JPH0794091A - Method for manufacturing cathode ray tube and cathode ray tube using the same - Google Patents

Abstract

(57) [Summary] [Structure] When a phosphor layer with a metal back layer is formed, by adjusting the firing temperature of the organic resin component that constitutes the metal back undercoat film, the metal back layer formed on the inner surface of the CRT is adjusted. To obtain a high-luminance, high-resolution cathode ray tube with improved smoothness and no blisters. [Effect] Since a metal back layer having high smoothness and high mirror effect can be obtained, a cathode ray tube with high brightness and high resolution can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a cathode ray tube (hereinafter referred to as CR
(Hereinafter referred to as "T"), a method of forming an undercoat film for forming a metal back layer of a metal vapor deposition layer of aluminum or the like on the phosphor surface, and C manufactured using the method.
Regarding RT.

[0002]

2. Description of the Related Art CR represented by a television cathode ray tube
The T is used in various display fields, and its display capability is also required to have high definition, high resolution, and high brightness in accordance with diversification of information and high density.

Conventionally, as one of the methods for manufacturing a CRT which meets these requirements, a metal vapor deposition layer (hereinafter referred to as a metal back layer) formed by aluminum vapor deposition is provided on a phosphor layer, and the CRT is formed by its mirror effect. There is a method of reflecting the light of the phosphor emitted on the inner surface to the front surface of the panel. As described above, in the method of directly forming a metal vapor deposition layer of aluminum or the like on the phosphor surface, a metal back layer having a mirror effect cannot be obtained due to the unevenness of the phosphor surface. Therefore, in order to increase the brightness of the CRT, it is essential to form an organic material layer that smoothly fills the irregularities on the phosphor surface.

That is, it is necessary to form an aluminum back undercoat film as smooth as possible on the phosphor surface, and form a metal back layer on this film to secure its smoothness and enhance its mirror effect.

Generally, the organic layer is called an aluminum back undercoat film, and the metal back layer using the undercoat film is formed as follows.
First, an aluminum back undercoating agent is directly applied on the phosphor surface to make the uneven surface of the phosphor surface smooth, and a metal vapor deposition layer of aluminum or the like is further formed on this undercoat film, and then the undercoat is subjected to heat treatment. The metal back layer is formed by decomposing and removing the organic component of the agent.

Specific methods for forming the aluminum back undercoat film are roughly classified into an emulsion method in which an emulsion obtained by emulsifying a resin in water is applied to the phosphor surface, and a water film is applied to the phosphor surface and then a solvent is applied. There is a water film method in which a melted resin is applied on a water film and dried.

[0007]

In the conventional method of forming an aluminum back undercoat film, the former emulsion method is a one-component type, so that it is considerably difficult to fill the irregularities of the phosphor surface to form a smooth surface. A large amount of emulsion is applied, and after vapor-depositing metal on this smooth surface, the amount of gas volatilized when the coating layer of emulsion is removed by firing the organic component is large. There is a limit to achieving a high level of smoothness of the metal back layer, because the phenomenon of "flaming" that separates from the metal back layer easily occurs.

On the other hand, the latter water film method is a wet-on-wet method in which a water film is formed on the phosphor surface and a resin dissolved in a solvent is applied and dried on the water film surface.
The resin thickness of the undercoat film formed is smaller than that of the emulsion method, and the amount of volatile gas is small when the aluminum back undercoat film is baked and removed after metal deposition on the aluminum back undercoat film.

However, in order to form a smooth metal back layer, the water film or the undercoat film must be thickened, and the "blistering" phenomenon easily occurs in the metal back layer as in the emulsion method. There is an essential problem that there is a limit in obtaining the mirror effect by improving the smoothness of the aluminum vapor deposition film necessary for improving the brightness of the CRT.

Conventionally, the cause of this "blistering" phenomenon is (a) insufficient number of gas vent holes in the contact portion between the metal back layer and the phosphor, and (b) thick film of the metal back undercoat film. It has been considered that the increase in the amount of volatile gas at the time of firing due to the increase in the temperature. Therefore, in order to prevent the "blistering" phenomenon of the metal back layer, the thickness of the metal back undercoat film should be made as thin as possible, or the firing removal time of the metal back undercoat film should be set very long to reduce the amount of volatile gas. The method of generating each one has been taken.

However, when the thickness of the metal back undercoat film is reduced, the unevenness on the phosphor surface cannot be filled, and a smooth metal back layer capable of realizing an improvement in brightness is not formed. This state is shown in FIGS. 1 and 2. FIG. 1 is a schematic view showing a cross section of a state where a metal back undercoat coating is thinly applied on the phosphor surface, and FIG. 2 is a schematic diagram showing a state where a metal back undercoat coating is applied thickly on the phosphor surface. is there.

