KR100516934B1 - Method of fabricating fluorescent material of plasma display panel - Google Patents

Abstract

The present invention relates to a method of manufacturing a phosphor of a plasma display panel to extend the life of the plasma display panel.

According to an embodiment of the present invention, there is provided a method of manufacturing a phosphor of a plasma display panel, the method comprising dispersing a phosphor powder in a liquid containing alcohol and a sol-gelation reaction of a starting material for forming a silica coating film in a liquid in which the phosphor powder is dispersed. Injecting a catalyst for inducing a, and the sol-gelling the starting material into the liquid to cause a sol-gelling reaction between the starting material, and the silica coating film produced as a result of the reaction between the starting material Separating the phosphor formed on the surface from the liquid, and firing the silica coating film and the phosphor.

Description

Phosphor manufacturing method of plasma display panel {METHOD OF FABRICATING FLUORESCENT MATERIAL OF PLASMA DISPLAY PANEL}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display panel, and more particularly, to a method of manufacturing a phosphor of a plasma display panel to extend the life of the plasma display panel.

Plasma Display Panels (hereinafter referred to as "PDPs") generally emit fluorescence by 147 nm vacuum ultraviolet rays generated when an inert mixed gas such as He + Xe, Ne + Xe, He + Xe + Ne is discharged. An image is displayed. Such a PDP is a display device that is attracting attention as a large area flat panel display due to its easy thin and large size. Recently, Korean and Japanese companies have begun commercial production, expanding the market, and improving image quality due to technology development.

Referring to FIG. 1, a discharge cell of a three-electrode AC surface discharge type PDP includes a sustain electrode pair 9 formed on an upper substrate 1, and an address electrode X formed on a lower substrate 2. .

Each of the sustain electrode pairs 9 includes a transparent electrode such as indium tin oxide (ITO), a metal bus electrode having a line width smaller than that of the transparent electrode, and formed at one edge of the transparent electrode. . The metal bus electrode is formed by laminating Cr / Cu / Cr by vapor deposition and then etching. The upper dielectric layer 6 and the protective layer 7 are stacked on the upper substrate 1 on which the sustain electrode pairs 9 are formed by screen printing or vacuum deposition. In the upper dielectric layer 6, wall charges generated during plasma discharge are accumulated. The protective layer 7 is formed on the upper dielectric layer 6 to a thickness of approximately 5000 Å to prevent damage to the upper dielectric layer 6 and the sustain electrode pair 9 due to sputtering generated during plasma discharge. This increases the emission efficiency of the secondary electrons. As the protective layer 7, magnesium oxide (MgO) is usually used.

The lower dielectric layer 4 and the partition wall 3 are formed on the lower substrate 2 on which the address electrode X is formed, and the phosphor 5 is formed on the surfaces of the lower dielectric layer 4 and the partition wall 3 by a screen printing process. do. The address electrode 2 is orthogonal to the sustain electrode pair 9. The partition wall 3 is formed by a screen printing process, a mold method, or the like to prevent ultraviolet rays and visible light generated by the discharge from leaking into adjacent discharge cells. The phosphor 5 is excited by vacuum ultraviolet (VUV) generated during plasma discharge of the mixed gas injected into the discharge cell to generate visible light of any one of red, green, and blue.

The phosphor 5 is excited by vacuum ultraviolet (VUV) light, and is divided into a red phosphor, a green phosphor, and a blue phosphor according to the wavelength of light emitted.

Referring to FIG. 2, a red phosphor generally used in PDP is (YGd) BO ₃ : Eu ³⁺ , and a green phosphor is Zn ₂ SiO ₄ : Mn ²⁺ . The composition of the blue phosphor is BaMgAl ₁₀ O ₁₇ : Eu ³⁺ . These phosphors are directly exposed to the mixed gas applied on the partition 3 of the PDP and filled in the discharge space. However, since the phosphor has a charging characteristic, crystal destruction easily occurs due to sputtering of the cation generated during discharge, that is, the impact caused by the cation, and as a result, the degradation of the phosphor rapidly decreases as the luminance of the phosphor elapses. In particular, since the cations generated during discharge have a larger mass than the anions, the impact energy applied to the phosphor is very large. The lowering of the luminance of the phosphor as described above causes the lifetime of the PDP. Therefore, it is pointed out as a preemptive agent to reduce the deterioration of the phosphor by enhancing the anti-sputtering or impact resistance of the phosphor in order to extend the life of the PDP.

