JP2013089334A - Transparent conductor, and production method thereof - Google Patents

Transparent conductor, and production method thereof Download PDF

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JP2013089334A
JP2013089334A JP2011226414A JP2011226414A JP2013089334A JP 2013089334 A JP2013089334 A JP 2013089334A JP 2011226414 A JP2011226414 A JP 2011226414A JP 2011226414 A JP2011226414 A JP 2011226414A JP 2013089334 A JP2013089334 A JP 2013089334A
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transparent
conductive film
transparent conductive
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Motomine Takano
元峰 高野
Yoshinori Iwabuchi
芳典 岩淵
Hideaki Takenouchi
秀章 竹之内
Hideshi Kotsubo
秀史 小坪
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Bridgestone Corp
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Abstract

PROBLEM TO BE SOLVED: To provide a transparent conductor having a transparent conductive film using metal nanofibers, and exhibiting excellent moist-heat durability.SOLUTION: The transparent conductor includes a transparent substrate, and a transparent conductive film formed on the surface thereof and containing metal nanofibers and a binder resin. The metal nanofibers in the transparent conductive film have a concentration distribution in the thickness direction, and the metal nanofiber concentration near the surface of the transparent conductive film on the side opposite from the transparent substrate is lower than that near the interface of the transparent conductive film to the transparent substrate.

Description

本発明は、液晶表示素子、有機発光素子、無機電界発光素子、タッチパネル、電子ペーパー等の電子デバイスに用いることができる透明導電膜を有する透明導電体に関し、特に、金属ナノ繊維を含み、湿熱試験において耐久性に優れた透明導電体に関する。   The present invention relates to a transparent conductor having a transparent conductive film that can be used for an electronic device such as a liquid crystal display element, an organic light emitting element, an inorganic electroluminescent element, a touch panel, and electronic paper, and particularly includes a metal nanofiber and a wet heat test. The present invention relates to a transparent conductor excellent in durability.

透明導電膜は液晶表示素子、有機発光素子、無機電界発光素子、タッチパネル、電子ペーパー等の電子デバイスの透明電極や電磁波シールド材等に用いられている。   The transparent conductive film is used for a transparent electrode of an electronic device such as a liquid crystal display element, an organic light emitting element, an inorganic electroluminescent element, a touch panel, and electronic paper, an electromagnetic shielding material, and the like.

透明導電膜としては、従来から、例えば、錫ドープ酸化インジウム(ITO)やアンチモンドープ酸化錫(ATO)等の金属酸化物が用いられている。一般に、金属酸化物を用いた透明導電膜の作製は、真空蒸着法、スパッタリング法、イオンプレーティング法等の気相製膜法が用いられる。気相製膜法は真空環境が必要なため、大型装置を用い、且つ大量のエネルギーを消費するため、製造コストや環境負荷が大きくなるという問題がある。   Conventionally, metal oxides such as tin-doped indium oxide (ITO) and antimony-doped tin oxide (ATO) have been used as the transparent conductive film. In general, a transparent conductive film using a metal oxide is produced by a vapor deposition method such as a vacuum deposition method, a sputtering method, or an ion plating method. Since the vapor deposition method requires a vacuum environment, a large apparatus is used and a large amount of energy is consumed, so that there is a problem that the manufacturing cost and the environmental load increase.

一方、金属ナノワイヤー又は金属ナノロッドとも称される金属ナノ繊維を用いた透明導電膜の開発も行われている。例えば、特許文献1においては、金属ナノ繊維とポリアニオンを含有する導電性材料で構成された透明導電層を有しており、塗工法により導電膜を形成できる点で有利である。   On the other hand, the development of transparent conductive films using metal nanofibers, also called metal nanowires or metal nanorods, has been carried out. For example, Patent Document 1 is advantageous in that it has a transparent conductive layer made of a conductive material containing metal nanofibers and polyanions, and a conductive film can be formed by a coating method.

特開2010−62059号公報JP 2010-62059 A

しかしながら、金属ナノ繊維を用いた透明導電膜は、高温高湿環境試験において金属ナノ繊維の酸化等により表面抵抗が上昇する場合があり、湿熱耐久性能が十分とはいえなかった。   However, the transparent conductive film using metal nanofibers may have increased surface resistance due to oxidation of the metal nanofibers in a high-temperature and high-humidity environment test, and the wet heat durability performance was not sufficient.

従って、本発明の目的は、金属ナノ繊維を用いた透明導電膜を有する透明導電体であって、湿熱耐久性に優れた透明導電体を提供することにある。   Accordingly, an object of the present invention is to provide a transparent conductor having a transparent conductive film using metal nanofibers and having excellent wet heat durability.

また、本発明の目的は、この透明導電体の製造方法を提供することにある。   Moreover, the objective of this invention is providing the manufacturing method of this transparent conductor.

上記目的は、透明基板と、その表面に形成された、金属ナノ繊維及びバインダ樹脂を含む透明導電膜とを含む透明導電体であって、前記透明導電膜における金属ナノ繊維が、厚さ方向に濃度分布を有しており、且つ前記透明導電膜の前記透明基板と反対側の表面近傍における金属ナノ繊維濃度が、前記透明導電膜の前記透明基板との界面近傍における金属ナノ繊維濃度に比べて低いことを特徴とする透明導電体によって達成される。本発明の透明導電体においては、金属ナノ繊維の透明導電膜表面近傍の濃度を膜表面から離れた透明基板との界面近傍の濃度よりも低くすることで、金属ナノ繊維が透明導電膜に均一に存在する場合に比べて、透明導電膜表面における金属ナノ繊維の酸化の影響を相対的に抑制することができる。そして、透明基板との界面近傍には金属ナノ繊維が透明導電膜表面近傍より高い濃度で存在しているので、透明導電膜として導電性を十分に確保することができる。これにより、湿熱耐久性に優れた透明導電膜を有する透明導電体とすることができる。   The above object is a transparent conductor including a transparent substrate and a transparent conductive film containing metal nanofibers and a binder resin formed on the surface thereof, and the metal nanofibers in the transparent conductive film are arranged in the thickness direction. The metal nanofiber concentration in the vicinity of the surface of the transparent conductive film opposite to the transparent substrate having a concentration distribution is compared with the metal nanofiber concentration in the vicinity of the interface of the transparent conductive film with the transparent substrate. This is achieved by a transparent conductor characterized by a low. In the transparent conductor of the present invention, the concentration of metal nanofibers in the vicinity of the transparent conductive film surface is made lower than the concentration in the vicinity of the interface with the transparent substrate away from the film surface, so that the metal nanofibers are uniform in the transparent conductive film. Compared with the case where it exists in this, the influence of the oxidation of the metal nanofiber in the transparent conductive film surface can be suppressed relatively. And since the metal nanofiber exists in the vicinity of the interface with the transparent substrate at a higher concentration than the vicinity of the transparent conductive film surface, it is possible to sufficiently ensure the conductivity as the transparent conductive film. Thereby, it can be set as the transparent conductor which has a transparent conductive film excellent in wet heat durability.

本発明の透明導電体の好ましい態様は以下の通りである。
(1)前記透明導電膜の表面近傍が、前記透明導電膜の表面から前記透明基板方向に対して透明導電膜の総膜厚の1〜40%の範囲であり、且つ前記透明導電膜の前記透明基板との界面近傍が、前記透明導電膜の前記透明基板との界面から透明導電膜の表面方向に対して前記透明導電膜の総膜厚の1〜40%の範囲である。
(2)前記透明導電膜の表面から前記透明基板方向に対して前記透明導電膜の総膜厚の1/3の範囲における金属ナノ繊維濃度(Cs)の、前記透明導電膜の前記透明基板との界面から前記透明導電膜の表面方向に対して透明導電膜の総膜厚の1/3の範囲における金属ナノ繊維濃度(Cb)に対する濃度比(Cs/Cb)が、0.1〜0.95である。
(3)前記透明導電膜全体の金属ナノ繊維濃度が、1〜90体積%である。これにより、更に十分な導電性を有する透明導電膜とすることができる。
(4)前記金属ナノ繊維が、銀又は銅からなる。
(5)前記バインダ樹脂が、導電性高分子を含む。これにより更に優れた導電性を有する透明導電膜とすることができる。
(6)前記導電性高分子が、下記式(I):
Preferred embodiments of the transparent conductor of the present invention are as follows.
(1) The surface vicinity of the transparent conductive film is in the range of 1 to 40% of the total film thickness of the transparent conductive film with respect to the transparent substrate direction from the surface of the transparent conductive film, and the transparent conductive film The vicinity of the interface with the transparent substrate is in the range of 1 to 40% of the total film thickness of the transparent conductive film with respect to the surface direction of the transparent conductive film from the interface with the transparent substrate of the transparent conductive film.
(2) The transparent substrate of the transparent conductive film having a metal nanofiber concentration (C s ) in a range of 1/3 of the total film thickness of the transparent conductive film from the surface of the transparent conductive film toward the transparent substrate. The concentration ratio (C s / C b ) to the metal nanofiber concentration (C b ) in the range of 1/3 of the total film thickness of the transparent conductive film with respect to the surface direction of the transparent conductive film from the interface with 1 to 0.95.
(3) The metal nanofiber density | concentration of the said transparent conductive film whole is 1-90 volume%. Thereby, it can be set as the transparent conductive film which has further sufficient electroconductivity.
(4) The metal nanofiber is made of silver or copper.
(5) The binder resin contains a conductive polymer. Thereby, it can be set as the transparent conductive film which has the further outstanding electroconductivity.
(6) The conductive polymer has the following formula (I):

