JPH10212475A - Fluorescent substance and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a high-quality fluorescent substance, hardly producing a residue in a fluorescent adherend part of a cathode-ray tube and capable of reproducing a highly precise image by sticking a specific amount of alumina particles having a specified particle diameter to surfaces of fluorescent substance grains consisting essentially of zinc sulfide and/or yttrium oxysulfide. SOLUTION: This fluorescent substance is produced by sticking (B) alumina particles having 0.05-2μm average particle diameter in an amount of 0.05-2wt.% based on the weight of (A) fluorescent substance grains consisting essentially of zinc sulfide and/or yttrium oxysulfide to the surfaces of the component A. The objective fluorescent substance is obtained by initially dispersing the component A in pure water, then adding an aqueous solution of zinc sulfate (ZnSO4 ) to the resultant dispersion, stirring the mixture, adding a dispersion of the component B thereto, stirring the mixture dispersion, subsequently regulating the pH to 8-9, thereby depositing zinc hydroxide, simultaneously stirring the mixture, sticking the component B through the zinc hydroxide to the surfaces of the component A and finally filtering the dispersion of the component A to which the component B sticks and drying and sieving the resultant filter cake.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor used in a cathode ray tube for a color television or a computer display and a method for producing the same.
The present invention relates to a phosphor capable of reproducing a high-quality and high-definition image and an efficient manufacturing method thereof.

[0002]

2. Description of the Related Art Generally, blue (B), green (G), and red (R) light emitted by electron beam excitation are provided in a picture tube (CRT) of a color television receiver or a cathode ray tube (CRT) for a computer display. Light emitting phosphors are used.

[0003] For example, as a blue light emitting phosphor for color television, silver and chlorine activated zinc sulfide phosphor (Zn) is used.
S: Ag, Cl), silver and aluminum activated zinc sulfide phosphor (ZnS: Ag, Al), silver, gold, aluminum activated zinc sulfide phosphor (ZnS: Ag, Au, Al) and the like are used. Examples of the green light emitting phosphor include copper and aluminum activated zinc sulfide phosphors (ZnS: Cu, Al),
Copper, gold, aluminum activated zinc sulfide phosphor (ZnS: C
u, Au, Al). As a red light emitting phosphor, a europium-activated yttrium oxysulfide phosphor (Y ₂ O ₂ S: Eu) or the like is generally and widely used.

As the phosphors used in the cathode ray tube for computer displays, the following phosphors are generally used in addition to the above-mentioned various phosphors for cathode ray tubes. That is, a manganese-activated zinc silicate phosphor (Zn ₂ SiO ₄ : Mn) is used as the green light-emitting phosphor,
In some cases, a manganese-activated zinc phosphate phosphor (Zn ₃ (PO ₄ ) ₂ : Mn) or the like is used as the red light-emitting phosphor.

[0005] The above-mentioned various phosphors are made of C, such as a cathode ray tube.
The following processing is performed in an RT assembly factory to form a phosphor layer of a CRT. First, the phosphor particles are uniformly mixed with pure water as a dispersion medium, polyvinyl alcohol (PVA), ammonium bichromate (ADC), and a surfactant to form a slurry. The prepared slurry is
It is spin-coated on the inner surface of the face plate of a cathode ray tube, and further dried to form a coating film. Next, the face plate having the coating film formed thereon is irradiated with ultraviolet rays through a mask on an exposure table, and only a predetermined portion of the coating film is exposed. The pattern exposed by the ultraviolet rays is in a stripe shape or a dot shape.
Curing with a photoresist made of ADC. Then, in the next development step, pure water is sprayed on the coating film to wash the coating film, and at the same time, the phosphor coating film in the uncured portion is washed off, and a stripe or dot pattern is formed. It is formed. This pattern forming step is repeated for phosphor particles of three primary colors B, G, and R, respectively, to form a phosphor layer (phosphor film) for a color CRT or a color CRT.

