JP2021088779A - Conductive fiber, coaxial cable and method for producing conductive fiber - Google Patents

Abstract

To provide a conductive fiber that has a plating layer covering a fiber bundle containing a plurality of resin wires, for example, the conductive fiber constituting a shield covering the side of a coaxial cable, the conductive fiber capable of achieving both of electric characteristics and durability.SOLUTION: A conductive fiber 10 has a fiber bundle 13b containing a first resin wire 11 and a second resin wire 12b, and a plating layer 14 covering the fiber bundle 13b. The second resin wire 12b is thinner than the first resin wire 11, and the plating layer 14 also exists in the interior 15 of the fiber bundle 13b.SELECTED DRAWING: Figure 1

Description

The present invention relates to conductive fibers, coaxial cables and methods for producing conductive fibers.

The conductive fiber has, for example, a fiber bundle made of resin wire and a plating layer that covers the fiber bundle.

As an example of such conductive fibers, Patent Document 1 describes metal-plated fibers in which the surface of organic fibers in which thermoplastic polyvinyl alcohol is present at least a part of the fiber surface is metal-plated. ing.

Japanese Unexamined Patent Publication No. 2008-38294

Details will be described later, but like the conductive fibers described in Patent Document 1, the presence of polyvinyl alcohol on at least a part of the fiber surface enables a good metal plating process without performing an etching process or the like. Furthermore, by being composed of ultrafine fibers, it is possible to provide metal-plated fibers having good electrical characteristics such as conductive performance, excellent flexibility, and excellent durability such as bending resistance. Become.

However, the present inventors have confirmed that it is difficult to achieve both electrical properties and durability in conductive fibers. Further, since conductive fibers are suitably used as conductors (particularly external conductors) of coaxial cables, coaxial cables using conductive fibers that can achieve both electrical characteristics and durability are also desired.

The present invention has been made in view of such problems, and an object of the present invention is to provide a conductive fiber capable of achieving both electrical characteristics and durability, and a coaxial cable using the conductive fiber.

A brief description of typical inventions disclosed in the present application is as follows.

[1] The conductive fiber has a fiber bundle containing the first resin wire and the second resin wire, and a plating layer for coating the fiber bundle, and the second resin wire is obtained from the first resin wire. The plating layer is also thin, and is also present inside the fiber bundle.

[2] In the conductive fiber according to [1], the first resin wire and the second resin wire are each composed of different resin compositions.

[3] In the conductive fibers according to [1] or [2], the second resin wire is arranged on the outer peripheral portion of the fiber bundle in a cross-sectional view more than the first resin wire.

[4] In the conductive fiber according to any one of [1] to [3], the fiber bundle is a stranded wire of the first resin wire and the second resin wire.

[5] A coaxial cable including the conductive fiber according to any one of [1] to [4], wherein the first conductor, the first insulating layer coated around the first conductor, and the like. It has a second conductor arranged around the first insulating layer and a second insulating layer coated around the second conductor, and the second conductor has the conductive fibers as the first one. It is a horizontal winding shield spirally wound around an insulating layer, or a braided shield in which the conductive fibers are braided.

[6] The method for producing conductive fibers includes (a) a step of twisting a first resin wire and a second resin wire to form a fiber bundle, and (b) after the step (a), the second resin. The step of thinning the wire includes (c) a step of coating the fiber bundle with a plating layer at the same time as the step (b) or after the step (b).

[7] In the method for producing conductive fibers according to [6], the second resin wire is more soluble in the first solution than the first resin wire, and in the step (b), the second resin wire is dissolved in the first solution. Immerse the fiber bundle.

[8] In the method for producing conductive fibers according to [7], the first solution is a basic electroless plating solution, and the steps (b) and (c) are performed at the same time.

[9] In the method for producing conductive fibers according to [7], the first solution is an acidic solution containing a plating catalyst, and the plating catalyst is attached to the fiber bundle at the same time as the step (b). The step (c) is performed after the step (b).

According to the present invention, it is possible to provide conductive fibers having both electrical characteristics and durability.

It is a cross-sectional view which shows the structure of the conductive fiber which concerns on 1st Embodiment. It is sectional drawing which shows the structure of the coaxial cable which concerns on 1st Embodiment. It is a side view which shows the structure of the coaxial cable which concerns on 1st Embodiment. It is a flow which shows the manufacturing process of the conductive fiber which concerns on 1st Embodiment. It is a cross-sectional view which shows the manufacturing process of the conductive fiber which concerns on 1st Embodiment. It is a cross-sectional view which shows the manufacturing process of the conductive fiber following FIG. It is a cross-sectional view which shows the structure of the conductive fiber which concerns on the modification of 1st Embodiment. It is a schematic diagram which shows the plating processing system used in the manufacturing process of the conductive fiber which concerns on 1st Embodiment. It is a cross-sectional view which shows the structure of the conductive fiber which concerns on study example.

