Conductive nonwoven fabric, shielding tape, and wire harness

Abstract

A conductive nonwoven fabric (11) comprises a nonwoven fabric (11a), and a plating part (11b) formed from a conductive metal that covers fibers (F) constituting the nonwoven fabric (11a). The value obtained by dividing the electrical resistance value in an intermediate layer positioned in the middle in the thickness direction of the conductive nonwoven fabric (11), by the electrical resistance value in a surface layer of the conductive nonwoven fabric (11), is 4.0 or lower. The shielding tape (10) comprises the conductive nonwoven fabric (11) and an adhesive layer (12). A wire harness (1) comprises an electric wire (W) and the shielding tape (10).

Description

[Technical field]

[0001] The present invention relates to a conductive nonwoven fabric, a shielding tape, and a wire harness. [Background technology]

[0002] A cable has been proposed in which a conductive nonwoven fabric having a nonwoven fabric and a metal layer formed on the surface of the nonwoven fabric is arranged around the outer periphery of an electric wire (see, for example, Patent Document 1). This cable exhibits an electromagnetic shielding effect due to the metal layer of the conductive nonwoven fabric, but can be easily bent because the nonwoven fabric has excellent stretching and compressing properties. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-075375 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the conductive nonwoven fabric used in the cable described in Patent Document 1 has insufficient shielding performance because the metal layer is formed only on the surface of the nonwoven fabric, and it is merely positioned as a supplementary shielding member. Therefore, the cable described in Patent Document 1 requires an outer conductor layer in addition to the conductive nonwoven fabric, resulting in a complex cable structure.

[0005] An object of the present invention is to provide a conductive nonwoven fabric, a shielding tape, and a wire harness that can achieve both improved shielding performance and suppression of complexity of the cable structure. [Means for solving the problem]

[0006] In a first aspect of the present invention, there is provided a method for producing a conductive nonwoven fabric comprising: a nonwoven fabric; and a plated portion made of a conductive metal that coats fibers constituting the nonwoven fabric, the method comprising the steps of: the value obtained by dividing the electrical resistance value of an intermediate layer, which is the middle position in the thickness direction of the conductive nonwoven fabric, by the electrical resistance value of a surface layer of the conductive nonwoven fabric is 4.0 or less; The conductive nonwoven fabric has a thickness of 50 μm or more and 2.0 mm or less, The conductive nonwoven fabric has the following properties: Using supercritical carbon dioxide containing an organometallic complex, The product is manufactured by carrying out supercritical processing under the conditions of a pressure of 12 MPa to 15 MPa, a temperature of 100°C to 130°C, a time of 10 minutes to 60 minutes, and a circulation flow rate during processing of 0.5 kg / min to 8 kg / min, followed by electroless plating. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing a wire harness according to an embodiment of the present invention. [Figure 2A] 2A is a cross-sectional view of the shielding tape when the shielding tape is cut along a plane along the axial direction of the wire harness in FIG. [Figure 2B] FIG. 2B is an enlarged view of part A in FIG. 2A. [Figure 2C] FIG. 2C is an enlarged view of part B in FIG. 2B. [Diagram 3] FIG. 3 is an electron microscope photograph showing a cross section of the conductive nonwoven fabric of the shielding tape, which corresponds to FIG. 2A. [Figure 4] FIG. 4 is an enlarged view of a portion corresponding to the intermediate layer of the conductive nonwoven fabric in the electron microscope photograph shown in FIG. [Diagram 5] FIG. 5 is a schematic diagram for explaining a plating pretreatment method applied to a conductive nonwoven fabric. [Figure 6] FIG. 6 is a table showing the formation states of the plated portions in Examples 1 and 2 and Comparative Examples 1 to 4. [Figure 7] FIG. 7 is a diagram showing the evaluation methods for Examples 1 and 2 and Comparative Examples 1 to 4. [Figure 8] FIG. 8 is a graph showing the flex resistance of Example 1 and Comparative Examples 5 and 6. [Figure 9]FIG. 9 is a graph showing the shielding performance of Example 1 and Comparative Examples 5 and 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described below along with preferred embodiments. Note that the present invention is not limited to the embodiments shown below, and can be modified as appropriate within the scope of the present invention. In addition, in the embodiments shown below, some configurations are omitted from illustration and description, but it goes without saying that publicly known or well-known technologies are appropriately applied to the details of the omitted technologies within the scope of the contents described below.

