JPS61136578A - Red light-emitting phosphor - Google Patents

Abstract

PURPOSE:The titled phosphor with excellent dispersibility in a slurry and giving a high-density phosphor film with few pores, causing no color migration, which is obtd. by coating the surface of a (red oxide pigment-coated) Eu-activated yttrium oxysulfide phosphor with ZnS. CONSTITUTION:An Eu-activated yttrium oxysulfide phosphor or a red oxide pigment-coated Eu-activated yttrium oxysulfide phosphor in which an org. resin is used as a binder is dispersed in deionized water. A water-soluble sulfide such as ammonium polysulfide and a water-soluble zinc salt such as ZnSO4 or ZnCl2 are added to the resultant dispersion and reacted with each other in water to coat the surface of the phosphor with the precipitate of ZnS. Then the phosphor is washed several times with deionized water, filtered and dried at about 130 deg.C to obtain the titled phosphor having a surface coated with 0.003-0.2wt%, based on the phosphor, ZnS.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a europium-activated yttrium oxysulfide phosphor that emits red light.

[Technical background of the invention and its problems]

A fluorescent film is formed on the inner surface of a panel of a color cathode ray tube, such as a color picture tube, by a conventional method. That is, the phosphor is dispersed in an aqueous solution containing polyvinyl alcohol, ammonium dichromate, and a surfactant.
Apply this to the inner surface of the glass panel to form a fluorescent film.
Next, the fluorescent film is irradiated with ultraviolet rays through the holes in the shadow mask attached to a predetermined position on the panel, and the polyvinyl alcohol in the irradiated area is cured.]! J! The fluorescent film other than the cured portions is removed according to the image to form stripes or dots of fluorescent material. By performing these operations three times, blue, green, and red phosphor films are formed, respectively, and a predetermined phosphor screen is obtained.

In such a coating method, the following requirements are required for the phosphor. ■Dense stripes or dots are formed. In other words, a fluorescent film with fewer pores can be obtained. (2) The phosphor of one luminescent component should not mix with the phosphor of another luminescent component, that is, color mixture should not occur.

In order to meet these requirements, there must be no aggregation of phosphor particles in the slurry, ie, the phosphor dispersion.

It is necessary to be well dispersed. In particular, the red phosphor film of a Galar picture tube is required to have good dispersibility, since the phosphor film is formed for the third color when forming a phosphor screen.

In other words, when forming a fluorescent film on the panel for the third color,
The blue fluorescent layer, green fluorescent layer, which are formed by coating first,
Furthermore, due to the presence of the black layer, the coated surface is highly uneven, and as a result, with red phosphors that have poor dispersibility, the slurry spreads poorly during coating, and the film surface becomes porous, resulting in poor density. This has the drawback that only a phosphor film with a low level of phosphor can be obtained, and furthermore, there is a problem that color mixing is likely to occur in which the red phosphor remains on the blue or green phosphor layer. Therefore, in the phosphor screen formed in this way, the luminance of one emission decreases and the color purity of one image deteriorates.

Therefore, there has been a demand for a phosphor for color picture tubes, especially a red phosphor, which has good dispersibility and does not cause the above-mentioned problems.

[Purpose of the invention]

The present invention was made in response to the above-mentioned needs, and an object of the present invention is to provide a red-emitting phosphor with excellent dispersibility for use in color cathode ray tubes.

[Summary of the invention]

The phosphor of the present invention is produced by coating zinc sulfide on the surface of a europium-activated yttrium oxysulfide phosphor or a red iron pigment-coated europium-activated yttrium oxysulfide phosphor using an organic resin as a binder. This method has the excellent effect of forming a dense phosphor screen for color cathode ray tubes that does not cause color mixture, and improving luminance.

To obtain the europium-activated yttrium oxysulfide phosphor of the present invention, the phosphor is dispersed in deionized water, and a water-soluble sulfide, such as ammonium polysulfide, is added thereto, followed by a water-soluble zinc salt.