(Consideration)
Before explaining the embodiment, the matters examined by the present inventors will be described.

FIG. 9 is a cross-sectional view showing the structure of the conductive fiber according to the study example. As shown in FIG. 9, the conductive fiber 90 according to the study example has a fiber bundle 93 formed of a resin wire 91 and a plating layer 94 covering the fiber bundle 93. The resin wire 91 is a resin formed in a single thread shape (circular cross section), and is also called a monofilament. The fiber bundle 93 is formed by twisting a plurality of resin wires 91 into a stranded wire, and is also called a multifilament.

The present inventors have confirmed that it is difficult to achieve both electrical characteristics and durability in the conductive fiber 90 according to such a study example, as described below.

Generally, the method for producing conductive fibers 90 includes a step of forming a plating layer 94 so as to cover the fiber bundle 93. This step is a step of immersing the fiber bundle 93 in the plating solution (aqueous solution). Further, the method for producing the conductive fiber 90 more preferably includes a step of adhering a plating catalyst to the surface of the resin wire 91 before the step of forming the plating layer 94 so as to cover the fiber bundle 93. ing. This step is a step of immersing the resin wire 91 in a solution (aqueous solution) containing a plating catalyst.

Here, in the fiber bundle 93 according to the study example, since a plurality of resin wires 91 having a circular cross section are assembled, there is a gap inside the fiber bundle 93, but the resin wire 91 has no gap around the gap. Surrounding. Further, since the material constituting the resin wire 91 is generally a hydrophobic resin material, the surface of the resin wire 91 has low wettability. Therefore, in the study example, it is difficult for the solution containing the plating catalyst and each aqueous solution such as the plating solution to enter the inside 95 of the fiber bundle 93.

Therefore, in the study example, the plating catalyst is unlikely to adhere to the surface of the resin wire 91 existing inside 95 of the fiber bundle 93. As a result, it becomes difficult for the plating layer to be formed in the voids existing in the inner 95 of the fiber bundle 93. From the above, it is difficult to improve the electrical characteristics (particularly conductivity) of the conductive fiber 90 according to the study example.

Here, the present inventors have studied to reduce the diameter of the resin wire 91. If the diameter of the resin wire 91 is reduced, the solution containing the plating catalyst and the aqueous solutions of the plating solution can easily enter the inner 95 of the fiber bundle 93, and the plating layer can be easily formed inside the fiber bundle 93. Because it becomes. However, if the diameter of the resin wire 91 is reduced, the fiber bundle 93 (resin wire 91) may be broken when the plating layer 94 is formed, which in turn leads to a decrease in the durability of the conductive fiber 90.

On the other hand, if the diameter of the resin wire 91 is increased, the possibility that the resin wire 91 (fiber bundle 93) is broken when the plating layer 94 is formed decreases, but as described above, the voids existing inside the fiber bundle 93 are 95. It becomes difficult for the plating layer to be formed on the surface, and the electrical characteristics (conductivity) of the conductive fiber 90 deteriorates.

From the above, it is desired to improve the electrical characteristics of conductive fibers while suppressing the decrease in durability.

(Embodiment)
<Main composition and effect of conductive fibers according to the first embodiment>
Hereinafter, the conductive fibers according to the first embodiment will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing the structure of conductive fibers according to the first embodiment.

As shown in FIG. 1, the conductive fiber 10 according to the first embodiment includes a fiber bundle 13b including the first resin wire 11 and the second resin wire 12b, and a plating layer 14 covering the fiber bundle 13b. However, the second resin wire 12b is thinner than the first resin wire 11, and the plating layer 14 is also present inside the fiber bundle 13b.

In the first embodiment, by adopting the above configuration, it is possible to provide conductive fibers capable of achieving both electrical characteristics and durability. The reason for this will be described in detail below.

As described above, in the conductive fiber 90 according to the study example shown in FIG. 9, when the electrical characteristics (conductivity) are improved by reducing the diameter of the resin wire 91, the durability of the conductive fiber 90 is improved. It will drop. Further, if the durability is improved by increasing the diameter of the resin wire 91, the plating layer 94 is not formed in the voids inside 95 of the fiber bundle 93, and the electrical characteristics are deteriorated.

In this regard, in the conductive fiber 10 according to the first embodiment shown in FIG. 1, the second resin wire 12b (diameter d12b) is thinner than the first resin wire 11 (diameter d11) (d12b <d11). The plating layer 14 is also present inside the fiber bundle 13b. By making the second resin wire 12b thinner than the first resin wire 11 in this way, a solution containing a plating catalyst and each aqueous solution such as a plating solution can easily enter the inside 15 of the fiber bundle 13b.

