JPH09235143A - Coating solution for forming reflection preventing film, reflection preventing film and cathode ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating solution for forming a uniform reflection preventing film excellent in mechanical strength and weathering resistance, capable of imparting antistatic effects and electromagnetic wave shielding effects to the surface of a Braun tube, by blending an alkyl silicate with a lower alcohol, propylene glycol ether, diacetone alcohol, water and an acid. SOLUTION: This coating solution comprises one or more selected from an alkyl silicate and its hydrolyzate (preferably 0.01-20wt.% calculated as solid content), 50-80wt.% of a 1-3C lower alcohol, 10-30wt.% of one or more selected from propylene glycol ether and propylene glycol ether acetate, 2-20wt.% of diacetone alcohol, water and an acid. The average molecular weight of a hydrolyzate in the alkyl silicate is preferably 400-2,000. The surface of an electroconductive oxide-coated film formed on a transparent substrate is coated with the coating solution for forming a reflection preventing film and dried to form a reflection preventing film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided on the outer surface of an image display area of an image display device such as a cathode ray tube, a liquid crystal display or a plasma display used for receiving television broadcasting or the like, and has an antistatic effect or an electromagnetic wave shielding effect. The present invention relates to a coating liquid for forming an antireflection film, an antireflection film, and a cathode ray tube that can be applied.

[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 is attached to the surface due to static electricity charged, making it difficult to see images.
Since an electric shock may occur due to discharge when a human body touches the outer surface, it is widely practiced to form a conductive film on the surface to prevent this.

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, long-term vision easily causes eye strain. As a preventive measure, it is also necessary to carry out antireflection processing and low reflection processing in the visible light region. In addition, from the viewpoint of safety of the human body, it has been desired to prevent leakage of electromagnetic waves generated from the flyback transformer of the cathode ray tube and the deflection yoke coil.

The leakage of electromagnetic waves can be prevented by forming a transparent conductive film on the surface of the cathode ray tube. Generally, surface resistance is 10 ⁸ to 10 ¹⁰ Ω / □ for antistatic and surface resistance 10 ² to 10 ⁸ is for electromagnetic wave shielding. Ω / □, especially 10 ² to 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.

Specifically, as described in JP-A-1-299887, 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, etc.), a dry method ( A method of forming a plurality of thin films by a CVD method, a sputtering method, a vacuum vapor deposition method, etc., 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.

[0008]

As the low reflection antistatic film, a low refractive index material film is formed on the air side and a transparent base material side is formed of a conductive material having a high refractive index. An optical interference film having the above-mentioned multilayer film structure is generally used. 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, but since the cost of maintaining a high degree of cleanliness is high, there has been a demand for a coating solution that is less likely to cause defects even when foreign matter is present.

Generally, after the coating liquid is applied to a cathode ray tube, the coating film is baked, and the baking temperature allowable for the cathode ray tube is about 200 ° C. Since a baking temperature of about 200 ° C. is not necessarily high in order to obtain sufficient film strength, it is necessary to give a film strength sufficient for practical use even at this temperature. In the case of the two-layer film by the wet method, there was a problem that the scratch resistance test was likely to cause peeling from the interface between the upper layer film and the lower layer film. Further, since the upper layer film is exposed to the atmosphere, stability such as weather resistance is required in addition to scratch resistance.

In order to solve the above-mentioned drawbacks of the prior art, an object of the present invention is to provide an antireflection film having uniform and high strength and excellent weather resistance on the surface of a cathode ray tube and the like, which can impart an antistatic effect and an electromagnetic wave shielding effect. It is to provide a coating solution for forming.

[0012]

The present invention comprises one or more selected from alkyl silicates and hydrolysates thereof, and 50 to 80% by weight of a lower alcohol having 1 to 3 carbon atoms,
10 to 3 of at least one selected from propylene glycol ether and propylene glycol ether acetate
Provided is a coating liquid for forming an antireflection film, which contains 0% by weight or less, 2 to 20% by weight of diacetone alcohol, water, and an acid.

