JP2002003746A - Coating for forming transparent electroconductive film, transparent electroconductive film and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating for forming a transparent electroconductive film for providing a display device having the transparent electroconductive film excellent in electromagnetic wave shielding effects and antireflection effects, having a natural hue of a transmitted image and weather resistance represented by salt water resistance and excellent in light transmissivity with extremely slight defects by aggregates, etc., of coating components even in the appearance of a coated film. SOLUTION: This coating for forming the transparent electroconductive film is obtained by including a liquid having the boiling point within the range of 150-250 deg.C under 1 atom and >=20 permittivity at 20 deg.C in the coating for forming the transparent electroconductive film containing metal fine particles dispersed therein.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paint for forming a transparent conductive film, a transparent conductive film, and a display device having the transparent conductive film formed on a display surface. In particular, the present invention relates to a display surface such as a cathode ray tube or a plasma display. It has excellent antistatic effect, electromagnetic wave shielding effect and antireflection effect, natural color of transmitted image, good weather resistance typified by salt water resistance, excellent light transmittance and coating film. The present invention relates to a transparent conductive film having very few defects due to agglomerates of paint components in appearance, a transparent conductive film forming paint used for forming the transparent conductive film, and a display device having the transparent conductive film formed on a display surface. .

[0002]

2. Description of the Related Art A cathode ray tube, which is a kind of display device used as a TV cathode ray tube or a display for a computer, etc., emits an electron beam on a phosphor screen which emits red, green, and blue light to display characters and images. Is projected on the display surface, and if static electricity is generated on the display surface, dust adheres to the display surface, lowering visibility, and radiating electromagnetic waves to affect the environment. Recently, it has been pointed out that a plasma display, which is being applied to a wall-mounted television or the like, may generate static electricity or emit electromagnetic waves.

[0003] In order to solve these problems, for example, Japanese Patent Application Laid-Open No. 8-77832 discloses a transparent conductive film having an excellent electromagnetic wave shielding effect and an anti-reflection effect, having an average particle diameter of 2 nm to 200 nm.
It proposes a transparent metal thin film made of metal fine particles containing at least silver of nm and a transparent thin film having a different refractive index.

[0004]

However, in the above-mentioned conventional device, although an electromagnetic wave shielding effect can be expected, absorption occurs in transmitted light having a wavelength in the range of 400 nm to 500 nm depending on the light transmission spectrum of silver, resulting in an increase in conductivity. The problem is that the film is colored yellow and the hue of the transmitted image changes unnaturally, the dispersion stability of the coating solution is poor, and film defects are generated on the coating film due to agglomerates of fine metal particles, and salt water. If immersed for more than 3 days, the surface resistance of the conductive film will increase and the electromagnetic wave shielding effect will decrease. Was. The present invention has been made in order to solve the above-mentioned problems, and therefore, has as its object an excellent electromagnetic wave shielding effect and anti-reflection effect, a natural hue of a transmitted image, and weather resistance represented by salt water resistance. A transparent conductive film which is excellent in light transmittance and has very few film defects due to agglomerates of paint components in the appearance of the coating film; a transparent conductive film forming paint used for forming the transparent conductive film; It is to provide a display device in which a conductive film is formed on a display surface.

[0005]

In order to solve the above-mentioned problems, the present invention relates to a coating material in which metal fine particles are dispersed,
Provided is a coating material for forming a transparent conductive film, which contains a liquid having a boiling point under atmospheric pressure of 150 ° C. to 250 ° C. and a dielectric constant at 20 ° C. of 20 or more. The liquid is N-
At least one selected from the group consisting of methyl-2-pyrrolidinone, ethylene glycol, diethylene glycol, propylene glycol, formamide, N-methylformamide, N, N-dimethylformamide, N-methylacetamide, and N, N-dimethylacetamide It is preferred that In addition, the boiling point under 1 atm
Dielectric constant within the range of 250 ° C. and 20 ° C. is 1
It is preferable not to contain a liquid of 0 or less. The metal fine particles are preferably at least one selected from the group consisting of gold fine particles, silver fine particles, and platinum group metal fine particles. It is preferable that at least a part of the metal fine particles form a chain aggregate. Preferably, at least a portion of the chain aggregate has a length in the range of 5 nm to 200 nm.

The present invention also provides a transparent conductive film including a conductive layer formed by using any of the above-mentioned paints for forming a transparent conductive film. This transparent conductive film has an excellent antistatic effect and an electromagnetic wave shielding effect by including a conductive layer formed using the transparent conductive film forming paint, and has a natural hue of a transmitted image and is represented by salt water resistance. The resulting coating film has good weather resistance and extremely few film defects due to agglomerates of paint components.

