JP2019079813A - Carbon nanotube coated electric wire, coil and coated electric wire - Google Patents

Abstract

To provide a carbon nanotube coated electric wire that can inhibit the occurrence of peeling even at high temperature and achieve excellent flex resistance while having excellent conductivity comparable to that of a wire made of copper, aluminum or the like, to provide a coil and to provide a coated electric wire.SOLUTION: A carbon nanotube coated electric wire 1 comprises a carbon nanotube wire 10 comprising a single or a plurality of carbon nanotube aggregates 11 each composed of a plurality of carbon nanotubes 11a and an insulation coating layer 21 coating the carbon nanotube wire. The thermal expansion coefficient of the carbon nanotube wire 10 is 0/K or less and the thermal expansion coefficient of the insulation coating layer 21 is 5×10/K or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a carbon nanotube coated electric wire in which a carbon nanotube wire composed of a plurality of carbon nanotubes is coated with an insulating material, a coil using the carbon nanotube coated electric wire, and a coated electric wire.

  Carbon nanotubes (hereinafter sometimes referred to as "CNT") are materials having various properties, and their application in many fields is expected.

  For example, CNT is a single layer of a tubular body having a network structure of a hexagonal lattice, or a three-dimensional network structure composed of multiple layers arranged substantially coaxially, which is lightweight, conductive, and thermally conductive. Excellent in various properties such as flexibility and mechanical strength. However, it is not easy to wire CNTs, and no technology has been proposed for utilizing CNTs as wires.

  As an example of a technology using a few CNT lines, using CNT as a substitute for metal which is a filling material of a via hole formed in a multilayer wiring structure is considered. Specifically, in order to reduce the resistance of the multilayer wiring structure, multilayer CNTs in which a plurality of incisions of the multilayer CNT concentrically extended to the end far from the growth origin of the multilayer CNT are brought into contact with the conductive layer A wiring structure used as an interlayer wiring of two or more conductive layers has been proposed (Patent Document 1).

  As another example, in order to further improve the conductivity of the CNT material, a CNT material in which a conductive deposit made of metal or the like is formed at the electrical junction of adjacent CNT wires is proposed, and such a CNT material Has been disclosed to be applicable to a wide range of applications (Patent Document 2). Moreover, the heater which has a thermally-conductive member made from the matrix of CNT is proposed from the outstanding thermal conductivity which a CNT wire has (patent document 3).

  On the other hand, as a power line or signal line in various fields such as automobiles and industrial equipment, an electric wire made of a core wire made of one or a plurality of wires and an insulation coating which covers the core wire is used. As a material of the wire which comprises a core wire, although a copper or copper alloy is usually used from a viewpoint of an electrical property, aluminum or an aluminum alloy is proposed from a viewpoint of weight reduction in recent years. For example, the specific gravity of aluminum is about 1/3 of the specific gravity of copper, and the conductivity of aluminum is about 2/3 of that of copper (based on 100% IACS for pure copper, about 66% IACS for pure aluminum) There is a need to increase the cross-sectional area of the aluminum wire to about 1.5 times the cross-sectional area of the copper wire in order to flow the same current as the copper wire to the aluminum wire. Even if the aluminum wire is used, since the mass of the aluminum wire is about half of the mass of the copper wire, using the aluminum wire is advantageous from the viewpoint of weight reduction.

  In addition, with the advancement of performance and functionality of automobiles, industrial equipment, etc., along with this, the number of installation of various electrical equipments, control equipments, etc. increases, and electric wiring bodies used for these equipments The number of wires and heat generation from the core tend to increase. Therefore, it is required to improve the heat radiation characteristics of the electric wire without impairing the insulation property by the insulation coating. On the other hand, in order to improve the fuel consumption of moving bodies such as automobiles for environmental protection, weight reduction of the wire is also required.

Unexamined-Japanese-Patent No. 2006-120730 Japanese Patent Application Publication No. 2015-523944 JP, 2015-181102, A

  The present invention is a carbon nanotube coated electric wire and coil capable of achieving excellent bending resistance while suppressing the occurrence of peeling even at high temperature while having excellent conductivity comparable to a wire made of copper, aluminum or the like. And coated wires are intended to be provided.

In order to achieve the above object, a carbon nanotube coated electric wire of the present invention comprises a carbon nanotube wire comprising a plurality of carbon nanotube aggregates composed of a plurality of carbon nanotubes twisted together, and an insulation coating for covering the carbon nanotube wire. A layer, the thermal expansion coefficient of the carbon nanotube wire is 0 / K or less, and the thermal expansion coefficient of the insulating covering layer is 5 × 10 ⁻⁶ / K or more.

It is preferable that the thermal expansion coefficient of the said carbon nanotube wire is 0 / K or less, and the thermal expansion coefficient of the said insulation coating layer is 25 * 10 < ^-6 > / K or more.

  The number of twists of the carbon nanotube wire is preferably 20 T / m or more and 1500 T / m or less.

Moreover, it is preferable that the thermal expansion coefficient of the said insulation coating layer is 400 * 10 < ^-6 > / K or less.

  The half width Δθ of the azimuth angle in an azimuth plot by small angle X-ray scattering showing the orientation of the plurality of carbon nanotube aggregates is preferably 60 ° or less.

Further, it is more the (10) of the scattering intensity by X-ray scattering shows a density of the carbon nanotubes q value of the peak top in the peak 2.0 nm ^-1 or 5.0 nm ^-1 or less, and the half-value width Δq 0 .1nm is preferably not ^-1 to 2.0 nm ^-1 or less.

  The ratio of the cross-sectional area in the radial direction of the insulating covering layer to the cross-sectional area in the radial direction of the carbon nanotube wire is preferably 0.01 or more and 1.5 or less.

The cross-sectional area in the radial direction of the carbon nanotube wire is preferably 0.001 mm ² or more and 20 mm ² or less.

  Further, the insulating covering layer may contain other carbon nanotubes.

  The insulating covering layer has a first insulating covering layer formed on the outer periphery of the carbon nanotube wire, and a second insulating covering layer formed on the outer periphery of the first insulating covering layer, and the second insulating covering layer The content of the other carbon nanotubes contained in the layer is preferably smaller than the content of the other carbon nanotubes contained in the first insulating covering layer.

