Provided is an abrasion-resistant polyester fiber, which has, in particular, a strength within a specific range, an elongation within a specific range and a Young's modulus falling within a specific range in a specific elongation range on a stress-strain curve, to improve the abrasion resistance of a woven/knitted product for clothing using, in particular, a fine size polyester fiber. The polyester fiber is an abrasion-resistant polyester fiber comprising ethylene terephthalate as a main repeating unit, characterized by satisfying the following requirements: (1) the fineness being from 8 dtex to 200 dtex inclusive; (2) the single yarn fineness being from 1.0 dtex to 4.0 dtex inclusive; (3) the breaking strength being 3.5 cN/dtex or greater; (4) the breaking elongation being from 20% to 50% inclusive; and (5) the minimum differential Young's modulus being 20 cN/dtex or less in an elongation range of from 2% to 5% inclusive on a stress-strain curve of the fiber.

A method of manufacturing multi-ply separable textured yarn, the method comprising, passing a multi-ply separable interlaced filament yarn through a texturizing unit to form a multi-ply separable draw textured yarn, wherein the multi-ply separable interlaced filament yarn is separable in to at least two separable interlaced filament yarn, wherein the interlacing of the filaments within each separable interlaced filament yarn is retained during further processing of the yarn to fabric and in the fabric.

A method of manufacturing multi-ply separable textured yarn, the method comprising, passing a multi-ply separable interlaced filament yarn through a texturizing unit to form a multi-ply separable draw textured yarn, wherein the multi-ply separable interlaced filament yarn is separable in to at least two separable interlaced filament yarn, wherein the interlacing 10 of the filaments within each separable interlaced filament yarn is retained during further processing of the yarn to fabric and in the fabric.