WO2020261916A1

WO2020261916A1 - Flexible wire

Info

Publication number: WO2020261916A1
Application number: PCT/JP2020/022085
Authority: WO
Inventors: 英輝森内; 仁朗白鳥; 高橋　真一; 一樹石原
Original assignee: 株式会社巴川製紙所
Priority date: 2019-06-27
Filing date: 2020-06-04
Publication date: 2020-12-30
Also published as: JPWO2020261916A1; JP7323613B2

Abstract

In order to address the problem of providing a flexible wire that has superior flexibility, does not break easily, and can be made more compact (so as not to stand out), the present invention provides a flexible wire (1) comprising: a conductive structure (20) that includes a plurality of metal fibers, which are bound to one another in at least one section; and an outer layer covering section (3) that covers the conductive structure (20), wherein the outer layer covering section (3) is formed from a resin material that is filled in between the plurality of metal fibers making up the conductive structure (20).

Description

Flexible electric wire

The present invention relates to a flexible electric wire.

Flexible electric wires are suitably used for wiring of devices having bent portions such as bending and stretching, such as body-mounted devices and clothes-wearing devices, including the robot field.

Examples of the flexible electric wire include a flexible electric wire that can be used in the field of robots and the like and is composed of a core portion, a conductor portion, a covering portion, and the like (Patent Document 1).
In addition, as an electric wire that deforms according to various movements and is hard to break, one or more elastic conductors are integrated with a flexible resin molded body, and a flexible electric wire that satisfies a predetermined requirement is also known. (Patent Document 2).
Further, as a band-shaped transmission line that is hard to be broken even if it is expanded and contracted, there is also known a means for arranging a conductor wire coated with an insulator on an elastic cloth having an elastic thread in a zigzag shape (Patent Document 3).

Flexible electric wires used in devices having such bent portions are required to have particularly excellent disconnection resistance.
Patent Document 1 requires that the conductor wire be an aggregate of at least two or more thin wires in order to exhibit elasticity even with a small load. In other words, the wire break resistance is improved by double tracking.
Patent Document 2 secures disconnection resistance by adjusting the relationship between the elongation force of a plurality of conductors and a resin molded body and the elongation length of the conductors.
In Patent Document 3, disconnection resistance is ensured in the relationship between the conductor wires arranged in a zigzag shape and the stretchable fabric.

International Publication No. 2008/07780 JP-A-2009-266401 Japanese Unexamined Patent Publication No. 2014-229568

That is, as long as a solid conductor thin wire is used as a conductor, disconnection resistance can be improved by using a plurality of conductor thin wires or adjusting the relationship between the elongation force of the resin molded body and the elongation length of the conductor. The current situation is that we are getting it.
Further, in such a configuration, it is practically impossible to make the conductor single-core and miniaturize (make it inconspicuous) while ensuring the disconnection resistance.
In particular, when a solid conductor thin wire is used as a conductor, the bending stress of the solid conductor thin wire tends to be concentrated at one point, so that there is a limit to the single core and miniaturization of the conductor.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a flexible electric wire which has sufficient flexibility, is hard to break, and can be miniaturized (made inconspicuous).

In order to solve the above problems, the present invention provides the following flexible electric wires.
(1) A conductive structure containing a plurality of metal fibers, at least partially bonded to each other,
It is provided with an outer layer coating portion that covers the conductive structure.
The outer layer coating portion is a flexible electric wire formed of a resin material filled between a plurality of metal fibers forming a conductive structure.
(2) The flexible electric wire according to (1), wherein the cross section of the conductive structure is corrugated.
(3) The flexible electric wire according to (2), which includes two or more of the conductive structures.
(4) The flexible electric wire according to any one of (1) to (3), wherein the conductive structure has a notch.
(5) The flexible electric wire according to any one of (1) to (3), wherein the conductive structure has a net shape.

According to the present invention, it is possible to provide a flexible electric wire having excellent flexibility, which is hard to break, and which can be miniaturized (make it inconspicuous).

