JP2006152491A - Conductive fiber and use thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive fiber excellent in conductivity, tensile strength and the like. <P>SOLUTION: The conductive fiber is one having ≤1.0×10<SP>9</SP>αcm volume resistivity, 5-500 μm fiber diameter and ≥2 g/dTex tensile strength, and preferably one formed from a thermoplastic resin composition containing carbon nanofiber having ≤1.0 αcm volume resistivity and ≥150 ml/100g DBP oil adsorption and which one has ≤1.0×10<SP>6</SP>αcm volume resistivity, 5-500 μm fiber diameter, ≥2.8 g/dTex tensile strength and ≥10% elongation. The conductive material is formed from the conductive fiber. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a conductive yarn excellent in mechanical strength such as conductivity and tensile strength. More specifically, conductive fiber products such as developing brushes, contact charging brushes, cleaner brushes, or static elimination brushes used in electrophotographic apparatuses (copiers, facsimiles, printers, etc.), dust-proof clothing, and antistatic work Conductives used in various industrial materials such as clothing, anti-static gloves, anti-static socks, anti-static stockings, anti-static hats, anti-static clothing, etiquette brushes, electrostatic belts, electrostatic sheets, etc. The present invention relates to a conductive yarn suitable as a raw material for conductive fibers.

Various brushes such as developing brushes and photosensitive drum cleaner brushes are used in electrophotographic copying machines, electrophotographic printers, etc., and these brushes are formed of conductive fibers to prevent residual charging of toner and the like. Therefore, there is a demand for a material having higher conductivity. Conventionally, as a conductive fiber, a fiber formed of a resin in which conductive fine particles are blended to reduce specific resistance is known, but the durability against environmental change is low, and the conductive fine particles present on the fiber surface have a small amount. When a brush formed of such a fiber with unevenness is used in an electrophotographic apparatus, the sharpness of the image may be reduced (Patent Document 1).

Further, a core part made of a thermoplastic synthetic polymer containing conductive carbon black and a non-conductive sheath part not containing conductive carbon black are known, and the sheath part is known to have a small filament cross-sectional area. (Patent Document 2). Since this conductive fiber does not contain conductive carbon black in the sheath portion, there are few fine irregularities on the fiber surface, but there is a problem that the manufacturing process is complicated and the conductivity is low.

Furthermore, there is known a conductive yarn in which a thermoplastic resin A containing conductive fine particles such as carbon black is divided into a plurality of parts and exposed on the fiber surface, and the thermoplastic resin B occupies the fiber center (Patent Document 3). . Also known is a conductive filament that attempts to improve the spinnability of the resin composition by adding a magnesium compound to the resin composition containing carbon black or the like, or adjusting the viscosity of the resin composition (patent) Document 4 and Patent document 5).
JP 09-49116 A JP 52-31450 A JP 2003-105634 A JP 2004-183180 A JP 2004-131899 A

Conventional conductive fibers formed from a resin composition in which carbon black or the like is blended with a resin have a problem that the physical properties of the resin are impaired when the blending amount of carbon black is increased in order to increase conductivity, and the strength is high. Therefore, it is difficult to obtain a fiber having excellent conductivity. As for conductive fibers using carbon nanotubes instead of carbon black, conventional carbon nanotubes are inferior in dispersibility in the resin, so increasing this compounding amount decreases the physical properties of the resin such as tensile strength and elongation, making spinning impossible. become. This invention solves the said problem in the conventional electroconductive fiber, and provides the electroconductive yarn excellent in mechanical strength with electroconductivity.