  Moreover, it is preferable that the coil of this invention is formed by winding the said carbon nanotube coated electric wire.

Furthermore, the coated electric wire of the present invention comprises a conductor and an insulating covering layer covering the conductor, the thermal expansion coefficient of the conductor is 0 / K or less, and the thermal expansion coefficient of the insulating covering layer is 5 × 10 ^-6 / K or more.

Unlike a metal core wire, a carbon nanotube wire using a carbon nanotube as a core wire is anisotropic in thermal conduction, and heat is preferentially conducted in the longitudinal direction as compared with the radial direction. That is, since the carbon nanotube wire has anisotropic heat dissipation characteristics, it has excellent heat dissipation as compared to a metal core wire. Therefore, the design of the insulating covering layer covering the core wire using carbon nanotubes needs to be designed differently from the insulating covering layer covering the metallic core wire. According to the present invention, since the thermal expansion coefficient of the carbon nanotube wire is 0 / K or less, and the thermal expansion coefficient of the insulating covering layer is 5 × 10 ⁻⁶ / K or more, the current exceeding the allowable current value Even if the carbon nanotube wire shrinks when the temperature of the carbon nanotube wire becomes high due to the use environment such as the flow of water, the insulation coating layer follows the shrinkage of the carbon nanotube wire and expands. By doing this, peeling of the insulating coating layer from the carbon nanotube wire made of a stranded wire can be suppressed, and excellent bending resistance can be realized. In addition, weight reduction can be realized as compared to metal-coated wires such as copper and aluminum.

  Moreover, the peeling between a carbon nanotube wire and an insulation coating layer can be suppressed because the twist number of a carbon nanotube wire is 20 T / m or more and 1500 T / m or less.

In addition, when the thermal expansion coefficient of the insulating covering layer is 400 × 10 ⁻⁶ / K or less, the increase or decrease in volume due to the temperature change is small. Therefore, when wiring a carbon nanotube coated electric wire according to a groove, it is hard to shift from a groove. In addition, when a carbon nanotube coated electric wire is used for a coil, it is difficult for the coil to loosen.

  In addition, the carbon nanotube aggregate in the carbon nanotube wire has high orientation because the half width Δθ of the azimuth angle in the azimuth plot by small angle X-ray scattering of the carbon nanotube aggregate in the carbon nanotube wire is 60 ° or less. The heat generated by the carbon nanotube wire is less likely to be conducted to the insulating coating layer, and the heat dissipation characteristics are improved.

Further, q values of the peak top in (10) the peak of scattering intensity by X-ray scattering of aligned carbon nanotubes is at 2.0 nm ^-1 or 5.0 nm ^-1 or less, and the half-value width Δq is 0.1 nm ^-1 When the thickness is 2.0 nm ⁻¹ or less, carbon nanotubes can be present at a high density, and thus the heat generated by the carbon nanotube wire becomes more difficult to conduct to the insulating coating layer, and the heat dissipation characteristics are improved.

  Furthermore, when the ratio of the cross-sectional area in the radial direction of the insulating coating layer to the cross-sectional area in the radial direction of the carbon nanotube wire is 0.01 or more and 1.5 or less, a thin insulating coating layer is easily formed. In such cases, further weight reduction can be realized without losing the insulation.

  Furthermore, since the insulating covering layer contains other carbon nanotubes, the thermal conductivity of the insulating covering layer is higher than in the case where the insulating covering layer does not contain CNT as a filler, and the carbon nanotube wire has a high temperature. It is possible to accelerate the response of the thermal expansion of the insulating covering layer when it is reached, and to further suppress the occurrence of peeling.

  Furthermore, since the content of other carbon nanotubes contained in the second insulating covering layer constituting the insulating covering layer is smaller than the content of other carbon nanotubes contained in the first insulating covering layer, the occurrence of peeling occurs. Weight reduction can be realized while suppressing the

It is an explanatory view of a carbon nanotube covering electric wire concerning an embodiment of the present invention. It is explanatory drawing of the carbon nanotube wire used for the carbon nanotube coated electric wire which concerns on embodiment of this invention. (A) A figure is a figure showing an example of a two-dimensional scattering image of scattering vector q of a plurality of carbon nanotube aggregate by SAXS, and a figure (b) shows an origin of a position of transmitting X-rays in a two-dimensional scattering image It is a graph which shows an example of azimuth angle-scattering intensity of arbitrary scattering vectors q which are made into. It is a graph which shows the relationship of q value-intensity by WAXS of a plurality of carbon nanotubes which constitute a carbon nanotube aggregate.

  Hereinafter, a carbon nanotube coated electric wire according to an embodiment of the present invention will be described with reference to the drawings.

[Composition of carbon nanotube coated wire]
As shown in FIG. 1, a carbon nanotube coated electric wire (hereinafter sometimes referred to as "CNT coated electric wire") 1 according to an embodiment of the present invention is sometimes referred to as a carbon nanotube wire (hereinafter referred to as a "CNT wire"). The outer peripheral surface of 10) 10 is covered with the insulating covering layer 21. That is, the insulating coating layer 21 is coated along the longitudinal direction of the CNT wire 10. In the CNT-coated electric wire 1, the entire outer peripheral surface of the CNT wire 10 is covered with the insulating covering layer 21. Further, in the CNT-coated electric wire 1, the insulating covering layer 21 is in an aspect in direct contact with the outer peripheral surface of the CNT wire 10. In FIG. 1, the CNT wire 10 is a strand (single wire) formed of one CNT wire 10. However, the CNT wire 10 may be in the form of a stranded wire obtained by twisting a plurality of CNT wires 10. By setting the CNT wire 10 in the form of a stranded wire, the equivalent circle diameter and the cross-sectional area of the CNT wire 10 can be appropriately adjusted.

