JP4573266B2 - Transparent conductive sheet - Google Patents
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本発明は、透明基板上に透明導電性塗膜を設けてなる透明導電性シートに関し、さらに詳しくは透明導電性塗膜が２以上の層から構成されている塗布型の透明導電性シートに関する。 The present invention relates to a transparent conductive sheet in which a transparent conductive coating film is provided on a transparent substrate, and more particularly to a coating type transparent conductive sheet in which the transparent conductive coating film is composed of two or more layers.
従来、透明導電性塗膜として、酸化スズ粒子、アンチモン含有酸化スズ粒子、スズ含有酸化インジウム粒子などをバインダ中に分散させて基板上に塗布した塗膜が知られている。中でもスズ含有酸化インジウム粒子を用いた塗膜は、その可視光に対する高い透光性と、その高い導電性から、静電気防止や電磁波遮蔽が要求されるＣＲＴ画面、ＬＣＤ画面などのデイスプレー用や、さらにはタッチパネル用など、広範囲での応用が期待されている。スズ含有酸化インジウムは、可視光に対して透明であると同時に、酸素欠損により導電性を示す半導体であり、酸化インジウム中のスズがＳｎ4+となって電子供給源となり、高い導電性を示すと考えられている。 Conventionally, a coating film in which tin oxide particles, antimony-containing tin oxide particles, tin-containing indium oxide particles and the like are dispersed in a binder and applied onto a substrate is known as a transparent conductive coating film. Among them, the coating film using tin-containing indium oxide particles is used for displays such as CRT screens and LCD screens that require static electricity prevention and electromagnetic wave shielding because of its high transparency to visible light and high conductivity. Furthermore, it is expected to be applied in a wide range such as for touch panels. Tin-containing indium oxide is a semiconductor that is transparent to visible light and at the same time exhibits conductivity due to oxygen deficiency, and tin in indium oxide becomes Sn 4+ and serves as an electron supply source, and exhibits high conductivity. It is believed that.
スズ含有酸化インジウム粒子をバインダ（結合剤）中に分散させて塗布して使用する場合、高い導電性を得るためには、通常、塗膜中に粒子を高充填するか、粒子サイズの大きい粒子を用いることが有効である。これは、バインダは通常絶縁性であるため、塗膜中のバインダの占有体積を少なくし、導電性物質であるスズ含有酸化インジウム粒子が占有する体積を多くすることにより、導電性を高くする、あるいは、スズ含有酸化インジウムの粒子サイズを大きくすることで粒子内電子伝導距離を増加させ、粒子間接触点を減らし、接触抵抗を減少させることにより、導電性を高くするものである。しかしながら、塗膜中にスズ含有酸化インジウム粒子を高充填するとバインダ量が減少し、スズ含有酸化インジウム粒子同士、およびスズ含有酸化インジウム粒子と基材との結合が弱くなり、塗膜の強度が低下し、ひび割れ、剥がれなどを引き起こす。また、本来、スズ含有酸化インジウム粒子などの無機粒子は不透明なものであり、粒子サイズを大きくしすぎると透明性に悪影響を及ぼすため、通常では可視光波長の下限値（約４００ｎｍ）の１／２よりも小さな粒子サイズである約２００ｎｍ以下の粒子が用いられる。 When tin-containing indium oxide particles are dispersed in a binder (binder) and used, in order to obtain high electrical conductivity, the coating is usually highly charged or particles with a large particle size. It is effective to use. This is because the binder is usually insulating, so the volume occupied by the binder in the coating film is reduced, and the volume occupied by the tin-containing indium oxide particles as the conductive material is increased, thereby increasing the conductivity. Alternatively, by increasing the particle size of the tin-containing indium oxide, the electron conduction distance in the particle is increased, the contact point between the particles is decreased, and the contact resistance is decreased, thereby increasing the conductivity. However, if the tin-containing indium oxide particles are highly filled in the coating film, the amount of the binder decreases, the bonding between the tin-containing indium oxide particles and between the tin-containing indium oxide particles and the substrate weakens, and the strength of the coating film decreases. Cause cracking and peeling. In addition, inorganic particles such as tin-containing indium oxide particles are originally opaque, and if the particle size is too large, the transparency is adversely affected. Therefore, usually, 1 / of the lower limit of the visible light wavelength (about 400 nm). Particles of about 200 nm or less with a particle size smaller than 2 are used.
一方で高い透明性を得るためには、塗膜中の粒子の充填率を低くするか、粒子サイズの小さい粒子を用いることが有効である。なぜなら、スズ含有酸化インジウム粒子のような無機粒子それ自体は本質的には不透明で光を透過させないが、このような無機粒子を含ませた塗膜中においてその占有体積を小さくするか、光の波長以下まで粒子サイズを小さくすることで、塗膜の透明性を確保できるようになるからである。 On the other hand, in order to obtain high transparency, it is effective to lower the filling rate of particles in the coating film or to use particles having a small particle size. This is because inorganic particles such as tin-containing indium oxide particles are essentially opaque and do not transmit light. However, in the coating film containing such inorganic particles, the occupied volume is reduced or light This is because the transparency of the coating film can be secured by reducing the particle size to the wavelength or less.
このように、導電性を向上させるために無機粒子の充填率を上げたり粒子サイズを大きくしたりすると、透明性および塗膜強度の低下を招き、逆に高い透明性を得るために塗膜中の無機粒子の充填率を低くしたり粒子サイズを小さくすると、導電性が低下することになり、これらはお互いトレードオフの関係にある。 Thus, increasing the filling rate of inorganic particles or increasing the particle size in order to improve conductivity leads to a decrease in transparency and coating strength, and conversely, in order to obtain high transparency, When the filling rate of the inorganic particles is reduced or the particle size is reduced, the conductivity is lowered, and these are in a trade-off relationship with each other.
このような事情から、従来においては、高い透明性と優れた導電性と所要の塗膜強度とを併せ持った透明導電性シートはいまだ見当たらない。例えば特許文献１には、粒子径４０ｎｍのスズ含有酸化インジウム粒子を用いて、塗膜中の粒子の体積含有率を６０〜８０％とし、膜厚３μｍの乾燥塗布膜を作製した後、スチールロールによって圧延処理を施したものが挙げられているが、表面抵抗率が１００Ω/ □以下である場合には、全光透過率が７０％以下となり、全光透過率が８０％程度という高い透明性を保持するためには、表面抵抗率が犠牲になる結果となっている。
Under such circumstances, a transparent conductive sheet having both high transparency, excellent conductivity, and required coating strength has not been found so far. For example, in Patent Document 1, after using a tin-containing indium oxide particle having a particle diameter of 40 nm to make a volume content of particles in a
また、特許文献２には、特許文献１の塗膜強度を向上させたものとして、上記スチールロールによる圧延処理の後、電子線硬化処理を施すことにより作製した透明導電性シートが挙げられているが、いずれも全光透過率は８０％前後であるのに対し、表面抵抗率は２００Ω/ □以上となっている。 Patent Document 2 includes a transparent conductive sheet produced by applying an electron beam curing treatment after rolling with the steel roll, as an improvement in the coating film strength of Patent Literature 1. However, in all cases, the total light transmittance is about 80%, while the surface resistivity is 200Ω / □ or more.
上記文献に記載された透明導電性シートは、いずれも透明導電性塗膜が単層構造のものであるが、少なくとも一層の導電膜と少なくとも一層の透明膜とを組み合わせて複数の機能を持つ重層塗布構造の透明導電性シートも知られている。例えば特許文献３では、スズ含有酸化インジウムを含有するスピンコートされた透明導電膜の上層に、黒色顔料微粒子を含有した膜をスピンコートにより形成し、低透過率透明導電性基材が得られている。たたじ、この特許文献３記載の技術は、帯電防止効果（その表面抵抗率は１０ｋΩ/ □以上となっている）を確保する一方で、黒色顔料を用いて透過率を減少させることにより表面反射を抑制することが目的となっている。 Each of the transparent conductive sheets described in the above documents has a single layer structure of the transparent conductive coating film, but is a multilayer having a plurality of functions by combining at least one conductive film and at least one transparent film. A transparent conductive sheet having a coating structure is also known. For example, in Patent Document 3, a film containing black pigment fine particles is formed by spin coating on a spin-coated transparent conductive film containing tin-containing indium oxide to obtain a low-transmittance transparent conductive substrate. Yes. In addition, the technique described in Patent Document 3 ensures the antistatic effect (the surface resistivity is 10 kΩ / □ or more), while reducing the transmittance using a black pigment. The purpose is to suppress reflection.
上記のように従来においては、所要の塗膜強度を確保した上で高い透明性と優れた導電性とを両立させた塗布型の透明導電性シートは未だ実現されていない。特に透明性と導電性について言えば、目的に応じて適当にバランスさせているにすぎず、両者ともに高い次元でバランスさせたものは見当たらない。そのため、従来における塗布型の透明導電性シートでは、蒸着やスパッタ法で作製したスズ含有酸化インジウム膜（ＩＴＯ膜）に比べて特性において見劣りし、塗布媒体の簡便性と低コスト性を十分に活かしきれておらず、限られた用途にしか適用できないのが現状である。 As described above, conventionally, a coating-type transparent conductive sheet that achieves both high transparency and excellent conductivity while ensuring the required coating strength has not been realized. Especially when it comes to transparency and electrical conductivity, they are only appropriately balanced according to the purpose, and there is no balance in both dimensions. For this reason, conventional coating-type transparent conductive sheets are inferior in properties compared to tin-containing indium oxide films (ITO films) produced by vapor deposition or sputtering, and fully utilize the simplicity and low cost of coating media. The current situation is that it can only be used for limited purposes.
本発明は、このような現状に鑑みてなされたもので、従来は不可能と考えられてきた高い充填率で無機粒子を含有させ、かつ塗膜強度を保ち、優れた導電性と高い透明性とを両立させた透明導電性シートを実現することを目的とする。 The present invention has been made in view of such a current situation, and contains inorganic particles at a high filling rate, which has been considered impossible in the past, and maintains coating film strength, excellent conductivity and high transparency. It aims at realizing the transparent conductive sheet which made it compatible.
本発明者らは、上記の目的を達成するため鋭意検討した結果、塗布型の透明導電性シートを構成する透明導電性塗膜を、従来の導電性粒子を含む単層の塗布膜ではなく、重層構成の塗布膜とすることで、透明性を損なうことなく導電性粒子を高充填でき、したがって所要の塗膜強度を保った上で高い透明性と優れた導電性が得られることを見出した。 As a result of intensive studies to achieve the above object, the inventors of the present invention have made the transparent conductive coating film constituting the coating-type transparent conductive sheet, not a conventional single-layer coating film containing conductive particles, It has been found that by using a multi-layer coating film, it is possible to highly fill conductive particles without impairing transparency, and thus high transparency and excellent conductivity can be obtained while maintaining the required coating film strength. .