It is preferable that at least one transparent layer having a refractive index different from that of the conductive layer is laminated on the upper and / or lower layers of the conductive layer. By the lamination of the transparent layers, the antireflection performance of the transparent conductive film is improved, and reflection of external light and haze are extremely reduced.

The present invention further provides a display device in which the transparent conductive film is formed on a display surface. This display device has an excellent antistatic effect and an electromagnetic wave shielding effect by forming the transparent conductive film on the display surface, has a natural hue of a transmitted image, and has good weather resistance represented by salt water resistance. In the appearance of the coating film, film defects due to agglomerates of paint components and the like are extremely small. Further, if the transparent conductive film has the transparent layer, the antireflection effect is improved and the visibility is further improved.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to preferred specific examples. The present inventors have conducted intensive studies on a paint containing metal fine particles, and a transparent conductive film formed by applying the paint, in order to impart excellent visibility and an electromagnetic wave shielding effect to the display surface of the display device. As a result, the boiling point under one atmosphere is 150 ° C., especially with the metal fine particles.
When a transparent conductive film is formed using a transparent conductive film forming paint containing a liquid having a dielectric constant of 20 or more within a range of 250 ° C. and a temperature of 20 ° C., a film resulting from massive aggregates on the coating film The present inventors have found that a transparent conductive film having extremely few defects and having excellent conductive performance and antireflection performance can be formed, and arrived at the present invention.

The coating for forming a transparent conductive film of the present invention is a dispersion of fine metal particles, and this dispersion medium is generally composed of a mixture of several solvents having different boiling points. When the coating material for forming a transparent conductive film is applied to a substrate, the composition of the dispersion medium changes such that the concentration of the high-boiling solvent increases with the concentration of the metal fine particles during the drying of the solvent. The characteristics of the dispersion medium that remains under the condition that the metal fine particles are present at a high concentration greatly affect the dispersion state of the metal fine particles. When the concentration of the metal fine particles becomes high, the boiling point under one atmosphere is 150 ° C. to 250 ° C.
When a liquid having a dielectric constant within 20 ° C. and a dielectric constant at 20 ° C. of 20 or more is present as a dispersion medium, the finally formed film does not aggregate metal fine particles in a lump, is excellent in light transmission, and It was found that the conductivity was good and the antistatic effect and the electromagnetic wave shielding effect were excellent.

[0011] When a liquid having a high boiling point and a high dielectric constant is present, the reason why metal fine particles do not agglomerate in a lump and a film excellent in both translucency and conductivity is obtained is not clear, but the coating area during the drying process is not clear. When the amount of the dispersion medium per unit decreases, the molecules of the high-boiling solvent having a high dielectric constant remain agglomerated in an island shape while excluding the highly conductive fine metal particles to the surroundings. Connected to each other around the island,
It is considered that a conductive path having a network structure is formed while forming a translucent window in which no metal fine particles are present. On the other hand, when a solvent having a high boiling point and a low dielectric constant is present at the end of drying, the network structure of the metal fine particles is not sufficiently developed, and both the conductivity and the visibility of the formed transparent conductive film become insufficient. When the paint does not contain a high boiling point solvent, the metal fine particles tend to agglomerate in a lump, resulting in a decrease in conductivity and an increase in film defects due to lumpy coarse particles. From this point of view, as a result of research on the effects of the boiling point and dielectric constant of the solvent on the film properties, 1
A high-boiling solvent having a boiling point in the range of 150 ° C. to 250 ° C. under atmospheric pressure and a dielectric constant at 20 ° C. of 20 or more, a transparent conductive material having satisfactory conductivity, visibility, and film defects. It was found that a film was obtained. Examples of solvents that meet this condition include, but are not limited to, N-
Methyl-2-pyrrolidinone (boiling point 202 ° C./1 atm, dielectric constant 32.0 / 20 ° C.), ethylene glycol (boiling point 1
98 ° C / 1 atm, dielectric constant 38.0 / 20 ° C), diethylene glycol (boiling point 244.8 ° C / 1 atm, dielectric constant 3)
1.7 / 20 ° C.), propylene glycol (boiling point 18
7.3 ° C./1 atm, dielectric constant 32.0 / 20 ° C.), formamide (boiling point 210.0 ° C./1 atm, dielectric constant 111.0)
/ 20 ° C), N-methylformamide (boiling point 185.0)
° C / 1 atm, dielectric constant 182.4 / 20 ° C), N, N-dimethylformamide (boiling point 153.0 ° C / 1 atm, dielectric constant 36.7 / 20 ° C), N-methylacetamide (boiling point 206.0) ° C / 1 atm, dielectric constant 191.3 / 20 ° C),
N, N-dimethylacetamide (boiling point 166.1 ° C / 1
Atmospheric pressure and dielectric constant of 37.8 / 20 ° C.) were particularly effective.
The same result can be obtained by using a mixture of two or more of these. On the other hand, the boiling point under one atmosphere is 150 ° C to 25 ° C.
Liquid having a high boiling point in the range of 0 ° C. and a dielectric constant at 20 ° C. of 10 or less, for example, butyl cellosolve (ethylene glycol monobutyl ether; boiling point 1
70.2 ° C / 1 atm, dielectric constant 9.3 / 20 ° C)
As described above, since the conductivity and visibility of the transparent conductive film are deteriorated, it is preferable not to contain the transparent conductive film.

