JPH10298546A - Fluorescent substance and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to obtain a fluorescent substance capable of enhancing adhesive force of a fluorescent film to a base material and preventing generation of intermixed colors at the same time by adhering precipitated powdery spherical silicon dioxide on the surface of fluorescent particles by a specific method. SOLUTION: This production of fluorescent substance comprises suspending a fluorescent substance and a treating agent (preferably a 1-4C tetraalkoxysilane such as tetramethoxysilane) selected from a tetraalkoxysilane and its partially hydrolyzed condensate in an alcohol (preferably an alcohol corresponding to the alcohol contained in the treating alcohol), adding an alkaline solution (preferably, a solution of sodium hydroxide, potassium hydroxide or ammonium hydroxide) and precipitating and adhering powdery spherical silicon dioxide on the surface of particles of fluorescent substance. The particle size of the silicon dioxide is preferably brought to 0.05-1 μm. The amount of adhered powdery silicon dioxide is preferably 0.1-1 wt.% based on the fluorescent substance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor and a method for producing the same, and more particularly, to a phosphor which has been subjected to a surface treatment so that a good phosphor film can be formed on a face plate, and a method for producing the same.

[0002]

2. Description of the Related Art As is well known, a fluorescent film of a color picture tube is formed by illuminating blue, green and red light-emitting dots or stripes made of phosphors, which are blue, green and red light-emitting components, by an optical printing method. They are arranged repeatedly and regularly on the face plate. In manufacturing a fluorescent film of a color picture tube by such an optical printing method, the following is required. That is: (1) The fluorescent film is dense and has few pinholes,
(2) no color mixing occurs; (3) good formation of luminescent pixels; (4) strong adhesion of the phosphor film to the substrate; and (5) high sensitivity of the phosphor slurry exposure. The workability is good.

Conventionally, various studies have been made on the surface treatment of phosphors, the composition of phosphor slurries, and the like, with the aim of satisfying the above requirements.
As a surface treatment method, a method is known in which a phosphor is suspended in an aqueous solution of colloidal silica, filtered, dehydrated, and then dried to attach silicon dioxide to the particle surface of the phosphor.

[0004]

In recent years, in a color picture tube, there has been an increasing demand for improving the image quality, and finer pixels have been formed on a plate so that a highly minute screen can be formed. It is necessary to: In order to meet this demand, it is necessary to simultaneously satisfy that the adhesion of the fluorescent film to the panel is strong and that no color mixing occurs. However, in the conventional method of applying the phosphor slurry, in order to increase the adhesive strength of the phosphor to the panel, a method of increasing the drying temperature after application or extending the drying time is employed. For this reason, as the adhesive strength of the fluorescent film to the base material is increased, there is a disadvantage that the fluorescent material remains in unnecessary portions and causes color mixing. Further, in the phosphor to which silicon dioxide is adhered by the colloidal silica treatment as described above, the adhesion between the silicon dioxide and the phosphor is weak, and a sufficiently satisfactory result has not been obtained.

An object of the present invention is to solve the above problems,
An object of the present invention is to provide a phosphor capable of simultaneously enhancing the adhesion of a phosphor film to a base material and preventing the occurrence of color mixing, and a method for producing the phosphor.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted studies to achieve the above object, and as a result, spherical silicon dioxide powder has been formed on the surface of phosphor particles in a suspension of the phosphor. It was found that the adhered substance had the above-mentioned preferable characteristics when forming the fluorescent film, and the present invention was completed.

That is, the phosphor of the present invention is characterized in that spherical silicon dioxide powder having a particle size of 0.05 to 1.0 μm adheres to the particle surface of the phosphor. In order to obtain a phosphor to which such spherical silicon dioxide powder is adhered, the production method of the present invention comprises: a phosphor and a treating agent selected from the group consisting of tetraalkoxysilane and a partially hydrolyzed condensate thereof. Suspended in alcohol, and added with an alkaline solution.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The phosphor used in the present invention may be of any kind, but the effect of the present invention is best exhibited while increasing the adhesive strength of the phosphor film to the substrate. It is a phosphor for a color picture tube that needs to prevent color mixing.

The treating agent for the phosphor is selected from the group consisting of tetraalkoxysilane and a partially hydrolyzed condensate thereof, and a mixture of both may be used. Thus, tetraalkoxysilane is preferred. The alkyl group of the tetraalkoxysilane is preferably one having 1 to 4 carbon atoms from the viewpoint of reactivity. As such a tetraalkoxysilane,
Examples include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane, and the alkyl group in tetrapropoxysilane and tetrabutoxysilane may be linear or branched.

