Abstract: A polyamide hollow and/or non-circular fiber containing a metal salt of a saturated fatty acid having at least 10 carbon atoms, wherein the amount (X) of a terminal carboxyl group is not larger than 60 gram equivalent per 1,000 kg of the polyamide and the amount (Y) (in parts by weight per 100 parts by weight of the polyamide) of the metal salt of a saturated fatty acid satisfies the following formula:Y.gtoreq.0.00871X-0.13wherein X is the amount of the terminal carboxyl group in gram equivalent/1,000 kg of the polyamide.

Abstract: A liquid pigment composition for master-coloring polyamides is described, which is comprised of a pigment and a pigment dispersant composed of a polymeric material selected from liquid polyesters and a liquid polyether esters, each having a hydroxyl value of 30 to 120 mg.KOH/g. The amount of the pigment dispersant is usually 30 to 3,000 parts by weight per 100 parts by weight of the pigment. A master-colored polyamide yarn also is described which contains, based on the weight of the yarn, 0.01 to 2% by weight of a pigment ingredient and up to 6% by weight of the above-mentioned pigment dispersant.

Abstract: Disclosed is a polyamide multifilament yarn comprising a plurality of polycapramide multifilaments and having a high softness, a mild touch, a level-dyeing property and an excellent colorfastness to washing and laundering. The individual filaments in this yarn are characterized by a birefringence of 0.045 or more, a denier of 0.8 or less and a ratio of the X-ray diffraction intensity I.sub.23 at an angle (2.theta.) of 23.2 degrees to the X-ray diffraction intensity I.sub.21 at a peak formed at an angle (2.theta.) of approximately 21 degrees which ranges from 0.50 to 1.00. A process for producing the above-mentioned polyamide yarn is also disclosed.