JP3652563B2 - Transparent conductive film forming paint, transparent conductive film and display device - Google Patents

Description

以上の評価試験結果を表１及び表２に示す。
【００５１】
【表１】

【表２】

【００５２】
上記表１、表２の結果から、金属微粒子の塊状凝集体を含む本塗料を塗布することにより形成された実施例１〜実施例３の陰極線管は、従来の均一分散した金属微粒子を含む比較例１〜比較例３と同等の膜厚にもかかわらず表面抵抗が小さくなっていることがわかる。この結果、同程度の表面抵抗値とする場合には導電層の厚みを薄くすることができ、従って透明導電膜の透過率が優れて透明性が高いものとなる。
また、本塗料を用いて形成された透明導電膜は耐スクラッチ性にも優れていた。透過率差、視認性、膜ムラについては、従来の均一分散した金属微粒子を含む比較例１〜比較例３と同等の良好な結果が得られている。
【００５３】
【発明の効果】
本発明によれば、形成された透明導電膜は、導電層の膜厚が極めて薄く従って可視光の平均透過率が高いにも係わらず、電磁波遮蔽効果および帯電防止効果に優れ、特に銀微粒子とパラジウム微粒子との塊状凝集体を用いた場合には透過画像の色相が自然で、しかも耐塩水性に代表される耐久性にも優れたものとなる。従ってこの透明導電膜が表示面に形成された本発明の表示装置は、透過画像の色相が自然で、優れた帯電防止性と電磁波遮蔽性と耐久性とを有し、しかも光透過性が高いために透過画像が明るく塗膜の膜厚ムラも目立たないものとなる。
【図面の簡単な説明】
【図１】 本発明の表示装置の一実施例を示す部分断面図である。
【図２】 （ａ）（ｂ）はそれぞれ、金属微粒子の塊状凝集体を模式的に示す概念図である。
【符号の説明】
１：表示面
２：導電層
３：透明層
４：凹凸層
５：透明導電膜
６：金属微粒子
７：塊状凝集体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transparent conductive film-forming coating material, a transparent conductive film, and a display device, and particularly has an antistatic effect and an electromagnetic wave shielding effect that are excellent for use on a display surface of a cathode ray tube or a plasma display. A transparent conductive film-forming coating material capable of forming a transparent conductive film having a high average visible light transmittance and a natural hue of a transmitted image and having excellent durability such as salt water resistance, oxidation resistance, and ultraviolet resistance. The present invention relates to a transparent conductive film formed by applying a coating for forming a transparent conductive film, and a display device in which the transparent conductive film is formed on a display surface.
[0002]
[Prior art]
A cathode ray tube currently used as a TV cathode ray tube or a computer display projects characters and images on a display screen by projecting an electron beam onto a fluorescent screen emitting red, green, and blue light. In addition to dust being attached due to static electricity generated on the display surface, visibility may be reduced, and electromagnetic waves may be radiated to affect the environment. Recently, the possibility of generation of static electricity and electromagnetic radiation has been pointed out in plasma displays that are being applied as wall-mounted televisions.
[0003]
In order to solve these problems, conventionally, a coating liquid in which fine particles such as silver and gold are uniformly dispersed in the liquid is applied and dried on the display surface of the display device, or conductive by sputtering or vapor deposition. A transparent transparent metal thin film is formed, and a transparent layer having a refractive index different from that of the transparent metal thin film is laminated on the upper layer and / or the lower layer of the transparent metal thin film so as to shield electromagnetic waves, prevent charging, and prevent reflection. For example, in JP-A-8-77832, as a transparent conductive film excellent in electromagnetic wave shielding effect and antireflection effect, a conductive layer made of metal fine particles containing at least silver in an average particle size range of 2 nm to 200 nm, and A layer composed of transparent layers having different refractive indexes has been proposed.
[0004]
[Problems to be solved by the invention]
However, in these methods, the conductivity of the transparent conductive film is not always sufficient, and depending on the light transmission spectrum of silver, absorption occurs in transmitted light of 400 nm to 500 nm, the conductive film is colored yellow, and the transmission image The problem is that the hue changes unnaturally, the visible light average transmittance of the film is low, and the unevenness of the transmitted color due to the film thickness distribution is conspicuous and the productivity is deteriorated. Since the resistance increases and the electromagnetic wave shielding effect decreases, problems such as a decrease in durability have not been solved in places that are easily affected by salt fog, such as the coast.
