JPH02233794A - Production of fluorescent material attached with spherical silicon dioxide - Google Patents

Abstract

PURPOSE:To obtain a fluorescent material suitable for a fluorescent face of a cathode-ray tube such as a color-picture tube satisfying the requirements of minimum stripe width, fogging of glass surface and relative luminance at the same time by applying SiO2 to a fluorescent material surface using a specific colloidal silica. CONSTITUTION:The objective fluorescent material is produced by applying a specific colloidal silica having the following properties to the surface of a fluorescent material and fixing the silica with an adhesive. The colloidal silica contains SiO2 having spherical form, containing >=70wt.% of particles (based on the whole particles) satisfying the formula 1>=DS/DL>=0.7 (DS is smallest particle diameter; DL is largest particle diameter), having an average particle diameter of 50-400mum and containing >=60wt% of particles (based on the whole particles) having particle diameter of Dav+ or -0.4Dav (Dav is average diameter of particle). The colloidal silica to be used in the present process is the one giving <=3wt.% of precipitate (based on the whole weight of the silica) when a colloid having a silica content of 1% and liquid pH of 10 is left standing for 48hr.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a phosphor suitably used in the phosphor screen of color picture tubes and other cathode ray tubes.

[Conventional technology and its problems]

In recent years, there has been a demand for particularly clear images from cathode ray tubes. A clear image can be achieved by satisfying the following characteristics. ■ Reducing the minimum stripe width to increase resolution; ■ Reducing phosphor cross-contamination to express beautiful colors; ■ Increasing luminance to create a bright screen. In order to satisfy these characteristics, the phosphors used in color picture tubes are subjected to various surface treatments to improve coating characteristics. Silicate compounds, aluminate compounds, phosphate compounds, metal oxides, and the like are used as substances to be attached to the surface of the phosphor. In particular, silicate compounds are widely used because they are easy to process. Silicon dioxide is known as a silicate compound. Furthermore, there are several types of silicon dioxide depending on the size and state of the particles and their properties. Particulate silica is an example of silicon dioxide with relatively large particles. In addition, as silicon dioxide with relatively small particles,
There is colloidal silica. Potassium silicate is silicon dioxide dissolved in water. When silicon dioxide is attached to the surface of a phosphor using colloidal silica in which silicon dioxide is dispersed in a liquid, silicon dioxide can be uniformly attached to the surface of the phosphor. A technique for attaching silicon dioxide to the surface of a phosphor using colloidal silica has not yet been developed (Japanese Patent Publication No. 61-465
Publication No. 12). The manufacturing method disclosed in this publication specifies the particle size of silicon dioxide adhering to the surface of the phosphor to improve the minimum stripe width and glass surface force blur. That is, the amount of silicon dioxide deposited with an extremely wide average particle diameter of 60 to 300 mμ was reduced to 70% by weight.
The above is specified. In this way, by attaching silicon dioxide, which is distributed from fine particles to large particles, to the surface of the phosphor, the minimum stripe width and glass surface force blur can be improved. However, the phosphor produced by this method has the drawback that fine particles and large granular silica particles are attached to the surface of the phosphor, resulting in a large amount of silicon dioxide attached. Large amounts of silicon dioxide deposited on the phosphor surface reduce the relative brightness of the phosphor. This is because silicon dioxide absorbs or scatters the light emitted from the phosphor. Furthermore, when large particles of silicon dioxide of 100 mμ or more are attached to the surface of the phosphor, the silicon dioxide tends to aggregate. Agglomerated silicon dioxide cannot uniformly coat the surface of the phosphor. Therefore, when a phosphor is coated with silicon dioxide containing agglomerated particles, the coating has little effect unless a large amount is applied. Furthermore, the aggregated particles have uneven surfaces and scatter light, thereby reducing the substantial luminance of the phosphor. A phosphor having large granular silica particles with an average particle diameter of several hundred microns attached to its surface has a wide minimum stripe width. On the other hand, a phosphor to which fine silica particles having an average particle diameter of several tens of microns is attached has the disadvantage that the glass surface tends to be blurry. That is, the minimum stripe width and the glass surface force blur are contradictory properties using the size of the particle size as a parameter, and it has been said that it is extremely difficult to satisfy both properties at the same time.

[Purpose of the invention]

This invention was developed with the aim of solving this difficult problem, and the important objectives of this invention are to use colloidal silica to minimize stripe width, reduce glass surface force blur, and reduce relative brightness. An object of the present invention is to provide a method for manufacturing a phosphor that satisfies three characteristics at the same time.

