JP5799184B1 - Transparent conductive laminate and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an extremely thin and light transparent conductive laminate excellent in flexibility even when bent, an electrode using the laminate, a wearable device, a biological device, and a method for producing the laminate . A transparent conductive laminate comprising at least a transparent conductive layer laminated on a surface of a transparent substrate, wherein the total thickness t of the transparent conductive laminate is 0.5 μm <t≰10 μm or less, When the test of bending the transparent conductive laminate on a mandrel rod having a diameter of 2 mm and bending the transparent conductive layer side by 180 degrees along the transparent conductive layer side to the mandrel rod side was performed 50 times, the surface resistance value of the transparent conductive layer after the test was The transparent conductive laminate is characterized in that the rate of change is 10% or less compared to the surface resistance value of the transparent conductive layer before the test. [Selection figure] None

Description

The present invention relates to a very thin transparent conductive laminate and a method for producing the transparent conductive laminate, more specifically, having a transparent conductive layer on the surface of a very thin transparent substrate, having excellent flexibility and The present invention relates to a very thin transparent conductive laminate with little change in resistance before and after bending, a method for producing the transparent conductive laminate, and a transparent electrode using the transparent conductive laminate.

Transparent conductive laminates are widely used as electrodes for flat devices such as touch panels, liquid crystal displays, and plasma displays. In recent years, however, it has been used as an electrode for so-called wearable devices that are worn on curved surfaces or flexible objects such as the human body or clothing, such as wrapping a display around an arm or attaching an electrode to clothing or skin. It is supposed to be.

Wearable devices are used by directly wearing or embedding a device that has been carried as a terminal until now. Such wearable devices are used for various purposes such as acquisition of information and use as power generation elements. Not only devices that are worn outside the body, such as wristwatch-type terminals and eyeglass-type displays that are already under development, but also electrodes that are directly attached to the skin, used as electronic skin integrated with the skin, It has a wide range of uses, such as pasting and embedding in organs. For example, the wearable biosensor can acquire biometric information such as heartbeat, respiration, movement, body temperature, and body fat percentage by attaching electrodes directly to the body. In addition, by attaching electrodes to pulsating organs, low-frequency treatment devices used for the treatment of functional disorders, testing and diagnostic equipment such as electrocardiographs, electromyographs, electroencephalographs, postoperative rehabilitation, etc. A weak current can be sent stably into the body.

The electrodes used in such wearable devices can be used by shaping them so that they conform to a curved surface or a flexible body such as the human body or clothing, or by attaching directly to the target adherend. To do. Therefore, it is necessary to have flexibility so as to follow the adherend. In view of this, the production of a transparent electrode rich in flexibility in which a transparent conductive layer is laminated on a flexible base material has been studied.

Patent Document 1 discloses a transparent conductive film in which graphene is laminated on a polymer resin film via a resin layer. Since the polymer resin film and graphene have flexibility, a device using the transparent conductive film as an electrode can be bent by such a configuration. Further, if a transparent base material is selected, a circuit is not visually recognized as in the case of a conventional metal electrode, so that a device with improved transparency and design can be obtained.

JP2014-124898A

However, the conventional transparent conductive film has a problem that when the bending becomes large, the conductivity is lowered due to cracks in the conductive layer due to the rigidity of the base material. In addition, if the base material has a high rigidity, it is difficult to follow it completely even if it is attached to an organ with many curved surfaces, for example. Furthermore, biosensors and the like need to be worn for a long time in order to detect slight changes in biometric information, but conventional transparent conductive films require an adhesive layer or the like to be attached to an object. Therefore, there are many things that have a sense of incongruity or discomfort due to wearing. Also, the thickness and weight of the base material are not preferable because they cause a feeling of wearing. Even if you try to make the base material thinner in order to deal with such problems, the thin base material is poor in handling, and it is not suitable for processing with wrinkles or insufficient heat resistance. It was difficult to use.

The present invention has been made in view of such problems, and an object of the present invention is to provide a very thin and light transparent conductive laminate having excellent flexibility, and a method for producing the same, which does not lower conductivity even when bent. Is to provide.

In order to solve the above problems, the invention related to the transparent conductive laminate according to claim 1 of the present invention is a transparent conductive laminate in which a transparent conductive layer made of at least graphene is laminated on the surface of a transparent substrate, When the total thickness of the transparent conductive laminate is t, 0.5 μm <t ≦ 10 μm, and the transparent conductive laminate is aligned with a mandrel rod having a diameter of 2 mm so that the transparent conductive layer side is on the mandrel rod side. When the test for bending 180 degrees is performed 50 times, the surface resistance value of the transparent conductive layer after the test is 10% or less compared to the surface resistance value of the transparent conductive layer before the test. It is characterized by.

