Synthesis of water-soluble urethane acrylate anionomers and their ultra-violet coating properties

Water-soluble and ultraviolet (UV)-curable urethane acrylate anionomers con taining dimethylolpropionic acid (DMPA) were synthesized with varying molec ular weight of soft segment and degree of neutralization. The ion group inc orporated was confirmed by H-1-NMR and C-13-NMR spectra. In viscosity measu rements, the enhancement of viscosity was achieved with increasing of ionic strength or pH of the solution. However, when the molecular weight of soft segment was high, the viscosity little changed for given parameters. This indicates that the strong hydrophobic interaction caused by the long soft s egment made the anionomer chain aggregate. The UV coating properties of ure thane acrylate anionomer films were depended on the molecular weight of sof t segment and the degree of neutralization. For the films of high ion conte nt and low molecular weight of soft segment, the tensile strength had a ten dency toward increasing, on the contrary, for the films of low ion content and high molecular weight of soft segment, the tensile strength displayed r everse tendency. However, compared with general urethane acrylate films, ov erall coating properties were significantly improved. This was believed tha t the ionic groups acted as reinforcing filler by means of the phase separa tion from the crosslinked urethane acrylate network. (C) 1999 Kluwer Academ ic Publishers.