JP2016212960A - Polymer fiber conductive wire and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer fiber conductive wire with high utility that has excellent bending resistance and shows stable characteristics for a long term even if used in a bent state.SOLUTION: A polymer fiber conductive wire 1 comprises a high strength polymer fiber 2 comprising a bulk material of many filaments 21 with a tensile strength of 250 kg/mmor more and a metal plating film 3 formed on the surface of the high strength polymer fiber 2. The diameter of each of the filaments 21 is 20 μm or less, and the average film thickness of the metal plating film 3 composed of an electroless copper plating film 31 and an electrolytic copper plating film 32 covering each surface of the filaments 21 is 3 μm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polymer fiber conductive line for a signal line and a manufacturing method thereof.

  As an electric wire material replacing a conventional metal wire, a polymer fiber conductive wire in which a copper surface is plated on a fiber surface made of a synthetic polymer has been proposed. As an example, Patent Document 1 discloses an electric wire in which a plurality of strands obtained by performing metal plating on high-strength fibers are twisted to form a conductor portion and covered with an insulating covering portion.

  Further, in Patent Document 2, as a method of manufacturing a composite electric wire including high-strength continuous long fibers, a step of maintaining a position of a plurality of high-strength continuous long fibers while being separated, and a conductive material for the high-strength continuous long fibers And a method of forming a fiber bundle in which the plated high-strength continuous long fibers are twisted together, and a step of collecting the continuous high-strength fibers and continuously collecting them.

JP 2012-104404 A JP 2012-129092 A

  Polymer fiber conductive wire is lighter than metal wire, so it can be used in various fields where miniaturization and weight reduction are required, such as automobile equipment, nursing robots and robot suits for work support. There is expected.

  However, it is not easy to form a uniform metal plating film on the entire surface of many filaments constituting the polymer fiber. In particular, in a device having a movable part such as an arm of a robot, the metal plating film on the bent part may be deteriorated by the repeated movement of the movable part. In such an application, a polymer fiber conductive wire having practically sufficient durability has not yet been obtained.

  The present invention has been made in view of such a background, and an object of the present invention is to provide a highly practical polymer fiber conductive wire that has excellent bending resistance and can maintain stable characteristics over a long period of time.

One aspect of the present invention is a polymer fiber conductive wire comprising a high-strength polymer fiber and a metal plating film formed on the surface of the high-strength polymer fiber,
The high-strength polymer fiber is an aggregate of a large number of filaments composed of synthetic polymer fibers having a tensile strength of 250 kg / mm ² or more, and the electroless copper plating is formed by covering the surface of each filament with the metal plating film. It consists of a film | membrane and an electrolytic copper plating film | membrane, The diameter of the said filament is 20 micrometers or less, The average film thickness of the said metal plating film is 3 micrometers or less, It is characterized by the above-mentioned.

Another aspect of the present invention is a high-strength polymer fiber that is an aggregate of a large number of filaments composed of synthetic polymer fibers having a tensile strength of 250 kg / mm ² or more, and electroless copper formed on the surface of the high-strength polymer fiber A method for producing a polymer fiber conductive wire having a metal plating film comprising a plating film and an electrolytic copper plating film,
A pre-treatment step of treating the aggregate of a large number of filaments with a solution containing a cationic surfactant after washing with hot water;
An electroless copper plating process in which the aggregate of the filaments is immersed in the order of a catalyst application solution, an activation solution, and an electroless copper plating solution, and the surface of each pretreated filament is covered with an electroless copper plating film. When,
An electrolytic copper plating step of performing electroplating in an electrolytic copper plating solution on the assembly of the numerous filaments to form an electrolytic copper plating film on the electroless copper plating film;
It is characterized by providing.

  The polymer fiber conductive wire of the present invention uses a high-strength synthetic polymer fiber, and is an aggregate in which the surface of each ultrafine filament of 20 μm or less is covered with an extremely thin metal plating film of 3.0 μm or less. Flexibility can be improved while ensuring initial characteristics of the wire.

