JP3491448B2 - Phosphors and phosphor slurries for cathode ray tubes - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode fluorescent substance, and more particularly to a fluorescent substance and a fluorescent substance slurry having excellent coating properties for a color cathode ray tube.

[0002]

2. Description of the Related Art As is well known, a fluorescent surface of a color cathode ray tube is formed with green, blue, and red light emitting phosphors in a dot shape or a stripe shape. Generally, a slurry method is used to form the fluorescent screen. The slurry method is as follows. Mainly PVA (polyvinyl alcohol) and ADC (ammonium dichromate)
A phosphor is suspended in an aqueous solution containing and to prepare a coating slurry. This coating slurry is poured onto the inner surface of the face plate of the color cathode ray tube mounted on the rotary coating machine,
After spreading over the whole, the excess slurry is shaken off at a predetermined speed and dried to form a phosphor layer. Then, by exposure to a predetermined pattern of dots or stripes through a shadow mask by an ultraviolet light source of a high-pressure mercury lamp, by developing, by washing away the unexposed excess phosphor layer,
This is a method of forming a fluorescent film. This operation is sequentially performed for each of the green, blue, and red light emitting phosphors. The following characteristics are generally required for the phosphor screen formed by such a slurry method.

(1) A good summary. That is, fine dots or stripes should be formed with a uniform film thickness. The good brightness improves the brightness of the fluorescent screen of the cathode ray tube. (2) Good sharpness. That is, dots or stripes with a predetermined shape and width are formed at predetermined positions. (3) The adhesive force between the phosphor layer and the face plate is large. If the adhesive strength is small, dots or stripes are peeled off, and the yield of the phosphor screen forming process is reduced. (4) No color mixture. That is, phosphors forming dots or stripes of one light emitting component should not be mixed with phosphors of other light emitting components adjacent to each other. When this color mixture occurs, the color purity of the green, blue, and red light emitting components decreases, and as a result, the color reproduction range of the color cathode ray tube decreases. (5) There is no residue. That is, the phosphor layer should not remain on the face plate when the unexposed phosphor layer is washed away. This also leads to a reduction in the color reproduction range of the color cathode ray tube.

The above characteristics are affected by the surface condition of the phosphor. Therefore, various phosphors for cathode ray tubes have been developed in which various treatment substances are attached to the phosphor to improve the surface condition of the phosphor.

At present, the most frequently used surface treatment substances are silicon dioxide (SiO2; hereinafter referred to as silica) and silicate compounds. These are generally obtained by adding an aqueous solution containing fine particle silica or silicate ions to a phosphor suspension, and further adding an electrolyte solution containing Zn, Al ions, etc., to adhere the additives to the phosphor surface. To be For example, Japanese Patent Publication Sho-1
Japanese Patent No. 5747 discloses a method of adding potassium water glass and zinc sulfate to a phosphor and coating the phosphor with zinc silicate. Further, Japanese Patent Publication No. 61-46512 discloses a phosphor coated with silica and a zinc compound.

[0006]

The phosphor for a cathode ray tube whose particle surface is coated by the above-mentioned method is still used in many cases since the above-mentioned coating characteristics (1) to (5) are satisfied to some extent. However, with the development of high-definition televisions, high-definition cathode ray tubes, and the like, there is a strong demand for the development of phosphors having even more excellent coating properties.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an excellent phosphor for a cathode ray tube and a phosphor slurry which satisfy all of the above-mentioned characteristics, and particularly (4) have less color mixture. .

[0008]

The present inventor believes that it is necessary to modify the particle surface of the phosphor in order to improve the color mixture, and a large number of surface treatment agents are attached to the surface of the phosphor particle. As a result of enormous tests to confirm the coating characteristics, it was found that the problem can be solved by applying a specific amount of zirconia (ZrO2) and silica (SiO2) to the phosphor, and the present invention has been completed. .

That is, the phosphor for a cathode ray tube of the present invention is
At least a phosphor and a phosphor for a cathode ray tube having a binder substance on the particle surface of the phosphor, wherein the particle surface of the phosphor is 0.1 to 0.4% by weight of the zirconia with respect to the phosphor, and the phosphor. 0.05 to 2.0% by weight of silica is attached to the binder material, and the binder material is zinc hydroxide, aluminum hydroxide, acrylic resin, gum arabic and gelatine coacervate, alginate,
It is characterized by being at least one selected from the group consisting of urea resins.

