KR20080024086A - Glass powder for covering electrode of display device - Google Patents

Abstract

A glass powder for covering an electrode of a display device is provided to show higher dielectric constant, appropriate thermal expansion coefficient, excellent storage stability and higher transmissivity while being environmentally friendly. A glass powder for covering an electrode of a display device comprises 3-45 wt% of SiO2; 10-55 wt% of B2O3; 2-20 wt% of Al2O3; 3-15 wt% of BaO; 3-50 wt% of ZnO; and 0.5-10 wt% of a material having higher dielectric constant selected from the group consisting of TiO2, ZrO2, La2O, Ta2O and a combination thereof. The glass powder further comprises P2O5; a first oxide selected from the group consisting of CuO, CeO2 and a combination thereof; CoO; MgO; CaO; a second oxide selected from the group consisting of Li2O, Na2O, K2O and a combination thereof; and a combination thereof. Further, the glass powder is used at plasma display device.

Description

Glass powder for electrode coating of display apparatus {GLASS POWDER FOR COVERING ELECTRODE OF DISPLAY DEVICE}

The present invention relates to a glass powder for electrode coating of a display device, and more particularly, to an electrode coating glass powder of a display device that is environmentally friendly and exhibits high dielectric constant and high transmittance.

In general, a plasma display panel displays an image using red (R), green (G), and blue (B) visible light generated by vacuum ultraviolet rays emitted from a plasma obtained through gas discharge to excite a phosphor. to be.

Such a plasma display panel can realize a super-large screen of 60 inches or more with a thickness of only 10 cm or less, and is a self-luminous display device such as a CRT, and has no characteristic of distortion due to color reproducibility and viewing angle. In addition, the manufacturing method is simpler than LCDs, and thus it is gaining attention as a TV and an industrial flat panel display having strengths in terms of productivity and cost.

The most common three-electrode surface discharge plasma display panel includes a front substrate including sustain electrodes and scan electrodes located on the same surface, and a rear substrate including address electrodes vertically spaced apart from each other by a predetermined distance therebetween. It has a structure in which discharge gas is sealed.

In such a plasma display panel, a dielectric layer is formed on a back substrate, and the dielectric layer is formed covering the address electrode to protect the address electrode from ion bombardment during plasma discharge, to maintain the discharge, to improve the luminous efficiency, and the phosphor It functions to increase the luminance by reflecting visible light emitted from back scattering from the back.

In order to fully exhibit such a function, such a dielectric layer is required to have physical properties such as high visible light reflection and transmittance, low thermal expansion coefficient, low firing temperature, high density, and proper dielectric constant.

As the glass composition for forming the dielectric layer, PbO-based glass compositions and Bi ₂ O ₃ -based glass compositions are conventionally used. However, PbO and Bi ₂ O ₃ are harmful to the environment. There is an active research in the glass composition.

The object of the present invention is environmentally friendly, and relates to an electrode coating glass powder of a display device exhibiting high dielectric constant and high transmittance.

In order to achieve the above object, the present invention is SiO ₂ 3 to 45% by weight; 10 to 55 weight percent B ₂ O ₃ ; Al ₂ O ₃ 2-20 weight percent; BaO 3-15 weight percent; ZnO 3-50 weight percent; And 0.5 to 10 wt% of a high dielectric constant material selected from the group consisting of TiO ₂ , ZrO ₂ , La ₂ O, Ta ₂ O, and a combination thereof.

The electrode powder glass coating of the display device of the present invention is an electrode coating glass powder that is environmentally friendly, has a high dielectric constant, has an appropriate coefficient of thermal expansion, has excellent storage stability, and has a high transmittance.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to glass powders used in display devices, and more particularly to glass powders used to form dielectric layers in plasma display panels.

Glass powder of the present invention comprises SiO ₂ 3 to 45% by weight as a main component; 10 to 55 weight percent B ₂ O ₃ ; Al ₂ O ₃ 2-20 weight percent; BaO 3-15 weight percent; And ZnO 3 to 50 wt%, and 0.5 to 10 wt% of a high dielectric constant material selected from the group consisting of TiO ₂ , ZrO ₂ , La ₂ O, Ta ₂ O, and combinations thereof.

SiO ₂ used in the glass powder of the present invention is a component for stabilizing the glass, preferably 3 to 45% by weight, more preferably 5 to 30% by weight. If the content of SiO ₂ is less than 3% by weight, there is a problem of stability and crystallization of the glass, and if it exceeds 45% by weight, there is a problem in the firing temperature due to a high softening point, which is not preferable.

