WO2011089773A1 - Dielectric material for plasma display panel and glass plate for plasma display panel - Google Patents

Abstract

Disclosed are a dielectric material which is for a plasma display panel and which enables a dielectric layer having high transmittance and a low dielectric constant to be obtained, and a glass plate which is for a plasma display panel and which comprises a dielectric layer having high transmittance and a low dielectric constant. The dielectric material for a plasma display panel contains a glass powder which contains virtually no PbO and contains, by mole percentage, 26-45% B₂O₃, 42-57% SiO₂, 1-8% Al₂O₃, 0-10% Na₂O, 1-15% K₂O (wherein Na₂O + K₂O is 4-20%), 0-5% ZnO, and 0-6% CuO + MoO₃ + CeO₂ + MnO₂ + CoO.

Description

Dielectric material for plasma display panel and glass plate for plasma display panel

The present invention relates to a dielectric material for a plasma display panel and a glass plate for the plasma display panel.

Plasma display is a self-luminous flat panel display. The plasma display panel has excellent characteristics such as light weight and thinness and a high viewing angle, and can have a large screen. For this reason, the market of plasma display panels is rapidly expanding.

The plasma display panel includes a front glass substrate and a back glass substrate. The front glass substrate and the rear glass substrate are opposed to each other with a certain distance. The periphery of the front glass substrate and the back glass substrate is hermetically sealed with sealing glass. The inside is filled with a rare gas such as Ne or Xe. A protective plate for protecting the front glass substrate is attached to the outer surface side of the front glass substrate. A color filter is mounted on the protective plate.

A plasma discharge scan electrode is formed on the front glass substrate of the plasma display panel, and a transparent dielectric layer having a thickness of about 10 to 40 μm is formed thereon to protect the scan electrode.

Also, address electrodes for determining the position of plasma discharge are formed on the rear glass substrate. On the address electrode, an address electrode protective dielectric layer having a thickness of about 10 to 20 μm is formed to protect the address electrode. On the address electrode protection dielectric layer, barrier ribs for partitioning a plurality of discharge cells are formed. A red (R), green (G) or blue (B) phosphor is applied in the cell. In the plasma display panel, the phosphor is stimulated to emit light by generating plasma discharge in the cell and generating ultraviolet rays.

Generally, soda lime glass and high strain point glass are used for the front glass substrate and the back glass substrate of the plasma display panel. Inexpensive Ag and Cr—Cu—Cr are widely used for the scan electrode and the address electrode. As a method of forming a dielectric layer on an electrode formed on a glass substrate, in general, in order to prevent deformation of the glass substrate and suppress deterioration of characteristics due to reaction with the electrode, 500 to 600 ° C. A method of firing in a temperature range of about is employed. Therefore, the dielectric material for forming the dielectric layer is required to be able to be fired at about 500 to 600 ° C. and not to react with the electrode.

In addition to the above characteristics, the transparent dielectric layer is also required to have high transparency. For this reason, the dielectric material for forming the transparent dielectric layer is also required to easily remove bubbles during firing.

Conventionally, a dielectric material containing a PbO—B ₂ O ₃ —SiO ₂ based lead glass powder as shown in Patent Document 1 has been used to satisfy the above required characteristics. However, in recent years, the use of glass containing Pb is being regulated due to the increase in environmental protection and the movement to reduce the use of environmentally hazardous substances. In view of this, for example, Patent Document 2 proposes a dielectric material containing ZnO—B ₂ O ₃ —SiO ₂ based lead-free glass powder as a dielectric material not containing PbO.

Japanese Patent Laid-Open No. 11-60272 JP 2008-60064 A

In recent years, there has been a demand for higher contrast in plasma display panels. Accordingly, there is an increasing demand for further increasing the light transmittance of the dielectric layer. Further, further reduction in power consumption of plasma display panels has been demanded. Accordingly, there is an increasing demand for reducing the dielectric constant of the dielectric layer.

An object of the present invention is to provide a dielectric material for a plasma display panel capable of obtaining a dielectric layer having a high transmittance and a low dielectric constant, and a dielectric layer having a high transmittance and a low dielectric constant. It is to provide a glass plate for a plasma display panel.

