JP2003132734A - Coating solution for forming transparent electroconductive layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating solution for forming a transparent electroconductive layer wherein the coating solution for forming the transparent electroconductive layer has a lower cost than that of a previous one and formation of the transparent electroconductive layer having a lower resistance and a lower reflectivity than that of the previous one is possible. SOLUTION: This is the coating solution for forming the transparent electroconductive layer on a transparent substrate wherein a solvent and noble metal fine particles having the average particle diameter 1 to 100 nm dispersed in this solvent, and the solvent contains 25 to 70 wt.% of low boiling point solvent(s) (for example, acetone) having the vapor pressure of 26.66 to 53.33 kPa at 25 deg.C.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a coating liquid for forming a transparent conductive layer for forming a transparent conductive layer on a transparent substrate,
In particular, the transparent conductive substrate on which the transparent conductive layer is formed is a cathode ray tube (CRT), a plasma display panel (PD
P), fluorescent display tube (VFD), liquid crystal display (LC
When applied to a front plate of a display device such as D), the present invention relates to a coating liquid for forming a transparent conductive layer which is inexpensive and can form a uniform transparent conductive layer having a good antireflection effect and electric field shielding effect.

[0002]

2. Description of the Related Art A cathode ray tube (also referred to as a cathode ray tube, also referred to as a CRT) currently used as a computer display or the like has a display screen that is easy to see and does not cause visual fatigue. It is required that there be no adhesion or electric shock.
Furthermore, in addition to these, recently, there is a concern that a low frequency electromagnetic wave generated from a CRT may adversely affect a human body, and it is desired that such an electromagnetic wave does not leak to the outside.

Such a leaked electromagnetic wave can be prevented by forming a transparent conductive layer on the front plate surface of the display. And, for the purpose of preventing leakage electromagnetic waves (electric field shield) of the CRT, at least 10
^It is required to form a transparent conductive layer having a low resistance of ⁶ Ω / □ or less, preferably 5 × 10 ³ Ω / □ or less, more preferably 10 ³ Ω / □ or less.

In order to deal with the electric field shield of the CRT, some proposals have been made so far,
For example, (1) a coating liquid for forming a transparent conductive layer, in which conductive oxide fine particles such as indium tin oxide (ITO) or metal fine particles are dispersed in a solvent, is applied to a CRT front glass (front plate) by a spin coating method or the like. After coating and drying in step 1, the composition is baked at a temperature of about 200 ° C. to form the transparent conductive layer. (2) A method of forming a transparent conductive tin oxide film (nesa film) on a front glass (front plate) by high temperature chemical vapor deposition (CVD) of tin chloride. (3) A method of forming a transparent conductive film on a front glass (front plate) by a sputtering method using indium tin oxide, titanium oxynitride, or the like. Etc. methods have been proposed.

Here, the method (1) using the transparent conductive layer forming coating liquid is far more than the method (2) and (3) for forming the transparent conductive film by the CVD method or the sputtering method. It is a very advantageous method because it is simple and the manufacturing cost is low.

However, in the method shown in (1), indium tin oxide (IT
O) or other conductive oxide fine particles are applied, the resulting transparent conductive layer has a high surface resistance of 10 ⁴ to 10 ⁶ Ω / □,
It was not enough to shield the leakage electric field.

On the other hand, in the case of the transparent conductive layer forming coating liquid to which the fine metal particles are applied, the film transmittance is slightly lower than that of the coating liquid using ITO, but it is as low as 10 ² to 10 ³ Ω / □. Since a resistive film can be obtained, it seems to be a promising method in the future.

The fine metal particles applied to the transparent conductive layer forming coating solution are not easily oxidized in air as disclosed in JP-A-8-77832 and JP-A-9-55175. Limited to precious metals such as silver, gold, platinum, palladium, rhodium and ruthenium. this is,
When metal fine particles other than noble metals, such as iron, nickel, and cobalt, are applied, an oxide film is always formed on the surface of these metal fine particles in the air atmosphere, and good conductivity is obtained as a transparent conductive layer. Because you will not be able to.

On the other hand, in order to make the display screen easier to see, for example, in a CRT, the surface of the front plate is subjected to an antiglare treatment to suppress the reflection of the screen.

This antiglare treatment is also carried out by a method of providing fine unevenness to increase the diffuse reflection on the surface. However, when this method is used, the resolution is lowered and the image quality is deteriorated, which is not so preferable. Absent.

Therefore, it is preferable to perform the antiglare treatment by an interferometric method for controlling the refractive index and the film thickness of the transparent film so that the reflected light causes destructive interference with the incident light.

In order to obtain a low reflection effect by such an interference method, the optical film thicknesses of the high refractive index film and the low refractive index film are generally 1 / 4λ and 1 / 4λ, or 1 / 2λ and 1 /, respectively.
A two-layer structure film set to 4λ is adopted, and the film made of the above-mentioned indium tin oxide (ITO) fine particles is also used as this kind of high refractive index film.

In the case of metal, the optical constant (ni)
k, n: refractive index, i ² = -1, k: extinction coefficient),
Since the value of n is small but the value of k is large, even when a transparent conductive layer made of fine metal particles is used, the antireflection effect due to the interference of light is obtained by the two-layer structure film, like ITO (high refractive index film). can get.

Further, the transparent conductive substrate having a transparent conductive layer of this type formed on a transparent substrate has the above-mentioned good conductivity,
In addition to various characteristics such as low reflectance, in recent years, with the flattening of the screen of a CRT, the transmittance thereof is adjusted to a predetermined range (40 to 75%) lower than 100% to improve image contrast (transmittance. Is also required), the contrast is improved. In this case, fine particles of color pigment or the like are also mixed in the coating liquid for forming the transparent conductive layer.