Figure 2013089334
Figure 2013089334

(式中、R1及びR2は、それぞれ独立して水素原子若しくは炭素原子数1〜4のアルキル基を表し、又はR1及びR2が相互に結合して任意に置換されていても良い炭素原子数1〜4のアルキレン基を形成し、nは50〜1000の整数を表す)で表される繰り返し単位を含むポリチオフェン誘導体である。上記のポリチオフェン誘導体は導電性が高いので本発明における導電性高分子として好適である。
(7)総膜厚が、5〜3000nmである。
(8)前記透明導電膜が、前記透明基板表面にパターニング処理されてなる透明電極である。本発明の透明導電体における透明導電膜は湿熱耐久性に優れているので透明電極として有用である。
(In the formula, R 1 and R 2 each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, or R 1 and R 2 may be bonded to each other and optionally substituted. A polythiophene derivative containing a repeating unit represented by the formula (1), an alkylene group having 1 to 4 carbon atoms, and n represents an integer of 50 to 1000. Since the above polythiophene derivative has high conductivity, it is suitable as the conductive polymer in the present invention.
(7) The total film thickness is 5 to 3000 nm.
(8) The transparent conductive film is a transparent electrode obtained by patterning the surface of the transparent substrate. Since the transparent conductive film in the transparent conductor of the present invention is excellent in wet heat durability, it is useful as a transparent electrode.

また、上記目的は、透明基板表面に、金属ナノ繊維及びバインダ樹脂を含む透明導電膜用塗工液を塗布して塗工液層を形成し、塗工液層における金属ナノ繊維を透明基板方向に沈降させた後、前記塗工液層を乾燥及び/又は硬化させることを特徴とする透明導電体の製造方法によって達成される。これにより、透明導電膜において、容易に金属ナノ繊維の濃度分布を形成し、透明導電膜と透明基板との界面近傍より透明導電膜表面近傍の金属ナノ繊維濃度が低い透明導電膜を有する透明導電体を得ることができる。   In addition, the above object is to form a coating liquid layer by applying a coating liquid for a transparent conductive film containing metal nanofibers and a binder resin on the surface of the transparent substrate, and the metal nanofibers in the coating liquid layer are directed toward the transparent substrate. And then, the coating liquid layer is dried and / or cured. Thereby, in the transparent conductive film, the metal nanofiber concentration distribution is easily formed, and the transparent conductive film having the transparent conductive film in which the metal nanofiber concentration near the surface of the transparent conductive film is lower than the vicinity of the interface between the transparent conductive film and the transparent substrate. You can get a body.

なお、本発明の製造方法においても、上記の本発明の透明導電体の好ましい態様と同様な態様が好ましい。   In addition, also in the manufacturing method of this invention, the aspect similar to the preferable aspect of said transparent conductor of this invention is preferable.

本発明によれば、透明電極膜において、金属ナノ繊維の透明導電膜表面近傍の濃度を膜表面から離れた透明基板との界面近傍の濃度よりも低くすることで、金属ナノ繊維が透明導電膜に均一に存在する場合に比べて、透明導電膜表面における金属ナノ繊維の酸化の影響を相対的に抑制することができる。そして、透明基板との界面近傍には金属ナノ繊維が透明導電膜表面近傍より高い濃度で存在しているので、透明導電膜として導電性を十分に確保することができる。これにより、湿熱耐久性に優れた透明導電膜とすることができる。従って、本発明の透明導電膜からなる透明電極は湿熱耐久性に優れた透明電極であるといえる。   According to the present invention, in the transparent electrode film, the concentration of metal nanofibers in the vicinity of the transparent conductive film surface is made lower than the concentration in the vicinity of the interface with the transparent substrate away from the film surface, so that the metal nanofibers are transparent conductive film. Compared with the case where it exists uniformly, the influence of the oxidation of the metal nanofiber on the transparent conductive film surface can be relatively suppressed. And since the metal nanofiber exists in the vicinity of the interface with the transparent substrate at a higher concentration than the vicinity of the transparent conductive film surface, it is possible to sufficiently ensure the conductivity as the transparent conductive film. Thereby, it can be set as the transparent conductive film excellent in wet heat durability. Therefore, it can be said that the transparent electrode which consists of a transparent conductive film of this invention is a transparent electrode excellent in wet heat durability.

図1は本発明の透明導電体の一例を示す概略断面図であり、図1(a)は全体図を示し、図1(b)は図1(a)の破線で囲った部分の拡大図を示す。FIG. 1 is a schematic cross-sectional view showing an example of the transparent conductor of the present invention, FIG. 1 (a) shows an overall view, and FIG. 1 (b) is an enlarged view of a portion surrounded by a broken line in FIG. 1 (a). Indicates. 図2は本発明の透明導電体の別の一例を示す概略断面図である。FIG. 2 is a schematic cross-sectional view showing another example of the transparent conductor of the present invention. 図3は本発明の透明導電体の透明導電膜を透明電極とした一例を示す概略断面図である。FIG. 3 is a schematic cross-sectional view showing an example in which the transparent conductive film of the transparent conductor of the present invention is used as a transparent electrode. 図4は本発明の透明導電体の製造方法の一例を示す概略断面図である。FIG. 4 is a schematic cross-sectional view showing an example of a method for producing a transparent conductor according to the present invention.

以下に図面を参照しながら本発明の実施の形態を詳細に説明する。図1は本発明の透明導電体の一例を示す概略断面図である。図1(a)に示すように、本発明の透明導電体20は、透明基板11、及び透明基板11の表面に形成された透明導電膜12を含む。透明導電膜12は、金属ナノ繊維19及びバインダ樹脂を含んだ透明導電膜である。金属ナノ繊維19は導電性が高く、可視光域の波長に対して透過性が高いため、透明導電膜12は透明性が高く、導電性に優れた導電膜である。そして、図示の通り、金属ナノ繊維19は、透明導電膜12において厚さ方向(透明導電膜12表面から透明基板11への方向)に濃度分布を有しており、透明導電膜12の透明基板11と反対側の表面近傍における金属ナノ繊維19の濃度が、透明導電膜12の透明基板11との界面近傍における金属ナノ繊維19の濃度に比べて低くなっている。透明導電膜12はどのように形成されたものでも良い。低コストで層形成できることから、後述の透明導電体の製造方法で詳述するように、金属ナノ繊維及びバインダ樹脂を含む塗工液を透明基板11の表面に塗工することで形成された塗工層であることが好ましい。   Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic sectional view showing an example of the transparent conductor of the present invention. As shown in FIG. 1A, the transparent conductor 20 of the present invention includes a transparent substrate 11 and a transparent conductive film 12 formed on the surface of the transparent substrate 11. The transparent conductive film 12 is a transparent conductive film containing metal nanofibers 19 and a binder resin. Since the metal nanofiber 19 has high conductivity and high transparency with respect to wavelengths in the visible light range, the transparent conductive film 12 is a conductive film having high transparency and excellent conductivity. And as shown in the figure, the metal nanofiber 19 has a concentration distribution in the thickness direction (direction from the surface of the transparent conductive film 12 to the transparent substrate 11) in the transparent conductive film 12, and the transparent substrate of the transparent conductive film 12 The concentration of the metal nanofibers 19 in the vicinity of the surface opposite to 11 is lower than the concentration of the metal nanofibers 19 in the vicinity of the interface between the transparent conductive film 12 and the transparent substrate 11. The transparent conductive film 12 may be formed in any way. Since the layer can be formed at low cost, the coating formed by coating the surface of the transparent substrate 11 with a coating solution containing metal nanofibers and a binder resin as described in detail in the method for producing a transparent conductor described later. A construction layer is preferred.