The dielectric material for a plasma display panel of the present invention is substantially free of PbO and has a mole percentage of B ₂ O _{3 of} 26 to 45%, SiO _{2 of} more than 42 to 57%, Al ₂ O _{3 of} 1 to 8%, Contains Na ₂ O 0-10%, K ₂ O 1-15% (however, Na ₂ O + K ₂ O 4-20%), ZnO 0-5%, and CuO + MoO ₃ + CeO ₂ + MnO ₂ + CoO 0-6% Made of glass powder.

The glass plate for a plasma display panel according to the present invention includes a dielectric layer formed of the dielectric material for a plasma display panel according to the present invention.

According to the present invention, a dielectric material for a plasma display panel capable of obtaining a dielectric layer having a high transmittance and a low dielectric constant, and a dielectric layer having a high transmittance and a low dielectric constant are provided. A glass plate for a plasma display panel can be provided.

The dielectric material for the plasma display panel includes a glass powder having a basic composition of B ₂ O ₃ —SiO ₂ based lead-free glass that easily obtains a low dielectric constant.

The dielectric material for the plasma display panel is substantially free of PbO and has a molar percentage of B ₂ O _{3 of} 26 to 45%, SiO _{2 of} more than 42 to 57%, Al ₂ O _{3 of} 1 to 8%, and Na ₂ O. A glass powder containing 0-10%, K ₂ O 1-15% (however, Na ₂ O + K ₂ O 4-20%), ZnO 0-5%, and CuO + MoO ₃ + CeO ₂ + MnO ₂ + CoO 0-6% Including. Incidentally, “more than SiO ₂ 42 to 57%” means that SiO ₂ is more than 42 mol% and not more than 57 mol%.

It is preferable that the dielectric material for the plasma display panel has a mole percentage, the content of Na ₂ O + K ₂ O in the glass powder is 5 to 20%, and the content of ZnO is less than 0 to 1%. . The phrase “ZnO content is 0 to less than 1%” means that the ZnO content is 0% or more and less than 1%.

Further, the dielectric material for plasma display panel has a mole percentage, the content of Na ₂ O in the glass powder is 0 to 3%, the content of K ₂ O is 1 to 10%, and Na ₂ O + K ₂ It is preferable that the O content is 4 to 10% and the ZnO content is 1 to 5%.

B ₂ O ₃ is a component that forms a glass skeleton. The content of B ₂ O ₃ is 26 to 45 mol%. When the content of B ₂ O ₃ decreases, the dielectric constant of the glass tends to increase. On the other hand, when the content of B ₂ O ₃ is too large, the softening point of the glass tends to increase. Therefore, the dielectric material for the plasma display panel is difficult to be fired at a low temperature. Further, if the content of B ₂ O ₃ is too large, the weather resistance of the glass tends to decrease. Therefore, when the content of B ₂ O ₃ is too large, glass will be altered glass in the middle of processing the powder, it is difficult to manufacture a high-quality plasma display panel dielectric glass powder. Further, if the content of B ₂ O ₃ is too large, stability of the glass tends to decrease. Therefore, when the content of B ₂ O ₃ is too large, the glass phase separation when fired dielectric layer, the dielectric layer having a high transmittance is difficult to obtain. The content of B ₂ O ₃ is preferably 29 to 40 mol%, more preferably 30 to less than 38 mol% (30 mol% or more and less than 38 mol%).

SiO ₂ is a component that forms a glass skeleton and lowers the dielectric constant. The content of SiO ₂ is more than 42 to 57 mol% (more than 42 mol% and not more than 57 mol%). When the content of SiO ₂ decreases, the dielectric constant of the glass tends to increase. On the other hand, when the content of SiO ₂ increases, the softening point of the glass tends to increase. Therefore, the dielectric material for the plasma display panel is difficult to be fired at a low temperature. Further, there is a case where the content of SiO ₂ is the increased thermal expansion coefficient of the glass becomes too low. The content of SiO ₂ is preferably 42.5 to 56 mol%, and more preferably 43 to 55 mol%.

