JP2012134079A - Dielectric forming glass paste for plasma display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dielectric forming glass paste for a plasma display panel, capable of obtaining a dielectric layer low in dielectric constant, excellent in surface flatness and thin in film thickness, even when a paste including a cellulose resin and glass powder comprising BO-SiOlead-free glass is used.SOLUTION: A dielectric forming glass paste for a plasma display panel of the present invention includes glass powder, a thermoplastic resin and a solvent. In the dielectric forming glass paste, the glass powder comprises BO-SiOlead-free glass, the thermoplastic resin comprises a cellulose resin, and the solvent contains a glycol ether solvent.

Description

  The present invention relates to a dielectric-formed glass paste for a plasma display panel.

  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 addition, as a method of forming a dielectric layer on a glass substrate on which an electrode is formed, a paste-like dielectric prepared by kneading a powder component such as glass powder and a vehicle (a solution obtained by dissolving a thermoplastic resin in a solvent). A method in which a material is applied by a screen printing method, dried, and fired is widely used. In forming the dielectric layer on the glass substrate, the glass substrate is baked in a temperature range of about 500 to 600 ° C. in order to prevent deformation of the glass substrate and suppress deterioration of characteristics due to reaction with the electrode. 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 and high withstand voltage. Therefore, the dielectric material for forming the transparent dielectric layer is required to be easy to remove bubbles during firing, and the dielectric layer obtained by firing has a smooth surface and a film thickness. Is required to be uniform.

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 B ₂ O ₃ —SiO ₂ non-lead 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, the above-mentioned dielectric-formed glass paste for plasma display panel contains a thermoplastic resin in order to increase the film strength of a dry paste film obtained by applying and drying the dielectric-formed glass paste on a glass substrate. ing.

  Note that the thermoplastic resin contained in the dielectric-formed glass paste is inexpensive and can easily improve the coating properties and leveling properties of the coating film when applying the dielectric-formed glass paste. Usually, a cellulose resin is used.

  However, since the cellulose-based resin is made of a natural polymer material, the molecular weight and the molecular structure vary greatly, and the solubility in the solvent also changes greatly. Therefore, an undissolved gel-like cellulose resin may remain in the vehicle in which the cellulose resin is dissolved in a solvent. In addition, when using a dielectric-forming glass paste containing an undissolved material of a cellulose-based resin, a paste film is formed on a glass substrate, and this is fired to form a dielectric layer. Large portions may remain in the existing portions, or large depressions may be easily formed on the film surface during defoaming, and it may be difficult to obtain a dielectric layer having a smooth surface and a uniform film thickness.

In particular, in a plasma display, a low dielectric constant of a dielectric layer is required due to the recent trend of low power consumption. In order to reduce the dielectric constant of the dielectric layer, it has been studied to use a dielectric-forming glass paste containing glass powder made of B ₂ O ₃ —SiO ₂ non-lead glass having a low dielectric constant. Glass powder has a high viscosity in the baking temperature range of the paste dry film, so when firing the paste dry film, it is easy to enclose the release gas generated by the thermal decomposition of organic components such as thermoplastic resin in the film. It becomes a large bubble, and it is easy to form a large depression on the film surface during defoaming.

  Furthermore, if the dielectric constant of the dielectric layer is lowered, the thickness of the dielectric layer must be reduced in order to satisfy other dielectric characteristics such as capacitance, so that it does not affect the surface of the dielectric layer conventionally. Even such small bubbles are starting to affect the surface of the dielectric layer.

An object of the present invention is to provide a thin dielectric film having a low dielectric constant and excellent surface smoothness even when a paste containing a glass powder composed of a cellulose resin and B ₂ O ₃ —SiO ₂ non-lead glass is used. It is to provide a dielectric-formed glass paste for a plasma display panel that can obtain a layer.

As a result of conducting various experiments, the inventors have made a paste containing a cellulose resin or a glass powder made of B ₂ O ₃ —SiO ₂ non-lead glass by containing a glycol ether solvent as a solvent. Even if it is used, it is found and proposed that a thin dielectric layer having a low dielectric constant and excellent surface smoothness can be obtained.