According to the present invention, the following conductive yarn is provided.
(1) It is formed of a thermoplastic resin composition containing carbon nanofibers, and has a volume resistance of 1.0 × 10 ⁹ Ωcm or less, a fiber diameter of 5 to 500 μm, and a tensile strength of 2 g / dTex or more. Conductive yarn.
(2) The conductive yarn according to the above (1), having a volume resistance value of 1.0 × 10 ⁶ Ωcm or less, a fiber diameter of 5 to 500 μm, a tensile strength of 2.8 g / dTex or more, and an elongation of 10% or more.
(3) The conductive yarn according to the above (1) or (2), which is formed from a thermoplastic resin composition containing carbon nanofibers having a volume resistance of 1.0 Ωcm or less and a DBP oil absorption of 150 ml / 100 g or more.
(4) The above-mentioned (1) to (3), wherein the carbon nanofiber content is 2000 m ² or less in terms of the surface area of the carbon nanofiber (carbon content × specific surface area value) relative to 100 parts by weight of the thermoplastic resin. A conductive yarn according to any one of the above.
(5) The conductive yarn according to any one of the above (1) to (4), which is formed of a resin composition containing a carbon nanofiber and a conductive powder having a volume resistance value of 100 Ωcm or less.
(6) The conductive yarn according to any one of the above (1) to (5), wherein the thermoplastic resin composition containing carbon nanofibers has an intrinsic viscosity (IV value) of 0.50 to 0.90.
(7) The above (1) to (1) using a polyester-based resin having a melt viscosity (MFR) of a thermoplastic resin composition containing carbon nanofibers of 10 g / min or more under the conditions of a temperature of 280 ° C. and a load of 2160 g. 6) The conductive yarn described in any of the above.
(8) A conductive material formed by the conductive yarn described in any one of (1) to (7) above.
(9) A conductive brush, a conductive belt, a conductive sheet, or an electrostatic garment formed of the conductive material according to (8).

The conductive yarn of the present invention is formed of a thermoplastic resin composition containing carbon nanofibers, has a volume resistance value of 10 ⁰ to 10 ⁹ Ωcm, a fiber diameter of 5 to 500 μm, and a tensile strength of 2 g / dTex or more. The conductive yarn is preferably a conductive yarn having a volume resistance of 10 ⁶ Ωcm or less, a fiber diameter of 5 to 500 μm, a tensile strength of 2.8 g / dTex or more, and an elongation of 10% or more. . Since the conductive yarn of the present invention is excellent in electrical conductivity and has high mechanical strength, it is possible to obtain a highly conductive conductive yarn having a finer fiber diameter than conventional conductive fibers, and can be used in a wide range of applications. Can do.

The conductive yarn of the present invention is, for example, a carbon nanofiber having a volume resistance value of 1.0 Ωcm or less and a DBP oil absorption of 150 ml / 100 g or more, converted into a surface area equivalent value of the carbon nanofiber with respect to 100 parts by weight of the thermoplastic resin (carbon content × It can be formed by a thermoplastic resin composition contained so as to have a specific surface area of 2000 m ² or less. Carbon nanofibers with a DBP oil absorption of 150ml / 100g or more have good dispersibility in the resin. By blending this into the resin within the above content range, the conductivity and the mechanical strength of the resin are not impaired. A conductive yarn excellent in strength and the like can be obtained. The conductive yarn of the present invention can be added with a small amount of conductive powder in order to stabilize the conductivity.

The resin composition used for the conductive yarn of the present invention preferably has an intrinsic viscosity (IV value) of a thermoplastic resin composition containing carbon nanofibers of 0.50 to 0.90. The melt viscosity (MFR) of the thermoplastic resin composition containing carbon nanofibers is preferably 10 g / min or more under the conditions of a temperature of 280 ° C. and a load of 2160 g, and a polyester resin is preferably used as the thermoplastic resin. By using the above resin, it is possible to obtain a conductive yarn excellent in spinnability and having a good surface condition.

A conductive material of high strength and high conductivity can be obtained by the conductive yarn of the present invention or a fiber body using the conductive yarn. For example, a high-performance conductive brush or conductive belt can be obtained by using the conductive material. A conductive sheet or an electrostatic garment can be obtained.

The conductive yarn of the present invention has a volume resistance value of 10 ⁰ to 10 ⁹ Ωcm, a fiber diameter of 5 to 500 μm and a tensile strength of 2 g / dTex or more, preferably a volume resistance value of 10 ⁶ Ωcm or less and a fiber diameter of 5 The tensile strength is 2.8 g / dTex or more and the elongation is 10% or more at ˜500 μm, more preferably the tensile strength is 3 g / dTex or more and the elongation is 20% or more.

Note that conventional conductive yarns containing carbon black or carbon nanotubes have poor dispersibility, and therefore the conductive filer is not uniformly dispersed. In addition, when a conductive filler is blended so that the volume resistance value is 10 ⁵ Ωcm or less, the physical properties of the resin are impaired, so that continuous spinning is impossible. Even when the yarn is spun, the tensile strength is generally 1.5 g / dTex or less and the elongation is 5% or less. On the other hand, when trying to obtain a yarn of 2 g / dTex or more and an elongation of 10% or more, the volume resistance value is It becomes 1.0 × 10 ¹² Ωcm or more.