The present invention has been made in order to solve the above-described problems, and therefore, the object thereof is excellent in conductivity that provides an electromagnetic wave shielding effect and an antistatic effect, has a high average visible light transmittance of the film, and is capable of transmitting images. Transparent conductive film-forming coating material capable of forming a transparent conductive film having a natural hue and excellent durability represented by salt water resistance, a transparent conductive film formed using this transparent conductive film-forming coating material, and this An object of the present invention is to provide a display device in which a transparent conductive film is formed on a display surface.
[0005]
[Means for Solving the Problems]
  In order to solve the above problems, the present invention provides at least a mass aggregate of metal fine particles as a conductive material.Dispersed in dispersion mediumA transparent conductive film-forming paint, wherein the particle size of the metal fine particles is in the range of 1 nm to 100 nm,The bulk aggregate has a particle size in the range of 70 nm to 300 nm.A paint for forming a transparent conductive film is provided.
  The above metal fine particlesContains at least silver fine particles and palladium fine particles, and the blending ratio of the silver fine particles and the palladium fine particles is in the range of 10% to 90% by weight of silver fine particles: 90% to 10% by weight of fine palladium particles. It is preferable.
[0006]
  The present invention also provides a transparent conductive film having a conductive layer formed by applying the paint for forming a transparent conductive film.
  Above conductive layerThe film thickness is preferably in the range of 5 nm to 500 nm.
  Also,The upper layer of the conductive layer, or the lower layer, or the upper layer and the lower layer,It is preferable that at least one transparent layer having a refractive index different from that of the conductive layer is laminated.
  These transparent conductive filmsAverage transmittance of visible light is 80% or moreAnd the surface resistance is 1 × 10⁴It is preferable that it is below Ω / □.
  The present invention further provides a display device in which any one of the transparent conductive films is formed on a display surface.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to preferred specific examples.
FIG. 1 is a partial sectional view of a preferred display device of the present invention. In this display device, a conductive layer 2, a transparent layer 3, and a transparent layer 4 (hereinafter referred to as an “uneven layer”) 4 are laminated in order on the display surface 1. 2, the transparent layer 3, and the uneven | corrugated layer 4 form the transparent conductive film 5 of this invention.
[0008]
As a result of intensive studies on the transparent conductive film formed by applying a paint containing metal fine particles in order to impart an excellent antireflection effect and electromagnetic wave shielding effect to the display surface 1 of the display device. In particular, metal fine particles having a particle diameter in the range of 1 nm to 100 nm are aggregated in a lump, and a metal fine particle aggregate having a particle diameter in the range of 30 nm to 500 nm (hereinafter referred to as “bulk aggregate”) is contained. When the conductive layer 2 is formed using a paint, the inventors have obtained the knowledge that a transparent conductive film 5 having higher conductive performance and transparency can be produced than when the metal fine particles are uniformly dispersed independently. .
[0009]
  Hereinafter, the present invention will be described in more detail.
  In the transparent conductive film 5 of the present invention, the conductive layer 2 is formed using a coating material in which massive aggregates of metal fine particles are uniformly dispersed as a whole, and is a thin film having a thickness of 5 nm to 500 nm. Regardless, the surface resistance is 1 × 10⁴Maintains high conductivity of Ω / □ or less, and
Average transmittance of visible light is 80% or moreIt has a high light transmittance.
[0010]
The reason why the conductive layer 2 has high conductivity and high light transmittance is not necessarily clear, but the conductive aggregates are baked in a state where the contact electric resistance is smaller than that of the independently dispersed fine particles. Therefore, it is considered that a much better conductive path is formed with a small number of fine particles, and that the light gap is improved by forming a gap between the meshes larger than a uniform dispersion layer of independent dispersed fine particles. .
[0011]
It is particularly important that the particle diameters of the individual metal fine particles forming the massive aggregate are in the range of 1 nm to 100 nm. If the particle size of each metal fine particle is less than 1 nm, the properties as a metal are impaired and the electrical conductivity is lowered, and if it exceeds 100 nm, it is difficult to obtain a massive aggregate.
