JPS603356B2 - Pigment-coated phosphor and method for producing the same - Google Patents

Description

[Detailed description of the invention] The present invention relates to a pigment-coated crab phosphor and a method for producing the same.

Conventional color televisions are bright, and in order to improve the contrast of the screen under outside light, various measures have been taken to reduce the reflection of light on the front surface of the cathode ray tube. Among these ideas, a color cathode ray tube equipped with a red light-emitting crab light body coated with a red pigment has been proposed.

A color cathode ray tube having such a structure can reduce the reflection of color components other than red in external light, and is therefore considered to be quite effective in reducing the reflection of external light. In color cathode ray tubes equipped with pigment-coated light bodies, the selection of pigments is important because the degree of contrast strongly depends on the spectral reflectance of the pigments.

In addition to the above spectral reflectance, the pigments used in cathode ray tubes must have the following characteristics: In addition to the above spectral reflectance, they must not contain any harmful substances (does not contain cadmium, bell, mercury, etc.). It is not water soluble because it is applied by suspending it in (slurry), and it is heat resistant.In other words, after making a slurry of crab light and applying it to the glass panel,
Since the polyvinyl alcohol in the slurry is burned away, it is necessary that the baking process does not cause melting, deterioration, or discoloration. However, among red pigments, the substance that shows a bright red color when exposed to natural light is sulfoselenide cadmium Cd (
SSe), etc. are known, but they cannot be used in cathode ray tubes because they are harmful substances.

The above-mentioned cadmium sulfoselenide has excellent spectral reflectance and is used in some cathode ray tubes, but it discolors during the baking process and has problems in terms of heat resistance.
For this reason, pengara (iron oxide Fe2Q) is used as a red pigment, but it is insufficient in terms of spectral reflectance, has a bright red body color, is water-insoluble, and is a heat-resistant and non-toxic material. The development of superior pigments has been desired. The present inventors have discovered indium sulfide (
ln2S3).

Although this material is satisfactory in terms of spectral reflectance and water insolubility, it is slightly oxidized and discolored during the baking process, and has some problems in terms of heat resistance. That is, this pigment-coated crab light material is exposed to the baking process (temperature 4.
00 to 450 qo), it has a drawback that the color starts to change from red to yellow. An object of the present invention is to obtain a red light-emitting crab phosphor coated with a red pigment based on indium sulfide and having excellent heat resistance.

That is, the pigment according to the present invention is composed of alkali sulfate and indium sulfide and has the general formula
．． It is obtained by heat-treating (400 to 450°C) a composite compound of alkali sulfide and indium sulfide shown in 5).

Accordingly, the present invention provides a europium-activated rare frame halo coated with the above pigment and a method for producing the same.

The present invention will be explained in detail below. Generally, color cathode ray tubes are subjected to baking treatment (400 to 450 qo) to treat organic matter after forming the screen, but it is necessary that the fin photoresists on the screen do not have an adverse milk effect at this temperature.

As mentioned above, the present inventors have developed indium sulfide as a pigment suitable for red pigment-coated red light emitters, but the present invention has completed a pigment consisting of alkali sulfate and indium sulfide as a pigment having more heat resistance.

This pigment has the general formula XA2S・yin2 S3 (however, A
was confirmed to be obtained by heating an alkali metal, a composite compound of alkali sulfide and indium sulfide represented by 0.1≦×noy≦1.5).

The above composite compound exhibits a color such as yellow with a shorter wavelength than red, but when this composite compound is formed into a screen and then subjected to the aging process (400 to 450 qo) of the cathode ray tube, alkali sulfate and indium sulfide are formed and the body color appears red. I found it. The pigment before aging can be obtained by, for example, reacting an indium compound aqueous solution with an alkali sulfide aqueous solution under certain conditions.
3 (However, A is alkali IJ metal, 0.1≦x/y≦1.5
) is indicated for the following reasons.

{1) As a result of X-ray diffraction, it has a pattern different from that of ln2S3.

