JPH08337925A - Conductive acrylic fiber and method for producing the same - Google Patents

Abstract

(57) [Abstract] [Problem] It has excellent conductivity and whiteness, and can be applied to a wide range of applications such as sweaters.
Provided is a conductive acrylic fiber having excellent processability. An organic solvent solution of an acrylonitrile copolymer containing 15 to 70% by volume of a conductive substance having an electric conductivity of 10 ⁻³ S / cm or more with respect to an acrylonitrile copolymer is used as a core, and an acrylonitrile system is used. An organic solvent solution of the copolymer is placed in the sheath, and spinning is performed so that the area ratio of the core to the sheath of the core-sheath composite spinneret is core / sheath = 5/95 to 60/40. Then, after being stretched, it is heated to 5 to 5 by heat treatment.
By shrinking 0%, core / sheath = 5 / 95-6
A conductive acrylic fiber having a core portion having a cross-sectional area of 7 μm ² or more and having a core portion containing a conductive substance having a conductivity of 10 ⁻³ S / cm or more of 15 to 70% by volume. obtain.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive acrylic fiber having excellent conductivity, whiteness and yarn strength, which can be widely applied to clothing such as sweaters, and a method for producing the same.

[0002]

2. Description of the Related Art Generally, synthetic fibers are electrically insulating, and static electricity generated by contact or friction does not easily leak. As a result, various problems such as (1) clinging to clothes, (2) adhesion of dirt, (3) flammable gas caused by static electricity charged on clothes, ignition of dust, explosion, and (4) malfunction of electronic devices cause. Especially, with the spread of electronic devices such as personal computers, the obstacle (4) has been highlighted in recent years.

In particular, acrylic fibers have a drawback that they are more likely to be charged with static electricity than other fibers, and are apt to cause the above-mentioned various problems. Therefore, acrylic fibers have a particularly high antistatic property, that is, electrical conductivity. Is required.

As a technique for imparting conductivity to acrylic fibers, fibers obtained by mixing carbon black in a spinning dope and spinning the fibers have been proposed in the past. However, whiteness and color development are required from the aspect of hue for clothing applications. Is difficult to adapt to.

Further, as a method for improving these hues to a white color, there is a method using a metal oxide typified by tin oxide, and an example of application to acrylic fiber is JP-A-59-2.
No. 23309, Japanese Patent Laid-Open No. 57-39213 and the like. The technique disclosed in JP-A-59-223309 for mixing and spinning an acrylic polymer solution and an elastic polymer solution in which conductive fine particles are dispersed contains conductive fine particles phase-separated from the acrylic polymer. Since the elastic polymer is exposed on the fiber surface, high conductive performance can be obtained, but in the spinning process, conductive fine particles adhere to the spinning nozzle, resulting in unevenness of fineness or defective ejection direction of the nozzle.
There is an industrial problem that polymer peeling, guide wear, and conductive fine particles fall off in all processes from spinning to spinning.

[0006] A conductive composite fiber disclosed in JP-A-57-39213, which is obtained by composite spinning a polymer solution in which titanium oxide having a conductive film is dispersed and a polymer solution in which titanium oxide is not dispersed into a core-sheath form. Then, when the core-sheath form is selected, the conductive performance is not sufficient although the above-mentioned drawbacks are not present.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a conductive acrylic fiber having excellent conductivity, excellent whiteness and excellent processability, and a method for producing the same. To do. The present inventors have arrived at the present invention as a result of diligent studies in order to eliminate the above-mentioned drawbacks of the prior art in conductive acrylic fibers.

