JP2000113811A - Forming method of cathode ray tube panel having conductive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a conductive film having high efficiency by low-temperature heat treatment by coating fluid containing sols of Ru metallic fine particles to a cathode ray tube panel, heating it, forming a conductive film, and forming a film having the index of refraction lower than that of the conductive film on the connective film. SOLUTION: Metal to be used to form a conductive film is Ru metal, and the Ru metal is used as fine particles. As metallic fine particles, metallic fine particles formed by evaporative condensation of metal or metallic fine particles formed by chemically reducing metallic salt are used. Coating fluid for forming the conductive film is prepared by uniformly dispersing Ru metallic fine particles to water or organic solvent in the form of sols. The coating fluid is applied on a base body so as to have the specified thickness after drying and heated to form the conductive film. A low reflection film is formed on the formed conductive film by making use of the interference action of light, and therefore, the index of refraction can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a cathode ray tube panel with a conductive film.

[0002]

2. Description of the Related Art Since a cathode ray tube panel operates at a high voltage, static electricity is induced on its surface at the time of start-up or termination. Dust adheres to the surface of the CRT panel due to the static electricity, causing a decrease in contrast, and when the CRT panel is directly touched with the hand, a slight electric shock often causes discomfort.

In order to prevent the above-mentioned phenomenon, various attempts have been made to apply an antistatic film to the surface of the CRT panel. For example, Japanese Patent Application Laid-Open No. 63-76247 discloses that the surface of a CRT panel is heated to about 350 ° C. And the surface has C
A method of providing a conductive oxide layer such as tin oxide and indium oxide by a VD method is disclosed.

[0004] However, in this method, in addition to the cost of the film forming apparatus, the surface of the CRT panel is heated to a high temperature, so that the phosphor in the CRT may fall off or the dimensional accuracy may be reduced. Was. In addition, tin oxide is most commonly used as a material used for the conductive layer. However, in the case of tin oxide, there is a disadvantage that it is difficult to obtain a high-performance film by low-temperature treatment.

[0005] In recent years, shielding of electromagnetic waves has also been required. By interposing the conductive coating on the surface of the cathode ray tube panel, the conductive coating is irradiated with electromagnetic waves and induces an eddy current in the coating, thereby reflecting the electromagnetic waves. It is necessary that the conductive coating film has good conductivity to withstand high electric field strength, but it has been more difficult to obtain a film having such good conductivity.

On the other hand, as a method of manufacturing a conductive film, for example,
As described in JP-A-6-310058 and the like, there is a method in which a mixed solution of a metal salt and a reducing agent is applied to the surface of a cathode ray tube panel to form a conductive film. It becomes a state plated on the surface,
There is a problem that the strength of the film is extremely weak and a step of cleaning the conductive film to remove by-product salts is required.

[0007] The formation of a low-reflection conductive film by a coating method is not limited to conventional optical devices, but also to consumer devices, particularly TVs and CRTs of computer terminals.
Numerous studies have been made on. The traditional method is
For example, as described in JP-A-61-118931, an SiO ₂ layer having fine irregularities is attached to the surface of a cathode ray tube panel so as to have an antiglare effect,
A method has been adopted in which the surface is etched with hydrofluoric acid to form irregularities. However, these methods are called non-glare treatment that scatters external light, and are not essentially a method of providing a low-reflection layer. Therefore, there is a limit in reducing the reflectance. It is also the cause of lowering.

[0008]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned drawbacks of the conductive film and the low-reflective conductive film of the prior art. An object of the present invention is to provide a method for forming a CRT panel having a conductive film and a method for forming a CRT panel having a low-reflection conductive film.

[0009]

SUMMARY OF THE INVENTION The present invention provides a method of forming a CRT panel with a conductive film, which comprises applying a coating solution containing a sol of Ru metal fine particles to a CRT panel and heating the coating solution. A feature of the present invention is to use a coating solution containing metal fine particles in the form of a sol in forming a conductive film. When this coating solution is applied on a substrate to form a conductive film, a conventional method is used. Unlike the plating film described above, minute holes are introduced into the conductive film.