すなわち、本発明は、透明基板上に透明導電性塗膜を設けてなる透明導電性シートにおいて、前記透明導電性塗膜が、ＩＴＯ粒子等の導電性酸化物粒子を含有する上層透明導電性塗膜層と、これよりも下層側つまり透明基板側に位置して無機粒子およびバインダ樹脂を含有する下層透明塗膜層との少なくとも２層を含んでなり、かつ、このうちの上層透明導電性塗膜層の平均空孔率が３０％以下である構成とし、更に、前記透明導電性塗膜は、前記下層透明塗膜層を塗布・乾燥により形成し、その上から前記上層透明導電性塗膜層を塗布・乾燥により形成した後、カレンダ処理を行うことにより前記透明基板上に形成されたものであり、前記上層透明導電性塗布層を圧縮したとき、該上層透明導電性塗布層における下部側の導電性酸化物粒子がその直下に位置する層に食い込んだ状態となり、該上層透明導電性塗布層の直下に位置する層に食い込んだ導電性酸化物粒子がアンカー効果を発揮するようになっており、上層透明導電性塗膜層中の導電性酸化物粒子の含有率が８６〜９９重量％であり、下層透明塗膜層中の無機粒子の含有率が５０〜８０重量％である構成としたものである。 That is, the present invention provides a transparent conductive sheet having a transparent conductive coating provided on a transparent substrate, wherein the transparent conductive coating contains a conductive oxide particle such as ITO particles. And comprising at least two layers of a film layer and a lower transparent coating layer containing inorganic particles and a binder resin located on the lower layer side, that is, on the transparent substrate side, and the upper transparent conductive coating of these layers. The membrane layer has an average porosity of 30% or less, and the transparent conductive coating film is formed by applying and drying the lower transparent coating layer, and then the upper transparent conductive coating film is formed thereon. After forming the layer by coating and drying, it is formed on the transparent substrate by performing a calendering process, and when the upper transparent conductive coating layer is compressed, the lower side of the upper transparent conductive coating layer Conductive oxide particles A state that bites the layer located immediately below them, ending past conductive oxide particles in a layer located immediately below the upper layer transparent conductive coating layer is adapted to exert an anchor effect, the upper transparent conductive coating The content of the conductive oxide particles in the film layer is 86 to 99% by weight, and the content of the inorganic particles in the lower transparent coating film layer is 50 to 80% by weight.
このような平均空孔率を有する上層透明導電性塗膜層は、透明基板上に、無機粒子を含有する下層透明塗膜層用の塗料を塗布し、さらにその上に他の中間層等を介して或いは中間層等を介することなく直接、導電性酸化物粒子を含有する上層透明導電性塗膜層用の塗料を塗布して乾燥させた後、得られた塗膜に対しカレンダ処理あるいはプレス処理を施すことによって作製することができる。 The upper transparent conductive coating layer having such an average porosity is coated with a coating for a lower transparent coating layer containing inorganic particles on a transparent substrate, and another intermediate layer or the like is further formed thereon. The coating for the upper transparent conductive coating layer containing the conductive oxide particles is applied directly through the intermediate layer without passing through the intermediate layer or the like and dried, and then the resulting coating is calendered or pressed. It can produce by processing.
ここで、上記平均空孔率における「空孔」とは導電性酸化物や無機粒子等用いた粉体が存在しない空間のことを意味し、ＦＩＢ（収束イオンビーム法）により加工された塗膜の断面ＳＥＭ写真の黒色部分を指す。この平均空孔率を測定することにより、塗膜がプレス処理されて、膜中にある酸化物微粒子、無機微粒子が高充填化されていることがわかる。ここで、カンレンダーまたはプレス後の平均空孔率は３０％以下とする必要があり、好ましくは２５％以下である。平均空孔率が３０％以上である場合には、カレンダ処理またはプレス処理されていないと考えられ、粒子が密に詰まっておらず、空孔が大きいため、導電性および透光性が向上しない。一方、平均空孔率の下限値については、上述したような本発明の効果が得られる限り特に限定されないが、実際には現在一般に市販されているプレス装置（例えば康井精機社製スーパーカレンダＬＣ−５２）で８％未満の平均空孔率を達成しようとしても圧力の限界を超えてしまうため、現状では、実現できない。すなわち、平均空孔率の実用上の下限値は８％であり、好ましい上限値は２５％である。 Here, the “hole” in the average porosity means a space where there is no powder using conductive oxide or inorganic particles, and the coating film processed by FIB (focused ion beam method). The black part of the cross-sectional SEM photograph of is shown. By measuring this average porosity, it can be seen that the coating film has been pressed, and the oxide fine particles and inorganic fine particles in the film are highly filled. Here, the average porosity after the calendar or press needs to be 30% or less, and preferably 25% or less. When the average porosity is 30% or more, it is considered that calendaring or pressing is not performed, and the particles are not densely packed and the pores are large, so that the conductivity and translucency are not improved. . On the other hand, the lower limit value of the average porosity is not particularly limited as long as the above-described effects of the present invention can be obtained, but in practice, a press apparatus currently commercially available (for example, Super Calendar LC manufactured by Yasui Seiki Co., Ltd.). Even if it is attempted to achieve an average porosity of less than 8% in -52), the pressure limit will be exceeded, so this cannot be realized at present. That is, the practical lower limit of the average porosity is 8%, and the preferable upper limit is 25%.
単層の透明導電性塗膜の場合には、導電性酸化物粒子を高い比率で含有させると、その分だけ逆にバイダーの含有量が少なくなるため、その塗膜強度が低下する。また、上記のようなカレンダ処理あるいはプレス処理を行っても、後述するように、その圧力効果はその表面の近傍部分に止まるため、深層部分（下層側部分）ではカレンダ処理等の前後で導電性酸化物粒子の充填率はあまり変化しないことが多い。 In the case of a single-layer transparent conductive coating film, if conductive oxide particles are contained in a high ratio, the content of the binder is reduced by that amount, so that the coating film strength is lowered. In addition, even if the above calendering or pressing treatment is performed, the pressure effect remains in the vicinity of the surface, as will be described later. Therefore, in the deep layer portion (lower layer side portion), it is conductive before and after the calendering treatment. The filling rate of oxide particles often does not change much.
これに対して、本発明の透明導電性シートのように、その透明導電性塗膜が、導電性酸化物粒子を含む透明導電性塗膜層の下側に無機粒子およびバインダを含有した透明塗膜層を設けた重層構成とされていると、カレンダ処理あるいはプレス処理を行ったときに、透明導電性塗膜の表面側の部分を形成している上層透明導電性塗膜層にカレンダ等あるいはプレスによる圧力効果が十分に及ぶため、上層透明導電性塗膜層においては導電性酸化物粒子の充填率が単層の透明導電性塗膜の場合に比べて高くなる。 On the other hand, like the transparent conductive sheet of the present invention, the transparent conductive coating film contains a transparent coating containing inorganic particles and a binder under the transparent conductive coating layer containing conductive oxide particles. When the multilayer structure is provided with a film layer, when the calendar process or the press process is performed, the upper transparent conductive coating layer that forms the surface side portion of the transparent conductive coating layer has a calendar or the like or Since the pressure effect by the press is sufficiently extended, the filling rate of the conductive oxide particles in the upper transparent conductive coating layer is higher than that in the case of the single-layer transparent conductive coating layer.
また、カレンダ処理あるいはプレス処理を行って上層透明導電性塗膜層を圧縮したときには、上層透明導電性塗膜層における下部側の導電性酸化物粒子がその直下に位置する下層透明塗膜層あるいは中間層に食い込んだ状態となり、その部分がアンカー効果を発揮することにより、上層透明導電性塗膜層がその直下の中間層あるいは下層透明塗膜層に対して強固に結合され、同時に表面平滑性も向上する。しかも、カレンダ処理あるいはプレス処理による圧縮時には、上層透明導電性塗膜層の導電性酸化物粒子間にも例えば下層透明塗膜層側からのバインダが浸透して、上層透明導電性塗膜層の導電性酸化物粒子同士の結合を強固なものとする。したがって、このようなバインダによる結合と前記アンカー効果による結合さらにはカレンダ処理あるいはプレス処理の圧力効果による粒子間の結合により、透明導電性塗膜について所要の塗膜強度を確保することが可能となる。 In addition, when the upper transparent conductive coating layer is compressed by calendaring or pressing, the lower transparent coating layer in which the lower conductive oxide particles in the upper transparent conductive coating layer are located immediately below or The intermediate transparent layer is encroached into the intermediate layer and exerts an anchor effect, so that the upper transparent conductive coating layer is firmly bonded to the intermediate layer or lower transparent coating layer directly below it, and at the same time surface smoothness Will also improve. Moreover, during compression by calendering or pressing, for example, a binder from the lower transparent coating layer side penetrates between the conductive oxide particles of the upper transparent conductive coating layer, and the upper transparent conductive coating layer Strengthen the bond between the conductive oxide particles. Therefore, it is possible to ensure the required coating strength for the transparent conductive coating film by such binding by the binder and the coupling by the anchor effect, and also by the coupling between particles by the pressure effect of the calendering or pressing process. .
このように本発明の構成によれば、透明導電性塗膜層中の導電性酸化物粒子の高い充填率と塗膜強度の確保とを矛盾なく両立させることができ、導電性や塗膜強度を犠牲にすることなく高い透明性を持った透明導電性シートを実現することができる。 As described above, according to the configuration of the present invention, the high filling rate of the conductive oxide particles in the transparent conductive coating layer and the securing of the coating strength can be achieved without contradiction. A transparent conductive sheet having high transparency can be realized without sacrificing the above.
本発明によれば、所要の塗膜強度と高い透明性と優れた導電性とを併せ持った透明導電性シートを実現できる。具体的には例えば透明導電性塗膜の厚さが1.０〜１０μｍの範囲にあり、全光透過率が７０〜９５％で、かつ表面抵抗率が１０〜１０００Ω/ □である透明導電性シートを実現できる。 According to the present invention, it is possible to realize a transparent conductive sheet having both required coating film strength, high transparency, and excellent conductivity. Specifically, for example, the transparent conductive film has a thickness of 1.0 to 10 μm, a total light transmittance of 70 to 95%, and a surface resistivity of 10 to 1000Ω / □. A sheet can be realized.
従来の導電性粒子を含む単層の塗布膜では、導電性を向上させるために導電性粒子の含有率を上げると、導電性粒子同士および導電性粒子と基材との結合が弱くなり塗膜強度が著しく低下し、さらに、導電性粒子そのものによる透過光の遮蔽のみならず、バインダ成分の減少により表面に直接導電性粒子が現れることにより表面平滑性が低下し散乱光が増え、透明性が低下するため、ある程度の妥協点を見出して含有率が決定されていた。これに対して、本発明の透明導電性シートのように、無機粒子を含有する塗膜層（透明塗膜層）を別に形成し、例えばこの層を下層に用いて導電性粒子を含有する塗膜層（透明導電性塗膜層）を上層に重層塗布し、プレス処理あるいはカレンダ処理を施すことにより、上層の導電性粒子が均一に下層中に埋め込まれるため、表面平滑性が向上し、導電性粒子間の隙間に下層のバインダ成分が浸透し、その結果、導電性粒子の含有率を増加させても塗膜強度および透明性が低下せず、導電性を飛躍的に向上させることができる。 In conventional single-layer coating films containing conductive particles, if the content of conductive particles is increased in order to improve conductivity, the bonding between the conductive particles and between the conductive particles and the substrate is weakened. In addition to significantly reducing the strength, not only shielding the transmitted light by the conductive particles themselves, but also the appearance of the conductive particles directly on the surface due to the reduction of the binder component, the surface smoothness is reduced, the scattered light is increased, and the transparency is increased. The content ratio was determined by finding a certain degree of compromise because of a decrease. On the other hand, a coating layer containing inorganic particles (transparent coating layer) is separately formed as in the transparent conductive sheet of the present invention. For example, a coating layer containing conductive particles is formed using this layer as a lower layer. The upper layer conductive particles are uniformly embedded in the lower layer by applying a film layer (transparent conductive coating layer) to the upper layer and applying press treatment or calendering treatment. As a result, the binder component in the lower layer penetrates into the gaps between the conductive particles. As a result, even if the content of the conductive particles is increased, the coating film strength and transparency are not lowered, and the conductivity can be dramatically improved. .