[0008]

That is, the first aspect of the present invention
The gist of is a core-sheath composite fiber in which both the core and the sheath are made of an acrylonitrile-based copolymer, and the area ratio of the core and the sheath in the fiber cross section is core / sheath = 5/95 to 60/40, 1 core of conductive material with conductivity of 10 ^-3 S / cm or more
5 to 70% by volume and the core has a cross-sectional area of 7 μm ²
A second aspect of the present invention is a conductive acrylic fiber characterized in that the conductive substance having a conductivity of 10 ⁻³ S / cm or more is added to an acrylonitrile-based copolymer in an amount of 15 to 7%.
The area ratio of the core and the sheath of the core-sheath composite spinneret was obtained by arranging the organic solvent solution of the acrylonitrile copolymer containing 0% by volume in the core and the organic solvent solution of the acrylonitrile copolymer in the sheath. To give a core / sheath = 5/95 to 60/40, followed by drawing and then heat treatment to 5
The method for producing a conductive acrylic fiber is characterized by shrinking by 50%.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in detail below. In the present invention, the acrylic polymer constituting the core component and the sheath component is not particularly limited as long as it is an acrylic copolymer usually used for producing acrylic fibers. In addition, the acrylic polymer constituting the core component and the sheath component may have the same composition or different compositions, but the monomer composition should contain at least 50% by weight of acrylonitrile. is necessary. When the acrylonitrile composition ratio is less than 50% by weight in the monomer composition, the obtained fiber does not exhibit the original characteristics of the acrylic fiber and is not suitable for the purpose of the present invention.

The monomer to be copolymerized with acrylonitrile is not particularly limited as long as it is a monomer which constitutes an acrylic polymer which usually constitutes an acrylic fiber, and examples thereof include methyl acrylate and ethyl acrylate. Isopropyl acrylate, n-butyl acrylate, 2-acrylic acid
Acrylic esters represented by ethylhexyl, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, etc., methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate. , N-hexyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, and other methacrylic acid esters, and further acrylic acid, methacrylic acid, maleic acid, itaconic acid, acrylamide. , N-methylolacrylamide, styrene, vinyltoluene, vinyl acetate, vinyl chloride, vinylidene chloride, vinyl bromide, vinylidene bromide, vinyl fluoride, vinylidene fluoride, etc. It is.

Further, p-sulfophenyl methallyl ether, methallyl sulfonic acid, allyl sulfonic acid, styrene sulfonic acid, 2-acrylamido-
Copolymerization of 2-methylpropanesulfonic acid and an alkali salt thereof is preferable for improving dyeability.

In the present invention, the degree of polymerization of the acrylic polymer is not particularly limited, but 0.1 g of the polymer is dissolved in 100 ml of dimethylformamide containing 0.1N sodium rhodanate, and the specific viscosity is measured at 25 ° C. The converted molecular weight is preferably in the range of 100,000 to 1,000,000.
If the molecular weight is less than this range, the spinnability tends to deteriorate and the yarn quality of the raw yarn tends to decrease remarkably. If the molecular weight exceeds 1 million, the concentration of the polymer which gives the optimum viscosity of the spinning dope is low. The productivity tends to decrease.

The conductive material contained in the core component is a metal oxide having a high whiteness and a powdery conductivity of 10 ⁻³ S / cm or more. Examples of such a conductive material include tin oxide. , Zinc oxide, indium oxide, and titanium oxide whose surface is coated with tin oxide or zinc oxide. As a method of using an additive that further enhances conductivity, tin oxide, indium oxide, antimony oxide, and zinc oxide can be used. On the other hand, a method of using a metal oxide such as aluminum, potassium, isodymium, germanium or tin in combination can be mentioned.

The form of the conductive substance is not particularly limited, but when it is granular, it is preferable that the average particle size is 3 μm or less from the viewpoint of stability in the filtration process and spinning process of the stock solution. Further, from the viewpoint of improving conductivity, needle-like particles having a larger aspect ratio than particles are preferable. The content of the conductive substance varies depending on the form and type of particles and the required conductivity, but in the case of particles, it is 20 to 70% by volume with respect to the core, and in the case of needles, the content of the core is 15 to 70% by volume. 70% by volume
Is. When the content is less than the above range, the electroconductivity is insufficient, and when it exceeds the above range, spinning stability and drawability in the subsequent step are deteriorated and sufficient yarn quality cannot be obtained.
Good conductivity here means that the conductivity of single fiber is 10 ^-6.
It is S / cm or more and the surface resistivity is 10 ⁹ Ω or less.