In order to make it easy to obtain a dielectric layer having a high transmittance by suppressing the phase separation of the glass during firing while maintaining the low dielectric constant of the glass, the molar ratio of B ₂ O ₃ to SiO ₂ (B ₂ O ₃ / SiO ₂ ) is preferably in the range of 0.55 to 0.80. If B ₂ O ₃ / SiO ₂ becomes too small, the strength of the dielectric layer tends to decrease. On the other hand, when B ₂ O ₃ / SiO ₂ becomes too large, the weather resistance of the glass tends to decrease. For this reason, if B ₂ O ₃ / SiO ₂ becomes too large, the glass is altered during the processing of the glass into a powder form, making it difficult to produce a high-quality dielectric glass powder for a plasma display panel. On the other hand, if B ₂ O ₃ / SiO ₂ becomes too large, the glass is phase-divided when the dielectric layer is fired, making it difficult to obtain a dielectric layer having high transmittance. B ₂ O ₃ / SiO ₂ is more preferably 0.60 to 0.80, and further preferably 0.67 to 0.80.

Al ₂ O ₃ is a component that improves the weather resistance of the glass, stabilizes the glass, and suppresses the phase separation of the glass during firing. The content of Al ₂ O ₃ is 1 to 8 mol%. When the content of Al ₂ O ₃ decreases, the weather resistance of the glass may be reduced. Further, when the content of Al ₂ O ₃ is reduced, glass is likely to be phase-separated in a firing step or the like, and thus it is difficult to obtain a dielectric layer having high transmittance. Further, even if the content of Al ₂ O ₃ increases, the glass is likely to be phase-divided in the firing step and the like, and it becomes difficult to obtain a dielectric layer having high transmittance. The content of Al ₂ O ₃ is preferably 1.0 to 7.4 mol%, more preferably 1.0 to 6.8 mol%, and 1.0 to 6.0 mol%. More preferably, it is 1.4 to 5.4 mol%.

Na ₂ O is a component that lowers the softening point of the glass and adjusts the thermal expansion coefficient. The content of Na ₂ O is 0 to 10 mol%. When the content ratio of Na ₂ O increases, for example, when the dielectric material is baked on the electrode containing Ag, the dielectric material and Ag easily react. Accordingly, the formed dielectric layer is easily colored. Also, if Na 2 _O content is increased, there is a case where the thermal expansion coefficient of the glass becomes too large. Furthermore, when the content of Na ₂ O increases, the stability of the glass tends to decrease and phase separation tends to occur. The content of Na ₂ O is preferably 0 to 8 mol%, and more preferably 0 to 6 mol%.

Further, it is preferable that the ZnO content is 1 mol% or more and the Na ₂ O content is 0 to 3 mol%. In this case, the content of Na ₂ O is more preferably 0-1 mol%. More preferably, the content of Na ₂ O is not substantially contained. By doing so, the phase separation of the glass can be more effectively suppressed at the time of firing the dielectric material for the plasma display panel without increasing the softening point and the dielectric constant of the glass. In this case, the ZnO content is preferably 5 mol% or less. The content of K ₂ O is preferably 1 to 10 mol%. The total amount of Na ₂ O + K ₂ O is preferably 4 to 10 mol%.

K ₂ O is a component that lowers the softening point of the glass and adjusts the thermal expansion coefficient. The content of K ₂ O is 1 to 15 mol%. When the content of K ₂ O is decreased, the softening point of the glass is increased, and firing at a low temperature may be difficult. On the other hand, when the content of K ₂ O increases, for example, when the dielectric material is baked on the electrode containing Ag, the dielectric material and Ag are likely to react. Accordingly, the formed dielectric layer is easily colored. Further, when the K 2 _O content is increased, there is a case where the thermal expansion coefficient of the glass becomes too large. Furthermore, when the content of K ₂ O increases, the stability of the glass decreases, and the glass tends to phase-separate when firing the dielectric material for the plasma display panel. The content of K ₂ O is preferably 1 to 14 mol%, and more preferably 4 to 12 mol%.

Further, ZnO is preferably contained in an amount of 1 mol% or more, and the content of K ₂ O is preferably 1 to 10 mol%. In this case, the content of K ₂ O is more preferably 4 to 10 mol%, and further preferably 4 to 9 mol%. By doing so, it is possible to make phase separation difficult during firing without increasing the softening point and dielectric constant of the glass.

The total amount of Na ₂ O and K ₂ O is 4 to 20 mol%. When the total amount of Na ₂ O and K ₂ O decreases, the softening point of the glass rises and it becomes difficult to fire at low temperatures. On the other hand, when the total amount of Na ₂ O and K ₂ O increases, when the dielectric material is baked on the electrode containing Ag, the dielectric material and Ag easily react. Accordingly, the formed dielectric layer is easily colored. Moreover, when the total amount of Na ₂ O and K ₂ O increases, the thermal expansion coefficient of the glass may become too large. Furthermore, when the total amount of Na ₂ O and K ₂ O increases, the stability of the glass tends to decrease and phase separation tends to occur. The total amount of Na ₂ O and K ₂ O is preferably 4 to 18 mol%, and more preferably 5 to 15 mol%.

