JP2020126720A - Conductive fiber, cable and method for producing conductive fiber - Google Patents

Abstract

To provide a conductive fiber excellent in flexibility which comprises a center thread composed of resin fibers and a metal layer for covering the circumference of the center thread and a method for producing the same and to provide a cable comprising a braided shield composed of the conductive fiber.SOLUTION: There is provided a conductive fiber 1 comprising a center thread 11 composed of a resin fiber 10 or a plurality of intertwisted resin fibers 10 and a plating layer 12 for directly covering the surface of the center thread 11, in which the plating layer 12 has a belt-like pattern which is spirally formed while being spaced in the center thread 11.SELECTED DRAWING: Figure 1

Description

The present invention relates to a conductive fiber, a cable, and a method for manufacturing a conductive fiber.

Conventionally, a conductor in which a metal plating layer is formed around a synthetic fiber is known (for example, refer to Patent Document 1). It is said that the conductor described in Patent Document 1 can be used as it is as a gold thread wire of a speaker, or by providing an insulating resin around the wire, a core wire of a cable, or a core wire reinforcing material. There is.

JP, 2011-76852, A

However, when the conductor as described in Patent Document 1 is used for a member such as a braided shield provided on the outer peripheral side of a cable, higher flex resistance is required.

Therefore, an object of the present invention is a conductive fiber having a core layer composed of a resin fiber and a metal layer coating the periphery thereof, which is excellent in bending resistance, a manufacturing method thereof, and the same. An object of the present invention is to provide a cable having a braided shield composed of conductive fibers.

The present invention, for the purpose of solving the above problems, comprises a central yarn made of one resin fiber or a plurality of twisted resin fibers, and a plating layer for directly coating the surface of the central yarn, Provided is a conductive fiber, in which a plating layer has a strip-shaped pattern formed in a spiral shape with a space in the central yarn.

According to the present invention, a conductive fiber comprising a core yarn composed of a resin fiber and a metal layer covering the core yarn, the conductive fiber having excellent bending resistance, a method for producing the same, and the conductivity thereof are provided. A cable with a braided shield composed of fibers can be provided.

FIG. 1 is a schematic view showing the appearance of the conductive fiber according to the embodiment. FIGS. 2A and 2B are cross-sectional views in the radial direction of the conductive fiber cut along the cutting line AA shown in FIG. 1. FIG. 3 is a radial cross-sectional view of a cable having a braided shield composed of a plurality of braided conductive fibers. FIG. 4 is a schematic diagram showing a configuration of a plating processing system used for forming a plating layer. FIG. 5 is a schematic view showing the appearance of the center yarn in a state in which a mask for protecting a region not subjected to the surface treatment is wound around the surface.

[Embodiment]
(Structure of conductive fiber)
FIG. 1 is a schematic diagram showing the appearance of a conductive fiber 1 according to an embodiment. 2A and 2B are cross-sectional views in the radial direction of the conductive fiber 1 cut along the cutting line AA shown in FIG. 1.

The conductive fiber 1 includes a center yarn 11 made of one resin fiber 10 or a plurality of twisted resin fibers 10, and a plating layer 12 that directly covers the surface (outer peripheral surface) of the center yarn 11. 2A shows a cross section of the conductive fiber 1 in the case where the central yarn 11 is composed of a plurality of resin fibers 10 twisted together, and FIG. 2B shows a resin fiber in which the central yarn 11 is one. 1 shows a cross section of a conductive fiber 1 when it is composed of 10.

The diameter of the conductive fiber 1 when the center yarn 11 is composed of a plurality of resin fibers 10 twisted together is, for example, 110 to 240 μm. The diameter of the conductive fiber 1 in the case where the central yarn 11 is composed of one resin fiber 10 is, for example, 50 to 330 μm. The diameter of the conductive fiber 1 in the case where the central yarn 11 is composed of a plurality of resin fibers 10 twisted together can be adjusted by the diameter and the number of the resin fibers 10.

The material of the resin fiber 10 that constitutes the center yarn 11 is not particularly limited as long as it is a material that does not dissolve even when it comes into contact with the catalyst solution or the plating solution used to form the plating layer 12.

Typically, polyethylene or fluororesin is used as the material of the resin fiber 10. In particular, polyethylene is preferable as the material of the resin fiber 10 because it is easily available and has high electron beam resistance. Specific examples of the fluorine-based resin include polytetrafluoroethylene (PTFE), perfluoroalkoxy (PFA), perfluoroethylenepropene copolymer (FEP), ethylene/tetrafluoroethylene copolymer (ETFE), and tetrafluoroethylene-peroxide. Fluorodioxole copolymer (TFE/PDD), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polyvinyl fluoride (PVF), etc. may be used. it can.