  Therefore, an increase in resistance value due to long-term use is suppressed, and it is suitably used for signal lines for various devices having a bent portion and a movable portion, thereby realizing practically sufficient durability.

  As a method for producing such a polymer fiber conductive wire, prior to the formation of the metal plating film, pretreatment with hot water and a cationic surfactant forms an electroless copper plating film on the entire surface of each filament. In the subsequent process, the electrolytic copper plating film can be formed uniformly.

  Therefore, according to the present invention, it is possible to improve the bending resistance of the metal plating film of the polymer fiber conductive wire and to obtain a highly practical signal line material that can be used for a bent portion or a movable portion that repeatedly bends.

The pseudo-schematic diagram which shows the whole structure of the polymer fiber conductive wire in Embodiment 1, and its radial direction and longitudinal direction cross section. The manufacturing process figure of the polymer fiber conductive wire in Embodiment 1. FIG. Schematic diagram for explaining the bending durability test method in the examples The figure which shows the relationship between the frequency | count of bending and resistance value of the comparative example 1 (sample 1). The figure which shows the relationship between the frequency | count of bending of Test Example 1 (sample 2), and resistance value. The figure which shows the relationship between the frequency | count of bending of Example 1 (sample 3), and resistance value. The figure which shows the relationship between the frequency | count of bending of Example 1 (sample 5), and resistance value. The figure which shows the relationship between the frequency | count of bending of Example 1 (sample 6), and resistance value. The figure which shows the relationship between the frequency | count of bending of Example 1 (sample 7), and resistance value. The scanning electron microscope (SEM) photograph which shows the cut surface of the polymer fiber conductive wire of Test Example 1 (sample 5). The figure which shows the relationship between the frequency | count of bending of Example 2 (sample 9), and resistance value. The fiber shape photograph for observing the plating state of the polymer fiber conductive wire of Comparative Example 2 (Sample 10).

(Embodiment 1)
FIG. 1 shows a schematic structure of the polymer fiber conductive wire 1 of this embodiment, and the high-strength polymer fiber 2 is composed of an assembly of a large number of filaments 21. Each filament 21, which is a single fiber of synthetic polymer, is covered with the metal plating film 3 on the entire outer peripheral surface, and a large number of these coated fibers are gathered in a bundle to form a polymer fiber conductive wire 1. The metal plating film 3 has a two-layer structure of an electroless copper plating film 31 and an electrolytic copper plating film 32 from the filament 21 side.

The fiber constituting the high-strength polymer fiber 2 is a synthetic polymer fiber having a tensile strength of 250 kg / mm ² or more, and preferably has a tensile strength of 300 kg / mm ² or more. Examples of such synthetic polymer fibers include polyarylate fibers and para-aramid fibers. The polyarylate fiber and the para-aramid fiber are fibers having high strength and high elastic modulus and low specific gravity with respect to the metal, and thus contribute to weight reduction and durability improvement of the polymer fiber conductive wire 1. Each filament 21 made of a synthetic polymer fiber has a fine diameter, particularly a diameter of 20 μm or less, and is necessary even if the fiber surface area with respect to the cross-sectional area of the polymer fiber conductive wire 1 is increased and the film thickness of the metal plating film 3 is reduced. Ensure resistance value characteristics.

  The plating conditions of the metal plating film 3 are such that the average film thickness of the electroless copper plating film 31 and the electrolytic copper plating film 32 is 3.0 μm or less, preferably 1.0 to 2.0 μm. Adjust etc. When the average film thickness exceeds 3.0 μm, the initial resistance value decreases, but the resistance value change due to repeated bending operations increases, and the bending resistance decreases. As the average film thickness is thinner, the bending resistance tends to be improved and becomes noticeable at 2.0 μm or less. However, if the average film thickness is less than 1.0 μm, the initial resistance value increases, and it is not easy to form a uniform plating film. It is not preferable.

