Alkyd-acrylic hybrid systems for use as binders in waterborne paints

Alkyd-acrylic hybrids were prepared by polymerizing acrylic monomers in the presence of colloidal alkyd droplets. Polymerization in the presence of alkyd caused a retardation of the polymerization through radical delocalization following radical transfer to the unsaturated groups of the fatty acids in the alkyd. The conversion could be raised to nearly 100% by adjusting the reaction conditions. The application properties of hybrids prepared according to this method could be varied over a broad range by changing either the acrylic part, the alkyd part or their ratio. The homogeneity of the hybrids differed from blends of acrylic dispersions and alkyd emulsions, as was shown by the minimum film formation temperature (MFFT). A good film formation was found without the use of co-solvents. Mixing of alkyd and polyacrylate on microscale, however, could not be determined. In some cases a true synergistic behaviour was observed, where the hybrid had properties superior to those of the acrylic polymer and the alkyd.