Poly-p-phenylene-terephthalamide fibers excellent in fatigue resistance and process for preparation thereof
AssigneeAsahi Kasei Kogyo Kabushiki Kaisha
InventorsTakashi Fujiwara, Shuji Kajita, Tetsuo Matsushita, Seiichi Manabe
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Abstract
A poly-p-phenylene-terephthalamide fiber with excellent fatigue resistance resulting from a unique combination of properties. The fibers are prepared by extruding an anisotropic polymer dope in a non-coagulating layer, passing the extrudate through a coagulating layer, depositing the resulting coagulated fibers on a net conveyor, and in the absence of substantial tension sequentially washing the fibers, holding the fibers in saturated steam, and drying the fibers under specified conditions.
Claims9
A fiber excellent in fatigue resistance, consisting essentially of poly-p-phenylene-terephthalamide, wherein the tangential refractive index (TRIv) of the fiber by polarized light vibrating in the direction perpendicular to the fiber axis is in the range of from 0 to 0.07, the tangential refractive index (TRIp) of the fiber by polarized light vibrating in the direction parallel to the fiber axis is in the range of from -0.06 to -0.005, the central refractive index (Nvo) of the fiber by polarized light vibrating in the direction perpendicular to the fiber axis and the X-ray diffraction intensity ratio (RIX) are in the range satisfying the conditions of the formulae (1) through (4):
- Nvo.gtoreq.-0.08(RIX)+1.672 (1)
- Nvo.ltoreq.1.700 (2)
- RIX.gtoreq.0.85 (3)
- RIX.ltoreq.1.20 (4)
- and the apparent crystallite size (ACS in A) of the fiber and the orientation angle (OA in degrees) of the fiber are in the range circumscribed by the four lines (a), (b), (c), and (d) defined by the formulae (5) through (8) as illustrated in FIG. 1:
- OA.gtoreq.0.04(ACS)+16 (5)
- OA.gtoreq.2(ACS)-160 (6)
- OA.ltoreq.0.04(ACS)+26 (7)
- OA.ltoreq.2(ACS)-82 (8).
Dependencies are inferred from the claim text.