[0011] 1 is a perspective view showing a wire harness 1 according to an embodiment of the present invention. The wire harness 1 according to this embodiment includes an electric wire W, a corrugated tube 50, and a shielding tape 10 attached to an inner wall surface of the corrugated tube 50. Note that the wire harness 1 may include another tube material instead of the corrugated tube 50, or may include a tape wound around the corrugated tube 50 or the other tube material.

[0012] The electric wire W includes a conductor made of, for example, copper, aluminum, or an alloy thereof, and an insulating coating that coats the conductor. In the present embodiment shown in FIG. 1, the conductor of the electric wire W is composed of a single strand. However, the conductor of the electric wire W may be a stranded wire in which a plurality of strands are twisted together. Furthermore, the wire harness 1 may include a plurality of electric wires W.

[0013] The corrugated tube 50 is a tubular member having a bellows portion formed with a series of alternating concaves and convexes in the longitudinal direction. The corrugated tube 50 is made of resin. For example, an electric wire W is inserted from an end of the corrugated tube 50, so that the corrugated tube 50 is disposed so as to cover the periphery of the electric wire W.

[0014] The shielding tape 10 has a conductive nonwoven fabric 11 as a shielding layer that exhibits a shielding function against external noise and the like. Fig. 2A is a cross-sectional view of the shielding tape 10 when the shielding tape 10 is cut along a plane along the axial direction of the wire harness 1 shown in Fig. 1, Fig. 2B is an enlarged view of part A in Fig. 2A, and Fig. 2C is an enlarged view of part B in Fig. 2B. As shown in Fig. 2A, the shielding tape 10 includes a conductive nonwoven fabric 11 and an adhesive layer 12 arranged so as to be laminated on the conductive nonwoven fabric 11 (i.e., on the front or back surface of the conductive nonwoven fabric 11). As shown in Fig. 1, the shielding tape 10 is attached to the inner wall surface of the corrugated tube 50 via the adhesive layer 12, and is provided so as to surround the electric wire W.

[0015] As shown in Fig. 2B, the conductive nonwoven fabric 11 includes a nonwoven fabric 11a and a plated portion 11b. The nonwoven fabric 11a is a sheet-like member in which fibers are intertwined without being woven, and has a predetermined thickness. As shown in Fig. 2B, the nonwoven fabric 11a has a structure in which the fibers F constituting the nonwoven fabric 11a are arranged in a number of layers in the thickness direction due to the characteristics of the manufacturing process. The nonwoven fabric 11a is made of, for example, fibers made of polyethylene terephthalate (PET), polypropylene, nylon, and resins such as acrylic, glass fibers, carbon fibers, aramid fibers, and polyarylate fibers.

[0016] The plated portion 11b is a conductive metal that covers the fibers F that make up the nonwoven fabric 11a. The plated portion 11b is made of, for example, copper, nickel, tin, silver, or an alloy of these metals. The plated portion 11b may be formed in a single layer so as to cover the fibers F that make up the nonwoven fabric 11a, or may be formed in a multi-layered structure. As an example, the plated portion 11b may have a multi-layered structure in which a first layer made of copper is provided so as to cover the fibers F that make up the nonwoven fabric 11a, and a second layer made of tin is provided so as to cover the first layer.

[0017] Here, in the conductive nonwoven fabric 11 according to this embodiment, the plated portion 11b is formed all the way to the inside of the nonwoven fabric 11a. Fig. 3 is an electron microscope photograph showing a cross section of the conductive nonwoven fabric 11 in which the plated portion 11b is formed on the resin fiber F, and Fig. 4 is an enlarged view of a portion corresponding to the middle layer M of the conductive nonwoven fabric 11 in the electron microscope photograph shown in Fig. 3.

