Apparatus for coating a continuous web

Abstract

Apparatus and method for coating a continuous web, such as paper or transparent film of cellulose acetate or polyethylene terephthalate, with liquid materials, such as photographic layer materials, which require chilling before they are dried, are described. Immediately before the chilling zone, the web with liquid materials thereon passes through isolation means which displaces higher dew point air travelling with the web with air having a dew point below the temperature of the atmosphere in the upstream end of the chilling zone. The displacement is achieved by directing several flows of low dew point air at the web. The flows are extensive transversely of the web and are spaced apart longitudinally of the web. Air may flow away from the web between the flows towards the web. By ensuring that the dew point of the air travelling with the web into the chilling zone is below the temperature in the upstream end of the chilling zone, condensation is avoided. Further, it becomes possible to operate at least the upstream end of the chilling zone at lower temperatures than previously. The flows of air onto the liquid coating are of such low velocity that the uniformity of thickness of the coating is not disturbed.