Preparation of zinc methacrylate-methylmethacrylate-butyl acrylate emulsions and their application in exterior paints

•Polymer emulsions containing zinc methacrylate and nano ZnO were synthesized.•Opaque and transparent colored exterior paints were prepared from emulsions.•Polymer and paint films were subjected to UV-condensation accelerated weathering.•Zinc methacrylate crosslinking prevented blistering of polymer films and paints.•Crosslinking also improved gloss and color stability of polymer films and paints. Semi-batch emulsion polymerization of methyl methacrylate-butyl acrylate- methacrylic acid monomers were carried out with the addition of nano ZnO to the monomer feed, to obtain a binder for exterior architectural paints. Nano ZnO reacted spontaneously with acid groups to form zinc methacrylate or dimethacrylate which participated in crosslinking reactions. The amount of nano ZnO added was increased up to the equivalence point and in several cases exceeded for unmodified, hydrophilic or hydrophobic silane modified nano zinc oxides. The emulsions and clear polymer films obtained from them were characterized with conventional methods. FTIR and UV/Vis spectra confirmed the transformation of nano zinc oxide up to the equivalence point. The emulsions were used for preparing of opaque and transparent colored paints which were tested with UV exposure-condensation accelerated weathering along with clear polymer films. The color parameter, gloss and water contact angle changes were determined for every 250 h up to 1000 h. Optical microscopy and for some cases AFM, FTIR and FESEM were also used for further characterizations. Presence of zinc methacrylate crosslinking and in some cases, additional presence of nano ZnO, provided blistering prevention and improvement of gloss and color stability.