JP2012033454A - Dielectric material for plasma display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric material for a plasma display panel, which can be calcined at a temperature of 600°C or less, causes no phase separation at the time of calcination and less yellowing due to reaction with an Ag electrode, and can obtain a dielectric layer high in transmittance and low in a dielectric constant, and to provide a glass plate for the plasma display panel including the dielectric layer formed by using the dielectric material.SOLUTION: A dielectric material for a plasma display panel according to the present invention comprises a BO-SiO-based glass powder. The glass powder is substantially free from PbO, and comprises glass containing, by mole percentage, 26 to 45% of BO, more than 42% to 57% of SiO, 1 to 8% of AlO, 0 to 10% of NaO, 1 to 15% of KO, 4 to 20% of NaO+KO, 0 to 5% of ZnO and 0 to 6% of CuO+MoO+CeO+MnO+CoO.

Description

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

  The plasma display is a self-luminous flat panel display, and has excellent characteristics such as light weight and thinness, a high viewing angle, and a large screen, so that the market is rapidly expanding.

  The plasma display panel has a structure in which a front glass substrate and a back glass substrate are opposed to each other at a constant interval, and the periphery thereof is hermetically sealed with sealing glass. A protective plate for protecting the front glass substrate is attached to the outer surface side of the front glass substrate, and a color filter is attached on the protective plate. The inside of the panel is filled with a rare gas such as Ne or Xe.

  A scanning electrode for plasma discharge is formed on the front glass substrate used for the above applications, and a dielectric layer (transparent dielectric layer) of about 10 to 40 μm is formed thereon to protect the scanning electrode. Has been.

  In addition, an address electrode for determining the position of plasma discharge is formed on the rear glass substrate, and a dielectric layer (address electrode protection dielectric layer) of about 10 to 20 μm is formed thereon to protect the address electrode. Is formed. In addition, barrier ribs are formed on the address electrode protection dielectric layer to partition discharge cells, and phosphors of red (R), green (G), and blue (B) are coated in the cells. The phosphor is stimulated to emit light by causing plasma discharge to generate 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, and materials made of inexpensive Ag or Cr—Cu—Cr are used for the scan electrode and the address electrode. Is widely used. In forming a dielectric layer on a glass substrate on which an electrode is formed, a method of firing in a temperature range of about 500 to 600 ° C. is used in order to prevent deformation of the glass substrate and suppress deterioration of characteristics due to reaction with the electrode. It is taken. Therefore, the dielectric material is required to be compatible with the thermal expansion coefficient of the glass substrate, be baked at 500 to 600 ° C., and not react with the electrode.

  In addition to the above characteristics, the transparent dielectric layer is also required to have high transparency. Therefore, the dielectric material for forming the transparent dielectric layer is also required to be free of bubbles during firing. ing.

In order to satisfy the above required characteristics, a dielectric material containing PbO—B ₂ O ₃ —SiO ₂ based lead glass powder as shown in Patent Document 1 has been used. From the movement of reducing the use of load substances, a dielectric material containing ZnO—B ₂ O ₃ —SiO ₂ based lead-free glass powder as shown in Patent Document 2 has been proposed.

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

  By the way, due to the recent eco-oriented trend, low power consumption has become a major issue in plasma display panels, and there is a strong demand for dielectric layers having a lower dielectric constant.

As a method for lowering the dielectric constant of the dielectric layer, ZnO—B ₂ O ₃ —SiO ₂ based lead-free glass capable of lowering the melting point of glass relatively easily contains a large amount of B ₂ O ₃ and SiO _2. It is conceivable to reduce the ZnO content.

However, in ZnO—B ₂ O ₃ —SiO ₂ -based lead-free glass, when a large amount of B ₂ O ₃ and SiO ₂ are contained and the content of ZnO is reduced, the softening point of the glass is increased, and the temperature is 600 ° C. or lower. There arises a problem that baking in the steel becomes difficult. In addition, the weather resistance of the glass may be lowered or the glass may become unstable, and the glass may be phase-divided during firing, so that a dielectric layer having high transmittance may not be obtained.

Therefore, in this composition system glass, in order to lower the softening point of the glass, it is conceivable to contain a large amount of an alkali metal oxide of Na ₂ O or K ₂ O. There is a problem that many bubbles remain in the glass film (dielectric layer) and a dielectric layer having high transmittance cannot be obtained. Further, when Ag is used as the electrode material, the dielectric material and Ag react with each other, causing a problem that the dielectric layer is yellowed and the image is difficult to see.

