JP7201399B2 - Conductive fabric and method for producing conductive fabric - Google Patents

Description

The present invention relates to conductive fabrics and methods of making the same. More specifically, the present invention relates to a conductive fabric having excellent bending resistance and a method for producing the same.

As a flexible conductive member, a polymer film having a metal-containing film formed on its surface is used. However, a conductive member in which a metal-containing film is formed on the surface of a polymer film has insufficient durability against sharp bending and repeated bending.

For the purpose of improving the durability against bending, it has been proposed to provide a metal film by plating on the surface of a fabric made of fibers. Patent Document 1 discloses a surface conductive fabric in which a metal film layer is provided by electroless metal plating on the surface of a fabric woven at a specific weaving density using warp and weft yarns having a specific total fineness.

Patent Document 2 discloses a conductive fabric in which a patterned metal foil is transferred to a fabric having an underlying coating layer via an adhesive layer, and then a cover coat is applied so as to cover the metal foil.

A number of methods have been proposed in which a conductive paste is applied to fibers to form a conductive cloth. A conductive paste is disclosed which contains a 40° C. saturated copolyester resin, a foil-like metal powder and a solvent. By coating a fiber core with a dry coating film of this conductive paste, it is possible to provide a conductive wire with excellent flexibility and bendability.

Japanese Unexamined Patent Application Publication No. 2004-11035 JP 2016-196139 A JP 2012-43648 A

However, in the method of forming a metal thin film on a fabric by metal plating or the like, as in Patent Documents 1 and 2, although the bending resistance is improved compared to the case of using a polymer film as a base material, It was not yet practical. Similarly, even with a conductive paste that uses a highly flexible resin selected as in Patent Document 3, the improvement in flex resistance is insufficient.

Furthermore, in recent years, there has been a demand for a conductive fabric having not only high bending durability but also conductivity in the thickness direction of the fabric.

As a result of intensive research, the present inventors have found that in a conductive fabric in which both sides of a mesh-like substrate having a specific open area are coated with a conductive composition, one side of the mesh-like substrate has a mesh-like substrate. The conductive composition is coated so that the constituting threads are not exposed, and the other surface of the mesh-like substrate is coated with the conductive composition to such an extent that part of the threads constituting the mesh-like substrate is exposed. It has been found that a coated conductive fabric exhibits high bending durability.

That is, the present invention provides a mesh-like substrate which is a fabric having an open area ratio of 30% or more in which at least one of the warp and the weft is composed of monofilaments, and a first surface of the mesh-like substrate and a side opposite to the first surface. and a conductive composition covering the second surface of the first surface side has no portion where the warp and weft yarns are exposed, and the second surface side has at least a portion of the monofilament It is a conductive fabric having exposed portions in a regular, substantially elliptical shape . According to this, a conductive fabric having conductivity in the thickness direction and having high durability against bending can be obtained.

On the second surface side, the value of S ₁ /S ₂ is 0 for the area S ₁ of the portion coated with the conductive composition and the area S ₂ of the portion where the warp and the weft are exposed. .7 to 10.0 is preferred.

On the second surface side, the value of S ₁ /S ₂ is 3 for the area S ₁ of the portion covered with the conductive composition and the area S ₂ of the portion where the warp and the weft are exposed. .0 to 10.0 is more preferable.

The open area ratio of the conductive cloth is preferably 20% or less. According to this, in the openings of the mesh-like base material, since the film of the conductive composition is formed continuously from the first surface to the second surface, good conductivity in the thickness direction can be obtained. Further, it is preferable that the conductive cloth has a thickness of 50 to 200 μm.

The method for producing a conductive fabric of the present invention is a method for producing a conductive fabric in which a conductive composition ink is applied from the first surface side of a mesh-like substrate and then dried to form a film of the conductive composition. hand,
The mesh-like base material is a woven fabric with an opening ratio of 30% or more in which at least one of the warp and the weft is composed of monofilaments,
The first surface side does not have a portion where the warp and the weft are exposed, and at least a part of the monofilament is exposed in a regular and substantially elliptical shape on the second surface side opposite to the first surface. A method for producing a conductive fabric, characterized by forming a film of a conductive composition so as to have a portion where the conductive fabric is formed.