Therefore, in the first embodiment, the plating catalyst easily adheres to the surfaces of the first resin wire 11 and the second resin wire 12b existing inside the fiber bundle 13b. As a result, the plating layer 14 is likely to be formed in the voids existing inside the fiber bundle 13b. From the above, the conductive fiber 10 according to the first embodiment can improve the electrical characteristics (conductivity) as compared with the conductive fiber 90 according to the above-mentioned study example shown in FIG. 9 (hereinafter,). , The second resin wire may be called a reduced diameter resin wire). Further, as shown in FIG. 1, since the fiber bundle 13b contains the first resin wire 11 which is thicker than the second resin wire 12b, the possibility that the fiber bundle 13b breaks when the plating layer 14 is formed is reduced. Therefore, the durability can be improved as compared with the conductive fiber 90 according to the above-mentioned study example shown in FIG. 9 (hereinafter, the first resin wire may be referred to as a supporting resin wire).

From the above, in the conductive fiber 10 according to the first embodiment shown in FIG. 1, it is possible to improve the electrical characteristics while suppressing the decrease in durability.

Further, the conductive fiber 10 according to the first embodiment is preferably composed of different resin compositions for the first resin wire 11 and the second resin wire 12b. By doing so, the reaction of the first resin wire 11 and the second resin wire 12b to the treatment in the liquid phase or the gas phase is different. The merits of such a configuration will be described in detail below.

As shown in FIGS. 4 and 5 described later, it is preferable that the second resin wire 12b is formed by reducing the diameter of the second resin wire 12a before the treatment by the resin wire diameter reduction step S12. Therefore, for example, the second resin wire 12b (second resin wire 12a) is composed of a resin composition that is more soluble in the diameter-reducing treatment solution (first solution) than the resin composition constituting the first resin wire 11. .. By doing so, of the fiber bundle 13a before the treatment, only the second resin wire 12a can be dissolved by the diameter reduction treatment solution (first solution) to reduce the diameter.

Further, the conductive fiber 10 according to the first embodiment is preferably a stranded wire of the first resin wire 11 and the second resin wire 12b in the fiber bundle 13b. In this way, even when the fiber bundle 13b is configured as a stranded wire, the plating layer 14 is formed in the voids generated in the stranded wire so that the plating layer 14 exists inside the fiber bundle 13b. (The same applies to the modified example of the first embodiment described later).

The diameter of the first resin wire (supporting resin wire) before forming the plating layer is 10 to 20 μm, the diameter of the second resin wire before forming the plating layer and before reducing the diameter is 10 to 20 μm, before forming the plating layer and thin. The diameter of the second resin wire after diameterening is 5 to 10 μm, the diameter of the fiber bundle before forming the plating layer is 0.04 to 0.19 mm, and the completed conductive fiber (diameter of the fiber bundle after forming the plating layer). ) Is 0.05 to 0.2 mm. Further, the plating layer can be made of, for example, tin, nickel, zinc, copper, silver, gold or the like. Examples of raw materials for the first resin wire (supporting resin wire) and the second resin wire (reduced diameter resin wire) will be described in the item of the method for producing conductive fibers according to the first embodiment.

<Coaxial cable according to the first embodiment>
Hereinafter, the coaxial cable according to the first embodiment will be described with reference to the drawings. FIG. 2 is a cross-sectional view showing the structure of the coaxial cable according to the first embodiment. FIG. 3 is a side view showing the structure of the coaxial cable according to the first embodiment.

As shown in FIGS. 2 and 3, the coaxial cable 100 according to the first embodiment includes a first conductor (inner conductor) 110, a first insulating layer 120 coated around the first conductor 110, and a first conductor. It has a second conductor (outer conductor) 130 arranged around the insulating layer 120, and a second insulating layer 140 coated around the second conductor 130.

Here, in the coaxial cable 100 according to the first embodiment, the second conductor 130 is a horizontal winding shield in which the conductive fibers 10 according to the first embodiment are spirally wound around the first insulating layer 120, or It is a braided shield in which the conductive fibers 10 according to the first embodiment are braided. As described above, by adopting the conductive fiber 10 according to the first embodiment described above as the second conductor (outer conductor) 130 of the coaxial cable, the second conductor (outer conductor) having excellent electrical characteristics and durability can be obtained. A coaxial cable can be provided.

