Drying rate of latex coating affected by the deformability of resin particles in convection drying

Latex paints are widely used, and many researchers pointed out that the film formation process depends on the deformability of dispersed polymer particles. However, the relationship between the film formation process and drying rate has not been totally understood due to the lack of accurate data on drying rate throughout the drying process. In the present study, we measured the drying rate of latex coating by the temperature change method proposed by Imakoma in convective drying. We revealed that the drying process significantly depends on particle deformability, especially in the former stage of the falling drying rate period. At a low drying temperature, the close-packed structure of polymer particles is formed throughout the film at the end of the constant drying rate period. On the other hand, partially deformed soft particles due to wet sintering inhibit the drying rate even under high moisture content at high drying temperatures. In either case, after forming the closest-packed structure, the shrinkage of the gap space between particles due to capillary deformation decreases the drying rate, proportional to the moisture content. Graphic abstract