JPH1145657A - Cathode ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fog-free fluorescent screen without using a large quantity of water by forming a resin film composed of a styrene (co) polymer on which weight average molecular weight and the molecular weight distribution expressed by the ratio of weight averate molecular weight (Mw) to number average molecular weight (Mn) are not less than a specific value, on a glass panel inside surface. SOLUTION: Weight average molecular weight is not less than 50 thousand, and the molecular weight distribution Mw/Mn is not less than 5. A volume specific resistance value of resin is desirable to be (1.0×10<16> to 9×10<17> Ω.cm). Styrene, m-styrene and p-phenyl styrene are used as a styrene monomer, and ethyl acrylate, propyl acrylate, n-butyl acrylate, methyl methacrylate, propyl methacrylate and n-butyl methacrylate are used as the other vinyl monomer. A constitutive component of a styrene (co) polymer is desirable to be not more than 40 to 90 wt.% of a styrene monomer and 60 wt.% of a (meta) acrylic ester monomer. Powder painting of a phosphor becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cathode ray tube.

[0002]

2. Description of the Related Art Conventionally, in a shadow mask type color cathode ray tube, a fluorescent film of three primary colors of blue, green and red is formed by dispersing a phosphor in an aqueous solution comprising polyvinyl alcohol and ammonium dichromate on a glass panel. After coating with a flow coat and drying, the obtained coating film is exposed by using a shadow mask having a predetermined pattern as a photomask, and an unexposed portion is removed by a hot water shower and developed. 55-2825
No. 6). Such a flow coating method is the most widely used method of forming a fluorescent film at present, since the control of the amount of the attached phosphor is easy and the thickness of the fluorescent screen can be controlled uniformly.

However, in the above-mentioned flow coating method, a large amount of water is used because the suspension in which the phosphor is dispersed is applied to a glass panel for each of the three primary colors by drying, exposure, and hot water shower washing. In addition to the above, there is a problem that it takes a long time to form the fluorescent film.

Further, as another method of forming a fluorescent film, the following coating method by spin coating is also performed. In this method, first, a toluene solution of a styrene-based polymer is spin-coated on the inner surface of a glass panel and dried to form a resin film surface. Next, the resin film surface is charged, and the charged resin film surface is exposed using a shadow mask having a predetermined pattern as a photomask. Then, the shadow mask is removed, and the phosphor is electrostatically exposed to the three primary colors (red, green, and blue). This is a method in which a phosphor film is formed by powder coating in the order of the colors of (1) and firing.

[0005] However, the spin coating method has a problem in that the chargeability of the resin film surface is insufficient, so that the phosphor is scattered and a fog-free fluorescent film cannot be formed.

[0006]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to form a fluorescent film on the inner surface of a glass panel in a short time without using a large amount of water in a manufacturing process, and Another object of the present invention is to provide a cathode ray tube having a clean fluorescent film without fogging.

[0007]

A cathode ray tube according to the present invention is a cathode ray tube having a fluorescent film formed by electrostatically coating a fluorescent substance on a resin film provided on the inner surface of a glass panel. The resin film has a weight average molecular weight (Mw) of 50,000 or more and a molecular weight distribution represented by a ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of 5 or more; It is characterized by being formed from a certain styrenic (co) polymer.

Hereinafter, the present invention will be described in detail. Examples of the styrene (co) polymer used in the present invention include a homopolymer or copolymer of a styrene monomer and a copolymer of a styrene monomer and another vinyl monomer. No.

As the styrene monomer, for example,
Styrene, o-methylstyrene, m-methylstyrene,
p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, pn-
Dodecyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, 3,4-dichloro styrene and the like may be mentioned, and these may be used alone or in combination of two or more.

As the other vinyl monomer, a monomer other than the styrene monomer, for example, an acrylate ester or a methacrylate ester is preferably used. Examples of the acrylate include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate These may be used alone or in combination of two or more.

Examples of the methacrylate include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, stearyl methacrylate and the like. These may be used alone or in combination of two or more.

Other vinyl monomers other than the above include, for example, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, methacrylic acid 2-hydroxyethyl acid, glycidyl methacrylate, bisglycidyl methacrylate, polyethylene glycol dimethacrylate, methacryloxyethyl phosphate and the like may be used.

Among the other vinyl monomers described above, ethyl acrylate, propyl acrylate, n-butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, and n-butyl methacrylate are preferred.

