Ultraviolet (UV) coatings are cured by UV light. They contain almost no solvents that may evaporate during the curing process. Instead, the UV curing process is achieved through polymerization—a crosslinking reaction of the coating constituents. The photoinitiators contained in the coating play a decisive role and are prerequisite to the process. They absorb the photons of the UV light and convert their energy into chemical chain reactions until complete crosslinking has occurred. The result is the curing of the coating.
Medium-pressure lamps have been used successfully for many years for UV polymerization. The advantage of their broadband emission spectrum is that photoinitiators can be used in a large variety of applications (see Figure 1). Their high energy enables high process speeds, but this often uses a lot of energy as well.