JPH065232A - Cathode ray tube - Google Patents

Abstract

(57) [Summary] [Structure] A metal in a heteropolyacid and a metal salt is mixed by mixing a hygroscopic metal salt with a heteropolyacid (HPA) which is a proton conductor, and encapsulating the mixture in a Si-O-Si skeleton. Ion M ⁺ React with and have a three-dimensional structure.
For example (HPA-M ⁺ ) − ^- free radicals such as O-Si can be formed in the gel framework. (HPA-M ⁺ )
The free radical is bulky in structure, and the surrounding area is Si—O.
Since it is surrounded by -Si, it exists stably in the gel thin film. [Effect] (HPA-M ⁺ Free radicals such as) are absorbed by the hygroscopic metal salt to partially absorb water molecules of water of crystallization contained in HPA, resulting in M ⁺ Always adsorbs protons. Further, HPA functions to prevent the invasion of carbon dioxide outside the membrane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube, and more particularly to a cathode ray tube having a thin film having an antistatic function on the outer surface of a front panel.

[0002]

2. Description of the Related Art Electrostatic charges are accumulated on the outer surface of the front panel of a cathode ray tube during operation or at the end of operation.
There were problems such as giving an electric shock to the human body and adsorbing dust.

In order to solve such a problem, Japanese Patent Laid-Open No.
64-27146 discloses a cathode ray tube provided with a glass gel thin film containing an alkali metal salt or an alkaline earth metal salt containing a silanol group as a main component. However, these salts have a problem in terms of environmental stability, because the metal salt absorbs moisture in the air to reduce the resistance of the glass thin film. That is, it is easily affected by humidity, and a sufficient effect cannot be obtained at low humidity. Furthermore, the metal salt has a drawback that it also absorbs carbon dioxide in the air to become a metal carbonate, which is precipitated from the glass gel thin film. Further, Japanese Patent Laid-Open No. 3-77247 discloses a technique for forming an antistatic film composed of conductive fine particles and an inorganic binder. However, in the method using the conductive fine particles, the transmittance changes depending on the film thickness.
Therefore, in order to provide the cathode ray tube with a sufficient transmittance, the film thickness of the antistatic film must be thin, and there is a problem that a sufficient antistatic effect cannot be obtained when the film thickness is thin. is doing.

[0004]

As described above, the conventional techniques have problems such as being unstable with respect to the environment and causing deterioration of optical characteristics. It is an object of the present invention to provide a cathode ray tube provided with an antistatic film which is environmentally stable and has a small film shrinkage and good optical characteristics.

[0005]

In order to solve the above-mentioned problems, the present invention provides a heteropolyacid and a hygroscopic metal salt containing at least SiO ₂ or P ₂ O ₅ as a main component on the outer surface of the front panel of a cathode ray tube. And a glass gel thin film containing

Further, the present invention is characterized in that the heteropolyacid and the hygroscopic metal salt are contained in the range of 0.01% by weight or more and 60% by weight or less with respect to the thin film. Further, the hygroscopic metal salt is a salt of an alkali metal or a salt of an alkaline earth metal. When the weight of the hygroscopic metal salt is A and the weight of the heteropolyacid is B, the weight ratio is 0.01 ≦ B.
/ A ≦ 5000.

[0007]

According to the present invention, a hygroscopic metal salt is supported by a heteropolyacid, and the hygroscopic metal salt and the heteropolyacid are enclosed in the gaps of the glass skeleton in the glass gel thin film, and the metal ions of the hygroscopic metal salt and the outside of the coating film. By preventing the reaction with the air, the glass gel thin film, which is environmentally stable and transparent, can achieve low resistance.

Conventionally, a hygroscopic metal salt has been used as an antistatic film.
There is a method using the method described in JP-A-64-27146.
Hygroscopic metal salts such as
It When the metal element of the hygroscopic metal salt is M, the metal ion
N M⁺ Is an alkoxide for forming a thin film glass skeleton, for example
Si (OR)_FourAnd reacts with (M⁺ −^-
Make free radicals such as O-Si). Via this free radical
The metal salt absorbs the absorbed water's protons,
It is well known that the rate goes up. However, (M⁺ −
^- O-Si) Free radical metal ion M⁺ Is in the air
It easily reacts with carbon to form carbonate, and metal carbonate is a film
It is deposited on the outside and the conductivity decreases. As a hygroscopic metal salt
Is disclosed, for example, in Japanese Patent Laid-Open No. 64-27146.
Li, K, Na, Ba, Sr, Ca nitrate, hydrochloric acid
Salts, sulfates, carbonates, etc.
I don't mind.

