JPH1053758A - Coating solution for forming conductive film, its freezing product, production of conductive film, and cathode ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a stable long-term storage of a freezing product of a coating soln. which contains fine conductive particles and is used for forming a conductive film and to efficiently form a conductive film on the surface of a cathode ray tube by causing the soln. to freeze to give a freezing product and thawing it to give a coating soln. when it is used for forming a conductive film. SOLUTION: A coating soln. contg. fine conductive particles is frozen to give a freezing product, which is thawed just before being applied to form a conductive film. This soln. pref. contains at least 40wt.% water. When the soln. further contains 0.5-60wt.% org. solvent (e.g. butyl cellosolve or N- methylpyrrolidone), a more uniform film can be formed. Examples of the particles are antimony-doped tin oxide, indium-tin oxide, ruthenium oxide, and metals such as silver, gold, and platinum. This soln. is applied to the image display face of a panel for a cathode ray tube to form a film on it, thus providing it with antistatic effects and electromagnetic shielding effects.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a frozen body of a coating solution for forming a conductive film, a coating solution for forming a conductive film, a method for manufacturing a conductive film, and a cathode ray tube.

[0002]

2. Description of the Related Art A cathode ray tube has an operating voltage of 25 to 32.
Since a high voltage of about kV is applied, dust adheres to the surface due to the charged static electricity, making the image difficult to see, or receiving an electric shock due to electric discharge when a human body touches the outer surface. It is widely practiced to form a conductive film on the substrate to prevent this.

[0003] Further, since external light is reflected on the surface of the panel, which is the front glass of the cathode ray tube, and the image becomes difficult to see, prolonged vision tends to cause eyestrain. As a preventive measure,
It is also necessary to perform low reflection processing in the visible light range together with antistatic processing. In addition, from the point of human safety,
It has been desired to prevent leakage of electromagnetic waves generated from a cathode ray tube flyback transformer and a deflection yoke coil.

[0004] Electromagnetic wave leakage can be prevented by forming a transparent conductive film on the surface of a cathode ray tube. Generally, a surface resistance of 10 ⁸ to 10 ¹⁰ Ω / □ is used for antistatic, and a surface resistance of 10 ² to 10 is used for shielding electromagnetic waves. ^{8 Ω} / □, especially 10 ² ~10 ³ Ω /
The film of □ is used.

Conventionally, as such a low reflection antistatic film, a method of forming a plurality of thin films on a glass surface with the refractive index and the film thickness being controlled to predetermined values is generally known.

More specifically, in addition to a wet method (a method of forming a transparent conductive film and a low refractive index film on a glass surface by a spray method, a spin coating method or the like) described in Japanese Patent Application Laid-Open No. 1-299887, a dry method (a CVD method) , A method of forming a plurality of thin films by a sputtering method, a vacuum evaporation method, or the like), and a method of combining both a wet method and a dry method.

[0007] The wet method does not require an expensive vacuum apparatus as compared with the dry method, and thus is advantageous in terms of mass production and equipment costs. In the case of the wet method, it is relatively easy to add an inorganic pigment, an organic pigment, an organic dye, or the like to a coating solution for forming a coating film to impart light absorbency in order to improve contrast with respect to ambient light.

The low-reflection antistatic film has a two-layer structure of a low-refractive-index material film on the air side and a high-refractive-index conductive material film on the transparent substrate side, or a multilayer structure of three or more layers. Light interference films are common. The anti-reflection method using such a multilayer film configuration requires precise film thickness control and film uniformity over the entire coated surface.

[0009] If foreign matter is present on the panel surface during spin coating, the film thickness around the surface will change, resulting in different defects of interference colors. As a feature of the spin coating, the liquid dropped on the surface of the CRT panel spreads in the outer circumferential direction due to centrifugal force generated by the rotation of the panel. Therefore, if there is a foreign substance, the defect greatly expands in the outer circumferential direction starting there. Therefore, it is necessary to clean the coating environment in order to prevent foreign matter from adhering. However, since the cost for maintaining a high degree of cleanliness is large, a coating liquid whose defect is unlikely to be expanded even when foreign matters are present has been demanded.

