Hydroresin dispersions: tailoring morphology of latex particles and films

Abstract

Hydroresin dispersions are a new class of emulsifier free polyacrylate secondary dispersions. They are prepared by the emulsification of self-emulsifying polymer blends in water. The blends typically consist of two polymers, one is a salt group containing copolymer, the other is a hydrophobic polymer without salt groups. The particle diameters can be controlled by the amount of salt group containing polymer and the concentration of salt groups in this polymer. One advantage over conventional secondary dispersions is the fact that they are not only water dilutable but free of organic solvents. Another advantage is the extremely low content of hydrophilic salt groups in the resulting polymer mixture, which leads to very hydrophobic films. The application properties of these aqueous systems are more similar to those of organic polymer solutions than to conventional emulsion polymers. Applications of these surfactant free binders are in areas such as solvent face road marking paints and corrosion protection coatings without active pigments. The technique for the preparation of hydroresin dispersions is also useful for the creation of latex particles with core-shell structures. Two examples are given, which differ in the glass transition temperature of both the cores and the shells. From these dispersions, films with defined morphology can be prepared. A blending of the polymers with hydrophobic low molecular weight compounds, before the emulsification step, is also possible. It can be used for the incorporation of additional functions into the latex particles. As an example, the loading of latexes with a hydrophobic fluorescent dye is given.