The plating layer 12 is a layer formed on the surface of the center yarn 11 by plating, and is made of a metal such as copper or silver. The thickness of the plating layer 12 is, for example, 2 to 30 μm.

In the conductive fiber 1, since a metal layer that covers the surface of the center yarn 11 is formed by plating, a special technique is not required to form the metal layer, and the metal layer is formed by winding a copper strip. The price can be reduced compared to.

Further, since the plating layer 12 formed by plating the surface of the center yarn 11 is in close contact with the center yarn 11, the conductive fiber 1 has high resistance to bending. Therefore, copper or silver having high conductivity can be used as the material of the plating layer 12. A material other than copper and silver such as a copper alloy may be used depending on the application of the conductive fiber 1.

Further, the plating layer 12 does not need to have a thickness capable of obtaining the mechanical strength required for winding like a copper strip, and is thinned within a range in which an original function such as a function as a shield material is obtained. be able to. For example, according to the plating process of the present embodiment described later, the thickness of the plating layer 12 can be reduced to several tens nm.

As shown in FIG. 1, the plating layer 12 has a strip-shaped pattern formed on the surface of the central yarn 11 in a spiral shape with a gap. By having such a pattern, as compared with the case where it is formed on the entire surface of the central yarn 11, the followability to the bending of the central yarn 11 as the base is improved, and when the conductive fiber 1 is largely bent. But it is hard to be damaged. That is, the bending resistance is high.

In particular, as shown in FIG. 2( a ), when the center yarn 11 is composed of a plurality of resin fibers 10 twisted together, the center yarn 11 has excellent bendability, and therefore the plating layer 12 has excellent bend resistance. is important.

In the pattern of the plating layer 12, the ratio W1/W2 of the width W2 of the gap in the lengthwise direction of the center yarn 11 to the width W1 of the band in the lengthwise direction of the center yarn 11 is preferably 1 or more. The above is more preferable. When W1/W2 is less than 1, the shield function of the braided shield formed using the conductive fiber 1 may be insufficient. For example, if W1/W2 is 1 or more, the shield function is used for the braided shield of cables that pass relatively low-speed signals such as control lines and signal lines, such as bending cables installed in robot systems in factories. No problem.

Further, W1/W2 is preferably 4 or less in order to enhance the bending resistance of the plating layer 12. Further, if the gap is too wide, the braided shield formed by using the conductive fiber 1 may have insufficient shield characteristics, so the width W2 is preferably 100 μm or less.

In the conductive fiber 1, in order to enhance the adhesion between the central yarn 11 and the plating layer 12, at least one of a roughening treatment and a hydrophilizing treatment is performed on a region of the surface of the central yarn 11 where the plating layer 12 is formed. Surface treatment including is performed. On the other hand, the plating layer 12 is not formed on the region of the surface of the center yarn 11 which is not subjected to the surface treatment, or even if the plating layer 12 is temporarily formed, the adhesion is weak and therefore the peeling occurs.

When the surface treatment is applied only to the area where the plating layer 12 is formed on the surface of the center yarn 11, for example, the area where the plating layer 12 is not formed, that is, the area where the surface treatment is not applied is covered with a belt-shaped mask. Perform processing. Like the region where the plating layer 12 is formed, the region where the plating layer 12 is not formed has a strip-shaped pattern that is formed in a spiral shape with a gap in the center yarn 11, so that a strip-shaped mask is formed between the center yarn 11 and the region. It may be wound in a spiral while leaving a gap.

As the above-mentioned strip-shaped mask, a thread or tape made of a material resistant to surface treatment can be used. A material that is resistant to surface treatment is, for example, a material having a strength that can withstand collision of a propellant when blasting is performed as the surface treatment, and does not easily react with a chemical solution when etching is performed as the surface treatment. It is a material.

Concavities and convexities are formed in the area of the surface of the central yarn 11 which has been roughened. The formation of the unevenness makes it difficult for the catalyst to detach from the surface of the center yarn 11 in the plating process for forming the plating layer 12, and also increases the surface area of the center yarn 11 to cause the plating of the center yarn 11 and the plating. The effect of improving the adhesiveness of the layer 12 is increased.

Further, when the central yarn 11 is subjected to the hydrophilic treatment after the roughening treatment, the surface area of the central yarn 11 increases, so that the amount of polar functional groups contributing to the improvement of surface wettability increases.

In order to increase the effect of these roughening treatments, the arithmetic average roughness Ra of the surface of the central yarn 11 is preferably in the range of 2 μm or more and 14 μm or less.