Further, in order to obtain uniformity of the film, it is necessary that the conductive fine particles are uniformly dispersed in the coating solution for forming the coating film. If agglomerates of particles, that is, coarse particles, are present in the coating solution, agglomerates are generated on the film surface at the time of coating, and these often become nuclei and become defects.

On the other hand, when the coating liquid is stored for a long period of time, it is well known that the conductive fine particles in the coating liquid that collided due to Brownian motion coalesce and coagulate with time. For this reason, conventionally, it has been necessary to use the coating liquid for forming a conductive film within a limited number of days after production. Therefore, it has been desired to suppress the aggregation of particles during storage of the liquid and extend the expiration date of the liquid.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide a frozen conductive film forming liquid which can stably store a conductive film forming liquid, and a conductive liquid forming coating liquid obtained from the frozen liquid. And a cathode ray tube on which the conductive film is formed.

Another object of the present invention is to provide a coating solution for forming a conductive film, which can form a uniform film on the surface of a cathode ray tube, hardly expand defects even if foreign substances are present, and can be stably stored for a long period of time. An object of the present invention is to provide a method for producing a conductive film using a liquid and a cathode ray tube on which the conductive film is formed.

[0014]

SUMMARY OF THE INVENTION The present invention provides a frozen conductive film-forming coating solution containing conductive fine particles, a method for producing a conductive film using a conductive film-forming coating solution obtained from the frozen body, and a method for manufacturing the conductive film. Provided is a cathode ray tube having a conductive film formed thereon.

By using a frozen form of the conductive film forming coating solution of the present invention, the conductive film forming coating solution can be stably stored for a long period of time. The coating liquid is frozen at the time of non-use other than at the time of coating, and thawed before use to form a coating liquid, and the coating liquid is applied to the substrate, whereby the conductive film can be efficiently formed.

[0016] The frozen body of the coating solution of the present invention preferably contains water by 40% by weight or more. This is because a frozen body can be easily obtained at a predetermined temperature of 0 ° C. or less.

The frozen body of the coating solution of the present invention is prepared, for example, by mixing an organic solvent, water and conductive fine particles with a water content of 40%.
It is obtained by mixing so as to be not less than weight% and freezing at 0 ° C. or less.

The frozen body of the coating solution of the present invention does not contain a component that changes with time. As a result, the expiration date of the liquid can be greatly extended by storing it frozen. The components that change over time include silicate hydrolysates, alkoxides such as transition metals, hydrolysates thereof, and chelate compounds.

The present invention also relates to butyl cellosolve, N-
A coating solution for forming a conductive film, comprising one or more organic solvents selected from the group consisting of methylpyrrolidone, tetrahydrofurfuryl alcohol, N, N-dimethylformamide and dimethylsulfoxide, water, and conductive fine particles, The content ratio of the organic solvent in the coating solution is 0.5
A coating solution for forming a conductive film, a method for producing a conductive film using the coating solution, and a cathode ray on which the conductive film is formed, wherein the content ratio of water is 40 to 95% by weight. Provide a tube.

The coating solution of the present invention contains water in an amount of 40% by weight or more. This is because a frozen body can be easily obtained at a predetermined temperature of 0 ° C. or less. On the other hand, the content is set to 95% by weight or less. If the content exceeds 95% by weight, repelling or the like occurs when the composition is applied to a substrate such as a panel for a cathode ray tube, and it becomes difficult to apply the composition uniformly.

In the coating solution of the present invention, one or more organic solvents selected from the group consisting of butyl cellosolve, N-methylpyrrolidone, tetrahydrofurfuryl alcohol, N, N-dimethylformamide and dimethylsulfoxide are used in an amount of 0.5 to 0.5%. ６０60% by weight. With these organic solvents, a uniform film can be formed.

Since the coating liquid of the present invention contains water in an amount of 40% by weight or more, the content of the organic solvent is 60% by weight or less. However, if the amount is less than 0.5% by weight, good results cannot be obtained.

As the conductive fine particles in the present invention, metal oxide fine particles or metal fine particles are used. Because of excellent conductivity and dispersibility, as the metal oxide,
One or more selected from the group consisting of antimony-doped tin oxide, indium tin oxide and ruthenium oxide is preferable, and the metal is selected from the group consisting of silver, gold, platinum, ruthenium, palladium, nickel and cobalt. More than species are preferred.