As the conducting wire 11a constituting the first conductor 110 shown in FIG. 2, a commonly used metal wire, for example, a copper wire, a copper alloy wire, an aluminum wire, a gold wire, a silver wire, or the like can be used. Further, as the conducting wire 11a, one having metal plating such as tin or nickel around the metal wire may be used. As the first conductor 110, a (aggregate) twisted conductor in which metal wires are twisted can also be used. The cross-sectional area and outer diameter of the first conductor 110 are not particularly limited, and can be appropriately changed according to the electrical characteristics required for the coaxial cable 100.

As the resin composition constituting the first insulating layer 120 shown in FIGS. 2 and 3, high-density polyethylene, low-density polyethylene, fluororesin, polyvinyl chloride, synthetic rubber and the like can be used. As the resin composition constituting the second insulating layer 140, silicone resin, polyvinyl chloride, chloroprene rubber, high-density polyethylene, low-density polyethylene, polyurethane and the like can be used.

In the coaxial cable 100 according to the first embodiment, the conductive fibers 20 according to the modification described later may be adopted instead of the conductive fibers 10 constituting the second conductor 130 (not shown). Further, although not shown, the first insulating layer 120 may have a two-layer structure of a foam layer having holes and a protective layer (skin layer) arranged around the foam layer.

<Method for manufacturing conductive fibers according to the first embodiment>
The conductive fiber 10 according to the first embodiment shown in FIG. 1 is manufactured as follows, for example. Hereinafter, the method for producing conductive fibers according to the first embodiment will be described. FIG. 4 is a flow showing a manufacturing process of conductive fibers according to the first embodiment. FIG. 5 is a cross-sectional view showing a manufacturing process of conductive fibers according to the first embodiment. FIG. 6 is a cross-sectional view showing a manufacturing process of conductive fibers following FIG.

The method for producing a conductive fiber according to the first embodiment is as follows: (a) a step of twisting a first resin wire and a second resin wire to form a fiber bundle (fiber bundle forming step S11 shown in FIG. 4), ( b) After the step (a), a step of thinning the second resin wire (resin wire diameter reduction step S12 shown in FIG. 4), and (c) a step of coating the fiber bundle with a plating layer (in FIG. 4). The plating layer forming step S13), which is shown, is included. Hereinafter, each step will be specifically described.

In the fiber bundle forming step S11 shown in FIG. 4, as shown in FIG. 5, the first resin wire 11 and the second resin wire 12a before the diameter is reduced (hereinafter, simply referred to as the second resin wire 12a) are twisted. Together, they form a fiber bundle 13a.

Subsequently, in the resin wire diameter reduction step S12 shown in FIG. 4, as shown in FIG. 5, the second resin wire 12a (diameter d12a) is thinned to form the second resin wire 12b (diameter d12b). At this time, the voids inside 15 of the fiber bundle 13b are expanded.

Subsequently, in the plating layer forming step S13 shown in FIG. 4, the fiber bundle 13b is coated with the plating layer 14 as shown in FIG. At this time, the plating layer 14 is formed not only around the fiber bundle 13b but also to fill the voids inside the fiber bundle 13b.

According to the method for producing conductive fibers according to the first embodiment described above, as shown in FIG. 5, a part of the resin wire (second resin wire) contained in the fiber bundle is thinned to make the fiber bundle thin. The voids 15 inside 13b are expanded. As a result, the solution containing the plating catalyst and the aqueous solutions of the plating solution can easily enter the inside 15 of the fiber bundle 13b. Therefore, in the first embodiment, the plating catalyst easily adheres to the surfaces of the first resin wire 11 and the second resin wire 12b existing inside the fiber bundle 13b. As a result, as shown in FIG. 6, the plating layer 14 can be formed not only around the fiber bundle 13b but also inside 15 of the fiber bundle 13b. The conductive fiber 10 shown in FIG. 1 manufactured in this way can improve the electrical characteristics (conductivity) as compared with the conductive fiber 90 according to the study example shown in FIG. Further, according to the method for producing conductive fibers according to the first embodiment, as shown in FIG. 5, it is possible to leave the first resin wire 11 which is not reduced in diameter (hard to be reduced in diameter) in the fiber bundle 13b. Therefore, the possibility that the fiber bundle 13b breaks when the plating layer 14 shown in FIG. 6 is formed can be reduced. The conductive fibers 10 shown in FIG. 1 manufactured in this way can improve durability as compared with the conductive fibers 90 according to the study example shown in FIG.

From the above, according to the method for producing conductive fibers according to the first embodiment, it is possible to improve the electrical characteristics of the conductive fibers 10 while suppressing the decrease in durability.

