Web coating applicator with cooling and material recovery
View Patent ↗Apparatus and method for applying a water-based emulsion of silicone fluid to a printed web required to be cooled, such that evaporative cooling of the web is promoted in addition to coating of said web with a silicone material. Water evaporated following the application of the silicone fluid to the web is recovered by condensation on the applicator(s) and reapplied to the web, thus economizing the amount of silicone fluid mixture necessary to provide both cooling and enhanced slip characteristics necessary for further handling and processing of the web. The condensation step is effected by containing the evaporated water from the web within a compact enclosure enveloping both the applicator(s) and the web, and optionally chilling said applicator(s) with a cooling medium, preferably water, by means of said cooling medium flowing through at least one of the applicators. In certain embodiments, in addition to condensing the evaporated water, the airborne silicone mist created in the coating step is captured and is returned to the fluid applicator.
1. A method of applying an applicator fluid to a heated web with at least one cooled applicator roller and promoting recovery of evaporated fluid by condensation of said evaporated fluid on the surface of said at least one cooled applicator roller in the immediate vicinity of contact between said heated web and said at least one applicator roller, said web traveling in a web path; said method comprising: providing a supply of applicator fluid comprising silicone and water for application to said web by said cooled applicator roller upon web-to-roller contact; internally cooling said at least one applicator roller with a cooling fluid; enclosing said web path in the extended vicinity of web-to-roller contact of said at least one applicator roller thereby conducting the boundary layer of air and vapor moving with said web to the vicinity of the surface of said at least one cooled roller to promote recovery of evaporated fluid by condensation.
2. Apparatus for cooling a web, said apparatus comprising a supply of an applicator fluid comprising silicone, and an applicator roller transferring said applicator fluid to said web, wherein said applicator roller is internally cooled by a cooling fluid and at least partially enclosed by an enclosure in the proximity of web-to-roller contact such that upon evaporation of said applicator fluid from said web, evaporated fluid remains within said enclosure and condenses on said applicator, wherein the surface of said roller has a smoothness of Ra 5 or less.
3. The apparatus of claim 2 , wherein there are a pair of applicator rollers, the first of said pair of rollers contacting said applicator fluid and the second of said pair of rollers contacting said first roller and transferring applicator fluid from said first roller to said web.
4. Apparatus for cooling a web, said apparatus comprising a supply of an applicator fluid comprising silicone, and an applicator roller transferring said applicator fluid to said web, wherein said applicator roller is internally cooled by a cooling fluid and at least partially enclosed by an enclosure in the proximity of web-to-roller contact such that upon evaporation of said applicator fluid from said web, evaporated fluid remains within said enclosure and condenses on said applicator, wherein the surface of said roller has a smoothness of Ra 1 or less.
5. The apparatus of claim 4 , wherein there are a pair of applicator rollers, the first of said pair of rollers contacting said applicator fluid and the second of said pair of rollers contacting said first roller and transferring applicator fluid from said first roller to said web.