  The reason for this is not necessarily clear, but since the cross-sectional shape of ultrafine filaments is not uniform, it is not easy to form a plating film with a constant film thickness with good adhesion. There is a possibility that the influence of the stress difference applied to the inside and the outside becomes large. When the average film thickness exceeds 3.0 μm, the flexibility decreases and the variation increases, and it is assumed that the load tends to concentrate on a part during bending.

  The polymer fiber conductive wire 1 is used as a fiber bundle in which a large number of filaments 21 are aligned in the fiber longitudinal direction, for example, as a core wire of a signal line electric wire. Specifically, depending on the required resistance characteristic, normally several hundreds of filaments 21 are gathered together and appropriately twisted to form a polymer fiber conductive wire 1 having a diameter of about several millimeters as a core wire. . The entire outer periphery may be further covered with an insulating resin to form a signal line electric wire.

  FIG. 2 shows an example of a manufacturing process of the polymer fiber conductive wire 1 and includes a pretreatment process, an electroless copper plating process, an electrolytic copper plating process, and a post-treatment process. The post-processing step can be omitted.

(Pretreatment process)
The pretreatment process includes a treatment of washing the fiber bundle to be the high-strength polymer fiber 2 with hot water and a treatment of immersing in a solution of a cationic surfactant. By performing the hot water washing treatment in advance, the fiber can be softened and opened easily, and the subsequent cationic surfactant treatment can be carried out in a state where many filaments 21 are loosened. The hot water temperature can be appropriately selected in the range of 40 to 80 ° C.

  The cationic surfactant is not particularly limited, and known ones such as a quaternary ammonium salt are used. A solution containing a cationic surfactant is heated to a temperature equivalent to the hot water washing temperature and adjusted to an appropriate pH.

  The effect of the treatment with the cationic surfactant is not always clear, but the cationic surfactant adsorbed on the hot-washed filament surface improves the flexibility and smoothness of the fiber surface. Therefore, in the subsequent process, the catalyst solution is likely to enter between a large number of filaments 21, and the catalyst is evenly applied to the fiber surface, so that electroless copper plating proceeds well and prevents unattached portions from occurring. Is done.

(Electroless copper plating process)
In the electroless copper plating step, the pretreated polymer fiber conductive wire 1 is dipped in the order of the catalyst application liquid, the activation liquid, and the electroless copper plating liquid. The catalyst-providing liquid is an aqueous solution containing a noble metal compound such as Pd, and the noble metal ions adsorbed and supported on the surface of each filament 21 are activated (reduced) by being immersed in an activation liquid such as hypophosphite. ) Then, by immersing in a known electroless copper plating solution, copper is deposited on the surface of each filament 21 by the activated catalyst, and the electroless copper plating film 31 is formed.

(Electro copper plating process)
In the electrolytic copper plating step, the polymer fiber conductive wire 1 is immersed in an activation liquid such as sulfuric acid, the surface is activated, and further, electroplating is performed in a known electrolytic copper plating liquid. As a result, the copper electroplating film 32 is formed using the copper deposited in the electroless copper plating step as a core, and the polymer fiber conductive wire 1 in which each filament 21 of the high-strength polymer fiber 2 is covered with the metal plating film 3 is formed. can get. The treatment with the activation liquid can be omitted when the electrolytic copper plating process is subsequently performed after the electroless copper plating process and the contact time between the fiber surface and the air is short.

(Post-processing process)
Preferably, the obtained polymer fiber conductive wire 1 can be further heat-treated to further improve the bending resistance. The heating temperature is appropriately set according to the synthetic polymer fiber used in order to suppress the strength reduction of the high-strength polymer fiber 2. For example, in the case of polyarylate fiber, the temperature is lower than its softening point (320 ° C.). Preferably, the temperature may be a temperature at which an increase in resistance due to surface oxidation during heat treatment can be suppressed, for example, 250 ° C. or less.