[0012]
As the metal fine particles used for the conductive layer 2, noble metal fine particles such as gold, silver, palladium, ruthenium, platinum, rhodium, iridium and osmium and metal fine particles such as copper and nickel are effective. In particular, it is preferable to use a combination of silver and palladium. In other words, silver is available as a colloidal dispersion relatively easily and inexpensively, and has high conductivity and excellent antistatic properties and electromagnetic wave shielding properties, thus reducing the cost of transparent conductive films while maintaining conductivity. This is effective in the case where it is desired to be used, and the chemical stability is increased by using it mixed with palladium, so that practically sufficient durability can be obtained. In consideration of conductivity and chemical stability, the blending ratio of silver and palladium is preferably in the range of 10% to 90% by weight of fine silver particles: 90% to 10% by weight of fine palladium particles.
[0013]
  As schematically shown in FIGS. 2 (a) and 2 (b), a mass aggregate of metal fine particles is formed of a plurality of metal fine particles.AgglomeratedFor example, as shown in FIG. 2 (a), metal fine particles (primary particles) 6 having a particle diameter of 1 nm to 5 nm are aggregated in a lump to form a lump aggregate (secondary particles) 7 having a particle diameter of 100 nm to 150 nm. Alternatively, as shown in FIG. 2B, the metal fine particles 6 having a particle size of 20 nm to 50 nm aggregate in a lump to form a lump aggregate 7 having a particle size of 100 nm to 150 nm. The diameter is in the range of 1 nm to 100 nm, and the particle size of the aggregate 7 is preferably in the range of 30 nm to 500 nm, more preferably in the range of 70 nm to 300 nm, from the viewpoints of conductivity and transparency. If the particle size of the massive aggregate is less than 50 nm, the electrical resistance between the particles becomes large and sufficient conductivity cannot be obtained, and if it exceeds 500 nm, the light scattering degree may increase and the transparency of the coating film may be impaired. .
[0014]
  When a coating material containing this aggregate is applied onto a substrate, dried and baked at a temperature in the range of 100 ° C. to 1000 ° C., a film is formed between the particles.Contact resistanceIs a thin film in which the conductive layer 2 is 5 nm to 500 nm.EvenSurface resistance value is 1 × 10⁴High conductivity of Ω / □ or less is obtained. As a result, the antistatic effect and electromagnetic wave shielding effect are excellent.Average transmittance of visible light is 80% or moreThus, a transparent conductive film having high transparency and less noticeable film thickness unevenness can be obtained.
[0015]
  In producing a coating material containing the above-mentioned aggregated aggregate (hereinafter referred to as “the present coating material”), first, a dispersion containing the above-mentioned aggregated aggregate is prepared. The aggregate aggregate dispersion can be prepared by various methods.(1)Desalting method,(2)Heat treatment method,(3)The mixing method etc. can be mentioned. A dispersion of fine metal particles (primary particles) used in these methods is obtained by known methods such as pulverizing metals.Dispersion mediumBy a method of dispersing in a colloid or by colloid formationDispersion mediumCan be prepared by a method of generating metal fine particles in
.
  Hereinafter, a typical method for preparing a massive aggregate dispersion will be described.
[0016]
  (1)Desalting treatment method: Bulk aggregates are formed by desalting the dispersion of metal fine particles. When performing a desalting process, it carries out in the state containing 1 or more types of metal microparticles. Specific examples of the desalting treatment method include a method of desalting the metal fine particle dispersion with a dialysis membrane, and a method of desalting the metal fine particle dispersion by ultrafiltration. The particle size of the massive aggregate can be adjusted by the desalting treatment method and the desalting treatment amount, and a suitable desalting treatment method and desalting treatment method can be selected in advance by experiments.
[0017]
  (2)Heat treatment method: Bulk aggregates are obtained by heat-treating the metal fine particle dispersion at a temperature of 50 ° C. or higher. In this heat treatment methodIsThe particle size of the bulk aggregate can be adjusted by the heat treatment time, temperature, blending ratio of the dispersion medium, and the like, and suitable conditions can be selected in advance by experiments. Dispersion medium when forming agglomeratesAsContains 5% to 95% by weight of water, 5% to 95% by weight of alcohol, and 1% by weight or more of cellosolve solventDispersion mediumWhen is used, a massive aggregate can be easily formed, which is preferable.
