Ink-Step Adaptability and Reliability of Maleimide-Functionalized UV-Curable Optically Clear Adhesives

Optically clear pressure-sensitive adhesives (OCAs, semi-solid = film-like) or UV-curable adhesives (optically clear resins, OCRs, liquid to solid) have been used for the optical bonding of mobile displays in order to enhance their outdoor visibility. These materials have to provide good ink-step coverage and reliability while having the limitation of mobile device designs becoming thinner and thinner. In this study, UV-curable pressure-sensitive adhesives (UV OCAs, semi-solid to solid) were synthesized and applied to the optical bonding of an OLED mobile display. It is a merging technology that combines OCAs and OCRs to overcome the drawbacks of both and to combine their advantages. The ink-steps adaptability of the UV OCA on a window black matrix was improved by a lamination process with low storage modulus (G') before UV curing. Reliability was also improved by post UV curing, after the lamination process. Also, a maleimide-functionalized acrylate was incorporated into chains of pre-polymer for improved adhesion strength between the UV OCA and the adherend.