JP7358796B2 - Conductive fiber and its manufacturing method - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act Published as a presentation at an academic conference (29th Annual Conference on Plastic Molding Processing) on June 20th, 2018 Published at an academic conference (26th Plastic Molding Processing Symposium) on November 26th, 2018 Published by presentation at the Annual Autumn Conference)

TECHNICAL FIELD The present invention relates to conductive fibers and methods for manufacturing the same.

Conductive fibers using conductive carbon black are known (for example, Patent Document 1). In the fiber cross section of such conductive fibers, there are two types: a non-exposed type in which the conductive layer is completely wrapped in a non-conductive layer, and an exposed type in which the conductive layer is exposed on a part of the fiber surface or the entire fiber surface. However, the exposed type has better antistatic performance, and among these, the type where the entire fiber surface is exposed has particularly excellent antistatic performance.

As a method for producing a conductive fiber having a conductive layer exposed over the entire surface of the fiber as described above, a method can be considered in which a large amount of highly structured carbon black aggregate is blended into a resin composition and then melt-molded.

However, since such a resin composition has poor melt flowability, it has been difficult to form it into thin conductive fibers with a conductive layer exposed on the surface. Furthermore, if high shear is applied to the resin composition in order to increase melt fluidity, the carbon black network may be broken and the conductivity may be reduced.

JP 2018-193648 Publication

Therefore, the problem to be solved by the present invention is to provide a thin conductive fiber having high conductivity and having a conductive layer exposed on its surface, and a method for manufacturing the same.

The present inventors conducted extensive studies in order to solve the above problems. As a result, the inventors discovered that the above problems could be solved by blending specific amounts of carbon black and metal phthalocyanine, and completed the present invention.

That is, the present invention provides a conductive fiber formed by blending a thermoplastic resin (A), carbon black (B), and metal phthalocyanine (C), wherein the carbon black (B) has a pH of 5 or more. , the blending amount of the metal phthalocyanine (C) with respect to 100 parts by mass of the carbon black (B) ranges from 0.1 parts by mass or more to 50 parts by mass or less, and the thermoplastic resin (A) and the carbon black ( The total blending amount of the carbon black (B) and the metal phthalocyanine (C) in the total blending amount of B) and the metal phthalocyanine (C) ranges from 5% by mass or more to 20% by mass or less, and the fiber diameter is 10 μm or less.

The present invention also provides a method for producing a conductive fiber comprising a thermoplastic resin (A), carbon black (B), and metal phthalocyanine (C), wherein at least the thermoplastic resin (A) A step 1 of obtaining a thermoplastic resin composition by melt-kneading the carbon black (B), the metal phthalocyanine (C), and a thermoplastic resin (D) other than the thermoplastic resin (A); Step 2 of melt-spinning the thermoplastic resin composition, and contacting the thermoplastic resin (D) with a solvent that dissolves the thermoplastic resin (D) but does not dissolve the thermoplastic resin (A). Step 3 of selectively removing the thermoplastic resin (D) to obtain conductive fibers, wherein the carbon black (B) has a pH of 5 or more, and the carbon black (B) in the conductive fibers The blending amount of the metal phthalocyanine (C) with respect to 100 parts by mass ranges from 0.1 parts by mass or more to 50 parts by mass or less, and the thermoplastic resin (A), the carbon black (B), and the metal phthalocyanine ( The total blending amount of the carbon black (B) and the metal phthalocyanine (C) in the total blending amount of C) ranges from 5% by mass to 20% by mass, and the fiber diameter of the conductive fiber is 10 μm. The following is.

ADVANTAGE OF THE INVENTION According to the present invention, it is possible to provide a thin conductive fiber having high conductivity and having a conductive layer exposed on its surface, and a method for producing the same.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated in detail.

In one embodiment of the present invention, the conductive fiber is a conductive fiber formed by blending a thermoplastic resin (A), carbon black (B), and metal phthalocyanine (C), B) has a pH of 5 or more, the amount of the metal phthalocyanine (C) blended in a range from 0.1 parts by mass to 50 parts by mass with respect to 100 parts by mass of the carbon black (B), and the thermoplastic resin ( The total blending amount of the carbon black (B) and the metal phthalocyanine (C) in the total blending amount of A), the carbon black (B), and the metal phthalocyanine (C) is from 5% by mass or more to 20% by mass or less. The fiber diameter is 10 μm or less.