  As shown in FIG. 2, the CNT wire 10 is sometimes referred to as a carbon nanotube assembly (hereinafter referred to as "CNT assembly") composed of a plurality of CNTs 11a, 11a, ... having a layer structure of one or more layers. 11) It is formed by bundling one or more of eleven. Here, the CNT wire means a CNT wire having a ratio of CNT of 90% by mass or more. In addition, plating and the dopant are excluded in calculation of the CNT ratio in a CNT wire. The CNT assembly 11 has a linear shape, and the plurality of CNT assemblies 11, 11, ... in the CNT wire 10 are arranged substantially in the long axis direction. Therefore, the plurality of CNT aggregates 11, 11, ... in the CNT wire 10 are oriented. Although the equivalent circle diameter of the CNT wire 10 which is a strand wire is not specifically limited, For example, they are 0.1 mm or more and 15 mm or less.

The coefficient of thermal expansion of the CNT wire 10 is 0 / K or less, preferably −10 × 10 ⁻⁶ / K to 0 / K. Moreover, when the CNT wire 10 is sweet-twisted, the thermal expansion coefficient of the CNT wire 10 is, for example, −10 × 10 ⁻⁶ / K to 0 / K, and when the CNT wire 10 is strongly-twisted, the CNT wire The coefficient of thermal expansion of 10 is, for example, −5 × 10 ⁻⁶ / K to 0 / K.

  The CNT assembly 11 is a bundle of CNTs 11 a having a layer structure of one or more layers. The longitudinal direction of the CNTs 11 a forms the longitudinal direction of the CNT assembly 11. The plurality of CNTs 11a, 11a,... In the CNT assembly 11 are arranged substantially in the same longitudinal direction. Therefore, the plurality of CNTs 11a, 11a,... In the CNT assembly 11 are oriented. The equivalent circle diameter of the CNT assembly 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 CNTs 11 a is, for example, 1.0 nm or more and 5.0 nm or less.

  The CNTs 11a constituting the CNT assembly 11 are cylindrical bodies having a single layer structure or a multilayer structure, and are respectively called SWNT (single-walled nanotubes) and MWNT (multi-walled nanotubes). In FIG. 2, for convenience, only the CNTs 11 a having a two-layer structure are described, but the CNT aggregate 11 includes CNTs having a three-layer structure or more and a CNT having a single-layer structure. It may be formed of CNT having a layer structure of three or more layer structure or CNT having a layer structure of single layer structure.

  The CNT 11a having a two-layer structure is a three-dimensional network structure in which two cylindrical bodies T1 and T2 having a network structure of a hexagonal lattice are arranged substantially coaxially, and is called DWNT (Double-walled nanotube) . The hexagonal lattice, which is a structural unit, is a six-membered ring having a carbon atom at its apex, and adjacent to another six-membered ring, these are continuously bonded.

  The properties of the CNTs 11a depend on the chirality of the above-mentioned cylindrical body. The chirality is roughly classified into an armchair type, a zigzag type, and a chiral type. The armchair type is metallic, the zigzag type is semiconductive and semimetallic, and the chiral type is semiconductive and semimetallic. Therefore, the conductivity of the CNTs 11a largely differs depending on which chirality the tubular body has. In the CNT aggregate 11 constituting the CNT wire 10 of the CNT-coated electric wire 1, it is preferable to increase the proportion of armchair-type CNTs 11a exhibiting metallic behavior, in order to further improve the conductivity.

  On the other hand, it is known that the chiral CNTs 11a exhibit metallic behavior by doping the chiral CNTs 11a exhibiting a semiconducting behavior with a material having an electron donating property or an electron accepting property (different element). In addition, in general metals, the doping of different elements causes scattering of conduction electrons inside the metal to lower the conductivity, but similar to this, the CNT 11a showing metallic behavior is doped with different elements. If it does, it causes a decrease in conductivity.

  Thus, the doping effects on the CNTs 11a showing the behavior of the metal and the CNTs 11a showing the behavior of the semiconductivity are in a trade-off relationship from the viewpoint of the conductivity, and thus the behavior of the metal theoretically appears. It is desirable that the CNTs 11a and the CNTs 11a exhibiting the behavior of the semiconductor property are separately manufactured, and the doping process is performed only on the CNTs 11a exhibiting the behavior of the semiconductor property, and then these are combined. However, it is difficult to selectively make the CNT 11a showing metallic behavior and the CNT 11a showing semiconducting behavior selectively with the current manufacturing technology, and exhibits the behavior of the semiconducting and CNT 11a showing metallic behavior It is produced in a state in which the CNTs 11a are mixed. Therefore, in order to further improve the conductivity of the CNT wire 10 composed of a mixture of CNTs 11a exhibiting metallic behavior and CNTs 11a exhibiting semiconducting behavior, a layer of CNTs 11a in which doping treatment with different elements and molecules is effective It is preferred to select the structure.

  For example, a CNT having a smaller number of layers, such as a two-layer structure or a three-layer structure, is relatively more conductive than a CNT having a larger number of layers, and when doped, the two-layer structure or three layers The doping effect in the structured CNT is the highest. Therefore, in order to further improve 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 ratio of CNTs having a two-layer structure or a three-layer structure to the entire CNTs is preferably 50 number% or more, and more preferably 75 number% or more. The proportion of CNTs having a two-layer structure or a three-layer structure can be determined by observing and analyzing the cross section of the CNT assembly 11 with a transmission electron microscope (TEM) and measuring a predetermined number of arbitrary CNTs within the range of 50 to 200. It can be calculated by selecting and measuring the number of layers of each CNT.

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

  Fig.3 (a) is a figure which shows an example of the two-dimensional scattering image of the scattering vector q of several CNT assembly 11,11, ... by small angle X ray scattering (SAXS), and FIG.3 (b) is shown. It is a graph which shows an example of the azimuth plot which shows the relationship of the azimuth angle-scattering intensity of arbitrary scattering vectors q which make the position of transmission X ray an origin in a two-dimensional scattering image.