In the conductive acrylic fiber of the present invention, in the fiber cross section, the area ratio of the core portion to the sheath portion is 5/9.
It is necessary to be 5 to 60/40, and more preferably 10/90 to 50/50. When the proportion of the core portion is less than 5%, the conductive performance is not sufficient even if the conditions described later are satisfied. On the other hand, if it exceeds 60%, a complete core-sheath structure cannot be obtained and the core portion is exposed to the fiber surface in many portions, which is not preferable.

In the conductive acrylic fiber of the present invention, the area of the core portion in the above-mentioned fiber cross section, that is, the absolute value of the cross-sectional area of the core portion is important and needs to be 7 μm ² or more. When the thickness is less than 7 μm ² , the conductivity which is the object of the present invention is not sufficient even if other conditions are satisfied.

Further, in the antistatic acrylic fiber of the present invention, it is particularly preferable that the sheath has a thickness of 3 μm or less at least at one location in the fiber cross section. This thickness is 3μ
If there is no place below, the voltage required for dielectric breakdown becomes high and the conductivity becomes insufficient. An eccentric core-sheath composite form in which the core is unevenly distributed near the fiber surface, and a core-sheath composite fiber with a flat fiber cross section is the voltage (dielectric breakdown voltage) required to flow electricity beyond the sheath that is an insulator. Is effective in reducing the

In particular, in the fiber cross section shown in FIGS. 1 and 2, the length (A) between both ends and the thickness (C) of the constricted portion are A /
The flat core-sheath composite fiber in which C is 2 to 7 has an area ratio between the core part and the sheath part which is larger than that of the core-sheath composite fiber in which the core part is eccentric,
The conductive material content and the minimum thickness of the sheath are well balanced, the conductive performance is best exhibited, and also the flexibility due to the flatness is combined, and in terms of manufacturing, stable control due to the control of the thickness of the sheath is achieved. The most preferable in terms of spinnability and expression of constant conductivity.

By the way, when exposed to the fiber surface as represented by the side-by-side type, generally, although high conductive performance is obtained, abrasion of various guides and fluffing of fibers in each process from spinning to spinning, and further from fibers However, such a problem occurs that the conductive substance is dropped off, which makes it difficult to industrially and stably produce it. Especially in the case of solution spinning,
Since the residual solvent is significantly diffused from the fiber surface in the drawing or solvent removal step, the conductive portion is apt to be cut, which is not preferable from the viewpoint of the conductive performance. The allowable exposure amount of the core portion to the fiber surface is 10% or less, preferably 5% or less, and more preferably 1% or less with respect to the fiber surface.

The conductive acrylic fiber of the present invention can be obtained, for example, by the following production method. The spinning stock solution that forms the core is prepared by adjusting the acrylonitrile copolymer to be 5 to 25% by weight, and further the conductive material is added to the spinning stock solution in a volume ratio of the conductive material and the acrylonitrile copolymer of 15 / 85-
The spinning stock solution, which is added and adjusted to 70/30 to form the sheath, contains 20 to 40 acrylonitrile-based copolymer.
Prepare separately so that the weight% is obtained. The solvent used at this time is not particularly limited, but for example, nitric acid (aqueous solution), aqueous solution of zinc chloride, inorganic solvent of aqueous solution of rhodanate, dimethylformamide, dimethylacetamide, dimethylsulfoxide, ethylene carbonate, γ-butyrolactone, and acetone. Organic solvents are convenient. There is no particular problem even if the solvent is different in the core portion and the sheath portion, but it is preferable that they are the same from the viewpoint of solvent recovery.