That is, the dielectric-forming glass paste for a plasma display panel of the present invention is a dielectric-forming glass paste for a plasma display panel containing glass powder, a thermoplastic resin, and a solvent, and the glass powder is B ₂ O ₃ —SiO ₂ non-lead. It is made of glass, the thermoplastic resin is made of a cellulose resin, and the solvent contains a glycol ether solvent.

The dielectric-forming glass paste for plasma display panel of the present invention is a cellulosic resin that easily generates a gel-like undissolved material in a solvent, or B ₂ O ₃ − which has high glass viscosity in the baking temperature range of the paste dry film. Even when a paste containing glass powder made of SiO ₂ non-lead glass is used, a thin dielectric layer having a low dielectric constant and excellent surface smoothness can be formed. Therefore, it is suitable as a dielectric-forming glass paste for a plasma display panel.

The dielectric-formed glass paste for a plasma display panel of the present invention is a glass powder made of B ₂ O ₃ —SiO ₂ non-lead glass, which is relatively easy to obtain a low dielectric constant, and coatability when applying the paste. And a thermoplastic resin containing a cellulose resin capable of easily improving the leveling property of the coating film and a solvent as main components.

  In general, such a dielectric-forming glass paste is, as described above, an undissolved cellulose-based resin is likely to remain in the solvent, and the viscosity of the glass in the baking temperature range of the paste dry film is high. The released gas generated when the film is baked tends to remain as a large bubble and remain in the dielectric layer, or a large depression tends to be formed on the surface of the dielectric layer.

However, in the dielectric-forming glass paste for a plasma display panel of the present invention, a glycol ether solvent having an effect of suppressing the generation of undissolved cellulose-based resin used for the thermoplastic resin is contained in a part of the solvent. Yes. Therefore, even when a paste containing glass powder made of B ₂ O ₃ —SiO ₂ non-lead glass is used, generation of large bubbles during firing can be suppressed, the dielectric constant is low, and the film has excellent surface smoothness. A thin dielectric layer can be formed.

  As the glycol ether solvent used as a part of the solvent, it is preferable to use at least one glycol ether solvent selected from phenyl glycol, phenyl diglycol, phenylpropylene glycol, and benzyl glycol. . If these glycol ether solvents are used, other solvents used for adjusting the viscosity of the paste (specifically, terpineol, diethylene glycol monobutyl ether acetate, 2,2,4-trimethyl-1,3-pentadiol mono) It has good affinity with solvents that contain isobutyrate alone or in combination, and can suppress the formation of undissolved cellulose-based resin, so it suppresses the generation of large bubbles during firing and has excellent surface smoothness. A thin dielectric layer having a small thickness can be formed.

  The content ratio of the glycol ether solvent in the solvent is preferably in the range of 3 to 90% by mass ratio. If the content ratio of the glycol ether solvent in the solvent is too small, it is difficult to obtain the effect of suppressing the formation of undissolved cellulose resin, and large bubbles may remain in the dielectric layer during firing. It is easy to form a large depression on the surface, and it becomes difficult to obtain a dielectric layer having excellent surface smoothness. In addition, even if the content ratio of the glycol ether solvent in the solvent is too large, it is difficult to obtain the effect of suppressing the generation of undissolved cellulose resin, and large bubbles remain in the dielectric layer during firing, It is easy to form a large depression on the surface of the dielectric layer, and it becomes difficult to obtain a dielectric layer excellent in surface smoothness. Moreover, the drying property of the coating film formed on the glass substrate tends to be lowered, and the workability is likely to be lowered. A more preferable range of the content ratio of the glycol ether solvent in the solvent is 10 to 85% by mass ratio.

  Moreover, it is preferable to make content of the solvent in a paste into the range of 20-60 mass%. If the content of the solvent in the paste is too small, it will be difficult to obtain the effect of suppressing the formation of undissolved cellulose-based resin, and large bubbles may remain in the dielectric layer during firing, It may be difficult to obtain a dielectric layer that is easy to form a large depression and has excellent surface smoothness. In addition, since the glass powder content is increased, it is difficult to obtain a thin dielectric layer, or the content of the thermoplastic resin including the cellulose resin is increased, and the binder removal property is reduced during firing. Therefore, the dielectric layer is easily yellowed. On the other hand, if the content of the solvent in the paste is too high, the viscosity of the dielectric-forming glass paste becomes too low to obtain an appropriate viscosity for applying the dielectric-forming glass paste, and a coating film is formed. In this case, dripping or the like occurs, and the coating property of the dielectric-forming glass paste is remarkably lowered. A more preferable range of the solvent is 22 to 58% by mass, and a more preferable range is 24 to 56% by mass.

