Polyester resins as binders for powder coatings
Polyester resins have played an important role through the years as binders for powder coatings. Formulators have been working to expand the use of polyesters. This article discusses thermosetting and thermoplastic polyester resins and explains how polyester resins have evolved from their use in Europe to their expansion into North American markets. Recent developments in polyester resins that have allowed them to yield improved performance properties of powder coatings are also discussed.
Most polyester resins used for the thin-film decorative powder coating market today are thermosetting polyesters. Thermosetting polyesters can be defined as typically having functional groups such as hydroxyl [OH] or carboxyl [COOH] functionality. OH functional polyesters react with curatives such as polymeric-blocked isocyanates to form a film that melts, flows, and chemically reacts only once.