High solids waterborne hybrid systems. Effect of surfactant concentration and pH on droplet size and morphology

Abstract

Hybrid systems have been made by taking an acrylic latex dispersion and slowly dropping an alkyd resin into the dispersion while stirring to achieve a solid content of 75–80%. The particle size distributions of alkyd droplets were studied with a laser diffraction instrument and the structure of the hybrid system in the liquid state has been studied by light microscopy. The hybrid system was defined as a “suspoemulsion”, which are mixtures of suspensions and emulsions. In the present hybrid system the alkyd is present as an oil-in-water (O/W) emulsion and the suspension is represented by the acrylic latex. When the way of adding surfactant and the added amount of surfactant were changed, it was found that addition of surfactant to the system decreases alkyd droplet size more effectively if the surfactant is present in the acrylic latex. If the surfactant was added to the latex prior to the addition of alkyd it resulted in the formation of O/W emulsions. On the other hand, in the case of addition of surfactant to the alkyd before dropping it into the latex, water-in-oil-in-water (W/O/W) double emulsions in respect of the alkyd were observed, and in order to obtain the same decrease in alkyd droplet size as in the experiments where surfactant was added to the latex, a higher surfactant concentration was needed.

Acknowledgement We are thankful for the financial support from “The Research school for industry: ’The Building and its Indoor Environment” organized by “The foundation for knowledge- and competence development (KK-foundation)”, Celanese Emulsions Norden AB, Perstorp, Sweden and Akzo Nobel Decorative Coatings AB, Malmö, Sweden.

This work was originally presented at the conference on Polymer Colloids, Irsee, Germany July 02