Conductors and conductive members using the same

Abstract

The present invention provides a conductor that eliminates the foreign body sensation caused by heater wires and improves tactile sensation, as well as a conductive component using the same. [Solution] The conductor comprises a carbon nanotube base fabric 20 and a synthetic leather layer 10 disposed on the carbon nanotube base fabric 20, the carbon nanotube base fabric 20 comprising a base fabric 21 made of synthetic fibers and carbon nanotubes 25 attached to the base fabric 21. The conductive member 1 comprises a conductor, resin substrates 30, 40 on which the conductor is placed, and a conductive circuit 50 connected to the conductor.

Description

Technical Field

[0001] The present invention relates to a conductor and a conductive member using the same.

Background Art

[0002] Inside vehicles such as automobiles, gripping members or interior members such as operation handles, knobs, and grips equipped with a heating function are used. Patent Document 1 discloses a seat with a heating device in which a planar heater is incorporated. The heater has a configuration in which heater wires are sewn to a planar base fabric, and is disposed between a pad inside the heater and a cover covering the surface thereof.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when heater wires are disposed in a cushioned portion like the heater of Patent Document 1, there is a problem that the foreign body sensation due to the floating and unevenness of the heater wires is prominent and the touch feeling is not good.

[0005] The present invention has been made in view of such problems of the prior art. An object of the present invention is to provide a conductor that eliminates the foreign body sensation caused by heater wires and improves the touch feeling, and a conductive member using the same.

Means for Solving the Problems

[0006] The conductor according to the present embodiment includes a carbon nanotube base fabric and a combined skin layer disposed on the carbon nanotube base fabric, and the carbon nanotube base fabric includes a base fabric made of synthetic fiber and carbon nanotubes attached to the base fabric.

[0007] The conductive member according to this embodiment comprises the conductor, a resin substrate on which the conductor is arranged, and a conductive circuit connected to the conductor. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a conductor that eliminates the feeling of foreign matter caused by the heater wire and improves tactile sensation, as well as a conductive member using the same. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing an example of a conductive member according to this embodiment. [Figure 2] This is a schematic diagram showing an example of a conventional conductive material. [Figure 3] This is a perspective view showing an example of a conductive member according to this embodiment. [Figure 4] This is a schematic diagram showing a method for fabricating carbon nanotube substrates. [Figure 5A] This is a schematic diagram showing a method for manufacturing a conductor and a conductive member according to this embodiment. [Figure 5B] This is a schematic diagram showing a method for manufacturing a conductor and a conductive member according to this embodiment. [Figure 5C] This is a schematic diagram showing a method for manufacturing a conductor and a conductive member according to this embodiment. [Figure 6] This is a SEM image of synthetic fibers. [Figure 7] This is a SEM image showing the cross-sectional structure of a synthetic fiber. [Figure 8] This is an optical microscope image of synthetic fibers. [Figure 9] This is an optical microscope image of fibers immersed in a carbon nanotube coating, as used in Comparative Example 1. [Figure 10] This is a schematic diagram of an experiment to measure surface resistivity. [Modes for carrying out the invention]

[0010] Hereinafter, the conductor according to the present embodiment and the conductive member using the same will be described in detail with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for convenience of explanation and may differ from the actual ratios.

[0011] [Conductor and Conductive Member] The conductor includes a carbon nanotube base fabric (hereinafter referred to as CNT base fabric) 20 and a composite skin layer 10 disposed on the CNT base fabric 20. And the conductive member 1 includes a conductor, resin base materials 30 and 40 in which the conductor is disposed, and a conductive circuit 50 connected to the conductor.