[0018] As shown in FIG. 2B, the fibers F constituting the nonwoven fabric 11a are arranged in a multi-layered manner in the thickness direction of the nonwoven fabric 11a. In the conductive nonwoven fabric 11 according to this embodiment, the plated portions 11b are formed not only on the surface layer S (see FIG. 3) but also on the intermediate layer M (see FIGS. 3 and 4) which is the intermediate position MP in the thickness direction. In FIG. 4, due to the insulating properties of the resin fiber F, the cross section of the fiber F is observed as black dots in the image taken by the electron microscope. Meanwhile, the portions other than the cross section of the fiber F are observed as fibrous. From this, it can be said that the plated portions 11b are appropriately formed on the fiber F in the intermediate layer M of the conductive nonwoven fabric 11.

[0019] In particular, in the conductive nonwoven fabric 11 according to this embodiment, the value obtained by dividing the electrical resistance value Rm in the intermediate layer M of the conductive nonwoven fabric 11 by the electrical resistance value Rs in the surface layer S (strictly speaking, the surface) of the conductive nonwoven fabric 11 is 4.0 or less. Generally, even when a conductive nonwoven fabric is plated, a plated portion is formed only near the surface layer, and it is difficult for a plated portion to be formed in the interior (intermediate layer). However, in the conductive nonwoven fabric 11 according to this embodiment, a plated portion 11b is formed up to the intermediate layer M. Therefore, the surface layer S on one side and the surface layer S on the opposite side can be electrically connected via the intermediate layer M.

[0020] The conductive nonwoven fabric 11 preferably has a thickness of 50 μm or more and 2.0 mm or less. As shown in FIG. 2B, the conductive nonwoven fabric 11 has the fibers F constituting the nonwoven fabric 11a arranged in multiple layers in the thickness direction, and therefore the plated portion 11b is also arranged in multiple layers in the thickness direction. As a result, the conductive nonwoven fabric 11 can exhibit high shielding performance compared to a single layer of metal foil or the like. However, if the thickness of the conductive nonwoven fabric 11 is less than 50 μm, the number (layers) of fibers F overlapping in the thickness direction is small, and it may be difficult to exhibit sufficient shielding performance. On the other hand, if the thickness exceeds 2 mm, there is a concern that the manufacturing burden will increase, for example, it will take time to form the plated portion 11b in the intermediate layer M (see FIG. 3).

[0021] Next, a method for producing the conductive nonwoven fabric 11 according to this embodiment will be described. Fig. 5 is a schematic diagram for explaining the plating pretreatment method according to this embodiment.

[0022] First, the nonwoven fabric 11a is prepared. The nonwoven fabric 11a prepared here is made of fibers made of resin such as polyethylene terephthalate, polypropylene, nylon, and acrylic, glass fiber, carbon fiber, aramid fiber, polyarylate fiber, and the like.

[0023] Next, the nonwoven fabric 11a is treated with a supercritical fluid (e.g., carbon dioxide). In this treatment, as shown in Fig. 5, an organometallic complex 30 soluble in a supercritical fluid (e.g., palladium or nickel soluble in carbon dioxide in a supercritical state) is stored in a housing 40. Furthermore, the nonwoven fabric 11a is stored in the housing 40 in a state where it is wound around a cylindrical bobbin, for example, two times.

[0024] After storing the nonwoven fabric 11a, in this embodiment, carbon dioxide in a supercritical state is supplied to the housing 40. The supercritical conditions for carbon dioxide are a pressure of 12 MPa to 15 MPa, a temperature of 100° C. to 130° C., and a time of 10 minutes to 60 minutes. Furthermore, the circulation flow rate during processing is 0.5 kg / min to 8 kg / min.

[0025] This treatment causes the organometallic complex 30 to dissolve in the supercritical carbon dioxide and be reduced, and the metal generated by decomposition of the organometallic complex 30 is precipitated not only in the surface layer S (see FIG. 3) of the nonwoven fabric 11a but also in the middle layer M (see FIG. 4). In particular, since the circulation flow rate during treatment is 0.5 kg / min or more and 8 kg / min or less as the supercritical condition, the supercritical carbon dioxide reaches the middle layer M of the nonwoven fabric 11a and the metal is precipitated sufficiently in the middle layer M. Supercritical carbon dioxide has excellent solubility and diffusibility, and easily precipitates the metal substantially uniformly without unevenness up to the middle layer M of the nonwoven fabric 11a.