It is a perspective view which shows the flexible electric wire of 1st Embodiment. It is a figure for demonstrating the conductive structure provided by the flexible electric wire of the 2nd Embodiment, and is the figure which shows the shape of the conductive structure when viewed in a plan view. It is a figure for demonstrating the conductive structure provided by the flexible electric wire of the 3rd Embodiment, and is the figure which shows the shape of the conductive structure when viewed in a plan view. It is a figure for demonstrating the conductive structure provided by the flexible electric wire of 4th Embodiment, and is the figure which shows the shape of the conductive structure when viewed in a plan view. It is a figure for demonstrating the conductive structure provided in the flexible electric wire of the 5th Embodiment, and is the figure which shows the shape of the conductive structure when viewed in a plan view. It is a figure for demonstrating the conductive structure provided in the flexible electric wire of the sixth embodiment, and is the figure which shows the shape of the conductive structure when viewed in a plan view. It is a figure for demonstrating the conductive structure provided by the flexible electric wire of 7th Embodiment, and is the figure which shows the shape of the conductive structure when cross-sectional view is seen along the length direction thereof. It is a figure for demonstrating the conductive structure provided in the flexible electric wire of 8th Embodiment, and is the figure which shows the shape of the conductive structure when cross-sectional view is seen along the length direction thereof. It is a figure which shows the other shape of the conductive structure when the flexible electric wire is cross-sectionally viewed along the length direction. It is a figure which shows the other shape of the conductive structure when the flexible electric wire is cross-sectionally viewed along the length direction. It is a figure which shows the other shape of the conductive structure when the flexible electric wire is cross-sectionally viewed along the length direction. It is a figure for demonstrating the conductive structure provided by the flexible electric wire of the 9th Embodiment, and is the figure which shows the shape of the conductive structure when viewed in a plan view. It is a figure for demonstrating the evaluation method of the flexibility of a flexible electric wire. It is a figure for demonstrating the evaluation method of the fracture resistance of a flexible electric wire. It is a figure for demonstrating the measuring method of the sheet resistance value of a flexible electric wire.

The "mean fiber diameter" is a cross-sectional area perpendicular to the longitudinal direction of a metal fiber calculated by a known calculation method based on a vertical cross section at any plurality of points of the conductive structure imaged with a microscope. It is an additive mean value of the area diameter derived by calculating the diameter of a perfect circle having the same area as the area. The plurality of locations may be, for example, 20 locations.
The "average fiber length" is an arithmetic mean value obtained by measuring the lengths of a plurality of metal fibers randomly selected with a microscope in the longitudinal direction. If the fiber is not straight, it shall be the length of the curve along the fiber. The plurality of lines may be, for example, 20 lines.

The "space factor" is the ratio of the portion where the fiber exists to the volume of the conductive structure, and is calculated by the following formula from the basis weight, thickness, and true density of the fiber of the conductive structure. When the conductive structure contains a plurality of types of fibers, the space factor can be calculated by adopting a true density value that reflects the composition ratio of each fiber.
(Space factor (%)) = (Basis weight of conductive structure) / ((Thickness of conductive structure) x (True density)) x 100
The "thickness of the conductive structure" is, for example, measuring any 20 measurement points of the conductive structure with a film thickness meter of the terminal drop type by air (for example, "Digimatic Indicator ID-C112X" manufactured by Mitutoyo Co., Ltd.). It may be the additive average value in the case of the above, or it may be the additive average value when the vertical cross section of the conductive structure when the cross section is observed with an electron microscope or the like is measured at 20 measurement points, for example. ..
“Homogeneity” means that there is little variation in the electrical characteristics, physical characteristics, and other characteristics of the conductive structure composed of metal fibers. As an index of homogeneity, for example, the coefficient of variation (CV value) of the basis weight specified in JIS Z8101 per 1 cm ² can be adopted.
The "porosity" is the ratio of the portion where the void exists to the volume of the conductive structure, and is calculated by the following formula from the basis weight, the thickness, and the true density of the metal fiber of the conductive structure. When the conductive structure contains a plurality of types of fibers, the space factor can be calculated by adopting a true density value that reflects the composition ratio of each fiber.
(Porosity (%)) = (1- (Basis weight of conductive structure) / ((Thickness of conductive structure) x (True density))) x 100

Hereinafter, the flexible electric wire of the present invention will be described in detail with reference to the drawings.
(First Embodiment)
As shown in FIG. 1, the flexible electric wire 1 of the present embodiment includes a conductive structure 20 including a plurality of metal fibers in which at least a part thereof is bonded to each other, and an outer layer covering portion 3 covering the conductive structure 20. It is roughly composed of.
Further, the outer layer covering portion 3 is formed on at least the surface of the conductive structure 20 by filling a resin material between a plurality of metal fibers forming the conductive structure 20.
Hereinafter, the conductive structure 20 and the outer layer covering portion 3 forming the flexible electric wire will be described in detail.

(Conductive structure)
The conductive structure 20 may be composed of metal fibers having a single composition, or may be composed of two or more types of metal fibers in combination. Alternatively, it may be composed of a metal-coated fiber in which the circumference of the organic fiber is coated with a metal or a structure containing the metal-coated fiber.
As the metal-coated fibers, the metal-coated organic fibers may be made into paper and then fused between the fibers, or the organic fibers may be made into paper and then metal-coated.
In the present invention, the "metal fiber" means a fiber containing a metal as a main component. For example, "copper fiber" means a fiber containing copper as a main component. The term "copper as a main component" means a state in which a certain amount of other components may be contained, including unavoidable impurities, as long as the effects of the present invention are not impaired.
Examples of the metal component constituting the metal fiber include copper, stainless steel, iron, aluminum, nickel, chromium and the like, but are not particularly limited. The metal component may be a noble metal such as gold, platinum, silver, palladium, rhodium, iridium, ruthenium, and osmium. Among these, copper, stainless steel, and aluminum are preferable as the metal component constituting the metal fiber. In particular, copper fiber is preferable because it has an excellent balance between rigidity and plastic deformability.

