A new UV-curable powder coating based on a α,ω-unsaturated copolyamide 6/11/12

This work deals with the elaboration of a new UV-curable powder coating for heat sensitive substrates. This powder contains a α,ω-unsaturated copolyamide 6/11/12 having a melting point of 107 °C and 4% (w/w) of photoinitiator. After description of the copolyamide synthesis, the photochemical reaction was investigated in the presence of two Norrish II photoinitiators (benzophenone and 4-phenylbenzophenone). The influence of the photocrosslinking on the crystallinity of the ultimate materials was studied. It was shown that the photochemical reaction can take place even when the sample is at the solid state and that its yield increases with the temperature and the time of irradiation. Lastly, the influence of the crystallinity/crosslinking ratio was characterized by measuring the swelling of the UV-cured materials into different solvents.