According to the conductive fiber, it is possible to provide a thin conductive fiber having high conductivity and having a conductive layer exposed on the surface. The reason why such an effect is obtained is not necessarily clear, but it is presumed to be due to the following mechanism.

The carbon black (B) and the metal phthalocyanine (C) blended in specific amounts form pseudo-agglomerations, and the pseudo-agglomerations form a conductive network, so it is thought that high conductivity is exhibited. In addition, when molding the thermoplastic resin composition that is the raw material for conductive fibers, if high shear is applied, the conductive network will temporarily collapse and the fluidity of the thermoplastic resin composition will develop, resulting in smaller fiber diameters. processing becomes easier. Moreover, since the carbon black (B) and the metal phthalocyanine (C) aggregate again during molding and solidification to form a conductive network, it is thought that the above problem can be solved.

The thermoplastic resin (A) is not particularly limited as long as it does not impair the effects of the present invention, but examples include polyamide resin, polycarbonate resin, rubber-reinforced styrene resin, polyester resin, polyether ketone resin, polyether resin, and polyimide. Examples include resins, polyarylene sulfide resins, polyarylene ether resins, silicone compounds, and among these, polyamide resins are preferred. The polyamide resin is a polymer having an acid amide bond (-CONH-) in the main chain. Such polyamide resins include nylon 6 (also called "poly(caprolactam)"), nylon 11 (also called "poly(11-aminoundecanoic acid)"), nylon 12 ("poly(lauryllactam)" or " Poly(12-7 minododecanoic acid)), Nylon 6.6 (also referred to as Poly(hexamethylene adipamide)), Nylon 6.9 (Poly(hexamethylene azeramide) or Poly(hexamethylene adipamide)). nylon 6.10 (also referred to as ``poly(hexamethylene sebacamide)'' or ``poly(hexamethylene decanediamide)''), nylon 6.12 (also referred to as ``poly(hexamethylene dodecanediamide)'') ”), nylon 4 (also referred to as “poly(δ-butyrolactam)”), nylon 7 (also referred to as “poly(7-aminohbutanoic acid)” or “poly(7-aminocaprylic acid)”), nylon 8 (also called "poly(8-aminocaprylic acid)" or "poly(8-aminooctanoic acid)"), nylon 10,6 ("poly(decamethylene adipamide)", partially aromatic nylon (PARNS), etc. Can be mentioned.

The blending ratio of the thermoplastic resin (A) in the conductive fibers is not particularly limited, but from the viewpoint of developing high conductivity, it is preferably 80% by mass or more, more preferably 85% by mass or more, and preferably 95% by mass or more. The range is 90% by mass or less, more preferably 90% by mass or less.

As the carbon black (B), carbon black used as a pigment, which is produced by a known method such as a contact method, a furnace method, or a thermal method, can be used without particular limitation. For example, Mitsubishi Chemical's #2600 series, #2300 series, #1000 series, #900 series, MA series, Orion Engineered Carbons' COLOR-BLACK series, SPECIAL-BLACK series, PRINTEX series, HIBLACK series, NEROX. series, NIPex series, SUNBLACK series, #70 series, and #80 series manufactured by Asahi Carbon Co., Ltd., and Toka Black #7000 series and #8000 series manufactured by Tokai Carbon Co., Ltd., and the like. Among them, carbon black with a high structure called conductive carbon is preferred from the viewpoint of exhibiting high conductivity.

The pH of the carbon black (B) is in the range of 5 or more, preferably 6 or more, preferably 10 or less, and more preferably 8 or less, from the viewpoint of developing high conductivity.

The volatile content of the carbon black (B) is preferably in the range of 1.5% or less from the viewpoint of exhibiting high conductivity.

The average particle size of the carbon black (B) is not particularly limited, but is preferably in the range of 30 nm or less from the viewpoint of developing formability that enables processing into small fiber diameters and from the viewpoint of developing high conductivity. The range is more preferably 28 nm or less. The lower limit is not particularly limited, but is preferably in the range of 10 nm or more, more preferably in the range of 15 nm or more.

The surface of the carbon black (B) may be physically or chemically treated. The surface area of the carbon black (B) is not particularly limited, but preferably has a BET specific surface area [m ² /g] of 30 or more, more preferably 50 or more, still more preferably 80 or more, preferably 300 or less, and more. The range is preferably 200 or less, more preferably 150 or less.