Further, when the baking time of the metal back undercoat film is set to be very long, the baking time becomes long, so that the productivity of the metal back layer is greatly reduced.
Therefore, in order to solve these drawbacks, even if the thickness of the metal back undercoat film is increased, "fire blisters"
A method of forming a metal back layer that does not include
No. 18657. This method, between the metal back undercoat film and the metal back layer,
In this method, an intermediate layer made of polyvinyl alcohol modified with boric acid or borax is formed to form holes for degassing during firing of the metal back layer and the metal back undercoat film.

In Japanese Patent Publication No. 57-18815, a metal back layer having holes for removing volatile gas is formed on a metal back undercoat film containing a crystalline substance such as ammonium oxalate. Methods are listed. In either method, fine holes for degassing the gas generated when the metal back undercoat film is baked are formed in the metal back layer, and it is difficult to form a metal back layer having a high mirror effect.

As described above, the conventional method for obtaining a metal back layer having high smoothness is only to increase the thickness of the resin layer forming the metal back undercoat film, but the thicker the layer is, the more it is baked. Since the amount of volatile gas generated at times increases, it is necessary to increase the diameter of the fine holes for removing volatile gas in the metal back layer or to increase the number of holes, so the mirror effect of the metal back layer formed by these methods is sufficient. It hasn't become something like that.

[0015]

Means for Solving the Problems The inventors of the present invention have not studied the above problems at all, and hold and fix the phosphor particles forming the phosphor layer at the time of firing the metal back undercoat film. As a result of diligent study on the influence of the presence or absence of the organic resin binder component on the "fire blistering" phenomenon of the metal back layer, a metal back undercoat film is formed on the phosphor surface formed by the organic resin binder and the phosphor. To form a vapor-deposited aluminum layer thereon, and when the volatile gas generated during the removal of the metal back undercoat film by firing pushes up the vapor-deposited aluminum film, the phosphor layer in contact with the vapor-deposited aluminum film is used as a fluorescent substance. The organic resin binder component of the body layer is used as a fixed state to make it difficult to move so that the aluminum vapor deposition film can be positively ventilated with micropores for removing volatile gas. Without form, "blistering"
It was found that the metal back layer can be formed without causing a phenomenon, and the present invention was completed.

That is, the gist of the present invention is that the CR
Forming a metal back undercoat surface on the phosphor surface formed by the phosphor particles and the binder component on the inner surface of T, and further forming a metal vapor deposition layer on the surface, baking the organic resin binder component forming the phosphor layer The firing is started from a temperature lower than the starting temperature, the firing is finished at a temperature lower than the firing end temperature of the binder component, the firing of the metal back undercoat film is completed, and the firing of the phosphor surface is then completed. CR characterized by forming a back phosphor surface
It is in the manufacturing method of T.

A detailed description of the invention is given below. In the baking process of the metal back undercoat film, photo-cured polyvinyl alcohol or the like which is mainly used as an organic resin binder component holding the phosphor particles in the phosphor surface is also baked.

That is, when the baking of the metal back undercoat film is carried out at the same time as or after the baking of the organic resin binder constituting the phosphor surface, the phosphor particles at the time of baking the metal back undercoat film are Since it is not supported and fixed by the organic resin binder component and it is in a state that it is very easy to move (a state that it can easily move by touching with fingers), the aluminum vapor deposition film on the metal back undercoat film swells due to the pressure of volatile gas A gap is likely to be formed between the phosphor layer and the phosphor layer, so that the phosphor layer is easily peeled off to cause a "blister" phenomenon.

On the other hand, when the metal back undercoat film is baked faster than the organic resin binder component constituting the phosphor surface, the volatile gas generated during the baking of the metal back undercoat film pushes up the aluminum vapor deposition film. Since the component fixes the phosphor particles, the adhesion between the aluminum vapor deposition film and the phosphor layer is strong and peeling is difficult. Therefore, it is possible to prevent the “blistering” phenomenon of the metal back layer without positively forming pores with only the necessary minimum amount of holes for removing volatile gas.

The metal back undercoating agent used in the present invention is not particularly limited as long as it can be thermally decomposed at a temperature lower than that of the organic resin binder component constituting the phosphor layer, from the viewpoint of baking property, but it has a high CRT inner surface. Considering the condition of being irradiated with an electron beam in a vacuum state, it is necessary that the baking residue and impurities (heavy metal, halogen, etc.) are not included. Polyvinyl alcohol is usually used as the organic resin binder for forming the phosphor layer, and its thermal decomposition is 250 ° C. to 3 ° C.
It starts at 50 ° C and ends at 400 ° C to 450 ° C.

