JPH0662940B2 - Fluorescent body - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a surface treatment of a phosphor used in a cathode ray tube, and more specifically, a physical property of a phosphor characteristic due to mutual contamination between the phosphors or contamination from an external environment during a phosphor film forming process. The present invention relates to a phosphor with little physical or chemical change or deterioration.

[Prior art]

With the recent development of display tubes for televisions, computer terminals, etc., the display colors have become multicolored, and there are demands for various colors for phosphors. For example, as the green-emitting phosphor, ZnS: Cu, Zn ₂ SiO ₄ : Mn, Zn
S: Cu, (Zn, Cd) S: Cu, Y ₂ O ₂ S: Tb, etc., as the blue-emitting phosphor, ZnS: Ag, ZnS: Zn, Y ₂
SiO ₅ : Ce, Y ₂ O ₂ S: E as a red light emitting phosphor
u, Y ₂ O ₃ : Eu, YVO ₄ : Eu, Zn ₃ (P
O ₄ ) ₂ : Mn and other emission colors are Cd ₅ Cl (P
_{O 4) 3: Mn, (} Zn, Cd) S: there is Ag and the like. For colors that cannot be expressed by a single phosphor, two or more kinds of phosphors are mixed to obtain a desired color. For example Cd ₅ C
1 (PO ₄ ) ₃ : Mn + ZnS: Ag purple emission mixed phosphor, Cd ₅ Cl (PO ₄ ) ₃ : Mn + ZnS: Cu yellow emission mixed phosphor, ZnS: Ag + (Zn, Cd) S: Cu white emission mixed _{phosphor, ZnS: Ag + Zn 3 (} PO 4) 2: Mn
+ Zn ₂ SiO ₄ : Mn, As is a light blue light-emitting mixed phosphor.

[Problems to be Solved by the Invention]

However, in the case of such a mixed phosphor, in the heating step in the manufacturing process of the cathode ray tube, the phosphors react with each other, and some phosphors that emit light of an undesired color are generated, resulting in an overall color purity. A problem that lowers. For example, Zn
In the case of S: Ag + Cd ₅ Cl (PO ₄ ) ₃ : Mn mixed phosphor, Cd or Mn of Cd ₅ Cl (PO ₄ ) ₃ : Mn is Z
The phenomenon that the phosphor film is discolored by reacting with the sulfur content of the phosphor of nS: Ag is a cause of lowering the brightness. There is also a problem that heavy metals such as copper, iron and nickel are mixed and contaminated in the cathode ray tube manufacturing process. For these, the surface treatment with phosphate has been conventionally used (Japanese Patent Publication No. 40-
No. 28648), surface treatment with ZnS (Japanese Patent Publication No.
No. 7-38307) has been proposed, but sufficient effects have not been obtained yet. The present invention was developed with the object of eliminating these conventional defects, and an important object of the present invention is to provide a stable phosphor covered with a surface composition. Another important object of the present invention is to provide a phosphor capable of obtaining a desired high-purity emission color when a phosphor film is formed by mixing a plurality of phosphors. Still another object of the present invention is to provide a phosphor capable of reducing heavy metal contamination and contamination in the process of manufacturing a cathode ray tube.

[Means for Solving the Problems]

The phosphor of the present invention has a surface composition attached to the surface of phosphor particles. The surface composition is borosilicate glass or borophosphosilicate glass, which is kept below the melting temperature and adhered to the surface of the phosphor particles in a non-hollow state. The content of Si, B and P in the borosilicate glass or borophosphosilicate glass adhered to the surface of the phosphor particles is preferably in the range of 1 × 10 ^{−3 to} 5% by weight based on the phosphor. By coating these surface compositions on the phosphor surface,
Even if the phosphor is cross-contaminated or the environment is contaminated during the phosphor film formation process, the contamination source is prevented from advancing into the phosphor. On the contrary, the elements inside the phosphor are less likely to be thermally diffused to the outside, which also has the effect of reducing contamination of other phosphors. In addition to the above surface composition, the present invention also comprises aluminum,
By simultaneously coating the surface with at least one hydroxide or oxide of zinc, calcium, barium, strontium, magnesium, etc., the effect of preventing pollution can be further enhanced.

