In-situ observation of drying distribution on cm 2 -scale coating films

Observation of drying films in industrial dryers is generally difficult, and we still do not understand drying processes. Especially, uniformity is a crucial factor in dried films and it is important to observe when and how distributions appear. In this study, we conduct in-situ observations of drying cm 2 -scale films using 2-D thermography, digital camera and an electric balance simultaneously. We found that surface temperature and gloss of drying films are closely related, from which we are able to determine distribution in drying progression. In addition, because both are obtained as two-dimensional data, shift from a constant-rate drying period to decreasing-rate one at a local position of drying films can be defined. Correlations of the data obtained are discussed.