JP5558511B2 - Conductive nanofiber sheet and touch panel using the same - Google Patents

Description

  The present invention relates to a conductive nanofiber sheet using conductive nanofibers and a touch panel using the same.

  Conventionally, as a method of forming a layer made of nanofibers having a conductive layer on the surface of a substrate made of resin, glass, etc., for example, a coating liquid in which ultrafine conductive fibers are dispersed in a solution in which a binder resin is dissolved in a volatile solvent There is a method in which a conductive layer is formed by coating the surface of a substrate and drying the coating solution (see, for example, Patent Document 1).

  Examples of the nanofibers include metal nanofibers. In addition, in recent years, the conductive layer made of the metal nanofiber has been used as a thin electrode. On the other hand, a metal paste is often used in a routing circuit provided for electrical connection from the electrode to the outside. Then, use of the electroconductive nanofiber sheet containing the electrode which consists of metal nanofibers, and the drawing circuit which consists of metal pastes is tried.

Japanese Patent No. 3903159

  In the metal nanofiber used for the electrode and the metal paste used for the routing circuit, ion migration may occur during use. This “ion migration” is a phenomenon in which the metal component forming the wiring moves on the insulator due to the influence of the electric field between the wirings, thereby causing an electrical short circuit between adjacent wirings. For example, in a conductive nanofiber sheet that includes an electrode made of metal nanofiber and a routing circuit made of metal paste, the electrode made of metal nanofiber is relatively thin, whereas the routing circuit made of metal paste is compared. Thick. For this reason, when the adhesive sheet is bonded from the opposite direction on the side where the routing circuit is formed, the height (thickness) of the routing circuit is higher than the height (thickness) of the electrode. Air may enter the vicinity of the part, that is, the end part between the electrodes on the routing circuit side. When air enters the end portion between the electrodes on the side of the routing circuit in this way, the metal constituting the conductive nanofiber causes ion migration due to moisture and electric field contained in the air, and the metal is generated. A short circuit may occur.

  In particular, the inventor finds that ion migration may occur between the electrodes using conductive nanofibers due to the conductive nanofibers used in the electrodes, and considers suppression of ion migration between the electrodes. It is what.

  Then, the objective of this invention is providing the electroconductive nanofiber sheet which suppressed the ion migration by the metal nanofiber used for the electrode between the edge parts of two adjacent electrodes.

The conductive nanofiber sheet according to the present invention includes a base sheet,
Two or more electrodes provided on the base sheet, including conductive nanofibers, and capable of conducting through the conductive nanofibers;
Two or more routing circuits for making electrical connections from the electrodes to the outside,
An air shield layer made of an insulating resin provided between the ends of two adjacent electrodes;
Is provided.

  As described above, the conductive nanofiber sheet according to the present invention has an air shield layer between two adjacent electrodes. As a result, it is possible to suppress the migration between two adjacent electrodes and to obtain an effect of suppressing the occurrence of a short circuit.

1 is an exploded perspective view showing a configuration of a conductive nanofiber sheet according to Embodiment 1. FIG. FIG. 2 is a perspective plan view of the conductive nanofiber sheet of FIG. 1. It is sectional drawing seen from the AA direction of the electroconductive nanofiber sheet | seat of FIG. It is sectional drawing which shows the internal structure of the electrode of FIG. 6 is a perspective plan view showing a configuration of a conductive nanofiber sheet according to Embodiment 2. FIG. It is sectional drawing seen from the BB direction of the electroconductive nanofiber sheet | seat of FIG. 6 is a perspective plan view showing a configuration of a conductive nanofiber sheet according to Embodiment 3. FIG. It is sectional drawing seen from CC direction of the electroconductive nanofiber sheet | seat of FIG. 6 is a perspective plan view showing a configuration of a conductive nanofiber sheet according to Embodiment 4. FIG. It is sectional drawing seen from the DD direction of the electroconductive nanofiber sheet | seat of FIG. 6 is a cross-sectional view showing a cross-sectional structure of a touch panel according to Embodiment 5. FIG.

The conductive nanofiber sheet according to the first aspect of the present invention includes a base sheet,
Two or more electrodes provided on the base sheet, including conductive nanofibers, and capable of conducting through the conductive nanofibers;
Two or more routing circuits for making electrical connections from the electrodes to the outside,
An air shield layer made of an insulating resin provided between the ends of two adjacent electrodes;
Is provided.

  In the conductive nanofiber sheet according to the first aspect, the air shield layer may be disposed so as to divide the air layer between the two adjacent electrodes.

