Carbon nanotube-coated electric wire

Abstract

To provide a carbon nanotube coated electric wire excellent in discriminability.SOLUTION: The carbon nanotube coated electric wire comprises a carbon nanotube wire having a single or a plurality of carbon nanotube aggregates each composed of a plurality of carbon nanotubes and an insulation coating layer coating the carbon nanotube wire in which the carbon nanotube wire has a discrimination mark.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a carbon nanotube coated electric wire in which a carbon nanotube wire made of a plurality of carbon nanotubes is coated with an insulating material.

Background Art

[0002] Carbon nanotubes (hereinafter sometimes referred to as "CNTs") are materials having various characteristics and are expected to be applied to many fields.

[0003] For example, CNTs are three-dimensional network structures composed of a single layer of a cylindrical body having a hexagonal lattice network structure or multiple layers arranged substantially coaxially, and are lightweight and excellent in various characteristics such as conductivity, heat conductivity, and mechanical strength. However, it is not easy to form CNTs into a wire, and there are few technologies using CNTs as a wire.

[0004] For example, in order to further improve the conductivity of CNT materials, a carbon nanotube material in which a conductive deposit made of a metal or the like is formed at an electrical junction of adjacent CNT wires has been proposed, and it has been disclosed that such a carbon nanotube material can be applied to a wide range of uses (Patent Document 1).

[0005] On the one hand, as power lines and signal lines in various fields such as automobiles and industrial equipment, electric wires composed of a core wire made of one or more wire materials and an insulating coating covering the core wire are used. As the material of the wire material constituting the core wire, copper or a copper alloy is usually used from the viewpoint of electrical characteristics. In recent years, however, aluminum or an aluminum alloy has been proposed from the viewpoint of weight reduction. For example, the specific gravity of aluminum is about 1 / 3 of that of copper, and the conductivity of aluminum is about 2 / 3 of that of copper (when pure copper is used as the reference of 100% IACS, pure aluminum is about 66% IACS). In order to pass the same current through an aluminum wire as through a copper wire, it is necessary to make the cross-sectional area of the aluminum wire about 1.5 times as large as that of the copper wire. However, even if an aluminum wire with such a large cross-sectional area is used, the mass of the aluminum wire is about half that of a pure copper wire. Therefore, using an aluminum wire is advantageous from the viewpoint of weight reduction.

[0006] In addition, the performance and functionality of automobiles, industrial equipment, etc. are being improved. Along with this, the number of various electrical equipment and control equipment installed increases, and the number of wirings of the electrical wiring bodies used in these equipment and the heat generation from the core wires also tend to increase. Therefore, it is required to improve the heat dissipation characteristics of the electric wire without impairing the insulation property by the insulating coating. On the other hand, in order to improve the fuel efficiency of moving bodies such as automobiles for environmental protection, weight reduction of the wire material is also required.

[0007] Furthermore, conventionally, in order to identify the type and use of electric wires, identification marks have been provided on the outer surface of the electric wires. For example, in an automobile, a variety of electrical components and electronic devices are installed, and a wire harness is routed to transmit power, control signals, etc. between the electrical components (electronic devices). In such various electric wires, identification marks for identifying the electric wires corresponding to each electrical circuit are provided. When such identification marks are provided on the outer surface, the identifiability may decrease due to abrasion or the like. On the other hand, when trying to provide the identification marks inside the outer surface, it is not easy to perform processing like that of a metal wire or to maintain conductivity after processing, and it is difficult to process the carbon nanotubes themselves.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] An object of the present invention is to improve the distinguishability of a carbon nanotube - coated electric wire using a carbon nanotube wire.

Means for Solving the Problems

[0010] The present invention has the following embodiments.

[0011] [1] A carbon nanotube wire having one or more carbon nanotube aggregates composed of a plurality of carbon nanotubes, and an insulating coating layer covering the carbon nanotube wire, comprising wherein the carbon nanotube wire has an identification mark, a carbon nanotube - coated electric wire. [2] A carbon nanotube wire formed by twisting a plurality of carbon nanotube aggregates composed of a plurality of carbon nanotubes, and an insulating coating layer covering the carbon nanotube wire, comprising wherein in a plurality of gaps between the carbon nanotube aggregates or the plurality of carbon nanotube wires, there is an identification mark, a carbon nanotube - coated electric wire. [3] The carbon nanotube - coated electric wire according to [1] or [2] above, wherein the carbon nanotube wire has, as the identification mark, another wire having a color different from that of the carbon nanotube aggregate. [4] The carbon nanotube - coated electric wire according to [1] or [2] above, wherein the identification mark includes a capsule. [5] The capsule is the carbon nanotube-coated wire according to [4] above, containing a fluorescent substance. [6] The identification mark is the carbon nanotube-coated wire according to [1] or [2] above, comprising a core part containing a fluorescent substance and a shell part containing silica. [7] The identification mark is the carbon nanotube-coated wire according to [1] or [2] above, containing a material whose color changes according to the temperature change or stress change of the carbon nanotube-coated wire. [8] The identification mark is the carbon nanotube-coated wire according to [1] or [2] above, containing a magnetic material. [9] The identification mark is a barcode or QR code (registered trademark) composed of three or more barcode lines with different line widths from each other, which is the carbon nanotube-coated wire according to [1] or [2] above.

[10] The identification mark is the carbon nanotube-coated wire according to any one of [4] to [9] above, which is located at regular intervals in the longitudinal direction of the carbon nanotube-coated wire.

[11] The identification mark is the carbon nanotube-coated wire according to any one of [4] to [9] above, which is located at at least one end in the longitudinal direction of the carbon nanotube-coated wire.

[12] The carbon nanotube-coated wire according to any one of [1] to

[11] above, where specific information is given to the identification mark.

[13] The refractive index n of the material constituting the insulating coating layer D is less than 1.5, and the film thickness of the insulating coating layer / the wire diameter of the carbon nanotube wire is less than 0.2, which is the carbon nanotube-coated wire according to any one of [1] to

[12] above.

[14] The total light transmittance specified in JIS 7375:2008 of the material constituting the insulating coating layer is 75% or more, and the film thickness of the insulating coating layer / the wire diameter of the carbon nanotube wire is less than 0.2, which is the carbon nanotube-coated wire according to any one of [1] to

[12] above.

[15] The carbon nanotube wire material is composed of a plurality of the carbon nanotube aggregates, and in the azimuth plot by small-angle X-ray scattering showing the orientation of the plurality of the carbon nanotube aggregates, the half-value width Δθ of the azimuth angle is 60° or less. The carbon nanotube coated wire according to any one of [1] to

[14] above.