Examples of components other than metal include polyethylene terephthalate (PET) resin, polyvinyl alcohol (PVA), polyethylene, and polyolefins such as polypropylene, polyvinyl chloride resin, aramid resin, nylon, acrylic resin, and fibrous materials thereof. Examples thereof include organic substances having a binding property and a supporting property. These organic substances can be used, for example, to assist / improve the morphological maintainability and functionality when the conductive structure 20 is produced.

The metal fibers forming the conductive structure 20 are partially bonded. The fact that the metal fibers are bound means that the metal fibers are physically fixed to each other to form a binding portion. In the conductive structure 20, the metal fibers may be directly fixed to each other at the binding portion, or a part of the metal fibers may be indirectly fixed to each other via a component other than the above metal component. Good.
For example, when the metal fibers are sintered and bonded, the thermal conductivity and homogeneity of the conductive structure 20 are stable, and it is easy to obtain excellent flexibility and disconnection resistance.
When a plurality of metal fibers are bound together, voids may be formed between the metal fibers. When the conductive structure 20 is provided with a plurality of fixed portions by binding and the gap, the metal fibers forming the conductive structure 20 are deformed, whereby the flexible electric wire 1 itself can be deformed, contracted, or stretched, which is excellent. Flexibility can be obtained.

The porosity of the conductive structure 20 is preferably 30% or more.
When the porosity of the conductive structure 20 is 30% or more, the shape of the conductive structure 20 itself can be easily maintained, and an appropriate void necessary for filling the resin material is provided therein.

The sheet resistivity of the conductive structure 20 is designed according to the energization conditions of the flexible electric wire, and is not limited, but is preferably 100 mΩ / □ or less, more preferably 50 mΩ / □ or less, and further preferably 30 mΩ / □. The following, and most preferably 10 mΩ / □ or less. When the sheet resistivity of the conductive structure is 100 mΩ / □ or less, it is easy to suppress heat generation when the flexible electric wire 1 is energized.

The structure of the conductive structure 20 is preferably strip-shaped. For example, the strip-shaped conductive structure 20 may be a non-woven fabric in which metal fibers are randomly bonded, a woven fabric having regularity, or a mesh material.
Further, the surface of the conductive structure 20 may be flat, corrugated, etc., and may have irregularities, and is not particularly limited.

The vertical thickness of the conductive structure 20 is preferably in the range of 0.005 mm to 10 mm, more preferably 5 mm or less, further preferably 1 mm or less, and most preferably 0.5 mm or less. If the thickness of the conductive structure 20 is 0.005 mm or more, it is difficult to break the flexible electric wire 1 even if it is deformed. When the thickness of the conductive structure 20 is 10 mm or less, excellent flexibility can be easily obtained.
The thickness of the conductive structure 20 can be appropriately adjusted in a pressing process described later.

The basis weight of the conductive structure 20 is preferably in the range of 10 g / m ² to 1,000 g / m ² . When the basis weight of the conductive structure 20 is 10 g / m ² or more, a predetermined thickness can be obtained and it is difficult to break the wire. When the basis weight of the conductive structure 20 is 1,000 g / m ² or less, the weight of the conductive structure 20 can be easily reduced, and the weight of the flexible electric wire 1 can be easily reduced.

The average fiber diameter of the metal fiber can be arbitrarily set as long as the effect of the present invention is not impaired. The average fiber diameter of the metal fibers is preferably 0.1 μm to 100 μm, more preferably 0.5 μm to 50 μm, and even more preferably 1 to 30 μm. When the average fiber diameter of the metal fibers is 0.1 μm or more, appropriate rigidity of the conductive metal fibers can be obtained, so that so-called lumps are unlikely to occur when the conductive structure 20 is manufactured. If no lumps occur, the homogeneity of the conductive structure 20 tends to be stable. This makes it easy to obtain excellent flexibility and disconnection resistance. When the average fiber diameter of the metal fibers is 30 μm or less, appropriate rigidity of the metal fibers can be obtained, so that entanglement of the fibers is unlikely to occur.

The shape of the cross section perpendicular to the longitudinal direction of the metal fiber can be any shape. The shape of such a cross section may be any shape such as a circular shape, an elliptical shape, a substantially quadrangular shape, and an amorphous shape.

The average fiber length of the metal fiber can be arbitrarily set as long as the effect of the present invention is not impaired. The average fiber length of the metal fibers is preferably in the range of 0.1 mm to 10 mm, more preferably in the range of 0.3 mm to 5 mm, and even more preferably in the range of 0.5 to 3 mm. When the average fiber length of the metal fibers is in the range of 0.1 mm to 10 mm, the homogeneity is likely to be stable even when the conductive structure 20 is obtained by papermaking.
The aspect ratio of the metal fiber is preferably 10 to 10,000. When the aspect ratio is 10 or more, the metal fibers can be easily partially bonded to each other, and the flexible electric wire 1 can maintain an appropriate strength. On the other hand, when the aspect ratio is 10,000 or less, it is easy to obtain excellent homogeneity of the conductive structure 20, and by extension, it is easy to obtain excellent flexibility.