金属ナノ繊維19の濃度は、バインダ樹脂中に分散して存在している金属ナノ繊維19の体積濃度を意味し、例えば、透明導電膜12の断面を顕微鏡観察し、単位面積当たりの金属ナノ繊維19が占める面積の割合から測定することができる。或いは、透明導電膜を透明導電膜の表面方向に平行に順次切断し、同様に顕微鏡観察や質量測定などを行うことによって測定することができる。   The concentration of the metal nanofibers 19 means the volume concentration of the metal nanofibers 19 dispersed and present in the binder resin. For example, the cross section of the transparent conductive film 12 is observed with a microscope, and the metal nanofibers per unit area are observed. It can measure from the ratio of the area which 19 occupies. Or it can measure by cut | disconnecting a transparent conductive film sequentially in parallel with the surface direction of a transparent conductive film, and performing a microscope observation, mass measurement, etc. similarly.

透明導電膜12において、金属ナノ繊維19の透明導電膜12における表面近傍の濃度を、膜表面から離れた透明基板11との界面近傍における濃度よりも低くすることで、金属ナノ繊維19が透明導電膜12に均一に存在する場合に比べて、透明導電膜12の表面において、金属ナノ繊維19が高温高湿等による酸化を受ける割合を相対的に低減することができる。そして、透明基材11との界面近傍には金属ナノ繊維19が透明導電膜12の表面近傍より高い濃度で存在しているので、透明導電膜12は十分な導電性を確保している。   In the transparent conductive film 12, the concentration of the metal nanofibers 19 in the vicinity of the surface of the transparent conductive film 12 is lower than the concentration in the vicinity of the interface with the transparent substrate 11 away from the film surface, so that the metal nanofibers 19 are transparently conductive. Compared with the case where the film exists uniformly in the film 12, the ratio of the metal nanofibers 19 that are oxidized by high temperature and high humidity on the surface of the transparent conductive film 12 can be relatively reduced. And since the metal nanofiber 19 exists in the vicinity of the interface with the transparent base material 11 at a higher concentration than the vicinity of the surface of the transparent conductive film 12, the transparent conductive film 12 ensures sufficient conductivity.

従って、透明導電膜12は、湿熱耐久性に優れ、十分な導電性を有する透明導電膜であるといえる。   Therefore, it can be said that the transparent conductive film 12 is a transparent conductive film having excellent wet heat durability and sufficient conductivity.

透明導電膜12の表面近傍とは、図1(b)に示すように、透明導電膜12の表面から、透明基板11の方向に対して厚さsの範囲である。厚さsは、一般に、総膜厚tの1%以上50%未満であり、好ましくは、総膜厚tの1〜40%であり、更に好ましくは、総膜厚tの5〜35%(特に、総膜厚tの1/3(約33%))である。   The vicinity of the surface of the transparent conductive film 12 is a range of the thickness s from the surface of the transparent conductive film 12 to the direction of the transparent substrate 11 as shown in FIG. The thickness s is generally 1% or more and less than 50% of the total film thickness t, preferably 1 to 40% of the total film thickness t, and more preferably 5 to 35% ( In particular, it is 1/3 (about 33%) of the total film thickness t.

また、透明導電膜12の透明基板11との界面近傍とは、図1(b)に示すように、透明導電膜12の透明基板11との界面から、透明導電膜12の表面方向に対して厚さbの範囲である。厚さbは、一般に、総膜厚tの1%以上50%未満であり、好ましくは、総膜厚tの1〜40%であり、更に好ましくは、総膜厚tの5〜35%(特に、総膜厚tの1/3(約33%))である。   Further, the vicinity of the interface between the transparent conductive film 12 and the transparent substrate 11 means that the surface of the transparent conductive film 12 is directed from the interface between the transparent conductive film 12 and the transparent substrate 11 as shown in FIG. It is the range of the thickness b. The thickness b is generally 1% or more and less than 50% of the total film thickness t, preferably 1 to 40% of the total film thickness t, and more preferably 5 to 35% ( In particular, it is 1/3 (about 33%) of the total film thickness t.

即ち、金属ナノ繊維19の透明導電膜12の表面近傍の濃度とは、図1(b)において、透明導電膜12の表面から厚さsの範囲を顕微鏡観察し、単位面積当たりの金属ナノ繊維19が占める面積の割合から求めた体積濃度である。また、透明導電膜12の透明基板11との界面近傍の金属ナノ繊維19の濃度とは、図1(b)において、透明導電膜12の透明基板11との界面から厚さbの範囲を顕微鏡観察し、単位面積当たりの金属ナノ繊維19が占める面積の割合から求めた体積濃度である。   That is, the concentration of the metal nanofibers 19 in the vicinity of the surface of the transparent conductive film 12 in FIG. 1 (b) is obtained by observing the range of the thickness s from the surface of the transparent conductive film 12 with a microscope. 19 is a volume concentration obtained from the proportion of the area occupied by 19. Moreover, the density | concentration of the metal nanofiber 19 of the transparent conductive film 12 vicinity of the interface with the transparent substrate 11 is a microscope in the range of thickness b from the interface with the transparent substrate 11 of the transparent conductive film 12 in FIG.1 (b). It is the volume concentration obtained by observing and calculating the ratio of the area occupied by the metal nanofibers 19 per unit area.

更に、本発明においては、透明導電膜12の表面近傍における金属ナノ繊維19の濃度(Cs)の、透明導電膜12の透明基板11との界面近傍における金属ナノ繊維19の濃度(Cb)に対する濃度比(Cs/Cb)は、Cs/Cb<1の関係を示す。濃度比(Cs/Cb)は、0.1〜0.95が好ましく、0.3〜0.9が更に好ましい。これにより、更に湿熱耐久性に優れた透明導電膜12とすることができる。なお、この規定において、濃度(Cs)は、透明基板12の表面から透明基板11方向に対して透明導電膜12の総膜厚tの1/3の範囲における金属ナノ繊維濃度とし、濃度(Cb)は、透明導電膜12の透明基板11との界面から透明導電膜12の表面方向に対して透明導電膜12の総膜厚tの1/3の範囲における金属ナノ繊維濃度とする。 Further, in the present invention, the concentration of the metal nano-fibers 19 concentration of metallic nano fibers 19 near the surface of the transparent conductive film 12 of the (C s), in the vicinity of the interface between the transparent substrate 11 of the transparent conductive film 12 (C b) The concentration ratio (C s / C b ) with respect to C shows a relationship of C s / C b <1. The concentration ratio (C s / C b ) is preferably 0.1 to 0.95, and more preferably 0.3 to 0.9. Thereby, it can be set as the transparent conductive film 12 which was further excellent in wet heat durability. In this rule, the concentration (C s ) is defined as the metal nanofiber concentration in the range of 1/3 of the total film thickness t of the transparent conductive film 12 from the surface of the transparent substrate 12 toward the transparent substrate 11. C b ) is a metal nanofiber concentration in the range of 1/3 of the total film thickness t of the transparent conductive film 12 from the interface of the transparent conductive film 12 with the transparent substrate 11 to the surface direction of the transparent conductive film 12.

また、本発明において、透明導電膜12全体における金属ナノ繊維19の濃度は、1〜90体積%が好ましく、更に1〜70体積%が好ましく、特に1〜50体積%が好ましい。これにより、更に十分な導電性を有する透明導電膜12とすることができる。   In the present invention, the concentration of the metal nanofibers 19 in the entire transparent conductive film 12 is preferably 1 to 90% by volume, more preferably 1 to 70% by volume, and particularly preferably 1 to 50% by volume. Thereby, it can be set as the transparent conductive film 12 which has further sufficient electroconductivity.

透明導電膜における金属ナノ繊維の濃度分布は、透明導電膜の表面近傍の濃度が、透明基板との界面近傍の濃度に比べて低くなっていれば良く、その間の濃度変化については特に制限は無い。図1に示したように、透明導電膜12の表面から透明基板11との界面に向かって金属ナノ繊維19の濃度が連続的に高くなるような濃度分布でも良く、金属ナノ繊維濃度が断続的に高くなるような濃度分布でも良い。   The concentration distribution of the metal nanofibers in the transparent conductive film is not particularly limited as long as the concentration in the vicinity of the surface of the transparent conductive film is lower than the concentration in the vicinity of the interface with the transparent substrate. . As shown in FIG. 1, the concentration distribution may be such that the concentration of the metal nanofibers 19 continuously increases from the surface of the transparent conductive film 12 toward the interface with the transparent substrate 11, and the metal nanofiber concentration is intermittent. The concentration distribution may be higher.

