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For years radiation curing lacquer systems have been broadly accepted in industry because of their environmental friendly and economical advantages. Important applications like coatings for furniture and packaging have a need for matt surfaces. So it is a challenge for the coatings industry to offer matt 100% UV systems with the same application and final film properties as for glossy systems. Numerous investigations exist on this complex topic. (Ref. 1 — 5) To achieve a low gloss or man film a microrough surface has to be created to allow diffuse lightscattering responsible for creating the visual effect of reduced gloss. In solvent- and water-borne systems this microrough surface is easily achieved when incorporating particles of a suitable size into the film followed by a substantial film shrinkage during drying due to evaporation of solvents or water. Micronised synthetic silicas with their low particle density and controlled particle size distribution are widely used as matting agents. Having in mind this matting mechanism, it is obviously difficult to achieve this effect in 100% systems because of the absence of volatile components. There is only a minor shrinkage of the film due to crosslinking. Incorporating porous particles with a defined oil adsorption can also give problems in controlling application viscosity at the high loadings necessary for low gloss. The matting agent suppliers offer a wide variety of products to satisfy these demands.
