KR20020066554A - Process for preparing zinc orthosilicate green phosphor - Google Patents

Abstract

PURPOSE: Provided is a method for producing a green phosphor based on zinc silicate, which has simplified manufacturing process and improved yield, and which can provide high brightness screen. CONSTITUTION: The method comprises the steps of (a) homogeneously mixing a fluorescent material comprising (i) ZnO or (CH3CO2)2Zn, (ii) noncrystalline colloidal silica(SiO2) or tetraethyl orthosilicate(TEOS) having particle size of 20 mm, and (iii) MnCO3 or (CH3CO2)2Mn4H2O to form zinc silicate glycolate under glycol; (b) heat treating the zinc silicate glycolate to 600-1000 deg.C in air to form a mixed material powder; (c) heat treating the powder in sealed reactor under nitrogen atmosphere. The glycol used in the step(a) is selected from ethylene glycol and 1,4-butanediol.

Description

Production method of zinc silicate-based green phosphors {PROCESS FOR PREPARING ZINC ORTHOSILICATE GREEN PHOSPHOR}

[TECHNICAL FIELD OF THE INVENTION]

The present invention relates to a new method for producing a zinc silicate-based green phosphor, and more particularly, to a method for producing Zn ₂ SiO ₄ : Mn ²⁺ used as a green phosphor of a plasma display panel (PDP) or a lamp.

[Private Technology]

Phosphors are widely used in the display field using visible light as a substance that emits light when external energy such as radiation, electron beam, ultraviolet ray, electric field, heat, and chemical reaction is applied. In general, desirable characteristics of color display phosphors should have high luminous efficiency and good color purity of red, green, blue, and three primary colors, and the change of optical characteristics is small due to the thermal and chemical treatment applied to the display parts. Therefore, it should be possible to realize high brightness screen with good applicability.

Application of the phosphor particles to the plasma display panel is generally commercially used a method of laminating the phosphor particles in a plurality of layers using a screen printing method of the paste prepared of the phosphor. At this time, the case where the compactness of the laminated phosphor particles is high is preferable to implement a high luminance screen, and the influence of the phosphor particles is greatly affected by the shape of the phosphor particles to be used by excluding the influence factors caused by the paste preparation and the coating process. In general, it is well known that the filling of phosphor particles having a spherical shape is higher than that of non-spherical phosphor particles, and therefore, it is a common desire of phosphor suppliers to shape phosphor particles.

In general, the phosphor is fired at a temperature of 600 to 1500 ° C. in which a solid chemical reaction can be performed in a batch or continuous electric furnace controlled by mixing a high-purity raw material and a crystal growth controlling flux. The size and shape of the phosphors produced are dependent on the firing time and temperature and the type and amount of the melt.

Conventionally, zinc silicate green phosphors have been manufactured by mechanically mixing fluorescent raw materials with the manufacturing method of zinc silicate green phosphors, but the manufacturing process is complicated and it is difficult to control the size and shape of particles by mixing heterogeneity and quality control Difficult, there was a disadvantage that the yield is lowered.

Accordingly, an object of the present invention is to provide a method for producing a zinc silicate-based green phosphor, which simplifies the manufacturing process of the phosphor, improves the yield, and is suitable for realizing a high brightness screen, in order to solve the problems in the prior art as described above. .

Another object of the present invention is to provide a zinc silicate green phosphor having a uniform particle distribution prepared by the above method.

1 is an SEM photograph (× 10000) of a phosphor prepared in Example 1,

2 is an SEM photograph (× 4000) of the phosphor prepared in Example 2,

3 is an SEM photograph (× 4000) of the phosphor prepared in Example 3. FIG.

The present invention to achieve the above object,

(a) under glycol

Iii) ZnO or (CH ₃ CO ₂ ) ₂ Zn,

Ii) amorphous colloidal silica (SiO ₂ ) or tetraethylolsosilicate (TEOS) with a particle size of 20 nm, and

Iii) MnCO ₃ or (CH ₃ CO ₂ ) ₂ Mn ₄ H ₂ O

Preparing a zinc silicate glycolate by homogeneously mixing the fluorescent raw material and the melting agent at a molecular level;

(b) heat-treating the zinc silicate glycolate at a temperature of 600 to 1000 ° C. to prepare a mixed raw material powder; And

(c) heat-treating the mixed raw material powder under a nitrogen atmosphere in a closed reactor

It provides a method for producing a zinc silicate-based green phosphor comprising a.

The present invention also provides a zinc silicate green phosphor prepared by the method described above.

Hereinafter, the present invention will be described in detail.

The inventors of the present invention uniformly mix the fluorescent raw material using glycol to prepare zinc silicate glycolate, and heat-treat it at 1000 ° C. or lower to prepare a mixed raw material powder, and then put it in a sealed reactor to heat-treat it under nitrogen atmosphere to improve the yield. The present invention was completed by discovering the formation of a green phosphor capable of realizing a high brightness screen.

The present invention comprises the steps of preparing a zinc silicate glycolate by mixing the fluorescent raw material and the melter in a uniform mixing method using glycol.

