JPS58198818A - Manufacturing method for metal back cathode ray tube - Google Patents

Abstract

PURPOSE:To obtain a smooth metal back layer by soaking a fluorescent screen formed on a face in an aqueous solution with a specific composition, forming a thin film of an organic high polymer material, on said fluorescent screen, and burning said thin film after forming a metal back layer on said thin film. CONSTITUTION:A fluorescent screen 7 is formed by depositing a prescribed phosphor on the inside of face part glass 6. Then, by wetting the fluorescent screen 7 by injecting an aqueous 0.1% solution having the degree of saponification of 80.0+ or -1.5% into the face part, and thereafter removing an excess aqueous solution, an aqueous solution layer 8 is formed. Then, by spraying a prescribed amount of a lacquer solution obtained by dissolving polyisobutyl acrylate, methacrylate ester, and acrylate ester, etc., into a solvent such as toluene, drying the solvent and the water content to form an organic material film 9, and successively vacuum evaporating aluminum on the film 9, a metal back layer 10 is formed. Thereafter, this organic material film 9 is removed through burning process.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a cathode ray tube having a metal back layer using a metal such as aluminum on the fluorescent surface.

In order to obtain a metal back layer that is free of stripes, spots, and unevenness when observed through the glass face of a cathode ray tube, conventionally, appropriate pretreatment has been performed to eliminate irregularities on the phosphor surface. For example, in the manufacturing process of a black and white cathode ray tube, as shown in FIG. The fluorescent surface 2 is wetted with water, the unevenness of the fluorescent surface 2 is filled with water 3 to make the fluorescent surface 2 appear smooth, and a solution of an organic polymeric substance dissolved in a solvent is sprayed onto the surface. After being applied, it was dried and water and solvent were evaporated to form a thin film 4 of an organic polymer substance on the fluorescent surface 2, and a metal back layer 5 such as aluminum was deposited thereon by vapor deposition. .

Note that the organic polymer thin film 4 is removed by thermal decomposition in a subsequent step.

However, in this conventional method, the water 3 wetting the phosphor surface 2 is repelled because the phosphor particles are water-repellent, and the time during which the phosphor surface 2 is apparently smooth is shortened.
Unwet phosphor particles appear. Therefore, the organic solvent in which the organic polymer substance is dissolved is directly sprayed onto the phosphor particles, causing the thin film 4 of the organic polymer substance to lose its smoothness, and when observed from the front of the face glass, uneven spots can be seen. It was done. As described above, the conventional method has the disadvantage that there is little margin for obtaining a smooth metal back layer.

An object of the present invention is to provide a method for manufacturing a cathode ray tube that eliminates the above-mentioned conventional drawbacks and provides a smooth metal back layer.

It is sufficient that the liquid that makes the phosphor particles have a low surface tension.

Figure 2 shows the surface tension of an aqueous solution of polyvinyl alcohol. In the figure, (a) is PVA117 (manufactured by Kuraray Co., Ltd.) saponification degree 98.5 ± 0.5%, ←) is pvA217 (
(manufactured by Kuraray Co., Ltd.) saponification degree 88. θ±1.0%, () is PV
A420 (manufactured by Kuraray) Saponification degree 81.5 ± 2.0%,
) are each characteristic of pure water. Note that the temperature condition was 20°C. From Figure 2, the lower the degree of saponification, the lower the surface tension.
It can be seen that a polyvinyl alcohol aqueous solution with a low degree of saponification is effective for wetting the phosphor particles.

A phosphor surface 7 is formed by depositing the phosphor by a sedimentation method. Next, PV manufactured by Kuraray with a saponification degree of 80.0±1.5%
A 0.1% aqueous solution of A-420 was injected to wet the fluorescent surface 7, and then the excess aqueous solution was removed and left to stand for an appropriate time to form an aqueous solution layer 8. Next, using toluene as a solvent, a lacquer solution was prepared by dissolving 6% by weight of polyisobutyl acrylate as a solvent and 0.06% by weight of a methacrylic acid ester and an acrylic ester (Acryloid B-72 manufactured by Rohm and Haas Co., Ltd. in the United States). A predetermined amount of was sprayed. Then, the solvent and moisture were dried to form an organic substance film 9, and then aluminum was vapor deposited on this film 9 to form a metal back layer 10. Thereafter, the organic substance film 9 was removed by firing treatment.

As shown in the table, the metal back layer formed in this manner was free from uneven spots compared to the conventional method.

In the case of a mixed aqueous solution of polyvinyl alcohol with a low saponification degree and a high saponification degree, the surface tension is mainly controlled by the low surface tension at a single concentration.

- Controlling the viscosity of the aqueous solution In the case of a mixed aqueous solution of polyvinyl alcohols with different degrees of polymerization, the viscosity of the aqueous solution is mainly controlled by the one with a high degree of polymerization. Therefore, it can be easily assumed that polyvinyl alcohol with a low degree of saponification can be used as a wettability improver in combination with other water-soluble polymers.

As described above, by using an aqueous solution containing polyvinyl alcohol with a low degree of saponification (84% or less), the effect of the metal back layer can be fully exhibited.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the main parts of a conventional method for forming a metal back layer on a fluorescent surface, Figure 2 is a diagram showing the surface tension of an aqueous solution, and Figure 3 is a diagram showing a metal back layer formed on a fluorescent surface according to the present invention. FIG. 3 is a sectional view of main parts according to a forming method. Agent Patent Attorney Usui 1) Li, S, ;-5'・1.・
... 1, -1 female PVA concentration (wt%) Figure 3 0

Claims (1)

[Claims] A step of applying a phosphor to the face surface to form a phosphorescent surface, a step of wetting this phosphorescent surface with an aqueous solution containing polyvinyl alcohol with a saponification degree of 84% or less, and a step of applying an organic polymer on the surface of the aqueous solution. 1. A method for manufacturing a metal back cathode ray tube, comprising the steps of forming a thin film of a substance, and forming a metal back layer on the thin film and then performing a firing process.