Study on photostabilization in situ of reactive hindered amine light stabilizers applied to UV-curable coatings

Four monomeric reactive hindered piperidinol derivatives, such as 4-methacryloyl-1,2,2,6,6-pentamethyl-piperidinyl (MPMP), 4-acryloyl-1,2,2,6,6-pentamethyl-piperidinyl (APMP), 4-methacryloyl-2,2,6,6-tetramethyl-piperidinyl (MTMP), and 4-acryloyl-2,2,6,6-tetramethyl-piperidinyl (ATMP), were applied as reactive hindered amine light stabilizers (r-HALS) in UV-curable coatings. The effect of r-HALS on the UV-curing kinetics of the UV-curable coatings of different monomers or oligomers has been previously investigated. Polymer coatings were prepared by means of UV-curing technology; experiments were conducted manually on photoaging indoors, monitoring the Yellowness Index (YI) in the photooxidation process, and adding r-HALS. The experiments were done to review its photoprotection effect on UV-cured coatings. Subsequently, they were compared with typical commercial HALS through parallel experiments to investigate the photooxidation aging mechanism of polymer coatings, and the effective concentration was determined from the changing circumstances of YI, thus comparing their differences in photostabilizing effect in situ of the polymer coatings.