[16] The q value at the peak top in the (10) peak of the scattering intensity by X-ray scattering showing the density of the plurality of the carbon nanotubes is 2.0 nm -1 or more and 5.0 nm -1 or less, and the half-value width Δq is 0.1 nm -1 or more and 2.0 nm -1 or less. The carbon nanotube coated wire according to any one of [1] to

[15] above.

Effect of the Invention

[0012] Since the carbon nanotube wire material has an identification mark, the carbon nanotube coated wire can have excellent discriminability.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0014] 1. Carbon Nanotube-Coated Wire Hereinafter, a carbon nanotube-coated wire according to an embodiment will be described with reference to the drawings.

[0015] As shown in FIG. 1, a carbon nanotube-coated wire (hereinafter sometimes referred to as a "CNT-coated wire") 1 according to an embodiment has a configuration in which an insulating coating layer 21 is coated on the outer peripheral surface of a carbon nanotube wire (hereinafter sometimes referred to as a "CNT wire") 10. That is, the insulating coating layer 21 is coated along the longitudinal direction of the CNT wire 10. In the CNT-coated wire 1, the entire outer peripheral surface of the CNT wire 10 is coated with the insulating coating layer 21. Further, in the CNT-coated wire 1, the insulating coating layer 21 is in direct contact with the outer peripheral surface of the CNT wire 10. In this case, the CNT-coated wire 1 includes a carbon nanotube wire having a single or a plurality of carbon nanotube aggregates composed of a plurality of carbon nanotubes, and an insulating coating layer that coats the carbon nanotube wire. Although not shown in FIG. 1, the CNT wire 10 has an identification mark. In FIG. 1, the CNT wire 10 is a single wire (single strand) composed of one CNT wire 10, but the CNT wire 10 may be a stranded wire formed by twisting a plurality of CNT wires 10. By forming the CNT wire 10 in the form of a stranded wire, the equivalent diameter and cross-sectional area of the CNT wire 10 can be appropriately adjusted. In this case, the CNT-coated wire 1 includes a carbon nanotube wire formed by twisting a plurality of carbon nanotube aggregates composed of a plurality of carbon nanotubes, and an insulating coating layer that coats the carbon nanotube wire. Further, the CNT-coated wire 1 has an identification mark in a plurality of gaps between the carbon nanotube aggregates or the plurality of carbon nanotube wires.

[0016] As shown in FIG. 2, the CNT wire 10 is formed by bundling a single or a plurality of carbon nanotube aggregates (hereinafter sometimes referred to as "CNT aggregates") 11 composed of a plurality of CNTs 11a, 11a,... having a layer structure of one or more layers. Here, the CNT wire means a CNT wire in which the proportion of CNTs is 90% by mass or more. In calculating the proportion of CNTs in the CNT wire, plating and dopants are excluded. In FIG. 2, the CNT wire 10 has a configuration in which a plurality of CNT aggregates 11 are bundled. The longitudinal direction of the CNT aggregate 11 forms the longitudinal direction of the CNT wire 10. Therefore, the CNT aggregate 11 is linear. The plurality of CNT aggregates 11, 11,... in the CNT wire 10 are arranged with their major axis directions substantially aligned. Therefore, the plurality of CNT aggregates 11, 11,... in the CNT wire 10 are oriented. The equivalent circle diameter of the CNT wire 10, which is a single wire, is not particularly limited, but is, for example, 0.01 mm or more and 4.0 mm or less. Also, the equivalent circle diameter of the stranded CNT wire 10 is not particularly limited, but is, for example, 0.1 mm or more and 15 mm or less.

[0017] The CNT aggregate 11 is a bundle of CNTs 11a having a layer structure of one or more layers. The longitudinal direction of the CNT 11a forms the longitudinal direction of the CNT aggregate 11. The plurality of CNTs 11a, 11a,... in the CNT aggregate 11 are arranged with their major axis directions substantially aligned. Therefore, the plurality of CNTs 11a, 11a,... in the CNT aggregate 11 are oriented. The equivalent circle diameter of the CNT aggregate 11 is, for example, 20 nm or more and 1000 nm or less, and more typically 20 nm or more and 80 nm or less. The width dimension of the outermost layer of the CNT 11a is, for example, 1.0 nm or more and 5.0 nm or less.

[0018] The CNTs 11a that make up the CNT aggregate 11 are cylindrical bodies having a single-layer structure or a multi-layer structure, and are called SWNTs (single-walled nanotubes) and MWNTs (multi-walled nanotubes), respectively. In FIG. 2, for the sake of convenience, only the CNT 11a having a two-layer structure is shown, but the CNT aggregate 11 may also include CNTs having a layer structure of three or more layers or CNTs having a single-layer structure, and may be formed from CNTs having a layer structure of three or more layers or CNTs having a single-layer structure.

[0019] In the CNT 11a having a two-layer structure, it is a three-dimensional network structure in which two cylindrical bodies T1 and T2 having a hexagonal lattice network structure are arranged substantially coaxially, and is called a DWNT (Double-walled nanotube). The hexagonal lattice that is the structural unit is a six-membered ring in which carbon atoms are arranged at its vertices, and these are continuously bonded adjacent to other six-membered rings.

[0020] The properties of the CNT 11a depend on the chirality of the above-mentioned cylindrical body. Chirality is roughly classified into armchair type, zigzag type, and chiral type. The armchair type shows metallic behavior, the zigzag type shows semiconductor and semi-metallic behavior, and the chiral type shows semiconductor and semi-metallic behavior. Therefore, the conductivity of the CNT 11a varies greatly depending on which chirality the cylindrical body has. In the CNT aggregate 11 that constitutes the CNT wire 10 of the CNT-coated wire 1, it is preferable to increase the proportion of the armchair-type CNT 11a that shows metallic behavior in order to further improve the conductivity.

[0021] On the other hand, it has been found that by doping the chiral-type CNT 11a that shows semiconductor behavior with a substance (hetero element) having electron-donating or electron-accepting properties, the chiral-type CNT 11a shows metallic behavior. Also, in general metals, doping with hetero elements causes scattering of conduction electrons inside the metal and decreases the conductivity. Similarly, when a hetero element is doped into the CNT 11a that shows metallic behavior, it causes a decrease in conductivity.