The high-strength and high-conductivity conductive yarn of the present invention can be formed by a resin composition obtained by blending carbon nanofibers with good dispersibility in a thermoplastic resin. The carbon nanofiber used in the present invention is, for example, a nano-sized ultrafine carbon fiber having a diameter of several tens of nanometers or less and a length of several hundreds of micrometers or less. Including those with a filled structure, including a case where the carbon layer has a single layer structure or a multilayer structure, the carbon layer is not limited to a spiral structure, and is not limited to a structure in which the carbon layer extends in the axial direction of the fiber. In addition, a carbon layer having a structure extending in the radial direction is also included.

The carbon nanofiber used in the conductive yarn of the present invention preferably has a volume resistance of 1.0 Ωcm or less and a DBP oil absorption of 150 ml / 100 g or more. Carbon nanofibers with a DBP oil absorption of less than 150 ml / 100 g have poor dispersibility in the resin and tend to agglomerate, making the resin composition non-uniform in conductivity and further reducing the processability of the resin composition. It is difficult to obtain a conductive yarn excellent in strength and elongation. Carbon nanofibers having a volume resistance value greater than 1.0 Ωcm have insufficient conductivity.

Carbon nanofibers having a volume resistance value of 1.0 Ωcm or less and a DBP oil absorption of 150 ml / 100 g or more can be produced by adjusting the composition of the catalyst and raw material mixed gas in a vapor phase growth method using a catalyst. Specifically, for example, the catalyst particles are one or more selected from oxides of Fe, Ni, Co, Mn, and Cu and one selected from oxides of Mg, Ca, Al, and Si. Alternatively, vapor phase growth in which carbon nanofibers are produced by using two or more mixed oxide powders and contacting carbon monoxide or a mixed gas of carbon dioxide and hydrogen with the catalyst particles at a temperature of 400 ° C. to 800 ° C. In this method, a mixed oxide of Co oxide and Mg oxide or a composite oxide in which a Mg oxide is coated with a Co oxide is used as a catalyst, and the raw material mixed gas is carbon monoxide and / or carbon dioxide and hydrogen. The volume ratio is adjusted by adjusting the mixing ratio to CO / H ₂ = 50/50 to 99/1, preferably by further treating with hydrogen gas for 10 minutes or more continuously at the same temperature as the reaction temperature after the reaction. value Can ku DBP oil absorption of producing high carbon nanofiber.

The carbon nanofibers preferably have a diameter of 5 to 100 nm, an aspect ratio of 10 or more, and a BET specific surface area of 400 m ² / g or less. If the diameter is smaller than this, it is difficult to disperse uniformly. On the other hand, if it is larger than this, the yarn strength is not increased because the filler is too large for the fiber system. If the aspect ratio is smaller than this, a sufficient network cannot be formed, so that the conductivity cannot be obtained with a small amount. Also, if the BET specific surface area is larger than this, the contact area with the resin becomes excessive, the properties of the resin are impaired, the inherent strength of the resin itself, the viscosity at the time of kneading or molding increases, and the fluidity is lost. Therefore, it is not preferable.

As the thermoplastic resin containing the carbon nanofiber, a thermoplastic resin that can be melt-spun can be generally used. Specifically, a polyester resin, a polyamide resin, a polyethylene resin, a polypropylene resin, or the like can be used. Among the thermoplastic resins, polyester is a high molecular weight body in which a so-called hydrocarbon group is connected to the main chain via an ester bond, and examples thereof include polyethylene terephthalate, polybutylene terephthalate, and polypropylene terephthalate. In view of spinning performance, polyethylene terephthalate is most preferable.

The thermoplastic resin composition containing carbon nanofibers preferably has an intrinsic viscosity (IV value) of 0.50 to 0.90. This value is an amount representing the molecular weight of the thermoplastic resin used. If this value is less than 0.5, the resin viscosity is too low during melt spinning because the molecular weight is small, and yarn breakage occurs. The yarn cannot be manufactured continuously. On the other hand, if the above value is greater than 0.9, the molecular weight is too large and the resin is hard, so that the resin does not flow sufficiently from the nozzle of the extruder during spinning, and the yarn cannot be manufactured.

The thermoplastic resin composition containing carbon nanofibers preferably has a melt viscosity (MFR) of 10 g / min or more under the conditions of a temperature of 280 ° C. and a load of 2160 g, and is a polyester resin as a thermoplastic resin. The MFR value is a value indicating the fluidity at the processing temperature, and if it is less than 10 g / min, the fluidity is small, so that the resin does not sufficiently flow out during melt spinning.