In addition, the ZnO content is preferably 0 to less than 1 mol%, and the total amount of Na ₂ O and K ₂ O is preferably 5 to 20 mol%. In this case, the total amount of Na ₂ O and K ₂ O is more preferably 7 to 18 mol%, and further preferably 8 to 15 mol%. Further, the content of K ₂ O is more preferably 4 to 9 mol%. By doing so, the raise of the softening point and dielectric constant of glass can be suppressed.

Further, ZnO is preferably contained in an amount of 1 mol% or more, and the total amount of Na ₂ O and K ₂ O is preferably 4 to 10 mol%. In this case, the total amount of Na ₂ O and K ₂ O is more preferably 4 to 9 mol%, and further preferably 5 to 9 mol%. By doing so, the phase separation of the glass during firing of the dielectric material for the plasma display panel can be more effectively suppressed without increasing the softening point and the dielectric constant of the glass.

The total amount of CuO, MoO ₃ , CeO ₂ , MnO ₂ and CoO is preferably 0 to 6 mol%. In this case, a dielectric layer formed by a reaction between a dielectric material and Ag when a dielectric layer is formed on an Ag electrode (in this specification, “Ag electrode” means an electrode containing Ag). The coloring of can be suppressed. When the total amount of CuO, MoO ₃ , CeO ₂ , MnO ₂ and CoO is increased, the dielectric layer is likely to be colored by these components. The total amount of CuO, MoO ₃ , CeO ₂ , MnO ₂ and CoO is preferably 0.005 to 5 mol%, and more preferably 0.005 to 3 mol%.

_{Incidentally, CuO, MoO 3, CeO 2} , when adding at least one MnO ₂ and _CoO, CuO, MoO _3, among CeO 2, MnO ₂ and CoO, it is preferable that an essential component CuO. In this case, the reactivity between the Ag electrode and the dielectric material can be further reduced. Therefore, the CuO content is preferably 0.01 to 3.0 mol%, and more preferably 0.02 to 2.5 mol%.

Each content of MoO ₃ , CeO ₂ , MnO ₂ and CoO is preferably 0 to 5 mol%, more preferably 0.01 to 3 mol%. More preferably, the CuO content is 0.005 to 0.20 mol%, and the total amount of CuO, MoO ₃ , CeO ₂ , MnO ₂ and CoO is 0.005 to 6 mol%. By doing so, the unevenness of the coloring degree of the dielectric layer when the dielectric layer is formed on the Ag electrode can be reduced.

From the viewpoint of suppressing coloring of the dielectric layer when the dielectric layer is formed by firing the dielectric material on the Ag electrode and increasing the light transmittance of the dielectric layer, (Na ₂ O + K it is preferable that the molar ratio of _B 2 _{O 3} with respect to _{2 O) (B 2 O 3} / (Na 2 O + K 2 O)) to 3.3 to 7.2. If B ₂ O ₃ / (Na ₂ O + K ₂ O) becomes too small, the dielectric layer may be easily colored when the dielectric layer is formed on the Ag electrode. On the other hand, if B ₂ O ₃ / (Na ₂ O + K ₂ O) becomes too large, the stability of the glass is lowered, and the glass tends to be phase-separated when firing the dielectric material for the plasma display panel. On the other hand, if B ₂ O ₃ / (Na ₂ O + K ₂ O) becomes too large, the softening point of the glass tends to increase, and the dielectric material for the plasma display panel is difficult to be fired at a low temperature. B ₂ O ₃ / (Na ₂ O + K ₂ O) is more preferably 3.3 to 5.1, still more preferably 3.3 to 4.9, and 3.4 to 4.8. Even more preferably.

ZnO is a component that lowers the softening point of the glass and stabilizes the glass. The content of ZnO is 0 to 5 mol%. When the ZnO content increases, the dielectric constant of the glass tends to increase.

In order to obtain a dielectric layer that can be fired at a lower temperature without increasing the dielectric constant, the total amount of Na ₂ O and K ₂ O is set to 5 to 20 mol%, and ZnO The content of is preferably 0 to less than 1 mol%. In this case, the content of ZnO is more preferably 0 to 0.9 mol%, and further preferably 0.1 to 0.7 mol%.

