In the world of resins and related paints, which is not an exact science, the role of additives and other special products is extremely important to obtain characteristics that often are a fundamental requirement for meeting pre-defined technical specifications or to meet the needs of end users. In fact, paints that normally play an aesthetic role in improving a product’s appearance also provide mechanical or chemical resistance. As an example we can mention paints for household appliances or those for aluminum frames, two cases where the satisfaction of technical specifications is a necessary requirement for approval in the end market.
By definition, additives are added in small quantities, often less than one point percent, to re-inforce selected chemical or physical properties of the finished paint. The powder coatings sector is no exception, and has some limitations that are intrinsic to the technology itself, which are linked to the physical state of the paint before application on the piece to be painted. Powder paint particles must melt first (melting), then aggregate to form a homogeneous liquid film (flow) and finally crosslink to form the final coating film (crosslinking) (Figure 1). Sometimes the “orange peel” effect is created, which sometimes distinguishes the final appearance of powder coatings compared to more conventional liquid coatings.