MANUFACTURING METHOD OF CARBON FIBER PRECURSOR FIBER BUNDLE, MANUFACTURING METHOD OF CARBON FIBER BUNDLE AND CARBON FIBER BUNDLE

PROBLEM TO BE SOLVED: To provide a carbon fiber bundle capable of exhibiting excellent composite mechanical properties even with same carbon fiber used amount and having excellent tensile strength and adhesive strength with a matrix resin.SOLUTION: There is provided a manufacturing method of a carbon fiber precursor fiber bundle having a constitutional percentage of single fibers a to e with an elliptical shape having a ratio of long diameter and short diameter of single fiber cross section of 1.20 to 1.60 of 15 to 60%, constitutional percentage of single fibers with a circle shape with a ratio of long diameter and short diameter of a single fiber cross section of 1.00 to 1.20 of 40 to 85%, single fiber fineness of 0.5 to 1.2 dtex and filament number of 1,000 to 18,000, by discharging a spinning raw liquid containing a polyacrylonitrile-based polymer body in a coagulation bath with concentration of a solvent of 50 to 80 mass% at a temperature of 45 to 67°C to obtain a coagulated yarn, then conducting drawing at 1.2 to 2.4 times in warn water, adding a silicone oil agent, drying to have moisture fraction of the coagulated yarn of 1 mass% or less and drawing at 5 to 9 times under a compression steam.SELECTED DRAWING: Figure 1 【課題】同一の炭素繊維使用量でも優れたコンポジット機械的特性を発現でき、優れた引張強度、マトリックス樹脂との接着強度性を有する炭素繊維束の提供。【解決手段】ポリアクリロニトリル系重合体を含む紡糸原液において、溶媒の濃度が５０〜８０質量％、温度４５〜６７℃の凝固浴中で吐出して凝固糸条を得た後、温水中で１．２〜２．４倍の延伸を施し、シリコーン系油剤を付与し、凝固糸条の含有水分量が１質量％以下となるまで乾燥させた後、加圧スチーム下で５〜９倍延伸する方法であって、単繊維断面の長径と短径との比が１．２０〜１．６０の楕円形状である単繊維ａ〜ｅの構成比率が１５〜６０％、単繊維断面の長径と短径との比が１．００〜１．２０の円形状である単繊維の構成比率が４０〜８５％であり、単繊維繊度が０．５〜１．２ｄｔｅｘ、フィラメント数が１，０００〜１８，０００である炭素繊維前駆体繊維束の製造方法。【選択図】図１