Accordingly, a method of preventing the deterioration of the phosphor by applying a thin film coating on the surface of the phosphor using a material protecting the phosphor is described in Korean Patent Publication No. 2002-025483.

The phosphor protection method described here is a method of first preparing a silica gel as a phosphor protective material as shown in FIG. 3, and then contacting the phosphor particles with a silica gel prepared in advance to coat a protective film, which is a SiO ₂ thin film, on the surface of the phosphor.

When described step by step, first, a tetra-alkyl ortho-silicate (hereinafter referred to as "TEOS") solution containing an organic solvent and water is prepared (step S31). Polar organic solvents such as ketones, esters and ethers are preferred, of which alcohols are more preferred. Suitable alcohols include lower alcohols such as methanol, ethanol, isopropanol or butanol, with ethanol, isopropanol or mixtures thereof being preferred.

It is preferable that an excess amount of water be used as compared to SiO ₂ generated during the post process. Accordingly, the molar ratio of TEOS, which is a starting material (precursor; referred to as "starting material") on which the SiO ₂ coating film is formed, is about 10: 1 or more, preferably about 100: 1 or more, and about 300: 1. desirable.

In addition, as any suitable starting material for SiO ₂ , a silicone compound may be used, with a silicon organic compound being preferred. Preferred here are silicon alkoxides, which are preferably starting materials which produce a gel at a high rate and can be easily removed from SiO ₂ by evaporation or oxidation. Suitable silicon alkoxides include TEOS having an alkyl group of about 1 to 6 carbon atoms. Thus, TEOS is used as the preferred starting material of SiO ₂ .

The TEOS solution formed in step S31 is adjusted to pH 4 to 10. (Step S32) The pH of the formed solution affects the quality of the coating film finally formed on the phosphor. In detail, the TEOS solution should be adjusted to pH 4 to 10 and preferably adjusted to pH 5 to 8, more preferably to a neutral pH (eg pH 7.5). Is formed. Base is used to adjust the pH of the TEOS solution. Suitable bases include ammonia or ammonium hydroxide and urea.

After adjusting the pH of the TEOS solution, the solution is heated (step S33). Here, the TEOS solution is heated under reflux in a reflux container.

In step S33, the TEOS solution subjected to the heating process is hydrolyzed to produce a gel. (S34) The hydrolysis reaction may be accelerated by heating the starting material TEOS solution. At this time, the heating temperature is in the range of 40 ° C to 100 ° C, preferably 50 ° C to 85 ° C. The heating is performed until the hydrolysis is sufficient and the heating time is correlated with temperature since the rate of hydrolysis increases with temperature. In other words, when the temperature is high, the heating time is shortened. Thereby, the precursor solution is heated for at least 0.1 hour, which is heated in the range of 1 hour to 72 hours and preferably for 10 hours to 30 hours, more preferably 20 hours to 24 hours.

When the gel is formed in step S34, a phosphor powder is prepared to contact the gel. Particle powder having a size of or greater than).

The phosphor powder prepared in step S35 is brought into contact with the gel obtained in step S34 (step S36). This contacting is performed by stirring the phosphor particles in a solution.

After the phosphor is contacted with the silicon hydroxide gel, the gel-coated phosphor and the gel solution are separated (step S37). The gel-coated phosphor is separated from the gel solution by filtration.

The gel-coated phosphor separated in step S37 is dried (step S38). The drying process is performed to remove the solvent adsorbed on the gel-coated phosphor, and is performed in air, in vacuum, or in an inert gas. The temperature at which the drying process is carried out is 60 ° C to 150 ° C, preferably 80 ° C to 120 ° C, which is 30 ° C or higher.

The dried gel-coated phosphor is calcined (step S39). At this time, a calcining process is performed to increase the binding force of the gel to the phosphor particles. The firing temperature is 250 ° C to 120 ° C, preferably 400 ° C to 1000 ° C, which is 200 ° C or higher. The firing process is carried out in air or in vacuum or inert gas / reduced gas and preferably in reducing gas.

In fact, the coating phosphor which was finally formed by the above firing process was found to have a very low drop in relative luminance of less than 20% and an improvement in lifespan characteristics of 10% or more.

This will be described in detail with reference to FIGS. 4 to 5.