When a coating solution containing a hydrolyzate of a silicon alkoxide forming a silicon compound is applied on the conductive film, the silicon compound penetrates into the pores, and the film strength is remarkably improved. Further, in the present invention, unlike the above-mentioned conventional method using a coating solution composed of a metal salt and a reducing solution, by-products are not generated during the formation of the conductive film, and the conductive film and the film formed thereon are not formed. There is no deterioration in film strength between the two. Therefore, according to the present invention, it is possible to form a conductive film that solves the above-mentioned problem or a low-reflective conductive film that includes at least one conductive film on the surface of a CRT panel.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to embodiments of the present invention. The metal used to form the conductive film in the present invention is Ru metal, and Ru metal is used as fine particles. As the metal fine particles, for example, metal fine particles generated by evaporation and condensation of the metal,
Alternatively, metal fine particles produced by chemically reducing the metal salt are preferably used.

The metal salt used in the present invention for producing metal fine particles by chemical reduction includes, for example, nitrates such as ruthenium nitroso nitrate; chlorides such as ruthenium chloride, ruthenium ammonium chloride, ruthenium potassium chloride and ruthenium sodium chloride; acetic acid Acetates such as ruthenium;

Examples of the metal salt reducing agent include hydrides such as sodium borohydride, potassium borohydride, sodium hydride and lithium hydride, formic acid,
Organic acids such as oxalic acid, phosphinic acid and sodium phosphinate, inorganic acids and salts can be used. The method for reducing and depositing the metal fine particles is not particularly limited. For example, a method of dissolving a metal salt in water or an organic solvent, adjusting the pH with ammonia or the like as necessary, and then adding a reducing agent can be used. In this method, it is preferable to adjust the reaction temperature depending on the type of the metal salt. The generated metal fine particles are appropriately washed and dried. The powder volume resistance of the metal fine particles obtained as described above is preferably 0.01 Ω · cm or less.

The coating liquid for forming the conductive film is Ru.
It is prepared by uniformly dispersing metal fine particles in the form of a sol in water or an organic solvent. Metal fine powder
If the particle size is too large, dispersion becomes difficult, so the average particle size is preferably 100 nm or less. More preferably, it is 5 to 80 nm. Further, in order to improve the dispersibility of the metal fine particles, the surface of the metal fine particles may be partially oxidized by heating, irradiation with ultraviolet rays, immersion in an oxidizing agent, or the like. The content of the metal fine particles in the coating liquid is not particularly limited, but is usually about 0.05 to 10% by weight, and the content is adjusted so that the formed conductive film has a predetermined thickness.

In preparing a coating solution, it is important to uniformly disperse metal fine particles in water, an organic solvent, or the like. For this purpose, it is necessary to perform sufficient stirring to facilitate the contact between the solvent and the metal fine particles. As the stirring means, for example, a commercially available pulverizer / disperser such as a colloid mill, a ball mill, a sand mill, and a homomixer can be used. Moreover, when dispersing, it can also be heated in the range of 20 to 200 ° C. When stirring at a temperature higher than the boiling point of the solvent, the pressure is increased so that the liquid layer can be maintained. Thus, an aqueous sol or organosol in which Ru metal fine particles are dispersed as colloid particles is obtained.

In the present invention, the aqueous sol can be used as a coating solution as it is. However, in order to enhance the coating property on the substrate, metal fine particles may be dispersed in an organic solvent,
Alternatively, the water of the aqueous sol can be replaced with an organic solvent before use.

The organic solvent used for the formation of the organosol and the replacement of the above-mentioned medium is preferably a hydrophilic organic solvent, for example, alcohols such as methanol, ethanol, propyl alcohol and butanol; ethyl cellosolve, methyl cellosolve, Ethers such as butyl cellosolve and propylene glycol methyl ether;
Ketones such as 2,4-pentadione and diacetone alcohol; and esters such as ethyl lactate and methyl lactate.