  Particularly, in recent years, plasma display panels are required to have high contrast quality, and a dielectric layer having high transmittance and less yellowing is required.

  An object of the present invention is to obtain a dielectric layer that can be fired at a temperature of 600 ° C. or less, does not undergo phase separation during firing, has little yellowing due to reaction with the Ag electrode, and has high transmittance and low dielectric constant. An object of the present invention is to provide a plasma display panel glass plate comprising a dielectric material for a plasma display panel and a dielectric layer formed using the dielectric material.

As a result of various experiments, the present inventor has found that B ₂ O ₃ —SiO ₂ based lead-free glass having a large content of B ₂ O ₃ and SiO ₂ and a small content of ZnO, Na ₂ O and K Alkali metal oxides such as ₂ O and Al ₂ O ₃ are contained as essential components, and by strictly limiting the content, firing can be performed at a temperature of 600 ° C. or less, phase separation during firing is suppressed, The present inventors have found and proposed that a dielectric layer having a high transmittance and a low dielectric constant can be obtained with little yellowing due to a reaction with an Ag electrode.

That is, the dielectric material for a plasma display panel of the present invention is a dielectric material for a plasma display panel made of a B ₂ O ₃ —SiO ₂ glass powder, and the glass powder does not substantially contain PbO, in molar _{percent, B 2 O 3 26~45%,} SiO 2 42 super _{~57%, Al 2 O 3 1~8} %, Na 2 O 0~10%, K 2 O 1~15%, Na 2 O + K 2 It is characterized by being made of glass containing O 4-20%, ZnO 0-5%, CuO + MoO ₃ + CeO ₂ + MnO ₂ + CoO 0-6%.

  In addition, a glass plate for a plasma display panel according to the present invention is characterized by comprising a dielectric layer formed of the above dielectric material.

  The dielectric material for a plasma display panel of the present invention has a low dielectric constant and is easily baked at a temperature of 600 ° C. or lower. In addition, there are few bubbles remaining in the glass film after firing, discoloration due to reaction with the Ag electrode hardly occurs, and a dielectric layer having high transmittance can be formed. Therefore, it is suitable as a glass plate for a plasma display panel comprising a dielectric material for a plasma display panel and a dielectric layer formed using the dielectric material.

The dielectric material for a plasma display panel according to the present invention has a basic composition of B ₂ O ₃ —SiO ₂ based lead-free glass that can easily obtain a low dielectric constant relatively easily.

In general, this type of glass has a high content of B ₂ O ₃ and SiO ₂ , so that the glass has a high softening point, the weather resistance of the glass is low, and the glass is also unstable. Therefore, when this type of glass is used as a dielectric material, it becomes difficult to fire at a temperature of 600 ° C. or lower. Further, the glass is denatured by moisture in the atmosphere and it becomes difficult to process into a powder form, or the glass is phase-divided during firing, and it tends to be difficult to obtain high transmittance. Therefore, in the present invention, 4 mol% or more of an alkali metal oxide such as Na ₂ O or K ₂ O, which is a component that lowers the softening point of the glass, is contained, and the glass is stabilized to improve the weather resistance of the glass. Al ₂ O ₃ which is a component to be added is contained in an amount of 1 mol% or more. Therefore, it is possible to obtain a dielectric layer that can be fired at a temperature of 600 ° C. or less and does not undergo phase separation during firing, and has a high transmittance and a low dielectric constant.

Glass powder used in the present invention are substantially free of PbO, in molar _{percentage, B 2 O 3 26~45%,} SiO 2 42 super _{~57%, Al 2 O 3 1~8} %, Na 2 O _{0~10%, K 2 O 1~15%} , used if glass having Na 2 O + K 2 O 4~20 %, 0~5% ZnO, the composition of _{CuO + MoO 3 + CeO 2 +} MnO 2 + CoO 0~6% be able to. When the content of alkali metal oxide is increased and the content of ZnO is decreased, it is easy to obtain a dielectric layer that can be fired at a lower temperature without significantly increasing the dielectric constant. When the content of is increased and the content of the alkali metal oxide is decreased, a dielectric layer having a high transmittance is easily obtained without causing a phase separation during firing without significantly increasing the dielectric constant.