[0018]
  (3)Mixing method: Agglomerates are obtained by mixing alcohol, water, and cellosolve solvent in the metal fine particle dispersion. In this mixing method, the particle size of the massive aggregate isDispersion mediumThe mixing ratio, mixing order, charging speed, temperature, pH, stirring speed and the like can be adjusted, and suitable conditions can be selected in advance through experiments. As a dispersion medium, 5% to 95% by weight of water, 5% to 95% by weight of alcohol, and 1% by weight or more of cellosolve solvent are included.Dispersion mediumIs preferably used because agglomerates are easily formed.
[0019]
The display device of the present invention is obtained by applying at least the present paint, and a transparent conductive film 5 having a conductive layer 2 preferably having a thickness in the range of 5 nm to 500 nm is formed on the display surface 1. . This transparent conductive film 5 has an average visible light transmittance of 70% or more and small absorption at a specific wavelength, so that the hue of the transmitted image is not impaired, and the excellent antistatic effect that is the object of the present invention is obtained. An electric field shielding effect can be obtained, and it has a practically sufficient level of resistance against salt water, and the film thickness unevenness of the coating film becomes inconspicuous due to its high light transmittance.
[0020]
  The conductive layer 2 may contain silica fine particles having an average particle diameter of 100 nm or less in the range of 1% by weight to 60% by weight with respect to the bulk aggregate in addition to the bulk aggregate. The conductive layer 2 obtained by applying the transparent conductive film-forming coating material containing silica fine particles to form a film has significantly improved film strength and improved scratch strength. Moreover, by making the conductive layer 2 contain silica fine particles,In the upper layer, or the lower layer, or the upper layer and the lower layer,In the case where one or more transparent layers 3 having a refractive index different from the refractive index of the conductive layer are provided, the wettability of the transparent layer 3 with the silica-based binder component is good, so that the adhesion between both layers is improved. Therefore, the scratch strength can be further improved. The silica fine particles are more preferably contained in the range of 20% by weight to 40% by weight with respect to the bulk aggregate from the viewpoint of achieving both improvement in film strength and conductivity.
[0021]
In addition to the above-described components, the conductive layer 2 may contain other components such as silicon, aluminum, zirconium, cerium, titanium, yttrium, zinc, magnesium, indium, tin, antimony, if necessary, for the purpose of improving film strength and conductivity. , Oxides such as gallium, composite oxides or nitrides, in particular, fine particles of inorganic materials mainly containing oxides of indium and tin, composite oxides or nitrides, polyester resins, acrylic resins, epoxy resins, melamine resins Contains organic synthetic resins such as urethane resin, butyral resin, ultraviolet curable resin, hydrolysates of metal alkoxides such as silicon, titanium and zirconium, or organic and inorganic binder components such as silicone monomers and silicone oligomers. Also good.
[0022]
In order to apply this paint on a substrate, any of ordinary thin film coating techniques such as spin coating, roll coating, spray coating, bar coating, dip coating, meniscus coating, and gravure coating can be used. Among these, spin coating is a particularly preferable coating method because a thin film having a uniform thickness can be formed in a short time. After coating, the coating film is dried and baked at 100 ° C. to 1000 ° C., whereby the conductive layer 2 is formed on the surface of the substrate.
[0023]
In determining the content and film thickness of the massive aggregates (metal fine particles) in the conductive layer 2, it is necessary to consider the requirements for the electromagnetic wave shielding effect.
In general, in order to exhibit an electromagnetic wave shielding effect in addition to the antistatic effect, the conductivity of the transparent conductive film 5 is 10^ThreeA volume resistivity (ρ) of the order of Ω · cm or less is required. That is, as the volume specific resistance (ρ) of the transparent conductive film 5 is as low as possible, electromagnetic waves having a wider frequency range can be effectively shielded. In order to satisfy this condition, it is preferable to set the film thickness of the conductive layer 2 in the transparent conductive film to 50 nm or more, and to further contain 10% by weight or more of the massive aggregate. When the film thickness of the conductive layer 2 is less than 50 nm or the content of the aggregated aggregate is less than 10% by weight, the conductivity is lowered and it is difficult to obtain a substantial electromagnetic wave shielding effect.
In consideration of transparency, the film thickness of the conductive layer 2 in the transparent conductive film is preferably 500 nm or less after satisfying the above conditions.
[0024]
  The transparent conductive film 5 of the present invention isUpper layer or lower layer of conductive layer 2, or upper and lower layersIt is preferable that at least one transparent layer 3 is laminated on the upper layer in FIG. The transparent layer 3 preferably has a refractive index different from that of the conductive layer 2. This not only protects the conductive layer 2 but also effectively removes or reduces external light reflection at the interlayer interface of the obtained transparent conductive film 5.