The invention relating to the transparent conductive laminate according to claim 2 of the present invention is the transparent conductive laminate according to claim 1 , wherein the transparent conductive layer has a visible light transmittance of 90% or more. And

0.5μm when invention relates to a transparent conductive laminate according to claim 3 of the present invention is a transparent conductive laminate according to claim 1 or claim 2, in which the thickness of the transparent substrate was set to t ₁ ≦ t ₁ <10 μm.

The invention related to the transparent conductive laminate with a carrier according to claim 4 of the present invention is the transparent conductive laminate according to any one of claims 1 to 3 , wherein the transparent conductive layer of the transparent substrate is the transparent conductive layer. A carrier base material is stuck on the surface opposite to the laminated surface.

The invention relating to the transparent electrode according to claim 5 of the present invention is peeled from the transparent conductive laminate according to any one of claims 1 to 3 or the transparent conductive laminate with carrier according to claim 4. It is characterized by using the transparent conductive laminated body made.

The invention relating to the wearable device according to claim 6 of the present invention is characterized by using the transparent electrode according to claim 5 .

The invention relating to the biological device according to claim 7 of the present invention is characterized by using the transparent electrode according to claim 5 .

The invention relating to the method for producing a transparent conductive laminate according to claim 8 of the present invention includes a step of attaching a carrier substrate to the surface of the transparent substrate to obtain a transparent substrate with a carrier, and the transparent substrate with a carrier. And laminating a transparent conductive layer made of graphene on the surface of the transparent base material to obtain a transparent conductive laminate with carrier, and peeling the carrier base material from the transparent conductive laminate with carrier. A method for producing a transparent conductive laminate, wherein the total thickness of the transparent conductive laminate is t, and 0.5 μm <t ≦ 10 μm, and the obtained transparent conductive laminate is applied to a mandrel rod having a diameter of 2 mm. When the test of bending 180 degrees along the transparent conductive layer side to the mandrel rod side was performed 50 times, the surface resistance value of the transparent conductive layer after the test was The rate of change is 10% or less in comparison with the surface resistance value.

An invention relating to a method for producing a transparent conductive laminate according to claim 9 of the present invention is the method for producing a transparent conductive laminate according to claim 8 , wherein the transparent conductive substrate is obtained in the step of obtaining the transparent substrate with a carrier. The base material is attached by overlapping the carrier base material and the transparent base material and irradiating a charging gun from the transparent base material side.

An invention relating to a method for producing a transparent conductive laminate according to claim 10 of the present invention is the method for producing a transparent conductive laminate according to claim 8 or 9 , wherein the transparent conductive laminate with carrier is obtained. In the step, the transparent conductive layer is formed by forming a transparent conductive layer with a release substrate by laminating the transparent conductive layer on the surface of the release substrate. The material side surface and the transparent conductive layer side are bonded together to remove the releasable base material.

The invention relating to the method for producing a transparent conductive laminate according to claim 11 of the present invention is the method for producing a transparent conductive laminate according to claim 10 , wherein the releasable substrate is a heat release sheet. It is characterized by.

The invention related to the method for producing a transparent conductive laminate according to claim 12 of the present invention is the method for producing a transparent conductive laminate according to any one of claims 8 to 11 , wherein the transparent conductive layer is formed. Is formed by chemical vapor deposition (CVD).

The invention related to the method for producing a transparent conductive laminate according to claim 13 of the present invention is the method for producing a transparent conductive laminate according to any one of claims 8 to 12 , wherein the transparent conductive layer is formed. The visible light transmittance is 90% or more.

An invention relating to a method for producing a transparent conductive laminate according to claim 14 of the present invention is the method for producing a transparent conductive laminate according to any one of claims 8 to 13 , wherein the transparent base material is used. When the thickness of t ₁ is t ₁ , 0.5 μm ≦ t ₁ <10 μm.