When antimony tin oxide or indium tin oxide is used, a transparent conductive film is obtained, and when ruthenium oxide, silver or ruthenium is used, a light-absorbing low-resistance conductive film is obtained.

Since the coating solution of the present invention contains the above-mentioned organic solvent, water and conductive fine particles in the above-described ratio, the coating solution has good wettability to a substrate and can form a uniform film even when foreign substances are present.

A black pigment can be added to the coating solution of the present invention. As the black pigment, carbon black and / or titanium black are preferable. By including carbon black and / or titanium black as a black pigment,
A light-absorbing film is obtained, and a high-contrast conductive film of the present invention can be formed.

The coating solution of the present invention can be stored frozen.
Since the coating solution of the present invention does not contain a component that changes with time, the storage period of the solution can be significantly extended by freezing and storing. The components that change over time are hydrolysates of silicates, alkoxides such as transition metals and hydrolysates thereof,
And chelating compounds.

A conductive film can be formed by applying the coating solution of the present invention to a substrate. The film formed using the coating solution of the present invention is suitable for a transparent substrate such as a panel for a cathode ray tube, in particular, a face surface on which an image of the panel for a cathode ray tube is displayed.

The method for applying the coating solution of the present invention is not particularly limited as long as it is a wet method. When a film is formed on a cathode ray tube panel surface by a spin coating method, generally, an outer surface of a cathode ray tube panel face (hereinafter, referred to as a face surface).
After washing and drying, the coating liquid is dropped from a nozzle arranged opposite to the face surface while rotating the cathode ray tube at a low speed of 100 to 150 rpm while maintaining the temperature at 30 to 50 ° C.

The coating solution applied to the face surface flows in a peripheral direction along the outer surface of the face surface due to centrifugal force generated by rotation, and excess coating solution scatters from the peripheral portion, and a uniform coating solution is applied to the outer surface of the face. A film is formed. In order to spread the coating liquid containing conductive fine particles uniformly, the surface tension,
It is necessary to control viscosity and drying speed optimally. Therefore, by considering the surface tension, viscosity, vapor pressure and the like of the solvent constituting the coating liquid and blending it as in the present invention, a uniform film having a small thickness deviation on the face surface can be obtained.

As described above, the coating solution of the present invention can be frozen and stored, so that it is stable for a long period of time. Therefore, it can be used not only in the spin coating method but also in any film forming method such as the spray coating method and the dip coating method. it can.

Further, a low-refractive-index film can be formed on a conductive film formed using the coating solution of the present invention to form a low-reflection conductive film. Examples of the low refractive index film include silica and magnesium fluoride.

The thickness of the conductive film formed by using the coating solution of the present invention is preferably about 100 nm, and the thickness of the low refractive index film is preferably about 100 nm.

[0034]

EXAMPLES Examples (Examples 1 to 9 and 11) and Comparative Examples (Examples 10 and 12) will be specifically described below, but the present invention is not limited to the following Examples.

[Examples 1 to 10] The fine particles shown in the fine particle column of Table 1 were dispersed in the amount of water (ion-exchanged water) shown in the water column of Table 1, and then dispersed in the organic solvent column of Table 1. The solvent was stirred and mixed to obtain a coating liquid for forming a conductive film (coating liquid A). In addition,
The numbers in Table 1 indicate the amounts of the raw materials (unit:% by weight).

Sb: SnO ₂ is antimony tin oxide, ITO is indium tin oxide, Ag is silver,
Ru is ruthenium, CB is carbon black, Ti-
B indicates titanium black, and SiO ₂ -S indicates silica sol. BC is butyl cellosolve, N-MP is N-methylpyrrolidone, THFA is tetrahydrofurfuryl alcohol, DMF is N, N-dimethylformamide, D
MSO is dimethyl sulfoxide, ETA is ethanol,
EC indicates ethyl cellosolve.

Next, ethyl orthosilicate 4% by weight, concentrated nitric acid 1% by weight, ethanol 60% by weight, propylene glycol monomethyl ether 25% by weight, diacetone alcohol 1%
0% by weight was mixed, stirred, hydrolyzed and polymerized to obtain a coating liquid for forming a low refractive index film (coating liquid B).