[0026] Next, after a predetermined time has elapsed (e.g., 30 minutes), the nonwoven fabric 11a is removed from the housing 40. Furthermore, a heat treatment is performed, for example, at 150° C. or higher (250° C. or higher depending on the heat resistance of the fibers F constituting the nonwoven fabric 11a) for 60 minutes or more. This heat treatment removes residual components of the supercritical fluid on the fibers F and activates the metal precipitated on the fibers F.

[0027] Then, electroless plating is performed. In this embodiment, the metal serving as a catalyst is deposited on nonwoven fabric 11a up to intermediate layer M. Therefore, plated portion 11b is formed also on intermediate layer M of nonwoven fabric 11a by electroless plating.

[0028] Through the above steps, a conductive nonwoven fabric 11 is obtained in which the value obtained by dividing the electrical resistance value Rm of the intermediate layer M by the electrical resistance value Rs of the surface layer S is 4.0 or less.

[0029] Next, examples and comparative examples of the conductive nonwoven fabric 11 according to this embodiment will be described.

[0030] FIG. 6 is a table showing the formation states of the plated portions in Examples 1 and 2 and Comparative Examples 1 to 4, and FIG.

[0031] The conductive nonwoven fabrics according to Examples 1 and 2 and Comparative Examples 1 and 2 were manufactured by subjecting a PET nonwoven fabric to the above-mentioned supercritical treatment. For the supercritical treatment, palladium hexafluoroacetylacetonate was used as an organometallic complex, and carbon dioxide in a supercritical state was supplied. The supercritical conditions for carbon dioxide were a temperature of 100°C, a pressure of 12 MPa, and a time of 30 minutes. Then, copper plating was performed by electroless plating. In Examples 1 and 2, the circulation flow rate was 3.8 kg / min, and the thickness of the nonwoven fabric was about 1 mm. In Comparative Examples 1 and 2, the circulation flow rate was 0.4 kg / min, and the thickness of the nonwoven fabric was 3 mm. Due to the difference between the circulation flow rate and the thickness of the nonwoven fabric, in Examples 1 and 2, copper plating was performed even inside the nonwoven fabric, while in Comparative Examples 1 and 2, copper plating was performed only on the surface layer of the nonwoven fabric.

[0032] The conductive nonwoven fabric in Comparative Examples 3 and 4 was made of PET nonwoven fabric that was copper-plated by a so-called sputtering method (manufactured by Sekisui Nano Coat Technology Co., Ltd.). In Comparative Examples 3 and 4, the thickness of the nonwoven fabric was about 3 mm.

[0033] Such conductive nonwoven fabrics according to Examples 1 and 2 and Comparative Examples 1 to 4 were cut into two pieces at the middle position in the thickness direction (the position corresponding to the middle position MP shown in FIG. 3) as shown in FIG. 7, and the cut surface was defined as the inner layer, and the surface opposite to the inner layer was defined as the surface layer. One of the two slices obtained by cutting the conductive nonwoven fabric was designated slice 1, and the other was designated slice 2.

[0034] As shown in FIG. 6, in Example 1, the electrical resistance value (hereinafter referred to as "surface resistance") at the surface of the surface layer of slice 1 was 0.874 Ω / m, and the surface resistance at the inner layer was 0.375 Ω / m. The surface resistance at the surface layer of slice 2 was 0.056 Ω / m, and the surface resistance at the inner layer was 0.088 Ω / m. When the thickness of slice 1 was measured at four specific locations on slice 1, the average thickness value at those four locations (hereinafter referred to as "four-location average") was 0.60 mm, and the four-location average thickness of slice 2 was 0.70 mm.

[0035] Therefore, in Example 1, the value obtained by dividing the surface resistance of the intermediate layer by the surface resistance of the surface layer was approximately 0.43 for slice 1 and approximately 1.57 for slice 2.

[0036] In Example 2, the surface resistance of the surface layer of slice 1 was 0.196 Ω / m, and the surface resistance of the inner layer was 0.615 Ω / m. The surface resistance of the surface layer of slice 2 was 0.260 Ω / m, and the surface resistance of the inner layer was 0.168 Ω / m. The average thickness of slice 1 at four points was 0.84 mm, and the average thickness of slice 2 at four points was 0.65 mm.