  Furthermore, in the conductive nanofiber sheet according to the first aspect, the air shield layer may have a triangular planar shape in which a vertex is located between two adjacent electrodes.

  Still further, in the conductive nanofiber sheet according to the first aspect, an apex angle of the triangle of the air shield layer may be 120 ° or less.

  In the conductive nanofiber sheet according to the first aspect, the base of the air shield layer facing the apex of the triangle may have a length of 100 μm or more.

  Furthermore, in the conductive nanofiber sheet according to the first aspect, the air shield layer may be further provided over at least one of the routing circuits from the ends of the two adjacent electrodes.

  Still further, in the conductive nanofiber sheet according to the first aspect, the air shield layer is disposed so as to divide an air layer between the two adjacent electrodes and at least one routing circuit. May be.

  In the conductive nanofiber sheet according to the first aspect, the air shield layer has a vertex located on the two adjacent electrodes, and a side corresponding to the vertex located on the routing circuit side. It may have a triangular planar shape.

The touch panel according to the second aspect of the present invention uses the conductive nanofiber sheet according to the first aspect as an electrode substrate.

  A conductive nanofiber sheet and a touch panel using the same according to an embodiment will be described with reference to the accompanying drawings. In the drawings, substantially the same members are denoted by the same reference numerals.

(Embodiment 1)
FIG. 1 is an exploded perspective view showing a configuration of a conductive nanofiber sheet 10 according to the first embodiment. FIG. 2 is a perspective plan view of the conductive nanofiber sheet 10 of FIG. FIG. 3 is a cross-sectional view of the conductive nanofiber sheet 10 of FIG. 2 as seen from the AA direction. FIG. 4 is a cross-sectional view showing an internal configuration of the electrode 2 of FIG. Referring to FIGS. 1 to 4, this conductive nanofiber sheet 10 is provided on base sheet 1 and base sheet 1, includes conductive nanofiber 12, and is conductive through conductive nanofiber 12. Between two or more possible electrodes 2a to 2d, two or more routing circuits 3a to 3d for making electrical connections from the electrodes 2a to 2d, respectively, and the ends of two adjacent electrodes 2a to 2d Provided are air shield layers 5a to 5c made of insulating resin, and adhesive sheets 4 provided on the electrodes 2a to 2d and the routing circuits 3a to 3d. In the conductive nanofiber sheet 10 according to the first embodiment, as described above, the air shield layers 5a to 5c are provided between the ends of the two adjacent electrodes 2a to 2d. As a result, the migration between the ends of the two adjacent electrodes 2a to 2d can be prevented, and the effect of suppressing the occurrence of a short circuit can be obtained.

  Below, each structural member which comprises the electroconductive nanofiber sheet | seat 10 which concerns on Embodiment 1 is demonstrated.

<Base material sheet>
Examples of the material of the base sheet 1 include resin films such as acrylic, polycarbonate, polyester, polybutylene terephthalate, polypropylene, polyamide, polyurethane, polyvinyl chloride, polyvinyl fluoride, and polyimide. The thickness of the base sheet 1 can be appropriately set within a range of 5 to 800 μm. If the thickness is less than 5 μm, the strength as a layer is insufficient and it will be torn when it peels off, making it difficult to handle. If the thickness exceeds 800 μm, the substrate sheet 1 is too rigid and difficult to process. In addition, flexibility cannot be obtained.

<Electrode>
In FIG. 1, each of the electrodes 2 (2a to 2d) includes a plurality of strip-shaped electrodes 2a to 2d. In this case, two conductive nanofiber sheets having a plurality of strip electrodes may be prepared, and the respective strip electrodes may be arranged so as not to overlap each other when viewed from the direction perpendicular to the surface. Thus, a touch panel can be comprised by arrange | positioning so that each strip-shaped electrode of two electroconductive nanofiber sheets may not overlap, and overlapping and joining. In this case, the detection sensitivity of the x-axis and the y-axis of the two conductive nanofiber sheets can be prevented from affecting each other.
In addition, although the case where the shape of the electrode 2 was a strip shape was illustrated above, the shape of the electrode 2 (2a to 2d) is not limited to a strip shape. For example, the electrode 2 may be composed of a plurality of rhombus electrodes connected in a diagonal direction.
Moreover, in FIG. 1, although the number of the electrodes 2a-2d is four, it is not restricted to this, Arbitrary numbers can be provided.

  The electrode 2 can be formed by patterning a conductive layer. As a conductive layer, what consists of photocurable resin binders 14, such as urethane acrylate and cyanoacrylate, and the conductive nanofiber 12, for example can be used. Further, the conductive layer can be provided by various general printing methods such as gravure printing, offset printing, screen printing, etc., or a dry film made of a photocurable resin 14 containing conductive nanofibers 12 or the like. It can also be provided by sticking a sheet.