通常塗布膜をプレス処理あるいはカレンダ処理する場合には、その圧力効果は塗膜の表面に近い部分にしか及ばないため、実際には、塗布した導電性粒子のうちの一部のみが高密度となり、表面部分を主として導電パスが形成される結果となる。 In general, when the coating film is pressed or calendered, the pressure effect only affects the part close to the surface of the coating film, so in reality, only a part of the applied conductive particles has a high density. As a result, a conductive path is mainly formed on the surface portion.
一方、導電性粒子を高充填した単層塗布膜にプレス処理あるいはカレンダ処理を施した場合には、導電性は向上するが、バインダ成分が不十分なため、塗膜強度を維持することが困難になる。したがって導電性粒子の充填率が高くなると、導電性は向上する反面、塗膜強度が低下する。 On the other hand, when a single-layer coating film highly filled with conductive particles is pressed or calendered, the conductivity is improved, but it is difficult to maintain the coating strength due to insufficient binder components. become. Therefore, when the filling rate of the conductive particles is increased, the conductivity is improved, but the coating film strength is decreased.
これに対して、本発明の透明導電性シートのように、無機粒子を含有する塗膜層を下層に用い、上層に導電性粒子を含有する塗膜層を形成した場合には、プレス処理あるいはカレンダ処理の効果が現れやすい上層部分に導電性層が存在するため、導電性層は効率的に圧力の効果を受け、導電性粒子が高密度となることによる導電性の向上と、塗膜中の平均空孔率が減少し膜表面の散乱光の減少による透明性の向上とを図ることができる。 On the other hand, like the transparent conductive sheet of the present invention, when a coating layer containing inorganic particles is used for the lower layer and a coating layer containing conductive particles is formed on the upper layer, press treatment or Since the conductive layer exists in the upper layer part where the effect of the calendar treatment is likely to appear, the conductive layer is effectively subjected to the effect of pressure, and the conductive particles are improved in density by increasing the density of the conductive particles. Therefore, it is possible to improve the transparency by reducing the scattered light on the film surface.
また、プレス処理あるいはカレンダ処理により、上層の導電性粒子の隙間に、下層に含まれるバインダ成分が浸透するため、導電性粒子を高充填させても、十分な塗膜強度を保つことができる。さらには、高充填される上層に導電性粒子が存在するため、少ない導電性粒子に対して効果的に導電性を発現させることができる。 Moreover, since the binder component contained in the lower layer penetrates into the gaps between the upper conductive particles by pressing or calendering, sufficient coating strength can be maintained even when the conductive particles are highly filled. Furthermore, since the conductive particles are present in the highly filled upper layer, the conductivity can be effectively expressed with respect to a small number of conductive particles.
このように、本発明の透明導電性シートは、好ましい構成として、無機粒子を含有する塗膜層を下層に、導電性粒子を含有する塗膜層を上層に設けてプレス処理あるいはカレンダ処理することにより、上層の導電性粒子が効率的に高密度化され導電性が向上し、表面における散乱光が減少し、かつ、最上層の導電性粒子間の隙間に下層中のバインダ成分が浸透するため、十分な塗膜強度を保持することができる。 As described above, the transparent conductive sheet of the present invention preferably has a coating layer containing inorganic particles as a lower layer and a coating layer containing conductive particles as an upper layer, and is subjected to press treatment or calendar treatment as a preferred configuration. As a result, the conductive particles in the upper layer are efficiently densified, the conductivity is improved, the scattered light on the surface is reduced, and the binder component in the lower layer penetrates into the gaps between the uppermost conductive particles. Sufficient coating strength can be maintained.
導電性粒子を含む上層透明導電性塗膜層中の導電性粒子の含有量が８６〜９９重量％であり、無機粒子を含有する下層透明塗膜層中の無機粒子の含有量が５０〜８０重量％の範囲のときに導電性と透明性のバランスの最も良好な透明導電性シートとなる。導電性と透明性のバランスさらには塗膜強度の確保を考慮すると、上層透明導電性塗膜層および下層透明塗膜層を含んでなる透明導電性塗膜の厚さは、1.０〜１０μｍの範囲が好ましい。このような構成によれば、シートの全光透過率が７０〜９５％の範囲にあり、かつ表面抵抗率が１０〜１０００Ω／□の範囲にある透明導電性シートを実現できる。 The content of conductive particles in the upper transparent conductive coating layer containing conductive particles is 86 to 99% by weight, and the content of inorganic particles in the lower transparent coating layer containing inorganic particles is 50 to 80. When the weight percentage is in the range, the transparent conductive sheet having the best balance between conductivity and transparency is obtained. Considering the balance between conductivity and transparency and securing the strength of the coating film, the thickness of the transparent conductive coating film comprising the upper transparent conductive coating layer and the lower transparent coating film layer is 1.0 to 10 μm. The range of is preferable. According to such a configuration, a transparent conductive sheet having a total light transmittance of 70 to 95% and a surface resistivity of 10 to 1000Ω / □ can be realized.
本発明は、塗布型の透明導電性シートにおいて、これまで不可能と考えられてきた、透明性と導電性の両立を実現し、同時に所要の塗膜強度を確保したものであり、その特性はスパッタ膜などの、薄膜の透明導電性膜の特性に匹敵する。 The present invention is a coating-type transparent conductive sheet, which has been considered impossible until now, and realizes both transparency and conductivity, and at the same time ensures the required coating strength, and its characteristics are It is comparable to the characteristics of thin transparent conductive films such as sputtered films.
次に、本発明の透明導電性シートの製造方法について説明する。 Next, the manufacturing method of the transparent conductive sheet of this invention is demonstrated.
（下層透明塗膜層用塗料の作製）
亜鉛、アルミニウム、アンチモン、インジウム、ガドリニウム、ガリウム、カルシウム、クロム、ケイ素、ゲルマニウム、コバルト、ジルコニウム、スズ、セリウム、タングステン、チタン、鉄、銅、鉛、ニッケル、バリウム、ビスマス、マグネシウム、マンガン、モリブデン、の酸化物または水酸化物から選ばれる一種あるいは二種以上の粒子、あるいは、上記元素から選ばれる一種あるいは二種以上の元素を含有する、複合酸化物粒子または複合水酸化物粒子を、下層透明塗膜層中の含有量が５０〜８０重量％の範囲になるようにバインダ溶液中に添加して、分散させる。上記無機粒子のうち、酸化亜鉛、アルミニウム置換酸化亜鉛、酸化アルミニウム、水酸化酸化アルミニウム、酸化珪素、酸化ジルコニウム、酸化インジウム、酸化スズ、スズ含有酸化インジウム、または、これらに元素置換を施した無機粒子が、透明膜を形成する上でより好ましい。ここで言う含有量とは、上記無機粒子とバインダ、および他の各種の添加剤など、最終的な下層透明塗膜層中に占める無機粒子の重量割合を示す。含有量が５０重量％より少ない場合には、透明性は良好であるが、バインダ成分が過多となり塗膜の硬度が上がり、プレス処理等を施した際に、導電性粒子が効率的に埋め込まれにくくなる。含有量が８０重量％より多くても、透明性が損なわれなければ問題はないが、一般的に無機粒子の含有率を高くすると、透明性の高い塗膜を作製することの難易度が上がるため、好ましくない。したがって上記無機粒子の含有率は、５０〜８０重量％が好ましく、より好ましくは６０〜７５重量％の範囲である。
(Preparation of paint for lower transparent coating layer)
Zinc, aluminum, antimony, indium, gadolinium, gallium, calcium, chromium, silicon, germanium, cobalt, zirconium, tin, cerium, tungsten, titanium, iron, copper, lead, nickel, barium, bismuth, magnesium, manganese, molybdenum, 1 type or 2 or more types of particles selected from oxides or hydroxides of the above, or composite oxide particles or composite hydroxide particles containing 1 or 2 types of elements selected from the above elements, It is added to the binder solution and dispersed so that the content in the coating layer is in the range of 50 to 80% by weight. Among the above inorganic particles, zinc oxide, aluminum-substituted zinc oxide, aluminum oxide, aluminum hydroxide oxide, silicon oxide, zirconium oxide, indium oxide, tin oxide, tin-containing indium oxide, or inorganic particles obtained by subjecting them to element substitution Is more preferable in forming a transparent film. The content here refers to the weight ratio of the inorganic particles in the final lower transparent coating layer such as the inorganic particles, the binder, and other various additives. When the content is less than 50% by weight, the transparency is good, but the binder component is excessive, the coating film hardness is increased, and the conductive particles are embedded efficiently when subjected to press treatment or the like. It becomes difficult. Even if the content is more than 80% by weight, there is no problem as long as the transparency is not impaired. However, generally, when the content of the inorganic particles is increased, the difficulty of producing a highly transparent coating film increases. Therefore, it is not preferable. Therefore, the content of the inorganic particles is preferably 50 to 80% by weight, more preferably 60 to 75% by weight.
（上層透明導電性塗膜層用塗料の作製）
アルミニウム、スズ、インジウム、亜鉛、フッ素、ガリウム、アンチモン、珪素などから選ばれる、一種あるいは二種以上の元素を含む導電性酸化物粒子を、上層透明導電性塗膜層中の含有量が８６〜９９重量％の範囲になるようにバインダ溶液中に添加して、分散させる。上記導電性酸化物粒子のうち、酸化亜鉛、アルミニウム置換酸化亜鉛、ガリウム置換酸化亜鉛、フッ素置換酸化スズ、アンチモン置換酸化スズ、スズ含有酸化インジウム、アルミニウム置換スズ含有酸化インジウム、亜鉛含有酸化インジウム、スズ亜鉛含有酸化インジウム、および、これらに元素置換あるいは、酸化珪素や酸化アルミニウム等による表面処理を施した導電性酸化物粒子がより好ましい。中でもアルミニウム置換スズ含有酸化インジウムは、高い導電性と透明性が得られやすいため特に好ましい。
(Preparation of paint for upper transparent conductive coating layer)
The conductive oxide particles containing one or two or more elements selected from aluminum, tin, indium, zinc, fluorine, gallium, antimony, silicon, etc. have a content of 86 to 86 in the upper transparent conductive coating layer. It is added and dispersed in the binder solution so as to be in the range of 99% by weight. Among the above conductive oxide particles, zinc oxide, aluminum-substituted zinc oxide, gallium-substituted zinc oxide, fluorine-substituted tin oxide, antimony-substituted tin oxide, tin-containing indium oxide, aluminum-substituted tin-containing indium oxide, zinc-containing indium oxide, tin Zinc-containing indium oxide, and conductive oxide particles obtained by subjecting them to element substitution or surface treatment with silicon oxide, aluminum oxide or the like are more preferable. Among these, aluminum-substituted tin-containing indium oxide is particularly preferable because high conductivity and transparency are easily obtained.