図2は、本発明の透明導電体の別の一例を示す概略断面図であり、透明導電膜の金属ナノ繊維濃度が、透明導電膜の表面から透明基板との界面に向かって断続的に高くなっている例を示している。図示の通り、図2の透明導電体30は、透明基板21及び透明導電膜22からなり、透明導電膜22は、透明基板21の表面に形成された第1導電層22Aとその表面に形成された第2導電層22Bから構成されている。そして、第2導電層22Bにおける金属ナノ繊維29の濃度が、第1導電層22Aにおける金属ナノ繊維29の濃度より低くなっている。透明導電膜22を構成する導電層は何層あっても良い。透明導電膜22が、3層以上の導電層から構成される場合、透明導電膜22の最表層の導電層の金属ナノ繊維29の濃度が透明基板21との界面に形成された導電層の金属ナノ繊維29の濃度より低くなっていれば良い。   FIG. 2 is a schematic cross-sectional view showing another example of the transparent conductor of the present invention, in which the metal nanofiber concentration of the transparent conductive film is intermittently high from the surface of the transparent conductive film toward the interface with the transparent substrate. An example is shown. 2, the transparent conductor 30 of FIG. 2 includes a transparent substrate 21 and a transparent conductive film 22, and the transparent conductive film 22 is formed on the first conductive layer 22A formed on the surface of the transparent substrate 21 and the surface thereof. The second conductive layer 22B. The concentration of the metal nanofibers 29 in the second conductive layer 22B is lower than the concentration of the metal nanofibers 29 in the first conductive layer 22A. There may be any number of conductive layers constituting the transparent conductive film 22. When the transparent conductive film 22 is composed of three or more conductive layers, the concentration of the metal nanofibers 29 in the outermost conductive layer of the transparent conductive film 22 is the metal of the conductive layer formed at the interface with the transparent substrate 21. It only needs to be lower than the concentration of the nanofibers 29.

透明導電膜の総膜厚は特に制限はなく、用途に応じて適宜設定できる。薄過ぎると本発明の効果が発揮され難い場合があるので、好ましくは5〜3000nm、更に好ましくは5〜1000nm、特に好ましくは5〜500nmである。   There is no restriction | limiting in particular in the total film thickness of a transparent conductive film, According to a use, it can set suitably. If it is too thin, the effect of the present invention may not be exerted, so the thickness is preferably 5 to 3000 nm, more preferably 5 to 1000 nm, and particularly preferably 5 to 500 nm.

なお、本発明の透明導電体における透明導電膜は、導電性を損なわない範囲で、その表面を保護するためにオーバーコート層が形成されていても良い。オーバーコート層は、上述のバインダ樹脂等を用いて形成することができる。本発明の透明導電体における透明導電膜は、湿熱耐久性に優れているので、従来のものより、オーバーコート層が薄層であっても同様な保護効果を得ることができる。   In addition, the transparent conductive film in the transparent conductor of the present invention may have an overcoat layer formed in order to protect the surface within a range that does not impair the conductivity. The overcoat layer can be formed using the above-described binder resin or the like. Since the transparent conductive film in the transparent conductor of the present invention is excellent in wet heat durability, the same protective effect can be obtained even if the overcoat layer is a thin layer as compared with the conventional one.

本発明の透明導電体においては、透明導電膜を透明電極とすることもできる。図3は、本発明の透明導電体における透明導電膜を透明電極とした一例を示す概略断面図である。図示の通り、本発明の透明導電体40は、透明基板31及びその表面に透明導電膜がパターニング処理された透明電極35を含む。透明電極35は、上述の透明導電膜と同様な構成である。即ち、透明電極35は金属ナノ繊維39及びバインダ樹脂を含み、金属ナノ繊維39は、透明電極35の厚さ方向(透明電極35の表面から透明基板31への方向)に濃度分布を有しており、透明電極35の表面近傍の金属ナノ繊維39の濃度が、透明電極35の透明基板31との界面近傍の金属ナノ繊維39の濃度に比べて低くなっている。パターニングは、どのような方法でされていても良い。例えば、後述する透明導電体の製造方法における透明導電膜用塗工液をインクとして用い、印刷法で透明基板31に電極パターンを形成する方法、透明導電膜を形成した後、フォトリソグラフィ法やレーザ加工法などにより電極パターンを形成する方法、フォトレジストで形成した電極パターンのネガパターンを含む透明基板上に、透明電極膜を形成し、リフトオフ法を用いて、電極パターンを形成する方法等が挙げられる。本発明の透明導電体における透明電極は、上述の透明導電膜の説明と同様に湿熱耐久性に優れた透明電極である。このような透明電極を有する本発明の透明導電体は、液晶表示素子、有機発光素子、無機電界発光素子、タッチパネル、電子ペーパー等の電子デバイスに好適に用いることができる。   In the transparent conductor of the present invention, the transparent conductive film can be a transparent electrode. FIG. 3 is a schematic cross-sectional view showing an example in which the transparent conductive film in the transparent conductor of the present invention is a transparent electrode. As illustrated, the transparent conductor 40 of the present invention includes a transparent substrate 31 and a transparent electrode 35 having a transparent conductive film patterned on the surface thereof. The transparent electrode 35 has the same configuration as the above-described transparent conductive film. That is, the transparent electrode 35 includes metal nanofibers 39 and a binder resin, and the metal nanofibers 39 have a concentration distribution in the thickness direction of the transparent electrode 35 (the direction from the surface of the transparent electrode 35 to the transparent substrate 31). In addition, the concentration of the metal nanofibers 39 near the surface of the transparent electrode 35 is lower than the concentration of the metal nanofibers 39 near the interface of the transparent electrode 35 with the transparent substrate 31. Patterning may be performed by any method. For example, a transparent conductive film coating liquid in a transparent conductor manufacturing method described later is used as an ink, an electrode pattern is formed on the transparent substrate 31 by a printing method, a transparent conductive film is formed, a photolithography method or a laser Examples include a method of forming an electrode pattern by a processing method, a method of forming a transparent electrode film on a transparent substrate including a negative pattern of an electrode pattern formed of a photoresist, and forming an electrode pattern using a lift-off method. It is done. The transparent electrode in the transparent conductor of this invention is a transparent electrode excellent in wet heat durability similarly to the description of the above-mentioned transparent conductive film. The transparent conductor of this invention which has such a transparent electrode can be used suitably for electronic devices, such as a liquid crystal display element, an organic light emitting element, an inorganic electroluminescent element, a touch panel, and electronic paper.

以下に、本発明の透明導電体に関する材料について説明する。   Below, the material regarding the transparent conductor of this invention is demonstrated.

[金属ナノ繊維]
金属ナノ繊維は、金属ナノワイヤー又は金属ナノロッドとも称されるサブミクロンレベルの微細な金属繊維である。金属ナノ繊維の短軸の長さは500nm未満が好ましく、200nm未満がより好ましく、100nm未満が更に好ましい。アスペクト比(長軸の長さ/短軸の長さ)は、一般に、10〜100000の範囲であり、50〜100000が好ましく、100〜100000が更に好ましい。
[Metal nanofibers]
Metal nanofibers are submicron-level fine metal fibers, also called metal nanowires or metal nanorods. The length of the short axis of the metal nanofiber is preferably less than 500 nm, more preferably less than 200 nm, and still more preferably less than 100 nm. The aspect ratio (major axis length / minor axis length) is generally in the range of 10 to 100,000, preferably 50 to 100,000, and more preferably 100 to 100,000.

金属ナノ繊維を構成する金属としては、金属元素、金属合金、金属酸化物等の金属化合物を含む。金属としては銀、金、銅、ニッケル、金めっきの銀が好ましく、特に銀が好ましい。   As a metal which comprises metal nanofiber, metal compounds, such as a metal element, a metal alloy, and a metal oxide, are included. As the metal, silver of silver, gold, copper, nickel and gold plating is preferable, and silver is particularly preferable.

金属ナノ繊維は、従来公知の技術で調製できる。例えば、銀ナノ繊維は、エチレングリコール等のポリオール及びポリ(ビニルピロリドン)の存在下で硝酸銀等の銀塩の液相還元により合成できる。   Metal nanofibers can be prepared by a conventionally known technique. For example, silver nanofibers can be synthesized by liquid phase reduction of silver salts such as silver nitrate in the presence of polyols such as ethylene glycol and poly (vinyl pyrrolidone).

[バインダ樹脂]
バインダ樹脂としては、透明(「可視光に対して透明」を意味する)であり、透明導電膜の形状を維持できるものであればどのようなものでも良い。例えば熱可塑性樹脂組成物、紫外線硬化性樹脂組成物又は熱硬化性樹脂組成物を使用できる。熱可塑性樹脂組成物、紫外線硬化性樹脂又は熱硬化性樹脂としては、ポリビニルアルコール樹脂、ポリ塩化ビニル樹脂、アクリル樹脂、ポリエステル樹脂、フェノール樹脂、レゾルシノール樹脂、尿素樹脂、メラミン樹脂、エポキシ樹脂、ウレタン樹脂、フラン樹脂、シリコン樹脂などを挙げることができ、紫外線硬化性樹脂は光重合開始剤等とともに紫外線硬化性樹脂組成物とし、熱硬化性樹脂は熱重合開始剤等とともに熱硬化性樹脂組成物として使用することができる。
[Binder resin]
Any binder resin may be used as long as it is transparent (meaning “transparent to visible light”) and can maintain the shape of the transparent conductive film. For example, a thermoplastic resin composition, an ultraviolet curable resin composition, or a thermosetting resin composition can be used. Thermoplastic resin composition, UV curable resin or thermosetting resin includes polyvinyl alcohol resin, polyvinyl chloride resin, acrylic resin, polyester resin, phenol resin, resorcinol resin, urea resin, melamine resin, epoxy resin, urethane resin , Furan resin, silicon resin, and the like. The ultraviolet curable resin is an ultraviolet curable resin composition together with a photopolymerization initiator and the like, and the thermosetting resin is an thermosetting resin composition together with a thermal polymerization initiator and the like. Can be used.