Further, the present invention is characterized in that the coating liquid for forming an antireflection film is applied to the surface of a conductive oxide film formed on a transparent substrate and dried to form a reflection film. Providing a barrier film.

Further, the present invention provides a cathode ray tube characterized in that the antireflection film is formed on a face surface of a panel for a cathode ray tube on which an image is displayed.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have prepared a low reflection antistatic film or a low reflection electromagnetic wave shielding film by using a coating liquid for forming an antireflection film (hereinafter referred to as a coating liquid) having the above composition. In addition, there is no unevenness in film thickness, defects are not noticeable even if foreign substances are present on the panel surface at the time of application, and the strength is high in the scratch resistance test, and stable and reliable in the weather resistance test. I found it.

In the present invention, the average molecular weight of the hydrolyzate of the alkyl silicate in the coating liquid is preferably 400 to 2000 in terms of pothistyrene. 400
If it is less than 2, the film surface will be partially dissolved when immersed in boiling water, and the stability of the film will be poor. If it exceeds 2000, when it is used as the upper layer of the two-layer film, it can sufficiently penetrate into the fine irregularities of the lower layer film. Without the strength. The amount of one or more selected from alkyl silicates and hydrolysates thereof is preferably 0.01 to 20% by weight in terms of solid matter.

In the present invention, propylene glycol ether means propylene glycol monomethyl ether (hereinafter abbreviated as PGMME), propylene glycol monoethyl ether (hereinafter abbreviated as PGMEE) or propylene glycol monopropyl ether (hereinafter PGM).
It is preferable that PE is abbreviated) because a uniform film can be obtained. Further, the propylene glycol ether acetate is preferably propylene glycol monomethyl ether acetate (hereinafter abbreviated as PGMMEA) from the viewpoint of obtaining a uniform film.

The coating solution preferably contains 0.01 to 5% by weight of nitric acid. If the amount is less than 0.01% by weight, it is inconvenient because the silicate is not sufficiently hydrolyzed.
If it exceeds the above range, it is disadvantageous in that the polymerization proceeds with time.

Water is preferably contained in an amount of 4 to 24 mol per mol of the alkyl silicate, and if it is less than 4 mol, the wettability to the base material is inferior, and if it exceeds 24 mol, the wettability to the base material is inferior. It is inconvenient.

The alkyl silicate of the present invention is not particularly limited as long as it can be converted into silica sol by a hydrolysis reaction, and examples thereof include alkyl silicate monomers typified by methyl silicate and ethyl silicate, and methyl silicate 51 (hereinafter referred to as MS51). Polymers such as ethyl silicate 40 (hereinafter abbreviated as ES40) and ethyl silicate 45 (hereinafter abbreviated as ES45) can be preferably used. Here, MS51 is silicate 1
This means that 51 g of SiO ₂ (solid content) is contained in 00 g, and the same applies to ES40 and ES45.

Since the coating liquid of the present invention has the above components and compositions, it has good wettability with respect to the substrate, can form a uniform film even in the presence of foreign matter, and has excellent scratch resistance and weather resistance. A film can be formed. In particular, when a dispersion liquid of antimony-doped tin oxide powder or a dispersion liquid of indium tin oxide is applied and then applied on a conductive oxide film having a high refractive index, which is formed by drying, a low reflection electrification which imparts the above effect is obtained. An anti-reflection film or a low reflection electromagnetic wave shielding film can be formed.

Further, a conductive oxide conductive film having a high refractive index,
In the case of a colored film containing carbon black and / or titanium black as the black pigment, a high-contrast low-reflection antireflection film or low-reflection electromagnetic wave shielding film having the above-mentioned effect can be formed.

The coating liquid of the present invention can optimally control the surface tension, viscosity and drying rate of the coating liquid and can form a uniform film. The case of forming a film on the surface of a cathode ray tube panel by a spin coating method, which is a typical film forming method among wet methods, will be described in detail. Generally, after the outer surface of the panel face is washed and dried, While maintaining the temperature at 30 to 50 ° C., the coating liquid is dropped from a nozzle arranged facing the face surface while rotating the cathode ray tube at a low speed of 100 to 150 rpm.