上記含有量が８６重量％より小さい場合には、透明性は良好であるが導電性粒子の充填率が低く、プレス処理等を施した際に、バインダ成分の割合が大きいために導電性粒子が高密度になりにくく、高い導電性を得にくい。また含有量が９９重量％より多い場合には、バインダが少ないため、導電性粒子を均一に分散することが困難になるため好ましくない。したがって上記無機粒子の含有率は、８６〜９９重量％が好ましく、より好ましくは９０〜９８重量％の範囲である。 When the content is less than 86% by weight, the transparency is good, but the filling rate of the conductive particles is low, and when the press treatment or the like is performed, the conductive particles are contained because the ratio of the binder component is large. It is difficult to obtain high density and high conductivity. On the other hand, when the content is more than 99% by weight, it is not preferable because the binder is small and it becomes difficult to uniformly disperse the conductive particles. Therefore, the content of the inorganic particles is preferably 86 to 99% by weight, and more preferably 90 to 98% by weight.
上記無機粒子および導電性酸化物粒子を分散させるバインダとしては、特に限定されるものではないが、例えば、塩化ビニル樹脂、アクリル樹脂、塩化ビニル−酢酸ビニル共重合体、塩化ビニル−ビニルアルコール共重合体、塩化ビニル−酢酸ビニル−無水マレイン酸共重合体、塩化ビニル−水酸基含有アルキルアクリレート共重合体、ニトロセルロース、ポリエステル樹脂、ポリウレタン樹脂などがあり、これらの中から、１種または２種以上が組み合わせて用いられる。とくに、アクリル樹脂は、光学特性と分散性の良好な樹脂として好ましく使用される。ポリウレタン樹脂としては、例えば、ポリエステルポリウレタン、ポリエーテルポリウレタン、ポリエーテルポリエステルポリウレタン、ポリカーボネートポリウレタン、ポリエステルポリカーボネートポリウレタンなどが挙げられる。 The binder for dispersing the inorganic particles and the conductive oxide particles is not particularly limited, and examples thereof include vinyl chloride resin, acrylic resin, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl alcohol copolymer. There are a combination, a vinyl chloride-vinyl acetate-maleic anhydride copolymer, a vinyl chloride-hydroxyl group-containing alkyl acrylate copolymer, a nitrocellulose, a polyester resin, a polyurethane resin, and the like. Used in combination. In particular, an acrylic resin is preferably used as a resin having good optical properties and dispersibility. Examples of the polyurethane resin include polyester polyurethane, polyether polyurethane, polyether polyester polyurethane, polycarbonate polyurethane, and polyester polycarbonate polyurethane.
また、無機粒子および導電性酸化物粒子の分散性を向上するための分散剤を添加することもできる。このような分散剤としては、従来から公知のものをいずれも使用することができる。 Further, a dispersant for improving the dispersibility of the inorganic particles and the conductive oxide particles can be added. As such a dispersant, any conventionally known dispersant can be used.
本発明において、透明導電性塗膜を形成するための透明基板としては、特に限定されるものではなく、従来から使用されている基板あるいは基材をすべて使用できる。具体的には、ポリエチレンテレフタレート、ポリエチレンナフタレートなどのポリエステル類、ポリオレフィン類、セルローストリアセテート、ポリカーボネート、ポリアミド、ポリイミド、ポリアミドイミド、ポリスルフオン、アラミド、芳香族ポリアミドなどからなる、厚さが通常３〜３００μｍのフィルムまたはシートが用いられる。また基板は、特にフレキシブルである必要はなく、ガラス板のような硬質の基板も使用できる。 In the present invention, the transparent substrate for forming the transparent conductive coating film is not particularly limited, and any conventionally used substrate or base material can be used. Specifically, polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins, cellulose triacetate, polycarbonate, polyamide, polyimide, polyamideimide, polysulfone, aramid, aromatic polyamide, etc., and usually having a thickness of 3 to 300 μm A film or sheet is used. The substrate need not be particularly flexible, and a hard substrate such as a glass plate can also be used.
なお、これらの基板には、酸化防止剤、難燃剤、耐熱防止剤、紫外線吸収剤、易滑剤、帯電防止剤等の添加剤が添加されていてもよい。さらに、膜の密着性を向上させるために、基板表面に易接着層（プライマー）を設けたり、またはコロナ処理、プラズマ処理などの公知の表面処理を行っても良い。 These substrates may contain additives such as antioxidants, flame retardants, heat resistance inhibitors, ultraviolet absorbers, lubricants and antistatic agents. Furthermore, in order to improve the adhesion of the film, an easy adhesion layer (primer) may be provided on the substrate surface, or a known surface treatment such as corona treatment or plasma treatment may be performed.
下層透明塗膜層用塗料（無機粒子分散塗料）および上層透明導電性塗膜層用塗料（導電性酸化物粒子分散塗料）の調製に用いる有機溶剤には、ベンゼン、トルエン、キシレンなどの芳香族系溶剤、アセトン、シクロヘキサノン、メチルエチルケトン、メチルイソブチルケトンなどのケトン系溶剤、酢酸エチル、酢酸ブチルなどの酢酸エステル系溶剤、ジメチルカーボネート、ジエチルカーボネートなどの炭酸エステル系溶剤、エタノール、イソプロパノールなどのアルコ―ル系溶剤のほか、ヘキサン、テトラヒドロフラン、ジメチルホルムアミドなどが挙げられる。 Organic solvents used for the preparation of the lower transparent coating layer coating (inorganic particle dispersion coating) and the upper transparent conductive coating layer coating (conductive oxide particle dispersion coating) include aromatics such as benzene, toluene and xylene. Solvents, acetone solvents, cyclohexanone, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, acetate solvents such as ethyl acetate and butyl acetate, carbonate solvents such as dimethyl carbonate and diethyl carbonate, alcohols such as ethanol and isopropanol In addition to the system solvents, hexane, tetrahydrofuran, dimethylformamide and the like can be mentioned.
（下層透明塗膜層の作製）
まず第一に、上記の方法により作製した下層透明塗膜層用塗料を、基板上に塗布する。塗布方法は、特に限定されるものではないが、例えばダイコーター、バーコーター、アプリケータ、スクリーン塗布、グラビア塗布、マイクログラビア塗布、スライド塗布、カーテン塗布などにより塗布される。
(Preparation of lower transparent coating layer)
First of all, the coating material for the lower transparent coating layer prepared by the above method is applied on the substrate. The coating method is not particularly limited, and for example, it is applied by die coater, bar coater, applicator, screen coating, gravure coating, micro gravure coating, slide coating, curtain coating or the like.
塗布により形成される下層透明塗膜層の厚さは、特に限定されるものではないが、なるべく高い透明性を示し、かつ上層に塗布される透明導電性塗膜層の粒子が効率的に埋め込まれるようにするために、カレンダ処理あるいはプレス処理（以下、「プレス処理等」あるいは単に「プレス処理」ともいう）前の乾燥後の厚さが0.５〜１０μｍになるように設定する。塗膜層の厚さが0.５μｍ以下では、透明性の面では問題ないが、上層透明導電性塗膜層の導電性粒子が均一に高密度化されにくくなる。塗膜厚さが１０μｍ以上でも特に問題はないが、さらに上層塗膜を塗布することなどから、高い透明性を示すことが難しくなり、また、塗料を多量に使用することとなり、メリットがない。したがって無機粒子を含む下層透明塗膜層は、プレス処理等を施す前の段階において、0.５〜２０μｍが好ましく、１〜１０μｍがより好ましい。プレス処理等を施した後の下層透明塗膜層の厚さは0.５〜１０μｍが好ましく、１〜５μｍがより好ましい。 The thickness of the lower transparent coating layer formed by coating is not particularly limited, but exhibits as high transparency as possible, and the particles of the transparent conductive coating layer applied to the upper layer are efficiently embedded. In order to achieve this, the thickness after drying prior to calendaring or pressing (hereinafter also referred to as “pressing or the like” or simply “pressing”) is set to 0.5 to 10 μm. When the thickness of the coating layer is 0.5 μm or less, there is no problem in terms of transparency, but the conductive particles of the upper transparent conductive coating layer are difficult to be uniformly densified. Even if the coating thickness is 10 μm or more, there is no particular problem. However, since an upper coating film is applied, it becomes difficult to show high transparency, and a large amount of paint is used, which is not advantageous. Therefore, the lower transparent coating film layer containing inorganic particles is preferably 0.5 to 20 μm and more preferably 1 to 10 μm in the stage before press treatment or the like. 0.5-10 micrometers is preferable and, as for the thickness of the lower layer transparent coating film layer after giving a press process etc., 1-5 micrometers is more preferable.
下層透明塗膜層は二層以上の多層膜であっても良い。例えば、屈折率や紫外線透過率、赤外線透過率等において、異なる光学特性を持つ層を何層かに塗り分け、最上層に透明導電性塗膜層を形成しても良い。この場合でも、下層透明塗膜層および上層透明導電性塗膜層を含む透明導電性塗膜のプレス後の総膜厚が0.５〜１０μｍになるように設定することが好ましいが、特に透明性が損なわれなければ、光学特性等の効果を高めるために、１０μｍ以上であってもかまわない。 The lower transparent coating layer may be a multilayer film of two or more layers. For example, a layer having different optical characteristics in refractive index, ultraviolet transmittance, infrared transmittance, etc. may be applied to several layers, and a transparent conductive coating layer may be formed as the uppermost layer. Even in this case, it is preferable to set the total film thickness after pressing of the transparent conductive coating film including the lower transparent coating film layer and the upper transparent conductive coating layer to be 0.5 to 10 μm. If the properties are not impaired, the thickness may be 10 μm or more in order to enhance the effects such as optical characteristics.
（上層透明導電性塗膜層の作製）
上記の上層透明導電性塗膜層用塗料を、上述した下層透明塗膜層上に塗布する。塗布方法は、特に限定されるものではないが、例えばダイコーター、バーコーター、アプリケータ、スクリーン塗布、グラビア塗布、マイクログラビア塗布、スライド塗布、カーテン塗布などにより塗布される。
(Preparation of upper transparent conductive coating layer)
The coating material for the upper transparent conductive coating layer is applied on the lower transparent coating layer described above. The coating method is not particularly limited, and for example, it is applied by die coater, bar coater, applicator, screen coating, gravure coating, micro gravure coating, slide coating, curtain coating or the like.