[0012] The resin base materials 30 and 40 are disposed inside the conductive member 1. Examples of the resin base materials 30 and 40 include resin members having rubber elasticity (polyurethane (foamed, non-foamed), olefin-based elastomers, etc.), hard resins (PP (polypropylene), ABS (acrylonitrile-butadiene-styrene resin), etc.), lightweight foams (bead-foamed styrene (foamed styrene), PEF (foamed polyethylene)), etc. In particular, those having heat insulation properties (foamed polyurethane, foamed styrene, etc.) are preferable because they can suppress the amount of heat transferred to the vehicle body and transfer more heat to the surface side. Also, as shown in FIG. 1, the resin base materials 30 and 40 may be composed of a plurality of layers combining these resins.

[0013] The CNT base fabric 20 constituting the conductor is disposed on the resin base materials 30 and 40. The CNT base fabric 20 includes a base fabric 21 made of synthetic fiber and carbon nanotubes (hereinafter referred to as CNT) 25 attached to the base fabric 21. And a conductive circuit 50 is connected to the CNT base fabric 20 constituting the conductor, and it functions as a heating element by being energized through the conductive circuit 50. Note that the thickness of the CNT base fabric 20 is preferably 0.3 mm to 1.2 mm from the viewpoint of conductivity, and more preferably 0.5 mm to 1.0 mm.

[0014] FIG. 2 shows an example of a conventional conductive member 100. The conventional conductive member 100 includes resin substrates 130 and 140, a heater portion 125 disposed on the resin substrates 130 and 140, a base fabric 120 disposed on the heater portion 125, and a composite leather layer 110 disposed on the base fabric 120. The heater portion 125 is configured as a heater wire using a nichrome wire heater or the like, and is sewn to the base fabric 120, and is disposed sandwiched between the resin substrates 130 and 140 and the composite leather layer 110. Therefore, there is a problem that the foreign body sensation due to the floating and unevenness of the heater portion 125 is prominent and the touch feeling is not good. The conductive member 1 according to the present embodiment does not include the configuration of the heater portion 125 sewn to the base fabric, and since the CNT base fabric 20 functions as a heating element instead of the heater portion 125, it is possible to provide a conductive member that eliminates the foreign body sensation caused by the heater wire and improves the touch feeling. Further, although a heating device such as a nichrome wire heater is known to have a large power consumption, since the conductive member 1 according to the present embodiment does not include a nichrome wire heater or the like, the power consumption can be suppressed.

[0015] The composite leather layer 10 constituting the conductor is disposed on the CNT base fabric 20 and is located on the surface side of the conductive member 1. The composite leather layer 10 is preferably one having good thermal conductivity, and for example, synthetic leather made of polyurethane resin or polyvinyl chloride resin can be selected. If necessary, the heat transfer property may be enhanced and the heating property may be improved by inserting a metal foil such as copper or aluminum alloy or adding the above metal in a flaky form. Further, as shown in FIG. 3, a barrier coat layer 11 for protecting the composite leather layer 10 may be provided on the surface of the composite leather layer 10. The thickness of the composite leather layer 10 is preferably 0.8 mm to 2.0 mm, and more preferably 1.0 mm to 1.5 mm, from the viewpoints of thermal conductivity and touch feeling.

[0016] The synthetic fibers used in the CNT base fabric 20 are not particularly limited, but it is preferable that they be at least one selected from the group consisting of polyester fibers, polyamide (nylon) fibers, polyolefin fibers, acrylic fibers, polyurethane fibers, and cellulose fibers. Of these, polyethylene terephthalate fibers (hereinafter referred to as PET fibers), which are a type of polyester fiber, allow carbon nanotube dispersion liquid (hereinafter referred to as CNT dispersion liquid) 24 to penetrate easily, and CNTs 25 adhere strongly to them, as described later. For this reason, polyester fibers are more preferable as synthetic fibers, and PET fibers are even more preferable.

