JP4678097B2 - Conductive film - Google Patents

Description

【００６９】
表１に示されるように、分散値σ１、σ２の比（σ１／σ２）が１．２以上、１．８５以下である透明導電層を備えた本発明の透明導電膜（試料１〜５）は、いずれも、電気抵抗値が充分に低く、かつ、ヘイズも低く十分な透明性を備えることが確認された。また、これらの透明導電膜は、樹脂を含有していないにもかかわらず透明導電層のＰＥＴフィルムに対する密着性も良好であることが確認された。
【００７０】
これに対して、分散値σ１、σ２の比（σ１／σ２）が１．２未満である透明導電層を備えた透明導電膜（試料６、８）は、透明導電層の電気抵抗の値に関係なく透明導電層のＰＥＴフィルムに対する密着性が悪いものであった。
【００７１】
また、分散値σ１、σ２の比（σ１／σ２）が１．２未満である透明導電層を備えた透明導電膜（試料７）は、透明導電層に多量の樹脂が含有されるため、透明導電層のＰＥＴフィルムに対する密着性は良好であるが、透明導電層の電気抵抗が高いものであった。
【００７２】
［実施例２］
まず、平均一次粒径が２０ｎｍのＩＴＯ微粒子（住友金属鉱山（株）製ＳＵＦＰ−ＨＸ）１００重量部に、メタノール３００重量部を加え、メディアをジルコニアビーズとして分散機にて分散して導電性塗料を調製した。
【００７３】
次に、厚み５０μｍのＰＥＴフィルムに、上記の導電性塗液をバーコーターを用いて塗布し５０℃で乾燥した。このようにして得られたフィルムを、以降において、圧縮前ＩＴＯフィルムと称する。これらの圧縮前ＩＴＯフィルムのＩＴＯ含有塗膜の厚みは１．９μｍであった。
【００７４】
次いで、圧縮前ＩＴＯフィルムを金属ロール（ロール表面にハードクロムめっき処理が施されたもの）間に挟み、室温（２３℃）にてロールを回転させ５ｍ／分の送り速度で圧縮した。この圧縮工程における単位面積当たりの圧縮圧力を下記の表２に示すように異なる条件で設定した。このようにＩＴＯフィルムを圧縮することにより、透明導電層を備えた透明導電膜（試料Ａ〜Ｆ）を得た。
【００７５】
また、樹脂として大成化工（株）製のアクリル樹脂溶液ＭＴ４０８−４２（不揮発成分濃度５０％）１００重量部を、メチルエチルケトン／トルエン／シクロヘキサノン（１：１：１）混合溶液４００重量部に溶解した樹脂溶液に、上記と同じＩＴＯ粉末１００重量部を加え、メディアをジルコニアビーズとして分散機にて分散して導電性塗料を調製した。この導電性塗料を用いて上述の透明導電膜（試料Ａ〜Ｆ）と同様にして、透明導電膜（試料Ｇ）を得た。但し、圧縮工程における単位面積当たりの圧縮圧力は、表２に示すものとした。
【００７６】
さらに、透明支持体として、上記のＰＥＴフィルム上に、シリコン樹脂系ハードコート材（ＧＥ・東芝シリコン（株）製トスガード５１０）を３μｍ厚で設けたものを使用した他は、上述の透明導電膜（試料Ｃ：樹脂を用いていない）と同様にして、透明導電膜（試料Ｈ）を得た。
【００７７】
上述のように作製した透明導電膜（試料Ａ〜Ｈ）について、実施例１と同様にして、透明導電層の厚み、分散値σ１、σ２の比（σ１／σ２）、表面電気抵抗値、ヘイズを測定し、結果を下記の表２に示した。また、実施例１と同様に９０°ピール試験を行い、結果を下記の表２に示した。
【００７８】
【表２】

【００７９】
表２に示されるように、分散値σ１、σ２の比（σ１／σ２）が１．２以上、１．８５以下である透明導電層を備えた本発明の透明導電膜（試料Ａ〜Ｅ）は、いずれも、透明導電層の電気抵抗が充分に低く、かつ、ヘイズも低く十分な透明性を備えることが確認された。また、これらの透明導電膜は、樹脂を含有していないにもかかわず透明導電層の透明支持体に対する密着性も良好であることが確認された。
【００８０】
これに対して、分散値σ１、σ２の比（σ１／σ２）が１．２未満である透明導電層を備えた透明導電膜（試料Ｆ、Ｈ）は、透明導電層の透明支持体に対する密着性が悪いものであった。
また、分散値σ１、σ２の比（σ１／σ２）が１．２未満である透明導電層を備えた透明導電膜（試料Ｇ）は、透明導電層に多量の樹脂が含有されるため、透明導電層のＰＥＴフィルムに対する密着性は良好であるが、透明導電層の電気抵抗が高いものであった。
【００８１】
【発明の効果】
以上詳述したように、本発明によれば、支持体の少なくとも一方の面に機能層を備える機能性膜を、機能層が機能性微粒子を含有し、かつ、機能層の表面側の機能性微粒子配列から得られる分散値σ２と、その反対側の機能性微粒子配列から得られる分散値σ１との比（σ１／σ２）が１．２以上、１．８５以下であるものとしたので、機能層において機能性微粒子の接触が充分になされ、例えば、機能性微粒子として導電性微粒子を用いた透明導電膜は電気抵抗が低いものとなる。また、支持体と機能層の密着も強固であり、長期間の使用が可能である。さらに、支持体として、透明樹脂フィルムのような透明支持体を使用することも可能であり、また、本発明の機能性膜は、大面積化に対しても、塗布装置や圧縮装置の変更等で対応可能である。
【図面の簡単な説明】
【図１】本発明の機能性膜の一実施形態である透明導電膜の写真倍率１０万倍の断面写真の一例を示す図である。
【図２】透明導電層の表面側と、その反対側の導電性微粒子配列状態を示す線から、分散値σ１、σ２を得る手順を説明するための図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a functional membrane. In the present invention, the functional film is defined as follows. That is, the functional film is a film having a function, and the function means a function performed through physical and / or chemical phenomena. Functional films include conductive film, magnetic film, ferromagnetic film, dielectric film, ferroelectric film, electrochromic film, electroluminescence film, insulating film, light absorption film, light selective absorption film, reflection film, antireflection Films having various functions such as a film, a catalyst film, and a photocatalyst film are included.