  SAXS is suitable for evaluating a structure having a size of several nm to several tens of nm. For example, the orientation of the CNT 11a having an outer diameter of several nm and the orientation of the CNT aggregate 11 having an outer diameter of several tens nm by analyzing the information of the X-ray scattering image by the following method using SAXS Can be evaluated. For example, when an X-ray scattering image of the CNT wire 10 is analyzed, as shown in FIG. 3A, the x component of the scattering vector q (q = 2π / d, d is the lattice spacing) of the CNT assembly 11 The distribution of qy, which is the y component, is narrower than qx. Moreover, as a result of analyzing the azimuth plot of SAXS about the same CNT wire 10 as FIG. 3 (a), half value width (DELTA) (theta) of the azimuth angle in the azimuth plot shown in FIG.3 (b) is 48 degrees. From these analysis results, in the CNT wire 10, it can be said that the plurality of CNTs 11a, 11a,... And the plurality of CNT aggregates 11, 11,. As described above, since the plurality of CNTs 11a, 11a,... And the plurality of CNT aggregates 11, 11,. It is easy to be dissipated while transmitting smoothly along the longitudinal direction of the. Therefore, the CNT wire 10 can adjust the heat radiation route in the longitudinal direction and the cross-sectional direction of the diameter by adjusting the orientation of the CNTs 11 a and the CNT aggregate 11, and therefore, the heat radiation characteristics superior to the metal core wire. Demonstrate. In addition, orientation refers to the angle difference of the vector of the CNT and the CNT assembly inside with respect to the vector V in the longitudinal direction of the stranded wire produced by twist-collecting CNTs.

  The CNT wire 10 is obtained by obtaining an orientation of at least a half value width Δθ of an azimuth angle in an azimuth plot of small angle X-ray scattering (SAXS) indicating the orientation of a plurality of CNT assemblies 11, 11,. The half width Δθ of the azimuth angle is preferably 60 ° or less, and particularly preferably 50 ° or less, in order to further improve the heat dissipation characteristics of the above.

  Next, the arrangement structure and the density of the plurality of CNTs 11 a constituting the CNT assembly 11 will be described.

  FIG. 4 is a graph showing the q value-intensity relationship of the plurality of CNTs 11a, 11a,... Constituting the CNT assembly 11 by WAXS (wide-angle X-ray scattering).

WAXS is suitable for evaluating the structure or the like of a substance having a size of several nm or less. For example, by analyzing the information of the X-ray scattering image by the following method using WAXS, it is possible to evaluate the density of the CNTs 11a having an outer diameter of several nm or less. Any one CNT aggregate 11 Analysis of the relationship between the scattering vector q and strength for, as shown in FIG. ^4, observed around ^{q = 3.0nm -1 ~4.0nm -1 (10} ) of the peak The value of the lattice constant estimated from the q value at the peak top is measured. Based on the measured values of the lattice constant and the diameter of the CNT aggregate observed by Raman spectroscopy or TEM, it is understood that the CNTs 11a, 11a,... Form a hexagonal close-packed structure in plan view. It can be confirmed. Therefore, the diameter distribution of the plurality of CNT aggregates is narrow in the CNT wire 10, and the plurality of CNTs 11a, 11a,... Form a hexagonal close-packed structure by having a regular arrangement, ie, a high density. It can be said that it exists in high density.

  In this way, the plurality of CNT aggregates 11, 11... Have good orientation, and further, the plurality of CNTs 11a, 11a,. Because they are arranged at high density, the heat of the CNT wire 10 is easily dissipated while being smoothly transmitted along the longitudinal direction of the CNT aggregate 11. Therefore, the CNT wire rod 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 CNT aggregate 11 and the CNTs 11a, so it is superior to a metal core wire. Demonstrates heat dissipation characteristics.

The peak top q value at the (10) peak of the intensity by X-ray scattering indicating the density of the plurality of CNTs 11a, 11a, ... is 2.0 nm ^-1 from the viewpoint of further improving the heat dissipation characteristics by obtaining high density. above 5.0 nm ^-1 or less, and is preferably a half-value width [Delta] q (FWHM) is 0.1 nm ^-1 or 2.0 nm ^-1 or less.

  The orientation of the CNT aggregate 11 and the CNTs 11a, and the arrangement structure and density of the CNTs 11a are adjusted by appropriately selecting the spinning method such as dry spinning, wet spinning, liquid crystal spinning, and spinning conditions of the spinning method described later. be able to.

  Next, the insulating covering layer 21 covering the outer peripheral surface of the CNT wire 10 will be described.

As a material of the insulation coating layer 21, the material used for the insulation coating layer of the covered electric wire which used the metal as a core wire can be used, for example, a thermoplastic resin and a thermosetting resin can be mentioned. As a thermoplastic resin, for example, polytetrafluoroethylene (PTFE) (coefficient of thermal expansion: 80 to 120 × 10 ⁻⁶ / K), polyethylene (coefficient of thermal expansion: 100 to 200 × 10 ⁻⁶ / K), polypropylene (polycarbonate) Thermal expansion coefficient: 60 to 110 × 10 ⁻⁶ / K), polystyrene (thermal expansion coefficient: 60 to 80 × 10 ⁻⁶ / K), polycarbonate (thermal expansion coefficient: 50 to 60 × 10 ⁻⁶ / K), polyamide (The coefficient of thermal expansion: 60 to 100 × 10 ⁻⁶ / K), polyvinyl chloride (the coefficient of thermal expansion: 50 to 170 × 10 ⁻⁶ / K), the polyurethane (the coefficient of thermal expansion: 100 to 200 × 10 ⁻⁶ / K ), Polymethyl methacrylate (coefficient of thermal expansion: 40 to 70 × 10 ⁻⁶ / K), acrylonitrile butadiene styrene resin (coefficient of thermal expansion: 60 to 130 × 10 ⁻⁶ / K), acrylic resin (: 50 to 50) 60 × 10 ⁻⁶ / K) and the like. As the thermosetting resin, such as polyimide ^{(5~17 × 10 -6 / K)} , can be exemplified phenol resin (10~60 × ¹⁰ -6 / K) and the like. These may be used alone or in combination of two or more.

  The insulating covering layer 21 preferably contains other CNTs different from the CNTs of the CNT wire 10 as a filler. The other CNTs refer to CNTs different from the CNTs constituting the CNT wire 10. The properties of the other CNTs may be the same as or different from the CNTs constituting the CNT wire. . The content of CNT contained in the insulating covering layer 21 is, for example, 0.01 to 1% by mass. When the insulating covering layer 21 contains CNTs, the thermal conductivity of the insulating covering layer 21 is higher than that in the case where the insulating covering layer 21 does not contain CNT as a filler, and the CNT wire becomes hot. Responsiveness of thermal expansion of the insulating covering layer at the time can be quickened, and the occurrence of peeling can be further suppressed.