The metal fine particles contained in the paint for forming a transparent conductive film of the present invention may be at least one of gold fine particles, silver fine particles and platinum group metal fine particles from the viewpoints of conductivity, transparency and chemical stability. Preferably, there is. In particular, when two or more of these are appropriately mixed and used, their characteristics complement each other, and are excellent in weather resistance typified by the hue and salt water resistance of a transmitted image, relatively inexpensive, and have an antistatic effect and electromagnetic wave. A paint that forms a transparent conductive film having an excellent shielding effect can be obtained.

Further, it is preferable that at least a part of each of the metal fine particles form a chain aggregate in the coating material, and that the chain aggregate is uniformly dispersed as a whole in a dispersion medium. The conductive layer formed using the transparent conductive film forming paint has both particularly high conductivity and high light transmittance. Although the reason is not necessarily clear, the metal fine particles form a special structure in the formed conductor layer, that is, a fine network structure in which chain-like aggregates are entangled, and the contact resistance between the metal fine particles is suppressed to be small. It is considered that fine meshes (openings) are formed to obtain light transmittance.

The particle diameter of each metal fine particle forming a chain aggregate of the metal fine particles is preferably in the range of 1 nm to 10 nm. If the particle size of each metal fine particle is less than 1 nm, the properties as a metal are impaired and the conductivity is lowered, which is not preferable. If it exceeds 10 nm, island-like aggregates are easily formed and the conductivity may be lowered. Not preferred.

When a chain aggregate of metal fine particles is formed, the length is preferably in the range of 5 nm to 200 nm, and more preferably in the range of 10 nm to 100 nm from the viewpoint of transparency. preferable. If the length of the chain aggregate is less than 5 mm, the resistance between the particles increases and sufficient conductivity may not be obtained. If the length exceeds 200 nm, the light scattering degree increases and the transparency of the coating film may be impaired. Not preferred.

Various methods are conceivable for forming chain aggregates of metal fine particles. For example, when a metal aqueous sol is formed, an aqueous solution of a metal salt is adjusted to a pH within a range of 5 to 7, A method in which a reducing agent is added in an amount of 0.5 to 3 molar equivalents with respect to the metal ions is exemplified. In this method, when the pH of the aqueous metal salt solution is higher than 7, or when the amount of the reducing agent is more than 3 times the molar equivalent, the grain growth of the metal fine particles themselves proceeds excessively and precipitates. When the pH of the aqueous metal salt solution is less than 5, or when the amount of the reducing agent is less than 0.5 times the molar equivalent, monodispersed fine particles are generated or the reduction reaction does not proceed sufficiently to form metal fine particles. It is not preferable because it may not be performed.

In the transparent conductive film of the present invention, the conductive layer contains, in addition to the metal fine particles, silica fine particles having an average particle diameter of 100 nm or less in the range of 1% by weight to 60% by weight based on the metal fine particles. You may. The conductive layer formed by applying the coating material for forming a transparent conductive film containing silica fine particles has a remarkably improved film strength and improved scratch strength. Also,
By including silica fine particles in the conductive layer, when one or more transparent layers having a refractive index different from the refractive index of the conductive layer are provided in the upper layer and / or the lower layer, the transparent layer and the silica binder component of the transparent layer may be mixed. Since the wettability is good, there is also an advantage that the adhesion between both layers is improved, and the scratch strength can be further improved. The silica fine particles are more preferably in the range of 20% by weight to 40% by weight based on the metal fine particles, from the viewpoint of achieving both improvement in film strength and conductivity.