  The dielectric-formed glass paste for a plasma display panel of the present invention contains a thermoplastic resin and glass powder as main components in addition to the above-mentioned solvent. Hereinafter, each component will be described.

  The thermoplastic resin used in the present invention improves the coating property of the dielectric-forming glass paste by adjusting the viscosity of the dielectric-forming glass paste, and increases the strength of the paste dry film or imparts flexibility. It is a component for this, It is preferable to make the content into the range of 3-30 mass%. If the thermoplastic resin content in the paste is too low, the glass powder content will increase, making it difficult to obtain a thin dielectric layer or increasing the solvent content, resulting in a dielectric-forming glass paste. The applicability of the coating is significantly reduced. On the other hand, if the content of the thermoplastic resin is too large, the binder removal property tends to be reduced during firing. When Ag is used as the electrode, the Ag electrode is reduced and the dielectric layer is easily yellowed. Become. A more preferable range of the thermoplastic resin is 4 to 25% by mass, and a further preferable range is 5 to 20% by mass.

  In addition, as a thermoplastic resin, it is preferable to use what consists of at least 1 or more types of cellulose resin chosen from ethyl cellulose, hydroxyethyl cellulose, methylcellulose, and carboxymethylcellulose. Since these cellulose resins are easily dissolved in a glycol ether solvent, generation of large bubbles during firing can be suppressed, and a thin dielectric layer having excellent surface smoothness can be formed. In particular, when ethyl cellulose is used, it becomes easy to obtain a dielectric-forming glass paste having a viscosity suitable for intermittent application. Further, in order to improve the debinding property at the time of firing, a part of these cellulose-based resins may be replaced with an acrylic resin such as polybutyl methacrylate, polymethyl methacrylate, polyethyl methacrylate or the like. .

  The glass powder used in the present invention is a component for forming a dielectric layer having a low dielectric constant and a high withstand voltage, and the content thereof is preferably in the range of 15 to 60% by mass. If the glass powder content in the paste is too small, it is difficult to obtain a dielectric layer having a low dielectric constant and a high withstand voltage. On the other hand, when the content of the glass powder is excessive, it is difficult to obtain a thin dielectric layer. A more preferable range of the glass powder is 17 to 57% by mass, and a further preferable range is 20 to 55% by mass.

The glass powder used in the present invention has a basic composition of B ₂ O ₃ —SiO ₂ non-lead glass. The reason is that it is possible to lower the dielectric constant and the melting point of the glass relatively easily, and it is easy to obtain a thermal expansion coefficient suitable for the glass substrate.

Further, among the B ₂ O ₃ —SiO ₂ non-lead glass, the glass powder is particularly B ₂ O ₃ 26 to 45%, SiO ₂ more than 42 to 57%, Al ₂ O ₃ 1 to 6%, Na _2. A glass having a composition range of O 0 to 10%, K ₂ O 1 to 15%, Na ₂ O + K ₂ O 4 to 20%, ZnO 0 to 7%, CuO + MoO ₃ + CeO ₂ + MnO ₂ + CoO 0 to 6% is used. It is preferable. If the glass is in such a composition range, the vitrification range is wide and stable, the softening point of the glass is low, the dielectric constant of the glass powder at 25 ° C. and 1 MHz tends to be 6.0 or less, and the low dielectric constant is low. It becomes easy to obtain the dielectric layer which has.

  In the present invention, the reason why the glass composition of the glass powder is limited as described above is as follows.