  The insulating covering layer 21 may be a single layer as shown in FIG. 1, or alternatively, may be two or more layers. For example, the insulating covering layer may have a first insulating covering layer formed on the outer circumference of the CNT wire 10 and a second insulating covering layer formed on the outer circumference of the first insulating covering layer. In this case, the content of the other carbon nanotubes contained in the second insulating covering layer may be smaller than the content of the other carbon nanotubes contained in the first insulating covering layer. In addition, one or more layers of a thermosetting resin may be further provided on the insulating covering layer 21 as necessary. The thermosetting resin may contain a filler having a fiber shape or a particle shape.

  In the CNT-coated electric wire 1, the ratio of the cross-sectional area in the radial direction of the insulating covering layer 21 to the cross-sectional area in the radial direction of the CNT wire 10 is preferably in the range of 0.01 or more and 1.5 or less. When the ratio of the cross-sectional area is in the range of 0.01 or more and 1.5 or less, the thickness of the insulating covering layer 21 can be reduced, so that the insulation reliability can be sufficiently secured and the heat of the CNT wire 10 can be reduced. Thus, excellent heat dissipation characteristics can be obtained. In addition, since the CNT-coated wire 1 is lighter in weight than the core wire made of copper, aluminum or the like, even if a thick insulating covering layer is formed, the CNT-coated wire 1 is a metal-coated wire such as copper or aluminum Weight reduction can be realized in comparison.

  In addition, in the case where the shape maintenance in the longitudinal direction may be difficult with the CNT wire 10 alone, the insulating covering layer 21 is coated on the outer peripheral surface of the CNT wire 10 at the ratio of the cross sectional area. Can maintain its shape in the longitudinal direction. Therefore, the handling property at the time of wiring of the CNT coated wire 1 can be enhanced.

  Furthermore, since fine irregularities are formed on the outer peripheral surface of the CNT wire 10, the adhesion between the CNT wire 10 and the insulating coating layer 21 is improved as compared to a coated wire using a core wire of aluminum or copper. Can be improved, and peeling between the CNT wire 10 and the insulating covering layer 21 can be suppressed.

  The ratio of the cross-sectional area is not particularly limited, but from the viewpoint of further improving the insulation reliability, the lower limit thereof is preferably 0.1, and particularly preferably 0.2. On the other hand, the upper limit value of the ratio of the cross-sectional area is preferably 1.0 from the viewpoint of further improving the weight saving of the CNT-coated electric wire 1 and the heat dissipation characteristics to the heat of the CNT wire 10.

If the ratio of the cross-sectional area is in a range of 0.01 to 1.5, the cross-sectional area in the radial direction of the CNT wire 10 is, for example, preferably 0.001 mm ² or more 20 mm ² or less, 0.001 mm ² or more 10mm ^Two or less are further preferable, and 0.01 mm ² or more and 5 mm ² or less are particularly preferable. Further, the cross-sectional area in the radial direction of the insulating cover layer 21 is, for example, preferably 0.001 mm ² or more 30 mm ² or less, particularly preferably 0.01 mm ² or more 5 mm ² or less.
The cross-sectional area can be measured, for example, from an image of a scanning electron microscope (SEM) observation. Specifically, after obtaining an SEM image (100 times to 10,000 times) of a radial cross section of the CNT-coated wire 1, the CNT wire 10 was penetrated from the area of the portion surrounded by the outer periphery of the CNT wire 10 The sum of the area obtained by subtracting the area of the material of the insulating covering layer 21, the area of the portion of the insulating covering layer 21 covering the outer periphery of the CNT wire 10 and the area of the material of the insulating covering layer 21 intruding inside the CNT wire 10 is The cross-sectional area in the radial direction of the CNT wire 10 and the cross-sectional area in the radial direction of the insulating coating layer 21 are respectively used. The radial cross-sectional area of the insulating covering layer 21 also includes the resin that has entered between the CNT wires 10.

The coefficient of thermal expansion (also referred to as the coefficient of thermal expansion) of the CNT wire 10 is smaller than the coefficient of thermal expansion of aluminum or copper used as a conventional core wire. For example, the coefficient of thermal expansion of aluminum at room temperature (293 K) is 23.1 × 10 ^-6 / K, the coefficient of thermal expansion at 227 ° C. (500 K) is 26.4 × 10 ^-6 / K, and the coefficient of thermal expansion of copper at room temperature The coefficient of expansion is 16.5 × 10 ⁻⁶ / K, and the coefficient of thermal expansion at 227 ° C. is 18.3 × 10 ⁻⁶ / K. On the other hand, the coefficient of thermal expansion of the CNT wire 10 at room temperature is, for example, −1.0 × 10 ⁻⁶ / K, and the coefficient of thermal expansion at 227 ° C. is −0.9 / K. Further, the thermal expansion coefficient of the CNT wire 10 depends on the number of twists (T / m: number of revolutions per meter) of the CNT wire 10. In particular, the absolute value of the linear expansion coefficient in the longitudinal direction of the CNT wire 10 is the number of twists The smaller is the smaller. Therefore, in the CNT-coated electric wire 1, the thermal expansion coefficient of the insulating covering layer 21 is not larger than the thermal expansion coefficient of the CNT wire 10 as compared with the coated electric wire using aluminum or copper as the core wire. In consideration of the number of twists of the wire 10, a material having a thermal expansion coefficient which is a value within an appropriate range may be used as the material of the insulating covering layer 21.