Conventionally, transparent conductive laminates need to have a certain degree of rigidity and thus have low flexibility, and if they are bent many times, the resistance value becomes large and performance as a conductive film cannot be obtained. However, in the transparent conductive laminate according to the present invention, since the total thickness is very thin, greater than 0.5 μm and 10 μm or less, the rigidity is small, the flexibility is excellent, and the object has many complicated curved surfaces such as organs. Can also follow. In addition, since the rate of change of the surface resistance value due to bending is as small as 10% or less, the resistance value does not increase significantly even if it is rounded or bent, for example, before bending, that is, the conductivity is reduced. Since it can be maintained, a stable electrode can be obtained. In addition, because it is very thin and light, even a weak interaction such as van der Waals force can be attached to the object without peeling off due to its own weight. It is not necessary to provide an adhesive layer. Thereby, even if it wears, there is no sense of incongruity or wearing, and it can be used for a long time. Furthermore, since the visible light transmittance is also good, it can be suitably used for applications where transparency is required, and the width is widened in design.

And in the conventional method for producing a transparent conductive laminate, producing a transparent conductive laminate having a very thin transparent substrate and a transparent conductive layer as in the present invention is due to problems such as handling properties and heat resistance. Although it was very difficult, if it is the manufacturing method of the transparent conductive laminated body concerning this invention, it can manufacture easily. Moreover, since the transparent base material and the transparent conductive layer are very thin, it is not necessary to provide an adhesive layer when transferring the transparent conductive layer to the transparent base material, and can be laminated only by van der Waals force. It can be made very thin compared to the conductive laminate.

Embodiments of the present invention will be described below. Note that the embodiment shown here is merely an example, and is not necessarily limited to this embodiment.

(Embodiment 1)
A transparent conductive laminate and a method for manufacturing the same according to the present invention will be described as a first embodiment.

The transparent conductive laminate according to the present embodiment is a transparent conductive laminate in which at least a transparent conductive layer is formed on the surface of a very thin transparent substrate.

Hereinafter, the description will be made in order.
First, the transparent substrate is not particularly limited as long as it is a transparent substrate generally used in a conventionally known transparent conductive laminate and excellent in flexibility. Examples of such transparent substrates include polydimethylsiloxane (PMDS), polyphenylsulfide (PPS), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), Films and sheets of polyimide (PI), polyamideimide (PAI), acrylic resin, cellulose resin, norbornene resin, etc., and glass with excellent flexibility can be considered. In this embodiment, A PET film is used.

The thickness of the transparent substrate is not particularly limited as long as the total thickness t of the finally obtained transparent conductive laminate is 0.5 μm <t ≦ 10 μm, but is preferably 0.5 μm or more and less than 10 μm. . When the thickness of the transparent substrate is 10 μm or more, the rigidity increases and the flexibility decreases, so that the transparent conductive laminate according to the present embodiment cannot conform to various shapes having curved surfaces and irregularities. In addition, since the substrate having such a high rigidity is repelled when bent, the transparent conductive layer described later is cracked when the resulting transparent conductive laminate is bent, and the conductive Cause a drop. Moreover, if the thickness of the transparent substrate is increased, the entire thickness of the transparent conductive laminate is also increased and becomes heavier, which is not preferable because the feeling of discomfort due to mounting increases. Furthermore, the increase in the thickness of the substrate is not preferable because the visible light transmittance is reduced and the visible light transmittance of the entire transparent conductive laminate is also lowered. Therefore, the thinner the transparent substrate, the less rigid and preferable because the entire transparent conductive laminate becomes thin and light.However, if it is too thin, the transparent conductive laminate according to the present embodiment is repeatedly processed or obtained. Since the transparent base material is damaged in the scene to be used, that is, the function as the transparent conductive laminate is damaged, it is preferable that the thickness is 0.5 μm or more. In this embodiment, it is 2 μm.

The transparent substrate according to the present embodiment preferably has a visible light transmittance of 85% or more. If it is a transparent base material which has a visible light transmittance of 85% or more, it can be set as the transparent conductive laminated body with sufficient transparency. In this embodiment, a PET film having a visible light transmittance of 85% is used.

A transparent substrate with a carrier is obtained by attaching a carrier substrate to the transparent substrate. The transparent substrate with a carrier will be described.

First, the carrier substrate will be described.
Although it will not specifically limit as a carrier base material if it becomes a support body of a transparent base material, What is necessary is just to select what is easy to use in a post process suitably. Specifically, it is a resin film, a silicon wafer, a metal plate, a glass plate, or the like.

By laminating the carrier base material and the transparent base material and sticking them while stretching wrinkles with a rubber roll or the like, a transparent base material with a carrier can be obtained. At this time, since the carrier substrate and the transparent substrate are in close contact by electrostatic interaction, an adhesive layer such as an adhesive is not necessary. In addition, since there is no adhesive layer, when the carrier substrate is peeled later, there is no adhesive residue and it can be easily peeled off.

