Lotion Distribution in Wet Wipes Investigated by Pore Network Simulation and X-ray Micro Tomography

Wet wipes are commercial products made of a fibrous substrate impregnated with lotion. The overall cleaning power, wetness perception, and opacity of wet wipes depend on the lotion distribution inside the substrate. In this work, a lab-scale X-ray microtomograph is used to acquire three-dimensional digital images of dry and wet wipe samples, from which the average structural properties of the fibrous substrate as well as the lotion distribution are obtained. In addition, a pore network model is developed to simulate the lotion distribution inside a wet wipe. The void space of the substrate is approximated by three layers of pore networks. Each layer has distinct structural properties in order to reflect the structural heterogeneity of the fibrous substrates in the thickness direction. A qualitatively good agreement of the pore network simulation results with the measured lotion distributions is observed. The influence of the equilibrium contact angle and viscosity on the lotion distribution is also investigated by pore network simulations.