Specifically, the glass powder is substantially free of PbO, and in molar percentage, B ₂ O ₃ 26 to 45%, SiO ₂ 42 to 57%, Al ₂ O ₃ 1 to 8%, Na ₂ O _{0~10%, K 2 O 1~15%} , Na 2 O + K 2 O 5~20%, ZnO less than 0 to _1%, as long as it is made of a _{CuO + MoO 3 + CeO 2 +} MnO 2 + CoO 0~6% content to glass , Easy to obtain a dielectric layer that can be fired at a lower temperature without significantly increasing the dielectric constant, and substantially free of PbO and in mole percentage, B ₂ O ₃ 26-45%, SiO ₂ 42 super _{~57%, Al 2 O 3 1~8} %, Na 2 O 0~3%, K 2 O 1~10%, Na 2 O + K 2 O 4~10%, 1~5% ZnO, CuO + MoO ₃ + CeO ₂ + MnO ₂ + CoO 0 If it is made of glass containing ˜6%, a dielectric layer having a high transmittance can be easily obtained without significantly increasing the dielectric constant, making it difficult for phase separation to occur during firing.

  In the present invention, the reason for limiting the glass composition as described above is as follows.

B ₂ O ₃ is a component that forms a glass skeleton, and its content is 26 to 45%. When the content of B ₂ O ₃ decreases, the dielectric constant of the glass tends to increase. On the other hand, if the content is too large, the softening point of the glass tends to be high, and it becomes difficult to fire at a temperature of 600 ° C. or lower. In addition, the weather resistance of the glass is lowered and the glass is denatured, making it difficult to process into a powder form, or the stability of the glass tends to be remarkably lowered. It is difficult to obtain a dielectric layer having a high transmittance due to phase separation. A preferable range of B ₂ O ₃ is 29 to 40%, and a more preferable range is 30 to less than 38%.

SiO ₂ is a component that forms a glass skeleton and lowers the dielectric constant, and its content is more than 42 to 57%. When the content of SiO ₂ decreases, the dielectric constant of the glass increases significantly. On the other hand, when the content increases, the softening point of the glass tends to increase, and it becomes difficult to fire at a temperature of 600 ° C. or lower. Moreover, since the thermal expansion coefficient of glass becomes too smaller than the glass substrate, the glass substrate is likely to warp during firing. A preferable range of SiO ₂ is 42.5 to 56%, and a more preferable range is 43 to 55%.

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 a low dielectric constant, the value of B ₂ O ₃ / SiO ₂ is set to a molar ratio of 0.00. It is preferable to be in the range of 55 to 0.80. If the value of B ₂ O ₃ / SiO ₂ becomes too small, the strength of the dielectric layer tends to decrease, and a glass substrate having high strength tends to be difficult to obtain. On the other hand, if the value of B ₂ O ₃ / SiO ₂ becomes too large, the weather resistance of the glass is lowered and the glass is denatured, making it difficult to process into a powder form, or the stability of the glass tends to be lowered. Therefore, when the dielectric layer is fired, it is difficult to obtain a dielectric layer having a high transmittance due to phase separation of the glass. A more preferable range of B ₂ O ₃ / SiO ₂ is 0.60 to 0.80, and a more preferable range is 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, and its content is 1 to 8%. When the content of Al ₂ O ₃ decreases, the weather resistance of the glass decreases and the glass changes in quality, making it difficult to process into a powder form. In addition, it is difficult to obtain the effect of suppressing phase separation, and as a result, it is difficult to obtain a dielectric layer having high transmittance. On the other hand, even if the content is increased, it is difficult to obtain the effect of suppressing phase separation, and it becomes difficult to obtain a dielectric layer having high transmittance. The preferable range of Al ₂ O ₃ is 1.0 to 7.4%, the more preferable range is 1.0 to 6.8%, the still more preferable range is 1.0 to 6.0%, and the most preferable range is 1. .4 to 5.4%.

Na ₂ O is a component that lowers the softening point of the glass or adjusts the thermal expansion coefficient, and its content is 0 to 10%. When the content is increased, when Ag is used for the electrode, the dielectric material and Ag react with each other, the dielectric layer is likely to turn yellow (yellowing), and the image becomes difficult to see. Moreover, the thermal expansion coefficient becomes larger than that of the glass substrate, and it becomes difficult to match the thermal expansion coefficient of the glass substrate. Furthermore, the stability of the glass tends to decrease, and when the dielectric layer is fired, it is difficult to obtain a dielectric layer having a high transmittance due to the phase separation of the glass. A preferable range of Na ₂ O is 0 to 8%, and a more preferable range is 0 to 6%. If you want to obtain a dielectric layer with high transmittance by suppressing phase separation during firing without significantly increasing the softening point and dielectric constant of the glass, lower the glass softening point and stabilize the glass. In addition to containing 1% or more of ZnO, which is a component to be added, the content of Na ₂ O is preferably 0 to 3%, more preferably 0 to 1%, and still more preferably not substantially contained. is there.

