Dual-Curable Acrylic Pressure-Sensitive Adhesives Based on UV and Thermal Processes

Several dual-curable acrylic pressure-sensitive adhesives (PSA) were synthesized by the radical polymerization of acrylic monomers containing benzophenone, hydroxyl, and alkyl groups. The optimum extent of UV-induced cure was determined by varying the content of the benzophenone groups (the photoinitiator) from 0.5 to 1.5 wt%. The weight average molecular weight of the polymers obtained ranged from 300,000 to 700,000 amu. The coated pressure-sensitive adhesives were cured either by short UV exposure to induce the grafting of acrylic polymers, or by heating for 6 hat $60^{\circ}C$ to promote the reactions between the polyisocyanates and hydroxyl groups. The dual-curing behavior was determined by monitoring both processes quantitatively by infrared spectroscopy. The developed dual-curable acrylic pressure-sensitive adhesives were found to compensate for the limitations in UV-induced curing of thick coatings.