[Means to solve conventional problems]

Despite the contradictory characteristics, the inventors of the present invention
With the aim of creating a phosphor that simultaneously improves the extremely important properties that are coveted in current phosphors, namely, ■ minimum stripe width, ■ glass surface strength, and ■ relative brightness characteristics, we
After conducting numerous experiments and thoroughly investigating the cause using every possible method, we developed an extremely unique phenomenon by using a unique type of colloidal silica. That is, although silicon dioxide of the same average particle diameter is attached to the surface of the phosphor, the above characteristics are improved by attaching primary particle silica with fewer aggregated particles to the surface. Successful. That is, the method for producing a phosphor according to the present invention uses colloidal silica to attach silicon dioxide to the surface, but by specifying a unique type of colloidal silica to be attached to the phosphor, It has been successfully achieved that the relative brightness is significantly improved. The following colloidal silica is used. (a) Spherical silicon dioxide is used in colloidal silica. In this silicon dioxide, when the maximum particle size is DL and the minimum particle size is DS, 70% by weight or more of the total particles are 1≧D S/D L≧0
．． 7 is satisfied. More preferably, 1≧DS/DL≧
Satisfies 0.8. (b) The silicon dioxide contained in the colloidal silica has an average particle diameter of 50 mμ or more and 400 mμ or less. (c) Silicon dioxide contained in colloidal silica has an average particle diameter of Dav±0.4D.
It is specified that the particles having a particle size of av are 60% by weight or more, preferably 65% by weight or more, and more preferably 70% by weight or more of the total weight, and the particle size distribution is extremely sharp. (d) The colloidal silica used has a low content of aggregated primary particles. That is, colloidal silica has a silica content of 1% by weight and a liquid p
After setting H to 1O and allowing it to stand for 48 hours, the precipitate was 3% by weight.
Use the one. Furthermore, the phosphor produced according to the present invention has an adhesion amount of silicon dioxide of 0.01 to 100 parts by weight per 100 parts by weight of the phosphor.
When the amount is adjusted within the range of 3 parts by weight, preferable characteristics are exhibited. In addition, adhesives for attaching surface treatment substances to the surface of phosphor particles include, for example, zinc compounds, aluminum compounds,
At least one of phosphate compounds, alkaline earth metal compounds such as Mg, Ca, and Sr, and borate compounds can be used. As the zinc compound, water-soluble zinc salts such as zinc sulfate, zinc nitrate, and zinc acetate are used. As the aluminum compound, water-soluble aluminum salts such as aluminum nitrate and aluminum sulfate can be used. Further, as the phosphoric acid compound, a water-soluble salt such as sodium pyrophosphate is used. Magnesium nitrate, calcium nitrate, and strontium nitrate can be used as alkaline earth compounds. As the boric acid compound, boric acid, sodium borate, etc. can be used. Since the phosphor produced by the method of the present invention exhibits excellent characteristics when used in color picture tubes, it goes without saying that it can be used not only in color picture tubes but also in monochrome picture tubes. Examples of phosphors include: ■ Sulfide-based phosphors such as zinc sulfide-based phosphors and zinc cadmium sulfide phosphors; ■ Eurobium-activated yttrium oxide phosphors, manganese-activated zinc phosphate phosphors, and manganese-activated zinc silicate phosphors. Oxide-based phosphors such as phosphors, (2) oxysulfide-based phosphors such as eurobium-activated W1 yttrium sulfide phosphors, and terbium-activated yttrium oxysulfide phosphors can be used. The phosphor of this invention is manufactured by the following steps. ■ Suspend the phosphor in water. ■ Add specific colloidal silica and adhesive aqueous solution to the phosphor suspension while stirring well. (2) While further stirring the liquid to which the colloidal silica and adhesive aqueous solution have been added, an acid or alkali aqueous solution is added to adjust the pH to 5 to 8. Aqueous ammonia, potassium hydroxide, sodium hydroxide, etc. can be used as the alkaline aqueous solution, and acetic acid can be used as the acidic aqueous solution. ■ After standing still for a certain period of time, the supernatant liquid is removed by decantation, the precipitate is dehydrated, dried, and separated through a sieve. The method for producing a phosphor of the present invention uses spherical silicon dioxide as a surface treatment substance. The minimum stripe width, glass surface blur, and relative brightness of the phosphor vary depending on the average particle diameter. Figures 3a, b, and c show the characteristics of silicon dioxide with respect to its average particle diameter. Figure 3 a, b,
In c, curve A shows the properties of the phosphor produced by the method of the present invention, and curve B shows the properties of the phosphor produced by the conventional method. FIG. 3a is a graph showing the minimum stripe width versus average particle size of spherical silicon dioxide. FIG. 3b shows the glass surface force versus the average particle size of spherical silicon dioxide. As is clear from FIG. 3b, it has been found that in the phosphor of the present invention, glass surface force blur increases whether the average particle size of the surface treatment substance particle size is too small or too large. Furthermore, FIG. 3C shows the relationship between the average particle size of the surface treatment material and the brightness. As is clear from this figure, high brightness can be obtained when the average particle diameter of the surface treatment substance is within a certain range, and it can be seen that the light emitted from the phosphor passes through the glass surface efficiently. However, in the measurements shown in FIGS. 3a to 3C, the method of the present invention used the following colloidal silica containing silicon dioxide to surface-treat the phosphor. ■ Microparticles of silicon dioxide contained in colloidal silica have a particle size of 80% by weight or more, D S / D L = 0.
As No. 9, one having a shape close to a sphere was used. ■ Furthermore, silicon dioxide in colloidal silica is Da
Particles with a particle size of v±0.4Dav accounted for 80% by weight or more of the total and had a sharp particle size distribution. ■ Colloidal silica with a low content of aggregated particles was used. Therefore, the colloidal silica used had a silica content of 1% by weight, a liquid pH of 1O, and a precipitate of 1% by weight or less after being allowed to stand for 48 hours. Granular silica, in which primary particles are aggregated, forms a precipitate at the bottom under the above conditions, but unaggregated primary particle silica does not precipitate. The surface of the phosphor manufactured using the conventional method was treated using colloidal silica as described below. ■ Silicon dioxide contained in colloidal silica is 80%