On the other hand, a heteropolyacid (hereinafter referred to as HPA) is known as a substance for lowering resistance. HPA is a heterogeneous acid among condensed acids produced by condensation of oxygen acid. Condensed between oxygen acids. HPA
The structure of is a structure in which a polyatom is arranged around a heteroatom located at the center through oxygen. There are many examples of centrally located heteroatoms that extend to elements of Groups 1 to 8 of the Periodic Table, specifically, P, As, Si, etc., and there is oxygen around the central heteroatom through oxygen. The formed poly atoms are composed of limited atoms such as Mo, W, Nb, and V. Specific examples of HPA include phosphotungstic acid (H
₃ PW ₁₂ O ₄₀ · nH ₂ O), phosphomolybdic acid (H ₃ P
Mo ₁₂ O ₄₀ · nH ₂ O), tungstosilicic acid (H ₄ Si
_{W 12 O 40 · nH 2 O} ), molybdenum de germane acid (H ₄ Ge
Mo ₁₂ O ₄₀ · nH ₂ O) and the like.

The polyanions of these HPAs have a structure called Keggin structure as shown in FIG. As shown in FIG. 2 (a), the Keggin structure is a tetrahedral oxyacid of 12 heteroatoms in which polyoxygen oxyacids 1 of 12 polyatoms share vertices and edges. It is a polyhedral structure that surrounds 2, and three octahedra 1 share a vertex and a ridge with each other to form one unit, and these four units form a central heteroatom as shown in FIG. 2 (b). It refers to a polyhedral structure with regular tetrahedral coordination. For example, it has a structure in which three octahedra WO ₆ are coordinated around P in a regular tetrahedral shape. Letting this Keggin structure be the primary structure, HPA has a polyanion and a counter cation (H ⁺ , Metal / inorganic / organic cations) and water of crystallization are well known. Therefore, HPA usually exists as a three-dimensional array with water of crystallization. The water molecules in this water of crystallization are protonated aqua cations such as H 2
A crystal having a face-centered cubic lattice diamond type array is formed in the form of ₃ (H ₂ O) ₂₉ ³⁺ . And, since these protons move around rapidly in the crystal, HPA is drawing attention as a proton conductor. Since HPA has a three-dimensional array structure as described above, it has a bulky structure and a large molecular weight. Such HPA can be used for example in Si
When dissolved in (OR) ₄ etc. to form a gel thin film,
HPA is encapsulated in the gaps in the glass skeleton existing in the gel, and HPA is incorporated into the Si—O—Si network structure as shown in FIG. This structure is stable and HPA does not deposit outside the coating. Therefore, a low resistance film can be obtained.

[0011] However, molecules that the HPA form the glass skeleton, for example, Si HPA itself be dissolved in solution, such as (OR) ₄ does not react with Si (OR) _4, also, Si (OR) ₄ is Condensate by itself to produce Si-OS
Form an i-bond. Therefore, in the film made of a strong Si-O-Si skeleton, HPAs are isolated from each other in the gap between the Si-O-Si skeletons, so that proton conduction between HPAs is blocked by the Si-O-Si skeleton. , The conductivity does not increase so much. Therefore, it is conceivable to increase the amount of HPA in order to increase the conductivity only with HPA, but in order to have sufficient conductivity, the relative amount of molecules forming the above glass skeleton is decreased and the relative amount of HPA is increased. Because there are many
When this molecule is condensed, HPA prevents the formation of the Si—O—Si skeleton, and as a result, the film is not formed, the film strength is significantly reduced, and the transparency of the film is lost.
Therefore, the present inventors have paid attention to the fact that the above-mentioned HPA is bulky in structure and contains water of crystallization.

That is, a hygroscopic metal salt and HPA, which is a proton conductor, are mixed and encapsulated in a Si--O--Si skeleton, whereby HPA and the metal ion M ⁺ in the metal salt are mixed. React with and have a three-dimensional structure, and, for example, (H
PA-M ⁺ ) − ^- Making O-Si radicals such as in the gel framework. Where (HPA-M ⁺ ) The free radical is bulky in structure and is larger than the gap of the gel skeleton, and the surroundings are surrounded by Si—O—Si. Therefore, as shown in FIG. 4, the free radical is incorporated into the network structure of Si—O—Si. HPA and metal ion M ⁺ Is believed to form free radicals and stably exist as such in a gel thin film having a glass skeleton.