  The twist number in the case of using the CNT wire 10 as a stranded wire is not particularly limited, but is preferably 20 T / m or more and 2000 T / m or less, and from the viewpoint of suppressing peeling between the CNT wire 10 and the insulating covering layer 21 It is more preferable that it is 20 T / m or more and 1500 T / m or less. The upper limit value of the number of twists is more preferably 1000 T / m, and still more preferably 800 T / m, from the viewpoint of preventing the line sagging due to twisting back in the coating step. Further, the lower limit value of the twist number is more preferably 50 T / m, and further preferably 100 T / m in terms of obtaining sufficient wire strength. When the number of twists is less than 20 T / m, the bending resistance and the handling property tend to be reduced. On the other hand, when the twist number exceeds 1500 T / m, the CNT wire 10 becomes hard, and the stress generated at the interface between the CNT wire 10 and the insulating coating layer 21 at high temperature may increase to cause peeling. The peeling between the CNT wire 10 and the insulation coating layer 21 can be suppressed as the twist number is 20 T / m or more and 1500 T / m or less.

In the CNT-coated electric wire 1, the thermal expansion coefficient of the CNT wire 10 is 0 / K or less, and the thermal expansion coefficient of the insulating covering layer 21 is 5 × 10 ⁻⁶ / K or more. When the thermal expansion coefficient of the CNT wire 10 is 0 / K or less and the thermal expansion coefficient of the insulating covering layer 21 is 5 × 10 ⁻⁶ / K or more, an overcurrent flows in the CNT wire 10, and the CNT wire 10 Even when the temperature is high or when the CNT-coated wire 1 is exposed to a high temperature environment, peeling at the interface between the CNT wire 10 and the insulating coating layer 21 can be suppressed. The thermal expansion coefficient of the CNT wire 10 is 0 / K or less from the viewpoint of improving the bending resistance, and the thermal expansion coefficient of the insulating covering layer 21 is 25 × 10 ⁻⁶ / K or more. Is preferred.

The coefficient of thermal expansion of the CNT wire 10 is 0 / K or less, preferably −10 × 10 ⁻⁶ / K or more and 0 / K or less.

The upper limit value of the thermal expansion coefficient of the insulating covering layer 21 is not particularly limited, but the insulating covering layer 21 follows the CNT wire 10 even if the CNT-coated electric wire 1 is repeatedly bent at high temperature. 400 × 10 ⁻⁶ / K is preferable from the viewpoint of suppressing the peeling of the covering layer 21, and preventing the insulating covering layer 21 from peeling from the CNT wire 10 even if the CNT-coated wire 1 is bent for a long period of time. To 200 × 10 ⁻⁶ / K is more preferable. When the thermal expansion coefficient of the insulating covering layer 21 exceeds 400 × 10 ⁻⁶ / K, the increase and decrease of the volume due to the temperature change tends to be large. Therefore, when wiring the CNT-coated electric wire 1 according to the groove, the groove may be deviated from the groove. In addition, when the CNT-coated wire 1 is used for a coil, the coil may be loosened. On the other hand, the lower limit value of the thermal expansion coefficient of the insulating covering layer 21 is preferably 5 × 10 ⁻⁶ / K because the insulating covering layer 21 needs to expand by more than the contraction of the CNT wire 10 from the viewpoint of peeling suppression. Or 25 × 10 ⁻⁶ / K is more preferable from the viewpoint of improving the bending resistance. Therefore, the thermal expansion coefficient of the insulating covering layer 21 is preferably 5 × 10 ⁻⁶ / K or more and 400 × 10 ⁻⁶ / K or less, more preferably 25 × 10 ⁻⁶ / K or more and 200 × 10 ⁻⁶ / K or less It is.

  The thermal expansion coefficient of the CNT wire 10 and the thermal expansion coefficient of the insulating covering layer 21 are obtained, for example, by using a cutter to divide a CNT-coated electric wire of an appropriate length into a CNT wire and an insulating covering layer. For example, it can be measured by measuring the coefficient of expansion while raising and lowering the temperature from -100 ° C. to 500 ° C. at a rate of 5 ° C./min.

  It is preferable that the thickness in the direction (that is, the radial direction) orthogonal to the longitudinal direction of the insulating covering layer 21 be uniform in terms of improving the insulation properties and the wear resistance of the CNT-coated electric wire 1. Specifically, the uneven thickness ratio of the insulating coating layer 21 is 50% or more from the point of improving the insulating property and the abrasion resistance, and is preferably 70% or more from the point of improving the handling property in addition to these. . In the present specification, “a non-uniform thickness ratio” means α = (insulation covering layer 21) for every 10 cm at any 1.0 m on the center side in the longitudinal direction of the CNT-coated electric wire 1. The value of the minimum value of the thickness / the maximum value of the thickness of the insulating coating layer 21) × 100 is calculated, which means a value obtained by averaging the α values calculated in each cross section. Further, the thickness of the insulating covering layer 21 can be measured, for example, from a SEM image by circular approximation of the CNT wire 10. Here, the longitudinal center side refers to a region located at the center as viewed from the longitudinal direction of the line.

  The uneven thickness ratio of the insulating covering layer 21 is, for example, a tension applied in the longitudinal direction of the CNT wire 10 when passing through the die during the extrusion process when forming the insulating covering layer 21 on the outer peripheral surface of the CNT wire 10 by extrusion coating. Can be improved by adjusting the

[Method of manufacturing carbon nanotube coated wire]
Next, an example of a method of manufacturing the CNT-coated electric wire 1 according to the embodiment of the present invention will be described. The CNT-coated electric wire 1 can be manufactured by first manufacturing the CNTs 11 a, forming the CNT wire 10 from the obtained plurality of CNTs 11 a, and coating the outer circumferential surface of the CNT wire 10 with the insulating covering layer 21.

  The CNTs 11a can be manufactured by a method such as a floating catalyst method (Japanese Patent No. 5819888) or a substrate method (Japanese Patent No. 5590603). The wire of the CNT wire 10 is, for example, 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). No. 2), liquid crystal spinning (Japanese Patent Application Publication No. 2014-530964), etc.

  At this time, the orientation of the CNT aggregate 11 constituting the CNT wire 10, the orientation of the CNT 11a constituting the CNT aggregate 11, and the density of the CNT aggregate 11 or CNT 11a are, for example, dry spinning, wet spinning, liquid crystal spinning And the spinning conditions of the spinning method can be selected as appropriate.