For the roughening treatment of the surface of the center yarn 11, for example, blast treatment can be used. Examples of the blast treatment include dry ice blast using particles of dry ice as a propellant, sand blast using particles of alumina, SiC, etc. as a propellant, and wet blast using a mixed liquid (slurry) of water and an abrasive as a propellant. Can be used.

In particular, it is preferable to use dry ice blast for the roughening treatment of the surface of the center yarn 11. Since dry ice sublimes under normal pressure and does not remain on the surface of the center yarn 11 after processing, when dry ice blasting is used, a cleaning step after processing is unnecessary.

When the blast treatment is used for the roughening treatment of the surface of the central yarn 11, the particle size of the blast propellant, the blast ejection pressure (spraying pressure), the distance between the blast device injection nozzle and the insulator, the center yarn 11 hardness, The arithmetic mean roughness Ra of the surface of the central yarn 11 can be controlled by adjusting the roughness.

Laser irradiation treatment may be used for the roughening treatment of the center yarn 11. In this case, the arithmetic mean roughness Ra of the surface of the central yarn 11 can be controlled by the spot diameter of the laser or the like.

Further, when the reaction rate between the chemical solution and the central yarn 11 can be controlled by controlling the concentration or temperature of the chemical liquid to control the arithmetic average roughness Ra of the surface of the resin fiber 10 or the central yarn 11, a sodium naphthalene complex solution or chromium is used. A wet etching process using a chemical solution such as an acid solution may be used for the roughening process of the center yarn 11. However, when the center yarn 11 is made of polyethylene or a fluororesin, it takes a very long time to perform the treatment, and thus it is not practical to use the etching treatment using the chromic acid solution.

The arithmetic average roughness Ra of the surface of the central yarn 11 can be measured by a laser microscope or the like.

Further, polar functional groups are generated in the region of the surface of the center yarn 11 which has been subjected to the hydrophilic treatment, and the wettability of the region is improved. Here, the polar functional group is a polar functional group (hydrophilic group) such as a carbonyl group or a hydroxy group. The polar functional group includes a functional group containing oxygen such as a carbonyl group and a hydroxy group, and a functional group containing nitrogen instead of oxygen. In general, the presence of a polar functional group is directly linked to surface wettability (see, for example, Akira Nakajima, wettability of solid surface, from superhydrophilic to superhydrophobic (Kyoritsu Shuppan Co., Ltd., 2014)).

By improving the wettability of the surface of the central yarn 11, the catalyst solution or the plating solution used for the plating treatment is likely to come into contact with the surface of the central yarn 11 over the entire circumference. As a result, the adhesion between the plating layer 12 and the center yarn 11 is improved.

The surface of the central yarn 11 is made hydrophilic by, for example, corona discharge exposure, plasma exposure in gas mixed with atmospheric composition gas or rare gas, ultraviolet irradiation, electron beam irradiation, γ-ray irradiation, X-ray irradiation, ion beam. Irradiation, immersion in an ozone-containing liquid, or the like can be used.

The conductive fiber 1 is, for example, a braided shield used for various cables such as EV vehicle harnesses, robot harnesses, electromagnetic shield wires for medical probes, cords for lightweight earphones, copper boats for lightweight heaters, and high-speed transmission cables. Can be used as That is, according to the present invention, it is possible to provide a cable including a braided shield composed of a plurality of braided conductive fibers 1.

FIG. 3 is a radial cross-sectional view of a cable 20 that is an example of a cable including a braided shield composed of a plurality of braided conductive fibers 1. The cable 20 includes a plurality of electric wires 21, a braided shield 22 that covers the plurality of electric wires 21, and an insulating jacket 23 that covers the surface of the braided shield 22. Here, the electric wire 21 is composed of a linear conductor and an insulator covering the conductor. The braided shield 22 is composed of a plurality of braided conductive fibers 1.

Since the braided shield made of the conductive fiber 1 is significantly lighter than the braided shield made entirely of metal, it is possible to reduce the weight of a cable or the like including the braided shield. Further, for example, by using the braided shield made of the conductive fiber 1, the total weight of the EV car or the robot can be reduced, so that the power consumption can be saved.

(Method for producing conductive fiber)
Hereinafter, an example of the method for manufacturing the conductive fiber 1 according to the first embodiment will be described.

FIG. 4 is a schematic diagram showing a configuration of the plating processing system 100 used for forming the plating layer 12. The plating system 100 includes a degreasing unit 110, a surface treatment unit 120, a first activation unit 130, a second activation unit 140, an electroless plating unit 150, an electrolytic plating unit 160, and a core yarn 11. Bobbins 170a to 170m for transfer.

