JP7192539B2 - Conductive fiber, cable, and method for producing conductive fiber - Google Patents

Description

The present invention relates to conductive fibers, cables, and methods of making conductive fibers.

Conventionally, a conductor is known in which a metal plating layer is formed around synthetic fibers (see, for example, 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 for a speaker, or can be used as a core wire of an electric wire or cable, or as a core wire reinforcing material by providing an insulating resin around it. there is

JP 2011-76852 A

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

Accordingly, an object of the present invention is to provide a conductive fiber having a center thread made of resin fiber and a metal layer covering the periphery thereof, the conductive fiber having excellent bending resistance, a method for producing the same, and a method for producing the same. To provide a cable with a braided shield composed of conductive fibers.

In order to solve the above problems, the present invention includes a central yarn made of one resin fiber or a plurality of twisted resin fibers, and a plated layer that directly coats the surface of the central yarn, Provided is a conductive fiber in which the plated layer has a belt-like pattern spirally formed at intervals on the central thread.

INDUSTRIAL APPLICABILITY According to the present invention, a conductive fiber having a center thread made of resin fiber and a metal layer covering the periphery thereof, which has excellent bending resistance, a method for producing the same, and the conductive fiber A cable can be provided with a braided shield composed of fibers.

FIG. 1 is a schematic diagram showing the appearance of a conductive fiber according to an embodiment. 2(a) and 2(b) are radial cross-sectional views of the conductive fiber cut along the cutting line AA shown in FIG. FIG. 3 is a radial cross-sectional view of a cable with a braided shield composed of a plurality of braided conductive fibers; FIG. 4 is a schematic diagram showing the configuration of a plating system used for forming a plating layer. FIG. 5 is a schematic diagram showing the appearance of the center thread with a mask wrapped around the surface to protect the areas not subjected to surface treatment.

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

The conductive fiber 1 includes a central yarn 11 made of one resin fiber 10 or a plurality of twisted resin fibers 10, and a plated layer 12 that directly coats the surface (peripheral surface) of the central yarn 11. FIG. 2(a) shows a cross section of the conductive fiber 1 when the center yarn 11 is composed of a plurality of twisted resin fibers 10, and FIG. 1 shows a cross-section of a conductive fiber 1 when composed of 10. FIG.

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

The material of the resin fiber 10 forming the center thread 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 plating solution used for forming the plating layer 12 .

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

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

In the conductive fiber 1, since the metal layer covering the surface of the central thread 11 is formed by plating, no special technique is required for forming the metal layer, and the metal layer is formed by winding a copper strip. The price can be reduced compared to

In addition, since the plating layer 12 formed by plating the surface of the central yarn 11 is in close contact with the central yarn 11, the conductive fiber 1 is highly resistant to bending. Therefore, copper or silver with high electrical conductivity can be used as the material of the plating layer 12 . Materials other than copper and silver, such as copper alloys, may be used depending on the intended use of the conductive fiber 1 .

In addition, the plated layer 12 does not need to have a thickness to obtain the mechanical strength necessary for winding like a copper strip, and should be made as thin as possible to obtain its original function such as a function as a shielding material. be able to. For example, according to the plating process of this embodiment, which will be described later, the thickness of the plating layer 12 can be reduced to several tens of nanometers.

As shown in FIG. 1, the plating layer 12 has a band-like pattern spirally formed on the surface of the center thread 11 with intervals. By having such a pattern, compared to the case where it is formed on the entire surface of the central yarn 11, the followability to bending of the central yarn 11, which is the base, is improved, and when the conductive fiber 1 is greatly bent But not easily damaged. That is, the bending resistance is high.

In particular, as shown in FIG. 2A, when the central yarn 11 is composed of a plurality of twisted resin fibers 10, the bending resistance of the plated layer 12 is increased because the central yarn 11 has excellent flexibility. is important.

In the pattern of the plating layer 12, the ratio W1/W2 of the width W2 of the gap in the longitudinal direction of the central yarn 11 to the width W1 of the band in the longitudinal direction of the central yarn 11 is preferably 1 or more. It is more preferable to be above. If W1/W2 is less than 1, the shielding function of the braided shield formed using the conductive fibers 1 may be insufficient. For example, if W1/W2 is 1 or more for braided shielding of cables that pass relatively low-speed signals such as control lines and signal lines, such as bending cables that are built into robot systems in factories, the shielding function will work. No problem.

