Castor oil based hyperbranched urethane acrylates and their performance as UV-curable coatings

ABSTRACT

Castor oil (CO) based hyperbranched urethane acrylates (HBUAs), namely C10-IH and C20-IH, were synthesized by modifying the hydroxyl groups of first (C10)- and second (C20)-generation of CO-based hyperbranched polyesters with isocyanate-bearing semi-adducts (IPDI-HEA). Herein, the C10 and C20 polyesters were prepared using the renewable CO as a B₃ core molecule and dimethylolpropionic acid as an AB₂ monomer via a pseudo-one-pot condensation procedure. For comparison, a CO-based urethane acrylate (CO-IH) was synthesized by directly modifying the hydroxyl groups of CO with IPDI-HEA. The structure-property relationship of the UV-cured films was investigated in detail. Consequently, the number of terminal urethane acrylates greatly influenced their final properties. The tensile strength of the C20-IH based UV-cured sample could be improved by 129% in comparison with the CO-IH based sample, and its pencil hardness reached up to 7H. Furthermore, the chemical resistance tests and the morphology study proved that the C20-IH based UV-cured coatings exhibited excellent chemical stability and superb microstructure. These improvements can be attributed to the unique oligomer architecture that combined the structural features of hyperbranching, castor oil chains and multiple urethane acrylates.

KEYWORDS:

• UV-curing
• hyperbranched urethane acrylate
• castor oil
• coatings
• chemical resistance

Acknowledgement

This research was financially supported by the Guangdong Academy of Sciences Project (Grant No. 2017GDASCX-0705).

Additional information

Funding

This work was supported by the Guangdong Academy of Sciences Project (Grant No. 2017GDASCX-0705).