'21 As a result of wet chemical analysis, the molar ratio of ln and S is 2.
: Contains more S than 3, and also contains alkali IJ metal.

It is believed that the following chemical reaction occurs in XA2S.yin23 by baking in air at 400 to 600 CO, based on the following experimental facts.

×A2S. yl-S312〇21XA2S○40yl-
S2. ．． ．． ．． ．． ．． ．． ．． ．． {1) As a result of X-ray diffraction, both ln2S3 and A2S04 patterns are observed in the material after baking.

As a result, in the above reaction formula, alkali metal sulfide A2
It is inferred that S04 densely coats the surface of one pile S3 and prevents oxidation of ln2S3 during the baking process, which was also supported by the following experiment. In other words, thoroughly wash the material after baking to make it water-removable A2S0.
The color of the product from which No. 4 was removed is considerably discolored, whereas that of the product that is not washed with water remains unchanged by the rebaking process.

As made clear in the above explanation, the feature of the present invention is that a composite compound of a pigment and a substance that is more easily oxidized than the pigment is synthesized, and after baking, the oxide of the substance that is more easily oxidized than the pigment becomes the pigment. The surface of the pigment is densely coated to prevent oxidation of the pigment and improve heat resistance.

FIGS. 1 and 2 show the spectral reflectance of a pigment-coated red light-emitting crab phosphor (europium-activated yttrium oxysulfide).

In both figures, the axis shows the wavelength (nm) and the vertical axis shows the spectral reflectance. Figure 1 shows the baking process. Figure 2 shows the baking process (50
0° C. for 1 hour). In the figure, the line A-A is the crab light body not coated with pigment, and the line B-B is the ×Abu・yi according to the present invention.
n2S3 coated crab light body [After baking, it is (ln2S3 ten S04) coated crab light body], line C-C is pengara coated crab light body of secondary column, line D-D is conventional cadmium sulfoselenide coated crab light body shows. As is clear from Figure 2, line B in the figure
The pigment according to the invention indicated by -B is the most excellent.

In other words, it can be seen that the crab phosphor of the present invention has a generally high spectral reflectance above the 60 mark, and a generally low spectral reflectance below the 60 mark, resulting in a marked improvement in contrast against external light. Table 1 shows the temperature at which discoloration begins (heat-resistant temperature) when various red pigment coated crab phosphors are applied to a cathode ray tube panel and baked, and the color change after baking at 500° C. for 1 hour.

In Table 1, the pigments according to the present invention (state a2S/yl-S3
) is yellow due to baking in the range of 400 to 600 qo →
A noticeable change to red appears.

At temperatures below 400°C, the chemical reaction of formula {1' described above does not proceed and the color change is slow, making it impractical.

Moreover, if it exceeds 600o0, undesirable changes begin as shown in the table, which is not preferable. In addition, the ratio of alkali metal to indium A/ln (molar ratio) confirmed by analysis is that the xA/ylwS3 product is in the range of 0.1Sx/y≦1.5, which meets the purpose of the present invention. is 0.
A value between 1 and 10 is appropriate.

When A/ln is 0.1 or less, ln3 is present in the product.
The heat resistance is not much different from that of pure IQS3. When A ln is 10 or more, the proportion of the alkali metal compound increases, and because this substance is water-repellent, when the crab photo substance is suspended in water after firing, the pigment peels off from the crab photo substance. I don't like it. The present invention will be described in more detail below with reference to Examples.

Example 1 25 pieces of europium-activated yttrium oxysulfide (average particle size about 7 µm) of red luminescent nectar are suspended in 2500 ml of deionized water.

2. Into this crab photon suspension. 10' of an aqueous indium chloride solution containing indium ions is added and mixed. With slow stirring, the pH of the suspension is adjusted to about 2.2 (1-3.6 is acceptable) by adding an acid such as hydrochloric acid. Next, sodium sulfide Na2SI. Approximately 200% of an aqueous solution of Z containing Flower R is added dropwise. The mixture is aged for at least 1 hour while the liquid is stirred, and almost all of the indium present is precipitated as indium sulfide particles on the crab phosphor particles.