In the sticking step of the transparent base material and the carrier base material, a charging gun may be irradiated from the transparent base material side to the carrier base material and the transparent base material which are overlapped when sticking with a rubber roll. By adding such a process, the transparent base material is charged, and the electrostatic interaction between the transparent base material and the carrier base material becomes stronger and can be adhered without gaps.

Next, the transparent conductive layer will be described.
As the transparent conductive layer according to the present embodiment, a transparent conductor conventionally used may be used as long as it is transparent and rich in flexibility. For example, a conductive resin layer coated with a metal oxide such as ITO, a resin having a conductive filler, or the like, graphene, or the like can be considered.

The visible light transmittance of the transparent conductive layer is preferably 90% or more. If it is a transparent conductive layer having such a visible light transmittance, the visible light transmittance of the transparent conductive laminate is increased, and a very transparent transparent conductive laminate can be obtained. Such a transparent conductive laminate can be suitably used for applications that require transparency, such as affixing to display electrodes or affected areas. In addition, in applications such as biosensors that are attached to the surface of the skin, or applications that are attached to the surface such as being worn on the body, problems such as an uncomfortable appearance or trouble in the design may occur if the electrodes are visible. However, if the transparent conductive laminate according to the present embodiment is transparent, the transparent conductive laminate is inconspicuous, so that there is no wearing feeling and the design is improved.

The thickness of the transparent conductive layer is not particularly limited as long as the total thickness t of the obtained transparent conductive laminate is 0.5 μm <t ≦ 10 μm and satisfies the visible light transmittance of the target transparent conductive layer, The thinner one is desirable from the viewpoint of flexibility. For example, when the transparent conductor is graphene, the thickness is preferably 0.5 nm or more and 10 nm or less. When it is thicker than 10 nm, the transparency is lowered, and when it is thinner than 0.5 nm, it is difficult to obtain desired conductivity.

As described above, a transparent conductive layer having a desired characteristic may be used as appropriate, but graphene is particularly preferable. Graphene is a film having a two-dimensional structure of sp ² -bonded carbon atoms. Although it is a very thin film, it has good visible light transmittance and conductivity, and has excellent flexibility. Therefore, it can be used for various applications even when compared with other transparent conductive layers.

For example, a transparent conductive layer made of PEDOT / PSS (a conductive polymer composed of polyethylene dioxythiophene and polystyrene sulfonic acid) tends to have a low visible light transmittance when trying to improve conductivity. It is difficult to meet. Moreover, although metal nanowires using silver or copper have high conductivity and transparency, such metal nanowires oxidize and thus lack durability compared to graphene. Furthermore, it is assumed that metal allergy becomes a problem when used in close contact with a living body. On the other hand, since graphene is excellent in conductivity even in a thin film as described above, it can be a very thin transparent conductive laminate having conductivity and excellent transparency. There is no sense of incongruity and it can be set as the electrode excellent in transparency. In addition, since it is composed only of carbon, it has high biocompatibility and is very effective when used for in vivo use, for example, for application to the skin surface or internal organs. Furthermore, since a graphene film is transferred to a transparent base material a plurality of times to form a laminated structure, a transparent conductive layer with higher conductivity can be obtained, so that higher conductivity can be easily obtained with a thin film thickness. Can do.

The transparent conductive layer as described above is laminated on the transparent substrate with carrier to obtain a transparent conductive laminate with carrier, and the lamination method may be appropriately selected depending on the transparent conductive layer to be formed. . Examples thereof include physical vapor deposition (PVD) such as sputtering, vapor deposition, and ion plating, chemical vapor deposition (CVD), and wet coating.

Here, the transparent conductive layer is not only directly laminated on the transparent substrate with a carrier, but a transparent conductive layer formed on another substrate may be transferred to the transparent substrate with a carrier and used. With such a manufacturing method, it is not necessary to limit the film forming method in accordance with the performance of the transparent substrate, so that a transparent conductive layer having characteristics according to the purpose can be formed. For example, graphene formed by CVD is very thin, transparent, and highly conductive, but the substrate temperature during film formation becomes very high, so when trying to laminate directly on a transparent substrate with a carrier, It is necessary to use a base material having very high heat resistance, and there are problems that the intended thinness cannot be obtained or the transparency is lowered. However, even in such a transparent conductive layer, if the transfer method as described above is used, the transparent conductive layer may be formed on a highly heat-resistant substrate and then transferred to a transparent substrate with a desired carrier. The transparent base material with a carrier may not necessarily have heat resistance. Therefore, when heat resistance is not particularly required as a required characteristic, it is not necessary to select a substrate with high heat resistance for the lamination of the transparent conductive layer, and there are restrictions on substrate selection, film formation method, etc. Can be prevented.