After washing and drying the face, 30 to 50 ° C.
While the cathode ray tube was rotated at a low speed of 100 to 150 rpm, the coating solution A was dropped from a nozzle arranged opposite to the face surface. After the coating film was dried, the coating liquid B was dropped while rotating the cathode ray tube again at a low speed of 100 to 150 rpm. Next, the face surface is heated at 160 ° C. for 30 minutes.
The low reflection conductive film was formed on the surface by holding for a minute. The film formation was performed under a booth with a cleanness of 1000.

Table 2 shows the results of evaluation of the obtained non-reflective conductive film for unevenness of film thickness in the face surface by using a spectral reflectance measuring system (manufactured by Easy and Gamma Science). As an evaluation method, by the system, the reflection characteristic in the face surface is measured, the maximum value and the minimum value of the bottom wavelength in the face surface are measured, and the bottom wavelength shifts to the longer wavelength side as the film thickness increases, Since the bottom wavelength shifts to the shorter wavelength side as the film thickness becomes thinner, the smaller the difference between the maximum value and the minimum value (that is, the film thickness unevenness), the more uniform the film.

In addition, Table 2 shows the results of evaluation of the visibility of appearance defects. As an evaluation method, an appearance inspection was performed, and the number of defects accompanied by tailing of 2 mm or more was counted.

Example 11 The procedure of Example 2 was repeated, except that the coating solution A used in Example 2 was used instead of the coating solution A used in Example 2, which was frozen at -20 ° C., stored for 4 months and thawed. Film,
evaluated. Table 2 shows the results.

Example 12 The same as Example 9 except that the coating solution A of Example 9 was used after being stored at room temperature (25 ° C.) for 4 months instead of the coating solution A used in Example 9. Film on the
evaluated. Table 2 shows the results.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

According to the present invention, by using a frozen body of the coating liquid for forming a conductive film of the present invention, the coating liquid for forming a conductive film can be stably stored for a long period of time.

Further, according to the coating solution for forming a conductive film of the present invention, a conductive film can be uniformly formed on the surface of a cathode ray tube or the like. Since a small amount of conductive film is obtained, it is preferably used on the outer surface of an image display area of an image display device such as a cathode ray tube, a liquid crystal display, and a plasma display used for receiving a television broadcast and the like, and can impart an antistatic effect and an electromagnetic wave shielding effect. .

The coating solution for forming a conductive film of the present invention can be stably stored for a long period of time.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication location H01J 9/20 H01J 9/20 A 29/88 29/88 H05F 1/02 H05F 1/02 E / / C23C 24/00 C23C 24/00

Claims (10)

[Claims] 1. A frozen body of a coating solution for forming a conductive film containing conductive fine particles. 2. A method for producing a conductive film, comprising thawing the frozen body of claim 1 to obtain a coating solution for forming a conductive film, and applying the coating solution on a substrate to form the conductive film. 3. A low-reflection conductive film, comprising: thawing the frozen body of claim 1 to obtain a coating solution for forming a conductive film; and applying the coating solution on a substrate to form a low-refractive-index film. Manufacturing method of membrane. 4. A cathode ray tube having a conductive film formed on a face of a cathode ray tube panel on which an image is displayed by the method for producing a conductive film according to claim 2. 5. An organic solvent, water and conductive fine particles are mixed so that the water content is 40% by weight or more.
A method for producing a frozen body of a coating solution for forming a conductive film, which is frozen below. 6. A conductive material comprising one or more organic solvents selected from the group consisting of butyl cellosolve, N-methylpyrrolidone, tetrahydrofurfuryl alcohol, N, N-dimethylformamide and dimethylsulfoxide, water, and conductive fine particles. A coating solution for forming a film, wherein the content of the organic solvent in the coating solution is 0.5 to 60% by weight, and the content of water is 40 to 95% by weight. Forming coating solution. 7. The coating liquid for forming a conductive film according to claim 6, wherein the coating liquid contains carbon black and / or titanium black as a black pigment. 8. A method for producing a conductive film, comprising applying the coating liquid for forming a conductive film according to claim 6 on a substrate. 9. A method for producing a low-reflection conductive film, comprising forming a low-refractive-index film after applying the coating solution for forming a conductive film according to claim 6 on a substrate. 10. A cathode ray tube having a conductive film formed by applying the coating solution for forming a conductive film according to claim 6 or 7 on a face surface of a cathode ray tube panel on which an image is displayed.