POLYPROPYLENE FIBER, METHOD OF PRODUCING THE SAME AND UTILIZATION OF THE SAME

摘要

[PROBLEMS] To provide a polypropylene fiber (PP fiber) excellent in strength, heat tolerance and water-absorbing property; a method of producing the same; and a hydraulic composition, a rope, a sheet-type fiber construct and a composite material with an organic polymer each using the above PP fiber. [MEANS FOR SOLVING PROBLEMS] A PP fiber having a fiber strength of 7 cN/dtex or more and exhibiting either or both of the following characteristics: (i) a single shape exhibiting a maximum heat absorption peak shape having a half-value width of 10°C or lower and DSC characteristics exhibiting a melting enthalpy change (?H) of 125 J/g, and (ii) peaks-and-valleys characteristics having a single filament fineness of 0.1 to 3 dtex wherein peaks with a large diameter and non-peaks with a small diameter are alternately located along the fiber axis on the surface and the average interval of? the peaks and valleys is from 6.5 to 20 µm and the average height thereof is from 0.35 to 1 µm; a method of producing the PP fiber as described above which comprises pre-stretching 3- to 10-fold an unstretched PP fiber having an IPF of 94% or more at 120 to 150°C, and then after-stretching it 1.2- to 3.0-fold at 170 to 190°C at a deformation speed of 1.5- to 15-fold/min under a stretch tension of 1.0 to 2.5 cN/dtex; and a hydraulic composition, a rope, a sheet-type fiber construct and a composite material with an organic polymer each using the above PP fiber.