Moreover, W1/W2 is preferably 4 or less in order to increase the bending resistance of the plating layer 12 . Also, if the gap is too wide, the shielding characteristics of the braided shield formed using the conductive fibers 1 may become insufficient, so the width W2 is preferably 100 μm or less.

In the conductive fiber 1, in order to increase the adhesion between the central yarn 11 and the plating layer 12, at least one of a roughening treatment and a hydrophilic treatment is applied to the area where the plating layer 12 is formed on the surface of the central yarn 11. surface treatment including On the other hand, the plated layer 12 is not formed on the untreated region of the surface of the center yarn 11, or even if the plated layer 12 is temporarily formed, it peels off due to weak adhesion.

When the surface treatment is applied only to the area where the plating layer 12 is formed on the surface of the central thread 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 band-shaped mask. Take action. Since the area where the plating layer 12 is not formed has a band-like pattern formed in a spiral shape with intervals on the center thread 11, similarly to the area where the plating layer 12 is formed, the band-like mask is spaced on the center thread 11. It should be wound spirally while leaving a gap.

Threads and tapes made of a material resistant to surface treatment can be used as the band-shaped mask. A material that is resistant to surface treatment is, for example, a material that has the strength to withstand the impact of a propellant when blasting is used as the surface treatment, and does not easily react with chemicals when etching is used as the surface treatment. material.

Concavities and convexities are formed in the roughened region of the surface of the center thread 11 . By forming the unevenness, it becomes difficult for the catalyst to detach from the surface of the central yarn 11 in the plating process for forming the plating layer 12, and the surface area of the central yarn 11 is increased. The effect of improving the adhesion 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, thereby increasing the amount of polar functional groups that contribute to the improvement of the surface wettability.

In order to increase the effect of these roughening treatments, the arithmetic mean roughness Ra of the surface of the center 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 thread 11, for example, a blasting treatment can be used. Blasting includes dry ice blasting using dry ice particles as a propellant, sand blasting using particles such as alumina and SiC as a propellant, and wet blasting using a mixture (slurry) of water and abrasives as a propellant. can be used.

In particular, dry ice blasting is preferably used for roughening the surface of the center yarn 11 . Dry ice sublimates under normal pressure and does not remain on the surface of the center yarn 11 after treatment. Therefore, when dry ice blasting is used, a cleaning step after treatment is not required.

When blasting is used to roughen the surface of the center yarn 11, the particle diameter of the blasting propellant, the blasting pressure (spraying pressure), the distance between the injection nozzle of the blasting device and the insulator, the hardness of the center yarn 11, The arithmetic mean roughness Ra of the surface of the center thread 11 can be controlled by adjusting the thickness.

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 center thread 11 can be controlled by the laser spot diameter or the like.

Further, when the arithmetic average roughness Ra of the surface of the resin fiber 10 and the center yarn 11 can be controlled by controlling the reaction rate between the chemical solution and the center yarn 11 by controlling the concentration and temperature of the chemical solution, a sodium naphthalene complex solution or chromium A wet etching treatment using a chemical solution such as an acid solution may be used for the roughening treatment of the center thread 11 . However, if the center thread 11 is made of polyethylene or fluorine-based resin, the etching process using a chromic acid solution is not realistic because the process takes a long time.

The arithmetic mean roughness Ra of the surface of the center thread 11 can be measured with a laser microscope or the like.

In addition, a polar functional group is generated in the area of the surface of the center thread 11 that has been subjected to a hydrophilic treatment, and the wettability of that area is improved. Here, the polar functional group is a polar functional group (hydrophilic group) such as a carbonyl group or a hydroxy group. Polar functional groups include functional groups containing oxygen, such as carbonyl groups and hydroxyl groups, as well as functional groups containing nitrogen instead of oxygen. In general, the presence of polar functional groups is directly related to surface wettability (see, for example, Akira Nakashima, Solid Surface Wettability: From Superhydrophilicity to Superhydrophobicity (Kyoritsu Shuppan Co., Ltd., 2014)).

By improving the wettability of the surface of the center thread 11, the catalyst solution and the plating solution used for the plating process can easily come into contact with the surface of the center thread 11 over the entire circumference. As a result, the adhesion between the plated layer 12 and the center thread 11 is improved.

Hydrophilization treatment of the surface of the center thread 11 includes, for example, corona discharge exposure, plasma exposure in a gas mixed with atmospheric composition gas or rare gas, ultraviolet irradiation, electron beam irradiation, gamma ray irradiation, X-ray irradiation, and ion beam. Irradiation, ozone-containing liquid immersion, etc. can be used.