The reason why the transparent conductive layer having a low transmittance is used in a CRT having a flat screen (flat CRT) is that the flat panel CRT having a flat outer surface and a curved inner surface has a face panel (front panel). ) Thickness is different between the central part and the peripheral part of the screen, and when the conventional colored glass (for example, semi-tinted glass, transmittance: about 53%) is used as the panel glass of the flat CRT, the in-plane brightness is not uniform. This is because it is necessary to combine the in-plane uniformity of brightness and the improvement of contrast by combining the panel glass with high transmittance and the low transmittance layer.

[0016]

By the way, since a film thickness of a certain amount or more is required to form the above-mentioned transparent conductive layer composed of fine metal particles, a conventional coating liquid for forming a transparent conductive layer containing noble metal fine particles is required. In this case, noble metal fine particles having a blending ratio of 0.4 to 0.6% by weight are used, and there is a problem that the coating liquid for forming a transparent conductive layer becomes expensive because of containing a large amount of noble metal fine particles. In this case, as a thickening method that can set the compounding ratio of the noble metal fine particles in the transparent conductive layer forming coating liquid to a low value, for example, a method of increasing the substrate temperature to increase the drying speed of the transparent conductive layer forming coating liquid or A method of lowering the rotation speed of spin coating can be considered, but when such a method is adopted, it is not practical because the uniformity of the transparent conductive layer obtained is deteriorated.

The present invention has been made by paying attention to such problems, and its problem is that it is cheaper than the conventional transparent conductive layer forming coating liquid, and has low resistance and low reflectance. Another object of the present invention is to provide a coating liquid for forming a transparent conductive layer, which enables formation of a uniform transparent conductive layer having

[0018]

That is, the invention according to claim 1 is based on a solvent and a noble metal fine particle having an average particle diameter of 1 to 100 nm dispersed in the solvent as a main component, and a transparent conductive layer on a transparent substrate. On the premise of a transparent conductive layer forming coating liquid for forming a film, the solvent has a vapor pressure at 25 ° C. of 26.66 to
25-70% by weight of a low boiling point solvent of 53.33 kPa
It is characterized by including.

The invention according to claim 2 is premised on the transparent conductive layer forming coating solution according to claim 1, wherein the content of the noble metal fine particles is 0.1 to 0.34% by weight. It is characterized by that.

The invention according to claim 3 is based on the coating liquid for forming a transparent conductive layer according to the invention according to claim 1 or 2, characterized in that the low boiling point solvent is acetone,
The invention according to claim 4 is based on the coating liquid for forming a transparent conductive layer according to any one of claims 1 to 3, and the noble metal fine particles are selected from gold, silver, platinum, palladium, rhodium and ruthenium. It is characterized in that it is any of fine particles of noble metal, fine particles of alloy of these noble metals, or noble metal-coated silver fine particles whose surface is coated with the above-mentioned noble metal except silver.

Next, the invention according to claim 5 relates to claims 1 to 1.
The transparent conductive layer forming coating liquid according to any one of claims 4 to 4 is premised on that colored pigment fine particles are contained. The invention according to claim 6 is the transparent conductive layer forming coating according to claim 5. Assuming a coating liquid, the colored pigment fine particles are carbon,
Selected from titanium black, titanium nitride, complex oxide pigments, cobalt violet, molybdenum orange, ultramarine blue, navy blue, quinacridone pigments, anthraquinone pigments, perylene pigments, isoindolinone pigments, azo pigments and phthalocyanine pigments. The invention according to claim 7 is characterized by being one or more kinds of fine particles.
Based on the transparent conductive layer forming coating liquid described in any one of 6 above, an inorganic binder is contained.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below.

First, according to the present invention, the vapor pressure at 25 ° C. in the coating liquid for forming a transparent conductive layer containing noble metal fine particles is 26.66 to.
25-70% by weight of a low boiling point solvent of 53.33 kPa
When compounded, it was discovered that a uniform transparent conductive layer with low resistance can be formed even if the content of the noble metal fine particles in the coating liquid is lower than in the past, and thus it is possible to form an inexpensive transparent conductive layer. It becomes possible to obtain a coating liquid for use.

By the way, as a method for forming a transparent conductive layer using the above-mentioned transparent conductive layer forming coating solution in a CRT, a spin coating method is widely adopted. When the coating liquid for forming the transparent conductive layer is used, the concentration of the coating liquid (volatilization of the low boiling point solvent) rapidly progresses in the initial stage of the film formation process of spin coating, so that the film thickness can be efficiently increased. It is thought to be because. Other methods for increasing the film thickness in spin coating include a method of increasing the substrate temperature to increase the drying rate of the transparent conductive layer forming coating solution and a method of decreasing the spin rotation rate, as described above. It is not practical because it tends to deteriorate the uniformity of the obtained transparent conductive layer.

The low boiling point solvent needs to have a vapor pressure at 25 ° C. of 26.66 to 53.33 kPa (Claim 1), and more preferably 26.66 to 40.0.
It is preferably 0 kPa. If the vapor pressure of the low boiling point solvent is less than 26.66 kPa, the degree of concentration of the coating liquid in the initial stage of the film formation process is insufficient and the effect of lowering the content of noble metal particles in the transparent conductive layer-forming coating liquid is low. , On the other hand, 5
When it exceeds 3.33 kPa, the content of the noble metal fine particles in the coating liquid for forming the transparent conductive layer can be significantly reduced, but the volatilization rate of the low boiling point solvent is too high, which deteriorates the uniformity of the obtained transparent conductive layer. However, there is a problem that it hinders the storage and transportation of the transparent conductive layer-forming coating liquid, which is not practical.

