GB1358298A - Method and apparatus for caoting continuous web - Google Patents

Abstract

1358298 Coating apparatus for webs EASTMAN KODAK CO 15 July 1971 [16 July 1970] 33198/71 Heading D1L A moving web is coated and overcoated by applying to the surface of a web a liquid composition, smoothing the applied coating by moving the coated web past the end of a flexible, trailing stationary blade which may have the other end fixed to a hopper, continuously metering a quantity of the same or a different composition as a layer onto the upper-most surface of the blade at a point spaced above the flexible end, allowing the layer to flow down the blade onto the coated web to form a coating thereon and curing the applied coatings simultaneously. The second coating is preferably applied to the blade from a cavity in the hopper via a discharge slot connecting the cavity with the upper-most surface of the blade. The Figure shows a two layer coater utilizing a single hopper for both coatings. A trailing blade 13 with flexible end, clamped between two sections 16 and 17 of the hopper is in engagement with the surface of web W or the coating applied thereto carried by rotating roller 10. The hopper section 17 contains a cavity 18 from which the coating composition fed into cavity 18 via inlet 19, is discharged through slot 20 as a flowable layer L along the underside of the blade to form a bead 21 extending completely across the deflected end 12 of the blade and between it and web W, and forming on the moving web a smooth first coating. The overcoating is applied from hopper section 16 via cavity 22 and downwardly inclined elongated slot 24 formed between the faces of hopper sections 16 and 23, to a point on the uppermost surface of the blade 13, as a ribbon which flows by gravity to form the layer L 1 which overcoats the first layer. In another embodiment, not shown, the first coating is applied to the web by a device separate and distinct from the hopper whilst in a further embodiment not shown, three coatings are applied to the web, one from a separate device and two from the hopper. The end of the blade may be knife-edged, rounded, or a compromise between rounded and knife-edged. The web is preferably raw paper, precoated baryta paper or polyethylene coated paper.