CARBON FIBER PRECURSOR ACRYLIC FIBER BUNDLE, METHOD FOR THERMALLY OXIDIZING PART THEREOF, THERMAL OXIDATION OVEN, AND PROCESS FOR PRODUCING CARBON FIBER BUNDLE

摘要

Provided is a carbon-fiber-precursor acrylic fiber bundle which can smoothly pass through a flame-resistance impartation step and a carbonization step. The carbon-fiber-precursor acrylic fiber bundle has a high-density part as a portion thereof, wherein the high-density part satisfies the following requirements (A) and (B). Requirement A: The high-density part has a maximum fiber density ρmax of 1.33 g/cm3 or higher. Requirement B: The portion extending between an intermediate-density point and a maximum-density-region arrival point has an increase in fiber density of 1.3×10−2 g/cm3 or less per 10 mm of the fiber bundle length. The term “intermediate-density point” means the site which has a density ρm that is intermediate between the fiber density ρo of the non-high-density part and the maximum fiber density ρmax. The term “maximum-density-region arrival point” means the site Pr at which the increase in fiber density per 10 mm of the fiber bundle length becomes 1.0×10−3 g/cm3 or less, the increase in fiber density being represented by (ρr+0−ρr)/5 determined from a measurement in which density measurement points beginning with the point where the density begins to increase and located at intervals of 50 mm are successively examined for fiber density (ρ1, ρ2, . . . , ρr, . . . , ρn).

主权项

1. A carbon fiber precursor acrylic fiber bundle comprising a high density part as a portion thereof, wherein the high density part satisfies requirements A and B:
A: the high density part has a maximum fiber density ρmax of 1.33 g/cm3 or higher, and B: an increase in fiber density between an intermediate density point and a maximum density region arrival point is 1.3×10−2 g/cm3 or less per 10 mm of a fiber bundle length; with the proviso that, the term “intermediate density point” is defined as the site which has a density ρm (=(ρ0+ρmax)/2) that is intermediate between the fiber density ρ0 of a non-high density part and the maximum fiber density ρmax, the term “maximum density region arrival point” is defined as the site Pr at which the increase in fiber density per 10 mm of the fiber bundle length becomes 1.0×10−3 g/cm3 or less, the increase in fiber density being represented by (ρr+1−ρr)/5 determined from a measurement in which density measurement points beginning with the density increase start point and located at intervals of 50 mm (P1, P2, . . . , Pr, Pr+1, . . . , Pn) are successively examined for fiber density (ρ1, ρ2, . . . , ρr, . . . , ρn), and the term “density increase start point” is defined as a site at which the fiber density is higher by 0.01 g/cm3 than the fiber density ρ0 of the non-high density part.