Conductive nonwoven fabric and method for manufacturing the same

Abstract

Provided are an electrically conductive nonwoven fabric and a method of manufacturing the same. The electrically conductive nonwoven fabric includes a metal-plated felt portion including a felt portion formed of a plurality of first fibers extending in an irregular direction and stacked, and a metal plating layer applied to the first fibers of the felt portion; and at least one metal-plated warp thread including a warp thread formed of a plurality of second fibers and a metal plating layer applied to the second fibers of the warp thread. The at least one metal-plated warp thread is formed to extend in a specific direction with respect to the metal-plated felt portion, and a density of the second fibers is higher than a density of the first fibers.

Description

Technical Field

[0001] This disclosure relates to a conductive nonwoven fabric and a method for manufacturing the same. Background Technology

[0002] In related technologies, a conductive nonwoven fabric with a metal layer formed on the nonwoven fabric has been proposed (for example, see JP2019-75375A).

[0003] For example, this conductive nonwoven fabric is wrapped around the outside of the wire and used as part of the shielding cable.

[0004] In shielded cables, the metallic layer of conductive nonwoven fabric exhibits electromagnetic shielding effect. At the same time, due to the properties of the material, nonwoven fabric has relatively good expansion and compression properties and can follow the bending of the wire.

[0005] However, the conductive nonwoven fabric disclosed in JP2019-75375A is not effective in metal deposition. Summary of the Invention

[0006] This disclosure provides a conductive nonwoven fabric and a method for manufacturing a conductive nonwoven fabric capable of enhancing metal deposition.

[0007] According to an illustrative aspect of this disclosure, a conductive nonwoven fabric includes: a metallized felt portion comprising a felt portion formed of a plurality of first fibers extending and stacked in an irregular direction, and a metallized coating applied to the first fibers of the felt portion; and at least one metallized warp comprising a warp formed of a plurality of second fibers and a metallized coating applied to the second fibers of the warp. The at least one metallized warp is formed to extend in a specific direction relative to the metallized felt portion, and the density of the second fibers is higher than the density of the first fibers.

[0008] According to another illustrative aspect of this disclosure, a method for manufacturing a conductive nonwoven fabric includes: preparing a nonwoven fabric comprising: a felt portion wherein a plurality of first fibers extending in an irregular direction are stacked; and at least one warp yarn formed of a plurality of second fibers and extending in a specific direction relative to the felt portion, the second fibers having a higher density than the first fibers; placing the nonwoven fabric in a processing tank; immersing the nonwoven fabric in a supercritical or subcritical fluid containing an organometallic complex of a catalyst metal for metallization; and applying a metallization layer to the immersed nonwoven fabric. Attached Figure Description

[0009] Figure 1 This is a top view of a conductive nonwoven fabric according to an embodiment of the present disclosure;

[0010] Figure 2 Is it like this? Figure 1An enlarged sectional view of the AM section shown;

[0011] Figure 3A Is it like this? Figure 1 The enlarged view of the conductive nonwoven fabric shown is as follows: Figure 1 An enlarged view of the BM section shown;

[0012] Figure 3B Is it like this? Figure 1 The enlarged view of the conductive nonwoven fabric shown is as follows: Figure 1 An enlarged view of the partial configuration shown;

[0013] Figure 4 This is a top view showing a nonwoven fabric forming a conductive nonwoven fabric according to an embodiment of the present disclosure;

[0014] Figure 5 Is it like this? Figure 4 An enlarged sectional view of part A shown;

[0015] Figure 6A Is it like this? Figure 4 The enlarged view of the nonwoven fabric shown is as follows: Figure 4 An enlarged view of part B shown;

[0016] Figure 6B Is it like this? Figure 4 The enlarged view of the nonwoven fabric shown is as follows: Figure 6A An enlarged view of the partial configuration shown;

[0017] Figure 7A The photograph, taken by transmission electron microscopy (TEM), shows the conductive nonwoven fabric according to the embodiment, specifically showing the area near the surface of the first fiber of the metallized felt portion.

[0018] Figure 7B This is another photograph taken by transmission electron microscopy (TEM) showing the conductive nonwoven fabric according to the embodiment, specifically showing the area near the surface of the second fiber with metallized warp.

