Effect of coating solids content and thickener type on the depletion of fine particle size coating color components in the blade coating process

Depletion of fine particle size coating color components from the coating color during blade coating can cause an increase in average particle size and instability in runnability and end-product quality. This study focuses on some possible controlling parameters for particle size segregation, mainly solids volume concentration and the type of thickeners used. The laboratory coater was used to study changes in coating color composition. The fine particle size fraction (< 0.2 pm) was the most prone for depletion, causing an increase in average particle size. The results show that both an increase in solids volume concentration and increased strength of structures between coating color components decreased the depletion of fine particles. Time-dependent changes in a coating color composition can be decreased by controlling the depletion of fine solid particles. This results in more stable process, more uniform product quality and more optimized use of raw materials.