Fluorescent raw materials used in the present invention are ZnO or (CH ₃ CO ₂ ) ₂ Zn, amorphous colloidal silica (SiO ₂ ) or tetraethylolsosilicate (Si (OC ₂ H ₅ ) ₄ , having a particle size of 20 nm, below Called 'TEOS'), MnCO ₃ or (CH ₃ CO ₂ ) ₂ Mn ₄ H ₂ O. Preferably, the mixing ratio of the raw materials is ZnO or (CH ₃ CO ₂ ) ₂ Zn: SiO ₂ or TEOS: MnCO ₃ or (CH ₃ CO ₂ ) ₂ Mn ₄ H ₂ O The molar ratio of Mn ₄ H ₂ O is 1.92: 1. It is preferable that it is 0.08.

In the homogeneous mixing method using glycol, ZnO or (CH ₃ CO ₂ ) ₂ Zn, MnCO ₃ or (CH ₃ CO ₂ ) ₂ Mn ₄ H ₂ O is completely dissolved in HNO ₃ and then colloidal silica or TEOS in the glycol solution. By mixing together and reacting at 200 ° C. or less, zinc (Zn), silicon (Si), and manganese (Mn) react with glycol to prepare zinc silicate glycolate, which is well mixed at the molecular level. At this time, nitric acid (HNO ₃ ), water, and substances generated during the reaction can be easily removed by the difference between the break point with the glycol. The glycol is preferably selected from ethylene glycol (C ₂ H ₆ O ₂ ) or 1,4-butanediol (C ₄ H ₁₀ O ₂ ), but the glycol used in the present invention is not limited thereto.

In the present invention, the melter may be used either in the homogeneous mixing with the raw material when preparing the zinc silicate glycolate or after mixing the zinc silicate glycolate. The present invention includes both the method of mixing by performing the ball milling (ball milling) in the method of mixing the fluorescent raw material and the melting agent or in the preparation of zinc silicate glycolate.

The shape controlling flux used in the present invention is preferably a compound containing fluorine or chlorine. Compounds containing the above-mentioned fluorine more preferably is ZnF _2, MnF _2, BaF ₂ and is selected from the group consisting of a mixture thereof, the compound containing the chlorine is as ZnCl _2, BaCl _2, MnCl _2, and mixtures thereof It is good to select from the group which consists of. The amount of the melting agent is preferably adjusted to have an appropriate size depending on the display in which the phosphor is used. That is, since the size of the phosphor required for the PDP requires a phosphor having a size of 2 to 4 μm, it is preferable to use 0.1 to 10.0% by weight.

In addition, the present invention includes the step of preparing a raw material mixed powder well mixed at the molecular level by heat-treating zinc silicate glycolate prepared by the above process in air at a temperature of 600 to 1000 ℃ or less.

According to the present invention, it is possible to omit various processes of raw material mixing as compared to the conventional process, and to obtain a phosphor having a pure crystal phase after firing by homogeneous mixing and a uniform particle distribution as compared with the conventional process.

In addition, the present invention includes the step of heat-treating under a nitrogen atmosphere by placing the mixed raw material powder prepared in the above process in a closed reactor.

The closed reactor is preferably a cotton processed alumina crucible. When the reactor is open during heat treatment, it is preferable that the reactor is closed because a problem in that the shape of the phosphor particles produced is not uniform is generated.

The heat treatment process of the present invention is carried out under a nitrogen atmosphere, and the nitrogen atmosphere is for reducing Mn present in trivalent to divalent Mn.

The heat treatment temperature in the heat treatment step of the present invention is preferably 1,100 to 1,500 ℃, more preferably 1,100 to 1,300 ℃. In this case, when the heat treatment temperature is less than 1,100 ℃, the formation of the zinc silicate phosphor is not well made, or the size of the formed particles is too small, if the heat treatment temperature exceeds 1,500 zinc silicate phosphor is well formed but the Not good because it gets too big.

In addition, the present invention provides a green phosphor produced by the method for producing the green phosphor, the phosphor is characterized in that the green phosphor having an average particle diameter of less than 10 ㎛. The green phosphor manufactured according to the present invention is particularly preferably used for plasma display panels requiring high brightness screens.

As described above, since the present invention manufactures the zinc silicate green phosphor by the homogeneous mixing method using glycol, it is possible to simplify the manufacturing process and increase the yield, and to obtain a green phosphor having a pure crystal phase and uniform particle distribution, as compared with the related art. .

Hereinafter, examples of the present invention will be described. The following examples are provided to illustrate the present invention, but the present invention is not limited to the following examples.

Example 1

1.92 mol of ZnO and 0.08 mol of (CH ₃ CO ₂ ) ₂ Mn ₄ H ₂ O are completely dissolved in 300 ml of 63% HNO ₃ , followed by 1 mol of colloidal silica (SiO ₂ ) using 1 liter of ethylene glycol solution as a solvent. The zinc silicate glycolate was prepared by the reaction at 200 ° C. or below. Then, heat treatment in air at a temperature of 600 ℃ to prepare a zinc silicate mixed raw material. The mixture was enclosed in a 300 cc faced crucible, sealed and heat-treated at 1,200 ° C. for 3 hours under a nitrogen atmosphere to prepare a phosphor. The shape of the prepared phosphor is shown in Figure 1 by SEM (Scanning Electron Microscope). In FIG. 1, it was confirmed that the shape of the phosphor particles was 1 μm or less and the particles were formed evenly.

