Patent ID: 6838173

Claim:
A polyester fiber comprising a polyester having a diethylene glycol content of 2 percent by weight or less; and a carboxyl end group content in the range of 10 to 50 equivalent/ton, the polyester fiber having a hygroscopic parameter ΔMR of 1% or more and containing 1 to 20 percent by weight of silica-based inorganic particles, wherein the silica-based inorganic particles satisfy the following conditions (A) to (C): (A) the micropore volume “V” is 0.4 ml/g or more, and the following relationship is satisfied: 100 ≦S/V <1,500 wherein S means the specific surface area S (m 2 /g) of the inorganic particles; (B) the average particle diameter D is in the range of 0.01 to 10 μm; and (C) the hygroscopic parameter ΔMR is 7% or more.