Patent ID: 6015593
Filing Date: 2000-01-18
Classification: F26B,G03C

Abstract:
A method for evaporating a coating solvent from a coating on a substrate and for reducing the formation of drying mottle as the coating solvent is evaporating, the substrate having a first substrate surface and a second substrate surface, the method comprising the steps of:(a) applying the coating onto the first substrate surface, the coating having a first coating temperature;(b) heating the coating with a first drying gas at no faster than a first heat transfer rate, the first drying gas having a first drying gas temperature, the first heat transfer rate being created by a first heat transfer coefficient and a first temperature difference between the first coating temperature and the first drying gas temperature, the first heat transfer rate causing maximum evaporation of the coating solvent yet no more than an acceptable level of drying mottle, the coating being heated predominantly by heat transferred from the first drying gas and through the substrate second surface; and(c) heating the coating with a second drying gas at no faster than a second heat transfer rate greater than the first heat transfer rate after a first portion of the coating solvent has evaporated, the coating having a second coating temperature just before being heated by the second drying gas, the second drying gas having a second drying gas temperature, the second heat transfer rate being created by a second heat transfer coefficient and a second temperature difference between the second coating temperature and the second drying gas temperature, the second heat transfer rate causing a maximum evaporation of the coating solvent yet no more than an acceptable level of drying mottle, at least one of the second heat transfer coefficient and the second temperature difference being greater than the respective first heat transfer coefficient and first temperature difference, the coating being heated predominantly by heat transferred from the drying gas and through the substrate second surface.