  Furthermore, the conductive layer may be made of, for example, various resin binders 14 such as acrylic, polyester, polyurethane, and polyvinyl chloride, and conductive nanofibers 12. You may provide what consists of this various resin binders 14 and the electroconductive nanofiber 12 with various general-purpose printing methods, such as gravure printing, offset printing, and screen printing.

  The thickness of the conductive layer can be appropriately set in the range of several tens nm to several hundreds nm. When the thickness is less than several tens of nm, the strength as a layer is insufficient, and when the thickness is more than several hundred nm, the flexibility becomes insufficient.

<Conductive nanofiber>
The conductive nanofiber 12 has an aspect ratio in the range of approximately 10 to 100,000. When the aspect ratio is large, the conductive nanofibers 12 can easily come into contact with each other, and an effective electrode 2 can be formed. Moreover, since the whole density of the electroconductive nanofiber 12 becomes low because of high transparency, it becomes advantageous to obtain the highly transparent electrode 2. That is, by using the conductive nanofiber 12 having a high aspect ratio, the density of the conductive nanofiber 12 can be sufficiently lowered so that the electrode 2 is substantially transparent.

  In addition, when the diameter d of the conductive nanofiber 12 is increased, the resistivity is substantially decreased and the conductivity is improved. On the other hand, the light transmittance is decreased because more light is absorbed. As a result, transparency is deteriorated. Further, the influence on the resistivity based on the grain boundary and surface scattering becomes large when the diameter is less than 10 nm. These effects decrease rapidly as the diameter increases. The resistivity of the entire electrode 2 is greatly reduced when the diameter of the conductive nanofiber 12 is 10 nm to 100 nm. However, the above improvement in electrical characteristics needs to be balanced with a decrease in transparency of the transparent conductive film.

  As the conductive nanofiber 12, for example, silver, gold, copper, nickel, gold-plated silver, aluminum, or the like can be used. Specifically, as an example of the conductive nanofiber 12, an applied voltage or current is continuously applied to the surface of a precursor carrying metal ions such as gold, silver, platinum, copper, and palladium from the tip of the probe. Examples thereof include metal nanofibers prepared by pulling out and peptide nanofibers obtained by adding gold particles to nanofibers formed by self-organization of peptides or derivatives thereof. In addition, as the electroconductive nanofiber 12, it is not limited to the said illustration.

<Circuit circuit>
The routing circuit 3 takes out an electrical signal emitted from the electrode 2 to the outside. The routing circuit 3 can be used as long as it is a conductive material usually used as an electrical wiring. For example, a silver paste can be used. Alternatively, like the conductive layer, the conductive nanofiber 12 may be included.

<Adhesive sheet>
The adhesive sheet 4 can be used as long as it is an adhesive sheet using a generally used insulating resin. Moreover, this adhesive sheet 4 has adhesiveness. By using the adhesive sheet 4, the plurality of conductive nanofiber sheets 10 can be overlapped and joined, and the touch panel can be easily configured.

<Air shield layer>
The air shield layer 5 is made of an insulating resin. For example, an insulating resin similar to the binder resin 14 constituting the electrode 2 may be used. The air shield layer 5 can prevent the ion migration between the end portions of the two adjacent electrodes 2a to 2d and can suppress the occurrence of a short circuit.

  The air shield layer 5 is provided between the ends of two adjacent electrodes. The air shield layer 5 is arranged so as to divide the air layer 6 formed between two adjacent electrodes when the adhesive sheet 4 is bonded from the opposite side where the routing circuit 3 of the conductive nanofiber sheet 10 is formed. May be. If comprised in this way, when bonding the adhesive sheet 4 from the opposing side in which the routing circuit 3 of the electroconductive nanofiber sheet 10 was formed, the air shield layer 5 is the air layer 6 formed at the time of the bonding. After that, the separated air layer 6 can be moved to the electrode 2 side. For this reason, it is possible to prevent moisture contained in the air layer 6 that causes ion migration from existing between two adjacent electrodes. Thereby, the growth of the metal which comprises the electroconductive nanofiber by ion migration can be suppressed. Further, the air shield layer 5 may have a triangular planar shape in which a vertex is located between two adjacent electrodes. Alternatively, the shape may be other than a triangle. When the air shield layer 5 has a triangular shape, the apex angle may be 120 ° or less. When the apex angle is an acute angle of 120 ° or less and further 90 ° or less, the air layer between two adjacent electrodes is divided, and the air layer 6 is easily moved to the electrode 2 side. The bottom of the air shield layer 5 that faces the apex of the triangle may have a length of 100 μm or more. When the base has a length of 100 μm or more, the air shield layer 5 can be provided between two adjacent electrodes even if the positioning accuracy of the air shield layer 5 is low.