The coating material for forming a transparent conductive film may contain, if necessary, other components such as silicon, aluminum, zirconium, etc., for the purpose of improving film strength and conductivity, in addition to the above components.
Cerium, titanium, yttrium, zinc, magnesium, indium, tin, antimony, gallium and other oxides, composite oxides, or nitrides, especially indium or tin oxides, inorganic substances mainly containing composite oxides or nitrides Of fine particles, organic synthetic resin such as polyester resin, acrylic resin, epoxy resin, melamine resin, urethane resin, butyral resin, and ultraviolet curable resin, and metal alkoxide such as silicon, titanium and zirconium Or an organic / inorganic binder component such as a silicone monomer or silicone oligomer.

In order to apply the above-mentioned paint for forming a conductive layer containing at least metal fine particles on a substrate, a spin coating method is used.
Any of ordinary thin film coating techniques such as a roll coating method, a spray method, a bar coating method, a dip method, a meniscus coating method, and a gravure printing method can be used. Of these, spin coating is a particularly preferred coating method because a thin film having a uniform thickness can be formed in a short time. After the application, the conductive film can be formed on the surface of the substrate by drying the coating film and baking it at a temperature in the range of 100 ° C. to 1000 ° C., for example.

Here, the thickness of the conductor layer formed on the surface of the substrate will be described. The conductive property of the transparent conductive film required to exhibit the electromagnetic wave shielding effect in addition to the antistatic function is represented by the following equation 1. S = 50 + 10log (1 / ρf) + 1.7t√ (fρ) (1) where, S (dB); electromagnetic wave shielding effect, ρ (Ω · cm); volume resistivity of the conductive layer, f (MHz); Electromagnetic wave frequency, t (cm); thickness of conductive layer. Here, the thickness t is 1 μm (1 μm) from the viewpoint of light transmittance.
× 10 ⁻⁴ cm) or less, so that the expression 1
If the term including the film thickness t (cm) is ignored, the electromagnetic wave shielding effect S can be approximately expressed by the following equation (2). S = 50 + 10 log (1 / ρf) (2) Here, as the value of S (dB) increases, the electromagnetic wave shielding effect increases.

Generally, the electromagnetic wave shielding effect is S> 60.
If it is dB, it is considered to be excellent. In particular, regarding the conductive layer on the display surface, an electromagnetic wave shielding effect of S> 80 dB is desired. In addition, since the frequency of the electromagnetic wave to be regulated is generally in the range of 10 kHz to 1000 MHz, the conductivity of the transparent conductive film needs to have a volume resistivity (ρ) of 10 ³ Ω · cm or less. That is, the lower the volume specific resistance value (ρ) of the transparent conductive film, the more effectively electromagnetic waves of a wider range of frequencies can be shielded. In order to satisfy this condition, it is desirable that the thickness of the conductive layer in the transparent conductive film is 10 nm or more, and that the metal fine particles are contained at 10% by weight or more. If the film thickness is less than 10 nm or the content of the metal fine particles is less than 10% by weight, the conductivity is reduced, and it is difficult to obtain a substantial electromagnetic wave shielding effect.

In the transparent conductive film of the present invention, it is preferable that at least one transparent layer is laminated on the upper and / or lower layer of the conductive layer. The transparent layer preferably has a refractive index different from that of the conductive layer. This not only protects the conductive layer but also effectively removes or reduces external light reflection at the interlayer interface of the obtained transparent conductive film.

Examples of the material for forming the transparent layer include thermoplastic, thermosetting, or photo / electron beam curable resins such as polyester resin, acrylic resin, epoxy resin, and butyral resin; silicon, aluminum, titanium, zirconium, etc. A metal alkoxide hydrolyzate; a silicone monomer or a silicone oligomer is used alone or as a mixture.

A particularly preferred transparent layer is a SiO ₂ thin film having a high surface hardness and a relatively low refractive index. Examples of materials that can form this SiO ₂ thin film include, for example, the following formula: M (OR) _m R _n (where M is Si, R is a C _{1 to} C ₄ alkyl group,
m is an integer from 1 to 4, n is an integer from 0 to 3, and m
+ N is 4), or one or more mixtures of partial hydrolysates thereof. As an example of the compound of the above formula, in particular, tetraethoxysilane (Si (OC ₂ H ₅ ) ₄ ) is preferably used from the viewpoints of thin film formation, transparency, bonding with a conductive layer, film strength and antireflection performance. Used.