The blending ratio of the carbon black (B) in the conductive fiber is not particularly limited, but from the viewpoint of developing high conductivity, it is preferably 1% by mass or more, more preferably 5% by mass or more, and preferably 20% by mass. % or less, more preferably 15% by mass or less.

Examples of the metal phthalocyanine (C) include pigments having a phthalocyanine skeleton, and among these, phthalocyanine blue and phthalocyanine green are preferred. Examples of the metal phthalocyanine (C) include Pigment Blue 15, 15:1, 15:2, 15:3, 15:4, 15:6, and 17:1 in Color Index Generic Name. Representative copper phthalocyanine; Halogenated phthalocyanine represented by Pigment Green 7 and Pigment Green 36 ; At least one metal phthalocyanine compound whose central metal element is selected from aluminum, nickel, cobalt, iron, magnesium, zinc, etc. It will be done. These may be used alone or in combination of two or more.

The average particle size of the metal phthalocyanine (C) is not particularly limited, but is preferably in the range of 800 nm or less from the viewpoint of developing formability that enables processing into small fiber diameters and from the viewpoint of developing high conductivity. The range is more preferably 500 nm or less. The lower limit is not particularly limited, but is preferably in the range of 10 nm or more, more preferably in the range of 30 nm or more.

The blending ratio of the metal phthalocyanine (C) in the conductive fiber is not particularly limited, but from the viewpoint of developing high conductivity, it is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, The content is preferably 5% by mass or less, more preferably 2% by mass or less.

The amount of the metal phthalocyanine (C) to be blended with respect to 100 parts by mass of the carbon black (B) is 0.05% from the viewpoint of developing moldability that enables processing into small fiber diameters and from the viewpoint of developing high conductivity. The amount ranges from 1 part by weight or more, preferably 1 part by weight or more, to 50 parts by weight or less, preferably 20 parts by weight or less.

The total blending amount of the carbon black (B) and the metal phthalocyanine (C) in the total blending amount of the thermoplastic resin (A), the carbon black (B), and the metal phthalocyanine (C) is the same as the total blending amount of the carbon black (B) and the metal phthalocyanine (C). From the viewpoint of developing formability to enable processing and high conductivity, the content ranges from 5% by mass or more, preferably 7% by mass or more, to 20% by mass or less, preferably 15% by mass or less. be.

Known additives other than the thermoplastic resin (A), the carbon black (B), and the metal phthalocyanine (C) can also be used as arbitrary raw material components in the conductive fiber. Such known additives include halogen flame retardants, nitrogen flame retardants, phosphate ester flame retardants, inorganic flame retardants such as metal hydroxides and oxides, silicone flame retardants, and organic metal phosphates. Flame retardants such as salts, antioxidants such as hindered phenol compounds, hydroquinone compounds, phosphite compounds and substituted products thereof, resorcinol compounds, salicylate compounds, benzotriazole compounds, benzophenone compounds, Weathering agents such as hindered amine compounds, mold release agents or lubricants such as aliphatic alcohols, aliphatic amides, aliphatic bisamides, bisurea compounds, polyethylene wax, crystal nucleating agents such as talc, silica, kaolin, clay, etc. Plasticizers such as octyl p-oxybenzoate, N-butylbenzenesulfonamide, etc., non-plasticizers such as alkyl sulfate type anionic antistatic agents, quaternary ammonium salt type cationic antistatic agents, polyoxyethylene sorbitan monostearate, etc. Antistatic agents such as ionic antistatic agents and betaine amphoteric antistatic agents, graphite, barium sulfate, magnesium sulfate, calcium carbonate, magnesium carbonate, antimony oxide, titanium oxide, aluminum oxide, zinc oxide, iron oxide, zinc sulfide. , zinc, lead, nickel, aluminum, copper, iron, stainless steel, bentonite, montmorillonite, synthetic mica, and other particulate, acicular, and plate-shaped fillers, as well as glass fiber, glass flakes, carbon fiber, boron nitride, and titanium. Examples include reinforcing materials such as potassium acid and aluminum borate. When these additives are used as optional components, the blending ratio in the conductive fiber is 25% by mass from the viewpoint of developing formability that enables processing into small fiber diameters and from the viewpoint of developing high conductivity. % or less. In other words, the total proportion of the thermoplastic resin (A), the carbon black (B), and the metal phthalocyanine (C) in the conductive fiber is in a range of more than 75% by mass.