[0022] As described above, since the doping effect on CNT11a showing metallic behavior and CNT11a showing semiconductor behavior is a trade-off relationship from the viewpoint of conductivity, theoretically, CNT11a showing metallic behavior and CNT11a showing semiconductor behavior are separately produced, and only the CNT11a showing semiconductor behavior is doped and then they are combined. However, with the current manufacturing technology, it is difficult to selectively produce CNT11a showing metallic behavior and CNT11a showing semiconductor behavior separately, and they are produced in a state where CNT11a showing metallic behavior and CNT11a showing semiconductor behavior are mixed. Therefore, in order to further improve the conductivity of the CNT wire 10 composed of a mixture of CNT11a showing metallic behavior and CNT11a showing semiconductor behavior, it is preferable to select a layer structure of CNT11a for which doping treatment with different elements / molecules is effective.

[0023] For example, CNTs with a small number of layers such as a two-layer structure or a three-layer structure have relatively higher conductivity than CNTs with a larger number of layers, and when doping treatment is performed, the doping effect in CNTs having a two-layer structure or a three-layer structure is the highest. Therefore, from the point of further improving the conductivity of the CNT wire 10, it is preferable to increase the proportion of CNTs having a two-layer structure or a three-layer structure. Specifically, the proportion of CNTs having a two-layer structure or a three-layer structure in the whole CNT is preferably 50% or more, more preferably 75% or more in terms of the number. The proportion of CNTs having a two-layer structure or a three-layer structure can be calculated by observing and analyzing the cross section of the CNT aggregate 11 with a transmission electron microscope (TEM) and measuring the number of layers of each of 100 CNTs.

[0024] In one embodiment, the CNT wire 10 has one or more CNT aggregates 11. As described above, the CNT aggregate 11 is formed by aggregation of CNTs 11a. Therefore, compared with a wire made of another material such as a copper wire, the identification mark materials such as pigments, dyes, fluorescent substances, and discoloring materials easily penetrate into the CNT aggregate 11. Due to the high specific surface area of the CNT itself, the adsorptivity of the identification mark material to the CNT aggregate 11 is increased. As a result, the identification mark material enters the CNT wire 10 and is stably retained.

[0025] In addition, the durability and weather resistance of the identification mark are also excellent, and the CNT wire 10 can stably maintain the visibility of the identification mark for a longer time. In a conventional wire mainly made of metal, the identification mark is simply attached to the surface by adhesion. Therefore, the identification mark is likely to detach from the wire during the coating treatment or cleaning treatment of the wire after the identification mark is applied. On the other hand, since the identification mark strongly adsorbs to the CNT wire in one embodiment, the identification mark can maintain a higher visibility state than a conventional wire mainly made of metal without detaching from the CNT wire.

[0026] Next, the orientation of the CNTs 11a and the CNT aggregate 11 in the CNT wire 10 will be described.

[0027] FIG. 3(a) is a diagram showing an example of a two-dimensional scattering image of the scattering vector q of a plurality of CNT aggregates 11, 11,... by small-angle X-ray scattering (SAXS), and FIG. 3(b) is a graph showing an example of an azimuth plot showing the relationship between the azimuth angle - scattering intensity of an arbitrary scattering vector q with the position of the transmitted X-ray as the origin in the two-dimensional scattering image.

[0028] SAXS is suitable for evaluating structures with sizes ranging from several nanometers to several tens of nanometers. For example, by using SAXS and analyzing the information of the X-ray scattering image in the following manner, the orientation of CNT11a with an outer diameter of several nanometers and the orientation of the CNT aggregate 11 with an outer diameter of several tens of nanometers can be evaluated. For example, when analyzing the X-ray scattering image of the CNT wire 10, as shown in Fig. 3(a), the x-component of the scattering vector q (q = 2π / d, where d is the lattice plane spacing) of the CNT aggregate 11, q x is more narrowly distributed than the y-component q y . Also, as a result of analyzing the azimuth plot of SAXS for the same CNT wire 10 as in Fig. 3(a), the half-value width Δθ of the azimuth angle in the azimuth plot shown in Fig. 3(b) is 48°. From these analysis results, it can be said that in the CNT wire 10, a plurality of CNT11a, 11a··· and a plurality of CNT aggregates 11, 11,··· have good orientation. Thus, since a plurality of CNT11a, 11a··· and a plurality of CNT aggregates 11, 11,··· have good orientation, the heat of the CNT wire 10 is easily dissipated while smoothly transferring along the longitudinal direction of the CNT11a and the CNT aggregate 11. Therefore, the CNT wire 10 can adjust the heat dissipation route in the longitudinal direction and the cross-sectional direction of the diameter by adjusting the orientation of the above CNT11a and the CNT aggregate 11, and thus exhibits excellent heat dissipation characteristics compared to a metal core wire. Note that the orientation refers to the angular difference between the vector V in the longitudinal direction of the twisted wire made by twisting and gathering CNTs and the vectors of the internal CNTs and CNT aggregates.

[0029] From the point of further improving the heat dissipation characteristics of the CNT wire 10 by obtaining an orientation of a certain level or more indicated by the half-value width Δθ of the azimuth angle in the azimuth plot of small-angle X-ray scattering (SAXS) showing the orientation of a plurality of CNT aggregates 11, 11,···, the half-value width Δθ of the azimuth angle is preferably 60° or less, and particularly preferably 50° or less.

[0030] Next, the array structure and density of the plurality of CNT11a constituting the CNT aggregate 11 will be described.

[0031] FIG. 4 is a graph showing the relationship between the q value and the intensity of the CNT aggregates 11 composed of a plurality of CNTs 11a, 11a, ··· by WAXS (wide-angle X-ray scattering).

[0032] WAXS is suitable for evaluating the structure of substances with a size of several nanometers or less. For example, by analyzing the information of the X-ray scattering image by the following method using WAXS, the density of the CNT 11a with an outer diameter of several nanometers or less can be evaluated. As a result of analyzing the relationship between the scattering vector q and the intensity for any one CNT aggregate 11, as shown in FIG. 4, q = 3.0 nm -1 ~4.0 nm -1 The value of the lattice constant estimated from the q value at the peak top of the (10) peak found in the vicinity is measured. Based on this measured value of the lattice constant and the diameter of the CNT aggregate observed by Raman spectroscopy or TEM, etc., it can be confirmed that the CNTs 11a, 11a, ··· form a hexagonal closest-packed structure in plan view. Therefore, it can be said that the diameter distribution of the plurality of CNT aggregates in the CNT wire 10 is narrow, and the plurality of CNTs 11a, 11a, ··· are regularly arranged, that is, have a high density, and thus exist at a high density by forming a hexagonal closest-packed structure. Thus, since the plurality of CNT aggregates 11, 11 ··· have good orientation, and furthermore, the plurality of CNTs 11a, 11a, ··· constituting the CNT aggregate 11 are regularly arranged and arranged at a high density, the heat of the CNT wire 10 is smoothly transmitted along the longitudinal direction of the CNT aggregate 11 and is easily radiated. Therefore, the CNT wire 10 can adjust the heat dissipation route in the longitudinal direction and the cross-sectional direction of the diameter by adjusting the arrangement structure and density of the above CNT aggregate 11 and CNT 11a, and thus exhibits excellent heat dissipation characteristics compared with a metal core wire.