紫外線硬化性樹脂(モノマー、オリゴマー)としては、例えば、(メタ)アクリレートモノマー類、ポリオール化合物と有機ポリイソシアネートと水酸基含有(メタ)アクリレートの反応物であるポリウレタン(メタ)アクリレート、ビスフェノール型エポキシ樹脂と(メタ)アクリル酸の反応物であるビスフェノール型エポキシ(メタ)アクリレート等の(メタ)アクリレートオリゴマー類等を挙げることができる。これら化合物は1種又は2種以上、混合して使用することができる。特に、ペンタエリスリトールトリ(メタ)アクリレート、ペンタエリスリトールペンタ(メタ)アクリレート、ジペンタエリスリトールヘキサ(メタ)アクリレート、トリメチロールプロパントリ(メタ)アクリレート等の硬質の多官能モノマーを主に使用することが好ましい。   Examples of the ultraviolet curable resin (monomer, oligomer) include (meth) acrylate monomers, polyurethane (meth) acrylate, which is a reaction product of a polyol compound, an organic polyisocyanate, and a hydroxyl group-containing (meth) acrylate, and a bisphenol type epoxy resin. (Meth) acrylate oligomers such as bisphenol-type epoxy (meth) acrylate, which is a reaction product of (meth) acrylic acid, can be mentioned. These compounds can be used alone or in combination. In particular, it is preferable to mainly use hard polyfunctional monomers such as pentaerythritol tri (meth) acrylate, pentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate and the like. .

これらの紫外線硬化性樹脂を、熱重合開始剤とともに用いて熱硬化性樹脂として使用してもよい。   These ultraviolet curable resins may be used as a thermosetting resin together with a thermal polymerization initiator.

紫外線硬化性樹脂組成物の光重合開始剤として、紫外線硬化性樹脂の性質に適した任意の化合物を使用することができる。例えば、1−ヒドロキシシクロヘキシルフェニルケトン等のアセトフェノン系、ベンジルジメチルケタール等のベンゾイン系、ベンゾフェノン等のベンゾフェノン系、チオキサントン系等が使用できる。特に、特に1−ヒドロキシシクロヘキシルフェニルケトン(BASFジャパン社製、イルガキュア184)が好ましい。光重合開始剤の量は、樹脂組成物に対して一般に0.1〜10質量%、好ましくは0.1〜5質量%である。   As the photopolymerization initiator for the ultraviolet curable resin composition, any compound suitable for the properties of the ultraviolet curable resin can be used. For example, acetophenone type such as 1-hydroxycyclohexyl phenyl ketone, benzoin type such as benzyldimethyl ketal, benzophenone type such as benzophenone, thioxanthone type, and the like can be used. In particular, 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF Japan, Irgacure 184) is preferable. Generally the quantity of a photoinitiator is 0.1-10 mass% with respect to a resin composition, Preferably it is 0.1-5 mass%.

熱硬化性樹脂組成物の熱重合開始剤として、加熱により重合を開始させる官能基を含む化合物である有機過酸化物やカチオン重合開始剤が挙げられ、中でも有機過酸化物が好ましい。熱重合開始剤は、1種又は2種以上の混合で使用することができる。熱重合開始剤の量は、樹脂組成物に対して、一般に0.01〜10質量%、好ましくは0.1〜5質量%である。   Examples of the thermal polymerization initiator of the thermosetting resin composition include organic peroxides and cationic polymerization initiators that are compounds containing a functional group that initiates polymerization by heating, and organic peroxides are preferred. A thermal-polymerization initiator can be used 1 type or in mixture of 2 or more types. Generally the quantity of a thermal-polymerization initiator is 0.01-10 mass% with respect to a resin composition, Preferably it is 0.1-5 mass%.

樹脂組成物は、必要に応じて、紫外線吸収剤、赤外線吸収剤、老化防止剤、塗料加工助剤、着色剤等を少量含んでいても良い。その量は、樹脂組成物に対して一般に0.1〜10質量%、好ましくは0.1〜5質量%である。   The resin composition may contain a small amount of an ultraviolet absorber, an infrared absorber, an anti-aging agent, a paint processing aid, a colorant, and the like, if necessary. The amount thereof is generally 0.1 to 10% by mass, preferably 0.1 to 5% by mass, based on the resin composition.

[導電性高分子]
また、本発明において、バインダ樹脂は、導電性高分子を含むことが好ましい。これにより、更に導電性に優れた透明導電膜とすることができる。なお、バインダ樹脂として、導電性高分子のみを用いても良く、上述の他の樹脂組成物とともに導電性高分子を用いても良い。
[Conductive polymer]
In the present invention, the binder resin preferably contains a conductive polymer. Thereby, it can be set as the transparent conductive film which was further excellent in electroconductivity. Note that only a conductive polymer may be used as the binder resin, or a conductive polymer may be used together with the other resin composition described above.

導電性高分子は、一般に共役型の二重結合を基本骨格に有する有機高分子で、具体的にはポリチオフェン、ポリピロール、ポリアニリン、ポリアセチレン、ポリパラフェニレン、ポリフラン、ポリフルオレン、ポリフェニレンビニレン、これらの誘導体、及びこれらを構成する単量体の共重合物から選ばれた導電性高分子のいずれか1種又は2種以上の混合物が好ましく挙げられる。中でも、水又はその他の溶媒に対して可溶性、又は分散性を有し、高い導電性及び透明性を示す、ポリチオフェン誘導体が好ましい。特に、下記式(I):   The conductive polymer is generally an organic polymer having a conjugated double bond as a basic skeleton, specifically, polythiophene, polypyrrole, polyaniline, polyacetylene, polyparaphenylene, polyfuran, polyfluorene, polyphenylene vinylene, and derivatives thereof. And any one or a mixture of two or more conductive polymers selected from the copolymer of monomers constituting them are preferred. Among these, polythiophene derivatives that are soluble or dispersible in water or other solvents and exhibit high conductivity and transparency are preferable. In particular, the following formula (I):

Figure 2013089334
Figure 2013089334

(式中、R1及びR2は、それぞれ独立して水素原子若しくは炭素原子数1〜4のアルキル基を表し、又はR1及びR2が相互に結合して任意に置換されていても良い炭素原子数1〜4のアルキレン基を形成し、nは50〜1000の整数を表す)で表される繰り返し単位を含むポリチオフェン誘導体が好ましい。 (In the formula, R 1 and R 2 each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, or R 1 and R 2 may be bonded to each other and optionally substituted. A polythiophene derivative containing a repeating unit represented by (forms an alkylene group having 1 to 4 carbon atoms and n represents an integer of 50 to 1000) is preferable.

式(I)において、R1及びR2が相互に結合して形成される、置換されていても良い炭素原子数1〜4のアルキレン基としては、具体的にはアルキル基で置換されたメチレン基、任意に炭素原子数1〜12のアルキル基又はフェニル基で置換されたエチレン−1,2基、プロピレン−1,3基、ブテン−1,4基を形成する基等が挙げられる。 In the formula (I), an optionally substituted alkylene group having 1 to 4 carbon atoms formed by bonding R 1 and R 2 to each other is specifically methylene substituted with an alkyl group. And groups that form ethylene-1,2 groups, propylene-1,3 groups, butene-1,4 groups optionally substituted with alkyl groups having 1 to 12 carbon atoms or phenyl groups.

式(I)におけるR1及びR2として、好ましくはメチル基又はエチル基であるか、R1及びR2が相互に結合して形成するメチレン基、エチレン−1,2基又はプロピレン−1,3基である。特に好ましいポリチオフェン誘導体としては、下記式(II): As R1 and R2 in formula (I), or preferably a methyl group or an ethyl group, methylene group R 1 and R 2 form by combining to each other, an ethylene-1,2 radical or propylene-1,3 radical It is. Particularly preferred polythiophene derivatives include the following formula (II):

Figure 2013089334
Figure 2013089334

(式中、pは50〜1000の整数を表す)で示される繰り返し単位、即ち、ポリ(3,4−エチレンジオキシチオフェン)単位を有するポリチオフェン誘導体である。 (Wherein p represents an integer of 50 to 1000), that is, a polythiophene derivative having a poly (3,4-ethylenedioxythiophene) unit.