  The transparent layer 3 not only prevents interface reflection in the multilayer thin film but also has an effect of protecting the surface from external force when used for a display surface of a display device. It is further preferable to have
[0025]
Examples of the material for forming the transparent layer 3 include thermoplastic, thermosetting, or light to electron beam curable resins such as polyester resin, acrylic resin, epoxy resin, and butyral resin; metals such as silicon, aluminum, titanium, and zirconium. Alkoxide hydrolyzate; silicone monomers or silicone oligomers can be used alone or in combination.
[0026]
A particularly preferred transparent layer is SiO having a high film surface hardness and a relatively low refractive index.₂ It is a thin film. This SiO₂ Examples of materials that can form a thin film include, for example:
M (OR)_mR_n
(Wherein M is Si and R is C₁~ C_FourM is an integer of 1 to 4, n is an integer of 0 to 3, and m + n is 4.)
Or a mixture of one or more of the partial hydrolysates thereof.
Examples of compounds of the above formula are in particular tetraethoxysilane (Si (OC₂H_Five)_Four) Is preferably used from the viewpoints of thin film forming ability, transparency, bondability with a conductive layer, film strength, and antireflection performance.
[0027]
The transparent layer 3 may include various resins, metal oxides, composite oxides, nitrides, etc., or precursors that can generate these by baking, as long as the refractive index can be set to a different refractive index from the conductive layer. Good.
[0028]
The formation of the transparent layer 3 can be performed by a method of forming a film by uniformly applying a coating liquid containing the above-described components (a transparent layer forming coating material) in the same manner as the method used for forming the conductive layer 2. For the application, any of ordinary thin film coating techniques such as spin coating, roll coating, spray coating, barcode coating, dip coating, meniscus coating, and gravure coating can be used. Among these, spin coating is a particularly preferable coating method because a thin film having a uniform thickness can be formed in a short time. After coating, the coating film is dried, and the transparent layer 3 is obtained by baking at 100 ° C. to 1000 ° C.
[0029]
In general, the interlayer interface antireflection performance in a multilayer thin film is determined by the refractive index and film thickness of the thin film, and the number of laminated thin films. Therefore, even in the transparent conductive film of the present invention, the total number of laminated layers of the conductive layer and the transparent layer. By designing the thickness of each conductive layer and transparent layer in consideration of the above, an effective antireflection effect can be obtained. In a multilayer film having antireflection ability, when the wavelength of reflected light to be prevented is λ, a high refractive index layer and a low refractive index are respectively set to λ / Reflection can be effectively prevented by using an optical film thickness of 4, λ / 4, or λ / 2, λ / 4. In the case of a three-layer antireflection film, the optical film thicknesses are λ / 4, λ / 2, and λ / 4 in the order of the medium refractive index layer, the high refractive index layer, and the low refractive index layer from the substrate side. Is considered valid.
[0030]
In particular, considering the ease of manufacturing and economic efficiency, as shown in FIG. 1, the upper layer of the conductive layer 2 has a relatively low refractive index and has a hard coat property.₂It is preferable to form the film (refractive index 1.46) with a film thickness of λ / 4.
[0031]
In the transparent conductive film of the present invention including a conductive layer and one or more transparent layers, the conductive layer and the transparent layer may be baked sequentially or simultaneously. For example, this paint (paint for forming a transparent conductive film) is applied to the display surface of a display device, the paint for forming a transparent layer is applied to the upper layer, and dried, and then collectively baked at a temperature of 100 ° C. to 1000 ° C. A layer and a transparent layer can be formed simultaneously to form a low reflective transparent conductive film.
[0032]
The outermost layer of the transparent conductive film 5 is preferably provided with an uneven transparent layer (uneven layer) 4. The concavo-convex layer 4 has an effect of scattering the surface reflected light of the transparent conductive film 5 and imparting an excellent antiglare property to the display surface. As the material of the uneven layer 4, silica is suitable from the viewpoint of surface hardness and refractive index. The concavo-convex layer 4 is formed by applying the concavo-convex layer-forming paint as the outermost layer of the transparent conductive film 5 by the various coating methods described above, and after drying, simultaneously with or separately from the conductive layer 1 or the transparent layer 2. It can be formed by baking at a temperature of 1000 ° C. In particular, spray coating is suitable as a method for applying the uneven layer 4. In addition, it is desirable that the height difference between the concave and convex portions of the unevenness is 5 nm or more and 500 nm or less.
