A simulation model to predict coating coverage

Factors affecting the coating coverage are investigated using mathematical modeling and numerical simulation. The Influence of application solids cont ent and dominant dewatering mechanism on the final coating microstructure i s probed. The covering of a sinusoidal base sheeet is modeled: contraction of the coating is shown to be the dominant factor controlling the surface s moothness: In-plane motion of particles is small under typical process cond itions. The results are discussed in light of experimental observations. The flow of suspension into a macro pore in the base sheet is modeled. Flow velocities close to a pore were found to be high enough to redistribute th e coating color locally. Spherical particles are able to "bridge" the pore and prevent other particles from entering the pore. Pores less than three s phere diameters, high particle concentration, and low electrostatic stabili zation encouraged the bridging mechanism to occur. The results provide a ph ysical picture that helps explain the improved coating holdout at high soli ds found in experimental studies.