In addition, unlike the first embodiment, a method in which the first resin wire 11 and the second resin wire 12b having a reduced diameter in advance are prepared and twisted to form a fiber bundle can be considered. However, in this method, when the resin wires are twisted to form a fiber bundle, the resin wires are in close contact with each other, and the void inside the fiber bundle cannot be expanded. In this respect, in the method for producing conductive fibers according to the first embodiment, the resin wires are twisted to form a fiber bundle, and then a part of the resin wires is reduced in diameter. By doing so, the voids inside the fiber bundle 13b can be reliably expanded. That is, in the method for producing conductive fibers according to the first embodiment, it is essential that the resin wire diameter reduction step S12 shown in FIG. 4 is performed after the fiber bundle forming step S11.

From this point of view, in the method for producing a conductive fiber according to the first embodiment, the diameter d12a of the second resin wire 12a before the diameter reduction is related to the diameter d11 of the first resin wire 11. For example, the diameter d12a of the second resin wire 12a before the diameter reduction is larger (thicker) than the diameter d11 of the first resin wire 11, and the diameter d12b of the second resin wire 12b after the diameter reduction is the first resin. It may be substantially the same as the diameter d11 of the wire 11. Even in this case, the voids of the fiber bundle are expanded by the amount that the diameter of the second resin wire is reduced after the fiber bundle is formed. However, as shown in FIG. 1, when the diameter d12b of the second resin wire 12b after the reduction in diameter is smaller (thinner) than the diameter d11 of the first resin wire 11, the inner 15 of the fiber bundle 13b is used for plating. Since the solution containing the catalyst and each aqueous solution of the plating solution can easily enter, the diameter d12b of the second resin wire 12b after the diameter reduction is the diameter d11 of the first resin wire 11 from the viewpoint of improving the electrical characteristics. Smaller (thinner) is more advantageous than. On the other hand, if the diameter d12b of the second resin wire 12b after the diameter reduction is substantially the same as the diameter d11 of the first resin wire 11, the fiber bundle 13b may break when the plating layer 14 shown in FIG. 6 is formed. From the viewpoint of improving durability, it is advantageous that the diameter d12b of the second resin wire 12b after the diameter reduction is substantially the same as the diameter d11 of the first resin wire 11. is there.

Further, as a preferred embodiment of the method for producing conductive fibers according to the first embodiment, the second resin wire 12a is more soluble in the first solution than the first resin wire 11, and the step (b) (FIG. 4). In the resin wire diameter reduction step S12) shown, the fiber bundle 13a is immersed in the first solution. In this way, by forming the fiber bundle with a resin wire (second resin wire) that is easily soluble in a certain solution and a resin wire (first resin wire) that is difficult to dissolve in a certain solution, it is easy to immerse the fiber bundle in the solution. It is possible to reduce the diameter of only one of the resin wires by various methods. A specific mode when this form is adopted will be described later.

<Conductive fiber according to the modified example of the first embodiment>
Hereinafter, the configuration of the conductive fibers according to the modified example of the first embodiment will be described. In the description of the modified example, the same or similar parts or components as the conductive fiber according to the first embodiment are indicated by the same or similar symbols or reference numbers, and the description will not be repeated in principle and will be omitted.

FIG. 7 is a cross-sectional view showing the structure of the conductive fiber according to the modified example. As shown in FIG. 7, the conductive fiber 20 according to the modified example has a fiber bundle 23b composed of the first resin wire 11 and the second resin wire 12b, and a plating layer 14 covering the fiber bundle 23b. However, the plating layer 14 also exists inside the fiber bundle 23b, and is basically configured in the same manner as the conductive fibers 10 according to the first embodiment shown in FIG. However, as shown in FIG. 7, in the modified example, in the cross-sectional view, the second resin wire 12b is arranged more than the first resin wire 11 on the outer peripheral portion of the fiber bundle 23b. It is different from the form. Here, the outer peripheral portion of the fiber bundle 23b means a region including the outer peripheral surface of the fiber bundle 23b.

As described above, in the conductive fiber 20 according to the modified example, since many second resin wires 12b thinner than the first resin wire 11 are arranged on the outer peripheral portion of the fiber bundle 23b, the inside of the fiber bundle 23b 25, a solution containing a plating catalyst and each aqueous solution such as a plating solution can easily enter the 25 as compared with the first embodiment. Therefore, in the modified example, the plating layer 14 is more likely to be formed in the voids existing in the inner 25 of the fiber bundle 23b as compared with the first embodiment. From the above, the conductive fiber 20 according to the modified example is more advantageous than the conductive fiber 10 according to the first embodiment shown in FIG. 1 in terms of electrical characteristics.