[Action]

In order to investigate the action and effect of the phosphor of the present invention, silver-activated zinc sulfide blue light-emitting phosphor ZnS: Ag is treated with orthoboric acid and silicon oxide at various ratios to form phosphor particles on the surface composition. The prototype of the phosphor of the present invention covered with is manufactured and the contamination with copper was investigated by the following method. The phosphor of the present invention is prepared into a phosphor slurry by using an aqueous solution of ammonium dichromate-containing polyvinyl alcohol, and the obtained phosphor slurry is applied to a glass plate for measurement and dried. Next, CuSO with a Cu concentration of 100 ppm
1 ml of ₄ solution was dropped on the phosphor-coated surface, and then 43 solution was applied according to the panel bake at the time of manufacturing a cathode ray tube.
After baking at 0 ° C. for 30 minutes, the color tone was measured after cooling.
This is plotted in FIG. 1 (a) and FIG. 1 (b) with respect to the B and Si adhesion amounts of the phosphor. FIG. 1A shows the relationship of the color tone x in the CIE color system with respect to the amount of adhered B, and FIG. 1B shows the relationship with the color tone y. However, the amount of Si attached is 0.1% by weight with respect to the phosphor.
(Constant) In the figure, Δ is the color tone of the phosphor which is not contaminated with copper, and ▲ is the color tone of the conventional phosphor not coated with the surface composition after copper contamination. That is, the conventional phosphor was discolored by a large amount of x-value shift from the position of Δ to the position of ▲ due to copper contamination. On the other hand, in the phosphor of the present invention coated with the surface composition, as the amount of B contained in the surface composition increases, x
Both the value and the y value were close to the color tone value before being contaminated with copper, and the color tone change was small. Both of these x and y values showed ideal characteristics when the B content of the surface composition was 0.2% by weight or more. FIG. 2 (a) shows the relationship between the color tone x and the Si content of the phosphor containing 0.1% by weight of B in the surface composition as an analytical value, and FIG. 2 (b) shows the color tone y. Shows the relationship. As is clear from this figure, as the Si content of the surface composition increased, both the x value and the y value became close to the color tone value (Δ) before contamination with copper, and the change in the color tone decreased. Further, when the Si content of the surface composition was 0.2% by weight, ideal characteristics were exhibited. From this, the following two conclusions can be concluded. Contamination of the phosphor with Cu is caused by the following reaction when baked at 430 ° C. for 30 minutes.
Cu enters nS: Ag as an emission center, and Cu causes emission of a green component, so that the emission color is yellowish as a whole. ZnS: Ag + Cu → ZnS: Ag, Cu The effect of suppressing the reaction is small with H ₃ BO ₃ and SiO ₂ alone, and is significantly improved when these two compositions are used together, which results in ZnS: Ag phosphor particles. In the case of the above, the change in color due to copper contamination is extremely reduced. From the results of FIGS. 1 and 2, the content of Si and B in the surface composition is preferably 0.2% by weight or more with respect to the phosphor, but 0.2% by weight A sufficient effect can be expected even with the following. On the contrary, B and S of the surface composition
If the content of i is too large, the dispersibility of the phosphor will be impaired and the coating characteristics will be deteriorated. Therefore, the practical range considering dispersibility is that the contents of Si and B are 1 × 10 ^{−5 to} 5% by weight, preferably 1 ×, relative to the phosphor.
It is 10 ^{−2 to} 2% by weight. Further, the same tendency as that of Si and B was confirmed by the surface composition in which P and B were combined instead of the combination of Si and B.