[0033] From the point of further improving the heat dissipation characteristics by obtaining a high density, the q value at the peak top of the (10) peak of the scattering intensity by X-ray scattering indicating the density of the plurality of CNTs 11a, 11a, ··· is 2.0 nm -1 or more and 5.0 nm -1 or less, and the full width at half maximum Δq (FWHM) is 0.1 nm -1 or more and 2.0 nm-1 It is preferably as follows.

[0034] The CNT aggregate 11, the orientation of the CNTs 11, and the array structure and density of the CNTs 11a can be adjusted by appropriately selecting a spinning method such as dry spinning or wet spinning and the spinning conditions of the spinning method, which will be described later.

[0035] Next, the insulating coating layer 21 that coats the outer surface of the CNT wire 10 will be described.

[0036] The insulating coating layer 21 may be opaque or transparent. When the insulating coating layer 21 is opaque, the carbon nanotube coated wire 1 is used such that when the CNT coated wire 1 is viewed from the outside, the identification mark located on the CNT wire 10 through the insulating coating layer 21 cannot be visually recognized. In this case, when the insulating coating layer 21 becomes thinner due to abrasion or the like, or when a part of the insulating coating layer 21 peels off and the outer surface of the CNT wire 10 is exposed, the thinning or peeling of the insulating coating layer 21 can be confirmed by visually recognizing the identification mark on the outer surface of the CNT wire 10. Since the discriminability of this identification mark is high, the identification mark can be confirmed even from a distance, and the deterioration of the CNT coated wire 1 can be detected early simply and at low cost.

[0037] Also, when a transparent or translucent insulating coating layer 21 is used, the carbon nanotube coated wire 1 is used such that when the CNT coated wire 1 is viewed from the outside, the identification mark located on the CNT wire 10 through the insulating coating layer 21 can be visually recognized. Examples of the CNT coated wire 1 having a transparent insulating coating layer 21 include the following CNT coated wires. (a) The carbon nanotube coated wire 1, in which the refractive index n of the material constituting the insulating coating layer 21 is less than 1.5 and the film thickness of the insulating coating layer 21 / the wire diameter of the CNT wire 10 is less than 0.2. D The carbon nanotube coated wire 1, in which the total light transmittance defined in JIS 7375:2008 of the material constituting the insulating coating layer 21 is 75% or more and the film thickness of the insulating coating layer 21 / the wire diameter of the CNT wire 10 is less than 0.2. (b) The carbon nanotube coated wire 1.

[0038] In the case of the above (a) or (b), the transparency of the insulating coating layer 21 is high, and the identification mark located on the CNT wire 10 can be effectively visually recognized. Also, in the case of the above (b), the total light transmittance specified in JIS 7375:2008 is preferably 90% or more. The refractive index n of the material constituting the insulating coating layer 21 D and the total light transmittance being within the above range can make the identifiability of the identification mark better.

[0039] Also, when the film thickness of the insulating coating layer 21 / the wire diameter of the CNT wire 10 is less than 0.2, the identifiability of the identification mark can be made good. The film thickness of the insulating coating layer 21 and the wire diameter of the CNT wire 10 can be calculated by averaging the information obtained using an image of the cross-section of the CNT-coated electric wire 1 observed with an SEM or an optical microscope for the same cross-section in the radial direction every 10 cm in the longitudinal direction of the 1.0 m CNT-coated electric wire 1.

[0040] As the material of the insulating coating layer 21, the materials used for the insulating coating layer of a coated electric wire using metal as the core wire can be used, for example, thermoplastic resins can be mentioned. Examples of thermoplastic resins include polytetrafluoroethylene (PTFE), polyethylene, polypropylene, polyacetal, polystyrene, polycarbonate, polyamide, polyvinyl chloride, polyvinyl acetate, polyurethane, polymethyl methacrylate, acrylonitrile-butadiene-styrene resin, acrylic resin, etc. These may be used alone or two or more of them may be appropriately mixed and used.

[0041] As shown in FIG. 1, the insulating coating layer 21 may be a single layer, or alternatively, may be two or more layers. Also, if necessary, a layer of a thermosetting resin may be further provided between the outer surface of the CNT wire 10 and the insulating coating layer 21.

[0042] Next, a method for manufacturing the CNT-coated electric wire 1 according to an embodiment of the present invention will be described. The CNT-coated electric wire 1 can be manufactured by first manufacturing CNTs 11a, forming a CNT wire 10 having an identification mark from the plurality of obtained CNTs 11a, and coating an outer peripheral surface of the CNT wire 10 with an insulating coating layer 21.

[0043] The CNTs 11a can be produced by methods such as a floating catalyst method (Japanese Patent No. 5819888) and a substrate method (Japanese Patent No. 5590603). The strands of the CNT wire 10 can be produced by dry spinning (Japanese Patent No. 5819888, Japanese Patent No. 5990202, Japanese Patent No. 5350635), wet spinning (Japanese Patent No. 5135620, Japanese Patent No. 5131571, Japanese Patent No. 5288359), liquid crystal spinning (Japanese Patent Application Laid-Open No. 2014-530964), and the like.

[0044] As a method for coating the outer peripheral surface of the CNT wire 10 obtained as described above with the insulating coating layer 21, a method for coating an insulating coating layer on a core wire of aluminum or copper can be used. For example, a method of melting a thermoplastic resin, which is a raw material of the insulating coating layer 21, and extruding and coating it around the CNT wire 10 can be mentioned.

[0045] The CNT-coated electric wire 1 according to the embodiment of the present invention can be used as a general electric wire such as a wire harness, or a cable may be produced from the general electric wire using the CNT-coated electric wire 1.