[0006] In recent years, with the spread of new cathode ray tubes such as high-definition television receivers and displays for high-definition computers, the phosphors used in the cathode ray tubes have been required to further improve their characteristics. Have been. There are many requests for improvement in the ease of use of the phosphor in the cathode ray tube manufacturing process, which leads to improvement in the quality and yield of the phosphor screen. It is always sought to strengthen the fit.
In other words, when performing cleaning by spraying with pure water in the developing step, the phosphor particles in the portions cured by the irradiation of ultraviolet rays are not peeled off from the adhered portions, but are adhered in a strong bonding state while maintaining a predetermined pattern shape. Department is required.

As a method for improving the adhesion of the phosphor,
Various techniques have been reported so far. For example, in JP-A-2-20989, JP-A-1-292092 and JP-A-62-267390, silica (SiO ₂ ) fine particles are coated on the surface of phosphor particles, and the adhesion of the phosphor is reduced. Are disclosed.

Further, as another measure for improving the adhesive force, a method of increasing the exposure sensitivity by ultraviolet rays has been adopted. This method involves increasing the amount of ammonium bichromate (ADC) or sodium bichromate (SDC), which becomes a photoresist added to the phosphor slurry, or adding a compound such as zinc oxide or zinc hydroxide to the phosphor. This is a method of increasing the exposure sensitivity of the phosphor slurry to ultraviolet rays by coating the particle surface. Then, since the exposure sensitivity of the phosphor slurry is increased, it has been expected that the slurry coating film can be effectively cured by exposure to a minimum amount of ultraviolet light, and the phosphor particles can be firmly attached to the adherend.

[0009]

The method of depositing silica particles by coating them on the surface of the phosphor particles is extremely effective in increasing the adhesion of the phosphor particles. However, if the coating amount is excessive,
Since the surface of the phosphor particles is activated, the phosphor remains in portions that should not be left behind in the adhered portion after washing, and defects such as color mixing and residues are likely to occur. However, there were problems that the color tone was lowered and high definition was not obtained.

On the other hand, in the method of increasing the ultraviolet exposure sensitivity, the curing of the coating film easily progresses beyond a predetermined region due to the improvement of the exposure sensitivity, and the size of the stripe-like or dot-like fluorescent film is enlarged, which is out of specification. Because it becomes easy to become
Similarly, there has been a problem that high color tone and high definition cannot be obtained.

In recent years, under the circumstances where the demand for high color tone and high definition has been further increased due to the spread of high-definition televisions and the like, the above-mentioned improvement in the adhesion of the phosphor particles has been achieved, and There is a need for a phosphor that does not cause problems such as poor color mixing or residue and enlargement of the phosphor film size. Originally, in a CRT manufacturing process for a cathode ray tube or the like, a stripe-like or dot-like phosphor film remains in a strong state with a high adhesive force in a predetermined pattern portion of a face plate, while the phosphor film remains in other portions. It is considered that the absence of particles at all is an essential requirement for achieving high color tone and high definition.

When the surface of the phosphor particles is coated with silica (SiO ₂ ) fine particles excessively or non-uniformly as described above, the adhesion of the phosphor film is increased, but defective residue is likely to occur. For this reason, a high level of production control has been required in which the amount of coating is strictly controlled to reduce residue defects.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a phosphor capable of reproducing a high-quality and high-definition image with little residue at a portion where a phosphor is applied to a cathode ray tube and an efficiency thereof. It is intended to provide a simple manufacturing method.

[0014]

Means for Solving the Problems In order to achieve the above object, the present inventors have made various compounds adhere to the surface of the phosphor particles, and the kind, particle size, and amount of the compounds are adjusted to the characteristics of the phosphor. The effects were compared by experiments. As a result, particularly when alumina particles of a predetermined particle size range were coated on the surface of the phosphor particles by a predetermined amount, defective residues could be significantly reduced. In addition, it was found that even when silica fine particles were adhered to the surface of the phosphor particles, a phosphor film with less residue defects and improved adhesion was obtained. The present invention has been completed based on the above findings.

