Fabrication and performance of UV cured transparent silicone modified polyurethane-acrylate coatings with high hardness, good thermal stability and adhesion

摘要

Conventional UV cured PUs suffer from low hardness, which will be scratched during the course of storage and transportation. They also undergoes severe pyrolysis when the temperature exceeds 200 degrees C, and the poor heat resistance limit their application in the high-temperature field. To address these challenges, a type of UV cured transparent coatings were prepared with thiol silicone resin and polyurethane-acrylate through thiol-ene click reaction. The coatings obtained are with high hardness, excellent scratch resistance, good thermal stability, fairly strong adhesion, efficient water resistance and good UV radiation resistance. More specifically, the pencil hardness and initial thermal decomposition temperature are in the range of 6 B-9 H and 297 degrees C-306 degrees C respectively, which are more superior to those of the conventional UV cured PUs. More strikingly, the coatings obtained with excellent scratch resistance because there are no traces on the coatings, even the slides are broken, when the cross cut tests were carried out on the coatings cured for 40 s-60 s. The coatings obtained are also with transmittance in the range of 85 %-99 %, adhesive properties to the slides can reach grade 0, water absorption in the range of 0.23 wt%-0.60 wt%, exposed to UV (7.8 mw.cm(-2)) at ambient for 180 min without turn yellow. The transparent silicone modified polyurethane-acrylate coatings prepared are promising for widespread applications in the information technology devices and automobile, etc.