The average particle size of zirconia is 0.01.
It is preferably about 0.2 μm.

The phosphor for a cathode ray tube is preferably a phosphor to be applied to a base. Further, the phosphor for a cathode ray tube is prepared as a phosphor slurry prepared by mixing at least polyvinyl alcohol and ammonium dichromate, whereby a phosphor slurry with less color mixture can be obtained.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION On the principle of the method of forming phosphor stripes or dots on the inner surface of the face plate of a color cathode ray tube, phosphors of other colors remain after development, which causes color mixing. For example, when first applying a green light emitting phosphor, then a blue light emitting phosphor, and finally applying a red light emitting phosphor,
The blue light emitting phosphor (b) is uniformly applied on the green light emitting phosphor stripe (G), exposed and developed to form a blue light emitting phosphor stripe (B) next to it. This (B)
The blue phosphor (b) remains in (G) during the development of the formation of. The color mixture due to this residual is represented by (b / G). Further, the red light emitting phosphor (r) is uniformly applied on (G) and (B), exposed and developed to form a red light emitting phosphor stripe (R) on the remaining sites. During development of the formation of this (R), the red light-emitting phosphor (r) is contained in (G) and (B).
Remains. These are expressed as (r / G) and (r / B). As described above, the color mixture is caused as a result of the residual of the other color phosphor on the base stripe.

The mixed colors are (1) the phosphor layer of the underlying stripes or dots tends to easily retain the phosphors of other colors, and (2) the phosphors applied later are in the stripes or dots of other colors. The tendency to remain in the, depends on two factors. The present invention mainly aims to reduce color mixture due to (1). That is, color mixing is made difficult by modifying the particle surface of the phosphor applied to the base.

The factor required to prevent color mixture of the phosphors forming the underlying stripes or dots is a physical factor that the coating surface has no irregularities and the phosphors applied later are easily washed off by development. Also, there is a chemical factor that the affinity with the phosphor particles to be applied later is not so great, and it is necessary to satisfy both of them.

Zirconia is an oxide of zirconium having a composition formula of ZrO2, and in the present invention, it is preferable that the average particle diameter is 0.01 to 0.2 μm.
When it is larger than this range, the specific surface area of zirconia becomes small, so that the effect on the affinity of the phosphor becomes small, and as a result, the adhered amount must be considerably increased, which causes an adverse effect of aggregating the phosphor.

Zinc hydroxide, a hydroxide of an inorganic substance of aluminum hydroxide, or an acrylic resin, which has been conventionally used as a binder substance for adhering zirconia alone or zirconia and silica to the surface of phosphor particles.
Organic binders such as coacervates of gum arabic and gelatin, alginates and urea resins can be preferably used.

FIG. 1 is a reference fluorescence of a mixed color (r / B) of the red light emitting phosphor (r) in the case where zirconia is attached to the phosphor forming the blue light emitting phosphor stripe (B), without zirconia being attached. It is the figure which plotted the relative ratio with respect to a body. From FIG. 1, the relative value of (r / B) decreases with the amount of zirconia deposited, and is 0.1 wt.
% Of 6 with no zirconia attached
It becomes relatively small, and the adhesion of 0.4 wt% becomes a minimum of 40% compared to the one without zirconia. This effect is presumed to be due to the fact that zirconia was attached to the blue light emitting phosphor to lower the chemical affinity with the red light emitting phosphor (r) to be applied later.

However, if more is added, (r / B)
On the contrary, the relative value of increases. This is because with the addition of zirconia, the blue-emitting phosphor tends to aggregate, the coated surface of the stripe (B) becomes rough, and the red-emitting phosphor (r) is three-dimensionally trapped in the unevenness of the surface of (B). This is because it cannot be easily removed by development.

FIG. 2 shows the relationship between the amount of zirconia applied to the blue light emitting phosphor and the evaluation of the applied surface. The evaluation of the coated surface in this case is the result of uniformly coating the blue light emitting phosphor on the cathode ray tube face plate and evaluating the coated surface with the naked eye in five grades. The higher the score, the better the coated surface. The amount of zirconia adhered to the blue-emitting phosphor is 0.
When it is less than 4 wt%, the coated surface is good at almost 5, but when it is more than this, the blue-emitting phosphor tends to aggregate, and the evaluation of the coated surface is greatly deteriorated. As the coated surface becomes rough, the surface (B) becomes uneven, and the area (r / B) in FIG. 1 where the amount of zirconia adhered is greater than 0.4 wt%
Reasonably explain the reason for the decrease in the relative value of.