On the other hand, in the conductive fiber 10 according to the first embodiment, in the outer peripheral portion of the fiber bundle 13b, the number of the first resin wire 11 thicker than the second resin wire 12b is the same as or larger than that of the second resin wire 12b. Since many of the fibers are arranged, the possibility that the fiber bundle 13b will break when the plating layer 14 is formed can be reduced as compared with the modified example. From the above, the conductive fiber 10 according to the first embodiment is more advantageous in terms of durability than the conductive fiber 20 according to the modified example shown in FIG. 7.

<Specific Aspects of the First Embodiment>
Hereinafter, specific embodiments of the first embodiment will be described. Here, the details of the method for producing conductive fibers according to the first embodiment described above will be described, and a specific embodiment when the first embodiment is applied will be described.

First, details of the method for producing conductive fibers according to the first embodiment will be described. FIG. 8 is a schematic view showing a plating treatment system used in the manufacturing process of conductive fibers according to the first embodiment. The plating treatment system 200 according to the first embodiment includes a degreasing unit 210, a surface treatment unit 220, a first activation unit 230, a second activation unit 240, an electroless plating unit 250, and a cleaning unit 260. The electroplating unit 270, the cleaning unit 270, and the bobbins 280a to 280q for transferring the fiber bundle 13a are provided.

In the plating treatment system 200 according to the first embodiment, the bobbins 280a to 280q are continuously operated at a desired rotation speed to transfer the fiber bundle 13a at a desired speed while maintaining a constant tension. In the plating treatment system 200 according to the first embodiment, among the methods for producing conductive fibers according to the first embodiment, the resin wire diameter reduction step S12 and the plating layer forming step S13 shown in FIG. 4 are performed. That is, while the fiber bundle 13a shown in FIG. 5 passes through the plating treatment system 200 shown in FIG. 8, the second resin wire 12a included in the fiber bundle 13a is reduced in diameter to become the second resin wire 12b, and the fiber bundle 13a is formed. Is a fiber bundle 13b including the second resin wire 12b, and as shown in FIG. 6, the fiber bundle 13b is coated with the plating layer 14 to obtain the conductive fiber 10.

The degreasing unit 210 is for removing oils and fats on the surface of the fiber bundle, and includes a degreasing tank 211 and a degreasing liquid 212 housed in the degreasing tank 211. The degreasing liquid 212 contains, for example, sodium borate, sodium phosphate, a surfactant and the like. Since the fiber bundle 13a is transferred and passed through the degreasing liquid 212, at least a part of the bobbin 280b is located in the degreasing liquid 212.

The surface treatment unit 220 is for applying a surface treatment to the fiber bundle, and includes a surface treatment device 221. The surface treatment device 221 includes, for example, an etching using a blasting device (dry ice as a propellant) for roughening treatment, a laser device, a chromic acid or sulfuric acid, a sodium naphthalene solution, an ozone-containing solution, or the like as an etchant. An apparatus, a corona processing apparatus for performing hydrophilization treatment, a plasma processing apparatus, an ultraviolet irradiation apparatus, an electron beam irradiation apparatus, a γ-ray irradiation apparatus, an X-ray irradiation apparatus, an ion beam irradiation apparatus and the like are used.

When both the roughening treatment and the hydrophilic treatment are performed as surface treatments, or when a plurality of treatments are performed as roughening treatments or hydrophilic treatments, a plurality of types of surface treatment devices 221 are included in the surface treatment unit 220. May be.

The first activation unit 230 is for forming a catalytically active layer (not shown) on the surface of the fiber bundle, and is housed in the first activation tank 231 and the first activation tank 231. It is provided with an activating solution 232. The first activation liquid 232 contains, for example, palladium chloride, tin (II) chloride, concentrated hydrochloric acid, and the like, and is adjusted so that the pH is less than 1. The catalytically active layer is for forming a dense, high-quality plating layer. Since the fiber bundles 13a (13b) are transferred and passed through the first activating liquid 232, at least a part of the bobbin 280f is located in the first activating liquid 232.

The second activation unit 240 is for cleaning the surface of the catalytically active layer formed by the first activation unit 230, and is housed in the second activation tank 241 and the second activation tank 241. It also includes a second activating solution 242. The second activation liquid 242 is, for example, sulfuric acid. Since the fiber bundles 13a (13b) are transferred and passed through the second activating liquid 242, at least a part of the bobbin 280h is located in the second activating liquid 242.

The electroless plating unit 250 is for forming an electroless plating layer on the surface of the fiber bundle to make the surface of the fiber bundle (the surface of the catalytically active layer) conductive before the electroless plating treatment, and electroless plating. A tank 251 and an electroless plating solution 252 housed in the electroless plating tank 251 are provided. The electroless plating solution contains, for example, copper (II) sulfate, sodium potassium tartrate (Rochelle salt), sodium hydroxide, potassium hydroxide, ammonium hydroxide (water ammonia), etc., so that the pH is 12 to 13. It has been adjusted. Since the fiber bundles 13a (13b) are transferred and passed through the electroless plating solution 252, at least a part of the bobbin 280j is located in the electroless plating solution 252.