In particular, the present invention relates to a transparent conductive film. The transparent conductive film can be used as a transparent electrode such as an electroluminescence panel electrode, an electrochromic element electrode, a liquid crystal electrode, a transparent surface heating element, and a touch panel, and can also be used as a transparent electromagnetic wave shielding film.
[0002]
[Prior art]
Conventionally, functional films made of various functional materials have been used for chemical vapor deposition (PVD) such as vacuum deposition, laser ablation, sputtering, ion plating, and chemical chemistry such as thermal CVD, photo CVD, and plasma CVD. Manufactured by chemical vapor deposition (CVD). These generally require a large-scale apparatus, and some are not suitable for forming a large-area film.
[0003]
It is also known to form a film by coating using a sol-gel method. The sol-gel method is suitable for forming a film having a large area, but in many cases, it is necessary to sinter the inorganic material at a high temperature after coating.
[0004]
For example, the transparent conductive film is as follows. Currently, the transparent conductive film is mainly produced by a sputtering method. There are various types of sputtering methods. For example, inert gas ions generated by direct current or high frequency discharge in vacuum are collided with the target surface at an accelerated rate, and atoms constituting the target are knocked out of the surface and deposited on the support surface. And forming a transparent conductive layer.
[0005]
The sputtering method is excellent in that a transparent conductive film having a low surface electric resistance can be formed even if it has a large area. However, there is a drawback that the apparatus is large and the film forming speed is slow. As the area of the transparent conductive film is further increased in the future, the apparatus will further increase. This causes a problem that technically the control accuracy must be increased, and a problem that the manufacturing cost increases from another viewpoint. Further, in order to compensate for the slow deposition rate, the number of targets is increased to increase the speed, but this is also a factor that increases the size of the apparatus.
[0006]
Attempts have also been made to produce a transparent conductive film by a coating method. In the conventional coating method, a conductive coating material in which conductive fine particles are dispersed in a binder solution is applied onto a resin film, dried and cured to form a transparent conductive film. The coating method has an advantage that a transparent conductive film having a large area can be easily formed, the apparatus is simple, the productivity is high, and the transparent conductive film can be produced at a lower cost than the sputtering method. In the transparent conductive film formed by the coating method, the conductive fine particles are brought into contact with each other to form an electrical path and develop conductivity. However, the transparent conductive film produced by the conventional coating method has a defect that the conductive fine particles are insufficiently contacted due to the presence of the binder, and the resulting transparent conductive film has a high electric resistance value (inferior in conductivity). , Its use will be limited.
[0007]
As a method for producing a transparent conductive film by a conventional coating method, for example, in JP-A-9-109259, a coating composed of conductive powder and a binder resin is applied on a transfer plastic film and dried to form a conductive layer. First step, pressurizing the surface of the conductive layer to a smooth surface (5 to 100 kg / cm²), A second process of heating (70 to 180 ° C.), and a third process of laminating this conductive layer on a plastic film or sheet and thermocompression bonding is disclosed.
[0008]
In this method, a large amount of binder resin is used (in the case of inorganic conductive powder, 100 to 500 parts by weight of conductive powder with respect to 100 parts by weight of binder, and in the case of organic conductive powder, binder 100 is used. Therefore, a conductive film having a low electric resistance value cannot be obtained.
[0009]
Also, for example, in JP-A-8-199096, a paint for forming a conductive film containing no tin-doped indium oxide (ITO) powder, solvent, coupling agent, metal organic acid salt or inorganic acid salt and containing no binder is disclosed. Is applied to a glass plate and fired at a temperature of 300 ° C. or higher. In this method, since no binder is used, the electrical resistance value of the conductive film is lowered. However, since it is necessary to perform a baking process at a temperature of 300 ° C. or higher, it is difficult to form a conductive film on a support such as a resin film. That is, the resin film melts, carbonizes, or burns at a high temperature. Depending on the type of resin film, for example, a polyethylene terephthalate (PET) film may have a limit of 130 ° C.
[0010]
As a conductive film formed by a method other than the coating method, Japanese Patent Application Laid-Open No. 6-13785 discloses at least a part of a void of a skeletal structure composed of a conductive substance (metal or alloy) powder, preferably the whole of the void. An electroconductive film comprising a powder compression layer filled with a resin and a resin layer below the resin compression layer is disclosed. The manufacturing method will be described by taking as an example the case where a film is formed on a plate material. According to the publication, when a resin, a powder substance (metal or alloy), and a plate as a member to be processed are vibrated or stirred in a container together with a film forming medium (a steel ball having a diameter of several mm), the member to be processed is obtained. A resin layer is formed on the surface. Subsequently, the powder substance is captured and fixed to the resin layer by the adhesive force of the resin layer. Furthermore, the film-forming medium that has been subjected to vibration or agitation applies a striking force to the powder material that has been subjected to vibration or agitation, and a powder compression layer is formed. However, a considerable amount of resin is required to obtain the fixing effect of the powder compression layer. Further, the production method is more complicated than the coating method.