[0019] Figure 8A The photograph, taken by transmission electron microscopy (TEM), shows the conductive nonwoven fabric according to the embodiment, specifically showing the interior of the first fiber of the metallized felt portion;

[0020] Figure 8B This is another photograph taken by transmission electron microscopy (TEM) showing the conductive nonwoven fabric according to the embodiment, specifically showing the interior of the second fiber with metallized warp; and

[0021] Figure 9 This is a flowchart illustrating a method for manufacturing a conductive nonwoven fabric according to an embodiment. Detailed Implementation

[0022] In the following description, the present disclosure will be described with reference to preferred embodiments. It should be noted that the present disclosure is not limited to the embodiments described below, and appropriate modifications can be made without departing from the spirit of the present disclosure. Furthermore, in the embodiments described below, although some illustrations and descriptions of certain configurations have been omitted, it is not intended that the disclosed or known techniques be appropriately applied to the omission of technical details without contradicting the following content.

[0023] Figure 1 This is a top view showing a conductive nonwoven fabric according to an embodiment of the present disclosure. Figure 2 yes Figure 1 An enlarged cross-sectional view of the AM section shown. Figure 3A Is it like this? Figure 1 The enlarged view of the conductive nonwoven fabric shown is as follows: Figure 1 An enlarged view of the BM section shown. Figure 3B Is it like this? Figure 1 The enlarged view of the conductive nonwoven fabric shown is as follows: Figure 1 An enlarged view of the partial configuration shown. Figure 4 This is a top view showing a nonwoven fabric forming a conductive nonwoven fabric according to an embodiment of the present disclosure. Figure 5 yes Figure 4 An enlarged sectional view of part A shown. Figure 6A Is it like this? Figure 4 The enlarged view of the nonwoven fabric shown is as follows: Figure 4 An enlarged view of part B shown. Figure 6B This is a magnified view of a portion of the nonwoven fabric shown in Figure 6, specifically as follows: Figure 6A An enlarged view of the partial configuration shown.

[0024] Figure 1 The conductive nonwoven fabric shown is produced by applying conductive materials to the conductive nonwoven fabric. Figure 4 The nonwoven fabric 10 shown is coated with a metal layer M (see...) Figure 2 , 3A It was obtained by means of 3B) and includes a metallized felt portion 11M and multiple metallized warp threads 12M.

[0025] The metal-plated felt portion 11M includes the felt portion 11 (see Figure 4 ) and metal plating M (see Figure 2 ).like Figure 5 As shown, the felt portion 11 is formed of multiple first fibers F1, which extend in an irregular direction and are stacked along the thickness direction of the nonwoven fabric 10. The first fibers F1 are made of, for example, polyethylene terephthalate (PET), but are not limited to it, and can be made of polypropylene, nylon, acrylic, glass fiber, carbon fiber, aramid fiber, polyaramid ester fiber, etc.

[0026] By applying a metal coating M to multiple first fibers F1 forming the felt portion 11, a structure is formed as shown below. Figure 1 and Figure 2 The metal-plated felt portion 11M is shown.

[0027] Multiple metal-plated warp threads 12M consist of multiple warp threads 12 (see...) Figure 4 , 6A and 6B) and metal plating M (see Figure 3B (Formed.) For example... Figure 6A As shown, the warp threads 12 are formed to extend in a specific direction relative to the felt portion 11. Multiple warp threads 12 are formed such that the interval D between adjacent warp threads 12 (see...) Figure 4 For example, 2.5mm or less.

[0028] like Figure 6A and 6B As shown, each warp 12 is formed by multiple second fibers F2. The second fibers F2 are made of the same material as the first fibers F1. Furthermore, in... Figure 6A and 6B In the warp 12 shown, the density of the second fiber F2 is higher than that of the others. Figure 5 The density of the first fiber F1 is shown. That is, the density of the second fiber F2 is greater than that of the first fiber F1.

[0029] A metal plating layer M is applied to the second fiber F2 forming the warp 12, thereby forming a... Figure 1 , 3A The metal-plated warp 12M is shown in 3B.

[0030] Here, since the conductive nonwoven fabric 1 according to this embodiment includes multiple metal-plated warp threads 12M with high fiber density, the tensile strength in a specific direction (the direction in which the metal-plated warp threads 12M extend) is 0.5 MPa or more. Therefore, tensile strength comparable to that of ordinary adhesive tape is achieved.

