Highly transparent acrylate epoxidized soybean oil based UV–curable silicone–modified coatings with good thermal stability and flame retardancy

Thermal stability, flame retardancy and transparency are essential for UV–curable materials serving as package materials for some optical or electronics devices. In this paper, acrylate epoxidized soybean oil (AESO) based UV–curable silicone modified coatings with good thermal stability, good flame retardancy, transmittance above 97% were fabricated by UV initiated thiol–ene reaction of AESO and thiol silicone resin. The thermal stability of AESO–based UV–curable silicone–modified coatings is better than that of neat AESO–based UV–curable coatings reported previously, because the thermal initial decomposition temperature (Td5) of the former is in the range of 313–322 °C while that of the latter is only in the range of 214–283 °C. Cone calorimetry test denotes AESO–based UV–curable silicone–modified coatings possess good flame retardancy because the maximum value of the heat release rate (HRR) and CO release (CO Yield) for AESO–based UV–curable silicone–modified coatings are 450–550 kW/m2 and 0.02%–0.33%, respectively. The mechanism for the improvement of flame retardancy was studied by scanning electron microscope (SEM) analysis of the surface morphology of the chars after being burned.