[0011]
As another conductive film formed by a method other than the coating method, in Japanese Patent Application Laid-Open No. 9-107195, a conductive short fiber is deposited on a film such as PVC by spraying, and the conductive film obtained by pressure treatment is used. An integrated fiber-resin layer is disclosed. The conductive short fiber is obtained by applying nickel plating or the like to a short fiber such as polyethylene terephthalate. However, the pressurizing operation is preferably performed under temperature conditions where the resin matrix layer exhibits thermoplasticity, and is 175 ° C., 20 kg / cm.²Therefore, it is difficult to form a conductive film on a support such as a resin film.
[0012]
[Problems to be solved by the invention]
In view of such a background, it is desired to develop a functional film having a large area that is easy to form a functional film, has a simple apparatus, has high productivity, is low in cost, and has high quality.
In particular, regarding a conductive film, it is desired to easily form a large-area conductive film, to develop a high-quality conductive film with a simple apparatus, high productivity, low cost, and high quality.
[0013]
Accordingly, an object of the present invention is to provide a functional film that can express various functions using functional fine particles.
In particular, an object of the present invention is to provide a transparent conductive film having a low resistance value using functional fine particles.
[0014]
[Means for Solving the Problems]
  In order to achieve such an object, the present inventionConductiveThe membrane is on the support and at least one surface of the support.ConductiveWith layersConductiveA membrane, saidConductiveLayerConductiveContaining fine particles of the surface sideConductiveDispersion value σ2 obtained from the fine particle array and the opposite surface sideConductiveThe ratio (σ1 / σ2) to the dispersion value σ1 obtained from the fine particle array is 1.2 or more and 1.85 or less.
[0015]
  In addition, the present inventionConductiveAs a preferred embodiment of the membrane, the support was a transparent resin film.
[0016]
In the present invention, the functional layer is sufficiently brought into contact with the functional layer, and the strength of the functional layer and the adhesion to the support are increased. For example, the functional film in which the functional fine particle is a conductive fine particle. Has a low electrical resistance.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described.
The functional film of the present invention is a functional film having a functional layer on at least one surface of a support, the functional layer containing functional fine particles, and a functional fine particle array on the surface side of the functional layer. The ratio (σ1 / σ2) between the dispersion value σ2 obtained from the above and the dispersion value σ1 obtained from the functional fine particle array on the opposite surface side (support side) is 1.2 or more and 1.85 or less. .
[0018]
Hereinafter, the present invention will be described by taking a transparent conductive film as an embodiment of the functional film of the present invention as an example. In the present invention, transparent means that visible light is transmitted. About the degree of light scattering, the level requested | required changes with the uses of a transparent conductive film.
The transparent conductive film which is a functional film of the present invention includes a transparent conductive layer as a functional layer on a transparent support.
[0019]
The transparent conductive layer constituting the transparent conductive film contains conductive fine particles as functional fine particles, the dispersion value σ2 obtained from the conductive fine particle array on the surface side of the transparent conductive layer, and the conductive fine particles on the opposite surface The ratio (σ1 / σ2) to the dispersion value σ1 obtained from the array is 1.2 or more and 1.85 or less. In the present invention, the dispersion value σ1 and the dispersion value σ2 are defined as follows. That is, the conductive fine particle array on the side opposite to the surface of the transparent conductive layer and the conductive fine particle array on the surface side in the cross-sectional photograph of the transparent conductive film at a magnification of 100,000 times are traced, and the two types of conductivity obtained A plurality of distances from the reference line are measured for the line indicating the fine particle arrangement state, and the average value of the difference between the average value of the measured values and each measured value is defined as dispersion values σ1 and σ2.
[0020]
This requirement will be described in more detail with reference to FIGS. First, the square tracing paper is placed on a cross-sectional photograph (Fig. 1) of the transparent conductive film at a magnification of 100,000 times so as not to be displaced, and is opposite to the surface of the transparent conductive layer (surface 1A in Fig. 2). The end face on which the conductive fine particles are arranged and the end face on which the conductive fine particles on the surface side (1B surface in FIG. 2) are arranged are traced, and lines L1 and L2 indicating the conductive fine particle arrangement state are respectively traced. obtain. Since the portion where the conductive fine particles are clearly missing affects the measurement, the missing portion is extrapolated from both sides of the missing portion to obtain a line segment. Next, reference lines B1 and B2 are drawn about 1 cm apart from each of the lines L1 and L2 indicating the above-described two kinds of conductive fine particle arrangement states. Then, the distance from the reference line B1 to the line L1 indicating the conductive fine particle arrangement state is measured at intervals of 1 to 2 mm (measurement length is 10 cm or more), and the difference between the average value of the measurement values and each measurement value The average value of the squares of is defined as the variance value σ1. Similarly, the distance from the reference line B2 to the line L2 indicating the conductive fine particle arrangement state is measured at intervals of 1 to 2 mm, and the average value of the difference between the average value of the measured values and each measured value is the dispersion value σ2. And Then, the ratio (σ1 / σ2) between the variance value σ1 and the variance value σ2 is calculated.
[0021]
The transparent conductive layer in which the ratio (σ1 / σ2) between the dispersion value σ1 and the dispersion value σ2 is 1.2 or more and 1.85 or less is such that the conductive fine particles constituting the transparent conductive layer are embedded in the transparent support. It is possible for the first time. In the conventional transparent conductive film, the surface opposite to the surface of the transparent conductive layer is a smooth surface reflecting the smooth surface of the transparent support as it is, and the ratio (σ1 / σ2) is 1.2 or more. Did not exist. When the ratio (σ1 / σ2) is less than 1.2, the contact between the conductive fine particles becomes insufficient, and it is difficult to obtain a transparent conductive layer excellent in conductivity. Further, the strength of the transparent conductive layer is low, and the adhesion to the transparent support is insufficient. On the other hand, a higher ratio (σ1 / σ2) is preferable, but a high compressive force is required in forming the transparent conductive layer, and the pressure resistance of the compression device must be increased. is there.