Further, for the purpose of improving various performances of the final fiber, titanium oxide or the like is added to a stock solution for forming a sheath portion for improving whiteness, or a hydrophilic compound is added to a core portion for further improving conductivity. It is possible to add a rubber-like component.

The two spinning stock solutions which respectively form the core and the sheath are shaped into a fiber form by a core-sheath composite spinneret to obtain undrawn yarn. At this time, when selecting wet type or dry type,
By using the core-sheath composite spinneret in which the core discharge holes are eccentric, it is possible to easily satisfy the above-described conditions of the sheath thickness. When spinning a fiber with a high content of conductive substances, a dry method capable of high draft spinning using a spinneret with a large pore size,
Dry and wet methods are preferred.

The undrawn yarn is 2 to 7 in hot water of 70 ° C. or higher.
The film is stretched twice and desolvated, and then dried and subjected to a relaxation heat treatment to shrink it by 5 to 50%. Hot water temperature during stretching is 70
If the temperature is lower than 0 ° C, a sufficient draw ratio cannot be obtained, and the obtained fiber tends to have insufficient yarn quality. Similarly, if the draw ratio is less than 2 times, sufficient yarn quality cannot be obtained, and if it exceeds 7 times, yarn breakage frequently occurs and the core portion is cut off, which lowers the conductive performance, which is not preferable. The above drying and relaxation heat treatment are conventionally used for producing acrylic fibers, drying and annealing by a heat roll or net process,
Relaxation methods such as hot plate relaxation and steam relaxation can be performed alone or in combination. The shrinkage ratio in the relaxation heat treatment is 5% or more, preferably 10% or more in order to secure good dyeability or yarn quality required for spinning and knitting.

Next, the most suitable production method for obtaining the conductive acrylic fiber having the most preferable flat cross section of the conductive acrylic fiber of the present invention will be described. As described above, in the fiber cross section, the length between both ends (A), the tip maximum portion (B), and the constricted portion thickness (C) are flat with A / C of 2 to 7 and B / C of 1 or more. The core-sheath composite fiber has a balanced area ratio of the core portion to the sheath portion, the content of the conductive substance, and the minimum thickness of the sheath portion, and the conductive performance is best exhibited, and the flexibility due to the flatness is also obtained. Most preferable to have both,
This cross-sectional form is a core-sheath of the organic solvent solution of the acrylonitrile copolymer containing 15 to 70% by volume of the conductive substance of the acrylonitrile copolymer, and the organic solvent solution of the acrylonitrile copolymer of the same. The core and the sheath of the composite spinneret are discharged into an inert gas so that the area ratio of the core to the sheath is within the above range, and the obtained coagulated yarn is washed and drawn, and then heat treated. 5% to 50%
Obtained by contracting.

Here, the temperature of the inert gas is not particularly limited, but 160 to 400 ° C. is important for forming a cross section having A / C of 2 to 7 and B / C of 1 or more. Further, the coagulated yarn is subjected to washing and drawing and then subjected to heat to shrink by 5 to 50% so that the distance between the conductive substances of the core portion is reduced and the acrylic fiber is provided with sufficient conductivity. In addition, it is necessary to secure good dyeability or yarn quality required for spinning and knitting.

[0026]

The present invention will be described in detail with reference to the following examples.
In the examples, the measurement was performed by the following method. (Surface resistivity of fibers) Single fibers were taken out from the fiber bundle, accurately separated by 1 cm, and bonded to a metal terminal with silver paste (Doutite manufactured by Fujikura Kasei Co., Ltd.). A DC voltage of 1000 V was applied between the terminals at 20 ° C. and a relative humidity of 40 RH%, and the resistance value R _S (Ω) between the terminals was measured with a super insulation meter (SM-8210 manufactured by Toa Denpa Co., Ltd.). From this, the surface resistivity σ (Ω) was obtained by the following equation. σ = 3.7 × 10 ⁻³ × R _S × (d / ρ) ^1/2 where d is the fineness and ρ is the specific gravity of the fiber.