The transparent layer can be formed by various resins, metal oxides, metal composite oxides, metal nitrides, or the like, or by baking, as long as the transparent layer can have a refractive index different from that of the conductive layer. It may contain a possible precursor or the like.

The transparent layer is formed by a method in which a coating solution containing the above-mentioned components (a coating material for forming a transparent layer) is uniformly applied to a base material to form a film, similarly to the method used for forming the conductive layer. It can be carried out. For coating, any of ordinary thin film coating techniques such as spin coating, roll coating, spray coating, bar coating, dipping, meniscus coating, and gravure printing can be used. Of these, spin coating is a particularly preferred coating method because a thin film having a uniform thickness can be formed in a short time. After coating, the coating is dried and baked at a temperature preferably in the range of 100C to 1000C to obtain a transparent layer.

Generally, the inter-layer interface antireflection performance of a multilayer thin film is determined by the refractive index and thickness of the thin film and the number of laminated thin films. Also in the transparent conductive film of the present invention, an effective antireflection effect can be obtained by designing the thickness of each conductive layer and transparent layer in consideration of the number of stacked conductive layers and transparent layers. In the case of a multilayer film having antireflection ability, when the wavelength of the reflected light to be prevented is λ, if the antireflection film has a two-layer structure, the high refractive index layer and the low refractive index are respectively λ / from the substrate side. By setting the optical film thickness to 4, λ / 4, or λ / 2, λ / 4, reflection can be effectively prevented. In the case of a three-layer antireflection film, the optical film thicknesses should be λ / 4, λ / 2, λ / 4 in order of the medium refractive index layer, the high refractive index layer, and the low refractive index layer from the substrate side. Is valid. In particular, in consideration of ease of manufacture and economy, an SiO ₂ film (refractive index: 1.46) having a relatively low refractive index and also having a hard coat property is formed on the conductive layer at a thickness of λ / 4. Preferably, it is formed.

In the transparent conductive film of the present invention including a conductive layer and a transparent layer, the conductive layer and the transparent layer may be baked sequentially or simultaneously. For example, a conductive layer forming paint is applied to the display surface of the display device, a transparent layer forming paint is applied thereon, and after drying, baking is performed at a temperature within a range of 100 ° C. to 1000 ° C. to form a conductive layer. By forming a transparent layer at the same time, a low-reflection transparent conductive film can be formed.

It is preferable to provide a transparent layer having irregularities on the outermost layer of the transparent conductive film. The uneven layer has an effect of scattering light reflected on the surface of the transparent conductive film and giving excellent antiglare properties to the display surface. As the material of the uneven layer, silica is preferable from the viewpoint of surface hardness and refractive index. This concavo-convex layer is formed by applying a coating for forming a concavo-convex layer as the outermost layer of the transparent conductive film by the above-mentioned various coating methods, and after drying, simultaneously with or separately from the conductive layer or the transparent layer, or from 100 ° C.
It can be formed by baking at a temperature in the range of 1000 ° C. In particular, a spray coating method is suitable as a method for forming the uneven layer.

At least one of the transparent conductive films of the present invention
The layer may contain a coloring material. This coloring material
It is used to improve the contrast of a transmitted image and to adjust the color 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, and perylene orange. , Perylene scarlet, perylene red 178,
Perylylene maroon, dioxazine violet, isoindoline yellow, nickel nitroso yellow, madder lake, copper azomethine yellow, aniline black, alkali blue, zinc white, titanium oxide, red iron oxide, chrome oxide, iron black, titanium black, cobalt blue, cerulean Blue, cobalt green, alumina white, viridian, cadmium yellow, cadmium red, vermilion, lithopone, graphite, molybdate orange, zinc chromate, calcium sulfate, barium sulfate, calcium carbonate, lead white, ultramarine, manganese violet, emerald green Organic and inorganic pigments such as blue, blue and carbon black, and azo dyes, anthraquinone dyes, indigoid dyes, phthalocyanine dyes, carbonium dyes, quinone imine dyes, methine dyes, Phosphorus dyes, nitro dyes, nitroso dyes, benzoquinone dyes, naphthoquinone dyes, naphthalimide dyes, and dyes such as perinone dyes. These coloring materials can be used alone or in combination of two or more.