[0017] The synthetic fiber preferably has grooves on its surface and an irregular cross-sectional shape. An example of a synthetic fiber is Calculo®, a PET fiber manufactured by Teijin Frontier Ltd., as shown in Figures 6-8. Calculo has an irregular cross-sectional shape with deep grooves on its fiber surface, and also has a random single-fiber cross-sectional shape in the fiber axis direction. Because it has large interfiber voids, it has superior water absorption and drying properties compared to conventional round-section PET fibers, and can provide sweat absorption and quick drying properties. By utilizing the characteristic cross-sectional shape of such PET fibers, the adhesion at the interface is improved through the anchoring effect and contact area expansion effect, making it easier for the PET fiber and CNT to intertwine and allowing the CNT to adhere firmly to the PET fiber.

[0018] The CNT base fabric 20 comprises CNTs 25 attached to the base fabric 21. As described later, the CNTs 25 can be attached to the base fabric 21 by immersing the base fabric 21 in the CNT dispersion 24. Alternatively, the CNTs 25 may be contained in a conductive film formed on the surface of the base fabric 21.

[0019] The carbon nanotubes (CNTs) are preferably at least one selected from the group consisting of single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), and multi-walled carbon nanotubes (MWCNTs), with SWCNTs being more preferable from the viewpoint of conductivity. Furthermore, the central diameter of the SWCNTs is preferably 0.5 nm to 5 nm, and more preferably 1 nm to 3 nm. In addition, the length of the SWCNTs is preferably 1 μm to several tens of μm.

[0020] Figure 3 shows an example of a conductive member 1. It consists of a CNT base fabric 20, a synthetic leather layer 10 placed on the CNT base fabric 20, and a conductive material, with a barrier coat layer 11 placed on top of the conductive material. A conductive circuit 50 is connected to the CNT base fabric 20 that constitutes the conductive material. By connecting wiring 51 to the conductive circuit 50 and applying current, heat is generated in the CNT base fabric 20 due to electrical resistance, and the conductive material can be used as a planar heating element.

[0021] From the viewpoint of conductivity, it is preferable to use conductive ink in the conductive circuit 50. Known conductive inks can be used. Conductive ink is composed of a conductive filler, a binder, and an organic solvent, and a conductor is formed by firing after application, enabling electrical conductivity. Examples of conductive fillers contained in conductive ink include carbon components and metal components. As for the carbon component, it is preferable to contain at least one selected from the group consisting of carbon black, graphite, graphene, carbon nanotubes, and carbon fibers. As for the metal component, it is preferable to contain at least one selected from the group consisting of gold, silver, copper, platinum, palladium, rhodium, ruthenium, iridium, osmium, tungsten, nickel, tantalum, bismuth, lead, indium, tin, zinc, and titanium. The thickness of the conductive circuit 50 is preferably 10 μm to 50 μm, and more preferably 20 μm to 40 μm, from the viewpoint of conductivity.

[0022] In the conductive member 1, when current is passed through the conductive circuit 50 to heat the CNT base fabric 20, the center point temperature measured using thermography from the barrier coat layer 11 side is preferably 30°C or higher and 60°C or lower. Furthermore, the time to reach 42°C is preferably within 5 minutes (300 seconds), and more preferably within 1 minute (60 seconds). The time to reach 42°C can be measured as the time it takes for the center point temperature to reach 42°C after applying voltage from room temperature (20°C).

[0023] Such conductive member 1 can be used in heaters incorporated into gripping members such as steering handles, knobs, and grips, armrests, and other interior components inside vehicles such as automobiles, and can also be used as a sensor member or an electrostatic discharge member.

[0024] As described above, the conductor according to this embodiment comprises a CNT base fabric 20 and a synthetic leather layer 10 disposed on the CNT base fabric 20. The CNT base fabric 20 comprises a base fabric 21 made of synthetic fibers and CNTs 25 attached to the base fabric 21. The conductive member 1 comprises a conductor, resin substrates 30 and 40 on which the conductor is placed, and a conductive circuit 50 connected to the conductor. The conductor and conductive member 1 do not include a heater wire sewn into the base fabric, and the CNT base fabric 20 functions as a heating element instead of a heater wire. Therefore, the conductor according to this embodiment can provide a conductor with improved tactile feel by eliminating the foreign body sensation caused by a heater wire. Furthermore, the conductive member 1 according to this embodiment can provide a conductive member with improved tactile feel by eliminating the foreign body sensation caused by a heater wire. Since the conductive member 1 according to this embodiment does not include a nichrome wire heater or the like, power consumption can be reduced.

