Influence of different photoinitiatiors in the UV-LED curing of polyester acrylated varnishes

The search for environmentally friendly coatings has gained relevance in recent years. To circumvent the use of volatile organic compounds, ultraviolet light curing has attracted considerable attention, especially with the recent advances in light emitting diodes (LEDs), wherein one of the most important components is the photoinitiator. Since UV-LED curing has a narrower wavelength spectrum than regular UV curing, the choice of photoinitiator is crucial. In this study, the influence of six types of photoinitiators in the curing of polyester acrylate varnishes was investigated. The post-curing optical, thermal, mechanical, dynamic mechanical, and morphological properties of these varnishes were examined. All varnishes were completely cured, and the resins cured with LED 1711 and diphenyl (acyl) phosphine oxide exhibited the lowest post-curing photoyellowing. Satisfactory mechanical and dynamic mechanical properties were achieved for all samples. However, due to the thickness of the films, more studies are needed to optimize the surface roughness of the varnishes.