[0033]
At least one layer of the transparent conductive film 5 of the present invention may contain a coloring material. This coloring material is used for improving the contrast of a transmission image and adjusting the colors of transmitted light and reflected light. Examples of the coloring material include monoazo pigment, quinacridone, iron oxide yellow, disazo pigment, phthalocyanine green, phthalocyanine blue, cyanine blue, flavanthrone yellow, dianthraquinolyl red, indanthrone blue, thioindigo Bordeaux, perylene orange. Perylene scarlet, perylene red 178, perylene maroon, dioxazine violet, isoindoline yellow, nickel nitroso yellow, madder lake, copper azomethine yellow, aniline black, alkali blue, zinc white, titanium oxide, petal, chromium oxide, iron Black, Titanium Yellow, Cobalt Blue, Cerulean Blue, Cobalt Green, Alumina White, Viridian, Cadmium Yellow, Cadmium Red, Zhu, Lito , Yellow lead, molybdate orange, zinc chromate, calcium sulfate, barium sulfate, calcium carbonate, lead white, ultramarine, manganese violet, emerald green, bitumen, carbon black and other organic and inorganic pigments, and azo dyes, anthraquinone dyes And dyes such as indigoid dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, quinoline dyes, nitro dyes, nitroso dyes, benzoquinone dyes, naphthoquinone dyes, naphthalimide dyes, and perinone dyes. These colorants can be used alone or in combination of two or more.
[0034]
When using a colorant, the type and amount thereof should be appropriately selected in accordance with the optical film characteristics of the corresponding transparent conductive film. The absorbance A of the transparent thin film is generally represented by the following formula.
A = log_Ten(I₀/ I) = εCD
Where I₀Incident light, I; transmitted light, C; color density, D; light distance, ε; molar extinction coefficient
It is.
[0035]
When a colorant is used in the transparent conductive film of the present invention, a colorant having a molar extinction coefficient of ε> 10 is generally used. The blending amount of the colorant varies depending on the molar extinction coefficient of the colorant to be used, but the absorbance A of the laminated film or single layer film blended with the colorant is in the range of 0.0004 to 0.0969 abs. Preferably, the amount is such that When these conditions are not satisfied, the transparency and / or antireflection effect is lowered. When the colorant is blended in the conductive layer 2, the blending amount is preferably 20% by weight or less, particularly preferably 10% by weight or less based on the metal content. If it exceeds 10% by weight, a decrease in conductivity is observed, and if it exceeds 20% by weight, the electromagnetic wave shielding effect is hindered.
[0036]
In the display device of the present invention, any one of the transparent conductive films 5 is formed on the display surface 1. In this display device, since the display surface 1 is prevented from being charged, dust or the like does not adhere to the display surface, and electromagnetic waves are shielded, so that various electromagnetic interferences are prevented and light transmission is excellent, so that an image is displayed. It is bright and has a natural hue in the transmitted image, and since the film thickness is uniform, uneven coating on the display surface is inconspicuous, and the salt water resistance is high, so that it is highly durable even in an environment where it is exposed to salt fog. If the transparent layer 3 and / or the concavo-convex layer 4 is formed in addition to the conductive layer 2, an excellent antireflection effect and / or antiglare effect against external light can be obtained.
[0037]
【Example】
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
The following were prepared as a metal fine particle dispersion common to the examples and comparative examples.
(Silver fine particle dispersion)
An aqueous solution (25 g) in which silver nitrate (2.5 g) is dissolved in an aqueous solution (60 g) in which sodium citrate dihydrate (14 g) and ferrous sulfate (7.5 g) are dissolved at 5 ° C. ) To obtain a reddish brown silver sol. The silver sol was washed with water by centrifugal separation to remove impurity ions to obtain a silver fine particle dispersion. In this silver fine particle dispersion, silver fine particles having a particle diameter in the range of 1 nm to 10 nm were dispersed independently.