In the plating processing system 100, the bobbins 170a to 170m are continuously operated at a desired number of revolutions to transfer the central yarn 11 at a desired speed while maintaining a constant tension. The center fiber 11 passes through the plating system 100 to form the plating layer 12, whereby the conductive fiber 1 is obtained.

The degreasing unit 110 is for removing oil and fat on the surface of the center yarn 11, and includes a degreasing tank 111 and a degreasing liquid 112 contained in the degreasing tank 111. The degreasing liquid 112 contains, for example, sodium borate, sodium phosphate, and a surfactant. At least a part of the bobbin 170b is located in the degreasing liquid 112 in order to transfer the central yarn 11 and pass it through the degreasing liquid 112.

The surface treatment unit 120 is for subjecting the central yarn 11 to surface treatment, and includes a surface treatment device 121. As the surface treatment device 121, for example, a blasting device for performing a roughening treatment, a laser device, an etching device using chromic acid, sulfuric acid or the like as an etchant, a corona treatment device for performing a hydrophilic treatment, a plasma treatment device, An ultraviolet irradiation device, an electron beam irradiation device, a γ-ray irradiation device, an X-ray irradiation device, an ion beam irradiation device, an etching device using an ozone-containing liquid as an etchant, and the like are used.

When both the roughening treatment and the hydrophilic treatment are performed as the surface treatment, or when a plurality of treatments are performed as the roughening treatment or the hydrophilic treatment, a plurality of types of surface treatment devices 121 are included in the surface treatment unit 120. May be.

The first activation unit 130 is for forming a catalytically active layer on the surface of the central yarn 11, and includes a first activation tank 131 and a first activation liquid 132 contained in the first activation tank 131. With. The first activation liquid 132 contains, for example, palladium chloride, stannous chloride, concentrated hydrochloric acid, or the like. The catalytically active layer is for forming a dense and high-quality plating layer 12. At least a part of the bobbin 170f is located in the first activation liquid 132 in order to transfer the central yarn 11 and pass it through the first activation liquid 132.

The second activation unit 140 is for cleaning the surface of the catalytically active layer formed by the first activation unit 130, and is housed in the second activation tank 141 and the second activation tank 141. And a second activation liquid 142. The second activation liquid 142 is, for example, sulfuric acid. At least a part of the bobbin 170h is located in the second activation liquid 142 in order to transfer the central yarn 11 and pass it through the second activation liquid 142.

The electroless plating unit 150 is for forming an electroless plating layer before the electroplating treatment to make the surface of the central yarn 11 (the surface of the catalytically active layer) electrically conductive. The electroless plating solution 152 contained in the electrolytic plating tank 151 is provided. The electroless plating solution 152 contains, for example, copper sulfate, Rossier salt, formaldehyde, sodium hydroxide and the like. At least a part of the bobbin 170j is located in the electroless plating solution 152 in order to transfer the central yarn 11 and pass it through the electroless plating solution 152.

The electroplating unit 160 is for performing an electroplating process, and includes an electroplating bath 161, an electroplating solution 162 contained in the electroplating bath 161, a pair of anodes 163, and a power supply unit 164.

As an example of the composition of the electrolytic plating solution 162, the composition and manufacturing method of the copper sulfate (CuSO ₄ ) plating solution and the copper cyanide (CuCN) plating solution are shown below.

[Copper sulfate plating solution]
Table 1 shows an example of the composition of the copper sulfate plating solution as the electrolytic plating solution 162. “Sodium chloride, hydrochloric acid” in Table 1 is an example of chloride.

First, about 60 to 70% by volume of water of the entire plating solution is put into a sufficiently washed electrolytic plating tank 161, and then the water temperature is raised from room temperature to about 50°C. Next, copper sulfate in an amount corresponding to the required plating deposition amount, which depends on the desired thickness of the plating layer 12 and the size and length of the center yarn 11, is poured into the warm water and stirred until the dissolution is completed. To do. Then, in order to control the conductivity (current density) of the plating solution and the solubility of the anode copper plate within an appropriate range, the necessary amount of sulfuric acid is added with stirring, and then the required amount of plating solution is finally reached. Add additional water to. Further, in order to remove impurities in the plating solution, activated carbon is introduced or an activated carbon layer is provided on the filter material of the filter, and then the activated carbon is circulated in the filter to remove the activated carbon having adsorbed the impurities.

