KR20000008995A - Surface processed fluoscent material, manufacturing method thereof, and forming method of fluoscent layer of plasma display panel using the same - Google Patents

Abstract

PURPOSE: A surface processed fluorescent material, manufacturing method thereof, and forming method of a fluorescent layer of a plasma display panel using the same are provided. CONSTITUTION: The surface processed fluorescent material comprising: fluorescent material particles(12); an inorganic particle(11) firstly coated on the surfaces of the fluorescent material particles(12), the inorganic particle(11) having SiO2 or MgO; and a heat resisting high molecular film secondly coated on the surfaces of the fluorescent material particles(12), wherein the inorganic particle(11) coated on the surfaces of the fluorescent material particles(12), the heat resisting high molecular film having a polyamide, a polyaramide, and a polyamidimide.

Description

Surface Treatment Phosphor, Manufacturing Method Thereof and Fluorescence Layer Forming Method Using the Same

The present invention relates to a surface-treated phosphor, a method of manufacturing the same, and a method of forming a fluorescent layer of a plasma display panel using the same.

BACKGROUND OF THE INVENTION A plasma display, which has recently attracted attention as a large flat panel display device, forms data electrodes 2 on a stripe on a back substrate 1 and covers a dielectric layer 3 thereon, as shown in FIG. The partition wall 4 is formed in a direction parallel to the data electrodes 2, and the phosphor 5 is coated on the upper surface of the dielectric layer 3 corresponding to the data electrodes 2 between the partition walls 4. It is. Such a plasma display is a device for displaying an image by controlling the phosphors 5 applied between the barrier ribs 4. In the case of the DC plasma display panel, the cathode and the anode are exposed to the discharge space, whereas in the case of the AC plasma display panel, each electrode is covered with a dielectric layer and an MgO layer. In either form, ultraviolet rays generated by the discharge between the electrodes excite the phosphor 5 coated on the inner surface of the discharge cell, and visible light is emitted from the phosphor by the principle of photoluminescence. In this case, the color display is performed by applying red, green, and blue phosphors to each display cell in the same manner as the CRT.

Such a plasma display device can increase the light emission time by using a memory effect, and can be easily applied to a large sized and thin flat panel display panel because high luminance is obtained regardless of the panel size. Problems in practical use are low contrast ratio, high discharge start voltage, color purity of phosphor, luminous efficiency, low luminance and lifetime. Among them, proper phosphor treatment and coating have a decisive influence on the color purity, color purity change, luminous efficiency, lifetime, luminance, and the like of the phosphor.

Since the phosphor is made of a solid powder, it is mixed with an organic material and coated by a printing method in which a paste is prepared and used. Although the photosensitive fluorescent substance paste may be used, it has not been put to practical use yet because of low exposure machine output, the absence of a large chromium mask, stability, or lack of sensitivity.

In addition, since the phosphors may have low luminous efficiency due to crystal breakdown and chemical change due to physical force received by the phosphor particles such as pressure, impact force, friction force, oxidation and impurity diffusion due to heating during display fabrication, surface treatments Phosphors should be protected against chemical changes, have high transmittance to visible light and excitation sources, and strong adhesion. Although surface treatment of the phosphor using SiO ₂ and MgO is performed to satisfy such conditions, it is not yet satisfactory.

Even if an appropriate phosphor paste is produced and printed, it is necessary to suppress the oxidation and initial luminance deterioration when firing the currently developed phosphors (especially green and blue). In particular, in the case of the blue phosphor, the color changes from blue to red due to oxidation during firing, which is a problem of color change.

The present invention has been made to improve the above problems, the surface treatment phosphor to prevent the lowering of the luminance due to the time-dependent change of green and blue phosphor, and prevent the oxidation by heat during firing of the phosphor paste, a method of manufacturing the same and a plasma using the same It is an object of the present invention to provide a method for forming a fluorescent layer of a display panel.

