KR20100083325A - Fluorescent paste - Google Patents

Abstract

PURPOSE: A fluorescent paste is provided to secure the oppose discharge voltage margin by containing magnesium oxide powder coated with fluorine for reducing the breakdown voltage. CONSTITUTION: A fluorescent paste contains phosphor powder, and magnesium oxide powder coated with fluorine. The particle of the magnesium oxide powder is a cubic form. 100~10,000ppm of fluorine is contained in the magnesium oxide powder. The fluorescent paste additionally contains a binder and a solvent. The binder is a cellulose resin. The fluorescent paste contains 30~50wt% of phosphor powder, 1~10wt% of magnesium oxide powder, 5~10wt% of binder, and 30~60wt% of solvent.

Description

Phosphor Paste

The present invention relates to a phosphor paste, and more particularly, to a phosphor paste comprising a magnesium oxide (MgO) powder coated with fluorine (Fluorine).

In general, a plasma display panel (PDP) injects a discharge gas into a discharge cell separated by a partition wall, and is caused by an energy difference when ultraviolet rays generated during plasma emission excite phosphors and return to a ground state. A display device using a light emission phenomenon of visible light. Since the phosphor is made of a solid powder, it is mixed with an organic material and coated by a printing method used to prepare a paste.

The phosphor for the plasma display panel should have excellent discharge characteristics, luminescence brightness and color coordinates, have a short afterglow time, and should not cause phosphor deterioration by heat or ultraviolet rays. However, as the plasma display device becomes more detailed, the discharge voltage may increase and efficiency and luminance may decrease due to the structure and characteristics of the discharge gas.

In addition, the phosphors of the plasma display panel have different characteristics from each other and different surface charge potentials, resulting in a lower discharge characteristic, a small amount of secondary electron emission, and an erroneous discharge at high temperature, thereby degrading display quality.

An object of the present invention is to provide a phosphor paste which is excellent in secondary electron emission characteristics and can lower a discharge start voltage.

The phosphor paste according to the present invention for achieving the above object includes a magnesium oxide (MgO) powder coated with a phosphor powder and fluorine (Fluorine), the magnesium oxide (MgO) powder particles are in Cubic form.

In addition, the phosphor paste according to the present invention for achieving the above object, 100 to 10000ppm of fluorine (Fluorine) compared to magnesium oxide (MgO) powder.

According to the present invention, since the phosphor paste includes magnesium oxide (MgO) powder coated with fluorine, the discharge start voltage can be lowered to secure a counter discharge voltage margin.

Hereinafter, with reference to the drawings will be described the present invention in more detail.

The phosphor paste according to an embodiment of the present invention may include a phosphor powder, a binder, a fluorine-coated magnesium oxide (MgO) powder, and a solvent.

The phosphor powder may be any one of red, green and blue phosphor powders, and in red, Y ₂ O ₃ : Eu, YVO ₄ : Eu, (Y, Gd) BO ₃ : Eu, Y ₂ O ₃ S: Eu and γ-Zn ₃ (PO ₄ ) ₂ : Mn, (Zn, Cd) S: Ag + In ₂ O ₃ , Y (P, V) O ₄ : Eu and the like.

In addition, in green, Zn ₂ GeO ₂ : Mn, BaAl ₁₂ O ₁₉ : Mn, Zn ₂ SiO ₄ : Mn, LaPO ₄ : Tb, ZnS: Cu, Al, ZnS: Au, Cu, Al, (Zn, Cd) S: Cu, Al, Zn ₂ SiO ₄ : Mn, As, Y ₃ Al ₅ O ₁₂ : Ce, CeMgAl ₁₁ O ₁₉ : Tb, Gd ₂ O ₂ S: Tb, Y ₃ Al ₅ O ₁₂ : Tb, ZnO: Zn, (Y, Gd) BO ₃ : Tb, (Ba, Sr, Mg) O.aAl ₂ O ₃ Mn, and the like, and Sr ₅ (PO ₄ ) ₃ Cl: Eu, BaMgAl ₁₄ O _{23 as} blue. : Eu, BaMgAl ₁₆ O ₂₇ : Eu, BaMg ₂ Al ₁₄ O ₂₄ : Eu, CaMgSi ₂ O ₆ : Eu, Y ₂ SiO ₃ : Ce, BaMgAl ₁₀ O ₁₇ : Eu, and the like.

It is preferable that the particle diameter of such fluorescent substance powder is 0.2-5 micrometers. When the particle size of the phosphor powder is smaller than 0.2 µm, the aggregation of the phosphor powder is likely to occur, and the surface is activated, and thus, chemical reaction with other components such as a binder can be caused. On the other hand, when the particle diameter is larger than 5 μm, the fluorescent film may become nonuniform or, accordingly, the luminance may be nonuniform, which is not preferable.