Next, in order to adjust the chlorine ion concentration for improving the effect of the surface gloss of the plating layer to a predetermined value, sodium chloride, hydrochloric acid or the like is appropriately added to the plating solution. Then, it is analyzed and confirmed whether sulfuric acid and copper sulfate have a specified concentration. Next, after appropriately adding an additive such as a brightener or a surfactant corresponding to the material of the core yarn 11, a Hull cell test (for example, “Yoshio Yamana, Introduction to Mechanical Engineering, Introduction to Plating Work, Science and Engineering Co., Ltd.” Or "Hidehiko Enomoto, Naoji Furukawa, Munejun Matsumura, Composite Plating, Nikkan Kogyo Shimbun") and check the state of the plating solution to see if the desired plating layer can be obtained. Finally, after performing continuous electrolysis at 10 A/dm ² for several hours of empty electrolysis, it is confirmed whether or not stable plating film formation is possible.

When a copper sulfate plating solution is used as the electrolytic plating solution 162 and Cu ions are generated as Cu atoms (metals), the reaction represented by the following formula 1 occurs. Formula 2 represents that a divalent Cu cation becomes a Cu atom (metal) by receiving two electrons.

In the reaction represented by the formula 1, two electrons are required for one Cu ion, so the amount of charge required to generate 1 mol of Cu is the product of the elementary charge and the Avogadro constant. It is about 192,971C which is twice the Therefore, considering the atomic weight of copper of 63.54, the amount of charge required to form 1 g of copper is about 3,037 C/g.

[Copper cyanide plating solution]
Table 2 shows an example of the composition of the copper cyanide plating solution as the electrolytic plating solution 162. "Free sodium cyanide (free potassium cyanide)" in Table 2 is alkali cyanide that remained in the bath without reacting with copper cyanide.

First, about 60% of the entire plating solution, pure water from which impurity components such as sulfur and chlorine have been removed is put in a preliminary tank. Next, sodium cyanide or potassium cyanide is poured into pure water and dissolved to form an alkali cyanide aqueous solution. Further, the paste-shaped cuprous cyanide made of pure water is added to and dissolved in the alkali cyanide aqueous solution while being stirred. In addition, potassium hydroxide or sodium hydroxide is added to adjust the pH and conductivity of the plating solution for the purpose of suppressing cyanide decomposition. Next, activated carbon or the like is added while heating to 40 to 70° C., which is close to the temperature of the plating solution at the time of plating treatment, and the mixture is sufficiently stirred and allowed to stand to precipitate the activated carbon on which impurities are adsorbed. Then, after passing through a filter to remove activated carbon and the like having impurities taken in, the solution is transferred to a plating tank, and pure water is added to adjust the solution volume to obtain a plating solution.

Next, this plating solution is analyzed, and an additive material is added if necessary in order to improve and stabilize the plating performance. Specifically, sodium carbonate or potassium carbonate is added as a pH buffering/adjusting agent in an appropriate amount. In addition, potassium sodium tartrate (Rochelle salt) is added in order to smoothly dissolve the copper anode and efficiently supply copper ions. Finally, a stainless steel plate as a cathode and a rolled copper plate for plating as an anode are suspended, and weak electrolysis is performed with a weak current density (0.2 to 0.5 A/dm ² ).

When a copper cyanide plating solution is used as the electrolytic plating solution 162 and Cu ions are generated as Cu atoms (metals), the reaction represented by the following formula 2 occurs. Formula 2 represents that a monovalent Cu cation becomes a Cu atom (metal) by receiving one electron.

In the reaction represented by Equation 2, one electron is required for one Cu ion, and therefore the charge amount required to generate 1 mol of Cu is the product of the elementary charge and the Avogadro constant. Is about 96,485 C (corresponding to the Faraday constant). Therefore, considering the atomic weight of copper of 63.54, the amount of electric charge required to form 1 g of copper is about 1,518 C/g.

As shown in Equation 3 below, the current i is represented by the charge amount Q and the time t. Therefore, if the electrolytic plating current density is the same, in principle, when a copper cyanide plating solution having a low valence (valence number+1) of copper ions is used as the electrolytic plating solution 162, the copper sulfate plating solution is used. It is possible to form the plating layer 12 in half the time when using. Therefore, if the voltage and current used during electrolytic plating are constant, it is considered that the power consumption directly linked to the plating time will be halved, and the energy cost can be reduced. Further, since the factory operation time in the electrolytic plating process is halved, it is possible to expect a reduction in personnel costs with respect to the number of products produced.

The plating solution that can be used as the electrolytic plating solution 162 is not limited to the above-mentioned copper sulfate plating solution or copper cyanide plating solution, and for example, Cu(BF ₄ ) ₂ , HBF ₄ , Cu metal, or the like can be used. A copper borofluoride plating solution prepared by mixing, Cu ₂ P ₂ O ₇ /3H ₂ O, K ₄ P ₂ O ₇ /3H ₂ O, NH ₄ OH, KNO ₃ , Cu metal, etc. are prepared by mixing. It may be a pyrophosphoric acid plating solution. Further, among these plating solutions, a plating solution in which two or more kinds of plating solutions are combined may be used.

