JP2020165044A - Conductive composite fiber and method for producing the same - Google Patents

Abstract

To provide a conductive composite fiber having excellent conductive performance and conductive performance uniform in the longitudinal direction.SOLUTION: A conductive composite fiber comprises a non-conductive component containing a thermoplastic polymer and a conductive component containing a thermoplastic polymer and 10 to 40 mass% of conductive particles. The electric resistance value of the conductive composite fiber is 1×104 to 1×1010 Ω/cm, and the CV value of the electric resistance value in the longitudinal direction of the fiber is 6%. The elongation of the conductive composite fiber is preferably 50% or more and 90% or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a conductive composite fiber and a method for producing the same.

Conventionally, conductive composite fibers having excellent conductive performance have been known (for example, Patent Document 1). In such conductive composite fibers, various studies have been made to suppress variations in conductive performance in the longitudinal direction. A conductive composite fiber in which variation in conductive performance in the longitudinal direction is suppressed is preferable because when used in a woven or knitted fabric, the overall conductivity becomes uniform.

Japanese Unexamined Patent Publication No. 2004-44071

However, in the conductive composite fiber of Patent Document 1, there is room for improvement in the variation in the conductive performance in the longitudinal direction.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, to have excellent conductive performance, to suppress variations in conductive performance in the longitudinal direction, and to have uniform conductive performance. The purpose is to obtain fibers.

According to the present inventor, the conductive composite fiber obtained by composite spinning under specific conditions has excellent conductive performance, the variation in conductive performance in the longitudinal direction is suppressed, and the conductive composite fiber has uniform conductive performance. It was found that the present invention was completed.

That is, the gist of the present invention is the following (1) to (9).
(1) A conductive composite fiber composed of a non-conductive component containing a thermoplastic polymer and a conductive component containing the thermoplastic polymer and conductive particles in an amount of 10 to 40% by mass, and the electricity of the conductive composite fiber. A conductive composite fiber having a resistance value of 1 × 10 ⁴ to 1 × 10 ¹⁰ Ω / cm and a CV value of 6% of the electrical resistance value in the longitudinal direction of the fiber.
(1) The conductive composite fiber of (1) having thread spots of 3.5% or less.
(3) The conductive composite fiber of (1) or (2) having an elongation of 50% or more and 90% or less.
(4) The conductive composite fiber according to any one of (1) to (3), which has a boiling water shrinkage rate of 3% or more and 20% or less.
(5) A method for producing a conductive composite fiber, which comprises the following steps (a) to (c) in this order.
(A) A step of preparing a non-conductive component containing a thermoplastic polymer and a conductive component containing a thermoplastic polymer and conductive particles.
(B) A step of composite spinning the conductive component and the non-conductive component.
(C) The process of picking up with the first pick-up roller and then picking up with the second pick-up roller.
However, the take-up speed of the first take-up roller shall be 4000 to 6000 m / min, the speed ratio between the first take-up roller and the second take-up roller shall be 1.0 or more and 1.1 or less, and after being picked up by the second take-up roller, it is substantially No stretching is applied.
(6) The method for producing a conductive composite fiber according to (5), wherein the spinning temperature in step (b) is 250 to 310 ° C.
(7) A woven or knitted fabric containing the conductive composite fiber according to any one of (1) to (4).
(8) Clothing including the woven and knitted fabric of (7).
(9) A brush containing the conductive composite fiber according to any one of (1) to (4).

The conductive composite fiber of the present invention has excellent conductive performance by setting the take-up speed of the first take-up roller and the speed ratio between the first take-up roller and the second take-up roller within a specific range after the composite spinning. However, since the variation in the conductive performance in the longitudinal direction is suppressed and the conductive performance is uniform, it can be suitably used for a woven or knitted fabric or a brush that requires the conductive performance.

