Quantifying Matting Agent Displacement in Package Printing Overprint Coatings
Quantifying matting agent displacement requires z-axis Raman depth profiling and strict viscosity recovery control to stop gloss drift and scuff failure.
Matting Agent Displacement
Coating Morphology
Silica particles create surface roughness within a binder matrix to control gloss levels on paper substrates. Matting agent displacement occurs when these particles migrate away from the surface during the curing phase of an aqueous or solvent coating. This phenomenon reduces the effective light scattering properties of the layer, resulting in an unintended increase in gloss measurement.
The primary trigger for this movement is the rapid evaporation rate of the solvent carrier which pulls the additive deeper into the wet film before solidification.
Surface Uniformity
Pressure during the film formation phase influences how evenly the particles remain suspended. High mechanical shear forces or excessive coating weight can drive the matte additive toward the interface between the substrate and the ink receiving layer. Corrective adjustments to the drying profile or the inclusion of rheology modifiers stabilize the matrix to ensure the silica remains exposed.
Operators monitor the surface topography using optical profilometry to ensure the distribution stays within the requested tolerance for the final finish.
Print Performance
Finished products lose their desired tactile qualities when the particles settle inside the film structure instead of creating micro-indentations at the surface. Lower friction coefficients follow this shift because the lack of surface texture changes the slip resistance of the stock. Converting machines encounter feeding difficulties as the coefficient of friction drops below the mechanical threshold required for reliable sheet separation.
Precision in the drying kiln prevents these issues by locking the particle orientation into a fixed state before the film reaches its immobilization point.