B ₂ O ₃ used in the glass powder of the present invention is a component that plays an important role in glass formation, the content of which is preferably 10 to 55% by weight, more preferably 15 to 45% by weight. If the content of the B ₂ O ₃ is less than 10% by weight, the crystallization phenomenon and transparency is lowered, which is not preferable, when the content of more than 55% by weight is weak in water resistance, the softening point is raised or the glass is unstable, or the glass powder It is not preferable because the gelation phenomenon may be caused when the paste composition is prepared to form a dielectric layer.

However, in the glass powder of the present invention, since the mixed weight of B ₂ O ₃ and SiO ₂ is preferably in the range of 10 to 75% by weight, the total amount of B ₂ O ₃ and SiO ₂ is in the range of 10 to 75% by weight. . At this time, when the combined weight of B ₂ O ₃ and SiO ₂ is less than 10% by weight, there is a glass stability problem, and when it exceeds 75% by weight, there is a problem of softening point increase or transmittance decrease.

Al ₂ O ₃ is a component that serves to stabilize the glass, the content is preferably 2 to 20% by weight, more preferably 3 to 18% by weight. If the content of Al ₂ O ₃ is less than 2% by weight, the glass powder is unstable and crystallization occurs, which is not preferable. If the content of Al ₂ O ₃ exceeds 25% by weight, the transmittance is poor, which is not preferable.

The BaO is a component that modifies the role of the modifier of the glass, the softening point, the coefficient of thermal expansion and the coefficient of linear expansion, the content is preferably 3 to 15% by weight, more preferably 5 to 15% by weight. If the content of BaO is less than 3% by weight, there is a problem in that the softening point is increased. If the content of BaO is more than 15% by weight, the coefficient of thermal expansion and coefficient of linear expansion increase, which is not preferable.

The ZnO is a component for adjusting the softening point and the coefficient of thermal expansion, the content is preferably 3 to 50% by weight, more preferably 10 to 40% by weight. If the content of ZnO exceeds 50% by weight, the glass is liable to crystallize, which is not preferable.

The high dielectric constant material selected from the group consisting of TiO ₂ , ZrO ₂ , La ₂ O, Ta ₂ O, and combinations thereof is a component added to improve the dielectric constant of the glass powder of the present invention, and the content thereof is 0.5 to 10 weight. % Is preferred, with 3-9% by weight being more preferred.

If the content of the high dielectric constant material is less than 0.5% by weight, the dielectric constant does not have a great effect, and if it is more than 10% by weight, crystallization of the glass is likely to occur, which is not preferable. Further, in the glass powder of the present invention, TiO _2, ZrO _2, La ₂ O and a case of using a mixture of at least one of Ta ₂ O The mixture ratio, so if properly adjusted to the desired physical properties need not be particularly limited .

In addition, the glass powder of the present invention is P ₂ O _{5 in} addition to SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , BaO, ZnO and a high dielectric constant material; A first oxide selected from the group consisting of CuO, CeO _2, and combinations thereof; CoO; MgO; CaO; And a second oxide selected from the group consisting of Li ₂ O, Na ₂ O, K ₂ O, and combinations thereof.

Hereinafter, the content of each component is a value based on 100 parts by weight of the total glass powder.

P ₂ O ₅ is a component which plays a role similar to SiO ₂ as the glass former, and the content thereof is preferably 0 to 15 parts by weight, more preferably 5 to 10 parts by weight. When the content of P 2 O 5 exceeds 15 parts by weight, the water resistance is lowered, but due to the effect of moisture in the air, the viscosity is increased when preparing the paste composition for forming the dielectric layer using the glass powder of the present invention, which is not preferable.

The first oxide selected from the group consisting of CuO, CeO ₂ and combinations thereof has an effect of suppressing reactivity with the electrode, the content is preferably 0 to 3 parts by weight, more preferably 0.3 to 2 parts by weight. When the content of the first oxide exceeds 3 parts by weight, the transmittance is lowered in the low wavelength region, which is not preferable. When using a mixture of CuO, and CeO _2, the mixture ratio is adjusted if and as appropriate based on the intended use, it is not necessary to be particularly restricted.

CoO is a component that plays a role of coloring the glass, and serves to improve the contrast of the plasma display panel, the content is preferably 0 to 3 parts by weight, more preferably 0.2 to 1.5 parts by weight. If the content of CoO exceeds 3 parts by weight, it is not preferable because the coloring is severe and the transmittance is lowered.

MgO is a component that plays a role of adjusting the coefficient of thermal expansion, and the content of MgO is preferably 0 to 10 parts by weight, more preferably 0.1 to 8 parts by weight. If the content of MgO exceeds 10 parts by weight, there is a problem that the softening point of the glass rises, which is not preferable.

CaO is a component that plays a role of adjusting the coefficient of thermal expansion, and the content of CaO is preferably 0 to 10 parts by weight, more preferably 0.1 to 10 parts by weight. If the content of CaO exceeds 10 parts by weight, the transmittance is lowered, which is not preferable.