[0046] 2. Identification Mark In a carbon nanotube-coated electric wire according to an embodiment, the carbon nanotube wire has an identification mark. The identification mark is provided on at least a part of the exposed outer surface of the carbon nanotube wire or inside the carbon nanotube wire. The identification mark may be for identifying the type, use, and state (e.g., normal state, abnormal state) of the carbon nanotube-coated electric wire. Further, specific information such as information about the electric wire itself or information related to the electric wire may be given to the identification mark. The material of the identification mark is not particularly limited as long as it can be identified by visual observation, binoculars, electromagnetic waves of a specific wavelength such as visible light or other light, magnetism, etc. The carbon nanotube wire can have another wire having a color different from that of the carbon nanotube aggregate as an identification mark. The identification mark can include a capsule. The size of the capsule is not particularly limited, and examples of the capsule include microcapsules and nanocapsules. The capsule can contain a fluorescent substance. Further, the identification mark can be composed of a core part containing a fluorescent substance and a shell part containing silica. The identification mark can include a pigment, a dye, or a material whose color changes according to the temperature change or stress change of the carbon nanotube-coated electric wire. When the identification mark contains a pigment or a dye, the identification mark is located on the outer surface of the carbon nanotube wire, and by making the color of the identification mark different from the color of the part other than the identification mark on the outer surface of the carbon nanotube wire, the identification mark can be visually recognized. Further, the identification mark can include a resin or a magnetic material. When the identification mark contains a magnetic material, the identification mark can be identified by magnetism. Furthermore, the identification mark can be a barcode, particularly a barcode (multi-binary code) composed of three or more barcode lines having different line widths from each other. The identification mark can be a QR code (registered trademark). When the identification mark is a barcode (particularly, a multi-binary code) or a QR code (registered trademark), specific information can be given to these codes.When a barcode or the like composed of thin line patterns is applied as an identification mark to a conventional wire mainly made of metal, the size of the identification mark itself is small and its adhesiveness is low, so the discriminability of the identification mark is low, and a clear identification mark cannot be applied. Further, since the identification mark attached to the conventional wire mainly made of metal is inferior in durability and weather resistance, peeling of the identification mark occurs in a short time, and the visibility deteriorates. On the other hand, in the present embodiment, since the adsorptivity of the identification mark to the CNT wire is high as described above, even when a barcode or the like composed of a fine line pattern is applied as the identification mark, the discriminability of the identification mark is high, and an identification mark with excellent visibility can be obtained. Further, since the identification mark attached to the CNT wire is excellent in durability and weather resistance, peeling of the identification mark does not occur even when used for a long time, and excellent visibility can be maintained. The above effects are more remarkable when barcodes (multi-binary codes) and QR codes (registered trademark) composed of three or more types of barcode lines having different line widths are used as the identification mark. That is, multi-binary codes and QR codes (registered trademark) are composed of finer lines and image patterns than ordinary barcodes, but since the adsorptivity of these codes to the CNT wire is high, an identification mark with excellent discriminability and visibility can be obtained. Further, since the identification mark composed of these codes attached to the CNT wire is excellent in durability and weather resistance, peeling of the identification mark does not occur even when used for a long time, and even better visibility can be maintained. Hereinafter, each material constituting the identification mark will be described in detail.

[0047] (Other wire) Other lines as identification marks are not particularly limited and may be conductive lines or insulating lines. By using a conductive line as an identification mark, it is possible to achieve both conductivity and identifiability of the carbon nanotube-coated electric wire. As the conductive line, an aluminum wire, an aluminum alloy wire, a copper wire, a copper alloy wire, or a combination of these wires can be used. Since these conductive lines have colors different from those of carbon nanotubes themselves, they can be used as identification marks. Since the insulating line can easily control its color and can have a color significantly different from that of the carbon nanotube wire material, the identifiability of the carbon nanotube-coated electric wire can be improved. As the insulating line, a thermoplastic resin, a thermosetting resin wire, etc. can be used. The other lines may be single wires or stranded wires. It is preferable that the other lines are single wires. By forming a stranded wire by twisting the carbon nanotube aggregate and the other wire, a carbon nanotube-coated electric wire with high mechanical strength can be obtained.

[0048] (Capsule) The capsule is, for example, a microcapsule or a nanocapsule having a particle size in the range of several tens of nm to several hundreds of μm. The shape of the capsule is not particularly limited, and for example, spherical, elliptical, etc. can be used. As the encapsulation method, for example, in-situ polymerization method, interfacial polymerization method, coacervation method, spray drying method, dry mixing method, orifice method, etc. can be used.

[0049] (Identification mark having a core part and a shell part) The core part of the identification mark is filled with a liquid material, and the liquid material is held in the core part by covering the liquid material with the shell part. Therefore, when the liquid material is held in the core part, the identification mark has no distinctiveness, and when the liquid material in the core part is released, the distinctiveness can be expressed by the liquid material. For example, when using microcapsules as the identification mark, when high stress or high temperature is applied to the microcapsules, the liquid material is instantaneously released from the microcapsules, and the distinctiveness can be expressed in a short time. Also, when the liquid material is released from the core part little by little over a long period of time (sustained release), the distinctiveness can be gradually expressed.

[0050] The liquid material filled in the core part is not particularly limited as long as it has excellent distinctiveness, and insulating gels, pigments, dyes, fluorescent substances, magnetic materials, etc. described later can be used. Among these liquid materials, it is particularly preferable to use a fluorescent substance as the liquid material because of its excellent distinctiveness in a dark place, etc. Also, the identification mark preferably consists of a core part containing a fluorescent substance and a shell part containing silica. For example, fluorescent silica particles, etc. can be mentioned.

[0051] Also, the material of the shell part is not particularly limited, and thermoplastic resins, thermosetting resins, etc. can be used, but it is preferable to use a thermoplastic resin.

[0052] (Pigment) The pigment is not particularly limited, and for example, red pigments, blue pigments, green pigments, yellow pigments, orange pigments, purple pigments, or combinations of these pigments can be used. Also, inorganic pigments and organic pigments can be used.

[0053] Examples of inorganic pigments include titanium oxide, barium sulfate, calcium carbonate, zinc white, lead sulfate, yellow lead, zinc yellow, red iron oxide (III), cadmium red, ultramarine blue, cobalt blue, chromium oxide green, cobalt green, amber, etc.

