Breathable Sheet

Kao’s disposable diapers use a breathable sheet for the outer surface, which reduces stuffiness by allowing water vapor to pass through while retaining liquid. Though seemingly no more than a flat and smooth film, the sheet is actually water-repellent and has thousands of micro pores that measure about 0.2 μm in diameter. These pores are no more than one five-hundredth the size of a water droplet (100 μm or larger), but 500 times larger than water vapor particles (0.0004 μm or smaller). Thanks to this pore size, water droplets become trapped inside the diaper, while only water vapor is able to pass through. In our efforts to improve performance by optimizing the number and size of these pores, Kao has developed a high-performance sheet that provides both a high level of fluid locking performance and high moisture permeability, allowing it to be utilized in disposable diapers for babies as well as adults.