The carbon nanofiber content of the resin composition forming the conductive yarn of the present invention is 2000 m ² or less in terms of the surface area of the carbon nanofiber (carbon content × specific surface area value) relative to 100 parts by weight of the thermoplastic resin. And what whose content in a resin composition is 2 to 10 weight% is preferable. When this content is less than 2% by weight, the specific resistance is low. On the other hand, when the content exceeds 10% by weight, melt spinnability is lowered, and yarn breakage frequently occurs during spinning.

Specifically, for example, when carbon nanofibers having a BET value of 100 g / m ² are used, the resin can contain up to 20 parts by weight under the conditions based on the surface area converted value. In the case of exceeding the range, melt spinnability is impaired from the viewpoint of continuity between resins, and spinning is difficult. Further, when carbon nanofibers having a BET value of 400 g / m ² are used, up to 10% by weight can be blended under the weight ratio condition, but the melt spinnability is the area in contact with the resin under the condition based on the surface area converted value. In practice, it is possible to spin only up to a content of 5% by weight. If any of the ranges is exceeded, there is a problem in melt spinnability and the yarn cannot be produced.

The resin composition can enhance the stability of conductivity by adding conductive fine particles such as carbon black within a range that does not significantly impair the mechanical strength and the like together with the carbon nanofibers. Examples of the conductive fine particles include carbon powder, conductive metal oxide powder, metal powder, and conductive powder coated with these. Furthermore, you may contain a flame retardant, a dispersion stabilizer, etc.

Examples of the present invention are shown below together with comparative examples. The spinning method and the evaluation method are as follows.
[Spinning method] Melt spinning was carried out at a winding speed of 1000 m / min, and the yarn was continuously drawn at a draw ratio of 3 to produce 48 filament yarn.
[Specific Resistance Value] Using a super insulation resistance meter (product of Toa Denpa Kogyo Co., Ltd .: SM-8210), applying a voltage of 10 to 1000 V between 10 cm of test length, under the conditions of temperature 20 ° C. and humidity 30% RH, The electrical resistance value R (Ωcm) was measured, and the cross-sectional area and length were converted and determined.
[Tensile Strength] The maximum load and the elongation at that time were measured using a tensile tester. For the tensile strength, the fiber thickness was measured separately and converted per unit thickness.

Carbon nanofibers (CNF) shown in Table 1 were uniformly kneaded into a resin to produce a conductive resin composition. This was melt-spun and further drawn to obtain conductive yarns having the fineness shown in Table 1. Table 1 shows the properties of the resin, carbon nanofibers, production conditions, and conductive yarn.

Claims (9)

A conductive yarn formed of a thermoplastic resin composition containing carbon nanofibers, having a volume resistance of 1.0 × 10 ⁹ Ωcm or less, a fiber diameter of 5 to 500 μm, and a tensile strength of 2 g / dTex or more.
2. The conductive yarn according to claim 1, having a volume resistance of 1.0 × 10 ⁶ Ωcm or less, a fiber diameter of 5 to 500 μm, a tensile strength of 2.8 g / dTex or more, and an elongation of 10% or more.
The conductive yarn according to claim 1 or 2, formed of a thermoplastic resin composition containing carbon nanofibers having a volume resistance value of 1.0 Ωcm or less and a DBP oil absorption of 150 ml / 100 g or more.
The content of the carbon nanofiber is 2000 m ² or less in terms of the surface area of the carbon nanofiber with respect to 100 parts by weight of the thermoplastic resin (carbon content x specific surface area value). Conductive yarn.
The conductive yarn according to any one of claims 1 to 4, wherein the conductive yarn is formed of a resin composition containing a conductive powder having a volume resistivity of 100 Ωcm or less together with carbon nanofibers.
The conductive yarn according to any one of claims 1 to 5, wherein the thermoplastic resin composition containing carbon nanofibers has an intrinsic viscosity (IV value) of 0.50 to 0.90.
7. The polyester resin having a melt viscosity (MFR) of 10 g / min or more under the conditions of a temperature of 280 ° C. and a load of 2160 g, using a thermoplastic resin composition containing carbon nanofibers. Conductive yarn to be described.
The electroconductive material formed with the electrically conductive thread in any one of Claims 1-7.
A conductive brush, a conductive belt, a conductive sheet, or an electrostatic garment formed of the conductive material according to claim 8.