K ₂ O is a component that lowers the softening point of the glass or adjusts the thermal expansion coefficient, and its content is 1 to 15%. When the content of K ₂ O decreases, the softening point of the glass increases and it becomes difficult to fire at a temperature of 600 ° C. or lower. On the other hand, when the content is increased, when Ag is used for the electrode, the dielectric material and Ag react with each other, and the dielectric layer tends to turn yellow, which tends to cause a problem that the image is difficult to see. In addition, the thermal expansion coefficient tends to be larger than that of the glass substrate, making it difficult to match the thermal expansion coefficient of the glass substrate. A preferable range of K ₂ O is 1 to 14%, and a more preferable range is 4 to 12%. If you want to obtain a dielectric layer with high transmittance by suppressing phase separation during firing without significantly increasing the softening point and dielectric constant of the glass, lower the glass softening point and stabilize the glass. While containing 1% or more of ZnO as a component to be added, the content of K ₂ O is preferably 1 to 10%, more preferably 4 to 10%, and further preferably 4 to 9%.

In order to suppress yellowing of the dielectric layer due to the reaction with Ag, and to be able to be fired at a temperature of 600 ° C. or less and to have a thermal expansion coefficient suitable for the glass substrate, Na ₂ O and K ₂ O are combined. The amount is preferably 4 to 20%. When the total amount of these components decreases, the softening point of the glass increases and it becomes difficult to fire at a temperature of 600 ° C. or lower. On the other hand, when the total amount of these components is increased, when Ag is used for the electrode, the dielectric material and Ag react with each other, and the dielectric layer tends to turn yellow, and the problem that the image becomes difficult to see is likely to occur. In addition, the thermal expansion coefficient tends to be larger than that of the glass substrate, making it difficult to match the thermal expansion coefficient of the glass substrate. Furthermore, the stability of the glass tends to decrease, and when the dielectric layer is fired, it is difficult to obtain a dielectric layer having a high transmittance due to the phase separation of the glass. A preferable range of the total amount of these components is 4 to 18%, and a more preferable range is 5 to 15%. When it is desired to obtain a dielectric layer that can be fired at a lower temperature without significantly increasing the dielectric constant, ZnO is made less than 1% and Na ₂ O and K ₂ O are combined in a total amount. It is preferable to make it 5 to 20%, More preferably, it is 7 to 18%, More preferably, it is 8 to 15%. If you want to obtain a dielectric layer with high transmittance by suppressing phase separation during firing without significantly increasing the softening point and dielectric constant of the glass, lower the glass softening point and stabilize the glass. In addition to containing 1% or more of ZnO, which is a component to be added, it is preferable that Na ₂ O and K ₂ O are combined in a total amount of 4 to 10%, more preferably 4 to 9%, still more preferably 5 to 9 %.

When the dielectric material of the present invention is formed on an Ag electrode, CuO, MoO ₃ , CeO ₂ , MnO ₂ and CoO are combined to suppress discoloration of the dielectric layer due to the reaction between the dielectric material and Ag. What is necessary is just to contain to 6% by quantity. When the total amount of these components increases, the dielectric layer is likely to be colored by these components. A preferable range of the total amount of these components is 0.005 to 5%, and a more preferable range is 0.005 to 3%. Of these components, CuO has the greatest effect of suppressing yellowing, and CuO is more preferably an essential component. In this case, the content of CuO is 0.01 to 3.0% (desirably 0.02 to 2.5%) and MoO ₃ , CeO ₂ , MnO ₂ and CoO are each preferably 0 to 5% (desirably 0.01 to 3%). Further, in the case where variation occurs in the effect of suppressing the discoloration of CuO due to variations in the firing conditions, the CuO content is limited to 0.005 to 0.20%, and CuO, MoO ₃ , CeO ₂ , MnO ₂ and CoO are added. It is desirable to adjust the content so that the total amount is 0.005 to 6%.

