KR100685111B1 - Composition containing lead-oxide free glass powder of low softening point useful for barrier rib in pdp - Google Patents

Abstract

The present invention is a composition used to form a barrier rib in a plasma display panel, which does not contain PbO and alkali metal oxide, 5 to 40% by mol BaO, 20 to 55% by mol ZnO, 15 to 50 The present invention relates to a composition comprising a powder of glass containing M ₂ B ₂ O ₃ and 0 to 25 mol% SiO ₂ as an essential component. The glass has a softening point of 630 ° C. or less. Ceramic powder is mixed with glass powder. In addition, the composition of the present invention may be provided in the form of a paste, or alternatively, in the form of a green sheet.

Description

COMPOSITION CONTAINING LEAD-OXIDE FREE GLASS POWDER OF LOW SOFTENING POINT USEFUL FOR BARRIER RIB IN PDP}

Background of the Invention

The present invention relates to dielectric materials useful in plasma display panels (PDPs), particularly compositions used to form barrier ribs in PDPs.

Plasma display panels are known as self-emitting flat panel displays having excellent properties such as light weight, thin film type, and the like, and have attracted considerable attention due to the possibility of having a wide screen surface.

In general, a PDP consists of a front glass plate and a rear glass plate facing each other with a gap therebetween, and generate a plasma discharge by the interaction of a plurality of electrodes located on the front glass plate and an electrode located on the rear glass plate. . Multiple barrier ribs (hereinafter referred to simply as "ribs") are formed in the gap to define and maintain a gap between the front and back glass plates. The rib also serves to divide the gap into multiple discharge spaces to emit R (red), G (green) and B (blue) light.

Each rib is formed by igniting a mixture of glass powder and ceramic powder as filler. In order to prevent deformation of the back glass plate during the firing of the mixture, it is advantageous to allow the mixture to ignite at about 600 ° C. or less. For this purpose, it is common to use glass having a softening point of 630 ° C. or lower as the glass powder. The glass contains PbO and / or alkali metal oxides to lower the softening point of the glass.

However, PbO-containing glass is problematic in that PbO not only adversely affects the health of the employees who handle the glass powder, but also causes environmental pollution when the glass is discarded.

On the other hand, since alkali metal adversely affects the electrical characteristics of electrical components and electronic components, it is preferable not to use alkali metal oxide in the glass for ribs in a PDP.

Summary of the Invention

It is an object of the present invention to provide glass, which is used in compositions useful for forming ribs in PDP, which has no PbO but has a softening point of 630 ° C. or lower.

It is an object of the present invention to provide glass which is used in compositions useful for forming ribs in PDPs, free of alkali metal oxides but having a softening point of 630 ° C. or lower.                         

It is still another object of the present invention to provide a composition used to form ribs in PDP, comprising a glass powder and a filler powder free of PbO and alkali metal oxides.

The present invention seeks to provide a glass and a dielectric composition comprising the same for use in compositions useful for forming ribs in PDPs free of PbO and / or alkali metal oxides that function to lower the softening point of the glass but cause various other problems.

According to the present invention, as a glass used for a material for forming ribs in a plasma display panel, 5 to 40 mol% BaO, 20 to 55 mol% ZnO, 15 to 50 mol% B ₂ O ₃ , 0 to 25 A glass is obtained which is composed of molecular% SiO ₂ as an essential component.

The glass preferably has a softening point of 630 ° C. or less.

The glass does not contain PbO and alkali metal oxides.

According to yet another aspect of the present invention, a composition is used for forming barrier ribs in a plasma display panel. The composition comprises a powder material comprising 50 to 95 molecular percent glass powder and 5 to 50 molecular percent ceramic filler powder as essential components. Glass contains 5 to 40 molecular percent BaO, 20 to 55 molecular percent ZnO, 15 to 50 molecular percent B ₂ O ₃ , 0 to 25 molecular percent SiO ₂ , and PbO and alkali metal oxides. It does not contain and has a softening point of 630 degrees C or less.

According to one embodiment of the invention, the composition of the invention further comprises a binder, a plasticizer and a solvent to form a paste. The paste comprises 30 to 90% by weight of powdered material, 0.1 to 20% by weight of binder, 0 to 10% by weight of plasticizer and 10 to 30% by weight of solvent.

