Method and apparatus for reducing fluid flow disruptions

#The present invention is related to methods, apparatuses, systems, and computer program products for clearing or reducing fluid flow disruptions in the application of coatings to substrates such as paper.

#Coating a web of paper is generally effected by the application of a liquid coating material onto a moving web. The coating material may be comprised of a solid constituent suspended in a liquid carrier. The quality of the coating applied onto the paper web depends upon a number of factors, an important one of which being how the material is applied. The application of the coating material should preferably result in a coating that is smooth, continuous and uniform across the web.

#Fountain coating of paper is a coating process in which the liquid coating material is jetted in a free-standing curtain of coating liquid directly onto the moving web with a fountain applicator. The fountain applicator comprises an elongate nozzle that includes a metering slot for communicating the coating fluid onto the web. The nozzle extends in a cross-machine direction coextensive with the paper web moving adjacent to it and supported by a backing roll. A downstream doctor blade meters and smoothes the coating. The amount of coating applied to the web may be controlled by controlling the size of the metering slot and pressure of the coating fluid. Desirably, a substantially uniform coating layer is applied across the width of the web. Fountain coating applicators are generally known in the art, with examples disclosed in U.S. Pat. Nos. 5,436,030 to Damrau and commonly owned by the assignee of the present application, which is hereby incorporated by reference.

#FIG. 1 is a schematic elevational view of a coater station illustrating an embodiment of the invention.

#FIG. 2 is a cross-sectional view of a fountain applicator having a vibrator mounted to the nozzle thereof.

#FIG. 3 is a schematic perspective view of a coater system embodiment of the invention.

#Before discussing several embodiments of the invention in detail, it will be appreciated that the discussion herein and the drawings may be useful in describing any of method, apparatus, system, and/or computer program product embodiments of the invention. Accordingly, it will be understood that discussion herein related to any of the embodiments of the invention may relate to another embodiment. By way of example, it will be appreciated that a computer program product embodiment may comprise computer readable instructions stored in a computer readable medium that when executed by a computer cause the computer to carry out the steps of a method embodiment. Similarly, it will be appreciated that a method embodiment of the invention may comprise performing steps using a system or an apparatus of the invention.

#Turning now to the drawings by way of illustrating the best known modes for practicing the present invention, FIG. 1 is a schematic elevational view of a fountain coater station, indicated generally at 2 comprising a backing roll 6 for supporting a moving paper web 8, an applicator 4, and a doctor 9. Those knowledgeable in the art will understand that the coater station 2 may be a component of a paper machine (i.e., an on-machine coater) or may be a component of an off-machine coater. The coater station 2 extends in a cross-machine direction substantially coextensive with the width of the web 8, for example in FIG. 3.

#The applicator 4 comprises a nozzle 18 having a front wall 10 and back wall 12. The walls define a metering slot 14 therebetween. The slot 14 has a minimum gap width 16 that is the closest separation of the front and back walls 14 and 16. A chamber 17 communicates with the slot 14. In operation a coating composition is delivered under pressure from the chamber 17 through the nozzle 18, and applied onto moving paper web 8. The nozzle 18 functions to meter the flow of coating material and impinge a uniform ribbon or sheet of coating onto the web, forming an excess coating layer 20 on the moving web. The coating layer is doctored to a desired coat weight by doctor 9.