Abstract: The present invention relates to polybenzazole fibers or filaments, staple fibers, spun yarns, and woven or knitted fabrics containing in themselves an organic pigment having heat resistance as high as a thermal decomposition temperature of 200° C. or higher, and soluble in a mineral acid and having group(s) of —N? and/or NH— in the molecule, such as any of perinones and/or perylenes, any of phthalocyanines, any of quinacridones, and any of dioxazines, wherein they have a strength retention of 50% or higher when exposed to light from a xenon lamp for 100 hours and having a tensile strength retention of 85% or higher after exposed to an atmosphere of a temperature of 80° C. and a relative humidity of 80% for 700 hours. The polybenzazole fibers or filaments, staple fibers, spun yarns, and woven or knitted fabrics can be used for cords for reinforcing rubber, sheets and rods for reinforcing cement/concrete, composite materials, sail clothes, ropes, knife proof vests and bullet proof vests.

Abstract: The present invention relates to polybenzazole fibers or filaments, staple fibers, spun yarns, and woven or knitted fabrics containing in themselves an organic pigment having heat resistance as high as a thermal decomposition temperature of 200° C. or higher, and soluble in a mineral acid and having group(s) of —N=and/or NH— in the molecule, such as any of perinones and/or perylenes, any of phthalocyanines, any of quinacridones, and any of dioxazines, wherein they have a strength retention of 50% or higher when exposed to light from a xenon lamp for 100 hours and having a tensile strength retention of 85% or higher after exposed to an atmosphere of a temperature of 80° C. and a relative humidity of 80% for 700 hours. The polybenzazole fibers or filaments, staple fibers, spun yarns, and woven or knitted fabrics can be used for cords for reinforcing rubber, sheets and rods for reinforcing cement/concrete, composite materials, sail clothes, ropes, knife proof vests and bullet proof vests.

Abstract: There is provided a polybenzazole fiber or film containing a basic organic compound in the form of a monomer or a condensate, selected from the group consisting of guanidines, triazoles, quinazolines, piperidines, anilines, pyridines, cyanuric acids, and p-phenylenediamine, m-phenylenediamine and a mixture thereof. This fiber has characteristics in that the X-ray meridian diffraction half-width factor is 0.3°/GPa or less, that the elasticity decrement (Er) attributed to change of molecular orientation is 30 GPa or less, and that the breaking strength is 1 GPa or more. This fiber can be used in staple fiber, a spun yarn, a woven or knit fabric, a felt material, a composite material, a cord, a rod, a fibrous sheet, a knife proof vest or a bullet proof vest.

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 colored high-tenacity fiber of ultra-high molecular weight polyethylene which is obtainable by spinning a solution of ultra-high molecular weight polyethylene and a dye for coloration to form solvent-containing filaments and drawing the solvent-containing filaments. The colored high-tenacity fiber of ultra-high molecular weight polyethylene has a tensile strength of at least 28 g/d and a tensile modulus of at least 700 g/d. The dye is substantially soluble in the solvent at the melting point of solvent-containing filaments which are obtained by spinning a solution of ultra-high molecular weight polyethylene and the dye is substantially uniformly dispersed in the core portion of the fiber. Also disclosed is a process for producing a colored high-tenacity fiber of ultra-high molecular weight polyethylene.

Abstract: There is disclosed a high-tenacity polyethylene fiber containing an ethylene component as a main repeating unit, the fiber exhibiting an intrinsic viscosity [.eta..sub.B ] of at least 7 and having a tenacity of at least 30 g/d and an elastic modulus of at least 900 g/d; the peak value of loss tangent in the .gamma.-dispersion being 0.025 to 0.06 and the peak temperature of loss modulus in the .alpha.-dispersion being 85.degree. C. or higher, as determined by measurement of temperature dispersion of viscoelastic properties of the fiber. Also disclosed is a process of producing such a high-tenacity polyethylene fiber.

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 high-tenacity polyethylene fiber containing an ethylene component as a main repeating unit, the fiber exhibiting an intrinsic viscosity [.eta..sub.B ] of at least 7 and having a tenacity of at least 30 g/d and an elastic modulus of at least 900 g/d; the peak value of loss tangent in the .gamma.-dispersion being 0.025 to 0.06 and the peak temperature of loss modulus in the a-dispersion being 85.degree. C. or higher, as determined by measurement of temperature dispersion of viscoelastic properties of the fiber. Also disclosed is a process of producing such a high-tenacity polyethylene fiber.