[0025] [Method for manufacturing conductors and conductive members] Figure 4 shows the process for manufacturing the CNT base fabric 20. Figures 5A to 5C show the manufacturing method for the conductor and conductive member 1 using the CNT base fabric 20.

[0026] As a method for manufacturing the conductor and conductive member 1, first, as shown in Figure 4, a step is performed in which a base fabric 21 is immersed in a CNT dispersion 24, which is obtained by dispersing CNTs 25 in an aprotic solvent 23.

[0027] An aprotic solvent 23 is used as the dispersion solvent for the CNT dispersion 24. The aprotic solvent 23 is preferably at least one selected from the group consisting of DMF (N,N-dimethylformamide), DMSO (dimethyl sulfoxide), DMA (N-methylacetamide), and acetonitrile. Both the aprotic solvent 23 and CNT 25 are highly polar, and even without the addition of dispersants such as surfactants, the CNT 25 is uniformly dispersed in the aprotic solvent 23, yielding a good CNT dispersion 24 composed solely of CNT 25. When the synthetic fiber is a PET fiber, DMF is more preferable from the viewpoint of its ease of penetration into the interior of the PET fiber.

[0028] DMF is an amide formed by the condensation of formic acid and dimethylamine. The amide bond is a relatively stable bond and does not react easily with nucleophiles or electrophiles, so it is used as an organic solvent. Furthermore, DMF has a carbonyl group and is polarized and highly polar, so it is called an aprotic polar solvent. On the other hand, CNT25 is highly polar and has high stereoregularity, exhibiting properties that make it easy for molecules to attract and aggregate. Since DMF molecules contain amide bonds, and amide bonds and carbon are easily adsorbed, a CNT dispersion 24 in which CNT25 is uniformly dispersed in the DMF solvent can be obtained without the addition of dispersants such as surfactants.

[0029] PET fibers have a microphase separation structure in which crystalline and amorphous regions are separated. When an aprotic solvent 23 (DMF) acts on them, the DMF penetrates the amorphous region of the PET fiber, causing softening and swelling. This effect is more pronounced at higher temperatures as molecular movement becomes more active, allowing for deeper penetration. Since the glass transition temperature of PET fibers is 70°C, at temperatures above 70°C, the molecular movement in the crystalline region also becomes more active, allowing DMF to penetrate into the interior of the crystalline region, disrupting the crystalline structure. This can lead to unstable dispersion of crystal grains during recrystallization, potentially causing a decrease in physical properties. Therefore, the action of DMF must be performed at temperatures below 70°C to maintain the physical properties of the PET fiber.

[0030] Furthermore, the interface between the PET fibers and CNTs becomes entangled in the surface layer due to the softening and swelling action of the PET fibers. When the DMF is removed, the PET fibers return to their original state, improving the adhesion strength of the interface, thus allowing the CNTs to adhere firmly to the PET fibers on their own.

[0031] As mentioned above, a binder is not required in the CNT dispersion 24. In conventional methods, when synthetic fibers are immersed in a CNT dispersion containing a binder, the conductivity may decrease because the binder's components are nonconductive. In the process of producing the CNT base fabric 20, by not including a binder in the CNT dispersion 24, it is possible to produce a CNT base fabric 20 with improved conductivity compared to conventional methods.

[0032] The method for preparing the CNT dispersion 24, in which CNTs 25 are dispersed in an aprotic solvent 23, is not particularly limited. To improve the dispersibility of CNTs 25 in the aprotic solvent 23, they can be pulverized using a grinder such as a ball mill, rotor speed mill, cutting mill, homogenizer, vibratory mill, or attritor, and then dispersed in the aprotic solvent 23. Since both the aprotic solvent 23 and CNTs 25 are highly polar, CNTs 25 can be uniformly dispersed in the aprotic solvent 23 without the addition of dispersants such as surfactants. Furthermore, the wettability of CNTs 25 in the aprotic solvent 23 is improved, and the CNTs 25 can be finely broken down.

