JPH0662942B2 - Fluorescent substance for cathode ray tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a phosphor for a cathode ray tube.

(Prior Art) Generally, a method of forming a fluorescent film of a cathode ray tube is generally carried out by dispersing a phosphor in an aqueous solution containing polyvinyl alcohol (PVA), ammonium dichromate and a surfactant, coating the glass with a phosphor, Form a film. Then, through the shadow mask, ultraviolet rays are irradiated to cure the PVA in the irradiated portion, and the fluorescent film other than the portion cured by development is removed,
Form stripes or dots of phosphor. By performing this operation three times, blue, green, and red fluorescent films are formed, respectively.

What is required of the phosphor in this coating method is that (1) a fluorescent film having a dense stripe or dot is formed. That is, a fluorescent film with few holes should be obtained.

(2) Do not mix one light emitting component with another light emitting component phosphor. That is, no color mixing should occur.

(3) Good attachment force. That is, the exposure sensitivity is good.

There are conditions such as. In order to meet these requirements, it is necessary that the phosphor particles are well dispersed in the slurry without aggregation.

Recently, a color television having a high quality phosphor film is required, and therefore, the demands on the above matters are further demanded for phosphors.

In order to satisfy these characteristics currently required, various improvements and developments have been made on the surface treatment of phosphors.

For example, JP-B-46-35425 discloses a method of coating the surface of a phosphor with silica of 0.01 to 0.02 μm in an amount of 0.1 to 5.0 weight percent.

(Problems to be Solved by the Invention) Although the film disclosed in Japanese Patent Publication No. 46-35425 provides a dense film to some extent, the emission brightness is still insufficient in view of the high demand level of the market. When the phosphor slurry is exposed and developed to form the blue, green, and red light-emitting phosphor films in stripes, the green light-emitting phosphor and the red light-emitting phosphor that will be formed in a later step are attached to the blue light-emitting phosphor film. The problem of so-called color mixing still remains.

Therefore, the present invention has been made in order to solve the above-mentioned drawbacks, and an object of the present invention is to provide a phosphor for obtaining a phosphor film having high emission brightness and free from color mixture.

[Structure of Invention]

(Means for Solving Problems) The present invention relates to a phosphor having silica particles coated on the surface thereof,
The average particle size of the silica particles is in the range of 0.0003 to 0.001 μm, and the amount of the silica particles attached is 0.005 to 0.09 of the host phosphor.
It is a phosphor for a cathode ray tube, characterized in that it is within the range of weight%.

It is practically impossible to form silica particles having an average particle size of less than 0.0003 μm.

If the average particle size exceeds 0.001 μm, the required silica adhesion increases, and therefore the emission brightness decreases. Furthermore, mixed color development remains.

The most preferable range is 0.0003 to 0.0008 μm.

If the amount of the silica particles attached is less than 0.005% by weight of the base phosphor, the dispersibility of the phosphor will be poor and the denseness of the film will be insufficient. If it exceeds 0.1% by weight, the adhesion of the cathode ray tube to the glass panel will decrease. As a result, the edge of the stripe film is peeled off during development, resulting in a so-called poorly cut fluorescent film (a state where the edge meanders), which causes color mixing. The most preferred range is 0.01 to 0.07% by weight.

The phosphor applied in the present invention is silver, chloro-activated zinc sulfide phosphor (ZnS / Ag, Cl), silver, aluminum-activated zinc sulfide phosphor (ZnS / Ag, Al), cobalt blue pigment or ultramarine blue pigment coating. ZnS / Ag, Cl phosphor, cobalt blue pigment or ultramarine blue pigment coated ZnS / Ag, Al phosphor, blue light emitting phosphor, copper, aluminum activated zinc sulfide phosphor (ZnS / Cu, A
l), gold, copper, aluminum activated zinc sulfide phosphor (ZnS / C
u, Au, Al) Copper- and aluminum-activated zinc-cadmium sulfide phosphor ((Zn, Cd) S / Cu, Al) green-emitting phosphor, europium-activated yttrium oxysulfide phosphor (Y ₂ O ₂
S / Eu), europium-activated yttrium oxide phosphor (Y ₂
O ₃ / Eu), a red light emitting phosphor selected from red iron oxide coated yttrium oxysulfide phosphor and the like.

The phosphor of the present invention is manufactured by the method described below.

Put the phosphor for color picture tube in pure water and stir it sufficiently. Next, add an appropriate amount of a solution of SiO ₂ dissolved in an alkaline solution of choline (hereinafter referred to as choline silica solution) to the stirring liquid,
Thereafter, an appropriate amount of any one of nitrates, sulfates and chlorides such as zinc nitrate, zinc sulfate, barium nitrate, aluminum nitrate and zinc chloride is added to the solution containing the choline silica solution to precipitate silica. The deposited ultrafine particles of silica are adsorbed on the surface of the phosphor. Then, this phosphor is washed several times with pure water to remove residual ions and then dried. The target phosphor is obtained by sieving the lump-shaped phosphor obtained after drying through a sieve. As described above, the present inventors have found that the use of the choline silica solution causes the ultrafine particles of silica to be precipitated by the reaction.

