Low Extractable Photoinitiators Based on Thiol Functionallzed Benzophenones and Thioxanthones

摘要

Previously described non or low extractable photoinitiators based upon monomer-photo initiators including maleimides, vinyl acrylates, vinyl cinnamate, divinyl esters, and thiols are compared. These monomer-photoinitiators participate in the free-radical polymerization of acrylates that they initiate, and in the process are bleached and incorporated into the final network. All have noted drawbacks to their use including toxicity, efficiency and cost. Recently, in our lab other photoinitiators based upon thioxanthone and benzophenone derivatives with thiol functional groups attached to the para position of the phenyl rings via sulfides have also been synthesized and evaluated. These latter types of photoinitiators are as efficient as typical thioxanthone and benzophenone photoinitiators in the presence of amine cosynergists, but having reactive thiols they also are incorporated into the acrylate network via chemical attachment.