As such a transfer method, it is preferable to use a transparent conductive layer with a releasable substrate in which a transparent conductive layer is appropriately laminated on a releasable substrate. The transparent conductive layer with a releasable substrate may be laminated directly on the releasable substrate, or the transparent conductive layer formed on another substrate is bonded to the releasable substrate. The substrate may be removed. At this time, the base material on which the transparent conductive layer is formed is not particularly limited as long as it is suitable for the transparent conductive layer lamination method and laminate and can be finally removed. For example, when graphene is formed by CVD, a metal foil such as a copper foil, a release film in which a catalyst layer is laminated, or the like can be considered. In the present embodiment, graphene is formed on a copper foil by CVD, and a copper foil is etched by attaching a releasable base material to the graphene surface.

Since the transparent conductive layer concerning this Embodiment is very thin, when transferring to a transparent base material with a carrier, there exists a possibility that a layer may be damaged. However, by sticking the releasable base material in this way, it is possible to prevent the transparent conductive layer from being damaged when the base material is removed. Such a releasable substrate is not particularly limited as long as it can hold a transparent conductive layer and can be easily peeled later, but is preferably a heat-release sheet. The heat release sheet can easily transfer the transparent conductive layer to the target object without being damaged by heating.

The transparent conductive layer side surface of this transparent conductive layer with a releasable base material and the transparent base material side surface of the transparent base material with a carrier are overlapped, and bonded together while stretching wrinkles with a rubber roll or the like to peel off the releasable base material. By doing so, a transparent conductive laminate with a carrier can be obtained. At this time, the transparent conductive layer and the transparent substrate are brought into close contact with each other by van der Waals force. Since the transparent conductive layer and the transparent substrate according to this embodiment are very thin and light, sufficient adhesion can be obtained even by a weak interaction such as van der Waals force. Therefore, since an adhesive layer such as an adhesive is not required in the lamination, the entire thickness of the transparent conductive laminate can be further reduced.

By peeling the carrier substrate from the obtained transparent conductive laminate with carrier, a very thin transparent conductive laminate is obtained. In the present embodiment, the carrier base material and the transparent base material of the transparent conductive laminate are not laminated by an adhesive layer or the like but are stuck by an electrostatic force, and thus can be easily peeled off. The obtained transparent conductive laminate has a total thickness t of 0.5 μm <t ≦ 10 μm, which is very thin and light. Therefore, the rigidity is small and the flexibility is excellent. Furthermore, it is excellent in transparency and is useful for applications requiring transparency.

The transparent conductive laminate according to the present embodiment is a test in which a mandrel bar having a diameter of 2 mm described in JIS K 5600-5-1 is bent 180 degrees along the transparent conductive layer side to be the mandrel bar side. Even after 50 tests, the rate of change of the surface resistance value of the transparent conductive layer after the test with respect to the surface resistance value of the transparent conductive layer before the test is 10% or less, and the decrease in conductivity due to bending is negligible. . In the conventional transparent conductive laminate, when such a test is performed, delamination occurs or cracks occur and the surface resistance value increases, and it is difficult to obtain stable conductivity. However, with the transparent conductive laminate according to the present embodiment, the surface resistance value hardly changes even after the extremely severe test as described above, and the electrode has excellent durability against bending. be able to.

Since the transparent conductive laminate according to the present embodiment is very thin and light, and is transparent, the carrier substrate may be used without peeling off as a support substrate until storage or transfer. This is because, with the support, for example, workability such as surface treatment and cutting process of the transparent conductive laminate is maintained, so that it may be preferable to have a carrier.

The transparent conductive laminate obtained as described above is a very thin and light transparent conductive laminate in which a transparent conductive laminate is laminated on the surface of a very thin transparent substrate. At this time, since the total thickness t of the transparent conductive laminate is as very thin as 0.5 μm <t ≦ 10 μm, it has excellent flexibility and the conductivity hardly changes even after being bent. Therefore, it can be made to follow an adherend with many curved surfaces and irregularities, and a transparent electrode can be obtained that provides stable conductivity. In addition, when the transparent conductive laminate according to the present embodiment is directly attached to the skin, it is very thin and light, so that the feeling of wearing due to the attachment is diminished and the adherend is weak such as van der Waals force. Since it can be sufficiently adhered even by force, it is not necessary to provide an adhesive layer or the like when transferring to the adherend, and there is no discomfort or discomfort due to wearing. Furthermore, since it is excellent in transparency, it can be used for applications requiring transparency. Since it has such a characteristic, the transparent conductive laminated body concerning this Embodiment can be used as a transparent electrode of various uses. In particular, it is useful as an electrode for wearable devices and biomedical devices, such as making it inconspicuous even if it is affixed to the body surface or the like, or affixing directly to an affected part of an organ.