Further, when it is desired to obtain a dielectric layer having a high transmittance by suppressing the phase separation of the glass during the firing of the dielectric material for the plasma display panel without increasing the dielectric constant, Na ₂ O and K ₂ O The total amount is preferably 4 to 10 mol%, and the ZnO content is preferably 1 to 5 mol%. In this case, the ZnO content is more preferably 1 to 4 mol%, and further preferably 2 to 4 mol%.

The dielectric material for a plasma display panel may contain various components in addition to the above components as long as required characteristics are not impaired. The dielectric material for a plasma display panel may contain, for example, at least one of MgO, CaO, SrO, BaO, and TiO ₂ that are components for adjusting the thermal expansion coefficient in a total amount of up to 15 mol%. The dielectric material for a plasma display panel may contain, for example, at least one of Cs ₂ O, Rb ₂ O, and the like, which are components that lower the softening point of glass, up to 10 mol%. The dielectric material for the plasma display panel is, for example, ZrO ₂ , Y ₂ O ₃ , La ₂ O ₃ , Ta ₂ O ₅ , which is a component that stabilizes glass or improves water resistance and acid resistance. At least one of SnO ₂ , WO ₃ , Nb ₂ O ₅ , Sb ₂ O ₅ , P ₂ O _{5 and the} like may be contained up to 10 mol% in total. However, the content of P ₂ O ₅ is preferably 5 mol% or less. When the content of P ₂ O ₅ is too large, the light transmittance of the dielectric layer formed by firing the dielectric material may be lowered.

Bi ₂ O ₃ is a component that lowers the softening point of the glass, but is a component that increases the dielectric constant of the glass and increases the cost. Therefore, it is preferable that the content of Bi ₂ O ₃ is not more than 5 mol%, and more preferably substantially zero.

Moreover, although PbO is a component that lowers the melting point of glass, it is preferable that the dielectric material does not substantially contain PbO because it is an environmental load substance.

In the present invention, “substantially not containing” means a level that is not actively used as a raw material but mixed as an impurity, and specifically means that the content is 0.1 mol% or less. To do.

It is preferable that the average particle diameter D ₅₀ of the dielectric material for a plasma display panel is 3.0μm or less. The maximum particle diameter _Dmax of the dielectric material for a plasma display panel is preferably 20 μm or less. If the particle size of the dielectric material for the plasma display panel is too large, bubbles tend to remain in the dielectric film obtained by firing. Therefore, it is difficult to obtain a dielectric layer having a stable withstand voltage.

The dielectric material for plasma display panel may contain ceramic powder in addition to the above glass powder in order to adjust the thermal expansion coefficient, strength after firing, and appearance. The ceramic powder is preferably at least one of alumina, zirconia, zircon, titania, cordierite, mullite, silica, willemite, tin oxide and zinc oxide, for example.

The ceramic powder is preferably spherical. In this case, the light transmittance of the dielectric layer formed by baking the dielectric material can be increased. In addition, the spherical shape means that there is no angular portion on the particle surface and the radius of the whole surface is within ± 20% from the particle center in the state observation with a photograph.

Also, from the viewpoint of increasing the light transmittance of the dielectric layer, the content of the ceramic powder in the dielectric material is preferably 0 to 20% by mass, and more preferably 0 to 10% by mass.

In the case where high light transmittance is not required for the dielectric layer, the content of the ceramic powder in the dielectric material is preferably 0 to 50% by mass, more preferably 5 to 40% by mass, More preferably, it is 10 to 40% by mass.

The average particle size of the ceramic powder is preferably 5.0 μm or less. The maximum particle size of the ceramic powder is preferably 20 μm or less. If the particle size of the ceramic powder is too large, the denseness of the dielectric layer formed by firing may be reduced.

The dielectric material for the plasma display panel can be used in any application of the transparent dielectric layer for the front glass substrate or the address electrode protective dielectric layer for the rear glass substrate. The dielectric material for the plasma display panel should be used as a material for any one of the dielectric layers on the electrode side and the dielectric layer on the opposite side of the electrode of the two or more dielectric layers. Is possible.