The reaction between the HPA and the hygroscopic metal salt occurs by mixing. In addition, (HPA-M ⁺ Free radicals such as (1) are partially absorbed by the hygroscopic metal salt of water molecules of water of crystallization contained in HPA, and the water of crystallization is not easily desorbed from the crystals. Therefore, the metal M ⁺ Always adsorbs protons. In addition, since HPA functions to prevent the invasion of carbon dioxide outside the membrane, (HPA-M ⁺ )
It is presumed that free radicals and carbon dioxide do not react to form carbonate.

Further, unlike the case of only HPA, (HP
A-M ⁺ Since they are free radicals, they are not isolated from each other, and as a result, the concentration of protons in the thin film is increased and the conductivity of the thin film is increased. Also, most of this proton is different from HPA, which is caused by moisture in the air outside the membrane.
Since it is due to the water of crystallization, it is retained inside the film and the conductivity is not affected by the humidity outside the film. Therefore, it is possible to obtain an antistatic film that is environmentally stable and has excellent optical characteristics.

That is, when the hygroscopic metal salt and HPA were used alone, the conductivity of the antistatic film was insufficient. However, when these substances were mixed, the hygroscopic metal salt became H.
When encapsulated in the skeleton component so as to be supported by PA, it is considered that the problem of conductivity can be solved by the interaction between the hygroscopic metal salt and HPA. In addition, (HP
A-M ⁺ Since (1) is bulky in structure, the film contraction of the gel thin film is small, and therefore a substance having a function other than antistatic, such as a dye, can be enclosed without being affected by the film strength and environmental stability.

The skeleton of the gel thin film is SiO ₂ ,
P ₂ O ₅ , B ₂ O _3, etc., or a mixture thereof, but those made from a solution of metal alkoxides, metal acetyls, etc. are preferable. Further, it may contain an element other than Si, P, B, for example, Zr, Ti, Fe, Al, V or the like for the purpose of imparting functionality such as improvement in film strength.

In order to utilize the above-mentioned interaction between the hygroscopic metal salt and HPA, it is desired to mix them in a predetermined ratio. If the hygroscopic metal salt is A and HPA is B,
The weight ratio is preferably 0.01 ≦ B / A ≦ 5000. When B / A is 0.01 or less, no interaction occurs, which is the same as when HPA is used alone.
When A is 5000 or more, it is the same as when the hygroscopic metal salt is used alone.

The content of the hygroscopic metal salt and HPA contained in the glass skeleton component is based on that of the glass skeleton component.
It is desirable that the content is 0.01% by weight or more and 60% by weight or less. If the amount is 0.01% by weight or less with respect to the glass skeleton component, the amount of the conductive material is insufficient with respect to the glass skeleton component, and a sufficient antistatic effect cannot be obtained. Also, 60
When it is at least wt%, (HPA-M ⁺ ) By Si-O
-Si skeleton formation is prevented, the film strength is significantly reduced, and as a result, no film is formed.

The coating of the present invention can be obtained by dissolving the above-mentioned heteropolyacid and hygroscopic metal salt in the skeleton component and the above-mentioned metal alkoxide and applying the solution to the cathode ray tube by a spray method, a spin method, a dip method or the like. .

[0020]

EXAMPLES The present invention will be described below with reference to examples.

First, a gel thin film coating solution was prepared by changing the addition amounts of lithium nitrate, which is a hygroscopic metal salt, and phosphotungstic acid, which is a heteropoly acid, at the following composition ratios. After dip coating this solution on a glass substrate,
By baking at 120 ° C. for 10 minutes, the film thickness is about 0.
A thin film of 1 μm was obtained. The evaluation results of the obtained film are shown in Table 1. Here, the amounts of lithium nitrate and phosphotungstic acid shown in Table 1 are represented by a weight ratio with respect to the obtained thin film. As an evaluation method of the obtained thin film, first, initial resistance value, film appearance, and pencil hardness (pencil hardness test JIS K540
0) was measured, and then the film was subjected to two weather resistance tests, a heat resistance test and a water resistance test, to measure the resistance value. Here, the heat resistance test is a measurement of the surface resistance after holding at 60 ° C. for 500 hours in a constant temperature oven, and the water resistance test is 6
The surface resistance was measured after immersion in pure water at 0 ° C. for 24 hours. Each resistance value, film strength, etc. shows the average value of the obtained data. Weight ratio: Tetraethoxysilane 27 wt% Nitric acid 0.29 wt% Water 34 wt% Isopropyl alcohol 72 wt% Lithium nitrate 0-5 wt% Phosphotungstic acid 0-15 wt %

[0022]

[Table 1] The relationship between the added amount and the film characteristics is shown in FIGS.