That is, in the phosphor according to the present invention, alumina particles having an average particle diameter of 0.05 μm or more and 2.0 μm or less adhere to the surface of the phosphor particles mainly containing at least one of zinc sulfide and yttrium oxysulfide. The adhesion amount of the alumina particles is 0.05% with respect to the weight of the phosphor particles.
２．０2.0% by weight. Further, the average particle diameter of the alumina particles is preferably set to 0.2 μm or more and 1.2 μm or less. Further, it is preferable to further attach silica particles to the surface of the phosphor particles.

Further, according to the method for producing a phosphor according to the present invention, there is provided a method for producing a phosphor comprising alumina particles adhered to the surface of the phosphor particles containing at least one of zinc sulfide and yttrium oxysulfide as a main component. To prepare a phosphor dispersion by dispersing the phosphor in pure water, a step of adding an aqueous solution of zinc sulfate (ZnSO ₄ ) to the phosphor dispersion and stirring, and a step of adding alumina to the phosphor dispersion to which zinc sulfate is added. (Al ₂ O ₃ ) A step of adding and stirring the particle dispersion, and a step of adjusting the pH of the phosphor dispersion to 8.0 to 9.0 by adding ammonia water to the phosphor dispersion to which the alumina particles are added. A step of adhering alumina particles to the surface of the phosphor particles via zinc hydroxide, and filtering the dispersion of the phosphor particles to which the alumina particles are adhered. Drying / sieve Characterized in that it comprises the step of.

Here, the step of preparing the phosphor dispersion liquid in the above-mentioned production method is generally a step of putting the phosphor particles in a dry state into pure water and stirring them. Alternatively, dispersion processing by milling may be performed in advance. In the case where the phosphor particles have been subjected to some treatment in the previous step and the phosphor particles have been dispersed in pure water in advance, the dispersion can be used after stirring.

In the step of adding a zinc sulfate (ZnSO ₄ ) aqueous solution as a chemical solution to the phosphor dispersion liquid and stirring the mixture, zinc hydroxide for adhering Al ₂ O ₃ particles to the phosphor particle surface, which will be described later, is generated. This is a step of adding a raw material to be made. The above-mentioned chemical is preferably a solution in which zinc sulfate is dissolved in pure water, but other compounds can be used as long as they are raw materials capable of producing zinc hydroxide.

The step of adding the alumina (Al ₂ O ₃ ) particle dispersion to the phosphor dispersion and stirring the mixture is a step of adding alumina particles for increasing the adhesion of the phosphor to the adherend.

Next, in the step of adjusting the pH of the phosphor dispersion to 8.0 to 9.0 by adding aqueous ammonia to the phosphor dispersion, a predetermined amount of zinc hydroxide is precipitated. By stirring the phosphor dispersion with the precipitated zinc hydroxide,
Alumina particles can be attached to the surface of the phosphor particles via zinc hydroxide. If the pH value of the dispersion is out of the above range, the amount of zinc hydroxide deposited decreases, and it becomes difficult to secure a sufficient amount of alumina particles attached.

The phosphor according to the present invention is obtained by filtering the dispersion of the phosphor particles to which the alumina particles have adhered and drying and sieving the obtained cake.

In the phosphor according to the present invention, the amount and average particle size of the alumina particles adhered to the surface of the phosphor particles greatly affect the residue characteristics and adhesion of the phosphor. The amount of adhesion is in the range of 0.05 to 2.0% by weight based on the weight of the phosphor particles. When the amount of the alumina particles attached is less than 0.05% by weight, the effect of improving the residue properties is insufficient and remains at the conventional level. On the other hand, when the amount exceeds 0.05% by weight, the properties of the residue begin to improve. When the content exceeds 2.0% by weight, the amount of the residue increases. Therefore, the adhesion amount of the Al ₂ O ₃ particles is 0.05
To 2.0% by weight, more preferably 0.5 to 2.0% by weight.

When the average particle size of the alumina (Al ₂ O ₃ ) particles is less than 0.05 μm or more than 2.0 μm, the adhesive strength of the phosphor film decreases and the amount of the residue increases. Therefore, the average particle size of the alumina particles is in the range of 0.05 to 2.0 μm.