1 is a perspective view of an AC plasma display panel back substrate;

2 is a schematic cross-sectional view of the surface-treated phosphor particles.

<Description of the symbols for the main parts of the drawings>

1. Back substrate 2. Data electrode

3. Dielectric layer 4. Bulkhead

5. Fluorescent layer 10. Heat resistant polymer film (polyimide)

11.inorganic particles 12.phosphor

In order to achieve the above object, the surface-treated phosphor according to the present invention includes phosphor particles; Inorganic particles primarily coated on surfaces of the phosphor particles; And a heat-resistant polymer membrane coated on the surface of the phosphor particles coated with the inorganic particles secondarily.

In the present invention, the inorganic particles are SiO ₂ or MgO, the heat-resistant polymer film is preferably any one of polyimide, poly aramid and polyamideimide.

In addition, the method for producing a surface-treated phosphor according to the present invention in order to achieve the above object, the first surface treatment step of coating an inorganic material on the phosphor particles; And a second surface treatment step of coating the heat resistant polymer film on the phosphor particles coated with the inorganic particles.

In the present invention, the first surface treatment step is to coat SiO ₂ or MgO with the inorganic particles using a SiO ₂ colloidal solution or Mg (NO ₃ ) aqueous solution, the SiO ₂ colloidal solution is ethanol solvent It is prepared by using a basic chemical such as ammonium hydroxide as a catalyst and reacting potassium silicate with ethyl silicate.

In addition, in the present invention, the first surface treatment step, the sub-step of adding the SiO ₂ colloidal solution while suspending and stirring the pure phosphor; Attaching the insoluble material of the SiO ₂ colloid to the surface of the phosphor particles using an aqueous ZnSO ₄ solution; And a sub step of filtering and drying the phosphor particles having the SiO ₂ colloidal insoluble material attached to a surface thereof, wherein the primary surface treatment step includes:

A sub-step of mixing the phosphor particles by stirring in an aqueous solution of Mg (NO ₃ ); And a sub-step of drying and firing the stirred solution of the phosphor and the aqueous solution of Mg (NO ₃ ).

In the present invention, in the secondary surface treatment step, any one of polyimide, polyaramid and polyamideimide is used as the heat resistant polymer membrane,

The second surface treatment step may include a sub-step of dissolving an acid hydride (anhydride) and a diamine using N-methyl pyrrolidinone (NMP) solvent and then polycondensing at a relatively low temperature of about 10 ° C. to produce a polyamic acid; Since the polyamic acid has a viscosity of about 10,000 cps and a high viscosity to coat the phosphor particles, a step of lowering the viscosity to within 100 cps by adding an NMP solvent after polymerization; Sub-mixing the phosphor particles coated with SiO ₂ or MgO to a polyamic acid having a viscosity within 100 cps; And a sub-step of performing a spray dry while stirring the mixture at a low speed to prevent the precipitation of the phosphor; Preferably, the sub-step of performing the spray dry, the pressure of the nozzle 2 ~ 10kg The NMP solvent is completely evaporated at / cm 2, and the temperature in the spray dryer chamber is preferably about 200 ° C. for pre-curing the polyamic acid. In addition, in order to achieve the above object, a method of forming a fluorescent layer of a plasma display panel using a surface-treated phosphor according to the present invention includes: a first surface treatment step of coating an inorganic material on phosphor particles; A second surface treatment step of coating a heat resistant polymer film on the phosphor particles coated with the inorganic particles; Preparing a phosphor paste using the first and second surface treated phosphor particles using a cellulose-based polymer compound, BCA, α-Terpineol, and isoamyl acetate; And printing the phosphor paste on a rear substrate of the plasma display panel.