The space factor of the conductive structure 20 is preferably 70% or less, more preferably 50% or less, and further preferably 30% or less. When the space factor is 70% or less, the flexibility of the conductive structure 20 can be maintained, and the resin material can be uniformly filled.

The coefficient of variation (CV value) of the basis weight specified in JIS Z8101 per 1 cm ^{2 of the} conductive structure 20 is preferably 10% or less. Since the basis weight is an index indicating the weight per unit volume, it can be said that the coefficient of variation of the basis weight is not more than a certain value, which is also a stable value for the space factor of the conductive structure 20. That is, when the coefficient of variation of the basis weight of the conductive structure 20 is 10% or less, the conductive structure 20 is less likely to have lumps and voids of an extreme size, the conductivity of the conductive structure 20 is excellent, and the flexible electric wire is used. It is easy to obtain the excellent flexibility and disconnection resistance of 1.

(Outer layer coating)
The outer layer coating portion 3 is obtained by at least partially filling the resin material between the plurality of metal fibers forming the conductive structure 20 so as to cover the conductive structure 20. The resin material forming the outer layer coating portion 3 may be filled only on the outer peripheral surface of the conductive structure 20, but may be filled on the entire conductive structure 20.
When the outer layer coating portion 3 is filled only on the outer peripheral surface of the conductive structure 20, air having poor thermal conductivity remains inside the flexible electric wire, and the outer peripheral surface is insulated with a resin material, so that the temperature is kept constant. This is advantageous when you want to keep the electric wire warm. Further, when the outer layer covering portion 3 is filled in the entire conductive structure 20, it is easy to obtain a contracting force after the flexible electric wire is stretched.
The thickness of the outer layer covering portion 3 is preferably 0.3 to 10,000 times, more preferably 1 to 1,000 times, still more preferably 2 to 100 times the thickness of the conductive structure 20.
As the resin material forming the outer layer coating portion 3, a known resin material having insulating properties and flexibility can be used.
For example, polyacrylic acid resin such as polymethacrylic acid and polycyanoacrylate (polycyanoacrylate); polyvinylpyrrolidone resin; polyester resin such as polyethylene terephthalate; polypropylene resin; fluororesin such as polytetrafluoroethylene; polyimide resin; Polyamide resin containing aramid; polyparaphenylene benzobisoxazole resin, silicone resin, silicone rubber, fluororubber, acrylic rubber and the like can be mentioned. These resins can be used alone or in admixture of two or more.
Among these, silicone, a fluororesin, acrylic rubber, or the like is preferable in consideration of the followability when the conductive structure 20 is deformed.

Next, a method of manufacturing the flexible electric wire of the present embodiment will be described.
First, the conductive structure 20 is manufactured.
Examples of the method for producing the conductive structure 20 include a dry method by compression molding and the like, a method of papermaking by a wet papermaking method, and the like.
When the conductive structure 20 is obtained by the dry method, a web mainly composed of metal fibers obtained by the card method, the airlaid method, or the like is compression-molded. At the time of compression molding, the metal fibers can be partially bonded to each other by impregnating the metal fibers with a binder. As such a binder, a known organic binder such as an acrylic adhesive and a known inorganic binder such as colloidal silica can be used. After the above step, the obtained conductive structure 20 may be sintered or the like to bind the metal fibers to each other.

When the conductive structure 20 is manufactured by the wet papermaking method, wet papermaking can be performed with a paper machine using a slurry in which metal fibers and the like are dispersed in an aqueous medium.
The aqueous medium is usually water, but a water-soluble solvent such as alcohol can be added. Further, known additives such as fillers, dispersants, thickeners, defoamers, paper strength enhancers, sizing agents, coagulants, colorants, and fixing agents may be appropriately added to the above slurry. it can.
In the wet papermaking method, a binding point forming step of partially binding metal fibers and the like to each other may be carried out. As the binding point forming step, a method of injecting a high-pressure jet water stream onto the wet body tape surface can be adopted. After passing through this step, the wet body sheet (conductive structure) is wound up through a dryer step.

In the wet papermaking method, the pressing process can be performed before the binding point forming process and the dryer process. By carrying out the pressing process, extremely large voids formed between the metal fibers can be reduced and homogeneity can be improved. In addition, the thickness of the conductive structure 20 can be adjusted by appropriately adjusting the pressure at the time of pressing during the pressing process. For example, in the case of producing a conductive structure 20 having a thickness of about 170 μm, the homogeneity of the conductive structure 20 and thus the flexibility and disconnection resistance can be improved by applying pressure at a linear pressure of less than 300 kg / cm.