FIG. 3 is a plot of the relationship of the relative value (r / B) to the silica adhesion of the blue light emitting phosphor to which 0.4 wt% of zirconia is adhered. From this figure, it is understood that the relative value of (r / B) becomes smaller due to the adhesion of silica, and the silica becomes minimum at 0.5 wt%.
However, when the amount of silica is larger than this, the (r / B) relative value gradually increases. Even so, when the silica content is 2 wt% or less, the relative value of (r / B) is smaller than that of zirconia alone without silica addition. Due to the interaction between this silica and zirconia, a blue-emitting phosphor stripe (B)
It can be estimated that the affinity for the red-emitting phosphor (r) is further reduced. The optimum value of the adhesion amount of silica and zirconia is somewhat affected by the combination with the phosphor to be applied later, and therefore needs to be finely adjusted.

1 to 3 have been described by taking the color mixture (r / B) due to the residual of the red light emitting phosphor (r) on the underlying blue light emitting phosphor stripe (B) as an example, the first is the green light emitting phosphor. When the stripe (G) is applied and then the blue light emitting phosphor (b) is applied, the underlying green light emitting phosphor stripe (G)
To the color mixture (b /
G), the color mixture (r / G) of the finally applied red light emitting phosphor (r) to the green light emitting phosphor stripe (G) is also reduced by the interaction of zirconia and silica, and the color mixing is improved. .

[0022]

[Examples] [Example 1] 1 kg of a blue light emitting phosphor (ZnS: Ag) was suspended in 3 L of water, in which: Zirconia sol (NZS-30A manufactured by Nissan Kagaku KK; average particle size) 0.062 μm; content 30.7%) ······· 3.3 g Silica (Snowtex ZL manufactured by Nissan Kagaku KK; average particle size 0.1 μm; content 52 %) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Adding 7.7 ml, ZnSO4 aqueous solution (2w / v% as Zn2 +)
Was added to 30 ml, the pH was adjusted to 7.8 with aqueous ammonia, separated, dried, passed through a sieve, and zirconia sol was adjusted to 0.1.
A phosphor of the present invention was adhered in an amount of 0.4% by weight and 0.4% by weight of silica.

[Example 2] 1 kg of a blue light emitting phosphor (ZnS: Ag) was suspended in 3 L of water, in which: Zirconia sol (NZS-30A manufactured by Nissan Kagaku KK; average particle size 0) 0.062 μm; content 30.7%) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 6.5 g ・ Silica (Snowtex ZL manufactured by Nissan Chemical Industries, Ltd .; average particle size 0.1 μm; content 52% ) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Add 7.7ml, ZnSO4 aqueous solution (2w / v% as Zn2 +)
Was added to 30 ml, the pH was adjusted to 7.8 with aqueous ammonia, separated, dried, and passed through a sieve to give a zirconia sol of 0.2
A phosphor of the present invention was adhered in an amount of 0.4% by weight and 0.4% by weight of silica.

Example 3 A blue-emitting phosphor (ZnS: Ag) (1 kg) was suspended in 3 L of water, in which: Zirconia sol (Nissan Chemical Co., Ltd. NZS-30A; average particle size 0) 0.062 μm; content 30.7%) ・ ・ ・ ・ ・ ・ ・ ・ 9.8 g ・ Silica (Snowtex ZL manufactured by Nissan Chemical Co., Ltd .; average particle size 0.1 μm; content 52% ) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Add 10.0 ml and add ZnSO4 solution (2w / v% as Zn2 +).
Was added to 30 ml, the pH was adjusted to 7.8 with aqueous ammonia, separated, dried, and passed through a sieve to give a zirconia sol of 0.3.
A phosphor of the present invention was adhered in an amount of 0.4% by weight and 0.4% by weight of silica.

[Example 4] 1 kg of a blue-emitting phosphor (ZnS: Ag) was suspended in 3 L of water, in which: Zirconia sol (NZS-30A manufactured by Nissan Kagaku Co., Ltd .; average particle size: 0. 062 μm; content 30.7%) ... Add 3.3 g of ZnSO4 aqueous solution (2w / v% as Zn2 +)
Was added to 30 ml, the pH was adjusted to 7.8 with aqueous ammonia, separated, dried, passed through a sieve, and zirconia sol was adjusted to 0.1.
A phosphor of the present invention having a weight% of adhered was obtained.