Further, the compounding amount of the low boiling point solvent is 25 to 7
It is set in the range of 0% by weight (claim 1). 25% by weight
If the amount is less than 70% by weight or less than 70% by weight, the effect of reducing the content of the noble metal fine particles in the coating liquid for forming the transparent conductive layer is low or the uniformity of the obtained transparent conductive layer is the same for the same reason as the above vapor pressure setting. And the problem of storage and transportation of the coating liquid for forming the transparent conductive layer is not preferable.

By the way, since the coating liquid for forming the transparent conductive layer containing the noble metal particles is usually obtained via the aqueous colloidal dispersion of the noble metal particles, the solvent inevitably contains water and the water concentration is 1 to 50% by weight, preferably 5
-25% by weight is preferred. When it exceeds 50% by weight, after the coating liquid for forming the transparent conductive layer is applied on the transparent substrate, repellency may easily occur due to high surface tension of water during drying. Further, in order to reduce the water concentration to less than 1% by weight, it is necessary to produce an aqueous colloidal dispersion in which the concentration of the noble metal fine particles is increased to a high concentration of about 30% by weight. If the concentration is increased to that level, the dispersion becomes unstable and the noble metal fine particles agglomerate, which is not practical.

Here, as the above-mentioned low boiling point solvent, water-soluble acetone (vapor pressure at 25 ° C .: 25 ° C .: from the viewpoint of harmfulness and from the viewpoint that water is contained in the above-mentioned transparent conductive layer forming coating liquid). 30.53 kPa) is preferable (claim 3).

The noble metal fine particles in the coating liquid for forming the transparent conductive layer must have an average particle size of 1 to 100 nm (claim 1). This is because, when the particle diameter is less than 1 nm, it is difficult to manufacture the particle and the particles easily aggregate in the transparent conductive layer forming coating solution, which is not practical. Further, when it exceeds 100 nm, the visible light transmittance of the formed transparent conductive layer becomes too low, and even if the visible light transmittance is increased by setting the film thickness thin, the surface resistance becomes too high. This is because it is not practical.

The average particle size referred to here is the average particle size of the fine particles observed with a transmission electron microscope (TEM).

The precious metal fine particles are gold,
It is possible to apply either noble metal fine particles selected from silver, platinum, palladium, rhodium, or ruthenium, alloy fine particles of these noble metals, or noble metal-coated silver fine particles whose surface is coated with the above noble metal except silver ( Claim 4).

When the specific resistances of silver, gold, platinum, rhodium, ruthenium, palladium, etc. are compared, platinum,
The specific resistances of rhodium, ruthenium and palladium are 10.6, 4.51, 7.6 and 10.8 μΩ · cm, respectively.
Since it is higher than 1.62 and 2.2 μΩ · cm for silver and gold, it is considered advantageous to apply silver fine particles or gold fine particles to form a transparent conductive layer having low surface resistance.

However, when silver fine particles are applied, the application is limited from the viewpoint of weather resistance that is severely deteriorated by sulfurization and salt solution, while gold fine particles, platinum fine particles, rhodium,
When ruthenium fine particles, palladium fine particles, etc. are applied, the above-mentioned problem of weather resistance disappears, but it is not necessarily optimum in view of cost.

Therefore, as described above, it is also possible to use fine particles in which the surface of silver fine particles is coated with a noble metal other than silver. The present inventor has proposed a transparent conductive layer forming coating liquid to which a noble metal-coated silver fine particle having an average particle diameter of 1 to 100 nm, whose surface is coated with gold or platinum alone or a complex of gold and platinum, and a method for producing the same. It has already been proposed (JP-A-11-228872 and JP-A-200).
0-268639).

Next, in the above-mentioned noble metal-coated silver fine particles, the coating amount of gold or platinum alone or gold / platinum composite is 5 parts by weight or more per 100 parts by weight of silver.
It is preferably set in the range of 0 parts by weight, and more preferably in the range of 100 parts by weight or more and 900 parts by weight. If the coating amount of gold or platinum alone or gold or platinum complex is less than 5 parts by weight, film deterioration due to the influence of ultraviolet rays etc. easily occurs and the protective effect of the coating is not seen, on the contrary, if it exceeds 1900 parts by weight, a precious metal coating is applied. This is because the productivity of the silver fine particles is deteriorated and the cost is difficult.

Next, colored pigment fine particles may be added to the transparent conductive layer forming coating liquid (claim 5). By adding the colored pigment fine particles, the transmittance of the transparent conductive substrate on which the transparent conductive layer is formed is lower than 100% in a predetermined range (40 to 75).
%) In addition to various characteristics such as good conductivity and low reflectance, the contrast of the image can be improved to make the display screen easier to see.

The colored pigment fine particles include carbon, titanium black, titanium nitride, complex oxide pigments, cobalt violet, molybdenum orange, ultramarine blue, navy blue, quinacridone pigments, anthraquinone pigments, perylene pigments, isoindolinone. One or more kinds of fine particles selected from the group consisting of pigments, azo pigments and phthalocyanine pigments can be used (Claim 6).

Further, it is preferable that the color pigment fine particles are fine particles whose surface is coated with silicon oxide. When the colored pigment fine particles treated with silicon oxide are used, a transparent conductive layer having excellent conductivity and film strength can be obtained as compared with the case where untreated colored pigment fine particles are used.