As a method for binding metal fibers and the like, there is a method of sintering the conductive structure 20 in addition to the method of using the above binder and the method of injecting a high-pressure jet water stream.
By sintering the conductive structure 20 and partially binding the metal fibers, the metal fibers and the like can be reliably bound and the metal fibers can be fixed, so that the basis weight of the conductive structure 20 can be increased. The fluctuation coefficient (CV value) tends to be stable. Further, since the binding portion can be reliably provided, it is easy to secure stable homogeneity and thermal conductivity of the conductive structure 20. Further, since a large number of binding portions are formed, when the flexible electric wire receives bending stress, the stress is dispersed and the flexibility is easily improved.
It is preferable that the conductive structure 20 that has undergone the sintering step further undergoes a pressing step. By further passing through the pressing step after the sintering step, the homogeneity of the conductive structure 20 can be more easily improved, and the conductive structure 20 can be made thinner. The pressing process after sintering causes a shift of metal fibers and the like not only in the thickness direction but also in the surface direction. As a result, the metal fibers and the like are arranged even in the places that were voids at the time of sintering, the homogeneity is improved, and such a state is maintained by the plastic deformation characteristics of the metal fibers. The pressure in the pressing step performed after the sintering step can be appropriately set in consideration of the thickness of the conductive structure 20.

When the conductive structure 20 is made of a woven cloth, a mesh, or the like, a known manufacturing method can be used.

When the cross section of the conductive structure 20 has a corrugated shape, it may be press-processed using an embossing machine or the like so that the cross section of the obtained conductive structure 20 has a desired shape. For example, a desired cross-sectional shape can be imparted by attaching a pair of gear-shaped embossing rolls that mesh with each other to a general embossing machine and passing the conductive structure 20 between the male and female embossing rolls.

Next, the outer layer covering portion 3 is formed so as to cover the obtained conductive structure 20.
First, the resin material is selected in consideration of the flexibility required for the flexible electric wire 1.
Then, the obtained resin material is impregnated with the conductive structure 20. At this time, by adjusting the viscosity of the resin material to be used, the impregnation time, the curing time, etc., the outer layer covering portion 3 that covers only the outer peripheral surface of the conductive structure 20 can be formed, and the inside of the conductive structure 20 is included. The entire surface can be covered with the outer layer covering portion 3. Further, the thickness of the outer layer covering portion 3 when forming the outer layer covering portion 3 covering only the outer peripheral surface can be adjusted.
Further, when forming the outer layer covering portion 3 that covers only the outer peripheral surface of the conductive structure 20, a resin material may be applied to the outer peripheral surface of the conductive structure 20.
Furthermore, a tubular outer layer coating layer 3 is formed using a resin material, the tubular outer layer coating layer 3 is covered with the conductive structure 20, and then heat is applied to the outer layer coating layer 3 to form the outer layer coating layer 3. A resin material may be filled between the metal fibers forming the conductive structure 20 by partially melting the inner peripheral side. For example, by heating the conductive structure 20, only the inner peripheral side of the outer layer coating layer 3 is melted, and a resin material can be filled between the metal fibers forming the conductive structure 20.

When an electrode is provided on the flexible electric wire, the electrode may be formed in advance at the end of the conductive structure 20, or a through hole may be provided after the outer coating portion 3 is provided to form the electrode.

The flexible electric wire 1 of the present embodiment has a three-dimensional structure in which the metal fibers of the conductive structure 20 are partially bonded. As described above, since the portion where the material constituting the conductive structure 20 does not exist is formed inside the conductive structure 20, the conductive structure 20 can be easily deformed, contracted, or stretched. Further, the outer layer covering portion 3 can follow the deformation, contraction, or elongation of the conductive structure 20.
Further, the bending stress applied to the flexible electric wire 1 can be dispersed and absorbed at the binding points of the metal fibers and the individual metal fibers.
Therefore, although the flexible electric wire 1 of the present embodiment has excellent flexibility, it has high disconnection resistance against bending stress. Therefore, it is possible to wire along the unevenness on the surface of the device provided with the unevenness while maintaining high disconnection property.

(Second Embodiment)
As shown in FIG. 2, the flexible electric wire 1 of the present embodiment is different from the flexible electric wire of the first embodiment in that the cross section of the conductive structure 21 contained therein is corrugated.
The manufacturing method of the flexible electric wire 1 of this embodiment will be described.
First, a copper fiber sheet is obtained by a papermaking method, and then the copper fibers are partially bonded to each other by sintering to obtain a copper fiber paper having a thickness of 1.0 mm. The copper fiber paper can be obtained, for example, by the production method described in WO2018 / 131658. Next, the obtained copper fiber paper is cut into a size of 50 x 200 mm, a pair of gear-shaped emboss rolls that mesh with male and female are attached to a general embossing machine, and the copper fiber paper is passed between the male and female emboss rolls. Then, the cross section is corrugated so that it becomes corrugated. For example, the copper fiber paper can be corrugated so that the height of the peaks and valleys is 1 mm, the distance between the peaks and the pitch are 0.5 mm. The conductive structure 21 is obtained by making a notch in the corrugated copper fiber paper using a cutting tool.
Next, the voids of the conductive structure 21 are impregnated with silicone rubber, and the silicone rubber is also adhered to the surface of the conductive structure 21 so that the total thickness is 1.2 mm. After that, air is removed as much as possible by vacuum defoaming, and thermosetting is performed.
As a result, the flexible electric wire 1 of the present embodiment can be obtained.
The flexible electric wire 1 of the present embodiment can be extended not only in the length direction but also in the width direction.

