Silica as Surface Modifiers
Silica additives are very effective in lowering the
gloss of all kinds of systems - both solvent - as well as waterborne. The
matting effect relies on the porous and uneven shape of the silica particles.
When added in a sufficient quantity to a coating or ink, they will extend beyond
the paint surface when the film shrinks during the drying process, thus altering
the film from a smooth and even - glossy - surface to a mat one.
The silica matting ability suits particularly in both solventborne or aqueous systems.
However silica efficiency is limited in high-solid or solvent-free coatings because
of the lack of film shrinkage when paint is drying.