このような塗布により形成される上層透明導電性塗膜層の厚さは、プレス処理等の効果が現れる範囲とし、かつ高い導電性を得るために、プレス処理前の乾燥後の厚さが0.５〜６μｍになるように設定する。塗膜の厚さが0.５μｍ以下でも、プレス処理等の効果は透明導電性塗膜層全体に及び、かつ透明性の面でも問題はないが、高い導電性が得られにくくなる。また塗膜厚さが６μｍを超えると、塗膜全体にプレス処理等の効果が現われにくく、含有されている導電性酸化物粒子全てが高密度化されにくく、かつ高い透明性が得られにくくなるため好ましくない。したがって導電性酸化物粒子を含む上層透明導電性塗膜層は、プレス処理等を施す前の段階において、0.５〜１２μｍが好ましく、１〜１０μｍがより好ましい。プレス処理等を施した後の上層透明導電性塗膜層の厚さは0.５〜６μｍが好ましく、１〜５μｍがより好ましい。 The thickness of the upper transparent conductive coating layer formed by such coating is in a range where the effect of press treatment or the like appears, and in order to obtain high conductivity, the thickness after drying before press treatment is 0 It sets so that it may become 0.5-6 micrometers. Even when the thickness of the coating film is 0.5 μm or less, the effect of the press treatment or the like extends to the entire transparent conductive coating film layer, and there is no problem in terms of transparency, but it becomes difficult to obtain high conductivity. If the coating thickness exceeds 6 μm, the effect of press treatment or the like hardly appears on the entire coating film, and all the conductive oxide particles contained therein are difficult to be densified, and high transparency is difficult to obtain. Therefore, it is not preferable. Therefore, the upper transparent conductive coating layer containing conductive oxide particles is preferably 0.5 to 12 μm, more preferably 1 to 10 μm, in a stage before press treatment or the like. 0.5-6 micrometers is preferable and, as for the thickness of the upper-layer transparent conductive coating film layer after giving a press process etc., 1-5 micrometers is more preferable.
作製した透明導電性塗膜に対してプレス加工処理やカレンダ処理をすることにより、導電性酸化物粒子が高充填化され、その結果、上層透明導電性塗膜層中の平均空孔率が減少し、膜の導電性、光学特性が向上する。光学特性においては、特に粒子間空隙による散乱光が減少することにより、光散乱強度を表す値であるヘイズ値が著しく減少し、透明性の高いものとなる。 By applying press processing and calendering to the transparent conductive coating film produced, the conductive oxide particles are highly filled, resulting in a decrease in the average porosity in the upper transparent conductive coating layer. In addition, the conductivity and optical characteristics of the film are improved. In the optical characteristics, the haze value, which is a value representing the light scattering intensity, is remarkably reduced by reducing the scattered light due to the interparticle voids in particular, and the transparency becomes high.
カレンダ処理する場合は、処理速度１〜３０ｍ／分、熱処理温度は、上記バインダを構成している樹脂のガラス転移温度（Ｔｇ）に対し、Ｔｇ±５０℃の範囲内、加圧条件は面圧力9.８×１０4 〜9.８×１０6 Ｐａ（１〜１００kg／cm2 ）の範囲内が有効である。また、プレス処理する場合は、熱処理温度は、上記バインダを構成している樹脂のガラス転移温度（Ｔｇ）に対し、Ｔｇ±５０℃の範囲内、加圧条件は面圧力9.８×１０4 〜9.８×１０6 Ｐａ（１〜１００kg／cm2 ）の範囲内が有効である。 When calendering is performed, the processing speed is 1 to 30 m / min, the heat treatment temperature is within the range of Tg ± 50 ° C. with respect to the glass transition temperature (Tg) of the resin constituting the binder, and the pressing condition is the surface pressure. A range of 9.8 × 10 4 to 9.8 × 10 6 Pa (1 to 100 kg / cm 2 ) is effective. When the press treatment is performed, the heat treatment temperature is within a range of Tg ± 50 ° C. with respect to the glass transition temperature (Tg) of the resin constituting the binder, and the pressing condition is a surface pressure of 9.8 × 10 4. The range of ˜9.8 × 10 6 Pa (1 to 100 kg / cm 2 ) is effective.
［実施例］
以下、本発明の実施例について説明する。なお、以下の例では、塗膜層、塗膜および導電性シートの名称に「透明」や「導電性」の語を付したが、これは実施例・比較例間で対応する各部を比較しやすくするためである。したがって、必ずしも高い透明性や導電性を有していることを意味するものではない。得られた透明導電性シートの透明性および導電性のレベルは、後述する全光透過率および表面抵抗率によってそれぞれ定量的に示される（表１等参照）。また、以下に述べる実施例のうち、実施例１０、実施例１３、実施例１４および実施例１５は、厳密には本発明の実施例ではなく、参考例として記載したものである（表１においても同様）。
[Example]
Examples of the present invention will be described below. In the following examples, the words “transparent” and “conductive” are added to the names of the coating layer, the coating film, and the conductive sheet. This compares the corresponding parts between the examples and comparative examples. This is to make it easier. Therefore, it does not necessarily mean that it has high transparency and conductivity. The transparency and conductivity level of the obtained transparent conductive sheet are quantitatively shown by the total light transmittance and the surface resistivity described later (see Table 1 etc.). Of the examples described below, Examples 10, 13, 14, and 15 are not strictly examples of the present invention, but are described as reference examples (in Table 1). The same).
〈下層透明塗膜層〉
水熱合成法で作製した平均粒子径５０ｎｍの板状の水酸化酸化アルミニウム（ベーマイト）微粒子を用いて、下記塗料成分を攪拌、混合した後、直径0.３mmのジルコニアビーズを加え、ペイントシェイカー（東洋精機社製）を用いて２０分間分散させて下層透明塗膜層用塗料を調整した。この塗料は、固形分濃度が４０重量％であり、固形分中の水酸化酸化アルミニウム粒子濃度が８０重量％である。この塗料を、透明基板としての厚さが１００μｍのポリエチレンテレフタレート製フィルム（ＰＥＴフイルム）上に、マイクログラビアコーター（康井精機社製）を用いて塗布し、下層透明塗膜層を作製した。この層の乾燥後の厚さは、3.２μｍであった。
・水酸化酸化アルミニウム粒子 ８０部
・アクリル樹脂（三菱レーヨン社製ＢＲ１１３） ２０部
・メチルエチルケトン ７５部
・トルエン ７５部
<Lower transparent coating layer>
Using the plate-like aluminum hydroxide oxide (boehmite) fine particles having an average particle diameter of 50 nm prepared by the hydrothermal synthesis method, the following paint components were stirred and mixed, and then zirconia beads having a diameter of 0.3 mm were added, and a paint shaker ( Toyo Seiki Co., Ltd.) was used for dispersion for 20 minutes to prepare a coating for the lower transparent coating layer. This coating material has a solid content concentration of 40% by weight and an aluminum hydroxide oxide particle concentration in the solid content of 80% by weight. This paint was applied onto a polyethylene terephthalate film (PET film) having a thickness of 100 μm as a transparent substrate using a micro gravure coater (manufactured by Yasui Seiki Co., Ltd.) to prepare a lower transparent coating film layer. The thickness of this layer after drying was 3.2 μm.
・ Aluminum
〈上層透明導電性塗膜層〉
次に、水熱合成法で作製した平均粒子径が約５０ｎｍのアルミニウム置換スズ含有酸化インジウム粒子（Ａｌ置換ＩＴＯ粒子）を用いて、下記塗料成分を攪拌、混合した後、直径0.３mmのジルコニアビーズを加え、ペイントシェイカーを用いて２５分間分散させて上層透明導電性塗膜層用塗料を調整した。この塗料は、固形分濃度が４０重量％であり、固形分中の水酸化酸化アルミニウム粒子濃度が９５重量％である。この塗料を上記の下層透明塗膜層上に、上記と同様のマイクログラビアコーターを用いて塗布し、上層透明導電性塗膜層を作製した。この層と先の下層透明塗膜層とを合わせた透明導電性塗膜の乾燥後の総膜厚は、7.３μｍであり、このうち上層透明導電性塗膜層の厚さは4.１μｍであった。
・アルミニウム置換スズ含有酸化インジウム粒子 ９５部
・アクリル樹脂（三菱レーヨン社製ＢＲ１１３） ５部
・メチルエチルケトン ７５部
・トルエン ７５部
<Upper transparent conductive coating layer>
Next, the following coating components were stirred and mixed using aluminum-substituted tin-containing indium oxide particles (Al-substituted ITO particles) having an average particle diameter of about 50 nm prepared by a hydrothermal synthesis method, and then zirconia having a diameter of 0.3 mm. The beads were added and dispersed for 25 minutes using a paint shaker to prepare a coating for the upper transparent conductive coating layer. This coating material has a solid concentration of 40% by weight and an aluminum hydroxide oxide particle concentration in the solid content of 95% by weight. This paint was applied onto the lower transparent coating layer using the same microgravure coater as described above to produce an upper transparent conductive coating layer. The total film thickness after drying of the transparent conductive coating film combining this layer and the previous lower transparent coating film layer is 7.3 μm, of which the upper transparent conductive coating film thickness is 4.1 μm. Met.
・ 95 parts of aluminum substituted tin-containing indium oxide particles ・ 5 parts of acrylic resin (Mitsubishi Rayon BR113) ・ 75 parts of methyl ethyl ketone ・ 75 parts of toluene
〈カレンダ処理〉
以上の塗膜について、５段メタルカレンダ機（康井精機社製）を用いてカレンダ処理を行うことにより、表面に透明導電性塗膜を有する導電性シートを作製した。カレンダ処理の条件は、温度１００℃、面圧力１００×9.８×１０4 Ｐａ（１００kg／cm2 ）、処理時間１０分とした。カレンダ処理後の透明導電性塗膜の厚さは、4.４μｍであった。
<Calendar processing>
About the above-mentioned coating film, the conductive sheet which has a transparent conductive coating film on the surface was produced by performing a calendar process using a 5-stage metal calendar machine (made by Yasui Seiki Co., Ltd.). The conditions for the calendar treatment were a temperature of 100 ° C., a surface pressure of 100 × 9.8 × 10 4 Pa (100 kg / cm 2 ), and a treatment time of 10 minutes. The thickness of the transparent conductive coating film after the calendar process was 4.4 μm.
実施例１の導電性シートの作製法において、乾燥後の上層透明導電性塗膜層の膜厚を2.９μｍとし、透明導電性塗膜の総膜厚を4.４μｍとした以外は、実施例１と同様にしてカレンダ処理を施し、透明導電性シートを作製した。カレンダ後の透明導電性塗膜の厚さは、3.４μｍであった。図２に、作製した透明導電性塗膜のカレンダ処理前の断面ＳＥＭ写真を示し、図３に、透明導電性塗膜のカレンダ処理後の断面ＳＥＭ写真を示す。 In the production method of the conductive sheet of Example 1, except that the thickness of the upper transparent conductive coating layer after drying was 2.9 μm and the total thickness of the transparent conductive coating layer was 4.4 μm. In the same manner as in Example 1, calendar treatment was performed to produce a transparent conductive sheet. The thickness of the transparent conductive coating film after calendar was 3.4 μm. FIG. 2 shows a cross-sectional SEM photograph of the produced transparent conductive coating film before calendaring, and FIG. 3 shows a cross-sectional SEM photograph of the transparent conductive coating coating after calendar processing.