(Third Embodiment)
As shown in FIG. 3, the flexible electric wire 1 of the present embodiment is different from the flexible electric wire of the second embodiment in that the conductive structure 22 is provided with a linear notch along the longitudinal direction.
Notches are not provided in the upper end and the lower end in the length direction so that the conductive structure 22 is not divided into a plurality of parts. In the present embodiment, the conductive structure 22 is provided with three notches, but the present invention is not limited to this. The number of cuts can be determined in consideration of the flexibility and elasticity required for the flexible electric wire 1.
It is preferable that the notch is provided through the conductive structure 22, but it is not always necessary to penetrate the notch. The depth of cut can be appropriately adjusted in consideration of the flexibility and elasticity required for the flexible electric wire 1.
Next, a method of manufacturing the flexible electric wire 1 of the present embodiment will be described.
In the flexible electric wire 1 of the present embodiment, similarly to the second embodiment, after obtaining the copper fiber paper, the obtained copper fiber paper is cut to 50 × 200 mm, and a plurality of cuts are made by using a cutting tool. Then, the flexible electric wire 1 of the present embodiment is obtained by corrugating in the same manner as in the second embodiment, impregnating with silicone rubber and adhering it on the surface.
The flexible electric wire 1 of the present embodiment can be extended not only in the length direction but also in the width direction.

(Fourth Embodiment)
As shown in FIG. 4, the flexible electric wire 1 of the present embodiment is different from the flexible electric wire of the second embodiment in that the conductive structure 23 is provided with a broken line-shaped notch along the longitudinal direction.
A broken line-shaped notch is provided so that the conductive structure 23 is not divided into a plurality of parts. In the present embodiment, the conductive structure 23 is provided with three broken-line notches, but the present invention is not limited to this. The number of fractured cuts can be determined in consideration of the flexibility required for the flexible electric wire 1. Further, the length and depth of the cut can be appropriately adjusted in consideration of the flexibility required for the flexible electric wire 1.
Next, a method of manufacturing the flexible electric wire 1 of the present embodiment will be described.
In the flexible electric wire 1 of the present embodiment, similarly to the second embodiment, after obtaining the copper fiber paper, the obtained copper fiber paper is cut into a size of 50 × 200 mm, and a fractured cut is made using a cutting tool. .. Next, the flexible electric wire 1 of the present embodiment is obtained by corrugating in the same manner as in the second embodiment, impregnating with silicone rubber and adhering it on the surface.
The flexible electric wire 1 of the present embodiment can be extended not only in the length direction but also in the width direction.

(Fifth Embodiment)
As shown in FIG. 5, the flexible electric wire 1 of the present embodiment is different from the flexible electric wire of the second embodiment in that the conductive structure 24 is provided with one notch in a square spiral shape along the outer circumference. It's different.
Since the conductive structure 24 is provided with one notch in a square spiral shape along the outer circumference, the conductive structure 24 is not divided into a plurality of parts. The interval between the cuts and the depth of the cuts can be appropriately adjusted in consideration of the flexibility required for the flexible electric wire 1.
Next, a method of manufacturing the flexible electric wire 1 of the present embodiment will be described.
In the flexible electric wire 1 of the present embodiment, similarly to the second embodiment, after obtaining the copper fiber paper, the obtained copper fiber paper is cut into a size of 50 × 200 mm, and a blade is used to cover the outer periphery of the copper fiber paper. Make a square spiral cut along it. Next, corrugated processing is performed in the same manner as in the second embodiment. Then, the flexible electric wire 1 of the present embodiment is obtained by impregnating the corrugated copper fiber paper with silicone rubber and adhering it on the surface.
The flexible electric wire 1 of the present embodiment can be extended not only in the length direction but also in the width direction and the thickness direction.

(Sixth Embodiment)
As shown in FIG. 6, the flexible electric wire 1 of the present embodiment is different from the flexible electric wire of the second embodiment in that the conductive structure 25 has a net shape.
The manufacturing method of the flexible electric wire 1 of this embodiment will be described.
In order to obtain the flexible electric wire 1 of the present embodiment, first, a conductive structure is obtained and then a pattern is cut by a fiber laser in the same manner as in the second embodiment. Next, the waveform is processed in the same manner as in the second embodiment. Then, the flexible electric wire 1 of the present embodiment is obtained by impregnating the corrugated copper fiber paper with silicone rubber and adhering it on the surface.
The flexible electric wire 1 of the present embodiment can be extended not only in the length direction but also in the width direction.

