Abstract: The present disclosure pertains to: polyamide fibers for an airbag which are characterized in that the fiber size thereof is 200-800 dtex, inclusive, and the stress retention rate thereof when obtained using a prescribed procedure is at least 3.0%; and a method for producing said polyamide fibers for an airbag, the method being characterized in that during the thermosetting step and the relaxing step thereof, the contact time between thread and a roller which is at least 190° C. is at least 30 msec and less than 110 msec, the temperature of the thermosetting roller is 190-205° C., inclusive, the temperature of the relaxing roller is greater than 100° C. and less than 190° C., and the speed ratio of the relaxing roller to the thermosetting roller satisfies this equation: 1.00<relaxing roller speed/thermosetting roller speed<1.10.

Abstract: Provided is an organic fiber doubled-and-twisted yarn cord the twist structure of which is uniform and with which it is possible to reduce weight. A doubled-and-twisted yarn cord comprising an organic fiber characterized in that a total fineness is 5000-15000 dtex inclusive, a coefficient of twisted yarn length difference between untwisting yarns constituting the doubled-and-twisted yarn cord that is obtained by an expression: coefficient of twisted yarn length difference (%)=(maximum value of yarn length difference between untwisting yarns)/(average value of yarn length of untwisting yarns)×100 is 1.5% or less, and breaking strength is 7.0 cN/dtex or greater.

Abstract: Provided is an organic fiber doubled-and-twisted yarn cord the twist structure of which is uniform and with which it is possible to reduce weight. A doubled-and-twisted yarn cord comprising an organic fiber characterized in that a total fineness is 5000-15000 dtex inclusive, a coefficient of twisted yarn length difference between untwisting yarns constituting the doubled-and-twisted yarn cord that is obtained by an expression: coefficient of twisted yarn length difference (%)=(maximum value of yarn length difference between untwisting yarns)/(average value of yarn length of untwisting yarns)×100 is 1.5% or less, and breaking strength is 7.0 cN/dtex or greater.

Abstract: Provided are: a polyamide multifilament fiber comprising a polycondensate of a diamine and a dicarboxylic acid including an alicyclic dicarboxylic acid, and fulfilling conditions (a), (b), and (c); a cord including the fiber; a fabric comprising said cord; and a tire applying said fabric to the cap ply thereof, (a): the ratio of alicyclic dicarboxylic acid to dicarboxylic acid being at least 50 mol %. (b): the total fineness of the polyamide multifilament fiber being at least 100 dtex. (c): the cross ratio (maximum diameter/minimum diameter) of the polyamide multifilament fiber being no more than 1.7). This polyamide multifilament fiber is high-Tg and high strength and has excellent spinning strength and fiber uniformity. The tire cord using same has excellent rubber adhesion properties and is capable of applying good dimensional stability to the tire at high temperatures.