Development of a High-Performance Single-Component Waterborne Acrylic Varnish Based on AAEM and Blocked Isocyanate for Enhanced Water Resistance and Durability in Automotive Coatings

To overcome the persistent issue of poor water resistance in single-component waterborne automotive varnish coatings, a novel AAEM (acetoacetoxyethyl methacrylate)-modified acrylic resin has been developed for single-component, waterborne automotive coatings, delivering exceptional improvements in water resistance, thermal stability, and corrosion protection. By precisely adjusting the ratio of methyl methacrylate to butyl acrylate and integrating methacrylic acid and N , N -dimethylethanolamine to enhance hydration stability, the resin achieves optimal hardness, flexibility, and adhesion. The incorporation of 10% acetoacetoxyethyl methacrylate dramatically enhances water resistance, extending beyond 10 days, while improving thermal durability and barrier performance, as confirmed by thermogravimetric and electrochemical analyses. Remarkably, the varnish achieved a high crosslinking density at just 110°C, resulting in a durable coating with 2H hardness. These advancements deliver superior weatherability and longevity, positioning this eco-friendly varnish as an innovative solution that meets the automotive industry's growing demand for sustainable, high-performance coatings.