[0033] The method for immersing the base fabric 21 in the CNT dispersion 24 is not particularly limited, and general impregnation methods such as those involving micro-vibration can be used. However, applying micro-vibration may cause a temperature increase in the CNT dispersion 24, making it easier for the aprotic solvent 23 to penetrate into the base fabric 21, increasing its attack on the base fabric 21, which could lead to dissolution of the base fabric 21, changes in its crystal structure, and a decrease in its physical properties.

[0034] Therefore, as a method for immersing the base fabric 21 in the CNT dispersion 24, it is preferable to use a ball mill 60, as shown in Figure 4. By using a ball mill 60, a uniform conductive film containing CNTs 25 can be formed on the base fabric 21 while maintaining the dispersibility of CNTs 25 in the aprotic solvent 23. Specifically, the base fabric 21 and the CNT dispersion 24 are placed in the ball mill 60, and the CNT dispersion 24 is dispersed on the base fabric 21 while stirring. A certain amount of balls 61, which are the dispersion medium, are placed in the cylindrical container of the ball mill 60. When the ball mill 60 is rotated around its horizontal axis, the balls 61 are lifted to a certain height along the inner wall as the cylindrical container rotates, and circulate in a certain direction within the cylindrical container by sliding along the inner wall or rolling down. A uniform conductive film can be formed on the base fabric 21 during the circulating movement of the balls 61. This method using the ball mill 60 results in almost no temperature rise, suppresses the penetration of the aprotic solvent 23 into the base fabric 21, and allows for the deposition of a conductive film containing CNTs 25 onto the base fabric 21 while minimizing the deterioration of the base fabric 21's physical properties.

[0035] The concentration of CNTs 25 in the CNT dispersion 24 is preferably 0.01 to 0.5% by mass, more preferably 0.05 to 0.2% by mass, and even more preferably 0.08 to 0.12% by mass, based on 100% by mass of the CNT dispersion 24. When the concentration of CNTs 25 is within the above range, it is easy to form a uniform conductive film containing CNTs 25 on the base fabric 21, and the CNTs can be firmly attached to the base fabric 21.

[0036] The synthetic fiber or base fabric 21 may have a pretreatment step of being immersed in polydopamine (hereinafter referred to as PDA) before being immersed in the CNT dispersion. PDA is a catechol-based polymer that mimics the byssal threads of the mussel (a type of bivalve), and has catechol groups, amino groups, and benzene rings, and can bind to various materials. It can change the surface properties of PET fibers, etc., and improve adhesion with the conductive film containing CNTs 25.

[0037] Next, the base fabric 21, after being immersed in the CNT dispersion 24, is dried to remove the aprotic solvent 23 and produce the CNT base fabric 20. As described above, when the base fabric 21 exceeds the glass transition temperature, the movement of molecules in the crystalline portion becomes active, the solvent penetrates into the crystal interior, the crystal structure collapses, and the dispersion of crystal grains becomes unstable during recrystallization, potentially causing a decrease in physical properties. Therefore, it is preferable that the temperature at which the aprotic solvent 23 is removed is below the glass transition temperature of the base fabric 21.

[0038] From the viewpoint of adhesion of the conductive film to the base fabric 21, it is preferable to remove the aprotic solvent 23 using a vacuum drying method. For example, if DMF is used as the aprotic solvent 23 and PET fiber is used as the synthetic fiber, since the boiling point of DMF is 153°C, drying conditions of 150°C or higher are required to remove DMF from the PET fiber. However, if heated above the glass transition temperature of PET fiber, 70°C, DMF will penetrate the crystalline structure of the PET fiber, degrading the physical properties of the PET fiber. Therefore, it is preferable to use a vacuum drying method and remove the solvent at a temperature of 70°C or lower. When drying, the PET fiber swollen by DMF shrinks back to its original state, further strengthening the adhesion at the interface between the PET fiber and the CNT. By the above method, a CNT base fabric 20 can be obtained.