Here, in the above-mentioned production method of the present invention, after the choline silica solution was added, either one of the sulfates and nitrates was added, but conversely, one of the sulfates and nitrates was added first. In addition, choline silica solution may be added next.

In any case, in order to stabilize and control the precipitation amount of ultrafine silica particles, after adding choline silica solution and sulfate or nitrate, etc., adjust the pH to 7.5-9.0 with an alkaline substance such as aqueous ammonia. You may.

The sedimentation volume is shown in FIG. 1 to show the dispersibility. This sedimentation volume value is generally obtained by preparing a slurry solution of a phosphor sample using polyvinyl alcohol, ammonium dichromate and a surfactant, putting a fixed amount in a sedimentation tube, and allowing it to sediment for 20 hours, and reading the volume. The larger the sedimentation volume value, the worse the dispersibility.

The surface treatment of the present invention can also be applied to a pigment-coated phosphor that uses an organic resin as an adhesive.

(Function) According to the present invention, both the emission brightness and the adhesive force of the fluorescent film are improved as compared with the case of using the conventional silica particle-coated phosphor.
A fluorescent film with little color mixing can be obtained.

(Example) Hereinafter, the present invention will be described in detail with reference to Examples.

(Example 1) Copper, aluminum activated zinc sulfide (ZnS / Cu, Al) phosphor 1k
Disperse g in 8 of pure water. To this dispersion, 35 cc of 0.4 mol zinc sulfate solution was added and stirred for 15 minutes, then 10.5 cc of choline silica solution (Si content 12%) was added, and then stirred for 30 minutes.

After stirring, the phosphor is allowed to settle, and the supernatant is removed by decantation. Next, the phosphor is washed with 10 pure water four times, filtered, dried at a temperature of around 130 ° C., and sieved with a 300-mesh sieve to remove the surface of the ZnS / Cu, Al phosphor to 0.0
A phosphor coated with 6 weight percent of 0.0005 μm ultrafine silica is obtained. The particle size of the ultrafine silica particles was measured with an electron microscope photograph taken by magnifying 100,000 times with an ALPHA-10 type electron microscope (manufactured by Akashi Seisakusho).

The phosphor obtained by the above is well dispersed in a slurry solution, and by using this slurry in a usual method, it is applied on a panel for a cathode ray tube, and the formed film is a highly dense phosphor film. Therefore, good emission brightness was obtained.

Table 1 shows various properties of the fluorescent film using the phosphor of the present invention, such as adhesion, breakage and emission brightness. The numbers in parentheses are various characteristics of the phosphor film using the conventional phosphor coated with silica particles having an average particle of 0.02 μm and a coating amount of 0.2% by weight with respect to the base phosphor.

The adhesive force is measured as follows. First, a phosphor slurry is applied to a panel and exposed so that the stripe width becomes 80 μm, which is narrower than usual.

Next, when the developing solution is poured onto the panel surface, the stripe width is narrow, so that the stripe film having a small adhesive force is removed by the developing solution. At this time, the amount of the striped fluorescent film remaining on the panel surface was expressed as a relative value (%) with respect to the design value, and the value was taken as the adhesive force.

The breakage indicates the maximum and minimum of the meandering amount of the edge when a normal striped fluorescent film (200 μm) is formed by a numeral.

The emission brightness is the relative brightness of the fluorescent film.

As is clear from Table 1, the phosphor film of the phosphor of the present invention has improved adhesiveness and emission brightness as compared with the phosphor film of the conventional phosphor. In addition, since the film can be cut off, color mixing does not occur.

(Example 2) 1 kg of gold, copper, and aluminum activated zinc sulfide (ZnS / Cu, Au, Al) phosphor is dispersed in 8 pure water. To this dispersion, 14.2 cc of choline silica solution (Si content 12%) was added and stirred for 20 minutes, then added to 48 cc of 0.4 mol zinc sulfate solution, and then stirred for 20 minutes.

After stirring, the phosphor is allowed to settle and the supernatant is removed by decantation. Next, the phosphor is washed 4 times with 10 pure water, filtered, dried at a temperature of around 130 ° C, and sieved with a 300 mesh screen to remove the surface of the ZnS / Cu, Au, Al phosphor.
A phosphor coated with 0.09 weight percent 0.0005 μm ultrafine silica is obtained.

Table 1 shows various characteristics when the phosphor obtained as described above is used as a phosphor film of a cathode ray tube.

(Example 3) Silver and chloro activated zinc sulfide (ZnS / Ag, Cl) phosphor 1 kg 8
Disperse in pure water. To this dispersion, 7 cc of 0.4 mol zinc sulfate solution was added and stirred for 15 minutes, then 2.1 cc of choline silica solution (Si content 12%) was added, and then stirred for 30 minutes.