  In addition, as shown in Embodiments 3 and 4 to be described later, the air shield layer 5 may be further provided over at least one routing circuit 3 from the ends of two adjacent electrodes. The air shield layer 5 may be arranged so as to divide the air layer 6 between the two adjacent electrodes and at least one routing circuit 3. Furthermore, the air shield layer 5 may have a triangular planar shape in which a vertex is located on the side of two adjacent electrodes and a side corresponding to the vertex is located on the side of the routing circuit 3. Moreover, as shown in Embodiment 2 described later, each air shield layer 5 may be formed continuously, and adjacent air shield layers 5 may be provided so as to overlap each other.

(Embodiment 2)
FIG. 5 is a perspective plan view showing the configuration of the conductive nanofiber sheet 10a according to the second embodiment. 6 is a cross-sectional view of the conductive nanofiber sheet 10a of FIG. 5 as seen from the BB direction. Compared with the conductive nanofiber sheet according to the first embodiment, the conductive nanofiber sheet 10a according to the second embodiment is provided so that the bottom portions of the air shield layers 5 overlap as shown in FIG. Is different. That is, the conductive nanofiber sheet 10a is characterized in that the air shield layer 5 is continuously formed and the continuously formed air shield layers 5 are overlapped with each other.

  In this conductive nanofiber sheet 10a, since the air shield layer 5 is provided as described above, when the adhesive sheet 4 is pasted thereon, the air accumulated in the back surface portion where the air shield layer 5 is formed. Thus, ion migration between the electrodes 2 does not occur. As a result, it is possible to suppress the occurrence of ion migration between the electrodes when the touch panel created using the conductive nanofiber sheet 10a is energized.

  Furthermore, since the air shield layer 5 is continuously formed and the continuously formed air shield layers 5 are provided so as to overlap each other, the air accumulated on the back surface portion where the air shield layer 5 is formed is interposed. Thus, ion migration between the electrodes 2 can be further suppressed.

(Embodiment 3)
FIG. 7 is a perspective plan view showing the configuration of the conductive nanofiber sheet 10b according to the third embodiment. FIG. 8 is a cross-sectional view of the conductive nanofiber sheet 10b of FIG. 7 as seen from the CC direction. Compared with the conductive nanofiber sheet according to the first embodiment, the conductive nanofiber sheet 10b according to the third embodiment has a gap between the ends of two adjacent electrodes as shown in FIGS. In addition, the difference is that the air shield layer 5 is also provided in the routing circuit 3 portion. That is, in this conductive nanofiber sheet 10b, as shown in the cross-sectional view of FIG. 8, the air shield layer 5 is provided between the ends of the adjacent electrodes and over the routing circuit.

  In the conductive nanofiber sheet 10c, as described above, the air shield layer 5 is provided between the ends of the adjacent electrodes and over the routing circuit. As a result, air can also be excluded from the routing circuit 3 portion. As a result, when the adhesive sheet 4 is pasted thereon, ion migration does not occur between the electrodes 2 via the air accumulated in the back surface portion where the air shield layer 5 is formed. Then, it can suppress that ion migration generate | occur | produces between electrodes when it supplies with electricity to the touchscreen created using this electroconductive nanofiber sheet 10a.

(Embodiment 4)
FIG. 9 is a perspective plan view showing the configuration of the conductive nanofiber sheet 10c according to the fourth embodiment. 10 is a cross-sectional view of the conductive nanofiber sheet 10c of FIG. 9 as seen from the DD direction. As shown in FIG. 9, the conductive nanofiber sheet 10c according to the fourth embodiment is provided so that the bottom side portions of the air shield layers 5 overlap each other, as compared with the conductive nanofiber sheet according to the third embodiment. Is different. That is, the conductive nanofiber sheet 10c is characterized in that the air shield layer 5 is continuously formed on the electrode 2 side, and the continuously formed air shield layers 5 are overlapped with each other. To do.

  In the conductive nanofiber sheet 10c, as described above, the air shield layer 5 is provided between the ends of the adjacent electrodes and over the routing circuit. As a result, air can also be excluded from the routing circuit 3 portion. As a result, when the adhesive sheet 4 is pasted thereon, ion migration does not occur between the electrodes 2 via the air accumulated in the back surface portion where the air shield layer 5 is formed. Then, it can suppress that ion migration generate | occur | produces between electrodes when it supplies with electricity to the touchscreen created using this electroconductive nanofiber sheet 10a.