[0022]
The conductive fine particles constituting the transparent conductive layer as described above are not particularly limited as long as the transparency of the transparent conductive film is not impaired, and known inorganic conductive fine particles can be used.
Examples of the inorganic conductive fine particles include tin oxide, indium oxide, zinc oxide, cadmium oxide, and the like, and antimony-doped tin oxide (ATO), fluorine-doped tin oxide (FTO), tin-doped indium oxide (ITO), and aluminum-doped oxide. Fine particles such as zinc (AZO) are preferred. Furthermore, ITO is preferable in that a superior conductivity can be obtained. Or what coated inorganic material, such as ATO and ITO, on the surface of fine particles which have transparency, such as barium sulfate, can also be used.
[0023]
These conductive fine particles have an average primary particle size of 300 nm or less, preferably 100 nm or less, and more preferably in the range of 5 nm to 50 nm. If the average primary particle size of the conductive fine particles exceeds 300 nm, the characteristic balance of the transparent conductive layer is likely to be impaired, which is not preferable.
[0024]
The transparent conductive layer made of the conductive fine particles as described above can have a thickness of 0.1 to 10 μm, preferably 0.5 to 5 μm. And the electrical resistance of a transparent conductive layer can be suitably set according to the use of a transparent conductive film.
[0025]
In this invention, you may contain a trace amount resin in the range which does not increase an electrical resistance value in the transparent conductive layer which comprises a transparent conductive film. For example, when the volume of the conductive fine particles is 100, the transparent conductive layer can contain a resin with a volume of less than 25, preferably less than 20, more preferably less than 3.7, more preferably The transparent conductive layer does not contain a resin. The resin has an effect of reducing light scattering of the transparent conductive layer, but on the other hand increases the electric resistance value of the transparent conductive film. This is because the contact between the conductive fine particles is inhibited by the insulating resin, and when the amount of the resin is large, the conductive fine particles do not contact each other, so that the electron transfer between the fine particles is inhibited. Therefore, in consideration of both improvement of the haze degree and securing of conductivity between the conductive fine particles, when the resin is contained, it is used within the above volume range. If the amount of resin is within this range, the amount of resin is small, and it is considered that most of the resin is present in the voids of the conductive fine particles in the transparent conductive layer.
[0026]
The above-mentioned resin is not particularly limited, and a thermoplastic resin excellent in transparency or a polymer having rubber elasticity can be used alone or in combination of two or more. Examples of resins include fluoropolymers, silicone resins, acrylic resins, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose diacetyl cellulose, polyvinyl chloride, polyvinyl pyrrolidone, polyethylene, polypropylene, SBR, polybutadiene, polyethylene oxide, and the like. Can be mentioned.
[0027]
Examples of the fluorine-based polymer include polytetrafluoroethylene, polyvinylidene fluoride (PVDF), vinylidene fluoride-trifluoride ethylene copolymer, ethylene-tetrafluoroethylene copolymer, propylene-tetrafluoroethylene copolymer, and the like. It is done. A fluorine-containing polymer in which hydrogen in the main chain is substituted with an alkyl group can also be used. The higher the density of the resin, the smaller the volume even if a larger weight is used, and the above volume condition is easily satisfied.
[0028]
Note that the volume of the conductive fine particles and the volume of the resin described above are not apparent volumes but true volumes. The true volume is obtained by determining the density using an instrument such as a pycnometer based on JIS Z 8807 and dividing the weight of the material to be used by the density. In this way, the amount of resin used is defined not by weight but by volume, which reflects more reality when considering how the resin exists for the conductive fine particles in the transparent conductive layer. Because it does.
[0029]
As a transparent support which comprises the transparent conductive film of this invention, various things, such as a resin film and glass, can be used. Accordingly, a part of the conductive fine particles in contact with the transparent support is felt to be embedded in the transparent support, and the transparent conductive layer is in close contact with the transparent support. As such a transparent support, when using a material having a hardness higher than that of the conductive fine particles, such as a material having high hardness such as glass, or a resin film having a hard film surface, the glass surface or A transparent support in which a resin layer having a hardness smaller than that of the conductive fine particles is previously formed on the hard film surface is used. Thereby, the conductive fine particles are embedded in the resin layer, and the adhesiveness between the transparent conductive layer and the transparent support becomes sufficient.
[0030]
In addition, after forming a transparent conductive layer, you may harden the resin layer with small hardness with a heat | fever, an ultraviolet-ray, etc. This resin layer is preferably a substance that does not dissolve in a liquid in which conductive fine particles are dispersed. When dissolved, a solution containing the resin comes around the conductive fine particles due to capillary action, and as a result, the electric resistance value of the obtained transparent conductive layer becomes high. Moreover, after forming a transparent conductive layer, a resin layer can be peeled from a glass surface or a hard film surface, and it can also be set as a transparent conductive film provided with a transparent resin layer as a transparent support body.
[0031]
The resin layer as described above can be formed of a thermoplastic resin having excellent transparency or a polymer having rubber elasticity, which is a single type or a mixture of two or more types. Examples of resins include fluoropolymers, silicone resins, acrylic resins, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose diacetyl cellulose, polyvinyl chloride, polyvinyl pyrrolidone, polyethylene, polypropylene, SBR, polybutadiene, polyethylene oxide, and the like. Can be mentioned.
[0032]
In the case of using a material that does not have flexibility, such as glass and ceramics, there is a high possibility that the material will break during the process. Therefore, a resin film that does not break is suitable as the transparent support. As will be described below, the resin film is preferable in terms of good adhesion to the transparent conductive layer made of conductive fine particles, and is also suitable for applications where weight reduction is required. Therefore, when there is no purpose of use at high temperatures, the resin film can be used as a transparent support.
[0033]
Examples of the resin film include polyester films such as polyethylene terephthalate (PET), polyolefin films such as polyethylene and polypropylene, polycarbonate films, acrylic films, norbornene films (Arton manufactured by JSR Corporation), and the like.