[0031] The metal plating M is a conductive metal covering the first and second fibers F1 and F2 forming the nonwoven fabric 10, and is formed on the first and second fibers F1 and F2 by, for example, electroless plating using a chemical reaction. The metal plating M is made of one or more metals selected from copper, silver, gold, nickel, chromium, tin and zinc.

[0032] Furthermore, the conductive nonwoven fabric 1 has a metal catalyst for metallization (e.g., palladium and nickel) to deposit a metal coating M via a chemical reaction. The metal catalyst is attached to the nonwoven fabric 10 by immersing it in a supercritical or subcritical fluid (e.g., in supercritical carbon dioxide) containing an organometallic complex containing the metal catalyst.

[0033] Figure 7A The photograph, taken by transmission electron microscopy (TEM), shows the conductive nonwoven fabric 1 according to this embodiment, specifically showing the area near the surface of the first fiber F1 of the metallized felt portion 11M. Figure 7B This is another photograph taken by transmission electron microscopy (TEM) showing the conductive nonwoven fabric 1 according to this embodiment, specifically showing the area near the surface of the second fiber F2 with the metallized warp 12M. Figure 7A and 7B In the diagram, the white dots represent palladium, which is used as a catalyst metal for metal plating.

[0034] like Figure 7A As shown, palladium, a catalyst metal used for metallization, is scattered near the surface of the first fiber F1 forming the metallized felt portion 11M. Similarly, as... Figure 7B As shown, palladium, which is a catalyst metal for metallization, is scattered near the surface of the second fiber F2 that forms the metallization warp 12M.

[0035] Here, comparing the number of palladium grains, the number of palladium grains in the metallized warp 12M is greater than that in the metallized felt portion 11M. This is because the density of the multiple second fibers F2 forming the warp 12 is higher than the density of the multiple first fibers F1 forming the felt portion 11. In other words, when the nonwoven fabric 10 is immersed in a supercritical or subcritical fluid containing an organometallic complex of a catalyst metal for metallization, the fluid has difficulty passing between the second fibers F2 due to their high fiber density. As a result, a large amount of organometallic complex adheres to the second fibers F2.

[0036] Therefore, in the conductive nonwoven fabric 1 according to this embodiment, the metal plating layer M can be easily deposited on the warp 12 during an electroless plating process. Furthermore, by centering on the metal plating layer M deposited on the warp 12, the formation of the metal plating layer M around the periphery of the warp 12 on the felt portion 11 can be promoted.

[0037] In particular, when the spacing D between the warp threads 12 in the conductive nonwoven fabric 1 according to this embodiment is 2.5 mm or less, the space between the warp threads 12 (felt portion 11) can be easily filled with the metal plating layer M. That is, in the conductive nonwoven fabric 1 according to this embodiment, since the metal plating layer M is easily deposited on the warp threads 12 and their periphery, even on the felt portion 11 where the metal plating layer M is difficult to deposit, the metal plating layer M can be appropriately formed by reducing the spacing D between the warp threads 12 to a certain extent.

[0038] Figure 8A The photograph, taken by transmission electron microscopy (TEM), shows the conductive nonwoven fabric 1 according to this embodiment, specifically showing the internal portion of the first fiber F1 of the metallized felt portion 11M. Figure 8B This is another photograph taken by transmission electron microscopy (TEM) showing the conductive nonwoven fabric 1 according to this embodiment, specifically showing the internal portion of the second fiber F2 with metallized warp 12M. Furthermore, in Figure 8A and 8B In the diagram, the white dots represent palladium, which is used as a catalyst metal for metal plating.

[0039] like Figure 8A As shown, a large number of palladium grains, which serve as catalyst metals for metallization, are scattered within the first fiber F1 forming the metallized felt portion 11M, and their grain diameter is quite large. Conversely, as Figure 8B As shown, a large number of palladium grains, which serve as catalyst metals for metal plating, are scattered inside the second fiber F2, which forms the metal plating warp 12M. The grain diameter of the second fiber F2 is smaller than that of the first fiber F1.

[0040] Here, the smaller the grain diameter of the catalyst metal used for metal plating, the easier it is to deposit the metal plating layer M. Therefore, in the conductive nonwoven fabric 1 according to this embodiment, the crystallinity of the second fiber F2 is set to be higher than that of the first fiber F1, so that the metal plating layer M can be easily deposited on the warp 12.