The content of the styrene monomer in the constituent components of the styrene (co) polymer is preferably from 40 to 90% by weight, more preferably from 50 to 80% by weight. Further, the content of the (meth) acrylate monomer in the constituent components of the styrene (co) polymer is preferably 60% by weight or less, more preferably 10 to 40% by weight.

If the weight average molecular weight (Mw) of the styrene (co) polymer is too small, it becomes difficult to form a uniform resin film, and a sufficient charge amount cannot be obtained on the resin film. It is preferably 100,000 or more, more preferably 200,000 or more.

The ratio (Mw / M) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the styrenic (co) polymer
The molecular weight distribution represented by n) is limited to 5 or more, preferably 5 to 50, and more preferably 10 to 30. The weight average molecular weight (Mw) and the number average molecular weight (Mn) are values measured by gel permeation chromatography (GPC).

When the molecular weight distribution (Mw / Mn) is less than 5, it is difficult to adjust the viscosity when a styrene (co) polymer is used as a solution, and it is difficult to obtain a resin film having a uniform thickness. Is not uniform, and it is difficult to form a fluorescent film having a uniform film thickness.

If the volume specific resistance of the resin is small, sufficient charge holding ability (initial potential, holding potential) cannot be obtained, so that powder coating of the phosphor becomes difficult, and a phosphor film having a uniform film thickness is required. It cannot be formed.

The styrenic (co) polymer can be synthesized by a conventionally known polymerization method such as suspension polymerization, emulsion polymerization, solution polymerization, or bulk polymerization.

A method for forming a resin film using the styrene (co) polymer will be described with reference to the drawings.
First, as shown in FIG. 1, a polyvinyl alcohol-based photoresist is spin-coated on the inner surface of the glass panel. Next, after exposing through a shadow mask having a predetermined pattern, it is washed with water to remove uncured portions and dried (FIGS. 2 and 3). Further, after spin-coating graphite, etching is performed with sulfuric acid to form a black matrix on the inner surface of the glass panel (FIGS. 4 and 5).

Next, a 5% by weight toluene solution of the styrene (co) polymer is spin-coated on the black matrix and then dried to form a resin film (FIGS. 6 and 7). After the resin film is charged, exposure is performed using a shadow mask having a predetermined pattern as a photomask (FIG. 7). Red toner (R) is electrostatically powder-coated on the portion where the charge has been lost by the exposure (FIGS. 8 and 9). By repeating the same operation, the green toner (G) and the blue toner (B) are successively electrostatically powder-coated. Finally, the phosphor coating is formed by heating and baking the powder-coated surface of the three color toner (FIG. 10).

[0022]

The cathode ray tube of the present invention has a weight average molecular weight (Mw) of 50,000 or more and a molecular weight distribution (Mw /
By forming a resin film made of a styrene-based polymer having Mn of 5 or more, powder coating of the phosphor becomes possible, so that a suspension in which the phosphor is dispersed is unnecessary, and Since there is no coating, drying, exposure, or development operation using a hot water shower, the manufacturing process can be greatly reduced, and there is no need to use a large amount of water. Further, by using a resin having a volume specific resistance of 1.0 × 10 ^{16 to} 9.9 × 10 ¹⁷ Ω · cm, the resin film has a sufficient charge retention ability (initial potential, (Holding potential), the scattering of the phosphor during the formation of the phosphor film is reduced, and a clean phosphor film without fogging can be formed.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to Examples and Comparative Examples.

Example 1 1000 g of toluene was placed in a 5 L separable flask, and a styrene copolymer (constituent: 75% by weight of styrene and 25% by weight of n-butyl acrylate, weight average molecular weight: 1.2 million) 450 g was charged and mixed and dispersed. Next, after replacing the gas phase of the separable flask with nitrogen gas, the temperature of this system was raised to the boiling point of toluene. While stirring with refluxing toluene, 600 g of styrene, 300 g of n-butyl methacrylate and 100 g of methyl methacrylate were added dropwise over 3 hours to a mixed solution obtained by adding 40 g of benzoyl peroxide as a polymerization initiator. Solution polymerization was performed. After completion of the dropwise addition, the mixture was aged for 1 hour while stirring at the temperature of boiling toluene. Next, while gradually raising the temperature of the system to 180 ° C., toluene was removed under reduced pressure to obtain a copolymer. This copolymer was cooled and pulverized to obtain a styrene copolymer (A). This styrenic copolymer (A)
Has a weight average molecular weight (Mw) of 280,000 and Mw / Mn = 30.
Met.

