Coating device

Abstract

A device for coating a travelling web of material such as photographic paper with a coating liquid includes a means for transporting the web along a path of travel and a coating hopper of the slot or slide type positioned above the path of travel and provided with a pouring lip from which the coating liquid falls freely as a liquid curtain onto the web to be coated. The pouring lip is provided with a rectilinear sharp edge at a distance of 0.7 to 2.5 mm from an imaginary vertical plane in the operative position of the hopper which is at a tangent to the pouring lip at that boundary surface which is on the coating liquid side. By virtue of this sharp edge a straight wetting line, and consequently a very even curtain thickness can be obtained. If the coating hopper is of the slide type whose slide surface is cylindrically curved in the area near the pouring lip the radius of curvature is preferably within the range between 20 and 40 mm, particularly between 25 and 35 mm. The minimum flow rate necessary for maintaining a stable liquid curtain is thereby considerably decreased.

Dependencies are inferred from the claim text.