The type and amount of the coloring material to be used should be appropriately selected according to the optical film characteristics of the corresponding transparent conductive film. The absorbance A of a transparent thin film is generally represented by the following equation. A = log ₁₀ (I ₀ / I) = εCD where I ₀ is incident light, I is transmitted light, C is color density, D is light distance, and ε is molar extinction coefficient. In the transparent conductive film of the present invention, a coloring material having a molar absorption coefficient of ε> 10 is generally used. The amount of the coloring material varies depending on the molar extinction coefficient of the coloring material used, but the absorbance A of the laminated film and the single-layer film containing the coloring material is 0.0004 to 0.0969ab.
s. It is preferable that the amount is within the range of the above. If these conditions are not satisfied, the transparency and / or the antireflection effect will decrease. When the above-mentioned coloring material is used for the conductive layer, the compounding amount thereof is 20 parts based on the content of the metal fine particles.
It is preferably at most 10% by weight, especially at most 10% by weight. If it exceeds 10% by weight, a decrease in conductivity is observed,
If it exceeds 20% by weight, the electromagnetic wave shielding effect will be impaired.

In the display device of the present invention, any one of the transparent conductive films described above is formed on a display surface. This display device
Since the display surface is prevented from being charged, greetings and the like do not adhere to the image display surface, so that the electromagnetic waves are shielded, preventing various electromagnetic wave disturbances, and the image is bright because the light transmittance is excellent,
The hue of the transmitted image is natural, the appearance of the display surface is good, and the salt water resistance is high, so the durability is high even in an environment exposed to salt fog. If the transparent layer and / or the uneven layer are formed in addition to the conductive layer, an excellent antireflection effect and / or an antiglare effect against external light can be obtained.

[0033]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The following were prepared as stock solutions common to Examples and Comparative Examples described below. (Aqueous gold sol) containing 0.15 mmol / L chloroauric acid
An aqueous solution containing pH 5.7 and 0.15 mmol / L sodium borohydride are mixed, and the obtained colloidal dispersion is concentrated to obtain an aqueous solution containing 0.102 mol / L chain-like gold aggregate. A sol was obtained. (Silver aqueous sol) Sodium citrate dihydrate (14 g)
And ferrous sulfate (14 g) dissolved in a 5 ° C. aqueous solution (6
0 g) was added an aqueous solution (25 g) of pH 5.9 in which silver nitrate (2.5 g) was dissolved to obtain a red-brown silver sol. The silver sol was washed with water by centrifugation to remove impurity ions, and pure water was added to obtain an aqueous sol containing 0.185 mol / L silver fine particles. (Palladium aqueous sol) A pH 5.7 aqueous solution containing 0.15 mmol / L palladium chloride and 0.15 mmol / L sodium borohydride were mixed, and the obtained colloidal dispersion was concentrated. An aqueous sol containing 0.102 mol / L chain palladium aggregate was obtained. (Colloidal silica) “Silica Doll 30” manufactured by Nippon Chemical Industry Co., Ltd. (paint for forming a transparent layer) Tetraethoxysilane (0.8
g), 0.1 N hydrochloric acid (0.8 g) and ethyl alcohol (9
8.4 g) to give a homogeneous solution.

(Example 1) Preparation of paint for forming conductive layer: 4.5 g of the above-mentioned aqueous gold sol,
4 g of an aqueous silver sol, 8 g of an aqueous palladium sol, 0.2 g of colloidal silica, N-methyl-2-pyrrolidinone (boiling point 2
5 g of 02 ° C./1 atm, dielectric constant of 32.0 / 20 ° C.), 10 g of ethyl cellosolve (ethylene glycol monoethyl ether), and 68.3 g of ethyl alcohol were stirred and mixed to prepare a coating for forming a conductive layer. Au / Ag / in paint
The Pd weight ratio was 36/32/32, and the metal fine particle / SiO ₂ weight ratio was 100/20. As a result of observation by a transmission electron microscope, the fine metal particles having an average particle diameter of 6 nm aggregated in a chain. Aggregate lengths ranged from 20 nm to 90 nm. Film formation: The above-mentioned coating material for forming a conductive layer is applied to the display surface of a cathode ray tube using a spin coater, and after drying, the coating material for forming a transparent layer is applied to the application surface similarly using a spin coater. Put this CRT in a dryer, 150 ℃
For 1 hour to form a transparent conductive film, thereby producing a cathode ray tube of Example 1 having an antireflective transparent conductive film.

