of an auxiliary liquid () as well as practically compelte removal of the auxiliary liquid () wilst preventing the forming of solidification on the edge guides elements. An auxiliary liquid is injected () essentially parallel to the flow direction of the coating film at an edge of the coating film wilst moving along a slide of said hopper arrangement.

Method and apparatus for curtain coating

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.

An apparatus for curtain coating, particularly for high-speed curtain coating of a continuous paper web substrate () is provided with a hopper means () providing one or more liquid coating materials in the form of a free-falling curtain () impinging the substrate () at a dynamic wetting line. Edge guide elements () are arranged on both sides supplying a wetting or auxiliary liquid. Each guide element () has at least one contact area of its surface directed towards said curtain, which contact area has a multiplicity of grooves () and ribs () extending along the length of said edge guide elements ().

A method for curtain coating a moving support with a liquid coating material. An evacuating device is utilized to evacuate air carried along with the moving support. A device for carrying out the method includes a pourer having a pourer lip, a pouring roll carrying a support, and an evacuating device which is disposed in front of the curtain. The evacuating device includes an evacuating blade having a front edge facing the curtain. The front edge is provided with a slot which is connected to a vacuum installation. The method and device allow a substantial stabilization of the curtain at its point of contact with the support.

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