Dependence of anti-graffiti properties of coatings on free surface energy

The adhesion between the phases to be contacted, i.e. between anti- graffiti and graffiti coatings, depends mainly on the size of the surfaces of the phases to be contacted and the intermolecular interaction formed at the phase boundary. The size of the surfaces of the phases to be contacted depends on the wetting ability of the surface, in this case graffiti, and the condition and structure of the surface to be wetted. One of the measures of the surface condition of polymeric coatings, used mainly to study the phenomena related to adhesion, is the value of surface free energy.S. According to the commonly ac-cepted criterion, proper wetting of polymeric surfaces occurs when their surface free energy is at least 10 mJ/m2 higher than the surface tension of the varnish product. The surface structure of the material is also an important factor influencing the interfacial interaction. The more developed the surface, the better the adhesion of the paint, the less developed the surface the less graffiti adheres to the protected surface. The aim of this study was to determine at what limits the free surface energy of anti-graffiti coatings are easily removable from the coating without damaging it. It was found that the value of surface free energy cannot be a criterion for qualifying paints or varnishes to the group of paint products with anti-graffiti properties, because the ease of graffiti removal is not directly dependent on it. Similarly, graffiti is removed from coatings with both high and low surface free energy. It seems that graffiti removal is therefore more influenced by the structure of the coating - its development, microporosity, etc.