In order to adjust the viscosity, surface tension, spreadability, etc. of the solution, Si (OR) _y · R ′ _4-y (where y is 3 or 4) R,
R 'is an alkyl group. ) And other hydrolyzable silicon compounds,
Alternatively, a partial hydrolyzate thereof can be added. The silicon compound can be added at an arbitrary ratio to the metal fine particles. However, considering the conductivity and the strength of the conductive film, the metal compound / silicon compound (weight ratio) in terms of SiO ₂ is 1
/ 6 to 10/1, more preferably 1/4 to
It is about 5/1.

The coating solution contains at least one oxide of a metal selected from the group consisting of Sn, Sb, In, Zn, Ga, Al and Ru in order to adjust the thickness of the conductive film. It can be contained in the form of a sol similar to the fine particles. The metal oxide can be used at an arbitrary ratio to the metal fine particles, but a preferable metal fine particle / metal oxide (weight ratio) is 99/1 to 60/40, more preferably 95/5 to 70/30. is there. Further, various surfactants can be added to the coating solution in order to improve the wettability with the substrate. The concentration (solid content) of the coating solution when a silicon compound or a metal oxide is contained together with the metal fine particles is 0.05 to
About 10% by weight is preferable.

The coating solution thus obtained is applied on a substrate to a predetermined thickness after drying, and heated to form a conductive film. The thickness of the conductive film is not particularly limited, but is usually about 50 to 150 nm.

The method of applying the coating solution to the substrate is not particularly limited, and examples thereof include spin coating, dip coating,
A method such as spray coating is preferred. In addition, the surface may be formed to have an anti-glare effect by using a spray coating method, and a hard coat such as a silica coating may be provided thereon. Further, the conductive film of the present invention is formed by either a spin coating method or a spray coating method, and the solution containing the silicon alkoxide is spray-coated thereon to form a non-glare coat of a silica coating having irregularities on the surface. It may be provided.

When a solvent having a low boiling point is used in the coating solution containing the Ru metal fine particle sol in the present invention, a uniform coating film can be obtained by drying at room temperature, but a medium having a boiling point in the range of 100 to 250 ° C. When a high-boiling solvent is used, heat treatment is performed because the solvent remains in the coating film at room temperature. The upper limit of the heating temperature is determined by the softening point of the CRT panel as the substrate. Considering this point, a preferable heating temperature range is 100 to 500 ° C.

In the present invention, a low-reflection film can be formed on the conductive film formed by the above method by utilizing the interference effect of light. For example, when the substrate is glass (refractive index n = 1.
52) The reflectance is reduced most by forming a low refractive index film such that the ratio of n (conductive film) / n (low refractive index film) is about 1.23 on the conductive film. be able to. To reduce the reflectance, in the visible light region, especially 555
Although it is preferable to reduce the reflectance of light having a wavelength of nm, it is preferable to determine the reflectance appropriately in consideration of the reflection appearance and the like in practical use.

The outermost low-refractive-index film of such a two-layer low-reflection conductive film has at least one layer selected from a solution containing MgF ₂ sol and a solution containing silicon alkoxide.
Films formed using seed solutions are preferred. MgF ₂ is the lowest among the above materials in terms of refractive index, and it is preferable to use a solution containing MgF ₂ sol to reduce the reflectance. However, SiO ₂ is mainly used in terms of film hardness and scratch resistance. A membrane as a component is preferred.

Various solutions can be used as a solution containing a silicon alkoxide for forming such a low refractive index film, but Si (OR) _y .R ′ _4-y (y is 3 or 4. R,
R 'is an alkyl group. )), A liquid containing a silicon alkoxide or a partial hydrolyzate thereof is preferable. As the silicon alkoxide, for example, silicon ethoxide, silicon methoxide, silicon isopropoxide,
Monomers such as silicon butoxide or polymers thereof are preferred.

The silicon alkoxide is usually used by dissolving it in alcohol, ester, ether or the like.
In addition, hydrochloric acid, nitric acid, sulfuric acid, acetic acid, formic acid, maleic acid, hydrofluoric acid, or an aqueous ammonia solution may be added to the above-mentioned solution for hydrolysis. The content of the silicon alkoxide in the solution is not particularly limited, but if the solid content is too large, the storage stability is reduced. Therefore, it is preferable to use the silicon alkoxide at a solid content of 30% by weight or less based on the solvent.