20 g of the pulverized resin of the styrene copolymer (A) was weighed in an aluminum petri dish, heated and melted on a hot plate, and then cooled and solidified to produce a smooth resin plate. The volume specific resistance of this resin plate was measured with a DSM-8103 digital insulation meter (manufactured by Toa Denpa Kogyo Co., Ltd.) and found to be 2.5 × 10 ¹⁶ Ω · cm. Next, regarding the surface potential of the resin plate, DS
The initial potential was 395 V and the holding potential after 3 minutes was 320 V when measured with an M-8103 digital insulation meter (manufactured by Toa Denpa Kogyo KK).

5% by weight of the styrene copolymer (A)
The toluene solution was spin-coated on the inner surface of the glass panel provided with the black matrix in the steps shown in FIGS. 1 to 5 and then dried to form a resin film. Then, after charging the resin film and exposing the shadow mask as a photomask,
By removing the shadow mask, the phosphor is electrostatically charged with the three primary colors (R,
G and B) were sequentially applied with powder and baked to form a fluorescent film (FIGS. 6 to 10). Through the above series of operations, a resin film having a uniform film thickness was formed, and a sufficient charge amount was obtained. Therefore, a clean phosphor film without scattering of the phosphor and without fogging was able to be formed.

Example 2 1000 g of toluene was placed in a 5 L separable flask, and a styrene copolymer (constituent: 75% by weight of styrene and 25% by weight of n-butyl acrylate, weight average molecular weight: 1.2 million) 300 g was charged and mixed and dispersed. Next, after replacing the gas phase of the separable flask with nitrogen gas, the temperature of this system was raised to the boiling point of toluene. While stirring while refluxing toluene, 600 g of styrene and 300 g of ethyl acrylate were added.
g and methyl methacrylate (100 g), a solution obtained by adding 40 g of benzoyl peroxide as a polymerization initiator was added dropwise over 3 hours to carry out solution polymerization. After dropping,
Further, the mixture was aged for 1 hour with stirring at a temperature at which toluene was boiling. Next, while gradually raising the temperature of the system to 180 ° C., toluene was removed under reduced pressure to obtain a copolymer. This copolymer was cooled and pulverized to obtain a styrene copolymer (B). The styrene copolymer (B) had a weight average molecular weight (Mw) of 200,000 and Mw / Mn = 22.

[0028] where in the same manner as in Example 1 to prepare a resin plate was measured volume resistivity, 2.1 × 10 ¹⁶
Ω · cm, and the initial potential is 38
The holding potential after 0 V and 3 minutes was 310 V.

5% by weight of the styrene copolymer (B)
A resin film was formed on the inner surface of the glass panel in the same manner as in Example 1 except that a toluene solution was used.
A phosphor film was formed by powder coating in the same manner as described above. By the above series of operations, sufficient charge was obtained on the resin film,
It was possible to form a clean fluorescent film without scattering of the phosphor and without fogging.

(Comparative Example 1) 1000 g of toluene was placed in a 3 L separable flask and stirred. After the gas phase was replaced with nitrogen gas, the temperature of the system was raised to the boiling point of toluene.
The solution polymerization was carried out while dropping a mixed solution obtained by adding 40 g of benzoyl peroxide as a polymerization initiator to 600 g of styrene and 400 g of n-butyl methacrylate dropwise with stirring over a period of 3 hours while stirring with refluxing toluene. . After completion of the dropwise addition, the mixture was aged for 1 hour while stirring at the temperature of boiling toluene. Next, while gradually raising the temperature of the system to 180 ° C., toluene was removed under reduced pressure to obtain a copolymer. This copolymer was cooled and pulverized to obtain a styrene copolymer (C). The weight average molecular weight (Mw) of the styrene copolymer (C) is 20,000, and Mw / Mn =
It was 3.

[0031] where in the same manner as in Example 1 to prepare a resin plate was measured volume resistivity, 2.0 × 10 ¹⁵
Ω · cm, and the surface potential is 15
The holding potential after 0 V and 3 minutes was 90 V.

5% by weight of the styrene copolymer (C)
Except that a toluene solution was used, a resin film was formed on the inner surface of the glass panel in the same manner as in Example 1, and then a fluorescent film was formed by powder coating in the same manner as in Example 1. The viscosity of the copolymer (C) solution is low,
Since the film thickness was too thin, a sufficient charge amount was not obtained on the resin film, and the scattering of the phosphor occurred, and fogging was recognized on the phosphor film.