More than % by weight of particles have DS/DL=0.6. ■ Furthermore, silicon dioxide in colloidal silica is Da
Particles having a particle size of v±0.4Dav accounted for 50% by weight of the total. (2) The colloidal silica used had a silica content of 1% by weight, a liquid pH of 10, and was allowed to stand for 48 hours to form a precipitate of 10% by weight of silicon dioxide at the bottom. Further, the amount of silicon dioxide deposited on both curves A and B is 0.98% by weight based on 100 of the phosphor. From the measurement results shown in FIGS. 3a to 3c, the present invention specifies the average particle size of silicon dioxide adhering to the phosphor to be in the range of 50 mμ or more and 400 mμ or less. Further, in the method for producing a phosphor of the present invention, the ratio between the minimum particle size DS and the maximum particle size DL of silicon dioxide to be adhered to the surface is specified. In other words, silicon dioxide has a ratio of the major axis to the minor axis of 70% by weight or more of all particles.
It is specified that ≧DS/DL≧0.7. DS/DL is 0
．． Silicon dioxide having a particle size of 7 or less has a shape ranging from a spherical shape to an elliptical shape or an elongated shape. Perfectly spherical silicon dioxide does not change shape depending on its orientation on the surface of the phosphor. However, the orientation of the elliptical or elongated silicon dioxide attached to the surface of the phosphor changes depending on whether the major axis is oriented in the radial direction or in the tangential direction. Furthermore, in the phosphor manufacturing method of the present invention, the average particle diameter Dav of silicon dioxide adhering to the surface of the phosphor is specified. That is, the particle size distribution is specified to be extremely sharp so that 60% by weight or more of the particles are contained in a range of Dav±0.4Dav, or in other words, only ±40% of the average particle diameter. The DS/DL and Dav of silicon dioxide are determined by providing a silicon dioxide coating layer of substantially equal thickness over the entire surface of the phosphor, and in addition, more silicon dioxide is present in the coating of this thickness. This is to make it contribute to creating layers. Furthermore, the present invention uses silica with fewer aggregated particles to be attached to the surface of the phosphor. Silica in which primary particles are aggregated reduces the actual luminance of the phosphor, in other words, the luminance of the fluorescent film. This is because aggregated particles have more surface irregularities than primary particles, and this uneven surface scatters light. Silicon dioxide with fine particles of 50 mμ or less has a small content of aggregated particles, but silica with large particles of 50 mμ or more has a large content of aggregated particles. This is because large silica particles of 50 mμ or more have a particle size that is an agglomeration of microscopic silica particles. That is, in the case of silica having an average particle diameter of 50 mμ or more, silica of several tens of mμ aggregates to form granular silica of several hundred mμ, so even if sorted by particle size, the content of agglomerated particles tends to be high. For this reason, it is extremely important to reduce the content of aggregated particles in silica having a diameter of 50 mμ or more. Agglomerated particles and primary particles can be distinguished by leaving colloidal silica in a pH adjusting solution. Agglomerated particles of silica settle to the bottom at certain pH values. The lower the pH, the more easily the aggregated particles will precipitate, and the state of the precipitate also changes depending on the silica concentration. The colloidal silica used in this invention has a silica concentration of 1% by weight and a precipitate amount of 3% by weight at pH]o.
I'm using the following: Silica contained in colloidal silica, 50 to 400 m without agglomerated particles
μ silica hardly forms a precipitate under these conditions. An important requirement of this invention is to use colloidal silica that does not contain aggregated particles. In order to identify the presence or absence of aggregated particles, colloidal silica is allowed to stand under certain conditions. Colloidal silica that does not form a precipitate when aged under specific conditions does not contain aggregated particles or has an extremely low content of aggregated particles. When colloidal silica containing aggregated particles is allowed to stand still under the above conditions,
Agglomerated particles of silica settle to the bottom. In other words, the aggregated particles settle to the bottom and are sorted out. Therefore, if the aggregated particles that have settled on the bottom are removed and a supernatant liquid of colloidal silica that does not precipitate is used to adhere to the phosphor, the surface can be treated with no aggregated particles or with a very small amount of silica. That is, in the step of identifying aggregated particles, colloidal silica from which aggregated particles have been removed can be obtained. This colloidal silica can be used to surface-treat phosphors with silica free of agglomerated particles. The present inventors have determined that, in a phosphor provided with spherical silicon dioxide as a surface treatment substance, the minimum stripe width when changing the amount of surface treatment substance attached to the weight portion of the phosphor,
As a result of repeated consideration of glass surface strength and brightness,
It was confirmed that there is an optimal value within a certain range. If the amount of silicon dioxide deposited is too large, the brightness will decrease; on the other hand, if it is too small, the surface treatment effect will be decreased. The minimum stripe width, glass surface strength, and brightness are determined when the amount of silicon dioxide adhered is 0.000 parts by weight per 100 parts by weight of the phosphor.
The best properties are exhibited around 2 to 1.5 parts by weight. The amount of silicon dioxide deposited is usually adjusted within the range of 0.01 parts by weight to 3 parts by weight, taking into consideration characteristics such as minimum stripe width and brightness. It has been found that in the phosphor of the present invention, even if the luminance of the phosphor itself is the same, the light emitted from the glass surface coated with a phosphor film is brighter than that of a phosphor provided with a conventional surface treatment substance.