Referring to FIG. 4, the change in the relative luminance of the coated phosphor on the Y axis is shown as the pH changes on the X axis. In addition, the temperature for firing the coating phosphor was set to 400 ℃ and 800 ℃ to form a trend line according to the data according to the experimental results under each temperature. At this time, the luminance decrease of the coating phosphor is less than 20% at 400 ℃, the higher the pH, the higher the relative luminance of the coating phosphor. In addition, at 800 ° C., the luminance decrease of the coating phosphor is less than 10%, and as the pH is lower, the relative luminance of the coating phosphor increases. As a result, the higher the pH at which the coating film is formed when the firing temperature is 400 ° C., the coating film formed on the surface of the phosphor is formed in a film-like film, thereby increasing the relative luminance.

5, the relative luminance (Y-axis) change of the phosphor is illustrated according to the weight fraction (wt%) (X-axis) of the silicon alkoxide included when the coating film is formed. When the wt% of silicon alkoxide falls in the range of 0 wt% to 10 wt%, the relative luminance of the coated phosphor is maintained at 80% level. Therefore, it can be seen that a coating film containing 10 wt% or less of silicon alkoxide is suitable as a protective film of the phosphor.

However, the method has a disadvantage in that it is difficult to uniformly form the silica gel on the surface of the phosphor particles because the silica gel in a state of very high viscosity is in direct contact with the phosphor particles. As such, since the silica coating film is hardly formed to have a uniform thickness on the phosphor, not only the coating film thickness is uneven, but even a coating film may not be formed on some surfaces of the phosphor. When the silica coating film is unevenly formed on the phosphor, deterioration of the phosphor proceeds relatively quickly in a portion where the thickness of the silica coating film is thin or in the absence of the silica coating film, thereby shortening the lifetime of the PDP.

Accordingly, it is an object of the present invention to provide a method for producing a phosphor of a PDP to extend the life of the PDP.

In order to achieve the above object, the phosphor manufacturing method of the PDP according to an embodiment of the present invention comprises the steps of dispersing the phosphor powder in a liquid containing alcohol, and the starting material for forming a silica coating film in the liquid in which the phosphor powder is dispersed Introducing a catalyst for inducing a sol-gelation reaction, introducing the sol-gelled starting material into the liquid to cause a sol-gelling reaction between the starting materials, and a reaction between the starting materials Separating the phosphor formed on the surface of the resulting silica coating film from the liquid, and calcining the silica coating film and the phosphor. In the present invention, the phosphor powder is (YGd) BO ₃ : Eu ³⁺ , Zn ₂ SiO ₄ : Mn ²⁺ , BaMgAl ₁₀ O ₁₇ : Eu ³⁺ .

delete

delete

In the present invention, the liquid contains at least one of distilled water and alcohol.

In the present invention, the alcohol has a chemical formula of C _n H _{2n + 1} OH and n = 5 or less.

In the present invention, the catalyst is any one of ammonia, sodium hydroxide and urea.

In the present invention, the liquid containing the catalyst is pH 7. 0 or more.

In the present invention, the starting material is characterized in that the silicon alkoxide compound.

In the present invention, the heat treatment temperature required for firing is 50 ° C to 350 ° C.

In the present invention, the thickness of the silica coating film is characterized in that 5nm to 80nm. In a liquid containing the phosphor particles, distilled water, alcohols, basic catalysts and silicon alkoxides, the content of the phosphor particles is about 0.1 wt% to about 5 w%, and the content of the distilled water is about 0.1 wt% to about 10 wt%. The content of alcohol is about 65 wt% to about 90 wt%, the content of the basic catalyst is about 0.1 wt% to about 10 wt%, and the content of the silicon alkoxide is about 0.1 wt% to about 10 wt%.

delete

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 6 to 8.

Referring to FIG. 6, a phosphor of a PDP according to an embodiment of the present invention includes a phosphor made of a phosphor and a protective film formed on the surface of each particle of the phosphor.

The top plate of the PDP includes a sustain electrode pair 69 formed on the upper substrate 61, an upper dielectric layer 66 and a protective film 67 stacked on the upper substrate 61 on which the sustain electrode pair 69 is formed. do. Each of the sustain electrode pairs 69 includes a transparent electrode such as indium tin oxide (ITO), and a metal bus electrode having a line width smaller than that of the transparent electrode and formed at one edge of the transparent electrode. One of the sustain electrode pairs 69 serves as a scan electrode for selecting a scan line by supplying a negative scan pulse in an address period for selecting a cell. In addition, the sustain electrode pair 69 is supplied with sustain pulses alternately in the sustain period to cause sustain discharge for the cells selected by the address discharge. The wall charges generated during the plasma discharge are accumulated in the upper dielectric layer 66. The passivation layer 67 is formed of a material such as MgO, thereby preventing damage to the upper dielectric layer 66 and the sustain electrode pair 69 due to sputtering generated during plasma discharge, and increasing emission efficiency of secondary electrons.

