CHAPTER 15. Green Chemistry for Automotive Coatings: Sustainable Applications

This chapter introduces automotive OEM coating systems with a focus on powder coatings. Driven by more stringent environmental regulations, the world powder coating demand is projected to grow from $7.5 billion in 2014 to $11.0 billion in 2020, at a CAGR of 6.8% between 2015 and 2020. In addition, the global quantity was 2 045 000 tons in 2014. The growth of powder coatings is outpacing conventional solvent-borne liquid coatings, as powder coatings exhibit significant economic and environmental benefits comparatively. Powder coatings have been successfully implemented as a primer-surfacer and clearcoat on car bodies. They are also used extensively for under-hood and underbody components. Innovative techniques have been invented to overcome the shortcomings of powder coatings such as high film thickness and inferior visual appearance. One example of such endeavors is the incorporation of nano-sized additives as spacers to improve the flow behavior of ultra-fine powder coatings. As heat sensitive plastic or composite parts have been increasingly employed in the automotive industry, UV curable powder coatings have significantly reduced heating temperature and boosted production rate thanks to the rapid curing process. Waterborne liquid coatings for automotive uses are also discussed as a comparison. Waterborne coatings enable substantial energy savings by a compact process, namely wet-on-wet spray, which eliminates high-temperature baking between coats of primer-surfacer, basecoat, and clearcoat. Volatile organic compound (VOC) emission is also significantly reduced by this technology. Powder coatings and waterborne liquid coatings are still evolving and competing, both leading to greater cost-saving, lower energy consumption and less pollution. The goal of future development might be a complete powder coating system of primer-surfacer, basecoat and topcoat due to its ecological benefit.