For example, zinc sulfate or zinc chloride is added, the sulfide and zinc ions are reacted in water, and a precipitate of zinc sulfide is attached to the surface of the phosphor. After washing with ionized water several times to which zinc sulfide is attached, it is filtered and dried at about 130° C. to obtain a desired phosphor.

The surface treatment amount of zinc sulfide is 0 for the coated phosphor.
．． If the amount is less than 0.03% by weight, the dispersibility of the phosphor is poor and a satisfactory phosphor film cannot be obtained. Also, 0.2
When the amount is more than '% by weight, the luminance of the light emitted by the phosphor decreases and the dispersibility tends to deteriorate, making it impossible to obtain a fluorescent film with good characteristics. In other words, the surface coating amount of zinc sulfide is 0.0
The range is preferably from 0.03% by weight to 0.2% by weight, and more preferably from 0.01% by weight to 0.1% by weight.

[Embodiments of the invention]

EXAMPLE 1 A dose of europium-activated yttrium oxysulfide phosphor is dispersed in an illumination of deionized water. To this dispersion, add commercially available special grade ammonium polysulfide, liquid 0.8 c, c, and mix 15
Stir for a further 0.4 molar zinc sulfate solution 4c, c,
Add and stir for 20 minutes. After stirring, the light body is allowed to settle, and the supernatant liquid is removed by decantation.

The phosphor is then washed five times with 10Q deionized water, filtered, dried at a temperature of about 130° C., and sieved using a 300-mesh sieve. In this way, a phosphor is obtained in which the surface of the europium-activated yttrium oxysulfide phosphor is coated with 0.0035% by weight of zinc sulfide.

The phosphor obtained in this way has good dispersion in the slurry, so the phosphor film formed by applying this phosphor slurry to the inner surface of the panel of a color picture tube using the usual method has a high density. It becomes a good product with few high holes, and
No color mixing occurs. Regarding the luminance, assuming that the luminance from the phosphor not coated with zinc sulfide is 100%,
It was 102%, indicating an improvement in characteristics.

Example 2 A europium-activated yttrium oxysulfide phosphor 1- is dispersed in deionized water 10Q. Commercially available special grade ammonium polysulfide solution 3c and c are added to this dispersion and stirred for 20 minutes. Furthermore, 0.4M zinc sulfate solution 15c, c was added and stirred for 20 minutes. After stirring, the light body is allowed to settle, and the supernatant liquid is removed by decantation. The phosphor is then washed five times with IOQ deionized water, filtered, dried at a temperature of about 130° C., and sieved using a 300 mesh sieve. In this way, a phosphor is obtained in which the surface of the europium-activated yttrium oxysulfide phosphor is coated with 0.027% by weight of zinc sulfide.

The phosphor thus obtained has good dispersion in the slurry, and the phosphor slurry is spread on the inner surface of the panel of a color picture tube in the usual manner to form a phosphor film.
It is highly dense and has few pores, and does not cause color mixing.

Compared to phosphors that do not coat the surface with zinc sulfide,
The luminance was also good at 105%, indicating that the characteristics were improved.

Example 3 Disperse europium-activated yttrium oxysulfide phosphor 1 in deionized water 1 (IQ). Add commercially available special grade ammonium polysulfide solution 10c, c to this dispersion and stir for 20 minutes. Then 0.4 molar zinc sulfate solution 50c, c
. and stir for 20 minutes. After stirring, the light body is allowed to settle, and the supernatant liquid is removed by decantation.

The phosphor was then washed five times with 10Q deionized water, filtered, and dried at a temperature of about 130°C.

Sieve with 300 mesh. In this way, a phosphor is obtained in which the surface of the europium-activated yttrium oxysulfide phosphor is coated with 0.619% by weight of zinc sulfide.

The phosphor obtained in this way has good dispersion in the slurry, and the phosphor film formed by applying this phosphor slurry to the inner surface of the panel of a color picture tube using the usual method has a high density. The luminance was improved by 103% compared to the phosphor whose surface was not coated with zinc sulfide, and the characteristics were improved.

