Patent ID: 8501642

Claim:
A nanofiber synthetic paper comprising disarranged nanofibers made of a thermoplastic polymer by melt spinning a polymer alloy into polymer alloy fibers comprising a sea component and island components and then removing the sea component to form the disarranged nanofibers from the island components in a homogeneously dispersed arrangement, and of 1 to 500 nm in the number average single fiber diameter and 70% or more in the sum Pa of single fiber ratios, wherein the freeness of the disarranged nanofibers is 350 or less, the fiber length of nanofibers in the nanofiber synthetic paper is 0.1 to 20 mm, the ratio (L/D) of the fiber length L (mm) to the number average single fiber diameter D (mm) is 3,000 to 50,000, and the index Pb of extremal coefficient of the single fiber diameters expressing the rate of the fibers failing within a range of plus and minus 15 nm from the number average single fiber diameter is 60% or more.