Why is 2-Ethoxyethyl acetate (CAC) essential in PU coatings and how does its slow evaporation affect film quality?

Why is 2-Ethoxyethyl acetate (CAC) essential in PU coatings and how does its slow evaporation affect film quality?
CAC is a critical slow-evaporating solvent in polyurethane coatings, often referred to as the 'PU slow-dry solvent' in Chinese formulation practice. Its balanced solvency dissolves polar resins while remaining compatible with oil-based components, making it versatile across nitrocellulose, alkyd, and two-component PU systems. With an evaporation rate of only 0.2 relative to butyl acetate and a boiling range of 150-160°C, CAC extends open time, allowing films to level properly and reducing defects like orange peel and moisture-induced blushing during humid summer spraying. In industrial baking enamels, it volatilizes smoothly during cure, preventing bubbles and gloss loss. Its high dilution ratio and surface tension of 28.2 dyne/cm also improve substrate wetting and final film adhesion.