Next, noble metal-coated silver fine particles are applied as the noble metal fine particles, and the solvent has a vapor pressure of 2 at 25 ° C.
The coating liquid for forming a transparent conductive layer containing a low boiling point solvent of 6.66 to 53.33 kPa can be produced by the following method. First, known methods [eg Carey-Lea
Law, Am.J.Sci., 37, 47 (1889), Am.J.Sci., 38 (188
9)] to prepare a colloidal dispersion of fine silver particles. That is, a mixed solution of an iron (II) sulfate aqueous solution and an aqueous sodium citrate solution is added to an aqueous silver nitrate solution to cause a reaction, the precipitate is filtered and washed, and then pure water is added to easily add a colloidal dispersion of silver fine particles ( Ag: 0.1 to 10% by weight)
Is prepared. The method for preparing the colloidal dispersion liquid of silver fine particles is arbitrary and is not limited as long as silver fine particles having an average particle diameter of 1 to 100 nm are dispersed.

Next, a reducing agent such as hydrazine (N ₂ H ₄ ) is added to the obtained colloidal dispersion of silver fine particles, and a solution of alkali metal such as a gold salt or a platinum salt is added thereto, or Metal platinate solution and aurate solution,
Alternatively, the surface of the silver fine particles is coated with gold or platinum alone or a complex of gold and platinum by adding a mixed solution of an alkali metal platinum salt and a gold salt to obtain a colloidal dispersion of noble metal-coated silver fine particles. be able to.
In the step of preparing noble metal-coated silver fine particles, if necessary, a colloidal dispersion of silver fine particles, an alkali metal aurate salt solution, an alkali metal platinate solution, an alkali metal aurate salt, and a mixed platinumate solution. A small amount of a dispersant may be added to at least one of the above or each of them.

The colloidal dispersion of noble metal-coated silver fine particles obtained as described above is then subjected to a desalting treatment method such as dialysis, electrodialysis, ion exchange or ultrafiltration to adjust the electrolyte concentration in the dispersion. It is preferable to lower it. This is because colloids generally agglomerate in the electrolyte unless the electrolyte concentration is lowered, and this phenomenon is also known as the Schulze-Hardy law.

Then, the desalted colloidal dispersion of the noble metal-coated silver fine particles is concentrated to obtain a dispersion concentrate of the noble metal-coated silver fine particles, which is added to the dispersion concentrate of the noble metal-coated silver fine particles at 25 ° C. Vapor pressure of 26.66-53.3
A solvent having a low boiling point of 3 kPa and another solvent, or colored pigment fine particles or / and an inorganic binder are further contained (claims 5 and 7). These solvents are added to adjust the components (fine particle concentration, water concentration, organic solvent). Concentration, etc.) to obtain the coating liquid for forming the transparent conductive layer according to the present invention.

The colloidal dispersion of the noble metal-coated silver fine particles can be concentrated by a conventional method such as a vacuum evaporator and ultrafiltration. Depending on the degree of concentration, the transparent conductive layer forming coating solution The water concentration of can be controlled within the above-mentioned range of 1 to 50% by weight.

The solvent used for the coating liquid for forming the transparent conductive layer has a vapor pressure of 26.66 at 25 ° C. as described above.
Examples include low boiling point solvents of ˜53.33 kPa,
The other solvent is not particularly limited and may be appropriately selected depending on the coating method and film forming conditions. For example, methanol (M
A), ethanol (EA), 1-propanol (NP
A), isopropanol (IPA), butanol, pentanol, benzyl alcohol, alcohol solvents such as diacetone alcohol, methyl ethyl ketone (ME
K), methyl propyl ketone, methyl isobutyl ketone (MIBK), ketone solvents such as cyclohexanone and isophorone, ethylene glycol monomethyl ether (M
CS), ethylene glycol monoethyl ether (EC
S), ethylene glycol isopropyl ether (IP
C), propylene glycol methyl ether (PG
M), propylene glycol ethyl ether (PE),
Propylene glycol methyl ether acetate (PG
M-AC), glycol derivatives such as propylene glycol ethyl ether acetate (PE-AC), formamide (FA), N-methylformamide, dimethylformamide (DMF), dimethylacetamide, dimethylsulfoxide (DMSO), N Examples include, but are not limited to, methyl-2-pyrrolidone (NMP) and the like.

Instead of the above-mentioned colloidal dispersion of noble metal-coated silver fine particles, at least one kind of noble metal fine particles selected from gold, silver, platinum, palladium, rhodium and ruthenium, and a colloidal dispersion of these noble metal alloy fine particles. Also in the case of applying, it is possible to obtain the coating liquid for forming a transparent conductive layer according to the present invention by the same method.

Next, using the thus obtained coating liquid for forming a transparent conductive layer according to the present invention, for example, a transparent substrate, and a transparent conductive layer and a transparent coat sequentially formed on this transparent substrate. It is possible to obtain a transparent conductive base material whose main part is composed of a transparent two-layer film composed of layers.

Then, in order to form the transparent two-layer film on the transparent substrate, this can be performed by the following method. That is, the transparent conductive layer forming coating liquid according to the present invention, a glass substrate, a spin coating on a transparent substrate such as a plastic substrate,
After being applied by a method such as spray coating, wire bar coating, doctor blade coating, etc. and dried if necessary, for example, a coating solution for forming a transparent coating layer containing silica sol as a main component is overcoated by the method described above.
Next, for example, a heat treatment is performed at a temperature of about 50 to 350 ° C. to cure the transparent coating layer forming coating liquid to obtain the transparent 2
A layer film is formed.

Here, the vapor pressure at 25 ° C. is 26.66-
25-70% by weight of a low boiling point solvent of 53.33 kPa
When using the transparent conductive layer forming coating liquid according to the present invention that has been blended, compared with the case of applying the conventional transparent conductive layer forming coating liquid in which the low boiling point solvent is not blended, the noble metal fine particles Even if the content is reduced to 0.1 to 0.34% by weight, a transparent conductive layer having excellent uniformity can be formed.

