PRODUCTION OF FINE DISPERSE AND LONG-TERM STABLE OIL-IN-WATER EMULSIONS BY THE PHASE INVERSION TEMPERATURE METHOD

Oil-in-water emulsions stabilized with nonionic emulsifiers can invert to water-in-oil emulsions when the temperature increases. At the phase inversion the hydrophilic and lipophilic properties of the emulsifier are balanced. Based on phase diagrams for emulsion systems containing mineral oil, water and the technical emulsifier tetraethyleneglycol tetradecyl ether as well as a mixed emulsifier of cetyl/stearyl alcohol and dodecaethyleneglycol cetyl/stearyl ether, the relationship between phase inversion, formation of a microemulsion phase and attainment of minimum interfacial tensions between oil and aqueous phase is explained. Fine disperse and long-time stable oil-in-water emulsions are obtained if the emulsion is heated up and cooled down above the temperature range of the phase inversion during the production process. With this phase inversion method, the fine dispersity of the emulsion only depends to a small extent on process parameters like mechanical energy input or cooling rate. Furthermore, with the PIT method, low-viscous, fine disperse emulsion concentrates were produced which can be diluted at will without losing their fine dispersity and long-term stability.