As the transparent support, those having a haze in the range of 0.5 to 5% can be used depending on the application.
In the present invention, it is of course possible to provide a transparent conductive film having a transparent conductive layer on both sides of the transparent support.
[0034]
Next, an example of the manufacturing method of the transparent conductive film of this invention is demonstrated.
The transparent conductive layer constituting the transparent conductive film can be formed by applying conductive fine particles and, if necessary, a dispersion containing a small amount of resin as a conductive paint on a transparent support, drying, and then compressing. .
[0035]
The liquid in which the conductive fine particles are dispersed is not particularly limited as long as the resin dissolves in the case where the conductive coating contains a resin, and various known solvents can be used. Examples of solvents include saturated hydrocarbons such as hexane, aromatic hydrocarbons such as toluene and xylene, alcohols such as methanol, ethanol, propanol, and butanol, and ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and diisobutyl ketone. , Esters such as ethyl acetate and butyl acetate, ethers such as tetrahydrofuran, dioxane and diethyl ether, amides such as N, N-dimethylformamide, N-methylpyrrolidone (NMP) and N, N-dimethylacetamide, ethylene chloride And halogenated hydrocarbons such as chlorobenzene. Among these, polar solvents are preferable, and alcohols such as methanol and ethanol, and amides such as NMP are preferable. These solvents can be used singly or as a mixture of two or more. Further, a dispersant may be used for improving the dispersibility of the conductive fine particles.
[0036]
Water can also be used as a solvent. When water is used, the transparent support needs to be hydrophilic. Since the above-mentioned resin layer and resin film are usually hydrophobic, they easily repel water and it is difficult to obtain a uniform film. When the resin layer is provided on the surface of the transparent support, when the transparent support is a resin film, it is necessary to mix alcohol with water or make the surface of the support hydrophilic. In addition, when a conductive coating material contains resin, it is better to consider the solubility of resin.
[0037]
The amount of the solvent to be used is not particularly limited, and the dispersion liquid of the conductive fine particles may have a viscosity suitable for coating. For example, the amount is about 100 to 100,000 parts by weight of the liquid with respect to 100 parts by weight of the conductive fine particles. It is good to select suitably according to the kind of electroconductive fine particles and liquid.
[0038]
The dispersion of the conductive fine particles in the liquid may be performed by a known dispersion method. For example, it is dispersed by a sand grinder mill method. In dispersing, it is also preferable to use a medium such as zirconia beads in order to loosen the aggregation of the conductive fine particles. Also, care should be taken not to mix impurities such as dust during dispersion.
[0039]
Various additives may be added to the dispersion of the conductive fine particles within a range in which the conductivity is not lowered. For example, additives such as ultraviolet absorbers, surfactants, and dispersants.
[0040]
Application | coating of the dispersion liquid of the electroconductive fine particles on a transparent support body can be performed by a well-known method, without being specifically limited. For example, it can be performed by a coating method such as a reverse roll method, a direct roll method, a blade method, a knife method, an extrusion nozzle method, a curtain method, a gravure roll method, a bar coat method, a dip method, a kiss coat method, or a squeeze method. It is also possible to deposit the dispersion on the transparent support by spraying or spraying.
[0041]
The drying temperature depends on the type of liquid used for dispersion, but is preferably about 10 to 150 ° C. If it is less than 10 ° C, condensation of moisture in the air tends to occur, and if it exceeds 150 ° C, the resin film support is deformed. Also, care should be taken so that impurities do not adhere to the surface of the conductive fine particles during drying.
The thickness of the conductive fine particle-containing layer after coating and drying may be about 0.1 to 10 μm, although it depends on the compression conditions of the next step and the use of the transparent conductive film.
[0042]
As described above, when conductive fine particles are dispersed in a liquid, applied, and dried, a uniform film can be easily formed. When a dispersion of conductive fine particles is applied and dried, the dispersion does not contain a large amount of binder resin as in the prior art, that is, does not contain a resin as in the present invention, or a specific amount of resin. Even in the following small amounts, the fine particles form a film. The reason why a film is formed even if a large amount of binder resin is not present is not necessarily clear, but when it is dried and the liquid is reduced, fine particles gather due to capillary force. Furthermore, the fact that it is a fine particle has a large specific surface area and a strong cohesive force, so it is thought that it may become a film. However, the film at this stage has a ratio (σ1 / σ2) of the dispersion value σ1 to the dispersion value σ2 of less than 1.2, the strength is weak, and the transparent conductive layer has a high electric resistance value. Also, the variation in electrical resistance value is large.
[0043]
Next, the formed conductive fine particle-containing layer is compressed to obtain a compressed layer of conductive fine particles. By compressing, the conductive fine particles are embedded in the transparent support, and the ratio (σ1 / σ2) between the dispersion value σ1 and the dispersion value σ2 is 1.2 or more. Thereby, a reduction in electrical resistance and an improvement in film strength are achieved. That is, by compressing, the contact points between the conductive fine particles increase and the contact surface increases. For this reason, electrical resistance falls and coating-film intensity | strength rises. Since the fine particles originally have a property of easily agglomerating, they become a strong film by being compressed. Moreover, haze degree falls by compressing.
[0044]
Compression is 44 N / mm²It is preferable to carry out with the above compressive force. 44 N / mm²If the pressure is less than 1, the conductive fine particle-containing layer cannot be sufficiently compressed, and it is difficult to obtain a transparent conductive layer excellent in conductivity. Compression is 180 N / mm²The above compressive force is more preferable. As the compressive force is higher, a transparent conductive layer having better conductivity is obtained, the strength of the transparent conductive layer is improved, and the adhesiveness to the transparent support is strengthened. The higher the compression force, the higher the pressure resistance of the device, so generally 1000 N / mm²The compression force up to is appropriate.