On the other hand, if the content of the phosphor powder is less than 30wt%, the coating thickness of the paste required to obtain the desired film thickness becomes thick, so that color mixing may occur between adjacent discharge cells, whereas the content of the phosphor powder exceeds 50wt%. The viscosity of the phosphor paste may increase, which may reduce dispensing coating uniformity. Therefore, the phosphor powder is preferably contained in 30 to 50wt%.

The binder functions as a binder of each component before firing and is a cellulose type such as ethyl cellulose, methyl cellulose, nitrocellulose, cellulose acetate, cellulose propionate, cellulose butyrate, hydroxy cellulose, and methyl hydroxy cellulose. Resins and the like can be used.

In addition, the content of the binder is preferably 5 to 10wt%. If the content of the binder is less than 5wt%, the bonding strength of the fluorescent film may be lowered. If the amount of the binder is greater than 10wt%, the phosphor content in the fluorescent film may be relatively reduced, resulting in deterioration of characteristics such as color purity.

Magnesium oxide (MgO) powder is added to increase the secondary electron emission coefficient to reduce discharge voltage and prevent hot discharge. This is due to the electrical properties of the oxide material, before the discharge occurs in the portion where the phosphor powder is disposed, the discharge occurs first in the portion where the magnesium oxide powder is disposed at a relatively low voltage, and the discharge is spread to the portion where the phosphor powder is placed. Because it becomes.

The magnesium oxide powder is preferably added at 1 to 10wt%. When the amount of magnesium oxide powder added is less than 1wt%, the effect of adding magnesium oxide is insignificant, and when it is added in excess of 10wt%, the ratio of the supplementary magnesium oxide of the phosphor increases, so that the overall brightness may be reduced.

In addition, the magnesium oxide powder particles may be spherical or cubic (Cubic) shape, the size of the magnesium oxide powder particles may be 2nm to 100nm. The size of the size of the magnesium oxide powder particles means the diameter if the shape of the sphere, the length of one side if the shape of the cube.

On the other hand, magnesium oxide is highly hygroscopic, and may deteriorate by reaction with moisture. In order to prevent this, the phosphor paste according to the present invention coats fluorine on the surface of the magnesium oxide powder.

As a method of coating fluorine on the surface of magnesium oxide powder, any conventional method may be used.

The amount of fluorine coated on the surface of the magnesium oxide powder particles depends on the shape of the magnesium oxide powder particles as shown in Table 1 below, but as the amount of fluorine coated increases, the discharge start voltage is lowered.

Table 1 below shows the amount of fluorine coated according to the shape of the magnesium oxide powder particles and the discharge start voltage accordingly. The amount of fluorine is based on magnesium oxide (MgO) powder.

No. Shape of MgO Amount of fluorine (ppm) E.I. Discharge start voltage (V) One phrase 0 - 180 2 phrase 100 5.8 179.6 3 phrase 200 12 177 4 phrase 400 15 175 5 hexahedron 100 6 178 6 hexahedron 2000 28 170 7 hexahedron 10000 50 165

In the case of No. 1 in Table 1, when fluorine is not coated on the spherical magnesium oxide surface, the discharge start voltage is 180V. Nos. 2 to 4 are for fluorine coating on the surface of spherical magnesium oxide, and Nos. 5 to 7 are for fluorine coating on the surface of magnesium oxide of hexahedron. This lowered result can be seen. This is because fluorine is coated on the surface of magnesium oxide, thereby preventing magnesium oxide from reacting with water to deteriorate.

In addition, referring to Table 1, it can be seen that the amount of fluoroine to be coated is greater in the case where the shape of MgO is hexahedron than in the case of sphere. In addition, as the amount of fluorine is coated, the discharge start voltage is lowered, and the shape of the magnesium oxide powder is preferably hexahedral.

FIG. 1 is a photograph taken with a scanning electron microscope of the microstructure of a fluoroine-coated specimen in a magnesium oxide powder of such a cube. In FIG. 1, the hexahedral magnesium oxide powder 10 and the fluoroine 20 attached to the surface thereof can be confirmed.

On the other hand, if the shape of the magnesium oxide hexahedron, fluorine may be included up to 10000ppm compared with magnesium oxide. When the amount of fluorine coated is more than 10000 ppm relative to magnesium oxide, the emission characteristics of the secondary electrons may be lowered. On the other hand, if the amount of fluorine coated is less than 100ppm, the effect of lowering the discharge start voltage does not appear.

Therefore, the amount of fluorine to be coated is preferably 100 to 10000ppm relative to magnesium oxide.

The solvent may use BCA (Butyl carbitol) or terpineol (Terpineol), and may be included in the phosphor paste at 30 to 60wt%.

If the solvent content is less than 30wt%, the phosphor may not be dispersed properly, or the viscosity of the phosphor paste may be too high, resulting in uneven phosphor coating thickness. On the other hand, when the content of the solvent is greater than 60wt%, the content of the phosphor per unit volume is too low, which is not preferable because the luminance is lowered.