On the second surface side, the value of S ₁ /S ₂ is 0 for the area S ₁ of the portion coated with the conductive composition and the area S ₂ of the portion where the warp and the weft are exposed. .7 to 10.0 is preferred.

ADVANTAGE OF THE INVENTION According to this invention, the conductive fabric which has high bending resistance and electroconductivity also in the thickness direction can be provided.

It is a cross-sectional schematic diagram of the conductive cloth which concerns on one Embodiment. 4 is a surface SEM observation image of the second surface side of the conductive fabric of Example 1. FIG. 4 is a surface SEM observation image of the second surface side of the conductive fabric of Comparative Example 1. FIG.

The conductive fabric of the present invention contains a mesh-like substrate as a base material. It is essential that the mesh-like substrate is a woven fabric in which at least one of the warp and the weft is made of monofilament and has an open area ratio of 30% or more.

The warp and weft that constitute the mesh-like substrate are preferably synthetic fibers such as nylon, polyester, acrylic, vinylon, polyethylene, and polypropylene. Monofilaments are used for at least one of the warp and the weft. The other yarn may be a monofilament, multifilament, or spun yarn. The fineness of the monofilament is preferably 10-50 dtex. The other yarn preferably has a total fineness of 10 to 500 dtex.

When monofilaments are used for at least one of warp and weft to form a woven fabric, it is necessary to adjust the weaving density of the warp and weft so that the open area ratio of the woven fabric is 30% or more. By appropriately setting the weaving density in consideration of the total fineness of the warp and weft, it is possible to weave a woven fabric having an open area ratio of 30% or more. The texture of the woven fabric is not particularly limited and may be plain weave, twill weave, or satin weave. A plain weave is preferable in that anisotropic low flex resistance can be obtained when the fabric is made into a conductive fabric. As a method for measuring the open area ratio, there is a method of analyzing an image of one surface of the mesh-like base material and calculating the area ratio of the portion where no warp or weft exists per unit area.

The conductive composition that constitutes the conductive fabric of the present invention preferably comprises conductive particles and a polymer resin. Examples of conductive particles include carbon particles, carbon nanotubes, and metal particles. Among them, metal particles are preferable when high conductivity is required. Examples of metal particles are preferably one selected from the group consisting of silver particles, nickel particles and copper particles, or a mixture of two or more.

The polymer resin to be blended in the conductive composition of the present invention is not particularly limited, but examples include acrylic resin, phenoxy resin, polyvinyl formal resin, polystyrene resin, polyvinyl butyral resin, polyester resin, polyamide resin, polyimide resin, xylene resin, Examples include polyurethane resins and epoxy resins. Alternatively, a conductive polymer material such as polypyrrole or PEDOT may be used.

The conductive fabric of the present invention will be described with reference to FIG. The mesh-like base material 2 used in the conductive fabric 1 of the present invention has a first surface 2a and a second surface 2b opposite to the first surface 2a. A conductive composition 3 is applied to the mesh base material 2 to cover the first surface 2a and the second surface 2b. The conductive composition 3 on the side of the first surface 2a and the conductive composition 3 on the side of the second surface 2b are continuous through openings and internal voids of the mesh-like base material 2 . Here, as shown in FIG. 1, the first surface 2a side is completely covered with the conductive composition 3 so that the surface of the mesh-like base material 2 is not exposed to the outside. At least part of the monofilament forming the mesh base material 2 is exposed on the second surface 2b side, as shown in FIG. Only the monofilament may be partially exposed on the second surface 2b side, or a part of the thread other than the monofilament may be similarly exposed.

When the thread exposed on the second surface 2b side is the monofilament that constitutes the mesh-like base material 2, the shape of the exposed portion is a regular, substantially elliptical shape. If a multifilament is used and exposed, the shape of the exposed portion is highly likely to be irregular. When the mesh-like base material 2 is entirely composed of multifilaments, the shape of the exposed portion of the warp and weft on the second surface 2b side is all irregular, and due to this shape, the film is greatly damaged by bending. It is considered to be Therefore, it is essential that at least one of the warp and the weft of the mesh base material 2 used in the conductive fabric 1 of the present invention is composed of monofilaments.