  As a method of covering the insulating covering layer 21 on the outer peripheral surface of the CNT wire 10 obtained as described above, a method of covering an insulating covering layer on a core wire of aluminum or copper can be used. For example, a raw material of the insulating covering layer 21 The method of melt | dissolving the thermoplastic resin which is and extruding and covering the fuse | melted thermoplastic resin around the CNT wire 10, or the method of apply | coating the fuse | melted thermoplastic resin around the CNT wire 10 can be mentioned.

  The CNT-coated electric wire 1 according to an embodiment of the present invention can be used as a general electric wire such as a wire harness, and a cable may be produced from a general electric wire using the CNT-coated electric wire 1. Alternatively, the coil may be produced by winding the CNT-coated wire 1. In this case, the space factor is preferably 60% or more.

In another aspect of the present invention, the coated electric wire includes a conductor and an insulating covering layer covering the conductor, the thermal expansion coefficient of the conductor is 0 / K or less, and the thermal expansion coefficient of the insulating covering layer is 5 × 10 ^-6 / K or more. That is, the conductor may have a thermal expansion coefficient of 0 / K or less, and is not limited to carbon nanotubes. Examples of the material having a coefficient of thermal expansion of 0 / K or less include aramid fibers (coefficient of thermal expansion: -6 × 10 ^-6 / K) and carbon fibers (-1 × 10 ^-6 / K). Moreover, as a material of an insulation coating layer, what was mentioned above can be used. Since the thermal expansion coefficient of the conductor is 0 / K or less, and the thermal expansion coefficient of the insulating covering layer is 5 × 10 ⁻⁶ / K or more, the temperature of the conductor becomes high and the conductor shrinks. Even when the insulation covering layer expands following the contraction of the conductor, it is possible to suppress peeling of the insulation covering layer from the conductor, and excellent bending resistance can be realized.

  Next, examples of the present invention will be described, but the present invention is not limited to the following examples as long as the purpose of the present invention is not exceeded.

(About Examples 1-21, Comparative Examples 1-2)
First, a dry spinning method (Japanese Patent No. 5819888) for directly spinning CNTs produced by a floating catalyst method or a method for wet spinning (Japanese Patent No. 5135620, Japanese Patent No. 5131571, Japanese Patent No. 5288359) No. 2) obtained a strand (single wire) of a CNT wire having a cross-sectional area as shown in Table 1. Further, the number of CNT wires having a predetermined circle equivalent diameter was adjusted and appropriately twisted to obtain a stranded wire having a cross-sectional area as shown in Table 1.

Method of Coating Insulating Coating Layer on Outer Peripheral Surface of CNT Wire By extruding or baking any of the following resins, an insulating coating layer is formed, which is used in Examples and Comparative Examples of Table 1 below. A CNT coated wire was produced.

Polyurethane: TPU3000EA manufactured by Higashi Tok Paint Co., Ltd.
Polyimide: Unitica U-imide polypropylene: Nippon Polypropylene Corporation Novatec PP

(A) Measurement of Cross-Sectional Area of CNT Wire After a radial cross-section of the CNT wire is cut out with an ion milling apparatus (IM 4000 manufactured by Hitachi High-Technologies Corporation), a scanning electron microscope (SU 8020 manufactured by Hitachi High-Technologies Corporation), magnification: 100-10 The cross-sectional area of the CNT wire in the radial direction was measured from the SEM image obtained in (1,000, 000). The same measurement was repeated every 10 cm at an arbitrary 1.0 m on the center side in the longitudinal direction of the CNT-coated wire, and the average value was taken as the cross-sectional area of the CNT wire in the radial direction. In addition, as a cross-sectional area of a CNT wire, the resin which got in the inside of a CNT wire was not included in measurement.

(B) Measurement of Cross-Sectional Area of Insulating Coating Layer A radial cross-section of the CNT wire is cut out with an ion milling apparatus (IM 4000 manufactured by Hitachi High-Technologies Corporation) and then scanning electron microscope (SU 8020 manufactured by Hitachi High-Technologies Corporation, magnification: 100 to The radial cross-sectional area of the insulation coating layer was measured from the SEM image obtained by 10,000 times). The same measurement was repeated every 10 cm at any 1.0 m in the longitudinal direction of the CNT-coated electric wire 1, and the average value was taken as the radial cross-sectional area of the insulating covering layer. Therefore, as the cross-sectional area of the insulating covering layer, the resin which entered into the CNT wire was also included in the measurement.

(C) Measurement of Half Angle Width Δθ of Azimuth Angle by SAXS Small angle X-ray scattering measurement was carried out using a small angle X-ray scattering device (Aichi Synchocroton), and the half width Δθ of azimuth angle was determined from the obtained azimuth plot.

(D) Measurement of peak top q value and half width Δq by WAXS Wide-angle X-ray scattering measurement was performed using a wide-angle X-ray scattering apparatus (Aichi Synchrotron), and the q value-intensity graph obtained shows that the intensity (10 ) The q value of the peak top at the peak and the half width Δq were determined.

(E) Number of Twists of CNT Wire The CNT wire is a stranded wire by bundling a plurality of strands and fixing one end, and twisting the other end a predetermined number of times. The twist number is represented by a value (unit: T / m) obtained by dividing the number of twists (T) by the length of the line (m).

(F) Measurement of coefficient of thermal expansion A 20 mm CNT-coated wire sample was cut out every 10 cm in the longitudinal direction of a 1.0 m CNT-coated wire, and was separated into a CNT wire and an insulating coating layer using a cutter knife. About each, using a thermomechanical analyzer (TMA / SS 6100, manufactured by Hitachi High-Tech Science Co., Ltd.), the coefficient of expansion was measured at a measurement load of 9.8 mN in nitrogen gas, and the average value was determined. The temperature range was −100 ° C. to 500 ° C., and the temperature rising rate and the temperature lowering rate were 5 ° C./min.

  The results of the above measurements of the CNT-coated wire are shown in Table 1 below. In addition, the value of a thermal expansion coefficient is a value in room temperature (25 degreeC).

  The following evaluation was performed about the CNT coated electric wire produced as mentioned above.