[0037] Therefore, in Example 2, the value obtained by dividing the surface resistance of the intermediate layer by the surface resistance of the surface layer was approximately 3.14 for slice 1 and approximately 0.64 for slice 2.

[0038] In Comparative Example 1, the surface resistance of the surface layer of slice 1 was 0.2207 Ω / m, and the surface resistance of the inner layer was not measurable because no plating was formed in the inner layer (i.e., the value was extremely large. Generally, the surface resistance of PET is 10 15 The surface resistance of the surface layer of slice 2 was 0.1892 Ω / m, and the surface resistance of the inner layer was not measurable (i.e., extremely large). The thickness of slice 1 was 1.39 mm on average at four locations, and the thickness of slice 2 was 1.56 mm on average at four locations.

[0039] Therefore, it was clear that in Comparative Example 1, the value obtained by dividing the surface resistance of the intermediate layer by the surface resistance of the surface layer was an extremely large value.

[0040] In Comparative Example 2, the surface resistance of the surface layer of slice 1 was 0.1303 Ω / m, and the surface resistance of the inner layer was not measurable (i.e., an extremely large value) because no plating was formed in the inner layer. The surface resistance of the surface layer of slice 2 was 0.215 Ω / m, and the surface resistance of the inner layer was not measurable (i.e., an extremely large value). The thickness of slice 1 was 1.62 mm on average at four points, and the thickness of slice 2 was 1.47 mm on average at four points.

[0041] Therefore, it was clear that in Comparative Example 2, the value obtained by dividing the surface resistance of the intermediate layer by the surface resistance of the surface layer was an extremely large value.

[0042] In Comparative Example 3, the surface resistance of the surface layer of slice 1 was 6.39 kΩ / m, and the surface resistance of the inner layer was not measurable (i.e., an extremely large value) because no plating was formed in the inner layer. The surface resistance of the surface layer of slice 2 was 297.7 kΩ / m, and the surface resistance of the inner layer was not measurable (i.e., an extremely large value). The thickness of slice 1 was 1.6 mm on average at four points, and the thickness of slice 2 was 1.4 mm on average at four points.

[0043] Therefore, it was clear that in Comparative Example 3, the value obtained by dividing the surface resistance of the intermediate layer by the surface resistance of the surface layer was an extremely large value.

[0044] In Comparative Example 4, the surface resistance of the surface layer of slice 1 was 62.66 Ω / m, and the surface resistance of the inner layer was not measurable (i.e., an extremely large value) because no plating was formed in the inner layer. The surface resistance of the surface layer of slice 2 was 355.9 kΩ / m, and the surface resistance of the inner layer was not measurable (i.e., an extremely large value). The thickness of slice 1 was 1.8 mm on average at four points, and the thickness of slice 2 was 1.2 mm on average at four points.

[0045] Therefore, it was clear that in Comparative Example 4, the value obtained by dividing the surface resistance of the intermediate layer by the surface resistance of the surface layer was an extremely large value.

[0046] As described above, in the conductive nonwoven fabrics according to Comparative Examples 1 to 4, the plated portion was not formed up to the intermediate layer, and the value obtained by dividing the surface resistance of the intermediate layer by the surface resistance of the surface layer was never 4.0 or less. In contrast, in the conductive nonwoven fabrics according to Examples 1 and 2, the plated portion was formed up to the intermediate layer, and the value obtained by dividing the surface resistance of the intermediate layer by the surface resistance of the surface layer was 4.0 or less. In other words, it was found that the conductive nonwoven fabrics according to Examples 1 and 2 have a sufficient plated portion formed up to the intermediate layer, and can exhibit high shielding performance.

[0047] FIG. 8 is a graph showing the flex resistance of the conductive nonwoven fabric of Example 1 and the conductors of Comparative Examples 5 and 6.