In addition, the second oxide selected from the group consisting of Li ₂ O, Na ₂ O, K ₂ O and combinations thereof is a component that serves to lower the softening point, the content is preferably 0 to 20 parts by weight, 0.1 to 20 parts by weight is preferred. When the content of the second oxide is more than 20 parts by weight, the softening point of the glass is lowered, but it is not preferable because crystallization is likely to occur and reactivity with the electrode easily occurs. When a mixture of Li ₂ O, Na ₂ O or K ₂ O is used, the softening point lowering characteristics are taken into consideration, and in consideration of discoloration due to Li ₂ O or Na ₂ O, or linear expansion coefficient due to K ₂ O, What is necessary is just to adjust the mixing ratio between them suitably, and it does not need to specifically limit the mixing ratio between these.

Since the glass powder of the present invention does not contain PbO or Bi ₂ O ₃ , it is environmentally friendly and can exhibit high dielectric constant of about 9 or more by appropriately adjusting the content of each component, and exhibits high transmittance of 70 to 90%. Can be. In addition, since the coefficient of thermal expansion of 70 to 82, it is possible to form a dielectric layer having excellent strength, it is possible to prevent the problem of the panel bending after the firing process when applied to the plasma display panel.

In order to use the glass powder of the present invention to produce a dielectric layer in a display device, a paste must be prepared, and the process of preparing the paste is as follows.

First, all the components constituting the glass powder are mixed. The obtained mixture is melted in a melting furnace of about 1000 ° C. or more, the melted product is pressed and then pulverized to give a glass powder having an appropriate particle size.

The glass powder and the vehicle are mixed to prepare a glass composition in the form of a paste.

As such vehicles, solvents and binders are mainly used. As solvent, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, butyl carbitol acetate, texanol, terpin oil, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol monomethyl ether acetate, γ-buty Rolactone, cellosolve acetate, butyl cellosolve acetate, tripropylene glycol, etc. can be used 1 type or in mixture of 1 or more types.

As the binder, one or more kinds of cellulose derivatives such as cellulose, hydroxy methyl cellulose, hydroxy ethyl cellulose, carboxy methyl cellulose, carboxy ethyl cellulose and carboxy ethyl methyl cellulose may be used.

The glass powder of the present invention may be usefully used for forming a dielectric layer of a display device, and may be used in any display device for this purpose, but may be particularly useful for plasma display panels.

Hereinafter, preferred embodiments of the present invention will be described. However, the following examples are only preferred embodiments of the present invention and the present invention is not limited by the following examples.

(Examples 1 to 6 and Comparative Examples 1 to 4)

SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , BaO, ZnO, TiO ₂ , K ₂ O, Li ₂ O and CuO were measured to the contents shown in Table 1 below and mixed. The obtained mixture was poured into a melting furnace at 1200 ° C. or higher to melt, and the melted product was pressed.

The compacted product was first milled to a ball mill, and then milled to a mean particle size of 2-2.5 μm by a second precision mill to prepare a glass powder.

The glass transition temperature (Tg), softening point (Ts), dielectric constant and coefficient of thermal expansion of the prepared glass powder were measured by the following method, and the results are shown in Table 1 below.

1) Glass transition temperature (Tg) and softening point measurement (Ts)

The glass products prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were measured by DSC after the induced pulverization to determine the transition temperature (Tg) and softening point (Ts) of the glass.

The measured glass transition temperature and softening point are shown in FIG. 1 for Comparative Example 1 and Example 1, Example 2 for FIG. 2, Examples 3 to 4 for FIG. 3, and Examples 5 to 6 for FIG. 1 to 4, the glass transition temperature is a value shown in the lower temperature compared to the softening point.

2) permittivity measurement

The molten glass material prepared according to Examples 1 to 6 and Comparative Examples 1 to 4 was poured into a predetermined mold and then processed into an appropriate size to prepare a specimen.

-Measuring device: LCR Meter

-Measurement method: After measuring the Cp value by applying Ag electrode material on the upper and lower surfaces of the prepared specimen, the dielectric constant value was calculated.

3) coefficient of thermal expansion

-As the measuring method uses the TMA device, the same measuring method as the glass transition temperature was used, and the average slope was calculated from 50 ° C to 350 ° C in the measured graph.

In Table 1 below, each component content unit is weight percent, and Tg and Ts units are degrees Celsius.

