Drying of Coated Paper:Simulation and Pilot Experiments

This paper presents a new structure of the macroscopic drying model for simulation of the drying process of the coated web. The consolidation (dewatering) process of the coated layer is divided into three phases separated by the first and second critical points. The model takes into account filter cake formation, and skin layer formation on the coating surface. Other drying parameters such as temperature and moisture profiles, absorption and evaporation rates are calculated by this model. Some of the experimental results obtained from the pilot coating trials are also shown and these are compared with the simulated data. Commonly measured data included paper temperatures in drying. Furthermore, gloss, scattering and web moisture, measured between the drying units with newly developed measurement system, are presented here. Analysis of the simulated and measured data showed that the moisture penetration rate into the base paper slowed down dramatically after the first critical point. Mottling behavior of the printed samples in conjunction with the drying conditions is also discussed