The glass plate for a plasma display panel according to the present invention includes a dielectric layer formed of the dielectric material for a plasma display panel according to the present invention. For this reason, in the glass plate for plasma display panels which concerns on this invention, the light transmittance of a dielectric material layer is high, and a dielectric constant is low.

The glass plate for a plasma display panel may further include a glass substrate and an electrode formed on the glass substrate and containing Ag, and a dielectric layer formed on the electrode. But in this invention, the electrode does not need to contain Ag.

The glass plate for the plasma display panel may be a front glass plate.

Next, a method of using the dielectric material for the plasma display panel of the present invention will be described. The dielectric material for a plasma display panel of the present invention can be used in the form of, for example, a paste or a green sheet.

When the dielectric material for a plasma display panel is used in the form of a paste, the paste can be produced by adding a thermoplastic resin, a plasticizer, a solvent, or the like to the dielectric material for the plasma display panel. Note that the ratio of the dielectric material in the entire paste is generally about 30 to 90% by mass.

The thermoplastic resin is a component that increases the film strength after drying and imparts flexibility. The content of the thermoplastic resin in the paste is generally about 0.1 to 20% by mass. As the thermoplastic resin, polybutyl methacrylate, polyvinyl butyral, polymethyl methacrylate, polyethyl methacrylate, ethyl cellulose, or a mixture of two or more thereof can be used.

The plasticizer is a component that controls the drying speed and imparts flexibility to the dry film. The content of the plasticizer is generally about 0 to 10% by mass. As the plasticizer, butylbenzyl phthalate, dioctyl phthalate, diisooctyl phthalate, dicapryl phthalate, dibutyl phthalate, or a mixture of two or more thereof can be used.

Solvent is a material for pasting the material. The content of the solvent is generally about 10 to 35% by mass. As the solvent, for example, terpineol, diethylene glycol monobutyl ether acetate, 2,2,4-trimethyl-1,3-pentadiol monoisobutyrate or the like can be used alone or in combination.

Preparation of the paste can be performed by preparing the above dielectric material, thermoplastic resin, plasticizer, solvent and the like and kneading them at a predetermined ratio.

In order to form a dielectric layer using such a paste, first, a paste is applied onto a glass substrate or the like on which an electrode is formed using a screen printing method, a batch coating method, or the like, and a predetermined film is formed. After forming a thick coating layer, it is dried. Thereafter, by holding and baking at a temperature of 500 to 600 ° C. for 5 to 20 minutes, a predetermined dielectric layer can be obtained. If the firing temperature is too low or the holding time is too short, sufficient sintering cannot be performed, making it difficult to form a dense dielectric layer. On the other hand, if the firing temperature is too high or the holding time is long, the glass substrate is deformed or the dielectric layer is liable to be discolored by reaction with the electrodes.

A laminate of two or more dielectric layers can be formed, for example, in the following manner. First, a lower layer dielectric forming paste is applied on a glass substrate or the like on which electrodes have been formed in advance by a screen printing method, a batch coating method or the like, dried, and then fired in the same manner as described above. Subsequently, an upper-layer dielectric forming paste is applied thereon by screen printing or a batch coating method and dried. Thereafter, the dielectric layer laminate can be obtained by firing in the same manner as described above.

When the plasma display panel dielectric material of the present invention is used in the form of a green sheet, the green sheet may be formed using a material obtained by adding a thermoplastic resin, a plasticizer, or the like to the plasma display panel dielectric material. it can. The proportion of the dielectric material in the green sheet is generally about 60 to 80% by mass.

As the thermoplastic resin and the plasticizer, the same thermoplastic resin and plasticizer as those used in the preparation of the paste can be used. The mixing ratio of the thermoplastic resin is generally about 5 to 30% by mass. The mixing ratio of the plasticizer is generally about 0 to 10% by mass.

The green sheet can be formed by forming a slurry containing a dielectric material on a polyethylene terephthalate film or the like by a doctor blade method or the like and drying it. For adjusting the slurry, a solvent such as toluene or isopropyl alcohol can be used.

As a method of forming a dielectric layer using a green sheet, there is a method in which a green sheet is placed on a glass substrate or the like on which an electrode is formed, and a coating layer is formed by thermocompression and then fired.

A laminate of two or more dielectric layers can be formed, for example, in the following manner. First, a lower dielectric layer forming green sheet is thermocompression-bonded on a glass substrate or the like on which an electrode has been formed in advance to form a lower dielectric layer and fired. A dielectric layer stack can be formed by thermocompression bonding and firing an upper dielectric forming green sheet thereon.