The amount of the treating agent is preferably from 0.1 to 20% by weight, more preferably from 0.1 to 20% by weight, based on the phosphor, in order to adhere an effective amount of the spherical silicon dioxide powder to the surface of the phosphor particles. 3 to 10% by weight.

In the method for producing a phosphor of the present invention, first, the phosphor and the above-mentioned treating agent are suspended in alcohol. As alcohol, methanol, ethanol,
Examples are propanol, isopropanol, n-butanol, isobutanol, sec-butanol and tert-butanol. When the alcohol after the treatment is reused, it is preferable to use the alcohol corresponding to the alkyl group contained in the treatment agent, since the alcohol by-produced by the reaction can be reused while being mixed.

Next, an alkaline solution is added to the suspension while stirring, whereby spherical silicon dioxide powder is precipitated on the surface of the phosphor particles from the treating agent, tetraalkoxysilane or its partially hydrolyzed condensate. . Here, the term “spherical” refers to a smooth shape having no outside corners, ridges, or edges, such as a true sphere, a spheroid, and a shape close to the spheroid, having a ratio of major axis / minor axis of 1.0. -1.5 is preferable, and a true sphere is most preferable.

The alkaline solution is not particularly limited as long as it exhibits an alkaline property, and may be an aqueous solution of lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium hydrogen carbonate, or the like, an alcohol solution, an alcoholic aqueous solution, or the like. Illustrative are solutions of sodium hydroxide, potassium hydroxide or ammonium hydroxide.
As the alcohol used as the solvent, a lower alcohol that is compatible with water is preferable.

Although the precipitation temperature is limited by the boiling point of the alcohol used, it is usually 20 to 100 ° C. Within a range not exceeding the boiling point of the alcohol, the higher the precipitation temperature, the more spherical silicon dioxide powder is obtained. When the precipitation is performed at the boiling point of alcohol or a temperature close to the boiling point, it is preferable to use a precipitation tank provided with a reflux cooling device.

According to such a method, spherical silicon dioxide powder can be deposited and adhered on the particle surface of the phosphor. The particle size of silicon dioxide gives the phosphor an adhesive force,
In order to form a fluorescent film having good adhesion to a substrate without causing color mixing, the thickness is in the range of 0.05 to 1.0 μm as described above. In addition, the amount of the spherical silicon dioxide powder adhered to the particle surface of the phosphor in this way is 0.05 to 5.0 of the phosphor in order to impart the above properties to the phosphor.
%, More preferably 0.1 to 1.0% by weight. If the amount is less than 0.05% by weight, sufficient adhesiveness cannot be provided. If the amount exceeds 5.0% by weight, agglomeration occurs when preparing a phosphor slurry for application. Cheap.

The phosphor particle surface of the phosphor of the present invention and the phosphor in an aqueous colloidal silica solution are added and mixed by stirring, so that the particle surface of the phosphor having silicon dioxide adhered to the surface can be increased by 10,000 times. When observed and compared with an electron microscope, the silicon dioxide powder formed by the conventional surface treatment method using colloidal silica is irregular, and has low adhesion to the phosphor. On the other hand, in the phosphor of the present invention, spherical silicon dioxide powder is stably and firmly adhered to the surface.

[0017]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples. In the examples, “parts” indicates “parts by weight”. The present invention is not limited by these examples.

The coating properties of the phosphors obtained in Examples and Comparative Examples were evaluated by the following coating tests. That is, the panel was equipped with a shadow mask, exposed to a specific dose of ultraviolet light, exposed, and then developed with water to observe the state of stripe attachment on the plate. 20mJ
The stripe width when an exposure amount of / cm ² was given was determined, and the minimum width of the stripe width formed when the exposure amount was reduced and the exposure amount at that time were determined.

The evaluation of color mixture (cross contamination) was performed as follows. That is, after forming a stripe with a green light emitting phosphor, a phosphor as a sample was applied and developed without exposure. Then, in the state where the sample was irradiated with the ultraviolet rays, the light amount ratio between the fluorescence from the sample and the green fluorescence was obtained, and the relative light amount was set to 1 with the light amount ratio of the comparative sample treated with the corresponding aqueous colloidal silica solution.