(Palladium fine particle dispersion)
Pre-desalted palladium fine particles (5 g), a dispersant (1 g), butyl cellosolve (10 g) and water (84 g) were mixed and dispersed using an ultrasonic disperser to obtain a palladium fine particle dispersant. In this fine palladium particle dispersant, fine palladium particles having a particle size in the range of 1 nm to 10 nm were dispersed independently.
(Transparent layer forming paint A)
Tetraethoxysilane (0.8 g), 0.1N hydrochloric acid (0.8 g), and ethyl alcohol (98.4 g) were mixed to obtain a uniform solution.
[0038]
Example 1
Preparation of this paint (paint for forming transparent conductive film)
[Coating composition]
0.05% by weight of silver
0.05% by weight of palladium
Ethyl cellosolve 5% by weight
Butyl cellosolve 10% by weight
10% by weight of methanol
74.9% by weight of water
[Formation of massive aggregates]
In water (10 ° C), methanol at 5 ° C, the above silver fine particle dispersion, the above palladium fine particle dispersion, ethyl cellosolve, and butyl cellosolve were added and mixed in 60 minutes. Prepared.
In this coating material, most of the silver fine particles and palladium fine particles were aggregated, and as a result of measurement by a laser Doppler method, a bulk aggregate having a particle size in the range of 100 nm to 150 nm was obtained.
[0039]
Film formation
The above paint is applied to the display surface of the cathode ray tube using a spin coater, and after drying, the coating material A for forming the transparent layer is similarly applied to the application surface using a spin coater. The cathode ray tube of Example 1 having an antireflective transparent conductive film was prepared by baking and forming a transparent conductive film by baking at 150 ° C. for 1 hour.
[0040]
(Example 2)
Preparation of the paint
[Coating composition]
Silver 0.08% by weight
Palladium 0.12% by weight
Ethyl cellosolve 1% by weight
Butyl cellosolve 10% by weight
50% by weight of methanol
38.8% by weight of water
[Formation of massive aggregates]
This paint having the above composition was prepared according to Example 1. In this paint, most of the silver fine particles and palladium fine particles were aggregated to form a massive aggregate having a particle size in the range of 150 nm to 200 nm.
[0041]
Film formation
Using this paint and the transparent layer forming paint A, a cathode ray tube of Example 2 having an antireflection transparent conductive film was prepared in the same manner as in Example 1.
[0042]
(Example 3)
Preparation of the paint
[Coating composition]
Silver 0.18% by weight
Palladium 0.12% by weight
Ethyl cellosolve 1% by weight
Ethanol 83.7% by weight
15% water
[Formation of massive aggregates]
Sequentially add ethanol of 5 ° C., the above-mentioned silver fine particle dispersion, the above-mentioned palladium fine particle dispersion, and ethyl cellosolve in water (10 ° C.) in accordance with Example 1 to prepare this paint having the above composition. did. In this coating material, most of the silver fine particles and palladium fine particles were aggregated to form a massive aggregate having a particle size in the range of 100 nm to 150 nm.
[0043]
Film formation
A cathode ray tube of Example 3 having an antireflection transparent conductive film was prepared by using the present coating material and the coating material A for forming a transparent layer in the same manner as in Example 1.
[0044]
(Comparative Example 1)
Preparation of paint for forming transparent conductive film
The coating composition was the same as in Example 1, silver fine particle dispersion, palladium dispersion, ethyl cellosolve, butyl cellosolve, methanol and water were mixed, and the resulting mixture was mixed with an ultrasonic disperser ("SONIFIER 450" manufactured by BRANSON ULTRASONICS). ]) To prepare a transparent conductive film-forming coating material of Comparative Example 1. In the paint of Comparative Example 1, it was confirmed by observation by TEM that silver fine particles and palladium fine particles were dispersed independently and uniformly and almost no aggregates were formed.
[0045]
Film formation
Using the transparent conductive film-forming paint of Comparative Example 1 and the transparent layer-forming paint A, a cathode ray tube of Comparative Example 1 having an antireflective transparent conductive film was prepared in the same manner as in Example 1.
[0046]
(Comparative Example 2)
Preparation of paint for forming transparent conductive film
The coating composition is the same as in Example 2, and silver fine particle dispersion, palladium dispersion, ethyl cellosolve, butyl cellosolve, methanol and water are mixed and treated in the same manner as in Comparative Example 1 to form a transparent conductive film forming paint of Comparative Example 2. Was prepared. In the paint of Comparative Example 2, it was confirmed by observation by TEM that the silver fine particles and the palladium fine particles were dispersed independently and uniformly and almost no aggregates were formed.