When the dielectric layer laminate is formed, it is preferable to form the subsequent dielectric layer by firing at a temperature in the range of about ± 20 ° C. of the firing temperature of the dielectric layer formed by firing first. By doing so, coloring of the dielectric layer due to reaction between the dielectric layer and the electrode, generation of bubbles, and the like can be suppressed.

Further, when forming the dielectric layer laminate, a part of the dielectric layers may be formed using a paste, and the remaining dielectric layers may be formed using a green sheet.

Hereinafter, the dielectric material for plasma display of the present invention will be described in detail based on examples.

First, raw materials were prepared so as to have glass compositions shown in mol% in Tables 1 to 4 below, and mixed uniformly to obtain batches. The batch was then placed in a platinum crucible and melted at 1350 ° C. for 2 hours. Thereafter, a part of the molten glass was poured out on the carbon plate, formed into a plate shape, and gradually cooled. Next, the obtained glass lump was cut and polished using a # 600 abrasive to obtain a glass sample having a size of 10 mm × 10 mm × 5 mm. The weather resistance was evaluated using the glass sample.

The remaining molten glass was formed into a thin plate shape. Subsequently, they were pulverized in a ball mill, the average particle diameter _{D 50} 3.0μm or less by air classification, the maximum particle diameter _{D max} is obtained the following glass powder sample 20 [mu] m. The glass powder sample was evaluated for softening point, thermal expansion coefficient, and dielectric constant.

Next, the above glass powder sample was mixed with a terpineol solution containing 5 mol% of ethyl cellulose and kneaded using a three-roll mill to prepare a paste. Next, this paste was applied on a glass substrate by a screen printing method, dried, held in an electric furnace at 600 ° C. for 10 minutes and baked to form a dielectric layer having a thickness of about 25 μm. Using this sample, the presence or absence of phase separation was inspected and the transmittance was measured.

Furthermore, a dielectric layer of about 25 μm was formed on the Ag electrode on the glass substrate by the same method as described above. Then, the degree of yellowing of the formed dielectric layer was evaluated.

The Ag electrode was formed using H-4040A manufactured by Shoei Chemical Industry Co., Ltd. As the glass substrate, PP-8 manufactured by Nippon Electric Glass Co., Ltd. having a thickness of 1.8 mm and 5 cm square was used.

Tables 1 to 4 show the evaluation results of Examples (Sample Nos. 1 to 18) and Comparative Examples (Sample Nos. 19 to 21).

As is apparent from the results shown in Tables 1 to 4, sample No. 1 to 18 had a small weight loss rate (ΔW) of 0.96 or less. Sample No. Nos. 1 to 18 had a softening point of 603 ° C. or lower and could be sufficiently fired at a temperature of 600 ° C. or lower. Sample No. The thermal expansion coefficient of 1 to 18 was 56 to 75 × 10 ⁻⁷ / ° C., which was consistent with the thermal expansion coefficient of a glass substrate used for a normal plasma display panel. Sample No. The dielectric constants of 1 to 18 were as low as 5.3 or less. Furthermore, sample no. In 1 to 18, almost no phase separation was observed. Sample No. The transmittance of 1 to 18 at a wavelength of 550 nm was as high as 81% or more. Sample No. For 1 to 18, b * was +5.0 or less, and yellowing due to reaction with the Ag electrode was hardly observed.

In contrast, Sample No., which is a comparative example, is used. 19 and No. In No. 21, the weight reduction rate (ΔW) was as large as 1.14 or more, and the weather resistance of the glass was low. In addition, Sample No. 19 and No. In 21, a phase separation was observed. Sample No. 19 and No. The transmittance of 21 was as low as 51%. Sample No. The dielectric constant of 20 was as high as 6.6.

In addition, the weather resistance of glass was measured in the following manner. First, the obtained glass sample was washed with water and dried at 120 ° C. for 30 minutes, and then the weight was measured to obtain the weight of the glass sample before the weather resistance evaluation. Next, the glass sample was immersed in pure water at 60 ° C. for 1 hour, dried at 120 ° C. for 30 minutes, and then weighed to obtain the weight of the glass sample after the weather resistance evaluation. And the weather resistance of glass was evaluated by calculating | requiring the weight decreasing rate ((DELTA) W) of a glass sample by subtracting the weight of the glass sample after evaluation from the weight of the glass sample before evaluation. In addition, it shows that a weather resistance is so low that a weight decreasing rate ((DELTA) W) is large. Further, if the weight reduction rate (ΔW) is greater than 1%, the glass tends to be altered by moisture in the atmosphere, making it difficult to process into powdered glass, and the glass tends to separate during firing. It becomes.