導電性高分子は、更にドーパント(電子供与剤)を含むことが好ましい。ドーパントとしては、例えば、ポリスチレンスルホン酸、ポリアクリル酸、ポリメタクリル酸、ポリマレイン酸、ポリビニルスルホン酸が好ましく挙げられる。特に、ポリスチレンスルホン酸が好ましい。これらにより導電性高分子の導電性を向上することができ、熱線反射層14の近赤外線遮蔽効果を高めることができる。ドーパントの数平均分子量Mnは、好ましくは1,000〜2,000,000であり、特に好ましくは2,000〜500,000である。   The conductive polymer preferably further contains a dopant (electron donor). Preferred examples of the dopant include polystyrene sulfonic acid, polyacrylic acid, polymethacrylic acid, polymaleic acid, and polyvinyl sulfonic acid. In particular, polystyrene sulfonic acid is preferable. By these, the electroconductivity of a conductive polymer can be improved and the near-infrared shielding effect of the heat ray reflective layer 14 can be improved. The number average molecular weight Mn of the dopant is preferably 1,000 to 2,000,000, particularly preferably 2,000 to 500,000.

ドーパントの含有量は導電性高分子100質量部に対して、通常20〜2000質量部であり、好ましくは、40〜200質量部である。例えば、式(II)のポリチオフェン誘導体を導電性高分子とし、ポリスチレンスルホン酸をドーパントとして使用する場合はポリチオフェン100質量部に対して、ポリスチレンスルホン酸100〜200質量部が好ましく、特に120〜180質量部が好ましい。   Content of a dopant is 20-2000 mass parts normally with respect to 100 mass parts of conductive polymers, Preferably, it is 40-200 mass parts. For example, when the polythiophene derivative of the formula (II) is a conductive polymer and polystyrene sulfonic acid is used as a dopant, 100 to 200 parts by mass of polystyrene sulfonic acid is preferable with respect to 100 parts by mass of polythiophene, and particularly 120 to 180 parts by mass. Part is preferred.

[溶媒]
金属ナノ繊維とバインダ樹脂とを分散又は溶解させる溶媒は、バインダ樹脂の種類によって適宜好適なものを選択することができる。例えば、水;メタノール、エタノール、プロパノール等のアルコール類;アセトフェノン、メチルエチルケトン等のケトン類;四塩化炭素及びフッ化炭化水素等のハロゲン化炭化水素;酢酸エチル、酢酸ブチル等のエステル類;テトラヒドロフラン、ジオキサン、ジエチルエーテル等のエーテル類;N,N−ジメチルアセトアミド、N,N−ジメチルホルムアミド、N−メチルピロリドン等のアミド類、シクロヘキサン、ベンゼン、トルエン等の炭化水素等が挙げられる。特にバインダ樹脂に導電性高分子を用いる場合は、水、アルコール類が好ましい。
[solvent]
As the solvent for dispersing or dissolving the metal nanofibers and the binder resin, a suitable solvent can be appropriately selected depending on the kind of the binder resin. For example, water; alcohols such as methanol, ethanol and propanol; ketones such as acetophenone and methyl ethyl ketone; halogenated hydrocarbons such as carbon tetrachloride and fluorinated hydrocarbons; esters such as ethyl acetate and butyl acetate; tetrahydrofuran and dioxane And ethers such as diethyl ether; amides such as N, N-dimethylacetamide, N, N-dimethylformamide and N-methylpyrrolidone, and hydrocarbons such as cyclohexane, benzene and toluene. In particular, when a conductive polymer is used for the binder resin, water and alcohols are preferable.

[透明基板]
本発明における透明基板は、透明(「可視光に対して透明」を意味する。)な基板であれば特に制限は無く、透明プラスチックフィルム、ガラス板、及び透明プラスチック基板等が挙げられる。透明プラスチックフィルムとしては、例えば、ポリエチレンテレフタレート(PET)フィルム、ポリエチレンナフタレート(PEN)フィルム、ポリエチレンブチレートフィルム、トリアセチルセルロース(TAC)フィルム、ポリメチルメタクリレート(PMMA)フィルム、ポリカーボネート(PC)フィルム等が挙げられる。ガラス板としては、グリーンガラス、珪酸塩ガラス、無機ガラス板、無着色透明ガラス板等が挙げられ、プラスチック板としては、ポリエチレンテレフタレート(PET)、ポリエチレンナフタレート(PEN)、ポリエチレンブチレート、ポリメチルメタクリレート(PMMA)、ポリカーボネート等のプラスチック製の基板が挙げられる。透明プラスチックフィルムの場合は、特に加工時の熱、溶剤、折り曲げ等の負荷に対する耐性が高く、透明性が高い点で、PETフィルムが好ましい。
[Transparent substrate]
The transparent substrate in the present invention is not particularly limited as long as it is a transparent substrate (meaning “transparent to visible light”), and examples thereof include a transparent plastic film, a glass plate, and a transparent plastic substrate. Examples of the transparent plastic film include a polyethylene terephthalate (PET) film, a polyethylene naphthalate (PEN) film, a polyethylene butyrate film, a triacetyl cellulose (TAC) film, a polymethyl methacrylate (PMMA) film, and a polycarbonate (PC) film. Is mentioned. Examples of the glass plate include green glass, silicate glass, inorganic glass plate, and non-colored transparent glass plate. Examples of the plastic plate include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene butyrate, and polymethyl. Examples thereof include plastic substrates such as methacrylate (PMMA) and polycarbonate. In the case of a transparent plastic film, a PET film is particularly preferred because of its high resistance to loads such as heat during processing, solvent and bending, and high transparency.

なお、透明プラスチックフィルム表面には、透明導電膜が形成し易くするために、予めコロナ処理、プラズマ処理、火炎処理、プライマー層コート処理などの接着処理を施してもよく、共重合ポリエステル樹脂やポリウレタン樹脂等の熱硬化性樹脂等の易接着層を設けてもよい。   In addition, in order to make it easy to form a transparent conductive film on the surface of the transparent plastic film, adhesion treatment such as corona treatment, plasma treatment, flame treatment, primer layer coating treatment, etc. may be performed in advance, such as a copolyester resin or polyurethane. An easy adhesion layer such as a thermosetting resin such as a resin may be provided.

[透明導電体の製造方法]
本発明の透明導電体の製造方法としては、どのような方法を用いても良いが、低コストで製造可能な塗工法を用いて行うことが好ましい。図4は、本発明の透明導電体の製造方法の一例を示す概略断面図である。図4においては、図1に示したような、透明導電膜の表面から透明基板との界面に向かって金属ナノ繊維の濃度が連続的に高くなるような濃度分布を有する透明導電膜を含む透明導電体の製造方法について説明する。
[Method for producing transparent conductor]
As a method for producing the transparent conductor of the present invention, any method may be used, but it is preferable to use a coating method that can be produced at low cost. FIG. 4 is a schematic cross-sectional view showing an example of a method for producing a transparent conductor according to the present invention. In FIG. 4, the transparent including the transparent conductive film having a concentration distribution such that the concentration of the metal nanofibers continuously increases from the surface of the transparent conductive film toward the interface with the transparent substrate as shown in FIG. A method for manufacturing the conductor will be described.

まず、上述の金属ナノ繊維及びバインダ樹脂を溶媒に分散させた透明導電膜用塗工液を、透明基板11の表面に塗工し、塗工液層12Lを形成する(図4(a))。塗工は、バーコーター法、ロールコーター法、カーテンフロー法、スプレー法など適当な方法を用いることができる。また、図3に示したような透明導電膜を透明電極とする場合は、印刷法を用いてパターニングすることもできる。この場合は、スクリーン印刷、グラビア印刷、オフセット印刷、グラビアオフセット印刷、インクジェット印刷等を用いることができる。塗工した段階では、金属ナノ繊維19は塗工液層12L中に均一に分散している。   First, a coating liquid for transparent conductive film in which the above-described metal nanofibers and binder resin are dispersed in a solvent is applied to the surface of the transparent substrate 11 to form a coating liquid layer 12L (FIG. 4A). . For coating, an appropriate method such as a bar coater method, a roll coater method, a curtain flow method, or a spray method can be used. Moreover, when using a transparent conductive film as shown in FIG. 3 as a transparent electrode, it can also pattern using a printing method. In this case, screen printing, gravure printing, offset printing, gravure offset printing, inkjet printing, or the like can be used. At the stage of coating, the metal nanofibers 19 are uniformly dispersed in the coating liquid layer 12L.