Furthermore, regarding the area S ₁ of the portion coated with the conductive composition on the second surface and the area S ₂ of the portion where the warp and the weft are exposed, the value of S ₁ /S ₂ is 0.7. It is preferably in the range of ~10.0. More preferably, the value of S ₁ /S ₂ is in the range of 3.0 to 10.0.
_When the conductive fabric has openings, the area of the openings is not included in either _S1 or S2. Each of the areas S ₁ and S ₂ can be measured by magnifying the surface of the conductive cloth 1 with a microscope or the like.

In the conductive fabric 1 to which the conductive composition 3 is applied, the open area ratio is preferably 20% or less. If the opening ratio of the conductive cloth 1 is 20% or less, the conductive composition 3 is applied in a sufficient amount from the first surface 2a side of the mesh-like base material 2 toward the second surface 2b side. become. As a result, good conductivity can be obtained in the thickness direction.

Next, a method for manufacturing the conductive fabric 1 of the present invention will be described. A fabric woven by a conventional method can be used as the mesh-like base material 2 . However, as described above, it is essential that monofilaments be used for at least one of the warp and weft, and that the fabric be woven so that the open area ratio is 30% or more.

The mesh-like base material 2 may be subjected in advance to treatments such as scouring, dyeing, and heat setting by conventional methods. In addition, functional finishing such as flame-retardant finishing and water-repellent finishing may be applied.

When forming a film of the conductive composition 3 on the mesh-like substrate 2, a conductive composition ink containing components of the conductive composition 3 and having fluidity can be used. The conductive composition ink may contain a solvent in addition to the components of the conductive composition 3 . Furthermore, it may contain a viscosity modifier, a leveling agent, a wettability modifier, an antiseptic, a stabilizer, and the like.

The conductive composition ink is applied from the first surface side of the mesh-like substrate by a known coating method, and then the solvent is removed to form a film of the conductive composition, thereby obtaining the conductive fabric of the present invention. be done. Further, by applying the conductive composition ink from the first surface side of the mesh base material by a printing method, it is possible to obtain a conductive cloth on which a film of the conductive composition in a pattern is formed. It is possible to produce a conductive fabric in which a film of a patterned conductive composition functions as an electric circuit. As a method for removing the solvent, a known drying method is employed.

When the conductive composition ink is coated from the first surface side of the mesh-like substrate, the first surface side of the mesh-like substrate can be adjusted by adjusting the viscosity of the conductive composition ink and the setting conditions of the coating apparatus. It is important to control the second side so that at least part of the monofilament is exposed without exposing the warp and weft. Similarly, in the case of the printing method, it is necessary to examine the printing conditions and control so that at least a part of the monofilament is exposed only on the second surface side.

In the conductive fabric after removing the solvent, the area S ₁ of the portion coated with the conductive composition on the second surface side and the area S ₂ of the portion where the warp and the weft are exposed S ₁ /S ₂ is preferably in the range of 0.7 to 10.0. More preferably, the value of S ₁ /S ₂ is in the range of 3.0 to 10.0.

(Example 1)
A polyester mesh fabric: SMART-MESH120/300-40/34 (manufactured by Nihon Tokushu Textile Co., Ltd.) was prepared using monofilaments for both the warp and weft as the mesh base material. The opening ratio of this polyester mesh fabric was 33%. On one side of the polyester mesh fabric, solid printing was performed on the entire surface with ME603 (manufactured by DuPont) containing silver particles as a conductive composition ink. The screen printer used is SSA-PC560A (manufactured by Seria Engineering Co., Ltd.). Table 1 shows the printing conditions.

After printing, drying was performed at 100° C. for 5 minutes with DRS620DA (manufactured by Toyo Seisakusho Co., Ltd.) to form a film of the conductive composition. The open area ratio of the conductive cloth was 2.0%, the entire first surface was covered with a film of the conductive composition, and the S ₁ /S ₂ value of the second surface was 3.04. As shown in FIG. 2, the portion not covered with the conductive composition on the second surface side, ie, the portion where the warp and weft were exposed, had a substantially elliptical shape. The obtained conductive cloth had good conductivity in the thickness direction.

(Example 2)
The conductive composition ink was once printed on release paper EV120PXDH (B) (manufactured by Lintec Co., Ltd.) under the same conditions as in Example 1, transferred to the polyester mesh fabric used in Example 1, and then the release paper was removed. to obtain a conductive cloth. The obtained conductive cloth had an open area ratio of 1.1%, the entire first surface was covered with a film of the conductive composition, and the value of S ₁ /S ₂ on the second surface was 0.70. rice field. The obtained conductive cloth had good conductivity in the thickness direction.

