LIQUID CRYSTAL POLYESTER FIBER AND METHOD FOR PRODUCING THE SAME

PROBLEM TO BE SOLVED: To provide a liquid crystal polyester fiber having excellent strength and modulus, and exhibiting excellent compression resistance in the vertical direction to the fiber axis.SOLUTION: The liquid crystal polyester fiber comprises a liquid crystal polyester constituted of 38-74 mol% structural unit derived from 2-hydroxy-6-naphthoic acid, 13-31 mol% structural unit derived from 4,4'-dihydroxybiphenyl, and 13-31 mol% structural unit derived from 2,6-naphthalenedicarboxylic acid, and satisfies the following conditions 1-3 at the same time: condition 1. the value (ΔHm1/ΔHm2) of quotient obtained by dividing the quantity (ΔHm1) of the heat of fusion at the endothermic peak (Tm1) observed when carrying out a differential calorie measurement in a temperature-raising condition of 20°C/min from 50°C, by the quantity (ΔHm2) of the heat of fusion at the endothermic peak (Tm2) observed when raising the temperature again after once having cooled the sample after observing the Tm1 is ≥2.0; condition 2. the half-width of the peak at the Tm1 is