(Seventh Embodiment)
As shown in FIG. 7, the flexible electric wire 1 of the present embodiment is different from the flexible electric wire of the second embodiment in that a plurality of

conductive structures

20A and 20B are arranged in the thickness direction.
In the flexible electric wire 1 of the present embodiment, two

conductive structures

20A and 20B having a zigzag cross section are arranged so that their waveforms match. The two

conductive structures

20A and 20B need not be arranged so as to overlap at all parts.
Next, a method of manufacturing the flexible electric wire 1 of the present embodiment will be described.
Two or more corrugated copper fiber papers obtained in the second embodiment are laminated without changing the phase of the peaks and valleys, and then silicone rubber is impregnated and adhered to the surface in the same manner as in the second embodiment. The flexible electric wire 1 of the present embodiment is obtained.
The flexible electric wire 1 of the present embodiment can be sufficiently extended in the length direction and has high disconnection resistance.

(Eighth embodiment)
As shown in FIG. 8, the flexible electric wire 1 of the present embodiment is different from the flexible electric wire of the second embodiment in that a plurality of conductive structures 2 are arranged in the thickness direction.
In the flexible electric wire 1 of the present embodiment, two conductive structures 2 having a zigzag cross section are arranged so as to have their waveforms in opposite phases. The two conductive structures 2 do not have to be in contact with each other, and may not be in contact with each other.
Next, a method of manufacturing the flexible electric wire 1 of the present embodiment will be described.
Two or more corrugated copper fiber papers obtained in the second embodiment are laminated so that the phases of the peaks and valleys are opposite to each other, and then silicone rubber is impregnated and adhered to the surface in the same manner as in the second embodiment. By doing so, the flexible electric wire 1 of the present embodiment can be obtained.
The flexible electric wire 1 of the present embodiment can be sufficiently extended in the length direction.

(Ninth Embodiment)
As shown in FIG. 12, the flexible electric wire 1 of the present embodiment is different from the flexible electric wire of the second embodiment in that the sheet-shaped conductive structure 2 is die-cut.
In the present embodiment, the sheet-shaped conductive structure 2 is die-cut into a bellows shape, but the present invention is not limited to this. The flexible electric wire 1 may be die-cut into a desired shape in consideration of the flexibility and elasticity required for the flexible electric wire 1.
Next, a method of manufacturing the flexible electric wire 1 of the present embodiment will be described.
The corrugated copper fiber paper obtained in the second embodiment was cut out in a flat bellows shape by a fiber laser. Then, similarly to the second embodiment, the flexible electric wire 1 of the present embodiment is obtained by impregnating the copper fiber paper cut out in a flat bellows shape with silicone rubber and adhering it on the surface.
The flexible electric wire 1 of the present embodiment can be sufficiently extended in the length direction.

In addition, in the second to ninth embodiments shown in FIGS. 2 to 8 and 12, the cross sections of the

conductive structures

21, 22, 23, 24, 25, 20A and 20B, and 20C and 20D are zigzag. Shape, but not limited to it. For example, as shown in FIGS. 9 to 11, the conductive structure has a sine curve shape (FIG. 9), a shape having a quadrangular convex portion and a quadrangular concave portion (FIG. 10), or a plurality of cross sections. It may have a shape formed of a right triangle (FIG. 11).

Examples 1-10
Copper fibers having the fiber diameter and fiber length shown in Table 1 below were dispersed in water, and a thickener, a dispersant, etc. were appropriately added to prepare a papermaking slurry. The obtained papermaking slurry having a basis weight of 300 g / m ² was put on a papermaking net, dehydrated under reduced pressure, and dried at 100 ° C. for 60 minutes to obtain copper fiber paper. Then, the obtained copper fiber paper was pressed at a linear pressure of 80 kg / cm at room temperature, and then heated at 1020 ° C. for 40 minutes in an atmosphere of 75% hydrogen gas and 25% nitrogen gas to partially gap the copper fibers. It was sintered.
Next, the obtained copper fiber paper was cut into a size of 50 x 200 mm, a pair of gear-shaped emboss rolls meshed with male and female were attached to the embossing machine, and the copper fiber paper was passed between the male and female emboss rolls to cross-section. Was corrugated so that Table 1 shows the wavelength, amplitude, width, and thickness of the corrugated copper fiber paper.
Next, the corrugated copper fiber paper was impregnated with the silicone resin and then dried to provide an outer layer coating portion. The thickness of the obtained flexible electric wire was 1.2 mm.

Comparative Examples 1 to 4
As shown in Table 2, as the material of the conductive structure, copper foil was used in Comparative Examples 1 and 4, perforated copper foil was used in Comparative Example 2, and copper wire (single wire) was used in Comparative Example 3. A flexible electric wire was obtained in the same manner as in Examples 1 to 10 except for the above.

The flexible electric wires obtained in Examples 1 to 10 and Comparative Examples 1 to 4 were evaluated as follows. The results are also shown in Table 1 or Table 2.
(Evaluation of miniaturization)
The evaluation of miniaturization used the thickness of the sheet-shaped conductive structure before corrugating as an index.
The thickness of the conductive structure was preferably 0.5 mm or less, more than 0.5 mm, and 1.0 mm or less.