(Conductivity of Fiber) A single fiber was taken out from the fiber bundle, cut exactly into 1 cm, and the end portion was bonded to a metal terminal with silver paste (Doutite manufactured by Fujikura Kasei Co., Ltd.). A DC voltage of 1000 V was applied between the terminals at 20 ° C. and a relative humidity of 40 RH%, and the resistance value R _V (Ω) between the terminals was measured by a super insulation meter (SM-82 manufactured by Toa Denpa Co., Ltd.).
It was measured according to 10). From this, the conductivity ζ (S / c
m) was calculated by the following equation. ζ = 1 / (1.11 × 10 ⁻⁶ × R _V × (d / ρ)) where d is the fineness and ρ is the specific gravity of the fiber.

(Minimum thickness of sheath, ratio of sheath / core) The minimum thickness of sheath, the ratio of sheath / core, and the cross-sectional area of the core were measured from a micrograph of the cross section of the fiber and determined as average values.

Comparative Example 1 An acrylic polymer (molecular weight: 160,000) consisting of 93.5% by weight of acrylonitrile, 6.0% by weight of methyl acrylate and 0.5% by weight of sodium methallyl sulfonate was dissolved in dimethylformamide. Then, a spinning solution (a) having a polymer concentration of 30% by weight was obtained.

Further, the grain size is 0.2 to 0.3 μ, and the conductivity is 0.
16 parts by weight of 4 S / cm granular conductive titanium oxide (ET-500W manufactured by Ishihara Sangyo Co., Ltd.) was dispersed in 100 parts by weight of a spinning dope having the same composition as the spinning dope (a) to prepare a spinning dope (b).
Was prepared. B was used as the spinning dope for forming the core, and a was used as the spinning dope for forming the sheath.

After heating the spinning dope separately to 130 ° C.,
The mixture was discharged into an inert gas at 230 ° C. using a core-sheath spinneret having a hole number of 400 and a hole diameter of 0.2 mmφ. The unstretched yarn obtained is subsequently stretched 3.75 times in hot water at 100 ° C.,
Furthermore, it wash | cleaned in 95 degreeC hot water. The obtained fiber bundle was dried and relaxed at a relative humidity of 40% and a temperature of 150 ° C. in a non-tensed state, and contracted by 20%. The obtained fiber has a fineness of 3
It was denier. The surface resistivity and the fluff generation state were evaluated and are shown in Table 1.

(Examples 1, 2 and Comparative Examples 2 and 3) The spinning stock solution (c) prepared as follows was used instead of the spinning stock solution (b) as the spinning stock solution for forming the core, and the sheath and the core were prepared. A fiber having a fineness of 3 denier was obtained in the same manner as in Comparative Example 1 except that the discharge ratio of the spinning dope was changed. The surface resistivity and the fluff generation state were evaluated and are shown in Table 1. In addition, in Comparative Example 3, the area of the exposed core portion was measured from a micrograph, and the ratio of the surface to the fiber side was shown.

The spinning stock solution (c) was prepared by dispersing 90 parts by weight of granular conductive titanium oxide (ET-500W manufactured by Ishihara Sangyo Co., Ltd.) in 100 parts by weight of the spinning stock solution having the same composition as the spinning stock solution (a).

[0034]

[Table 1]

Comparative Example 4 The same procedure as in Comparative Example 1 was carried out except that the spinning dope (d) prepared as follows was used instead of the spinning dope (b) as the spinning dope for forming the core. A fiber having a fineness of 3 denier was obtained. The surface resistivity and the fluff generation state were evaluated and are shown in Table 2.

The spinning solution (d) is a needle-shaped conductive titanium oxide (FT-20 manufactured by Ishihara Sangyo Co., Ltd.) having a long axis of 2.9 μm, an aspect ratio of 13, and a conductivity of 0.2 S / cm as a conductive substance.
00) 13 parts by weight were dispersed in 100 parts by weight of a spinning dope having the same composition as the spinning dope (a) to prepare 30% by weight of conductive fine particles.

