International. Researchers at Tianjin University, School of Chemical Engineering and Technology, have studied the molecular structure of UV-curable aqueous polyurethane acrylate emulsions (UV-WPUA). The research showed in particular three outstanding properties.
Finished polyurethane acrylate oligomer with multiple unsaturated bonds was prepared using isophorone diisocyanate (IPDI), methylene diphenyl diisocyanate (MDI) and polyols as monomers, using 2,2-dimethylpropionic acid (DMPA) as a hydrophilic chain extender, along with pentaerythritol PETA triacrylate) as an end-capper.
The emulsion composed of UV-curable aqueous polyurethane acrylate (UV-WPUA) was obtained by mixing the PUA oligomer with a certain content of reactive diluents and then dispersing the mixture in water.
The molecular structure of polyurethane prepolymer, PUA oligomer and UV-cured polymer was investigated using FT-IR. The influence of the composition and content of the diluents and the final layer on the UV-WPUA properties was studied, including emulsion stability, thermal property, water resistance, adhesion, hardness and brightness of the polymer film.
The results showed that the WPUA emulsion has excellent stability and the UV-cured film exhibits good hardness and remarkable water resistance when PETA is used as an end-capper and the final coverage radius of the polyurethane prepolymer is 70% and DPHA/DPGDA (Mass 1:1) used as a diluent.
Source: Applied Polymer Science.
