Development of a New Evaluation Method for O/W Cleansing Creams Involving Phase Inversion during Use

Abstract

It is known that commercial cleansing creams undergo a phase inversion from O/W (Oil in water) to W/O (Water in oil) during use, and that the viscosity of the creams decreases, resulting in a marked change in the texture. We attempted to establish a new measurement method to evaluate the change in the texture of cleansing creams caused by the phase inversion on a rheometer. As a result, we found that viscosity changes corresponding to usability could be observed by performing a new measurement (phase inversion mode) in which the sample was measured while being applied by shearing for 1 min, then the upper plate was raised and exposed to dry air for 1 min, and the measurement was repeated 10 times with the plate returned to its original position again. The results of the impedance and the small-angle light scattering (SALS) measured synchronously with the rheological measurements revealed that phase inversion from O/W to W/O during applied shearing.