Moreover, it is preferable to perform compression at the temperature near normal temperature (15-40 degreeC). When compression (hot pressing) is performed under heating conditions, the resin film may be stretched when the compression pressure is increased.
[0045]
The compression means is not particularly limited and can be performed by a sheet press, a roll press, or the like, but is preferably performed using a roll press machine. Roll press is a method in which a film to be compressed is sandwiched between rolls and compressed, and the roll is rotated. A roll press is suitable for increasing productivity because it is uniformly pressurized and can be produced roll-to-roll.
[0046]
The roll temperature of the roll press machine is preferably normal temperature. In the compressed atmosphere (hot press) in which the heated atmosphere or the roll is heated, there is a problem that the resin film stretches when the compression pressure is increased. If the compression pressure is weakened so that the resin film does not stretch under heating, the mechanical strength of the transparent conductive layer decreases and the electrical resistance increases. When there is a reason for wanting to minimize moisture adhesion on the surface of fine particles, a heated atmosphere may be used to reduce the relative humidity of the atmosphere, but the temperature range is within the range where the film does not easily stretch. It is. Generally, it is a temperature range below the glass transition temperature (secondary transition temperature). In consideration of fluctuations in humidity, the temperature may be a little higher than the required temperature. It is also preferable to adjust the temperature so that the roll temperature does not rise due to heat generation when continuously compressed by a roll press. The glass transition temperature of the resin film is obtained by measuring dynamic viscoelasticity and refers to a temperature at which the dynamic loss of main dispersion reaches a peak. For example, in the case of a PET film, the glass transition temperature is about 110 ° C.
[0047]
The roll of the roll press machine is preferably a metal roll because a strong pressure is applied. Further, if the roll surface is soft, the conductive fine particles may be transferred to the roll during compression, and therefore it is preferable to treat the roll surface with a hard film.
[0048]
Thus, the transparent conductive film of this invention provided with the transparent conductive layer is obtained by forming the compression layer of conductive fine particles. As described above, the thickness of the transparent conductive layer may be about 0.1 to 10 μm although it depends on the application. Moreover, in order to obtain a thick transparent conductive layer of about 10 μm, a series of operations of applying a dispersion of conductive fine particles, drying, and compression may be repeated. In addition, when the same operation is repeated in this way to obtain a functional layer in which the same functional layers are laminated, the outermost surface of the laminated layer is set as a surface to be measured. Also, when a functional layer in which different functional layers are laminated is obtained, the outermost surface of the laminated layer is a surface to be measured.
[0049]
The transparent conductive film of the present invention obtained in this way has a transparent conductive layer exhibiting excellent conductivity, and practically sufficient film strength despite being prepared without using a large amount of binder resin as in the past. And has excellent adhesion to a transparent support.
[0050]
In the above-described embodiment, the transparent conductive film is exemplified as the functional film. However, in the present invention, the functional film is not particularly limited, and the conductive film, the magnetic film, the ferromagnetic film, the dielectric film, the strong film, and the like. Films having various functions such as a dielectric film, an electrochromic film, an electroluminescence film, an insulating film, a light absorption film, a light selective absorption film, a reflection film, an antireflection film, a catalyst film, and a photocatalyst film are included. Therefore, in the present invention, functional fine particles that should constitute the target film are used. The functional fine particles are not particularly limited, and mainly inorganic fine particles having a cohesive force are used. In any of the functional films of the present invention, a functional layer having sufficient mechanical strength can be obtained, and adverse effects caused by the binder resin in the conventional coating method using a large amount of the binder resin can be eliminated. As a result, the intended function is further improved.
[0051]
In addition to the transparent conductive film described above, for example, in a ferromagnetic film, γ-Fe₂ O_Three , Fe_Three O_Four Co-FeO_x, Iron oxide magnetic powders such as Ba ferrite, and ferromagnetic alloy powders mainly composed of ferromagnetic metal elements such as α-Fe, Fe—Co, Fe—Ni, Fe—Co—Ni, Co, and Co—Ni And the saturation magnetic flux density of the magnetic coating film which is a functional layer is improved.
[0052]
For dielectric films and ferroelectric films, magnesium titanate, barium titanate, strontium titanate, lead titanate, lead zirconate titanate (PZT), lead zirconate, lanthanum-doped titanate Dielectric or ferroelectric fine particles such as lead zirconate (PLZT), magnesium silicate, and lead-containing perovskite compounds are used. The dielectric film or the ferroelectric film of the present invention can improve dielectric characteristics or ferroelectric characteristics.
[0053]
In addition, in metal oxide films that exhibit various functions, iron oxide (Fe₂ O_Three), Silicon oxide (SiO₂), Aluminum oxide (Al₂ O_Three), Titanium dioxide (TiO₂), Titanium oxide (TiO), zinc oxide (ZnO), zirconium oxide (ZrO)₂), Tungsten oxide (WO_Three) And other metal oxide fine particles are used. In the metal oxide film of the present invention, the degree of filling of the metal oxide in the functional layer is increased, so that each function is improved. For example, SiO on which a catalyst is supported₂, Al₂ O_ThreeWhen is used, a porous catalyst membrane having practical strength can be obtained. TiO₂When is used, the photocatalytic function can be improved. In addition, WO_ThreeWhen is used, an improvement in the coloring effect in the electrochromic display element can be obtained.
[0054]
Furthermore, zinc sulfide (ZnS) fine particles are used in the electroluminescence film. The electroluminescent film of the present invention can be made inexpensive by a coating method.
[0055]
The particle diameter r of the functional fine particles varies depending on the application of the functional film, for example, depending on the degree of scattering that is required, and cannot generally be described depending on the shape of the particles. = 10 μm or less, preferably 1.0 μm or less, and more preferably 5 nm to 100 nm.