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 SiO ₂ 15 15 6 2 8 5 8 9.5 19 25 B ₂ O ₃ 28 43 17 37 50 40 40 35 30 30 Al ₂ O ₃ 3 12 5.5 3 8 9 10 5 14 CaO 8 ZnO 23 8.5 52 30 29 26 25 30 30 8 TiO ₂ 4 12 2 4 3.5 One 5 5.5 BaO 20 15 15 13 8 5 5 3.5 10 K ₂ O 3.5 1.5 5 3 4 Li ₂ O 3 6 2 6 3.5 6 5 7 7 CuO 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Sum 100 100 100 100 100 100 100 100 100 100 Tg 483 484 481 465 458 450 464 486 Ts 505 516 499 485 478 471 485 507 permittivity 10.5 8.4 11.5 11.8 9.2 10.3 10 9.9 10.6 9.2 Coefficient of thermal expansion 84 75 78 79 70 79 81 80 74 75 Crystallization presence X X O O X X X X X X

As shown in Table 1, the glass powder for display devices of Examples 1 to 8 has a high dielectric constant of about 9.2 or more without including PbO and Bi ₂ O ₃ which are harmful to the environment, and has a coefficient of thermal expansion of 70 to Since it is 81, it is possible to form a dielectric layer having excellent strength, and when applied to the plasma display panel, it can be predicted that the problem of the panel bending after the firing process can be prevented.

In addition, in the case of Comparative Example 1, the dielectric constant was high as 10.5, but the thermal expansion coefficient was too high as 84, which is considered to be due to the increase in thermal expansion coefficient as BaO content is excessively 20 wt%. Thus, when the coefficient of thermal expansion is higher than 82, problems of strength and problems such as bending of the panel after firing may occur, which is not preferable.

In addition, in the case of Comparative Example 2, the dielectric constant is very low as 8.4, it can be seen that it is not suitable for forming the dielectric layer of the plasma display panel.

In addition, the ZnO content is very excess of 52% by weight, and the content of SiO ₂ and B ₂ O ₃ is 6 and 17% by weight, respectively, in the case of Comparative Example 3 containing very small amounts, and the content of TiO ₂ is 12% by weight. In the case of phosphorus Comparative Example 4 it can be seen that there is a problem in storage stability due to crystallization occurs.

All simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

1 is a graph showing the glass transition temperature and the softening point temperature of the glass powder prepared according to Example 1 and Comparative Example 1 of the present invention.

Figure 2 is a graph showing the glass transition temperature and the softening point temperature of the glass powder prepared according to Example 2 of the present invention.

3 is a graph showing the glass transition temperature and the softening point temperature of the glass powder prepared according to Examples 3 to 4 of the present invention.

Figure 4 is a graph showing the measured glass transition temperature and softening point temperature of the glass powder prepared according to Examples 5 to 6 of the present invention.

Claims (12)

SiO ₂ 3-45 weight percent; 10 to 55 weight percent B ₂ O ₃ ; Al ₂ O ₃ 2-20 weight percent; BaO 3-15 weight percent; ZnO 3-50 weight percent; And 0.5 to 10 wt% high dielectric constant material selected from the group consisting of TiO ₂ , ZrO ₂ , La ₂ O, Ta ₂ O and combinations thereof Glass powder for electrode coating of a display device comprising a. The method of claim 1, The SiO ₂ content is 5 to 30% by weight of the glass coating for electrode coating of the display device. The method of claim 1, The content of the B ₂ O ₃ is 15 to 45% by weight glass powder for electrode coating of the display device. The method of claim 1, The Al ₂ O ₃ content is 3 to 18% by weight of the glass powder for electrode coating of the display device. The method of claim 1, The BaO content is 5 to 15% by weight of the glass coating for electrode coating of the display device. The method of claim 1, The content of the ZnO is 10 to 40% by weight glass powder for electrode coating of the display device. The method of claim 1, The content of the high dielectric constant material selected from the group consisting of TiO ₂ , ZrO ₂ , La ₂ O, Ta ₂ O, and combinations thereof is 3 to 9% by weight of the glass coating for electrode coating of the display device. The method of claim 1, The glass powder is P ₂ O ₅ ; A first oxide selected from the group consisting of CuO, CeO _2, and combinations thereof; CoO; MgO; CaO; A glass oxide for electrode coating of a display device, further comprising a compound selected from the group consisting of a second oxide selected from the group consisting of Li ₂ O, Na ₂ O, K ₂ O, and a combination thereof. The method of claim 2, The glass powder contains 0 to 15 parts by weight of P ₂ O ₅ , 100 to 3 parts by weight of the total glass powder, 0 to 3 parts by weight of the first oxide, and 0 to 3 parts by weight of CoO. The MgO is contained in an amount of 0 to 10 parts by weight, the CaO is contained in an amount of 0 to 10 parts by weight, and the second oxide is contained in an electrode coating glass powder of a display device. The method of claim 1, The glass powder is a glass powder for electrode coating of a display device, the mixed weight of B ₂ O ₃ and SiO ₂ is 10 to 75% by weight based on the total glass powder. The method of claim 1, The glass powder for electrode coating of the display device is used for the plasma display device. A display device comprising the glass powder of claim 1.

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