Example 2

1.92 mol of ZnO and 0.08 mol of (CH ₃ CO ₂ ) ₂ Mn ₄ H ₂ O are completely dissolved in 300 ml of 63% HNO ₃ , followed by 1 mol of colloidal silica (SiO ₂ ) using 1 liter of ethylene glycol solution as a solvent. The zinc silicate glycolate was prepared by the reaction at 200 ° C. or below. Then, heat treatment in air at a temperature of 600 ℃ to prepare a zinc silicate mixed raw material. 99.6% by weight of the zinc silicate mixed raw material and 0.4% by weight of the melting agent BaCl ₂ were ball milled at 250 rpm for 20 hours using ethanol as a solvent to prepare a mixture. The mixture was enclosed in a 300 cc faced crucible and sealed and heat-treated at 1,100 ° C. for 3 hours under a nitrogen atmosphere to prepare a phosphor. The shape of the prepared phosphor was shown in Figure 2 by scanning electron microscope (SEM). In FIG. 1, it was confirmed that the shape of the phosphor particles was 1 to 2 μm and the particles were formed evenly.

Example 3

1.92 mol of ZnO and 0.08 mol of (CH ₃ CO ₂ ) ₂ Mn ₄ H ₂ O are completely dissolved in 300 ml of 63% HNO ₃ , followed by 1 mol of colloidal silica (SiO ₂ ) using 1 liter of ethylene glycol solution as a solvent. The zinc silicate glycolate was prepared by the reaction at 200 ° C. or below. Then, heat treatment in air at a temperature of 600 ℃ to prepare a zinc silicate mixed raw material. 99.2% by weight of the zinc silicate mixed raw material and 0.8% by weight of the melting agent BaCl ₂ were ball milled at 250 rpm for 20 hours using ethanol as a solvent to prepare a mixture. The mixture was enclosed in a 300 cc faced crucible and sealed and heat-treated at 1,100 ° C. for 3 hours under a nitrogen atmosphere to prepare a phosphor. Figure 3 shows the shape of the prepared phosphor by scanning electron microscope (SEM). In FIG. 1, it was confirmed that the shape of the phosphor particles was 2-3 μm and the particles were formed evenly.

As described above, in the present invention, the fluorescent raw material may be uniformly mixed at the molecular level in the glycol solution to simplify the process and improve the yield, and to obtain a green phosphor having a uniform particle distribution of less than 10 μm of pure crystal phase. High brightness screen can be realized.

Claims (11)

(a) under glycol Iii) ZnO or (CH ₃ CO ₂ ) ₂ Zn, Ii) amorphous colloidal silica (SiO ₂ ) or tetraethylolsosilicate (TEOS) with a particle size of 20 nm, and Iii) MnCO ₃ or (CH ₃ CO ₂ ) ₂ Mn ₄ H ₂ O Preparing a zinc silicate glycolate by homogeneously mixing the fluorescent raw material and the melting agent at a molecular level; (b) heat-treating the zinc silicate glycolate at a temperature of 600 to 1000 ° C. to prepare a mixed raw material powder; And (c) heat-treating the mixed raw material powder under a nitrogen atmosphere in a closed reactor Method for producing a zinc silicate-based green phosphor comprising a. The method for producing a zinc silicate-based green phosphor according to claim 1, wherein the glycol of (a) is ethylene glycol or 1,4-butanediol. The method of claim 1, wherein the homogeneous mixing of the fluorescent raw material and the melting agent of (a) is homogeneous after mixing with the raw material when preparing the zinc silicate glycolate, or mixing after preparing the zinc silicate glycolate. Method for producing phosphorus zinc silicate green phosphor. The method for producing a zinc silicate-based green phosphor according to claim 1, wherein the melter of (a) is a compound containing fluorine or chlorine. The zinc silicate according to claim 4, wherein the melter is selected from the group consisting of AlF ₃ , MgF ₂ , BaF ₂ and mixtures thereof or is selected from the group consisting of ZnCl ₂ , BaCl ₂ , MnCl ₂ and mixtures thereof. Method for producing a green phosphor. The method of manufacturing a zinc silicate-based green phosphor according to claim 1, wherein the amount of the melting agent of (a) is 0.1 to 10.0 wt%. The method of manufacturing a zinc silicate-based green phosphor according to claim 1, wherein the heat treatment temperature of (c) is 1,100 to 1,300 ° C. The method for producing a zinc silicate-based green phosphor according to claim 1, wherein the green phosphor is for a plasma display panel. Zinc silicate-based green phosphor prepared by the method of claim 1. The zinc silicate-based green phosphor according to claim 9, wherein the green phosphor is for a plasma display panel. The zinc silicate-based green phosphor of claim 9, wherein the green phosphor has a particle size of less than 10 μm.