In the present invention, the first surface treatment step may be coated with SiO ₂ or MgO with the inorganic particles using a SiO ₂ colloidal solution or Mg (NO ₃ ) aqueous solution, and in the second surface treatment step the poly- Mid, poly aramid and polyamideimide is used, and the second surface treatment step, the acid dianhydride (anhydride) and diamines with NMP (N-methyl pyrrolidinone) solvent is dissolved, about 10 ℃ A substep of polycondensation at a relatively low temperature to produce a polyamic acid; Since the polyamic acid has a viscosity of about 10,000 cps and a high viscosity to coat the phosphor particles, a step of lowering the viscosity to within 100 cps by adding an NMP solvent after polymerization; Sub-mixing the phosphor particles coated with SiO ₂ or MgO to a polyamic acid having a viscosity within 100 cps; And a sub-step of performing a spray dry while stirring the mixed solution at a low speed to prevent precipitation of the phosphor. In the sub-step of performing the spray dry, the nozzle pressure is set to 2 to 10 kg / cm 2. The temperature in the spray dryer chamber is preferably about 200 ° C. to completely evaporate the NMP solvent and pre-cur the polyamic acid.

Hereinafter, a surface-treated phosphor, a method of manufacturing the same, and a method of forming a phosphor layer of a plasma display panel using the same will be described in detail with reference to the accompanying drawings.

In the plasma display, surface treatment is generally performed to maintain the luminescence stability through the surface protection film of the phosphor or to improve the luminescence efficiency. The surface-treated phosphor according to the present invention is deoxidation and initial stage during firing by surface treatment of the phosphor. It aims at suppressing luminance deterioration. To this end, in the present invention, after the surface treatment of SiO ₂ or MgO on the phosphor particles, the polymer film excellent in heat resistance is recoated to form a phosphor. The reason for coating the polymer film having excellent heat resistance is to eliminate the possibility of oxidizing the phosphor during firing of the phosphor.

Surface-treated phosphors according to the present invention are phosphor particles and SiO ₂ or MgO required for the primary surface treatment, polyimide for the secondary surface treatment, cellulose-based polymer compounds and high boiling point solvents, etc. It consists of.

Green phosphors that may be applied in the present invention include Zn ₂ SiO ₄ : Mn, BaAl ₁₂ O ₁₉ : Mn, BaMgAl ₁₄ O ₂₃ : Mn, SrAl ₁₂ O ₁₉ : Mn, ZnAl ₁₂ O ₁₉ : Mn, CaAl ₁₂ O ₁₉ : Mn, YBO ₃ : Tb, LuBO ₃ : Tb, GdBO ₃ : Tb, ScBO ₃ : Tb, Sr ₄ Si ₃ O ₈ C ₁₄ : Eu, etc., and red phosphors are Y ₂ O ₃ : Eu, Y ₂ SiO ₅ : Eu, Y ₃ Al ₅ O ₁₂ : Eu, Zn ₃ (PO ₄ ) ₂ : Mn, YBO ₃ : Eu, (Y, Gd) BO ₃ : Eu, GdBO ₃ : Eu, ScBO ₃ : Eu, LuBO ₃ Examples include Eu, and blue phosphors include CaWO ₄ : Pb, Y ₂ SiO ₅ : Ce, and BaMgAl ₁₄ O ₂₃ : Eu.

Since green phosphors have a radial decay time of 25 to 35ms up to 10% maximum intensity, image smearing is very slow for moving picture representation, but Zn ₂ SiO ₄ : Mn phosphors are problematic. Many improvements have been made using. As the concentration of Mn doped increases, the afterimage property decreases, but in actual panel, the concentration of Mn is about 0.8-2.6 wt% to minimize the time that the afterimage remains. In addition, phosphors such as Mg (Ga, Al) ₂ O ₄ : Mn, Y ₃ (Al, Ga) ₅ O ₁₂ : Ce using Mn, Ce, Tb, etc. as dopants have a great effect in improving the lifetime, but are not yet available. There are many things to improve. BaAl ₁₂ O ₁₉ : Mn and YBO ₃ : Tb may be used to improve color purity.

