Toray Industries, Inc.

Seiji Mizukami

Masato Masuda

Joji Funakoshi

Yoshitsugu Funatsu

Akira Kishiro

Makoto Endo

Haruki Morikawa

Eiichi Yamamoto

A sea-island composite fiber includes island component fibers having a circumscribed circle diameter of 10 to 1000 nm, a circumscribed circle diameter variation of 1 to 20%, a non-circularity of 1.2 to 5.0, and a non-circularity variation of 1 to 10%.

Sea-island composite fiber

A sea-island composite fiber has an island component which is ultrafine fibers having a noncircular cross-section, the ultrafine fibers being uniform in the degree of non-circularity and in the diameter of the circumscribed circle. The sea-island composite fiber includes an easily soluble polymer as the sea component and a sparingly soluble polymer as the island component, and the island component has a circumscribed-circle diameter of 10-1,000 nm, a dispersion in circumscribed-circle diameter of 1-20%, a degree of non-circularity of 1.2-5.0, and a dispersion in the degree of non-circularity of 1-10%.

Sea-island composite fiber, ultrafine fiber, and composite spinneret

By using carbon fibers having a fineness of 25,000 deniers or more, the present invention provides a carbon fiber package including a cheese winding package or a coreless package in which an outside diameter of the package, a diameter of a bobbin or an inside diameter of the package, and a winding width are regulated in the specific ranges, a square-end type package in which a yarn width per fineness, wind angles at the start of winding and at the end of winding, and shifting of the yarn are regulated in the specific ranges, and a carbon fiber packed member in which an average bulk density is regulated in a specific range. Those carbon fiber packages and the carbon fiber packed member solve troubles and inconveniences during use, and also packages which have a high winding density and which do not break easily can be obtained.

Carbon fiber package and carbon fiber packed member

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Otsu, Japan

Seiji Mizukami