Patent ID: 8236273
Filing Date: 2012-08-07
Classification: D01F

Abstract:
1. A method of producing a pre-oxidation fiber in the production of the pre-oxidation fiber by subjecting a polyacrylic precursor fiber to pre-oxidation processing in an oxidizing atmosphere, the method comprising: (1) shrinking the precursor fiber as a pretreatment of pre-oxidation at a load of 0.58 g/tex or less in the temperature range of 220 to 260° C. under conditions in which the degree of cyclization (I (2) initially-drawing the precursor fiber at a load of 2.7 to 3.5 g/tex in an oxidizing atmosphere of 230 to 260° C. in the ranges of the degree of cyclization of not exceeding 27% and of the density of not exceeding 1.2 g/cm (3) subjecting the precursor fiber to pre-oxidation treatment at 200 to 280° C. at a draw ratio of 0.85 to 1.3 until the density becomes 1.3 to 1.5 g/cm