Red phosphor of the phosphor doped with Eu ₃ ⁺ Mn and YBO _3: may be the substitution has superior characteristics in this VUV region of the 147nm Eu Y with Gd optimize efficiency.

The blue phosphor is Y ₂ SiO _5: Ce The efficiency and color purity due to insufficient blue as a light emitting center and that attempts to use the new doping material, such as Ce, Ti, Eu ₂ ^+, but recently BaMgAl ₁₄ O _23: Eu is widely used and, BaMgAl ₁₀ O ₁₇ with an emission spectrum changes during use in order to improve the life of such phenomena and the color shift occurs: there is used a lot of Eu ₂ ^+.

Among these phosphors, the problems related to the improvement of lifespan in green and blue phosphors, in particular, are the biggest problem to be solved, and in order to improve the panel brightness, the state of the phosphor particles and the matching between surface treatment and coating are the most important problems. Can be.

To this end, SiO ₂ or MgO surface treatment in the present invention is carried out in the following manner.

First, the surface treatment of SiO ₂ is carried out using an alcohol such as ethanol as a solvent, a basic chemical such as ammonium hydroxide as a catalyst, and reacting potassium silicate with ethyl silicate to react SiO _2. Prepare colloidal material. This is called aging, and the SiO ₂ colloidal solution thus produced is called aging. The pure phosphor is suspended and the aging solution is added with stirring, and the SiO ₂ colloidal insoluble substance is attached to the surface of the phosphor using an aqueous solution of ZnSO ₄ . This may be filtered and dried to prepare a phosphor having SiO ₂ adhered to the surface. MgO surface treatment is carried out by stirring and mixing the phosphor in an aqueous solution of Mg (NO ₃ ), followed by dry firing.

In the present invention, the polymer compound having excellent heat resistance, such as polyimide, which is secondarily surface treated can be treated by the following method.

First, an acid anhydride and a diamine are dissolved using NMP (N-methyl pyrrolidinone) solvent, and then polycondensed at a relatively low temperature of about 10 ° C. to prepare a polyamic acid. The polyamic acid thus prepared has a viscosity of 10,000 cps and is high for coating phosphor particles, and thus, the viscosity of the polyamic acid is further reduced by adding an NMP solvent. If the temperature is slightly increased during the initial polymerization, a low viscosity polyamic acid may be produced. The viscosity of the polyamic acid for coating the phosphor particles is preferably within 100 cps.

The polyamic acid synthesized with low viscosity is mixed with phosphor particles coated with SiO ₂ or MgO. Spray-drying is performed while stirring this liquid mixture at low speed in order to prevent precipitation of fluorescent substance. When spray drying, the nozzle pressure should be 2 ~ 10kg / ㎠. When spray drying, the NMP is completely evaporated and the temperature in the spray dryer chamber should be about 200 ° C. for pre-curing the polyamic acid. Even if spray-drying is performed, SiO ₂ and MgO surface-treated on the phosphor particles are strongly attached, so that there is no separation from the phosphor. As shown in FIG. 2, the phosphor particles thus prepared are first surface-treated with inorganic particles 11 of SiO ₂ or MgO on the surface of the phosphor 12 and secondly pre-cured. It is a step that is coated with the polyamic acid (10).

The surface treated phosphor particles are made of a phosphor paste for printing. The phosphor paste uses an organic vehicle (vehicle) in order to improve the printability, the composition of the organic vehicle (vehicle) used in the ethyl cellulose or nitrocellulose-based polymer compound and BCA (Butyl Carbitol Acetate), α- It is a mixture of high boiling point solvent mixtures such as Terpineol and Isoamylacetate.