[0041] Figure 9 This is a flowchart illustrating a method for manufacturing the conductive nonwoven fabric 1 according to this embodiment. First, as... Figure 9 As shown, the nonwoven fabric preparation process (S1) is performed. In the nonwoven fabric preparation process, as... Figure 4 As shown, a nonwoven fabric 10 is prepared in which multiple warp threads 12 are formed on a felt portion 11. In the nonwoven fabric 10, as described above, the fiber density of the warp threads 12 is higher than the fiber density of the felt portion 11, and the second fiber F2 forming the warp threads 12 has a higher degree of crystallinity than the first fiber F1 forming the felt portion 11.

[0042] Next, the soaking process (S2) is performed. In the soaking process, the nonwoven fabric 10 is placed in a treatment tank (not shown) and immersed in a supercritical or subcritical fluid (e.g., in supercritical carbon dioxide) containing an organometallic complex of a metallizing catalyst metal for metallization. Through this process, the organometallic complex of the metallizing catalyst metal for metallization adheres to the nonwoven fabric 10. In particular, in the nonwoven fabric 10 prepared in the nonwoven fabric preparation process of step S1, the warp yarns 12 have a very high fiber density, so a large amount of the organometallic complex of the metallizing catalyst metal for metallization adheres to the warp yarns 12. Furthermore, since the crystallinity of the second fiber F2 forming the warp yarns 12 is higher than that of the first fiber F1 forming the felt portion 11, only the organometallic complex of the metallizing catalyst metal for metallization with a smaller grain diameter enters the interior of the second fiber F2.

[0043] Subsequently, an electroless plating process (S3) is performed. In the electroless plating process, the reduced nonwoven fabric 10 is supplied to an electroless plating tank, and a metal coating M is deposited on the periphery of the metal plating catalyst metal using a chemical reaction. At this time, the warp yarns 12 of the nonwoven fabric 10 have a large amount of metal plating catalyst metal, and the metal plating catalyst metal with a smaller grain diameter penetrates into the interior of the warp yarns 12. Therefore, the metal coating M is advantageously deposited on the warp yarns 12. Furthermore, the metal coating M is also advantageously deposited on the felt portion 11 with the metal coating M deposited on the warp yarns 12 as the center. Thus, a conductive nonwoven fabric 1 according to this embodiment is obtained.

[0044] Thus, according to the conductive nonwoven fabric 1 and its manufacturing method in this embodiment, since the density of the second fiber F2 forming the warp 12 is higher than the density of the first fiber F1 forming the felt portion 11, a large amount of organometallic complex can be attached to the second fiber F2 by utilizing the fiber density. Therefore, the metal plating layer M can be advantageously deposited at least on the warp 12, and the formation of the metal plating layer M around the warp 12 can be promoted by centering on the metal plating layer M deposited on the warp 12. Therefore, metal deposition can be enhanced.

[0045] In addition, since the tensile strength in a specific direction is 0.5 MPa or above, it can ensure strength comparable to that of ordinary vinyl chloride tape.

[0046] Furthermore, since the interval between adjacent warp 12 of the multiple warp 12 is 2.5 mm or less, it is easy to form a metal plating M between the warp 12 with the metal plating M formed on the warp 12 as the center.

[0047] Furthermore, since the metallized warp 12M is formed by the second fiber F2, which has a higher crystallinity than the first fiber F1 that forms the metallized felt portion 11M, for example, when the nonwoven fabric 10 is immersed in a supercritical or subcritical fluid containing an organometallic complex, only the organometallic complex with a small grain diameter enters the interior portion of the second fiber F2, which helps to improve the metallization deposition.

[0048] Although this disclosure has been described based on the above embodiments, this disclosure is not limited to the above embodiments, and modifications can be made without departing from the spirit of this disclosure, and known or publicly known techniques can be appropriately combined.

[0049] For example, in the above embodiments, the metal-plated warp yarn 12M (warp yarn 12) extends from one end to the other in a specific direction without being interrupted in the middle of the conductive nonwoven fabric 1 (nonwoven fabric 10), and this disclosure is not particularly limited in this respect. Optionally, the metal-plated warp yarn 12M may be interrupted in the middle. Furthermore, in the above embodiments, the conductive nonwoven fabric 1 (nonwoven fabric 10) includes multiple metal-plated warp yarns 12M (warp yarns 12), and this disclosure is not particularly limited thereto. Optionally, the conductive nonwoven fabric 1 may include only one warp yarn 12M.