The reason why the residue characteristics of the phosphor obtained by the manufacturing method according to the present invention are improved is not necessarily clear, but it is considered to be based on the following mechanism. That is, the alumina particles adhered to the surface of the phosphor particles are dried and fixed to the surface of the phosphor particles in a strong bonding state. Here the alumina particles are electrically strong plus (+)
Therefore, the phosphor particles to which the alumina particles are fixed are also positively (+) charged. When the phosphor particles adhere to an adhered portion such as a glass panel, it is considered that the residue characteristics are improved due to a phenomenon in which the residue is reduced by repulsion from the positive charging on the glass panel.

The phosphor particles have a particle diameter of 0.06 to
By adhering fine silica (SiO ₂ ) particles of 0.3 μm, it is possible to improve the adhesion between the adhered portion such as a cathode ray tube panel and the phosphor particles, and to obtain a uniform and dense phosphor film. As a result, a high-definition cathode ray tube without color mixture can be formed.

According to the phosphor having the above-described structure, a predetermined amount of alumina particles having a predetermined fine particle diameter is adhered to the surface of the phosphor particles, so that the adhesion between the adherend and the phosphor particles can be increased. And a phosphor film with improved residue characteristics can be formed. Therefore, it is possible to provide a high-definition cathode ray tube with less increase in the size and color mixture of the phosphor film pattern.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be specifically described with reference to the following examples.

Example 1 200 g of zinc sulfide phosphor particles were sampled and uniformly dispersed in 500 ml of pure water to prepare a phosphor dispersion. Next, 20 cc of an aqueous solution of zinc sulfate was added to the phosphor dispersion and stirred for 30 minutes. Next, an average particle size of 0.3 μm
Was added so that the ratio of the alumina particles to the phosphor particles was 0.05% by weight, followed by stirring for 30 minutes. Thereafter, a diluted ammonia aqueous solution is added to the phosphor dispersion liquid, and p
The mixture was adjusted to H 8.0 and stirred for 1 hour. Thereafter, the phosphor dispersion liquid was filtered, and the obtained cake was dried and sieved to obtain Example 1.
Was prepared.

Example 2 200 g of zinc sulfide phosphor particles were sampled and uniformly dispersed in 500 ml of pure water to prepare a phosphor dispersion. Next, 20 cc of an aqueous solution of zinc sulfate was added to the phosphor dispersion and stirred for 30 minutes. Next, an average particle size of 0.3 μm
Alumina dispersion liquid in which alumina particles are dispersed is 0.5% by weight of alumina particles with respect to phosphor particle weight.
And stirred for 30 minutes. After a while
A diluted ammonia aqueous solution is added to the phosphor dispersion, and the pH is adjusted.
The mixture was adjusted to 8.5 and stirred for 1 hour. Thereafter, the phosphor dispersion liquid was filtered, and the obtained filter cake was dried and sieved to prepare a phosphor according to Example 2.

Example 3 200 g of zinc sulfide phosphor particles were sampled and uniformly dispersed in 500 ml of pure water to prepare a phosphor dispersion. Next, 20 cc of an aqueous solution of zinc sulfate was added to the phosphor dispersion and stirred for 30 minutes. Next, an average particle size of 0.3 μm
The alumina dispersion in which the alumina particles are dispersed was prepared by mixing the alumina particles with the phosphor particles at a weight ratio of 1.0% by weight.
And stirred for 30 minutes. After a while
A diluted ammonia aqueous solution is added to the phosphor dispersion, and the pH is adjusted.
The mixture was adjusted to 9.0 and stirred for 1 hour. Thereafter, the phosphor dispersion liquid was filtered, and the obtained cake was dried and sieved to prepare a phosphor according to Example 3.

Example 4 200 g of zinc sulfide phosphor particles were sampled and uniformly dispersed in 500 ml of pure water to prepare a phosphor dispersion. Next, 20 cc of an aqueous solution of zinc sulfate was added to the phosphor dispersion and stirred for 30 minutes. Next, an average particle size of 0.3 μm
The alumina dispersion in which the alumina particles are dispersed is prepared by mixing the alumina particles with the phosphor particles at a ratio of 2.0% by weight based on the weight of the phosphor particles.
And stirred for 30 minutes. After a while
A diluted ammonia aqueous solution is added to the phosphor dispersion, and the pH is adjusted.
The mixture was adjusted to 8.5 and stirred for 1 hour. Thereafter, the phosphor dispersion liquid was filtered, and the obtained filter cake was dried and sieved to prepare a phosphor according to Example 4.

