| abstract |
Provided is a fine fiber structure that will not suffer wrinkling or deformation of shape due to breaking or bending even if passed through a small-diameter roller or guide or wound about a wind-up bobbin during manufacture or processing steps, that simultaneously has excellent ion permeability, short circuit resistance, and the like, and that is suitable as a separator or insulating material for a battery, electric double layer capacitor, electric condenser, or the like. A fine fiber structure comprising a porous fine fiber layer made of polymeric fine fibers having a mean diameter of 50 to 3,000 nm, the fine fiber structure being characterized in that the bending resistance of the fine fiber structure according to a 45° cantilever method is 100 mm or less, and the mean pore size, thickness, porosity, basis weight, Frazier air permeability, and Macmillan number in the porous fine fiber layer are 0.01 to 15 μm, 0.0025 to 0.3 mm, 20 to 90%, 1 to 90 g/m 2 , less than 46 m 3 /min/m 2 , and 2 to 15, respectively. |