B ₂ O ₃ is a component that forms a glass skeleton, and its content is preferably 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 viscosity of the glass in the baking temperature range tends to be high, large bubbles remain in the dielectric layer, or depressions are formed on the surface of the dielectric layer, resulting in a thin dielectric layer with excellent surface smoothness. It becomes difficult to obtain. Furthermore, the weather resistance of the glass is lowered, the glass is denatured, and it becomes 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 more preferable range of B ₂ O ₃ is 29 to 40%, and a further 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 preferably more than 42 to 57%. When the content of SiO ₂ decreases, the dielectric constant of the glass tends to increase remarkably. 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. In addition, the viscosity of the glass in the baking temperature range tends to be high, large bubbles remain in the dielectric layer, or depressions are formed on the surface of the dielectric layer, resulting in a thin dielectric layer with excellent surface smoothness. It becomes difficult to obtain. Furthermore, the thermal expansion coefficient of the glass becomes too small, and the glass substrate is likely to warp during firing. A more preferable range of SiO ₂ is 42.5 to 56%, and a further 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 it becomes difficult to obtain a glass substrate having high strength. 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 preferably 1 to 6%. 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. A more preferable range of Al ₂ O ₃ is 1.1 to 5.9%, and a more preferable range is 1.2 to 5.4%.

Na ₂ O is a component that lowers the viscosity of the glass at the softening point and the firing temperature range of the glass or adjusts the thermal expansion coefficient, and its content is preferably 0 to 10%. When the content of Na ₂ O increases, when Ag is used for the electrode, the dielectric material reacts with Ag, and the dielectric layer is likely to turn yellow (yellowing), resulting in a problem that the image is difficult to see. . In addition, the thermal expansion coefficient tends to be too large, 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 more 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 viscosity of the glass in the softening point and the firing temperature range of the glass or adjusts the thermal expansion coefficient, and its content is preferably 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 too large, and it becomes difficult to match the thermal expansion coefficient of the glass substrate. A more 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 too large, 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 more preferable range of the total amount of these components is 4 to 18%, and a further 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 %.

In addition, 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. It is preferable to contain up to 6%. When the total amount of these components increases, the dielectric layer is likely to be colored by these components. A more 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 viscosity of the glass in the softening point and firing temperature range of the glass and stabilizes the glass, but also a component that remarkably increases the dielectric constant of the glass, and its content is 0 to 7%. It is preferable. When the ZnO 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. It is preferable to make it 1 to 7%, More preferably, it is 1 to 6%, More preferably, it is 2 to 6%.

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.

Incidentally, Bi ₂ O ₃ are the components to reduce the viscosity of the glass at the softening point and the firing temperature range of the glass, by containing Bi ₂ O _3, by reducing the content of alkali metal oxide component , Yellowing of the dielectric layer due to reaction with Ag can be made 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 viscosity of the glass at the softening point and firing temperature range 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. .

Further, the particle size of the glass powder used in the plasma display panel for dielectric formation glass paste of the present invention has an average particle diameter D ₅₀ of 3.0μm or less, the maximum particle diameter D _max may be desirable to use those 20μm 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.

  Moreover, a plasticizer, an inorganic filler powder, etc. can also be added as needed other than the said component.

  The plasticizer is a component that controls the drying speed of the coated film and imparts flexibility to the dried film, and can be added up to 10% by mass. However, when the content of the plasticizer is increased, the debinding property is remarkably lowered, and bubbles are likely to remain in the fired film. Therefore, it is particularly preferably in the range of 0 to 5% 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 inorganic filler powder is a component that adjusts the fluidity, sinterability, or thermal expansion coefficient of the paste, and can be added up to 40% by mass. However, if the content of the inorganic filler powder is increased, sintering cannot be performed sufficiently and it becomes difficult to form a dense film, and therefore it is particularly preferably in the range of 0 to 30% by mass. As the inorganic filler 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 transparency of the dielectric layer due to the introduction of the inorganic filler powder, a part or all of the inorganic filler 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. Further, it is desirable to use inorganic filler powder having an average particle size of 5.0 μm or less and a maximum particle size of 20 μm or less.

  The dielectric-formed glass paste 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. Also, as a material of 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 is not in direct contact with the electrode It is possible to use. Of course, it can also be used in a dielectric material formed on an electrode other than Ag, and 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 inorganic filler powder into 0-30 mass% (preferably 0-25 mass%). By setting the content of the inorganic filler 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 inorganic filler powder. When used as an address electrode protective dielectric material or a partition material, the inorganic filler powder is contained in the range of 0 to 40% by mass (more preferably 5 to 38% by mass, and still more preferably 10 to 35% by mass). You can use it. By setting the content of the inorganic filler powder in this way, a fired film having high strength or excellent acid resistance can be obtained.