The conductive fiber 1 is, for example, a braided shield used for various cables such as harnesses for EV vehicles, harnesses for robots, electromagnetic shield wires for medical probes, cords for lightweight earphones, copper wires 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 with a braided shield composed of a plurality of braided conductive fibers 1. FIG.

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

A braided shield made of the conductive fibers 1 is much lighter than a braided shield made entirely of metal, so that a cable or the like including it can be made lighter. Further, for example, by using a braided shield made of the conductive fibers 1, the total weight of an EV vehicle or a robot can be reduced, so power can be saved.

(Method for producing conductive fiber)
An example of a method for manufacturing the conductive fiber 1 according to the first embodiment will be described below.

FIG. 4 is a schematic diagram showing the configuration of a plating system 100 used for forming the plating layer 12. As shown in FIG. 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 electroplating unit 160, and a center thread 11. and bobbins 170a-170m for transporting.

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

The degreasing unit 110 is for removing oil from 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, surfactant, and the like. At least a portion of the bobbin 170b is located in the degreasing liquid 112 to transport the center thread 11 through the degreasing liquid 112 .

The surface treatment unit 120 is for applying a surface treatment to the center yarn 11 and includes a surface treatment device 121 . Examples of the surface treatment apparatus 121 include a blasting apparatus, a laser apparatus, an etching apparatus using chromic acid, sulfuric acid, etc. as an etchant for roughening, a corona treatment apparatus for hydrophilization, a plasma treatment apparatus, 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 or the like as an etchant, and the like are used.

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

The first activation unit 130 is for forming a catalytically active layer on the surface of the center yarn 11, and includes a first activation tank 131 and a first activation liquid 132 contained in the first activation tank 131. and 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, high-quality plating layer 12 . At least a portion of the bobbin 170f is located in the first activating liquid 132 to transport the center thread 11 through the first activating 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 contains a second activation tank 141 and a and a second activation liquid 142 . The second activation liquid 142 is, for example, sulfuric acid. At least a portion of the bobbin 170h is located in the second activating liquid 142 to transport the center thread 11 through the second activating liquid 142 .

The electroless plating unit 150 forms an electroless plating layer before electroplating to make the surface of the center thread 11 (the surface of the catalytically active layer) conductive. and an electroless plating solution 152 contained in an electrolytic plating bath 151 . The electroless plating solution 152 contains, for example, copper sulfate, Rossell salt, formaldehyde, sodium hydroxide, and the like. At least a portion of the bobbin 170j is located in the electroless plating solution 152 to transport the center thread 11 through the electroless plating solution 152 .

The electroplating unit 160 is for performing electroplating, 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 compositions and manufacturing methods of a copper sulfate (CuSO ₄ ) plating solution and a 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 chlorides.

First, about 60 to 70% by volume of water of the entire plating solution is added to the sufficiently washed electrolytic plating tank 161, and then the water temperature is raised from room temperature to about 50.degree. Next, an amount of copper sulfate corresponding to the required amount of plating deposition, which depends on the desired thickness of the plating layer 12 and the size and length of the central thread 11, is put into the warm water and stirred until dissolution is completed. 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, add the required amount of sulfuric acid while stirring, and then finally reach the required amount of plating solution. Add water up to Also, in order to remove impurities in the plating solution, activated carbon is added or after forming an activated carbon layer on the filter material of the filter, the activated carbon is circulated through the filter to remove the impurities.

Next, sodium chloride, hydrochloric acid, or the like is appropriately added to the plating solution in order to adjust the chloride ion concentration, which improves the surface gloss of the plating layer, to a predetermined value. Then, analyze and confirm whether sulfuric acid and copper sulfate are at the specified concentration. Next, after appropriately adding additives such as brighteners and surfactants corresponding to the material of the center thread 11, Hull cell test ” and “Hidehiko Enomoto, Naoji Furukawa, Sojun Matsumura, Composite Plating, Nikkan Kogyo Shimbun”), and check the condition of the plating solution to see if the desired plating layer can be obtained. Finally, after conducting air electrolysis at about 10 A/dm ² for several hours while performing continuous filtration, it is confirmed whether or not a stable plating film can be formed.

When a copper sulfate plating solution is used as the electrolytic plating solution 162 to generate Cu ions as Cu atoms (metal), a reaction represented by Equation 1 below occurs. Equation 2 expresses that a divalent Cu cation becomes a Cu atom (metal) by accepting two electrons.

