Curing behavior of a UV-curable inkjet ink: Distinction between surface-cure and deep-cure performance

Safety requirements and the need of low-migration UV inks have received increasing attention in the packaging industry. Crucial for the development and design of low-migration UV inkjet inks for migration-sensitive applications is the polymerization degree. In this study, curing-behavior of a black, high purity packaging ink (HPP-ink) was monitored using ATR-FTIR spectroscopy. UV irradiation of HPP-ink led to changes in specific absorption bands of the FTIR spectra due to crosslinking reaction of double bonds. Changes in absorptions bands at 1,408 and 1,321 cm(-1)permitted the determination of C(sic)C conversion of acrylic and vinyl double bond, independently of one another. In addition, a method was developed which allows the investigation of surface-cure and deep-cure behavior, separately.