The lower plate of the PDP includes an address electrode X6 formed on the lower substrate 62, a lower dielectric layer 64 and a lower dielectric layer 64 deposited on the lower substrate 62 so as to cover the address electrode X6. And a partition wall 63 formed vertically from the lower dielectric layer 64 and the phosphor 65 formed on the surface of the partition wall 63. The address electrode X6 is orthogonal to the sustain electrode pair 69 and supplied with a positive data pulse synchronized with the scan pulse supplied to any one of the sustain electrode pair 69. The cell is selected by the address discharge occurring in the form of counter discharge between any one of the address electrode X6 and the sustain electrode pair 69. The partition 63 is formed in parallel with the address electrode X6 to prevent ultraviolet rays and visible light generated by the discharge from leaking to the adjacent discharge cells. In the phosphor, the red phosphor is (YGd) BO ₃ : Eu ³⁺ , the blue phosphor is BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , the green phosphor is Zn ₂ SiO ₄ : Mn ^2+, and a coating film is formed on the surface of the phosphor particles. The degradation of the phosphors formed and generated during discharge is reduced. Such fluorescent substance is manufactured by the process mentioned later.

7 shows a step-by-step process for producing a phosphor of the PDP according to the present invention.

Referring to Fig. 7, first, a phosphor powder is prepared. (Step S71) In the present invention, the shape of the phosphor does not have an important meaning, and powder of the phosphor used in the conventional PDP can be used as it is. At this time, it is preferable that the phosphor particles have a spherical shape, and this shape is mainly a shape that the phosphor produced by the liquid phase method has. In the embodiment of the present invention, BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , which is a blue phosphor having the most deterioration phenomenon, is used.

The phosphor powder prepared in step S71 is dispersed in a mixed solution of distilled water and alcohol. (Step S72) At this time, the phosphor particles dispersed in the mixed solution is 5wt% or less and dispersed in the solution through stirring. As a solution in which the phosphor powder is dispersed, a liquid containing at least one of distilled water and alcohol may be used. The alcohol may be an alcohol having 5 or less carbon atoms such as methyl alcohol, ethyl alcohol, n-prop alcohol, and iso-propyl alcohol. This is to prevent the hydrolysis reaction from being inhibited due to the size of the alkyl croup when using an alcohol having a larger carbon number.

The silicon alkoxide and the basic aqueous solution are added to the dispersion in which the phosphor powder is dispersed in step S72. (Step S73) As a suitable starting material of SiO ₂ , a silicon compound is suitable, of which a silicon organic compound is preferable. Here, silicon alkoxides are preferred as they produce gels at high rates and can be easily removed from SiO ₂ by evaporation or oxidation. Suitable silicon alkoxides include TEOS having an alkyl group of about 1 to 6 carbon atoms. Thereby, TEOS is used as the preferred starting material of SiO ₂ . TEOS is a starting material for forming a SiO ₂ coating film and has excellent reactivity in water or alcohol solution. The basic aqueous solution causes the pH of the dispersion mixed with TEOS to be 7 or more, and serves as a catalyst when the dispersion mixed with TEOS causes a hydrolysis / condensation reaction. Basic aqueous solutions that play this role include ammonia, sodium hydroxide, urea, and the like.

At this time, the dispersion containing the mixed materials through the step S73 includes the phosphor particles in a weight fraction of 0.1wt% to 5wt%. In addition, 0 wt% to 10 wt% of distilled water and 0 wt% to 90 wt% of alcohol are included in the weight fraction. In addition, a basic catalyst is added at a weight fraction of 0 wt% to 10 wt%, and silicon alkoxide is added at a weight fraction of 0.1 wt% to 10 wt%.

In step S73, the materials mixed in the sol-gelation reaction are completed by the hydrolysis / condensation polymerization reaction (step S74). In this reaction, the phosphor particles act as clot tuber like dust particles in the cloud, and the reaction is performed. Upon completion, a SiO ₂ gel is formed on the surface of the phosphor particles as a film.

When the film is formed on the surface of the phosphor, centrifugation is performed to separate the phosphor coated with the film. (Step S75) When the dispersion is completed and operated in a centrifuge, the coated inorganic particles and the remaining dispersion differ in specific gravity. Separated by. Here, the coated phosphor is precipitated.