Example 2 Preparation of a paint for forming a conductive layer: 4.5 g of the above-mentioned aqueous gold sol,
4 g of an aqueous silver sol, 8 g of an aqueous palladium sol, 0.2 g of colloidal silica, ethylene glycol (boiling point: 198 ° C./1
Atmospheric pressure, dielectric constant: 38.0 / 20 ° C.) 5 g, ethyl cellosolve 10 g, and ethyl alcohol 68.3 g were stirred and mixed to prepare a coating for forming a conductive layer. Au / Ag / Pd in paint
The weight ratio was 36/32/32, and the weight ratio of metal fine particles / SiO ₂ was 100/20. As a result of observation with a transmission electron microscope, metal fine particles having an average particle size of 6 nm aggregated in a chain, and this chain Aggregate lengths were in the range of 20-90 nm. Film formation: Using the above-mentioned paint for forming a conductive layer, the same treatment as in Example 1 was carried out to produce a cathode ray tube of Example 2 having an antireflective transparent conductive film.

Comparative Example 1 Preparation of paint for forming conductive layer: 4.5 g of the above gold aqueous sol,
4 g of an aqueous silver sol, 8 g of an aqueous palladium sol, 0.2 g of colloidal silica, 5 g of butyl cellosolve (ethylene glycol monobutyl ether, boiling point: 170.2 ° C./1 atm, dielectric constant: 9.3 / 20 ° C.), 10 g of ethyl cellosolve, and ethyl alcohol 68.3 g was stirred and mixed to prepare a coating for forming a conductive layer. The Au / Ag / Pd weight ratio in the paint is 36.
/ 32/32, metal fine particle / SiO ₂ weight ratio is 100/20
As a result of observation with a transmission electron microscope, metal fine particles having an average particle diameter of 6 nm were aggregated in a chain, and the length of the chain aggregate was in the range of 20 nm to 90 nm. Film formation: The cathode ray tube of Comparative Example 1 having an anti-reflective transparent conductive film was prepared by using the above-mentioned paint for forming a conductive layer and treating in the same manner as in Example 1.

Comparative Example 2 Preparation of paint for forming conductive layer: 15 g of aqueous gold sol, 2 g of silver aqueous sol, 0.2 g of colloidal silica, 10 g of ethyl cellosolve, and 72.8 g of ethyl alcohol were stirred and mixed. The same treatment as in Example 1 was carried out to prepare a conductive layer forming paint. The weight ratio of Au / Ag in the paint was 88/12, and the weight ratio of fine metal particles / SiO ₂ was 100/20. As a result of observation with a transmission electron microscope, fine metal particles having an average particle diameter of 6 nm aggregated in a chain, The length of this chain aggregate was in the range of 30 nm to 100 nm. Film formation: Using the above-mentioned paint for forming a conductive layer, the same treatment as in Example 1 was carried out to produce a cathode ray tube of Comparative Example 2 having an antireflective transparent conductive film.

The high boiling point solvents used in Examples 1 and 2 and Comparative Examples 1 and 2 (boiling point at 1 atm.
Table 1 shows the solvent in the range of from 0 ° C to 250 ° C).

[0039]

[Table 1]

(Evaluation Measurement) The performance of the transparent conductive film formed on the cathode ray tube was measured by the following apparatus or method, and the appearance was visually evaluated. Chain structure: Confirmed by TEM observation Film thickness: Measured by SEM observation Surface resistance: "Loresta AP" manufactured by Mitsubishi Chemical Corporation (4-terminal method) Electromagnetic wave shielding property: Calculated by the above formula 1 based on 0.5 MHz Salt water resistance: Salt water immersion 0.5 MHz electromagnetic wave shielding effect after 3 days Scratch test: Under a load of 1 kg, the membrane surface was rubbed with the metal part of the tip of a sharp pencil, and the degree of scratching was visually evaluated. ○: No scratch △: Slight scratch ×: Scratched Transmittance: “Automatic Haze Meter HIIIDP” manufactured by Tokyo Denshoku Co., Ltd. Haze: “Automatic Haze Meter HIIIDP” manufactured by Tokyo Denshoku Co., Ltd. The difference between the maximum transmittance and the minimum transmittance in the visible light region was determined using a 3500 ”type self-recording spectrophotometer. (The smaller the maximum-minimum transmittance difference in the visible light region, the flatter the transmittance and the sharper the hue of the transmitted image. Particularly, when the difference is 10% or less, the color of the transmitted image approaches black, and High clarity.) Luminous reflectance: "MODEL C-11" manufactured by EG & GGAMMASCIENTIFIC Co., Ltd. Reflected color: "CR-300" manufactured by Mirta Camera (CIE chromaticity diagram using CIE color system) The distance of the deviation from the white point (x = 0.3137, FO.3198) is expressed as √ (Δx ² + Δy ² ) using Δx and Δy, whereby the value of √ (Δx ² + Δy ² ) becomes The closer to “0”, the whiter the reflected color is, that is, the closer to natural light that is easy on the eyes.) Visibility: Overall evaluation including low reflection performance, reflected color, and transmitted color ○: good ×: defective film Defect: Visual defect evaluation ○: good ×: defective Table 2, shown in Table 3.