実施例１の導電性シートの作製法において、乾燥後の下層透明塗膜層の膜厚を6.４μｍ、上層透明導電性塗膜層の膜厚を2.３μｍ、透明導電性塗膜の総膜厚を8.７μｍとした以外は、実施例１と同様にしてカレンダ処理を施し、透明導電性シートを作製した。カレンダ後の透明導電性塗膜の厚さは、5.５μｍであった。 In the method for producing the conductive sheet of Example 1, the film thickness of the lower transparent coating film layer after drying was 6.4 μm, the film thickness of the upper transparent conductive coating layer was 2.3 μm, and the total thickness of the transparent conductive coating film Except that the film thickness was 8.7 μm, the calendar treatment was performed in the same manner as in Example 1 to produce a transparent conductive sheet. The thickness of the transparent conductive coating film after calendar was 5.5 μm.
実施例１の導電性シートの作製法において、乾燥後の下層透明塗膜層の膜厚を6.４μｍ、上層透明導電性塗膜層の膜厚を1.１μｍ、透明導電性塗膜の総膜厚を7.５μｍとした以外は、実施例１と同様にしてカレンダ処理を施し、透明導電性シートを作製した。カレンダ後の透明導電性塗膜の厚さは、3.８μｍであった。 In the method for producing the conductive sheet of Example 1, the thickness of the lower transparent coating film layer after drying was 6.4 μm, the thickness of the upper transparent conductive coating layer was 1.1 μm, and the total thickness of the transparent conductive coating film Except that the film thickness was 7.5 μm, the calendar treatment was performed in the same manner as in Example 1 to produce a transparent conductive sheet. The thickness of the transparent conductive coating film after calendar was 3.8 μm.
実施例１において、アルミニウム置換スズ含有酸化インジウム粒子、アクリル樹脂の添加量を、それぞれ９７部、３部に変更した以外は、実施例１と同様にして上層透明導電性塗膜層用塗料を作製し、乾燥後の厚さ3.２μｍの下層透明塗膜層上に上層透明導電性塗膜層を作製した。上層透明導電性塗膜層の乾燥後の厚さは2.１μｍであり、透明導電性塗膜の総膜厚は5.３μｍであった。この透明導電性塗膜について、実施例１と同様にカレンダ処理を施し、透明導電性シートを作製した。カレンダ後の透明導電性塗膜の厚さは、3.５μｍであった。 In Example 1, except that the addition amounts of aluminum-substituted tin-containing indium oxide particles and acrylic resin were changed to 97 parts and 3 parts, respectively, a coating for an upper transparent conductive coating layer was produced in the same manner as in Example 1. Then, an upper transparent conductive coating layer was formed on the lower transparent coating layer having a thickness of 3.2 μm after drying. The thickness of the upper transparent conductive coating layer after drying was 2.1 μm, and the total thickness of the transparent conductive coating layer was 5.3 μm. About this transparent conductive coating film, the calendar process was performed similarly to Example 1, and the transparent conductive sheet was produced. The thickness of the transparent conductive coating film after calendar was 3.5 μm.
実施例１において、アルミニウム置換スズ含有酸化インジウム粒子、アクリル樹脂の添加量を、それぞれ９０部、１０部とした以外は、実施例１と同様にして上層透明導電性塗膜層用塗料を作製し、乾燥後の厚さ3.２μｍの下層透明塗膜層上に上層透明導電性塗膜層を作製した。乾燥後の上層透明導電性塗膜層の厚さは2.４μｍであり、透明導電性塗膜の総膜厚は5.６μｍであった。この透明導電性塗膜について、実施例１と同様にカレンダ処理を施し、透明導電性シートを作製した。カレンダ後の透明導電性塗膜の厚さは、3.７μｍであった。 In Example 1, except that the addition amounts of the aluminum-substituted tin-containing indium oxide particles and the acrylic resin were 90 parts and 10 parts, respectively, an upper transparent conductive coating layer coating was prepared in the same manner as in Example 1. Then, an upper transparent conductive coating layer was formed on the lower transparent coating layer having a thickness of 3.2 μm after drying. The thickness of the upper transparent conductive coating layer after drying was 2.4 μm, and the total thickness of the transparent conductive coating layer was 5.6 μm. About this transparent conductive coating film, the calendar process was performed similarly to Example 1, and the transparent conductive sheet was produced. The thickness of the transparent conductive coating film after calendar was 3.7 μm.
実施例１において、下層透明塗膜層に用いる水酸化酸化アルミニウム粒子を、水熱合成法で作製した平均粒子径３０ｎｍの板状の酸化珪素に変更した以外は、実施例１と同様にして下層透明塗膜層用塗料を作製し、乾燥後の厚さ3.１μｍの下層透明塗膜層上に透明導電性塗膜層を作製した。乾燥後の透明導電性塗膜層の厚さは4.１μｍであり、透明導電性塗膜の総膜厚は7.２μｍであった。この透明導電性塗膜について、実施例１と同様にカレンダ処理を施し、透明導電性シートを作製した。カレンダ後の透明導電性塗膜の厚さは、4.２μｍであった。 In Example 1, except that the aluminum hydroxide oxide particles used for the lower transparent coating layer were changed to plate-like silicon oxide having an average particle diameter of 30 nm prepared by a hydrothermal synthesis method, the lower layer was the same as in Example 1. A coating for a transparent coating layer was prepared, and a transparent conductive coating layer was prepared on the lower transparent coating layer having a thickness of 3.1 μm after drying. The thickness of the transparent conductive coating layer after drying was 4.1 μm, and the total thickness of the transparent conductive coating layer was 7.2 μm. About this transparent conductive coating film, the calendar process was performed similarly to Example 1, and the transparent conductive sheet was produced. The thickness of the transparent conductive coating film after calendar was 4.2 μm.
実施例１において、下層透明塗膜層に用いる水酸化酸化アルミニウム粒子を、水熱合成法で作製した、平均粒子径６０ｎｍの四角板状形状を有するスズ含有酸化インジウム粒子に変更した以外は、実施例１と同様にして下層透明塗膜層用塗料を作製し、乾燥後の厚さ2.２μｍの下層透明塗膜層を作製した。この下層透明塗膜層上に実施例１と同様にして上層透明導電性塗膜層を作製した。乾燥後の上層透明導電性塗膜層の厚さは2.１μｍであり、透明導電性塗膜の総膜厚は4.３μｍであった。この透明導電性塗膜について、実施例１と同様にカレンダ処理を施し、透明導電性シートを作製した。カレンダ後の透明導電性塗膜の厚さは、3.１μｍであった。 In Example 1, except that the aluminum hydroxide oxide particles used for the lower transparent coating layer were changed to tin-containing indium oxide particles having a square plate shape with an average particle diameter of 60 nm prepared by a hydrothermal synthesis method. In the same manner as in Example 1, a coating material for the lower transparent coating layer was prepared, and a lower transparent coating layer having a thickness of 2.2 μm after drying was prepared. An upper transparent conductive coating layer was prepared on the lower transparent coating layer in the same manner as in Example 1. The thickness of the upper transparent conductive coating layer after drying was 2.1 μm, and the total thickness of the transparent conductive coating layer was 4.3 μm. About this transparent conductive coating film, the calendar process was performed similarly to Example 1, and the transparent conductive sheet was produced. The thickness of the transparent conductive coating film after calendar was 3.1 μm.
実施例１において、下層透明塗膜層に用いる水酸化酸化アルミニウム粒子を、粒子径１０〜３０ｎｍの球状のコロイダルシリカ（日産化学工業（株) 製 ＭＩＢＫ−ＳＴ）に変更した以外は、実施例１と同様にして下層透明塗膜層用塗料を作製し、乾燥後の厚さ2.１μｍの下層透明塗膜層を作製し、さらにその上に上層透明導電性塗膜層を作製した。乾燥後の上層透明導電性塗膜の厚さは2.１μｍであり、透明導電性塗膜の総膜厚は、4.２μｍであった。この透明導電性塗膜について、実施例１と同様にカレンダ処理を施し、透明導電性シートを作製した。カレンダ後の透明導電性塗膜の厚さは、3.１μｍであった。 In Example 1, except that the aluminum hydroxide oxide particles used in the lower transparent coating layer were changed to spherical colloidal silica (MIBK-ST manufactured by Nissan Chemical Industries, Ltd.) having a particle size of 10 to 30 nm. In the same manner as above, a coating material for a lower transparent coating film layer was prepared, a lower transparent coating film layer having a thickness of 2.1 μm after drying was prepared, and an upper transparent conductive coating film layer was further formed thereon. The thickness of the upper transparent conductive coating film after drying was 2.1 μm, and the total film thickness of the transparent conductive coating film was 4.2 μm. About this transparent conductive coating film, the calendar process was performed similarly to Example 1, and the transparent conductive sheet was produced. The thickness of the transparent conductive coating film after calendar was 3.1 μm.
実施例９において、下層透明塗膜層と上層透明導電性塗膜層とをスライド塗布（同時重層塗布）により作製した後、乾燥することにより、透明導電性塗膜を作製した。乾燥後の上層透明導電性塗膜層の厚さは2.９μｍであり、透明導電性塗膜の総膜厚は、5.６μｍであった。この透明導電性塗膜について、実施例１と同様にカレンダ処理を施し、透明導電性シートを作製した。カレンダ後の透明導電性塗膜の厚さは、4.２μｍであった。同時重層塗布により作製した上層透明導電性塗膜層および下層透明塗膜層のそれぞれの厚さは、断面ＳＥＭ写真より、任意の１０視野の厚みを測定し、それらの平均とした。 In Example 9, the lower transparent coating film layer and the upper transparent conductive coating film layer were prepared by slide coating (simultaneous multilayer coating) and then dried to prepare a transparent conductive coating film. The thickness of the upper transparent conductive coating layer after drying was 2.9 μm, and the total thickness of the transparent conductive coating layer was 5.6 μm. About this transparent conductive coating film, the calendar process was performed similarly to Example 1, and the transparent conductive sheet was produced. The thickness of the transparent conductive coating film after calendar was 4.2 μm. The thicknesses of the upper transparent conductive coating layer and the lower transparent coating layer produced by simultaneous multilayer coating were measured from the cross-sectional SEM photographs, and the thicknesses of arbitrary 10 fields were averaged.
実施例１おいて、上層透明導電性塗膜層に用いる導電性微粒子を一次粒子径が５０ｎｍのＡｌドープＺｎＯ（ＡＺＯ）に変更した以外は、実施例１と同様にして上層透明導電性塗膜層用塗料を作製し、乾燥後の厚さ4.１μｍの下層透明塗膜層上に上層透明導電性塗膜層を作製した。カレンダ処理前の透明導電性塗膜の総膜厚は、7.３μｍであった。この透明導電性塗膜について、実施例１と同様にカレンダ処理を施し、透明導電性シートを作製した。カレンダ後の透明導電性塗膜の厚さは、4.４μｍであった。 In Example 1, except that the conductive fine particles used for the upper transparent conductive coating layer were changed to Al-doped ZnO (AZO) having a primary particle diameter of 50 nm, the same procedure as in Example 1 was repeated. A layer coating was prepared, and an upper transparent conductive coating layer was formed on the lower transparent coating layer having a thickness of 4.1 μm after drying. The total film thickness of the transparent conductive coating film before calendaring was 7.3 μm. About this transparent conductive coating film, the calendar process was performed similarly to Example 1, and the transparent conductive sheet was produced. The thickness of the transparent conductive coating film after calendar was 4.4 μm.