In the reaction represented by 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 is about 192,971 C, which is twice the . Therefore, considering the atomic weight of copper, which is 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 remaining in the bath without reacting with copper cyanide.

First, about 60% of the total plating solution is filled with pure water from which impurity components such as sulfur and chlorine have been removed, in a preliminary bath. Next, sodium cyanide or potassium cyanide is put into pure water and dissolved to form an aqueous alkali cyanide solution. Further, cuprous cyanide made into a pasty state using pure water is added to and dissolved in the alkaline cyanide aqueous solution while stirring. Further, for the purpose of suppressing cyanide decomposition, potassium hydroxide or sodium hydroxide is added to adjust the pH and electrical conductivity of the plating solution. Next, while heating to 40 to 70° C., which is close to the temperature of the plating solution during the plating process, activated carbon or the like is added, and the mixture is sufficiently stirred and allowed to stand to settle the activated carbon that has adsorbed the impurities. Then, after removing impurities such as activated carbon through a filtering device, the solution is transferred to a plating bath, and then pure water is added to adjust the solution volume to obtain a plating solution.

Next, this plating solution is analyzed, and additive materials are added as necessary in order to improve and stabilize the plating performance. Specifically, an appropriate amount of sodium carbonate or potassium carbonate is added as a pH buffer and adjuster. In addition, potassium sodium tartrate (Rochelle salt) is added in order to facilitate the dissolution of the copper anode and efficiently supply copper ions. Finally, a stainless steel plate is suspended as a cathode and a rolled copper plate for plating as an anode, 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 to generate Cu ions as Cu atoms (metal), a reaction represented by the following Equation 2 occurs. Formula 2 expresses that a monovalent Cu cation becomes a Cu atom (metal) by accepting one electron.

In the reaction represented by Formula 2, one electron is 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 is approximately 96,485 C (corresponding to the Faraday constant). Therefore, considering the atomic weight of copper, which is 63.54, the amount of charge required to form 1 g of copper is approximately 1,518 C/g.

As shown in Equation 3 below, the current i is represented by the amount of charge Q and the time t. Therefore, if the current density of electrolytic plating is the same, in principle, when using a copper cyanide plating solution containing copper ions with a low valence (valence +1) as the electrolytic plating solution 162, the copper sulfate plating solution The plating layer 12 can be formed in half the time of using . Therefore, if the voltage and current used during electroplating are constant, the power consumption, which is directly related to the plating time, can be halved, and the energy cost can be reduced. In addition, since the factory operating time in the electroplating process is halved, labor costs can be expected to be reduced relative to the number of production units.

_The plating solution that can be used as the electrolytic plating solution 162 is not limited to the above _- described copper sulfate plating solution or copper cyanide _plating solution. _A copper _borofluoride plating solution prepared by _mixing , _Cu2P2O7.3H2O , _{K4P2O7.3H2O , NH4OH} , _KNO3 , _{Cu metal} , etc. may be a pyrophosphate plating solution. Moreover, the plating solution may be a combination of two or more of these plating solutions.

Anode 163 is immersed in electrolytic plating solution 162 . The anode 163 is a supplier of copper ions in electroplating, and is produced, for example, by rolling and casting molten copper (blister copper with a purity of about 99%) made from copper hot water. In addition, a seed plate electrolysis is performed using blister copper as the anode and a stainless steel or titanium plate as the cathode, and the copper deposited on the surface of the cathode is stripped off. It may also be used as anode 163 .

A bobbin 170k and a bobbin 170m positioned above the electrolytic plating bath 161 are conductive and function as cathodes. The bobbin 170l located in the electrolytic plating solution 162 is insulating. The power supply unit 164 applies a DC voltage between the anode 163 and the cathode bobbins 170k and 170m.

While a DC voltage is applied between the node 163 and the bobbins 170k and 170m, the central yarn 11 is transported and passed through the electroplating solution 162 to form the electroless plating layer on the surface of the central yarn 11. An electrolytic plated layer is formed to obtain the plated layer 12 .

It should be noted that the transfer mechanism for the central thread 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 electroplating solution 162, the central thread 11 is bent into a shape having a predetermined curvature or multiple curvatures and laid in the electroplating solution 162, pushed out from one side, and pulled from the other side to be transported. It may be a mechanism that Furthermore, without providing a transfer mechanism, the bundled center threads 11 are immersed in the electrolytic plating solution 162, connected to the cathode electrode, and appropriately swung to cover the entire surface of the center threads 11 with the electrolytic plating solution 162. Electroplating may be performed by contacting with .