[0039] Next, the synthetic leather layer 10 and the CNT base fabric 20 are bonded together. Figures 5A to 5C show an example of the manufacturing method for the conductor and conductive member 1 in Figure 3.

[0040] As shown in Figure 5A, first the first jig 71 is preheated. The first jig 71 has a cavity for pouring resin, and the bottom surface of the cavity may be textured. Then, a release agent 81 is applied to the first jig 71, followed by a barrier coat 82 to form a barrier coat layer 11.

[0041] Next, as shown in Figure 5B, a second jig 72, which is slightly larger than the first jig 71, is installed. The second jig 72 has a structure that surrounds the outside of the first jig 71. Preferably, the outer frame portion of the second jig 72 is thicker than the outer frame portion of the first jig 71. Then, the synthetic leather layer forming resin 83 is injected into the cavity formed after the second jig 72 is installed, and the synthetic leather layer 10 is formed by spreading it evenly with a tool 73. The tool 73 can be any tool commonly used for coating, such as a brush, spatula, or roller brush.

[0042] As mentioned above, the synthetic leather layer-forming resin 83 can be a resin used in synthetic leather, such as polyurethane resin or polyvinyl chloride resin. Therefore, the method for forming the synthetic leather layer 10 may be the same as the method for producing synthetic leather. When the synthetic leather layer-forming resin 83 is polyurethane resin, a reaction mixture of polyol, which is the main component, and isocyanate, which is the curing agent, can be injected and cured to form the synthetic leather layer. When the synthetic leather layer-forming resin 83 is polyvinyl chloride resin, a coating process such as applying a polyvinyl chloride resin solution and heat-drying it may be used. The method for forming the synthetic leather layer 10 is not limited to the molding method described above, and any known molding method may be used.

[0043] Furthermore, as shown in Figure 5C, the CNT base fabric 20 prepared as described above is placed on the synthetic leather layer 10, and a weight 74 is placed on top of it to heat and dry it, thereby bonding the CNT base fabric 20 to the synthetic leather layer 10 in close contact. In this way, a conductive material can be produced. Note that the method for bonding the synthetic leather layer 10 and the CNT base fabric 20 is not limited to the method described above, and known methods such as using an adhesive can be used.

[0044] Next, a conductive ink is printed onto the CNT base fabric 20 that constitutes the conductor, and the conductive circuit 50 is connected. When conductive ink is used for the conductive circuit 50, the method of printing the conductive ink onto the CNT base fabric 20 is not particularly limited and can be done by conventionally known methods such as screen printing, rotary screen printing, flexographic printing, inkjet printing, gravure printing, gravure offset printing, and offset printing. Screen printing is preferred because it allows for inexpensive mass production.

[0045] Furthermore, assuming a voltage of 13.5V and a current of 3A applied to the automobile, the maximum output is achieved when the resistance value of the CNT base fabric, conductive circuit, and wiring is preferably approximately 4Ω to 10Ω, as this allows for the most efficient heating.

[0046] Next, in order to arrange the conductors on the resin substrates 30 and 40, a step is performed to bond the CNT base fabric 20, to which the conductive circuit 50 is connected, to the resin substrates 30 and 40. The method for molding the resin substrates 30 and 40 is not particularly limited, and as described above, known molding methods corresponding to the resin used can be used. For example, in Figure 1, if the resin substrate 30 is polyurethane resin and the resin substrate 40 is PP resin, the polyurethane resin can be molded by RIM molding (reaction injection molding), and the PP resin can be molded by injection molding. In the case of RIM molding, the PP resin substrate can be set in a mold, and a reaction mixture of polyol and isocyanate can be injected to form the substrate.