FIG. 5 shows the film characteristics when the addition amount of the heteropolyacid alone was changed without adding the hygroscopic metal salts of Experiment Nos. 1 to 5 in Table 1, and the addition amount of phosphotungstic acid was plotted on the horizontal axis. Is a graph in which the vertical axis represents the surface resistance value. Figure 5
In, the solid line indicates the initial resistance value, the broken line indicates the resistance value after the heat resistance test, and the alternate long and short dash line indicates the resistance value after the water resistance test. The shaded area is an area that does not maintain transparency. Furthermore, the film strength is in the practical range of 7H
9H to 9H are indicated by ◯, and 6H or less which is not in a practical range is indicated by X. Hereinafter, the same legend is used from FIG. 6 to FIG. Figure 5
As a result, in the case of the film to which phosphotungstic acid is added, the resistance value is almost the same as the initial value and exhibits excellent weather resistance, but the resistance value required for the antistatic effect is 1 × 10 ¹⁰ Ω.
It can be seen that the amount of addition is required to be approximately 50 wt% or more in order to obtain the following. However, as shown in Table 1, it can be seen that with this amount, the film strength is weak and the transparency cannot be maintained. This tendency was also seen in other HPAs.
It is considered that this is because the excess HPA is not enclosed in this gap and precipitates as crystals.

FIG. 6 shows the resistance value when the amount of hygroscopic metal salt alone was changed without adding HPA of Experiment Nos. 6 to 11 in Table 1 above. From this, it can be seen that the initial resistance value in the region where the transparency of the film to which lithium nitrate is added is maintained is good, but the resistance value is significantly deteriorated after the weather resistance test, and the weather resistance is poor. This tendency was the same for other hygroscopic metal salts. this is,
This is because, in the case of heat resistance test, the relative humidity is lowered, so that the metal salt becomes carbonate and precipitates outside the coating film, and in the case of water resistance test, the metal salt dissolves in water. I understood it.

In addition, FIG. 7 shows experiment numbers 12 to 1 in Table 1.
Fix the addition amount of lithium nitrate of 5 to 0.01 wt%,
6 is a graph showing the amount of phosphotungstic acid added on the horizontal axis and the surface resistance value on the vertical axis. As a result, when the metal salt was not added, the HPA amount, which was in the region where the film characteristics were poor, was 50 wt.
%, Even when the metal salt is added in a small amount of 0.01 wt%, an antistatic film having good weather resistance can be obtained. However, when HPA is 55 wt%, transparency and film hardness deteriorate. Therefore, metal salt (A) and HPA
The ratio with (B) is desired to be B / A ≦ 5000.

Therefore, the results obtained when the amount of HPA was fixed at 55 wt% and the amount of lithium nitrate was changed are Experiment Nos. 15 to 17. As can be seen from the results of Experiment No. 16, when the amount of the metal salt increases, it is possible to obtain a film having good weather resistance, which exhibits an antistatic effect even when HPA is 55 wt%. This tendency was also seen when using other metal salts and HPA. Therefore, metal salt (A) and HPA
It has been found that the condition that the ratio with (B) is B / A ≦ 5000 is desired.

The sample of Experiment No. 17 is devitrified, and the film strength is weak as 6H. This is because the total amount of A and B is 6
It is considered to be because the amount of the conductive material is too much with respect to the skeleton component, which is 2 wt% and exceeds 60 wt%. From other experimental results, A + B is required to obtain a good antistatic film.
It was found that ≦ 60 wt%. It was also found that the antistatic effect was not obtained unless the amount of the conductive material was 0.01 wt% or more. From the above, the desirable range of the addition amount of the metal salt (A) and the heteropolyacid (B) is 0.01
wt% ≦ A + B ≦ 60 wt%.

Further, FIG. 8 shows the results of Experiment Nos. 18 to 21 when the amount of the metal salt was fixed at 10 wt% and the amount of HPA was changed, and the abscissa indicates the addition amount of phosphotungstic acid and the ordinate indicates. 2 is a graph showing the surface resistance value in FIG. From this, it can be seen that the weather resistance becomes worse as the amount of phosphotungstic acid becomes smaller, and that the transparency and the film hardness cannot be put to practical use at 0.1 wt% or less. This tendency was also seen when using other metal salts and HPA. From this, it is desired that the ratio of the metal salt (A) and HPA (B) is B / A ≧ 0.01. From the above, it was found that the desirable ratio of the metal salt (A) and the heteropolyacid (B) should be 0.01 ≦ B / A ≦ 5000.