(Examples 3, 4 and Comparative Example 5) A spinning stock solution (e) prepared as follows was used instead of the spinning stock solution (b) instead of the spinning stock solution (b) to spin a sheath and a core. A fiber having a fineness of 3 denier was obtained in the same manner as in Comparative Example 1 except that the discharge ratio of the stock solution was changed. The surface resistivity and the fluff generation state were evaluated and are shown in Table 2.

[0038]

[Table 2]

The spinning solution (e) is a needle-shaped conductive titanium oxide (FT-20 manufactured by Ishihara Sangyo Co., Ltd.) having a major axis of 2.9 μm, an aspect ratio of 13, and a conductivity of 0.2 S / cm as a conductive substance.
00) 30 parts by weight were dispersed in 100 parts by weight of a spinning dope having the same composition as the spinning dope (a).

(Examples 5 and 6) A spinning stock solution (a) was used as a spinning stock solution for forming a sheath, and a spinning stock solution (b) was used as a spinning stock solution for forming a core portion, and a spinneret was used as an ordinary eccentric type core. A fiber having a fineness of 3 denier was obtained in the same manner as in Comparative Example 1 except that the discharge ratio of the spinning dope for the sheath and the core was changed to the sheath composite spinneret. The surface resistivity and the fuzz generation state were evaluated and are shown in Table 3. In addition, in Comparative Example 6, the area of the exposed core portion was measured from the micrograph, and the ratio of the surface to the fiber side was shown.

Example 7 The fineness was the same as in Example 6 except that the spinning solution (a) was used as the spinning solution for forming the sheath and the spinning solution (e) was used as the spinning solution for forming the core. Fibers of 3 denier were obtained. The surface resistivity and the fuzz generation state were evaluated and are shown in Table 3.

Comparative Example 6 A fiber having a fineness of 3 denier was obtained in the same manner as in Example 6 except that the spinneret was replaced with a normal side-by-side type composite spinneret. The surface resistivity and the fuzz generation state were evaluated and are shown in Table 3.

Example 8 An acrylic polymer (molecular weight: 15%) comprising 93% by weight of acrylonitrile, 6.5% by weight of vinyl acetate and 0.5% by weight of sodium methallylsulfonate.
10,000) is dissolved in dimethylacetamide to give a polymer concentration of 2
A spinning dope (f) of 5% by weight was obtained.

Further, the grain size is 0.2 to 0.3 μ, and the conductivity is 0.
75 parts by weight of 4S / cm granular conductive titanium oxide (ET-500W manufactured by Ishihara Sangyo Co., Ltd.) was added to 100 parts of the spinning solution (f).
The solution was dispersed in parts by weight to prepare a spinning dope (g).

An eccentric type core-sheath spinneret having a hole diameter of 0.15 mm and 60 holes is a spinning stock solution (f) as a spinning stock solution for forming a sheath portion, and a spinning stock solution (g) as a spinning stock solution for forming a core portion. After being discharged into the air and traveling in a space of about 7 mm, it was introduced into a 70% by weight dimethylacetamide aqueous solution coagulating bath at 35 ° C. and coagulated. The coagulated yarn is taken from the coagulation bath at a speed of 60 m / min, washed in hot water at 60 ° C., stretched 3 times in hot water at 95 ° C., and after applying an oil agent, 1
Dry on a heating roll at 40 ℃ and use a hot plate at 260 ℃ to
A 0% shrinkage relaxation was performed to obtain an acrylic long fiber having a circular cross section with 180 denier / 60 filaments. The surface resistivity and the fuzz generation state were evaluated and are shown in Table 3.