The anode 163 is immersed in the electroplating solution 162. The anode 163 is a supplier of copper ions in electrolytic plating, and is, for example, a product obtained by roll-casting molten copper (crude copper having a purity of about 99%) made from copper hot water. In addition, a stripped copper plate (electrolytic copper) made of copper with improved purity obtained by performing electrolysis of a seed plate using crude copper as an anode and stainless steel or a titanium plate as a cathode, and stripping the copper deposited on the cathode surface. It may be used as the anode 163.

The bobbin 170k and the bobbin 170m located on the electrolytic plating tank 161 have conductivity and function as a cathode. The bobbin 170l located in the electrolytic plating solution 162 is insulative. The power supply unit 164 applies a DC voltage between the anode 163 and the bobbins 170k and 170m, which are cathode bobbins.

By applying the DC voltage between the node 163 and the bobbin 170k and the bobbin 170m, the central yarn 11 is transferred and passed through the electrolytic plating solution 162, so that the central yarn 11 is placed on the electroless plating layer. An electrolytic plating layer is formed and a plating layer 12 is obtained.

The transport mechanism for the center yarn 11 in the electroplating unit 160 is not limited to the bobbin 170k, the bobbin 170l, and the bobbin 170m. For example, without providing a bobbin mechanism in the electrolytic plating solution 162, the center yarn 11 is bent into a shape having a predetermined curvature or a large number of curvatures, and is crawled into the electrolytic plating solution 162, extruded from one side, and pulled from the other side to be transferred. It may be a mechanism that does. Further, without arranging a transfer mechanism, the bundled central yarns 11 are immersed in the electrolytic plating solution 162, and then connected to the cathode electrode and appropriately swung so that the entire surface of the central yarns 11 is electroplated. May be contacted with to perform electrolytic plating.

Next, an example of the flow of the forming process of the plating layer 12 using the plating processing system 100 will be described.

First, a thread, a tape, or the like is spirally wound around the surface of the center thread 11 as a mask for protecting the area not subjected to the surface treatment. In addition, after the next step of removing the oil and fat, a thread or a tape as a mask may be wound.

FIG. 5 is a schematic view showing the appearance of the center yarn 11 in a state in which a mask 13 for protecting a region not subjected to the surface treatment is wound around the surface. Since the mask 13 covers the area where the surface treatment is not performed, that is, the area where the gap of the plating layer 12 is formed, the width of the mask 13 in the length direction of the central yarn 11 is W2. On the other hand, the region not covered with the mask 13 is the region where the surface treatment is performed, that is, the region where the plating layer 12 is formed, so the width of the gap between the masks 13 in the length direction of the central yarn 11 is W1. ..

Next, the center yarn 11 is immersed in the degreasing liquid 112 in the degreasing unit 110 for 3 to 5 minutes. The temperature of the degreasing liquid 112 at this time is 40 to 60° C., for example. As a result, the oil and fat adhering to the surface of the central yarn 11 is removed.

In the next surface treatment step, when a treatment having an effect of removing oils and fats on the surface of the central yarn 11 such as a roughening treatment by a blast method is performed, the degreasing step by the degreasing unit 110 can be omitted.

Next, in the surface treatment unit 120, the central yarn 11 is subjected to roughening treatment by blast treatment and hydrophilic treatment by exposure to corona discharge. At this time, since the surface treatment is performed in a state where the surface of the central yarn 11 is covered with the above-mentioned belt-shaped mask, it is applied only to the region of the surface of the central yarn 11 which is not covered with the mask. That is, the surface treatment is applied to a region having a strip-shaped pattern, which is a region where the plating layer 12 is formed, and which is spirally wound around the central yarn 11 with a space.

In the blasting process, a propellant such as dry ice is jetted from a jetting nozzle of a blasting device as one of the surface treatment devices 121 to roughen the surface of the center yarn 11.

In the blasting process, in order to control the arithmetic average roughness Ra of the surface of the resin fiber 10 and the center yarn 11, the particle size of the blasting propellant, the blasting blasting pressure, the distance between the tip of the blasting device jetting nozzle and the insulator. Etc. can be set appropriately. For example, when performing dry ice blasting, the particle size of dry ice particles is set in the range of 0.3 to 3 mm, and the distance from the surface of the central yarn 11 to the tip of the injection nozzle is set in the range of 0 to 10 cm. The dry ice blast treatment is performed under temperature conditions in the range of -80°C to room temperature.