次いで、この塗工液層12Lが形成された透明基板11を、透明基板11が下方になるように静置し、金属ナノ繊維19を透明基板11の方向へ沈降させる(図4(b))。静置時間は特に制限は無く、塗工液の比重、粘度との関係で塗工液層12の表面近傍における金属ナノ繊維19の濃度が低下し、塗工液層12Lと透明基板11との界面近傍の金属ナノ繊維19の濃度が上昇する程度の静置時間を設定することができる。静置時間は5分〜10時間が好ましく、10分〜5時間が更に好ましく、10分〜1時間が特に好ましい。   Next, the transparent substrate 11 on which the coating liquid layer 12L is formed is allowed to stand so that the transparent substrate 11 faces downward, and the metal nanofibers 19 are allowed to settle in the direction of the transparent substrate 11 (FIG. 4B). . The standing time is not particularly limited, and the concentration of the metal nanofibers 19 in the vicinity of the surface of the coating liquid layer 12 decreases due to the specific gravity and viscosity of the coating liquid, and the coating liquid layer 12L and the transparent substrate 11 It is possible to set the standing time such that the concentration of the metal nanofiber 19 in the vicinity of the interface increases. The standing time is preferably 5 minutes to 10 hours, more preferably 10 minutes to 5 hours, and particularly preferably 10 minutes to 1 hour.

その後、塗工液層12Lを乾燥及び/又は硬化処理し、透明導電膜12を形成する(図4(c))。乾燥及び/又は硬化処理は40〜150℃、好ましくは60〜130℃で加熱することで行うことができる。加熱時間は、一概には決められないが、数分〜数時間程度である。   Thereafter, the coating liquid layer 12L is dried and / or cured to form the transparent conductive film 12 (FIG. 4C). The drying and / or curing treatment can be performed by heating at 40 to 150 ° C, preferably 60 to 130 ° C. The heating time is not generally determined, but is about several minutes to several hours.

バインダ樹脂として紫外線硬化性樹脂を用いる場合、紫外線硬化の光源として紫外〜可視領域に発光する多くのものが採用でき、例えば超高圧、高圧、低圧水銀灯、ケミカルランプ、キセノンランプ、ハロゲンランプ、マーキュリーハロゲンランプ、カーボンアーク灯、白熱灯、レーザ光等を挙げることができる。照射時間は、ランプの種類、光源の強さによって一概には決められないが、数秒〜数分程度である。また、硬化促進のために、予め積層体を40〜120℃に加熱し、これに紫外線を照射してもよい。   When an ultraviolet curable resin is used as the binder resin, many ultraviolet light sources that emit light in the ultraviolet to visible region can be used. For example, ultra-high pressure, high pressure, low-pressure mercury lamp, chemical lamp, xenon lamp, halogen lamp, mercury lamp A lamp, a carbon arc lamp, an incandescent lamp, a laser beam, etc. can be mentioned. The irradiation time cannot be determined unconditionally depending on the type of lamp and the intensity of the light source, but is about several seconds to several minutes. Moreover, in order to accelerate curing, the laminate may be preheated to 40 to 120 ° C. and irradiated with ultraviolet rays.

なお、図2に示したような、透明導電膜の表面から透明基板との界面に向かって金属ナノ繊維の濃度が断続的に高くなるような濃度分布を有する透明導電膜については、例えば、金属ナノ繊維濃度の異なる塗工液を2種以上用いて、塗工液を塗工する工程、及び塗工液層を乾燥及び/又は硬化する工程を繰り返すことで製造することができる。   As for the transparent conductive film having a concentration distribution such that the concentration of the metal nanofibers intermittently increases from the surface of the transparent conductive film to the interface with the transparent substrate as shown in FIG. It can be manufactured by using two or more kinds of coating liquids having different nanofiber concentrations and repeating the step of coating the coating liquid and the step of drying and / or curing the coating liquid layer.

以下に、実施例を示し、本発明についてさらに詳述する。   Hereinafter, the present invention will be described in more detail with reference to examples.

1.透明導電膜の形成
[実施例1]
PETフィルム(厚さ100μm)の表面に、銀ナノ繊維分散液(銀ナノ繊維(直径50nm、長さ50μm)、バインダ樹脂(ポリビニルアルコール)、溶媒(水)、固形分2質量%(銀ナノ繊維:バインダ樹脂(質量比)=4:1))をワイヤーバーコーターにより塗工した。塗工後室温にて10分間静置し、銀ナノ繊維を沈降させた後、乾燥炉中で120℃、10分間乾燥して、膜厚25nmの透明導電膜を形成した。表面抵抗率が200±20Ω/□になるように膜厚を調製した。透明導電膜の顕微鏡写真から、透明導電膜の表面近傍(表面から総膜厚の1/3の範囲)の金属ナノ繊維濃度(Cs)と透明導電膜の透明基板との界面近傍(界面から総膜厚の1/3の範囲)の金属ナノ繊維濃度(Cb)との濃度比(Cs/Cb)は、0.89であった。
1. Formation of transparent conductive film [Example 1]
On the surface of a PET film (thickness 100 μm), a silver nanofiber dispersion (silver nanofiber (diameter 50 nm, length 50 μm), binder resin (polyvinyl alcohol), solvent (water), solid content 2% by mass (silver nanofiber : Binder resin (mass ratio) = 4: 1)) was coated with a wire bar coater. After coating, the mixture was allowed to stand at room temperature for 10 minutes to precipitate silver nanofibers, and then dried in a drying furnace at 120 ° C. for 10 minutes to form a transparent conductive film having a thickness of 25 nm. The film thickness was adjusted so that the surface resistivity was 200 ± 20Ω / □. From the micrograph of the transparent conductive film, the vicinity of the interface (from the interface) between the metal nanofiber concentration (C s ) near the surface of the transparent conductive film (in the range of 1/3 of the total film thickness) and the transparent substrate of the transparent conductive film The concentration ratio (C s / C b ) to the metal nanofiber concentration (C b ) in the range of 1/3 of the total film thickness was 0.89.

[実施例2]
透明導電膜の表面抵抗率が500±20Ω/□になるように、膜厚を15nmに調製した以外は、実施例1と同様に透明導電膜を形成した。上記の濃度比(Cs/Cb)は、0.92であった。
[Example 2]
A transparent conductive film was formed in the same manner as in Example 1 except that the film thickness was adjusted to 15 nm so that the surface resistivity of the transparent conductive film was 500 ± 20 Ω / □. The concentration ratio (C s / C b ) was 0.92.

[比較例1]
銀ナノ繊維分散液を塗工後、静置せず、すぐに乾燥炉で(振動させながら)乾燥した以外は、実施例1と同様に透明導電膜を形成した。上記の濃度比(Cs/Cb)は、1.13であった。
[Comparative Example 1]
A transparent conductive film was formed in the same manner as in Example 1 except that after the silver nanofiber dispersion was applied, it was not allowed to stand and was immediately dried (vibrated) in a drying furnace. The concentration ratio (C s / C b ) was 1.13.

[比較例2]
銀ナノ繊維分散液を塗工後、静置せず、すぐに乾燥炉で(振動させながら)乾燥した以外は、実施例2と同様に透明導電膜を形成した。上記の濃度比(Cs/Cb)は、1.11であった。
[Comparative Example 2]
A transparent conductive film was formed in the same manner as in Example 2 except that the silver nanofiber dispersion was not left standing after coating, but was immediately dried (vibrated) in a drying furnace. The concentration ratio (C s / C b ) was 1.11.

2.評価方法
(1)表面抵抗率
上記でPETフィルム上に形成した各透明導電膜のサンプル(4×6cm)について、初期及び環境耐久試験(温度60℃、湿度90%RH、200時間)後の表面抵抗率をロレスタMCP−T610(三菱化学アナリテック社製)を用いて測定した。
(2)全光線透過率
(1)と同様のサンプルについて、ヘイズメータNDH2000(日本電色工業社製)を用いて、全光線透過率を測定した。
2. Evaluation method (1) Surface resistivity The surface after the initial and environmental durability tests (temperature 60 ° C., humidity 90% RH, 200 hours) for each transparent conductive film sample (4 × 6 cm) formed on the PET film above. The resistivity was measured using Loresta MCP-T610 (Mitsubishi Chemical Analytech Co., Ltd.).
(2) Total light transmittance About the sample similar to (1), the total light transmittance was measured using haze meter NDH2000 (made by Nippon Denshoku Industries Co., Ltd.).

3.評価結果
各透明導電膜の評価結果を表1に示す。
3. Evaluation results Table 1 shows the evaluation results of each transparent conductive film.