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

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

FIG. 5 is a schematic diagram showing the appearance of the center thread 11 with a mask 13 wrapped around its surface to protect the areas not subjected to surface treatment. The width of the mask 13 in the longitudinal direction of the central thread 11 is W2 because the mask 13 covers the area where the surface treatment is not applied, that is, the area where the gaps are formed in the plating layer 12 . On the other hand, the area not covered with the mask 13 is the area where the surface treatment is applied, that is, the area where the plating layer 12 is formed. .

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, for example, 40 to 60.degree. As a result, oil and fat adhering to the surface of the center thread 11 is removed.

In the next surface treatment step, if a treatment that has the effect of removing oil and fat from the surface of the center yarn 11, such as roughening treatment by blasting, the degreasing step by the degreasing unit 110 can be omitted.

Next, in the surface treatment unit 120, the center yarn 11 is subjected to a roughening treatment by blasting and a hydrophilization treatment by exposure to corona discharge. At this time, the surface treatment is performed while the surface of the center thread 11 is covered with the belt-shaped mask, so that only the area of the surface of the center thread 11 not covered with the mask is applied. That is, the surface treatment is applied to a region having a belt-like pattern spirally wound around the central thread 11 with a gap therebetween, which is the region where the plating layer 12 is formed.

In the blasting process, a propellant such as dry ice is injected from an injection 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 mean roughness Ra of the surface of the resin fiber 10 and the center yarn 11, the particle size of the blasting propellant, the blasting pressure, the distance between the tip of the blasting nozzle and the insulator. etc. can be set as appropriate. For example, when dry ice blasting is performed, 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 thread 11 to the tip of the injection nozzle is set in the range of 0 to 10 cm. Also, dry ice blasting is carried out under temperature conditions ranging from -80°C to room temperature.

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

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

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

Next, in the first activation unit 130, the center 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, 30-40.degree. Thereby, a catalytically active layer is formed on the surface of the center thread 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 adhered to the surface of the central thread 11, and catalytic activity is achieved. form a layer. At this time, a catalytically active layer is not formed to a sufficient degree for the subsequent plating treatment in the areas where the surface treatment is not applied.

Next, in the second activation unit 140, the center 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, 30-50.degree. As a result, for example, Sn that reduces the activity can be removed from the catalytically active layer on the surface of the center yarn 11, and the activity of the catalytically active layer can be increased.

Next, in the electroless plating unit 150, the center thread 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, 20-30.degree. As a result, an electroless plated layer as a seed layer for electroplating is formed on the surface of the center thread 11, and the surface of the center thread 11 is made conductive. The longer the immersion time in the electroless plating solution 152, the thicker the electroless plating layer. At this time, the electroless plated layer is not formed in the region where the surface treatment is not performed, or the layer is formed in a state where the adhesion to the central yarn 11 is weak.

Next, in the electroplating unit 160, the center yarn 11 is immersed in the electroplating solution 162 for 3 minutes or less. The thickness of the electroplating layer can be controlled by the transfer speed of the center thread 11 and the immersion time in the electroplating solution 162 . The transfer speed and immersion time of the center thread 11 are determined according to the desired thickness of the plating layer 12, the management status of the plating bath (the plating solution in the state of being contained in the plating bath), the change over time of the plating bath, etc., and the current density , the concentration of the plating bath, pH, temperature, the type of additives, etc. are considered and optimized.

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

By the electroplating described above, an electroplated layer is formed on the surface of the electroless plated layer. The plated layer 12 is composed of a laminate of the electroless plated layer and the electrolytic plated layer. Here, the plated layer 12 is not formed on the area of the surface of the central yarn 11 that is not surface-treated, or even if the plated layer 12 is temporarily formed, it peels off due to weak adhesion. That is, the plating layer 12 is formed only on the surface-treated region of the surface of the center thread 11 . Conductive fiber 1 according to the present embodiment is obtained through the above steps.

Although not shown in FIG. 4, the center yarn 11 is cleaned (ultrasonic cleaning, ultrasonic cleaning, oscillating washing, running water washing, etc.) is preferably performed.

Also, in order to obtain a suitable transfer speed of the center thread 11 in each process, it is preferable to optimize the number of revolutions by adjusting the gear ratio (radius of rotation) for each of the bobbins 170a to 170m. Therefore, it is preferable to provide a rotation mechanism with a buffer between each unit so that the transfer speed can be changed and the temporary standby can be optionally carried out in the inter-process route.