In the corona discharge exposure, a high frequency high voltage is applied between a pair of flat plate electrodes installed with the center yarn 11 interposed therebetween in the corona treatment device as one of the surface treatment devices 121 to generate corona discharge. This makes the surface of the central yarn 11 hydrophilic and improves the wettability. The corona treatment device may include two or more pairs of flat plate electrodes.

In corona discharge exposure, for example, the voltage output is about 9 kV, the distance between the surface of the central yarn 11 and the tip of the discharge probe is several tens mm, and the scanning speed of the discharge probe is 0.15 to 15 mm/sec. Corona discharge exposure.

Next, the mask for protecting the area not subjected to the surface treatment is removed from the surface of the center yarn 11.

Next, in the first activation unit 130, the central yarn 11 is immersed in the first activation liquid 132 for 1 to 3 minutes. The temperature of the first activation liquid 132 is, for example, 30 to 40°C. As a result, a catalytically active layer is formed on the surface of the central yarn 11. Specifically, for example, by using a colloidal solution of Pd-Sn particles as the first activating liquid 132, Pd-Sn particles containing Pd exhibiting high catalytic activity are attached to the surface of the central yarn 11 to achieve catalytic activity. Form the layers. At this time, the catalytically active layer is not formed to a sufficient extent for the subsequent plating treatment in the area not subjected to the surface treatment.

Next, in the second activation unit 140, the central yarn 11 is immersed in the second activation liquid 142 for 3 to 6 minutes. The temperature of the second activation liquid 142 is, for example, 30 to 50°C. As a result, for example, Sn that lowers the activity can be removed from the catalytically active layer on the surface of the central yarn 11, and the activity of the catalytically active layer can be increased.

Next, in the electroless plating unit 150, the center yarn 11 is immersed in the electroless plating solution 152 for 10 minutes or less. The temperature of the electroless plating solution 152 is, for example, 20 to 30°C. As a result, an electroless plating layer as a seed layer for electrolytic plating is formed on the surface of the center yarn 11, and the surface of the center yarn 11 is made conductive. The longer the immersion time in the electroless plating solution 152, the larger the thickness of the electroless plating layer. At this time, the electroless plating layer is not formed or is formed in the region where the surface treatment is not performed, in a state where the adhesion to the central yarn 11 is weak.

Next, in the electrolytic plating unit 160, the center yarn 11 is immersed in the electrolytic plating solution 162 for 3 minutes or less. The thickness of the electrolytic plating layer can be controlled by the transfer speed of the central yarn 11 and the immersion time in the electrolytic plating solution 162. The transfer speed and the immersion time of the central yarn 11 depend on the desired thickness of the plating layer 12, the control condition of the plating bath (the plating solution in the state of being stored in the plating tank), the change over time of the plating bath, and the like. , Concentration of the plating bath, pH, temperature, type of additive, etc. are considered and optimized.

Examples of specific conditions for electrolytic plating in the electrolytic plating unit 160 are as shown in Table 3 below. "Bath temperature" and "bath voltage" in Table 3 are the temperature of the plating bath, the voltage between the anode 163 in the plating bath, and the bobbin 170k and the bobbin 170m serving as the cathode, respectively.

The electrolytic plating described above forms an electrolytic plated layer on the surface of the electroless plated layer. The plating layer 12 is composed of the laminated body of the electroless plating layer and the electrolytic plating layer. Here, the plating layer 12 is not formed on the region of the surface of the center yarn 11 which is not subjected to the surface treatment, or even if the plating layer 12 is temporarily formed, the adhesion is weak and therefore the peeling occurs. That is, the plating layer 12 is formed only on the surface-treated region of the surface of the central yarn 11. Through the above steps, the conductive fiber 1 according to the present embodiment is obtained.

Although not shown in FIG. 4, cleaning of the center yarn 11 with pure water (ultrasonic cleaning, so as not to cause a defect due to residual chemicals in the previous step between the above steps) It is preferable to perform rocking washing, running water washing, etc.).

In addition, in order to obtain a suitable transfer speed of the central yarn 11 in each step, it is preferable to adjust the gear ratio (rotation radius) for each of the bobbins 170a to 170m to optimize the rotation speed. Therefore, it is preferable to provide a rotating mechanism having a buffer between the units so that the transfer speed can be changed or the temporary standby can be arbitrarily performed in the inter-process route.

(Effects of the embodiment)
According to the above-mentioned embodiment, the conductive fiber is provided with the central yarn made of the resin fiber and the metal layer covering the periphery thereof, and copper or silver is used for the metal layer while ensuring bending resistance. It is possible to provide a low-cost conductive fiber and a method for producing the same that can be obtained.

(Summary of Embodiments)
Next, the technical idea grasped from the embodiment described above will be described with reference to the reference numerals and the like in the embodiment. However, the reference numerals and the like in the following description are not intended to limit the constituent elements in the claims to the members and the like specifically shown in the embodiments.