Further, in the above-mentioned coating liquid for forming a transparent conductive layer containing noble metal fine particles, the noble metal fine particles are more likely to aggregate than oxide fine particles such as ITO, and the film forming process of coating / drying the transparent conductive layer forming coating liquid. In the above-mentioned transparent conductive layer obtained by using the coating liquid for forming a transparent conductive layer, fine pores are introduced into the conductive layer of the noble metal fine particles, that is, a network structure. have.

Therefore, when the coating liquid for forming a transparent coat layer containing silica sol as a main component is overcoated by the above-mentioned method, the holes having a mesh structure in the transparent conductive layer (conductive layer of noble metal fine particles) previously formed. The overcoating silica sol liquid (this silica sol liquid becomes a binder matrix containing silicon oxide as a main component by the above heat treatment) soaks into the area of
An increase in conductivity is achieved at the same time.

Further, since the contact area between the transparent substrate and the binder matrix such as silicon oxide is increased through the hole portion of the mesh structure, the bond between the transparent substrate and the binder matrix is strengthened and the strength is also improved. To be

Further, in the optical constant (n-ik) of the transparent conductive layer in which the noble metal fine particles are dispersed in the binder matrix containing silicon oxide as a main component, the refractive index n is not so large but the extinction coefficient k is large. Therefore, the transparent double-layer film structure of the transparent conductive layer and the transparent coat layer can significantly reduce the reflectance of the transparent double-layer film.

Here, the silica sol is hydrolyzed by adding water or an acid catalyst to orthoalkyl silicate,
Polymers that have undergone dehydration polycondensation, or commercially available alkyl silicate solutions that have already undergone polymerization to 4- to 5-mer,
Further, a polymer or the like that has undergone hydrolysis and dehydration polycondensation can be used. Incidentally, as the dehydration polycondensation progresses, the solution viscosity rises and eventually solidifies. Therefore, the degree of the dehydration polycondensation is not more than the upper limit viscosity that can be applied on a transparent substrate such as a glass substrate or a plastic substrate. Adjust to. However, the degree of dehydration polycondensation is not particularly specified as long as it is at the level of the above upper limit viscosity or less, but the film strength,
Considering weather resistance etc., the weight average molecular weight is 500 to 30.
About 00 is preferable. Then, the hydrolyzed alkyl silicate polymer undergoes a dehydration polycondensation reaction when the transparent two-layer film is heated and baked, and becomes a hard silicate film (a film containing silicon oxide as a main component). It is also possible to add magnesium fluoride fine particles, alumina sol, titania sol, zirconia sol, etc. to the silica sol to adjust the refractive index of the transparent coating layer to change the reflectance of the transparent two-layer film.

The vapor pressure at 25 ° C. is 26.66-5.
A solvent containing 25 to 70% by weight of a low boiling point solvent of 3.33 kPa and an average particle size of 1 to 100 nm dispersed in this solvent
In addition to the above noble metal fine particles, colored pigment fine particles (dispersion liquid) or / and a silica sol liquid as an inorganic binder component may be mixed as described above to form the transparent conductive layer forming coating liquid according to the present invention. Items 5 and 7). Also in this case, a similar transparent two-layer film can be obtained by applying the transparent conductive layer forming coating liquid, drying it if necessary, and then overcoating the transparent coating layer forming coating liquid by the method described above. To be For the same reason as desalting treatment in the production of the colloidal dispersion of the noble metal-coated silver fine particles, the colored pigment fine particle dispersion liquid and the silica sol liquid to be blended in the transparent conductive layer forming coating liquid are also the same. It is desirable to carry out sufficient desalting.

As described above in detail, a transparent conductive substrate having a transparent conductive layer formed by applying the coating liquid for forming a transparent conductive layer according to the present invention can be manufactured at a lower cost than before, and Since the transparent conductive layer having various characteristics of low resistance and low reflectance and excellent uniformity can be formed, for example, the above-described cathode ray tube (CRT) and plasma display panel (PD
P), a fluorescent display tube (VFD), a field emission display (FED), an electroluminescence display (ELD), a liquid crystal display (LCD), and the like as a front plate of a display device.

[0056]

EXAMPLES Examples of the present invention will be specifically described below, but the present invention is not limited to these examples. Further, “%” in the text means “% by weight” excluding the transmittance, reflectance and haze value (%), and “part” means “part by weight”.

Example 1 A colloidal dispersion of silver fine particles was prepared by the above-mentioned Carey-Lea method.

Specifically, in 33 g of a 9% silver nitrate aqueous solution,
After adding a mixed solution of 39 g of a 23% iron (II) sulfate aqueous solution and 48 g of a 37.5% sodium citrate aqueous solution, the precipitate was filtered and washed, and then pure water was added to the colloidal dispersion of silver particles (Ag). : 0.15%) was prepared.

To 60 g of this colloidal dispersion of fine silver particles,
8.0 g of a 1% aqueous solution of hydrazine monohydrate (N ₂ H ₄ · H ₂ O) was added, and the mixture was stirred while potassium aurate [KAu] was added.
A mixed solution of 480 g of an (OH) ₄ ] aqueous solution (Au: 0.075%) and 0.2 g of a 1% aqueous polymer dispersant solution was added to obtain a colloidal dispersion of noble metal-coated silver fine particles coated with simple gold.

The colloidal dispersion liquid of the noble metal-coated silver fine particles is desalted with an ion exchange resin (trade name: Diaion SK1B, SA20AP manufactured by Mitsubishi Chemical Co., Ltd.), and then ultrafiltration is performed to obtain a concentrated liquid (A of the noble metal-coated silver fine particles). Liquid) was obtained.