[0054] Examples of organic pigments include anthraquinone pigments, aminoanthraquinone pigments, quinacridone pigments, quinacridonequinone pigments, diketopyrrolopyrrole pigments, perylene pigments, perinone pigments, anthraanthrone pigments, benzimidazolone pigments, disazo condensate pigments, azo pigments, thioindigo pigments, pyranthrone pigments, dioxazine pigments, quinophthalone pigments, isoindoline pigments, phthalocyanine pigments, and the like.

[0055] By using a pigment as the material for the identification mark, the visibility of the identification mark can be improved.

[0056] (Dye) The dye is not particularly limited, but for example, red dyes, blue dyes, green dyes, yellow dyes, or combinations of these dyes can be used. Examples of dyes include azo dyes, anthraquinone dyes, phthalocyanine dyes, quinoneimine dyes, quinoline dyes, nitro dyes, carbonyl dyes, methine dyes, and the like. By using a dye as the material for the identification mark, the visibility of the identification mark can be improved.

[0057] (Fluorescent substance) The identification mark can also contain a fluorescent substance. By using a fluorescent substance as the material for the identification mark, the carbon nanotube-coated wire can be recognized even in a dark place. There are no particular restrictions on the fluorescent substance, and it can be an organic compound, an inorganic compound, semiconductor particles, etc. The material of the fluorescent substance is not particularly limited, and examples include C.I. Basic Red 1, 2, 9, 12, 13, 14, 17, C.I. Basic Violet 1, 3, 7, 10, 11:1, 14, C.I. Acid Yellow 73, 184, 250, C.I. Acid Red 51, 52, 92, 94, C.I. Direct Yellow 11, 24, 26, 87, 100, 147, C.I. Direct Orange 26, 29, 29:1, 46, C.I. Direct Red 1, 13, 17, 239, 240, 242, 254, and the like.

[0058] Also, when using a fluorescent substance, the insulating coating layer is preferably semi-transparent or transparent, and more preferably transparent. When the insulating coating layer is transparent, the identification mark can be recognized even in a dark place. Further, when the insulating coating layer is semi-transparent, when the insulating coating layer becomes thin due to abrasion or the like, only the thinned portion becomes easily recognizable. In particular, in a dark place, only this portion emits fluorescence, so that the deteriorated portion of the carbon nanotube-coated electric wire can be effectively identified. Further, instead of the fluorescent substance, an absorptive substance may be used.

[0059] (Discoloring material) The identification mark can include a material that changes to a color different from the normal state when a specific characteristic value or physical property value of the carbon nanotube-coated electric wire changes and the carbon nanotube-coated electric wire becomes in an abnormal state where it cannot be used. For example, the identification mark can include a discoloring material whose color changes according to a temperature change or a stress change of the carbon nanotube-coated electric wire. The discoloring material may change color reversibly or irreversibly. That is, when the discoloring material changes color reversibly, it changes color when the carbon nanotube-coated electric wire becomes in an abnormal state, but returns to the original color when the carbon nanotube-coated electric wire returns to the normal state. On the other hand, when the discoloring material changes color irreversibly, it changes color when the carbon nanotube-coated electric wire becomes in an abnormal state, and the color after the change does not change even when the carbon nanotube-coated electric wire returns to the normal state.

[0060] When using an identification mark including a discoloring material whose color changes according to a temperature change, when the carbon nanotube-coated electric wire is placed in a low-temperature or high-temperature environment and reaches a temperature at which it cannot be used, such an abnormal state can be recognized by visually observing the color change of the identification mark. Therefore, it is not necessary to directly measure the temperature of the carbon nanotube-coated electric wire, and since the color change can be confirmed even from a distance, the abnormal state of the carbon nanotube-coated electric wire can be simply confirmed at low cost, and the deterioration of the carbon nanotube-coated electric wire can be detected at an early stage.

[0061] Examples of discoloring materials that change color according to temperature changes include, for example, pigments containing leuco dyes, color-developing substances, and discoloration temperature adjusters, and those encapsulated by coating these with a resin. Examples of leuco dyes include diphenylmethane phthalides, indolyl phthalides, diphenylmethane azaphthalides, phenylindolyl azaphthalides, fluorans, styrylnaphthyridines, diazaro damin lactones, and the like. It is also possible to adjust the types of colors that change and the discoloration temperature range by changing the composition of the leuco dye, color-developing substance, and discoloration temperature adjuster.

[0062] When using an identification mark including a discoloring material that changes color according to stress change, when the carbon nanotube-coated wire is bent or a heavy object such as snow is placed on the carbon nanotube-coated wire, when a high stress is applied to the carbon nanotube-coated wire, such an abnormal state can be confirmed by visually recognizing the color change of the identification mark. Therefore, it is not necessary to directly measure the stress applied to the carbon nanotube-coated wire, and since the color change can be confirmed even from a distance, the abnormal state of the carbon nanotube-coated wire can be simply and inexpensively confirmed, and the deterioration of the carbon nanotube-coated wire can be detected early. In addition, CNT has extremely high strength compared to metal wires, and there is a possibility that deterioration may preferentially occur around the connecting member. Such a state change can also be recognized by the color change of the identification mark. Therefore, it is also preferable to use an identification mark around the connecting member.

[0063] (Resin) The identification mark can also contain a resin. In this case, since the resin and CNT that constitute the identification mark are different materials on the outer surface of the carbon nanotube wire, the surface properties, color, texture, etc. of these materials will be different, and the identification mark can be visually recognized. As the resin that constitutes the identification mark, any material of thermoplastic resin or thermosetting resin can be used.

[0064] The thermoplastic resin is not particularly limited, and examples thereof include vinyl polymers such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, (meth)acrylic resins, ethylene-vinyl acetate copolymers, and ethylene-vinyl alcohol copolymers; polyester resins such as polylactic acid resin, polyethylene terephthalate, and polybutylene terephthalate; polyamides such as nylon and polyamideamine; polyvinyl acetal resins such as polyvinyl acetoacetal, polyvinyl benzal, and polyvinyl butyral resin; ionomer resins; polyphenylene ether; polyphenylene sulfide; polycarbonate; polyether ether ketone; polyacetal; ABS resin; LCP (liquid crystal polymer); fluororesin; urethane resin; elastomer; or modified products of these resins.

[0065] The thermosetting resin is not particularly limited, and examples thereof include phenolic resins, urea resins, melamine resins, epoxy resins, unsaturated polyester resins, polyimides, polyurethanes, and silicone resins.