実施例１に示す下層膜の作製方法のうち、水酸化酸化アルミニウム粒子を平均粒子径７０ｎｍの酸化亜鉛粒子に変更した以外は、実施例１と同様にして、下層塗膜を作製した。この膜厚は4.４μｍだった。さらに、この下層塗膜の上に、実施例１に示す水酸化酸化アルミニウムの塗料を用い、厚さ4.５μｍの中間層を作製した。その後、最上層に実施例１と同様に作製した導電性塗料を塗布した。最上層の導電性膜の厚さは3.３μｍであり、総膜厚は、１2.２μｍであった。この塗布膜について、実施例１と同様にカレンダ処理を施し、透明導電性シートを作製した。カレンダ後の塗膜の厚さは、9.８μｍであった。 The lower layer coating film was produced like Example 1 except having changed the aluminum hydroxide oxide particle to the zinc oxide particle with an average particle diameter of 70 nm among the preparation methods of the lower layer film shown in Example 1. FIG. This film thickness was 4.4 μm. Furthermore, an intermediate layer having a thickness of 4.5 μm was formed on the lower coating film using the aluminum hydroxide oxide paint shown in Example 1. Then, the conductive paint produced similarly to Example 1 was apply | coated to the uppermost layer. The thickness of the uppermost conductive film was 3.3 μm, and the total film thickness was 12.2 μm. About this coating film, the calendar process was given like Example 1, and the transparent conductive sheet was produced. The thickness of the coating after calendar was 9.8 μm.
実施例１において、水酸化アルミニウム、アクリル樹脂の添加量を、それぞれ４５部、５５部とした以外は、実施例１と同様にして、下層透明塗膜層を作製した後、アルミニウム置換スズ含有酸化インジウム粒子、アクリル樹脂の添加量を、それぞれ８７部、１６部とした上層透明導電性塗膜層用塗料を調整し、これを用いて下層透明塗膜層上に上層透明導電性塗膜層を作製した。乾燥後の上層透明導電性塗膜層の厚さは、2.４μｍであり、透明導電性塗膜の総膜厚は5.６μｍであった。この透明導電性塗膜について、実施例１と同様にカレンダ処理を施し、透明導電性シートを作製した。カレンダ後の透明導電性塗膜の厚さは、3.７μｍであった。 In Example 1, except that the addition amounts of aluminum hydroxide and acrylic resin were changed to 45 parts and 55 parts, respectively, a lower transparent coating layer was prepared in the same manner as in Example 1, and then the aluminum-substituted tin-containing oxidation was performed. An upper transparent conductive coating layer is prepared on the lower transparent coating layer by adjusting the coating material for the upper transparent conductive coating layer with the addition amount of indium particles and acrylic resin being 87 parts and 16 parts, respectively. Produced. The thickness of the upper transparent conductive coating layer after drying was 2.4 μm, and the total thickness of the transparent conductive coating layer was 5.6 μm. About this transparent conductive coating film, the calendar process was performed similarly to Example 1, and the transparent conductive sheet was produced. The thickness of the transparent conductive coating film after calendar was 3.7 μm.
実施例１において、アルミニウム置換スズ含有酸化インジウム粒子、アクリル樹脂の添加量を、それぞれ８４部、１６部とした上層透明導電性塗膜層用塗料を調整し、これを用いて実施例１と同様に下層透明塗膜層上に上層透明導電性塗膜層を作製した。乾燥後の上層透明導電性塗膜層の厚さは、2.４μｍであり、透明導電性塗膜の総膜厚は5.６μｍであった。この透明導電性塗膜について、実施例１と同様にカレンダ処理を施し、透明導電性シートを作製した。カレンダ後の透明導電性塗膜の厚さは、3.７μｍであった。 In Example 1, the coating material for the upper transparent conductive coating layer in which the addition amounts of aluminum-substituted tin-containing indium oxide particles and acrylic resin were 84 parts and 16 parts, respectively, was prepared, and this was used as in Example 1. An upper transparent conductive coating layer was prepared on the lower transparent coating layer. The thickness of the upper transparent conductive coating layer after drying was 2.4 μm, and the total thickness of the transparent conductive coating layer was 5.6 μm. About this transparent conductive coating film, the calendar process was performed similarly to Example 1, and the transparent conductive sheet was produced. The thickness of the transparent conductive coating film after calendar was 3.7 μm.
実施例１において、水酸化酸化アルミニウム、アクリル樹脂の添加量を、それぞれ８２部、１８部とした以外は、実施例１と同様にして、下層透明塗膜層を作製した後、アルミニウム置換スズ含有酸化インジウム粒子、アクリル樹脂の添加量を、それぞれ９５部、５部とした上層透明導電性塗膜層用塗料を調整し、これを用いて下層透明塗膜層上に上層透明導電性塗膜層を作製した。乾燥後の上層透明導電性塗膜層の厚さは、2.５μｍであり、透明導電性塗膜の総膜厚は5.８μｍであった。この透明導電性塗膜について、実施例１と同様にカレンダ処理を施し、透明導電シートを作製した。カレンダ後の透明導電性塗膜の厚さは、4.１μｍであった。 In Example 1, except that the addition amounts of aluminum hydroxide oxide and acrylic resin were changed to 82 parts and 18 parts, respectively, a lower transparent coating layer was prepared in the same manner as in Example 1, and then aluminum-substituted tin-containing An upper transparent conductive coating layer is prepared on the lower transparent coating layer using the coating material for the upper transparent conductive coating layer in which the addition amounts of indium oxide particles and acrylic resin are 95 parts and 5 parts, respectively. Was made. The thickness of the upper transparent conductive coating layer after drying was 2.5 μm, and the total thickness of the transparent conductive coating layer was 5.8 μm. About this transparent conductive coating film, the calendar process was given similarly to Example 1, and the transparent conductive sheet was produced. The thickness of the transparent conductive coating film after calendar was 4.1 μm.
［比較例１］
実施例１において、下層透明塗膜層を作製しなかったことと、アルミニウム置換スズ含有酸化インジウム粒子を用いて透明導電性塗膜層用塗料を調整し、これを用いてＰＥＴフィルムからなる透明基板上に透明導電性塗膜層を作製したこと以外は、実施例１と同様にして透明導電性塗膜を作製した。乾燥後の透明導電性塗膜層つまり透明導電性塗膜の膜厚は、4.３μｍであった。この透明導電性塗膜について、実施例１と同様にしてカレンダ処理を行うことにより、透明導電性シートを作製した。カレンダ処理後の透明導電性塗膜の厚さは、3.４μｍであった。
[Comparative Example 1]
In Example 1, the lower transparent coating film layer was not prepared, and a transparent conductive coating film coating material was prepared using aluminum-substituted tin-containing indium oxide particles. A transparent conductive coating film was prepared in the same manner as in Example 1 except that a transparent conductive coating layer was prepared thereon. The film thickness of the transparent conductive coating layer after drying, that is, the transparent conductive coating layer, was 4.3 μm. About this transparent conductive coating film, it carried out similarly to Example 1, and produced the transparent conductive sheet. The thickness of the transparent conductive coating film after the calendar process was 3.4 μm.
［比較例２］
実施例１において、下層に用いる塗料の、水酸化酸化アルミニウム粒子、アクリル樹脂の添加量を、それぞれ３５部、６５部に変更した以外は、実施例１と同様にして透明導電性塗膜層を作製し、乾燥後の厚さ3.１μｍの下層透明塗膜層上に上層透明導電性塗膜層を作製した。乾燥後の上層透明導電性塗膜層の厚さは2.２μｍであり、透明導電性塗膜の総膜厚は5.３μｍであった。この透明導電性塗膜について、実施例１と同様にカレンダ処理を施し、透明導電性シートを作製したが、作製直後に、光学顕微鏡で観察できる大きさの多数のひび割れを生じた。カレンダ後の透明導電性塗膜の厚さは、3.４μｍであった。
[Comparative Example 2]
In Example 1, the transparent conductive coating film layer was formed in the same manner as in Example 1 except that the addition amount of the aluminum hydroxide oxide particles and the acrylic resin in the paint used for the lower layer was changed to 35 parts and 65 parts, respectively. An upper transparent conductive coating layer was prepared on the lower transparent coating layer having a thickness of 3.1 μm after being prepared and dried. The thickness of the upper transparent conductive coating layer after drying was 2.2 μm, and the total thickness of the transparent conductive coating layer was 5.3 μm. About this transparent conductive coating film, the calendar process was performed similarly to Example 1, and the transparent conductive sheet was produced, However, Immediately after preparation, many cracks of the magnitude | size which can be observed with an optical microscope were produced. The thickness of the transparent conductive coating film after calendar was 3.4 μm.
［比較例３］
実施例１と同様にして透明導電性塗膜を作製した後、カレンダ処理を行なうことなく、透明導電性シートを作製した。透明導電性塗膜の総厚みは、7.３μｍであった。
[Comparative Example 3]
After producing a transparent conductive coating film in the same manner as in Example 1, a transparent conductive sheet was produced without performing a calendar treatment. The total thickness of the transparent conductive coating film was 7.3 μm.
［比較例４］
実施例１において、水酸化酸化アルミニウム粒子の固形分中の含率を４５％に調整した下層透明塗膜層用塗料を用い、実施例１と同様にして透明導電性塗膜を作製した。その後、カレンダ処理を施さず、透明導電シートを作製した。
[Comparative Example 4]
In Example 1, a transparent conductive coating film was produced in the same manner as in Example 1 using the coating for the lower transparent coating film layer in which the content of the aluminum hydroxide oxide particles in the solid content was adjusted to 45%. Thereafter, a calendar process was not performed, and a transparent conductive sheet was produced.
《平均空孔率》
実施例１〜１５、比較例１〜４でそれぞれ得られた透明導電性シートについて、平均空孔率を調べた。平均空孔率は、ＦＩＢ（収束イオンビーム法）により加工された塗膜の断面SEM 写真の塗膜部分に1.５ミクロンを４等分するように厚み方向に線を引き、それぞれの線で通った空孔の割合を測定し、その平均値を平均空孔率とする。平均空孔率が小さいほど、塗膜の空孔が少なく、空孔による散乱光が減少することを示し、透明導電シートとして優れていることを示している。
《Average porosity》
The average porosity was investigated about the transparent conductive sheet each obtained in Examples 1-15 and Comparative Examples 1-4. The average porosity is a cross-sectional SEM photograph of the coating film processed by FIB (focused ion beam method). The ratio of the vacant holes passed is measured, and the average value is defined as the average porosity. The smaller the average porosity, the fewer the pores in the coating film, indicating that the scattered light due to the pores is reduced, indicating that the transparent conductive sheet is excellent.
