Another is the unique properties of UV-cured products that are providing lasting value to their users and continued growth of the process. Color stability, greater opacity and sharper graphics are only some of the benefits obtained with UV-curable inks. Instead, they are converted, or cured, to a dry solid state through a chemical process called polymerization. This cycle begins when the ink, coating or adhesive is exposed to ultraviolet light of sufficient energy to initiate the following chemical reaction. Upon exposure to the ultraviolet light, the photoinitiators contained within UV inks and coatings are transformed into free radicals.
Free radicals are simply groups of atoms with an excess of electrons.
The oligomers and monomers simply become chained together, binding the pigments and other additives in the polymer chain. In the case of the less commonly used cationic chemistry, the photoinitiators are converted into acids that act as catalysts to cross-link an epoxy system. After this bonding occurs, the UV ink or coating is then inherently stable. Since there are no solvents to evaporate, color consistency and print sharpness are increased. All rights reserved.