The softening point of the glass was measured by using a macro type differential thermal analyzer, and obtained by calculating the temperature of the fourth inflection point.

The thermal expansion coefficient of glass was measured in the following manner. First, each glass powder sample was press-molded. Next, after baking at 600 ° C. for 10 minutes, it was polished into a cylindrical shape having a diameter of 4 mm and a length of 20 mm. Then, using the obtained sample, the thermal expansion coefficient in a temperature range of 30 to 300 ° C. was measured based on JIS R3102. The thermal expansion coefficient of the glass substrate used for the plasma display panel is generally about 83 × 10 ⁻⁷ / ° C., and the thermal expansion coefficient of the dielectric material is 55 to 80 × 10 ⁻⁷ / ° C. If it is 0 degreeC, it will become easy to match | combine with the thermal expansion coefficient of a glass substrate, and even if it forms a dielectric material layer on a glass substrate, it will become a thing which does not generate | occur | produce a curvature in a glass substrate at the time of baking.

Dielectric constant was measured based on JIS C2141 using a sample obtained by press molding each sample, firing at 600 ° C. for 10 minutes, and polishing to a 2 mm plate. Here, the dielectric constant means a dielectric constant at 25 ° C. and 1 MHz.

Regarding the presence or absence of phase separation, the surface of the dielectric layer after firing was visually observed, and “◎” indicates that there was no white turbidity and no phase separation was observed. “○”, and those that were clearly clouded with white turbidity were evaluated as “x”.

For the transmittance, the diffuse transmittance at a wavelength of 550 nm was measured using a spectrophotometer equipped with an integrating sphere. The light transmittance was measured using U-4000 manufactured by Shimadzu Corporation. The light transmittance is the light transmittance of only the dielectric layer obtained by subtracting the light transmittance of the glass plate.

About the degree of yellowing, the color tone of the dielectric layer was evaluated by measuring the b * value using a color difference meter. In addition, it shows that it has changed into yellow, so that b * value becomes large.

Claims (8)

1. Substantially free of PbO, in mole percentages,
   B ₂ O ₃ 26-45%,
   SiO ₂ > 42 to 57%,
   Al ₂ O ₃ 1-8%,
   Na ₂ O 0-10%,
   K ₂ O 1-15% (however, Na ₂ O + K ₂ O 4-20%),
   ZnO 0-5%, and CuO + MoO ₃ + CeO ₂ + MnO ₂ + CoO 0-6%
   A dielectric material for a plasma display panel, comprising a glass powder comprising
2. The dielectric material for a plasma display panel according to claim 1, wherein the glass powder has a Na ₂ O + K ₂ O content of 5 to 20% and a ZnO content of 0 to less than 1%.
3. In mole percentage, the content of Na ₂ O in the glass powder is 0 to 3%, the content of K ₂ O is 1 to 10%, and the content of Na ₂ O + K ₂ O is 4 to 10%. The dielectric material for a plasma display panel according to claim 1, wherein the dielectric material is present and the ZnO content is in the range of 1 to 5%.
4. The plasma display panel according to any one of claims 1 to 3, wherein a molar ratio (B ₂ O ₃ / SiO ₂ ) of B ₂ O ₃ to SiO ₂ in the glass powder is in the range of 0.55 to 0.80. Dielectric material.
5. Molar ratio of _B 2 _{O 3} in the glass powder to _{(Na 2 O + K 2 O} ) (B 2 O 3 / (Na 2 O + K 2 O)) is according to claim 1 which is in the range of 3.3 to 7.2 4. The dielectric material for a plasma display panel according to any one of 4 above.
6. A glass plate for a plasma display panel comprising a dielectric layer formed of the dielectric material according to any one of claims 1 to 5.
7. The glass for a plasma display panel according to claim 6, further comprising: a glass substrate; and an electrode containing Ag formed on the glass substrate, wherein the dielectric layer is formed on the electrode. Board.
8. The glass plate for a plasma display panel according to claim 6, which is a front glass substrate.