It is a schematic diagram which shows an example of the composite form in the conductive composite fiber of this invention. It is a schematic diagram which shows an example of the composite form in the conductive composite fiber of this invention. It is a schematic diagram which shows an example of the composite form in the conductive composite fiber of this invention. It is a schematic diagram which shows an example of the composite form in the conductive composite fiber of this invention.

Hereinafter, the present invention will be described in detail.
The conductive composite fiber of the present invention comprises a non-conductive component containing a thermoplastic polymer and a conductive component containing 10 to 40% by mass of the thermoplastic polymer and conductive particles.

As the thermoplastic polymer in the non-conductive component, a polyester resin is preferable. Of these, polyethylene terephthalate (hereinafter referred to as PET resin) obtained by copolymerizing isophthalic acid as a copolymerization component is more preferable. As a result, the flexibility of the polymer is improved, the spinning process can be smoothly performed, the arrangement state (structure) of the conductive particles can be further improved, and the variation in the conductive performance in the longitudinal direction is suppressed. It can have uniform conductive performance.

The copolymerization amount of isophthalic acid in the thermoplastic polymer forming the non-conductive component is preferably 5 to 15 mol%, more preferably 6 to 12 mol%. If the copolymerization amount is less than 5 mol%, the flexibility of the polymer is low and the spinnability may be deteriorated during high-speed spinning. On the other hand, if it exceeds 15 mol%, the amorphous property becomes too high, and it becomes difficult to control the boiling water shrinkage rate, and it may be difficult to suppress the variation in the conductive performance in the longitudinal direction.

The intrinsic viscosity (IV) of the thermoplastic polymer forming the non-conductive component is preferably 0.50 to 0.80, more preferably 0.60 to 0.70. If the IV is less than 0.50, the granulation property of the polymer deteriorates, and it may be difficult to pelletize the polymer. If IV exceeds 0.80, the fluidity and crystallinity of the polymer may deteriorate, and the conductive performance may be inferior.

Additives such as a matting agent, a pigment, a coloring agent, a stabilizer, and an antistatic agent can be added to the thermoplastic polymer contained in the non-conductive component.

The content of the thermoplastic polymer in the non-conductive component is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 100% by mass.

As the thermoplastic polymer in the conductive component, a polyester resin is preferable. Among them, polyethylene terephthalate (hereinafter referred to as PET), polyethylene oxybenzoate, polybutylene terephthalate (hereinafter referred to as PBT) and the like can be mentioned. PBT is particularly preferable. Since the PBT resin is a highly crystalline resin, it is possible to exhibit relatively high conductive performance with a relatively low content of conductive particles. Further, it may be a copolymer or a modified product of these polymers depending on the purpose.

In addition, other copolymerization components can be contained within a range that does not impair the crystallinity of PBT, for example, phthalic acid, 1.3-propanediol, sebacic acid, dimer acid, dodecanedioic acid, xylylene glycol, and the like. Examples thereof include polytetramethylene glycol and polyethylene glycol.

The intrinsic viscosity (IV) of the copolymerized PET forming the conductive component is preferably 0.4 to 0.8. When the IV is less than 0.4, the fluidity of the polymer is increased and the dispersibility of the conductive particles in the polymer is improved, but the subsequent granulation property is deteriorated and it may be difficult to pelletize. is there. If IV exceeds 0.8, the fluidity or crystallinity of the polymer may deteriorate, and the conductive performance may be deteriorated.

Additives such as matting agents, pigments, colorants, stabilizers and antistatic agents can also be added to the thermoplastic polymer in the non-conductive fibers.

Examples of the conductive particles used for the conductive component include conductive carbon black, metal powder (silver, nickel, copper, iron, tin or alloys thereof, etc.), copper sulfide, copper iodide, zinc sulfide, cadmium sulfide, etc. Metal compounds of. In addition, a small amount of antimony oxide is added to tin oxide, and a small amount of aluminum oxide is added to zinc oxide to obtain conductive particles. Further, those obtained by coating the surface of titanium oxide with tin oxide and mixing and firing antimony oxide to obtain conductive particles can also be used. Among them, carbon black (acetylene black, ketjen black, etc.) having conductivity is used because it is generally used for improving the performance of conductive fibers and is less likely to inhibit the fluidity of the polymer as compared with other metal particles. preferable.