Moreover, in order to make it easy to obtain a dielectric layer having high transmittance by suppressing yellowing of the dielectric layer due to the reaction between the phase separation of the glass and Ag during firing, B ₂ O ₃ / (Na ₂ O + K ₂ O ) In a molar ratio of 3.3 to 7.2. When the value of B ₂ O ₃ / (Na ₂ O + K ₂ O) becomes too small, when Ag is used for the electrode, the dielectric material and Ag react, and the dielectric layer tends to yellow, and the image is Problems that are difficult to see occur. On the other hand, if the value of B ₂ O ₃ / (Na ₂ O + K ₂ O) becomes too large, the stability of the glass tends to decrease, and when the dielectric layer is baked, the glass is phase-separated and has high transmission. It becomes difficult to obtain a dielectric layer having a ratio. Further, the softening point of the glass tends to increase, and it becomes difficult to fire at a temperature of 600 ° C. or lower. A more preferable range of B ₂ O ₃ / (Na ₂ O + K ₂ O) is 3.3 to 5.1, a further preferable range is 3.3 to 4.9, and a most preferable range is 3.4 to 4 .8.

  ZnO is a component that lowers the softening point of the glass and stabilizes the glass, but it is also a component that remarkably increases the dielectric constant of the glass, and its content is 0 to 5%. When the content increases, the dielectric constant of the glass tends to increase remarkably. In addition, when it is desired to obtain a dielectric layer that can be fired at a lower temperature without significantly increasing the dielectric constant, the content of the alkali metal oxide is increased and the content of ZnO is set to 0 to 1. % Is preferable, more preferably 0 to 0.9%, and still more preferably 0.1 to 0.7%. In addition, when it is desired to obtain a dielectric layer having a high transmittance by suppressing phase separation during firing without significantly increasing the dielectric constant, the content of ZnO is reduced while reducing the content of alkali metal oxides. The content is preferably 1 to 5%, more preferably 1 to 4%, and still more preferably 2 to 4%.

In addition to the above components, the dielectric material of the present invention can contain various components as long as the required characteristics are not impaired. For example, MgO, CaO, SrO, BaO and TiO ₂ which are components for adjusting the coefficient of thermal expansion are combined up to 15% in total, and Cs ₂ O, Rb ₂ O, etc. are combined in order to lower the softening point of glass. In order to stabilize the glass up to 10% and improve water resistance and acid resistance, ZrO ₂ , Y ₂ O ₃ , La ₂ O ₃ , Ta ₂ O ₅ , SnO ₂ , WO ₃ , Nb ₂ O ₅ , Sb ₂ O ₅ , P ₂ O _{5 and the} like can be added up to 10% in total. However, since P ₂ O ₅ is also a component that devitrifies the glass and makes it difficult to obtain a transparent fired film, its content is preferably 5% or less.

Bi ₂ O ₃ is a component that lowers the softening point of the glass. Therefore, by containing Bi ₂ O ₃ , the content of the alkali metal oxide component is reduced and the dielectric is reacted with Ag. It is possible to make yellowing of the layer difficult to occur. However, Bi ₂ O ₃ is a component that increases the dielectric constant of the glass and significantly increases the cost. Therefore, its content is preferably 5% or less, more preferably not substantially contained. is there.

  PbO is a component that lowers the melting point of the glass, but it is also an environmentally hazardous substance, so it is preferably not substantially contained.

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

As for the particle size of the glass powder in the dielectric material for a plasma display panel of the present invention, it is desirable to use one having an average particle size D ₅₀ of 3.0 μm or less and a maximum particle size D _max of 20 μm or less. If either of these exceeds the upper limit, large bubbles are likely to remain in the fired film, making it difficult to obtain a dielectric layer having a stable withstand voltage.

  The dielectric material for a plasma display panel of the present invention may contain a ceramic powder in addition to the glass powder in order to adjust the thermal expansion coefficient, the strength after firing, and the appearance. If the ceramic powder is increased, it cannot be sufficiently sintered and it becomes difficult to form a dense film. As the ceramic powder, for example, alumina, zirconia, zircon, titania, cordierite, mullite, silica, willemite, tin oxide, zinc oxide and the like can be used alone or in combination. Further, when it is desired to avoid a decrease in the transparency of the dielectric layer due to the introduction of the ceramic powder, a part or all of the ceramic powder may be spherical. As used herein, the term “spherical” means that the particle surface does not have an angular portion and the radius of the entire surface from the particle center is within ± 20% in the state observation with a photograph. The ceramic powder preferably has an average particle size of 5.0 μm or less and a maximum particle size of 20 μm or less.