  Next, a method for producing the dielectric-formed glass paste of the present invention will be described.

  First, glass powder, a thermoplastic resin, a solvent, etc. are prepared. It is important that the glass powder is pulverized using a ball mill, jet mill, bead mill, etc., and further classified by airflow classification or the like so as to have a predetermined particle size distribution. Subsequently, the dielectric-forming glass paste of the present invention can be obtained by kneading each component at a predetermined ratio.

  Next, a method for forming a dielectric layer using the dielectric-formed glass paste of the present invention will be described.

  First, a back glass substrate on which electrodes are formed is prepared, and the dielectric-formed glass paste of the present invention is applied onto the glass substrate by a screen printing method, a batch coating method, or the like, and a predetermined film thickness (transparent dielectric) After forming a coating layer of 50 to 100 μm in the case of a body layer and 30 to 50 μm in the case of an address protection dielectric 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 a dielectric layer having two or more dielectric structures is formed, a lower layer dielectric forming paste is formed on a glass substrate on which electrodes have been formed in advance by a screen printing method, a batch coating method, or the like. It is applied to ˜80 μm, dried, and then fired in the same manner as described above. Subsequently, an upper layer dielectric forming paste is applied to a film thickness of about 60 to 160 μm by screen printing, a batch coating method, or the like, and dried. Then, it can obtain by baking similarly to the above.

  In forming the dielectric layer having two or more dielectric structures, when the upper dielectric layer is formed, if the upper dielectric material is fired at a temperature range of ± 20 ° C. for firing the lower dielectric layer, 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. 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.

  As described above, when the dielectric-formed glass paste of the present invention is applied on the glass substrate on which the electrode is formed, and baked to form a dielectric layer, when Ag is used for the electrode, 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.

  Hereinafter, the dielectric-formed glass paste 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 No. 19) of the present invention.

  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, after putting in a platinum crucible and melting at 1300 ° C. for 2 hours, the molten glass 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. Each glass powder sample thus obtained was evaluated for softening point, thermal expansion coefficient and dielectric constant. The evaluation results are shown in the table.

  Next, a glass sample, a thermoplastic resin, and a solvent were mixed at a ratio shown in the table, and kneaded uniformly with a three-roll mill to obtain a paste sample. For each paste sample thus obtained, the amount of undissolved material in the paste was measured. The evaluation results are shown in the table.

  Next, using the paste prepared above, it was applied with a coater so as to obtain a 20 μm fired film on a glass substrate, dried, held in an electric furnace at 600 ° C. for 10 minutes, and fired to obtain a dielectric layer. A glass substrate sample on which was formed was obtained. With respect to each sample thus obtained, the presence or absence of large bubbles in the dielectric layer, the height difference on the surface of the dielectric layer, and the transmittance were evaluated. The evaluation results are shown in the table.

  Further, using the paste prepared above, a dielectric layer was formed on the glass substrate on which the Ag electrode was formed in the same manner as described above, and the degree of yellowing was evaluated. The evaluation results are shown in the table.

  In addition, as the glycol ether solvent, the following a to d were used.

a: phenyl glycol b: phenyl diglycol c: phenylpropylene glycol d: benzyl glycol Further, terpineol is used as a solvent other than the glycol ether solvent, ethyl cellulose is used as a thermoplastic resin, and dibutyl phthalate is used as a plasticizer. It was.

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

As can be seen from the table, the sample No. Nos. 1 to 18 had a small number of undissolved cellulose resin in the paste of 3 or less. In addition, the dielectric layer formed using these pastes had no large bubbles remaining in the dielectric layer, and the surface height difference was as small as 2 μm or less, and was excellent in surface smoothness. . Furthermore, the transmittance of the dielectric layer was as high as 80% or more, b * was +4.9 or less, and yellowing due to reaction with the Ag electrode was hardly observed. The glass has a softening point of 603 ° C. or lower, and can 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. It was a thing. The dielectric constant was as low as 5.3 or less.

