PURPOSE: To obtain a synthetic fibrous material, capable of utilizing fibers thereof in the direction perpendicular to the fiber axis direction and useful as a heat insulating or feathery material, by cutting modified cross-section synthetic fibers having divided branches and leaves to a very short and specific length in the fiber axis direction.
CONSTITUTION: Modified cross-section synthetic fibers having divided branches and leaves are cut to a length of <5 times, preferably ≤2 times based on the cross-sectional diameter (normally 1W5cm) in the fiber axis direction to afford the aimed fibrous material. Preferred examples of the modified cross-section synthetic fibers are fibers in which many feathery ultrafine branches and leaves of, e.g. 0.04 de, are present and satisfy the following relations; H/W ≥0.8, H/R ≥0.7 and A/πR2 ≤0.4 (W is the opening distance of the adjacent branches and leaves; H is the height of protrusions; R is the radius of the longest axis; A is the cross-sectional area) with hollow trunk parts.
NANBA MASANORI
NAKAMURA TERUO