  The post-treatment step is performed by heating in the air, but can also be performed in a reducing atmosphere. By heating in a reducing atmosphere, for example, in a hydrogen or nitrogen gas atmosphere, surface oxidation of the metal plating film 3 due to post-treatment can be prevented.

  According to the production process of FIG. 2, a metal plating film 3 was formed on the surface of the high-strength polymer fiber 2, and the resulting polymer fiber conductive wire 1 was subjected to a bending durability test to evaluate its characteristics.

(Test Example 1)
According to the manufacturing process of FIG. 2, the polymer fiber conductive wire 1 in which the surface of the filament 21 of the high-strength polymer fiber 2 was covered with the metal plating film 3 was manufactured. As the high-strength polymer fiber 2, a commercially available polyarylate fiber (Vectran (registered trademark) manufactured by Kuraray Co., Ltd .; tensile strength 330 kg / mm ² , filament diameter 16 to 17 μm, 1670 dtex, 600 to 601) is used. The processing conditions shown in Tables 2 and 3 were performed.

  First, as a pretreatment step, the high-strength polymer fiber 2 is washed with hot water at 60 ° C. for 10 minutes, and then a solution of a cationic surfactant (Neofix R-800 manufactured by Nikka Chemical Co., Ltd.) (concentration 40 g / L, pH 11). , 60 ° C.) for 5 minutes.

  Next, as an electroless copper plating step, a catalyst-providing solution containing Pd ions (OPC-50 Inducer A manufactured by Okuno Pharmaceutical Co., Ltd .; concentration 50 ml / L, OPC-50 inducer C; concentration 50 ml / L, pH 12, 40) C.) and the pretreated high-strength polymer fiber 2 was immersed for 5 minutes and then immersed in a sodium hypochlorite solution (concentration 50 g / L, 60 ° C.) for 5 minutes for activation treatment. Then, electroless copper plating solution (Okuno Pharmaceutical Co., Ltd. OPC Copper-AF-M; Concentration 150 ml / L, OPC Copper-AF-1; Concentration 100 ml / L, OPC Copper-AF-2; Concentration 40 ml / L, pH 9.5, 50 ° C.) for 10 minutes to form an electroless copper plating film 31.

  Furthermore, as an electrolytic copper plating process, after activating by immersing in a sulfuric acid solution (concentration 3%, room temperature) for 5 minutes, an electrolytic copper plating solution (copper sulfate 70 g / L, sulfuric acid 200 g / L, chlorine, 25 ° C.) Ion 50mg / L, manufactured by Okuno Pharmaceutical Co., Ltd. Top Lucina Makeup 5ml / L, Top Lucina LS-A 2.5ml / L, Top Lucina LS-B 1.0ml / L) 32 was formed.

  The average film thickness of the metal plating film 3 is adjusted to 1.6 μm (Samples 2 and 5), 3.0 μm (Samples 3 and 6), 6.0 μm (Sample 4 and The polymer fiber conductive wire 1 changed to 7) was obtained. Here, the average film thickness is a numerical value calculated from the weight before and after the formation of the metal plating film 3 and the surface area of the high-strength polymer fiber 2. Among them, samples 2 to 4 were subjected to stranded wire processing (50 times / m), and samples 5 to 7 were not subjected to stranded wire processing.

A plurality of these samples 2 to 7 were prepared (n = 3 to 4), and a bending durability test using an MIT type bending resistance tester was performed. As shown in FIG. 3, a sample S having a length of 50 cm is suspended to fix the upper end, and the lower end is gripped from both sides by a chuck portion 101 provided on the rotating plate 100, and the rotating plate 100 is rotated and reciprocated at a predetermined angle. The operation of bending the sample S left and right with a predetermined load applied was repeated. The test conditions were as follows.
Load: 250g
Bending angle: 90 °
Bending frequency: 90 times / min. Chuck width: 1.0 mm
About each sample 2-7, the resistance value change during a test was measured and it evaluated by the frequency | count of bending until the electrical resistance of a copper wire exceeded 1 ohm / 50cm. The results are shown in Table 1 together with the initial resistance value (Ω / 50 cm). Moreover, the resistance value change of sample 2, 3, 5, 6, 7 was shown to FIGS.

