Allyl ether-modified unsaturated polyesters for UV/air dual-curable coatings. I: Synthesis and characterization of the oligomers and their cured films

Allyl ether (AE)-modified unsaturated polyester oligomers were synthesized from polyethylene glycol (PEG), maleic anhydride (MAH), and trimethylolpropane mono allyl ether (TMPAE), and characterized by Fourier transform infrared (FTIR) spectra. The UV/air dual-curable coatings were prepared from the oligomers using vinyl ether (VE) as a reactive diluent. FTIR spectra showed that C==C bonds in the coating composition had polymerized partially after cured by UV or air. The investigation of rheological behavior of the dual curable composition suggested that all the systems belonged to pseudoplastic fluid, and the increasing allyloxy content in oligomer resulted in a higher viscosity. Differential scanning calorimetry (DSC) analysis showed that the increasing TMPAE-PEG molar ratio resulted in lower T-g, and all samples had the same glass transition temperature irrespective of the type of curing. The results of TGA for cured films indicated that UV-cured film had better thermal stability than the air-cured one. The air-cured film showed superior pencil hardness, impact strength, and flexibility to the LTV-cured counterpart. However, the air-cured film had poor adhesion and electric resistance properties. (C) 2004 Wiley Periodicals, Inc.