【Example】

Examples of the present invention will be described below. Example 1 Blue-Emitting Silver-Activated Zinc Sulfide Phosphor ZnS: Ag100
g, 1.7 g of orthoboric acid, and 0.
3 g was poured into 250 ml of pure water, and the pH was adjusted to 8 with aqueous ammonia. Water was evaporated from this solution to dry it, and then baked at 430 ° C. for 30 minutes to obtain a phosphor of the present invention. The phosphor that has been surface-treated with H ₃ BO ₃ and SiO ₂ as described above has the surface composition in the state of borosilicate glass attached, and the contents of B and Si are different from those of the phosphor. Then, B was 0.267% by weight and Si was 0.246% by weight. Borosilicate glass baked at 430 ° C
At this temperature, it is not melted and adheres to the surface of the phosphor particles in a non-hollow state. Incidentally, the softening temperature of borosilicate glass is 900 ° C. However, in the present specification, when the content of the surface deposit on the phosphor is expressed in wt%, the reference phosphor does not include the surface deposit. The phosphor obtained as described above, using an aqueous solution of polyvinyl alcohol containing ammonium dichromate, a phosphor slurry was prepared by a usual method, and the obtained phosphor slurry was applied to a glass plate for measurement and dried. . Then, a CuSO ₄ solution having a Cu concentration of 100 ppm was dropped on the phosphor-coated surface and baked at 430 ° C. for 30 minutes. After cooling, body color (visual observation), emission color, and emission spectrum were measured. The surface composition of the phosphor of the present invention, borosilicate glass is not attached, conventional blue-emitting, silver-activated zinc sulfide phosphor is applied to a glass plate in the same manner, copper contamination similar to the above Compared with the one given. The results are shown in Table 1. As shown in Table 1, the conventional phosphor changed its color tone and body color of the emission color due to copper contamination, but the phosphor of Example 1 hardly changed. How the emission spectrum of the phosphor changes due to Cu contamination is shown in the measurement result of the emission spectrum of FIG. The curve a shows the emission spectrum of the phosphor before it was contaminated with copper, the curve b shows the characteristics of the conventional phosphor after it was contaminated with copper, and the curve c shows the phosphor of the present invention contaminated with copper. It is the emission spectrum after. It is clear from the curves a and c that the phosphor of the present invention has almost the same emission spectrum before and after being contaminated, and the surface composition prevents the contamination. Example 2. Manganese-activated cadmium chloride orthophosphate phosphor, Cd ₅
Cl (PO ₄ ) ₃ : Mn 100 g, H ₃ BO ₃ 3.4
g, 0.6 g of colloidal silica, and 250 ml of pure water, the pH was adjusted to 8 with caustic soda aqueous solution, and the mixture was sufficiently stirred, water was evaporated to dryness, and the phosphor of the present invention was obtained. . The surface of the obtained phosphor is B, P and Si.
A non-enamelous surface composition which is a borophosphosilicate glass containing and was adhered. The obtained phosphor of the present invention was mixed with the blue light-emitting phosphor of the present invention obtained in Example 1 in a weight ratio of 1: 1, and thereafter, in the same manner as in Example 1, for measurement. It was applied to a glass plate and dried. This was baked at 430 ° C. for 30 minutes, cooled, and then visually observed and the color tone was measured. On the other hand, as a conventional mixed light-emitting phosphor, a conventional amber-color-emitting manganese activated cadmium chloride orthophosphate phosphor Cd ₅ Cl (PO ₄ ) ₃ : M which is not coated with a surface composition.
n and a ZnS: Ag blue light-emitting phosphor not coated with the surface composition are prepared, and the mixture is applied to a glass plate by the same method as described above, and then baked at 430 ° C. for 30 minutes and cooled. Then, the body color was visually observed and the color tone was measured. The results of the mixed emission phosphor of the present invention and the conventional mixed emission phosphor in which the emission spectrum changes after baking are shown in Table 2, FIG. 4 and FIG. As shown in Table 2, in the conventional mixture phosphor, the color tone of the luminescent color by heating (baking), and the x value from 0.245 to 0.