The binder is at least one component selected from the group consisting of poly butyl methacrylate, polyvinyl butyral, poly methyl methacrylate, poly ethyl methacrylate and ethyl cellulose. The plasticizer is at least one component selected from the group consisting of butyl benzyl phthalate, dioctyl phthalate, diisooctyl phthalate, dicapryl phthalate, dibutyl phthalate.

The solvent is at least one component selected from the group consisting of terpineol, diethylene glycol monobutyl ether acetate and 2,2,4-trimethyl-1,3-pentanediol monoisobutylate.

According to another embodiment, the composition of the present invention further comprises a binder and a plasticizer to form a green sheet. The green sheet comprises 60 to 80 wt% powder material, 5 to 30 wt% binder and 0 to 10 wt% plasticizer.

Description of Preferred Embodiments

For use in materials forming ribs in plasma display panels, the present invention uses BaO—ZnO—B ₂ O ₃ glass. The amount of components used in the glass is limited to the amount such that softening points of up to 630 ° C. are achieved. In addition, ZnO in the glass is increased in an amount such that a coefficient of thermal expansion comparable to that of the front and rear glass plates of the PDP is obtained compared to the conventional amount of ZnO in BaO—ZnO—B ₂ O ₃ glass.

In the glass of the present invention, BaO is contained to lower the softening point of the glass. The content of BaO is 5 to 40 molecular percent, preferably 10 to 30 molecular percent. If the content is less than 5%, the softening point is not lowered sufficiently. If the content exceeds 40%, this results in an elevated coefficient of thermal expansion not comparable to the front and rear glass plates of the PDP.

ZnO is a component contained in order to lower the softening point of glass and to adjust the thermal expansion coefficient of glass. The content of ZnO is selected from 20 to 55 molecular percent, preferably 30 to 50 molecular percent. If selected less than 20%, the intended function of ZnO is not achieved. If it exceeds 55%, the resultant glass has crystals therein, making it difficult to produce dense bodies of ribs by ignition.

B ₂ O ₃ is a glass forming component that extends the vitrification range. The content should be contained at 15 to 50 molecular percent, preferably 20 to 50 molecular percent. If the B ₂ O ₃ content is less than 15%, vitrification becomes difficult. If the content is more than 50%, the resulting glass has a softening point higher than 630 ° C., so that the compacted body of the rib cannot be produced by igniting at a temperature of 600 ° C. or lower.

In addition, SiO ₂ is a glass forming component and should be selected in an amount of 0 to 25 molecular percent, preferably 2 to 15 molecular percent. When more than 25% SiO ₂ is used, a softening point higher than 630 ° C. is also brought about, so that the compact body of the rib cannot be produced by firing at a temperature of 600 ° C. or lower.

For certain objects, other components, such as Al ₂ O ₃ , ZrO ₂ , TiO ₂ , alkaline earth metal oxides such as MgO, CaO and SrO can be added to the glass to improve the water resistance and chemical resistance, and P ₂ O ₅ can be added to stabilize the glass. The amount of additives should be limited to 20 or less, preferably 15 or less.

The composition according to the invention can include not only glass powder but also ceramic powder to form a powder mixture, thereby improving the mechanical strength of the fired layer. Ceramic powders include alumina, zircon, zirconia, titania, cordierite, mullite, silica, willemite, tin oxide and zinc oxide. It is preferable that the largest particle size Dmax of a ceramic powder is 15 micrometers or less.

In the content, the glass powder and the ceramic powder are 50 to 95% by weight and 5 to 50% by weight, preferably 60 to 90% and 10 to 40% by weight, respectively. When the ceramic powder content exceeds 50%, it is difficult to form ribs of the dense body by ignition. If the ceramic powder is used at less than 5%, the strength of the fired ribs is lowered.

In practical use, the composition according to the invention may be provided in the form of a paste or green sheet.

To prepare the dielectric composition as a paste, the glass powder or the powder mixture described above is mixed with a binder, a plasticizer and a solvent. Glass powder and powder mixtures alone will be referred to collectively as "powder material" below.

The paste is 30 to 90% by weight, preferably 50 to 80% by weight of the powder material, 0.1 to 20% by weight, preferably 0.5 to 10% by weight of the binder, 0 to 10% by weight, preferably 0 to 9% by weight % Plasticizer and 10 to 30% by weight, preferably 15 to 25% by weight of solvent.