[0066] (Magnetic material) The identification mark can include a magnetic material. By including a magnetic material in the identification mark, the identification mark can be identified by a device capable of detecting magnetism. The magnetic material is not particularly limited, and examples thereof include iron oxides such as magnetite, maghemite, and ferrite, or iron oxides containing other metal oxides, metals such as Fe, Co, and Ni, or alloys of these metals with metals such as Al, Co, Cu, Pb, Mg, Ni, Sn, Zn, Sb, Be, Bi, Cd, Ca, Mn, Se, Ti, W, and V, and mixtures thereof.

[0067] (Provision of information) Specific information can also be added to the identification mark. For example, specific information can be added by directly printing predetermined characters, figures, numbers, etc. on the identification mark. Also, specific code information such as barcodes, QR codes (registered trademarks), etc. can be printed on the identification mark itself or on the identification mark. The barcode can be a barcode (multi-binary code) composed of three or more barcode lines with different line widths. These code information can be optically read. In another example, an IC chip can be provided on the identification mark, and specific information can be read with an IC chip reader or written with an IC chip writer. Also, in another example, the identification mark contains a magnetic material, and specific information is added to the identification mark by the magnetic material, and the information can be read with a magnetic reader.

[0068] (Method for attaching an identification mark) The method for attaching an identification mark to a carbon nanotube wire is not particularly limited, and for example, the following methods can be mentioned. (a) A method of forming a carbon nanotube wire from a mixed material obtained by mixing a material of an identification mark having a predetermined size and shape and a material of a carbon nanotube wire other than the material of the identification mark. (b) A method of printing an identification mark on the outer surface of a carbon nanotube wire. (c) A method of chemically reacting the material of the outer surface of a carbon nanotube wire with the material of the identification mark to form a chemical bond between the material of the outer surface and the material of the identification mark.

[0069] In the method of (a) above, the mixing method for obtaining the mixed material is not particularly limited, and examples thereof include ball mill mixing, bead mill mixing, V-type mixer, container rotation type mixing methods such as a Borre container mixer, a method of mixing by mechanical stirring force such as a ribbon mixer, and a method of stirring and mixing by an air current such as a fluidized bed. A carbon nanotube wire can be obtained from the obtained mixed material. For example, when the identification mark includes a core portion containing a fluorescent substance and a shell portion containing silica, a carbon nanotube wire can be obtained by twisting these materials while mixing them with the elementary wires of the carbon nanotube aggregate.

[0070] The method of (b) above is not particularly limited, and examples thereof include a method of printing an ink containing the material of the identification mark on the outer surface of the carbon nanotube wire. The printing method of the ink is not particularly limited, and examples thereof include inkjet printing, super inkjet printing, screen printing, transfer printing, offset printing, jet printing method, dispenser, jet dispenser, needle dispenser, comma coater, slit coater, die coater, gravure coater, letterpress printing, intaglio printing, gravure printing, soft lithography, dip pen lithography, spray coater, spin coater, dip coater, electrodeposition coating, and the like. The ink can contain a solvent, a dispersant, a surfactant, etc. as components other than the material of the identification mark, if necessary.

[0071] The method in (c) above is not particularly limited, but examples include a method of chemically reacting an organic peroxide or the like with the carbon nanotube wire on the outer surface of the carbon nanotube wire and the material of the identification mark. For example, an organic peroxide thermally decomposes at a relatively low temperature or reacts with a reducing substance to easily generate free radicals. The properties of the generated free radicals can promote the addition of the identification mark material to the unsaturated double bond in the outer surface material, the extraction of hydrogen atoms, etc., and the addition of the identification mark material. The organic peroxide is not particularly limited, and examples thereof include ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxyester, peroxydicarbonate, and the like.

[0072] (Shape, size, and position of the identification mark) The shape and size of the identification mark and the position of the identification mark on the carbon nanotube wire are not particularly limited. Depending on the purpose of applying the identification mark, the shape, size, and position of the identification mark can be determined as appropriate. The shape of the identification mark can be, for example, a polygon, a circle, a shape surrounding the outer circumference of the carbon nanotube wire, a character, a pattern consisting of multiple colors, etc. Also, the size of the identification mark is not particularly limited.

[0073] Figs. 5(a) to 5(d) are schematic views showing the CNT-coated electric wire 1 having an identification mark, and Fig. 5(e) is an enlarged view of the barcode which is the identification mark 31 in Fig. 5(b). In Figs. 5(a) to 5(d), the CNT wire 10 schematically represents its outer surface by a solid line, the internal structure of the CNT-coated electric wire 1 is omitted, and the outer surface of the insulating coating layer is represented by a dotted line.

[0074] FIG. 5(a) shows an example where the identification mark 31 is located at at least one end 32 in the longitudinal direction 33 of the CNT coated wire 1 on the outer surface of the CNT wire 10. The identification mark 31 may be located at one end 32 of the CNT wire 10 or at both ends 32. In FIG. 5(a), for example, when the insulating coating layer is transparent, the wire end for connection to the terminal can be visually recognized by the identification mark 31.

[0075] FIG. 5(b) shows an example where the identification marks 31 are located at regular intervals in the longitudinal direction 33 of the CNT coated wire 1 on the outer surface of the CNT wire 10. In FIG. 5(b), for example, when the insulating coating layer is transparent, the identification mark 31 can be used as a length mark for recognizing the length of the CNT coated wire 1.

[0076] FIG. 5(c) shows an example in which an identification mark 31 extending from the first end to the second end in the longitudinal direction 33 of the CNT coated wire 1 is provided on the outer surface of the CNT wire 10. That is, the identification marks 31 are continuously provided along the longitudinal direction 33 between both ends. In FIG. 5(c), for example, when the insulating coating layer is transparent, an aspect can be cited in which the identification mark 31 contains a material whose color changes according to the temperature change or stress change of the CNT coated wire 1. In this aspect, when a specific part of the CNT coated wire 1 deteriorates due to a low-temperature or high-temperature environment or a high stress load, only the identification mark 31 located at the specific part exhibits a color different from that of the identification marks 31 located at other parts. Therefore, the deteriorated part of the CNT coated wire 1 can be detected at an early stage and countermeasures can be taken.