Moreover, if it is a manufacturing method of the transparent conductive laminated body as described above, the transparent conductive laminated body concerning this Embodiment can be manufactured easily. In the conventional method for producing a transparent conductive laminate, it is very difficult to produce a transparent conductive laminate having a very thin transparent substrate and a transparent conductive layer as in the present invention due to problems such as handleability and processability. Although it was difficult, if it is a method for producing a transparent conductive laminate according to the present invention, it is not necessary to laminate a transparent conductive layer directly on a transparent substrate. Since it is thin, handling does not deteriorate, and it can be manufactured easily. In addition, since the transparent substrate and the transparent conductive layer are very thin, it is not necessary to provide an adhesive layer for bonding, and can be laminated only by van der Waals force, which is very thin compared to conventional transparent conductive laminates Can be.

The transparent conductive laminate according to the present invention and the transparent electrode using the laminate will be described below with further examples, but the present invention is not limited to these examples.

(Transparent conductive layer with releasable substrate)
Rolled copper foil (Fukuda Metal Foil Powder Co., Ltd.) was put in a vacuum chamber, the pressure was reduced to 1.0 × 10 ⁻³ Pa or less, and the copper foil was heated with a heater. Thereafter, while introducing methane and hydrogen gas into the chamber at a ratio of 1: 300, surface wave plasma was generated by microwaves to form graphene on the copper foil. The pressure at the time of film formation was about 4 Pa, and the film formation was performed for a time determined by each level. Next, the graphene surface formed on the copper foil and an adhesive sheet (manufactured by Nitto Denko Corporation) were bonded together, and the copper foil was dissolved with an aqueous ammonium persulfate solution (10% by weight). Thereafter, it was sufficiently washed with ion exchange water to obtain a transparent conductive layer with a releasable substrate.

(Transparent substrate with carrier)
Using a 2 μm PET film as a transparent substrate, overlaying it on a 188 μm PET film (Mitsubishi Resin Co., Ltd.) as a carrier substrate, setting a charging gun (manufactured by Green Techno Co., Ltd.) to 5 kV on the 2 μm PET film and irradiating for several seconds Further, the heels were stretched with a silicon rubber roll and bonded by electrostatic interaction to obtain a transparent substrate with a carrier.

Example 1
A transparent conductive layer with a releasable substrate is prepared with a graphene film formation time of 2 minutes, and a graphene surface of the transparent conductive layer with a releasable substrate and a 2 μm PET film surface of a transparent substrate with a carrier are used with a rubber roll. The pressure-sensitive adhesive sheet was peeled off by applying heat at 100 ° C. for 1 minute. Thereafter, the 188 μm PET film was peeled off to obtain a transparent conductive laminate 1 composed of a 2 μm PET film and graphene.

(Example 2)
Two transparent conductive layers with a releasable substrate are prepared with a film formation time of graphene of 2 minutes, and a 2 μm PET film of a graphene surface of one of the transparent conductive layers with a releasable substrate and a transparent substrate with a carrier The surfaces were bonded using a rubber roll, and the adhesive sheet was peeled off by applying heat at 100 ° C. for 1 minute to obtain a transparent conductive laminate with a carrier. After that, the other graphene surface of the transparent conductive layer with the releasable substrate is bonded so as to face the graphene surface of the transparent conductive laminate with carrier, and the adhesive sheet is peeled off by applying heat at 100 ° C. for 1 minute. Finally, the 188 μm PET film was peeled off to produce a transparent conductive laminate 2 in which the graphene layer was laminated twice on the 2 μm PET film.

(Example 3)
A target transparent conductive laminate 3 was produced using the same method as in Example 1 except that the graphene film formation time was changed to 40 seconds.

Example 4
A target transparent conductive laminate 4 was produced using the same method as in Example 1 except that the transparent substrate was changed from a 2 μm PET film to a 6 μm PET film.

(Comparative Example 1)
A transparent conductive layer with a releasable substrate was prepared with a graphene film formation time of 2 minutes, and the graphene surface of the transparent conductive layer with a releasable substrate and a 50 μm PET film were bonded together using a rubber roll, The adhesive sheet was peeled off by applying heat for 1 minute to obtain a transparent conductive laminate 5 composed of a 50 μm PET film and graphene.

