Tertiaryamine linked and polysiloxane modified polyurethane acrylate oligomer and its effects of migration/co-initiation on photo-curable inkjet printing

Abstract To resolve the issue of handle-softness inadequacy in current polyurethane acrylate (PUA) oligomers for photo-curable inkjet printing on flexible substrates, and to improve the ability of anti-oxygen inhibition and photo-initiation efficiency of the tertiaryamine macromolecular co-initiator, the hydroxyl-terminated polydimethylsiloxane co-polymerized with tertiaryamine modified polyurethane acrylate (SiPUA) oligomer was designed and synthesized by using a sequential polymerization process. The structure of the SiPUA oligomer was confirmed by titration test and FTIR analysis, and the properties of the oligomers and the resultant photo-cured films were characterized by a range of analytical and measurement techniques. During the photo-curing process, the polysiloxane chain segment moved to the surface of the photo-cured SiPUA-HEA film due to the similar "surfactant critical micelle effect", forming an interconnected microphase structure of 50-70 μm thickness enriched with siloxane. The tertiaryamine group linked with polysiloxane segment was also enriched in the surface accordingly due to the migration of polysiloxane, thus improving the ability of anti-oxygen inhibition and photo-initiation efficiency. Benefiting from the both polysiloxane and tertiaryamine enriched surface and the retained PUA-HEA framework bulk in the cured film, a soft, flexible and strong photo-cured film with water-resistance and high photo-initiating efficiency was obtained.