(Comparative Example 1)
For comparison, a bending endurance test using a MIT-type folding resistance tester was performed on a copper wire (diameter 400 μm × 7), which is a conventional electric wire material, in the same manner as in Test Example 1 (Sample 1). The results are shown in Table 1 together with the initial resistance value (Ω / 50 cm).

(Evaluation)
As is clear from Table 1, the number of bendings of sample 1 (n = 3) was 260 to 458, both of which were 500 times or less and the resistance value exceeded 1 Ω / 50 cm. Moreover, all the seven copper wires of Sample 1 were disconnected. As shown in FIG. 4, all of them are almost equal to the initial resistance value until just before the disconnection, and then the resistance value rapidly rises to the disconnection.

  In the samples 2 to 7 using the polymer fiber conductive wire 1 in comparison with the conventional sample 1 using the copper wire, the number of bendings until the resistance value exceeds 1Ω is 5000 times or more and 10 times or more that of the sample 1. Showed durability. Sample 3 (3-1 to 3-4; average film thickness of 3.0 μm) is compared to the number of flexing cycles 5799 to 8370 of sample 4 (4-1 to 4-4; twisted) having an average film thickness of 6.0 μm. Twisted) is the number of flexing times 8278 to 11164, 1.6 μm of sample 2 (2-1 to 2-3; with twisting), the number of flexing times 11939 to 16669, and the average film thickness of the metal plating film 3 is reduced, The number of bends has increased.

  This tendency is the same for the untwisted samples 5 to 7, and the sample 5 (5-1 to 5-3) having an average film thickness of 1.6 μm is a sample having the number of bendings 26318 to 115419 and an average film thickness of 3.0 μm. 6 (6-1 to 6-3) is the number of bendings 11318 to 15796, and the sample 7 (7-1 to 7-3) of 6.0 μm is the number of bendings 5573 to 5995, in particular, the average of the metal plating film 3 When the film thickness is 3.0 μm or less, the number of bendings is about 10,000 or more and the bending resistance is greatly improved.

  In addition, when the average film thickness is 3.0 μm or less (see FIGS. 5 to 8), in the sample 7 (see FIG. 9) having an average film thickness of 6.0 μm, the initial resistance is increased even when the resistance value increases rapidly around 5000. Resistance change and variation from the value are small, and good resistance value characteristics can be obtained. In addition, when the average film thickness is 3.0 μm or less, the samples 5 and 6 without twisting tend to have a slightly larger number of bendings, and the samples 2 and 3 with twisting have a lower number of bendings due to the stress of twisting. It is presumed that

  FIG. 10 is a cut surface (SEM image) of the sample prepared by embedding the polymer fiber conductive wire 1 of the sample 5 (average film thickness 1.6 μm) in the resin, and the entire outer periphery of each filament 21 of the high-strength polymer fiber 2. It can be seen that the metal plating film 3 is uniformly formed.

(Test Example 2)
Next, after forming the metal plating film 3 on the high-strength polymer fiber 2 in the same manner as in the samples 2 and 3, heat treatment (200 ° C., 3 hours) is performed as a post-processing step, and the polymer fiber conductive wire 1 is formed. Obtained (samples 8 and 9). A plurality of samples 8 and 9 (n = 3 to 5) were evaluated by the same bending durability test, and the results are shown in Table 4. Moreover, the resistance value change of the sample 9 is shown in FIG.