When MgF ₂ is used for forming a low refractive index film, MgF ₂ fine particles are used, and the fine particles are uniformly formed as colloid particles stable in a solvent such as water or an organic solvent in the same manner as described above. Used as an aqueous sol or an organosol. The preferred concentration of MgF ₂ in the dispersion is the same as in the case of silicon alkoxide. As the organic solvent, the above-mentioned organic solvents can be used.

In order to improve the strength of the film, the above solution or dispersion contains Zr and T as binders.
Addition of alkoxides such as i, Sn, Al and the like and partial hydrolysates thereof to form ZrO ₂ , TiO ₂ , SnO ₂ , A
l ₂ O ₃ 1 species, such as, or two or more composite MgF ₂
Or SiO ₂ may be precipitated at the same time. The addition amount of these alkoxides and the like to the above solution or dispersion may be set to 0.1 to silicon alkoxide and / or MgF ₂ .
About 1 to 10% by weight is preferable.

Further, if necessary, a surfactant may be added to the above solution or dispersion in order to improve the wettability with the substrate. Examples of the surfactant to be added include sodium linear alkylbenzene sulfonate, alkyl ether sulfate, and the like. Using the above solution or dispersion for forming a low refractive index film, a low refractive index film is formed on the conductive film in the same manner as in the case of forming the conductive film.

The method for forming a low-reflection conductive film according to the present invention can be applied to a low-reflection conductive film by a multilayer interference effect. As a configuration of a multilayer low-reflective film having anti-reflection performance, for example, λ is the wavelength of light to be anti-reflective,
From the substrate side, the high-refractive-index layer-low-refractive-index layer is formed with an optical thickness of λ / 2.
A two-layer low-reflection film formed at λ / 4 or λ / 4-λ / 4, a medium refractive index layer, a high refractive index layer, and a low refractive index layer formed from the substrate side with an optical thickness of λ / 4-λ / 3-Layer low-reflection film formed at λ / 4, and optical thickness λ / 2-λ / 2-λ of low refractive index layer-medium refractive index layer-high refractive index layer-low refractive index layer from substrate side / 2
A four-layer low-reflection film formed at -λ / 4 is known as a typical example.

As described above, according to the method of the present invention, the conductive film containing the Ru metal fine particles absorbs over the entire visible light region, thereby contributing to the improvement of contrast.

[0032]

The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. The percentages and percentages used in the examples and comparative examples are on a weight basis. The evaluation methods of the films obtained in Examples and Comparative Examples are as follows.

1) Evaluation of conductivity The surface resistance of the film surface was measured by a Loresta resistance measuring device (manufactured by Mitsubishi Chemical Corporation). 2) Scratch resistance 1 kg with a scratch resistance measuring device (50-50 manufactured by LION)
After the film surface was reciprocated 50 times under a load, scratches on the surface were visually determined. The evaluation criteria were as follows. ○: No scratches at all △: Some scratches at all ×: Partial film peeling 3) Pencil hardness Under a 1 kg load, the film surface is scanned with pencils of various hardness, and then the surface is visually scratched. The pencil hardness that began to develop was determined to be the pencil hardness of the film.

4) Luminous reflectance The luminous reflectance of the multilayer film at 400 to 700 nm was measured using a GAMMA spectral reflectance spectrum measuring instrument. 5) Luminous transmittance Spectrophotometer U manufactured by Hitachi, Ltd.
The luminous transmittance at 380 to 780 nm was measured according to -3500. The powder volume resistance of the obtained metal fine particles was measured by a four-terminal method, and the average particle size of the obtained sol was measured by a laser diffraction particle size analyzer LPA-3100 manufactured by Otsuka Electronics.

Example 1 A sodium borohydride solution was added to a ruthenium trichloride aqueous solution (solid content: 10%) at a molar ratio of 4 times the amount of ruthenium, to thereby reduce and precipitate metal ruthenium. After sufficiently washing the metal ruthenium, it was dried at 100 ° C. for 24 hours to obtain a metal ruthenium powder. This metal ruthenium powder was ground with a sand mill for 20 minutes. At this time, the average particle size of the metal ruthenium in the liquid was 89 nm. Thereafter, concentration was performed to obtain a dispersion having a solid content of 5%. This is designated as solution A.