In 341, the y value changed considerably from 0.159 to 0.293 and the body color changed from white to gray, while the phosphor of the present invention had an x value of 0.246 to 0.248. , Y value hardly changed from 0.158 to 0.161, and no visual change in body color was observed. Further, the mixed light-emitting phosphor of the present invention has the curves a and b in FIG.
As shown in, the emission spectrum hardly changed even after baking. Curve a in FIG. 4 is the emission spectrum of the phosphor before baking, and curve b is the emission spectrum of the mixed light-emitting phosphor of the present invention after baking. On the other hand, the conventional mixed light-emitting phosphor, as shown in FIG.
The emission spectrum changed significantly after baking. In FIG. 5, the curve a shows the emission spectrum before the wave, and the curve b.
Shows the emission spectrum after baking. Example 3. 1.5 g of H ₃ BO ₃ in 20 ml of water, (NH ₄ ).
0.9 g of ₂ HPO ₄ and 0.4 g of colloidal silica are added, and the pH is adjusted to 8 with aqueous ammonia. In this way, an aqueous solution of the coating is obtained. On the other hand, in 250 ml of methanol, ZnS: A
100 g of the blue light emitting phosphor is added to obtain a phosphor suspension. Slow addition of an aqueous coating solution to this phosphor suspension causes precipitation. This suspension was dehydrated and then dried to obtain the phosphor of the present invention. In the phosphor manufactured in this way, the surface composition in the state of borophosphosilicate glass containing B, P and Si was attached to the surface of the phosphor particles. As a result of analysis of this phosphor, B is phosphor 10
0.210% by weight and P is 0.184 with respect to 0% by weight
%, And Si was 0.252% by weight. When a Cu contamination test was conducted under the same conditions as in Example 1, neither the color tone nor the emission spectrum changed. Example 4. To 20 ml of water, 2.0 g of H ₃ BO ₃ ((N
H ₄ ) ₂ HPO ₄ 1.0 g, colloidal silica 0.4
1.0 g of Mg (NO ₃ ) ₂ and p with ammonia water
Adjust H to 8. In this way, an aqueous solution of the coating is obtained. On the other hand, ZnS: Ag was added to 250 ml of methanol.
100 g of blue light emitting phosphor is added to make a phosphor suspension. Slow addition of an aqueous coating solution to this phosphor suspension causes precipitation. The precipitate was dehydrated and dried, and then baked at 430 ° C. for 30 minutes to obtain the phosphor of the present invention. The phosphor manufactured in this way is composed of B, P, Si and M.
The surface composition of borophosphosilicate glass containing n was adhered to the surface of the phosphor particles. As a result of the analysis, this phosphor has a B content of 0.281% by weight, a P content of 0.196% by weight, a Si content of 0.263% by weight, and a Mg content of 0.510%.
% By weight. When a Cu contamination test was conducted in the same manner as in Example 1, there was no change in color tone or emission spectrum. Example 5. 1.8 g of H ₃ BO ₃ in 20 ml of water, (NH ₄ ).
₂ HPO ₄ (0.8 g) and colloidal silica (0.2 g) are added, and the pH is adjusted to 8 with aqueous ammonia. In this way, an aqueous solution of the coating is obtained. On the other hand, 250 ml of methanol in (Zn, cd) S:
100 g of Cu yellow light emitting phosphor is added to obtain a phosphor suspension. Precipitation occurs when an aqueous solution of the coating is slowly added to this phosphor suspension. The precipitate was dehydrated and dried, and then baked at 430 ° C. for 30 minutes to obtain the phosphor of the present invention. The phosphor manufactured in this way is composed of B, P and Si.
The surface composition of borophosphosilicate glass containing and was adhered to the surface of the phosphor particles. This product was mixed at 60% and the phosphor of Example 1 was mixed at a ratio of 40% to form a black-and-white phosphor, and a precipitation film was formed using a barium acetate and potassium silicate solution, and the same baking test as in Example 2 was performed. As a result, the color tone and the emission spectrum did not change. Example 6. The amber-color-emitting phosphor Cd ₅ Cl (P
O _{4) 3:} Mn 65.2 wt%, Example blue phosphor obtained in 4 ZnS: the Ag 11.0 wt% and the green light emitting phosphor _Zn 2 _SiO 4: Mn, the As 23.8 weight%
Are mixed, and as a paper white emission color, Ba (CH ₃ CO
O) ₂ and K ₂ SiO ₃ solution to form a precipitate film
When baked for 0 minutes, neither the color tone nor the emission spectrum changed.