Comparative Example 1 200 g of zinc sulfide phosphor particles were sampled and uniformly dispersed in 500 ml of pure water to prepare a phosphor dispersion. Next, 20 cc of an aqueous solution of zinc sulfate was added to the phosphor dispersion and stirred for 30 minutes. Next, an average particle size of 0.3 μm
Alumina dispersion liquid in which alumina particles were dispersed was prepared in such a manner that the ratio of alumina particles to the phosphor particles was 3.0% by weight.
And stirred for 30 minutes. After a while
A diluted ammonia aqueous solution is added to the phosphor dispersion, and the pH is adjusted.
The mixture was adjusted to 8.0 and stirred for 1 hour. Thereafter, the phosphor dispersion liquid was filtered, and the obtained cake was dried and sieved to prepare a phosphor according to Comparative Example 1.

Conventional Example Alumina (Al ₂ O ₃ ) particles were not attached, and the zinc sulfide phosphor particles prepared in Example 1 were used as they were to obtain a conventional phosphor.

For each of the phosphors of the conventional example, Examples 1 to 4 and Comparative Example 1, a phosphor slurry containing a photoresist made of PVA-ADC was prepared, and this slurry was applied to a face plate of a cathode ray tube. The number of residues remaining between the stripe-shaped phosphor films formed by fixing and irradiating the resulting phosphor screen on the face plate by irradiating ultraviolet rays with different exposure amounts is measured by a simple microscope (Shop Micro). And the results shown in Table 1 below were obtained. The number of residues is shown as a relative value (residue ratio) with reference value 1 when a phosphor of the conventional example to which Al ₂ O ₃ particles are not attached is used.

The relationship between the exposure amount and the stripe width corresponding to the adhesive force was measured, and the results shown in FIG. 1 were obtained.

[0036]

[Table 1]

As is clear from the results shown in Table 1 above,
It has been found that residue characteristics can be effectively improved by using phosphor particles having a predetermined amount of alumina particles having a predetermined average particle diameter adhered to the surfaces of the phosphor particles. In particular, Example 2
As is clear from to 4, the amount of deposition of Al ₂ O ₃ particles was confirmed that the effect of reducing the residual amount becomes conspicuous in the range of 0.50 to 2.00 wt%.

As is clear from the results shown in FIG. 1, the lower limit of the adhesive force (corresponding to the stripe width) corresponding to the change in the exposure amount of the phosphor according to each embodiment is 1.
It is in the range of 25 to 135, and this value means that the change in the adhesive force is small. That is, it was also confirmed that the adhesion of the phosphor film hardly changed due to the adhesion of the Al ₂ O ₃ particles.

Examples 5 to 8 and Comparative Example 2 In Example 3, alumina to be adhered (Al ₂ O ₃ )
The average particle size of each particle was 0.05 μm (Example 5),
0.50 μm (Example 6), 1.0 μm (Example 7),
Except for using 2.0 μm (Example 8) and 2.5 μm (Comparative Example 2), the processing was performed in the same manner as in Example 3 to obtain Example 5 respectively.
To 8 and Comparative Example 2 were prepared.

Each of the phosphors was converted into a slurry in the same manner as in Example 1, applied to a face plate of a cathode ray tube, exposed to ultraviolet rays, developed, and washed to form stripe-shaped phosphor films. The ratio of the number of residues remaining between the phosphor films was measured, and the results shown in Table 2 below were obtained. The relationship between the average particle size of the alumina particles and the adhesive force of the phosphor film (the ratio of the stripes remaining on the face plate) was measured, and the results shown in FIG. 2 were obtained.

