Method and apparatus for applying a liquid coating to strip material

Abstract

Coating apparatus for applying a coating liquid to a moving roll. The apparatus has a trough-like pan, longer than the width of the roll surface to be coated, for holding a supply of the coating liquid. A pair of weirs is mounted on the pan which holds the coating liquid partially impounded therebetween. The weirs are spaced closer than the ends of the roll and the width of the roll surface to be coated. The weirs each are formed with a curved concave central portion having a radius the same or slightly larger than the radius of the roll, and with at least one overflow end portion to serve as a spillway. Coating liquid is supplied continuously to the central portion of the pan between the weirs and is drained continuously from the weir overflow end portions. The level of the coating liquid between the weirs is maintained at a higher level than coating liquid outside the weirs. The roll may serve as a backup roll for a strip passing around it or as a transfer roll to transfer the coating liquid from the pan to a strip in contact with the upper portion of the roll. A method of applying a coating liquid to one side of a strip of material by providing a body of coating liquid between a pair of spaced weirs which are mounted on a trough-like container. The material to be coated extends laterally beyond the weirs and is passed through the body of coating liquid in a curved path beneath a backup roll which is partially submerged in the coating liquid. The weirs each have a curved portion and at least one end overflow portion communciating with collecting compartments beyond the weirs. The coating liquid level in the collecting compartments is maintained below the lowest level of the curved weir portions whereby the excess coating liquid from the liquid body flows over the weir overflow portions, into the collecting compartments.