Acetone as a low boiling point solvent, and ethanol (EA), propylene glycol monomethyl ether (PGM), diacetone alcohol (DAA), and formamide (FA) as other solvents were added to the liquid A to add precious metal-coated silver fine particles and A transparent conductive layer forming coating liquid (Ag: 0.04%, Au: 0.
16%, water: 5.3%, acetone: 65%, EA: 4.
45%, PGM: 20%, DAA: 5%, FA: 0.0
3%) was obtained.

As a result of observing this transparent conductive layer forming coating liquid with a transmission electron microscope, the average particle diameter of the noble metal-coated silver fine particles was 7.2 nm.

Next, the transparent conductive layer-forming coating liquid according to Example 1 containing noble metal-coated silver fine particles was spin-coated on a glass substrate (soda lime glass having a thickness of 3 mm) heated to 35 ° C. (90 rpm for 10 seconds, then 12
(0 rpm for 80 seconds), and then spin-coat the silica sol solution (solution B) (150 rpm, 60 seconds).
And further cured at 180 ° C. for 20 minutes to form a transparent two-layer film including a transparent conductive layer containing noble metal-coated silver fine particles and a transparent coat layer composed of a silicate film containing silicon oxide as a main component. A glass substrate, that is, a transparent conductive base material according to Example 1 was obtained.

The glass substrate is polished with a cerium oxide-based abrasive before use, washed with pure water and dried,
It was used after being heated to 35 ° C.

Here, the silica sol solution (solution B) was prepared by using methyl silicate 51 (trade name, manufactured by Colcoat Co.).
6 parts, ethanol 57.8 parts, 1% nitric acid aqueous solution 7.9
Part, and 14.7 parts of pure water, SiO ₂ (silicon oxide)
A solution having a solid content concentration of 10% and a weight average molecular weight of 1350 (C liquid) was prepared, and isopropyl alcohol (IP) was added so that the SiO ₂ solid content concentration was finally 0.8%.
A) and n-butanol (NBA) mixture (IPA / N
It is obtained by diluting with BA = 3/1).

The transparent 2 formed on the glass substrate
Film characteristics of layer film (surface resistance, visible light transmittance, haze value,
The bottom reflectance / bottom wavelength) and film uniformity are shown in Table 1 below. The bottom reflectance means the minimum reflectance in the reflection profile of the transparent conductive base material, and the bottom wavelength means the wavelength when the reflectance is minimum. The film uniformity was judged by visually inspecting the reflected light and transmitted light of the film.

In Table 1, a transparent substrate (glass substrate)
The (visible light) transmittance of only the transparent two-layer film containing no is determined as follows. That is, the transmittance (%) of the transparent two-layer film not including the transparent substrate =
[(Transmittance measured for each transparent substrate) / (Transmittance of transparent substrate)] × 100 In this specification, unless otherwise specified, as the transmittance, only a transparent two-layer film containing no transparent substrate is used. The visible light transmittance value of is used.

The surface resistance of the transparent two-layer film is Mitsubishi Chemical
Surface resistance meter Loresta AP (MCP-T400)
Was used for measurement. The haze value and visible light transmittance were measured using a haze meter (HR-200) manufactured by Murakami Color Research Laboratory. The reflectance was measured using a spectrophotometer (U-4000) manufactured by Hitachi, Ltd. The particle size of the noble metal-coated silver fine particles is evaluated by a transmission electron microscope manufactured by JEOL.

Example 2 Liquid A of Example 1 was prepared by adding acetone as a low boiling point solvent and ethanol (E as another solvent).
A), propylene glycol monomethyl ether (PG
M), diacetone alcohol (DAA) and formamide (FA) are added, and the noble metal-coated silver fine particles and acetone are contained in the transparent conductive layer forming coating liquid (A).
g: 0.05%, Au: 0.2%, water: 6.8%, acetone: 45%, EA: 22.9%, PGM: 20%, D
AA: 5%, FA: 0.05%) was obtained.

Then, the same procedure as in Example 1 was carried out except that this transparent conductive layer forming coating solution was used, and the transparent conductive layer containing noble metal-coated silver fine particles and the silicate film containing silicon oxide as the main component were used. A glass substrate having a transparent two-layer film formed of a transparent coating layer, that is, a transparent conductive substrate according to Example 2 was obtained.

Table 1 below shows the film characteristics and film uniformity of the transparent two-layer film formed on the glass substrate.

Example 3 Liquid A of Example 1 was prepared by adding acetone as a low boiling point solvent and ethanol (E as another solvent).
A), propylene glycol monomethyl ether (PG
M), diacetone alcohol (DAA), formamide (FA), and the transparent conductive layer forming coating liquid (A) containing noble metal-coated silver fine particles and acetone.
g: 0.05%, Au: 0.2%, water: 6.8%, acetone: 35%, EA: 32.9%, PGM: 20%, D
AA: 5%, FA: 0.05%) was obtained.

Then, the procedure is carried out in the same manner as in Example 1 except that this transparent conductive layer forming coating solution is used, and it is composed of a transparent conductive layer containing noble metal-coated silver fine particles and a silicate film containing silicon oxide as a main component. A glass substrate with a transparent two-layer film composed of a transparent coating layer, that is, a transparent conductive substrate according to Example 3 was obtained.

The above film characteristics and film uniformity of the transparent two-layer film formed on the glass substrate are shown in Table 1 below.

[Example 4] 2 g of phthalocyanine blue fine particles (cyanine blue # 5203, manufactured by Dainichiseika Kogyo Co., Ltd.), 0.1 g of a dispersant, and 4 g of the silica sol liquid (C liquid) of Example 1 were mixed with 93.9 g of ethanol. After mixing and performing paint shaker dispersion with zirconia beads,
It was desalted with an ion exchange resin to obtain a silicon oxide-coated phthalocyanine blue fine particle dispersion liquid (D liquid) having a dispersion particle diameter of 95 nm.