[0047]
Film formation
Using the transparent conductive film-forming coating material of Comparative Example 2 and the transparent layer-forming coating material A, a cathode ray tube of Comparative Example 2 having an antireflection transparent conductive film was prepared in the same manner as in Example 1.
[0048]
(Comparative Example 3)
Preparation of paint for forming transparent conductive film
The coating composition was the same as in Example 3, and a silver fine particle dispersion, palladium dispersion, ethyl cellosolve, ethanol and water were mixed and treated in the same manner as in Comparative Example 1 to prepare a transparent conductive film forming coating of Comparative Example 3. did. In the paint of Comparative Example 3, it was confirmed by observation by TEM that silver fine particles and palladium fine particles were dispersed independently and uniformly and almost no aggregates were formed.
[0049]
Film formation
Using the transparent conductive film-forming coating material of Comparative Example 3 and the transparent layer-forming coating material A, a cathode ray tube of Comparative Example 3 having an antireflective transparent conductive film was prepared in the same manner as in Example 1.
[0050]

The above evaluation test results are shown in Tables 1 and 2.
[0051]
[Table 1]

[Table 2]

[0052]
From the results of Tables 1 and 2 above, the cathode ray tubes of Examples 1 to 3 formed by applying the present paint containing agglomerates of metal fine particles were compared with conventional uniformly dispersed metal fine particles. It can be seen that the surface resistance is small despite the film thickness equivalent to that of Example 1 to Comparative Example 3. As a result, when the surface resistance is set to the same level, the thickness of the conductive layer can be reduced, so that the transparency of the transparent conductive film is excellent and the transparency is high.
Moreover, the transparent conductive film formed using this coating material was also excellent in scratch resistance. Regarding the transmittance difference, the visibility, and the film unevenness, good results equivalent to those of Comparative Examples 1 to 3 including conventional uniformly dispersed metal fine particles are obtained.
[0053]
【The invention's effect】
  According to the present invention,The formed transparent conductive film has a very thin conductive layer.ofDespite its high average transmittance, it excels in electromagnetic wave shielding and antistatic effects. Especially when agglomerates of silver fine particles and palladium fine particles are used, the hue of the transmitted image is natural, and representative of salt water resistance. Durability is also excellent. Therefore, the display device of the present invention in which this transparent conductive film is formed on the display surface has a natural hue of the transmitted image, excellent antistatic properties, electromagnetic wave shielding properties and durability, and high light transmittance. For this reason, the transmitted image is bright and the film thickness unevenness of the coating film is not noticeable.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view showing an embodiment of a display device of the present invention.
FIGS. 2A and 2B are conceptual diagrams schematically showing massive aggregates of metal fine particles.
[Explanation of symbols]
1: Display surface
2: Conductive layer
3: Transparent layer
4: Uneven layer
5: Transparent conductive film
6: Metal fine particles
7: Bulk aggregate

Claims (7)

A coating for forming a transparent conductive film in which at least agglomerates of fine metal particles are dispersed in a dispersion medium as a conductive material,
A coating material for forming a transparent conductive film, wherein a particle diameter of the metal fine particles is in a range of 1 nm to 100 nm, and a particle diameter of the massive aggregate is in a range of 70 nm to 300 nm . The metal fine particles include at least silver fine particles and palladium fine particles, and the blending ratio of the silver fine particles and the palladium fine particles is within a range of 10% by weight to 90% by weight of silver fine particles: 90% by weight to 10% by weight of palladium fine particles. The paint for forming a transparent conductive film according to claim 1, wherein: A transparent conductive film comprising a conductive layer formed by applying the paint for forming a transparent conductive film according to claim 1 .   4. The transparent conductive film according to claim 3, wherein the thickness of the conductive layer is in the range of 5 nm to 500 nm. 5. The transparent conductive film according to claim 3 , wherein at least one transparent layer having a refractive index different from that of the conductive layer is laminated on the upper layer, the lower layer, or the upper layer and the lower layer of the conductive layer. The average transmittance of visible light is 80% or more , and the surface resistance is 1 × 10 ⁴
The transparent conductive film according to claim 3, 4 or 5, wherein it is Ω / □ or less. 7. A display device comprising the transparent conductive film according to claim 3 formed on a display surface.

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