The centrifugal force generated by the rotation causes the coating liquid applied to the face surface to flow in the peripheral direction along the outer surface of the face surface, and the excess coating liquid is scattered from the peripheral portion to uniformly coat the outer surface of the face. A film is formed. When coating as a low refractive index film for antireflection film on a conductive oxide film formed on the surface of a cathode ray tube, unlike when coating on a glass surface, there are fine irregularities due to fine particles, so coating It is necessary to optimally control the surface tension, the viscosity, and the drying speed in order for the liquid to be uniformly spread and spread.

Therefore, a lower alcohol having a low boiling point and a high vapor pressure and having 1 to 3 carbon atoms, a propylene glycol ether or a propylene glycol ether acetate having a higher boiling point and a lower vapor pressure, and a higher boiling point and a lower vapor pressure than these By blending diacetone alcohol (hereinafter abbreviated as DAA) as in the present invention, a uniform film with a small film thickness deviation can be obtained over the entire face.

Further, when foreign matter is present on the face surface during coating, a defect such as a trailing edge is usually generated. However, the coating solution having the above composition has a spreading and solidifying or gelling speed. Since it is optimally controlled, even if a foreign substance is present, the coating liquid wraps around the foreign substance before it solidifies, and the deviation in film thickness around the foreign substance can be suppressed. Therefore, the length of the tailing is small and extremely inconspicuous, and the yield of the appearance in mass production can be dramatically improved.

The low-reflection antistatic film or the low-reflection electromagnetic wave shielding film has a conductive oxide film having a high refractive index containing conductive oxide fine particles formed on the lower layer, and a low refractive index comprising the coating liquid of the present invention on the upper layer. It is constructed by forming layers. Microscopic observation of scratches observed in the scratch resistance test of the low-reflection antistatic film or the low-reflection electromagnetic wave shielding film reveals that the scratches are often peeled from the interface between the upper layer film and the lower layer film.

In the present invention, by setting the water content and the acid concentration as described above, a coating solution in which the hydrolysis rate of alkyl silicate is high and the average molecular weight is controlled to 400 to 2000 is obtained, and the upper layer film is the lower layer. A film having a high adhesiveness is obtained by biting into fine irregularities of the film.

Examples of the acid include sulfuric acid, acetic acid and the like in addition to nitric acid and hydrochloric acid. Sulfuric acid is difficult to volatilize, and acetic acid is a weak acid and the reaction proceeds slowly, so nitric acid or hydrochloric acid is preferable.

The coating liquid of the present invention is applied on a dispersion liquid of antimony-doped tin oxide powder or a dispersion liquid of indium tin oxide and dried to form a conductive oxide film (underlayer film) having a high refractive index. By coating and baking at 100 to 200 ° C., a highly uniform and high-strength low reflection antistatic film or low reflection electromagnetic wave shielding film can be formed.

By including carbon black and / or titanium black as a black pigment in the lower layer film, external light is absorbed, the reflection characteristics are further improved, and the contrast to ambient light is also improved.

The cathode ray tube provided with the antireflection film of the present invention is
It has excellent effects such as low reflection antistatic effect, low reflection electromagnetic wave shielding effect, and high contrast.

[0033]

EXAMPLES Examples (Examples 1 to 8) and Comparative Examples (Example 9, below)
10) will be specifically described, but the present invention is not limited to the following examples.

(1) Film forming method The outer surface of the cathode ray tube face is washed and dried,
Keep the temperature at 50 ℃, CRT 100 ~ 150 rp
While rotating at a low speed of m, the coating liquid for forming a conductive oxide film was dropped from a nozzle arranged facing the face surface. After drying the coating film, place the CRT again at 100-150.
The coating liquid for forming an antireflection film of the present invention was dropped while rotating at a low speed of rpm. Next, set the CRT face face to 1
By holding at 60 ° C. for 30 minutes, a low-reflection antistatic film or a low-reflection electromagnetic wave shielding film was formed on the surface.