[effect]

The phosphor manufacturing method of the present invention simultaneously improves the three characteristics of minimum stripe width, glass surface blur, and relative brightness, which have long been desired but were extremely difficult to improve at the same time. It has been extremely successful. The excellent characteristics of the phosphor produced by the method of this invention are shown in Figures 3a and 3b. Shown in c. FIG. 3a shows the minimum stripe width relative to the average particle diameter of phosphors produced by the method of the present invention and the conventional method. As is clear from this figure, as shown by curve A, the phosphor produced by the method of the present invention has a lower Live width has been improved. FIG. 3b shows the glass surface force blur versus the average particle size. The phosphors produced by the method of the present invention have dramatically improved properties compared to those obtained by conventional methods. This poor property is the main reason why the surface treatment method for phosphors using microparticles of colloidal silica is unable to simultaneously satisfy the three properties of minimum stripe width, glass surface strength, and relative brightness. However, the method of the present invention succeeded in significantly improving this property despite using colloidal silica. For example, assuming that the glass surface strength of the phosphor produced by the conventional method is 1.0, the phosphor obtained by the method of the present invention has an average particle size of silicon dioxide of 50 mμ or more and 0.0.
It has achieved dramatically superior characteristics of 5 to 0.2. Furthermore, FIG. 3C shows the relative brightness with respect to the average particle size. This figure shows that although silicon dioxide, which itself does not emit light, is attached to the surface of the phosphor, the relative brightness of the coated phosphor has been mysteriously improved to more than 100%. are doing. The reason why the relative brightness of a phosphor can be improved by a coating layer that does not emit light is that the luminescence of the phosphor is efficiently irradiated to the outside, and the phosphor is efficiently stimulated by electron beams. The reason why this invention is able to improve all the characteristics of the phosphor, including the minimum stripe width, glass surface blur, and relative brightness, is that silicon dioxide contained in colloidal silica has been identified in a unique form. This is the reason. That is, the reason is that all the silicon dioxide attached to the surface of the phosphor effectively acts as a coating layer, and the scattering of light by the silicon dioxide on the surface of the phosphor is prevented. In a phosphor manufactured by a conventional method, fine particles of silica are attached between large particles of silica of 100 mμ or more in which primary particles are aggregated. In this state, the silicon dioxide attached to the surface of the phosphor is aggregated into large granular silica particles, which determines the substantial thickness of the coating film. Microscopic silicon dioxide distributed between large granular silica particles is
It is masked by the large particles of silicon dioxide and hidden between the particles of silica, and has no effect of forming a coating layer of a constant thickness on the surface of the phosphor. For this reason, in the case of a phosphor in which aggregated particles of granular silica and colloidal silica are adhered together, glass surface blur and minimum stripe width cannot be improved unless a large amount of silicon dioxide is attached. FIGS. 4a, b, and c show the minimum stripe width, glass surface force blur, and relative brightness with respect to the amount of silicon dioxide deposited. As is clear from these figures, the phosphor produced by the method of the present invention has improved minimum stripe width, glass surface blur, and relative brightness in areas with low silicon dioxide deposition. ．． In these figures, curve A shows the properties of the phosphor produced by the method of the present invention, and curve B shows the properties of the phosphor produced by the conventional method. In this measurement, the method of the present invention surface-treated the phosphor using colloidal silica containing silicon dioxide as described below. ■ Silicon dioxide contained in colloidal silica is 80%
More than % by weight of the particles have a DS/DL=0.9 and are extremely close to spherical. (2) The average particle diameter of silicon dioxide contained in colloidal silica was set to 130 mμ. ■ Silicon dioxide contained in colloidal silica is Da
Particles having a particle size of v±0.4Dav accounted for 80% by weight or more of the total. (2) Further, the colloidal silica used had a silica content of 1% by weight, a liquid pH of 1O, and a precipitate of 1% by weight or less after being allowed to stand for 48 hours. The surface of the phosphor manufactured using the conventional method was treated using colloidal silica as described below. (2) 80% by weight or more of particles of silicon dioxide contained in colloidal silica have a DS/DL=0.5. ■ Colloidal silica with a silica content of 0.3% by weight (
0.3% by weight of granular silica (average particle size 60 mμ)
(average particle size: 400 mμ) was added, and this liquid was used to adhere silicon dioxide to the surface of the phosphor. ■ Colloidal silica is a liquid with a silica content of 1% by weight, left to stand for 48 hours, and 10%