《全光透過率測定》
実施例１〜１５、比較例１〜４でそれぞれ得られた透明導電性シートについて、全光透過率を調べた。全光透過率は、日本分光製の紫外可視分光光度計を用いて、入射光強度に対する透過光強度の割合を測定した。これらの評価結果を、表１にまとめて示す。表１では、全光透過率の値が大きいほど、透明性が高いことを示しており、透明導電性シートとして優れていることを示している。また、同様の装置を用いて、全光透過率とは別に光の波長による透過率変化を測定した。実施例１および実施例１２の透明導電性シートについて測定した、この可視光域（３５０〜７８０ｎｍ）の透過率スペクトルを図１および図４にそれぞれ示す。
<Measurement of total light transmittance>
The total light transmittance was examined for the transparent conductive sheets obtained in Examples 1 to 15 and Comparative Examples 1 to 4, respectively. The total light transmittance was determined by measuring the ratio of the transmitted light intensity to the incident light intensity using an ultraviolet-visible spectrophotometer manufactured by JASCO. These evaluation results are summarized in Table 1. In Table 1, it shows that transparency is so high that the value of total light transmittance is large, and it has shown that it is excellent as a transparent conductive sheet. Further, using the same apparatus, a change in transmittance due to the wavelength of light was measured separately from the total light transmittance. The transmittance spectra in the visible light region (350 to 780 nm) measured for the transparent conductive sheets of Example 1 and Example 12 are shown in FIGS. 1 and 4, respectively.
《ヘイズ値測定》
実施例１〜１５、比較例１〜４でそれぞれ得られた透明導電性シートについて、ヘイズ値を求めた。ヘイズ値は、日本分光製の紫外可視分光光度計を用いて、ＪＩＳ Ｋ７１０５に規定された方法により測定、算出した。これらの評価結果を、表１にまとめて示す。
《Haze value measurement》
Haze values were determined for the transparent conductive sheets obtained in Examples 1 to 15 and Comparative Examples 1 to 4, respectively. The haze value was measured and calculated by a method defined in JIS K7105 using an ultraviolet-visible spectrophotometer manufactured by JASCO Corporation. These evaluation results are summarized in Table 1.
《表面抵抗率測定》
実施例１〜１５、比較例１〜４でそれぞれ得られた透明導電性シートについて、表面抵抗率を測定した。表面抵抗率は、三菱化学製の抵抗率計ロレスターＧＰを用いて、四端子法により測定した。なお、電圧端子間距離は５mmである。これらの評価結果を、表１にまとめて示す。表１では、表面抵抗率の値が小さいほど、導電性が高いことを示しており、透明導電性シートとして優れていることを示している
<Measurement of surface resistivity>
The surface resistivity of each of the transparent conductive sheets obtained in Examples 1 to 15 and Comparative Examples 1 to 4 was measured. The surface resistivity was measured by a four-terminal method using a resistivity meter Lorester GP manufactured by Mitsubishi Chemical. The distance between the voltage terminals is 5 mm. These evaluation results are summarized in Table 1. Table 1 shows that the smaller the value of the surface resistivity, the higher the conductivity, and the better the transparent conductive sheet.
《剥離試験》
実施例１〜１５、比較例１〜４でそれぞれ得られた透明導電性シートについて、セロテープ（登録商標）剥離試験を行った。この評価結果を表１にまとめて示す。剥離試験は各１０回づつ行い、評価は以下のように定義した。
・１０回中０〜１回剥離：○
・１０回中２〜４回剥離：△
・１０回中５回以上剥離：×
<Peel test>
For the transparent conductive sheets obtained in Examples 1 to 15 and Comparative Examples 1 to 4, a cello tape (registered trademark) peel test was performed. The evaluation results are summarized in Table 1. The peel test was performed 10 times each, and the evaluation was defined as follows.
・ Peeling 0 to 1 out of 10 times: ○
・ 2-10 times peeling out of 10 times: △
・ Peeling 5 times or more out of 10 times: ×
表１から明らかなように、各実施例で得られた重層塗布した透明導電性シートは、各比較例で得られたものに比べて、全光透過性、導電性ともに優れている。 As is clear from Table 1, the multi-layer coated transparent conductive sheet obtained in each example is superior in both total light transmission and conductivity as compared with those obtained in each comparative example.
各実施例では、下層透明塗膜層に上層透明導電性塗膜層の導電性粒子が埋め込まれ、バインダ成分が上層透明導電性塗膜層中に浸透することにより、塗膜強度を保つことができている。一方、比較例１では、充填率の高い透明導電性塗膜を一層で塗布したため、バインダ量が足りず、導電性粒子同士および、粒子と透明基板（基材）であるＰＥＴフィルムとの結合が弱く、簡単に剥離してしまい塗膜強度が弱い。同じ理由で、粒子間空隙による光散乱のため光学特性の低下も見られる。比較例３では、実施例１に示されているカレンダ処理を行わなかったため、比較例１と同様の理由で光学特性が全光透過率６０％と低く、ヘイズ値が５０％と非常に高い値となり、光学フィルムには適さないことがわかる。 In each Example, the conductive particles of the upper transparent conductive coating layer are embedded in the lower transparent coating layer, and the coating strength can be maintained by penetrating the binder component into the upper transparent conductive coating layer. is made of. On the other hand, in Comparative Example 1, since the transparent conductive coating film having a high filling rate was applied in a single layer, the amount of the binder was insufficient, and the bonding between the conductive particles and the particles and the PET film, which was the transparent substrate (base material), occurred. It is weak and easily peels off, resulting in poor coating strength. For the same reason, optical characteristics are also degraded due to light scattering by interparticle voids. In Comparative Example 3, since the calendar process shown in Example 1 was not performed, for the same reason as Comparative Example 1, the optical characteristics were as low as 60% in total light transmittance, and the haze value was as high as 50%. It turns out that it is not suitable for an optical film.
次に、各実施例では、透明導電性塗膜層中の導電性粒子の充填率が高められていることにより、カレンダ処理の効果が最大限に引き出されており、１０００Ω/ □以下、中でも優れたものでは１００Ω/ □以下の高い導電性が現れている。これに対し比較例３では、上層の導電性粒子の充填率が低いため、透明性および塗膜強度の面では問題ないが、カレンダ処理の効果が現れにくく、十分な導電性を実現することができない。 Next, in each example, the filling rate of the conductive particles in the transparent conductive coating layer is increased, so that the effect of the calendar treatment is drawn out to the maximum, and 1000Ω / □ or less, among others, excellent As a result, a high conductivity of 100Ω / □ or less appears. On the other hand, in Comparative Example 3, since the filling rate of the conductive particles in the upper layer is low, there is no problem in terms of transparency and coating strength, but the effect of the calendering treatment is hardly exhibited and sufficient conductivity can be realized. Can not.
また各実施例では、下層に用いる透明塗膜層における無機粒子濃度を適切な範囲に設定したことにより、透明性、導電性に影響を与えず、高い塗膜強度を保つことができているが、比較例２，３は、下層に用いる透明塗膜層における無機粒子濃度が高すぎても低すぎても、優れた特性が現れないことがわかる。比較例３では、無機粒子濃度が高すぎるために透明性が低下し、さらに、塗膜全体としてのバインダ量が減少したために塗膜強度も低下している。次に比較例２では、無機粒子濃度が低すぎるために下層の硬度が増し、上層の透明導電塗膜層が効率的に下層に埋め込まれず、結果、塗膜にひび割れが生じている。このひび割れにより、塗膜強度はもちろん、導電性、透明性も著しく劣化している。 Moreover, in each Example, by setting the inorganic particle concentration in the transparent coating layer used for the lower layer to an appropriate range, it is possible to maintain high coating strength without affecting transparency and conductivity. Comparative Examples 2 and 3 show that excellent properties do not appear even if the inorganic particle concentration in the transparent coating layer used for the lower layer is too high or too low. In Comparative Example 3, the transparency is lowered because the inorganic particle concentration is too high, and the coating strength is also lowered because the amount of the binder as the whole coating is reduced. Next, in Comparative Example 2, since the inorganic particle concentration is too low, the hardness of the lower layer is increased, the upper transparent conductive coating layer is not efficiently embedded in the lower layer, and as a result, the coating film is cracked. Due to this crack, not only the strength of the coating film but also the conductivity and transparency are significantly deteriorated.
またさらに実施例１２では、下層に紫外線吸収能を持つ酸化亜鉛粒子を用い、中間層にベーマイト粒子を用いることにより、上層の導電性粒子による高い導電性を損なうことなく、紫外線遮蔽機能を持たせることができる。このように、下層あるいは中間層に光学的な特徴を持つ粒子を用いることにより、高い導電性と同時に光学的な特徴を持った膜を作製することができる。 Furthermore, in Example 12, by using zinc oxide particles having ultraviolet absorbing ability in the lower layer and using boehmite particles in the intermediate layer, an ultraviolet shielding function is imparted without impairing the high conductivity of the upper conductive particles. be able to. As described above, by using particles having optical characteristics in the lower layer or the intermediate layer, a film having optical characteristics as well as high conductivity can be manufactured.
Claims (5)
前記透明導電性塗膜が、導電性酸化物粒子を含有する上層透明導電性塗膜層と、これよりも透明基板側に位置して無機粒子およびバインダ樹脂を含有する下層透明塗膜層との少なくとも２層を含んでなり、
更に、この透明導電性塗膜は、前記下層透明塗膜層を塗布・乾燥により形成し、その上から前記上層透明導電性塗膜層を塗布・乾燥により形成した後、カレンダ処理を行うことにより前記透明基板上に形成されたものであり、
前記上層透明導電性塗布層を圧縮したとき、該上層透明導電性塗布層における下部側の導電性酸化物粒子がその直下に位置する層に食い込んだ状態となり、該上層透明導電性塗布層の直下に位置する層に食い込んだ導電性酸化物粒子がアンカー効果を発揮するようになっており、
上層透明導電性塗膜層中の導電性酸化物粒子の含有率が８６〜９９重量％であり、
下層透明塗膜層中の無機粒子の含有率が５０〜８０重量％であり、
このうちの上層透明導電性塗膜層の平均空孔率が３０％以下であることを特徴とする透明導電性シート。 A transparent conductive sheet comprising a transparent conductive film on a transparent substrate,
The transparent conductive coating film is composed of an upper transparent conductive coating layer containing conductive oxide particles, and a lower transparent coating layer containing inorganic particles and a binder resin located closer to the transparent substrate than the upper transparent conductive coating layer. Comprising at least two layers,
Furthermore, the transparent conductive coating film is formed by applying and drying the lower transparent coating film layer, forming the upper transparent conductive coating layer by coating and drying, and then performing a calendar treatment. Formed on the transparent substrate,
When the upper transparent conductive coating layer is compressed, the conductive oxide particles on the lower side of the upper transparent conductive coating layer bite into the layer located immediately below, and immediately below the upper transparent conductive coating layer. The conductive oxide particles that have digged into the layer located at the position where the anchor effect is exerted,
The content of the conductive oxide particles in the upper transparent conductive coating layer is 86 to 99% by weight,
The content of inorganic particles in the lower transparent coating layer is 50 to 80% by weight,
Among these, the average porosity of the upper layer transparent conductive coating film layer is 30% or less.
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| JP2004006263A (en) * | 2002-03-25 | 2004-01-08 | Sumitomo Metal Mining Co Ltd | Transparent conductive film, coating liquid for forming this transparent conductive film and transparent conductive laminated structural body and display device |
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| JP2004006263A (en) * | 2002-03-25 | 2004-01-08 | Sumitomo Metal Mining Co Ltd | Transparent conductive film, coating liquid for forming this transparent conductive film and transparent conductive laminated structural body and display device |
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