Abstract: 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 L1/L0 ratio is 1.04 to 10.0 where L1 represents the length of a boundary between the core component and the sheath component in a cross section of the conjugate fiber and L0 represents 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° C. is within a specified range, and the fiber surface coverage of the sheath component is 85% or more.

Abstract: An electrically conductive composite fiber comprising an electrically conductive layer formed of a polyester-based polymer (A) having a melting point of 200° 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° 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.

Abstract: 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 L1/L0 ratio is 1.04 to 10.0 where L1 represents the length of a boundary between the core component and the sheath component in a cross section of the conjugate fiber and L0 represents the length of the circumference of a 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° C. is within a specified range, and the fiber surface coverage of the sheath component is 85% or more.

Abstract: An electrically conductive composite fiber comprising an electrically conductive layer formed of a polyester-based polymer (A) having a melting point of 200° 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° 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.

Abstract: Provided is an electrically conductive conjugate fiber formed by conjugating an electrically conductive layer (A) including 60 to 80% by weight of a thermoplastic resin and 20 to 40% by weight of electrically conductive particles and a protective layer (B) including 50 to 95% by weight of polyethylene terephthalate and 5 to 50% by weight of polyethylene-2,6-naphthalate, wherein the fiber has a degree of elongation (DE) of 100 to 350%. This provides an electrically conductive conjugate fiber which exhibits a small change with time in physical properties such as a degree of elongation or boiling water shrinkage during its transportation or storage, while having a certain degree of elongation.