The above-mentioned conductive particles are not particularly limited, but those having a specific resistance value of 1 × 10 ⁴ Ω / cm or less are preferable, and those having a specific resistance value of 1 × 10 ² Ω / cm or less are more preferable. If the specific resistance is used in excess of 10 ⁴ Ω / cm, in order to obtain the desired conductive performance, there may be necessary to disperse a large amount of conductive particles in the polymer adversely affect the fiber properties Not only that, it can also cause problems with spinnability.

The particle size of the conductive particles is not particularly limited, but the average particle size is preferably 1 μm or less, and more preferably 0.5 μm or less. If the average particle size exceeds 1 μm, the dispersibility of the conductive particles in the polymer tends to deteriorate, and the fibers tend to have deteriorated properties such as conductivity performance and strong elongation.

The content of the conductive particles in the conductive component is 10 to 40% by mass, more preferably 15 to 35% by mass in the conductive component. If the content is less than 10% by mass, the conductive performance may be insufficient, and if it exceeds 40% by mass, it may be difficult to disperse the conductive particles in the polymer, which is not preferable.

Further, the conductive component and the non-conductive component may be used as a dispersant such as waxes, polyalkylene oxides, various surfactants, organic electrolytes, and antioxidants, as long as the effects of the present invention are not impaired. Agents, stabilizers such as UV absorbers, colorants, pigments, fluidity improvers, and other additives can also be added.

In the composite fiber of the present invention, the composite ratio of the non-conductive component and the conductive component is preferably 60 to 90% by mass for the non-conductive component and 40 to 10% by mass for the conductive component. It is more preferable that the conductive component is 70 to 85% by mass and the conductive component is 30 to 15% by mass. If the composite ratio of the conductive components is less than 10% by mass, the conductive performance may not be sufficient, while if the composite ratio of the conductive components exceeds 40% by mass, the yarn quality performance such as strong elongation characteristics is inferior. May adversely affect spinnability.

Next, the composite form of the conductive composite fiber of the present invention will be described with reference to the drawings. The composite form is not particularly limited, but it is preferably a cross-sectional shape as shown in FIGS. 1 to 4.

First, FIG. 1 shows a type in which the non-conductive component 2 is divided by the conductive component 1. The number of rows of the conductive components may be one or a plurality, but it is preferably 2 to 8. FIG. 1 shows three columns and intersecting ones. FIG. 2 shows a type in which a part of the conductive component 1 is exposed on the fiber surface, and the exposed conductive component 1 may be at one place or at a plurality of places, but preferably 2 to 8 places. It is exposed in places. FIG. 2 shows the conductive components exposed at three locations. FIG. 3 shows a type in which a part of the conductive component 1 is exposed on the fiber surface, and the conductive component 1 is exposed at four places. FIG. 4 shows a type in which the conductive component 2 and the non-conductive component 1 exhibit a core-sheath structure, and the conductive component 1 covers the fiber surface as a sheath portion.

(Physical properties)
The conductive performance of the conductive composite fiber of the present invention has an electric resistance value of 1 × 10 ⁴ to 1 × 10 ¹⁰ Ω / cm. If the electrical resistance value of the composite fiber exceeds 1 × 10 ¹⁰ Ω / cm, the conductive performance becomes insufficient. On the other hand, if it is attempted to be less than 1 × 10 ⁴ Ω / cm, it is necessary to contain a large amount of conductive particles in the polymer, which not only adversely affects the physical properties of the fiber but also causes a problem in the spinnability.