Example 1, Comparative Example 1 To 2,370 parts of ethanol heated to 50 ° C. was added ZnS:
1,000 parts of an Ag blue light emitting phosphor was added and sufficiently suspended. 56 parts of tetraethoxysilane was added thereto, and the mixture was again stirred well and suspended. Next, 776 parts of a 2% aqueous sodium hydroxide solution was added, and stirring was further continued for 2 hours.
After allowing the phosphor to settle by standing for 10 minutes, the supernatant was discharged by decantation and washed once with deionized water. Then, after filtering the phosphor, dehydrated,
It was dried at 120 ° C. for 10 hours and passed through a 300-mesh sieve to obtain the surface-treated phosphor of Example 1. Observation of the particle surface of this phosphor with an electron microscope revealed that spherical silicon dioxide powder having an average particle diameter of 0.6 μm adhered to the particle surface, and the amount of the adhered powder was 0.30% by weight based on the phosphor. Met.

As Comparative Example 1, the same blue light emitting phosphor as used in Example 1 was suspended in an aqueous colloidal silica solution, so that 0.30% by weight of silica adhered to the phosphor was treated with colloidal silica. A phosphor was obtained.

Using the surface-treated phosphor obtained in Example 1 and Comparative Example 1 and an ordinary aqueous solution of polyvinyl alcohol containing ammonium dichromate, a phosphor slurry was prepared by an ordinary method. A coating test was performed using the obtained phosphor slurry, and the photosensitive performance, panel adhesion performance, and color mixing of the fluorescent film were evaluated. Table 1 shows the results.
Shown in

[0023]

[Table 1]

Example 2 and Comparative Example 2 Y ₂ O ₂ was added to 2,370 parts of ethanol heated to 50 ° C.
S: 1,000 parts of Eu red light emitting phosphor was added and sufficiently suspended. Add 41 parts of tetramethoxysilane to this,
The mixture was again well stirred and suspended. Next, 776 parts of a 10% aqueous sodium hydroxide solution was added, stirring was further continued for 2 hours, and the mixture was left standing for 10 minutes to settle the phosphor. Then, the supernatant was discharged by decantation, and washed with deionized water. Was performed once. Next, the phosphor was filtered, dehydrated, dried at 120 ° C. for 10 hours, and passed through a 300-mesh sieve to obtain the phosphor of Example 2. The surface-treated phosphor had a spherical silicon dioxide powder having an average particle diameter of 0.5 μm adhered to the particle surface, and the amount of the adhered was 0.25% by weight based on the phosphor.

As Comparative Example 2, the same red light-emitting phosphor as used in Example 2 was suspended in an aqueous colloidal silica solution, so that 0.25% by weight of silica adhered to the phosphor was treated with colloidal silica. A phosphor was obtained.

The same tests as in Example 1 and Comparative Example 1 were performed on the phosphors obtained in Example 2 and Comparative Example 2. Table 2 shows the results.

[0027]

[Table 2]

As is clear from the results shown in Tables 1 and 2, the phosphor of the present invention has higher photosensitivity and adhesiveness than conventional phosphors having silica adhered in an aqueous colloidal silica solution, and Color mixing is unlikely to occur.

[0029]

According to the present invention, it is possible to obtain a phosphor in which spherical silicon dioxide powder is firmly adhered to the particle surface of the phosphor. By forming a phosphor film using the phosphor of the present invention, the adhesive strength of the phosphor film to the substrate is improved, and color mixing can be prevented.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tomohito Inoue 3583-5 Kawajiri, Yoshida-cho, Haibara-gun, Shizuoka Prefecture Inside Toshiba Oigawa Center Co., Ltd. (72) Inventor Yohei Shimizu 7-1, Nisshincho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture East Shiba Electronics Engineering Co., Ltd.

Claims (6)

[Claims] 1. A phosphor particle surface characterized by suspending a phosphor and a treating agent selected from tetraalkoxysilane and a partially hydrolyzed condensate thereof in an alcohol and adding an alkaline solution. A method for producing a phosphor to which a spherical silicon dioxide powder deposited on a substrate is adhered. 2. The method according to claim 1, wherein the tetraalkoxysilane is tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane or tetrabutoxysilane. 3. The method according to claim 1, wherein the alkaline solution is a solution of sodium hydroxide, potassium hydroxide or ammonium hydroxide. 4. A phosphor having a particle size of 0.05 to
1. A phosphor to which 1.0 μm spherical silicon dioxide powder is attached. 5. The phosphor according to claim 4, wherein the spherical silicon dioxide powder adheres to the phosphor in an amount of 0.05 to 5.0% by weight. 6. The phosphor according to claim 4, wherein the phosphor is a phosphor for a color picture tube.