Preparation of low viscosity and high flexibility epoxy acrylate and its application in UV-curable coatings

Epoxy acrylate (EA) is currently the most widely used UV-curable oligomer due to its short curing time, high coating hardness, excellent mechanical property, and thermal stability. To address the problems of high brittleness, poor flexibility, and high viscosity of EA, the UV-curable epoxy acrylate oligomer with low viscosity and high flexibility was prepared and applied to UV-curable coatings. The carboxyl terminated intermediate obtained by the reaction of anhydride and diol was used to modify EA to improve the flexibility of cured film, and the flexibility was adjusted through the length of the carbon chain of diols. The resin viscosity was reduced by partially replacing E51 with binary glycidyl ether. Compared with unmodified EA, the viscosity of the resin prepared in this study decreases from 29800 to 13920 mPa s (25°C), and the flexibility of the cured film increases from 12 to 1 mm. Compared with commercially available modified EA, the raw materials used in this study are low cost and easy to obtain with a reaction temperature below 130°C, using a simple synthesis process, and no organic solvents.