  The dielectric material for a plasma display panel of the present invention can be used in any application of a transparent dielectric layer for a front glass substrate or an address electrode protective dielectric layer for a rear glass substrate. It can be used as a material for a lower dielectric layer that is in contact with a dielectric electrode having a dielectric structure of two or more layers, or an upper dielectric layer that is formed on the lower dielectric layer and does not directly contact the electrode. Is possible. Of course, it can also be used in a dielectric material formed on an electrode other than Ag, or in other applications such as a partition wall forming material. When using as a transparent dielectric material, it can be used by making content of the said ceramic powder 0-20 mass% (preferably 0-10 mass%). By setting the content of the ceramic powder in this way, it is possible to obtain a fired film having high transparency while suppressing the scattering of visible light due to the addition of the ceramic powder. When used as an address electrode protective dielectric material or a partition wall material, the ceramic powder is contained in a range of 0 to 50% by mass (more preferably 5 to 40% by mass, still more preferably 10 to 40% by mass). Can be used. By setting the content of the ceramic powder in this way, a fired film having high strength or excellent acid resistance can be obtained.

  Next, the usage method of the dielectric material for plasma display panels of this invention is demonstrated. The material of the present invention can be used in the form of, for example, a paste or a green sheet.

  When used in the form of a paste, a thermoplastic resin, a plasticizer, a solvent, etc. are used together with the dielectric material described above. In general, the proportion of the dielectric material in the entire paste is about 30 to 90% by mass.

  The thermoplastic resin is a component that increases the film strength after drying and imparts flexibility, and the content is generally about 0.1 to 20% by mass. As the thermoplastic resin, polybutyl methacrylate, polyvinyl butyral, polymethyl methacrylate, polyethyl methacrylate, ethyl cellulose and the like can be used, and these are used alone or in combination.

  The plasticizer is a component that controls the drying speed and imparts flexibility to the dry film, and the content thereof is generally about 0 to 10% by mass. As the plasticizer, butylbenzyl phthalate, dioctyl phthalate, diisooctyl phthalate, dicapryl phthalate, dibutyl phthalate and the like can be used, and these are used alone or in combination.

  The solvent is a material for pasting the material, and its content 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.

  The paste can be prepared 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, these pastes are applied onto a glass substrate on which electrodes are formed by 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. Then, a predetermined dielectric layer can be obtained by holding and baking at a temperature of 500 to 600 ° C. for 5 to 20 minutes. If the firing temperature is too low or the holding time is shortened, sufficient sintering cannot be performed, and it becomes difficult to form a dense film. 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.

  When forming a dielectric layer having a dielectric structure of two or more layers, the thickness of the lower layer dielectric forming paste is increased by a screen printing method or a batch coating method on a glass substrate on which electrodes are previously formed. After applying to about 20 to 80 μm and drying, baking is performed in the same manner as described above. Subsequently, an upper dielectric layer forming paste is applied thereon by screen printing, a batch coating method or the like so as to have a film thickness of about 60 to 160 μm and dried. Then, it can obtain by baking similarly to the above.

  When the material of the present invention is used in the form of a green sheet, a thermoplastic resin, a plasticizer or the like is used together with the dielectric material described above. The ratio 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 used in the preparation of the paste can be used, and the mixing ratio of the thermoplastic resin is about 5 to 30% by mass. Generally, the mixing ratio of the plasticizer is generally about 0 to 10% by mass.

  As a general method for producing a green sheet, the above-described dielectric material, thermoplastic resin, plasticizer, etc. are prepared, and a main solvent such as toluene or an auxiliary solvent such as isopropyl alcohol is added to these to form a slurry. The slurry is formed into a sheet on a film of polyethylene terephthalate (PET) or the like by the doctor blade method. After forming the sheet, the solvent and the solvent can be removed by drying to obtain a green sheet.

  In order to form the dielectric layer using the green sheet obtained as described above, the green sheet is placed on the glass substrate on which the electrode is formed, and the coating layer is formed by thermocompression bonding. The dielectric layer can be obtained by firing in the same manner as the paste.

  When forming a dielectric layer having a dielectric structure of two or more layers, after forming a lower dielectric film by thermocompression bonding a green sheet for forming a lower dielectric on a glass substrate on which electrodes have been previously formed. Baking is performed in the same manner as in the case of the paste described above. Subsequently, the upper dielectric layer forming green sheet is thermocompression-bonded thereon to form an upper dielectric layer, and then fired in the same manner as described above.