Above all, the electric resistance value is preferably 1 × 10 ⁵ Ω / cm to 1 × 10 ⁹ Ω / cm. By setting the value to 1 × 10 ⁹ Ω / cm or less, it is possible to almost eliminate the charge when the obtained woven or knitted fabric or brush is used in a normal environment. Further, by setting it to 1 × 10 ⁵ Ω / cm or more, the possibility of causing problems in both fiber physical properties and spinnability is reduced.

The electric resistance value in the present invention is measured as follows according to the AATCC76 method.
First, one conductive composite fiber is cut in the longitudinal direction, and 10 samples having a length of 15 cm are collected. Conductive paste (manufactured by Fukuda Denshi Co., Ltd., trade name "keratin cream", model "OJE-01D") is applied to the surfaces at both ends of this sample, and the surface portions at both ends are connected to the metal terminals. Here, the sample is connected to the metal terminal so that the measurement length of the sample is 10 cm (that is, the electrical resistance value in the longitudinal direction of the sample 10 cm is measured). In an environment with a temperature of 20 ° C and a relative humidity of 20% RH, a resistance value measuring device (“SM-10E” manufactured by Toa Denpa Kogyo Co., Ltd.) was used to apply a DC current of 50 V to measure the current value. The electric resistance value was calculated by the following formula.
Electrical resistance = E / (I × L)
E: Voltage (V)
I: Measured current (A)
L: Measurement length (cm)
Then, it is used as the arithmetic mean value of the calculated electrical resistance values of the 10 samples.

Further, from the maximum and minimum electric resistance values of the 10 samples calculated as described above and the arithmetic mean value, the conductivity variation (CV of the electric resistance value in the longitudinal direction of the fiber) calculated from the following formula. In terms of value), the conductive composite fiber of the present invention has a CV value of 6% or less, and more preferably 5% or less. When the CV value of the electrical resistance value in the longitudinal direction of the fiber is 6% or less, it is shown that the variation in the conductive performance in the longitudinal direction is further suppressed and is uniform.

CV (%) = (V / E (X)) × 100 of electrical resistance value in the longitudinal direction of the fiber
V: Square root of the unbiased variance of the electrical resistance value E (X): The average value of the electrical resistance value The unbiased variance is obtained as follows. That is, the difference between the average electric resistance value and the average electric resistance value is obtained for all the test pieces. The sum of the values obtained by squaring these differences is divided by (number of test pieces-1), and the obtained values are used as the unbiased variance.

The thread unevenness of the conductive composite fiber of the present invention is preferably 3.5% or less, and more preferably 3% or less. If the thread unevenness exceeds 3.5%, the above CV value may increase beyond the range of the present invention, that is, the variation in conductive performance in the longitudinal direction may increase.

The elongation of the conductive composite fiber of the present invention is preferably 50% or more and 90% or less, and more preferably 60% or more and 80% or less. If the elongation is less than 50%, the orientation crystallization may proceed too much and cutting threads may occur in the post-process, while if it exceeds 90%, the orientation crystallization may be low and the conductive performance may be low.

The boiling water shrinkage rate of the conductive composite fiber of the present invention is preferably 3% or more and 20% or less, and more preferably 5% or more and 15% or less. If the boiling water shrinkage rate is less than 3%, the fabric may undulate during heat setting due to the difference in boiling water shrinkage rate with the fiber of the composite partner when used in combination with other fibers, while 20%. If it exceeds, the variation in conductive performance may increase due to shrinkage due to heat setting when the fabric is made.

In the conductive composite fiber of the present invention, it is essential to adopt a specific manufacturing method as described later in order to reduce the thread unevenness to 3.5% or less for the purpose of setting the above CV value to 6%. Is. That is, after composite spinning, after picking up with the first pick-up roller at a specific pick-up speed, the speed ratio between the first pick-up roller and the second pick-up roller is set to 1.0 or more and 1.1 or less, and then picked up by the second pick-up roller. In addition, it is essential that the drawing is not substantially stretched after being picked up by the second pick-up roller. Alternatively, the melt viscosities of the conductive component and the non-conductive component at the time of composite spinning can be set in a specific range.