[0050] In the above embodiments, the first fiber F1 and the second fiber F2 are both made of the same material, but this disclosure is not limited thereto. Optionally, the first fiber F1 and the second fiber F2 may be made of different materials. Furthermore, in the conductive nonwoven fabric 1 according to this embodiment, the crystallinity of the second fiber F2 is higher than that of the first fiber F1, and this disclosure is not particularly limited thereto. As long as there are no problems with the deposition of the metal plating M, the crystallinity of fibers F1 and F2 may be equal, or the crystallinity of the second fiber F2 may be lower than that of the first fiber F1.

[0051] According to a first aspect of this disclosure, the conductive nonwoven fabric (1) includes: a metallized felt portion (11M) comprising a felt portion (11) formed of a plurality of first fibers (F1) extending and stacked in an irregular direction, and a metallization (M) applied to the first fibers (F1) of the felt portion (11); and at least one metallized warp (12M) comprising a warp (12) formed of a plurality of second fibers (F2) and a metallization (M) applied to the second fibers (F2) of the warp (12). The at least one metallized warp (12M) is formed to extend in a particular direction relative to the metallized felt portion (11M), and the density of the second fibers (F2) is higher than the density of the first fibers (F1).

[0052] According to a second aspect of this disclosure, the conductive nonwoven fabric (1) may have a tensile strength of 0.5 MPa or above in a particular direction.

[0053] According to a third aspect of this disclosure, the meridian (12) may include a plurality of meridians (12), and the interval (D) between adjacent meridians of the plurality of meridians (12) may be 2.5 mm or less.

[0054] According to a fourth aspect of this disclosure, the second fiber (F2) of the warp (12) may have a higher degree of crystallinity than the first fiber (F1) of the felt portion (11).

[0055] According to a fifth aspect of this disclosure, a method for manufacturing a conductive nonwoven fabric (1) includes: preparing a nonwoven fabric (10) comprising: a felt portion (11) wherein a plurality of first fibers (F1) extending in an irregular direction are stacked; and at least one warp (12) formed of a plurality of second fibers (F2) and extending in a specific direction relative to the felt portion (11), the density of the second fibers (F2) being higher than the density of the first fibers (F1); placing the nonwoven fabric (10) into a treatment tank to immerse the nonwoven fabric (10) in a supercritical or subcritical fluid containing an organometallic complex of a catalyst metal for metallization; and applying a metallization layer (M) to the immersed nonwoven fabric (10).

[0056] According to this disclosure, a conductive nonwoven fabric and a method for manufacturing a conductive nonwoven fabric capable of enhancing metal deposition can be provided.

Claims

1. An electroconductive nonwoven fabric comprising: a metal-plated felt portion including a felt portion formed of a plurality of first fibers extending in an irregular direction and stacked, and a metal plating layer applied to the first fibers of the felt portion; and at least one metal-plated warp yarn including a warp yarn formed of a plurality of second fibers and a metal plating layer applied to the second fibers of the warp yarn, wherein the at least one metal-plated warp yarn is formed to extend in a specific direction with respect to the metal-plated felt portion, and a gap between the second fibers constituting the warp yarn is smaller than a gap between the first fibers constituting the felt portion; wherein the warp yarn includes a plurality of warp yarns, and a spacing between adjacent warp yarns of the plurality of warp yarns is 2.5 mm or less.

2. The electroconductive nonwoven fabric according to claim 1, wherein a tensile strength of the electroconductive nonwoven fabric in a specific direction is 0.5 MPa or more.

3. The electroconductive nonwoven fabric according to claim 1 or 2, wherein a crystallinity of the second fibers of the warp yarn is higher than that of the first fibers of the felt portion.

4. A method for manufacturing an electroconductive nonwoven fabric, the method comprising: preparing a nonwoven fabric including a felt portion in which a plurality of first fibers extending in an irregular direction are stacked, and at least one warp yarn formed of a plurality of second fibers and extending in a specific direction with respect to the felt portion, a gap between the second fibers constituting the warp yarn being smaller than a gap between the first fibers constituting the felt portion, wherein the warp yarn includes a plurality of warp yarns, and a spacing between adjacent warp yarns of the plurality of warp yarns is 2.5 mm or less; immersing the nonwoven fabric in a supercritical fluid or a subcritical fluid containing an organometallic complex of a catalyst metal for metal plating, by placing the nonwoven fabric in a treatment tank; and applying a metal plating layer to the immersed nonwoven fabric. ​

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