Example 4 A europium-activated yttrium oxysulfide phosphor 1- is dispersed in deionized water 11. To this was added 20 c, c of a 5% red iron pigment dispersion well dispersed into particles, and stirred well. 6 Then, 1 c, c of a 45% Agryl emulsion solution was added and stirred well. Add dilute sulfuric acid to adjust the pH to 3, and stir for 30 minutes. After stirring, transfer to a ball mill pot and stir for 20 minutes.Then, transfer the phosphor to a stirring tank and add deionized water to bring the total amount to 121. Further, adjust the pH to 7-8 with dilute ammonia water.
After 6 stirrings, the phosphor was washed 5 times with deionized water.

Next, deionized water is added to bring the total volume to 10Q, and while stirring, commercially available special grade ammonium polysulfide liquids 3c and 3c are added, and the mixture is stirred for 20 minutes. Then 0.4 molar zinc sulfate solution 15c,c is added and stirred for 20 minutes. After stirring, the light body is allowed to settle, and the supernatant liquid is removed by decantation. The phosphor was then washed five times with IOA deionized water, filtered, dried at a temperature of about 130°C, and dried at a temperature of 300°C.
Sieve through mesh. In this way, the surface of the europium-activated yttrium oxysulfide phosphor coated with red iron pigment was reduced to zero.
．． A phosphor coated with 0.027% by weight of zinc sulfide is obtained.

The phosphor obtained in this way has good dispersion in the slurry, and the phosphor film formed by applying this phosphor slurry to the inner surface of the panel of a color picture tube using the usual method is
It has a high density with less porosity, and the zero emission brightness, which does not cause color mixture, is 104% higher than that of a europium-activated yttrium oxysulfide phosphor coated with a red iron pigment that is not coated with zinc sulfide. It has improved and its characteristics have improved.

Example 5 In the same manner as in Example 4, deionized water was added to 1 kg of europium-activated yttrium oxysulfide phosphor whose surface was coated with red iron pigment to make the total amount 1OQ.

While stirring, commercially available special grade ammonium polysulfide liquid 4c, c
, and stir for 10 minutes.

Next, a well-dispersed lO% silica dispersion 3c, c is added and stirred for 10 minutes. Then 0.4M zinc sulfate solution 20c,c is added and stirred for 20 minutes. After stirring, the light body is allowed to settle, and the supernatant liquid is removed by decantation. The phosphor was then diluted with 1012 ml of deionized water.
After washing twice with water, filtering and drying at a temperature of about 130°C,
Sieve with 300 mesh. In this way, a phosphor is obtained in which the surface of the red iron pigment-coated europium-activated yttrium oxysulfide phosphor is coated with 0.02% by weight of silica and coated with 0.02% by weight of zinc sulfide of O,OS.

The phosphor thus obtained has good dispersion in the slurry, and the phosphor slurry is applied to the inner surface of the panel of a color picture tube using the usual method. It becomes a good product with high density and little gap, and also causes color mixing. Not at all.

Compared to phosphors that do not coat the surface with zinc sulfide,
The luminance was also good at 106%, indicating that the characteristics were improved.

〔Effect of the invention〕

As described above, the red light-emitting phosphor of the present invention has zinc sulfide coated on the surface of the europium-activated yttrium oxysulfide phosphor, so it has excellent dispersion in the slurry, and therefore can be coated on the inner surface of the panel. The resulting polymeric film was highly dense, had few pores, and did not cause color mixture, and the luminance of color cathode ray tubes equipped with such a phosphor screen was further improved. . As described above, the red-emitting phosphor of the present invention is extremely useful industrially.

Claims (2)

[Claims] (1) A red-emitting phosphor characterized in that the surface of a europium-activated yttrium oxysulfide phosphor or a red iron pigment-coated europium-activated yttrium oxysulfide phosphor is coated with zinc sulfide. (2) Zinc sulfide coating amount is 0 with respect to the coated phosphor.
．． 2. The red-emitting phosphor according to claim 1, characterized in that the content is in the range of 0.003% to 0.2% by weight.