  Furthermore, since the air shield layer 5 is continuously formed and the continuously formed air shield layers 5 are provided so as to overlap each other, the air accumulated on the back surface portion where the air shield layer 5 is formed is interposed. Thus, ion migration between the electrodes 2 can be further suppressed.

  Furthermore, this conductive nanofiber sheet 10 c has the air shield layer 5 over the electrode 2 and the routing circuit 3. Therefore, when the adhesive sheet 4 is provided so as to cover the electrode 2 and the routing circuit 3 thereafter, the air shield layer 5 is formed on the adhesive sheet 4 so as to compensate for the recess between the electrode 2 and the routing circuit 3. Covered. As a result, when creating a touch panel with a smooth surface, the thickness of the adhesive sheet 4 can be reduced by the amount of the recess that the air shield layer 5 compensates. As a result, a thin conductive nanofiber sheet 10c can be obtained as a whole.

(Embodiment 5)
FIG. 11 is a cross-sectional view showing a cross-sectional structure of touch panel 20 according to the fifth embodiment. The touch panel 20 is an X electrode substrate and a Y electrode substrate using two conductive nanofiber sheets 10 according to the first embodiment. Note that the conductive nanofiber sheets 10a and 10b according to Embodiment 2 or 3 may be used. In FIG. 9, the liquid crystal display device 22 is disposed on the lower surface of the touch panel 20, and the protective plate 24 is disposed so as to cover the upper surface of the touch panel 20, thereby configuring the composite function display device 30.
As described above, since the air shield layer 5 is provided between the ends of the adjacent electrodes of each conductive nanofiber sheet 10, ion migration of the metal constituting the conductive nanofiber 12 can be suppressed, and occurrence of a short circuit can be prevented. The effect that it can suppress is acquired.

  In addition, the effect which each embodiment has can be show | played by combining suitably any embodiment of the said various embodiment.

  While the invention has been fully described in connection with preferred embodiments with reference to the accompanying drawings, various changes and modifications will be apparent to those skilled in the art. Such changes and modifications are to be understood as being included therein, so long as they do not depart from the scope of the present invention according to the appended claims.

  Since the conductive nanofiber sheet according to the present invention is provided with an air shield layer between the ends of adjacent electrodes, the ion migration of silver can be suppressed and the occurrence of a short circuit can be suppressed. Useful.

1 Base sheet 2, 2a, 2b, 2c, 2d Electrode (electrode pattern)
3, 3a, 3b, 3c, 3d Routing circuit 4 Adhesive sheet 5, 5a, 5b, 5c Air shield layer 6 Air layer 10, 10a, 10b, 10c Conductive nanofiber sheet 12 Conductive nanofiber 14 Binder resin 20 Touch panel 22 Liquid crystal display device 24 Protection plate 30 Multifunction display device

Claims (8)

A base sheet;
Two or more electrodes provided on the base sheet, including conductive nanofibers, and capable of conducting through the conductive nanofibers;
Two or more routing circuits for making electrical connections from the electrodes to the outside,
An air shield layer made of an insulating resin provided between the ends of two adjacent electrodes;
Equipped with a,
The conductive nanofiber sheet , wherein the air shield layer is arranged to divide an air layer between the two adjacent electrodes . A base sheet;
Two or more electrodes provided on the base sheet, including conductive nanofibers, and capable of conducting through the conductive nanofibers;
Two or more routing circuits for making electrical connections from the electrodes to the outside,
An air shield layer made of an insulating resin provided between the ends of two adjacent electrodes;
With
The air shield layer is a conductive nanofiber sheet having a triangular planar shape with a vertex located between two adjacent electrodes. The conductive nanofiber sheet according to claim 2 , wherein an apex angle of the triangle of the air shield layer is 120 ° or less. 3. The conductive nanofiber sheet according to claim 2 , wherein a bottom side of the air shield layer facing the apex of the triangle has a length of 100 μm or more.   2. The conductive nanofiber sheet according to claim 1, wherein the air shield layer is further provided from the end portions of two adjacent electrodes to at least one of the routing circuits. The conductive nanofiber sheet according to claim 5 , wherein the air shield layer is disposed so as to divide an air layer between the two adjacent electrodes and at least one routing circuit. The air shield layer is positioned vertex on the side of two adjacent electrodes have a planar shape of triangle sides is positioned corresponding to the apex on a side of the routing circuits, conductive claim 5 Nanofiber sheet. A touch panel using the conductive nanofiber sheet according to any one of claims 1 to 7 as an electrode substrate.

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