  In contrast, Sample No. as a comparative example. In No. 19, the number of undissolved cellulose resin in the paste was as large as seven. Further, the dielectric layer formed using this paste had large bubbles remaining in the dielectric layer, the surface height difference was as large as 6 μm, and the surface smoothness was inferior. Further, the transmittance of the dielectric layer was as low as 78%.

  These facts indicate that when the dielectric-formed glass paste of the present invention is used, a thin dielectric layer having a low dielectric constant, almost no large bubbles remaining, and excellent transparency and surface smoothness can be obtained. Shows that you can.

  In addition, about the softening point of glass, it measured using the macro-type differential thermal analyzer, and made the softening point the value of the 4th inflection point. In addition, the temperature increase rate was measured on the conditions of 10 degree-C / min.

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. In addition, if the thermal expansion coefficient of the glass substrate used for the plasma display panel is about 83 × 10 ⁻⁷ / ° C. and the thermal expansion coefficient of the dielectric material is 55 to 83 × 10 ⁻⁷ / ° C., glass Even if a dielectric layer is formed on the glass substrate in conformity with the thermal expansion coefficient of the substrate, the glass substrate is hardly warped 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 amount of undissolved material in the paste, each paste sample was filtered using a standard sieve of 635 mesh (opening 20 μm), and the number of undissolved gel-like cellulose resin remaining on the screen (per liter) ) Was measured.

  The presence or absence of large bubbles in the dielectric layer was evaluated by observing the dielectric layer with a stereomicroscope and confirming the presence or absence of bubbles of 15 μm or more in the dielectric layer.

  Regarding the height difference of the dielectric layer surface, the surface of the glass substrate on which the dielectric layer was formed was measured using a laser displacement meter. In addition, it shows that the surface smoothness of a dielectric material layer is inferior, so that this value becomes large.

  The transmittance is evaluated by measuring the linear transmittance at a wavelength of 550 nm of a glass substrate sample having a dielectric layer formed on a glass substrate and a single glass substrate with a spectrophotometer, and canceling the linear transmittance of the glass substrate. did.

  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)

In the dielectric-forming glass paste for a plasma display panel containing glass powder, a thermoplastic resin and a solvent, the glass powder is made of B ₂ O ₃ —SiO ₂ non-lead glass, the thermoplastic resin is made of a cellulose resin, and A dielectric-forming glass paste for a plasma display panel, wherein the solvent contains a glycol ether solvent.   2. The dielectric formation for a plasma display panel according to claim 1, wherein the solvent comprises at least one glycol ether solvent selected from phenyl glycol, phenyl diglycol, phenylpropylene glycol, and benzyl glycol. Glass paste.   The dielectric formation for a plasma display panel according to claim 1 or 2, wherein the thermoplastic resin comprises at least one cellulose-based resin selected from ethyl cellulose, hydroxyethyl cellulose, methyl cellulose, and carboxymethyl cellulose. Glass paste. Glass powder, substantially free of PbO, in molar _{percentage, B 2 O 3 26~45%,} SiO 2 42 super _{~57%, Al 2 O 3 1~6} %, Na 2 O 0~10%, _{K 2 O 1~15%, Na 2} O + K 2 O 4~20%, ZnO 0~7%, claims 1 to 3, comprising the _{CuO + MoO 3 + CeO 2 +} MnO 2 + CoO 0~6% content to glass A dielectric-forming glass paste for a plasma display panel according to any one of the above.   5. The dielectric-forming glass paste for a plasma display panel according to claim 1, wherein the dielectric constant of the glass powder at 25 ° C. and 1 MHz is 6.0 or less.   In percentage by mass, the glass powder is 15-60%, the inorganic filler powder is 0-40%, the thermoplastic resin is 3-30%, the solvent is 20-60%, and the plasticizer is 0-10%. The dielectric-forming glass paste for a plasma display panel according to any one of claims 1 to 5.   The dielectric-forming glass paste for a plasma display panel according to any one of claims 1 to 6, which is used for forming a dielectric layer in contact with an Ag electrode formed on a glass substrate.   The dielectric-forming glass paste for a plasma display panel according to any one of claims 1 to 7, which is used as a transparent dielectric-forming material for a front glass substrate.