(2) Evaluation (Average molecular weight) The average molecular weight of the coating solution was measured by gel permeation chromatography using the following apparatus. Device: Gel Permeation Chromatograph HLC-8020 (manufactured by Tosoh Corporation), Column: TSK-Gel 2500H and 3
000H, solvent: tetrahydrofuran.

(Thickness unevenness in panel plane) The reflection characteristic in the panel plane was measured by a spectral reflectance measurement system manufactured by Easy & Gamma Science Co., and the maximum and minimum values of the bottom wavelength in the panel plane were measured. Was measured. Since the bottom wavelength shifts to the long wavelength side as the film thickness increases, and the bottom wavelength shifts to the short wavelength side as the film thickness decreases, the smaller the difference between the maximum value and the minimum value, the more uniform the film.

(Easyness of appearance defect) Cleanliness 1
The appearance of the film made under the 000 booth was inspected.
The number of defects with a trailing length of mm or more was counted.

(Scratch resistance) After a reciprocation of the film surface 50 times with an eraser under a load of 1 kg, how the surface was scratched was visually determined. The criteria for judgment were as follows: ○: no scratches, Δ: some scratches, ×: many scratches.

(Boiling-resistant water resistance) A 5 cm square glass piece on which a film was formed was immersed in boiling water for 30 minutes, and the change in bottom wavelength before and after immersion was measured.

(3) Preparation of coating liquid A coating liquid for forming a conductive oxide film was prepared as follows. After the raw materials in the A column of Table 1 were dispersed in the ion-exchanged water in the B column, the raw materials in the C column were mixed by stirring to obtain a uniform dispersion having the name in the D column. The numbers in Table 1 indicate the amounts of raw materials (unit:% by weight).

Example 1 The kinds and amounts (unit: wt%) of raw materials shown in Table 2 were mixed, stirred and hydrolyzed and polymerized to obtain a uniform coating liquid for forming an antireflection film (coating liquid). B-1).
The coating liquid A-1 (lower layer) and the coating liquid B-1 (upper layer) were combined to form a low reflection electromagnetic wave shielding film on the surface of the Braun tube. The characteristics of the obtained film are shown in Table 4.

[Example 2] Raw materials of the types and amounts (unit:% by weight) shown in Table 2 were mixed, stirred and hydrolyzed and polymerized to obtain a uniform coating liquid for forming an antireflection film (coating liquid). B-2).
The coating liquid A-2 and the coating liquid B-2 were combined to form a low reflection antistatic film on the surface of the cathode ray tube. The characteristics of the obtained film are shown in Table 4.

[Example 3] Raw materials of the types and amounts (unit:% by weight) shown in Table 2 were mixed, stirred and hydrolyzed and polymerized to obtain a uniform coating liquid for forming an antireflection film (coating liquid). B-3).
The coating liquid A-3 and the coating liquid B-3 were combined to form a low reflection antistatic film on the surface of the cathode ray tube. The characteristics of the obtained film are shown in Table 4.

[Example 4] Raw materials of the types and amounts (unit:% by weight) shown in Table 2 were mixed, stirred and hydrolyzed and polymerized to obtain a uniform coating liquid for forming an antireflection film (coating liquid. B-4).
The coating liquid A-4 and the coating liquid B-4 were combined to form a low reflection antistatic film on the surface of the cathode ray tube. The characteristics of the obtained film are shown in Table 4.

Example 5 Raw materials of the types and amounts (unit: wt%) shown in Table 2 were mixed, stirred and hydrolyzed and polymerized to obtain a uniform coating liquid for forming an antireflection film (coating liquid). B-5).
The coating liquid A-5 and the coating liquid B-5 were combined to form a low reflection electromagnetic wave shielding film on the surface of the cathode ray tube. The characteristics of the obtained film are shown in Table 4.