A material that produced a precipitate of silicon dioxide in a weight percent was used. FIG. 4a shows the minimum stripe width with respect to the adhesion amount of phosphors produced by the method of the present invention and the conventional method. FIG. 4b shows the glass surface force blur with respect to the amount of adhesion. Furthermore, FIG. 4C shows the relative brightness with respect to the amount of adhesion. As shown by curves HA in Figures 4a and b, the phosphor produced by the method of the present invention has a lower amount of silicon dioxide deposited and a minimum cost compared to that produced by the conventional method. Live width and glass surface force blur can be significantly improved. In particular, it is possible to dramatically improve glass surface force blur. The surface treatment method for phosphor using colloidal silica is as follows:
This poor characteristic was the biggest cause, and the three characteristics of minimum stripe width, glass surface force blur, and relative brightness could not be satisfied at the same time. However, the method of the present invention succeeds in significantly improving this property despite using colloidal silica. In FIG. 4b, the phosphor obtained by the method of the present invention has a silicon dioxide adhesion amount of 0.1 or more and a glass surface friction of 0.1. This can be dramatically improved from 5 to 0.2. Furthermore, FIG. 4C shows the relative brightness with respect to the amount of adhesion. This figure clearly shows that by depositing silicon dioxide on the surface of the phosphor, the relative brightness can be improved by as much as about 10%. That is, the present invention has mysteriously succeeded in improving the relative brightness of the coated phosphor, despite the attachment of silicon dioxide, which itself does not emit light. As described above, the reason why the phosphor of the present invention exhibits a remarkable effect compared to conventional products is that the phosphor forms a phosphor film in an almost ideal state. That is, since the phosphor of the present invention uses a specific silicon dioxide free of agglomerated particles as a surface treatment substance, all surface treatment substances effectively act on the surface treatment of the phosphor particles. In the case of phosphors produced using conventional methods, in addition to the masking of small particles by large silica particles, the surface of the phosphor is also covered with large silica particles of several hundred micrometers in size, which are aggregates of microparticles of silica and primary particles. Another reason for the deterioration of properties is that the surface of the phosphor is covered with a coating layer of uneven thickness, making it easier for the phosphors to aggregate and reducing dispersibility. . On the other hand, in the phosphor of the present invention, silicon dioxide can be uniformly deposited on the surface of the phosphor, so the dispersibility of the phosphor is improved. In addition to improving the dispersibility of this phosphor, when it is applied to a glass surface to form a phosphor film, uniform gaps are created between the phosphor particles due to silicon dioxide. To fill gaps between phosphors, apply phosphor to the glass surface.
To improve the passage of ultraviolet rays into the interior of the phosphor film when exposing and curing PVA. If the ultraviolet rays are sufficiently transmitted to the inside of the phosphor film and irradiated, the adhesion of the phosphor to the glass surface becomes good, and as a result, the minimum stripe width becomes smaller. Furthermore, the reduction in light scattering caused by silicon dioxide is one of the reasons why the phosphor particles can be strongly adhesively bonded. Spherical silicon dioxide, which does not contain aggregated particles, scatters less light than granular silica, which has aggregated primary particles. stomach. Silicon dioxide, which scatters less light, allows ultraviolet rays to efficiently penetrate into the interior of the phosphor film. In this state, the phosphor particles are firmly adhered to the sufficiently cured PVA. When irradiating a glass surface with an electron beam, the above two reasons combine to create uniform gaps between the phosphors, and ■ reduce scattering, so that the electron beam hits the phosphor film. Infiltrate efficiently. This means that the electron beam does not only affect the surface of the fluorescent film on the irradiated side.
Even the phosphor near the glass surface located inside the phosphor on the irradiation side is efficiently excited and emitted light efficiently. In addition to this, the light emitted from the excited phosphor is efficiently transmitted through the coating layer. This is because the scattering of light by the silicon dioxide forming the coating layer is reduced. Therefore, even if the emitting phosphor is located far from the glass surface, it is efficiently transmitted toward the glass surface. As a result, the brightness becomes higher than before. Furthermore, uniformity of the metal back applied to the surface of the phosphor layer is also effective in improving brightness. it is,
The phosphor of this invention can be formed into a coating film that is evenly distributed, so the back surface of the phosphor film (the surface of the electron gun example) can be made smoother, which is why the metal back can be made uniform. It is. Furthermore, it is thought that the shape of the silicon dioxide of the present invention also affects the glass surface tension. During the manufacturing process of cathode ray tubes, when the unexposed areas of the phosphor are washed away, the phosphor that has spherical silicon dioxide attached to it with a certain particle size is difficult to adhere to the previously formed stripes and dots and the glass surface. Easily washed away. If you consider that silicon dioxide acts like a roller, it will be easier to understand why it is easier to wash and there is less fog.

