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US 4,051,278 AGranted
Method for reducing mottle in coating a support with a liquid coating composition
AssigneeEastman Kodak Company
InventorRoger E. Democh
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AssigneeEastman Kodak Company
InventorRoger E. Democh
Estimating the term…
In coating a support, such as a flexible web of synthetic organic polymer, with a coating composition comprising a film-forming material in an evaporable liquid vehicle, at least two of (1) the temperature of the atmosphere in the coating zone, (2) the temperature of the coating composition at the point where it is coated on the support, and (3) the temperature of the support at the point where the coating composition is applied thereto, are maintained at a temperature substantially equivalent to the equilibrium surface temperature of the coated layer within the coating zone. The equilibrium surface temperature is defined as the temperature assumed by the surface of a layer of the coating composition under steady state conditions of heat transfer following evaporative cooling of the layer in the coating zone. Such temperature control minimizes thermal gradients within the coated layer and significantly reduces the formation of mottle and similar coating defects. The method is especially useful in the coating of organic solvent solutions of polymeric resins and finds particular application in the manufacture of photographic elements.
In a method of coating a support with a coating compositionn comprising a film-forming material in an evaparable liquid vehicle in which said support is coated with a layer of said coating composition and said coated layer is dried, coating of said layer taking place within a coating zone containing a gaseous atmosphere and evaporation of said liquid vehicle occuring within said coating zone to thereby cause the temperature of the surface of said coated layer to decrease, the improvement which comprises maintaining at least two of (1) the temperature of the atmosphere within said coating zone, (2) the temperature of said support at the point where said coating composition is applied thereto, and (3) the temperature of said coating composition at the point where it is applied to said support, at a temperature which is substantially equivalent to the equilibrium surface temperature of said coated layer within said coating zone, said equilibrium temperature being the temperature assumed by the surface of said coated layer under steady state conditions of heat transfer following evaporative cooling of said layer in said zone, whereby the formation of mottle in said coated layer is reduced.
In a method of coating a support with a coating composition comprising a film-forming material in an evaporable liquid vehicle in which said support is coated with a layer of said coating composition and said coated layer is dried, coating of said layer taking place within a coating zone containing a gaseous atmosphere and evaporation of said liquid vehicle occuring within said coating zone to thereby cause the temperature of the surface of said coated layer to decrease, the improvement which comprises maintaining each of (1) the temperature of the atmosphere within said coating zone, (2) the temperature of said support at the point where said coating composition is applied thereto, and (3) the temperature of said coating composition at the point where it is applied to said support, at a temperature which is substantially equivalent to the equilibrium surface temperature of said coated layer within said coating zone, said equilibrium temperature being the temperature assumed by the surface of said coated layer under steady state conditions of heat transfer following evaporative cooling of said layer in said zone, whereby the formation of mottle in said coated layer is reduced.
Dependencies are inferred from the claim text.