Printing inks cured with ultraviolet light.
These inks contain no volatile substances, but instead, in addition to color pigments, individual molecules and short molecular chains that can link to form polymers and so-called photo-initiators.
The latter decompose when exposed to UV light and form highly reactive fragments.
These radicals trigger a polymerization process in which stable, three-dimensional network structures are formed. UV inks are primarily used to print non-absorbent materials, such as metal (sheet metal) and plastic, but also high-quality paper boards and labels.