Polyurethane Powder Coatings: A Review of Composition and Characterization

Powder coatings have gained a lot of attention since the 1960s and the 1970s (implementation of polyurethanes into the market) because of the environmental and ecological concerns. Over the decades, there have been several publications relating the manufacturing and development of powder coatings as an alternative for liquid/solvent or water-based organic coatings. In general, powder coatings can be divided into two main groups based on the properties of the resin being used, thermoplastic and thermoset powder coating systems. Among thermoset powder coatings, polyurethane powder coatings have outstanding properties such as weather stability and are the best choice for exterior applications comparing overall properties. This paper reviews the most recent advances in the field of powder coating by focusing on polyurethane powder coating as a group of thermoset powder coatings. It also considers the industrial problems engaged in this field, such as emission of the blocking agents, the low reactivity of uretdione systems, and high curing temperature and their solutions. Finally, it also suggests the future potential investigation of polyurethane powder coating compositions and improvements.