When a paste is used to form ribs between the front and rear glass plates of the PDP, the paste is coated on the back glass plate by a screen printing or batch coating process to form a coating layer of a predetermined thickness. On the dried coating layer, a dry film resist (DFR) is laminated and then irradiated with ultraviolet rays through a mask. Thereafter, the unirradiated portion of the DFR is removed using an alkaline developer to partially expose the coating layer. Thereafter, the remaining portions are formed into ribs while the exposed portions of the coating layer are removed using sand blasting. Thereafter, after the DFR on the remaining portion is removed by the alkaline peeling solution, the remaining portion is ignited to complete the formation of the ribs. The windshield is then placed on the ribs and bonded to the ribs. Thus, the gap is defined between the front and back glass plates.

Binders are used to reinforce the dried coating layer as well as to provide flexibility to the layer. The binder is at least one component selected from the group consisting of poly butyl methacrylate, polyvinyl butyral, poly methyl methacrylate, poly ethyl methacrylate and ethyl cellulose.

Plasticizers are used to adjust the drying rate of the coating layer and to provide flexibility to the dried layer. The plasticizer is at least one component selected from the group consisting of butyl benzyl phthalate, dioctyl phthalate, diisooctyl phthalate, dicapryl phthalate, dibutyl phthalate.

Solvents are used to dissolve or suspend powdered materials, binders and plasticizers. The solvent is at least one component selected from the group consisting of terpineol, diethylene glycol monobutyl ether acetate and 2,2,4-trimethyl-1,3-pentanediol monoisobutylate.

To prepare the composition of the present invention as a green sheet, the powdered material is mixed with toluene or toluol mixed or unmixed with a binder, a plasticizer and an organic solvent such as isopropyl alcohol to form a slurry. do. The slurry is coated on the film of PET (polyethylene terephthalate) by the doctor blade method, for example, to form a thin layer. Thereafter, when the layer is dried to remove the solvent, a green sheet is obtained.

The green sheet is 60 to 80% by weight, preferably 65 to 77% by weight of the powder material, 5 to 30% by weight, preferably 10 to 25% by weight of the binder, and 0 to 10% by weight, preferably 0.1 to 7% by weight of plasticizer.

As used herein, the binders and plasticizers are the same as the binders and plasticizers described above in connection with the preparation of the paysheets, thus providing the green sheet with flexibility and self-binding properties.

When using the green sheet to form ribs on the back glass plate, the green sheet is released from the film and then laminated onto the back glass plate. The green sheet is then treated similarly to the manner described above in connection with the treatment of the coating layer of the paste. Thus, ribs are formed on the back glass plate.

Examples of the present invention will be described below.

Table 1 shows examples of the present invention (sample numbers 1 to 4) and comparative examples (sample number 5).

Table 1

Sample number The present invention Comparative Example One 2 3 4 5 Glass Composition (Molecular%) BaO ZnO B ₂ O ₃ SiO ₂ P ₂ O ₅  23 35 42--  30 40 26 2 2  20 48 22 10-  15 45 30 10-  15 18 35 32- Coefficient of thermal expansion (x 10 ^-7 / ℃) 85.0 87.1 79.5 77.6 72.1 Softening Point (℃) 602 595 592 615 653 Mixture (wt%) Glass Powder Alumina Powder Titania Powder Zirconia Powder  88 8 4-  82 8 6 4  80 15 5 5  90 10--  90 8 2- Ignition ○ ○ ○ ○ ×

Each sample was prepared by the following steps.

Fillings of raw materials were combined for each sample shown in Table 1 and melted at 1,250 ° C. for 2 hours in a platinum crucible. Thereafter, the glass body was obtained from the molten glass, pressed and crushed in an alumina ball mill and sorted by a screen having a hole of 53 mu m to obtain a glass powder.

The coefficient of thermal expansion and the softening point of the glass powder were measured and recorded. As shown in Table 1, the thermal expansion coefficients of Samples 1 to 4 were 77.6 to 87.1 (× 10 ⁻⁷ / ° C.), and the softening point was 615 ° C. or less. In comparison, Sample 5 had a high softening point of 653 ° C.

The glass powder of each sample was mixed with the ceramic powder as described in Table 1 to obtain these mixed powders, and the ignitability was tested. Sample Nos. 1 to 4 were found to have good flammability, but Sample 5 could not provide a fired dense body.

The coefficient of thermal expansion was measured according to JIS R 3102 in the temperature range of 30 to 300 ° C. of the sample pieces formed by the following steps. Each sample powder was compression molded, ignited, and ground to form a sample piece in the form of a cylindrical rod 4 mm in diameter and 40 mm in length.

