Kuraray Co., Ltd.

Tadayoshi Koizumi

Kazuhiko Tanaka

Masao Kawamoto

Hitoshi Nakatsuka

Nobuhiro Koga

Kenichi Yoshioka

In an electrically conductive sheath-core conjugate fiber including an electrically conductive layer made of a thermoplastic polymer (A) containing electrically conductive carbon black fine particles which constitutes a sheath component and a protective layer made of a fiber-forming thermoplastic polymer (B) which constitutes a core component, the ratio of the (A) to the total weight of the (A) and the (B) is 10 to 35% by weight, the L/Lratio is 1.04 to 10.0 where Lrepresents the length of a boundary between the core component and the sheath component in a cross section of the conjugate fiber and Lrepresents the length of the circumference of a circle having an area equal to a cross sectional area of the core component, the fineness, the strength at break and the elongation at break are each adjusted within specified ranges, the shrinkage in hot water at 100&#xb0; C. is within a specified range, and the fiber surface coverage of the sheath component is 85% or more. This results in provision of an electrically conductive sheath-core conjugate fiber that is excellent in antistatic performance, which is hardly degraded even after long-term wearing, that is maintained for a long time, and that is excellent in durability. A method for producing the electrically conductive sheath-core conjugate fiber and a dust-proof clothing using such a fiber are also provided.

Conductive sheath-core conjugate fiber and process for producing the same

An electrically conductive composite fiber comprising an electrically conductive layer formed of a polyester-based polymer (A) having a melting point of 200&#xb0; C. or higher and containing from 23 to 33% by weight of electrically conductive carbon black, and a protective layer formed of a polyester-based polymer (B) having a melting point of 210&#xb0; C. or higher, wherein the difference between the SP value of the (A) and the SP value of the (B) is adjusted to not greater than a predetermined value and the fiber strength and the elongation at break are adjusted within certain ranges. This can make it possible to obtain an electrically conductive composite fiber that has a superior antistatic performance, which is not degraded very much over a practical wearing for a long term, though it contains only a relatively small amount of electrically conductive carbon black, and that is suitable for the field of clothing such as clean room wears and working wears.

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Kurashiki, Japan

Tadayoshi Koizumi