(Example 3)
Conductive fabric in the same manner as in Example 1 except that SMART-MESH59/150-54 (manufactured by Nihon Tokushu Textile Co., Ltd.) was used as the base material, polyester mesh fabric made of monofilaments for both warp and weft and having an opening ratio of 46%. got The obtained conductive cloth had an open area ratio of 0.02%, the entire first surface was covered with a film of the conductive composition, and the value of S ₁ /S ₂ on the second surface was 10.0. rice field. The obtained conductive cloth had good conductivity in the thickness direction.

(Comparative example 1)
Instead of polyester mesh fabric, polyester plain fabric TE5880 (warp 30dtex/36f, 192 threads/inch, weft 62dtex/150f, 122 threads/inch, aperture ratio 3.0%) made of multifilament yarns for both warp and weft is used. A conductive cloth was obtained in the same manner as in Example 1 except that The open area ratio of this conductive cloth was 1.5%, and the value of S1/S2 _on the _second surface side was 1.12. As shown in FIG. 3, the portion not coated with the conductive composition on the second surface side, ie, the portion where the warp and weft were exposed, had an irregular shape without a regular shape. The obtained conductive cloth had good conductivity in the thickness direction, but the film of the conductive composition on the second surface side was not in a smooth state, so the electrical connection with the measuring instrument was somewhat poor. was stable.

For the conductive fabrics obtained in the above examples and comparative examples, bending tester No. A flexing test was performed using a 306 FPC FLEXING TESTER (manufactured by Yasuda Seiki Co., Ltd.), and the resistance values before and after the flexing test were measured with a HIOKI 3540 mΩ HiTESTER (manufactured by Hioki Electric Co., Ltd.). Table 2 shows the rate of increase in the resistance value after the bending test relative to the resistance value before the bending test as the resistance value increase rate (%). The test piece had a width of 1 cm, a length of 10 cm, and a bending angle of 180°. The number of times of bending is 15,000 times each in the front direction and the back direction at two different locations in the length direction, so the total number of bending times is 60,000.

1: Conductive fabric 2: Mesh-like base material 2a: First surface 2b: Second surface 3: Conductive composition

Claims (7)

A mesh-like base material which is a woven fabric having an open area ratio of 30% or more in which at least one of the warp and the weft is composed of monofilaments, and a first surface and a second surface opposite to the first surface of the mesh-like base material. The first surface side does not have a portion where the warp and weft yarns are exposed, and the second surface side has at least a portion of the monofilament that is regular and substantially elliptical An electrically conductive fabric having a shape exposed portion. On the second surface side, the value of S ₁ /S ₂ is 0 for the area S ₁ of the portion coated with the conductive composition and the area S ₂ of the portion where the warp and the weft are exposed. .7 to 10.0, the conductive fabric according to claim 1. On the second surface side, the value of S ₁ /S ₂ is 3 for the area S ₁ of the portion covered with the conductive composition and the area S ₂ of the portion where the warp and the weft are exposed. .0 to 10.0, the conductive fabric according to claim 1. The conductive fabric according to any one of claims 1 to 3, wherein the conductive fabric has an open area ratio of 20% or less. The conductive fabric according to any one of claims 1 to 4, wherein the conductive fabric has a thickness of 50 to 200 µm. A method for producing a conductive fabric, comprising applying a conductive composition ink from the first surface side of a mesh-like substrate and then drying to form a film of the conductive composition,
The mesh-like base material is a woven fabric with an opening ratio of 30% or more in which at least one of the warp and the weft is composed of monofilaments,
The first surface side does not have a portion where the warp and the weft are exposed, and at least a part of the monofilament is exposed in a regular and substantially elliptical shape on the second surface side opposite to the first surface. A method for producing a conductive fabric, characterized by forming a film of a conductive composition so as to have a portion where the conductive fabric is formed. On the second surface side, the value of S ₁ /S ₂ is 0 for the area S ₁ of the portion coated with the conductive composition and the area S ₂ of the portion where the warp and the weft are exposed. 7 to 10.0.

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