When measuring the softening point, a macro type differential thermal analyzer was used and the value of the fourth inflection point was selected as the softening point.

Ignitability was tested by the following method. Each sample was mixed with a 5% terpineol solution and kneaded by a triple roll mill to form a paste. The paste was coated on a glass plate with a coefficient of thermal expansion of 85 (x10 ^-7 / deg. C) by a screening process to form a coating layer having a thickness of 200 mu m. Thereafter, the coating layer was ignited at 600 ° C. for 10 minutes in an electric furnace to form a glass thin film. Thereafter, the ink oil was coated on the surface of the glass film and then wiped off with alcohol. Samples from which ink oils can be removed were determined to have good flammability and are indicated in Table 1 by ○. On the other hand, another sample, which was infiltrated with ink oil and was hardly removed, was determined to be poorly flammable, and is indicated by × in Table 1.

As described above, the compositions of the present invention are not only able to provide dense bodies by firing at temperatures below 600 ° C., but also contain no PbO and alkali metal oxides, and thus are useful for forming ribs on the back glass plate of PDP. Do.

Claims (12)

Glass used for materials forming barrier ribs in plasma display panels, comprising 5 to 40 molecular percent BaO, 20 to 55 molecular percent ZnO, 15 to 50 molecular percent B ₂ O ₃ and 0 to 25 molecular percent SiO. Glass which contains ₂ as an essential component. The glass according to claim 1, wherein the softening point of the glass is 630 ° C. or less. The glass of claim 1, wherein the glass does not contain PbO and an alkali metal oxide. The composition according to claim 3, wherein the composition comprises 10 to 30 molecular percent BaO, 30 to 50 molecular percent ZnO, 20 to 50 molecular percent B ₂ O _3, and 2 to 15 molecular percent SiO ₂ . Glass. A composition comprising a powder material used to form barrier ribs in a plasma display panel, wherein the powder material contains 50 to 95% by weight of glass powder and 5 to 50% by weight of ceramic filler powder as essential ingredients, and the glass contains 5 to 40 Molecular Weight BaO, 20 to 55 Molecular Weight ZnO, 15 to 50 Molecular Weight B ₂ O ₃ and 0 to 25 Molecular Weight SiO ₂ as essential components, the glass does not contain PbO and alkali metal oxide A composition having a softening point of 630 ° C. or less. 6. The glass of claim 5 wherein the glass comprises 10 to 30 molecular percent BaO, 30 to 50 molecular percent ZnO, 20 to 50 molecular percent B ₂ O ₃ and 2 to 15 molecular percent SiO ₂ . Composition. The method of claim 5, further comprising a binder, a plasticizer and a solvent to form the paste, wherein the paste is 30 to 90% by weight of powdered material, 0.1 to 20% by weight of binder, 0 to 10% by weight of plasticizer. And 10 to 30% by weight of a solvent. The method of claim 7, wherein the binder is at least one component selected from the group consisting of poly butyl methacrylate, polyvinyl butyral, poly methyl methacrylate, poly ethyl methacrylate and ethyl cellulose, the plasticizer is butyl benzyl phthalate, At least one component selected from the group consisting of dioctyl phthalate, diisooctyl phthalate, dicapryl phthalate and dibutyl phthalate. 8. The process of claim 7, wherein the solvent is at least one component selected from the group consisting of terpineol, diethylene glycol monobutyl ether acetate and 2,2,4-trimethyl-1,3-pentanediol monoisobutylate. Composition. The method of claim 5, further comprising a binder and a plasticizer to form a green sheet, wherein the green sheet is 60 to 80% by weight of powdered material, 5 to 30% by weight of binder and 0 to 10% by weight of plasticizer. Composition comprising a. The method of claim 10 wherein the binder is at least one component selected from the group consisting of poly butyl methacrylate, polyvinyl butyral, poly methyl methacrylate, poly ethyl methacrylate and methyl cellulose, the plasticizer being butyl benzyl phthalate, And at least one component selected from the group consisting of dioctyl phthalate, diisooctyl phthalate, dicapryl phthalate and dibutyl phthalate. The ceramic filler powder according to claim 5, wherein the ceramic filler powder is selected from the group consisting of alumina powder, zircon powder, zirconia powder, titania, cordierite, mullite, silica, willemite, tin oxide and zinc oxide. At least one component selected.