Synergistic Enhancement of Long-Afterglow Road Marking Coatings Using Surface-Modified SrAl2O4:Eu2+,Dy3+ Luminescent Powder and Glass Beads

Long-afterglow self-luminous road marking coatings are promising for improving nighttime visibility, but their application is restricted by the poor water stability of SrAl2O4:Eu2+,Dy3+ phosphors and weak interfacial compatibility with polymer matrices. In this study, SrAl2O4:Eu2+,Dy3+ phosphor was modified using a silane coupling agent and incorporated into a two-component methyl methacrylate coating. The modification mechanism and durability performance were investigated through SEM, FTIR, fluorescence spectroscopy, afterglow decay, abrasion, water immersion, and UV aging tests. Results showed that silane modification formed an organic protective layer on the phosphor surface, improving interfacial bonding and water stability while maintaining the intrinsic luminescent properties. Modified and unmodified phosphors exhibited similar excitation and emission peaks at approximately 360 and 520 nm, respectively, with comparable two-stage afterglow decay behavior. The coating containing modified phosphor and glass beads showed the best performance, with an abrasion loss of 27.9 mg and a skid resistance value of 69 BPN after 1000 abrasion cycles. After 7 days of water immersion and UV aging, the coating maintained good mechanical and luminescent stability. This study demonstrates that the synergistic reinforcement of modified phosphor and glass beads is an effective strategy for durable self-luminous road markings.