(Comparative Example 2)
A target transparent conductive laminate 6 was produced in the same manner as in Comparative Example 1 except that the transparent substrate described in Comparative Example 1 was changed from a 50 μm PET film to a 188 μm PET film.

The physical properties of the transparent conductive laminates obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were determined by the methods described below.

(Visible light transmittance)
The transmittance (%) at 550 nm of the transparent base material before forming the transparent conductive layer and the transparent conductive layered body after forming the transparent conductive layer was measured with a UV-VIS ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation: “SolidSpec3700DUV”). And the transmittance | permeability of the transparent conductive layer was calculated | required by following (Formula 1). The unit of each transmittance is%.

(Formula 1)
Transmissivity of transparent conductive layer = 100− (Transmittance of transparent substrate only−Transmittance of transparent conductive laminate)

(thickness)
It is known that the transmittance of graphene at 550 nm decreases by about 2.3% for each layer. Further, since the thickness of graphene is one atomic layer (about 0.3 nm), the approximate thickness of the transparent conductive layer was calculated using the transmittance of the transparent conductive layer. The thickness of the transparent substrate was measured at an arbitrary five points by a palpation type digital multimeter (manufactured by Mitutoyo Corporation), and the average value was obtained. The total thickness of the obtained transparent conductive laminate was calculated as the sum of the thickness of the transparent conductive layer and the thickness of the substrate.

(Surface resistance value)
The surface resistance value of the transparent conductive laminate was measured at any five points using “Loresta GP” manufactured by Mitsubishi Chemical Analytech Co., Ltd., and the average value was used.

(Bending test)
The bending test was performed 50 times by bending a transparent conductive laminated body 180 ° along the mandrel bar using a mandrel bar described in JIS K5600-5-1 having a mandrel diameter of 2 mm. At this time, it carried out with the transparent conductive layer side being the mandrel rod side.

(Resistance change rate)
Before and after performing the above bending test, a sample was cut into a size of 25 × 60 mm, Ag paste was applied to both ends 5 × 25 mm width on the surface of the transparent conductive layer and dried, and the resistance between terminals between the Ag pastes was tested for bending. Before and after measurement using a tester, the resistance change rate was obtained by the following (Equation 2). The unit of resistance change rate is%, and the unit of each resistance value is Ω.

(Formula 2)
Resistance change rate = (resistance value after bending−resistance value before bending) / resistance value before bending × 100

In Examples 1 to 4 and Comparative Examples 1 and 2, the transmittance of the transparent conductive layer, the thickness of the transparent conductive layer, the thickness of the substrate, the total thickness of the transparent conductive laminate, and the surface resistance of the transparent conductive laminate The values and the resistance change rate before and after the bending test are shown in Table 1.

(Table 1)

From Table 1, it is understood that Comparative Example 1 and Comparative Example 2 in which the total thickness of the transparent conductive laminate is greater than 10 μm has a resistance change rate of 10% or more before and after the bending test, and the conductivity decreases due to bending. . On the other hand, Examples 1 to 4 in the range of 0.5 μm <t ≦ 10 μm, where t is the total thickness of the transparent conductive laminate, have a resistance change rate of 10% or less before and after the bending test. The decrease in conductivity due to the test is minute. This is because when the total thickness t of the transparent conductive laminate becomes thicker than 10 μm, the rigidity of the laminate increases, and cracks and missing portions occur in the transparent conductive layer by bending it many times. It is thought that. In general, it is known that the rigidity of a substance increases as the thickness increases, and if the total thickness t of the transparent conductive laminate is 0.5 μm <t ≦ 10 μm as in Examples 1 to 4, the transparent conductive Since the rigidity of the laminate is sufficiently small, the repulsion due to bending is small, and the conductivity is not lowered because there are few cracks and missing parts in the transparent conductive layer. Therefore, if the total thickness t of the transparent conductive laminate is 0.5 μm <t ≦ 10 μm, the rate of change in resistance before and after the bending test is 10% or less, and the transparent conductive laminate is durable against bending. I understand. In Examples 1 to 4, the surface resistance value and transmittance are the same as or better than those of Comparative Example 1 and Comparative Example 2. That is, it can be seen that Examples 1 to 4 are transparent conductive laminates that not only have a small change in resistance before and after bending, but also have good conductivity and transparency.