Experimental results 22 to 25 show the results of examination of the composition ratios at which more favorable film strength and surface resistance value are obtained. From this, as a more preferable range, the amount of the conductive material is 10% by weight or more and 32% by weight or less with respect to the skeleton component, and the ratio of the metal salt (A) and the heteropolyacid (B) is 1 ≦.
B / A ≦ 500. Next, specific examples of the present invention will be described. <Example 1>

FIG. 9 is a partially cut side view showing a cathode ray tube 10 manufactured according to the present invention. This cathode ray tube 10 is
It has an airtight glass envelope 11 whose interior is evacuated. The envelope 11 has a neck 12 and a cone 13 continuous from the neck 12. Further, the envelope 11 has a cone 13 and a face plate 14 sealed with frit glass. A metal tension band 15 is wound around the side wall of the face plate 14 to prevent explosion.
An electron gun 16 that emits an electron beam is arranged on the neck 12. On the inner surface of the face plate 14, an electron gun
A phosphor screen 17 including a phosphor layer that emits light when excited by an electron beam from 16 is provided. Also,
A deflection device (not shown) for deflecting the electron beam so as to scan the phosphor screen is attached to the outside of the cone 13.

By the way, the antistatic film 18 of the present invention is formed on the outer surface of the face plate 14 of the cathode ray tube 10 by applying the lower layer forming solution and the upper layer forming solution of the first embodiment. .

Although the above-mentioned embodiment is applied by the dipping method, in this embodiment, the composition liquids of Experiment Nos. 23 and 25 in Table 1 are spun on the front surface of the face plate of the 25-inch cathode ray tube after completion of assembly. Apply by coat, 150 ℃
And baked for 30 minutes to form a transparent antistatic film having a thickness of 0.2 μm. The surface resistance at this time is 1 × 10 ⁹ It was Ω. When this was subjected to the same heat resistance test and water resistance test as in Example 1, the surface resistance after the test was 1 × 10 ^{9 which was} not different from the initial resistance. Ω was shown. From this, it is possible to obtain a cathode ray tube having an antistatic film which is very stable to the environment, and the remarkable effect of the present invention was confirmed. <Example 2>

Experiment No. 23 in Table 1 as in Example 1 above
2% by weight of the dye for the color selective absorption filter was further added to the No. 25 and No. 25 composition liquids, and the mixture was applied to the face plate of the color picture tube by the spraying method and baked at 150 ° C. for 30 minutes to provide the color selective absorption filter. An antistatic film was prepared. The surface resistance at this time is 4 × 10 ⁹ When the heat resistance test and the water resistance test similar to those in Table 1 were performed, the surface resistance value after the test was 8 × 10 after the heat resistance test.
⁹ Ω, after water resistance test 1 × 10 ⁹ It was Ω. Than this,
Even when the dye was added, the remarkable effect of the present invention was recognized.

[0034]

As described above, according to the present invention, a cathode ray tube having an antistatic film that is stable against the environment can be easily obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an atomic model showing a state of an antistatic film of a conventional cathode ray tube.

FIG. 2 is a schematic diagram showing the primary structure of heteropolyacid.

FIG. 3 is a schematic diagram of an atomic model showing a state of a gel film containing heteropolyacid.

FIG. 4 is a schematic diagram of an atomic model showing a state of a gel film for explaining the present invention.

FIG. 5 is a characteristic diagram showing film characteristics when a hygroscopic metal salt is not added to a gel thin film and the amount of heteropolyacid added is varied.

FIG. 6 is a characteristic diagram showing film characteristics when heteropolyacid is not added to the gel thin film and only the hygroscopic metal salt is added.

FIG. 7 is a characteristic diagram showing film characteristics when a hygroscopic metal salt and a heteropolyacid are added to a gel thin film and the addition amount of only the hygroscopic metal salt is changed.

FIG. 8 is a characteristic diagram showing film characteristics when a hygroscopic metal salt and a heteropolyacid are added to a gel thin film, and the addition amount of only the heteropolyacid is changed.

FIG. 9 is a sectional view showing a structure of a cathode ray tube according to the present invention.

Claims (4)

[Claims] 1. A cathode ray tube comprising a glass gel thin film containing at least SiO ₂ or P ₂ O ₅ as a main component and containing a heteropolyacid and a hygroscopic metal salt on the outer surface of the front panel. 2. The heteropolyacid and the hygroscopic metal salt are contained in the range of 0.01% by weight or more and 60% by weight or less with respect to the thin film.
The described cathode ray tube. 3. The cathode ray tube according to claim 1, wherein the hygroscopic metal salt is a salt of an alkali metal or a salt of an alkaline earth metal. 4. When the weight of the hygroscopic metal salt is A and the weight of the heteropolyacid is B, the weight ratio is 0.01 ≦.
The cathode ray tube according to claim 1, wherein B / A ≦ 5000.