Abstract: A polyester fiber containing polyethylene terephthalate at 90 mol % or higher of a whole repeating unit in a molecular chain thereof, the fiber having an intrinsic viscosity (IV) of 0.85 dl/g or higher and simultaneously meeting the following characteristics: (a) strength?6.0 cN/dtex; (b) strength×(breaking elongation)0.5?26.0 cN/dtex. %0.5; (c) monofilament linear density?5.0 dtex; and (d) main dispersion peak temperature of loss tangent (tan ?) in the measurement of dynamic viscoelasticity at 110 Hz?147.0° C.

Abstract: A polyester fiber containing polyethylene terephthalate at 90 mol % or higher of a whole repeating unit in a molecular chain thereof, the fiber having an intrinsic viscosity [IV] of 0.85 dl/g or higher and simultaneously meeting the following characteristics: (a) strength≧6.0 cN/dtex; (b) strength×(breaking elongation)0.5≦26.0 cN/dtex.%0.5; (c) monofilament linear density≦5.0 dtex; and (d) main dispersion peak temperature of loss tangent (tan &dgr;) in the measurement of dynamic viscoelasticity at 110 Hz≦147.0° C.

Abstract: Crimped polybenzazole staple fibers which satisfy the following specifications at the same time:(1) 2.ltoreq.number of crimps (number/inch).ltoreq.40(2) 2.ltoreq.crimp index (%).ltoreq.30(3) 0.3.ltoreq.crimp index/number of crimps.ltoreq.3.0; methods for manufacturing crimped polybenzazole staple fibers; and the rotary cutter therefor. The crimped polybenzazole staple fibers of the present invention are superior in crimp property and are useful for manufacturing spun yarn and unwoven fabric. According to the method of the present invention, crimped polybenzazole staple fibers superior in spinnability can be manufactured with ease. In addition, the cutting blade of the present invention stands a long time use for manufacturing staple fibers from a continuous filaments tow of high tenacity fibers.

Abstract: There is disclosed a structured fiber material with a three-dimensional network structure containing non-elastic crimped short fibers (A) and three-dimensionally crimped composite fibers (B), the fibers (B) being partially interlocked with each other, in which contact portions the fibers (B) are partially heat-bonded with each other; the fibers (B) being partially wound around the fibers (A) at their contact points, in which contact portions the fibers (A) and (B) are partially heat-bonded with each other; and the material having an apparent density of 0.005 to 0.10 g/cm.sup.3. Also disclosed is a process for producing the structured fiber material.

Abstract: Crimped polybenzazole staple fibers which satisfy the following specifications at the same time:(1) 2.ltoreq.number of crimps (number/inch).ltoreq.40(2) 2.ltoreq.crimp index (%).ltoreq.30(3) 0.3.ltoreq.crimp index/number of crimps.ltoreq.3.0; methods for manufacturing crimped polybenzazole staple fibers; and the rotary cutter therefor. The crimped polybenzazole staple fibers of the present invention are superior in crimp property and are useful for manufacturing spun yarn and unwoven fabric. According to the method of the present invention, crimped polybenzazole staple fibers superior in spinnability can be manufactured with ease. In addition, the cutting blade of the present invention stands a long time use for manufacturing staple fibers from a continuous filaments tow of high tenacity fibers.

Abstract: There is disclosed a structured fiber material with a three-dimensional network structure containing non-elastic crimped short fibers (A) and three-dimensionally crimped composite fibers (B), the fibers (B) being partially interlocked with each other, in which contact portions the fibers (B) are partially heat-bonded with each other; the fibers (B) being partially wound around the fibers (A) at their contact points, in which contact portions the fibers (A) and (B) are partially heat-bonded with each other; and the material having an apparent density of 0.005 to 0.10 g/cm.sup.3. Also disclosed is a process for producing the structured fiber material.

Abstract: A recyclable vehicular cushioning material which is thermoformed from a web composed of three-dimensionally crimped polyester fiber having a fineness lower than 45 denier per filament and an initial tensile strength (IS) higher than 30 g/d and heat-bonding fiber containing polyester elastomer, as heat-bonding component, which are mixed and dispersed and, if necessary, interlaced, said cushioning material having a layer whose bulk density is 0.02-0.06 g/cm.sup.3.

Abstract: Polyester fibers having high tenacity and high modulus can be produced practically and economically by melt-spinning a copolyester at a take-up speed of 3,000 meters/min. or more. The copolyester comprises at least 60 mol % of ethylene terephthalate units, has a persistence length of 15 angstroms or more and does not show a liquid crystalline nature in the molten state.