Example 9 An acrylic polymer (molecular weight: 150,000) consisting of 93% by weight of acrylonitrile and 7% by weight of vinyl acetate was dissolved in dimethylacetamide to prepare a spinning dope (h) having a polymer concentration of 25% by weight. Obtained. Furthermore, granular conductive titanium oxide (ET-500W manufactured by Ishihara Sangyo Co., Ltd.) 75 having a particle size of 0.2 to 0.3 μm and a conductivity of 0.4 S / cm 75
The spinning dope (i) was prepared by dispersing 100 parts by weight of the spinning dope (f).

A spinning stock solution (h) is used as a stock solution for forming a sheath, and a spinning stock solution (i) is used as a stock solution for forming a core. Then, the mixture was discharged into a 55% by weight dimethylacetamide aqueous solution coagulation bath at 40 ° C. for coagulation. The coagulated yarn is taken from the coagulation bath at a speed of 8 m / min, washed in boiling water, stretched 5 times in hot water at 95 ° C., and after applying an oil agent, 14
It was dried with a heating roll at 0 ° C., shrinkage was relaxed by 20% with saturated steam of 3.0 kg / cm ² , and an acrylic fiber having a round cross section of 3 denier was obtained. The surface resistivity and the fuzz generation state were evaluated and are shown in Table 3.

[0048]

[Table 3]

[0049]

EFFECT OF THE INVENTION The conductive acrylic fiber of the present invention has excellent conductivity, whiteness and yarn strength, and can be widely used mainly for clothing such as sweaters. Furthermore, according to the method for producing a conductive acrylic fiber of the present invention, it is possible to produce, with high productivity, one of the above-mentioned conductive acrylic fibers which is excellent in wrinkle performance.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a cross section of a conductive acrylic fiber of the present invention having a flat cross section.

[Explanation of symbols] 1 sheath part 2 core part A length between both ends B tip maximum thickness C constriction thickness

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akemi Kitani 20-1 Miyuki-cho, Otake-shi, Hiroshima Mitsubishi Rayon Co., Ltd. Otake Works (72) Inventor Hiroshi Hosokawa 20-1 Miyuki-cho, Otake-shi, Hiroshima Mitsubishi Rayon Co., Ltd. Otake Office

Claims (6)

[Claims] 1. A core-sheath composite fiber in which both the core and the sheath are made of an acrylonitrile-based copolymer, and the area ratio of the core and the sheath in the fiber cross section is core / sheath = 5/95 to 60/40. Contains 15 to 70% by volume of a conductive substance having an electric conductivity of 10 ⁻³ S / cm or more in the core, and has a cross-sectional area of the core of 7 μm.
A conductive acrylic fiber characterized by being ² or more. 2. The sheath has a thickness of at least part of 3
The conductive acrylic fiber according to claim 1, which has a thickness of not more than μm. 3. A length (A) between both ends in a fiber cross section,
The thickness (C) of the constricted portion has an A / C of 2 to 7.
Alternatively, the conductive acrylic fiber described in 2. 4. An organic solvent solution of an acrylonitrile-based copolymer containing a conductive substance having an electric conductivity of 10 ⁻³ S / cm or more with respect to the acrylonitrile-based copolymer in an amount of 15 to 70% by volume, and acrylonitrile as a core. The organic solvent solution of the copolymer is placed in the sheath, and the core-sheath composite spinneret is spun so that the area ratio of the core to the sheath is 5/95 to 60/40. Then, after being stretched, a heat treatment is performed for 5 to 5
A method for producing a conductive acrylic fiber, which comprises shrinking by 0%. 5. A length (A) between both ends in a fiber cross section,
So that the thickness (C) of the necked portion is A / C of 2 to 7,
The method for producing a conductive acrylic fiber according to claim 4, wherein the organic solvent solution disposed in the core portion and the sheath portion is discharged from the core-sheath composite spinneret into an inert gas for spinning. 6. After spinning, 2 to 2 in hot water of 70 ° C. or higher
The method for producing a conductive acrylic fiber according to claim 4, wherein the conductive acrylic fiber is stretched 7 times.