(Evaluation of flexibility)
As shown in FIG. 13, the obtained flexible electric wire is supported so as to be sandwiched from the vertical direction, bent by + 90 ° so as to contact the side surface of the upper support member from that state, and then contacted with the side surface of the lower support member. It was bent by -90 ° so as to.
When the resistance change was 5% or less and the flexible electric wire or the conductive structure in the portion sandwiched between the support members was visually inspected, the number of bendings in which there was no significant change in appearance (no cracks or breaks) was examined.
Those that cannot withstand 500 bending tests are not allowed, those that can withstand 1,000 or more and less than 2,000 bending tests are good, and those that can withstand 2,000 or more bending tests. To be excellent.

(Evaluation of fracture resistance)
As shown in FIG. 14, the obtained flexible electric wire is supported so as to be sandwiched from the vertical direction, twisted 90 ° (+ 90 °) clockwise from that state, returned to the original position (0 °), and then counterclockwise. Twisted 90 ° (-90 °).
When the resistance change was 5% or less and the flexible electric wire or the conductive structure in the portion sandwiched between the support members was visually inspected, the number of twists without any significant change in appearance (no cracks or breaks) was examined.
As for the breaking resistance, those that cannot withstand 500 times of tests are not allowed, those that can withstand 1,000 times of tests are good, and those that can withstand 2,000 or more times of tests are excellent.

(Sheet resistance value)
The voltage and current of each piece were measured according to the individual piece resistance measurement procedure shown in FIG. 15, and the sheet resistance value was calculated from the following number 1 by the van der Pauw method. In FIG. 15, reference numeral 1 indicates a flexible electric wire. The black circles in FIG. 15 indicate the contacts between the wiring for resistance measurement and the conductive structure constituting the flexible electric wire. The contact may be formed by removing the outer layer coating portion by an arbitrary method or the like.
Power supply: PA250-0.25A (manufactured by KENWOOD)
Voltmeter: KEITHLEY DMM7510 7 1/2 DIGIT MULTIMETER (manufactured by Tektronix)

(1) As shown in FIG. 15, two types of IV characteristics are measured, and then resistance is obtained.

As shown in the left diagram of FIG. 15, I _AB includes an electrode A, when you connect DC power to the electrode B, and through the flexible wire means the magnitude of the current flowing from electrode A to electrode B. _VDC means the voltage between the power supply D and the power supply C when a DC power supply is connected to the electrode A and the electrode B. _{RAB and CD} mean the resistance of the flexible electric wire when the electrode A and the DC power supply are connected to the electrode B.
As shown in swirl of FIG 15, I _BC includes an electrode B, when you connect DC power to the electrode C, and through the flexible wire means the magnitude of the current flowing from the electrode B to the electrode C. V _AD means an electrode B, when you connect DC power to the electrode C, and the voltage between the source A and source D. _{RBC and DA} mean the resistance of the flexible electric wire when the electrode B and the DC power supply are connected to the electrode C.

(2) Calculate Rs (sheet resistance) using the following formula.

In the above equation, f means a factor related to the correction of current wraparound due to the difference in resistance value.

From Tables 1 and 2, the flexible electric wires of Examples 1 to 10 in which the silicone resin as the outer layer coating portion is filled between the plurality of metal fibers forming the conductive structure are the same as the flexible electric wires of Comparative Examples 1 to 4. In comparison, it can be seen that the balance between the flexibility and the disconnection resistance is excellent even though the sheet resistance value is not a problem in practical use.

Although some embodiments of the flexible electric wire of the present invention have been described above, they are presented as examples and are not intended to limit the scope of the invention. The flexible electric wire of the above-described embodiment can be implemented in various other forms, and various substitutions, modifications, and the like can be made without departing from the gist of the invention.

The flexible electric wire of the present invention is suitably used for wiring of devices having a bent portion such as bending and stretching, such as body-worn devices and clothes-worn devices, including the robot field.
Especially humanoid robots (internal wiring, outer wiring), power assist devices, wearable electronic devices, etc. In addition, it is preferably used for rehabilitation aids, vital data measuring devices, motion capture, game controllers, microphones, headphones, etc., and is particularly suitable for applications where the presence of wiring is not desired to be noticed.

1 Flexible electric wire 20-25, 20A-20G, 26 Conductive structure 3 Outer layer coating

Claims

A conductive structure containing a plurality of metal fibers, at least partially bonded to each other,
It is provided with an outer layer coating portion that covers the conductive structure.
The outer layer coating portion is a flexible electric wire formed of a resin material filled between a plurality of metal fibers forming a conductive structure.
The flexible electric wire according to claim 1, wherein the cross section of the conductive structure is corrugated.
The flexible electric wire according to claim 2, further comprising two or more of the conductive structures.
The flexible electric wire according to any one of claims 1 to 3, wherein the conductive structure has a notch.
The flexible electric wire according to any one of claims 1 to 3, wherein the conductive structure has a net shape.