When surface-treating SiO ₂ or MgO, the ratio of the phosphor is less than 1%, and 0.1-0.5% is the best. When preparing a solution for spray drying, the ratio of the phosphor particles to the polyamic acid solution should be such that the higher the viscosity of the polyamic acid, the smaller the content of the phosphor particles should be. Mix about 10g. The ratio of the high boiling point solvent and the cellulose in the organic medium is preferably about 10: 1, and as shown in FIG. 2, the amount of the organic medium used to make the phosphor paste is greater than that of the surface-treated phosphor particles. 50 to 90% of the total composition of the phosphor is good.

The phosphor paste thus prepared is printed between the partition walls through printing. The printed phosphor layer is fired at about 450 ° C. for the deorganized vehicle. At this time, the high boiling point solvent is burned out at a temperature of about 200 ° C., and the high boiling point solvent of the cellulose system is burned out over a wide range of about 300 to 400 ° C. On the other hand, the polyamic acid that has been pre-cured primarily becomes post-curing at a temperature of about 300 ° C. to become polyimide, but is burned out at 400 ° C. Therefore, in the absence of a surface coating such as polyimide, heat at high temperatures near 400 ° C. is directly applied to the phosphor particles to promote phosphor oxidation, whereas in the presence of a surface protective layer such as polyimide, heat is used to pyrolyze the polyimide. This reduces the possibility of phosphor oxidation.

Basically, the polyimide surrounding the phosphor may be thermally decomposed when the paste is fired, but even if some polyimide remains, it functions to prevent phosphor oxidation by heat during sealing of the upper and lower plates. At this time, all the polyimide is thermally decomposed. When surface-coating phosphors with a resin having low heat resistance, there is no effect of preventing phosphor oxidation because it is pyrolyzed before cellulose polymer during paste firing. Therefore, the surface coating polymer used in the present invention may be a heat-resistant polymer film such as polyimide, polyaramid, polyamideimide, etc. having excellent heat resistance, but considering the ease of coating, it can be said that polyimide is best used. .

As described above, the surface-treated phosphor according to the present invention, a manufacturing method thereof, and a phosphor layer forming method of the PDP using the same include SiO ₂ , MgO, and the like for preventing the luminance deterioration due to the aging change of the phosphor, especially green and blue phosphors. Primary surface treatment with an inorganic material, and consists of a secondary surface coating for the prevention of oxidation by heat during firing of the phosphor paste.

The reason for the first surface treatment is not yet known, but it is possible to maintain the emission stability, improve the emission efficiency, and to print at a high print density when printing the phosphor by mitigating ion bombardment in the panel. The reason for the secondary surface coating is to prevent phosphor oxidation by using the heat applied to the phosphor during pyrolysis of the phosphor paste and the sealing of the upper and lower plates to prevent thermal decomposition of the coating having excellent heat resistance. This is because the phenomenon in which the luminance is lowered can be prevented.

Claims (16)