The electrical resistivity of the conductive fiber is preferably from 10 ² Ω·cm or more, more preferably 10 ³ Ω·cm or more, to preferably 10 ⁹ Ω·cm or less, more preferably 10 ⁸ Ω·cm or less. range. Note that the electrical resistivity of the conductive fiber is measured by the method described in Examples.

Since the conductive fiber has high conductivity and moldability that allows processing into small fiber diameters, it may be microfibers with a fiber diameter of preferably 10 μm or less, more preferably 8 μm or less. can.

In one embodiment of the present invention, the method for producing a conductive fiber includes the method of manufacturing a conductive fiber comprising the thermoplastic resin (A), the carbon black (B), and the metal phthalocyanine (C). A manufacturing method, comprising: melting at least the thermoplastic resin (A), the carbon black (B), the metal phthalocyanine (C), and a thermoplastic resin (D) other than the thermoplastic resin (A). Step 1 of kneading to obtain a thermoplastic resin composition; Step 2 of melt-spinning the thermoplastic resin composition; and a solvent that dissolves the thermoplastic resin (D) but does not dissolve the thermoplastic resin (A). contacting the thermoplastic resin (D) to selectively remove the thermoplastic resin (D) to obtain conductive fibers, the carbon black (B) having a pH of 5 or more. The content of the metal phthalocyanine (C) based on 100 parts by mass of the carbon black (B) in the conductive fiber is in the range from 0.1 parts by mass to 50 parts by mass, and the thermoplastic resin ( The total blending amount of the carbon black (B) and the metal phthalocyanine (C) in the total blending amount of A), the carbon black (B), and the metal phthalocyanine (C) is from 5% by mass or more to 20% by mass or less. The fiber diameter is 10 μm or less.

In the step 1, the carbon black (B) preferably has a particulate shape. The average particle size is preferably in the range of 30 nm or less, more preferably 28 nm or less, still more preferably 25 nm or less, from the viewpoint of developing formability that enables processing into small fiber diameters and from the viewpoint of developing high conductivity. It is. Although the lower limit of the average particle diameter range is not particularly set, it is preferably 10 nm or more, more preferably 15 nm or more, and still more preferably 18 nm or more.

In the step 1, the shape of the metal phthalocyanine (C) is preferably particulate. The average particle size is not particularly limited, but from the viewpoint of developing formability that enables processing into small fiber diameters and from the viewpoint of developing high conductivity, the average particle size is preferably 10 nm or more, more preferably 30 nm or more. , more preferably from 40 nm or more to 800 nm or less, more preferably 500 nm or less, even more preferably 300 nm or less.

The thermoplastic resin (D) is not particularly limited as long as it is a thermoplastic resin that can be selectively removed in step 3, and examples thereof include polyethylene, polypropylene, polystyrene, and the like.

In step 1, the blending ratio of the thermoplastic resin (D) to 100 parts by mass of the total blend of the thermoplastic resin (A), the carbon black (B), and the metal phthalocyanine (C) is not particularly limited; The amount ranges from preferably 50 parts by weight or more, more preferably 70 parts by weight or more, to preferably 100 parts by weight or less, more preferably 90 parts by weight or less.

In the step 1, the thermoplastic resin (A), the carbon black (B), the metal phthalocyanine (C), the thermoplastic resin (D), and the other optional raw material components as necessary. The colorant and the other additives (hereinafter simply referred to as "optional raw material components") are premixed as necessary in various forms such as bulk, pellets, and chips, and then melt-kneaded. The mixture is put into a machine and heated to a temperature higher than the melting point of the thermoplastic resin (A) and the thermoplastic resin (D) to melt and knead. The form of the melt-kneaded product is not particularly limited as long as it does not impair the effects of the present invention, and it can be submitted to step 2 described below in a molten state, but it can be extruded into strands and then cut into pellets or chips. It is preferable to make it into granules such as.

