Abstract: A hollow polyester long fiber has a cross-sectional hollowness ranging from 20.0% to 45.0%, the long fiber in natural state being of a three-dimensionally crimped shape, and the radius of curvature of the crimped shape being 10.0 mm to 50.0 mm. The fluffy processed tows obtained by processing the hollow polyester long fiber have high fluffiness.

Abstract: Provided are: a polyester composition which balances structural stability with dyeability of disperse dyes at less than 100° C. when made into fibers; and a method for producing said polyester composition. This polyester composition having dyeability at atmospheric pressure: contains components comprising dicarboxylic acid, a diol and polyethylene glycol, with the main repeating components comprising ethylene terephthalate; and is characterized in that 5-10 mol % of the total diol component has three carbon chains with side chains, the content of polyethylene glycol in the polyester composition is 2-4 wt %, and the content of cyclic dimers is not more than 0.35 wt %.

Abstract: A polyester monofilament package is formed by reeling a polyester monofilament comprising polyethylene terephthalate and satisfies all of the following requirements (a) to (d): (a) the coefficient of dynamic friction between yarns of the polyester monofilament being 0.13 ?d or less; (b) the package end being in a tapered shape with a taper angle (0) of 75° or less; (c) the variation gradient in unreeling tension (AT) being 0.02 cN/dtex-m or less; and (d) in a part of a reeling thickness of 1 mm in the inner layer of the package, the variation in contraction stress of the polyester monofilament being 3.0 cN/dtex or less.

Abstract: A polyester monofilament package is formed by reeling a polyester monofilament comprising polyethylene terephthalate and satisfies all of the following requirements (a) to (d): (a) the coefficient of dynamic friction between yarns of the polyester monofilament being 0.13 ?d or less; (b) the package end being in a tapered shape with a taper angle (0) of 75° or less; (c) the variation gradient in unreeling tension (AT) being 0.02 cN/dtex-m or less; and (d) in a part of a reeling thickness of 1 mm in the inner layer of the package, the variation in contraction stress of the polyester monofilament being 3.0 cN/dtex or less.