Hindered Phenol Antioxidant AO-10 (Coating Grade, Anti-Yellowing)

Yellowing in white coatings occurs through two main mechanisms: (1) Thermal oxidation during baking (160–200°C)—oxidative degradation of unsaturated sites in alkyd, polyurethane, or melamine resin; (2) Phenolic yellowing (also called BHT stain)—phenolic antioxidants in packaging material react with NOx to form yellow quinone-methide compounds. Hindered phenol antioxidants (AO-10) prevent mechanism 1 by scavenging peroxy radicals before they degrade the polymer chain. For packaging coatings susceptible to mechanism 2, use non-phenolic antioxidants (phosphite, lactone types). HALS stabilizers address photolytic mechanism but not thermal oxidation.