The cleaning unit 260 is for cleaning the surface of the electroless plating layer formed by the electroless plating unit 250, and includes a cleaning tank 261 and a cleaning liquid 262 housed in the cleaning tank 261. The cleaning liquid 262 is, for example, pure water. Since the fiber bundle 13b is transferred and passed through the cleaning liquid 262, at least a part of the bobbin 280 m is located in the cleaning liquid 262.

The electroplating unit 270 is for performing an electroplating process, and includes an electroplating tank 271, an electrolytic plating solution 272 contained in the electroplating tank 271, a pair of electrodes 273, and a power supply unit 274. The electrolytic plating solution 272 is, for example, a copper sulfate plating solution, a copper cyanide plating solution, a borofluoride plating solution, a pyrophosphate plating solution, or the like, and among these plating solutions, two or more kinds of plating solutions are combined. It may be a plating solution. The pair of electrodes 273 are immersed in the electrolytic plating solution 272 and act as an anode. The pair of electrodes 273 are, for example, blister copper having a purity of about 99%, and are a source of copper ions in electrolytic plating. The bobbins 280n and 280q located above the electrolytic plating tank 271 have conductivity and act as a cathode. The bobbin 280p located in the electrolytic plating solution 272 is insulating. The power supply unit 274 applies a DC voltage between the pair of electrodes 273, which are anodes, and the bobbins 280n, 280q, which are cathodes. With a DC voltage applied between the pair of electrodes 273 and the bobbins 280n and 280q, the fiber bundle 13b is transferred and passed through the electrolytic plating solution 272 on the electroless plating layer on the surface of the fiber bundle 13b. An electrolytic plating layer is formed on the surface, and a fiber bundle 13b on which the plating layer 14 composed of these is formed, that is, a conductive fiber 10 is obtained.

<< Specific Aspect 1 >>
Hereinafter, two preferable specific embodiments will be exemplified in the method for producing conductive fibers according to the first embodiment. First, as a specific embodiment 1, a case where the resin wire diameter reduction step S12 shown in FIG. 4 is performed by the electroless plating unit 250 (shown by * 1 in the figure) shown in FIG. 8 will be described. That is, in the method for producing conductive fibers according to the specific aspect 1, the first solution is a basic electroless plating solution, and the step (b) (resin wire diameter reduction step S12 shown in FIG. 4). And the step (c) (plating layer forming step S13 shown in FIG. 4) are performed at the same time. In this way, by forming the fiber bundle with a resin wire (second resin wire) that is easily dissolved in a basic solution and a resin wire (first resin wire) that is difficult to dissolve, the fiber bundle 13a before the diameter reduction can be obtained. When immersed in a basic electroless plating solution (for example, pH 12 to 13), the diameter of the second resin wire 12a is reduced, and at the same time, the formation of the plating layer 14 proceeds. As a result, in the first embodiment, the process can be further simplified and the manufacturing cost can be reduced.

As described above, when the fiber bundle is composed of a resin wire (second resin wire) that is easily dissolved in a basic solution and a resin wire (first resin wire) that is difficult to dissolve in a basic solution, the first resin wire (supporting resin wire) is used. ) And the specific examples of the raw materials of the second resin wire (reduced diameter resin wire) are summarized in Table 1. The first resin wire may be a combination of resin wires that are difficult to dissolve in a basic solution. Similarly, the second resin wire may be a combination of resin wires that are easily soluble in a basic solution.

In the specific embodiment 1, the compound containing the constituent elements of the second resin wire is dissolved or precipitated in the electroless plating solution 262 shown in FIG. 8 through the resin wire diameter reduction step S12, or FIG. The plating layer 14 shown in 1 contains a compound containing a constituent element of the second resin wire. Specifically, as shown in Table 1, when the second resin wire is polyester-based (polyethylene terephthalate, polybutylene terephthalate, etc.), its constituent elements C (carbon), O (oxygen), H ( It is considered that the compound containing (hydrogen) is dissolved or precipitated in the electroless plating solution, or is contained in the plating layer. These compounds can be detected by emission spectroscopy (inductively coupled plasma emission spectroscopy: ICP), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Auger electron spectroscopy (AES), and the like. (The same applies to the specific aspect 2).