After the precipitated coated phosphor is separated, the coated phosphor is heated and calcined (step S76). At this time, the heat treatment temperature is 50 ° C to 350 ° C. It removes hydroxyl groups and strongly adheres the coating film to the particle surface.

In step S76, a phosphor having a protective film is finally formed. As such, the coating film of the phosphor formed after the phosphor coated with the film is fired is formed to have a width 87 of 5 nm to 80 nm as shown in FIG. 8. Such SiO ₂ (88) has an excellent chemical stability, and has a large band gap, so that the transmittance of vacuum ultraviolet rays is high. In addition, since SiO ₂ 88 is coated on the phosphor particles 85 in a uniform and continuous thin film form, anti-sputtering or impact resistance of the phosphor is enhanced to prevent crystal destruction of the phosphor due to physical impact. Done.

As described above, the phosphor of the PDP according to the present invention forms a silica protective film on the phosphor material in a liquid state having a low viscosity. As a result, since the phosphor of the PDP according to the present invention forms a uniform coating film on the surface of the phosphor, the degradation of the phosphor can be minimized to extend the life of the PDP.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

1 is a perspective view showing a discharge cell structure of a conventional three-electrode AC surface discharge type plasma display panel.

FIG. 2 is a cross-sectional view of a portion of the plasma display panel shown in FIG. 1.

3 is a flowchart illustrating a process of manufacturing a phosphor protective film of a conventional plasma display panel.

4 is a graph showing luminance characteristics according to firing temperature and pH of a phosphor of a conventional plasma display panel.

5 is a graph showing luminance characteristics according to an addition ratio of a material forming a coating film of a phosphor of a conventional plasma display panel.

6 is a cross-sectional view partially showing a plasma display panel according to an embodiment of the present invention.

7 is a flowchart illustrating a phosphor manufacturing process of a plasma display panel according to an embodiment of the present invention.

8 is a cross-sectional view illustrating a phosphor of a plasma display panel according to an exemplary embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

1, 61: upper substrate 2, 62: lower substrate

3, 63: partition 4, 64: lower dielectric layer

5, 65, 85: phosphor 6, 66: upper dielectric layer

7, 67: protective layer 9, 69: sustain electrode pair

88: phosphor coating film X, X6: address electrode

Claims (11)

In the method for producing a silica coating film formed on the phosphor, Dispersing the phosphor powder in a liquid comprising alcohol, Adding a catalyst for inducing a sol-gelation reaction of a starting material for forming a silica coating film in a liquid in which the phosphor powder is dispersed; Injecting the sol-gelled starting material into the liquid to cause a sol-gelling reaction between the starting materials; Separating the phosphor formed on the surface of the silica coating film formed as a result of the reaction between the starting materials from the liquid, Firing the silica coating film and the phosphor. delete The method of claim 1, The phosphor powder is any one of (YGd) BO ₃ : Eu ³⁺ , Zn ₂ SiO ₄ : Mn ²⁺ , BaMgAl ₁₀ O ₁₇ : Eu ³⁺ . delete The method of claim 1, The alcohol has a chemical formula of C _n H _{2n + 1} OH and n = 5 or less. The method of claim 1, The catalyst is a phosphor manufacturing method of the plasma display panel, characterized in that any one of ammonia, sodium hydroxide, urea. The method of claim 1, The liquid containing the catalyst is a method of producing a phosphor of the plasma display panel, characterized in that the pH 7. 0 or more. The method of claim 1, The starting material is a phosphor manufacturing method of the plasma display panel, characterized in that the silicon alkoxide compound. The method of claim 1, The heat treatment temperature required for the firing is 50 ℃ to 350 ℃ characterized in that the phosphor manufacturing method of the plasma display panel. The method of claim 1, The silica coating film has a thickness of 5nm to 80nm phosphor manufacturing method of the plasma display panel. The method of claim 1, In a liquid containing the phosphor particles, distilled water, alcohols, basic catalysts and silicon alkoxides, The content of the phosphor particles is about 0.1wt% to 5w%, The content of the distilled water is about 0.1wt% to 10wt%, The content of the alcohol is about 65wt% to 90wt%, The content of the basic catalyst is about 0.1wt% to 10wt%, Content of the silicon alkoxide is about 0.1wt% to about 10wt% phosphor manufacturing method of the plasma display panel.