Synthesis of TDI-Polyurethane/Polyacrylate Composite Emulsion by Solvent-free Method and Performances of the Latex Film

Abstract

Using the blend of methyl methacrylate (MMA) and butyl acrylate (BA) instead of acetone as a diluent, hydroxyethyl acrylate to terminate the ends of prepolymer, and emulsifying at 85°C, TDI-polyurethane/polyacrylate (TDI-PU/PA) composite emulsion was prepared using toluene diisocyanate (TDI), polypropylene glycol (PPG), 1,6-hexanediol (HDO) and dimethylol propionic acid (DMPA) on the basis of solvent-free method. The chain structure and polymerization progress were confirmed by the analysis of Fourier transform infrared spectroscopy. The desired emulsion could be synthesized when the molar ratio of NCO group in TDI to total OH groups in PPG, DMPA and HDO was 1.18, triethylamine (TEA) and water were added simultaneously during the emulsification, and acrylic monomers were initiated by potassium persulfate at 80°C. It was found that tensile strength, pendulum hardness of the latex film cast from composite emulsion increased and water resistance became better with increasing the content of MMA. Compared with IPDI-PU/PA, TDI-PU/PA composite emulsion not only had a low cost, but also the maximum of titanium pigment added into the emulsion could be increased double, which introduced a distinct increase for the hardness and the covering power of the latex film.