[Preferred embodiment]

Examples of the present invention will be described below. (Example 1) A phosphor to which silicon dioxide is attached as a surface treatment material is manufactured in the following steps. ■ Green-emitting phosphor (ZnS: Au, Cu, AQ)
Add 3.0 kg of pure water to the mixture and stir well. ■ Add colloidal silica and 10% zinc sulfate aqueous solution to the phosphor suspension while stirring well. The amount of colloidal silica added is 30 ml, and the silica content is 0.6 parts by weight per 100 parts by weight of the phosphor. This colloidal silica contains silicon dioxide with an average particle diameter of 130 mμ. Further, the particle size distribution of silicon dioxide contained in colloidal silica is shown in FIG. This colloidal silica has a Day±0.
4Dav, i.e. l30±5 2 m It
60% by weight of the particle size is included in the range of 78 to 182 mμ. The amount of acid-breaking zinc aqueous solution added was 3 mjl, and the phosphor was 100 mjl.
The zinc content relative to parts by weight is 0.03 parts by weight. (2) While further stirring the liquid to which colloidal silica and zinc sulfate aqueous solution have been added, an alkali aqueous solution is added to adjust the pH to 7.4. Ammonia water can be used as the alkaline aqueous solution. ■ After standing for a certain period of time, the supernatant liquid is removed by decantation, the precipitate is dehydrated and heated to 110°C to 120°C.
Then, dry for 8 to 15 hours and separate through a sieve. The thus obtained phosphor had spherical silicon dioxide adhered to its surface. The surface condition of the phosphor obtained in this step is shown in FIG. 1a. For reference, FIG. 2 shows an electron micrograph of a phosphor manufactured by a conventional method. The obtained phosphor has a weight ratio of 0.5 to 100 parts by weight of the phosphor.
9 parts by weight of silicon dioxide was attached. 0.59 parts by weight of silicon dioxide was deposited. Furthermore, when this phosphor was observed under an electron microscope, it was found that silicon dioxide was uniformly dispersed and adhered to the surface. The attached silicon dioxide has a DS/DL of 80% by weight or more of particles of 0. It had a shape extremely close to a sphere, with a rating of 9 or more. When we measured the minimum stripe width, glass surface force blur, and brightness for this phosphor, we found that: ■ Minimum stripe width was 144 μm, ■ Glass surface force blur was 0.25, and ■ Relative brightness was 109%, compared to conventional products. The minimum stripe width was reduced by 36 μm, the glass surface force blur was reduced by 75%, and the brightness was increased by 9%. (Example 2) A phosphor to which silicon dioxide is attached as a surface treatment material is manufactured in the following steps. ■ Green-emitting phosphor (ZnS: Cu, All) 1k8
Add pure water and stir well. (2) While stirring the phosphor suspension well, add colloidal silica, 10% zinc sulfate aqueous solution, and 2% aluminum nitrate aqueous solution. This colloidal silica contains silicon dioxide with an average particle diameter of 60 mμ. Further, the particle size distribution of silicon dioxide contained in colloidal silica is shown in FIG. This colloidal silica has Dav±0.4
Dav, i.e. 36-84m which is 60±24mμ
The μ range includes 80% by weight or more of the particle size. The amount of colloidal silica added is 40 mM, and the content of silica is 0.8 parts by weight per 100 parts by weight of the phosphor. The amount of the zinc sulfate aqueous solution added is 2 mQ, and the zinc content is 0.02 parts by weight with respect to 100 parts by weight of the phosphor. The amount of aluminum nitrate aqueous solution added was 5 mα, and the aluminum content was 0.01 with respect to 100 parts by weight of the phosphor.
Weight%. (2) While further stirring the liquid to which colloidal silica and zinc sulfate aqueous solution have been added, an alkali aqueous solution is added to adjust the pH to 7.4. Ammonia water can be used as the alkaline aqueous solution. ■ After standing still for a certain period of time, the supernatant liquid was removed by decantation, the precipitate was dehydrated and heated to 110°C to 120°C.
Dry at ℃ for 8 to 15 hours and sieve. The thus obtained phosphor had silicon dioxide attached to its surface. The surface condition of the phosphor obtained in this step is shown in FIG. 1b. The obtained phosphor has a weight ratio of 0.7 to 100 parts by weight of the phosphor.
8 parts by weight of spherical silicon dioxide were deposited. Also,
When this phosphor was observed under an electron microscope, it was found that silicon dioxide was uniformly dispersed and adhered to the surface. The silicon dioxide on the surface has a DS/DL of 0.80% by weight or more of the particles.