[Example 6] Raw materials of the types and amounts (unit: wt%) shown in Table 3 were mixed, stirred and hydrolyzed and polymerized to obtain a uniform coating liquid for forming an antireflection film (coating liquid). B-6).
The coating liquid A-5 and the coating liquid B-6 were combined to form a low reflection electromagnetic wave shielding film on the surface of the cathode ray tube. The characteristics of the obtained film are shown in Table 4.

[Example 7] Raw materials of the types and amounts (unit:% by weight) shown in Table 3 were mixed, stirred and hydrolyzed and polymerized to obtain a uniform coating liquid for forming an antireflection film (coating liquid). B-7).
The coating liquid A-5 and the coating liquid B-7 were combined to form a low reflection antistatic film on the surface of the cathode ray tube. The characteristics of the obtained film are shown in Table 4.

[Example 8] Raw materials of the types and amounts (unit:% by weight) shown in Table 3 were mixed, stirred and hydrolyzed and polymerized to obtain a uniform coating liquid for forming an antireflection film (coating liquid B). -8). The coating liquid A-1 and the coating liquid B-8 were combined to form a low reflection electromagnetic wave shielding film on the surface of the cathode ray tube. The characteristics of the obtained film are shown in Table 4.

[Example 9] Raw materials of the types and amounts (unit: wt%) shown in Table 3 were mixed, stirred and hydrolyzed and polymerized to obtain a uniform coating liquid for forming an antireflection film (coating liquid). C-1).
The coating liquid A-1 and the coating liquid C-1 were combined to form a low reflection antistatic film on the surface of the cathode ray tube. The characteristics of the obtained film are shown in Table 4.

[Example 10] Raw materials of the types and amounts (unit: wt%) shown in Table 3 were mixed, stirred and hydrolyzed and polymerized,
A uniform coating liquid for forming an antireflection film was obtained (coating liquid C-
2). The coating liquid A-1 and the coating liquid C-2 were combined to form a low reflection antistatic film on the surface of the cathode ray tube. The characteristics of the obtained film are shown in Table 4.

[0051]

[Table 1]

[0052]

[Table 2]

[0053]

[Table 3]

[0054]

[Table 4]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C09K 3/00 C09K 3/00 R G02B 1/11 G02F 1/1335 G02F 1/1335 H01J 9/20 A H01J 9/20 29/88 29/88 G02B 1/10 A

Claims (8)

[Claims] 1. One or more selected from alkyl silicates and hydrolysates thereof, 50 to 80% by weight of a lower alcohol having 1 to 3 carbon atoms, and one selected from propylene glycol ether and propylene glycol ether acetate. A coating liquid for forming an antireflection film, characterized in that it contains 10 to 30% by weight or less of the above, 2 to 20% by weight of diacetone alcohol, water, and an acid. 2. The coating liquid for forming an antireflection film according to claim 1, wherein the hydrolyzate of the alkyl silicate has an average molecular weight of 400 to 2000 in terms of polystyrene. 3. The coating liquid for forming an antireflection film according to claim 1, wherein the propylene glycol ether is propylene glycol monomethyl ether, propylene glycol monoethyl ether or propylene glycol monopropyl ether. 4. The coating liquid for forming an antireflection film according to claim 1, 2 or 3, wherein the propylene glycol ether acetate is propylene glycol monomethyl ether acetate. 5. An antireflection film-forming coating solution according to claim 1, 2, 3 or 4 is applied to the surface of a conductive oxide film formed on a transparent substrate and dried to form the coating. An antireflection film characterized by being. 6. The conductive oxide film is formed by applying a dispersion liquid of antimony-doped tin oxide powder or a dispersion liquid of indium tin oxide and drying the applied coating liquid.
The antireflection film according to the above. 7. The antireflection film according to claim 5, wherein the conductive oxide film contains at least one selected from carbon black and titanium black as a black pigment. 8. A cathode ray tube characterized in that the antireflection film according to claim 5, 6 or 7 is formed on a face surface of a panel for a cathode ray tube on which an image is displayed.