HOLLOW CROSS-SECTIONAL FIBER

To provide a hollow cross-sectional fiber which is excellent in bulkiness, light weight and wear resistance while having high smoothness when being made into a dough.SOLUTION: Provided is a hollow cross-sectional fiber which comprises at least one hollow part and plural protruding parts in a single fiber cross-section perpendicular to a fiber axis direction, and has the characteristics of the following A to C: A that a modified degree (the circumscribed circle diameter (R) of the single fiber/the inscribed circle diameter (r1) of the single fiber when it is assumed to be solid) is 1.3 to 1.6; B that, provided that distances from an apex of each protruding part to the deepest points of recessed parts on both the sides of the protruding part are defined as L1, L2, their ratio L1/L2 is 1.3 to 2.6; and C that, in the single fiber, the central axes of the protruding parts (straight lines connecting the apexes of the protruding parts and the middle points of the line segments L1, L2) are tilted in the same direction in the outer circumferential direction of the fiber cross-section.SELECTED DRAWING: Figure 1 【課題】生地にした際に高い平滑性を有しながら、嵩高・軽量性、耐摩耗性に優れた中空断面繊維を提供する。【解決手段】繊維軸方向に対して直交する単繊維横断面において、少なくとも１個の中空部と複数の突起部とを備え、下記Ａ～Ｃの特徴を有する中空断面繊維。Ａ．異形度(単繊維の外接円直径（Ｒ）／中実と仮定した際の単繊維の内接円直径（ｒ１）)が１．３～１．６である。Ｂ．突起部の頂点から該突起部の両側の凹部の最深点までの距離をＬ１、Ｌ２としたとき、その比Ｌ１／Ｌ２が１．３～２．６である。Ｃ．単繊維において、突起部の中心軸（突起部の頂点と線分Ｌ１Ｌ２の中点とを結ぶ直線）が繊維横断面の外周方向において同じ方向に傾斜している。【選択図】図１