[0056]
【Example】
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.
[0057]
[Example 1]
First, 300 parts by weight of ethanol is added to 100 parts by weight of ATO fine particles (SN-100P manufactured by Ishihara Sangyo Co., Ltd.) having an average primary particle size of 20 nm, and the medium is dispersed as a zirconia bead in a disperser to form a conductive paint. Prepared.
[0058]
Next, the conductive coating solution was applied onto a PET film (thickness 50 μm) using a bar coater and dried at 50 ° C. The obtained film is hereinafter referred to as a pre-compression ATO film. The thickness of the ATO-containing coating film was 2.2 μm.
[0059]
Next, the ATO film before compression was sandwiched between metal rolls (the roll surface was hard-chrome plated), and the roll was rotated at room temperature (23 ° C.) and compressed at a feed rate of 5 m / min. The compression pressure per unit area in this compression step was set under different conditions as shown in Table 1 below. Thus, the transparent conductive film (samples 1-6) provided with the transparent conductive layer was obtained by compressing an ATO film.
[0060]
Further, a resin obtained by dissolving 100 parts by weight of an acrylic resin solution MT408-42 (nonvolatile component concentration: 50%) manufactured by Taisei Kako as a resin in 400 parts by weight of a mixed solution of methyl ethyl ketone / toluene / cyclohexanone (1: 1: 1). 100 parts by weight of the same ATO powder as described above was added to the solution, and the media was dispersed as zirconia beads with a disperser to prepare a conductive paint. Using this conductive paint, a transparent conductive film (sample 7) was obtained in the same manner as the transparent conductive film (samples 1 to 6) described above. However, the compression pressure per unit area in the compression process is shown in Table 1.
[0061]
In addition, the transparent conductive film described above was used except that a transparent resin was prepared by providing a 3 μm thick silicon resin hard coat material (GE, Toshiba Silicon Co., Ltd. Tosguard 510) on the PET film. A transparent conductive film (Sample 8) was obtained in the same manner as (Sample 3: No resin used).
[0062]
For the eight types of transparent conductive films (samples 1 to 8) produced as described above, the thickness of the transparent conductive layer after compression was measured, and the dispersion value σ1 and the dispersion value for the transparent conductive layer were measured according to the following measurement method. The ratio to σ2 (σ1 / σ2) was measured and the results are shown in Table 1 below.
[0063]
Further, the surface electrical resistance value and haze were measured according to the following measurement method, and the results are shown in Table 1 below. Furthermore, in order to evaluate the adhesiveness between the PET film and the transparent conductive layer and the strength of the transparent conductive layer, a 90 ° peel test was conducted by the following method, and the results are shown in Table 1 below.
[0064]
Method for measuring the ratio (σ1 / σ2)
Place the tracing paper of the grid on the cross-sectional photograph of the transparent conductive film with a magnification of 100,000 times so that it does not deviate, and trace the end face where the conductive particles on the interface side and the surface side of the transparent conductive layer are arranged respectively. The lines L1 and L2 indicate the conductive fine particle arrangement state. Incidentally, the part where the conductive fine particles are clearly missing is extrapolated from both sides to obtain a line segment. Next, the reference lines B1 and B2 are drawn at a distance of about 1 cm from the lines L1 and L2 indicating the above-described two kinds of conductive fine particle arrangement states. Then, the distance from the reference line B1 to the line L1 and the distance from the reference line B2 to the line L2 are measured at intervals of 2 mm (measurement length is 10 cm), and the average value of the measured values and each measurement are measured. The average value of the square of the difference from the value is set as the dispersion values σ1 and σ2, and the ratio (σ1 / σ2) is calculated.
[0065]
Measurement of surface electrical resistance
The transparent conductive film on which the transparent conductive layer was formed was cut into a size of 50 mm × 50 mm, and the electrical resistance was measured by applying a tester terminal bar to two corners at diagonal positions.
[0066]
Haze measurement
Measured using a haze meter (TC-H3 DPK type manufactured by Tokyo Denshoku Co., Ltd.).
[0067]
90 ° peel test
A double-sided tape is attached to the surface of the transparent conductive film opposite to the surface on which the transparent conductive layer of the PET film is formed, and this is cut into a size of 25 mm × 100 mm to be a test sample, which is then attached to a stainless steel plate. Next, a cellophane tape is applied to both end portions (25 mm long side) of the test sample so that the test sample is not peeled off. Thereafter, a cellophane tape (width 12 mm, No. 29 manufactured by Nitto Denko Corporation) is applied to the transparent conductive layer surface of the test sample so as to be parallel to the long side of the test sample. The length of the cellophane tape and the test sample is 50 mm. Next, attach the end of the cellophane tape to the chuck, set it so that the angle between the cellophane tape application surface and the non-adhesion surface is 90 degrees, and pull the cellophane tape at a speed of 100 mm / min. . At this time, the speed at which the cellophane tape is peeled off and the stainless steel plate to which the test sample is attached are moved at the same speed so that the non-sticking surface of the cellophane tape and the test sample surface are always 90 degrees. After the test, the state of the coating film is examined and evaluated according to the following evaluation criteria.
○: The coating film is not destroyed and peeling from the PET film does not occur
X: The coating film is destroyed and a part of the coating film adheres to the cellophane tape
[0068]
[Table 1]

[0069]
As shown in Table 1, the transparent conductive film of the present invention (samples 1 to 5) provided with a transparent conductive layer having a ratio (σ1 / σ2) of dispersion values σ1 and σ2 of 1.2 or more and 1.85 or less It was confirmed that all of these materials have sufficiently low electrical resistance values, low haze, and sufficient transparency. Moreover, it was confirmed that these transparent conductive films have good adhesion to the PET film of the transparent conductive layer even though they do not contain a resin.