(Production method)
The method for producing a conductive composite fiber of the present invention includes the following steps (a) to (c) in this order.
(A) A step of preparing a non-conductive component containing a thermoplastic polymer and a conductive component containing a thermoplastic polymer and conductive particles.
(B) A step of composite spinning the conductive component and the non-conductive component.
(C) The process of picking up with the first pick-up roller and then picking up with the second pick-up roller.
However, the take-up speed of the first take-up roller shall be 4000 to 6000 m / min, the speed ratio between the first take-up roller and the second take-up roller shall be 1.0 or more and 1.1 or less, and after being picked up by the second take-up roller, it is substantially No stretching is applied.

Regarding the step (a), the method for obtaining the conductive component is not particularly limited, and the method of adding the conductive particles at the polymerization stage of the base polymer and the method of adding the conductive particles to the polymer in the subsequent step. There is a method of melting and kneading. Depending on the polymer used, it may be difficult to add it at the polymerization stage, so a method of melt-kneading in a subsequent step is preferable.

The conductive component and the non-conductive component thus obtained are used and subjected to a treatment such as drying as necessary to form chips. Then, it is subjected to the step (b) to perform composite spinning. The method of composite spinning is not particularly limited, and a normal two-component composite melt spinning apparatus can be used.

In the step (b), the spinning temperature is preferably 250 to 310 ° C., and more preferably + 10 ° C. to + 30 ° C. with respect to the melting point of the resin used. If the spinning temperature is less than 250 ° C., the melt spinning property may be inferior, and if it exceeds 310 ° C., the resin may be decomposed and the physical properties may be deteriorated, or yarn may be cut.

In step (b), it is preferable to set the melt viscosities of the conductive component and the non-conductive component within a specific range. The melt viscosity of the conductive component is preferably 500 to 2800 dPa · S, more preferably 800 to 2400 dPa · S. The melt viscosity of the non-conductive component is preferably 500 to 2600 dPa · S, more preferably 1000 to 2000 dPa · S. By setting the melt viscosities of both in the above range, it becomes suitable for high-speed spinning as described above, thread unevenness can be suppressed, and a composite fiber having more remarkably excellent conductivity variation can be obtained.

In the step (c), the take-up speed of the first take-up roller is 4000 to 6000 m / min, preferably 4000 to 6000 m / min. By setting the take-up speed faster than before, both the conductive component and the non-conductive component are oriented at high speed in the molten state, so that the orientation crystallization of the polymer forming the fiber proceeds appropriately. Therefore, the structure of the conductive particles is developed and the thread unevenness is suppressed, and a composite fiber having remarkably excellent variation in conductivity can be obtained. Further, the boiling water shrinkage rate can be lowered.

In the step (c), the speed ratio between the first take-up roller and the second take-up roller is 1.0 or more and 1.1 or less, and preferably 1.0 or more and 1.05 or less. In the present invention, it is essential that the speed ratio between the first take-up roller and the second take-up roller is set within such a range and is not substantially stretched, and is not substantially stretched in the subsequent steps. As a result, it is possible to suppress thread unevenness and reduce variations in conductive performance.

The woven or knitted fabric of the present invention contains the conductive composite fiber of the present invention. The ratio of the conductive composite fiber of the present invention to the woven or knitted fabric of the present invention is not particularly limited, but is preferably 0.01 to 20% by mass.

In the case of a woven fabric, the woven or knitted fabric of the present invention uses the conductive composite fibers of the present invention for either or both of the warp and the weft, and the conductive composite fibers are arranged in the woven fabric at intervals of 10 mm or less. Those are preferable. More preferably, the interval is 5 mm or less. The weave structure is not particularly limited, and examples thereof include plain weave, twill weave, satin weave, double weave, and leno weave.

