Morphologies and droplet sizes of alkyd–acrylic hybrids with high solids content

Alkyd–acrylic hybrids having final solids content of 75–80% were prepared by dropping alkyd resin into an acrylic dispersion. The resulting suspo emulsion structures and the alkyd droplet sizes in the hybrids were dependent on the preparation procedure as well as the interfacial tension between the two liquid phases, σ12, the shear rate, γ ˙ , the latex/alkyd ratio and the viscosity ratio, p, between the viscosity of the dispersed phase, ηd, and the viscosity of the matrix, ηm. σ12 was varied by changing the surfactant concentration and pH of the hybrids, ηd was varied by changing the viscosity of the alkyd phase but was also affected by variations in the pH, and finally the shear stress was varied by varying the solids content and the amount of latex in the hybrid systems. Parameters that effected the ratio, p, were also studied separately and in combination, and by varying parameters such as the presence of latex particles, alkyd viscosity and solids content, the effect of p on the alkyd droplet size was determined. ent liquid structures were obtained depending on how the surfactant was added to the system. When surfactant was added to the latex prior to the addition of the alkyd, an O/W emulsion was formed. However, if the surfactant was added to the alkyd prior to the addition of the alkyd to the latex, a multi-emulsion (W/O/W) of alkyd was formed, which was also observed when the hybrids were prepared at a high pH. The structures obtained were stable over time and remained unchanged even after ageing for 1 year at room temperature.