[Example 5] 1 kg of a blue light emitting phosphor (ZnS: Ag) was suspended in 3 L of water, in which: Zirconia sol (NZS-30A manufactured by Nissan Kagaku KK; average particle size 0) 0.062 μm; content 30.7%) ········ 3.3 g · Silica (Nissan Chemical Co., Ltd. Snowtex ZL; average particle size 0.1 μm; content 52%)・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Add 7.7 ml and add Al2 (SO4) 3 aqueous solution (2w / Al3 +).
(v%) was added to 5 ml, and the pH was adjusted to 7.8 with aqueous ammonia.
Was adjusted to 2, separated and dried, and passed through a sieve to obtain a phosphor of the present invention on which 0.1% by weight of zirconia sol and 0.4% by weight of silica adhered.

[Example 6] 1 kg of a blue-light-emitting phosphor (ZnS: Ag) was suspended in 3 L of water, in which: Zirconia sol (NZS-30A manufactured by Nissan Kagaku KK; average particle size 0) 0.062 μm; content 30.7%) ... 3.3 g Silica (Snowtex ZL manufactured by Nissan Chemical Co., Ltd .; average particle size 0.1 μm; content 52% ) ............ Add 7.7 ml, add 30 ml of 1% aqueous solution of gum arabic and 30 ml of 1% aqueous solution of gelatin, add acid to adjust pH to 3.8.
Was adjusted to 2, separated and dried, and passed through a sieve to obtain a phosphor of the present invention having 0.1% by weight of zirconia sol and 0.4% by weight of silica.

Example 7 1 kg of a blue-emitting phosphor (ZnS: Ag) was suspended in 3 L of water, in which: Zirconia sol (Nissan Chemical Co., Ltd. NZS-30A; average particle size 0) 0.062 nm; content 30.7%) ... 3.3 g Silica (Nissan Chemical Co., Ltd. Snowtex ZL; average particle size 0.1 μm; content 52% ) ... Add 7.7 ml and add 0.1% sodium alginate aqueous solution to 300
30 ml of ZnSO4 aqueous solution (2 w / v% as Zn2 +) was added to obtain a phosphor of the present invention having 0.1% by weight of zirconia sol and 0.4% by weight of silica.

Example 8 A blue-emitting phosphor (ZnS: Ag) (1 kg) was suspended in 3 L of water, and zirconia sol (Nissan Chemical Co., Ltd. NZS-30A; average particle size 0) 0.062 nm; content 30.7%) ... 3.3 g Silica (Nissan Chemical Co., Ltd. Snowtex ZL; average particle size 0.1 μm; content 52% ) ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Add 7.7ml, acrylic emulsion (acrylic content 45%)
6.7 ml was added, spray-dried and passed through a sieve,
Zirconia sol 0.1 wt%, silica 0.4 wt%
The adhered phosphor of the present invention was obtained.

[Comparative Example 1] 1 kg of a blue light-emitting phosphor (ZnS: Ag) was suspended in 3 L of water, and in it: Silica (Snowtex ZL manufactured by Nissan Kagaku Co .; 1 μm; content 52%) ............ Add 7.7 ml, add ZnSO4 aqueous solution (2 w / v% as Zn2 +) 30 ml, and add ammonia water to adjust pH to 7.8. Was adjusted to 2, separated and dried, and passed through a sieve to obtain a phosphor of Comparative Example to which 0.4% by weight of silica adhered.

Example 9 Instead of the blue light emitting phosphor, a green light emitting phosphor (ZnS:
In the same manner as in Example 1 except that Cu, Al) was used, a phosphor of the present invention having 0.1% by weight of zirconia sol and 0.4% by weight of silica was obtained.

[Example 10] Instead of the blue light emitting phosphor, a green light emitting phosphor (ZnS:
A phosphor of the present invention having 0.2% by weight of zirconia sol and 0.4% by weight of silica was obtained in the same manner as in Example 2 except that Cu, Al) was used.

Example 11 Instead of the blue light emitting phosphor, a green light emitting phosphor (ZnS:
A phosphor of the present invention having 0.3% by weight of zirconia sol and 0.4% by weight of silica was obtained in the same manner as in Example 3 except that Cu, Al) was used.

