In multi-laid nonwoven, the permeability, that has been widely used as an index for fluid transmissivity was investigated considering the structural factors such as the porosity, the pore size and its distribution, and the number of constituent layers. For the experiment, spun-bonded nonwovens with various fiber fineness, web densities, and porosities were used. In a single-layered structure, as the fiber thickness increased, the pore size increased, that resulted in an increase in fluid permeability. In the multi-layered structure, as the number of the constituent layers increased, the effective pore size decreased resulting in a decrease in the permeability. The experimental results could be clearly rationalized from the simulation based on the network model developed in the research.