[0047] Furthermore, the method for bonding the CNT base fabric 20 and the resin substrates 30 and 40 is not particularly limited. For example, when bonding the resin substrates 30 and 40 prepared as described above to the CNT base fabric 20, the CNT base fabric 20 and the resin substrates 30 can be bonded together using double-sided tape, adhesive sheets, or adhesives.

[0048] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0049] [Examples] As raw materials for the CNT dispersion, SWCNTs and DMF without a dispersant (an aprotic solvent) were prepared. The SWCNTs used were TUBALL® (registered trademark) manufactured by OCSiAl (outer diameter 1.6 ± 0.4 nm, length ≥ 5 μm). The CNT dispersion was prepared by dispersing the SWCNTs in DMF using an ultrasonic homogenizer to a SWCNT content of 0.1% by mass. The ultrasonic homogenizer was operated under conditions of a 10-second pulse cycle and a vibration amplitude of 40%, for 30 minutes.

[0050] In Example 1, PET fiber (Calcuro) was used as the synthetic fiber. A test sample of a base fabric composed of PET fiber was then prepared.

[0051] A magnetic ball mill was used to immerse test samples of the base fabric in a CNT dispersion. The magnetic ball mill settings were 350 rpm for 30 minutes. This immersion in the CNT dispersion was repeated twice.

[0052] Next, the base fabric 21, which had been immersed in the CNT dispersion, was dried by vacuum drying at approximately 26°C for approximately 6 hours to remove DMF. The CNT base fabric 20 was then prepared. The thickness of the CNT base fabric was approximately 0.5 to 1 mm.

[0053] Next, after applying a barrier coat layer to a thickness of approximately 20 μm using the method described above, a polyurethane resin is applied as a synthetic leather layer with a thickness of 0.3 to 0.5 mm and a density of 0.5 g / cm³. 3 The coating was applied. Then, the CNT base fabric prepared as described above was placed on top of the synthetic leather layer, and a weight was placed on top to heat and dry it at 85°C.

[0054] Subsequently, silver ink was printed onto the CNT base fabric to a thickness of approximately 30 μm using screen printing, and conductive circuits were connected. Furthermore, wiring was connected to the conductive circuits to allow current to flow through the CNT base fabric.

[0055] On the other hand, as Comparative Example 1, a conductive base fabric manufactured by KJ Specialty Paper Co., Ltd. was used instead of the CNT base fabric prepared as described above. Specifically, as shown in Figure 9, the weft 210 used conductive fibers made by impregnating PET fibers with CNT paint, and the warp 220 used non-conductive PET fibers in the woven fabric. As Comparative Example 2, a base fabric made by Cu-Ni plating PET fibers manufactured by Seiren Co., Ltd. was used instead of the CNT base fabric 20. Furthermore, as Comparative Example 3, a nonwoven fabric with nichrome wire sewn on as a heater wire was used. In Comparative Examples 1 to 3, the components other than the CNT base fabric in Example 1, namely the barrier coat layer and synthetic leather layer, were prepared in the same manner as in Example 1. In addition, for the conductive circuits in Comparative Examples 1 and 2, silver ink was printed in the same manner as in Example 1, and wiring was connected to enable current flow. For the conductive circuit in Comparative Example 3, wiring was connected to the nichrome wire to enable current flow.

[0056] (evaluation) Example 1 and Comparative Examples 1-3 were evaluated using the methods described below.

[0057] <Evaluation of conductivity> The resistance between electrodes was measured by connecting a digital multimeter (PM3, manufactured by Sanwa Electric Instrument Co., Ltd.) to the wiring.