Therefore, as a metal back undercoating agent, thermal decomposition starts at around 200.degree.
It is preferable that the thermal decomposition is completed before and after. The properties of the metal back undercoating agent used in the present invention are applied in the state of being dissolved in a solvent or in the form of an emulsion emulsified in water, and in order to obtain a particularly smooth undercoating film. It is preferable to increase the film thickness by using the latter undercoat agent depending on the emulsion state.

[0022]

EXAMPLES The present invention will be described below with reference to examples. In addition, the part in an Example shows a weight part.

The evaluation method is as follows. -Presence of blistering: Visual evaluation was performed after firing. Luminance relative value: Relative value when the luminance of white of the obtained cathode ray tube, which is a combination of the red phosphor, the blue phosphor, and the green phosphor, is measured and the luminance of the current product is 100%.

Synthesis of Acrylic Resin for Solvent-Based Metal Back Undercoat Agent [Acrylic Resin (A1)] Pour 800 parts of water into a 2-liter four-necked flask, and use polyvinyl alcohol (saponification degree 88%, polymerization degree 1000). ) 1 part was dissolved. Next, a monomer solution in which 2.0 parts of azobisisobutyronitrile was dissolved in 100 parts of isobutyl methacrylate was added to the flask and the atmosphere was replaced with nitrogen gas, and then at 80 ° C. for 2 hours under a nitrogen gas stream, Stir vigorously. Then, the mixture was heated at 90 ° C. for 2 hours, further heated to 120 ° C., and the residual monomer was distilled off together with water. The obtained slurry was filtered, washed, and dried with a hot air dryer at 50 ° C. to obtain a white granular powder acrylic resin (polymerization rate 98%, molecular weight 150,000).

[Acrylic resin (A2) to acrylic resin (A4)] Acrylic resin (A1) was prepared in the same manner as acrylic resin (A1) except that the compounds having the compositions shown in Table 1 were used.
2) to acrylic resin (A4) were prepared. Table 1 shows the polymerization rate and the molecular weight of each of the obtained acrylic resins.

[0026]

[Table 1]

The abbreviations in the table are as follows. iBMA: Isobutyl methacrylate EA: Ethyl acrylate nBMA: Normal butyl methacrylate MAA: Methacrylic acid MMA: Methyl methacrylate-Synthesis of emulsion type acrylic resin for metal back undercoat agent

[Acrylic resin (B1)] 2 liters of 4
In a one-necked flask, 370 parts of water, 8.0 parts of polyoxyethylene nonylphenyl ether (manufactured by Kao Corporation; trade name Emulgen 950), alkylbenzene sulfonate (manufactured by Kao Corporation; trade name Neoperex No. 25) ) 0.
2 parts and 0.6 part of potassium persulfate were mixed. Next, a mixture of 100 parts of normal butyl methacrylate and 100 parts of isobutyl methacrylate was added, and the mixture was stirred under a nitrogen atmosphere for 7 minutes.
Polymerization was performed by heating at 0 ° C. for 5 hours to obtain an emulsion acrylic resin (B1) (solid content: 36.0%). The polymerization rate and molecular weight of the obtained acrylic resin are shown in Table 2.

[Acrylic resin (B2)] An acrylic resin (B2) was obtained in the same manner as the acrylic resin (B1) except that the compounds having the compositions shown in Table 2 were used. Table 2 shows the polymerization rate and the molecular weight of each of the obtained acrylic resins.

[0030]

[Table 2]

The abbreviations in the table are as follows. iBMA: isobutyl methacrylate EA: ethyl acrylate nBMA: normal butyl methacrylate MAA: methacrylic acid MMA: methyl methacrylate

[Example 1] A phosphor surface was formed by a photocuring method using a photocurable binder having a firing start temperature of 270 ° C and a firing end temperature of 400 ° C and phosphor particles. An aluminum back undercoating agent prepared by dissolving 3 parts of an acrylic resin (A1) in 100 parts of toluene was spray-coated on the inner surface of a 14-inch CRT in which a water film was formed in advance on the color phosphor surface. After that, the solvent and water in the formed coating film were removed by drying to form a metal back undercoat coating film. Next, after vapor-depositing aluminum on the metal back undercoat film, firing was performed under the firing conditions shown in Table 1 to obtain a color CRT having a phosphor surface provided with a metal back layer. The firing time was 1 hour. Here, as an intermediate inspection, the film thickness of the applied metal back undercoat film and the presence or absence of "blistering" of the aluminum vapor deposition film in the firing process were evaluated. The brightness was also measured. The evaluation results obtained are shown in Table 3.