In the case of knitted fabric, any of circular knitting, weft knitting, and warp knitting may be used, and in the case of circular knitting and weft knitting, the conductive composite fibers of the present invention shall be inserted in a border shape at intervals of 10 mm or less, preferably 5 mm or less. Is preferable. Also in the case of warp knitting, it is preferable that the conductive composite fibers of the present invention are inserted in stripes at intervals of 10 mm or less, preferably 5 mm or less.

In the woven and knitted fabric of the present invention, the conductive composite fiber of the present invention may be used as it is, or the conductive composite fiber may be twisted and mixed with other fibers. Other fibers are not particularly limited, and examples thereof include synthetic fibers such as polyamide, polyester, and polyethylene, recycled fibers such as rayon, and natural fibers such as cotton, linen, and wool, which are the same as conductive composite fibers. Therefore, polyester fiber is preferable.

Preferred uses of the woven and knitted fabric of the present invention include, for example, various clothes, outdoor products, interior products and the like.

The brush of the present invention uses at least a part of the conductive composite fiber of the present invention. The ratio of the conductive composite fiber of the present invention to the brush of the present invention is not particularly limited, but is preferably 10 to 100% by mass.

The brush of the present invention is suitably used for, for example, a developing brush for an electrophotographic copying machine, an electrophotographic printer, a contact charging brush, a photosensitive drum cleaner brush, and the like.

The present invention will be described in detail below with reference to Examples and Comparative Examples. However, the present invention is not limited to the following examples.
The measurement method or evaluation method of each physical property is as follows.
(1) Thread spots 50 m of conductive composite fibers were collected and cut into 50 fibers of 1 m each. For these 50 yarns, the fineness of each single yarn was measured using a denier computer "DC-11B" manufactured by Search, and the average value of the fineness of the 50 yarns was X, the maximum fineness was Xmax, and the minimum fineness was set. It was calculated as Xmin by the following formula.
Thread spots [%] = (| X-Xmax | / Xx100 + | X-Xmin | / Xx100) / 2

(2) Electrical resistance value in the longitudinal direction of the fiber, CV value of the electrical resistance value in the longitudinal direction of the fiber The measurement was carried out as follows by the AATCC76 method.
The conductive composite fiber was cut to about 15 cm, and 10 samples were taken. A conductive paste (manufactured by Fukuda Denshi Co., Ltd., trade name "keratin cream", model "OJE-01D") was applied to the surfaces at both ends of this sample, and the surface portions at both ends were connected to metal terminals. Here, the sample was connected to the metal terminal so that the measurement length of the sample was 10 cm (that is, the electrical resistance value in the longitudinal direction of 10 cm was measured). In an environment with a temperature of 20 ° C and a relative humidity of 20% RH, a resistance value measuring device (“SM-10E” manufactured by Toa Denpa Kogyo Co., Ltd.) was used to apply a DC current of 50 V to measure the current value. The electric resistance value was calculated by the following formula.
X = E / (I × L)
X: Electrical resistance value (Ω / cm)
E: Voltage (V)
I: Measured current (A)
L: Measurement length (cm)

Then, the CV value of the electrical resistance value in the longitudinal direction of the fiber was calculated according to the following formula.
CV (%) = (V / E (X)) × 100 of electrical resistance value in the longitudinal direction of the fiber
V: Square root of unbiased variance of electrical resistance E (X): Mean of electrical resistance The unbiased variance was determined as follows. That is, the difference between the average electric resistance value and the average electric resistance value was obtained for all the test pieces. The sum of the values obtained by squaring these differences was divided by (number of test pieces-1), and the obtained values were defined as unbiased variance.