  In forming a dielectric layer having two or more dielectric structures, when the upper dielectric layer is formed, the temperature at which the lower dielectric layer is baked is ± 20 ° C., regardless of whether a paste or a green sheet is used. If the upper dielectric material is fired within the range, yellowing of the dielectric layer due to Ag can be suppressed, and foaming at the interface between the lower layer and the upper layer can be suppressed while maintaining the shape of the lower dielectric layer. it can. In addition, when the firing temperatures of the upper dielectric material and the lower dielectric material are the same, in addition to the above formation method, after drying the lower dielectric film, forming the upper dielectric film, drying, A method of simultaneously firing both layers at a temperature can also be employed.

  Further, it is also possible to use a hybrid forming method in which the lower dielectric layer is formed using a paste and the upper dielectric layer is formed using a green sheet.

  As described above, when Ag is used for the electrode by applying or arranging the dielectric material of the present invention on the glass substrate on which the electrode is formed, firing, and forming a dielectric layer, the dielectric material by Ag There is little discoloration of a layer, it is excellent in transparency, and the glass plate for plasma display panels of this invention can be obtained.

  In the above description, a method using a paste or a green sheet is described as an example of a dielectric forming method. However, the dielectric material for a plasma display panel of the present invention is limited to these methods. Instead, it is a material that can be applied to other forming methods such as a photosensitive paste method and a photosensitive green sheet method.

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

  Tables 1 to 4 show Examples (Sample Nos. 1 to 18) and Comparative Examples (Sample Nos. 19 to 21) of the present invention, respectively.

  Each sample in the table was prepared as follows.

  First, the raw materials were prepared so as to have the glass composition shown in the table in mol%, and mixed uniformly. Subsequently, it was put into a platinum crucible and melted at 1350 ° C. for 2 hours. Thereafter, a part of the molten glass is poured onto a carbon plate, formed into a plate shape, slowly cooled, and then the glass lump is cut and polished with a # 600 abrasive to obtain 10 mm × 10 mm × A glass sample having a size of 5 mm was obtained and its weather resistance was evaluated.

Further, the molten glass residue was formed into a thin plate shape. Subsequently, they were pulverized in a ball mill, an air classifier to a mean particle diameter D ₅₀ 3.0μm or less, the maximum particle diameter D _max to obtain a sample of the following glass powder 20 [mu] m. The softening point, thermal expansion coefficient and dielectric constant of each glass powder sample thus obtained were evaluated.

  Next, the above glass powder sample is mixed with a terpineol solution containing 5% of ethyl cellulose, kneaded with a three-roll mill to form a paste, and then this paste is glass so that a fired film of about 25 μm is obtained. It was applied onto the substrate by screen printing, dried, held in an electric furnace at 600 ° C. for 10 minutes and baked to obtain a glass substrate sample on which a dielectric layer was formed. About each sample obtained in this way, the presence or absence of phase separation and the transmittance were measured.

  Further, by the same method as described above, the above paste was applied onto a glass substrate on which an Ag electrode was formed and baked to form a dielectric layer of about 25 μm, and the degree of yellowing was evaluated.

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

As can be seen from the table, the sample No. Nos. 1 to 18 had a weight reduction rate (ΔW) as small as 0.96 or less, and had sufficient weather resistance to be processed into a powder form. Further, the softening point of the glass was 603 ° C. or lower, and it could be sufficiently fired at a temperature of 600 ° C. or lower. The thermal expansion coefficient is 56 to 75 × 10 ⁻⁷ / ° C., which matches the thermal expansion coefficient of the glass substrate. Even if a dielectric layer is formed on the glass substrate, the glass substrate warps during firing. It was not something. Further, the dielectric constant was 5.3 or less and low. Furthermore, no phase separation was observed at all, or even if a phase separation was observed, the transmittance was very small and the transmittance was as high as 81% or more. Moreover, b * was +5.0 or less, and there was almost no yellowing by reaction with Ag electrode.

  In contrast, Sample No. as a comparative example. 19 and No. No. 21 had a large weight reduction rate (ΔW) of 1.14 or more, the weather resistance of the glass was low, phase-separated during firing, and the transmittance was as low as 51%. Sample No. No. 20 had a high dielectric constant of 6.6.

  In addition, about the weather resistance of glass, after wash | cleaning the obtained glass sample with water and drying for 30 minutes at 120 degreeC, the weight of the glass sample before a weather resistance evaluation was measured, and then the glass sample was 60 After immersing in pure water of 1 ° C. for 1 hour, drying at 120 ° C. for 30 minutes, and measuring the weight of the glass sample after the weather resistance evaluation, it was evaluated by determining the weight reduction rate (ΔW) of the glass sample. In addition, it shows that a weather resistance is so low that this value is large. In addition, when the weight reduction rate (ΔW) is greater than 1%, the glass tends to be altered by moisture in the atmosphere, and it becomes difficult to process into powdered glass, or the glass tends to separate during firing. Become.