(Comparative Example 2) 1 g of partially saponified polyvinyl alcohol ("Gohsenol GH-17" manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was placed in a 3 L separable flask and dissolved in 1000 ml of distilled water. After replacing the gas phase with nitrogen gas, the temperature was raised to 80 ° C. After heating, 600 g of styrene and 200 g of n-butyl methacrylate
g, and a mixed solution to which 5 g of benzoyl peroxide as a polymerization initiator was added was dropped at a constant speed over 5 hours, and after completion of the dropping, the mixture was kept at 80 ° C. for 8 hours. Next, the temperature was raised to 100 ° C., polymerization was carried out at that temperature for 2 hours, followed by cooling, repeated dehydration and water washing, and then drying to obtain a styrene-based copolymer (D). The weight average molecular weight (Mw) of this styrene-based copolymer (D) was 350,000, and Mw / Mn = 3.

[0034] where in the same manner as in Example 1 to prepare a resin plate was measured volume resistivity, 3.3 × 10 ¹⁵
Ω · cm, and the initial potential is 18
The holding potential after 0 V and 3 minutes was 110 V.

5% by weight of the styrene copolymer (D)
A resin film was formed on the inner surface of the glass panel in the same manner as in Example 1 except that a toluene solution was used.
An attempt was made to form a fluorescent film by powder coating in the same manner as described above. However, since the viscosity of the styrene-based copolymer (D) solution was high and the resin film thickness was non-uniform, charging unevenness occurred and a clean fluorescent film was obtained. Could not be formed.

[0036]

The cathode ray tube of the present invention is constructed as described above and has a uniform resin film thickness.
When charging the resin film, there is no charge unevenness and a sufficient charge amount can be obtained. Therefore, the phosphor has a clean phosphor film without scattering and no fogging. In addition, since there is no development and drying process using a hot water shower, the manufacturing process can be simplified and the productivity can be improved. Furthermore, since a hot water shower is not required in the manufacturing process, the amount of water used can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a step of spin-coating a photoresist.

FIG. 2 is a schematic view showing a process of exposing a photoresist to a photoresist using a shadow mask as a photomask.

FIG. 3 is a schematic view showing a step of washing and drying an unexposed portion of a photoresist.

FIG. 4 is a schematic view showing a step of spin-coating graphite on a photoresist.

FIG. 5 is a schematic view showing a step of forming a black matrix by etching with sulfuric acid.

FIG. 6 is a schematic view showing a step of spin-coating a styrene (co) polymer on a black matrix to form a resin film.

FIG. 7 is a schematic view showing a step of charging a resin film.

FIG. 8 is a schematic view showing a step of exposing a resin film using a shadow mask as a photomask.

FIG. 9 is a schematic view showing a step of powder coating a phosphor on a charged resin film.

FIG. 10 is a schematic view showing a step of baking a phosphor coated with powder.

FIG. 11 is a schematic view showing a step of spin-coating a phosphor in a conventional method.

FIG. 12 is a schematic view showing a step of exposing a phosphor to a photomask using a shadow mask in a conventional method.

FIG. 13 is a schematic view showing a step of washing and drying an unexposed portion of the phosphor in a conventional method.

Claims (2)

[Claims] 1. A cathode ray tube having a fluorescent film formed by electrostatically coating a phosphor on a resin film provided on an inner surface of a glass panel, wherein the resin film has a weight average molecular weight (Mw). ) Is 50,000 or more and the weight average molecular weight (M
A cathode ray tube comprising a styrene (co) polymer having a molecular weight distribution represented by a ratio (Mw / Mn) of w) to a number average molecular weight (Mn) of 5 or more. 2. A cathode ray tube having a fluorescent film formed by electrostatically coating a phosphor on a resin film provided on an inner surface of a glass panel, wherein the resin film has a weight average molecular weight (Mw). ) Is 50,000 or more and the weight average molecular weight (M
The molecular weight distribution represented by the ratio (Mw / Mn) of w) to the number average molecular weight (Mn) is 5 or more, and the resin has a volume resistivity of 1.0 × 10 ^{16 to} 9.9 × 10 ¹⁷ Ω ・ c
m. A cathode ray tube characterized by being formed from a styrene (co) polymer.