Patent ID: 7910207

Claim:
A fine fiber bundle obtained from an islands-in-sea type composite fiber comprising a sea part comprising an easily-soluble polymer and a plurality of 100 or more island parts comprising a hardly-soluble polymer, in a cross-sectional profile of which each of the island parts has a thickness in the range of from 10 to 1,000 nm and the intervals between the island parts adjacent to each other are 500 nm or less, by dissolving and removing the sea part from the composite fiber, and having: a number of individual fine fibers of 100 or more per bundle, a thickness of the individual fine fibers in the range of from 10 to 1,000 nm, a tensile strength in the range of from 1.0 to 6.0 cN/dtex, and an elongation at break in the range of from 15 to 60%.