Organic coatings on powder pigments basis.: II.: Thermoreactive powder pigments

Thermosetting powder coatings are very fine particles of polymeric materials, used to obtain organic coatings for many applications. They have as binders thermosetting polymers (epoxy resins, polyesters, acrylic copolymers) and cross-linking agents which are included in a large range of chemical classes (amines, isocianates, phenols, oxiranic compounds, polyesters). Depending on formulation, especially depending on the nature of the thermosetting system (polymer and hardener, the organic coatings based on thermosetting powder coatings present specific characteristics, such as mechanical properties (impact resiatance, adherence, flexibility, elasticity etc.), optical properties (gloss, appearance, colour), chemical resistance, weathering resistance. The paper presents the main classes of thermosetting powder coatings (epoxy, epoxy-polyesters, polyesters, polyurethanes, acrylics), their main constituents and the chemical reactions for the cross-linking of each system, their properties and uses.