[0041]

[Table 2]

[Table 3]

From the results shown in Tables 2 and 3, N-methyl-2-pyrrolidinone or ethylene glycol having a boiling point at 1 atm within the range of 150 ° C. to 250 ° C. and a dielectric constant at 20 ° C. of 20 or more was obtained. The cathode ray tubes of Examples 1 and 2 produced by applying the coating material for forming the transparent conductive film to the display surface contained therein have particularly low surface resistance as compared with the cathode ray tubes of Comparative Examples 1 and 2, and have an electromagnetic wave shielding property. It is clear that both the visibility and the film defect are good. Comparative Example 1 used the same coating material as in Examples 1 and 2 except that a solvent having a high boiling point and a low dielectric constant (butyl cellosolve) was used instead of the solvent having a high boiling point and a high dielectric constant in Examples 1 and 2, but a transparent material was used. As a result, the surface resistance of the conductive film was large and the visibility was poor. Comparative Example 2 did not use a high boiling point solvent, but resulted in a large surface resistance of the transparent conductive film and poor film defects.

[0043]

As described above, the coating composition for forming a transparent conductive film according to the present invention has a boiling point at 1 atm within the range of 150 ° C. to 250 ° C.
Since it contains a liquid having a dielectric constant of 20 or more at 0 ° C., a display device having a transparent conductive film formed by applying this coating material to a display surface has an excellent antistatic effect and electromagnetic wave shielding effect. It has natural color hue of transmitted image, good weather resistance represented by salt water resistance, excellent light transmittance, and very little visibility in coating film appearance due to film defects such as agglomerates of paint components. A good display surface is obtained.

Continuing from the front page (72) Inventor Kenichiro Nishida 585 Tomimachi, Funabashi-shi, Chiba F-term in the New Materials Division, Sumitomo Osaka Cement Co., Ltd. (Reference) 2K009 AA06 AA15 CC03 CC09 CC14 CC42 DD02 EE01 EE03 4J038 AA011 HA061 JA20 JA32 JB12 KA06 NA20 PB09 PC03 PC08 5C058 AA01 BA08 DA01 DA08 DA10

Claims (9)

[Claims] 1. A coating material in which metal fine particles are dispersed,
A paint for forming a transparent conductive film, comprising a liquid having a boiling point under atmospheric pressure of 150 ° C. to 250 ° C. and a dielectric constant at 20 ° C. of 20 or more. 2. The method according to claim 1, wherein the liquid is N-methyl-2-pyrrolidinone, ethylene glycol, diethylene glycol, propylene glycol, formamide, N-methylformamide, N, N-dimethylformamide, N-methylacetamide, and N, N-dimethylacetamide. The coating material for forming a transparent conductive film according to claim 1, wherein the coating material is at least one member selected from the group consisting of: 3. A liquid having a boiling point within a range of 150 ° C. to 250 ° C. at 1 atm and containing no liquid having a dielectric constant of 10 or less at 20 ° C. For forming a transparent conductive film. 4. The method according to claim 1, wherein the metal fine particles are gold fine particles, silver fine particles,
4. The transparent conductive film forming paint according to claim 1, wherein the paint is at least one selected from the group consisting of platinum group metal fine particles. 5. 5. The transparent conductive film forming paint according to claim 1, wherein at least a part of the metal fine particles forms a chain aggregate. 6. At least a part of the linear aggregate has a size of 5 nm.
The coating for forming a transparent conductive film according to claim 5, wherein the coating has a length in the range of -200 nm. 7. A transparent conductive film comprising a conductive layer formed using the transparent conductive film forming paint according to claim 1. Description: 8. The transparent conductive film according to claim 7, wherein at least one transparent layer having a refractive index different from that of the conductive layer is laminated on an upper layer and / or a lower layer of the conductive layer. 9. A display device, wherein the transparent conductive film according to claim 7 is formed on a display surface.