Next, in the liquid A of Example 1, the above liquid D, acetone as a low boiling point solvent, ethanol (EA) as another solvent, propylene glycol monomethyl ether (PGM), diacetone alcohol (DAA), formamide. (FA) was added, and the coating liquid for forming the transparent conductive layer according to Example 4 containing noble metal-coated silver fine particles and acetone (Ag: 0.06%, Au: 0.24%, phthalocyanine blue: 0.05%). , Water: 8.0%, acetone: 4
5%, EA: 21.6%, PGM: 20%, DAA: 5
%, FA: 0.05%) was obtained.

Then, the procedure is carried out in the same manner as in Example 1 except that this transparent conductive layer forming coating liquid is used, and the transparent conductive layer containing the noble metal-coated silver fine particles and the phthalocyanine blue fine particles, and silicon oxide as the main component. A glass substrate provided with a transparent two-layer film composed of a transparent coating layer made of a silicate film, that is, a transparent conductive substrate according to Example 4 was obtained.

The above-mentioned film characteristics and film uniformity of the transparent two-layer film formed on the glass substrate are shown in Table 1 below.

[Example 5] 5 g of titanium nitride (TiN) fine particles (manufactured by Netren Co., Ltd.) and silica sol liquid (C liquid) 5
20 g of ethanol and 70 g of ethanol were mixed, and the mixture was subjected to paint shaker dispersion with zirconia beads, followed by desalting with the above ion exchange resin to obtain a silicon oxide-coated titanium nitride fine particle dispersion liquid (E liquid) having a dispersion particle diameter of 85 nm. It was

Next, in the solution A of Example 1, the solution E, acetone as a low boiling point solvent, ethanol (EA) as another solvent, propylene glycol monomethyl ether (PGM), diacetone alcohol (DAA), formamide were added. (FA) was added, and the transparent conductive layer forming coating liquid (Ag: 0.06%, Au: 0.2) according to Example 5 containing noble metal-coated silver fine particles, titanium nitride fine particles, and acetone was added.
4%, TiN: 0.075%, water: 8.3%, acetone: 45%, EA: 21.2%, PGM: 20%, D
AA: 5%, FA: 0.05%) was obtained.

As a result of observing the coating liquid for forming the transparent conductive layer with a transmission electron microscope, the average particle diameter of titanium nitride fine particles was 2
It was 0 nm.

Then, the procedure is carried out in the same manner as in Example 1 except that this transparent conductive layer forming coating solution is used, and the transparent conductive layer containing the noble metal-coated silver fine particles and the titanium nitride fine particles, and silicon oxide as the main component. A glass substrate with a transparent two-layer film composed of a transparent coating layer made of a silicate film, that is, a transparent conductive substrate according to Example 5 was obtained.

The film characteristics and film uniformity of the transparent two-layer film formed on the glass substrate are shown in Table 1 below.

Comparative Example 1 Ethanol (EA) was added to the liquid A of Example 1 without adding acetone as a low boiling point solvent.
Propylene glycol monomethyl ether (PGM),
Diacetone alcohol (DAA), formamide (F
A) is added, and the transparent conductive layer forming coating liquid (Ag:
0.07%, Au: 0.28%, water: 9.4%, EA:
65.1%, PGM: 20%, DAA: 5%, FA:
0.1%) was obtained.

Then, the procedure is carried out in the same manner as in Example 1 except that this transparent conductive layer forming coating solution is used, and it is composed of a transparent conductive layer containing noble metal-coated silver fine particles and a silicate film containing silicon oxide as a main component. A glass substrate with a transparent two-layer film composed of a transparent coating layer, that is, a transparent conductive substrate according to Comparative Example 1 was obtained.

The film characteristics and film uniformity of the transparent two-layer film formed on the glass substrate are shown in Table 1 below.

[Comparative Example 2] Ethanol (EA) was added to the liquid A of Example 1 without adding acetone as a low boiling point solvent.
Propylene glycol monomethyl ether (PGM),
Diacetone alcohol (DAA), formamide (F
A) is added to the transparent conductive layer-forming coating liquid (Ag:
0.05%, Au: 0.2%, water: 6.8%, EA: 6
7.9%, PGM: 20%, DAA: 5%, FA: 0.
05%).

Then, the procedure is carried out in the same manner as in Example 1 except that this transparent conductive layer forming coating solution is used, and it is composed of a transparent conductive layer containing noble metal-coated silver fine particles and a silicate film containing silicon oxide as a main component. A glass substrate provided with a transparent two-layer film composed of a transparent coating layer, that is, a transparent conductive substrate according to Comparative Example 2 was obtained.

The above-mentioned film characteristics and film uniformity of the transparent two-layer film formed on the glass substrate are shown in Table 1 below.

Comparative Example 3 Liquid A of Example 1 was replaced with Example 5
E liquid, methanol (vapor pressure at 25 ° C: 16.93k
Pa), ethanol (EA), propylene glycol monomethyl ether (PGM), diacetone alcohol (DAA), formamide (FA), and a transparent conductive layer forming coating according to Comparative Example 3 containing noble metal-coated silver fine particles and methanol. Liquid (Ag: 0.06%, Au: 0.2
4%, TiN: 0.075%, water: 8.3%, methanol: 45%, EA: 21.2%, PGM: 20%, DA
A: 5%, FA: 0.05%) was obtained.

