Tetrafunctional acrylates based on β-hydroxy alkyl amides as crosslinkers for UV curable coatings

Ultraviolet (UV) curable coating formulations were prepared from novel crosslinking acrylates synthesized from β-hydroxy alkyl amides. Variations were done with respect to the nature of the monomer backbone by introducing aliphatic, aromatic and cycloaliphatic structures in between the amide groups. The synthesized multifunctional alcohols and acrylates were subjected to IR and NMR analysis for structure confirmation. The acrylates were dissolved in chloroform and the UV–vis spectrum was recorded to substantiate the presence of carbonyl group conjugated to the vinyl group. The new acrylates were added to basic formulation and exposed to UV radiation to get transparent films. The dynamic mechanical properties of the films cast from the formulations were assessed and studies on the effect of the synthesized crosslinking acrylate content and their nature on the viscoelastic properties of the films were carried out. Improvements in glass transition temperature (Tg) were observed with increasing percentage of crosslinker. Acrylates based on aromatic acid amides showed higher Tg than aliphatic acid amides. The storage modulus (E′) increased up to 10% and further increases in the crosslinker percentage led to a decrease in the modulus. The rubbery modulus depended on percentage of crosslinker and not on crosslinker structure.