Zero VOC sunlight curable coatings

Curing of one-pack epoxy coatings by exposure to visible light for a few ho urs would be a useful innovation for architectural, industrial, and mainten ance (AIM) coatings as well as for any large objects that would be difficul t to heat but easy to shine a light on. Zero VOC, low viscosity, sunlight curable clearcoats can be formulated with cycloaliphatic epoxy compounds as well as aromatic glycidyl ethers. Cure i s achieved with a cationic photoinitiator that generates a strong acid when exposed to sunlight for a couple of hours. The clearcoats had good hardnes s, adhesion,and solvent resistance. No cure was achieved with incandescent light or with fluorescent light, which contains only 0.1% UV light as compa red to sunlight that has 5% UV light. This work indicates that zero VOC one pack clearcoat epoxy formulations for AIM applications and large objects c ould be cured by light racks that generate the spectrum of sunlight.