[0077] Further, FIG. 5(d) shows an example in which a barcode is provided as the identification mark 31 on the outer surface of the CNT wire 10, and specific information regarding the CNT-coated wire 1 can be imparted to the barcode. In one embodiment, as shown in FIG. 5(e), this identification mark 31 is a barcode (multi-binary code) composed of three or more types of barcode lines having different line widths L from each other. For example, when a barcode including a thin barcode line of 100 μm or less is applied as an identification mark to a conventional metal-based wire, it is difficult to identify each line of the barcode because the adhesiveness of the identification mark is low. Further, since the identification mark attached to the conventional wire is inferior in durability and weather resistance, the identification mark peels off in a short time. In contrast, in the present embodiment, since the adsorptivity of the identification mark to the CNT wire is high as described above, even when a barcode composed of fine barcode lines is applied as the identification mark, the discriminability of the barcode is enhanced. Further, since the identification mark attached to the CNT wire is excellent in durability and weather resistance, it is less likely that the identification mark peels off even when used for a long period of time. When a pigment, a dye, a fluorescent substance, a discoloring material, or the like is used as the material of the barcode, the visibility of the barcode can be further improved.

[0078] FIG. 6 is a schematic diagram showing another CNT-coated wire 1 having an identification mark, and is a cross-sectional view of the CNT-coated wire 1 as seen in a cross-section perpendicular to its longitudinal direction. In FIG. 6, the CNT wire 10 is a stranded wire, but is schematically shown. As shown in FIG. 6, the CNT wire 10 has an identification mark 40, and the core portion of the identification mark 40 is filled with a fluorescent substance. When the insulating coating layer 21 is thinned due to friction or the like to form a thin film portion 38, a large stress is also applied to the identification mark 40 located in the vicinity of the thin film portion 38, and the fluorescent substance in the identification mark 40 is released and flows along the twisting direction of the CNT wire 10. Since the thin film portion 38 has a concave shape, finally the fluorescent substance accumulates in the thin film portion 38. As a result, the discriminability of the thin film portion becomes prominent, and the occurrence of the thin film portion 38 can be detected at an early stage.

[0079] FIG. 7 is a schematic diagram showing another CNT-coated electric wire 1 having an identification mark. In FIG. 7, although the CNT wire 10 is a stranded wire, its outer surface is schematically represented by a solid line, the internal structure of the CNT-coated electric wire 1 is omitted, and the outer surface of the insulating coating layer is represented by a dotted line. In the CNT-coated electric wire 1 of FIG. 7, the fluorescent substance 39 is distributed over the entire CNT wire 10. The CNT wire 10 of FIG. 7 can be obtained by twisting while mixing the fluorescent substance with the strands of the carbon nanotube aggregate.

Example

[0080] (Example 1) Using the floating catalyst chemical vapor deposition (CCVD) method, a raw material solution containing decahydronaphthalene as a carbon source, ferrocene as a catalyst, and thiophene as a reaction promoter was supplied by spray spraying into an alumina tube with an inner diameter of φ60 mm and a length of 1600 mm heated to 1300° C. by an electric furnace of a CNT production apparatus. The carrier gas was supplied with hydrogen at 9.5 L / min. The produced CNTs were continuously wound up and recovered to obtain a CNT wire having a diameter of about 100 μm and a length of 75 m. Next, the obtained CNT wire was heated to 500° C. in the atmosphere and further purified by acid treatment. Thereafter, the purified CNT aggregate was subjected to nitric acid doping. Subsequently, 100 mL of an ethanol solution (0.1 wt%) of fluorescent silica particles (Quartz dot, manufactured by Furukawa Advanced Engineering Co., Ltd.) having a particle size of 0.1 μm containing rhodamine 6G was prepared, and the above CNT wire was immersed in this solution for 1 hour, and then the CNT wire was taken out of the solution and dried at 60° C. for 4 hours to obtain a CNT wire labeled with an identification mark composed of fluorescent silica particles. Next, a thermoplastic resin (polypropylene) was melted using an extrusion molding machine and extruded around the CNT wire to obtain a CNT-coated electric wire having a transparent insulating coating layer with a thickness of about 50 μm on the outer surface of the CNT wire. When the obtained CNT-coated electric wire was irradiated with a laser diode having an emission wavelength of 532 nm at night and confirmed through an optical filter (LOPF-25C-532, manufactured by Sigma Koki Co., Ltd.), the CNT wire could be clearly visually recognized by the green fluorescence derived from the fluorescent silica particles (fluorescent substance) which is the identification mark.

Description of Symbols

[0081] 1 Carbon nanotube-coated wire 10 Carbon nanotube wire 11 Carbon nanotube aggregate 11a Carbon nanotube 21 Insulation coating layer 31, 40 Identification mark 32 End portion 33 Longitudinal direction 38 Thin film portion 39 Fluorescent substance

Claims

1. A carbon nanotube wire having one or more carbon nanotube aggregates each composed of a plurality of carbon nanotubes, and an insulating coating layer that coats the carbon nanotube wire; Equipped with The carbon nanotube wire has an identification mark, The carbon nanotube coated electric wire, wherein the identification mark is a microcapsule having a core portion containing a fluorescent substance and a shell portion containing silica.

2. A carbon nanotube wire formed by twisting together a plurality of carbon nanotube aggregates each composed of a plurality of carbon nanotubes, and an insulating coating layer that coats the carbon nanotube wire; Equipped with The carbon nanotube aggregate or the carbon nanotube wire has an identification mark in a plurality of gaps, The carbon nanotube coated electric wire, wherein the identification mark is a microcapsule having a core portion containing a fluorescent substance and a shell portion containing silica.

3. The refractive index n of the material constituting the insulating coating layer Ｄ 3. The carbon nanotube covered electric wire according to claim 1, wherein the thickness of the insulating covering layer is less than 1.5, and the ratio of the thickness of the insulating covering layer to the diameter of the carbon nanotube wire is less than 0.

2.

4. 3. The carbon nanotube-coated electric wire according to claim 1, wherein the material constituting the insulating coating layer has a total light transmittance of 75% or more as defined in JIS 7375:2008, and the ratio of the thickness of the insulating coating layer to the wire diameter of the carbon nanotube wire is less than 0.

2.

5. the carbon nanotube wire is composed of a plurality of the carbon nanotube aggregates, 5. The carbon nanotube-coated electric wire according to claim 1, wherein a half-width Δθ of an azimuth angle in an azimuth plot by small-angle X-ray scattering showing the orientation of a plurality of the carbon nanotube aggregates is 60° or less.

6. The q value of the peak top in the (10) peak of the scattering intensity by X-ray scattering showing the density of the plurality of carbon nanotubes is 2.0 nm. －１ 5.0nm or more －１ and the half width Δq is 0.1 nm or less. －１ 2.0nm or more －１ 6. The carbon nanotube covered electric wire according to claim 1, wherein:

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