Armin Wadle

Calculation of optimum emulsifier mixtures for phase inversion emulsification

The phase inversion emulsification is a convenient method of preparing fine‐disperse and long‐term stable oil‐in‐water emulsions, which are stabilized with nonionic emulsifiers. On the basis of EACN‐values (equivalent alkane carbon numbers) the calculation of phase inversion in concentrates (CAPICO) is possible, which yields emulsifier and oil mixing ratios corresponding to a given phase inversion temperature (PIT). The CAPICO‐method is illustrated for the example of a cosmetic oil‐in‐water lotion containing an oil mixture, glyceryl monostearate and a fatty alcohol ethoxylate. Of special interest is the influence of silicone oils on the PIT. At a constant emulsifier oil ratio the complete phase behaviour of this emulsion system is represented in a temperature/water content graph. Optimum emulsification results are obtained if during PIT emulsification a microemulsion or a lamellar phase is passed. The emulsions were characterized by particle sizing, and emulsion stability against sedimentation was evaluated by ultrasonic velocity changes. A fine‐disperse and long‐term stable oil‐in‐water emulsion was prepared by a time and energy‐saving two‐step hot‐cold process.