Study of low energy emulsification of alkyl ketene dimer related to the phase behavior of the system

The main objective of this work was to improve the physicochemical understanding of the emulsification of a hydrophobizing agent for paper, alkyl ketene dimer (AKD), by relating the equilibrium phase behavior to the emulsification process. Emulsions have been formed with a system containing water, a surfactant mixture of alcohol ethoxylate and calcium dodecylbenzene sulphonate, dodecanol and AKD. The phase behavior was determined at a constant temperature of 60 °C because the emulsification needs to be performed at this temperature in order for AKD to be in melted stage. The study is based on a formulation for emulsification with low energy input, which has been published earlier (J. Disper. Sci. Technol. 22 (2001) 569). The result of the low energy emulsification when adding water to a mixture of AKD and surfactant was compared with the addition of AKD to a water and surfactant mixture. Emulsions with an average droplet size of less than 300 nm were obtained by adding water to the AKD-surfactant mixture. It was found that the method of emulsification, as well as the types of liquid crystalline phases involved in the emulsification process, is important. This is in accordance with a previous work by Forgiarini et al. (Langmuir 17 (2001) 2076).