[0058] The surface resistivity was measured using the Van der Pauw method. As shown in Figure 10, the magnitude of the current when a current power supply was connected between two terminals and the resistances R1 and R2 due to the potential difference between the other two terminals were determined, and the correction coefficient f, which is determined by the ratio of resistances R1 and R2 (R1 > R2), was obtained from a table. Then, the surface resistivity Rs (Ω / sq.) was calculated by solving the following equation (1). Rs=(π / ln2)·(R1+R2) / 2·f(R1 / R2) (1)

[0059] <Evaluation of temperature rise> The center point temperature was measured from the barrier coat layer side using an infrared thermography camera (FLIR E5 Pro, manufactured by FLIR Systems).

[0060] The time to reach 42°C was measured by applying voltage from room temperature (20°C) and taking the time for the center point temperature to reach 42°C.

[0061] The amount of electricity was calculated using the following equations (2) and (3). Electric energy (Wh) = Electric power (W) × Time to reach 42℃ (h) (2) Power (W) = 13.5 (V) × Measured Current (A) (3)

[0062] [Table 1]

[0063] The evaluation results are shown in Table 1. As described above, when the voltage applied to the automobile is 13.5V and the current is 3A, the maximum output is achieved when the resistance values ​​of the CNT base fabric, silver ink, and wiring are approximately 4Ω to 10Ω, allowing for the most efficient heating. In Example 1, the above resistance value, which allows for the most efficient heating, was achieved by adjusting the surface resistivity of the CNT base fabric to 4Ω / sq. to 6Ω / sq. Then, heating was achieved by applying current to the CNT base fabric, and heating could be performed without feeling any foreign matter due to the lifting or unevenness of the heater wire. In addition, the center point temperature could be raised within the range of 30℃ to 60℃, and the time to reach 42℃ was within 300 seconds. Furthermore, the amount of power consumed was significantly reduced compared to Comparative Example 3, which used nichrome wire.

[0064] On the other hand, in Comparative Example 1, the paint on the CNT contained a binder, and the inter-electrode resistance value was 4.0 × 10⁻⁶. 7 The temperature did not rise because the resistance was too high (Ω). Furthermore, the conductive base fabric used in Comparative Example 1 conducts electricity only in the weft threads, so the anisotropy in the direction of current flow is also considered to be a factor in the high resistance value. In addition, in Comparative Example 1, since the CNTs are fixed to the fibers by the binder, it is possible that the CNTs may peel off from the fibers due to the solvent test or the effect of the adhesive, causing the resistance value to increase. In addition, the resistance value between electrodes in Comparative Example 2 is 1.0 × 10⁻⁶. -2The impedance was too low (Ω), so it did not heat up. Furthermore, in Comparative Example 3, although it did heat up, a foreign body sensation was felt due to the lifting and unevenness of the heater wire. In addition, Comparative Example 3 consumed more power than Example 1.

[0065] These results show that the conductive member 1 according to this embodiment provides a conductive member that eliminates the foreign body sensation caused by the heater wire and improves tactile sensation. Furthermore, the conductive member 1 was able to reduce power consumption compared to a conductive member using nichrome wire.

[0066] Although this embodiment has been described above, this embodiment is not limited to these, and various modifications are possible within the scope of the gist of this embodiment. [Explanation of Symbols]

[0067] 1. Conductive member 10 Synthetic leather layer 20. Carbon nanotube-based fabric (CNT-based fabric) 21 Base fabric 23 Aprotic solvents 24. Carbon nanotube dispersion (CNT dispersion) 25 Carbon nanotubes (CNTs) 30,40 Resin base material 50 Conductive Circuits

Claims

1. Carbon nanotube substrate and The system comprises a synthetic leather layer disposed on the carbon nanotube base fabric, The carbon nanotube base fabric is a conductor comprising a base fabric made of synthetic fibers and carbon nanotubes attached to the base fabric.

2. The conductor according to claim 1, wherein the synthetic fiber has grooves on its surface and has an irregular cross-sectional shape.

3. The conductor according to claim 1 or 2, wherein the synthetic fiber is a polyester fiber.

4. A conductor according to claim 1 or 2, A resin substrate on which the aforementioned conductor is arranged, A conductive member comprising a conductive circuit connected to the aforementioned conductor.

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