i-Line sensitive photoacid generators for UV curing

UV curing systems based on cationic processes are very significant because the systems have several advantages compared to the radical process. Photoacid generator (PAG) is essential for the cationic UV curing system including epoxides and vinyl ethers. Although many types of PAG have been developed, most of them are not sensitive to i-line (365 nm) from a high-pressure mercury lamp. In this study, non-ionic PAG that is thermally stable and highly sensitive to i-line was designed and synthesized. Imino sulfonate and N-hydroxyimide sulfonate compounds were prepared as PAG. Fluorenone, thioxanthone, and thianthrene skeletons were used as chromophores for PAG. Furthermore, photochemistry of the PAG and its applications to photocrosslinking systems based on epoxy-containing polymers were studied.