In the step 1, the premixing is not particularly limited as long as it does not impair the effects of the present invention, but dry blending using a ribbon blender, Henschel mixer, V blender, etc. can be used. Further, the melt kneading machine is not particularly limited as long as it does not impair the effects of the present invention, but melt kneading machines equipped with a heating mechanism such as a Banbury mixer, a mixing roll, a single-screw or twin-screw extruder, and a kneader can be used. can be mentioned. Note that the melt-kneading machine used in Step 1 may be equipped with a filter having an opening in the range of preferably 100 μm or less, more preferably 50 μm or less, and still more preferably 30 μm or less.

In step 2, the thermoplastic resin composition obtained in step 1 is melt-spun to obtain a conductive material. Further, in the present invention, the conductive material may be stretched.

The solvent used in the step 3 is a solvent that dissolves the thermoplastic resin (D) but does not dissolve the thermoplastic resin (A), and is a solvent that is brought into contact with the thermoplastic resin (D) to dissolve the conductive material. There is no particular limitation as long as the thermoplastic resin (D) can be selectively removed from the resin.

In the present invention, the shape of the fiber is not particularly limited, and may be a so-called filament (long fiber) having a long fiber length, or a so-called staple (short fiber) having a short fiber length. The fiber diameter (diameter) of the fibers varies depending on the use and can be arbitrarily thin, but usually the average diameter is preferably 0.01 μm or more, more preferably 0.05 μm or more, and even more preferably The range is from 0.1 μm or more, most preferably 0.5 μm or more, to 10 μm or less, preferably 8 μm or less, more preferably 3 μm or less, and even more preferably 1 μm or less. Conventionally, it has been difficult to produce fibers with a fiber diameter of 10 μm or less, preferably 8 μm or less (referred to as microfibers in the present invention), which have high conductivity. Microfibers with electrical conductivity can be manufactured.

The present invention will be explained in more detail below based on Examples, but the present invention is not limited by these Examples.

(Example 1)
6-Nylon (“UBE NYLON 1013B” manufactured by Ube Industries, Ltd.) 67% by mass, carbon black (Mitsubishi Chemical Corporation #3050: pH 7.0, volatile content 0.5%, BET specific surface area 50 m ² /g) and 30% by mass of copper phthalocyanine blue (Fastogen Blue PA5380 manufactured by DIC Corporation) were melt-kneaded using a twin-screw extruder to create a masterbatch. They were blended and mixed so that the masterbatch was 16% by mass, low-density polyethylene was 42% by mass, and 6-nylon was 42% by mass, melt-spun at 280° C., and 5 dtex filaments were obtained by drawing 3 times. The polyethylene was eluted from the obtained filament using toluene to prepare a microfiber, and when the resistivity was measured, a conductive thread having a resistivity of 10 ⁶ Ω·cm was obtained.

(Example 2)
6-Nylon (“UBE NYLON 1013B” manufactured by Ube Industries, Ltd.) 72% by mass, carbon black (Tokai Carbon Toka Black #4300: pH 5.0, volatile content 0.7%, BET specific surface area 33 m ² /g) A masterbatch was prepared by melt-kneading raw materials containing 25% by mass of copper phthalocyanine blue (Fastogen Blue PA5380 manufactured by DIC Corporation) and 3% by mass using a twin-screw extruder. They were blended and mixed so that the masterbatch was 16% by mass, low-density polyethylene was 42% by mass, and 6-nylon was 42% by mass, melt-spun at 280° C., and 5 dtex filaments were obtained by drawing 3 times. Microfibers were prepared by eluting polyethylene from the obtained filaments using toluene, and when the resistivity was measured, a conductive thread having a resistivity of 10 ⁶ Ω·cm was obtained.

(Example 3)
6-72% by mass of nylon (“UBE NYLON 1013B” manufactured by Ube Industries, Ltd.), carbon black (HIBLACK40B1 manufactured by Orion Engineered Carbons: pH 8.0, volatile content 1.5%, BET specific surface area 150 m ² /g) A masterbatch was prepared by melt-kneading raw materials containing 25% by mass of copper phthalocyanine blue (Fastogen Blue PA5380 manufactured by DIC Corporation) and 3% by mass using a twin-screw extruder. They were blended and mixed so that the masterbatch was 16% by mass, low-density polyethylene was 42% by mass, and 6-nylon was 42% by mass, melt-spun at 280° C., and 5 dtex filaments were obtained by drawing 3 times. Microfibers were prepared by eluting polyethylene from the obtained filaments using toluene, and when the resistivity was measured, a conductive thread having a resistivity of 10 ⁶ Ω·cm was obtained.