Ethyl silicate was dissolved in ethanol, hydrolyzed with an aqueous hydrochloric acid solution, and adjusted to 5% in terms of SiO ₂ with ethanol. This is designated as solution B.
A solution and B solution are mixed so that A solution / B solution = 8/2,
Thereafter, ultrasonic waves were irradiated for 1 hour to obtain a mixed solution. This is C
Liquid. A solution comprising 50: 42: 5: 3 of water: ethanol: methanol: propylene glycol monomethyl ether was prepared. This is designated as solution D. The solution C was diluted with the solution D so that the solid content became 1.0%. This is designated as solution E. Solution E was applied to the surface of a 14-inch CRT panel by spin coating, and heated at 180 ° C. for 30 minutes to form a conductive film.

Example 2 Isopropyl alcohol: propylene glycol monomethyl ether acetate: diacetone alcohol 6:
A solution consisting of 3: 1 was prepared. This is designated as U1 liquid.
The solution A was diluted with the solution D to a solid content of 0.8%, and the solution was applied to the surface of a 14-inch CRT panel by spin coating, and dried at 60 ° C. for 10 minutes to form a conductive film. Was. Thereafter, a solution obtained by diluting the solution B to a concentration of 0.85% with the U1 solution is applied on the film by a spin coating method.
The resultant was baked at 60 ° C. for 30 minutes to form a low-reflection conductive film.

Example 3 Tin chloride and antimony chloride were mixed so that Sn / Sb = 85/15, and the solution was adjusted to pH 10 with aqueous ammonia.
And added to the solution maintained at 50 ° C. to precipitate. This precipitate was washed, separated by filtration, dried at 100 ° C. for 12 hours, and then calcined at 650 ° C. for 3 hours in the atmosphere to obtain antimony-doped tin oxide fine particles. These fine particles were pulverized with a sand mill for 2 hours. At this time, the average particle size of the antimony-doped tin oxide fine particles in the liquid was 65 nm. Thereafter, concentration was performed to obtain a liquid having a solid content of 5%. This solution was diluted with solution D to a solid content of 1.2%, and spin-coated on the surface of a 14-inch CRT panel. Then, add B solution onto this film with U
A solution diluted to 0.9% with one solution was applied by a spin coating method, and baked at 160 ° C. for 20 minutes to form a two-layer film.

In the above, Examples 1 and 2 are examples, and Example 3
Is a comparative example. The conductive films and low-reflective conductive films of Examples 1 to 3 were evaluated. Table 1 shows the results.

[0040]

[Table 1]

[0041]

According to the present invention, an excellent conductive film can be efficiently provided by a simple method such as spraying or spin coating. Since the present invention provides a conductive film made of metal fine particles, it can easily shield electromagnetic waves and can be manufactured relatively inexpensively. In particular, it can be sufficiently applied to a large-area substrate such as a cathode ray tube panel, and can be mass-produced.

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[Procedure amendment]

[Submission date] November 4, 1999 (1999.11.
4)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction contents]

Ruthenium trichloride aqueous solution (solid content 10%)
The sodium ruthenium hydride solution was added at a molar ratio of 4 times the amount of ruthenium to reduce and precipitate metal ruthenium. After sufficiently washing the metal ruthenium, it was dried at 100 ° C. for 24 hours to obtain a metal ruthenium powder. This metal ruthenium powder was ground with a sand mill for 20 minutes. At this time, the average particle size of the metal ruthenium in the liquid was 89 nm. Thereafter, concentration was performed to obtain a dispersion having a solid content of 5%. This is A
Liquid.

Continuing from the front page (72) Inventor Kenji Ishiseki 1150 Hazawa-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Inside the Asahi Glass Co., Ltd.

Claims (2)

[Claims] 1. A method of forming a CRT panel with a conductive film, comprising applying a coating solution containing a sol of Ru metal fine particles to a CRT panel and heating the coating solution. 2. The method according to claim 1, wherein a film having a lower refractive index than the conductive film is formed on the conductive film.