Then, the procedure is carried out in the same manner as in Example 1 except that this transparent conductive layer forming coating liquid is used, and it is composed of a transparent conductive layer containing noble metal-coated silver fine particles and a silicate film containing silicon oxide as a main component. A glass substrate having a transparent two-layer film formed of a transparent coating layer, that is, a transparent conductive base material according to Comparative Example 3 was obtained.

The film characteristics and film uniformity of the transparent two-layer film formed on the glass substrate are shown in Table 1 below.

Comparative Example 4 Liquid A of Example 1 was replaced with Example 5
Solution E, and acetone as a low boiling point solvent, ethanol (EA), propylene glycol monomethyl ether (PGM), diacetone alcohol (DAA), formamide (FA) are added, and noble metal-coated silver fine particles, titanium nitride fine particles, and acetone are added. The coating liquid for forming the transparent conductive layer according to Comparative Example 4 (Ag: 0.06%, Au: 0.2).
4%, TiN: 0.075%, water: 8.3%, acetone: 20%, EA: 46.2%, PGM: 20%, DA
A: 5%, FA: 0.05%) was obtained.

Then, the procedure is carried out in the same manner as in Example 1 except that this transparent conductive layer forming coating solution is used, and the transparent conductive layer containing the noble metal-coated silver fine particles and the silicate film containing silicon oxide as the main component are used. A glass substrate provided with a transparent two-layer film composed of a transparent coating layer, that is, a transparent conductive substrate according to Comparative Example 4 was obtained.

The above-mentioned film characteristics and film uniformity of the transparent two-layer film formed on the glass substrate are shown in Table 1 below.

[0096]

[Table 1] "Evaluation" The results shown in Table 1 confirm the following.

First, the content of noble metal is 0.25 to 0.3.
%, The surface resistance of the transparent two-layer film according to Comparative Examples 2 to 4 is 6
300 to> 10 ⁶ (Ω / □), while the content of the noble metal is 0.2 to 0.3%.
The surface resistance of the layer film is 440 (Ω / □) to 1034 (Ω /
It is confirmed that the conductivity is excellent.

In Comparative Example 3, methanol having a vapor pressure of less than 26.66 kPa at 25 ° C. was used as the low boiling point solvent, and in Comparative Example 4, the amount of acetone as the low boiling point solvent was 25% by weight. since 20% by weight less than, the surface resistance of the transparent 2-layered film since it is less effective to reduce the noble metal fine particle content of the transparent conductive layer forming coating liquid in the> 10 ⁶ (Ω / □) and the The value is higher than the surface resistance of the transparent two-layer film according to the example.

Further, the surface resistance of the transparent two-layer film according to Comparative Example 1 in which the content of the noble metal is 0.35% is 398 (Ω /
□), the conductivity is excellent, but since the content of the noble metal in the transparent conductive layer forming coating liquid is as high as 0.35%, it is difficult to form the transparent conductive layer at low cost and the manufacturing cost is difficult. It is confirmed that there is.

[0100]

According to the coating liquid for forming a transparent conductive layer according to the present invention, the vapor pressure at 25 ° C. is 26.66.
Since it contains 25 to 70% by weight of a low boiling point solvent of 53 to 33.33 kPa, even when the content of noble metal fine particles in the coating liquid for forming a transparent conductive layer is reduced from the conventional value,
Since it is possible to form a transparent conductive layer having various properties such as low resistance and low reflectance and excellent film uniformity, it is possible to obtain an inexpensive coating liquid for forming a transparent conductive layer.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masaya Gyunobu             Sumitomo, 3-18-5 Chugoku, Ichikawa, Chiba             Central Research Laboratory, Metal Mining Co., Ltd. F term (reference) 4J038 HA026 HA061 HA156 HA211                       HA216 HA246 HA316 HA441                       HA446 HA506 HA566 JA03                       JA17 JA25 JA30 JA33 JB12                       JB16 JB17 JC11 JC38 KA06                       KA08 KA20 MA07 MA14 NA20                       PA18 PB09 PB11 PC03 PC08                 5G301 DA02 DA03 DA05 DA11 DA12                       DA32 DA42 DD01 DD02

Claims (7)

[Claims] 1. A transparent conductive layer-forming coating liquid, which comprises a solvent and a noble metal fine particle having an average particle size of 1 to 100 nm dispersed in the solvent as a main component and forms a transparent conductive layer on a transparent substrate, wherein However, the vapor pressure at 25 ° C is 26.66 to 53.3.
A coating liquid for forming a transparent conductive layer, which comprises a low boiling point solvent of 3 kPa in an amount of 25 to 70% by weight. 2. The content of the noble metal fine particles is 0.1 to 0.
The coating liquid for forming a transparent conductive layer according to claim 1, wherein the coating liquid is 34% by weight. 3. The coating liquid for forming a transparent conductive layer according to claim 1, wherein the low boiling point solvent is acetone. 4. The noble metal fine particles are fine particles of a noble metal selected from gold, silver, platinum, palladium, rhodium and ruthenium, alloy fine particles of these noble metals, or a noble metal coat whose surface is coated with the noble metal other than silver. It is any one of silver fine particles, It is characterized by the above-mentioned.
The coating liquid for forming a transparent conductive layer according to any one of 1. 5. The coating liquid for forming a transparent conductive layer according to claim 1, wherein the colored pigment fine particles are contained. 6. The colored pigment fine particles are carbon, titanium black, titanium nitride, complex oxide pigments, cobalt violet, molybdenum orange, ultramarine blue, navy blue, quinacridone pigments, anthraquinone pigments, perylene pigments,
The coating liquid for forming a transparent conductive layer according to claim 5, which is one or more kinds of fine particles selected from an isoindolinone pigment, an azo pigment and a phthalocyanine pigment. 7. The transparent conductive layer forming coating liquid according to claim 1, further comprising an inorganic binder.