(Comparative example 1)
6-Nylon (“UBE NYLON 1013B” manufactured by Ube Industries, Ltd.) is 70% by mass, carbon black (Mitsubishi Chemical #3050: pH 7.0, volatile content 0.5%, BET specific surface area 50 m ² /g) is 30% by mass. A masterbatch was prepared by melt-kneading the raw materials blended in mass % using a twin-screw extruder. They were blended and mixed so that the masterbatch was 16% by mass, low-density polyethylene was 42% by mass, and 6-nylon was 42% by mass, melt-spun at 280° C., and 5 dtex filaments were obtained by drawing 3 times. Microfibers were prepared by eluting the polyethylene from the obtained filaments using toluene, and when the resistivity was measured, a conductive thread having a resistivity of 10 ¹² Ω·cm was obtained.

(Comparative example 2)
6-67% by mass of nylon (“UBE NYLON 1013B” manufactured by Ube Industries, Ltd.), 30% by mass of carbon black (MA11 manufactured by Mitsubishi Chemical: pH 3.5, volatile content 1.6%, BET specific surface area 92 m ² /g) % and copper phthalocyanine blue (Fastogen Blue PA5380 manufactured by DIC Corporation) at 3% by mass, the raw materials were melt-kneaded using a twin-screw extruder to create a masterbatch. They were blended and mixed so that the masterbatch was 16% by mass, low-density polyethylene was 42% by mass, and 6-nylon was 42% by mass, melt-spun at 280° C., and 5 dtex filaments were obtained by drawing 3 times. Microfibers were prepared by eluting the polyethylene from the obtained filaments using toluene, and when the resistivity was measured, a conductive thread having a resistivity of 10 ¹⁴ Ω·cm was obtained.

Note that the above evaluation results are based on the following measurement examples.

(Measurement example 1) Resistivity A test piece was cut into 2 cm width and 4 cm length. Conductive adhesive was applied to 1.5 cm of both ends in the length direction, and the part was sandwiched between metal electrodes, and a DC voltage of 1 kV was applied. Resistance was measured.

Claims (4)

A conductive fiber formed by blending a thermoplastic resin (A), carbon black (B), and metal phthalocyanine (C),
The carbon black (B) has a pH of 5 or more,
The blending amount of the metal phthalocyanine (C) with respect to 100 parts by mass of the carbon black (B) ranges from 0.1 parts by mass or more to 50 parts by mass or less,
The total blending amount of the carbon black (B) and the metal phthalocyanine (C) in the total blending amount of the thermoplastic resin (A), the carbon black (B), and the metal phthalocyanine (C) is 5% by mass or more. The range is up to 20% by mass,
A conductive fiber having a fiber diameter of 10 μm or less. The conductive fiber according to claim 1, wherein the carbon black (B) contains carbon black having a pH of 5 to 10 and a volatile content of 1.5% or less. The conductive fiber according to claim 1 or 2, having an electrical resistivity in a range from 10 ² Ω·cm to 10 ⁹ Ω·cm. A method for producing a conductive fiber comprising a thermoplastic resin (A), carbon black (B), and metal phthalocyanine (C), the method comprising:
At least the thermoplastic resin (A), the carbon black (B), the metal phthalocyanine (C), and a thermoplastic resin (D) other than the thermoplastic resin (A) are melt-kneaded to form a thermoplastic resin. Step 1 of obtaining a composition;
Step 2 of melt-spinning the thermoplastic resin composition;
A solvent that dissolves the thermoplastic resin (D) but does not dissolve the thermoplastic resin (A) is brought into contact with the thermoplastic resin (D) to selectively remove the thermoplastic resin (D) and thereby conduct the thermoplastic resin (D). Step 3 of obtaining sexual fibers,
The carbon black (B) has a pH of 5 or more,
The amount of the metal phthalocyanine (C) mixed with respect to 100 parts by mass of the carbon black (B) in the conductive fiber is in the range of 0.1 parts by mass or more and 50 parts by mass or less,
The total blending amount of the carbon black (B) and the metal phthalocyanine (C) in the total blending amount of the thermoplastic resin (A), the carbon black (B), and the metal phthalocyanine (C) is 5% by mass or more. A method for producing conductive fibers having a fiber diameter of 10 μm or less, in a range of up to 20% by mass.