Modified epoxy acrylate resin for photocurable temporary protective coatings

A series of UV-curable oligomers based on bisphenol-F epoxy resin were synthesized via end-capping of acrylic acid (AA) and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) in different ratios. Along with the increase of AMPS content, viscosities of modified resins reduced obviously. Integrated performance of cured films was also evaluated. Water swelling and contact angle tests indicated that the hydrophilicity was enhanced by the incorporation of sulfonate and amide groups into the coatings. Thermal degradation behaviors showed that the char residue, as well the glass transition temperature of the cured films was increased with the rising AMPS proportion, though the initial decomposition temperature declined. Moreover, doping of plentiful AMPS caused a remarkable enhancement in elongation at break, which was ascribed to greater flexibility of polymer chains and reduced density of crosslinking structure. Cured films with AMPS modified showed strong adhesive strength resulted from strong hydrogen bonding formed between amide sulfonate groups from AMPS and polar surface of glass substrates. For pure AA modified film, it was unaffected in NaOH solution (2   wt%) for 24   h. While for AMPS modified film, the film could be completely removed in several minutes when exposed to alkali solution. The modified epoxy films with these attractive features had prospective applications in temporary protective coatings, which could resist acid and organic solvents while would be easily wiped off from the substrate by soaking in the alkali solution.