<< Specific Aspect 2 >>
Next, as a specific embodiment 2, a case where the resin wire diameter reduction step S12 shown in FIG. 4 is performed by the first activation unit 230 (indicated by * 2 in the figure) shown in FIG. 8 will be described. That is, in the method for producing conductive fibers according to the specific aspect 2, the first solution is an acidic solution containing a catalyst for plating, and the step (b) (resin wire diameter reduction step S12 shown in FIG. 4). At the same time, the plating catalyst is attached to the fiber bundle. In this way, by forming the fiber bundle with a resin wire (second resin wire) that is easily soluble in an acidic solution and a resin wire (first resin wire) that is difficult to dissolve in an acidic solution, the fiber bundle 13a before the diameter reduction can be formed. When immersed in an acidic solution containing a plating catalyst (for example, the pH is less than 1), the diameter of the second resin wire 12a is reduced, and at the same time, the plating catalyst adheres to the resin wires constituting the fiber bundle. As a result, in the first embodiment, the process can be further simplified and the manufacturing cost can be reduced.

As described above, when the fiber bundle is composed of a resin wire (second resin wire) that is easily dissolved in an acidic solution and a resin wire (first resin wire) that is difficult to dissolve in an acidic solution, the first resin wire (supporting resin wire). Table 2 summarizes specific examples of the raw materials for the second resin wire (reduced diameter resin wire). The first resin wire may be a combination of resin wires that are difficult to dissolve in an acidic solution. Similarly, the second resin wire may be a combination of resin wires that are easily dissolved in an acidic solution.

Similar to the specific aspect 1, in the specific aspect 2, the compound containing the constituent elements of the second resin wire is added to the first activating liquid 231 shown in FIG. 8 through the resin wire diameter reduction step S12. Is dissolved or precipitated, and the plating layer 14 shown in FIG. 1 contains a compound containing a constituent element of the second resin wire. Specifically, as shown in Table 2, when the second resin wire is nylon, a compound containing its constituent elements C (carbon), O (oxygen), H (hydrogen), and N (nitrogen). However, when the second resin wire is a silicone resin, its constituent elements C (carbon), O (oxygen), H (hydrogen), and Si (silicon) are dissolved or precipitated in the first activator, respectively. Alternatively, it is considered to be contained in the plating layer.

The present invention is not limited to the above-described embodiment and the above-mentioned specific embodiment, and various modifications can be made without departing from the gist thereof.

10, 20, 90 Conductive fiber 11 First resin wire 11a Conductive wire 12a, 12b Second resin wire 13a, 13b, 23b, 93 Fiber bundle 14,94 Plating layer 91 Resin wire 100 Coaxial cable 110 First conductor (inner conductor)
120 1st insulation layer 130 2nd conductor (outer conductor)
140 Second insulating layer

Claims (9)

It has a fiber bundle containing a first resin wire and a second resin wire, and a plating layer that covers the fiber bundle.
The second resin wire is thinner than the first resin wire.
The plating layer is a conductive fiber that is also present inside the fiber bundle. In the conductive fiber according to claim 1,
The first resin wire and the second resin wire are conductive fibers composed of different resin compositions. In the conductive fiber according to claim 1 or 2.
A conductive fiber in which the second resin wire is arranged more than the first resin wire on the outer peripheral portion of the fiber bundle in a cross-sectional view. In the conductive fiber according to any one of claims 1 to 3,
The fiber bundle is a conductive fiber which is a stranded wire of the first resin wire and the second resin wire. A coaxial cable comprising the conductive fiber according to any one of claims 1 to 4.
The first conductor, the first insulating layer coated around the first conductor, the second conductor arranged around the first insulating layer, and the second insulating coated around the second conductor. With layers,
The second conductor is a coaxial cable which is a horizontal winding shield in which the conductive fibers are spirally wound around the first insulating layer, or a braided shield in which the conductive fibers are braided. (A) A step of twisting the first resin wire and the second resin wire to form a fiber bundle,
(B) After the step (a), the step of thinning the second resin wire,
(C) A step of coating the fiber bundle with a plating layer at the same time as the step (b) or after the step (b).
A method for producing conductive fibers, including. In the method for producing conductive fibers according to claim 6,
The second resin wire is more soluble in the first solution than the first resin wire.
In the step (b),
A method for producing conductive fibers, in which the fiber bundle is immersed in the first solution. In the method for producing conductive fibers according to claim 7,
The first solution is a basic electroless plating solution.
A method for producing conductive fibers, wherein the step (b) and the step (c) are performed at the same time. In the method for producing conductive fibers according to claim 7,
The first solution is an acidic solution containing a catalyst for plating.
At the same time as the step (b), the plating catalyst is attached to the fiber bundle.
The step (c) is a method for producing conductive fibers, which is carried out after the step (b).

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