  The softening point of the glass was measured using a macro differential thermal analyzer, and the value of the fourth inflection point was taken as the softening point.

Regarding the thermal expansion coefficient of glass, each glass powder sample was press-molded, baked at 600 ° C. for 10 minutes, polished into a cylindrical shape having a diameter of 4 mm and a length of 20 mm, and measured according to JIS R3102. A value in a temperature range of ˜300 ° C. was obtained. The glass substrate used in the plasma display panel has a thermal expansion coefficient of about 83 × 10 ⁻⁷ / ° C., and the dielectric material has a thermal expansion coefficient of 55 to 80 × 10 ⁻⁷ / ° C. It is easy to match the thermal expansion coefficient of the substrate, and even if a dielectric layer is formed on the glass substrate, the glass substrate is less likely to warp during firing.

  For the dielectric constant, each sample was powder press molded, fired at 600 ° C. for 10 minutes, polished to a 2 mm plate, measured according to JIS C2141, and values at 25 ° C. and 1 MHz were obtained.

  Regarding the presence or absence of phase separation, the surface of the glass film (dielectric layer) after firing was visually observed, and “◎” indicates that there was no white turbidity and no phase separation was observed. What was recognized was shown as “◯”, and white turbidity and clearly separated phases were shown as “x”.

  Regarding the transmittance, the diffuse transmittance at a wavelength of 550 nm was measured using a spectrophotometer equipped with an integrating sphere. In addition, the transmittance | permeability measurement was performed in Shimazu U-4000, and the value after canceling the value of a glass plate was shown. In addition, it shows that it is excellent in transparency, so that the value of the transmittance | permeability becomes large.

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

Claims (8)

B ₂ O ₃ a dielectric material for a plasma display panel of -SiO ₂ based glass powder, the glass powder is substantially free of PbO, in molar _{percentage, B 2 O 3 26~45%,} SiO ₂ 42 super _{~57%, Al 2 O 3 1~8} %, Na 2 O 0~10%, K 2 O 1~15%, Na 2 O + K 2 O 4~20%, 0~5% ZnO, CuO + MoO 3 A dielectric material for a plasma display panel, comprising: + CeO ₂ + MnO ₂ + CoO 0 to 6% glass. B ₂ O ₃ a dielectric material for a plasma display panel of -SiO ₂ based glass powder, the glass powder is substantially free of PbO, in molar _{percentage, B 2 O 3 26~45%,} SiO ₂ 42 super _{~57%, Al 2 O 3 1~8} %, Na 2 O 0~10%, K 2 O 1~15%, Na 2 O + K 2 O 5~20%, less than 0~1% ZnO, CuO + MoO _{2. The} dielectric material for a plasma display panel according to claim 1, comprising a glass containing ₃ + CeO ₂ + MnO ₂ + CoO 0 to 6%. B ₂ O ₃ a dielectric material for a plasma display panel of -SiO ₂ based glass powder, the glass powder is substantially free of PbO, in molar _{percentage, B 2 O 3 26~45%,} SiO ₂ 42 super _{~57%, Al 2 O 3 1~8} %, Na 2 O 0~3%, K 2 O 1~10%, Na 2 O + K 2 O 4~10%, 1~5% ZnO, CuO + MoO 3 The dielectric material for a plasma display panel according to claim 1, wherein the dielectric material is made of glass containing 0 to 6% of + CeO ₂ + MnO ₂ + CoO. Glass powder, in a molar _ratio, B ₂ O ₃ / dielectric material for a plasma display panel according to claim 1, characterized in that it consists of glass is SiO 2 from .55 to 0.80 . 5. The plasma display according to claim 1, wherein the glass powder is made of glass having a molar ratio of B ₂ O ₃ / (Na ₂ O + K ₂ O) of 3.3 to 7.2. Dielectric material for panels.   6. The dielectric material for a plasma display panel according to claim 1, wherein the dielectric material is used for forming a dielectric layer in contact with an Ag electrode formed on a glass substrate.   7. The dielectric material for a plasma display panel according to claim 1, wherein the dielectric material is used as a transparent dielectric material for a front glass substrate.   A glass plate for a plasma display panel, comprising a dielectric layer formed of the dielectric material according to claim 1.