| Popis: |
A straightforward correlation of coating thickness and base sheet surface height (topography) data does not clearly show the expected differences between a contour coat-like structure for curtain coating or a leveling coat-like structure for blade coating. We defined a measure to clearly distinguish between these different kinds of spatial coating-layer formation. Filtering in the frequency domain preserves only the large structures in the coating-layer thickness and the base sheet topography data. The coefficient of determination (R²) and the slope of a linear regression model, between filtered coating thickness and base sheet surface height (topography), are the measures used to describe the leveling behavior of a coating layer. Three application systems—blade, film press, and curtain coating—were compared. Analysis of the original data showed only minor differences in the coating-layer formation between the application systems. For the filtered data where large structures are preserved, curtain coating gave an almost ideal contour coat, where coating thickness was hardly influenced by base sheet topography. The coating thickness in blade coating strongly depended on local base sheet surface height variations. A film press application of the coating layer resulted in a coating structure between curtain and blade coating. |