[0033]

[Table 3]

Example 2 A color CRT having a phosphor surface provided with a metal back undercoat film was prepared in the same manner as in Example 1 except that the acrylic resin (A2) was used. The evaluation results obtained are shown in Table 3.

[Example 3] A color cathode ray tube was prepared in the same manner as in Example 1 except that 5 parts of the acrylic resin (A1) was used. Table 3 shows the evaluation results of the obtained undercoat film.

[Comparative Examples 1 and 2] A metal back undercoat film was formed in the same manner as in Example 1 except that the acrylic resin (A3) and the acrylic resin (A4) were used. Aluminum was vapor-deposited on the obtained metal back undercoat film, and the binder resin contained in the phosphor surface and the organic components of the metal back undercoat film were baked under the conditions shown in Table 3. Peeling due to "fire blistering" occurred and it was not possible to make a color CRT. The evaluation results are shown in Table 3.

[Comparative Example 3] A metal back undercoating agent was formed on the phosphor surface prepared in the same manner as in Example 1.
Acrylic resin emulsion (Japan Acrylic Chemical Co., Ltd.)
Manufactured; applied with brand name Brimal B-74) and dried,
After forming the aluminum vapor-deposited film, firing was performed under the conditions shown in Table 3, and the firing time was 5 hours, which was extremely long. Table 3 shows the evaluation results of the obtained color cathode ray tubes.

Example 4 Pure water was added to the acrylic resin (B1) to prepare an Ersion metal back undercoat agent diluted to a solid content of 17%. Next, the metal back undercoating agent was applied onto the phosphor surface of a 14-inch CRT having the phosphor surface prepared in Example 1 by heating it to 42 ° C. in advance and heating it with a far infrared heater to undercoat. A film was formed. Then, aluminum was vapor-deposited on the undercoat film and baked under the conditions shown in Table 4 to obtain a color CRT. Here, as an intermediate inspection, the film thickness of the applied metal back undercoat film, the aluminum vapor deposition film in the firing step were evaluated, and the brightness was measured. The evaluation results are shown in Table 4.

[0039]

[Table 4] [Comparative Example 4] Acrylic resin (B2) as acrylic resin
A metal back undercoat film was formed in the same manner as in Example 4 except that was used. After drying the obtained undercoat film, aluminum vapor deposition and firing were performed.
The peeling of the metal back layer due to "fire blistering" occurred, and C
I couldn't convert it to RT. The results are shown in Table 4.

[Comparative Example 5] The procedure of Example 4 was repeated except that an acrylic resin emulsion (Nippon Acrylic Chemical Co., Ltd .; trade name Primal B-74) was used as the metal back undercoating agent. A metal back undercoat film was formed, dried, and then aluminum vapor deposition was performed to obtain a color cathode ray tube. The evaluation results are shown in Table 3.

[0041]

As described above in detail, according to the present invention, when the phosphor layer with the metal back layer is formed, the smoothness can be improved by adjusting the firing temperature of the organic binder resin component constituting the metal back undercoat film. It is possible to form a metal back undercoat film with a high reflectivity and to form a metal back layer with a high mirror effect, resulting in high brightness,
It is possible to meet the technical requirement that a high-resolution CRT be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a state in which a thin metal back undercoat film is formed on a phosphor surface formed on a glass panel. FIG. 2 is a cross-sectional view showing a state in which a thick metal back undercoat film is formed on the phosphor surface formed on the glass panel.

[Explanation of symbols]

 1: Glass panel 2: Phosphor particles 3: Metal back undercoat film

Claims (4)

[Claims] 1. An organic resin binder component for forming a phosphor layer by forming a metal back undercoat film and an aluminum vapor deposition layer on a phosphor layer formed of an organic resin binder and phosphor particles on the inner surface of a cathode ray tube. Firing at a temperature lower than the firing start temperature of, the firing ends at a temperature lower than the firing end temperature of the organic resin binder component to form a metal back layer, and further the firing of the phosphor layer. And a method for manufacturing a cathode ray tube. 2. A resin for forming a metal back undercoat film, whose firing start temperature is lower than a firing start temperature of an organic resin binder for forming a phosphor layer, and a firing end temperature of a resin for forming a metal back undercoat coat is fluorescent. The method for producing a cathode ray tube according to claim 1, wherein a resin having a temperature lower than a firing end temperature of the organic resin binder for forming a body layer is used. 3. A cathode ray tube obtained by the manufacturing method according to claim 1. 4. A cathode ray tube obtained by the manufacturing method according to claim 2.