[0041]

[Table 2]

As is clear from the results shown in Table 2 above,
It was found that the number of residues was reduced in the phosphor films of the respective examples in which the average particle size of the alumina (Al ₂ O ₃ ) particles to be attached was in the range of 0.05 to 2.00 μm. Further, as is clear from the results shown in FIG. 2, it was confirmed that in the above-mentioned range of the particle size of the alumina particles, the adhesion of the phosphor film did not decrease much.

Examples 9 to 13 In Example 3, 1.0% by weight based on the weight of phosphor particles
Further, silica particles having an average particle diameter of 0.1 μm are further added to the phosphor particles having the alumina particles of 0.1 wt%, respectively.
(Example 9), 0.5% by weight (Example 10), 1.0% by weight (Example 11), 2.0% by weight (Example 12) and 3% by weight (Example 13) Example 3 except for the points
The phosphors according to Examples 9 to 13 were prepared in the same manner as described above.

Using each of the prepared phosphors, a striped phosphor film was formed on the face plate of a cathode ray tube in the same manner as in Example 1, and the ratio of the number of residues remaining between the phosphor films was measured. The results shown in Table 3 below were obtained. In addition, each residue ratio was relatively displayed as the reference value 1 in Example 3 where silica particles were not attached.

[0045]

[Table 3]

As is clear from the results shown in Table 3 above,
It has been found that residue characteristics can be further improved by attaching silica (SiO ₂ ) particles to the surfaces of the phosphor particles in addition to the alumina particles.

As described above, according to the phosphor according to the present embodiment, it is possible to maintain the adhesion of the phosphor film at a high level and significantly improve the residue characteristics as compared with the phosphor produced by the conventional method. It became. Further, since there is little problem such as an increase in the size of the phosphor film, a cathode ray tube having a good color tone and capable of reproducing a high-definition image can be obtained.

[0048]

As described above, according to the phosphor of the present invention, a predetermined amount of alumina particles having a predetermined fine particle diameter is adhered to the surface of the phosphor particles. It is possible to form a phosphor film with improved residue characteristics as well as improved adhesion to the phosphor. Therefore, it is possible to provide a high-definition cathode ray tube with less increase in the size and color mixture of the phosphor film pattern.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between an exposure amount and an adhesive force (stripe width).

FIG. 2 is a graph showing the relationship between the average particle size of alumina particles and the adhesion of a phosphor film.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Katsuyuki Aoki 1-9-2, Hara-cho, Fukaya-shi, Saitama Prefecture Inside the Toshiba Fukaya Electronics Factory (72) Inventor Toshifumi Takehara 7-Nisshincho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture 1. Toshiba Electronic Engineering Corporation

Claims (4)

[Claims] An alumina particle having an average particle diameter of 0.05 μm or more and 2.0 μm or less adheres to the surface of a phosphor particle containing at least one of zinc sulfide and yttrium oxysulfide as a main component. A phosphor characterized in that the amount of adhesion is 0.05 to 2.0% by weight based on the weight of the phosphor particles. 2. The average particle diameter of alumina particles is 0.2 μm.
2. The phosphor according to claim 1, wherein the thickness is not less than 1.2 μm. 3. The phosphor according to claim 1, wherein silica particles are further attached to the surface of the phosphor particles. 4. A method for producing a phosphor in which alumina particles are adhered to the surface of a phosphor particle containing at least one of zinc sulfide and yttrium oxysulfide as a main component, wherein the phosphor particles are dispersed in pure water. A step of preparing a dispersion, a step of adding a zinc sulfate (ZnSO ₄ ) aqueous solution to the phosphor dispersion and stirring, and a step of adding an alumina (Al ₂ O ₃ ) particle dispersion to the phosphor dispersion to which zinc sulfate is added. Adding and stirring, and adding ammonia water to the phosphor dispersion liquid to which the alumina particles have been added to adjust the pH of the phosphor dispersion liquid to 8.0 to 9.
Adjusting the temperature to 0 and precipitating the zinc hydroxide, stirring at the same time, and attaching the alumina particles to the surface of the phosphor particles via zinc hydroxide, and filtering the dispersion liquid of the phosphor particles with the alumina particles attached. Drying and sieving the filter cake.