[0048] The conductive nonwoven fabric of Example 1 was produced by subjecting PET nonwoven fabric to supercritical treatment as described above (see Figs. 6 and 7). A flat-braided tin-plated soft copper wire with a cross-sectional area of ​​5.5 sq (manufactured by Meiko Futaba Co., Ltd., product name: TBC (5.5 sq)) was used as the conductor of Comparative Example 5. A copper foil with a thickness of 13 µm was used as the conductor of Comparative Example 6. Note that "sq" stands for "mm 2 " is substantially identical to "

[0049] For the bending resistance test, a weight of 100 g was attached to one end of the conductive nonwoven fabric of Example 1 and the conductors of Comparative Examples 5 and 6, and the one end was fixed. Then, at room temperature (e.g., 23°C), the other ends of the conductive nonwoven fabric and the conductors were repeatedly bent at a speed of 30 rpm in an angle range of -90° to 90° using a mandrel with a bending radius of 1 mm. For each of the conductive nonwoven fabric of Example 1 and the conductors of Comparative Examples 5 and 6, the number of reciprocating bends (number of breaks) until one end and the other end of each were completely separated was measured.

[0050] As a result, the conductive nonwoven fabric of Example 1 did not break even after being bent 200,000 times. The conductor of Comparative Example 5 broke after being bent 1,588 times. The conductor of Comparative Example 6 broke after being bent 543 times. Therefore, it was found that the conductive nonwoven fabric of Example 1 has excellent flexibility (ability to follow the bending of an electric wire).

[0051] FIG. 9 is a graph showing the shielding performance of the conductive nonwoven fabric of Example 1 and the conductors of Comparative Examples 5 and 7.

[0052] The conductive nonwoven fabric of Example 1 was produced by subjecting a PET nonwoven fabric to supercritical treatment as described above (see Figs. 6 and 7). The flat-braided tin-plated soft copper wire described above was used as the conductor of Comparative Example 5. The copper PET film in which a copper foil having a thickness of 8 µm and a PET film having a thickness of 12 µm were laminated was used as the conductor of Comparative Example 7. The conductive nonwoven fabric of Example 1 had a conductor resistance of 830 mΩ / m, the flat-braided tin-plated soft copper wire of Comparative Example 5 had a conductor resistance of 3.6 mΩ / m, and the copper PET film of Comparative Example 7 had a conductor resistance of 72 mΩ / m.

[0053] The shielding effect of these conductive nonwoven fabrics and conductors was evaluated by an absorbing clamp method, with the sample length of each sample using the conductive nonwoven fabric and conductor being 1 m. Considering the magnitude of the conductor resistance value described above, it was predicted that the flat-braided tin-plated soft copper wire of Comparative Example 5 would have the highest shielding effect, and Example 1 would have the lowest. However, in reality, as shown in Figure 9, the conductive nonwoven fabric of Example 1 was superior to the conductors of Comparative Examples 5 and 7 in terms of shielding performance in the high frequency band of 60 MHz or more.

[0054] This is thought to be because, according to the shielding theory based on the Kley equation, in the conductive nonwoven fabric of Example 1, the fibers are arranged in multiple layers in the thickness direction of the conductive nonwoven fabric and plated portions are formed on those fibers, so that each of the numerous fiber layers exhibits a shielding function.

[0055] In this way, the value obtained by dividing the electrical resistance value Rm in the intermediate layer M of the conductive nonwoven fabric 11 according to this embodiment by the electrical resistance value Rs in the surface layer S is 4.0 or less. Therefore, the plated portion 11b is formed up to the middle position MP in the thickness direction of the conductive nonwoven fabric 11. In other words, the surface layer S of the nonwoven fabric 11a and the surface layer S on the opposite side can be electrically connected through the middle position MP. Therefore, compared with the case where the plated portion 11b is formed only on the surface of the nonwoven fabric 11a, the conductive nonwoven fabric 11 can exhibit higher shielding performance. Since the conductive nonwoven fabric 11 has excellent shielding performance, for example, when a wire harness is manufactured using an electric wire and the conductive nonwoven fabric 11, it is not necessary to provide a shielding layer separate from the conductive nonwoven fabric 11, and the configuration of the wire harness can be prevented from becoming complicated. That is, a wire harness that achieves both high shielding performance and simplified configuration can be provided. Here, the value obtained by dividing the electrical resistance value Rm in the intermediate layer M of the conductive nonwoven fabric 11 by the electrical resistance value Rs in the surface layer S is preferably 3.2 or less, and more preferably 1.6 or less.