[Comparative Example 2] Instead of the blue light emitting phosphor, a green light emitting phosphor (ZnS:
In the same manner as in Comparative Example 1 except that Cu, Al) was used, a phosphor of the present invention having 0.4% by weight of silica attached was obtained.

Using 100 parts by weight of the phosphor obtained as described above, 110 parts by weight of pure water, 7.5 parts by weight of polyvinyl alcohol adjusted to a usual working concentration, and ammonium dichromate are added. 0.4 parts by weight and 0.7 parts by weight of a surfactant were mixed to prepare a coating slurry.
The respective coating slurries are applied, exposed and developed according to a conventional method to form a green light emitting phosphor stripe (G) → a blue light emitting phosphor stripe (B) → a red light emitting phosphor stripe (R) in this order, and the color mixture at that time (B / G), (r /
G) and (r / B) were measured as follows.

For example, when the blue light emitting phosphor is applied and then the green light emitting phosphor is applied, ultraviolet rays are radiated from the outer surface of the face plate to cause the fluorescent surface to emit light, and a unit area (0.2 mm × 0.2 mm The number of particles of the blue light emitting phosphor (b) remaining on the green light emitting phosphor stripe (G) per 1) was observed by an optical microscope and counted, and the average of the counted values at 10 points was obtained. This is expressed as a relative value of (b / B) by taking a relative ratio with respect to a reference phosphor to which zirconia and silica are not attached. Similarly, (r / G), (r / B)
The relative value of was also calculated. The results are shown in Table 1.

[0037]

[Table 1]

[0038]

EFFECTS OF THE INVENTION As for color mixing, (1) the phosphor layers of the underlying stripes or dots tend to easily retain phosphors of other colors, and (2) the phosphors applied later are of stripes or dots of other colors. It tends to remain inside, and depends on two factors. The present invention was able to reduce the color mixture mainly due to (1). That is, by adhering zirconia and silica to the particle surface of the phosphor applied to the underlayer, it was possible to make it difficult to receive color mixing.

The amount of zirconia deposited is 0.005 to 0.5
By setting the content in the range of wt%, it is possible to reduce the affinity between the stripes or dots formed earlier and the phosphor particles applied later, which is a major cause of color mixing, and the color mixing is reduced.

Further, the amount of silica adhered is 0.05 to
By setting the content in the range of 2.0% by weight, the unevenness of the phosphor-coated surface is good, and by limiting the content in this range, it is possible to reduce the color mixture due to the phosphor remaining due to steric hindrance.

[Brief description of drawings]

FIG. 1 shows the amount of zirconia deposited on a blue-emitting phosphor and (r /
The characteristic view which shows the relationship of B).

FIG. 2 is a characteristic diagram showing a relationship between a zirconia adhesion amount of a blue light emitting phosphor and a coated surface evaluation value.

FIG. 3 is a characteristic diagram showing the relationship between the silica deposition amount and (r / B) of a blue light emitting phosphor to which 0.4 wt% of zirconia is deposited.

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-4-214789 (JP, A) JP-A-4-236294 (JP, A) JP-A-7-188650 (JP, A) JP-A-1- 272688 (JP, A) JP 59-36182 (JP, A) JP 8-92549 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09K 11/08 C09K 11 / 02

Claims (4)

(57) [Claims] 1. A phosphor for a cathode ray tube comprising at least a phosphor and a binder substance on the particle surface of the phosphor, wherein the particle surface of the phosphor is 0.1 to 0.
4 wt% zirconia and 0.05 to 2.0 wt% silica are attached to the phosphor, and the binder material is zinc hydroxide, aluminum hydroxide, acrylic resin, gum arabic and gelatin coacervate, A phosphor for a cathode ray tube, which is at least one selected from the group consisting of alginates and urea resins. 2. The average particle size of the zirconia is 0.0
The phosphor for a cathode ray tube according to claim 1, having a thickness of 1 to 0.2 μm. 3. The phosphor for a cathode ray tube according to claim 1, wherein the phosphor for a cathode ray tube is a phosphor coated on a base. 4. A phosphor slurry prepared by mixing the phosphor for a cathode ray tube according to any one of claims 1 to 3 with at least polyvinyl alcohol and ammonium dichromate.