In the embodiment of the present invention, since a very thin transparent conductive layer of about several nanometers is used, the thickness of the base material and the total thickness of the transparent conductive laminate are the same. As long as the total thickness t of the film is in the range of 0.5 μm <t ≦ 10 μm, even if the thickness of the transparent conductive layer is larger than the thickness described in this example, the rigidity of the transparent conductive laminate is not affected. Is obtained. Details are omitted here.

The transparent conductive laminate according to the present invention described above and the transparent electrode using the transparent conductive laminate are much thinner than conventional ones and are excellent in flexibility, durability associated therewith, and transparency. It can be applied to clothing, external devices as small terminals, biological information measuring sensors such as heart rate monitors and activity meters, electrocardiographs, electromyographs, electroencephalographs and other testing and diagnostic equipment, electronic skin, medication It can be used in a wide range of applications such as wearable devices such as functional sensors, diaper sensors based on moisture sensing, and power generation elements that are attached to the body surface or inside the body.

Claims (14)

A transparent conductive laminate formed by laminating at least a transparent conductive layer made of graphene on the surface of a transparent substrate,
When the total thickness of the transparent conductive laminate is t, 0.5 μm <t ≦ 10 μm,
The surface resistance value of the transparent conductive layer after the test was conducted 50 times when the transparent conductive laminate was bent 180 degrees along a mandrel rod having a diameter of 2 mm so that the transparent conductive layer side was the mandrel rod side. However, the rate of change is 10% or less compared to the surface resistance value of the transparent conductive layer before the test,
A transparent conductive laminate characterized by the above. The transparent conductive laminate according to claim 1 , wherein the transparent conductive layer has a visible light transmittance of 90% or more. 0.5 μm ≦ t ₁ <10 μm, where t ₁ is the thickness of the transparent substrate,
The transparent conductive laminate according to claim 1 , wherein: In the transparent conductive laminate according to any one of claims 1 to 3 ,
The carrier substrate is adhered to the surface opposite to the surface on which the transparent conductive layer of the transparent substrate is laminated,
A transparent conductive laminate with a carrier, characterized by: Using the transparent conductive laminate according to any one of claims 1 to 3 , or the transparent conductive laminate peeled from the transparent conductive laminate with a carrier according to claim 4 ,
A transparent electrode characterized by. A wearable device using the transparent electrode according to claim 5 . A biological device using the transparent electrode according to claim 5 . A step of attaching a carrier substrate to the surface of the transparent substrate to obtain a transparent substrate with a carrier;
Laminating a transparent conductive layer made of graphene on the transparent substrate side surface of the transparent substrate with carrier to obtain a transparent conductive laminate with carrier;
Peeling the carrier substrate from the transparent conductive laminate with carrier,
A method for producing a transparent conductive laminate comprising:
When the total thickness of the transparent conductive laminate is t, 0.5 μm <t ≦ 10 μm,
When the test of bending the transparent conductive laminate obtained by bending the transparent conductive layer on the mandrel rod having a diameter of 2 mm by 180 degrees along the transparent conductive layer side to the mandrel rod side was performed 50 times, The rate of change of the surface resistance value is 10% or less compared to the surface resistance value of the transparent conductive layer before the test,
A method for producing a transparent conductive laminate, comprising: In the step of obtaining the transparent base material with the carrier, the sticking of the transparent base material is performed by overlapping the carrier base material and the transparent base material and irradiating a charging gun from the transparent base material side,
The manufacturing method of the transparent conductive laminated body of Claim 8 characterized by these. In the step of obtaining the transparent conductive laminate with carrier, the lamination of the transparent conductive layer,
A transparent conductive layer laminated with a transparent conductive layer on the surface of the releasable base material is bonded to the transparent base material-side surface of the transparent base material with the carrier on the transparent conductive layer side. , Being made by removing the releasable substrate,
The manufacturing method of the transparent conductive laminated body of Claim 8 or Claim 9 characterized by these. The releasable substrate is a heat release sheet,
The manufacturing method of the transparent conductive laminated body of Claim 10 characterized by these. The transparent conductive layer is formed by chemical vapor deposition;
The method for producing a transparent conductive laminate according to any one of claims 8 to 11 , wherein: The visible light transmittance of the transparent conductive layer is 90% or more,
The method for producing a transparent conductive laminate according to any one of claims 8 to 12 , wherein: 0.5 μm ≦ t ₁ <10 μm, where t ₁ is the thickness of the transparent substrate,
The method for producing a transparent conductive laminate according to any one of claims 8 to 13 , wherein: