JP2005100721A - Manufacturing method of transparent conductive substrate and substrate and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a transparent conductive substrate having superior characteristics by preventing the coagulation of metal particulates in a coating liquid for transparent conductive layer formation coated on a colored layer, even in the case the coating liquid for colored layer formation contains a hydrophobic dispersant as a dispersant of colored pigment particulates. <P>SOLUTION: After the coating liquid for the colored layer formation including the hydrophobic dispersant is coated on a transparent substrate, and the colored layer is cleaned by water or a solvent containing water, the coating liquid for transparent conductive layer formation and the coating liquid for transparent coat layer formation are coated and dried, and heat-treated. By using the coating liquid for colored layer formation containing the colored pigment particulates having maximum absorption at a wavelength of 560-600 nm, the transparent conductive substrate which has improved in contrast without accompanying the deterioration of illuminance when used for a front screen such as CRT etc. can be obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a transparent conductive substrate used as a front plate of a display device such as a cathode ray tube (CRT), a plasma display panel (PDP), a fluorescent display tube (VFD), and a liquid crystal display (LCD), particularly on a transparent substrate. A method for producing a transparent conductive substrate comprising a colored transparent three-layer film composed of a colored layer, a transparent conductive layer, and a transparent coating layer, the transparent conductive substrate, and the transparent conductive layer The present invention relates to a display device to which a conductive substrate is applied.

  Display devices such as cathode ray tubes (also called CRTs), plasma display panels (PDPs), fluorescent display tubes (VFDs), liquid crystal displays (LCDs) and the like currently used as computer displays have display screens. It is required to be easy to see and not cause visual fatigue.

Furthermore, recently, there are concerns about the adverse effects of low-frequency electromagnetic waves generated from CRT and the like on the human body, and it is desired that such electromagnetic waves do not leak to the outside. Such leakage electromagnetic waves can be prevented by forming a transparent conductive layer on the front plate surface of the display. For example, for preventing leakage electromagnetic waves (electric field shield) of CRT, the surface resistance is at least 10 ⁶ Ω / □ or less, preferably 5 × 10 ³ Ω / □ or less, more preferably 10 ³ Ω / □ or less. It is required to form a transparent conductive layer.

As a low resistance transparent conductive film for the CRT electric field shield, several proposals have been made so far. For example, a coating liquid for forming a transparent conductive layer in which metal fine particles are dispersed in a solvent is used as a CRT front glass (front plate). And a method of forming a transparent conductive layer by applying and drying by spin coating or the like and then baking at a temperature of about 200 ° C. (see Japanese Patent Application Laid-Open No. 9-115438). This method is extremely advantageous because it is much simpler and less expensive to manufacture than a method of forming a transparent conductive film by a CVD method, a sputtering method, or the like, and a low resistance film of 10 ² to 10 ³ Ω / □ can be obtained. It is a simple method.

  As metal fine particles applied to the coating liquid for forming the transparent conductive layer, noble metals that are not easily oxidized in the air, for example, silver, gold, platinum, palladium, rhodium, ruthenium, and the like have been proposed (Japanese Patent Laid-Open No. 8-77832). Gazette, JP-A-9-55175). In the same publication, it is stated that metal fine particles other than noble metals such as iron, nickel, cobalt, etc. are also applicable, but in actuality, these metal fine particles are oxidized on the surface in an air atmosphere. Since a material film is always formed, it is difficult to obtain good conductivity as a transparent conductive layer.

  Further, in order to improve the weather resistance of the noble metal fine particles in the coating liquid for forming the transparent conductive layer, noble metal coated silver fine particles having an average particle diameter of 1 to 100 nm, such as gold or It is also known to use noble metal-coated silver fine particles coated with single platinum or a composite of gold and platinum (see JP-A-11-228872 and JP-A-2000-268639).

  By the way, since metal is not inherently transparent to visible light, in order to achieve both high transmittance and low resistance in the transparent conductive film, as little metal particles as possible can efficiently pass through the conductive path in the transparent conductive film. It is desirable to form. In other words, the conductive film obtained using a general coating liquid for forming a transparent conductive layer mainly composed of a solvent and metal fine particles has a network (network-like) structure in which the metal fine particles are connected to each other. (See “Industrial Materials”, Vol. 44, No. 9, 1996, p. 68-71).

  A transparent conductive film having a low resistance and a high transmittance can be obtained by the formation of such a network structure. The mesh portion made of metal fine particles functions as a conductive path, while the hole portion of the mesh structure has a light transmittance. It is thought to fulfill the function of improving As a method for forming a network (network-like) structure of the metal fine particles, for example, a method using a coating liquid for forming a transparent conductive layer in which metal fine particle groups in which metal fine particles are aggregated in a chain shape is dispersed in advance (Japanese Patent Laid-Open No. 2000-1999) No. 124662) is known.

In addition, in order to make a display screen such as a CRT easy to see, an anti-glare treatment is performed on the front plate surface to suppress reflection of the screen. This anti-glare treatment includes anti-glare by an interference method that controls the refractive index and film thickness of a multilayer film composed of a transparent conductive layer and a transparent coating layer so that the reflected light causes destructive interference with incident light. Processing is generally performed. In addition, in a metal, the value of n (refractive index) is small among optical constants (n−ik, n: refractive index, i ² = −1, k: extinction coefficient), but k (extinction coefficient). Since the value is large, even in the case of a multilayer film using a transparent conductive layer made of metal fine particles, the antireflection effect due to light interference can be obtained if the optical constant and film thickness of each layer are set appropriately.

  Further, in recent years, in display devices such as CRT, in addition to the above-mentioned characteristics such as good conductivity and low reflectance, the transmittance of the display screen is reduced to a predetermined range (specifically, lower than 100%) as the display screen is flattened. In particular, it is required to improve the contrast of the image by adjusting to 40 to 95%, generally 40 to 75%. As a means for this, for example, a method of controlling the visible light transmittance of the transparent conductive layer by blending colored pigment fine particles or the like with the coating liquid for forming the transparent conductive layer has been implemented.

  In the case of a flat CRT face panel (front plate), the outer surface is flat and the inner surface has a curvature, and the panel thickness is different between the central portion and the peripheral portion of the screen. When colored glass (for example, semi-tinted glass, transmittance: about 53%) is used, luminance in-plane nonuniformity occurs, making it difficult to see the screen. Therefore, in order to improve the contrast of the image and increase the in-plane uniformity of luminance, a method of combining a transparent film having a low transmittance with a panel glass having a high transmittance is used.

  By the way, in the method of controlling the transmittance of the transparent conductive layer by adding colored pigment fine particles or the like to the coating liquid for forming the transparent conductive layer for improving the contrast, the film resistance value increases as the amount of the colored pigment fine particles added increases. Problems such as an increase, stability of the coating liquid, and a decrease in coating properties occur. Therefore, a method of laminating a colored layer and a conductive layer, that is, a method of providing a transparent conductive layer mainly composed of metal fine particles on a colored layer containing colored pigment fine particles has been proposed. According to this method, since the colored layer and the conductive layer are separated, the electroconductive deterioration due to the colored pigment fine particles does not occur, and at the same time, the amount of the colored pigment fine particles added can be increased. Is the preferred method.

  However, in the coating liquid for forming a colored layer used in this method, when a hydrophobic dispersant is used as a dispersant for dispersing colored pigment fine particles in a solvent, the coating liquid for forming a transparent conductive layer is formed on the formed colored layer. When applied, the metal fine particles are agglomerated, and the resistance value, haze, and the like of the obtained transparent conductive layer are deteriorated. The aggregation of the metal fine particles is considered to be caused by the hydrophobicity of the colored layer formed using the coating solution for forming the colored layer. Therefore, in the conventional coating liquid for forming a colored layer, a hydrophilic dispersant such as a hydrophilic resin has only been used as a dispersant (see JP 2002-279829 A).

JP-A-9-115438 JP-A-8-77832 JP-A-9-55175 JP-A-11-228872 JP 2000-268639 A JP 2000-124662 A JP 2002-279829 A “Industrial Materials”, Vol. 44, No. 9, 1996, p.

  As described above, in the method of laminating the colored layer and the conductive layer for improving the contrast, it is necessary to use a hydrophilic dispersant as the dispersant for the colored pigment fine particles in the colored layer forming coating solution. However, in the coating liquid for forming a colored layer using a hydrophilic dispersant, there is a high possibility that the water resistance of the entire transparent conductive film including the colored layer is deteriorated, and further, there is an inconvenience that usable dispersants are extremely limited. was there.

  In view of such conventional circumstances, the present invention provides a coating for forming a transparent conductive layer on a colored layer even when a hydrophobic dispersant is used as a dispersing agent for colored pigment fine particles of a coating liquid for forming a colored layer. An object of the present invention is to provide a method for producing a transparent conductive substrate which prevents aggregation of metal fine particles when the liquid is continuously applied, has high water resistance of the entire transparent conductive film including the colored layer, and has excellent characteristics. . Further, a transparent conductive substrate obtained by this production method, having a low haze value of the transparent conductive layer, excellent conductivity and film strength, and having low reflection characteristics, and a display to which the transparent conductive substrate is applied An object is to provide an apparatus.

  The present inventor has studied the method of forming a colored layer using a coating solution for forming a colored layer containing a hydrophobic dispersant and forming a transparent conductive layer thereon, and as a result, the hydrophobic dispersant is contained. When the colored layer formed with the colored layer forming coating liquid is washed with water or a solvent containing water, when the transparent conductive layer forming coating liquid mainly composed of noble metal-containing fine particles is applied onto the colored layer, The inventors have found that aggregation of noble metal-containing fine particles can be effectively suppressed, and have completed the present invention.

  That is, the manufacturing method of the transparent conductive base material concerning Claim 1 of this invention is a transparent conductive material provided with the colored transparent 3 layer film | membrane comprised by the colored layer, the transparent conductive layer, and the transparent coat layer which were sequentially formed on the transparent substrate. In the method for producing a conductive substrate, a coating solution for forming a colored layer mainly composed of a solvent, colored pigment fine particles dispersed in the solvent, a hydrophobic dispersant, and a binder was applied onto a transparent substrate and dried. Thereafter, it is washed with water or a solvent containing water, and subsequently, a coating solution for forming a transparent conductive layer mainly composed of the solvent and the noble metal-containing fine particles dispersed in the solvent is applied and dried, and then the solvent and the binder A coating liquid for forming a transparent coating layer containing as a main component is applied and dried, followed by heat treatment.

  The method for producing a transparent conductive substrate according to claim 2 of the present invention is the method for producing a transparent conductive substrate according to claim 1, wherein the noble metal-containing fine particles are gold-silver alloy fine particles, platinum- It is at least one selected from silver alloy fine particles, gold-silver-platinum alloy fine particles, noble metal-coated silver fine particles whose surface is coated with gold alone, platinum alone or a composite of gold and platinum.

  The method for producing a transparent conductive substrate according to claim 3 of the present invention is the method for producing a transparent conductive substrate according to claim 1 or 2, wherein the colored pigment fine particles are carbon fine particles, titanium black fine particles. And at least one selected from titanium nitride fine particles, phthalocyanine pigment fine particles, quinacridone pigment fine particles, and dioxazine pigment fine particles.

  The method for producing a transparent conductive substrate according to claim 4 of the present invention is the method for producing a transparent conductive substrate according to any one of claims 1 to 3, wherein at least one of the colored pigment fine particles is used. The colored pigment fine particles have maximum absorption in the visible light wavelength region of 560 to 600 nm.

  The manufacturing method of the transparent conductive base material concerning Claim 5 of this invention exists in the manufacturing method of the transparent conductive base material in any one of the said Claims 1-4, In the said coating liquid for colored layer formation, The binder is characterized in that the main component is at least one selected from silicon oxide, zirconium oxide, and titanium oxide. Moreover, the manufacturing method of the transparent conductive base material concerning Claim 6 of this invention exists in the manufacturing method of the transparent conductive base material in any one of the said Claims 1-5, The application for said transparent coat layer formation The binder in the liquid is mainly composed of silicon oxide.

  Moreover, this invention is manufactured by the method in any one of the said Claims 1-6, and is equipped with the colored transparent 3 layer film | membrane comprised by the colored layer, the transparent conductive layer, and the transparent coating layer on a transparent substrate. The transparent conductive base material characterized by the above is provided.

  Furthermore, the present invention is a display device comprising a front plate disposed on the front side of the display unit of the device body, wherein the transparent conductive substrate according to claim 7 is a colored transparent three-layer film as the front plate. Provided is a display device characterized in that the display device is incorporated with the side as an outer surface.

  According to the present invention, even though a hydrophobic dispersant is used as the dispersant for the colored pigment fine particles in the colored layer forming coating solution, the colored layer forming coating solution is coated with the colored layer forming coating solution. When the coating solution for forming the transparent conductive layer is continuously applied to the transparent conductive group, it is possible to prevent the aggregation of the noble metal-containing fine particles and not only has excellent properties such as conductivity and haze, but also has excellent water resistance. A method for producing a material can be provided.

  Moreover, the transparent conductive substrate obtained by the production method of the present invention has a low haze value, high conductivity, low reflection characteristics, and excellent film strength. Therefore, by incorporating the transparent conductive substrate of the present invention as a front plate disposed on the front side of the display unit of the apparatus main body, the contrast of the display screen can be improved, surface reflection is suppressed, and a high electric field shielding effect is provided. A display device can be provided.

  In the present invention, a colored layer forming coating solution containing colored pigment fine particles, a hydrophobic dispersant, and a binder is used, and this is applied to a transparent substrate and dried to form a colored layer. Before applying the coating liquid for forming a transparent conductive layer as a component, the colored layer is washed with water or a solvent containing water. Thereafter, the transparent conductive layer-forming coating solution is applied and dried on the washed colored layer, and the transparent coating layer-forming coating solution is applied and dried, followed by heat treatment, whereby the colored layer and the transparent conductive layer are heated. And a transparent conductive substrate provided with a colored transparent three-layer film composed of a transparent coating layer.

  By washing the colored layer with water or a solvent containing water as described above, aggregation of the noble metal-containing fine particles can be effectively suppressed when the transparent conductive layer forming coating solution is applied onto the colored layer. The reason why aggregation of the noble metal-containing fine particles can be suppressed by washing the colored layer with water or a solvent containing water is not clear, but for example, the hydrophobic dispersant or hydrophobicity on the colored layer surface with water or a solvent containing water. Possible reasons are that impurities caused by the dispersant are removed by washing, water is adsorbed on the surface of the colored layer and is made hydrophilic.

  Application of the coating liquid for forming the colored layer, the coating liquid for forming the transparent conductive layer, and the coating liquid for forming the transparent coating layer is performed using a technique such as spray coating, spin coating, wire bar coating, doctor blade coating, dip coating, or the like. Is possible. In particular, when a coating method such as spray coating, spin coating, dip coating, or the like is used, the colored layer can be washed with water or a solvent containing water by the same method. For example, by the same spin coating, a coating solution for forming a colored layer, water or a solvent containing water, a coating solution for forming a transparent conductive layer, and a coating solution for forming a transparent coating layer can be applied in this order. Can be performed continuously.

  Further, water or a solvent containing water is used for washing the colored layer. As the solvent at this time, it is preferable to use the solvent used for preparing any one of the coating liquid for forming a colored layer, the coating liquid for forming a transparent conductive layer, or the coating liquid for forming a transparent coat layer. However, when using a solvent containing water, if the amount of water is less than 5% by weight, the effect of suppressing aggregation of noble metal-containing fine particles when the transparent conductive layer forming coating solution is applied on the colored layer cannot be obtained. It is preferable to contain 5% by weight or more of water.

  In addition, as a board | substrate which apply | coats the coating liquid for colored layer formation, the coating liquid for transparent conductive layer formation, and the coating liquid for transparent coating layer formation sequentially, according to the use of a transparent conductive base material, a glass substrate, a plastic substrate, etc. Use a transparent substrate. The drying after application | coating of each coating liquid can use the method currently performed normally. Moreover, although heat processing changes with kinds etc. of used binder, it is normally implemented at the temperature of about 50-250 degreeC.

  The colored pigment fine particles used in the colored layer forming coating solution and the noble metal-containing fine particles used in the transparent conductive layer forming coating solution preferably have an average particle diameter of 1 to 100 nm. When the average particle size is less than 1 nm, it is difficult to produce the fine particles and to disperse the fine particles. When the average particle size exceeds 100 nm, the scattering of visible light increases in the formed colored layer and transparent conductive layer. It is too expensive and impractical. In addition, said average particle diameter has shown the average particle diameter of the microparticles | fine-particles observed with a transmission electron microscope (TEM).

  As the noble metal-containing fine particles applied to the coating liquid for forming the transparent conductive layer, fine particles such as silver, gold, platinum, rhodium, palladium and the like that are not easily oxidized in air can be used. When the specific resistances of these noble metal fine particles are compared, the specific resistances of platinum, rhodium, and palladium are 10.6, 5.1, 10.8 μΩ · cm, and 1.62 and 2.2 μΩ of silver and gold, respectively. Since it is higher than cm, it is advantageous to use silver fine particles or gold fine particles to form a transparent conductive layer having a low surface resistance. However, when silver fine particles are applied, deterioration due to sulfidation, oxidation, saline solution, ultraviolet rays, etc. is severe, and there is a problem in weather resistance. On the other hand, when gold fine particles are applied, the above-mentioned problem of weather resistance is eliminated, but there is a cost problem as in the case where platinum fine particles, rhodium fine particles, palladium fine particles and the like are applied.

  From this point of view, the noble metal-containing fine particles include gold-silver alloy fine particles, platinum-silver alloy fine particles, gold-silver-platinum alloy fine particles, and precious metal whose surface is coated with gold alone or platinum alone or a composite of gold and platinum. It is desirable to use any one kind or two or more kinds of coated silver fine particles. In the case of the noble metal-coated silver fine particles, the surface of the silver fine particles is protected with gold, platinum, or a composite of gold and platinum, so that the weather resistance, chemical resistance, and the like can be improved. The coating liquid for forming a transparent conductive layer in which noble metal-coated silver fine particles are dispersed is described in JP-A-11-228872 and JP-A-2000-268639.

  The colored pigment fine particles contained in the coating solution for forming the colored layer include carbon fine particles, titanium black fine particles, titanium nitride fine particles, phthalocyanine pigment fine particles, quinacridone pigment fine particles, dioxazine pigment fine particles, or two or more of these. Can be used in combination. By providing a colored layer containing these colored pigment fine particles, the transmittance of the colored transparent three-layer film can be reduced. Therefore, the transparent conductive substrate provided with the colored transparent three-layer film is assembled as a front plate. If this is done, the contrast of a display device such as a CRT can be improved.

  Further, if colored pigment fine particles having maximum absorption at a wavelength of 560 to 600 nm in the visible light wavelength range (380 to 780 nm) are used as the colored pigment fine particles, each emission of green (G: 540 nm) and red (R: 630 nm) Since the light in the wavelength region between the wavelengths is selectively absorbed, when applied to a CRT or the like, the contrast can be further improved without a decrease in luminance. Examples of the colored pigment fine particles having the maximum absorption at 560 to 600 nm include quinacridone-based colored pigment fine particles.

  In addition, as a hydrophobic dispersant used for dispersing colored pigment fine particles in a solvent in a coating solution for forming a colored layer, for example, compared with a hydroxyl group (OH) or a carboxyl group (COOH) that is a hydrophilic functional group. Examples thereof include a polymer dispersant containing a large amount of a hydrophobic functional group such as an alkyl group. These are well soluble in various organic solvents, but have no or very low solubility in water, and a wide variety of products are available from dispersant manufacturers. Among them, a basic functional group-containing copolymer (for example, PB711 manufactured by Ajinomoto Finetech Co., Ltd.) and the like are preferable. By using the hydrophobic dispersant, it is possible to improve the water resistance of the colored layer to be formed, and thus the entire colored transparent three-layer film, as compared with the case of using a conventional hydrophilic dispersant. In addition, since there are many types of hydrophobic dispersants compared to hydrophilic dispersants, there is an advantage that a wide range of usable dispersants can be selected.

  As the binder used in the coating solution for forming the colored layer, a binder mainly containing at least one selected from silicon oxide, zirconium oxide, and titanium oxide can be preferably used. Moreover, the binder used for the coating liquid for forming the transparent coat layer is preferably one having silicon oxide as a main component. The binder in the coating solution for forming the colored layer and the coating solution for forming the transparent coat layer is almost completely dehydrated and condensed by the final heat treatment (for example, about 50 to 250 ° C.), so that silicon oxide, zirconium oxide, Or it becomes a hard film | membrane which has a titanium oxide as a main component.

  Specifically, when a transparent conductive layer forming coating solution is overcoated and coated on a transparent conductive layer formed by previously applying and drying a transparent conductive layer forming coating solution on the colored layer, the transparent conductive layer is formed. The binder of the coating liquid for forming the transparent coat layer soaks into the gaps between the noble metal-containing fine particle layers constituting the. And finally by heat treatment, both the binder in the transparent coating layer and the colored layer become a hard film mainly composed of silicon oxide and the like, and by being firmly bonded to the substrate and the noble metal-containing fine particles, conductivity, A colored transparent three-layer film having improved film strength and weather resistance can be obtained.

  The binder mainly composed of silicon oxide can be obtained by the following method. That is, water or an acid catalyst is added to an orthoalkyl silicate to hydrolyze it, and a dehydrating condensation polymerization is promoted, or a commercially available alkyl silicate solution that has already been polymerized to a 4 to 5 mer is added to water or an acid. A polymer obtained by adding an acid catalyst to further proceed hydrolysis and dehydration condensation polymerization (these are also called silica sols) can be used. However, if the dehydration condensation polymerization proceeds too much, the solution viscosity increases and eventually solidifies, so the degree of dehydration condensation polymerization needs to be adjusted below the upper limit viscosity that can be applied on the substrate. .

  Preferably, silica sol is used as the binder used in the coating liquid for forming the transparent coat layer, and the binder used in the coating liquid for forming the colored layer is silica sol or a silica sol to which titania sol and / or zirconia sol is added. Further, by adding magnesium fluoride fine particles or magnesium fluoride sol to the binder of the coating liquid for forming the transparent coating layer, the refractive index of the transparent coating layer is adjusted to change the reflectance of the colored transparent three-layer film. Is also possible.

  In the transparent conductive substrate, a colored transparent three-layer film structure comprising a colored layer in which colored pigment fine particles are dispersed in a binder, a transparent conductive layer in which noble metal-containing fine particles are dispersed in a binder, and a transparent coating layer. As a result, the reflectance can be greatly reduced. Furthermore, the reflectance of the colored transparent three-layer film is increased by adding zirconium oxide or titanium oxide to the binder of the colored layer to increase the refractive index of the colored layer, or adding magnesium fluoride to the binder of the transparent coating layer. It is possible to further reduce the refractive index by lowering the refractive index.

  Next, the colored layer forming coating solution, the transparent conductive layer forming coating solution, and the transparent coating layer forming coating solution used in the present invention can be produced by the following methods, respectively.

  First, the colored layer forming coating liquid is prepared by mixing colored pigment fine particles in a solvent together with a hydrophobic dispersant, and using a dispersion device such as a paint shaker, a bead mill, a sand mill, or an ultrasonic disperser, to obtain a uniform colored pigment fine particle dispersion. And And a binder, a solvent, etc. are added to this colored pigment fine particle dispersion, and component adjustment (colored pigment fine particle density | concentration, binder density | concentration, etc.) is performed, and the coating liquid for colored layer formation is prepared. If necessary, the dispersion treatment may be performed after previously mixing a binder with the colored pigment fine particles, the hydrophobic dispersant, and the solvent.

  The manufacturing method of the coating liquid for forming a transparent conductive layer will be described by taking an example in which the noble metal-containing fine particles are noble metal-coated silver fine particles. First, a known method [for example, Carey-Lea method: Am. J. Sci., 37 , 38, 47 (1889)], a colloidal dispersion of silver fine particles is prepared. Specifically, a mixed solution of an iron (II) sulfate aqueous solution and an aqueous sodium citrate solution is added to a silver nitrate aqueous solution to cause a reaction, the precipitate is filtered and washed, and then pure water is added to obtain a silver fine particle colloidal dispersion. It is done.

  By adding a reducing agent solution such as hydrazine and a gold salt solution and / or a platinum salt solution to the silver fine particle colloidal dispersion, gold or platinum alone or a gold-platinum complex or the like on the surface of the silver fine particles A dispersion of noble metal-coated silver fine particles coated with is obtained. If necessary, a small amount of a dispersant may be added to one or both of the colloidal dispersion of silver fine particles, the gold salt solution and the platinum salt solution in the coating step. The silver fine particle colloid dispersion and the noble metal coated silver fine particle dispersion may be prepared by any method as long as a dispersion of noble metal coated silver fine particles having an average particle diameter of 1 to 100 nm is finally obtained. It is not limited.

  Thereafter, the electrolyte concentration in the dispersion is preferably lowered by a method such as dialysis, electrodialysis, ion exchange, or ultrafiltration. This is because colloids generally aggregate in the electrolyte unless the electrolyte concentration is lowered, and this phenomenon is known as the Schulze-Hardy law. The noble metal-coated silver fine particle dispersion with the electrolyte concentration lowered in this way is concentrated by a conventional method such as a vacuum evaporator, ultrafiltration or the like to obtain a noble metal-coated silver fine particle dispersion.

  Then, an organic solvent or the like is added to the dispersion concentrate of the noble metal-coated silver fine particles, the components are adjusted (fine particle concentration, moisture concentration, etc.), and finally the transparent conductive layer forming coating solution containing the noble metal-coated silver fine particles is obtained. Prepared. In the step of preparing the coating liquid for forming a transparent conductive layer containing the noble metal-coated silver fine particles, a small amount of silica sol liquid may be blended as a component constituting the binder.

  In the step of preparing the coating liquid for forming the transparent conductive layer, the noble metal-coated silver fine particle dispersion is obtained by concentrating the noble metal-coated silver fine particle dispersion and condensing the noble metal-coated silver fine particles. Aggregated noble metal-coated silver fine particles can also be obtained. In this agglomeration treatment, a hydrazine solution is added little by little while stirring the noble metal-coated silver fine particle dispersion and concentrated, for example, kept at room temperature for several minutes to several hours to agglomerate, and then a hydrogen peroxide solution is added to add hydrazine. Decompose. If a coating solution for forming a transparent conductive layer in which noble metal-coated silver fine particles are aggregated in advance is used, a network structure (network structure) of noble metal-coated silver fine particles is easily formed. A transparent conductive layer can be easily formed.

  The coating liquid for forming the transparent coating layer can be prepared by adding a solvent or the like to a binder (silica sol liquid) containing silicon oxide as a main component and adjusting the components (fine particle concentration, moisture concentration, etc.). .

  Here, a colored layer obtained by applying and drying the colored layer forming coating solution, the transparent conductive layer forming coating solution, the solvent used in the transparent coating layer forming coating solution, and the colored layer forming coating solution. There is no restriction | limiting in particular as a solvent used by mixing with water at the time of washing | cleaning, According to the coating method and film-forming conditions, it can select suitably.

  Examples of the solvent include alcohol solvents such as methanol (MA), ethanol (EA), 1-propanol (NPA), isopropanol (IPA), butanol, pentanol, benzyl alcohol, diacetone alcohol (DAA); acetone, Ketone solvents such as methyl ethyl ketone (MEK), methyl propyl ketone, methyl isobutyl ketone (MIBK), cyclohexanone and isophorone; ethylene glycol monomethyl ether (MCS), ethylene glycol monoethyl ether (ECS), ethylene glycol isopropyl ether (IPC), Propylene glycol methyl ether (PGM), propylene glycol ethyl ether (PE), propylene glycol methyl ether acetate (PGM-AC), propylene Glycol derivatives such as N-glycol ethyl ether acetate (PE-AC), formamide (FA), N-methylformamide, dimethylformamide (DMF), dimethylacetamide, dimethylsulfoxide (DMSO), N-methyl-2-pyrrolidone ( NMP) and the like, but are not limited thereto.

  As described above, the transparent conductive base material manufactured by the manufacturing method according to the present invention, that is, the colored transparent three-layer film composed of the colored layer, the transparent conductive layer, and the transparent coat layer is provided on the transparent substrate. The transparent conductive substrate has a low haze value, excellent conductivity, low reflection characteristics, and excellent water resistance. Further, by providing the colored layer, the contrast is improved, and further by including colored pigment fine particles having a maximum absorption at 560 to 600 nm such as quinacridone colored pigment fine particles in the colored layer, a further excellent contrast improving effect is obtained. It is done.

  Therefore, the transparent conductive substrate of the present invention is, for example, CRT, plasma display panel (PDP), fluorescent display tube (VFD), field emission display (FED), electroluminescence display (ELD), liquid crystal display (LCD), etc. It can be used very suitably as a front plate of the display device. In these display devices, the front plate made of a transparent conductive substrate disposed on the front side of the display unit is usually incorporated with the colored transparent three-layer film side of the transparent conductive substrate as the outer surface. .

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

[Example 1]
5 g of carbon black fine particles (MA7, manufactured by Mitsubishi Chemical Corporation) having a specific surface area of 137 m ² / g and 0.5 g of a hydrophobic dispersant (manufactured by Ajinomoto Finetech, PB711), 94.5 g of diacetone alcohol (DAA) and After mixing, paint shaker dispersion was performed together with zirconia beads to obtain a carbon black fine particle dispersion (liquid A) having a dispersed particle diameter of 96 nm.

  After mixing 5 g of blue colored pigment fine particles (phthalocyanine blue # 5203, manufactured by Dainichi Seika Co., Ltd.) and 0.5 g of a hydrophobic dispersant (PB711) with 94.5 g of diacetone alcohol (DAA), together with zirconia beads A paint shaker was dispersed to obtain a phthalocyanine blue fine particle dispersion (liquid B) having a dispersion particle diameter of 105 nm.

  In addition, 5 g of red colored pigment fine particles (quinacridone # 44, manufactured by Dainichi Seika Co., Ltd.) having a maximum absorption at 570 to 580 nm and 0.5 g of a hydrophobic dispersant (PB711) were added to diacetone alcohol (DAA) 94. After mixing with 5 g, paint shaker dispersion was performed together with zirconia beads to obtain a quinacridone fine particle dispersion (liquid C) having a dispersion particle diameter of 113 nm.

  When the carbon black fine particle dispersion (liquid A), phthalocyanine blue fine particle dispersion (liquid B), and quinacridone fine particle dispersion (liquid C) were observed with a transmission electron microscope, the average particle diameter of the carbon black fine particles was 24 nm. The average particle size of the fine particles was 10 to 60 nm, and the particle size of the quinacridone fine particles was 10 to 90 nm.

Further, 19.6 parts of methyl silicate 51 (manufactured by Colcoat Co., Ltd .: trade name), 57.8 parts of ethanol (EA), 7.9 parts of 1% nitric acid aqueous solution, and 14.7 parts of pure water were used to obtain SiO ₂ ( Silicon oxide) A silica sol solution (solution D) having a solid content concentration of 10% and a weight average molecular weight of 1200 was obtained.

  Next, after adding said A liquid, B liquid, C liquid, and D liquid to ethanol (EA), propylene glycol monomethyl ether (PGM), and diacetone alcohol (DAA), amphoteric ion exchange resin (SMNUBP, Mitsubishi Chemical) Co., Ltd.) and a coating solution for forming a colored layer containing carbon pigment fine particles and a hydrophobic dispersant (carbon black: 0.025%, phthalocyanine blue: 0.05%, quinacridone : 0.1%, SiO2: 1.3%, water: 2.9%, EA: 80.6%, PGM: 10%, DAA: 5%).

  A colloidal dispersion of silver fine particles was prepared by the aforementioned Carey-Lea method. Specifically, a mixture of 390 g of 23% iron (II) sulfate aqueous solution and 480 g of 37.5% sodium citrate aqueous solution was added to 330 g of 9% silver nitrate aqueous solution, the precipitate was filtered and washed, and then pure water was added. Thus, a colloidal dispersion of silver fine particles (Ag: 0.15%) was prepared.

To 600 g of this silver fine particle colloidal dispersion, 80.0 g of a 1% aqueous solution of hydrazine monohydrate (N ₂ H ₄ .H ₂ O) was added and stirred, while stirring with an aqueous potassium metalate [KAu (OH) ₄ ] solution ( Au: 0.075%) A mixed solution of 4800 g and 1% polymer dispersant aqueous solution 2.0 g was added to obtain a colloidal dispersion of noble metal-coated silver fine particles having a surface coated with simple gold.

  The noble metal-coated silver fine particle colloidal dispersion was desalted with an ion exchange resin (Diaion SK1B, SA20AP, manufactured by Mitsubishi Chemical Corporation), and then the noble metal-coated silver fine particle dispersion was concentrated by ultrafiltration. Ethanol (EA) was added to the resulting liquid to disperse and concentrate the noble metal coated silver fine particles (Ag-Au: 1.6%, water: 20.0%, EA: 78.4%) (E liquid). Got.

Next, while stirring 60 g of this noble metal-coated silver fine particle dispersion concentrate (solution E), 0.8 g (1.6% Ag−) of hydrazine aqueous solution (N ₂ H ₄ .H ₂ O: 0.75%) was stirred. (100 ppm with respect to the Au dispersion) was added over 1 minute, then kept at room temperature for 15 minutes, and then 0.6 g of hydrogen peroxide aqueous solution (H ₂ O ₂ : 1.5%) was added over 1 minute. As a result, an aggregated noble metal-coated silver fine particle dispersion concentrate (liquid F) in which the noble metal-coated silver fine particles were aggregated in a chain form was obtained.

  The dispersion stability of the noble metal-coated silver fine particles when the hydrazine solution is added to the dispersion concentrate (liquid E) of the noble metal-coated silver fine particles, and the chain-like noble metal-coated silver fine particles aggregated by the addition of the hydrazine solution. The improvement of the dispersion stability in the aggregated noble metal-coated silver fine particle dispersion concentrate when the hydrogen peroxide solution was added to the dispersion concentrate was scientifically confirmed from the measured value of the zeta potential of each dispersion.

  Ethanol (EA), propylene glycol monomethyl ether (PGM), diacetone alcohol (DAA), and formamide (FA) are added to the aggregated noble metal-coated silver fine particle dispersion concentrate (F) obtained above, and aggregated noble metal-coated silver is added. Transparent conductive layer forming coating solution containing fine particles (Ag: 0.06%, Au: 0.24%, water: 6.5%, EA: 63.1%, PGM: 20%, DAA: 10%, FA: 0.03%) was obtained.

  When this transparent conductive layer forming coating solution was observed with a transmission electron microscope, the aggregated noble metal-coated silver fine particles had a shape in which the noble metal-coated silver fine particles having a primary particle size of about 6 nm were connected in a bead shape and partially branched (maximum aggregation length). 100 to 300 μm).

The silica sol solution (D solution) is a mixture of ethanol (EA), propylene glycol monomethyl ether (PGM), and diacetone alcohol (DAA) so that the final SiO ₂ solid content concentration is 0.95%. It diluted with (EA / PGM / DAA = 7/2/1), 0.005g of (gamma) -mercaptopropyltrimethoxysilane was added to 100g of obtained liquids, and the coating liquid for transparent coating layer formation was obtained.

  Next, after the colored layer forming coating solution is filtered through a filter having a filtration accuracy (pore size) of 5 μm, spin coating (110 rpm, 12 seconds) on a glass substrate (3 mm thick soda lime glass) heated to 43 ° C. 130 rpm, 80 seconds), followed by spin coating with pure water (130 rpm, 5 seconds) and washing. Subsequently, the transparent conductive layer-forming coating solution containing the aggregated noble metal-coated silver fine particles is filtered through a filter with a filtration accuracy (pore size) of 5 μm, spin-coated (130 rpm, 80 seconds), and finally for forming a transparent coat layer. The coating solution was spin coated (150 rpm, 80 seconds).

  Thereafter, the whole is cured by heating at 200 ° C. for 30 minutes, a colored layer containing colored pigment fine particles, a transparent conductive layer containing aggregated noble metal-coated silver fine particles, and a transparent silicate film mainly composed of silicon oxide. A glass substrate with a colored transparent three-layer film composed of a coating layer, that is, a transparent conductive substrate of Sample 1 according to Example 1 was obtained. The glass substrate was polished with a cerium oxide-based abrasive before use, washed with pure water and dried, and then heated to 35 ° C. for use.

  Regarding the transparent conductive substrate of Sample 1 according to Example 1, the binder, dispersant, and cleaning method of the colored layer are shown in Table 1 below, and the film characteristics of the colored transparent three-layer film formed on the glass substrate ( Table 2 shows the surface resistance, visible light transmittance, haze value, bottom reflectance / bottom wavelength, and film strength. Further, the transmission profile of the transparent conductive substrate of Sample 1 according to Example 1 is shown in FIG.

  The surface resistance of the colored transparent three-layer film was measured using a surface resistance meter Loresta AP (MCP-T400) manufactured by Mitsubishi Chemical Corporation. 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 shape and particle size (length) of the chain-like noble metal-coated silver fine particles were evaluated with a transmission electron microscope manufactured by JEOL. Further, the film strength was measured by reciprocating 100 times while pressing the eraser on the film surface with a load of 1 kg, and observing and evaluating the scratches on the film surface.

  In addition, the said bottom reflectance means the minimum reflectance in the reflection profile of a transparent conductive base material, and a bottom wavelength means the wavelength in which a reflectance is the minimum. In Table 1 below, the visible light transmittance of only the colored transparent three-layer film not including the transparent substrate (glass substrate) can be obtained by the following calculation formula 1. In the present specification, unless otherwise specified, as the transmittance, the value of the visible light transmittance of only the colored transparent three-layer film not including the transparent substrate is used.

[Calculation Formula 1]
Transmittance (%) of only colored transparent three-layer film not including transparent substrate = [(transmittance measured for each transparent substrate) / (transmittance of transparent substrate)] × 100

[Example 2]
10 parts of ethyl silicate 28 (manufactured by Colcoat Co., Ltd .: trade name), 4 parts of zirconiisopropoxide [Zr (OC ₃ H ₇ ) ₄ ] and 84 parts of isopropyl alcohol (IPA) were uniformly mixed, and then 34.5% nitric acid. 2 parts of the aqueous solution was gradually added dropwise to obtain a silica-zirconia composite sol solution (G solution) having a SiO ₂ —ZrO ₂ (silicon oxide-zirconia oxide) solid concentration of 4.4%.

Next, after adding the liquid A, liquid B, liquid C and liquid G of Example 1 to ethanol (EA), propylene glycol monomethyl ether (PGM), diacetone alcohol (DAA), the amphoteric ion exchange resin (SMUPB, manufactured by Mitsubishi Chemical Corporation) and subjected to deionization treatment, a coating solution for forming a colored layer (carbon black: 0.025%, phthalocyanine blue: 0) containing three kinds of colored pigment fine particles and a hydrophobic dispersant .05%, _{quinacridone: 0.1%, SiO 2 -ZrO 2} : 1.3%, water: 0.6%, EA: 83.5% , PGM: 10%, DAA: 5%) was obtained.

Further, the coating solution for forming the transparent coat layer was prepared by using the silica sol solution (D solution) of Example 1 with ethanol (EA) and propylene glycol monomethyl so that the final SiO ₂ solid content concentration was 0.9%. The mixture was diluted with a mixture of ether (PGM) and diacetone alcohol (DAA) (EA / PGM / DAA = 7/2/1), and 0.004 g of γ-mercaptopropyltrimethoxysilane was added to 100 g of the obtained liquid. It was adjusted.

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

  Regarding the transparent conductive substrate of Sample 2 according to Example 2 above, the binder, dispersant, and cleaning method of the colored layer are shown in Table 1 below, and the film characteristics of the colored transparent three-layer film formed on the glass substrate ( Table 2 shows the surface resistance, visible light transmittance, haze value, bottom reflectance / bottom wavelength, and film strength.

[Example 3]
After the coating solution for forming the colored layer is spin-coated on the glass substrate, the subsequent cleaning of the colored layer is performed by spinning a mixed solution of pure water and ethanol (EA) (pure water / EA (weight ratio) = 2/8). Except for coating, the same procedure as in Example 1 was carried out, and a colored layer containing colored pigment fine particles, a transparent conductive layer containing aggregated noble metal-coated silver fine particles, and a silicate containing silicon oxide as a main component. A glass substrate with a colored transparent three-layer film composed of a transparent coating layer of the film, that is, a transparent conductive substrate of Sample 3 according to Example 3 was obtained.

  About the transparent conductive base material of the sample 3 which concerns on the said Example 3, the film characteristic (surface resistance, visible-light transmittance, haze) of the colored transparent three-layer film formed on the glass substrate with the binder and washing | cleaning method of a colored layer Values, bottom reflectance / bottom wavelength, film strength) are shown in Table 1 below.

[Comparative Example 1]
After the coating solution for forming the colored layer was spin-coated on the glass substrate, the same procedure as in Example 1 was performed except that the subsequent cleaning of the colored layer was not performed. A glass substrate with a colored transparent three-layer film composed of a transparent conductive layer containing aggregated noble metal-coated silver fine particles and a transparent coating layer of a silicate film mainly composed of silicon oxide, that is, a sample according to Comparative Example 1 4 transparent conductive substrates were obtained.

  In the transparent conductive substrate of Sample 4 according to Comparative Example 1, the binder, dispersant, and cleaning method of the colored layer are shown in Table 1 below, and the surface resistance of the colored transparent three-layer film formed on the glass substrate is shown. The results are shown in Table 2 below. However, when applying and drying the coating liquid for forming the transparent conductive layer on the colored layer, the noble metal-coated silver fine particles in the coating liquid were agglomerated and a good transparent conductive layer was not obtained. The optical properties of the film were not measured.

  As is clear from the results shown in Tables 1 and 2, in the transparent conductive base materials of Samples 1 to 3 according to each example, the transparent conductive layer was washed with water or a solvent containing water after washing the colored layer. Since the coating solution for forming is coated, the colored transparent three-layer film has all of the surface resistance, visible light transmittance, haze value, reflectance, and film strength even though the colored layer contains a hydrophobic dispersant. It shows excellent properties. On the other hand, since the transparent conductive substrate of Sample 4 according to Comparative Example 1 does not wash the colored layer, the noble metal-coated silver fine particles of the coating solution for forming the transparent conductive layer aggregate on the colored layer containing the hydrophobic dispersant. Therefore, the surface resistance of the colored transparent three-layer film is extremely high and does not show any function as a transparent conductive film.

  Further, as is clear from the transmission profile shown in FIG. 1, the transparent conductive substrate of Sample 1 according to Example 1 has a sharp absorption around 575 nm in the visible light region. Is applied to the front plate of a display device such as a CRT, it has been confirmed that it has an extremely excellent contrast improving effect.

3 is a graph showing a transmission profile of a transparent conductive substrate of Sample 1 according to Example 1. FIG.

Claims (8)

In the method for producing a transparent conductive substrate comprising a colored transparent three-layer film composed of a colored layer, a transparent conductive layer, and a transparent coat layer sequentially formed on a transparent substrate,
A coating solution for forming a colored layer mainly composed of a solvent, colored pigment fine particles dispersed in the solvent, a hydrophobic dispersant, and a binder is coated on a transparent substrate and dried, and then water or a solvent containing water. Next, a transparent conductive layer-forming coating liquid mainly composed of a solvent and noble metal-containing fine particles dispersed in the solvent is applied and dried, and then transparent mainly composed of a solvent and a binder. A method for producing a transparent conductive substrate, comprising: applying and drying a coating layer forming coating solution, followed by heat treatment. The noble metal-containing fine particles are selected from gold-silver alloy fine particles, platinum-silver alloy fine particles, gold-silver-platinum alloy fine particles, and noble metal-coated silver fine particles whose surface is coated with gold alone or platinum alone or a composite of gold and platinum. The method for producing a transparent conductive substrate according to claim 1, wherein the transparent conductive substrate is at least one kind. The colored pigment fine particles are at least one selected from carbon fine particles, titanium black fine particles, titanium nitride fine particles, phthalocyanine pigment fine particles, quinacridone pigment fine particles, and dioxazine pigment fine particles. 2. A method for producing a transparent conductive substrate according to 2. The transparent conductive substrate according to claim 1, wherein at least one of the colored pigment fine particles is a colored pigment fine particle having a maximum absorption in a visible light wavelength range of 560 to 600 nm. Manufacturing method. The transparent in any one of Claims 1-4 in which the binder in the said coating liquid for colored layer formation has as a main component at least 1 sort (s) chosen from silicon oxide, zirconium oxide, and titanium oxide. A method for producing a conductive substrate. The method for producing a transparent conductive substrate according to any one of claims 1 to 5, wherein the binder in the coating liquid for forming a transparent coat layer contains silicon oxide as a main component. A transparent conductive film comprising a colored transparent three-layer film produced by the method according to claim 1 and composed of a colored layer, a transparent conductive layer, and a transparent coating layer on a transparent substrate. Base material. A display device comprising a front plate disposed on the front side of the display unit of the device main body, wherein the transparent conductive substrate according to claim 7 is incorporated with the colored transparent three-layer film side as an outer surface as the front plate. A display device.

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