Phosphor particles; Inorganic particles primarily coated on surfaces of the phosphor particles; And And a heat-resistant polymer film secondary coated on the surfaces of the phosphor particles coated with the inorganic particles. The method of claim 1, The inorganic particles are surface treated phosphor, characterized in that SiO ₂ or MgO. The method according to claim 1 or 2, The heat resistant polymer film is any one of polyimide, polyaramid and polyamideimide. A primary surface treatment step of coating an inorganic substance on the phosphor particles; And A second surface treatment step of coating a heat resistant polymer film on the phosphor particles coated with the inorganic particles; The manufacturing method of the surface-treated fluorescent substance characterized by including. The method of claim 4, wherein The first surface treatment step is a method for producing a surface-treated phosphor, characterized in that the coating of SiO ₂ or MgO with the inorganic particles using a SiO ₂ colloidal solution or Mg (NO ₃ ) aqueous solution. The method of claim 5, The SiO ₂ colloidal solution is prepared by reacting potassium silicate with ethyl silicate using ethanol as a solvent and a basic chemical such as ammonium hydroxide as a catalyst. Method for producing treated phosphor. The method of claim 6, The first surface treatment step, A sub-step of suspending pure phosphor and adding the SiO ₂ colloidal solution while stirring; Attaching the insoluble material of the SiO ₂ colloid to the surface of the phosphor particles using an aqueous ZnSO ₄ solution; And A sub-step of filtering and drying the phosphor particles having the SiO ₂ colloidal insoluble material attached to the surface; The manufacturing method of the surface-treated fluorescent substance characterized by including. The method of claim 5, The first surface treatment step, A sub-step of mixing the phosphor particles by stirring in an aqueous solution of Mg (NO ₃ ); And Sub step of drying and firing the stirred solution of the phosphor and Mg (NO ₃ ) aqueous solution; The manufacturing method of the surface-treated fluorescent substance characterized by including. The method according to claim 4 or 5, Method of producing a surface-treated phosphor, characterized in that any one of polyimide, polyaramid and polyamideimide is used as the heat resistant polymer film in the secondary surface treatment step. The method of claim 9, The second surface treatment step, A sub-step of dissolving an acid anhydride and a diamine using N-methyl pyrrolidinone (NMP) solvent and then polycondensing at a relatively low temperature of about 10 ° C. to produce a polyamic acid; Since the polyamic acid has a viscosity of about 10,000 cps and a high viscosity to coat the phosphor particles, a step of lowering the viscosity to within 100 cps by adding an NMP solvent after polymerization; Sub-mixing the phosphor particles coated with SiO ₂ or MgO to a polyamic acid having a viscosity within 100 cps; And A sub-step of performing a spray dry while stirring the mixture at a low speed to prevent the precipitation of the phosphor; The manufacturing method of the surface-treated fluorescent substance characterized by including. The method of claim 10, In the sub-drying step, the pressure of the nozzle is 2 to 10 kg / cm 2 to completely evaporate the NMP solvent, and the temperature in the spray dryer chamber is about 200 ° C. for pre-curing the polyamic acid. The manufacturing method of the surface-treated fluorescent substance characterized by the above-mentioned. A primary surface treatment step of coating an inorganic substance on the phosphor particles; A second surface treatment step of coating a heat resistant polymer film on the phosphor particles coated with the inorganic particles; Preparing a phosphor paste using the first and second surface treated phosphor particles using a cellulose-based polymer compound, BCA, α-Terpineol, and isoamyl acetate; And Printing the phosphor paste on a rear substrate of a plasma display panel; And a fluorescent layer forming method of the plasma display panel. The method of claim 12, The first surface treatment step is a method of forming a fluorescent layer of a plasma display panel, characterized in that the coating of SiO ₂ or MgO with the inorganic particles using a SiO ₂ colloidal solution or Mg (NO ₃ ) aqueous solution. The method according to claim 12 or 13, And using one of polyimide, polyaramid and polyamideimide as the heat resistant polymer film in the second surface treatment step. The method of claim 14, The second surface treatment step, A sub-step of dissolving an acid anhydride and a diamine using N-methyl pyrrolidinone (NMP) solvent and then polycondensing at a relatively low temperature of about 10 ° C. to produce a polyamic acid; Since the polyamic acid has a viscosity of about 10,000 cps and a high viscosity to coat the phosphor particles, a step of lowering the viscosity to within 100 cps by adding an NMP solvent after polymerization; Sub-mixing the phosphor particles coated with SiO ₂ or MgO to a polyamic acid having a viscosity within 100 cps; And A sub-step of performing a spray dry while stirring the mixture at a low speed to prevent the precipitation of the phosphor; And a fluorescent layer forming method of the plasma display panel. The method of claim 15, In the sub-drying step, the pressure of the nozzle is 2 to 10 kg / cm 2 to completely evaporate the NMP solvent, and the temperature in the spray dryer chamber is about 200 ° C. for pre-curing the polyamic acid. A method of forming a fluorescent layer of a plasma display panel.