(Evaluation)
As is apparent from Table 4 and FIG. 11, by adding a heat treatment step, the number of bendings of Sample 8 (8-1 to 8-3; average film thickness 1.6 μm) is 12920 to 35680, and Sample 9 (9− 1-9-5; average film thickness of 3.0 μm) is 14259 to 34098, which is greater than the samples 2 and 3 that are not heat-treated, and the bending resistance is improved.

  In addition, in the bending endurance test, when the resistance values of the polymer fiber conductive wires 1 of Samples 2 to 9 were continuously measured, all of them exceeded 1 Ω / 50 cm and then gradually increased, but the copper wire of Comparative Example 1 There was no disconnection.

(Comparative Example 2)
Furthermore, in order to confirm the effect of the pretreatment step, the polymer fiber conductive wire 1 in which the metal plating film 3 is formed on the high-strength polymer fiber 2 in the same manner as the sample 5 except that the treatment with the cationic surfactant is not performed. (Sample 10) was obtained. As shown in FIG. 12, when the surface of the sample 10 was observed, there was a portion where the metal plating film 3 was not partially formed (outlined), and when a cationic surfactant was not used, It was found that an unattached part was produced and the electro copper plating was not performed well.

  As described above, the polymer fiber conductive wire 1 according to the present invention has high strength and bending resistance by forming the metal plating film 3 of a uniform thin film on the surface of the fine synthetic polymer fiber filament 21. Realizes durability not found in wire materials. As the synthetic polymer fiber, in addition to the polyarylate fiber used in the examples and the para-aramid fiber (for example, Kevlar (registered trademark) manufactured by Toray DuPont Co., Ltd.), any fiber can be used. Can also be suitably used.

DESCRIPTION OF SYMBOLS 1 Polymer fiber conductive wire 2 High-strength polymer fiber 21 Filament 3 Metal plating film 31 Electroless copper plating film 32 Electro copper plating film

Claims (6)

A high-strength polymer fiber, and a polymer fiber conductive wire comprising a metal plating film formed on the surface of the high-strength polymer fiber,
The high-strength polymer fiber is an aggregate of a large number of filaments composed of synthetic polymer fibers having a tensile strength of 250 kg / mm ² or more, and the electroless copper plating is formed by covering the surface of each filament with the metal plating film. A polymer fiber conductive wire comprising a film and an electrolytic copper plating film, wherein the filament has a diameter of 20 μm or less and the metal plating film has an average film thickness of 3 μm or less.   The polymer fiber conductive wire according to claim 1, wherein the high-strength polymer fiber is made of polyarylate fiber.   The polymer fiber conductive wire according to claim 1 or 2, wherein the metal plating film is obtained by heat-treating an electroless copper plating film on an electroless copper plating film.   The polymer fiber conductive wire according to any one of claims 1 to 3, wherein the high-strength polymer fiber is pretreated with a cationic surfactant. From a high-strength polymer fiber that is an aggregate of a large number of filaments composed of synthetic polymer fibers having a tensile strength of 250 kg / mm ² or more, and an electroless copper plating film and an electrolytic copper plating film formed on the surface of the high-strength polymer fiber A method for producing a polymer fiber conductive wire having a metal plating film comprising:
A pre-treatment step of treating the aggregate of a large number of filaments with a solution containing a cationic surfactant after washing with hot water;
An electroless copper plating process in which the aggregate of the filaments is immersed in the order of a catalyst application solution, an activation solution, and an electroless copper plating solution, and the surface of each pretreated filament is covered with an electroless copper plating film. When,
An electrolytic copper plating step of performing electroplating in an electrolytic copper plating solution on the assembly of the numerous filaments to form an electrolytic copper plating film on the electroless copper plating film;
A method for producing a polymer fiber conductive wire.   The method for producing a polymer fiber conductive wire according to claim 5, further comprising a post-treatment step of heat-treating the aggregate of the plurality of filaments at a temperature of 250 ° C. or less after the electrolytic copper plating step.