(1) Flexural resistance A 90-degree bending was performed 1000 times with a load of 500 gf applied to a 100 cm CNT-coated electric wire by a method in accordance with IEC 60227-2. Thereafter, cross-sectional observation was performed every 10 cm in the axial direction, and it was confirmed whether or not there was peeling between the CNT wire and the insulating covering layer. Those with no peeling were regarded as good "〇", those with partial peeling but with acceptable level of product quality were generally regarded as good "△", those with complete peeling, and broken CNT wires as defects "x".

(2) Existence of exfoliation after repeated current load A current was applied for 5 minutes to a current density of 2000 A / cm ² to a 100 cm CNT-coated wire. Subsequently, it was left to stand at 0 ° C. for 5 minutes in the state where no current was applied. Similarly, a current was applied for 5 minutes so that the current density was 2000 A / cm ^2, and a cycle of standing at 0 ° C. for 5 minutes was carried out for a total of 100 cycles. In addition, about the CNT coated electric wire of Example 9, 50 cycles were implemented and the following evaluation was performed.
Subsequently, cross-sectional observation was performed every 10 cm in the axial direction, and it was confirmed whether or not there was peeling between the CNT wire and the insulating coating layer. Those with no peeling were regarded as good "〇", those with partial peeling but with acceptable level of product quality were generally good "「 ", and those with broken CNT wire were regarded as defective" x ".

(3) Handling Property A five-layered coil of 10 mm in width was obtained by manually winding a CNT-coated electric wire around a core of 10 mm in diameter at a constant speed. From the cross-sectional observation of the obtained coil, the space factor (space factor (%) = (sum of cross-sectional area of CNT-coated wire) / (coil cross-sectional area) × 100) was determined. A coil was produced 5 times for each CNT-coated wire, and the space factor was an average value of 5 times. A space factor of 70% or more is “◎” as handling is very good, a space factor of 50% or more and less than 70% is a handleability of good “O”, a space factor of less than 50% is handling Not good as "x".

  The results of the above evaluation are shown in Table 1 below.

As shown in Table 1 above, in Examples 1 to 21, the thermal expansion coefficient of the CNT wire is 0 / K or less, and the thermal expansion coefficient of the insulating coating layer is 5 × 10 ⁻⁶ / K or more, The flex resistance, the presence or absence of peeling after repeated current load, and the handling property were all generally good or more.

Furthermore, in Examples 1 to 21, the half value width Δθ of the azimuth angle was 60 ° or less. Therefore, in the CNT wire of Examples 1 to 21, the CNT aggregate had excellent orientation. Further, in Examples 1 to 21, q values of the peak top in (10) peak intensity are both at 2.0 nm ^-1 or 5.0 nm ^-1 or less, the half width Δq are all 0.1nm ^-1 or more and 2.0 nm- ¹ or less. Therefore, in the CNT wires of Examples 1 to 21, the CNTs were present at a high density.

  On the other hand, in Comparative Example 1, the conductor was an aluminum wire, the thermal expansion coefficient of the conductor was more than 0 / K, and the bending resistance was inferior. In Comparative Example 2, the conductor was a copper wire, the coefficient of thermal expansion of the conductor was more than 0 / K, and the bending resistance was inferior.

Reference Signs List 1 carbon nanotube-coated electric wire 10 carbon nanotube wire rod 11 carbon nanotube aggregate 11a carbon nanotube 21 insulating coating layer

Claims (12)

A carbon nanotube wire formed by twisting together a plurality of carbon nanotube assemblies composed of a plurality of carbon nanotubes, and an insulating covering layer covering the carbon nanotube wire;
The carbon nanotube coated electric wire, wherein the thermal expansion coefficient of the carbon nanotube wire is 0 / K or less, and the thermal expansion coefficient of the insulating covering layer is 5 × 10 ⁻⁶ / K or more. The carbon nanotube coated electric wire according to claim 1, wherein the thermal expansion coefficient of the carbon nanotube wire is 0 / K or less, and the thermal expansion coefficient of the insulating covering layer is 25 × 10 ^-6 / K or more.   The carbon nanotube covering electric wire according to claim 1 or 2 whose twist number of said carbon nanotube wire rod is 20T / m or more and 1500T / m or less. The carbon nanotube coated electric wire according to any one of claims 1 to 3, wherein a thermal expansion coefficient of the insulating covering layer is 400 × 10 ^-6 / K or less.   The carbon nanotube coated electric wire according to any one of claims 1 to 4, wherein a half value width Δθ of an azimuth angle in an azimuth plot by small angle X-ray scattering showing orientation of a plurality of the carbon nanotube aggregate is 60 ° or less. . Q value of the peak top in (10) the peak of scattering intensity by X-ray scattering shows a density of a plurality of the carbon nanotubes is at 2.0 nm ^-1 or 5.0 nm ^-1 or less, and the half-value width Δq is 0.1nm ^-1 2.0nm is less than ^-1, the carbon nanotube covered electric wire according to any one of claims 1 to 5.   The carbon according to any one of claims 1 to 6, wherein the ratio of the cross-sectional area in the radial direction of the insulating covering layer to the cross-sectional area in the radial direction of the carbon nanotube wire is 0.01 or more and 1.5 or less. Nanotube coated wire. The carbon nanotube coated electric wire according to any one of claims 1 to 7, wherein a cross sectional area in a radial direction of the carbon nanotube wire rod is 0.001 mm ² or more and 20 mm ² or less.   The carbon nanotube coated electric wire according to any one of claims 1 to 8, wherein the insulating covering layer contains another carbon nanotube. The insulating covering layer has a first insulating covering layer formed on the outer periphery of the carbon nanotube wire, and a second insulating covering layer formed on the outer periphery of the first insulating cover layer,
The carbon nanotube coated electric wire according to claim 9, wherein the content of the other carbon nanotubes contained in the second insulating covering layer is smaller than the content of the other carbon nanotubes contained in the first insulating covering layer.   A coil formed by winding the carbon nanotube coated electric wire according to any one of claims 1 to 10. A conductor and an insulating covering layer covering the conductor;
The covered electric wire whose coefficient of thermal expansion of the said conductor is 0 / K or less and whose coefficient of thermal expansion of the said insulation coating layer is 5 * 10 < ^-6 > / K or more.