It had a shape extremely close to a sphere, with a rating of 9 or more. When we measured the minimum stripe width, glass surface force blur, and brightness for this phosphor, we found that: (1) the minimum stripe width was 142 μm; (2) the glass surface force blur was 0. 2. ■ The relative brightness is 110%, the minimum stripe width is 38 μm thinner than the conventional product, the glass surface force blur is reduced by 80%, and the brightness is 10% brighter. (Example 3) A phosphor to which silicon dioxide is attached as a surface treatment material is manufactured in the following steps. ■ Add 3 ml of pure water to 1 kg of green-emitting phosphor (ZnS: Ag, CQ) and stir well. ■ Add colloidal silica and 10% zinc sulfate aqueous solution while stirring the phosphor suspension well. The amount of colloidal silica added is 50 rrl, and the content of silica is 1 part by weight per 100 parts by weight of the phosphor. The amount of zinc sulfate aqueous solution added was 3 m, and the phosphor was 100 m.
The zinc content relative to parts by weight is 0.03 parts by weight. This colloidal silica contains silicon dioxide with an average particle diameter of 240 mμ. This colloidal silica has Dav±0.4Dav, that is,
In the range of 144 to 336 mμ, which is 240 ± 96 mμ,
It contains about 60% by weight or more of particle size. (2) While further stirring the liquid to which colloidal silica and fF [zinc aqueous solution have been added, an alkaline aqueous solution is added to adjust the pH to 7.4. Ammonia water can be used as the alkaline aqueous solution. ■ After standing still, the supernatant liquid was removed by decantation, the precipitate was dehydrated, and the mixture was heated at 110°C to 120°C for 8
~3:00 p.m. Dry and separate through a sieve. The thus obtained phosphor had silicon dioxide attached to its surface. The obtained phosphor has a weight ratio of 0.9 to 100 parts by weight of the phosphor.
8 parts by weight of spherical silicon dioxide were deposited. The silicon dioxide adhering to the surface of this phosphor had a shape extremely close to spherical, with D S/D L of 80% by weight or more of the particles being 0.9 or more. Minimum stripe width for this phosphor, glass surface cover 1
When the bar brightness was measured, ■ the minimum stripe width was 145 μm1 ■ the glass surface force blur was 0.4, ■ the relative brightness was 108%, and the minimum stripe width was 35 μm thinner than the conventional product, and the glass surface force blur was It decreased by 60% and the brightness became 8% brighter. (Example 4) A phosphor to which silicon dioxide is attached as a surface treatment material is manufactured in the following steps. ■ Red light-emitting phosphor (Y202S: E u ) 1
Add pure water to 3 kg and stir well. (2) While stirring the phosphor suspension well, add colloidal silica, 10% zinc sulfate aqueous solution, and 2% aluminum nitrate aqueous solution. The amount of colloidal silica added is 50rnQ, and the content of silica is 1 part by weight per 100 parts by weight of the phosphor. This colloidal silica contains silicon dioxide with an average particle diameter of 400 mμ. This colloidal silica has Dav±0.4Dav, that is, 4
In the range of 240 to 560 mμ, which is 00 ± 160 mμ,
Contains 75% by weight of particle size. The amount of the zinc sulfate aqueous solution added is 2m, and the zinc content is 0.02 parts by weight with respect to 100 parts by weight of the phosphor. The amount of aluminum nitrate aqueous solution added was 5 m, and the aluminum content was o. oi
Weight%. (2) While further stirring the liquid to which colloidal silica and zinc sulfate aqueous solution have been added, an alkali aqueous solution is added to adjust the pH to 7.4. Ammonia water can be used as the alkaline aqueous solution. ■ After standing still, the supernatant liquid was removed by decantation, the precipitate was dehydrated, and the mixture was heated at 110°C to 120°C for 8
~3:00 p.m. Dry and separate through a sieve. The thus obtained phosphor had silicon dioxide attached to its surface. The silicon dioxide adhering to the surface of this phosphor had a shape close to 80% by weight or more. The obtained phosphor has a weight ratio of 0.9 to 100 parts by weight of the phosphor.
5 parts by weight of spherical silicon dioxide were deposited. When we measured the minimum stripe width, glass surface force blur, and brightness for this phosphor, we found that: (1) the minimum stripe width was 15,571 m; (2) the glass surface force blur was 0. 5. ■ The relative brightness is 108%, the minimum stripe width is 25 μm thinner than the conventional product, the glass surface force blur is reduced by 50%, and the brightness is 8% brighter.