[0070]
On the other hand, the transparent conductive film (samples 6 and 8) provided with the transparent conductive layer having a ratio (σ1 / σ2) of the dispersion values σ1 and σ2 of less than 1.2 has a value of electrical resistance of the transparent conductive layer. Regardless of the adhesion of the transparent conductive layer to the PET film.
[0071]
Further, the transparent conductive film (sample 7) provided with a transparent conductive layer having a ratio (σ1 / σ2) of dispersion values σ1 and σ2 of less than 1.2 is transparent because a large amount of resin is contained in the transparent conductive layer. The adhesion of the conductive layer to the PET film was good, but the electrical resistance of the transparent conductive layer was high.
[0072]
[Example 2]
First, 300 parts by weight of methanol is added to 100 parts by weight of ITO fine particles (SUFP-HX manufactured by Sumitomo Metal Mining Co., Ltd.) having an average primary particle size of 20 nm, and the medium is dispersed as a zirconia bead in a disperser to form a conductive paint. Was prepared.
[0073]
Next, the conductive coating liquid was applied to a PET film having a thickness of 50 μm using a bar coater and dried at 50 ° C. The film thus obtained is hereinafter referred to as a pre-compression ITO film. The thickness of the ITO-containing coating film of these pre-compression ITO films was 1.9 μm.
[0074]
Next, the ITO film before compression was sandwiched between metal rolls (the roll surface was subjected to hard chrome plating treatment), and the roll was rotated at room temperature (23 ° C.) and compressed at a feed rate of 5 m / min. The compression pressure per unit area in this compression step was set under different conditions as shown in Table 2 below. Thus, the transparent conductive film (sample AF) provided with the transparent conductive layer was obtained by compressing an ITO film.
[0075]
Further, a resin obtained by dissolving 100 parts by weight of an acrylic resin solution MT408-42 (nonvolatile component concentration: 50%) manufactured by Taisei Kako as a resin in 400 parts by weight of a mixed solution of methyl ethyl ketone / toluene / cyclohexanone (1: 1: 1). 100 parts by weight of the same ITO powder as above was added to the solution, and the media was dispersed as zirconia beads with a disperser to prepare a conductive paint. Using this conductive paint, a transparent conductive film (sample G) was obtained in the same manner as the transparent conductive films (samples A to F) described above. However, the compression pressure per unit area in the compression process is shown in Table 2.
[0076]
In addition, the transparent conductive film described above was used except that a transparent resin was prepared by providing a 3 μm thick silicon resin hard coat material (GE, Toshiba Silicon Co., Ltd. Tosguard 510) on the PET film. A transparent conductive film (Sample H) was obtained in the same manner as (Sample C: no resin used).
[0077]
For the transparent conductive film (samples A to H) produced as described above, in the same manner as in Example 1, the thickness of the transparent conductive layer, the ratio of dispersion values σ1 and σ2 (σ1 / σ2), surface electrical resistance value, haze The results are shown in Table 2 below. Further, a 90 ° peel test was conducted in the same manner as in Example 1, and the results are shown in Table 2 below.
[0078]
[Table 2]

[0079]
As shown in Table 2, the transparent conductive film of the present invention (samples A to E) provided with a transparent conductive layer having a ratio (σ1 / σ2) of dispersion values σ1 and σ2 of 1.2 or more and 1.85 or less In any of the above, it was confirmed that the transparent conductive layer had a sufficiently low electrical resistance, a low haze, and sufficient transparency. Moreover, although these transparent conductive films did not contain resin, it was confirmed that the adhesiveness of the transparent conductive layer to the transparent support is also good.
[0080]
On the other hand, the transparent conductive film (samples F and H) provided with a transparent conductive layer having a ratio (σ1 / σ2) of the dispersion values σ1 and σ2 of less than 1.2 is in close contact with the transparent support of the transparent conductive layer. It was bad.
Moreover, since the transparent conductive layer (sample G) including a transparent conductive layer having a dispersion value σ1, σ2 ratio (σ1 / σ2) of less than 1.2 contains a large amount of resin, it is transparent. The adhesion of the conductive layer to the PET film was good, but the electrical resistance of the transparent conductive layer was high.
[0081]
【The invention's effect】
As described above in detail, according to the present invention, a functional film having a functional layer on at least one surface of the support, the functional layer containing functional fine particles, and the functionality on the surface side of the functional layer. Since the ratio (σ1 / σ2) between the dispersion value σ2 obtained from the fine particle array and the dispersion value σ1 obtained from the functional fine particle array on the opposite side is 1.2 to 1.85, The layer is sufficiently contacted with the functional fine particles. For example, a transparent conductive film using conductive fine particles as the functional fine particles has a low electrical resistance. In addition, the adhesion between the support and the functional layer is strong, and long-term use is possible. Furthermore, it is also possible to use a transparent support such as a transparent resin film as the support, and the functional film of the present invention can be applied to a large area even when the coating device or the compression device is changed. It is possible to cope with.
[Brief description of the drawings]
FIG. 1 is a view showing an example of a cross-sectional photograph of a transparent conductive film as an embodiment of the functional film of the present invention at a photographic magnification of 100,000.
FIG. 2 is a diagram for explaining a procedure for obtaining dispersion values σ1 and σ2 from the surface side of the transparent conductive layer and a line indicating the conductive fine particle arrangement state on the opposite side.

Claims (2)

In a conductive film comprising a support and a conductive layer on at least one surface of the support,
The conductive layer contains conductive fine particles, the ratio of the variance .sigma. @ 2 obtained from the surface side of the conductive fine particle arrangement, the dispersion value .sigma.1 obtained conductive fine particle arrangement on the opposite side (σ1 / σ2) but less than 1.2, a conductive film, characterized in that it is 1.85. The conductive film according to claim 1, wherein the support is a transparent resin film.

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