The solids are then allowed to settle, the supernatant is filtered, the settled solids are washed with deionized water, and the solids are dried at about 125°C. The dried solid substance has a slightly light yellow color. 1.1 kudzu P of sodium carbonate and 2 & r of sulfur are thoroughly mixed with 25 r of the above solid material. Next, this mixture is placed in a quartz crucible and fired for 850q030 minutes in a slightly reducing atmosphere. The body color of the product obtained as described above is yellow, and the product has a spectral reflectance as shown in FIG. 1B.
After washing and drying with water and baking in air for 1 hour at 500°C, this substance exhibits a red color, and is a pigment-coated crab phosphor with a spectral reflectance as shown in Figure 2E and excellent contrast against external light. . Example 2 Indium chloride 1008 is dissolved in deionized 2500'.

A portion of the indium ions present in the aqueous solution are precipitated as indium sulfide particles by passing hydrogen sulfide into this aqueous solution at a rate of 12 minutes per minute for 3 hours. The solids are then allowed to settle, the top light is turned off, the settled solids are washed with deionized water, and the solids are dried at about 100 qo. The dried solid substance has a clear reddish color. Thoroughly mix 0.521 log of sulfur of sodium carbonate with 10 pieces of the above solid material. Next, this mixture is placed in a quartz crucible and calcined for 850 kg in a weakly reducing atmosphere for 30 minutes. This calcined product has a yellow color, but after washing with water and drying. After baking at 500 DEG C. for 1 hour, the color changed to red, and as shown in FIG. 2B, the pigment-coated crab phosphor had almost the same spectral reflectance and excellent contrast.
Example 3 In the same manner as in Example 1, 0.8 female liters of lithium carbonate was added to 25 liters of solid material of crab phosphor on which indium sulfide was precipitated.
Two sulfur hydroxides were mixed uniformly and fired at 800°C for 30 minutes.

After washing and drying this baked product, the body color of the crab phosphor obtained was pale yellow, but after baking in air for 50 million hours, it took on a red color similar to that of Example 1. Example 4 Similar to Examples 1 and 3, but with 1.5 ml of potassium carbonate instead of lithium carbonate and sodium carbonate.
Baked for 9000030 minutes.

After firing, the crab phosphor is washed with water and dried, giving it a light color.
After baking for 1 hour at 0.degree. C., the crab photophores exhibit a red color. Example 5 In the same manner as in Example 1, 25 kg of solid material of crab phosphor with indium sulfide precipitated on the surface was mixed with lithium carbonate and 0.2 kg of sodium carbonate. 23× of sulfur was mixed uniformly and fired at 850° C. for 30 minutes.

After washing and drying this fired product, the obtained crab phosphor exhibits a pale yellow color, but when baked in air at 500° C. for 1 hour, it exhibits a red color similar to that of Example 1. Example 6 In the same manner as in Example 1, a solid substance of crab phosphor with indium sulfide precipitated on the surface was washed twice with deionized water, and then sodium sulfide N was added to the crab phosphor suspension in SO. Add an aqueous solution containing 858 and dry at about 125 qo.

This dried product was mixed uniformly with sulfur and sulfur, and fired at 850 oo for 30 minutes. The grooved light body obtained after washing with water and drying exhibits a yellow color, but after baking in air for 500q01 hours,
It exhibits a red color with almost the same spectral reflectance as Example 1.
Although sodium sulfide was used here, similar results can be obtained using other alkali sulfides.

Example 7 Yttrium oxide with europium (red light-emitting crab luminous material)
An average grain size of about 6 mounds) 245 gr is suspended in 1000' of deionized water.