On the other hand, the phosphor paste of this invention can add photosensitive components, such as a photosensitive monomer, a photosensitive oligomer, and a photosensitive polymer, and additive components, such as a photoinitiator, a sensitizer, antioxidant, a ultraviolet absorber, and a polymerization inhibitor.

2 is a diagram illustrating a structure of a PDP including a black matrix formed of a black paste according to the present invention.

Referring to the drawings, the plasma display panel 200 includes a scan electrode 211, a sustain electrode 212 and a sustain electrode 212, which are formed on the upper substrate 210, and an address electrode 222 formed on the lower substrate 220. It includes.

The sustain electrode pairs 211 and 212 generally include transparent electrodes 211a and 212a and bus electrodes 211b and 212b formed of indium tin oxide (ITO), and the bus electrodes 211b, 212b) may be formed of a metal such as silver (Ag) or chromium (Cr) or a stack of chromium / copper / chromium (Cr / Cu / Cr) or a stack of chromium / aluminum / chromium (Cr / Al / Cr). .

The bus electrodes 211b and 212b are formed on the transparent electrodes 211a and 212a to reduce the voltage drop caused by the high resistance transparent electrodes 211a and 212a.

Meanwhile, between the transparent electrodes 211a and 212a of the scan electrode 211 and the sustain electrode 212 and the bus electrodes 211b and 211c, external light generated from the outside of the upper substrate 210 is absorbed to reduce reflection. The main is arranged a black matrix (BM) that functions to block light and to improve the purity and contrast of the upper substrate 210.

The black matrix is formed on the upper substrate 210, and is formed between the first black matrix 215 formed at a position overlapping the partition wall 221, between the transparent electrodes 211a and 212a and the bus electrodes 211b and 212b. The second black matrices 211c and 212c may be formed.

Meanwhile, the first black matrix 215 and the second black matrices 211c and 212c, which are also called black layers or black electrode layers, may be simultaneously formed and physically connected in the formation process, or may not be simultaneously formed and thus not physically connected. .

In addition, when physically connected and formed, the first black matrix 215 and the second black matrix 211c and 212c may be formed of the same material, but may be formed of different materials when they are formed separately.

The passivation layer 214 protects the upper dielectric layer 213 from sputtering of charged particles generated during gas discharge, and increases emission efficiency of secondary electrons.

The address electrode 222 is formed in a direction crossing the scan electrode 211 and the sustain electrode 212. The lower dielectric layer 224 and the partition wall 221 are formed on the lower substrate 220 on which the address electrode 222 is formed.

The lower dielectric layer 224 is electrically condensed to protect the address electrode 222 and is formed in white to prevent the discharge light from being transmitted to the rear substrate.

The method of forming the lower dielectric layer 224 is mainly used for screen printing, but may be formed by various coaters such as a green sheet laminate method, a slot coater method, and a roll coater method. In addition, the phosphor layer 223 is formed on the surfaces of the lower dielectric layer 224 and the partition wall 221.

The phosphor layer 223 may be formed of a phosphor paste according to the present invention. The phosphor paste according to the present invention includes a magnesium oxide (MgO) powder coated with a phosphor powder and fluorine (Fluorine), and the magnesium oxide (MgO) powder particles are in Cubic form. In addition, the amount of fluorine to be coated is preferably 100 to 10000ppm relative to magnesium oxide.

By coating fluorine on magnesium oxide in this manner, magnesium oxide is prevented from being deteriorated by a reaction with water, thereby lowering the discharge start voltage and securing a counter discharge voltage margin.

The partition wall 221 has a vertical partition wall 221a and a horizontal partition wall 221b formed in a closed shape, and physically distinguishes the discharge cells, and prevents ultraviolet rays and visible light generated by the discharge from leaking to the adjacent discharge cells.

While the preferred embodiments of the present invention have been shown and described, the present invention is not limited to the specific embodiments described above, and the present invention is not limited to the specific embodiments of the present invention, without departing from the spirit of the invention as claimed in the claims. Various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

FIG. 1 is a photograph taken with a scanning electron microscope of the microstructure of a fluoroine-coated specimen in a magnesium oxide powder of a cube.

2 is a diagram illustrating a structure of a PDP including a fluorescent film formed of a phosphor paste according to an embodiment of the present invention.

Claims (6)

Phosphor powder; And Fluorine-coated magnesium oxide (MgO) powder, The magnesium oxide (MgO) powder particles are phosphor paste of Cubic form. The method of claim 1, The fluorine (Fluorine) is a phosphor paste containing 100 to 10000ppm compared to the magnesium oxide (MgO) powder. The method of claim 1, A phosphor paste further comprising a binder and a solvent. According to claim 4, The binder is a cellulose resin phosphor paste. The method of claim 3, 30 to 50 wt% of the phosphor powder, 1 to 10 wt% of the magnesium oxide (MgO) powder, 5 to 10 wt% of the binder, and 30 to 60 wt% of the solvent. A plasma display panel comprising a fluorescent film formed from the phosphor paste of any one of claims 1 to 5.

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