After stirring, the phosphor is allowed to settle, and the supernatant is removed by decantation. Next, the phosphor is washed 4 times with 10 pure water, filtered, dried at a temperature of around 130 ° C, and sieved with a 300 mesh screen to remove the ZnS / Ag, Cl phosphor surface by 0.013.
A phosphor coated with a weight percent of 0.0008 μm ultrafine silica is obtained.

The phosphor obtained as described above is well dispersed in a slurry solution, and a normal method using this slurry is applied to a panel for a cathode ray tube to form a film, which is a highly dense phosphor film. Therefore, good emission brightness was obtained. The results are shown in Table 1.

Example 4 1 kg of a cobalt blue pigment-coated ZnS / Ag, Cl phosphor using an acrylic emulsion resin as an adhesive is dispersed in 8 pure water. To this dispersion, 3.5 cc of 0.4 mol zinc nitrate solution was added and stirred for 15 minutes, and then choline silica solution (Si content
(12%) 1.1 cc, and then stir for 30 minutes.

After stirring, the phosphor is allowed to settle, and the supernatant is removed by decantation. Next, the phosphor is washed with 10 parts of pure water four times, filtered, dried at a temperature of around 130 ° C, and sieved with a 300-mesh sieve to remove cobalt blue pigment-coated ZnS / A.
0.006 μm of 0.006 weight percent on the surface of g, Cl phosphor
A phosphor coated with the ultrafine silica particles of is obtained.

Table 1 shows various characteristics of the phosphor film using this phosphor.

Example 5 1 kg of europium-activated yttrium oxide phosphor is dispersed in 8 pure water. To this dispersion, 21 cc of 0.4 mol zinc sulfate solution was added and stirred for 15 minutes, then 6.3 cc of choline silica solution (Si content 12%) was added, and then stirred for 30 minutes.

After stirring, the phosphor is allowed to settle, and the supernatant is removed by decantation. Next, the phosphor is washed with 10 pure water four times, filtered, dried at a temperature of around 130 ° C, and sieved with a 300 mesh screen to remove the surface of the Y ₂ O ₂ S / Eu phosphor. A phosphor coated with 0.04 weight percent of 0.0004 μm ultrafine silica is obtained.

The phosphor obtained by the above is well dispersed in a slurry solution, and by using this slurry in a usual method, it is applied on a panel for a cathode ray tube, and the formed film is a highly dense phosphor film. Therefore, good emission brightness was obtained. The results are shown in Table 1.

Example 6 1 kg of red iron oxide-coated Y ₂ O ₂ S / Eu phosphor using an acrylic emulsion resin as an adhesive is dispersed in 8 pure water. Add 14cc of 0.4M zinc sulfate solution to this dispersion and add 1
Stir for 5 minutes, then choline silica solution (Si content 12%) 4.2
Add cc, then adjust to pH 8.2 with dilute aqueous ammonia and stir for 30 minutes.

After stirring, the phosphor is allowed to settle, and the supernatant is removed by decantation. Next, the phosphor is washed with 10 parts of pure water four times, filtered, dried at a temperature of around 130 ° C., and sieved with a 300 mesh sieve to remove the red iron oxide pigment Y ₂ O ₂ S / Eu phosphor. As a result, a phosphor in which 0.025 weight percent of 0.0005 μm ultrafine silica particles is coated on the surface of

Table 1 shows various characteristics of the phosphor film using this phosphor.

(Example 7) 1 kg of red iron oxide-coated Y ₂ O ₂ S / Eu phosphor using an acrylic emulsion resin as an adhesive is dispersed in 8 pure water. 4.2cc of choline silica liquid (Si content 12%)
And stir for 20 minutes. Next, after adding 14 cc of 0.4 mol aluminum nitrate solution and stirring for 10 minutes, the pH is adjusted to 7.5 with diluted ammonia water, and the mixture is stirred for 30 minutes.

After stirring, the phosphor is allowed to settle, and the supernatant is removed by decantation. Next, the phosphor is washed with 10 pure water four times, filtered, dried at a temperature of around 130 ° C., and sieved with a 300 mesh sieve to remove red iron oxide Y ₂ O ₂ S / Eu fluorescence. A phosphor is obtained in which the surface of the body is coated with 0.022 weight percent of 0.0004 μm ultrafine silica.

Table 1 shows various characteristics of the phosphor film using this phosphor.

Table 2 summarizes the above description as a general tendency.

[Advantages of the Invention] According to the phosphor of the present invention, when applied to a cathode ray tube, it is possible to realize a phosphor film having high emission brightness, strong adhesion, and little color mixture.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the silica particle coating amount of the silica particle-covered Y ₂ O ₂ S: Eu phosphor and the sedimentation volume in the phosphor slurry.

Claims (1)

[Claims] 1. A phosphor having silica particles coated on the surface thereof, wherein the average particle diameter of the silica particles is in the range of 0.0003 to 0.001 μm, and the amount of silica particles attached is 0.005 to 0.005 of that of the host phosphor.
A phosphor for a cathode ray tube, which is in the range of 0.09% by weight.