Syntheses and properties of waterborne polyurethane-epoxy adhesives

ASBTRACTIn this study, waterborne polyurethanes (WPUs) with an epoxy group and improved hydrolysis resistance and adhesion were synthesized using a polyester polyol, epoxy resin, 4,4-dicyclohexylmethane diisocyanate, and dimethylol propionic acid (DMPA). The properties of the WPU were evaluated by differential scanning calorimetry, tensile strength, elongation, hardness and adhesion strength. The glass transition temperature (Tg) of the synthesized WPU was approximately −50°C. The Tg and tensile strength increased with increasing epoxy resin content while the elongation decreased. The optimum adhesion was achieved with a polyol:epoxy ratio of 99:1.