[Brief explanation of the drawing]

Figures 1a and 1b are 3300x electron micrographs of the phosphors obtained in Examples 1 to 2, and Figure 2 is a photograph of conventional ultrafine, flat-grained silicon dioxide. 3300x electron micrograph of attached phosphor, Figure 3 a-C
is a graph showing the minimum stripe width of the phosphor with respect to the particle size of silicon dioxide, the minimum stripe width of the phosphor with respect to the glass surface cover, the glass surface strength, and the relative brightness. A graph showing the minimum stripe width of the phosphor, glass surface force blur, and relative brightness with respect to the adhesion amount of silicon. The fifth graph is a graph showing the particle size distribution of colloidal silica used in Example 1. Figure 6 is a graph showing the particle size distribution of the colloidal silica used in Example 1. 2 is a graph showing the particle size distribution of colloidal silica used in .

Claims (1)

[Claims] In a method for producing a phosphor to which silicon dioxide is attached by using colloidal silica and attaching it to the surface of a phosphor with an adhesive, the following is applied to the silicon dioxide attached to the surface of the phosphor: A method for producing a phosphor, characterized by using a phosphor that satisfies the following conditions. (a) Colloidal silica for attaching silicon dioxide to the surface of the phosphor contains spherical silicon dioxide. For spherical silicon dioxide, the maximum particle size is DL, and the minimum particle size is D.
When S, 70% by weight or more of the entire particles satisfy 1≧DS/DL≧0.7. (b) Fine particles of silicon dioxide contained in colloidal silica have an average particle diameter of 50 mμ or more and 400 mμ or less. (c) When the average particle diameter of the particles is Dav, Da
Particles having a particle size of v±0.4Dav account for 60% by weight or more of the total. (d) Colloidal silica has a silica content of 1% by weight.
, the pH of the liquid is set to 10, the liquid is allowed to stand for 48 hours, and the precipitate is 3% by weight or less of the total weight of the silica.