Figure 2013089334
Figure 2013089334

表1に示す通り、透明導電膜の表面近傍の銀ナノ繊維濃度が、透明導電膜のPETフィルムとの界面近傍の銀ナノ繊維濃度に比べて低い実施例1及び2の透明導電膜は、初期及び環境耐久試験後の表面抵抗率にほとんど変化がなく、湿熱耐久性が高いことが認められた。一方、透明導電膜の表面近傍の銀ナノ繊維濃度が、透明導電膜のPETフィルムとの界面近傍の銀ナノ繊維濃度に比べて高い比較例1及び2の透明導電膜は、環境耐久試験後の表面低効率が上昇しており、銀ナノ繊維が透明導電膜表面において、酸化され導電性が低下していた。   As shown in Table 1, the concentration of silver nanofibers near the surface of the transparent conductive film is lower than the concentration of silver nanofibers near the interface of the transparent conductive film with the PET film. In addition, it was confirmed that the surface resistivity after the environmental durability test hardly changed and the wet heat durability was high. On the other hand, the transparent conductive film of Comparative Examples 1 and 2 in which the silver nanofiber concentration near the surface of the transparent conductive film is higher than the silver nanofiber concentration near the interface with the PET film of the transparent conductive film The surface low efficiency was increased, and the silver nanofibers were oxidized on the surface of the transparent conductive film and the conductivity was lowered.

従って、本発明により、金属ナノ繊維を含み、湿熱耐久性に優れた透明導電膜を有する透明導電体が得られることが示された。   Therefore, according to the present invention, it has been shown that a transparent conductor containing a metal nanofiber and having a transparent conductive film excellent in wet heat durability can be obtained.

なお、本発明は上記の実施の形態及び実施例に限定されるものではなく、発明の要旨の範囲内で種々変形が可能である。   In addition, this invention is not limited to said embodiment and Example, A various deformation | transformation is possible within the range of the summary of invention.

液晶表示素子、有機発光素子、無機電界発光素子、タッチパネル、電子ペーパー等の電子デバイスに用いることができる湿熱耐久性に優れた透明導電膜を有する透明導電体を低コストで提供することができる。   A transparent conductor having a transparent conductive film excellent in wet heat durability that can be used for electronic devices such as liquid crystal display elements, organic light-emitting elements, inorganic electroluminescent elements, touch panels, and electronic paper can be provided at low cost.

11、21、31:透明基板
12、22:透明導電膜
20、30、40:透明導電体
22A:第1導電層
22B:第2導電層
12L:塗工液層
19、29、39:金属ナノ繊維
35:透明電極
11, 21, 31: Transparent substrate 12, 22: Transparent conductive film 20, 30, 40: Transparent conductor 22A: First conductive layer 22B: Second conductive layer 12L: Coating liquid layer 19, 29, 39: Metal nano Fiber 35: Transparent electrode

Claims (10)

透明基板と、その表面に形成された、金属ナノ繊維及びバインダ樹脂を含む透明導電膜とを含む透明導電体であって、
前記透明導電膜における金属ナノ繊維が、厚さ方向に濃度分布を有しており、且つ
前記透明導電膜の前記透明基板と反対側の表面近傍における金属ナノ繊維濃度が、前記透明導電膜の前記透明基板との界面近傍における金属ナノ繊維濃度に比べて低いことを特徴とする透明導電体。
A transparent conductor comprising a transparent substrate and a transparent conductive film containing metal nanofibers and a binder resin formed on the surface thereof,
The metal nanofibers in the transparent conductive film have a concentration distribution in the thickness direction, and the metal nanofiber concentration in the vicinity of the surface of the transparent conductive film opposite to the transparent substrate is A transparent conductor characterized in that it is lower than the metal nanofiber concentration in the vicinity of the interface with the transparent substrate.
前記透明導電膜の表面近傍が、前記透明導電膜の表面から前記透明基板方向に対して透明導電膜の総膜厚の1〜40%の範囲であり、且つ
前記透明導電膜の前記透明基板との界面近傍が、前記透明導電膜の前記透明基板との界面から透明導電膜の表面方向に対して前記透明導電膜の総膜厚の1〜40%の範囲である請求項1に記載の透明導電体。
The vicinity of the surface of the transparent conductive film is in the range of 1 to 40% of the total film thickness of the transparent conductive film with respect to the transparent substrate direction from the surface of the transparent conductive film, and the transparent substrate of the transparent conductive film The transparent vicinity according to claim 1, wherein the vicinity of the interface is in the range of 1 to 40% of the total film thickness of the transparent conductive film with respect to the surface direction of the transparent conductive film from the interface of the transparent conductive film with the transparent substrate. conductor.
前記透明導電膜の表面から前記透明基板方向に対して前記透明導電膜の総膜厚の1/3の範囲における金属ナノ繊維濃度(Cs)の、前記透明導電膜の前記透明基板との界面から前記透明導電膜の表面方向に対して透明導電膜の総膜厚の1/3の範囲における金属ナノ繊維濃度(Cb)に対する濃度比(Cs/Cb)が、0.1〜0.95である請求項1又は2に記載の透明導電体。 The interface between the transparent conductive film and the transparent substrate at a metal nanofiber concentration (C s ) in the range of 1/3 of the total film thickness of the transparent conductive film from the surface of the transparent conductive film to the transparent substrate direction. The concentration ratio (C s / C b ) to the metal nanofiber concentration (C b ) in the range of 1/3 of the total film thickness of the transparent conductive film with respect to the surface direction of the transparent conductive film is 0.1-0. The transparent conductor according to claim 1, which is .95. 前記透明導電膜全体の金属ナノ繊維濃度が、1〜90体積%である請求項1〜3のいずれか1項に記載の透明導電体。   4. The transparent conductor according to claim 1, wherein the concentration of the metal nanofibers in the entire transparent conductive film is 1 to 90% by volume. 前記金属ナノ繊維が、銀からなる請求項1〜4のいずれか1項に記載の透明導電体。   The transparent conductor according to claim 1, wherein the metal nanofiber is made of silver. 前記バインダ樹脂が、導電性高分子を含む請求項1〜5のいずれか1項に記載の透明導電体。   The transparent conductor according to claim 1, wherein the binder resin contains a conductive polymer. 前記導電性高分子が、下記式(I):
Figure 2013089334
(式中、R1及びR2は、それぞれ独立して水素原子若しくは炭素原子数1〜4のアルキル基を表し、又はR1及びR2が相互に結合して任意に置換されていても良い炭素原子数1〜4のアルキレン基を形成し、nは50〜1000の整数を表す)で表される繰り返し単位を含むポリチオフェン誘導体である請求項6に記載の透明導電体。
The conductive polymer has the following formula (I):
Figure 2013089334
(In the formula, R 1 and R 2 each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, or R 1 and R 2 may be bonded to each other and optionally substituted. The transparent conductor according to claim 6, wherein the transparent conductor is a polythiophene derivative containing a repeating unit represented by: an alkylene group having 1 to 4 carbon atoms, wherein n represents an integer of 50 to 1,000.
総膜厚が、5〜3000nmである請求項1〜7のいずれか1項に記載の透明導電体。   The transparent conductor according to any one of claims 1 to 7, wherein the total film thickness is 5 to 3000 nm. 前記透明導電膜が、前記透明基板表面にパターニング処理されてなる透明電極である請求項1〜8のいずれか1項に記載の透明導電体。   The transparent conductor according to claim 1, wherein the transparent conductive film is a transparent electrode formed by patterning the surface of the transparent substrate. 透明基板表面に、金属ナノ繊維及びバインダ樹脂を含む透明導電膜用塗工液を塗布して塗工液層を形成し、塗工液層における金属ナノ繊維を透明基板方向に沈降させた後、前記塗工液層を乾燥及び/又は硬化させることを特徴とする透明導電体の製造方法。   After applying a coating liquid layer for transparent conductive film containing metal nanofibers and a binder resin on the transparent substrate surface to form a coating liquid layer, the metal nanofibers in the coating liquid layer are precipitated in the direction of the transparent substrate, A method for producing a transparent conductor, wherein the coating liquid layer is dried and / or cured.
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KR20180060327A (en) * 2016-11-28 2018-06-07 엘지디스플레이 주식회사 Substrate embedded transparent conducting layer and method of fabricating the same, and electric device using the substrate
US10831327B2 (en) 2016-09-30 2020-11-10 Dai Nippon Printing Co., Ltd. Electroconductive film, touch panel, and image display device

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10831327B2 (en) 2016-09-30 2020-11-10 Dai Nippon Printing Co., Ltd. Electroconductive film, touch panel, and image display device
US11298925B2 (en) 2016-09-30 2022-04-12 Dai Nippon Printing Co., Ltd. Electroconductive film, touch panel, and image display device
US11648759B2 (en) 2016-09-30 2023-05-16 Dai Nippon Printing Co., Ltd. Electroconductive film, touch panel, and image display device
KR20180060327A (en) * 2016-11-28 2018-06-07 엘지디스플레이 주식회사 Substrate embedded transparent conducting layer and method of fabricating the same, and electric device using the substrate
KR102632503B1 (en) * 2016-11-28 2024-01-31 엘지디스플레이 주식회사 Substrate embedded transparent conducting layer and method of fabricating the same, and electric device using the substrate

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