(3) Boiling water shrinkage rate The obtained fiber is squeezed 20 times with a measuring machine, the yarn length L0 is measured under a load of 0.03 (cN / dtex), and then placed in boiling water under no load. Treated for 30 minutes. Then, it is air-dried, the length L1 after shrinkage is measured again under a load of 0.03 (cN / dtex), and the boiling water shrinkage ratio is calculated by the following formula.
Boiling water shrinkage rate (%) = [(L0-L1) / L0] × 100

(4) Intrinsic viscosity [η]
The measurement was carried out by a conventional method under the conditions of a sample concentration of 0.9% by mass and a temperature of 20 ° C. using an equal mass mixture of phenol and ethane tetrachloride as a solvent.

(5) Melt Viscosity Measured using a flow tester (manufactured by Shimadzu Corporation, model "CFT-500") under the conditions of a temperature of 270 ° C. and a shear rate of 1000 sec ^-1 .

(6) Observation of cross-sectional shape The cross-sectional shape of the conductive composite fiber was observed using a digital microscope "VHX-600" manufactured by KEYENCE Co., Ltd. (magnification: 1000 times).

<Example 1>
As a non-conductive component, PET in which IPA (isophthalic acid) was copolymerized at a ratio of 8 mol% was used. PBT containing 25% by mass of carbon black as a conductive component and having a melt viscosity at 270 ° C. of 1581 dPa · s (intrinsic viscosity of 0.54) was used. Each of these components is supplied to a normal composite spinning apparatus, and a spinning base designed so that the cross-sectional shape of the fiber is as shown in FIG. 1 is used, the spinning temperature is 270 ° C., and the composite ratio of the conductive components is 20% by mass. It was melt-spun so that it would be. In FIG. 1, it is a type in which a non-conductive component is divided by a conductive component, and the number of rows of the conductive component is three and intersects. The spun yarn was cooled and oiled while being picked up by the first pick-up roller at a speed of 4000 m / min, and then picked up by the second pick-up roller at a speed ratio of 1.002 without substantially stretching. The conductive composite fiber (28dtex / 3f) of Example 1 was obtained.

<Examples 2 and 3><Comparative example 2>
The same procedure as in Example 1 was carried out except that the take-up speed of the first take-up roller was changed to 5000 m / min and 6000 m / min and 3000 m / min, respectively, to obtain the conductive composite fibers of Examples 2, 3 and Comparative Example 2. It was.

<Examples 4 and 5><Comparative example 5>
Example 1 except that the amount of carbon black contained as a conductive component was changed to 35% by mass, 15% by mass, and 5% by mass, and the melt viscosities were changed to 1793 dPa · s, 1145 dPa · s, and 940 dPa · s accordingly. The same procedure was carried out to obtain conductive composite fibers of Examples 4, 5 and Comparative Example 5.

<Examples 6 and 7><Comparative Examples 3 and 4>
Example 1 except that the intrinsic viscosity of the conductive component and the intrinsic viscosity of the non-conductive component were changed as shown in Table 1, and the melt viscosity was changed accordingly as shown in Table 1. The same procedure was carried out to obtain the conductive composite fibers of Examples 6 and 7 and Comparative Examples 3 and 4.

<Examples 8, 9, and 10>
The same procedure as in Example 1 was carried out except that the cross-sectional shape of the fiber was changed to FIGS. 2, 3 and 4, to obtain conductive composite fibers of Examples 8, 9 and 10.

<Comparative example 1>
As a non-conductive component, PET in which 8 mol% of IPA was copolymerized was used. PBT containing 25% by mass of carbon black as a conductive component and having a melt viscosity at 270 ° C. of 1581 dPa · s (intrinsic viscosity of 0.54) was used. Each component is supplied to a normal composite spinning device, and a spinning base designed so that the cross-sectional shape of the fiber is as shown in FIG. 1 is used, the spinning temperature is 270 ° C., and the composite ratio of the conductive component is 20% by mass. It was melt-spun so as to be. In FIG. 1, it is a type in which a non-conductive component is divided by a conductive component, and the number of rows of the conductive component is three and intersects. The spun yarn was cooled and oiled while being picked up by the first pick-up roller at a speed of 1500 m / min, and then picked up by the second pick-up roller at a speed ratio of 1.002 without substantially stretching, and 74 dtex. An undrawn yarn of / 3f was obtained. This undrawn yarn is stretched 2.64 times through a hot roller at 90 ° C., further heat-treated with a heat plate at 140 ° C., and then wound up to exhibit the cross-sectional shape of Comparative Example 1. Fiber (28dtex / 3f) was obtained.