(Effect of Embodiment)
According to the above embodiment, the conductive fiber has a center thread made of a resin fiber and a 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.

(Summary of embodiment)
Next, technical ideas understood from the embodiments described above will be described with reference to the reference numerals and the like in the embodiments. However, each reference numeral and the like in the following description do not limit the constituent elements in the claims to the members and the like specifically shown in the embodiment.

[1] A central yarn (11) composed of one resin fiber (10) or a plurality of twisted resin fibers (10), and a plated layer (12) directly covering the surface of the central yarn (11) A conductive fiber (1) comprising a plated layer (12) having a belt-like pattern formed spirally at intervals on a central thread (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 [1] above, which is within the range of

[3] The conductive fiber (1) according to the above [1] or [2], wherein the plated 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), covering the circumference of the electric wire (21), and a jacket (23) covering the braided shield (22) And, the conductive fiber (1) is a central yarn (11) made of one resin fiber (10) or a plurality of twisted resin fibers (10), and the surface of the central yarn (11) is directly a covering plating layer (12), the plating layer (12) having a strip-like pattern formed spirally with spaces on the central thread (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 thread (11) to the width of the band in the longitudinal direction of the central thread (11) is 1 or more and 4 or less. The cable (20) of [4] above, wherein the cable (20) is in the range of

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

[7] Surface treatment including at least one of roughening treatment and hydrophilization treatment is applied to the surface of the central yarn (11) composed of one resin fiber (10) or a plurality of twisted resin fibers (10). and after the surface treatment, the surface of the central yarn (11) is plated to form a plated layer (12), wherein the surface treatment causes the central yarn (11) to have a gap. A conductive fiber that is applied to a region having a belt-like pattern formed in a spiral shape with spaces, and a plating layer (12) is formed only on the surface-treated region of the surface of the central yarn (11). The manufacturing method of (1).

[8] The method for producing a conductive fiber (1) according to [7] above, wherein the surface treatment is carried out with a band-shaped mask covering the area not subjected to the surface treatment.

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 scope of the invention.

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

REFERENCE SIGNS LIST 1 conductive fiber 10 resin fiber 11 center thread 12 plating layer 20 cable 21 electric wire 22 uneven shield 23 jacket

Claims (7)

a center yarn in which a plurality of resin fibers made of polyethylene or fluorine resin are twisted ;
a plating layer that directly covers the surface of the central thread;
with
The plated layer has a belt-like pattern formed in a spiral shape with spaces on the central thread ,
On the surface of the center thread on which the plating layer is formed, irregularities having an arithmetic mean roughness Ra of 2 μm or more and 14 μm or less are formed along the strip-shaped pattern formed in a spiral shape.
conductive fiber. In the pattern of the plating layer, the ratio of the width of the gap in the longitudinal direction of the central thread to the width of the band in the longitudinal direction of the central thread 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 or 2. an electric wire;
a braided shield made of a plurality of braided conductive fibers and covering the wire;
a jacket covering the braided shield;
with
The conductive fibers are
a central yarn obtained by twisting a plurality of resin fibers made of polyethylene or fluorine-based resin ;
a plating layer that directly covers the surface of the central thread;
with
The plated layer has a belt-like pattern formed spirally with intervals on the central thread ,
On the surface of the center thread on which the plating layer is formed, irregularities having an arithmetic mean roughness Ra of 2 μm or more and 14 μm or less are formed along the strip-shaped pattern formed in a spiral shape.
cable. In the pattern of the plating layer, the ratio of the width of the gap in the longitudinal direction of the central thread to the width of the band in the longitudinal direction of the central thread is in the range of 1 or more and 4 or less.
Cable according to claim 4. The plating layer is made of copper or silver,
Cable according to claim 4 or 5. a step of applying a surface treatment including a roughening treatment and a hydrophilization treatment to the surface of a central yarn obtained by twisting a plurality of resin fibers made of polyethylene or fluororesin ;
After the surface treatment, a step of plating the surface of the center thread to form a plating layer;
including
In the step of applying the surface treatment, the surface of the central yarn is subjected to the roughening treatment by dry ice blasting in a state where the circumference of the central yarn is spirally covered with a band-shaped mask while leaving a gap. forming irregularities having an arithmetic mean roughness Ra of 2 μm or more and 14 μm or less along a spiral belt-like pattern on the surface of the central yarn,
In the step of forming the plated layer, the plated layer is formed on the roughened region of the surface of the center yarn.
A method for producing a conductive fiber.

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