Add 10 parts of indium chloride aqueous solution (0
．． Add 2 liters of indium ions (containing in each drop) and mix thoroughly into the suspension. This suspension is then dried at about 125°C. 1.158 sodium carbonate and 25 nails of sulfur were uniformly mixed into this dried material, and 8500
Bake at 0 for 30 minutes. The honey phosphor obtained by washing with water and drying exhibits a yellow color, and after baking for 500 q01 hours, it exhibits a red color with almost the same spectral reflectance as in Example 1. Example 8 In the same manner as in Example 2, a precipitate of indium sulfide was produced, washed with water and dried, and 7.18% of solid material, 24% of europium-activated yttrium oxide, 1.158% of sodium carbonate, and sulfur were added. Mix 258 evenly and make 85
Bake for 30 minutes at 0°C.

The body color of the crab photophores obtained by washing with water and drying is yellow.
After baking for 0 and 01 hours, a red color with almost the same spectral reflectance as in Example 1 was obtained. Although not mentioned in the examples, other alkali metals rubidium and cesium are also slightly expensive, but it has been confirmed that they have almost the same effect as lithium, sodium, and potassium in the examples above. It was done. Example 9 A red light-emitting photoreceptor, europium-activated yttrium oxysulfide (average grain size of about 7 μm), was mixed uniformly with 25 mm of europium oxide, 3.0 mm of indium oxide, and 1.15 g of sodium carbonate, and 2 mm of sulfur. Bake for 30 minutes at ℃.

The crab phosphor obtained by washing with water and drying exhibits a red color having substantially the same spectral reflectance as in Example 1 by baking at 500° C. for 1 hour. The pigment-coated crab phosphor of the present invention as described above generates a higher light world power than the pengara-coated crab phosphor of the subordinate type.

Table 2 shows the results of the luminescence characteristics of the indium red sulfide red oxide coated rear light body having the spectral reflectance shown in FIGS. 2B and 2C.
Here, the red light-emitting crab light is a europium-activated yttrium oxysulfide halo. Table 2 Note that luminous reflectance here refers to spectral reflectance and luminous sensitivity distribution in the range of 400 to 70 blood.
It is calculated by multiplying the distance between the plates by each wavelength and adding up the total, and represents the brightness as seen from the visual sense.

As can be easily expected from the comparison of lines B-B and C-C in FIG. 2, the results in Table 2 show that the crab light of the present invention has a higher luminous reflectance than the conventional pengara-coated crab light. It can be seen that the brightness is high even though the brightness is low.

Furthermore, in Examples 1 to 9, the body color shifts to longer wavelengths by baking, such as from yellow to red, but the present invention is not limited to this, and the body color changes before and after baking. The present invention includes those that remain unchanged and those that shift to a slightly shorter wavelength by baking.

[Brief explanation of drawings]

Figure 1 is a diagram showing the spectral reflectance of the halo of the present invention in comparison with that of a conventional pigment-coated halo. Figure 2 is a pigment-coated halo after baking the halo of Figure 1. It is a figure showing the spectral reflectance of a body. In the figure, B-B...Pigment x, S, yin of the present invention
2S3 coated shark photon, C-C... red iron (Fe
203) Coated crab photon, DD... Cadmium sulfoselenide (CdSSe) coated crab photon. Multi-1 drawing ticket 2 drawings

Claims (1)

[Scope of Claims] 1. A pigment-coated phosphor comprising a europium-activated yttrium oxysulfide phosphor or a europium-activated yttrium oxide phosphor coated with a pigment consisting of alkali sulfate and indium sulfide. 2 A europium-activated yttrium oxysulfide phosphor or a europium-activated yttrium oxide phosphor coated with a composite compound of alkali sulfide and indium sulfide is heated at 400°C to
1. A method for producing a pigment-coated phosphor, which comprises processing at a baking temperature of 600° C. to obtain a phosphor whose surface is coated with a pigment made of alkali sulfate and indium sulfide. 3. The method for producing a pigment-coated phosphor according to claim 2, wherein the composite compound of alkali sulfide and indium sulfide is a pigment represented by the following general formula. xA
_2S・yIn_2S_3 However, A is at least one kind of alkali metal, 0.1≦x
/y≦1.5.