【The invention's effect】

The phosphor for a cathode ray tube of the present invention coats the surface of phosphor particles with a specific surface composition. The surface composition is a non-hollow, borosilicate or borophosphosilicate glass. The phosphor for a cathode ray tube coated with this surface composition can have a desired high-purity emission color when a plurality of phosphors are mixed to form a phosphor film. that is,
This is because the surface composition stably protects the phosphor particles.
The stably protected phosphor does not generate a phosphor that emits light of an undesired color in a heating process for manufacturing a cathode ray tube, in which a plurality of phosphors react with each other. Therefore, even if using a plurality of phosphors, the color purity does not decrease,
A highly pure emission color can be obtained. This feature is apparent from FIGS. 5 and 4. FIG. 4 shows emission spectra of the phosphor of the present invention before and after baking. FIG. 5 shows emission spectra of a conventional phosphor before and after baking. These figures show that Cd ₅ Cl (P
A mixture of O ₄ ) ₃ : Mn phosphor and ZnS: Ag phosphor was mixed at 430 ° C. in the same manner as in the cathode ray tube manufacturing process.
It shows the change in emission spectrum before and after baking for 30 minutes. The emission spectrum of the conventional phosphor shown in FIG. 5 remarkably changes before and after baking, but the emission spectrum of the phosphor of the present invention shown in FIG. 4 has a very small difference between before and after baking. Furthermore, the phosphor for a cathode ray tube of the present invention can effectively prevent a change in emission color due to the inclusion of heavy metals in the process of manufacturing the cathode ray tube. This is because the surface of the phosphor is coated with a specific surface composition to stably protect the phosphor. FIG. 3 shows a state in which copper is mixed and the emission color of the ZnS: Ag phosphor is changed. Curve a is an emission spectrum of a phosphor not contaminated with copper, curve b is an emission spectrum of a conventional phosphor contaminated with copper, and curve c is an emission spectrum of the phosphor of the present invention contaminated with copper. As shown by the curve c, the phosphor of the present invention has an excellent characteristic that the change in emission spectrum due to contamination with copper can be extremely reduced. Furthermore, a remarkable feature of the phosphor for a cathode ray tube of the present invention is that the phosphor can be extremely stably protected by the surface composition, but the deterioration of the emission characteristics of the phosphor can be extremely reduced. That is because the phosphor of the present invention coats the surface of the phosphor particle with a surface composition which is a non-hollow glassy material. The surface composition that coats the particle surface of the phosphor is melted into a enamel when heated to a temperature higher than the melting temperature. The enamel surface composition can stably protect the phosphor particles. However, when a phosphor coated with a enamel surface composition is used in a cathode ray tube, there is a drawback that the electron beam excitation efficiency is reduced. This is because the electron beam cannot directly excite the phosphor, but penetrates the enamel surface composition to excite the phosphor. Therefore, the phosphor coated with the enamel surface composition has an excellent feature in that the emission spectrum is not changed, but has a drawback that the most important luminous efficiency of the phosphor is lowered. The phosphor of the present invention is used for a cathode ray tube excited by an electron beam. The method of reducing the emission efficiency of the electron beam cannot be used at all even if it has an excellent feature that the emission spectrum does not change. The phosphor for a cathode ray tube of the present invention stably protects the phosphor as a non-enamel surface composition by making the composition of the surface composition and the content thereof specific. For this reason, it is possible to minimize the deterioration of the emission characteristics, which is extremely important for the phosphor, and to realize an excellent feature that can effectively prevent a change in emission color.

[Brief description of drawings]

1 to 2 are graphs showing changes in color tone with respect to the amount of B or Si deposited, FIG. 3 are graphs showing changes in emission spectrum due to copper contamination, and FIGS. 4 and 5 are before and after baking. 5 is a graph showing changes in the emission spectrum of

Claims (4)

[Claims] 1. A cathode ray tube characterized in that a surface composition which is a borosilicate glass or a borophosphosilicate glass is adhered to the surface of phosphor particles in a non-enamel state while being kept at a melting temperature or lower. Phosphor. 2. The phosphor for a cathode ray tube according to claim 1, wherein the content of Si in the surface composition is in the range of 1 × 10 ^{−5 to} 5% by weight with respect to the phosphor. . 3. The phosphor for a cathode ray tube according to claim 1, wherein the content of B in the surface composition is in the range of 1 × 10 ^{−5 to} 5% by weight with respect to the phosphor. . 4. The phosphor is ZnS: Ag, ZnS: Ag,
Al, ZnS: Cu, ZnS: Cu, Al, Cd ₅ Cl
_{(PO 4) 3: Mn,} (Zn, Cd) S: Cu, Zn 2 SiO 4: M
The phosphor for a cathode ray tube according to claim (1), which is any one of n, As, and Zn ₂ SiO ₄ : Mn.