The evaluations of the conductive composite fibers obtained in Examples and Comparative Examples are summarized in Tables 1 and 2.

As can be understood from Tables 1 and 2, the conductive composite fibers of the present invention obtained in Examples 1 to 10 were excellent in conductive performance, thread spots were suppressed, and variations in conductivity were remarkably reduced.

In Comparative Example 1, the take-up speed of the first take-up roller was slow, and after taking up with the second take-up roller, a drawing step of 2.7 times was performed, so that the obtained conductive composite fiber had very fine thread spots. Badly, the variation in conductivity also increased.

In Comparative Example 2, since the take-up speed of the first take-up roller was slow, the obtained conductive composite fiber had poor thread unevenness and a large variation in conductivity. In addition, since the orientation and crystallization of both the conductive component and the non-conductive component did not proceed appropriately, the boiling water shrinkage rate was also high. Furthermore, since the orientation and crystallization did not proceed properly, the structure of the conductive particles was not developed, and the variation in the conductive performance was reduced.

In Comparative Example 3, the melt viscosity of the polymer contained in the conductive component is high, and in Comparative Example 4, the melt viscosity of the polymer contained in the conductive component is low, and high-speed spinning as in the present invention (that is, first Since the take-up speed of the take-up roller is not in a preferable range suitable for 4000 to 6000 m / min), the orientation crystallization does not proceed properly and the conductive performance is lowered. In addition, since the thread unevenness was also bad, the variation in conductive performance became large.

In Comparative Example 5, since the content of the conductive particles was small, only the conductive composite fiber having inferior conductive performance was obtained.

1 Conductive component 2 Non-conductive component

Claims (9)

A conductive composite fiber composed of a non-conductive component containing a thermoplastic polymer and a conductive component containing the thermoplastic polymer and conductive particles in an amount of 10 to 40% by mass, wherein the electric resistance value of the conductive composite fiber is A conductive composite fiber having a CV value of 1 × 10 ⁴ to 1 × 10 ¹⁰ Ω / cm and an electrical resistance value in the longitudinal direction of the fiber of 6%. The conductive composite fiber according to claim 1, wherein the thread unevenness is 3.5% or less. The conductive composite fiber according to claim 1 or 2, wherein the elongation is 50% or more and 90% or less. The conductive composite fiber according to any one of claims 1 to 3, wherein the boiling water shrinkage rate is 3% or more and 20% or less. A method for producing a conductive composite fiber, which comprises the following steps (a) to (c) in this order.
(A) A step of preparing a non-conductive component containing a thermoplastic polymer and a conductive component containing a thermoplastic polymer and conductive particles.
(B) A step of composite spinning the conductive component and the non-conductive component.
(C) The process of picking up with the first pick-up roller and then picking up with the second pick-up roller.
However, the take-up speed of the first take-up roller shall be 4000 to 6000 m / min, the speed ratio between the first take-up roller and the second take-up roller shall be 1.0 or more and 1.1 or less, and after being picked up by the second take-up roller, it is substantially No stretching is applied. The method for producing a conductive composite fiber according to claim 5, wherein the spinning temperature in the step (b) is 250 to 310 ° C. A woven or knitted fabric containing the conductive composite fiber according to any one of claims 1 to 4. A garment comprising the woven or knitted fabric according to claim 7. A brush comprising the conductive composite fiber according to any one of claims 1 to 4.