[1] A central yarn (11) made of one resin fiber (10) or a plurality of twisted resin fibers (10), and a plating layer (12) directly coating the surface of the central yarn (11). The conductive fiber (1), which comprises a plating layer (12) having a strip-shaped pattern formed in a spiral shape with a gap in the central yarn (11).

[2] In the pattern of the plating layer (12), the ratio of the width of the gap in the longitudinal direction of the central yarn (11) to the width of the band in the longitudinal direction of the central yarn (11) is 1 or more and 4 or less. The conductive fiber (1) according to the above [1], which is within the range.

[3] The conductive fiber (1) according to the above [1] or [2], wherein the plating layer (12) is made of copper or silver.

[4] A braided shield (22) composed of an electric wire (21) and a plurality of woven conductive fibers (1) for covering the periphery of the electric wire (21), and a jacket (23) for covering the braided shield (22). The conductive fiber (1) directly comprises a central yarn (11) made of one resin fiber (10) or a plurality of twisted resin fibers (10) and a surface of the central yarn (11). And a plating layer (12) for coating, wherein the plating layer (12) has a strip-shaped pattern formed in a spiral shape while being spaced from the central yarn (11).

[5] In the pattern of the plating layer (12), the ratio of the width of the gap in the longitudinal direction of the central yarn (11) to the width of the band in the longitudinal direction of the central yarn (11) is 1 or more and 4 or less. The cable (20) according to [4] above, which is in the range of.

[6] The cable (20) according to the above [4] or [5], wherein the plating layer (12) is made of copper or silver.

[7] A surface treatment including at least one of a roughening treatment and a hydrophilizing treatment on the surface of the central yarn (11) made of one resin fiber (10) or a plurality of twisted resin fibers (10). And a step of forming a plating layer (12) by performing a plating treatment on the surface of the center yarn (11) after the surface treatment, wherein the surface treatment includes spacing the center yarn (11). A conductive fiber which is applied to an area having a strip-shaped pattern formed in a spiral shape while being vacant, and the plating layer (12) is formed only on the surface-treated area of the surface of the central yarn (11). The manufacturing method of (1).

[8] The method for producing the conductive fiber (1) according to the above [7], wherein the surface treatment is performed in a state where the region not subjected to the surface treatment is covered with a belt-shaped mask.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the invention.

In addition, the embodiments described above do not limit the invention according to the claims. Further, it should be noted that not all combinations of the features described in the embodiments are essential to the means for solving the problems of the invention.

1 Conductive Fiber 10 Resin Fiber 11 Core Thread 12 Plating Layer 20 Cable 21 Electric Wire 22 Unbalanced Shield 23 Jacket

Claims (8)

A central yarn made of one resin fiber or a plurality of twisted resin fibers,
A plating layer that directly covers the surface of the central yarn,
Equipped with
The plating layer has a band-shaped pattern formed in a spiral shape with a space in the central yarn.
Conductive fiber. The value of the ratio of the width of the gap in the length direction of the central yarn to the width of the band in the length direction of the central yarn in the pattern of the plating layer is in the range of 1 or more and 4 or less,
The conductive fiber according to claim 1. The plating layer is made of copper or silver,
The conductive fiber according to claim 1. Electric wire,
A braided shield that is composed of a plurality of woven conductive fibers and covers the periphery of the electric wire,
A jacket covering the braided shield,
Equipped with
The conductive fiber,
A central yarn made of one resin fiber or a plurality of twisted resin fibers,
A plating layer that directly covers the surface of the central yarn,
Equipped with
The plating layer has a band-shaped pattern formed in a spiral shape with a space in the central yarn.
cable. The value of the ratio of the width of the gap in the length direction of the central yarn to the width of the band in the length direction of the central yarn in the pattern of the plating layer is in the range of 1 or more and 4 or less,
The cable according to claim 4. The plating layer is made of copper or silver,
The cable according to claim 4 or 5. A step of performing a surface treatment including at least one of a roughening treatment and a hydrophilization treatment on the surface of a central yarn made of one resin fiber or a plurality of twisted resin fibers,
A step of performing a plating treatment on the surface of the central yarn after the surface treatment to form a plating layer;
Including,
The surface treatment is applied to a region having a belt-shaped pattern formed in a spiral shape with a space in the central yarn,
The plating layer is formed only on the surface-treated region of the surface of the central yarn,
Method for producing conductive fiber. The surface treatment is performed in a state in which the area not subjected to the surface treatment is covered with a belt-shaped mask,
The method for producing the conductive fiber according to claim 7.

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