[0056] The thickness of the conductive nonwoven fabric 11 is 50 μm or more and 2.0 mm or less. As a result, since the thickness is 50 μm or more, the fibers of the conductive nonwoven fabric 11 are arranged in multiple layers in the thickness direction, thereby improving the shielding performance. As the thickness is 2.0 mm or less, the plated portion 11b is reliably formed up to the middle position MP of the conductive nonwoven fabric 11, and the shielding performance can be improved. Therefore, it is possible to provide a conductive nonwoven fabric 11 with excellent shielding performance.

[0057] The shielding tape 10 according to this embodiment includes the conductive nonwoven fabric 11 and the adhesive layer 12, and therefore the conductive nonwoven fabric 11 can be easily attached to the electric wires W or the like via the adhesive layer 12.

[0058] The wire harness 1 according to the present embodiment includes an electric wire W and a shielding tape 10 provided around the electric wire W. In the present embodiment, the shielding tape 10 is attached to an inner wall surface of a corrugated tube 50. However, the shielding tape 10 may be attached directly to the electric wire W.

[0059] The present invention is not limited to the above-described embodiments, and various modifications can be adopted within the scope of the present invention. For example, the present invention is not limited to the above-described embodiments, and appropriate modifications, improvements, etc. are possible. In addition, the material, shape, size, number, arrangement location, etc. of each component in the above-described embodiments are arbitrary as long as the present invention can be achieved, and are not limited.

[0060] For example, in the present embodiment, the wire harness 1 includes the corrugated tube 50. However, the wire harness 1 does not have to include the corrugated tube 50. Furthermore, the shielding tape 10 may be directly wrapped around the electric wire W. When the shielding tape 10 is directly attached to the electric wire W, the electric wire W may be sandwiched between the adhesive layers 12 of two shielding tapes 10.

[0061] 1, the shielding tape 10 is attached to the inner wall surface of the corrugated tube 50 without any overlapping portions where the shielding tapes 10 overlap each other. However, the shielding tape 10 may be attached to the inner wall surface of the corrugated tube 50 with an overlapping portion.

[0062] Furthermore, in this embodiment, in manufacturing the conductive nonwoven fabric 11, a supercritical process is followed by a heat treatment and then an electroless plating process. However, when the nonwoven fabric 11a is made of PET, the heat treatment may be omitted. This is because, in the usage environment in which the wire harness 1 using the conductive nonwoven fabric 11 is mounted on an automobile, there is considered to be no problem in terms of quality even if the heat treatment of the nonwoven fabric 11a is omitted from the viewpoint of hydrolysis and heat resistance.

[0063] This application is based on a Japanese patent application (Patent Application No. 2021-178590) filed on November 1, 2021, the contents of which are incorporated herein by reference. [Industrial Applicability]

[0064] The conductive nonwoven fabric, shielding tape, and wire harness of the present invention can achieve both improved shielding performance and suppression of the complication of the cable structure. The present invention having this effect can be used, for example, as a wire harness to be mounted on an automobile or the like. [Explanation of symbols]

[0065] 1: Wire harness 10: Shielding tape 11: Conductive nonwoven fabric 11a: Non-woven fabric 11b: Plating department 12: Adhesive layer 30: Organometallic complexes 40: Cabinet 50: Corrugated tube F: Fiber M: Middle class MP: intermediate position S: Surface layer W: Electric wire

Claims

[Claim 1] A method for producing a conductive nonwoven fabric comprising: a nonwoven fabric; and a plated portion made of a conductive metal that coats fibers constituting the nonwoven fabric, the method comprising the steps of: a value obtained by dividing the electrical resistance value of an intermediate layer that is a middle position in the thickness direction of the conductive nonwoven fabric by the electrical resistance value of a surface layer of the conductive nonwoven fabric is 4.0 or less; The conductive nonwoven fabric has a thickness of 50 μm or more and 2.0 mm or less, The conductive nonwoven fabric is produced by subjecting the nonwoven fabric to a supercritical treatment using supercritical carbon dioxide containing an organometallic complex under conditions of a pressure of 12 MPa to 15 MPa, a temperature of 100° C. to 130° C., a treatment time of 10 minutes to 60 minutes, and a circulation flow rate during the treatment of 0.5 kg / min to 8 kg / min, and then performing an electroless plating treatment. A method for manufacturing conductive nonwoven fabric.

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